WO2024107731A2

WO2024107731A2 - Anti-pd-l1 antibodies

Info

Publication number: WO2024107731A2
Application number: PCT/US2023/079644
Authority: WO
Inventors: Godfrey Jonah Rainey; Jane SEAGAL; Manankumar SHAH
Original assignee: Ablexis, Llc
Priority date: 2022-11-14
Filing date: 2023-11-14
Publication date: 2024-05-23
Also published as: WO2024107731A3

Abstract

Anti-PD-L1 antibodies and antigen-binding fragments thereof and related compositions useful in any of a variety of therapeutic and diagnostic methods for the treatment of diseases and disorders, such as cancer and chronic viral infections.

Description

Agent Ref.: 000118-0020-WO1 ANTI-PD-L1 ANTIBODIES RELATED APPLICATIONS [0001] This application claims priority to and benefit of United States Provisional Application No. 63/425,299, filed November 14, 2022, which is incorporated herein by 5 reference in its entirety. FIELD OF THE DISCLOSURE [0002] The present disclosure relates generally to anti-PD-L1 antibodies, compositions and methods of using same. Such antibodies are useful, for example, for enhancing T-cell activation, e.g., as treatments for cancer or chronic viral infection. Such antibodies may also 10 be useful, for example, as arms in bispecific antibodies or other multi-specific antibodies. BACKGROUND OF THE DISCLOSURE [0003] Programmed death ligand 1 (PD-L1), also known as cluster of differentiation 274 (CD274) or B7 homolog 1 (B7-H1), is a 40 kDa type 1 transmembrane protein and is the 15 principal ligand of programmed death 1 (PD-1), a receptor found on, e.g., activated T cells and B-cells. Under normal physiological conditions, the interaction of PD-L1 and its receptor PD- 1 is essential for the development of immune tolerance and for preventing the development of autoimmunity. The interaction of PD-L1 to PD-1 has been demonstrated to play a major role in suppressing the activation of the adaptive immune system, wherein the binding of PD-L1 to 20 its receptor (PD-1) is associated with an inhibitory signal that reduces the proliferation of CD8+ T-cells. PD-1 inhibits T-cell signaling leading to activation and proliferation through multiple pathways primarily by the actions of Src homology 2 domain-containing protein tyrosine phosphatases 1 and 2 (SHP-1 and 2). SHP-1 and SHP-2 associate with the immunoreceptor tyrosine switch motif (ITSM) and/or the immunoreceptor tyrosine inhibitory motif (ITIM) of 25 PD-1 and directly or indirectly act upon CD3ζ, Zeta-chain-associated protein kinase 70 (ZAP70), vav, Akt, and extracellular signal-regulated kinase (ERK). These interactions result in the downregulation of multiple pathways in T cells leading to downregulation of hallmark cytokines from downstream signaling events. A key example of this activity is Protein kinase C theta (PKC-θ) activation loop phosphorylation, necessary for the activation of transcription 30 factors for the production of interleukin-2 (IL-2). [0004] Under pathological conditions, malignancies, such as cancer, can exploit the role of PD-L1 to evade the immune system. Specifically, malignant cells can overexpress PD- L1 to evade the subject’s immune response and reduce T-cell proliferation. Accordingly, the interaction between PD-L1 and PD-1 has become a target for anti-cancer therapies. Several PD-L1 blocking antibodies have shown clinical activity in multiple cancers known to overexpress PD-L1. Specifically anti-PD-L1 antibodies, such as Atezolizumab, have been used to treat urothelial carcinoma, non-small cell lung cancer (NSCLC), triple-negative breast cancer (TNBC), small cell lung cancer (SCLC), and hepatocellular carcinoma (HCC) (See, e.g. Tie Y, et al. Drug Des Devel Ther.2019 Feb.). Because of its role in T-cell activation, anti- PD-L1 antibodies have also been used to treat chronic viral infections. [0005] Because of the complexities of malignancies, such as cancer, bispecific antibodies have become an attractive approach for dual targeting to generate biological activities normally not possible through monospecific antibodies or drug combinations. And, although there are several PD-L1 monospecific antibodies approved for clinical use, many PD- L1 bispecific antibodies have only recently started clinical testing. Further, even the monospecific PD-L1 antibodies approved for treating, e.g. cancer, carry significant side effects. For example, Atezolizumab is commonly associated with fatigue, rash, and gastrointestinal symptoms and, more rarely, with encephalitis and encephalopathy (See, e.g., Laserna A et al. SAGE Open Medical Case Reports. 2018;6). Accordingly, there remains a need to identify additional anti-PD-L1 binding antibodies and bispecific and multi-specific antibodies containing them, e.g., antibodies having improved efficacy or better safety profiles in patients. SUMMARY OF THE DISCLOSURE [0006] The present disclosure relates to antibodies or antigen-binding fragments thereof that bind PD-L1. More specifically, it relates to chimeric anti-PD-L1 antibodies, and antigen-binding fragments thereof, in some embodiments generated from an AlivaMab® Mouse (Ablexis LLC), as well as fully human anti-PD-L1 antibodies, bispecific and multi- specific antibodies characterized by one arm being selected from those chimeric or fully human antibodies,, compositions comprising such chimeric, human and bispecific or multi-specific antibodies; polynucleotides, vectors and host cells producing such chimeric, human and bispecific or multi-specific antibodies; and methods of making and using such chimeric, human, and bispecific or multi-specific antibodies. [0007] One aspect of the disclosure provides an isolated anti-PD-L1 antibody, or an antigen-binding fragment thereof, comprising one to six of the complementarity determining regions (CDRs) comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 1-642. [0008] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises a heavy chain CDR3 (HCDR3) comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 536-642. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises a light chain CDR3 (LCDR3) comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 215-321. [0009] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises i) a heavy chain variable region comprising a HCDR1 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 322- 428, a HCDR2 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 429-535, and a HCDR3 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 536-642 of an antibody and ii) a light chain variable region comprising the LCDR1 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs:1-107, the LCDR2 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 108-214, and the LCDR3 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 215-321 of the same antibody. [0010] In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the heavy chain variable (“VH”) region of an antibody comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 857-1070. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the light chain variable (“VL”) region of an antibody comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 643-856. In some embodiments of this disclosure, the antibody, or antigen-binding fragment thereof, comprises the VH and VL regions selected respectively from the group consisting of SEQ ID NOs: 857-1070 or from the group consisting of SEQ ID NOs: 643-856. [0011] In some embodiments of this disclosure, the CDRs, VH, and/or VL regions are from an antibody selected from the group consisting of ABL-PD-L1-1 to ABL-PD-L1-107 and ABL-PD-L1-1A to ABL-PD-L1-107A. In some embodiments, the CDRs, VH, and/or VL regions are from an antibody selected from the group consisting of ABL-PD-L1-1, ABL-PD- L1-40, ABL-PD-L1-49, ABL-PD-L1-6, ABL-PD-L1-29, ABL-PD-L1-14, ABL-PD-L1-8, ABL-PD-L1-47, ABL-PD-L1-23, ABL-PD-L1-9, ABL-PD-L1-15, ABL-PD-L1-11, ABL-PD- L1-13, ABL-PD-L1-17, ABL-PD-L1-4, ABL-PD-L1-19, ABL-PD-L1-1A, ABL-PD-L1-40A, ABL-PD-L1-49A, ABL-PD-L1-6A, ABL-PD-L1-29A, ABL-PD-L1-14A, ABL-PD-L1-8A, ABL-PD-L1-47A, ABL-PD-L1-23A, ABL-PD-L1-9A, ABL-PD-L1-15A, ABL-PD-L1-11A, ABL-PD-L1-13A, ABL-PD-L1-17A, ABL-PD-L1-4A, and ABL-PD-L1-19A. [0012] In some embodiments of this disclosure, the HCDR1 of the antibody or antigen- binding fragment thereof comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 322-428. In some embodiments of this disclosure, the HCDR2 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 429-535. In some embodiments of this disclosure, the HCDR3 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 536-642. In some embodiments of this disclosure, the LCDR1of the antibody or antigen-binding fragment thereof comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 1-107. In some embodiments of this disclosure, the LCDR2 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 108-214. In some embodiments of this disclosure, the LCDR3 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 215-321. In some embodiments of this disclosure, the VH region of the antibody or antigen-binding fragment thereof comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 857-1070. In some embodiments of this disclosure, the VL region of the antibody or antigen- binding fragment thereof comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 643-856. [0013] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, is a fully human antibody or antigen-binding fragment thereof. In some embodiments, the antibody or antigen-binding fragment thereof is chimeric. In some embodiments, the antibody is selected from a single-variable domain antibody, a single chain antibody, a scFv, a bispecific antibody, a multi-specific antibody, a Fab, a F(ab')2, and a whole antibody. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, is a bispecific antibody or antigen binding fragment thereof. [0014] In some embodiments of this disclosure, the anti-PD-L1 antibody is an IgG antibody. In some embodiments of this disclosure, the anti-PD-L1 antibody is an IgM antibody. In some embodiments, the anti-PD-L1 antibody is an IgA antibody. In some embodiments of this disclosure, the anti-PD-L1 antibody is an IgD antibody. In some embodiments of this disclosure, he anti-PD-L1 antibody is an IgE antibody. In some embodiments, the anti-PD-L1 antibody is an IgG1 antibody. In some embodiments of this disclosure, the anti-PD-L1 antibody is an IgG2 antibody. In some embodiments, the anti-PD- L1 antibody is an IgG3 antibody. In some embodiments of this disclosure, the anti-PD-L1 is an IgG4 antibody. In some embodiments, the anti-PD-L1 antibody is a variant of an IgG antibody, such as a variant of an IgG1, an IgG2, an IgG3, an IgG4, or combinations thereof. In some embodiments of this disclosure, the anti-PD-L1 antibody may have reduced effector function or no effector function. In some embodiments, the anti-PD-L1 antibody is engineered to reduce or eliminate effector function. [0015] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises a complete heavy chain, a first Fc domain, and a complete light chain. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises a single-chain Fv (scFv), Fab, Fab’, F(ab’)2 or an Fv fragment operably linked to a first Fc domain. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises a single-chain Fv (scFv) operably linked to a first Fc domain. [0016] In some embodiments, the anti-PD-L1 bispecific antibody comprises an anti- PD-L1 fragment operably linked to the heavy chain of the second or targeting antibody. In some embodiments, the anti-PD-L1 fragment is operably linked to the N-terminus of the heavy chain of the second or targeting antibody. In such embodiments, the heavy chain of the targeting antibody may comprise, from N-terminus to C-terminus, the anti-PD-L1 fragment, the VH of the second or targeting antibody, and a Fc region. In some embodiments, the heavy chain of the second or targeting antibody from N-terminus to C terminus comprises the anti- PD-L1 fragment, the VH of the targeting antibody and a constant region. In some embodiments, the anti-PD-L1 antibody is operably linked to the C-terminus of the heavy chain of the second or targeting antibody. In such embodiments, the heavy chain of the targeting antibody may comprise, from N-terminus to C-terminus, the VH of the second or targeting antibody, a Fc region, and the anti-PD-L1 fragment. In some embodiments, the heavy chain of the second or targeting antibody comprises, from N-terminus to C-terminus, the VH of the second or targeting antibody, a constant region, and the anti-PD-L1 fragment. In some embodiments, the PD-L1 fragment is an scFv fragment. [0017] In some embodiments of this disclosure, the anti-PD-L1 bispecific antibody, or antigen-binding fragment thereof, comprises an scFv linked to a heavy chain sequence via a linker. In some embodiments, the linker is a variable length Gly-Ser linker. In some embodiments, the linker is selected from the group consisting of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO:1112), (Ser-Ser-Ser-Ser-Gly)n (SEQ ID NO: 1104), (Gly-Ser-Ser-Gly-Gly)n (SEQ ID NO: 1105), and (Gly-Gly-Ser-Gly-Gly)n (SEQ ID NO: 1106), where n is an integer between 1 and 5. In some embodiments, the linker comprises the amino acid sequence of (Gly-Gly-Gly- Gly-Ser)n (SEQ ID NO: 1111), wherein n is 1. In some embodiments, the linker comprises the amino acid sequence (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4. [0018] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises a first Fc domain. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, is operably linked to the first Fc domain via a first linker. In some embodiments, the first linker is an antibody hinge region. In some embodiments, the first linker is a variable length Gly-Ser linker. In some embodiments, the first linker comprises a linker selected from the group consisting of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1112), (Ser-Ser-Ser-Ser-Gly)n (SEQ ID NO: 1104), (Gly-Ser-Ser-Gly-Gly)n (SEQ ID NO: 1105), and (Gly-Gly-Ser-Gly-Gly)n (SEQ ID NO: 1106), where n is an integer between 1 and 5. In some embodiments, the first linker comprises the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1111), wherein n is 1. [0019] In other embodiments, the disclosure provides an anti-PD-L1 bispecific antibody or an antigen-binding fragment thereof. In some embodiments, the anti-PD-L1 bispecific antibody further comprises a second antibody, or an antigen-binding fragment thereof. In some embodiments, the anti-PD-L1 bispecific antibody further comprises a targeting antibody, or an antigen-binding fragment thereof. In some embodiments, the targeting antibody is an immune cell targeting antibody, or an antigen-binding fragment thereof. In some embodiments, the targeting antibody is a cancer or virally infected cell targeting antibody or an antibody that binds relevant cells for targeting these tissues, or an antigen-binding fragment thereof. In some embodiments, the second binding specificity does not provide targeting activity, but instead provides a complementary or redundant functional activity. In some embodiments, the second antibody, the anti-immune cell, cancer or virally infected cell targeting antibody, or antigen-binding fragment thereof, comprises a second Fc domain. In some embodiments, the second antibody, the anti-immune cell, cancer or virally infected cell targeting antibody, or antigen-binding fragment thereof, is operably linked to a second Fc domain via a second linker. In some embodiments, the second linker is an antibody hinge region. In some embodiments, the second linker is a variable length Gly-Ser linker. In some embodiments, the second linker comprises a linker selected from the group consisting of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1112), (Ser-Ser-Ser-Ser-Gly)n (SEQ ID NO: 1104), (Gly-Ser-Ser-Gly-Gly)n (SEQ ID NO: 1105), and (Gly-Gly-Ser-Gly-Gly)n (SEQ ID NO: 1106), where n is an integer between 1 and 5. In some embodiments, the second linker comprises the amino acid sequence (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1111), wherein n is 1. [0020] In some embodiments of this disclosure, the first and second Fc domains comprise mutations to promote heterodimer formation. In some embodiments, the first and second Fc domains comprise knob-into-hole (KIH) mutations. In some embodiments, the first Fc domain comprises a T366W mutation and the second Fc domain comprises T366S/L368A/Y407V mutations. In some embodiments, the first Fc domain comprises T366S/L368A/Y407V mutations and the second Fc domain comprises a T366W mutation. In some embodiments, the first and second Fc domains comprise KIH_S-S mutations. In some embodiments, the first Fc domain comprises S354C/T366W mutations and the second Fc domain comprises Y349C/T366S/L368A/Y407V mutations. In some embodiments, the first Fc domain comprises Y349C/T366S/L368A/Y407V mutations and the second Fc domain comprises S354C/T366W mutations. In some embodiments, the first Fc domain comprises S354C/T366W mutations and the second Fc domain comprises Y349C/T366S/L368A/Y407V/H435R/Y436F mutations. In some embodiments, the first Fc domain comprises Y349C/T366S/L368A/ Y407V/H435R/Y436F mutations and the second Fc domain comprises S354C/T366W mutations. In some embodiments, the first Fc domain comprises S354C/T366W/H435R/Y436F mutations and the second Fc domain comprises Y349C/T366S/L368A/Y407V mutations. In some embodiments, the first Fc domain comprises Y349C/T366S/L368A/Y407V mutations and the second Fc domain comprises S354C/T366W/H435R/Y436F mutations. Each of the foregoing mutations is according to EU numbering. [0021] One aspect of the disclosure provides a polynucleotide encoding the anti-PD- L1 antibody, or antigen-binding fragment thereof. Another aspect of the disclosure provides a polynucleotide encoding anti-PD-L1 antibodies, or antigen-binding fragment thereof, or an anti-PD-L1 multi-specific antibody or antigen binding fragment thereof. Another aspect of the disclosure provides a vector, such as an expression vector, comprising the polynucleotide. Another aspect of the disclosure provides an isolated host cell that comprises the polynucleotide or the vector containing it. An additional aspect of the disclosure provides a method for producing the anti-PD-L1 antibody, or antigen-binding fragment thereof. Another aspect of the disclosure provides a composition comprising an anti-PD-L1 antibody, or antigen- binding fragment thereof and a physiologically acceptable carrier. [0022] A further aspect of the disclosure provides methods of, or methods of preparing a medicament for, or using an antibody or fragment of this disclosure in, treating or preventing cancer in a subject in need thereof by administering an anti-PD-L1 antibody, or antigen-binding fragment thereof, or bispecific or multi-specific antibody of the disclosure or a composition comprising the antibody or fragment to a subject in need thereof. One aspect of the disclosure provides a method of maintaining cancer remission in a subject by administering an anti-PD- L1 antibody, or antigen-binding fragment thereof, or bispecific or multi-specific antibody of the disclosure or a composition comprising the antibody or fragment to a subject in need thereof. An additional aspect of the disclosure provides a method of enhancing T-cell activation. In some embodiments, the anti-PD-L1 bispecific antibody further comprises a second antibody, or an antigen-binding fragment thereof. In some embodiments of the disclosure, the bispecific or multi-specific antibody or fragment further comprises an immune cell targeting arm. In some embodiments, the targeting antibody is a cancer or virally infected cell targeting antibody or an antibody that binds relevant cells for targeting these tissues, or an antigen-binding fragment thereof. In some embodiments, the second binding specificity does not provide targeting activity, but instead provides a complementary or redundant functional activity. A further aspect of the disclosure provides a method of treating cancer by administering an anti-PD-L1 bispecific or multi-specific antibody, or antigen-binding fragment thereof, of the disclosure or a composition comprising the antibody or fragment to a subject in need thereof, wherein the bispecific or multi-specific antibody or fragment further comprises a second antibody, an immune cell targeting arm, or a or cancer or virally infected cell targeting antibody. [0023] Another aspect of the disclosure provides methods of preparing a medicament for, or using the antibodies and fragments of this disclosure in, treating or preventing a chronic viral infection or disorder in a subject in need thereof by administering an anti-PD-L1 antibody, or antigen-binding fragment thereof or bispecific or multi-specific antibody of the disclosure or a composition comprising the antibody or fragment to a subject in need thereof. BRIEF DESCRIPTION OF THE FIGURES [0024] Figures 1A and 1B provide results of a binding enzyme-linked immunosorbent assay (ELISA) to identify anti-human PD-L1 specific antibodies and a blocking ELISA to identify antibodies that also block PD-L1 to PD-1 interaction, respectively. [0025] Figure 2 provides a schematic of an anti PD-L1/Lag3 bispecific antibody. [0026] Figure 3A provides the results of an ELISA employed to measure polyspecific/nonspecific antibody binding to ds DNA and ss DNA, cardiolipin, insulin, lipopolysaccharide, and Hemocyanin. Figure 3B provides the results of an ELISA employed to measure polyspecific/nonspecific antibody binding Baculovirus Particles. Figure 3C provides results of the retention time of the antibody measured on a HIC-butyl column with less hydrophobic species eluting earlier and more hydrophobic species eluting later. BRIEF DESCRIPTION OF THE SEQUENCES Table 1A. Anti-PD-L1 Antibody Amino Acid Sequence Identifiers

Table 1B. Anti-PD-L1 Antibody LCDR Sequences

Table 1C. Anti-PD-L1 Antibody HCDR Sequences

Table 1D. Anti-PD-L1 Antibody VL Sequences

Table 1E. Anti-PD-L1 Antibody VH Sequences

Table 1F. scFv Sequences

DETAILED DESCRIPTION [0027] The present disclosure relates to anti-PD-L1 antibodies and antigen-binding fragments thereof in the form of mono-specific, bispecific and multi-specific antibodies. In some embodiments of this disclosure, these antibodies were produced using the proprietary AlivaMab® Mouse technology (See WO 2010/039900 and WO 2011/123708, incorporated by reference herein in their entirety). However, other methods could also be used. The antibodies and their fragments associated with ABL-PD-L1-1 to ABL-PD-L1-50 are cross reactive with human and cynomolgus. [0028] Embodiments of the disclosure pertain to the use of these anti-PD-L1 antibodies, or antigen-binding fragments thereof, for the diagnosis, assessment and treatment of cancer and chronic viral infections. [0029] Portions of variable regions of the antibodies or fragments thereof of this disclosure may include all or a combination of the complementarity determining regions (CDRs) of the VH and/or VL chains (see, SEQ ID NO: 1-1070). The variable regions may also be formatted with constant regions, either native or modified for either up-regulation or down-regulation of various effector functions, in a standard antibody structure (two heavy chains and two light chains). The variable regions may also be formatted as multi-specific antibodies, e.g., bispecific antibodies binding to two different epitopes of PD-L1 or to two different antigens, one of which is PD-L1. In some embodiments, the anti-PD-L1 bispecific antibody further comprises a second antibody, or an antigen-binding fragment thereof. In some embodiments of this disclosure, the antibody or antigen-binding fragment thereof is a bispecific antibody. In some embodiments, the bispecific antibody comprises an immune cell targeting arm. In some embodiments, the targeting antibody is a cancer or virally infected cell targeting antibody or an antibody that binds relevant cells for targeting these tissues, or an antigen- binding fragment thereof. In some embodiments, the second binding specificity does not provide targeting activity, but instead provides a complementary or redundant functional activity. The variable regions may also be formatted as antibody fragments, e.g., single-domain antibodies comprising a single VH or VL, Fab, Fab’2, scFv, or chimeric antigen receptor (CAR). The antibodies may also be used in antibody-drug conjugates or carry other additions, such as small molecule toxins, or included as a part of, biologic toxins, cytokines, radioisotopes, RNAs, or CAR-T cells to increase therapeutic modality and/or to increase safety. [0030] The practice of the present disclosure will employ, unless indicated specifically to the contrary, conventional methods of virology, immunology, microbiology, molecular biology and recombinant DNA techniques within the skill of the art, many of which are described below for the purpose of illustration. Such techniques are explained fully in the literature. See, e.g., Current Protocols in Molecular Biology or Current Protocols in Immunology, John Wiley & Sons, New York, N.Y.(2009); Ausubel et al., Short Protocols in Molecular Biology, 5th ed., Wiley & Sons, 2002; Sambrook and Russell, Molecular Cloning: A Laboratory Manual (4th Edition, 2012); and other like references. [0031] This disclosure is not limited to particular compositions or biological systems. It is also to be understood that the terminology used herein is for the purpose of describing particular illustrative embodiments only and is not intended to be limiting. The terms used in this specification generally have their ordinary meaning in the art, within the context of this disclosure and in the specific context where each term is used. Certain terms are discussed below or elsewhere in the specification, to provide additional guidance to the practitioner in describing the compositions and methods of the disclosure and how to make and use them. The scope and meaning of any such terms will be apparent from the specific context in which the term is used. As such, the definitions set forth herein are intended to provide illustrative guidance in ascertaining particular embodiments of the disclosure, without limitation to particular compositions or biological systems. [0032] As used in the present disclosure and the appended claims, the singular forms “a,” “an” and “the” include plural references unless the content clearly dictates otherwise. [0033] Throughout the present disclosure and the appended claims, unless the context requires otherwise, the word “comprise”, or variations such as “comprises” or “comprising,” will be understood to imply the inclusion of a stated element or group of elements but not the exclusion of any other element or group of elements. “Comprising” may be synonymous with “including” or “containing.” [0034] It should be understood that wherever embodiments are described herein with the language “comprising,” and otherwise analogous embodiments described in terms of “consisting of” and/or “consisting essentially of” are also provided. As used herein, “consisting of” is a closed term that includes only the specific elements recited, and “consisting essentially of” includes the specific elements recited and may include additional unrecited, nonmaterial elements. [0035] As used herein, the term “about” modifying the quantity of an ingredient, parameter, calculation, or measurement in the compositions of the disclosure or employed in the methods of the disclosure refers to variation in the numerical quantity that can occur, for example, through typical measuring and liquid handling procedures used for making isolated antibodies or pharmaceutical compositions in the real world; through inadvertent error in these procedures; through differences in the manufacture, source, or purity of the ingredients employed to make the compositions or carry out the methods; and the like without having a substantial effect on the chemical or physical attributes of the compositions or methods of the disclosure. Whatever the cause, known or unknown, of the variation or a variation made by choice, the term “about” as used herein means within 10%, more typically within 5%, of a given value or range. Whether or not modified by the term “about”, the disclosure includes equivalents to the recited quantities. Reference to “about” a value or parameter herein includes (and describes) embodiments that are directed to that value or parameter per se. For example, description referring to about “X“ includes “X” itself Numeric ranges are likewise inclusive of the numbers defining the range. Moreover, all ranges disclosed herein are to be understood to encompass any and all subranges or individual values subsumed therein. [0036] The terms “antibody” (Ab) and “immunoglobulin” (Ig) are used interchangeably herein and refer to a molecule (e.g., complete antibodies, antibody fragments or modified antibodies) capable of recognizing and binding to a specific target or antigen, such as a carbohydrate, polynucleotide, lipid, polypeptide, protein etc., through at least one antigen recognition site, located in the variable region of the molecule. An antibody may be either membrane bound or secreted. As used herein, the term encompasses not only intact, or “whole”, polyclonal or monoclonal antibodies, but also fragments thereof (such as single- variable domain (VH, VL or combination thereof) antibodies, Fab, Fab', F(ab')2, Fv), single chain (ScFv), synthetic variants thereof, naturally occurring variants, fusion proteins comprising an antibody portion with an antigen-binding fragment of the required specificity, fully human, humanized antibodies, chimeric antibodies, chimeric antigen receptors (CARs), and any other modified configuration of the immunoglobulin molecule that comprises an antigen-binding site or fragment (epitope recognition site) of the required specificity. [0037] Antibody, or Ig, molecules, in some embodiments a “whole antibody”, typically comprise two identical heavy chains and two identical light chains linked together through disulfide bonds. Both the heavy chains (IgH) and light chains (IgL) of an antibody or Ig molecule contain a variable (V) region or domain and a constant (C) region or domain. Within any given immune repertoire, the portion of the IgH locus encoding the V region comprises multiple copies of variable (V), diversity (D), and joining (J) gene segments. Within any given immune repertoire, the portion of the IgL loci encoding the V region comprises multiple copies of V and J gene segments. The V region encoding portion of the IgH and IgL loci undergoes gene segment rearrangement, e.g., different combinations of a V, (D) and J gene segments arrange to form the IgH and IgL variable regions (VH and VL, respectively), to develop the diverse antigen specificity that characterize antibodies. Each variable region comprises three hypervariable complementarity-determining regions (CDRs) interspersed between the less variable framework regions (FRs). The heavy chain comprises HCDR1, HCDR2, and HCDR3. The light chain comprises LCDR1, LCDR2, and LCDR3. The secreted form of the IgH C region of most antibodies is made up of three C domains, CH1, CH2, CH3, and a hinge region, except for C ^, which includes a CH4 regions and lacks a hinge region. The membrane-bound form of the IgH C region also has membrane and intra-cellular domains. The IgH constant region determines the isotype of the antibody, e.g. IgM, IgD, IgG1, IgG2, IgG3, IgG4, IgA or IgE. It will be appreciated that non-human mammals, such as an AlivaMab® Mouse, encoding multiple Ig isotypes will be able to undergo isotype class switching. There are two types of human IgL, Ig ^ and Ig ^. [0038] As used herein, the term “monoclonal antibody” or “mAb” refers to an antibody produced by an identical set of immune cells that is each a clone of a unique parent cell. Monoclonal antibodies are monospecific, have identical sequences, and bind to the same epitope in the same way. [0039] The term “antigen-binding fragment” as used herein refers to a polypeptide fragment that contains at least one CDR of an immunoglobulin heavy and/or light chain that binds to PD-L1. In this regard, an antigen-binding fragment of the antibodies may comprise 1, 2, 3, 4, 5, or all 6 CDRs of a VH and VL sequence. (See SEQ ID NO: 1-1070). In some embodiments of this disclosure, the antigen-binding fragment of the anti-PD-L1 antibodies comprise all 6 CDRs of a VH and VL sequence. An antigen-binding fragment of the PD-L1- specific antibodies disclosed herein is capable of binding to the PD-L1 protein, preferably the receptor binding domain (RBD) of the PD-L1 protein. [0040] In some embodiments, antibodies and antigen-binding fragments thereof disclosed herein include a heavy chain and a light chain CDR set, respectively interposed between heavy chain and light chain framework regions (FR) that provide conformational support to the CDRs and define the spatial relationship of the CDRs relative to each other. As used herein, the term “CDR set” refers to the three hypervariable regions of a heavy or light chain V region. Proceeding from the N terminus of a heavy or light chain, these regions are denoted as “CDR1,” “CDR2,” and “CDR3” respectively. An antigen-binding fragment in these embodiments, therefore, includes six CDRs, comprising the CDR set from each of a heavy and a light chain V region. [0041] A “Fab” domain or fragment comprises the N-terminal portion of the IgH, which includes the V region and the CH1 domain of the IgH, and the entire IgL. A “F(ab’)₂” domain comprises the Fab domain and a portion of the hinge region, wherein the 2 IgH are linked together via disulfide linkage in the middle hinge region. Both the Fab and F(ab’)2 are non-limiting examples of “antigen-binding fragments.” [0042] The C-terminal portion of the IgH, which is the crystallizable fragment of an antibody following papain digestion and comprises the CH2 and CH3 domains, is referred to as the “Fc” domain. The Fc domain is the portion of the Ig recognized by cell receptors, such as the FcR, and to which the complement-activating protein, C1q, binds. The lower hinge region, which is encoded in the 5’ portion of the CH2 exon, provides flexibility within the antibody for binding to FcR receptors. Although the boundaries of the Fc domain may vary, the human IgG heavy chain Fc domain, as defined herein, comprises residue E216 to its carboxyl-terminus of the CH3 domain (or the CH4 domain for IgM and IgE antibodies), wherein the numbering is in the EU format as set forth in Edelman. The term “Fc domain” may refer to this sequence in isolation, or this sequence in the context of an antibody, antibody fragment, or Fc fusion protein. The amino acid sequence of a non-naturally occurring Fc domain (also referred to herein as a “variant Fc domain”) may comprise one or more amino acid modifications. For example, polymorphisms have been observed at a number of Fc domain positions, including but not limited to positions 270, 272, 312, 315, 356, and 358, according to EU numbering, and, thus slight differences between the presented sequence and sequences in the prior art may exist. Mutations may also be introduced into the Fc domain. [0043] The term “EU format as set forth in Edelman” refers to the residue numbering of the human IgG1 EU antibody as described in Edelman GM et al., (1969) Proc. Natl. Acad. USA, 63, 78-85. The human IgG2 and human IgG4 residue numbering is also in the EU format (See Dillon TM, et al., J Biol Chem. Jun 6;283(23):16206-15 (2008); Aalberse RC et al., Immunology 105:9-19 (2002); and Scholthauer T et al., Protein Engineering, Design and Selection, 29(10): 457-466, (2016). The EU numbering of residues may be determined by aligning an antibody at regions of homology to the sequence of the antibody with a “standard” EU numbered sequence. Unless indicated to the contrary, all residue numbering of constant regions herein will be according to EU numbering. [0044] The term “Kabat numbering” refers to the residue numbering of the variable regions as described in Kabat et al, (1991) US Department of Health and Human Services, NIH publication n 91-3242. Variable region CDRs (CDR L1, CDR L2, CDR L3, CDR H1, CDR H2, CDR H3) are identified according to contact based on crystal structures as defined in Karpusas et al. Structure. Apr 4;9(4):321-9 (2001) and numbered in accordance with the Kabat numbering system. Unless indicated to the contrary, all residue numbering of variable regions will be according to Kabat. [0045] An “Fv” fragment includes a non-covalent VH::VL heterodimer including an antigen-binding site. In certain embodiments, single chain Fv (scFv) antibodies are contemplated as part of this disclosure A scFv is a covalently linked VH::VL heterodimer which is expressed from a gene fusion including VH- and VL-encoding genes linked by a peptide-encoding linker (see, e.g., Huston et al. (1988) Proc. Nat. Acad. Sci. USA 85(16):5879- 5883 and Byrd et al (1988) Science, 242:423-6, incorporated herein by reference). As used herein, the term “linker” refers to a polypeptide sequence that joins two or more antibody domains. Linkers’ characteristics and their suitability for particular purposes are known in the art. See, e.g., Chen et al. Adv Drug Deliv Rev. October 15; 65(10): 1357–1369 (2013) (disclosing various types of linkers, their properties, and associated linker designing tools and databases), which is incorporated herein by reference. Linkers may be flexible, rigid, or in vivo cleavable. Preferably, the linker is flexible. Flexible linkers typically comprise small non- polar (e.g. Gly) or polar (e.g., Ser or Thr) amino acids. The most commonly used flexible linkers have sequences consisting primarily of stretches of Gly and Ser residues (“GS” linker). Optionally, flexible linkers comprise repeats of 5 Gly and Ser residues. [0046] Where bispecific antibodies are to be used, these may be conventional bispecific antibodies, which can be manufactured in a variety of ways (see, e.g., Holliger, P. and Winter G. Current Opinion Biotechnol. 4, 446-449 (1993) ; Brinkmann U, Kontermann RE. MAbs. 9(2),182-212 (2017); Brinkmann U, Kontermann RE. Science. 372(6545), 916-917 (2021); Kontermann RE, Brinkmann U. Bispecific antibodies. Drug Discov Today. 20(7), 838-47 (2015); Spiess C, Zhai Q, Carter PJ. Mol Immunol. 67(2 Pt A), 95-106 (2015); Labrijn AF, Janmaat ML, Reichert JM, Parren PWHI. Nat Rev Drug Discov. 18(8), 585-608 (2019 incorporated herein by reference), e.g., prepared chemically or from hybrid hybridomas, or may be any of the bispecific antibody fragments mentioned above. [0047] As used herein, the term “chimeric antibody” refers to an antibody having regions derived from two or more species, e.g., human and mouse. While an arm of a bispecific or multi-specific antibody may be “chimeric” in that it comprises regions derived from two or more species, the bispecific or multi-specific antibody is not chimeric just because its individual arms were derived from different species. [0048] As used herein, the term “chimeric Ig chain” refers to an Ig heavy chain or an Ig light chain having regions derived from two or more species, e.g., human and mouse. For example, a chimeric Ig heavy chain may comprise a human VH domain, DH domain, JH domain, CH1 domain, and upper hinge region and mouse CH2 and CH3 domains. In some embodiments, the middle hinge region is mouse. In some embodiments, the middle hinge region is human. In some embodiments, the middle hinge region is chimeric. [0049] As used herein, the term “fully human antibody” or “human antibody” refers to an antibody having variable and constant regions derived from human germline immunoglobulin sequences. A “human antibody” can also include amino acid residues not encoded by human germline immunoglobulin sequences (e.g., mutations introduced by random or site-specific mutagenesis in vitro or by somatic mutation in vivo). The term “human antibody,” however, does not encompass antibodies in which the CDR sequences are derived from the germline of another mammalian species, such as a mouse, and have been grafted onto human framework sequences (i.e., humanized antibodies). The term “human antibody” also encompasses antibodies with sequences derived from human genes, but which have been changed, e.g. to decrease possible immunogenicity, increase affinity, decrease effector function eliminate cysteines that might cause undesirable folding, etc. The term “human antibody” also encompasses such antibodies comprising human amino acid sequences produced recombinantly in non-human cells, which might impart a glycosylation pattern that is not typical of human cells. [0050] As used herein, the term “isolated” antibody or antigen-binding fragment refers to an antibody or fragment that is at least partially free of or purified from, for example, the other biological molecules present in the cells used to produce it. The other biological molecules from which an isolated antibody or fragment is at least partially free include nucleic acid molecules, proteins, lipids, carbohydrates, cellular debris and culture medium. The term “isolated” antibody or fragment does not require, but does encompass, a complete absence of such other biological molecules or is at least 70%, 80%, 90%, 95%, 96%, 97%, 98%, or 99% free of said biological molecules. The term “isolated” antibody or fragment also does not refer to a complete absence of other molecules, such as water, buffers, salts or the components of pharmaceutical formulations. Thus, a molecule that is chemically synthesized or synthesized in a cell-free system will be “isolated” from its naturally associated components. A molecule may also be “isolated” using purification techniques well known in the art. Similarly, the term “isolated polynucleotide” or nucleic acid molecule, as used herein, refers to a polynucleotide of genomic, mRNA, cDNA, or synthetic origin or some combination thereof, which (1) is not associated with all or a portion of polynucleotide with which the “isolated nucleic acid” is associated with in nature or (2) is operably linked to a polynucleotide to which it is not linked in nature. An isolated polynucleotide “comprising” a specific sequence may also include coding sequences for other proteins or immunoglobulin chains, expression regulatory sequences or vector sequences. [0051] As used herein, the terms “polypeptide,” “peptide” or “protein” are used interchangeably herein to describe a chain of amino acids that are linked together by chemical bonds. Non-limiting examples of a polypeptide or protein include an IgH, IgL, V domain, C domain, or an antibody. [0052] As used herein, the term “amino acid modification” refers to at least one amino acid substitution, insertion, deletion or mutation in an amino acid sequence compared to a wild- type amino acid sequence. Such modifications are within the ordinary skill of an artisan. Some modifications, including amino acid deletions, substitutions and additions, of the Fc domain have been shown to alter the Fc domain’s binding to its ligands and/or receptors resulting in a concomitant modification of effector function (see, e.g., Shields et al., J Biol Chem 276:6591- 6604 (2001); Presta et al., Biochem Soc Trans 30:487-490 (2002); Escobar-Cabrera E et al. Antibodies.6: 7 (2017); Duncan AR et al. Nature.1988; 332: 738–740 (1988); Duncan AR et al. Nature. 332: 563–564 (1988); Hezareh M et al. J Virol. 75: 12161–12168 (2001); Oganesyan V et al. Acta Crystallogr D Biol Crystallogr; 64: 700–704 (2008); Schlothauer T et al. Protein Eng Des Sel. Oct; 29(10):457-466 (2016); Tao MH et al. J. Immunol.143: 2595– 2601 (1989); Von Kreudenstein TS et al. MAbs.5(5):646–654 (2013); Wang X et al. Protein Cell.9(1):63–73 (2018); U.S. Patent Publications 20040132101; 20070111260; 20110287032; 20180194860; U.S. Patent No. US 8409568; International Publication No. WO2017/177337, each incorporated by reference in its entirety). An amino acid deletion is indicated with a “∆”, and an insertion is indicated with a “In”. For example, a deletion of the amino acid sequence from E216 to E222 is indicated as ∆E216-E222. An insertion of an arginine (R) between amino acid residues 234 and 235, e.g., would be indicated as InR234/235. [0053] A “conservative amino acid substitution” replaces an amino acid residue with a different amino acid residue having similar biochemical properties (e.g., charge, hydrophobicity, or size). Generally, conservative amino acid substitutions do not substantially change the functional properties of a protein. When comparing proteins comprising conservative substitutions, the percent sequence similarity may be adjusted to account for the conservative nature of the substitution. Such adjustments are well-known in the art. See, e.g., Pearson, Methods Mol. Biol. 243:307-31 (1994). Table 2, infra, provides some of the biochemical properties of the twenty naturally occurring amino acids. Table 3, infra, provides non-limiting examples of conservative amino acid substitutions for each of the naturally occurring amino acids. Table 2.

Table 3.

[0054] The term “percent sequence identity” in the context of polypeptide (or polynucleotide) sequences is defined as the percentage of amino acid (or nucleic acid) residues in a candidate sequence that are identical with the amino acids (or nucleic acid residues) in the reference polypeptide (or polynucleotide) sequence, after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent sequence identity, and not counting any conservative substitutions as different. Such conservative substitutions are considered (in addition to identical residues) in calculating the “percent sequence similarity” of two sequences. Residue positions that are not identical but are similar differ by conservative amino acid substitutions. [0055] Sequence alignments (e.g. for determining percent amino acid sequence identity or sequence similarity, such as between a wild type protein and a mutein thereof) can be achieved in various ways that are within the skill in the art, for instance, using publicly available sequence analysis computer software such as BLAST, BLAST-2, ALIGN, Megalign (DNASTAR), Gap, BESTFIT®, and other programs in programs in Wisconsin Package Version 10.0 or Genetics Computer Group (GCG), Madison, Wisconsin, software Geneious Biologics, PipeBio. The skilled artisan can determine appropriate parameters for aligning sequences, including any algorithms needed to achieve maximal alignment over the full length of the sequences being compared. Polypeptide sequences also can be compared using FASTA using default or recommended parameters. In the context of polypeptide sequences, FASTA takes the query amino acid sequence and searches a sequence database using local sequence alignment to identify similar sequences within the database (Pearson, Methods Enzymol. 183:63-98 (1990); Pearson, Methods Mol. Biol. 132:185-219 (2000); Pearson Curr Protoc Bioinformatics. Mar 24;53:3.9.1-25 (2016); each herein incorporated by reference). BLAST, especially blastp or tblastn, using default parameters may be used to compare a query sequence to a database containing sequences from different organisms. See, e.g., Altschul et al., J. Mol. Biol.215:403-410 (1990); Altschul et al., Nucleic Acids Res.25:3389-402 (1997); Eser et al., PLoS One.22;9(12): e115445 (2014), each herein incorporated by reference. [0056] Amino acids may be grouped based on their similar biochemical properties. Such groupings that may be used to define conservative substitutions include 1) amino acid residues with aliphatic side chains: glycine, alanine, valine, leucine, and isoleucine; 2) amino acid residues with aliphatic-hydroxyl side chains: serine and threonine; 3) amino acid residues with amide-containing side chains: asparagine and glutamine; 4) amino acid residues with aromatic side chains: phenylalanine, tyrosine, and tryptophan; 5) amino acid residues with basic side chains: lysine, arginine, and histidine; 6) amino acid residues with acidic side chains: aspartic acid and glutamic acid; and 7) amino acid residues with sulfur-containing side chains: cysteine and methionine. Non-limiting examples of preferred conservative amino acids substitution groups include: valine-leucine-isoleucine, phenylalanine-tyrosine, lysine-arginine, alanine-valine, glutamate-aspartate, and asparagine-glutamine. [0057] As used herein, the term “effector function” refers to the responses of cells of the immune system that are triggered by the interaction of antibodies and antibody-antigen complexes. These effector functions usually involve one of three major mechanisms: antibody-dependent cell-mediated cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), and opsonization and phagocytosis. In ADCC, the Fc receptors on cytotoxic T cells, natural killer (NK) cells, or macrophages bind to the Fc domains of antibodies that are bound to a target cell, resulting in the secretion of substances, such as lytic enzymes, perforin, granzymes and tumor necrosis factor, that mediate the destruction of the target cell. In CDC, cell death is induced via activation of the complement cascade. See Daeron, Annu. Rev. Immunol., 15:203-234 (1997); Ward and Ghetie, Therapeutic Immunol., 2:77-94 (1995); and Ravetch and Kinet, Annu. Rev. Immunol.9:457-492 (1991)). In opsonization and phagocytosis, a pathogen-bound antibody’s Fc domain binds to a Fc receptor on the surface of a phagocyte, inducing phagocytosis. Such effector functions generally require the Fc domain to be combined with a binding domain (e.g. an antibody variable domain) and can be assessed using standard assays that are known in the art (see, e.g., WO 05/018572, WO 05/003175, and U.S. Pat. No.6,242,195). The Fc domain of the antibody mediates immune effector mechanisms. IgG antibodies activate effector pathways of the immune system by binding to members of the family of cell surface Fcγ receptors and to Clq of the complement system. Ligation of effector proteins by clustered antibodies triggers a variety of responses, including release of inflammatory cytokines, regulation of antigen production, endocytosis, and cell killing. These responses can provoke unwanted side effects such as inflammation and thrombosis. Accordingly, the present disclosure further relates to anti-PD-L1 antibodies, with modified effector functions, including antibodies in which one or more effector functions is reduced or eliminated. [0058] As used herein, the term “modified effector functions” refers to a Fc domain with one or more effector functions that differ from a wild-type immunoglobulin Fc domain. In some embodiments, one or more effector functions are reduced. Optionally, one or more effector functions are eliminated. The modified or reduced effector functions may be the result of lower binding affinity of the Fc domain of the antibodies disclosed herein to effector molecules (e.g., FcγRs and/or C1q). For example, the anti-PD-L1 antibodies disclosed herein may have reduced Fc receptor binding and complement activation compared with that of wild- type anti-PD-L1 antibodies. In some embodiments, a variant Fc domain has a reduced antibody dependent cell-mediated cytotoxicity (ADCC). Effector function of an anti-PD-L1 antibody may be determined using one of many known assays, including the CDC assay, the ADCC assay, and the phagocytosis assay (see Xu-Rong Jiang et al., Nature Reviews Drug Discovery 10: 101–111 (2011) and Liu et al., The Journal of Biological Chemistry 292:1876-1883 (2017)). One or more of the antibody’s effector functions may be reduced by at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 95% relative to the effector function of a wild- type antibody. [0059] The strength, or affinity of immunological binding interactions can be expressed in terms of the dissociation constant (KD) of the interaction, wherein a smaller KD represents a greater affinity. Immunological binding properties of selected polypeptides can be quantified using methods well known in the art. One such method entails measuring the rates of antigen- binding site/antigen complex formation and dissociation, wherein those rates depend on the concentrations of the complex partners, the affinity of the interaction, and on geometric parameters that equally influence the rate in both directions. Thus, both the “on rate constant” (kon) and the “off rate constant” (koff) can be determined by calculation of the concentrations and the actual rates of association and dissociation. The ratio of koff /kon enables cancellation of all parameters not related to affinity, and is thus equal to the equilibrium dissociation constant, KD. See, generally, Davies et al. (1990) Annual Rev. Biochem. 59:439-473. An antibody is considered to specifically bind an antigen when the KD is ≤ 1 µM, preferably ≤ 100 nM. High affinity antibodies generally have a K_D in the low nanomolar (10^-9) range, and very high affinity antibodies generally have a K_D in picomolar (10^-12) range. A K_D binding affinity constant can be measured by surface plasmon resonance, e.g. using the BIACORE^® system (Cytiva Life Sciences, Sweden and Piscataway, N.J.). See also, Jonsson et al., Ann. Biol. Clin. 51:19-26 (1993); Jonsson et al., Biotechniques 11:620-627 (1991); Jonsson et al., J. Mol. Recognit.8:125-131 (1995); Johnsson et al., Anal. Biochem.198:268-277 (1991); Hearty S et al., Methods Mol Biol.907:411-42 (2012), each incorporated herein by reference. The KD may also be measured using a KINEXA^® system (Sapidyne Instruments, Hanover, Germany and Boise, ID). The KD may also be measured by biolayer interferometry (BLI) using an OCTET^® system (Sartorius AG, Goettingen, Germany). An antibody, or antigen-binding fragment thereof, is said to “specifically bind,” “immunologically bind,” and/or is “immunologically reactive” to PD-L1 if it reacts at a detectable level (within, for example, an ELISA assay) with PD-L1, and does not react detectably with unrelated polypeptides under similar conditions and antibody concentrations. In some embodiments, the antibody, or antigen-binding fragment thereof, specifically binds PD-L1. [0060] As used herein, the term “avidity” refers to the overall strength of an antibody-antigen complex. Avidity relates to three major parameters: the affinity of the antibody for the epitope; the valency of both the antibody and antigen; and the structural arrangement of the parts that interact. As used herein, “avidity” describes the increased affinity that occurs as result of multiple antigen binding sites on an immunoglobulin. [0061] As used herein, the terms “polynucleotide” and “nucleic acid molecule” are used interchangeably and refer to a polymer of nucleic acids that are linked together by chemical bonds. Polynucleotides include, but are not limited to, DNA, cDNA, RNA, mRNA, and gene sequences and segments. Polynucleotides may be isolated from a living source such as a eukaryotic cell, prokaryotic cell or virus, or may be derived through in vitro manipulation by using standard techniques of molecular biology, or by DNA synthesis, or by a combination of a number of techniques. Polynucleotides may comprise ribonucleotides, deoxynucleotides, modified forms of either type of nucleotide, or a combination thereof. A polynucleotide may be single-stranded or double-stranded. A reference herein to a nucleotide sequence encompasses its complement, unless otherwise specified. Thus, a reference to a polynucleotide having a particular sequence should be understood to encompass its complementary strand, with its complementary sequence. [0062] As used herein, the term “highly stringent conditions” refers to hybridization to filter-bound DNA in 0.1x sodium chloride/sodium citrate (SSC) at 65 °C, followed by one or more washes in 0.1x SSC, 0.1% SDS at 50-65 °C. (Ausubel et al., eds., 1989, Current Protocols in Molecular Biology, Vol. I, Green Publishing Associates, Inc., and John Wiley & Sons, Inc., N.Y., at p.2.10.3). [0063] As used herein, the term “operably linked” refers to two structures that have been placed in a functional relationship with each other. In the context of an antibody, for example, a second antibody or targeting arm may be operably linked to a structure that confers effector function. For example, the antigen-binding sequence of an antibody (e.g., variable region or VH or VL domain) may be operatively linked to a Fc domain. In the context of a polynucleotide, a coding sequence may be operatively linked to a non-coding regulatory sequence, such as a promoter, an enhance, a signal sequence, a ribosome binding sequence, a splice acceptor sequence, a splice donor sequence, a termination sequence, etc. Two operably linked structures may be directly connected. Alternatively, two operably linked structures may be connected via one or more intermediary structures. For example, the antigen-binding portion of an antibody may be operably linked to the Fc domain via a CH1 domain, a hinge region and/or a linker sequence. Similarly, operably linked non-coding regulatory sequences include both sequences that act in cis and are contiguous with the coding sequence and sequences that act in trans or at a distance to control the coding sequence. [0064] As used herein, the term “vector“ refers to a polynucleotide molecule that can replicate in a cell and into which another polynucleotide fragment can be integrated without loss of the vector's ability to replicate. Vectors may originate from a virus, a plasmid or the cell of a higher organism. Vectors are utilized to introduce foreign or DNA or RNA into a host cell, wherein the vector together with the inserted DNA is replicated. Non-limiting examples of vectors include viral vectors, naked DNA or RNA expression vectors, bacterial vectors, mammalian vectors, plasmids, cosmids, phage vectors, DNA or RNA expression vectors associated with cationic condensing agents, DNA or RNA expression vectors encapsulated in liposomes, and certain eukaryotic cells, such as producer cells. In some embodiments, the vectors autonomously replicate in the host cell into which they are introduced. Optionally, the vectors integrate into the host cell’s genome and are replicated along with the host genome. Vectors may be capable of directing the expression of coding sequences contained within them. Such vectors are referred to herein as “recombinant expression vectors” or “expression vectors.” [0065] A polynucleotide can be contained in a vector, which can facilitate manipulation of the polynucleotide, including introduction of the polynucleotide into a target cell. The vector may be a cloning vector, which is useful for maintaining the polynucleotide or producing larger amounts of it. Where the polynucleotide encodes an RNA, for expressing the encoded RNA in a particular cell, either for subsequent translation of the RNA into a polypeptide or for subsequent trans regulatory activity by the RNA in the cell, the vector may be an expression vector, which contains, in addition to the polynucleotide, regulatory elements useful for expressing the polynucleotide. An expression vector may contain the expression elements necessary to achieve, for example, sustained transcription of the encoding polynucleotide, or the regulatory elements can be operatively linked to the polynucleotide prior to its being cloned into the vector. [0066] An expression vector generally contains a promoter sequence, which can provide constitutive or, if desired, inducible, tissue-specific or developmental-stage-specific expression of the encoding polynucleotide; a poly-A sequence; and a ribosome recognition site or internal ribosome entry site, or other regulatory elements such as an enhancer, which can be tissue specific. The vector also can contain elements required for replication in a prokaryotic or eukaryotic host system or both, as desired. Such vectors, which include plasmid vectors and viral vectors such as bacteriophage, baculovirus, retrovirus, lentivirus, adenovirus, vaccinia virus, alpha virus and adeno-associated virus vectors, are well known and can be purchased from a commercial source (Agilent technologies, Santa Clara Cal.; Thermo Fisher Scientific, Waltham, MA.) or can be constructed by one skilled in the art (see, e.g., Meth. Enzymol., Vol. 185, Goeddel, ed. (Academic Press, Inc., 1990); Jolly, Canc. Gene Ther.1:51-64, 1994; Flotte, J. Bioenerg. Biomemb 25:37-42, 1993; Kirshenbaum et al., J. Clin. Invest, 92:381-387, 1993; each of which is incorporated herein by reference). [0067] The term “polynucleotide construct” as used herein refers to a sequence of DNA artificially constructed by genetic engineering, recombineering or synthesis. In some embodiments, the DNA constructs are linearized prior to recombination. In another embodiment, the DNA constructs are not linearized prior to recombination. [0068] As used herein, the “host cell” refers to a cell into which a polynucleotide or a vector has been introduced. It should be understood that a “host cell” includes not only the particular subject cell but also the progeny of such a cell. Because certain modifications may occur in succeeding generations due to either mutation or environmental influences, such progeny may not, in fact, be identical to the parent cell, but are still included within the scope of the term “host cell” as used herein, provided they still contain the vector, polynucleotide, or a portion thereof, either maintained episomally or integrated into the host-cell genome. [0069] The terms “patient,” “subject,” and “individual” are used interchangeably herein and refer to either a human or a non-human animal in need to treatment. These terms include mammals, such as humans, primates (e.g., monkey), livestock such as cattle, sheep, pigs, horses and goats, and companion animals such as dogs and cats. Optionally, the subject is a human. In some embodiments, the subject is suffering from or at risk for cancer. In some embodiments, the subject is suffering from a chronic viral infection. [0070] The terms “treating” and “treatment” with regard to a subject, refers to improving at least one symptom of the subject's disease or disorder. Treating includes curing, improving, or at least partially ameliorating the disease or disorder or any symptom of the disease or disorder. With regard to cancer, these terms refer to providing an increased life expectancy of an individual suffering from cancer or that one or more of the symptoms of the cancer is reduced. The terms also encompass a decreased risk of malignancy in a subject suffering from cancer. With respect to the treatment of chronic viral infection, treatment may refer to enhancing the body’s immune responses towards the virus. [0071] As used herein, the terms “prevent,” “preventing,” and “prevention” refer to the prevention or delay of the recurrence or onset of, or a reduction in one or more symptoms of a disease or a disorder in a subject as a result of the administration of an anti-PD-L1 antibody or antigen-binding fragment thereof of this disclosure. For example, in the context of cancer, “prevent,” “preventing,” and “prevention” refer to the inhibition, reduction, delay in the development, the prevention or delay of the recurrence, onset, or development of one or more symptoms associated with cancer in a subject and the maintenance of remission in the subject. Also, in the context of chronic viral infection, “prevent”, “preventing” and “prevention” refer to the inhibition, reduction, or delay in the development or onset of a chronic viral infection or the prevention or delay of the recurrence, onset, or development of one or more symptoms associated with chronic viral infection. [0072] As used herein, the term “therapeutically effective amount” refers to that amount of the therapeutic agent being administered, as a single agent or in combination with one or more additional agents, which will relieve or improve to some extent one or more of the symptoms of the condition being treated. With respect to the treatment of cancer, a therapeutically effective amount refers to that amount which has at least one of the following effects: palliate, ameliorate, stabilize, reverse, prevent, slow or delay the progression of (and/or symptoms associated with) of cancer. The effective amounts that may be used in the present disclosure varies depending upon the manner of administration, the age, body weight, and general health of the subject. The appropriate amount and dosage regimen can be determined using routine skill in the art. [0073] A “prophylactically effective amount” refers to an amount effective, at dosages and for periods of time necessary, to achieve the desired prophylactic result. Typically, because a prophylactic dose is used in subjects in remission, the prophylactically effective amount may be less than the therapeutically effective amount. [0074] As used herein, the terms “pharmaceutically acceptable carrier” and “pharmaceutically acceptable excipient” are used interchangeably and refer to any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, and the like that are physiologically compatible. Pharmaceutically acceptable carriers are well known in the art. See, e.g., Remington's Pharmaceutical Sciences and U.S. Pharmacopeia: National Formulary, Mack Publishing Company, Easton, PA (1984), incorporated herein by reference. Some examples of pharmaceutically acceptable carriers are water, saline, phosphate buffered saline, dextrose, glycerol, ethanol and the like, as well as combinations thereof. These carriers, without limitation, may be included in the FDA compendium of excipients that are generally regarded as safe (GRAS) (https://www.fda.gov/food/food-ingredients-packaging/generally-recognized-safe-gras). In many cases, it will be preferable to include isotonic agents, for example, sugars, polyalcohols such as mannitol, sorbitol, or sodium chloride in the composition. Additional examples of pharmaceutically acceptable substances are wetting agents or minor amounts of auxiliary substances such as wetting or emulsifying agents, preservatives or buffers, which enhance the shelf life or effectiveness of the antibody. Pharmaceutical compositions may be prepared by mixing an antibody disclosed herein with acceptable carriers, excipients, or stabilizers in the form of, e.g., lyophilized powders, slurries, aqueous solutions or suspensions (see, e.g., Hardman, et al. (2001) Goodman and Gilman’s The Pharmacological Basis of Therapeutics, McGraw-Hill, New York, NY; Gennaro (2000) Remington: The Science and Practice of Pharmacy, Lippincott, Williams, and Wilkins, New York, NY; Avis, et al. (eds.) (1993) Pharmaceutical Dosage Forms: Parenteral Medications, Marcel Dekker, NY; Lieberman, et al. (eds.) (1990) Pharmaceutical Dosage Forms: Tablets, Marcel Dekker, NY; Lieberman, et al. (eds.) (1990) Pharmaceutical Dosage Forms: Disperse Systems, Marcel Dekker, NY; Weiner and Kotkoskie (2000) Excipient Toxicity and Safety, Marcel Dekker, Inc., New York, NY; each incorporated herein by reference). These carriers, without limitation, may be included in the FDA compendium of excipients that are generally regarded as safe (GRAS) (https://www.fda.gov/food/food-ingredients-packaging/generally-recognized-safe-gras). [0075] The term “administering,” as used herein, refers to any mode of transferring, delivering, introducing, or transporting a pharmaceutical composition or other agent, such as an anti-PD-L1 antibody, to a subject. For cancer therapy, such administrations are typically parenteral, such as intravenous. [0076] Each embodiment in this specification is to be applied mutatis mutandis to every other embodiment unless expressly stated otherwise. [0077] Standard techniques may be used for recombinant DNA, oligonucleotide synthesis, and tissue culture and transformation (e.g., electroporation, lipofection, etc). Enzymatic reactions and purification techniques may be performed according to manufacturer's specifications or as commonly accomplished in the art or as described herein. These and related techniques and procedures may be generally performed according to conventional methods well known in the art and as described in various general and more specific references that are cited and discussed throughout the present specification. Unless specific definitions are provided, the nomenclature utilized in connection with, and the laboratory procedures and techniques of, molecular biology, analytical chemistry, synthetic organic chemistry, and medicinal and pharmaceutical chemistry described herein are those well-known and commonly used in the art. Standard techniques may be used for recombinant technology, molecular biological, microbiological, chemical syntheses, chemical analyses, pharmaceutical preparation, formulation, and delivery, and treatment of patients. Anti-PD-L1 Antibodies [0078] AlivaMab® Mouse anti-PD-L1 antibodies were generated using both an AlivaMab ® XKL Mouse (a cross between Alivamab® Kappa-Lambda mice and another genetic background) and an AlivaMab® Mouse Lambda Only mice. Antibodies produced by the AlivaMab® XKL Mouse comprise a chimeric immunoglobulin heavy (IgH) chain and a human immunoglobulin kappa (Ig ^) light chain. Antibodies produced by AlivaMab Lambda Only Mice comprise a chimeric IgH chain and a human immunoglobulin lambda (Ig ^) light chain. The chimeric IgH chain of the AlivaMab® Mouse antibodies comprises a human variable region comprising a human variable heavy (VH) domain, a human diversity heavy (DH) domain, and a human joining heavy (JH) domain, a human constant heavy 1 (CH1) domain, a human upper hinge region (except for C ^, which is naturally missing an upper hinge region), a mouse middle hinge region, a mouse CH2 domain, and a mouse CH3 domain. The human heavy chain variable region of any of the chimeric anti-PD-L1 antibodies may be readily appended to a fully human constant region, while maintaining the antigen-binding characteristics of the parent chimeric antibody that were developed in vivo in the AlivaMab® Mouse. In some embodiments, the human heavy chain variable region, CH1 and, optionally, the upper hinge region of the chimeric antibody are appended to human hinge, a human CH2 domain and a human CH3 domain to produce a fully human antibody. [0079] In some aspects of the disclosure, anti-PD-L1 antibodies or an antigen-binding fragments thereof are provided. An anti-PD-L1 antibody, or an antigen-binding fragment thereof, may be a human antibody or fragment thereof. In some embodiments, an anti-PD-L1 antibody, or an antigen-binding fragment thereof, of the disclosure is chimeric. In some embodiments, the chimeric anti-PD-L1 antibody, or an antigen-binding fragment thereof, comprises a chimeric IgH chain and a human Ig ^ chain. In some embodiments, the chimeric anti-PD-L1 antibody, or an antigen-binding fragment thereof, comprises a chimeric IgH chain and a human Ig ^ chain. In some embodiments, the chimeric anti-PD-L1 antibody comprises human and mouse sequences. In some embodiments, an anti-PD-L1 antibody, or an antigen- binding fragment thereof, of the disclosure is a bispecific or multi-specific antibody. In some embodiments, the anti-PD-L1 antibody, or an antigen-binding fragment thereof, of the disclosure is a bispecific or multispecific antibody. In some embodiments, the anti-PD-L1 bispecific antibody further comprises a second antibody, or an antigen-binding fragment thereof. In some embodiments, the bispecific antibody further comprises an immune cell- targeting arm. In some embodiments, the targeting antibody is a cancer or virally infected cell targeting antibody or an antibody that binds relevant cells for targeting these tissues, or an antigen-binding fragment thereof. In some embodiments, the second binding specificity does not provide targeting activity, but instead provides a complementary or redundant functional activity [0080] In some embodiments, the anti-PD-L1 antibody or the antigen-binding fragment thereof comprises one to six complementarity determining regions (CDRs). The one to six CDRs of the antibodies of this disclosure comprise an amino acid sequence selected from the group consisting of SEQ ID NOs: 1-642. [0081] In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises a heavy chain CDR3 (HCDR3) comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 536-642. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises a light chain CDR3 (LCDR3) comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 215- 321. [0082] In some embodiments, the CDRs of an anti-PD-L1 antibody, or antigen-binding fragment thereof, may be mixed and matched between the CDRs of various antibody clones produced by the methods of this disclosure. In some embodiments, an anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises a HCDR1 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 322-428, a HCDR2 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 429-535, and a HCDR3 comprising any HCDR3 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 536-642. In some embodiments, the HCDR1, HCDR2 and HCDR3 are selected from three different anti-PD-L1 clones of this disclosure. In some embodiments, the HCDR1, HCDR2 and HCDR3 are selected from two different anti-PD-L1 clones of this disclosure. In some embodiments, the HCDR1, HCDR2, and HCDR3 are from a single anti- PD-L1 clone of this disclosure. [0083] In some embodiments, an anti-PD-L1 antibody, or an antigen-binding fragment thereof, comprises a LCDR1 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs:1-107, a LCDR2 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 108-214, and a LCDR3 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 215-321. In some embodiments, the LCDR1, LCDR2 and LCDR3 are selected from three different anti-PD-L1 clones of this disclosure. In some embodiments, the LCDR1, LCDR2 and LCDR3 are selected from two different anti-PD-L1 clones of this disclosure. In some embodiments, the LCDR1, LCDR2, and LCDR3 are from a single anti-PD-L1 clone disclosed herein. The single anti-PD-L1 clone may be the same anti-PD-L1 clone from which the HCDR1, HCDR2, and HCDR3 were selected. [0084] In some embodiments, the six CDRs of an anti-PD-L1 antibody, or antigen- binding fragment thereof, are from the same anti-PD-L1 antibody clone of this disclosure. In some embodiments, the six CDRs of an anti-PD-L1 antibody, or antigen-binding fragment thereof, are selected from the corresponding VH and VL of a single clone of this disclosure. In some embodiments, an anti-PD-L1 antibody, or an antigen-binding fragment thereof, comprises 1) a HCDR1, a HCDR2, and a HCDR3 selected from the HCDR1, HCDR2 and HCDR3 of one VH selected from any one of the VH regions of SEQ ID NO: 857-1070 and 2) a LCDR1, a LCDR2, and a LCDR3 selected from the LCDR1, LCDR2 and LCDR3 of one VL selected from any one of the VL regions of SEQ ID NO: 643-856. In some embodiments, an anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises a HCDR1, a HCDR2, a HCDR3, a LCDR1, a LCDR2, and a LCDR3 within the corresponding VH and VL amino acid sequences of a single clone of this disclosure. [0085] In some embodiments, an anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises a VH comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 857-1070. In some embodiments, an anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises a VL comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 643-856. In some embodiments, an anti-PD-L1 antibody, or an antigen-binding fragment thereof, comprises a corresponding VH and VL of a single clone. [0086] The CDRs, VH and/or VL may be selected from any one of the clones from the group consisting of ABL-PD-L1-1 to ABL-PD-L1-107 and ABL-PD-L1-1A to ABL-PD-L1- 107A. [0087] In some embodiments, the HCDR1 may comprise an amino acid sequence selected from the group consisting of SEQ ID NOs: 322-428. In some embodiments, the HCDR2 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 429-535. The HCDR3 may comprise an amino acid sequence selected from the group consisting of SEQ ID NOs: 536-642. In some embodiments the LCDR1 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 1-107. The LCDR2 may comprise an amino acid sequence selected from the group consisting of SEQ ID NOs: 108-214. In some embodiments, the LCDR3 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 215-321. The VH region may comprise an amino acid sequence selected from the group consisting of SEQ ID NOs: 857-1070. In some embodiments, the VL region comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 643-856. [0088] It is known in the art that during the processing and expression of Fc-containing proteins (e.g. antibody heavy chains) that the C-terminal lysine may be cleaved (also known in the art as C-terminal lysine clipping). Accordingly, for each sequence of this disclosure that contains a C-terminal lysine, the corresponding sequence without the C-terminal lysine (i.e., the C-terminal lysine cleavage product) is also contemplated. In some embodiments, the first monomer comprises a C-terminal lysine. In some embodiments, the first monomer lacks a C- terminal lysine. In some embodiments, the second monomer comprises a C-terminal lysine. In some embodiments, the second monomer lacks a C-terminal lysine. [0089] It is also known in the art that the C-terminal cleavage process is imprecise and that additional C-terminal residues are sometimes cleaved. Accordingly, for each sequence of this disclosure that contains a C-terminal lysine, the corresponding sequence without the two C-terminal residues, without the three C-terminal residues, without the four C-terminal residues, without the five C-terminal residues, without the six C-terminal residues, without the seven C-terminal residues, without the eight C-terminal residues, without the nine C-terminal residues, is also contemplated, without the ten C-terminal residues, without the eleven C- terminal residues, without the twelve C-terminal residues, without the thirteen C-terminal residues, without the fourteen C-terminal residues, or without the fifteen C-terminal residues is also contemplated. [0090] In some embodiments, an anti-PD-L1 antibody is a whole antibody. In some embodiments, an anti-PD-L1 antibody is a single-chain antibody. In some embodiments, an anti-PD-L1 antibody is an scFv. In some embodiments, an anti-PD-L1 antibody is a Fab. In some embodiments, an anti-PD-L1 antibody is a Fab’. In some embodiments, an anti-PD-L1 antibody is a F(ab’)₂. In some embodiments, an anti-PD-L1 antibody is an Fv. In some embodiments, the anti-PD-L1 antibody is an scFv, comprising an amino acid sequence selected from the group consisting of SEQ ID NOs.:1071-1102. The skilled artisan would also understand that an scFv fragment can be arranged, from N-terminus to C-terminus, in a VH to VL orientation or in a VL to VH orientation. As used herein, the term “scFv_VH-VL” refers to an scFv fragment which is arranged, from N-terminus to C-terminus, in a VH to VL orientation. Similarly, the term “scFv_VL-VH” refers to an scFv fragment which is arranged, from N-terminus to C-terminus, in a VL to VH orientation. [0091] In some embodiments of the antibodies or antigen-binding fragments of this disclosure, the VH comprises a G44C substitution, according to Kabat numbering. In some embodiments, the VL comprises a G100C substitution, according to Kabat numbering. In some embodiments, the VH comprises a G44C substitution and the VL comprises a G100C substitution, according to Kabat numbering. In some cases, the parental sequence at VH44 may be a different amino acid than G. In such instances, the VH44 residue (according to Kabat) is still mutated to cysteine. In more common, but still relatively rare cases, the parental sequence at VL position 100 may be an amino acid other than G. In such instances, the VL100 residue (according to Kabat) is still mutated to cysteine. Without being bound by theory, the introduction of such complementary cysteine residues can result in a disulfide bond, which can stabilize antibody fragments (e.g. scFv). While non-exhaustive, other Cys substitutions are known and may be employed (see Weatherill et al, PEDS (2012) 25:321-9) including VL position 99, 100a, and 101 in the antibodies and antigen-binding fragments of this disclosure. In some embodiments, free cysteine residues in the VH and/or VL may be substituted to a non- cysteine residue. [0092] In some embodiments, an anti-PD-L1 antibody is a bispecific antibody. In some embodiments, the anti-PD-L1 bispecific antibody further comprises a second antibody, or an antigen-binding fragment thereof. [0093] In some embodiments, the anti-PD-L1 bispecific an antibody further comprises a targeting antibody, or an antigen-binding fragment thereof. In some embodiments, the targeting antibody is immune cell targeting antibody, or an antigen-binding fragment thereof. In some embodiments the targeting antibody binds the same or different tumor cell than the anti-PD-L1 moiety. In some embodiments the targeting antibody binds a virally infected cell or other cell relevant for treating viral infection. [0094] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-1 and ABL-PD- L1-1A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 1, 108, 215, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 322, 429, and 536, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-1, i.e., comprising the amino acid sequence of SEQ ID NO: 643. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-1, i.e., comprising the amino acid sequence of SEQ ID NO: 857. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-1, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 643 and VH comprising the amino acid sequence of SEQ ID NO: 857. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-1A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 750. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-1A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 964. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-1A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 750 and the VH comprising the amino acid sequence of SEQ ID NO: 964. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-1_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 857; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 643. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-1_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 643; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 857. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-1A_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 964; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 750. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-1A_scFv_VL-VH, i.e., comprising from N-terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 750; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 964. In some embodiments, the anti- PD- L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-1A_scFv_VH-VL, i.e., comprising the amino acid sequence of SEQ ID NO: 1071. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1- 1A_scFv_VL-VH, i.e., comprising the amino acid sequence of SEQ ID NO: 1087. [0095] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-2-1 and ABL-PD- L1-2-1A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 2, 109, 216, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 323, 430, and 537, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-2-1, i.e., comprising the amino acid sequence of SEQ ID NO: 644. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-2-1, i.e., comprising the amino acid sequence of SEQ ID NO: 858. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-2-1, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 644 and VH comprising the amino acid sequence of SEQ ID NO: 858. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-2-1A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 751. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-2-1A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 965. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-2-1A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 751 and the VH comprising the amino acid sequence of SEQ ID NO: 965. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-2-1_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 858; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 644. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-2-1_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 644; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 858. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-2-1_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 965; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 751. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-2A-1_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 751; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 965. [0096] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-2-2 and ABL-PD- L1-2-2A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 3, 110, 217, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 324, 431, and 538, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-2-2, i.e., comprising the amino acid sequence of SEQ ID NO: 645. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-2-2, i.e., comprising the amino acid sequence of SEQ ID NO: 859. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-2-2, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 645 and VH comprising the amino acid sequence of SEQ ID NO: 859. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-2-2A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 752. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-2-2A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 966. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-2-2A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 752 and the VH comprising the amino acid sequence of SEQ ID NO: 966. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-2-2_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 859; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 645. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-2-2_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 645; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 859. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-2-2_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 966; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 752. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-2-2A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 752; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 966. [0097] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-4 and ABL-PD- L1-4A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 4, 111, 218, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 325, 432, and 539, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-4, i.e., comprising the amino acid sequence of SEQ ID NO: 646. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-4, i.e., comprising the amino acid sequence of SEQ ID NO: 860. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-4, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 646 and VH comprising the amino acid sequence of SEQ ID NO: 860. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-4A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 753. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-4A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 967. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-4A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 753 and the VH comprising the amino acid sequence of SEQ ID NO: 967. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-4_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 860; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 646. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-4_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 646; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 860. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-4_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 967; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 753. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-4A_scFv_VL-VH, i.e., comprising from N-terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 753; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 967. In some embodiments, the anti- PD- L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-4A_scFv_VH-VL, i.e., comprising the amino acid sequence of SEQ ID NO: 1085. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1- 4A_scFv_VL-VH, i.e., comprising the amino acid sequence of SEQ ID NO: 1101. [0098] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-5 and ABL-PD- L1-5A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 5, 112, 219, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 326, 433, and 540, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-5, i.e., comprising the amino acid sequence of SEQ ID NO: 647. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-5, i.e., comprising the amino acid sequence of SEQ ID NO: 861. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-5, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 647 and VH comprising the amino acid sequence of SEQ ID NO: 861. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-5A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 754. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-5A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 968. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-5A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 754 and the VH comprising the amino acid sequence of SEQ ID NO: 968. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-5_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 861; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 647. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-5_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 647; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 861. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-5_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 968; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 754. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-5A_scFv_VL-VH, i.e., comprising from N-terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 754; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 968. [0099] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-6 and ABL-PD- L1-6A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 6, 113, 220, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 327, 434, and 541, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-6, i.e., comprising the amino acid sequence of SEQ ID NO: 648. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-6, i.e., comprising the amino acid sequence of SEQ ID NO: 862. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-6, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 648 and VH comprising the amino acid sequence of SEQ ID NO: 862. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-6A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 755. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-6A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 969. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-6A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 755 and the VH comprising the amino acid sequence of SEQ ID NO: 969. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-6_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 862; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 648. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-6_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 648; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 862. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-6_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 969; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 755. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-6A_scFv_VL-VH, i.e., comprising from N-terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 755; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 969. In some embodiments, the anti- PD- L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-6A_scFv_VH-VL, i.e., comprising the amino acid sequence of SEQ ID NO: 1074. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1- 6A_scFv_VL-VH, i.e., comprising the amino acid sequence of SEQ ID NO: 1090. [00100] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-7 and ABL-PD- L1-7A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 7, 114, 221 respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 328, 435, and 542, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL- PD-L1-7, i.e., comprising the amino acid sequence of SEQ ID NO: 649. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-7, i.e., comprising the amino acid sequence of SEQ ID NO: 863. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-7, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 649 and VH comprising the amino acid sequence of SEQ ID NO: 863. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-7A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 756. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody PD-L1-7A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 970. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-7A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 756 and the VH comprising the amino acid sequence of SEQ ID NO: 970. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-7_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 863; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 649. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-7_scFv_VL-VH, i.e., comprising from N-terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 649; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 863. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-7_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 970; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 756. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD- L1-7A_scFv_VL-VH, i.e., comprising from N-terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 756; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 970. In some embodiments, the anti- PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-6A_scFv_VH-VL, i.e., comprising the amino acid sequence of SEQ ID NO: 1074. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-6A_scFv_VL-VH, i.e., comprising the amino acid sequence of SEQ ID NO: 1090. [00101] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-8 and ABL-PD- L1-8A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 8, 115, 222, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 329, 436, and 543, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-8, i.e., comprising the amino acid sequence of SEQ ID NO: 650. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-8, i.e., comprising the amino acid sequence of SEQ ID NO: 864. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-8, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 650 and VH comprising the amino acid sequence of SEQ ID NO: 864. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-8A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 757. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-8A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 971. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-8A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 757 and the VH comprising the amino acid sequence of SEQ ID NO: 971. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-8_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 864; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 650. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-8_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 650; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 864. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-8_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 971; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 757. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-8A_scFv_VL-VH, i.e., comprising from N-terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 757; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 971. In some embodiments, the anti- PD- L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-8A_scFv_VH-VL, i.e., comprising the amino acid sequence of SEQ ID NO: 1077. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1- 8A_scFv_VL-VH, i.e., comprising the amino acid sequence of SEQ ID NO: 1093. [00102] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-9 and ABL-PD- L1-9A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 9, 116, 223, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 330, 437, and 544, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-9, i.e., comprising the amino acid sequence of SEQ ID NO: 651. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-9, i.e., comprising the amino acid sequence of SEQ ID NO: 865. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-9, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 651 and VH comprising the amino acid sequence of SEQ ID NO: 865. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-9A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 758. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-9A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 972. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-9A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 758 and the VH comprising the amino acid sequence of SEQ ID NO: 972. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-9_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 865; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 651. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-9_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 651; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 865. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-9_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 972; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 758. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-9A_scFv_VL-VH, i.e., comprising from N-terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 758; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 972. In some embodiments, the anti- PD- L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-9A_scFv_VH-VL, i.e., comprising the amino acid sequence of SEQ ID NO: 1080. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1- 9A_scFv_VL-VH, i.e., comprising the amino acid sequence of SEQ ID NO: 1096. [00103] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-10 and ABL-PD- L1-10A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 10, 117, 224, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 331, 438, and 545, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-10, i.e., comprising the amino acid sequence of SEQ ID NO: 652. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-10, i.e., comprising the amino acid sequence of SEQ ID NO: 866. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-10, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 652 and VH comprising the amino acid sequence of SEQ ID NO: 866. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-10A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 759. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-10A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 973. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-10A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 759 and the VH comprising the amino acid sequence of SEQ ID NO: 973. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-10_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 866; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 652. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-10_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 652; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 866. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-10_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 973; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 759. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-10A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 759; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 973. [00104] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-11 and ABL-PD- L1-11A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 11, 118, 225, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 332, 439, and 546, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-11, i.e., comprising the amino acid sequence of SEQ ID NO: 653. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-11, i.e., comprising the amino acid sequence of SEQ ID NO: 867. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-11, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 653 and VH comprising the amino acid sequence of SEQ ID NO: 867. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-11A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 760. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-11A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 974. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-11A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 760 and the VH comprising the amino acid sequence of SEQ ID NO: 974. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-11_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 867; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 653. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-11_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 653; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 867. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-11_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 974; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 760. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-11A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 760; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 974. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1- 11A_scFv_VH-VL, i.e., comprising the amino acid sequence of SEQ ID NO: 1082. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-11A_scFv_VL-VH, i.e., comprising the amino acid sequence of SEQ ID NO: 1098. [00105] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-12 and ABL-PD- L1-12A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 12, 119, 226, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 333, 440, and 547, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-12, i.e., comprising the amino acid sequence of SEQ ID NO: 654. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-12, i.e., comprising the amino acid sequence of SEQ ID NO: 868. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-12, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 654 and VH comprising the amino acid sequence of SEQ ID NO: 868. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-12A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 761. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-12A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 975. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-12A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 761 and the VH comprising the amino acid sequence of SEQ ID NO: 975. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-12_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 868; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 654. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-12_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 654; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 868. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-12_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 975; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 761. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-12A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 761; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 975. [00106] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-13 and ABL-PD- L1-13A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 13, 120, 227, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 334, 441, and 548, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-13, i.e., comprising the amino acid sequence of SEQ ID NO: 655. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-13, i.e., comprising the amino acid sequence of SEQ ID NO: 869. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-13, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 655 and VH comprising the amino acid sequence of SEQ ID NO: 869. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-13A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 762. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-13A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 976. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-13A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 762 and the VH comprising the amino acid sequence of SEQ ID NO: 976. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-13_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 869; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 655. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-13_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 655; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 869. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-13_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 976; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 762. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-13A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 762; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 976. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1- 13A_scFv_VH-VL, i.e., comprising the amino acid sequence of SEQ ID NO: 1083. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-13A_scFv_VL-VH, i.e., comprising the amino acid sequence of SEQ ID NO: 1099. [00107] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-14 and ABL-PD- L1-14A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 14, 121, 228, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 335, 442, and 549, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-14, i.e., comprising the amino acid sequence of SEQ ID NO: 656. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-14, i.e., comprising the amino acid sequence of SEQ ID NO: 870. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-14, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 656 and VH comprising the amino acid sequence of SEQ ID NO: 870. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-14A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 763. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-14A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 977. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-14A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 763 and the VH comprising the amino acid sequence of SEQ ID NO: 977. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-14_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 870; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 656. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-14_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 656; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 870. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-14_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 977; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 763. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-14A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 763; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 977. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1- 14A_scFv_VH-VL, i.e., comprising the amino acid sequence of SEQ ID NO: 1076. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-13A_scFv_VL-VH, i.e., comprising the amino acid sequence of SEQ ID NO: 1092. [00108] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-15 and ABL-PD- L1-15A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 15, 122, 229, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 336, 443, and 550, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-15, i.e., comprising the amino acid sequence of SEQ ID NO: 657. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-15, i.e., comprising the amino acid sequence of SEQ ID NO: 871. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-15, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 657 and VH comprising the amino acid sequence of SEQ ID NO: 871. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-15A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 764. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-15A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 978. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-15A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 764 and the VH comprising the amino acid sequence of SEQ ID NO: 978. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-15_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 871; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 657. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-15_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 657; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 871. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-15_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 978; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 764. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-15A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 764; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 978. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1- 15A_scFv_VH-VL, i.e., comprising the amino acid sequence of SEQ ID NO: 1081. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-15A_scFv_VL-VH, i.e., comprising the amino acid sequence of SEQ ID NO: 1097. [00109] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-16 and ABL-PD- L1-16A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 16, 123, 230, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 337, 444, and 551, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-16, i.e., comprising the amino acid sequence of SEQ ID NO: 658. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-16, i.e., comprising the amino acid sequence of SEQ ID NO: 872. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-16, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 658 and VH comprising the amino acid sequence of SEQ ID NO: 872. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-16A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 765. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-16A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 979. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-16A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 765 and the VH comprising the amino acid sequence of SEQ ID NO: 979. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-16_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 872; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 658. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-16_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 658; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 872. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-16_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 979; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 765. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-16A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 765; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 979. [00110] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-17 and ABL-PD- L1-17A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 17, 124, 231, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 338, 445, and 552, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-17, i.e., comprising the amino acid sequence of SEQ ID NO: 659. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-17, i.e., comprising the amino acid sequence of SEQ ID NO: 873. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-17, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 659 and VH comprising the amino acid sequence of SEQ ID NO: 873. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-17A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 766. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-17A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 980. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-17A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 766 and the VH comprising the amino acid sequence of SEQ ID NO: 980. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-17_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 873; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 659. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-17_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 659; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 873. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-17_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 980; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 766. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-17A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 766; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 980. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1- 17A_scFv_VH-VL, i.e., comprising the amino acid sequence of SEQ ID NO: 1084. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-17A_scFv_VL-VH, i.e., comprising the amino acid sequence of SEQ ID NO: 1100. [00111] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-18 and ABL-PD- L1-18A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 18, 125, 232, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 339, 446, and 553, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-18, i.e., comprising the amino acid sequence of SEQ ID NO: 660. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-18, i.e., comprising the amino acid sequence of SEQ ID NO: 874. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-18, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 660 and VH comprising the amino acid sequence of SEQ ID NO: 874. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-18A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 767. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-18A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 981. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-18A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 767 and the VH comprising the amino acid sequence of SEQ ID NO: 981. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-18_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 874; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 660. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-18_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 660; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 874. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-18_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 981; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 767. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-18A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 767; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 981. [00112] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-19 and ABL-PD- L1-19A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 19, 126, 233, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 340, 447, and 554, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-19, i.e., comprising the amino acid sequence of SEQ ID NO: 661. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-19, i.e., comprising the amino acid sequence of SEQ ID NO: 875. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-19, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 661 and VH comprising the amino acid sequence of SEQ ID NO: 875. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-19A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 768. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-19A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 982. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-19A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 768 and the VH comprising the amino acid sequence of SEQ ID NO: 982. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-19_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 875; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 661. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-19_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 661; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 875. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-19_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 982; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 768. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-19A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 768; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 982. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1- 19A_scFv_VH-VL, i.e., comprising the amino acid sequence of SEQ ID NO: 1086. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-19A_scFv_VL-VH, i.e., comprising the amino acid sequence of SEQ ID NO: 1102. [00113] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-20-1 and ABL- PD-L1-20-1A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 20, 127, 234, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 341, 448, and 555, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-20-1, i.e., comprising the amino acid sequence of SEQ ID NO: 662. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-20-1, i.e., comprising the amino acid sequence of SEQ ID NO: 876. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-20-1, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 662 and VH comprising the amino acid sequence of SEQ ID NO: 876. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VL of antibody ABL-PD-L1-20-1A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 769. In some embodiments, the anti-PD- L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody PD-L1-20- 1A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 983. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-20-1A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 769 and the VH comprising the amino acid sequence of SEQ ID NO: 983. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-20-1_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 876; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 662. In some embodiments, the anti-PD- L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-20-1_scFv_VL-VH, i.e., comprising from N-terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 662; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 876. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-20-1_VH-VL, i.e., comprising from N-terminus to C- terminus, a VH comprising the amino acid sequence of SEQ ID NO: 983; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 769. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-20- 1A_scFv_VL-VH, i.e., comprising from N-terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 769; a linker comprising the amino acid sequence of (Gly-Gly- Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 983. [00114] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-20-2 and ABL- PD-L1-20-2A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 21, 128, 235, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 342, 449, and 556, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-20-2, i.e., comprising the amino acid sequence of SEQ ID NO: 663. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-20-2, i.e., comprising the amino acid sequence of SEQ ID NO: 877. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-20-2, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 663 and VH comprising the amino acid sequence of SEQ ID NO: 877. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VL of antibody ABL-PD-L1-20-2A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 770. In some embodiments, the anti-PD- L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody PD-L1-20- 2A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 984. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-20-2A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 770 and the VH comprising the amino acid sequence of SEQ ID NO: 984. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-20-2_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 877; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 663. In some embodiments, the anti-PD- L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-20-2_scFv_VL-VH, i.e., comprising from N-terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 663; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 877. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-20-2_VH-VL, i.e., comprising from N-terminus to C- terminus, a VH comprising the amino acid sequence of SEQ ID NO: 984; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 770. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-20- 2A_scFv_VL-VH, i.e., comprising from N-terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 770; a linker comprising the amino acid sequence of (Gly-Gly- Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 984. [00115] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-22 and ABL-PD- L1-22A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 22, 129, 236, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 343, 450, and 557, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-22, i.e., comprising the amino acid sequence of SEQ ID NO: 664. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-22, i.e., comprising the amino acid sequence of SEQ ID NO: 878. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-22, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 664 and VH comprising the amino acid sequence of SEQ ID NO: 878. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-22A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 771. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-22A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 985. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-22A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 771 and the VH comprising the amino acid sequence of SEQ ID NO: 985. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-22_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 878; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 664. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-22_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 664; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 878. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-22_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 985; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 771. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-22A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 771; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 985. [00116] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-23 and ABL-PD- L1-23A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 23, 130, 237, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 344, 451, and 558, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-23, i.e., comprising the amino acid sequence of SEQ ID NO: 665. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-23, i.e., comprising the amino acid sequence of SEQ ID NO: 879. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-23, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 665 and VH comprising the amino acid sequence of SEQ ID NO: 879. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-23A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 772. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-23A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 986. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-23A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 772 and the VH comprising the amino acid sequence of SEQ ID NO: 986. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-23_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 879; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 665. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-23_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 665; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 879. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-23_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 986; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 772. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-23A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 772; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 986. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1- 23A_scFv_VH-VL, i.e., comprising the amino acid sequence of SEQ ID NO: 1079. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-23A_scFv_VL-VH, i.e., comprising the amino acid sequence of SEQ ID NO: 1095. [00117] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-24 and ABL-PD- L1-24A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 24, 131, 238, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 345, 452, and 559, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-24, i.e., comprising the amino acid sequence of SEQ ID NO: 666. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-24, i.e., comprising the amino acid sequence of SEQ ID NO: 880. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-24, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 666 and VH comprising the amino acid sequence of SEQ ID NO: 880. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-24A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 773. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-24A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 987. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-24A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 773 and the VH comprising the amino acid sequence of SEQ ID NO: 987. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-24_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 880; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 666. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-24_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 666; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 880. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-24_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 987; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 773. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-24A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 773; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 987. [00118] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-25 and ABL-PD- L1-25A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 25, 132, 239, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 346, 453, and 560, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-25, i.e., comprising the amino acid sequence of SEQ ID NO: 667. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-25, i.e., comprising the amino acid sequence of SEQ ID NO: 881. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-25, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 667 and VH comprising the amino acid sequence of SEQ ID NO: 881. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-25A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 774. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-25A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 988. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-25A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 774 and the VH comprising the amino acid sequence of SEQ ID NO: 988. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-25_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 881; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 667. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-25_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 667; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 881. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-25_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 988; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 774. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-25A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 774; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 988. [00119] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-26 and ABL-PD- L1-26A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 26, 133, 240, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 347, 454, and 561, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-26, i.e., comprising the amino acid sequence of SEQ ID NO: 668. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-26, i.e., comprising the amino acid sequence of SEQ ID NO: 882. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-26, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 668 and VH comprising the amino acid sequence of SEQ ID NO: 882. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-26A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 775. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-26A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 989. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-26A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 775 and the VH comprising the amino acid sequence of SEQ ID NO: 989. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-26_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 882; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 668. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-26_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 668; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 882. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-26_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 989; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 775. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-26A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 775; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 989. [00120] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-27 and ABL-PD- L1-27A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 27, 134, 241, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 348, 455, and 562, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-27, i.e., comprising the amino acid sequence of SEQ ID NO: 669. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-27, i.e., comprising the amino acid sequence of SEQ ID NO: 883. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-27, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 669 and VH comprising the amino acid sequence of SEQ ID NO: 883. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-27A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 776. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-27A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 990. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-27A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 776 and the VH comprising the amino acid sequence of SEQ ID NO: 990. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-27_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 883; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 669. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-27_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 669; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 883. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-27_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 990; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 776. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-27A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 776; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 990. [00121] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-28 and ABL-PD- L1-28A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 28, 135, 242, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 349, 456, and 563, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-28, i.e., comprising the amino acid sequence of SEQ ID NO: 670. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-28, i.e., comprising the amino acid sequence of SEQ ID NO: 884. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-28, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 670 and VH comprising the amino acid sequence of SEQ ID NO: 884. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-28A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 777. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-28A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 991. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-28A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 777 and the VH comprising the amino acid sequence of SEQ ID NO: 991. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-28_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 884; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 670. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-28_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 670; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 884. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-28_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 991; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 777. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-28A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 777; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 991. [00122] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-29 and ABL-PD- L1-29A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 29, 136, 243, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 350, 457, and 564, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-29, i.e., comprising the amino acid sequence of SEQ ID NO: 671. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-29, i.e., comprising the amino acid sequence of SEQ ID NO: 885. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-29, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 671 and VH comprising the amino acid sequence of SEQ ID NO: 885. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-29A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 778. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-29A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 992. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-29A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 778 and the VH comprising the amino acid sequence of SEQ ID NO: 992. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-29_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 885; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 671. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-29_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 671; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 885. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-29_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 992; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 778. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-29A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 778; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 992. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1- 29A_scFv_VH-VL, i.e., comprising the amino acid sequence of SEQ ID NO: 1075. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-29A_scFv_VL-VH, i.e., comprising the amino acid sequence of SEQ ID NO: 1091. [00123] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-30 and ABL-PD- L1-30A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 30, 137, 244, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 351, 458, and 565, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-30, i.e., comprising the amino acid sequence of SEQ ID NO: 672. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-30, i.e., comprising the amino acid sequence of SEQ ID NO: 886. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-30, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 672 and VH comprising the amino acid sequence of SEQ ID NO: 886. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-30A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 779. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-30A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 993. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-30A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 779 and the VH comprising the amino acid sequence of SEQ ID NO: 993. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-30_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 886; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 672. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-30_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 672; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 886. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-30_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 993; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 779. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-30A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 779; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 993. [00124] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-31 and ABL-PD- L1-31A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 31, 138, 245, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 352, 459, and 566, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-31, i.e., comprising the amino acid sequence of SEQ ID NO: 673. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-31, i.e., comprising the amino acid sequence of SEQ ID NO: 887. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-31, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 673 and VH comprising the amino acid sequence of SEQ ID NO: 887. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-31A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 780. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-31A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 994. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-31A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 780 and the VH comprising the amino acid sequence of SEQ ID NO: 994. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-31_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 887; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 673. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-31_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 673; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 887. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-31_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 994; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 780. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-31A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 780; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 994. [00125] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-32 and ABL-PD- L1-32A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 32, 139, 246, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 353, 460, and 567, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-32, i.e., comprising the amino acid sequence of SEQ ID NO: 674. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-32, i.e., comprising the amino acid sequence of SEQ ID NO: 888. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-32, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 674 and VH comprising the amino acid sequence of SEQ ID NO: 888. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-32A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 781. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-32A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 995. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-32A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 781 and the VH comprising the amino acid sequence of SEQ ID NO: 995. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-32_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 888; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 674. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-32_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 674; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 888. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-32_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 995; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 781. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-32A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 781; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 995. [00126] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-33 and ABL-PD- L1-33A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 33, 140, 247, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 354, 461, and 568, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-33, i.e., comprising the amino acid sequence of SEQ ID NO: 675. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-33, i.e., comprising the amino acid sequence of SEQ ID NO: 889. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-33, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 675 and VH comprising the amino acid sequence of SEQ ID NO: 889. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-33A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 782. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-33A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 996. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-33A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 782 and the VH comprising the amino acid sequence of SEQ ID NO: 996. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-33_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 889; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 675. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-33_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 675; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 889. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-33_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 996; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 782. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-33A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 782; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 996. [00127] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-34 and ABL-PD- L1-34A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 34, 141, 248, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 355, 462, and 569, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-34, i.e., comprising the amino acid sequence of SEQ ID NO: 676. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-34, i.e., comprising the amino acid sequence of SEQ ID NO: 890. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-34, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 676 and VH comprising the amino acid sequence of SEQ ID NO: 890. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-34A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 783. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-34A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 997. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-34A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 783 and the VH comprising the amino acid sequence of SEQ ID NO: 997. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-34_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 890; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 676. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-34_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 676; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 890. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-34_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 997; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 783. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-34A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 783; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 997. [00128] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-35 and ABL-PD- L1-35A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 35, 142, 249, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 356, 463, and 570, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-35, i.e., comprising the amino acid sequence of SEQ ID NO: 677. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-35, i.e., comprising the amino acid sequence of SEQ ID NO: 891. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-35, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 677 and VH comprising the amino acid sequence of SEQ ID NO: 891. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-35A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 784. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-35A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 998. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-35A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 784 and the VH comprising the amino acid sequence of SEQ ID NO: 998. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-35_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 891; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 677. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-35_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 677; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 891. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-35_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 998; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 784. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-35A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 784; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 998. [00129] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-36 and ABL-PD- L1-36A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 36, 143, 250, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 357, 464, and 571, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-36, i.e., comprising the amino acid sequence of SEQ ID NO: 678. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-36, i.e., comprising the amino acid sequence of SEQ ID NO: 892. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-36, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 678 and VH comprising the amino acid sequence of SEQ ID NO: 892. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-36A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 785. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-36A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 999. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1-36A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 785 and the VH comprising the amino acid sequence of SEQ ID NO: 999. In some embodiments of this disclosure, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-36_scFv_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 892; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 678. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-36_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 678; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 892. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-36_VH- VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 999; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 785. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises PD-L1-36A_scFv_VL-VH, i.e., comprising from N-terminus to C- terminus, a VL comprising the amino acid sequence of SEQ ID NO: 785; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 999. [00130] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-37 and ABL-PD- L1-37A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 37, 144, 251, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 358, 465, and 572, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-37, i.e., comprising the amino acid sequence of SEQ ID NO: 679. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-37, i.e., comprising the amino acid sequence of SEQ ID NO: 893. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-37, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 679 and VH comprising the amino acid sequence of SEQ ID NO: 893. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-37A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 786. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-37A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1000. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 37A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 786 and the VH comprising the amino acid sequence of SEQ ID NO: 1000. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-37_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 893; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 679. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-37_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 679; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 893. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-37_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1000; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 786. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-37A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 786; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1000. [00131] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-38 and ABL-PD- L1-38A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 38, 145, 252, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 359, 466, and 573, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-38, i.e., comprising the amino acid sequence of SEQ ID NO: 680. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-38, i.e., comprising the amino acid sequence of SEQ ID NO: 894. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-38, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 680 and VH comprising the amino acid sequence of SEQ ID NO: 894. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-38A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 787. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-38A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1001. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 38A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 787 and the VH comprising the amino acid sequence of SEQ ID NO: 1001. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-38_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 894; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 680. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-38_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 680; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 894. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-38_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1001; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 787. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-38A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 787; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1001. [00132] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-39 and ABL-PD- L1-39A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 39, 146, 253, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 360, 467, and 574, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-39, i.e., comprising the amino acid sequence of SEQ ID NO: 681. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-39, i.e., comprising the amino acid sequence of SEQ ID NO: 895. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-39, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 681 and VH comprising the amino acid sequence of SEQ ID NO: 895. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-39A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 788. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-39A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1002. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 39A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 788 and the VH comprising the amino acid sequence of SEQ ID NO: 1002. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-39_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 895; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 681. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-39_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 681; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 895. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-39_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1002; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 788. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-39A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 788; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1002. [00133] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-40 and ABL-PD- L1-40A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 40, 147, 254, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 361, 468, and 575, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-40, i.e., comprising the amino acid sequence of SEQ ID NO: 682. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-40, i.e., comprising the amino acid sequence of SEQ ID NO: 896. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-40, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 682 and VH comprising the amino acid sequence of SEQ ID NO: 896. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-40A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 789. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-40A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1003. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 40A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 789 and the VH comprising the amino acid sequence of SEQ ID NO: 1003. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-40_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 896; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 682. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-40_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 682; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 896. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-40_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1003; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 789. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-40A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 789; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1003. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-40A_scFv_VH-VL, i.e., comprising the amino acid sequence of SEQ ID NO: 1072. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-40A_scFv_VL-VH, i.e., comprising the amino acid sequence of SEQ ID NO: 1088. [00134] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-41 and ABL-PD- L1-41A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 41, 148, 255, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 362, 469, and 576, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-41, i.e., comprising the amino acid sequence of SEQ ID NO: 683. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-41, i.e., comprising the amino acid sequence of SEQ ID NO: 897. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-41, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 683 and VH comprising the amino acid sequence of SEQ ID NO: 897. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-41A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 790. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-41A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1004. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 41A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 790 and the VH comprising the amino acid sequence of SEQ ID NO: 1004. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-41_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 897; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 683. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-41_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 683; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 897. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-41_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1004; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 790. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-41A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 790; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1004. [00135] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-42 and ABL-PD- L1-42A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 42, 149, 256, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 363, 470, and 577, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-42, i.e., comprising the amino acid sequence of SEQ ID NO: 684. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-42, i.e., comprising the amino acid sequence of SEQ ID NO: 898. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-42, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 684 and VH comprising the amino acid sequence of SEQ ID NO: 898. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-42A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 791. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-42A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1005. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 42A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 791 and the VH comprising the amino acid sequence of SEQ ID NO: 1005. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-42_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 898; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 684. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-42_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 684; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 898. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-42_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1005; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 791. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-42A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 791; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1005. [00136] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-43 and ABL-PD- L1-43A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 43, 150, 257, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 364, 471, and 578, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-43, i.e., comprising the amino acid sequence of SEQ ID NO: 685. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-43, i.e., comprising the amino acid sequence of SEQ ID NO: 899. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-43, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 685 and VH comprising the amino acid sequence of SEQ ID NO: 899. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-43A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 792. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-43A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1006. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 43A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 792 and the VH comprising the amino acid sequence of SEQ ID NO: 1006. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-43_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 899; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 685. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-43_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 685; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 899. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-43_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1006; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 792. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-43A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 792; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1006. [00137] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-44 and ABL-PD- L1-44A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 44, 151, 258, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 365, 472, and 579, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-44, i.e., comprising the amino acid sequence of SEQ ID NO: 686. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-44, i.e., comprising the amino acid sequence of SEQ ID NO: 900. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-44, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 686 and VH comprising the amino acid sequence of SEQ ID NO: 900. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-44A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 793. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-44A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1007. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 44A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 793 and the VH comprising the amino acid sequence of SEQ ID NO: 1007. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-44_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 900; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 686. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-44_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 686; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 900. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-44_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1007; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 793. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-44A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 793; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1007. [00138] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-45 and ABL-PD- L1-45A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 45, 152, 259, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 366, 473, and 580, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-45, i.e., comprising the amino acid sequence of SEQ ID NO: 687. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-45, i.e., comprising the amino acid sequence of SEQ ID NO: 901. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-45, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 687 and VH comprising the amino acid sequence of SEQ ID NO: 901. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-45A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 794. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-45A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1008. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 45A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 794 and the VH comprising the amino acid sequence of SEQ ID NO: 1008. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-45_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 901; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 687. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-45_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 687; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 901. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-45_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1008; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 794. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-45A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 794; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1008. [00139] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-46 and ABL-PD- L1-46A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 46, 153, 260, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 367, 474, and 581, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-46, i.e., comprising the amino acid sequence of SEQ ID NO: 688. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-46, i.e., comprising the amino acid sequence of SEQ ID NO: 902. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-46, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 688 and VH comprising the amino acid sequence of SEQ ID NO: 902. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-46A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 795. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-46A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1009. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 46A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 795 and the VH comprising the amino acid sequence of SEQ ID NO: 1009. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-46_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 902; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 688. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-46_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 688; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 902. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-46_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1009; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 795. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-46A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 795; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1009. [00140] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-47 and ABL-PD- L1-47A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 47, 154, 261, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 368, 475, and 582, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-47, i.e., comprising the amino acid sequence of SEQ ID NO: 689. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-47, i.e., comprising the amino acid sequence of SEQ ID NO: 903. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-47, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 689 and VH comprising the amino acid sequence of SEQ ID NO: 903. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-47A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 796. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-47A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1010. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 47A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 796 and the VH comprising the amino acid sequence of SEQ ID NO: 1010. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-47_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 903; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 689. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-47_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 689; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 903. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-47_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1010; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 796. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-47A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 796; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1010. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-47A_scFv_VH-VL, i.e., comprising the amino acid sequence of SEQ ID NO: 1078. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-47A_scFv_VL-VH, i.e., comprising the amino acid sequence of SEQ ID NO: 1094. [00141] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-48 and ABL-PD- L1-48A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 48, 155, 262, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 369, 476, and 583, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-48, i.e., comprising the amino acid sequence of SEQ ID NO: 690. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-48, i.e., comprising the amino acid sequence of SEQ ID NO: 904. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-48, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 690 and VH comprising the amino acid sequence of SEQ ID NO: 904. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-48A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 797. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-48A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1011. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 48A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 797 and the VH comprising the amino acid sequence of SEQ ID NO: 1011. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-48_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 904; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 690. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-48_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 690; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 904. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-48_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1011; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 797. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-48A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 797; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1011. [00142] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-49 and ABL-PD- L1-49A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 49, 156, 263, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 370, 477, and 584, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-49, i.e., comprising the amino acid sequence of SEQ ID NO: 691. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-49, i.e., comprising the amino acid sequence of SEQ ID NO: 905. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-49, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 691 and VH comprising the amino acid sequence of SEQ ID NO: 905. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-49A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 798. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-49A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1012. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 49A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 798 and the VH comprising the amino acid sequence of SEQ ID NO: 1012. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-49_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 905; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 691. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-49_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 691; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 905. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-49_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1012; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 798. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-49A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 798; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1012. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-49A_scFv_VH-VL, i.e., comprising the amino acid sequence of SEQ ID NO: 1073. In some embodiments, the anti- PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD-L1-49A_scFv_VL-VH, i.e., comprising the amino acid sequence of SEQ ID NO: 1089. [00143] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-50 and ABL-PD- L1-50A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 50, 157, 264, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 371, 478, and 585, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-50, i.e., comprising the amino acid sequence of SEQ ID NO: 692. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-50, i.e., comprising the amino acid sequence of SEQ ID NO: 906. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-50, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 692 and VH comprising the amino acid sequence of SEQ ID NO: 906. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-50A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 799. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-50A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1013. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 50A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 799 and the VH comprising the amino acid sequence of SEQ ID NO: 1013. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-50_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 906; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 692. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-50_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 692; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 906. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-50_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1013; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 799. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-50A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 799; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1013. [00144] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-51 and ABL-PD- L1-51A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 51, 158, 265, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 372, 479, and 586, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-51, i.e., comprising the amino acid sequence of SEQ ID NO: 693. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-51, i.e., comprising the amino acid sequence of SEQ ID NO: 907. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-51, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 693 and VH comprising the amino acid sequence of SEQ ID NO: 907. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-51A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 800. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-51A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1014. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 51A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 800 and the VH comprising the amino acid sequence of SEQ ID NO: 1014. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-51_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 907; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 693. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-51_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 693; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 907. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-51_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1014; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 800. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-51A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 800; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1014. [00145] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-52 and ABL-PD- L1-52A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 52, 159, 266, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 373, 480, and 587, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-52, i.e., comprising the amino acid sequence of SEQ ID NO: 694. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-52, i.e., comprising the amino acid sequence of SEQ ID NO: 908. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-52, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 694 and VH comprising the amino acid sequence of SEQ ID NO: 908. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-52A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 801. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-52A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1015. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 52A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 801 and the VH comprising the amino acid sequence of SEQ ID NO: 1015. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-52_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 908; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 694. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-52_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 694; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 908. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-52_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1015; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 801. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-52A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 801; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1015. [00146] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-53 and ABL-PD- L1-53A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 53, 160, 267, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 374, 481, and 588, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-53, i.e., comprising the amino acid sequence of SEQ ID NO: 695. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-53, i.e., comprising the amino acid sequence of SEQ ID NO: 909. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-53, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 695 and VH comprising the amino acid sequence of SEQ ID NO: 909. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-53A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 802. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-53A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1016. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 53A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 802 and the VH comprising the amino acid sequence of SEQ ID NO: 1016. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-53_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 909; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 695. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-53_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 695; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 909. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-53_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1016; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 802. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-53A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 802; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1016. [00147] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-54 and ABL-PD- L1-54A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 54, 161, 268, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 375, 482, and 589, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-54, i.e., comprising the amino acid sequence of SEQ ID NO: 696. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-54, i.e., comprising the amino acid sequence of SEQ ID NO: 910. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-54, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 696 and VH comprising the amino acid sequence of SEQ ID NO: 910. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-54A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 803. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-54A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1017. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 54A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 803 and the VH comprising the amino acid sequence of SEQ ID NO: 1017. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-54_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 910; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 696. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-54_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 696; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 910. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-54_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1017; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 803. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-54A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 803; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1017. [00148] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-55 and ABL-PD- L1-55A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 55, 162, 269, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 376, 483, and 590, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-55, i.e., comprising the amino acid sequence of SEQ ID NO: 697. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-55, i.e., comprising the amino acid sequence of SEQ ID NO: 911. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-55, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 697 and VH comprising the amino acid sequence of SEQ ID NO: 911. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-55A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 804. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-55A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1018. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 55A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 804 and the VH comprising the amino acid sequence of SEQ ID NO: 1018. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-55_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 911; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 697. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-55_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 697; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 911. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-55_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1018; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 804. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-55A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 804; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1018. [00149] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-56 and ABL-PD- L1-56A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 56, 163, 270, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 377, 484, and 591, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-56, i.e., comprising the amino acid sequence of SEQ ID NO: 698. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-56, i.e., comprising the amino acid sequence of SEQ ID NO: 912. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-56, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 698 and VH comprising the amino acid sequence of SEQ ID NO: 912. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-56A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 805. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-56A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1019. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 56A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 805 and the VH comprising the amino acid sequence of SEQ ID NO: 1019. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-56_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 912; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 698. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-56_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 698; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 912. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-56_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1019; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 805. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-56A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 805; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1019. [00150] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-57 and ABL-PD- L1-57A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 57, 164, 271, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 378, 485, and 592, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-57, i.e., comprising the amino acid sequence of SEQ ID NO: 699. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-57, i.e., comprising the amino acid sequence of SEQ ID NO: 913. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-57, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 699 and VH comprising the amino acid sequence of SEQ ID NO: 913. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-57A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 806. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-57A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1020. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 57A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 806 and the VH comprising the amino acid sequence of SEQ ID NO: 1020. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-57_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 913; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 699. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-57_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 699; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 913. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-57_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1020; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 806. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-57A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 806; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1020. [00151] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-58 and ABL-PD- L1-58A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 58, 165, 272, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 379, 486, and 593, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-58, i.e., comprising the amino acid sequence of SEQ ID NO: 700. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-58, i.e., comprising the amino acid sequence of SEQ ID NO: 914. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-58, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 700 and VH comprising the amino acid sequence of SEQ ID NO: 914. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-58A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 807. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-58A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1021. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 58A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 807 and the VH comprising the amino acid sequence of SEQ ID NO: 1021. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-58_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 914; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 700. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-58_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 700; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 914. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-58_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1021; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 807. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-58A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 807; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1021. [00152] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-59 and ABL-PD- L1-59A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 59, 166, 273, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 380, 487, and 594, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-59, i.e., comprising the amino acid sequence of SEQ ID NO: 701. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-59, i.e., comprising the amino acid sequence of SEQ ID NO: 915. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-59, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 701 and VH comprising the amino acid sequence of SEQ ID NO: 915. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-59A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 808. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-59A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1022. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 59A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 808 and the VH comprising the amino acid sequence of SEQ ID NO: 1022. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-59_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 915; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 701. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-59_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 701; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 915. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-59_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1022; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 808. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-59A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 808; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1022. [00153] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-60 and ABL-PD- L1-60A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 60, 167, 274, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 381, 488, and 595, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-60, i.e., comprising the amino acid sequence of SEQ ID NO: 702. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-60, i.e., comprising the amino acid sequence of SEQ ID NO: 916. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-60, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 702 and VH comprising the amino acid sequence of SEQ ID NO: 916. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-60A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 809. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-60A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1023. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 60A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 809 and the VH comprising the amino acid sequence of SEQ ID NO: 1023. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-60_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 916; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 702. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-60_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 702; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 916. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-60_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1023; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 809. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-60A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 809; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1023. [00154] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-61 and ABL-PD- L1-61A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 61, 168, 275, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 382, 489, and 596, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-61, i.e., comprising the amino acid sequence of SEQ ID NO: 703. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-61, i.e., comprising the amino acid sequence of SEQ ID NO: 917. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-61, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 703 and VH comprising the amino acid sequence of SEQ ID NO: 917. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-61A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 810. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-61A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1024. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 61A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 810 and the VH comprising the amino acid sequence of SEQ ID NO: 1024. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-61_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 917; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 703. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-61_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 703; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 917. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-61_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1024; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 810. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-61A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 810; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1024. [00155] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-62 and ABL-PD- L1-62A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 62, 169, 276, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 383, 490, and 597, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-62, i.e., comprising the amino acid sequence of SEQ ID NO: 704. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-62, i.e., comprising the amino acid sequence of SEQ ID NO: 918. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-62, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 704 and VH comprising the amino acid sequence of SEQ ID NO: 918. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-62A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 811. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-62A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1025. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 62A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 811 and the VH comprising the amino acid sequence of SEQ ID NO: 1025. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-62_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 918; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 704. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-62_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 704; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 918. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-62_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1025; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 811. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-62A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 811; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1025. [00156] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-63 and ABL-PD- L1-63A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 63, 170, 277, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 384, 491, and 598, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-63, i.e., comprising the amino acid sequence of SEQ ID NO: 705. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-63, i.e., comprising the amino acid sequence of SEQ ID NO: 919. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-63, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 705 and VH comprising the amino acid sequence of SEQ ID NO: 919. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-63A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 812. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-63A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1026. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 63A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 812 and the VH comprising the amino acid sequence of SEQ ID NO: 1026. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-63_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 919; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 705. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-63_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 705; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 919. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-63_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1026; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 812. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-63A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 812; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1026. [00157] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-64 and ABL-PD- L1-64A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 64, 171, 278, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 385, 492, and 599, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-64, i.e., comprising the amino acid sequence of SEQ ID NO: 706. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-64, i.e., comprising the amino acid sequence of SEQ ID NO: 920. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-64, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 706 and VH comprising the amino acid sequence of SEQ ID NO: 920. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-64A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 813. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-64A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1027. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 64A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 813 and the VH comprising the amino acid sequence of SEQ ID NO: 1027. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-64_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 920; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 706. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-64_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 706; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 920. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-64_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1027; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 813. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-64A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 813; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1027. [00158] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-65 and ABL-PD- L1-65A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 65, 172, 279, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 386, 493, and 600, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-65, i.e., comprising the amino acid sequence of SEQ ID NO: 707. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-65, i.e., comprising the amino acid sequence of SEQ ID NO: 921. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-65, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 707 and VH comprising the amino acid sequence of SEQ ID NO: 921. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-65A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 814. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-65A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1028. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 65A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 814 and the VH comprising the amino acid sequence of SEQ ID NO: 1028. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-65_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 921; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 707. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-65_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 707; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 921. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-65_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1028; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 814. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-65A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 814; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1028. [00159] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-66 and ABL-PD- L1-66A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 66, 173, 280, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 387, 494, and 601, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-66, i.e., comprising the amino acid sequence of SEQ ID NO: 708. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-66, i.e., comprising the amino acid sequence of SEQ ID NO: 922. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-66, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 708 and VH comprising the amino acid sequence of SEQ ID NO: 922. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-66A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 815. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-66A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1029. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 66A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 815 and the VH comprising the amino acid sequence of SEQ ID NO: 1029. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-66_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 922; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 708. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-66_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 708; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 922. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-66_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1029; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 815. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-66A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 815; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1029. [00160] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-67 and ABL-PD- L1-67A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 67, 174, 281, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 388, 495, and 602, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-67, i.e., comprising the amino acid sequence of SEQ ID NO: 709. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-67, i.e., comprising the amino acid sequence of SEQ ID NO: 923. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-67, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 709 and VH comprising the amino acid sequence of SEQ ID NO: 923. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-67A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 816. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-67A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1030. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 67A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 816 and the VH comprising the amino acid sequence of SEQ ID NO: 1030. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-67_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 923; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 709. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-67_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 709; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 923. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-67_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1030; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 816. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-67A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 816; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1030. [00161] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-68 and ABL-PD- L1-68A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 68, 175, 282, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 389, 496, and 603, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-68, i.e., comprising the amino acid sequence of SEQ ID NO: 710. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-68, i.e., comprising the amino acid sequence of SEQ ID NO: 924. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-68, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 710 and VH comprising the amino acid sequence of SEQ ID NO: 924. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-68A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 817. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-68A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1031. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 68A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 817 and the VH comprising the amino acid sequence of SEQ ID NO: 1031. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-68_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 924; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 710. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-68_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 710; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 924. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-68_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1031; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 817. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-68A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 817; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1031. [00162] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-69 and ABL-PD- L1-69A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 69, 176, 283, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 390, 497, and 604, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-69, i.e., comprising the amino acid sequence of SEQ ID NO: 711. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-69, i.e., comprising the amino acid sequence of SEQ ID NO: 925. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-69, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 711 and VH comprising the amino acid sequence of SEQ ID NO: 925. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-69A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 818. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-69A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1032. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 69A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 818 and the VH comprising the amino acid sequence of SEQ ID NO: 1032. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-69_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 925; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 711. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-69_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 711; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 925. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-69_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1032; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 818. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-69A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 818; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1032. [00163] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-70 and ABL-PD- L1-70A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 70, 177, 284, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 391, 498, and 605, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-70, i.e., comprising the amino acid sequence of SEQ ID NO: 712. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-70, i.e., comprising the amino acid sequence of SEQ ID NO: 926. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-70, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 712 and VH comprising the amino acid sequence of SEQ ID NO: 926. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-70A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 819. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-70A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1033. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 70A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 819 and the VH comprising the amino acid sequence of SEQ ID NO: 1033. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-70_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 926; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 712. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-70_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 712; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 926. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-70_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1033; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 819. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-70A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 819; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1033. [00164] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-71 and ABL-PD- L1-71A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 71, 178, 285, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 392, 499, and 606, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-71, i.e., comprising the amino acid sequence of SEQ ID NO: 713. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-71, i.e., comprising the amino acid sequence of SEQ ID NO: 927. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-71, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 713 and VH comprising the amino acid sequence of SEQ ID NO: 927. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-71A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 820. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-71A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1034. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 71A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 820 and the VH comprising the amino acid sequence of SEQ ID NO: 1034. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-71_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 927; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 713. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-71_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 713; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 927. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-71_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1034; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 820. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-71A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 820; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1034. [00165] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-72 and ABL-PD- L1-72A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 72, 179, 286, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 393, 500, and 607, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-72, i.e., comprising the amino acid sequence of SEQ ID NO: 714. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-72, i.e., comprising the amino acid sequence of SEQ ID NO: 928. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-72, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 714 and VH comprising the amino acid sequence of SEQ ID NO: 928. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-72A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 821. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-72A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1035. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 72A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 821 and the VH comprising the amino acid sequence of SEQ ID NO: 1035. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-72_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 928; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 714. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-72_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 714; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 928. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-72_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1035; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 821. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-72A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 821; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1035. [00166] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-73 and ABL-PD- L1-73A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 73, 180, 287, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 394, 501, and 608, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-73, i.e., comprising the amino acid sequence of SEQ ID NO: 715. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-73, i.e., comprising the amino acid sequence of SEQ ID NO: 929. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-73, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 715 and VH comprising the amino acid sequence of SEQ ID NO: 929. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-73A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 822. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-73A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1036. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 73A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 822 and the VH comprising the amino acid sequence of SEQ ID NO: 1036. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-73_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 929; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 715. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-73_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 715; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 929. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-73_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1036; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 822. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-73A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 822; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1036. [00167] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-74 and ABL-PD- L1-74A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 74, 181, 288, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 395, 502, and 609, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-74, i.e., comprising the amino acid sequence of SEQ ID NO: 716. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-74, i.e., comprising the amino acid sequence of SEQ ID NO: 930. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-74, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 716 and VH comprising the amino acid sequence of SEQ ID NO: 930. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-74A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 823. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-74A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1037. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 74A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 823 and the VH comprising the amino acid sequence of SEQ ID NO: 1037. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-74_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 930; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 716. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-74_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 716; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 930. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-74_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1037; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 823. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-74A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 823; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1037. [00168] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-75 and ABL-PD- L1-75A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 75, 182, 289, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 396, 503, and 610, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-75, i.e., comprising the amino acid sequence of SEQ ID NO: 717. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-75, i.e., comprising the amino acid sequence of SEQ ID NO: 931. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-75, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 717 and VH comprising the amino acid sequence of SEQ ID NO: 931. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-75A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 824. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-75A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1038. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 75A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 824 and the VH comprising the amino acid sequence of SEQ ID NO: 1038. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-75_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 931; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 717. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-75_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 717; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 931. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-75_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1038; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 824. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-75A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 824; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1038. [00169] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-76 and ABL-PD- L1-76A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 76, 183, 290, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 397, 504, and 611, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-76, i.e., comprising the amino acid sequence of SEQ ID NO: 718. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-76, i.e., comprising the amino acid sequence of SEQ ID NO: 932. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-76, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 718 and VH comprising the amino acid sequence of SEQ ID NO: 932. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-76A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 825. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-76A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1039. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 76A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 825 and the VH comprising the amino acid sequence of SEQ ID NO: 1039. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-76_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 932; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 718. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-76_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 718; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 932. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-76_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1039; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 825. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-76A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 825; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1039. [00170] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-77 and ABL-PD- L1-77A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 77, 184, 291, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 398, 505, and 612, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-77, i.e., comprising the amino acid sequence of SEQ ID NO: 719. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-77, i.e., comprising the amino acid sequence of SEQ ID NO: 933. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-77, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 719 and VH comprising the amino acid sequence of SEQ ID NO: 933. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-77A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 826. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-77A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1040. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 77A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 826 and the VH comprising the amino acid sequence of SEQ ID NO: 1040. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-77_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 933; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 719. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-77_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 719; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 933. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-77_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1040; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 826. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-77A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 826; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1040. [00171] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-78 and ABL-PD- L1-78A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 78, 185, 292, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 399, 506, and 613, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-78, i.e., comprising the amino acid sequence of SEQ ID NO: 720. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-78, i.e., comprising the amino acid sequence of SEQ ID NO: 934. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-78, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 720 and VH comprising the amino acid sequence of SEQ ID NO: 934. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-78A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 827. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-78A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1041. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 78A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 827 and the VH comprising the amino acid sequence of SEQ ID NO: 1041. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-78_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 934; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 720. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-78_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 720; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 934. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-78_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1041; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 827. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-78A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 827; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1041. [00172] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-79 and ABL-PD- L1-79A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 79, 186, 293, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 400, 507, and 614, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-79, i.e., comprising the amino acid sequence of SEQ ID NO: 721. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-79, i.e., comprising the amino acid sequence of SEQ ID NO: 935. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-79, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 721 and VH comprising the amino acid sequence of SEQ ID NO: 935. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-79A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 828. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-79A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1042. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 79A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 828 and the VH comprising the amino acid sequence of SEQ ID NO: 1042. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-79_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 935; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 721. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-79_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 721; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 935. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-79_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1042; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 828. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-79A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 828; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1042. [00173] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-80 and ABL-PD- L1-80A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 80, 187, 294, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 401, 508, and 615, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-80, i.e., comprising the amino acid sequence of SEQ ID NO: 722. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-80, i.e., comprising the amino acid sequence of SEQ ID NO: 936. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-80, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 722 and VH comprising the amino acid sequence of SEQ ID NO: 936. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-80A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 829. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-80A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1043. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 80A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 829 and the VH comprising the amino acid sequence of SEQ ID NO: 1043. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-80_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 936; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 722. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-80_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 722; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 936. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-80_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1043; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 829. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-80A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 829; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1043. [00174] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-81 and ABL-PD- L1-81A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 81, 188, 295, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 402, 509, and 616, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-81, i.e., comprising the amino acid sequence of SEQ ID NO: 723. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-81, i.e., comprising the amino acid sequence of SEQ ID NO: 937. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-81, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 723 and VH comprising the amino acid sequence of SEQ ID NO: 937. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-81A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 830. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-81A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1044. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 81A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 830 and the VH comprising the amino acid sequence of SEQ ID NO: 1044. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-81_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 937; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 723. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-81_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 723; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 937. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-81_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1044; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 830. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-81A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 830; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1044. [00175] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-82 and ABL-PD- L1-82A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 82, 189, 296, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 403, 510, and 617, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-82, i.e., comprising the amino acid sequence of SEQ ID NO: 724. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-82, i.e., comprising the amino acid sequence of SEQ ID NO: 938. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-82, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 724 and VH comprising the amino acid sequence of SEQ ID NO: 938. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-82A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 831. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-82A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1045. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 82A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 831 and the VH comprising the amino acid sequence of SEQ ID NO: 1045. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-82_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 938; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 724. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-82_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 724; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 938. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-82_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1045; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 831. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-82A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 831; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1045. [00176] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-83 and ABL-PD- L1-83A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 83, 190, 297, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 404, 511, and 618, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-83, i.e., comprising the amino acid sequence of SEQ ID NO: 725. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-83, i.e., comprising the amino acid sequence of SEQ ID NO: 939. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-83, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 725 and VH comprising the amino acid sequence of SEQ ID NO: 939. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-83A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 832. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-83A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1046. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 83A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 832 and the VH comprising the amino acid sequence of SEQ ID NO: 1046. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-83_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 939; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 725. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-83_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 725; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 939. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-83_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1046; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 832. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-83A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 832; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1046. [00177] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-84 and ABL-PD- L1-84A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 84, 191, 298, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 405, 512, and 619, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-84, i.e., comprising the amino acid sequence of SEQ ID NO: 726. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-84, i.e., comprising the amino acid sequence of SEQ ID NO: 940. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-84, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 726 and VH comprising the amino acid sequence of SEQ ID NO: 940. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-84A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 833. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-84A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1047. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 84A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 833 and the VH comprising the amino acid sequence of SEQ ID NO: 1047. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-84_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 940; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 726. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-84_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 726; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 940. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-84_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1047; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 833. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-84A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 833; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1047. [00178] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-85 and ABL-PD- L1-85A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 85, 192, 299, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 406, 513, and 620, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-85, i.e., comprising the amino acid sequence of SEQ ID NO: 727. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-85, i.e., comprising the amino acid sequence of SEQ ID NO: 941. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-85, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 727 and VH comprising the amino acid sequence of SEQ ID NO: 941. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-85A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 834. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-85A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1048. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 85A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 834 and the VH comprising the amino acid sequence of SEQ ID NO: 1048. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-85_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 941; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 727. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-85_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 727; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 941. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-85_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1048; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 834. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-85A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 834; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1048. [00179] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-86 and ABL-PD- L1-86A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 86, 193, 300, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 407, 514, and 621, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-86, i.e., comprising the amino acid sequence of SEQ ID NO: 728. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-86, i.e., comprising the amino acid sequence of SEQ ID NO: 942. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-86, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 728 and VH comprising the amino acid sequence of SEQ ID NO: 942. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-86A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 835. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-86A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1049. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 86A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 835 and the VH comprising the amino acid sequence of SEQ ID NO: 1049. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-86_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 942; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 728. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-86_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 728; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 942. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-86_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1049; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 835. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-86A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 835; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1049. [00180] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-87 and ABL-PD- L1-87A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 87, 194, 301, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 408, 515, and 622, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-87, i.e., comprising the amino acid sequence of SEQ ID NO: 729. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-87, i.e., comprising the amino acid sequence of SEQ ID NO: 943. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-87, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 729 and VH comprising the amino acid sequence of SEQ ID NO: 943. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-87A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 836. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-87A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1050. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 87A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 836 and the VH comprising the amino acid sequence of SEQ ID NO: 1050. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-87_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 943; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 729. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-87_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 729; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 943. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-87_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1050; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 836. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-87A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 836; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1050. [00181] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-88 and ABL-PD- L1-88A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 88, 195, 302, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 409, 516, and 623, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-88, i.e., comprising the amino acid sequence of SEQ ID NO: 730. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-88, i.e., comprising the amino acid sequence of SEQ ID NO: 944. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-88, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 730 and VH comprising the amino acid sequence of SEQ ID NO: 944. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-88A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 837. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-88A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1051. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 88A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 837 and the VH comprising the amino acid sequence of SEQ ID NO: 1051. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-88_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 944; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 730. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-88_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 730; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 944. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-88_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1051; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 837. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-88A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 837; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1051. [00182] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-89 and ABL-PD- L1-89A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 89, 196, 303, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 410, 517, and 624, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-89, i.e., comprising the amino acid sequence of SEQ ID NO: 731. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-89, i.e., comprising the amino acid sequence of SEQ ID NO: 945. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-89, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 731 and VH comprising the amino acid sequence of SEQ ID NO: 945. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-89A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 838. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-89A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1052. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 89A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 838 and the VH comprising the amino acid sequence of SEQ ID NO: 1052. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-89_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 945; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 731. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-89_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 731; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 945. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-89_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1052; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 838. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-89A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 838; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1052. [00183] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-90 and ABL-PD- L1-90A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 90, 197, 304, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 411, 518, and 625, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-90, i.e., comprising the amino acid sequence of SEQ ID NO: 732. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-90, i.e., comprising the amino acid sequence of SEQ ID NO: 946. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-90, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 732 and VH comprising the amino acid sequence of SEQ ID NO: 946. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-90A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 839. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-90A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1053. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 90A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 839 and the VH comprising the amino acid sequence of SEQ ID NO: 1053. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-90_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 946; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 732. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-90_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 732; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 946. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-90_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1053; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 839. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-90A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 839; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1053. [00184] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-91 and ABL-PD- L1-91A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 91, 198, 305, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 412, 519, and 626, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-91, i.e., comprising the amino acid sequence of SEQ ID NO: 733. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-91, i.e., comprising the amino acid sequence of SEQ ID NO: 947. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-91, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 733 and VH comprising the amino acid sequence of SEQ ID NO: 947. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-91A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 840. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-91A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1054. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 91A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 840 and the VH comprising the amino acid sequence of SEQ ID NO: 1054. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-91_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 947; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 733. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-91_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 733; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 947. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-91_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1054; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 840. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-91A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 840; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1054. [00185] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-92 and ABL-PD- L1-92A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 92, 199, 306, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 413, 520, and 627, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-92, i.e., comprising the amino acid sequence of SEQ ID NO: 734. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-92, i.e., comprising the amino acid sequence of SEQ ID NO: 948. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-92, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 734 and VH comprising the amino acid sequence of SEQ ID NO: 948. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-92A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 841. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-92A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1055. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 92A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 841 and the VH comprising the amino acid sequence of SEQ ID NO: 1055. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-92_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 948; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 734. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-92_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 734; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 948. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-92_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1055; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 841. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-92A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 841; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1055. [00186] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-93 and ABL-PD- L1-93A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 93, 200, 307, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 414, 521, and 628, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-93, i.e., comprising the amino acid sequence of SEQ ID NO: 735. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-93, i.e., comprising the amino acid sequence of SEQ ID NO: 949. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-93, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 735 and VH comprising the amino acid sequence of SEQ ID NO: 949. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-93A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 842. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-93A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1056. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 93A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 842 and the VH comprising the amino acid sequence of SEQ ID NO: 1056. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-93_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 949; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 735. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-93_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 735; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 949. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-93_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1056; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 842. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-93A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 842; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1056. [00187] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-94 and ABL-PD- L1-94A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 94, 201, 308, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 415, 522, and 629, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-94, i.e., comprising the amino acid sequence of SEQ ID NO: 736. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-94, i.e., comprising the amino acid sequence of SEQ ID NO: 950. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-94, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 736 and VH comprising the amino acid sequence of SEQ ID NO: 950. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-94A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 843. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-94A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1057. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 94A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 843 and the VH comprising the amino acid sequence of SEQ ID NO: 1057. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-94_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 950; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 736. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-94_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 736; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 950. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-94_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1057; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 843. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-94A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 843; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1057. [00188] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-95 and ABL-PD- L1-95A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 95, 202, 309, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 416, 523, and 630, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-95, i.e., comprising the amino acid sequence of SEQ ID NO: 737. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-95, i.e., comprising the amino acid sequence of SEQ ID NO: 951. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-95, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 737 and VH comprising the amino acid sequence of SEQ ID NO: 951. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-95A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 844. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-95A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1058. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 95A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 844 and the VH comprising the amino acid sequence of SEQ ID NO: 1058. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-95_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 951; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 737. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-95_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 737; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 951. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-95_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1058; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 844. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-95A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 844; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1058. [00189] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-96 and ABL-PD- L1-96A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 96, 203, 310, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 417, 524, and 631, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-96, i.e., comprising the amino acid sequence of SEQ ID NO: 738. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-96, i.e., comprising the amino acid sequence of SEQ ID NO: 952. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-96, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 738 and VH comprising the amino acid sequence of SEQ ID NO: 952. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-96A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 845. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-96A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1059. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 96A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 845 and the VH comprising the amino acid sequence of SEQ ID NO: 1059. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-96_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 952; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 738. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-96_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 738; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 952. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-96_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1059; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 845. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-96A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 845; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1059. [00190] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-97 and ABL-PD- L1-97A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 97, 204, 311, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 418, 525, and 632, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-97, i.e., comprising the amino acid sequence of SEQ ID NO: 739. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-97, i.e., comprising the amino acid sequence of SEQ ID NO: 953. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-97, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 739 and VH comprising the amino acid sequence of SEQ ID NO: 953. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-97A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 846. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-97A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1060. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 97A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 846 and the VH comprising the amino acid sequence of SEQ ID NO: 1060. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-97_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 953; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 739. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-97_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 739; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 953. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-97_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1060; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 846. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-97A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 846; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1060. [00191] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-98 and ABL-PD- L1-98A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 98, 205, 312, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 419, 526, and 633, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-98, i.e., comprising the amino acid sequence of SEQ ID NO: 740. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-98, i.e., comprising the amino acid sequence of SEQ ID NO: 954. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-98, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 740 and VH comprising the amino acid sequence of SEQ ID NO: 954. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-98A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 847. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-98A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1061. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 98A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 847 and the VH comprising the amino acid sequence of SEQ ID NO: 1061. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-98_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 954; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 740. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-98_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 740; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 954. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-98_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1061; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 847. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-98A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 847; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1061. [00192] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-99 and ABL-PD- L1-99A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 99, 206, 313, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 420, 527, and 634, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-99, i.e., comprising the amino acid sequence of SEQ ID NO: 741. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-99, i.e., comprising the amino acid sequence of SEQ ID NO: 955. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-99, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 741 and VH comprising the amino acid sequence of SEQ ID NO: 955. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-99A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 848. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-99A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1062. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 99A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 848 and the VH comprising the amino acid sequence of SEQ ID NO: 1062. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-99_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 955; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 741. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-99_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 741; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 955. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-99_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1062; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 848. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-99A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 848; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1062. [00193] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-100 and ABL-PD- L1-100A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 100, 207, 314, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 421, 528, and 635, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-100, i.e., comprising the amino acid sequence of SEQ ID NO: 742. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-100, i.e., comprising the amino acid sequence of SEQ ID NO: 956. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-100, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 742 and VH comprising the amino acid sequence of SEQ ID NO: 956. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-100A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 849. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-100A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1063. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 100A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 849 and the VH comprising the amino acid sequence of SEQ ID NO: 1063. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-100_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 956; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 742. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-100_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 742; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 956. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-100_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1063; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 849. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-100A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 849; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1063. [00194] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-101 and ABL-PD- L1-101A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 101, 208, 315, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 422, 529, and 636, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-101, i.e., comprising the amino acid sequence of SEQ ID NO: 743. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-101, i.e., comprising the amino acid sequence of SEQ ID NO: 957. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-101, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 743 and VH comprising the amino acid sequence of SEQ ID NO: 957. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-101A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 850. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-101A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1064. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 101A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 850 and the VH comprising the amino acid sequence of SEQ ID NO: 1064. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-101_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 957; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 743. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-101_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 743; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 957. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-101_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1064; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 850. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-101A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 850; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1064. [00195] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-102 and ABL-PD- L1-102A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 102, 209, 316, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 423, 530, and 637, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-102, i.e., comprising the amino acid sequence of SEQ ID NO: 744. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-102, i.e., comprising the amino acid sequence of SEQ ID NO: 958. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-102, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 744 and VH comprising the amino acid sequence of SEQ ID NO: 958. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-102A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 851. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-102A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1065. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 102A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 851 and the VH comprising the amino acid sequence of SEQ ID NO: 1065. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-102_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 958; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 744. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-102_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 744; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 958. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-102_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1065; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 851. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-102A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 851; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1065. [00196] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-103 and ABL-PD- L1-103A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 103, 210, 317, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 424, 531, and 638, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-103, i.e., comprising the amino acid sequence of SEQ ID NO: 745. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-103, i.e., comprising the amino acid sequence of SEQ ID NO: 959. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-103, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 745 and VH comprising the amino acid sequence of SEQ ID NO: 959. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-103A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 852. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-103A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1066. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 103A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 852 and the VH comprising the amino acid sequence of SEQ ID NO: 1066. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-103_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 959; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 745. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-103_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 745; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 959. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-103_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1066; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 852. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-103A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 852; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1066. [00197] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-104 and ABL-PD- L1-104A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 104, 211, 318, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 425, 532, and 639, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-104, i.e., comprising the amino acid sequence of SEQ ID NO: 746. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-104, i.e., comprising the amino acid sequence of SEQ ID NO: 960. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-104, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 746 and VH comprising the amino acid sequence of SEQ ID NO: 960. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-104A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 853. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-104A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1067. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 104A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 853 and the VH comprising the amino acid sequence of SEQ ID NO: 1067. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-104_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 960; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 746. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-104_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 746; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 960. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-104_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1067; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 853. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-104A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 853; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1067. [00198] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-105 and ABL-PD- L1-105A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 105, 212, 319, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 426, 533, and 640, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-105, i.e., comprising the amino acid sequence of SEQ ID NO: 747. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-105, i.e., comprising the amino acid sequence of SEQ ID NO: 961. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-105, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 747 and VH comprising the amino acid sequence of SEQ ID NO: 961. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-105A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 854. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-105A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1068. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 105A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 854 and the VH comprising the amino acid sequence of SEQ ID NO: 1068. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-105_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 961; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 747. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-105_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 747; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 961. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-105_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1068; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 854. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-105A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 854; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1068. [00199] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-106 and ABL-PD- L1-106A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 106, 213, 320, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 427, 534, and 641, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-106, i.e., comprising the amino acid sequence of SEQ ID NO: 748. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-106, i.e., comprising the amino acid sequence of SEQ ID NO: 962. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-106, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 748 and VH comprising the amino acid sequence of SEQ ID NO: 962. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-106A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 855. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-106A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1069. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 106A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 855 and the VH comprising the amino acid sequence of SEQ ID NO: 1069. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-106_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 962; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 748. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-106_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 748; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 962. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-106_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1069; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 855. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-106A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 855; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1069. [00200] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the six CDRs of antibody ABL-PD-L1-107 and ABL-PD- L1-107A, i.e., the LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NOs: 107, 214, 321, respectively; and the HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NOs: 428, 535, and 642, respectively. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-107, i.e., comprising the amino acid sequence of SEQ ID NO: 749. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VH of antibody ABL-PD-L1-107, i.e., comprising the amino acid sequence of SEQ ID NO: 963. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody ABL-PD-L1-107, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 749 and VH comprising the amino acid sequence of SEQ ID NO: 963. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL of antibody ABL-PD-L1-106A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 856. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises the VH of antibody PD-L1-107A, i.e., the VH comprising the amino acid sequence of SEQ ID NO: 1070. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises the VL and VH of antibody PD-L1- 107A, i.e., the VL comprising the amino acid sequence of SEQ ID NO: 856 and the VH comprising the amino acid sequence of SEQ ID NO: 1070. In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL-PD- L1-107_scFv_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 963; a linker comprising the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 749. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises ABL-PD-L1-107_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 749; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 963. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises ABL- PD-L1-107_VH-VL, i.e., comprising from N-terminus to C-terminus, a VH comprising the amino acid sequence of SEQ ID NO: 1070; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VL comprising the amino acid sequence of SEQ ID NO: 856. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises PD-L1-107A_scFv_VL-VH, i.e., comprising from N- terminus to C-terminus, a VL comprising the amino acid sequence of SEQ ID NO: 856; a linker comprising the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4; and a VH comprising the amino acid sequence of SEQ ID NO: 1070. [00201] In some embodiments of this disclosure, the VL comprises an amino acid sequence of one of SEQ ID NOs: 643-856. In some embodiments, the VH comprises an amino acid sequence of one of SEQ ID NOs: 857-1070. In some embodiments, the VL comprises an amino acid sequence of one of SEQ ID NOs: 643-856, and the VH comprises an amino acid sequence of one of SEQ ID NOs: 857-1070. In some embodiments, the VH and the VL are from the same anti-PD-L1 AlivaMab® antibody. [00202] In some embodiments, an anti-PD-L1 antibody, or an antigen-binding fragment thereof, of the disclosure is human. In some embodiments, the human anti-PD-L1 antibody, or an antigen-binding fragment thereof, comprises a human IgH chain and a human Ig ^ chain. In some embodiments, the human anti-PD-L1 antibody, or an antigen-binding fragment thereof, comprises a human IgH chain and a human Ig ^ chain. In some embodiments, the isotype of the anti-PD-L1 antibody is selected from IgM, IgD, IgG (such as IgG1, IgG2, IgG3, and IgG4), IgA and IgE. In some embodiments, the isotype of the anti-PD-L1 antibody is IgG. In some embodiments, the isotype of the anti-PD-L1 antibody is selected from IgG1, IgG2, IgG3, and IgG4. [00203] In some embodiments of this disclosure, the anti-PD-L1 antibody or fragment thereof binds an Fc receptor (FcR) selected from an Fc ^R, an Fc ^R, and an Fc ^R. In some embodiments, the anti-PD-L1 antibody or fragment thereof binds an Fc ^R selected from FcγRI (CD64), FcγRII (CD32), and FcγRIII (CD16), including isoforms thereof. In some embodiments, the Fc domain of the anti-PD-L1 antibody comprises a mutation so that it preferentially binds a particular Fc ^R (see, e.g., U.S.6,737,056 and U.S.2015/0031862). [00204] In some embodiments of this disclosure, the anti-PD-L1 antibody has reduced effector function. In some embodiments, the anti-PD-L1 antibody exhibits reduced binding to an Fc receptor (FcR) selected from an Fc ^R, an Fc ^R, and an Fc ^R. In some embodiments, the anti-PD-L1 antibody exhibits reduced binding to an Fc ^R selected from FcγRI (CD64), FcγRII (CD32), and FcγRIII (CD16), including isoforms thereof. In some embodiments, the Fc domain of the anti-PD-L1 antibody comprises a mutation that reduces its binding to a particular Fc ^R. [00205] In some embodiments of this disclosure, the anti-PD-L1 antibody may have no effector function. In some embodiments, the anti-PD-L1 antibody does not bind an Fc receptor (FcR) selected from an Fc ^R, an Fc ^R, and an Fc ^R. In some embodiments, the anti-PD-L1 antibody does not bind an Fc ^R selected from FcγRI (CD64), FcγRII (CD32), and FcγRIII (CD16), including isoforms thereof. In some embodiments, the Fc domain of the anti-PD-L1 antibody comprises a mutation such that it does not bind a particular Fc ^R. The engineering of antibodies to reduce or eliminate effector function is well-known in the art (see, e.g., Stewart et at (2014) JITC 2:29, Dumet C. et al. MAbs, 2019, vol.11(8): 1341-1350; and Desjarlais, JR. and Lazar, GA, Exp. Cell. Res., 2011, vol. 317(9): 1278-1285; see also WO 89/07142; WO 94/28027; WO 94/29351; WO 95/26403; WO 2000/42072; WO 2004/029207; WO 2005/018572; WO 2005/007809; WO 2011/066501; WO 2011/149999; WO 2012/130831; WO 2014/121087; WO 2017/079369; WO 2018/071919; US 8,961,967; US 10,259,887; US 10,501,543; US 2006/0134105). [00206] In some embodiments of this disclosure, the Fc domain of the anti PD-L1 antibody comprises one or more amino acid modifications that reduces or eliminates one or more effector functions. In some embodiments, the modified Fc domain is derived from an IgG1 Fc domain. Optionally, the modified Fc domain is derived from an IgG1 constant region. In some embodiments, the modified Fc domain is derived from an IgG2 Fc domain. In some embodiments, the modified Fc domain is derived from an IgG2 constant region. The modified Fc domain may be derived from an IgG4 Fc domain region. In some embodiments, the modified Fc domain is derived from an IgG4 constant region. In some embodiments, the modified Fc domain is derived from a combination of Fc domains from more than one isotype of constant region. [00207] In some embodiments of this disclosure, the anti PD-L1 antibody comprises a modified Fc domain derived from an IgG1 molecule, wherein the modified Fc domain comprises an amino acid modification at any one of the positions selected from the group consisting of E216, R217, K218, C219, C220, C226, C229, P230, E233, L234, L235, G236, G237, P238, S239, V240, F241, K246, L251, T260, D265, V266, H268, W277, N297, E318, K322, P329, A330, P331, Q347, N348, T350, L351, K360, T366, N390, K392, T394, D399, S400, F405, Y407, K409, T411 or a combination such amino acid modifications, wherein the numbering of amino acid residues is according to the EU index as set forth in Edelman GM et al., Proc. Natl. Acad. USA, 63, 78-85 (1969). In some embodiments of this disclosure, the modified Fc domain derived from IgG1 comprises an amino acid modification selected from any one of the group consisting of C220S, C226S, C229S, P230S, E233P, L234A, L234F, L234V, L235A, L235E, L235V, G236E, G237A, P238S, D265S, D265A, H268Q, W277T, N297G, N297Q, N297D, N297A, E318A, K322A, P329G, P329A, A330S, P331S, Q347R, Q347E, Q347K, T350V, L351Y, K360D, K360E, T366A, T366I, T366L, T366M, T366V, N390R, N390K, N390D, K392V, K392M, K392R, K392L, K392F, K392E, T394W, D399R, D399W, D399K, S400E, S400D, S400R, S400K, F405A, F405I, F405M, F405T, F405S, F405V, F405W, Y407A, Y407I, Y407L, Y407V, K409F, K409I, K409S, K409W, T411N, T411R, T411Q, T411K, T411D, T411E, T411W, ∆E216-E222, K246R/L251E/T260R, InR234/235, InV235/236, InR236/237, InR237/238, InV238/239, InN238/239, InL238/239, InE238/239, InG238/239, InS239/240, InG240/241, InE240/241, InG240/241, InL238/239/P238Q, InE238/239/N348A, InS239/240/V266A, and InR237/238/G236A or a combination thereof. [00208] In some embodiments of this disclosure, the anti PD-L1 antibody comprises a modified Fc domain derived from an IgG2 molecule, wherein the modified Fc domain comprises an amino acid modification at any one of the positions selected from the group consisting of V234, G237, P238, H268, V309, A330, and P331 or a combination thereof, wherein the numbering of amino acid residues is according to the EU numbering as set forth in Edelman. In some embodiments of the disclosure, the modified Fc domain derived from IgG2 comprises an amino acid modification selected from any one of the group consisting of V234A, G237A, P238S, H268Q, H268A, V309L, A330S, P331S, or a combination thereof. [00209] In some embodiments, the anti PD-L1 antibody comprises a modified Fc domain derived from an IgG4 molecule, wherein the modified Fc domain comprises an amino acid modification at any one of the positions selected from the group consisting of S228, L235, L236, G237, E318, and N297 or a combination thereof, wherein the numbering of amino acid residues is according to the EU index as set forth in Edelman GM et al., Proc. Natl. Acad. USA, 63, 78-85 (1969). In some embodiments, the modified Fc domain derived from IgG4 comprises an amino acid modification selected from the group consisting of S228P, L235A, L235E, L236E, G237A, E318A, and N297Q or a combination thereof. Bispecific Antibodies [00210] One aspect of the present disclosure provides a bispecific antibody. In some embodiments, the bispecific antibody comprises an anti-PD-L1 antibody, or antigen-binding fragment thereof. In some embodiments, the anti-PD-L1 bispecific antibody further comprises a second antibody, or an antigen-binding fragment thereof. In some embodiments, the bispecific antibody comprises an anti-PD-L1 antibody, or antigen-binding fragment thereof, of this disclosure and a targeting antibody, or an antigen-binding fragment thereof. In some embodiments, the targeting antibody, or antigen-binding fragment thereof, is an immune cell- targeting antibody, or an antigen-binding fragment thereof. In some embodiments the targeting antibody binds the same or different tumor cell than the anti-PD-L1 moiety. In some embodiments the targeting antibody binds a virally infected cell or other cells relevant for treating viral infection. [00211] In some embodiments, the anti-PD-L1 bispecific antibody comprises an anti- PD-L1 fragment operably linked to the heavy chain of the second or targeting antibody. In some embodiments, the anti-PD-L1 fragment is operably linked to the N-terminus of the heavy chain of the second or targeting antibody. In such embodiments, the heavy chain of the targeting antibody may comprise, from N-terminus to C-terminus, the anti-PD-L1 fragment, the VH of the second or targeting antibody, and a Fc region. In some embodiments, the heavy chain of the second or targeting antibody from N-terminus to C terminus comprises the anti- PD-L1 fragment, the VH of the targeting antibody and a constant region. In some embodiments, the anti-PD-L1 antibody is operably linked to the C-terminus of the heavy chain of the second or targeting antibody. In such embodiments, the heavy chain of the second or targeting antibody comprises, from N-terminus to C-terminus, the VH of the second or targeting antibody, a Fc region, and the anti-PD-L1 fragment. In some embodiments, the heavy chain of the second or targeting antibody comprises, from N-terminus to C-terminus, the VH of the second or targeting antibody, a constant region, and the anti-PD-L1 fragment. In some embodiments, the PD-L1 fragment is an scFv fragment. [00212] In some embodiments the bispecific antibody is a homodimer. The anti-PD-L1 fragment is operably linked to a HC of a symmetrical 2+2 Bispecific antibody. In some embodiments, the 2+2 Bispecific antibody comprises two identical light chains and two identical FC domains. [00213] In some embodiments of this disclosure, the anti-PD-L1 bispecific antibody, or antigen-binding fragment thereof, comprises an scFv linked to a heavy chain sequence via a linker. In some embodiments, the linker is a variable length Gly-Ser linker. In some embodiments, the linker is selected from the group consisting of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1112), (Ser-Ser-Ser-Ser-Gly)n (SEQ ID NO: 1104), (Gly-Ser-Ser-Gly-Gly)n (SEQ ID NO: 1105), and (Gly-Gly-Ser-Gly-Gly)n (SEQ ID NO: 1106), where n is an integer between 1 and 5. In some embodiments, the linker comprises the amino acid sequence of (Gly-Gly-Gly- Gly-Ser)n (SEQ ID NO: 1111), wherein n is 1. In some embodiments, the linker comprises the amino acid sequence (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4. [00214] In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises a single-chain Fv (scFv). In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises a single-chain Fv (scFv) operably linked to a first Fc domain. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises a Fab fragment. In some embodiments, the anti-PD-L1 antibody, or antigen- binding fragment thereof, comprises a Fab fragment operably linked to a first Fc domain. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises a Fab’. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises a Fab’ operably linked to a first Fc domain. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises a F(ab’)2. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises a F(ab’)₂ operably linked to a first Fc domain. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises an Fv. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises an Fv operably linked to a first Fc domain. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises a complete heavy chain, comprising a first Fc domain. As used herein, a complete heavy chain includes heavy chains that do not contain all of their amino acid residues as a result of C- terminal clipping. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises a complete light chain. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, comprises a complete heavy chain, comprising a first Fc domain, and a complete light chain. [00215] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, is operably linked to the first Fc domain via a first linker. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, is operably linked to the N-terminus of the first Fc domain. In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, is operably linked to the C-terminus of the first Fc domain. In some embodiments, the first linker is an antibody hinge region. In some embodiments, the first linker is a variable length Gly-Ser linker. In some embodiments, the first linker comprises a linker selected from the group consisting of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1112), (Ser-Ser-Ser-Ser-Gly)n (SEQ ID NO: 1104), (Gly-Ser-Ser-Gly-Gly)n (SEQ ID NO: 1105), and (Gly-Gly-Ser-Gly-Gly)n (SEQ ID NO: 1106), where n is an integer between 1 and 5. In some embodiments, the linker comprises the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1111), wherein n is 1. [00216] In some embodiments, the anti-PD-L1 bispecific antibody further comprises a second antibody, or an antigen-binding fragment thereof. In some embodiments of this disclosure, the targeting antibody in the anti-PD-L1 bispecific antibody is an immune cell targeting antibody, or an antigen-binding fragment thereof. In some embodiments, the targeting antibody is a cancer or virally infected cell targeting antibody or an antibody that binds relevant cells for targeting these tissues, or an antigen-binding fragment thereof. In some embodiments, the second binding specificity does not provide targeting activity, but instead provides a complementary or redundant functional activity. In some embodiments, the second antibody, the immune cell, cancer or virally infected cell targeting antibody, or antigen-binding fragment thereof, comprises a single-chain Fv (scFv). In some embodiments, the second antibody, the immune cell, cancer or virally infected cell targeting antibody, or antigen-binding fragment thereof, comprises a single-chain Fv (scFv) operably linked to a second Fc domain. In some embodiments, the second antibody, the immune cell, or virally infected cell targeting antibody, or antigen-binding fragment thereof, comprises a Fab fragment. In some embodiments, the second antibody, the anti-immune cell, cancer or virally infected cell targeting antibody, or antigen-binding fragment thereof, comprises a Fab fragment operably linked to a second Fc domain. In some embodiments, the second antibody, the anti-immune cell, cancer or virally infected cell targeting antibody, or antigen-binding fragment thereof, comprises a Fab’. In some embodiments, the second antibody, the anti-immune cell, cancer or virally infected cell targeting antibody, or antigen-binding fragment thereof, comprises a Fab’ operably linked to a second Fc domain. In some embodiments, the second antibody, the anti- immune cell, cancer or virally infected cell targeting antibody, or antigen-binding fragment thereof, comprises a F(ab’)2. In some embodiments, the second antibody, the anti-immune cell, cancer or virally infected cell targeting antibody, or antigen-binding fragment thereof, comprises a F(ab’)₂ operably linked to a second Fc domain. In some embodiments, the second antibody, the anti-immune cell, or virally infected cell targeting antibody, or antigen-binding fragment thereof, comprises an Fv. In some embodiments, the second antibody, the anti- immune cell, cancer or virally infected cell targeting antibody, or antigen-binding fragment thereof, comprises an Fv operably linked to a second Fc domain. In some embodiments, the second antibody, the anti-immune cell, cancer or virally infected cell targeting antibody, or antigen-binding fragment thereof, comprises a complete heavy chain, comprising a second Fc domain. As used herein, a complete heavy chain includes heavy chains that do not contain all of their amino acid residues as a result of C-terminal clipping. In some embodiments, the second antibody, the anti-immune cell, cancer or virally infected cell targeting antibody, or antigen-binding fragment thereof, comprises a complete light chain. In some embodiments, the second antibody, the anti-immune cell, cancer or virally infected cell targeting antibody, or antigen-binding fragment thereof, comprises a complete heavy chain, comprising a second Fc domain, and a complete light chain. [00217] In some embodiments of this disclosure, the second antibody, the anti-immune cell, cancer or virally infected cell targeting antibody, or antigen-binding fragment thereof, is operably linked to the second Fc domain via a second linker. In some embodiments, the second antibody, the anti-immune cell, cancer or virally infected cell targeting antibody, or antigen- binding fragment thereof, is operably linked to the N-terminus of the second Fc domain. In some embodiments, the second antibody, the anti-immune cell, cancer or virally infected cell targeting antibody, or antigen-binding fragment thereof, is operably linked to the C-terminus of the second Fc domain. In some embodiments, the second linker is an antibody hinge region. In some embodiments, the second linker is a variable length Gly-Ser linker. In some embodiments, the second linker comprises a linker selected from the group consisting of (Gly- Gly-Gly-Gly-Ser)n (SEQ ID NO: 1112), (Ser-Ser-Ser-Ser-Gly)n (SEQ ID NO: 1104), (Gly- Ser-Ser-Gly-Gly)n (SEQ ID NO: 1105), and (Gly-Gly-Ser-Gly-Gly)n (SEQ ID NO: 1106), where n is an integer between 1 and 5. In some embodiments, the linker comprises the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1111), wherein n is 1. [00218] It is known in the art the mutations can be introduced into the Fc domains of bispecific antibodies to promote heterodimerization over homodimerization. See, e.g., Ha, JH et al., “Immunoglobulin Fc heterodimer platform technology: from design to applications in therapeutic antibodies and proteins,” Front. Immunol. 2016, vol. 7: 394, incorporated by reference herein in its entirety. Such mutations include “knobs-into-holes” (KIH) mutations; HA-TF (and related) mutations; skew mutations; ZW mutations; 7.8.60 (and related) mutations; DD-KK (and related) mutations; EW-RVT mutations; EW-RVT_S-S mutations; SEED mutations A107 mutations, Duobody mutations and CrossMab mutations. In some embodiments, the first Fc domain is derived from an IgG1 constant region. In some embodiments, the second Fc domain is derived from an IgG1 constant region. In some embodiments, the first and second Fc domains are derived from IgG1 constant regions. [00219] In some embodiments, the first and second Fc domains comprise KIH mutations. See, e.g., Ridgway JB et al., Protein Eng (1996) 9(7):617–21; Atwell S et al., J Mol Biol (1997) 270(1):26–35; and Merchant et al., Nat Biotechnol, 1998, 16:677-81, each of which is incorporated by reference herein. Non-limiting examples of “knob” mutations include S354C and T366W. Non-limiting examples of “hole” mutations include Y349C, T366S, L368A, and Y407V. The “hole” may be further mutated to eliminate protein A binding (H435R/Y436F). In this way, the knob-containing Fc domain can bind to protein A, and the hole-containing Fc can bind to Fab-selective resins, offering multiple purification options. [00220] In some embodiments, the first Fc domain comprises a T366W mutation and the second Fc domain comprises T366S/L368A/Y407V mutations. In some embodiments, the first Fc domain comprises T366S/L368A/Y407V mutations and the second Fc domain comprises a T366W mutation. In some embodiments, the first and second Fc domains comprise KIH_S-S mutations. In some embodiments, the first Fc domain comprises S354C/T366W mutations and the second Fc domain comprises Y349C/T366S/L368A/Y407V mutations. In some embodiments, the first Fc domain comprises Y349C/T366S/L368A/Y407V mutations and the second Fc domain comprises S354C/T366W mutation. In some embodiments, the first Fc domain comprises S354C/T366W mutations and the second Fc domain comprises Y349C/T366S/L368A/Y407V/H435R/Y436F mutations. In some embodiments, the first Fc domain comprises Y349C/T366S/L368A/ Y407V/H435R/Y436F mutations and the second Fc domain comprises S354C/T366W mutation. In some embodiments, the first Fc domain comprises S354C/T366W/H435R/Y436F mutations and the second Fc domain comprises Y349C/T366S/L368A/Y407V mutations. In some embodiments, the first Fc domain comprises Y349C/T366S/L368A/Y407V mutations and the second Fc domain comprises S354C/T366W/H435R/Y436F mutations. Each of the foregoing mutations is according to EU numbering. [00221] In some embodiments, the anti-PD-L1 bispecific antibody comprises an anti- PD-L1 fragment operably linked to a heavy chain of a LAG3 antibody. In some embodiments, the anti-PD-L1 bispecific antibody comprises an anti-PD-L1 fragment operably linked to a heavy chain comprising the amino acid sequence of QVQLVQSGAEVKKPGASVKVSCKASGYTFTDYNMDWVRQAPGQGLEWMGDINPD NGVTIYNQKFEGRVTMTTDTSTSTAYMELRSLRSDDTAVYYCAREADYFYFDYWG QGTTLTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSG VHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKT HTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVD GVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTI SKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKT TPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK (SEQ ID NO.1107). In some embodiments, the anti-PD-L1 fragment is operably linked to the N-terminus of the heavy chain. In such embodiments, the heavy chain of the second or targeting antibody may comprise, from N-terminus to C-terminus, the anti-PD-L1 fragment, the VH of the targeting antibody, and a Fc region. In some embodiments, the VH of the second or targeting antibody comprises the amino acid sequence of QVQLVQSGAEVKKPGASVKVSCKASGYTFTDYNMDWVRQAPGQGLEWMGDINPD NGVTIYNQKFEGRVTMTTDTSTSTAYMELRSLRSDDTAVYYCAREADYFYFDYWG QGTTLTVSS (SEQ ID NO.: 1108). In some embodiments, the PD-L1 fragment is an scFv fragment. In some embodiments of this disclosure, the anti-PD-L1 bispecific antibody, or antigen-binding fragment thereof, comprises an scFv linked to a heavy chain sequence via a linker. In some embodiments, the linker is a variable length Gly-Ser linker. In some embodiments, the linker is selected from the group consisting of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1112), (Ser-Ser-Ser-Ser-Gly)n (SEQ ID NO: 1104), (Gly-Ser-Ser-Gly-Gly)n (SEQ ID NO: 1105), and (Gly-Gly-Ser-Gly-Gly)n (SEQ ID NO: 1106), where n is an integer between 1 and 5. In some embodiments, the linker comprises the amino acid sequence of (Gly-Gly-Gly- Gly-Ser)n (SEQ ID NO: 1111), wherein n is 1. In some embodiments, the linker comprises the amino acid sequence (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 1103), wherein n is 4. [00222] In some embodiments, the second or targeting antibody is a LAG3 antibody. In some embodiment, the second or targeting antibody comprises a light chain comprising the amino acid sequence of DIQMTQSPSSLSASVGDRVTITCRASQDVSSVVAWYQQKPGKAPKLLIYSASYRYTG VPSRFSGSGSGTDFTLTISSLQPEDFATYYCQQHYSTPWTFGGGTKLEIKRTVAAPSVF IFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTY SLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC (SEQ ID NO.: 1109). In some embodiments, the VL of the second or targeting antibody comprises the amino acid sequence of DIQMTQSPSSLSASVGDRVTITCRASQDVSSVVAWYQQKPGKAPKLLIYSASYRYTG VPSRFSGSGSGTDFTLTISSLQPEDFATYYCQQHYSTPWTFGGGTKLEIK(SEQ ID NO.: 1110). In some embodiments, the first and second Fc domains comprise HA-TF and related mutations. See, e,g., Moore GL, et al., MAbs (2011) 3(6):546–57, incorporated herein by reference. In some embodiments, the first Fc domain comprises a S364H mutation and the second Fc domain comprises a Y349T mutation. In some embodiments, the first Fc domain comprises a Y349T mutation and the second Fc domain comprises a S364H mutation. In some embodiments, the first Fc domain comprises a F405A mutation and the second Fc domain comprises a T394F mutation. In some embodiments, the first Fc domain comprises a T394F mutation and the second Fc domain comprises a F405A mutation. In some embodiments, the first Fc domain comprises S364H/T394F mutations and the second Fc domain comprises Y349T/F405A mutations. In some embodiments, the first Fc domain comprises Y349T/F405A mutations and the second Fc domain comprises S364H/T394F mutations. In some embodiments, the first Fc domain comprises S364H/F405A mutations and the second Fc domain Y349T/T394F mutations. In some embodiments, the first Fc domain comprises Y349T/T394F mutations and the second Fc domain S364H/F405A mutations. Each of the foregoing mutations is according to EU numbering. [00223] In some embodiments, the first and second Fc domains comprise skew mutations. See, e.g., U.S. Patent 10,793,632, incorporated herein by reference. In some embodiments, the first Fc domain comprises S364K/E357Q mutations and the second Fc domain comprises L368D/K370S mutations. In some embodiments, the first Fc domain comprises L368D/K370S mutations and the second Fc domain comprises S364K/E357Q mutations. In some embodiments, the first Fc domain comprises L368D/K370S mutations and the second Fc domain comprises a S364K mutation. In some embodiments, the first Fc domain comprises a S364K mutation and the second Fc domain comprises L368D/K370S mutations. In some embodiments, the first Fc domain comprises L368E/K370S mutations and the second Fc domain comprises a S364K mutation. In some embodiments, the first Fc domain comprises a S364K mutation and the second Fc domain comprises L368E/K370S mutations. In some embodiments, the first Fc domain comprises T411E/K360E/Q362E mutations and the second Fc domain comprises a D401K mutation. In some embodiments, the first Fc domain comprises a D401K mutation and the second Fc domain comprises T411E/K360E/Q362E mutations. In some embodiments, the first Fc domain comprises L368D/K370S mutations and the second Fc domain comprises S364K/E357L mutations. In some embodiments, the first Fc domain comprises S364K/E357L mutations and the second Fc domain comprises L368D/K370S mutations. In some embodiments, the first Fc domain comprises a K370S mutation and the second Fc domain comprises S364K/E357Q mutations. In some embodiments, the first Fc domain comprises S364K/E357Q mutations and the second Fc domain comprises a K370S mutation. In some embodiments, the first Fc domain comprises T366S/L368A/Y407V mutations and the second Fc domain comprises a T366W mutation. In some embodiments, the first Fc domain comprises a T366W mutation and the second Fc domain comprises T366S/L368A/Y407V mutations. In some embodiments, the first Fc domain comprises T366S/L368A/Y407V/Y349C mutations and the second Fc domain comprises T366W/S354C mutations. In some embodiments, the first Fc domain comprises T366W/S354C mutations and the second Fc domain comprises T366S/L368A/Y407V/Y349C mutations. Each of the foregoing mutations is according to EU numbering. [00224] In some embodiments, the first and second Fc domains comprise ZW mutations. See, e.g., Von Kreudenstein TS, et al., MAbs (2013) 5(5):646–54, incorporated herein by reference. In some embodiments, the first Fc domain comprises F405A/Y407V mutations and the second Fc domain comprises a T394W mutation. In some embodiments, the first Fc domain comprises a T394W mutation and the second Fc domain comprises F405A/Y407V mutations. In some embodiments, the first Fc domain comprises F405A/Y407V mutations and the second Fc domain comprises T366I/T394W mutations. In some embodiments, the first Fc domain comprises T366I/T394W mutations and the second Fc domain comprises F405A/Y407V mutations. In some embodiments, the first Fc domain comprises F405A/Y407V mutations and the second Fc domain comprises T366L/T394W mutations. In some embodiments, the first Fc domain comprises T366L/T394W mutations and the second Fc domain comprises F405A/Y407V mutations. In some embodiments, the first Fc domain comprises F405A/Y407V mutations and the second Fc domain comprises T366L/K392M/T394W mutations. In some embodiments, the first Fc domain comprises T366L/K392M/T394W mutations and the second Fc domain comprises F405A/Y407V mutations. In some embodiments, the first Fc domain comprises L351Y/F405A/Y407V mutations and the second Fc domain comprises T366L/K329M/T394W mutations. In some embodiments, the first Fc domain comprises T366L/K329M/T394W mutations and the second Fc domain comprises L351Y/F405A/Y407V mutations. In some embodiments, the first Fc domain comprises T350V/L351Y/F405A/Y407V mutations and the second Fc domain comprises T350V/T366L/K392M/T394W mutations. In some embodiments, the first Fc domain comprises T350V/T366L/K392M/T394W mutations and the second Fc domain comprises T350V/L351Y/F405A/Y407V mutations. In some embodiments, the first Fc domain comprises T350V/L351Y/F405A/Y407V mutations and the second Fc domain comprises T350V/T366L/K392L/T394W mutations. In some embodiments, the first Fc domain comprises T350V/T366L/K392L/T394W mutations and the second Fc domain comprises T350V/L351Y/F405A/Y407V mutations. Each of the foregoing mutations is according to EU numbering. [00225] In some embodiments of this disclosure, the first and second Fc domains comprise 7.8.60 mutations or related mutations. See, e.g., Leaver-Fay A, et al., Structure (2016) 24(4):641–51, incorporated herein by reference. In some embodiments, the first Fc domain comprises D399M/Y407A mutations and the second Fc domain comprises T366V/K409V mutations. In some embodiments, the first Fc domain comprises T366V/K409V mutations and the second Fc domain comprises D399M/Y407A mutations. In some embodiments, the first Fc domain comprises K360D/D399M/Y407A mutations and the second Fc domain comprises E345R/Q347R/T366V/K409V mutations. In some embodiments, the first Fc domain comprises E345R/Q347R/T366V/K409V mutations and the second Fc domain comprises K360D/D399M/Y407A mutations. In some embodiments, the first Fc domain comprises Y349S/K370Y/T366V/K409V mutations and the second Fc domain comprises E357D/S364Q/Y407A mutations. In some embodiments, the first Fc domain comprises E357D/S364Q/Y407A mutations and the second Fc domain comprises Y349S/K370Y/T366V/K409V mutations. In some embodiments, the first Fc domain comprises Y349S/K370Y/T366M/K409V mutations, and the second Fc domain comprises E356G/E357D/S364Q/Y407A mutations. In some embodiments, the first Fc domain comprises E356G/E357D/S364Q/Y407A mutations, and the second Fc domain comprises Y349S/K370Y/T366M/K409V mutations. In some embodiments, the first Fc domain comprises Y349S/K370Y/T366M/K409V mutations and the second Fc domain comprises E357D/S364R/Y407A mutations. In some embodiments, the first Fc domain comprises E357D/S364R/Y407A mutations and the second Fc domain comprises Y349S/K370Y/T366M/K409V mutations. Each of the foregoing mutations is according to EU numbering. [00226] In some embodiments of this disclosure, the first and second Fc domains comprise DD-KK mutations or related mutations. See, e.g., Gunasekaran K, et al., J Biol Chem (2010) 285(25):19637–46, incorporated herein by reference. In some embodiments, the first Fc domain comprises K409D/K392D mutations and the second Fc domain comprises D399K/E356K mutations. In some embodiments, the first Fc domain comprises D399K/E356K mutations and the second Fc domain comprises K409D/K392D mutations. In some embodiments, the first Fc domain comprises K409E/K392D mutations and the second Fc domain comprises D399R/E356K mutations. In some embodiments, the first Fc domain comprises D399R/E356K mutations and the second Fc domain comprises K409E/K392D mutations. In some embodiments, the first Fc domain comprises K409D/K392D mutations and the second Fc domain comprises D399R/E356K mutations. In some embodiments, the first Fc domain comprises D399R/E356K mutations and the second Fc domain comprises K409D/K392D mutations. In some embodiments, the first Fc domain comprises K409E/K392D mutations and the second Fc domain comprises D399K/E356K mutations. In some embodiments, the first Fc domain comprises D399K/E356K mutations and the second Fc domain comprises K409E/K392D mutations. In some embodiments, the first Fc domain comprises K409D/K392D/K370D mutations and the second Fc domain comprises D399K/E356K/E357K mutations. In some embodiments, the first Fc domain comprises D399K/E356K/E357K mutations and the second Fc domain comprises K409D/K392D/K370D mutations. Each of the foregoing mutations is according to EU numbering. [00227] In some embodiments, the first and second Fc domains comprise EW-RVT mutations or related mutations. See, e.g., Choi HJ, et al., Mol Cancer Ther (2013) 12(12):2748–59 and Choi HJ, et al., Mol Immunol (2015) 65(2):377–83, each of which is incorporated herein by reference. In some embodiments, the first Fc domain comprises a K409W mutation and the second Fc domain comprises F405T/D399V mutations. In some embodiments, the first Fc domain comprises F405T/D399V mutations and the second Fc domain comprises a K409W mutation. In some embodiments, the first Fc domain comprises K360E/K409W mutations and the second Fc domain comprises Q347R/D399V/F405T mutations. In some embodiments, the first Fc domain comprises Q347R/D399V/F405T mutations and the second Fc domain comprises K360E/K409W mutations. In some embodiments, the first Fc domain comprises K360E/K409W/Y349C mutations and the second Fc domain comprises Q347R/D399V/F405T/S354C mutations. In some embodiments, the first Fc domain comprises Q347R/D399V/F405T/S354C mutations and the second Fc domain comprises K360E/K409WY349C mutations. Each of the foregoing mutations is according to EU numbering. [00228] In some embodiments, the first and second Fc domains comprise strand- exchange engineered domains (SEED). See, e.g., Davis JH, et al., Protein Eng Des Sel (2010) 23(4):195–202, incorporated herein by reference. SEED CH3 heterodimers are composed of alternating segments of human IgA and IgG CH3 sequences. In some embodiments, the first Fc domain comprises an AG SEED domain and the second Fc domain comprises a GA SEED domain. In some embodiments, the first Fc domain comprises a GA SEED domain and the second Fc domain comprises an AG SEED domain. [00229] In some embodiments, the first and second Fc domains comprise A107 mutations or related mutations. See, e.g., Choi HJ, et al. PLoS One (2015) 10(12):e0145349, incorporated herein by reference. In some embodiments, the first Fc domain comprises K370E/K409W mutations and the second Fc domain comprises E357N/D399V/F405T mutations. In some embodiments, the first Fc domain comprises E357N/D399V/F405T mutations and the second Fc domain comprises K370E/K409W mutations. In some embodiments, the first Fc domain comprises K370E/K409W mutations and the second Fc domain comprises E357I/S364T/D399V/F405T mutations. In some embodiments, the first Fc domain comprises E357I/S364T/D399V/F405T mutations and the second Fc domain comprises K370E/K409W mutations. In some embodiments, the first Fc domain comprises K370M/K409W mutations and the second Fc domain comprises E357M/S364W/D399V/F405T mutations. In some embodiments, the first Fc domain comprises E357M/S364W/D399V/F405T mutations and the second Fc domain comprises K370M/K409W mutations. In some embodiments, the first Fc domain comprises K370D/K409W mutations and the second Fc domain comprises E357M/D399V/F405T mutations. In some embodiments, the first Fc domain comprises E357M/D399V/F405T mutations and the second Fc domain comprises K370D/K409W mutations. In some embodiments, the first Fc domain comprises E357D/S364W/K370E mutations and the second Fc domain comprises E357N/K370R mutations. In some embodiments, the first Fc domain comprises E357N/K370R mutations and the second Fc domain comprises E357D/S364W/K370E mutations. In some embodiments, the first Fc domain comprises E357A/S364Y/K370E mutations and the second Fc domain comprises E357N/K370H mutations. In some embodiments, the first Fc domain comprises E357N/K370H mutations and the second Fc domain comprises E357A/S364Y/K370E mutations. In some embodiments, the first Fc domain comprises E357G/S364W/K370E mutations and the second Fc domain comprises an E357N mutation. In some embodiments, the first Fc domain comprises an E357N mutation and the second Fc domain comprises E357G/S364W/DK70E mutations. In some embodiments, the first Fc domain comprises E357N/S364W/K370E mutations and the second Fc domain comprises an E357N mutation. In some embodiments, the first Fc domain comprises an E357N mutation and the second Fc domain comprises E357N/S364W/DK70E mutations. Each of the foregoing mutations is according to EU numbering. [00230] In some embodiments, the first and second Fc domains comprise Duobody® mutations. See, e.g., Labrijn et al., Nat Biotech 27(8), 767-71 (2009); Labrijn et al., J Immunol 187(6), 3238-46 (2011); Labrijn et al., PNAS 110(13): 5145-5150 (2013); Labrijn et al., Nature Protocols 9(10): 2450-63 (2014); Labrijn et al., Sci Report 7(1) (2017); Engelberts et al. EBioMedicine. (2020) 52:102625 and Middleburg et al Cancers (Basel). (2021) 14;13(2):287), each of which is incorporated herein by reference in its entirety. Such mutations allow two separately generated antibodies to be recombined into a bispecific antibody by controlled Fab- arm exchange. Non-limiting examples of Duobody® mutations include an F405L mutation and a K409R mutation. In some embodiments, the first Fc domain comprises an F405L mutation. In some embodiments, the first Fc domain comprises a K409R mutation. In some embodiments, the second Fc domain comprises an F405L mutation. In some embodiments, the second Fc domain comprises a K409R mutation. In some embodiments, the first Fc domain comprises an F405L mutation, and the second Fc domain comprises a K409R mutation. In some embodiments, the first Fc domain comprises a K409R mutation, and the second Fc domain comprises an F405L mutation. [00231] In some embodiments of this disclosure, the anti-PD-L1 bispecific antibody comprises CrossMAb® mutations. See, e.g. Surowka et al. MAbs. 202113(1):1967714. CrossMAb® technology addresses the issues of light chain mispairing by swapping the CH1 and CL domains of one of the arms of the bispecific antibody. For example, the heavy chain of one arm of a bispecific antibody can contain, from N-term to C-term, a VH domain, a CL domain, a hinge, a CH2 domain and a CH3 domain, and the light chain of that arm of the bispecific antibody can contain, from N-term to C-term, a VL domain and a CH1 domain. A similar effect can be achieved by swapping the VH and VL domains of one of the arms of the bispecific antibody. For example, the heavy chain of one arm of a bispecific antibody can contain, from N-term to C-term, a VL domain, a CH1 domain, a hinge, a CH2 domain and a CH3 domain, and the light chain of that arm of the bispecific antibody can contain, from N- term to C-term, a VH domain and a CL domain. Additionally, the VH and CH1 of one arm of a bispecific antibody can be swapped with the VL and CL of that arm. For example, the heavy chain of one arm of a bispecific antibody can contain, from N-term to C-term, a VL domain, a CL domain, a hinge, a CH2 domain and a CH3 domain, and the light chain of that arm of the bispecific antibody can contain, from N-term to C-term, a VH domain and a CH1 domain. [00232] In some embodiments of this disclosure, the CH1 and CL domains of the anti- PD-L1 antibody are swapped. In some embodiments, the VH and VL domains of the anti-PD- L1 antibody are swapped. In some embodiments, the VH/CH1 domains of the anti-PD-L1 antibody are swapped with the VL/CL domains of the anti-PD-L1 antibody. In some embodiments, the CH1 and CL domains of the anti- second or targeting antibody are swapped. In some embodiments, the VH and VL domains of the second or targeting antibody are swapped. In some embodiments, the VH/CH1 domains of the second or antibody are swapped with the VL/CL domains of the second or cell targeting antibody. [00233] In some embodiments of this disclosure, the first Fc domain and/or the second Fc domain are independently engineered to further prolong systemic exposure and increase half-life through enhanced FcRn binding at a lower pH (6.0). Without being bound by theory, Fc domains with increased binding to the neonatal Fc Receptor (FcRn) at a pH of about 6.0 are believed to have increased circulating half-lives in vivo because they remain bound to the FcRn in the endosomal compartment. When the endosome recycles to the cell surface and opens to the extracellular space, the Fc-containing protein can be released back into the blood, however, increased binding to FcRn at a higher pH (around 7.4) can prevent the release of the Fc-containing protein back into the blood. Accordingly, Fc mutations that increase binding to FcRn at lower pHs, while permitting release from the FcRn at higher pHs should increase their circulating half-lives. See, e.g., Dall’ Acqua et al. J. Immunol., 2002, 169:5171-5180. The charge state of histidine changes between pH 6.0 and pH 7.4, and histidine residues in the Fc domain (H310 and H435) were shown to play an important role in the pH-dependent binding to FcRn. Id. (See, also, Oganesyan V et al. J Biol Chem.2014 ;289(11):7812-24). Residues shown to be important in improved FcRn binding include P230, F241, V264, T307, N315, A330, A378, N389, M428, and N434 (according to EU numbering). See, e.g., Céline, M. et al., “Selection of IgG Variants with Increased FcRn Binding Using Random and Directed Mutagenesis: Impact on Effector Functions,” Front. Immunol.2015, vol.6, doi: 10.3389/fimmu.2015.00039. Exemplary improved FcRn-binding mutations of these residues include, but are not limited to, P230S, V264E, T307A, N315D, A330V, A378V, N389T, M428L, and N434Y. Non-limiting examples of additional improved FcRn-binding mutations known in the art include, 436I, 436V, 311I, 311V, 428L, 434S, 428L/434S, 259I, 308F, 259I/308F, 259I/308F/428L, 307Q/434S, 434A, 434H, 250Q/428L, M252Y/S254T/T256E, 307Q/434A, 307Q/380A/434A, and 308P/434A (according to EU numbering). See, e.g., U.S.8,637,641, which is incorporated herein by reference in its entirety [00234] In some embodiments of this disclosure, the first and/or second Fc domain are independently engineered to have improved PK. In some embodiments, the first and/or second Fc domains of the present disclosure independently comprise amino acid substitutions M428L and/or N434S, according to EU numbering. In some embodiments, the first Fc domain comprises one or both of the amino acid substitution M428L and N434S. In some embodiments, the second Fc domain comprises one or both of the amino acid substitution M428L and N434S. [00235] In some embodiments, the first and/or second Fc domain are independently engineered to allow purification of homodimers away from heterodimers by increasing the pI difference between the two monomers. Accordingly, in some embodiments of this disclosure, amino acid substitutions are introduced into either or both of the constant regions of the anti- PD-L1 antibody and the second or targeting antibody to alter the isoelectric point of that antibody. Accordingly, the homodimeric anti-PD-L1 antibody, the homodimeric second or targeting antibody, and the heterodimeric bispecific antibody will each have a different isoelectric point, allowing them to be separated from each other by, e.g., isoelectric focusing. The separation of the heterodimers from the two homodimers can be accomplished if the pIs of the two monomeric antibodies differ by as little as 0.1 pH unit, with 0.2, 0.3, 0.4 and 0.5 or greater all finding use for this purpose in the present disclosure. There are two general categories of pI variants: those that increase the pI of the antibody (basic changes) and those that decrease the pI of the antibody (acidic changes). All combinations of these variants are contemplated: one antibody may be wild type, or a variant that does not display a significantly different pI from wild-type, and the other can be either more basic or more acidic. Alternatively, each antibody may be changed, one to more basic and one to more acidic. Such mutations may be introduced into the hinge, CH2 and/or CH3 domains of the antibody. [00236] In some embodiments, the pI mutations are introduced into the hinge domain. Residues 221, 222, 223, 224, 225, 233, 234, 235 and 236 (according to EU numbering) within the hinge may be mutated to alter the pI of an antibody. Non-limiting examples of substitutions that may be used to lower the pI of hinge domains include a deletion at position 221, a non- native valine or threonine at position 222, a deletion at position 223, a non-native glutamic acid at position 224, a deletion at position 225, a deletion at position 235 and a deletion or a non- native alanine at position 236. [00237] In some embodiments, the pI mutations are introduced into the CH2 domain. Residues 274, 296, 300, 309, 320, 322, 326, 327, 334 and 339 (according to EU numbering) within the CH2 may be mutated to alter the pI of an antibody. Non-limiting examples of substitutions that may be used to lower the pI of CH2 domains include a non-native glutamine or glutamic acid at position 274, a non-native phenylalanine at position 296, a non-native phenylalanine at position 300, a non-native valine at position 309, a non-native glutamic acid at position 320, a non-native glutamic acid at position 322, a non-native glutamic acid at position 326, a non-native glycine at position 327, a non-native glutamic acid at position 334, a non-native threonine at position 339. [00238] In some embodiments, the pI mutations are introduced into the CH3 domain. Residues 355, 359, 362, 384, 389, 392, 397, 418, 419, 444 and 447 (according to EU numbering) within the CH3 may be mutated to alter the pI of an antibody. Non-limiting examples of substitutions that may be used to lower the pI of CH3 domains include a non- native glutamine or glutamic acid at position 355, a non-native serine at position 384, a non- native asparagine or glutamic acid at position 392, a non-native methionine at position 397, a non-native glutamic acid at position 419, a non-native glutamic acid at position 359, a non- native glutamic acid at position 362, a non-native glutamic acid at position 389, a non-native glutamic acid at position 418, a non-native glutamic acid at position 444, and a deletion or non- native aspartic acid at position 447. [00239] Mutations that delete a positively charged residue or substitute it with a neutral or negatively charged residue will lower the pI of an antibody. Non-limiting examples of positively charged residues that may be deleted or substituted include: K274, R355, K392, and K447 (according to EU numbering). Exemplary pI-lowering mutations of these residues include: K274Q, R355Q, K392N, and K447del (deletion of K447). Mutations that substitute a neutral residue with a negatively charged residue will also lower the pI of an antibody. Non- limiting examples of neutral residues that may be substituted with negatively charged residues include: N203, Q295, N384, Q418, Q419, and N421 (according to EU numbering). Exemplary pI-lowering mutations of these residues include: N203D, Q295E, N384D, Q418E, Q419E, and N421D. [00240] Mutations that delete a negatively charged residue or substitute it with a neutral or positively charged residue will raise the pI of an antibody. Non-limiting examples of negatively charged residues that may be deleted or substituted include: E269, E272, E283, and E357 (according to EU numbering). Exemplary pI-raising mutations of these residues include: E269Q, E272Q, E283Q, and E357Q. Mutations that substitute a neutral residue with a positively charged residue will also raise the pI of an antibody. Non-limiting examples of neutral residues that may be substituted with positively charged residues include: Q196, P217, P228, and N276 (according to EU numbering). Exemplary pI-raising mutations of these residues include: Q196K, P217R, P228R, and N276K. [00241] In some embodiments, the first Fc domain comprises one or more mutations to lower the isoelectric point as compared to a wild-type Fc domain. In some embodiments, the first Fc domain comprises one or more mutations to raise the isoelectric point as compared to a wild-type Fc domain. In some embodiments, the second Fc domain comprises one or more mutations to lower the isoelectric point as compared to a wild-type Fc domain. In some embodiments, the second Fc domain comprises one or more mutations to raise the isoelectric point as compared to a wild-type Fc domain. In some embodiments, the first Fc domain comprises one or more mutations to lower the isoelectric point as compared to a wild-type Fc domain and the second Fc domain comprises one or more mutations to raise the isoelectric point as compared to a wild-type Fc domain. In some embodiments, the first Fc domain comprises one or more mutations to raise the isoelectric point as compared to a wild-type Fc domain and the second Fc domain comprises one or more mutations to lower the isoelectric point as compared to a wild-type Fc domain. [00242] In some embodiments, the second antibody or targeting antibody is an anti- LAG3 antibody. In some embodiments, the anti-LAG3 antibody comprises the six CDRs of anti-LAG3 Fab derived from tebotelimab. In some embodiments, the anti-LAG3 antibody comprises the VH of anti-LAG3 Fab derived from tebotelimab. In some embodiments, the anti-LAG3 antibody comprises the VL of anti-LAG3 Fab derived from tebotelimab. In some embodiments, the anti-Lag3 antibody comprises the VH and the VL of anti- LAG3 Fab derived from tebotelimab. In some embodiments, the heavy chain of the anti- LAG3 antibody comprises the amino acid sequence of SEQ ID NO: 1107. In some embodiments, the light chain of the anti- LAG3 antibody comprises the amino acid sequence of SEQ ID NO: 1109. In some embodiments, the VH of the anti- LAG3 antibody comprises the amino acid sequence of SEQ ID NO1108, and the VL of the anti- LAG3 antibody comprises the amino acid sequence of SEQ ID NO: 1110. Polynucleotides [00243] One aspect of the present disclosure provides a polynucleotide sequence that encodes an anti-PD-L1 antibody, or antigen-binding fragment thereof of this disclosure. In some embodiments, the polynucleotide is cDNA. In some embodiments, separate polynucleotide molecules encode a heavy chain and a light chain of an anti-PD-L1 antibody or fragment. In some embodiments, a first polynucleotide encodes the heavy chain of an anti-PD- L1 antibody or fragment and a second polynucleotide encodes the light chain of the anti-PD- L1 antibody or fragment. In other embodiments, the same polynucleotide molecule encodes both the heavy chain and the light chain of an anti-PD-L1 antibody or fragment. [00244] In some embodiments of this disclosure, the polynucleotide encodes a CDR of an anti-PD-L1 antibody or antigen binding fragment thereof. In some embodiments, the polynucleotide comprises a sequence encoding a HCDR1 domain of the antibody or fragment (SEQ ID NO: 322-428). In some embodiments, the polynucleotide comprises a sequence encoding a HCDR2 domain of the antibody or fragment (SEQ ID NO: 429-535). In some embodiments, the polynucleotide comprises a sequence encoding a HCDR3 domain of the antibody or fragment (SEQ ID NO: 536-642). In some embodiments, the polynucleotide comprises a sequence encoding a LCDR1 domain of the antibody or fragment (SEQ ID NO: 1-107). In some embodiments, the polynucleotide comprises a sequence encoding a LCDR2 domain of the antibody or fragment (SEQ ID NO: 108-214). In some embodiments, the polynucleotide comprises a sequence encoding a LCDR3 domain of the antibody or fragment (SEQ ID NO: 215-321). In some embodiments, the polynucleotide comprises a sequence encoding the six CDRs of an anti-PD-L1 antibody or fragment (SEQ ID NO: 1-642). [00245] In some embodiments, a polynucleotide comprises a sequence encoding a VH domain of an anti-PD-L1 antibody or fragment (SEQ ID NO: 857-1070). In some embodiments, a polynucleotide comprises a sequence encoding a VL of an anti-PD-L1 antibody or fragment (SEQ ID NO: 643-856). In some embodiments, a polynucleotide comprises a sequence encoding a VH (SEQ ID NO: 857-1070) of an anti-PD-L1 antibody or fragment and a sequence encoding a VL (SEQ ID NO: 643-856) of an anti-PD-L1 antibody or fragment. [00246] In some embodiments of this disclosure, the polynucleotide encodes a VL comprising an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 97%, 98% or 99% identical to the VL amino acid sequence of any one of SEQ ID NOs: 643-856. In some embodiments, the polynucleotide encodes a VL comprising an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 97%, 98% or 99% similar to the VL amino acid sequence of SEQ ID NO: 643-856. The polynucleotides of this disclosure also include nucleotide sequences that hybridize under highly stringent conditions to the complement of a polynucleotide encoding the amino acid sequence the VL region of SEQ ID NO: 643-856. [00247] In some embodiments, the polynucleotide encodes a VH comprising an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 97%, 98% or 99% identical to the VH amino acid sequence of any one of SEQ ID NOs: 857-1070. In some embodiments, the polynucleotide encodes a VH comprising an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 97%, 98% or 99% similar to the VH amino acid sequence of SEQ ID NO: 857-1070. The polynucleotides of this disclosure also include nucleotide sequences that hybridize under highly stringent conditions to the complement of a polynucleotide encoding the amino acid sequence the VH region of SEQ ID NO: 857-1070. [00248] It is known in the art that each heavy chain and light chain (or fragment thereof) is expressed comprising a leader sequence (also known as a signal sequence) at its N terminus, which is used to transport the newly synthesized chains into the endoplasmic reticulum. During post-translational processing the leader sequences is removed and, therefore, is not present in the final chain or the mature antibody. Most heavy chain leader sequences contain 19 amino acid residues (i.e., are encoded by the first 57 nucleotides), and most light chain leader sequences contain 22 amino acid residues (i.e. are encoded by the first 66 nucleotides). Haryadi R, et al., PLoS One, 2015, vol.10(2): e0116878. The skilled artisan would recognize that the nucleotide sequence encoding the mature heavy chain or light chain (or fragment thereof) may be operably linked to a particular leader sequence to optimize its expression in a given expression system. Id. Vectors [00249] An additional aspect of the disclosure provides one or more vectors comprising a polynucleotide sequence encoding an anti-PD-L1 antibody, or an antigen-binding fragment thereof, disclosed herein. In some embodiments, the sequences encoding the heavy and light chains of the anti-PD-L1 antibody or fragment are on the same vector. In some embodiments, the sequences encoding the heavy and lights chain of the anti-PD-L1 antibody or fragment are on separate vectors. In some embodiments, the vector comprises a polynucleotide sequence encoding a HCDR1, a HCDR2, and an HCDR3 of the anti-PD-L1 antibody, or an antigen- binding fragment thereof In some embodiments, the vector comprises a polynucleotide sequence encoding a LCDR1, a LCDR2, and an LCDR3 of the anti-PD-L1 antibody, or an antigen-binding fragment thereof. In some embodiments of this disclosure, the vector comprises a polynucleotide sequence encoding a HCDR1, a HCDR2, a HCDR3, a LCDR1, a LCDR2, and an LCDR3 of the anti-PD-L1 antibody, or an antigen-binding fragment thereof. In some embodiments, the vector comprises a polynucleotide sequence encoding a VH of the anti-PD-L1 antibody, or an antigen-binding fragment thereof. In some embodiments, the vector comprises a polynucleotide sequence encoding a VL of the anti-PD-L1 antibody, or an antigen-binding fragment thereof. In some embodiments, the vector comprises a polynucleotide sequence encoding a VL and a VH of the anti-PD-L1 antibody, or an antigen- binding fragment thereof. In some embodiments, the vector comprises a polynucleotide sequence encoding a heavy chain of the anti-PD-L1 antibody, or an antigen-binding fragment thereof. In some embodiments, the vector comprises a polynucleotide sequence encoding a light chain of the anti-PD-L1 antibody, or an antigen-binding fragment thereof. In some embodiments, the vector comprises a polynucleotide sequence encoding a light chain and a heavy chain of the anti-PD-L1 antibody, or an antigen-binding fragment thereof. In some embodiments, the vector is an expression vector. In some embodiments, the vector is a cloning vector. [00250] Suitable cloning and expression vectors can include a variety of components, such as promoter, enhancer, and other transcriptional regulatory sequences. The vector may also be constructed to allow for subsequent cloning of an antibody variable domain into different vectors. [00251] Suitable cloning vectors may be constructed according to standard techniques, or may be selected from a large number of cloning vectors available in the art. While the cloning vector selected may vary according to the host cell intended to be used, useful cloning vectors will generally have the ability to self-replicate, may possess a single target for a particular restriction endonuclease, and/or may carry genes for a marker that can be used in selecting clones containing the vector. Suitable examples include plasmids and bacterial viruses, e.g., pUC18, pUC19, Bluescript (e.g., pBS SK+) and its derivatives, mp18, mp19, pBR322, pMB9, ColE1, pCR1, RP4, pCDNA, TGEX, phage DNAs, and shuttle vectors such as pSA3 and pAT28. These and many other cloning vectors are available from commercial vendors such as BioRad, Strategene, and Invitrogen. [00252] Expression vectors generally are replicable polynucleotide constructs that contain a polynucleotide according to the disclosure. Suitable expression vectors include but are not limited to plasmids, viral vectors, including adenoviruses, adeno-associated viruses, retroviruses, cosmids, and expression vector(s) disclosed in PCT Publication No. WO 87/04462. Vector components may generally include, but are not limited to, one or more of the following: a signal sequence; an origin of replication; one or more marker genes; suitable transcriptional controlling elements (such as promoters, enhancers and terminator). For expression (i.e., translation), one or more translational controlling elements are also usually required, such as ribosome binding sites, translation initiation sites, stop codons, and polyadenylation signals. [00253] The vectors containing the polynucleotides of the disclosure and/or the polynucleotides themselves, can be introduced into the host cell by any of a number of appropriate means, including electroporation, transfection employing calcium chloride, rubidium chloride, calcium phosphate, DEAE-dextran, or other substances; microprojectile bombardment; lipofection; and infection (e.g., where the vector is an infectious agent such as vaccinia virus). The choice of introducing vectors or polynucleotides will often depend on features of the host cell. [00254] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof, may be made recombinantly using a suitable host cell. A polynucleotide encoding the antibody or antigen-binding fragment thereof can be cloned into an expression vector, which can then be introduced into a host cell to obtain the synthesis of an antibody in the recombinant host cell. Host Cells [00255] An additional aspect of the disclosure is a host cell for expressing the anti-PD- L1 antibody or an antigen-binding fragment thereof. In some embodiments, the host cell comprises a polynucleotide encoding the heavy and light chains of the anti-PD-L1 antibody or fragment. In some embodiments, the host cell comprises a pair of polynucleotides: one encoding the light chain and the other encoding the heavy chain of the anti-PD-L1 antibody or fragment. In some embodiments, the host cell comprises a vector encoding the heavy and light chains of the anti-PD-L1 antibody or fragment. In some embodiments, the host cell comprises a pair of vectors: one encoding the light chain and the other encoding the heavy chain of the anti-PD-L1 antibody or fragment disclosed. In some embodiments, the host cell is an isolated host cell. [00256] In some embodiments, the host cell is an E. coli cell, a yeast cell, an insect cell, a simian COS cell, a Chinese hamster ovary (CHO) cell, a myeloma cell, or a hybridoma cell. In some embodiments, the host cell is a mammalian cell or cell line. Mammalian cell lines available as hosts for expression are well known in the art and include many immortalized cell lines available from the American Type Culture Collection (ATCC). These include, inter alia, Chinese hamster ovary (CHO) cells, NSO, SP2 cells, HeLa cells, baby hamster kidney (BHK) cells, monkey kidney cells (COS), human hepatocellular carcinoma cells (e.g., Hep G2), A549 cells, and a number of other well-known and available cell lines. Cell lines are selected through determining which cell lines have high expression levels. In some embodiments, the host cell is a CHO cell, a Human embryonic kidney (HEK) 293 cell, or an Sp2.0 cell. In some embodiments, the host cell is a CHO cell. In some embodiments, the host cell is a HEK293 cell. In some embodiments, the host cell is an Sp2.0 cell. In some embodiments, the host cell is a hybridoma cell. Other cell lines that may be used in embodiments of this disclosure are insect cell lines, such as Sf9 cells. In some embodiments, the host cell does not otherwise produce an immunoglobulin protein. Methods of Producing Anti-PD-L1 Antibodies [00257] An additional aspect of the disclosure is a method for producing the anti-PD-L1 antibody or an antigen-binding fragment thereof. The antibody, or antigen-binding fragment thereof, may be made recombinantly using a suitable host cell. A polynucleotide encoding the antibody or antigen-binding fragment thereof can be cloned into an expression vector, which can then be introduced into a host cell to obtain the synthesis of an antibody of fragment in the recombinant host cell. [00258] When recombinant expression vectors encoding antibody genes are introduced into mammalian host cells, the antibodies are produced by culturing the host cells for a period of time sufficient to allow for expression of the antibody in the host cells or in some embodiments, secretion of the antibody into the culture medium in which the host cells are grown. Antibodies can be recovered from the culture medium using standard protein purification methods. In some embodiments, the method comprises culturing a host cell disclosed herein under conditions in which the antibody or fragment is expressed by the cell. In some embodiments, the method further comprises recovering the antibody or fragment from the culture media. In some embodiments, the method further comprises isolating or purifying or partially isolating or partially purifying the antibody or fragment. Modified Anti-PD-L1 Antibodies [00259] In some embodiments of this disclosure, the anti-PD-L1 antibodies of and antigen-binding fragments and variants thereof, may be conjugated or operably linked to another compound (e.g., therapeutic agent, label, or tag), referred to herein as a conjugate. The conjugate may be a cytotoxic agent, a chemotherapeutic agent, a cytokine, an anti-angiogenic agent, a tyrosine kinase inhibitor, a toxin, a radioisotope, or other therapeutically active agent. Chemotherapeutic agents, cytokines, anti-angiogenic agents, tyrosine kinase inhibitors, and other therapeutic agents are contemplated. In some embodiments, the antibody or fragment is conjugated or operably linked to a toxin, including but not limited to small molecule toxins and enzymatically active toxins of bacterial, fungal, plant, animal or synthetic origin, including fragments and/or variants thereof. [00260] There are many linking groups known in the art for making antibody conjugates, including, for example, those disclosed in U.S. Pat. No.5,208,020 or EP Patent 0425235 B1, and Chari et al., Cancer Research 52: 127-131 (1992). The linking groups include disulfide groups, thioether groups, acid labile groups, photolabile groups, peptidase labile groups, or esterase labile groups, as disclosed in the above-identified patents, disulfide and thioether groups being preferred. Pharmaceutical Compositions [00261] An additional aspect of the present disclosure is pharmaceutical compositions and methods of use. The pharmaceutical compositions of the present disclosure include the anti PD-L1 antibody, or fragment thereof, in a pharmaceutically acceptable carrier. Pharmaceutical compositions may be administered in vivo for the treatment or prevention of a disease or disorder. Furthermore, pharmaceutical compositions comprising the antibody, or a fragment thereof, may include one or more agents for use in combination, or may be administered in conjunction with one or more agents. Agents for use in combination with the anti-PD-L1 antibody or fragment include, but are not limited to cytotoxic agents, chemotherapeutic agents, cytokines, anti-angiogenic agents, tyrosine kinase inhibitors, toxins, and radioisotopes. [00262] The pharmaceutical compositions of this disclosure may include a therapeutically effective amount or a prophylactically effective amount of the anti-PD-L1 antibody or fragment thereof. A therapeutically effective amount may vary according to factors such as the disease state, age, sex, and weight of the individual, and the ability of the antibody or fragment to elicit a desired response in the individual. A therapeutically effective amount is also one in which any toxic or detrimental effects of the antibody are outweighed by the therapeutically beneficial effects. It is routine in the art for the skilled artisan to determine a therapeutically effective amount of an antibody or fragment based on these factors. [00263] The present disclosure also provides kits relating to any of the anti PD-L1 antibodies, or fragments thereof of this disclosure, and/or methods of using them. Kits may include use in therapy, prophylaxis or diagnosis. A kit of the present disclosure may further provide instructions for use of the composition or the antibody or fragment and packaging. A kit of the present disclosure may also include devices, reagents, containers or other components. Furthermore, a kit of the present disclosure may also require the use of an apparatus, instrument or device, including a computer. Methods of Use [00264] In some embodiments of this disclosure, the anti PD-L1 antibodies and antigen- binding fragments thereof, including fully human antibodies and fragments and bispecific and multispecific antibodies, are useful for the treatment, prophylaxis or diagnosis of human disease including, but not limited to, cancer and chronic viral infection, including in the preparation of medicaments for use in those treatments. [00265] In some embodiments, the anti-PD-L1 antibody, or antigen-binding fragment thereof, is used to treat, or to prepare a medicament for treating, cancer. In some embodiments, the method comprising administering a therapeutically effective amount of the antibody, or antigen-binding fragment thereof, or a composition or medicament comprising them. In some embodiments, the method comprising administering a therapeutically effective amount of the bispecific antibody, or antigen-binding fragment thereof, or a composition or medicament comprising them. In some embodiments, the anti-PD-L1 antibody is an anti-PD-L1 bispecific antibody comprising a second or targeting antibody. In some embodiments, the anti-PD-L1 antibody is an anti-PD-L1 multi-specific antibody comprising a second or targeting antibody. One aspect of the disclosure provides use of an anti-PD-L1 bispecific antibody, or a bispecific antigen-binding fragment thereof, of the disclosure in the manufacture of a medicament for treating cancer. [00266] In some embodiments of this disclosure, the anti-PD-L1 antibody, or antigen- binding fragment thereof is used to treat, or to prepare a medicament for treating, a chronic viral infection. In some embodiments, the chronic viral infection is, without limitation, human immunodeficiency virus, hepatitis B virus, or hepatitis C virus. In some embodiments, the method comprises administering a therapeutically effective amount of the antibody, or antigen- binding fragment thereof, or a composition or medicament comprising them. In some embodiments, the method comprises administering a therapeutically effective amount of a bispecific antibody, or antigen-binding fragment thereof, or a composition or medicament comprising them. [00267] A further aspect of the disclosure provides methods of preventing cancer by administering the anti-PD-L1 antibody, or antigen-binding fragment thereof, or a composition or medicament comprising them or a composition comprising the antibody or fragment to a subject in need thereof. In some embodiments, the anti-PD-L1 antibody is an anti-PD-L1 bispecific antibody. In some embodiments, the anti-PD-L1 antibody is an anti-PD-L1 multi- specific antibody. [00268] Another aspect of the disclosure provides methods of preventing chronic viral infection by administering the anti-PD-L1 antibody, or antigen-binding fragment thereof, or a composition or medicament comprising them to a subject in need thereof. [00269] Another aspect of the disclosure is a method of maintaining cancer remission by administering an anti-PD-L1 antibody, or antigen-binding fragment thereof, or a composition or medicament comprising them a subject in need thereof. An additional aspect of the disclosure provides a method of enhancing T-cell activation using the anti-PD-L1 bispecific antibody, or an antigen-binding fragment thereof, or a composition or medicament comprising them. In some embodiments, the antibody is a bispecific antibody or fragment. In some embodiments, the bispecific antibody or fragment further comprises a second or targeting arm. In some embodiments, the anti-PD-L1 antibody is an anti-PD-L1 multi-specific antibody comprising a second or targeting antibody. EXAMPLES EXAMPLE 1 G^{ENERATION OF} A^NTI-PD-L1 H^YBRIDOMAS Immunizations [00270] Three cohorts of AlivaMab® mice (AMM-XKL, AMMK, and AMM-LO) were immunized with human PD-L1 cDNA and boosted with recombinant human, cynomolgus, and mouse PD-L1 proteins. Titers were checked by ELISA against human, cynomolgus and mouse recombinant PD-L1-His. Fusion and Screening [00271] Spleen and lymph node cells were isolated from AlivaMab® Mice and enriched for IgG-antibody expressing cells, then electro-fused with cells from a myeloma cell line (Sp2/mIL6) and seeded into 384 well plates in HAT medium to select for hybridomas. Primary screening was performed by functional PD-1/PD-L1 blocking ELISA. First, the ELISA plates were coated with human PD-L1 protein followed by blocking (1% BSA) and incubation with hybridoma supernatants for 1 hour. ELISA plates were washed and recombinant biotinylated human PD1 protein was added for 1 hour, followed by washing. PD-1/PD-L1 interaction was detected by streptavidin-HRP. Atezolizumab (Cat#ICH4018, Ichor Bio) was used as a positive control in this assay. [00272] Confirmatory screens were performed to assess binding to human and cynomolgus PD-L1 by flow cytometry against HEK293T cells overexpressing human PD-L1 as well as by ELISA against recombinant cynomolgus PD-L1 proteins. Fluorophore- or HRP- conjugated anti-mouse IgG Fc were used to detect binding of the chimeric AlivaMab® antibodies to PD-L1 (Table 4). Bio-Layer Interferometry (Sartorius Octet) assays were performed to assess the kinetics of binding of the hits to recombinant human and cynomolgus PD-L1 proteins (Table 5). Selected hits (Table 6, infra) were subcloned, scaled up for purification and sequencing by next generation sequencing (NGS). Table 4. Confirmatory Screening of Hybridoma Supernatants

Table 5. Octet Binding of non-clonal hybridoma supernatants to PD-L1-His

EXAMPLE 2 GENERATION OF ANTIBODY SEQUENCES FROM HYBRIDOMAS [00273] Hybridoma cells were lysed and total RNA was isolated using the RNeasy Midiprep kit (Qiagen, USA). First strand cDNA synthesis was performed using reverse transcriptase primed with oligo dT. Second strand synthesis was performed using a template switching oligonucleotide. Ig-encoding fragments were then generated by polymerase chain reaction using a universal upstream primer introduced in the template switching oligonucleotide and gene-specific Ig downstream primers. Barcodes and Illumina adaptor sequences were added, and samples were sequenced using a MiSeq to generate 2x300 bp paired-end reads. Sequences were sorted by barcode and analyzed to generate nucleotide sequences from which amino acid sequences were derived. EXAMPLE 3 P^{URIFICATION OF} M^ONOCLONAL A^{NTIBODIES FROM} H^YBRIDOMA S^{UPERNATANTS AND} CHARACTERIZATION OF PD-L1/PD-1 BLOCKING [00274] A panel of antibodies comprising unique VH and VL sequences was purified by protein A affinity chromatography. Hybridoma supernatants were incubated with protein A beads, the beads were washed, and antibodies were eluted with acidic pH buffer and neutralized. Samples were exchanged into phosphate buffered saline (PBS) and analyzed by HPLC-SEC (Table 6, infra). Samples were evaluated for blocking PD-1/PD-L1 binding by ELISA. First, the ELISA plates were coated with human PD-L1 protein followed by blocking (1% BSA) and incubation with purified anti-PD-L1 monoclonal antibodies starting at 30nM (followed by serial dilutions) for 1 hour. ELISA plates were washed and recombinant biotinylated human PD-1 protein was added for 1 hour, followed by washing. PD-1/PD-L1 interaction was detected by streptavidin-HRP. Atezolizumab (Cat#ICH4018, Ichor Bio) was used as a positive control in this assay. IC50 values are presented in Table 7. Table 6. Expression and Purification Characteristics of Antibodies from Clonal Hybridoma

Table 7. Blocking of PD-L1/PD-1 Interaction by Purified Anti-PD-L1 mAbs

EXAMPLE 4 IMMUNE REPERTOIRE DISPLAY, EXPRESSION, AND ANALYSIS Construction of Immune Phage Display Library [00275] Splenocytes and lymphocytes were isolated from AlivaMab® mice, immunized as described in Example 1.2.5 x 10⁷ combined cells were used to isolate total RNA using the RNeasy Midiprep kit (Qiagen, USA). Next, first strand cDNA was synthesized from ~4 ^g of total RNA using a SuperScript-III first strand cDNA synthesis kit (Thermo Scientific, USA) primed with oligo dT. Genes for variable regions of heavy chain, kappa chain, and lambda chain were PCR amplified separately using gene specific primer sets (Table 8). Primary PCR consisted of 42 reactions for heavy chain, 65 reactions for kappa chain, and 45 reactions for lambda chain amplification. Variable gene families were amplified in separate reactions containing 2 ^l of cDNA and 2 ^l of each of forward and reverse primers, using Q5 Hot Start polymerase master mix (NEB, USA). The PCR reactions were performed by heating samples at 98 ^C for 30 seconds, followed by 25 cycles of 95 ^C for 10 seconds, 55-68 ^C for 30 seconds, 72 ^C for 30 seconds. The final elongation was carried out for 2 minutes at 72 ^C before cooling at 4 ^C. PCR products were analyzed on a FlashGel and purified using a PCR clean up kit. Secondary PCR was carried out to add restriction enzyme sites and overlapping sequences for the scFv linker. Primers used for the secondary PCR are listed in Table 9. The products of the secondary PCR were gel purified and combined in such a way that each of the V gene family is presented in equimolar amount. To assemble the full length scFv, overlap extension PCR was carried out using 100 ng of each of heavy chain (VH) and light chain (VL) fragments. To maintain the diversity of the library, heavy chain fragments were mixed separately with kappa and lambda chain fragments. The overlap PCR reactions were performed using Taq polymerase and was cycled 25 times (94 ^C for 1 min, 60 ^C for 1 min, 72 ^C for 2 min), with final extension at 72 ^C for 10 minutes. The PCR products were gel purified by gel extraction kit. Table 8. Primer set for primary PCR of V genes

[00276] The assembled scFv fragment and pADL-23c phagemid vector (Antibody Design Labs, USA) were digested with BglI (NEB, USA) at 37 ^C overnight and purified by gel extraction the next day. A total of 1 ^g of digested scFv fragment was ligated into digested pADL-23c vector using T4 DNA ligase (NEB, USA) to generate the immune phage display library. Ligated DNA was electroporated into TG1 E.coli cells and plated onto 2xTY plates with 100 ^g/mL of carbenicillin and 2% glucose (2xTYCG) for incubation at 30 ^C overnight. At this stage, serial dilutions were prepared for determining the complexity of the library. By counting the number of colonies on plates, it was calculated that the phage library had >2.0E+10 total transformants of which more than 95% were functional clones (in frame, no stop codon, and no truncations). The next day, cells were scraped from plates and grown to log phase in 2xTYCG media. Once O.D.600 reached ~0.5, the cell culture was infected with CM13 hyperphage (Antibody Design Labs, USA) at an MOI of 10 phage per cell. After one hour of incubation at 37 ^C, cells were centrifuged and resuspended in 2xTY media with 100 ^g/mL of carbenicillin and 50 ^g/mL of kanamycin and incubated overnight at 30 ^C. The following day, cells were centrifuged, and phage were purified from supernatant using PEG precipitation. Table 9. Primer set for the secondary PCR

Phage Panning [00277] An aliquot of scFv-phage library containing ~10¹² phage particles was blocked in 3% skim milk powder in PBS (w/v) for 1 hour at room temperature. The blocked library was subsequently depleted against streptavidin magnetic beads for 1 hour at room temperature. For the first round of panning, the depleted library was incubated with 100 nM of recombinant biotinylated-huPD-L1 for 1 hour at room temperate with rotation. The huPD-L1 bound phage were captured using blocked streptavidin magnetic beads. Beads were collected using a magnetic separator and any non-specifically bound phage were removed by washing beads 5 times with 0.2% Tween-20/PBS followed by 5 additional washes with PBS. To elute huPD-L1 bound phage, beads were incubated with 500 ^L of TEPC-treated tryspsin (100 ng/ ^L) for 30 minutes at room temperature. The eluted phage was used to infect TG1 Cells at log phase (O.D. ~ 0.5) for one hour at 37 ^C, followed by plating onto 2xTYCG plates overnight at 30 ^C. Following incubating agar plates at 30 ^C overnight, bacteria were scraped from these plates and an aliquot of it was used to start a fresh 5 ml culture in 2xTYCG media. When the O.D.₆₀₀ reached ~0.5, the culture was superinfected with hyperphage with multiplicity of infection (MOI) of 10 phage particles per cell and incubated at 37 ^C for 1 hour at 170 rpm shaking. Cells were pelleted at 3000 rpm for 10 minutes and supernatant was discarded. Pelleted cells were resuspended in 5 ml of 2xTY media supplemented with 100 ^g/mL of carbenicillin and 50 ^g/mL of kanamycin. The culture was incubated overnight at 28 ^C and 250 rpm to drive the phage expression. Next day, cells were pelleted at 3000 rpm for 10 minutes and phage containing supernatant was collected for the next round of panning. A total of 3 rounds of panning were carried out with increasing washing stringency for each round (Table.10). Table.10 Conditions and enrichment factor for every round of panning

Reformatting into scFv-Fc [00278] After 3 rounds of panning, the genes encoding scFv fragments were PCR amplified (FWD primer: 5’-CTTCCGGCTCGTATGTTGTGTG-3’ and REV primer: 5’- GTCGTCTTTCCAGACGTTAGTAAATG-3’) and purified using a PCR clean up kit. The receiving vector, TGEX-SCblue (Antibody Design Labs, USA) was designed for mammalian expression of scFv-Fc fusion protein. The scFv fragment and the TGEX-SCblue vector, were digested with SfiI enzyme (NEB, USA) overnight at 37 ^C. After gel extraction and purification, the digested vector and scFv fragments were ligated using T4 DNA Ligase (NEB, USA) at 16 ^C overnight. The next day, the ligated DNA was transformed into Stellar competent E. coli cells by heat shock and plated on 2XTYCG plates and grown overnight at 37 ^C. The following day, single colonies were picked into 96-deep well plates for incubation at 37 ^C overnight. Plasmids were extracted from the overnight culture using transfection grade 96-well miniprep kits. These plasmids preps were used for transfection in to Expi293 cells for scFv-Fc fusion protein expression. Binding ELISA [00279] To identify huPD-L1 specific antibodies, 384 well black plates were coated with 1 ^g/ml of huPD-L1-mFc protein (Acro biosystems, USA) overnight at 4 ^C. The next day, plates were washed 3 times with ELISA washing buffer (0.05% Tween-20 in PBS) before blocking wells with the blocking buffer (1% BSA in PBS) for 1 hour at room temperature. scFv-Fc samples were diluted 1:1 with ELISA assay buffer (1% BSA + 0.05% Tween-20 in PBS) and added to blocked assay plates. After 1 hour of incubation at room temperature, plates were washed 4 times with washing buffer, followed by incubation with HRP-conjugated anti- human Fc secondary antibody for 1 hour. Plates were washed 5 times with ELISA buffer and binding was detected using SuperSignal ELISA pico chemiluminescent substrate (ThermoFisher Scientific, USA) (Figure 1A, Table 11, infra). Blocking ELISA [00280] To identify huPD-L1 specific antibodies that also blocks PD-L1 to PD-1 interaction, a blocking ELISA was developed. First, 384 well black plates were coated with 1 ^g/ml of huPD-L1-mFc protein (Acro biosystems, USA) overnight at 4 ^C. The next day, plates were washed 3 times with ELISA washing buffer (0.05% Tween-20 in PBS) before blocking wells with the blocking buffer (1% BSA in PBS) for 1 hour at room temperature. scFv-Fc samples were diluted 1:1 with ELISA assay buffer (1% BSA + 0.05% Tween-20 in PBS) and added to blocked assay plates. After 1 hour of incubation at room temperature, plates were washed 4 times with washing buffer, followed by incubation with 1 ^g/ml of biotinylated- huPD-1 protein for 1 hour. Next, plates were washed 4 times with washing buffer and incubated with HRP-conjugated Streptavidin protein for 1 hour. Following incubation, plates were washed 5 times with ELISA buffer and binding was detected using SuperSignal ELISA pico chemiluminescent substrate (ThermoFisher Scientific, USA). Results are presented in Figure 1B, Table 11. Table 11: Results of the Binding and Blocking ELISA

Octet [00281] A panel of scFv-Fcs was assessed by Octet for binding to recombinant human PD-L1 using Anti-hIgG Fc Capture (AHC) Biosensors (Table 12). Table 12. Binding of Phage-derived scFv-Fc to human PD-L1-His by Octet.

EXAMPLE 5 G^{ENERATION AND} C^{HARACTERIZATION OF} B^ISPECIFIC A^NTIBODIES Generation of Plasmids Encoding Bispecific Constructs [00282] Sequences derived from hybridoma candidates were selected for cloning based on FACS and Octet analysis as described in Examples above. These were reformatted as scFv in VL-VH and VH-VL orientations of the variable heavy and light chains. These were made as disulfide bond stabilized scFv by mutating VH44 and VL100 to Cys (Kabat numbering). These scFvs were cloned onto an HC from a human IgG1 antibody in a proprietary vector as either N-term scFv fusion (BiSAb1 format) and C-term scFv fusion (BiSAb2 format) (Digiandomenico, A et al, Sci Transl Med.2014 Nov 12;6(262):262ra155), with an anti-Lag3 Fab derived from tebotelimab (MGD013, PD1/Lag3 bispecific, Macrogenics). [00283] Cloning into AlivaMab proprietary vector (ALP1E21) for eukaryotic expression was performed with Takara Infusion HD using standard molecular biology techniques. Positive clones were confirmed by rolling circle amplification (RCA) followed by Sanger sequencing and milligram quantity DNA was made using Endo-EF maxiprep kit (Takara) to achieve low endotoxin levels. The panel of PD-L1 scFv-anti-Lag3 (tebotilimab) in BiSAb1 and BiSAb2 formats were then transfected along with tebotilimab anti-Lag3 LC in Expi293 to make BiSAbs (Figure 2, Table 1F, supra). Tebotilimab Heavy Chain (SEQ ID NO.: 1107): QVQLVQSGAEVKKPGASVKVSCKASGYTFTDYNMDWVRQAPGQGLEWMGDINPD NGVTIYNQKFEGRVTMTTDTSTSTAYMELRSLRSDDTAVYYCAREADYFYFDYWG QGTTLTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSG VHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKT HTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVD GVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTI SKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKT TPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK Tebotilimab Light Chain (SEQ ID NO.: 1109): DIQMTQSPSSLSASVGDRVTITCRASQDVSSVVAWYQQKPGKAPKLLIYSASYRYTG VPSRFSGSGSGTDFTLTISSLQPEDFATYYCQQHYSTPWTFGGGTKLEIKRTVAAPSVF IFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTY SLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC Expression and Purification of Bispecific Constructs [00284] Antibodies were expressed in Expi293 (HEK) cells following Thermofisher guidelines for the Expi293 Expression System (Publication number MAN0007814). Antibodies were expressed in 30 mL cultures in 125 mL Thomson Flasks (PN: 931110). [00285] Antibodies were harvested after 4 days of expression by adding diatomaceous earth into the expression flask and filtered using 0.2 µm Steriflips (Millipore PN: SCGP00525). The collected supernatants were purified on an Akta Pure using a 1 mL HiTrap MabSelect SuRe column with a loading flow rate of 4 mL/min. Once loaded, the column was washed with 5 CV of PBS and antibodies were eluted with 50 mM sodium acetate pH 3.5 and neutralized with 1 M tris pH 8.0. After neutralization antibodies were buffer exchanged into 1 x PBS pH 7.4 using 50 kD MWCO spin concentrators (Sartorious PN:VS0632) by concentrating the neutralized eluted antibodies then filling the spin concentrator to the 6 mL mark and concentrating again. This was repeated 3 times to ensure complete buffer exchange. [00286] After the antibodies were collected, the concentration and yield were determined by A260 on a NanoDrop spectrophometer. Antibody quality was analyzed by SEC- HPLC on a TSKgel SuperSW3000 (4.6 mm ID x 30 cm, 4 um, Tosoh PN: 18675) column equipped with a guard column (Tosoh) using 0.1 M NaPO₄ and 0.1 M NaSO₄ pH 6.8 at a flow rate of 0.35 mL/min. Peak analysis was done using CDS Open Lab 2.6. Next, antibodies were polished on semi-preparative SEC-HPLC column (Zenix 7.8x300mm) to remove aggregates and get monomeric content above 95%. After the polishing step, BiSAbs were again buffer exchanged into 1 x PBS pH 7.4 using 50 kD MWCO spin concentrators (Sartorious PN:VS0632) by concentrating the neutralized eluted antibodies then filling the spin concentrator to the 6 mL mark and concentrating again. This was repeated 3 times to ensure complete buffer exchange. [00287] After the antibodies were collected, the concentration and yield were determined by A260 using a NanoDrop spectrophometer. Antibody quality was analyzed by SEC-HPLC on a TSKgel SuperSW3000 (4.6 mm ID x 30 cm, 4 um, Tosoh PN: 18675) column equipped with a guard column (Tosoh) using 0.1 M NaPO₄ and 0.1 M NaSO₄ pH 6.8 at a flow rate of 0.35 mL/min. Peak analysis was done using CDS Open Lab 2.6. Titers and purity are reported in Table 13. Table 13. Bispecific Antibody Expression Characteristics

[00288] A panel of bispecific antibodies was assessed by Octet for binding to recombinant human PD-L1, cyno PD-L1, and human LAG3 using FAB2G biosensors (Table 14, 15, and 16, respectively). In addition, binding to human recombinant PD-L1 was confirmed by ELISA using HRP-conjugated Goat anti-human IgG Fc (Jackson ImmunoResearch Labs, Inc., West Grove, PA) (Table 17, infra). PD-1/PD-L1 functional blocking ELISA assay was performed to calculate IC50 for a subset of bispecific antibodies (Table 17, infra). Table 14. Binding of Bispecific Antibodies to human PD-L1 by Octet.

Table 15. Binding of Bispecific Antibodies to cyno PD-L1 by Octet.

Table 16. Binding of Bispecific Antibodies to human LAG3 by Octet.

Table 17. Binding of Bispecific Antibodies to human PD-L1 and blocking PD-1/PD-L1 interaction by ELISA.

[00289] A panel of bispecific antibodies was selected for further characterization in additional assays to assess their functionality using reporter cell lines obtained from Promega: PD-1/PD-L1 Blockade Bioassay (J1250), LAG3/MHCII Blockade Bioassay (JA1111), and PD-1+LAG-3 Combo Blockade Bioassay (CS1978B11). Tebotelimab-derived anti-LAG3 and anti-PD-L1 mAb control were used as controls, individually, or in combination. Reporter assay results are summarized in Tables 18-20. Table 18. Functional activity of bispecific antibodies in PD-1/ PD-L1 reporter assay.

Table 19. Functional activity of bispecific antibodies in LAG3 reporter assay.

Table 20. Functional activity of bispecific antibodies in combo PD-1/ PD-L1 and LAG3/MHC reporter assay.

EXAMPLE 6 CHARACTERIZATION OF FAVORABLE BIOPHYSICAL CHARACTERISTICS T_m/T_agg analysis [00290] Samples were loaded in duplicate into 9 µL wells called a Uni on an UNCLE instrument (Unchained Labs) and thermal data were analyzed by the Uncle instrument software. The following parameters are obtained: 1. starting temperature of first melt (T_onset), 2. melting temperature transitions (TM), and 3. aggregation temperature transitions at two different wavelengths (T_agg). Full spectrum intrinsic fluorescence is used to obtain T_m and T_onset while static light scattering is used to obtain T_agg. Polyspecific Reagent/nonspecific binding (PSR/NSB) ELISA [00291] PSR/NSB ELISA was employed to measure polyspecific/nonspecific antibody binding to various antigens: ds DNA (D4544, Sigma) and ss DNA (D8899 Sigma), cardiolipin (C0563, Sigma), insulin (l9278, Sigma), lipopolysaccharide (LPS; tlrl-eblps, InvivoGen), and Hemocyanin (H8283, Sigma). he wells were coated with a mixture of the antigens, and the plate was then blocked with 1% BSA. Wells were washed after every step, test antibodies and controls were added followed by a secondary HRP-conjugated Goat anti-human IgG Fc (Jackson ImmunoReasearch Labs, Inc., West Grove, PA). The plate was developed with TMB and read on a plate reader with the setting at OD650. Results are described in Figure 3A and Table 21. BVP ELISA [00292] BVP ELISA measuring nonspecific/polyspecific antibody binding to Baculovirus Particles (BVP). The plate is coated with BVP antigen (E3001 Medna), and the plate is blocked with 1% BSA, washes follow every step, test antibodies and controls are added followed by a secondary HRP-conjugated Goat anti-human IgG Fc (Jackson ImmunoReasearch Labs, Inc., West Grove, PA). The plate is developed with TMB and read on a plate reader with the setting at OD650. Results are described in Figure 3B and Table 21. Hydrophobic interaction chromatography (HIC) Analysis [00293] Each bispecific Ab was diluted with HN4SO4 to final concentration of 1 M HN₄SO_4, and 10ug was injected into HPLC. The antibody species are then eluted using a reverse NaCl gradient (high concentration to low concentration). The retention time of the antibody is measured on a HIC-butyl column (Proteomix HIC Butyl-NP5) with less hydrophobic species eluting earlier and more hydrophobic species eluting later. Results are described in Figure 3C and Table 21. Table 21. Developability assessments of PD-L1 Bispecific molecules

Claims

WHAT IS CLAIMED: 1. An isolated anti-PD-L1 antibody, or an antigen-binding fragment thereof, comprising: i) a heavy chain variable region (VH) comprising a HCDR1 selected from any of SEQ ID NOs: 322-428, a HCDR2 selected from any of SEQ ID NOs: 429-535, and a HCDR3 selected from any of SEQ ID NOs: 536-642 and ii) a light chain variable region (VL) comprising a LCDR1 selected from any of SEQ ID NOs : 1-107, a LCDR2 selected from any of SEQ ID NOs: 108-214, and a LCDR3 selected from any of SEQ ID NOs : 215-321.

2. The antibody, or antigen-binding fragment thereof, of claim 1, wherein the VH region is selected from any one of SEQ ID NOs: 857-1070.

3. The antibody, or antigen-binding fragment thereof, of claims 1 or 2, wherein the VL region is selected from any one of SEQ ID NOs: 643-856.

4. The antibody, or antigen-binding fragment thereof, of any one of claims 1-3, wherein the antibody is humanized or fully human.

5. The antibody, or antigen-binding fragment thereof, of any one of claims 1-3, wherein the antibody is chimeric.

6. The antibody, or antigen-binding fragment thereof, of any one of claims 1-5, wherein the antibody is selected from a single-variable domain antibody, single chain antibody, a scFv, a bispecific antibody, a multi-specific antibody, a Fab, a F(ab')2, and a whole antibody.

7. The antibody, or antigen-binding fragment thereof, of claim 6, wherein the antibody is a multi-specific antibody.

8. The antibody, or antigen-binding fragment thereof, of claim 6, wherein the antibody is a bispecific antibody.

9. The antibody, or antigen-binding fragment thereof, of claim 6, wherein the antibody is a bispecific antibody comprising a first and second Fc domain.

10. The antibody, or antigen-binding fragment thereof, of claim 9, wherein the antibody is a bispecific antibody comprising identical Fc domains and identical light chains.

11. The antibody, or antigen-binding fragment thereof, of any of claims 8-10, wherein the bispecific antibody further comprises a second or a targeting antibody.

12. The antibody, or antigen-binding fragment thereof, of claim 11, wherein the targeting antibody is an immune cell, cancer or virally infected cell targeting antibody, or an antigen- binding fragment thereof.

13. The antibody, or antigen-binding fragment thereof, of claims 9 or 10, wherein the anti- PD-L1 antibody, or the antigen-binding fragment thereof, comprises an scFv.

14. The antibody, or antigen-binding fragment thereof, of claims 6 or 13, wherein the anti- PD-L1 scFv antibody comprises an amino acid sequence selected from any one of SEQ ID NOs: 1071-1102.

15. The antibody, or antigen-binding fragment thereof, of claims 13 or 14, wherein the anti-PD-L1 scFv antibody is operably linked to a heavy chain of a bispecific antibody.

16. The antibody, or antigen-binding fragment thereof, of claims 13 or 14, wherein the anti- PD-L1 scFv antibody is operably linked to a first Fc domain.

17. The antibody, or antigen-binding fragment thereof, of claim 16, wherein the anti- PD- L1 scFv antibody is operably linked to the first Fc domain through a first linker.

18. The antibody, or antigen-binding fragment thereof, of claim 9, wherein the targeting antibody, or the antigen-binding fragment thereof, comprises a Fab fragment or a F(ab’)2 fragment.

19. The antibody, or antigen-binding fragment thereof, of claim 18, wherein the targeting Fab or F(ab’)2 fragment is operably linked to the second Fc domain.

20. The antibody, or antigen-binding fragment thereof, of claim 19, wherein the targeting Fab or F(ab’)₂ fragment is operably linked to the second Fc domain through a second linker.

21. The antibody, or antigen-binding fragment thereof, of claims 18 or 20, wherein the first linker or second linker is a variable length Gly-Ser linker.

22. The antibody, or antigen-binding fragment thereof, of claim 21, wherein the first linker and the second linker are independently selected from the group consisting of SEQ ID NOs.: 1103-1106 and 1111-1112.

23. The antibody, or antigen-binding fragment thereof, of claim 9, wherein the first and second Fc domain comprises complementary mutations selected from knobs-into-holes (KIH) mutations, K409R/F405L, HA-TF and related mutations, skew mutations, ZW mutations, 7.8.60 mutations or related mutations, DD-KK mutations or related mutations, EW-RVT mutations or related mutations, strand-exchange engineered domains (SEED), Duobody mutations, CrossMAb mutations, or A107 mutations or related mutations.

24. The antibody, or antigen-binding fragment thereof, of claim 23, wherein (1) the first Fc domain comprises a T366W mutation and the second Fc domain comprises T366S/L368A/Y407V mutations; (2) the first Fc domain comprises T366S/L368A/Y407V mutations and the second Fc domain comprises a T366W mutation; (3) the first Fc domain comprises S354C/T366W mutations and the second Fc domain comprises Y349C/T366S/L368A/Y407V mutations; (4) the first Fc domain comprises Y349C/T366S/L368A/Y407V mutations and the second Fc domain comprises S354C/T366W mutation; (5) the first Fc domain comprises S354C/T366W mutations and the second Fc domain comprises Y349C/T366S/L368A/Y407V/H435R/Y436F mutations; (6) the first Fc domain comprises Y349C/T366S/L368A/ Y407V/H435R/Y436F mutations and the second Fc domain comprises S354C/T366W mutations; 7) the first Fc domain comprises S354C/T366W/H435R/Y436F mutations and the second Fc domain comprises Y349C/T366S/L368A/Y407V mutations; or 8) the first Fc domain comprises Y349C/T366S/L368A/Y407V mutations and the second Fc domain comprises S354C/T366W/H435R/Y436F mutations.

25. The antibody, or antigen-binding fragment thereof, of claim 23, wherein the heavy chain operably linked to the anti-PD-L1 scFv antibody comprises the amino acid sequence of SEQ ID NO: 1107.

26. The antibody, or antigen-binding fragment thereof, of claim 25, wherein the second or targeting antibody comprises a light chain comprising the amino acid sequence of SEQ ID NO: 1109.

27. The antibody, or antigen-binding fragment thereof, of claim 23, wherein (1) the first Fc domain comprises a S364H mutation and the second Fc domain comprises a Y349T mutation; (2) the first Fc domain comprises a Y349T mutation and the second Fc domain comprises a S364H mutation; (3) the first Fc domain comprises a F405A mutation and the second Fc domain comprises a T394F mutation; (4) the first Fc domain comprises a T394F mutation and the second Fc domain comprises a F405A mutation; (5) the first Fc domain comprises S364H/T394F mutations and the second Fc domain comprises Y349T/F405A mutations; (6) the first Fc domain comprises Y349T/F405A mutations and the second Fc domain comprises S364H/T394F mutations; (7) the first Fc domain comprises S364H/F405A mutations and the second Fc domain Y349T/T394F mutations; or (8) the first Fc domain comprises Y349T/T394F mutations and the second Fc domain S364H/F405A mutations.

28. The antibody, or antigen-binding fragment thereof, of claim 23, wherein (1) the first Fc domain comprises S364K/E357Q mutations and the second Fc domain comprises L368D/K370S mutations; (2) the first Fc domain comprises L368D/K370S mutations and the second Fc domain comprises S364K/E357Q mutations; (3) the first Fc domain comprises L368D/K370S mutations and the second Fc domain comprises a S364K mutation; (4) the first Fc domain comprises a S364K mutation and the second Fc domain comprises L368D/K370S mutations; (5) the first Fc domain comprises L368E/K370S mutations and the second Fc domain comprises a S364K mutation; (6) the first Fc domain comprises a S364K mutation and the second Fc domain comprises L368E/K370S mutations; (7) the first Fc domain comprises T411E/K360E/Q362E mutations and the second Fc domain comprises a D401K mutation; (8) the first Fc domain comprises a D401K mutation and the second Fc domain comprises T411E/K360E/Q362E mutations; (9) the first Fc domain comprises L368D/K370S mutations and the second Fc domain comprises S364K/E357L mutations; (10) the first Fc domain comprises S364K/E357L mutations and the second Fc domain comprises L368D/K370S mutations; (11) the first Fc domain comprises a K370S mutation and the second Fc domain comprises S364K/E357Q mutations; (12) the first Fc domain comprises S364K/E357Q mutations and the second Fc domain comprises a K370S mutation; (13) the first Fc domain comprises T366S/L368A/Y407V mutations and the second Fc domain comprises a T366W mutation; (14) the first Fc domain comprises a T366W mutation and the second Fc domain comprises T366S/L368A/Y407V mutations; (15) the first Fc domain comprises T366S/L368A/Y407V/Y349C mutations and the second Fc domain comprises T366W/S354C mutations; or (16) the first Fc domain comprises T366W/S354C mutations and the second Fc domain comprises T366S/L368A/Y407V/Y349C mutations.

29. The antibody, or antigen-binding fragment thereof, of claim 23, wherein (1) the first Fc domain comprises F405A/Y407V mutations and the second Fc domain comprises a T394W mutation; (2) the first Fc domain comprises a T394W mutation and the second Fc domain comprises F405A/Y407V mutations; (3) the first Fc domain comprises F405A/Y407V mutations and the second Fc domain comprises T366I/T394W mutations; (4) the first Fc domain comprises T366I/T394W mutations and the second Fc domain comprises F405A/Y407V mutations; (5) the first Fc domain comprises F405A/Y407V mutations and the second Fc domain comprises T366L/T394W mutations; (6) the first Fc domain comprises T366L/T394W mutations and the second Fc domain comprises F405A/Y407V mutations; (7) the first Fc domain comprises F405A/Y407V mutations and the second Fc domain comprises T366L/K392M/T394W mutations; (8) the first Fc domain comprises T366L/K392M/T394W mutations and the second Fc domain comprises F405A/Y407V mutations; (9) the first Fc domain comprises L351Y/F405A/Y407V mutations and the second Fc domain comprises T366L/K329M/T394W mutations; (10) the first Fc domain comprises T366L/K329M- /T394W mutations and the second Fc domain comprises L351Y/F405A/Y407V mutations; (11) the first Fc domain comprises T350V/L351Y/F405A/Y407V mutations and the second Fc domain comprises T350V/T366L/K392M/T394W mutations; (12) the first Fc domain comprises T350V/T366L/K392M/T394W mutations and the second Fc domain comprises T350V/L351Y/F405A/Y407V mutations; (13) the first Fc domain comprises T350V/L351Y/F405A/Y407V mutations and the second Fc domain comprises T350V/T366L -/K392L/T394W mutations; or (14) the first Fc domain comprises T350V/T366L/K392L- /T394W mutations and the second Fc domain comprises T350V/L351Y/F405A/Y407V mutations.

30. The antibody, or antigen-binding fragment thereof, of claim 23, wherein (1) the first Fc domain comprises D399M/Y407A mutations and the second Fc domain comprises T366V/K409V mutations; (2) the first Fc domain comprises T366V/K409V mutations and the second Fc domain comprises D399M/Y407A mutations; (3) the first Fc domain comprises K360D/D399M/Y407A mutations and the second Fc domain comprises E345R/Q347R/T366V/K409V mutations; (4) the first Fc domain comprises E345R/Q347R/T366V/K409V mutations and the second Fc domain comprises K360D/D399M/Y407A mutations; (5) the first Fc domain comprises Y349S/K370Y/T366V- /K409V mutations and the second Fc domain comprises E357D/S364Q/Y407A mutations; (6) the first Fc domain comprises E357D/S364Q/Y407A mutations and the second Fc domain comprises Y349S/K370Y/T366V/K409V mutations; (7) the first Fc domain comprises Y349S/K370Y/T366M/K409V mutations, and the second Fc domain comprises E356G/E357D/S364Q/Y407A mutations; (8) the first Fc domain comprises E356G/E357D/S364Q/Y407A mutations, and the second Fc domain comprises Y349S/K370Y/T366M/K409V mutations; (9) the first Fc domain comprises Y349S/K370Y/T366M/K409V mutations and the second Fc domain comprises E357D/S364R/Y407A mutations; or (10) the first Fc domain comprises E357D/S364R/Y407A mutations and the second Fc domain comprises Y349S/K370Y/T366M/K409V mutations.

31. The antibody, or antigen-binding fragment thereof, of claim 23, wherein (1) the first Fc domain comprises K409D/K392D mutations and the second Fc domain comprises D399K/E356K mutations; (2) the first Fc domain comprises D399K/E356K mutations and the second Fc domain comprises K409D/K392D mutations; (3) the first Fc domain comprises K409E/K392D mutations and the second Fc domain comprises D399R/E356K mutations; (4) the first Fc domain comprises D399R/E356K mutations and the second Fc domain comprises K409E/K392D mutations; (5) the first Fc domain comprises K409D/K392D mutations and the second Fc domain comprises D399R/E356K mutations; (6) the first Fc domain comprises D399R/E356K mutations and the second Fc domain comprises K409D/K392D mutations; (7) the first Fc domain comprises K409E/K392D mutations and the second Fc domain comprises D399K/E356K mutations; (8) the first Fc domain comprises D399K/E356K mutations and the second Fc domain comprises K409E/K392D mutations; (9) the first Fc domain comprises K409D/K392D/K370D mutations and the second Fc domain comprises D399K/E356K/- E357K mutations; or (10) the first Fc domain comprises D399K/E356K/E357K mutations and the second Fc domain comprises K409D/K392D/K370D mutations.

32. The antibody, or antigen-binding fragment thereof, of claim 23, wherein (1) the first Fc domain comprises a K409W mutation and the second Fc domain comprises F405T/D399V mutations; (2) the first Fc domain comprises F405T/D399V mutations and the second Fc domain comprises a K409W mutation; (3) the first Fc domain comprises K360E/K409W mutations and the second Fc domain comprises Q347R/D399V/F405T mutations; (4) the first Fc domain comprises Q347R/D399V/F405T mutations and the second Fc domain comprises K360E/K409W mutations; (5) the first Fc domain comprises K360E/K409W/Y349C mutations and the second Fc domain comprises Q347R/D399V/F405T/S354C mutations; or (6) the first Fc domain comprises Q347R/D399V/F405T/S354C mutations and the second Fc domain comprises K360E/K409WY349C mutations.

33. The antibody, or antigen-binding fragment thereof, of claim 23, wherein (1) the first Fc domain comprises an AG SEED domain and the second Fc domain comprises a GA SEED domain or (2) the first Fc domain comprises a GA SEED domain and the second Fc domain comprises an AG SEED domain.

34. The antibody, or antigen-binding fragment thereof, of claim 23, wherein (1) the first Fc domain comprises K370E/K409W mutations and the second Fc domain comprises E357N/D399V/F405T mutations; (2) the first Fc domain comprises E357N/D399V/F405T mutations and the second Fc domain comprises K370E/K409W mutations; (3) the first Fc domain comprises K370E/K409W mutations and the second Fc domain comprises E357I/S364T/D399V/F405T mutations; (4) the first Fc domain comprises E357I/S364T/D399V/F405T mutations and the second Fc domain comprises K370E/K409W mutations; (5) the first Fc domain comprises K370M/K409W mutations and the second Fc domain comprises E357M/S364W/D399V/F405T mutations; (6) the first Fc domain comprises E357M/S364W/D399V/F405T mutations and the second Fc domain comprises K370M/K409W mutations; (7) the first Fc domain comprises K370D/K409W mutations and the second Fc domain comprises E357M/D399V/F405T mutations; (8) the first Fc domain comprises E357M/D399V/F405T mutations and the second Fc domain comprises K370D/K409W mutations; (9) the first Fc domain comprises E357D/S364W/K370E mutations and the second Fc domain comprises E357N/K370R mutations; (10) the first Fc domain comprises E357N/K370R mutations and the second Fc domain comprises E357D/S364W/K370E mutations; (11) the first Fc domain comprises E357A/S364Y/K370E mutations and the second Fc domain comprises E357N/K370H mutations; (12) the first Fc domain comprises E357N/K370H mutations and the second Fc domain comprises E357A/S364Y/K370E mutations; (13) the first Fc domain comprises E357G/S364W/K370E mutations and the second Fc domain comprises an E357N mutation; (14) the first Fc domain comprises an E357N mutation and the second Fc domain comprises E357G/S364W/DK70E mutations; (15) the first Fc domain comprises E357N/S364W/K370E mutations and the second Fc domain comprises an E357N mutation; or (16) the first Fc domain comprises an E357N mutation and the second Fc domain comprises E357N/S364W/DK70E mutations.

35. The antibody, or antigen-binding fragment thereof, of claim 9, wherein the first and/or second Fc domain are independently engineered to have improved pharmacokinetics (PK).

36. The antibody, or antigen-binding fragment thereof, of claim 35, wherein the first and/or second Fc domains comprise amino acid substitutions M428L and/or N434S.

37. The antibody, or antigen-binding fragment thereof, of claim 11, wherein the second antibody or anti-immune cell targeting antibody is an anti-Lag3 antibody.

38. The antibody, or antigen-binding fragment thereof, of claim 37, wherein the anti-Lag3 antibody comprises the VH of SEQ ID:1108.

39. The antibody, or antigen-binding fragment thereof, of claims 37 or 38, wherein the anti-Lag3 antibody comprises the VL of SEQ ID:1110.

40. The antibody, or antigen-binding fragment thereof, of any one of claims 1-39, wherein the antibody is selected from an IgG antibody, an IgM antibody, an IgA antibody, an IgD antibody, and an IgE antibody.

41. The antibody, or antigen-binding fragment thereof, of claim 40, wherein the antibody is an IgG antibody.

42. The antibody, or antigen-binding fragment thereof, of claim 41, wherein the antibody is a variant of an IgG antibody selected from an IgG1 antibody, an IgG2 antibody, an IgG3 antibody or an IgG4 antibody.

43. The antibody, or antigen-binding fragment thereof, of claim 42, wherein the antibody comprises a modified Fc domain derived from an IgG1 molecule.

44. The antibody, or antigen-binding fragment thereof, of claim 43, wherein the modified Fc domain derived from the IgG1 molecule comprises an amino acid modification at any one of the positions selected from the group consisting of E216, R217, K218, C219, C220, C226, C229, P230, E233, L234, L235, G236, G237, P238, S239, V240, F241, K246, L251, T260, D265, V266, H268, W277, N297, E318, K322, P329, A330, P331, Q347, N348, T350, L351, K360, T366, N390, K392, T394, D399, S400, F405, Y407, K409, and T411 or a combination such amino acid modifications.

45. The antibody, or antigen-binding fragment thereof, of claim 43, wherein the modified Fc domain derived from IgG1 comprises an amino acid modification selected from the group consisting of C220S, C226S, C229S, P230S, E233P, L234A, L234F, L234V, L235A, L235E, L235V, G236E, G237A, P238S, D265S, D265A, H268Q, W277T, N297G, N297Q, N297D, N297A, E318A, K322A, P329G, P329A, A330S, P331S, Q347R, Q347E, Q347K, T350V, L351Y, K360D, K360E, T366A, T366I, T366L, T366M, T366V, N390R, N390K, N390D, K392V, K392M, K392R, K392L, K392F, K392E, T394W, D399R, D399W, D399K, S400E, S400D, S400R, S400K, F405A, F405I, F405M, F405T, F405S, F405V, F405W, Y407A, Y407I, Y407L, Y407V, K409F, K409I, K409S, K409W, T411N, T411R, T411Q, T411K, T411D, T411E, T411W, ∆E216-E222, K246R/L251E/T260R, InR234/235, InV235/236, InR236/237, InR237/238, InV238/239, InN238/239, InL238/239, InE238/239, InG238/239, InS239/240, InG240/241, InE240/241, InG240/241, InL238/239/P238Q, InE238/239/N348A, InS239/240/V266A, and InR237/238/G236A or a combination thereof.

46. The antibody, or antigen-binding fragment thereof, of claim 45, wherein the modified Fc domain derived from IgG1 comprises L234F/L235E/P331S mutations.

47. The antibody, or antigen-binding fragment thereof, of claim 42, wherein the antibody comprises a modified Fc domain derived from an IgG2 molecule.

48. The antibody, or antigen-binding fragment thereof, of claim 47, wherein the modified Fc domain derived from the IgG2 molecule comprises an amino acid modification at any one of the positions selected from the group consisting of V234, G237, P238, H268, V309, A330, and P331 or a combination thereof.

49. The antibody, or antigen-binding fragment thereof, of claim 48, wherein the modified Fc domain derived from the IgG2 molecule comprises an amino acid modification selected from the group consisting of V234A, G237A, P238S, H268Q, H268A, V309L, A330S, and P331S, or a combination thereof.

50. The antibody, or antigen-binding fragment thereof, of claim 42, wherein the antibody comprises a modified Fc domain derived from an IgG4 molecule.

51. The antibody, or antigen-binding fragment thereof, of claim 50, wherein the modified Fc domain derived from the IgG4 molecule comprises an amino acid modification at any one of the positions selected from the group consisting of S228, L235, L236, G237, E318, and N297 or a combination thereof.

52. The antibody, or antigen-binding fragment thereof, of claim 51, wherein the modified Fc domain derived from the IgG4 molecule comprises an amino acid modification selected from the group consisting of S228P, L235A, L235E, L236E, G237A, E318A, and N297Q or a combination thereof.

53. A polynucleotide encoding an anti-PD-L1 antibody, or antigen-binding fragment thereof, of any one of claims 1-52.

54. An expression vector comprising the polynucleotide of claim 53.

55. An expression vector comprising a first polynucleotide encoding the heavy chain of an anti- PD-L1 antibody, or antigen-binding fragment thereof, of any one of claims 1-52 and a second polynucleotide encoding the light chain of an anti- PD-L1 antibody, or antigen- binding fragment thereof, of any one of claims 1-52.

56. An isolated host cell comprising the polynucleotide of claim 51, the expression vector of claim 55.

57. A method of producing the antibody, or antigen-binding fragment thereof, or any one of claims 1-52, the method comprising culturing the host cell of claim 56 under conditions suitable for expressing the antibody or fragment.

58. A composition comprising the antibody, or antigen-binding fragment thereof, of any one of claims 1-52 and a pharmaceutically acceptable carrier.

59. A method of treating or preventing cancer in a subject in need thereof, the method comprising administering the antibody, or antigen-binding fragment thereof, of any one of claims 1-52 or the composition of claim 58 to the subject.

60. A method of maintaining cancer remission in a subject whose cancer is in remission, the method comprising administering the antibody, or antigen-binding fragment thereof, of any one of claims 1-52 or the composition of claim 58 to the subject.

61. The method of claims 59 or 60, wherein the anti- PD-L1 antibody is an anti- PD-L1 bispecific antibody, wherein the bispecific antibody further comprises an immune cell- targeting antibody.

62. A method of treating or preventing a chronic viral infection in a subject in need thereof, the method comprising administering the antibody, or antigen-binding fragment thereof, of any one of claims 1-52 or the composition of claim 58 to the subject.