WO2023076876A1

WO2023076876A1 - Modulation of immune responses to viral vectors

Info

Publication number: WO2023076876A1
Application number: PCT/US2022/078624
Authority: WO
Inventors: Courtney Crane; Kristine SWIDEREK
Original assignee: Mozart Therapeutics, Inc.
Priority date: 2021-10-26
Filing date: 2022-10-25
Publication date: 2023-05-04

Abstract

The present invention provides binding agents that specifically bind to CD8+KIR+ T regulatory cells and their use in the suppression, reduction, or prevention of an immune response to a virus, such as an immune response induced by administration of a viral vector.

Description

MODULATION OF IMMUNE RESPONSES TO VIRAL VECTORS

REFERENCE TO AN ELECTRONIC SEQUENCE LISTING

The content of the electronic sequence listing (670151_407WO_SEQUENCE_LISTING.xml; Size: 253,985 bytes; and Date of Creation: October 17, 2022) is herein incorporated by reference in its entirety.

BACKGROUND

The immune system includes the innate immune and the adaptive immune system. The adaptive immune system has a number of cell subtypes, including T cells subsets and B cell subsets. T cell subsets include a variety of types of T cells, including naive T lymphocytes and effector T lymphocytes, such as cytotoxic T cells and helper T cells, and regulatory T cells (also referred to as "Tregs"). The activity of the different types of T cells is achieved by a balance between the activity of effector T cells and regulation by Tregs. While effector T cells promote inflammation, Tregs are generally thought to control it. Therefore, Tregs play an important role in autoimmune pathogenesis by maintaining self-tolerance, limiting autoimmunity, and controlling expansion and activation of autoreactive CD4+ T effector cells. Disruption of the balance between effector and regulatory T cells can lead to an inappropriate activation or suppression of an immune response, the loss of selftolerance, autoimmune disorders, and cancer. The mechanisms and the regulation of regulatory T cells to maintain balance of the immune system is only beginning to be understood.

The use of viral vectors, such as adeno-associated virus (AAV) vectors, to deliver genes of interest is currently an important tool for therapeutic approaches involving gene replacement, gene silencing, gene addition, and gene editing. However, host immune responses can limit the effectiveness of these approaches (Wang et al., Adeno-associated virus vector as a platform for gene therapy delivery, Nat Rev Drug Discov 18, 358-378 (2019), https://doi.org/10.1038/s41573-019-0012- 9). For example, the host may produce neutralizing antibodies against the vector capsids based on exposure to the wild-type virus, blocking gene delivery. The host may also produce neutralizing antibodies against the vector capsid that limit the effectiveness of re-administration of the vector in therapies requiring repeated dosing. Hosts can also mount a cytotoxic T lymphocyte (CTL)-mediated cytotoxicity that clears transduced cells. In a subset of 'reactive patients', AAV mediated gene delivery can be associated with inflammatory side effects and toxicities mediated by pathogenic CD4+ T cells. Approaches for preventing the induction of undesired immune responses associated with vector-mediated delivery of genetic material are needed.

BRIEF SUMMARY

The present disclosure provides methods of modulating an immune response to a virus. In some embodiments, the disclosure provides methods of suppressing, reducing, or preventing an immune response induced by administration of a viral vector (e.g., an immune response to a viral vector capsid, a transduced cell, and/or a transgenic protein), by administering binding agents that modulate the activity of CD8+KIR+ regulatory T cells (Tregs). The binding agents are bispecific or multispecific and specifically bind to antigens expressed on the surface of the CD8+KIR+ Tregs. In some embodiments, the CD8+KIR+ Tregs are MHC class I restricted. In some embodiments, the CD8+KIR+ Tregs are not MHC Qa-1 restricted.

In some embodiments, a binding agent is provided that comprises a first binding domain that specifically binds to a first antigen, the first antigen selected from antigens expressed on CD8+KIR+ T regulatory cells (Tregs) other than a KIR protein; and a second binding domain that specifically binds to an inhibitory KIR protein expressed on the surface of the CD8+KIR+ Tregs, wherein the binding agent binds to CD8+KIR+ Tregs.

In some embodiments, the first antigen is selected from the group consisting of CD3, CD8, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD103 (ITGAE), CD122, CD166, CD177, CCR7, CXCR3, CXCR5, HLA-DR, ICOS, LAG-3/CD223, OX-40, PD-1 , S1000A8/9, TIM-3, TLT-2, 2B4, and 41 BB. In some embodiments, the first antigen is selected from the group consisting of CD3, CD5, CD8, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD103 (ITGAE), CD122, CD166, CD177, CCR7, CXCR3, CXCR5, HLA-DR, ICOS, LAG- 3/CD223, OX-40, PD-1 , S1000A8/9, TIM-3, TLT-2, 2B4, and 41 BB. In some embodiments, the first antigen is selected from CD3, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD122, ICOS, OX-40, 2B4, 41 BB, and HLA- DR. In some embodiments, the first antigen is selected from CD3, CD5, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD122, ICOS, OX-40, 2B4, 41 BB, and HLA-DR. In some embodiments, the first antigen is selected from LAG-3/CD223, TIM-3, PD-1 , S1000A8/9, and TLT2. In some embodiments, the first antigen is selected from CD103 (ITGAE), CD166, CD177, CXCR3, and S1000A8/9. In some embodiments, the first antigen is selected from CCR7, CXCR3, and CXCR5. In some embodiments, the first antigen is selected from PD-1 , CXCR3, and ICOS. In some embodiments, the first antigen is selected from CD3, CD5, and CD8. In some embodiments, the first antigen is selected from CD3 and CD8.

In some embodiments, the binding agent is a bispecific antibody, a diabody, an antibody Fc fusion, an scFv1-ScFv2, an SCFV12-FC-SCFV22, an IgG-scFv, a DVD- Ig, a triomab/quadroma, a two-in-one IgG, a scFv2-Fc, a TandAb, an scFv-HSA- scFv, an scFv-VHH, a Fab-scFv-Fc, a Fab-VHH-Fc, a dAb-IgG, an IgG-VHH, a Tandem scFv-Fc, a (scFv1)2-Fc-(VHH)2, a BiTe, a DART, a crossmab, an anticalin, an affibody, an avimer, a DARPin, an adnectin, a scFv-Fc, a one-armed tandem scFv-Fc, or a DART-Fc. In some embodiments, either the first or second binding domain of the binding agent is selected from an antibody or antigen binding portion thereof, and the other binding domain is an antibody fragment. In some embodiments, the antigen binding portion is a Fab, Fab', F(ab')2, Fv, scFv, or a single domain antibody (also referred to as a VHH, VNAR, sdAb, or nanobody). In some embodiments, the first binding domain comprises a heavy chain variable region and a light chain variable region. In some embodiments, the second binding domain comprises a heavy chain variable region and a light chain variable region.

In some embodiments, the first binding domain specifically binds to CD3 or a subunit of CD3, optionally CD3epsilon. In some embodiments, the first binding domain comprises a heavy chain variable region (VH) and a light chain variable region(VL), the VH and VL having amino acid sequences selected from the pairs of amino acids sequences set forth in the group consisting of: a. SEQ ID NO:1 and SEQ ID NO:2, respectively; b. SEQ ID NO:9 and SEQ ID NO: 10, respectively; c. SEQ ID NO: 17 and SEQ ID NO: 18, respectively; d. SEQ ID NO:25 and SEQ ID NO:26, respectively; e. SEQ ID NO:33 and SEQ ID NO:34, respectively; f. SEQ ID NO:41 and SEQ ID NO:34, respectively; j. SEQ ID NO:45 and SEQ ID NO:34, respectively; k. SEQ ID NO:49 and SEQ ID NQ:50, respectively; l. SEQ ID NO:57 and SEQ ID NO:58, respectively; m. SEQ ID NO:65 and SEQ ID NO:66, respectively; and n. SEQ ID NO:65 and SEQ ID NO: 166, respectively.

In some embodiments, the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3, and ICDR1 , ICDR2, and ICDR3, respectively, the CDRs having amino acid sequences selected from the sets of amino acid sequences set forth in the group consisting of: a. SEQ ID NO:3 to SEQ ID NO:8, respectively; b. SEQ ID NO: 11 to SEQ ID NO: 16, respectively; c. SEQ ID NO: 19 to SEQ ID NO:24, respectively; d. SEQ ID NO:27 to SEQ ID NO:32, respectively; e. SEQ ID NO:35 to SEQ ID NQ:40, respectively; f. SEQ ID NO:42 to SEQ ID NO:44 and SEQ ID NO:38 to SEQ ID NQ:40, respectively; g. SEQ ID NO:46 to SEQ ID NO:48 and SEQ ID NO:38 to SEQ ID NQ:40, respectively; h. SEQ ID NO:51 to SEQ ID NO:56, respectively; i. SEQ ID NO:59 to SEQ ID NO:64, respectively; j. SEQ ID NO:67 to SEQ ID NO:72, respectively; and k. SEQ ID NOs: 67-69 and 167-169, respectively.

In some embodiments, the first binding domain specifically binds to CD8 or a subunit of CD8, optionally CD8alpha. In some embodiments, the first binding domain comprises a heavy chain variable region (VH) and a light chain variable region (VL), the VH and VL regions having the amino acid sequences selected from the pairs of amino acid sequences set forth in group consisting of: a. SEQ ID NO:73 and SEQ ID NO:74, respectively; and b. SEQ ID N0:81 and SEQ ID NO:82, respectively; or the first binding domain comprises a VHH chain, the VHH chain having the amino acid sequence selected from the amino acid sequences set forth in the group consisting of the following: c. SEQ ID NO:89; d. SEQ ID NO:93; and e. SEQ ID NO:97.

In some embodiments, the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3, and ICDR1 , ICDR2, and ICDR3, respectively, the amino acid sequences of the CDRs selected from the amino acid sequences set forth in the group consisting of the following: a. SEQ ID NO:75 to SEQ ID NQ:80, respectively; or b. SEQ ID NO:83 to SEQ ID NO:88, respectively; or the first binding domain includes a VHH chain having hCDR1 , hCDR2, and hCDR3, the amino acid sequences of the VHH CDRs selected from the amino acid sequences set forth in the group consisting of the following: c. SEQ ID NQ:90 to SEQ ID NO:92, respectively; d. SEQ ID NO:94 to SEQ ID NO:96, respectively; and e. SEQ ID NO:98 to SEQ ID NO: 100, respectively.

In some embodiments, the first binding domain specifically binds to ICOS or a subunit of ICOS. In some embodiments, the first binding domain comprises a heavy chain variable region (VH) and a light chain variable region (VL), the VH and VL having amino acid sequences of SEQ ID NO: 170 and SEQ ID NO: 171 , respectively.

In some embodiments, the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3 having amino acid sequences of SEQ ID NOs: 172-174, respectively, and ICDR1 , ICDR2, and ICDR3 having amino acid sequences of SEQ ID NOs: 175-177, respectively.

In some embodiments, the first binding domain specifically binds to PD-1 or a subunit of PD-1 . In some embodiments, the first binding domain comprises a heavy chain variable region (VH) and a light chain variable region (VL), the VH and VL having amino acid sequences of SEQ ID NO: 178 and SEQ ID NO: 179, respectively.

In some embodiments, the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3 having amino acid sequences of SEQ ID NOs:180-182, respectively, and ICDR1 , ICDR2, and ICDR3 having amino acid sequences of SEQ ID NOs: 183-185, respectively.

In some embodiments, the first binding domain specifically binds to CXCR3 or a subunit of CXCR3. In some embodiments, the first binding domain comprises a heavy chain variable region (VH) and a light chain variable region (VL), the VH and VL having amino acid sequences of SEQ ID NO: 186 and SEQ ID NO: 187, respectively.

In some embodiments, the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3 having amino acid sequences of SEQ ID NOs: 188-190, respectively, and ICDR1 , ICDR2, and ICDR3 having amino acid sequences of SEQ ID NOs: 191 -193, respectively.

In some embodiments, the first binding domain specifically binds to CD5 or a subunit of CD5. In some embodiments, the first binding domain comprises a heavy chain variable region (VH) and a light chain variable region (VL), the VH and VL having amino acid sequences of SEQ ID NO: 194 and SEQ ID NO: 195, respectively.

In some embodiments, the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3 having amino acid sequences of SEQ ID NOs: 196-198, respectively, and ICDR1 , ICDR2, and ICDR3 having amino acid sequences of SEQ ID NOs: 199-201 , respectively.

In some embodiments, the second binding domain specifically binds to an inhibitory KIR protein selected from KIR3DL1 , KIR3DL2, KIR2DL1 , KIR2DL2, and KIR2DL3 or a combination thereof. In some embodiments, the second binding domain specifically binds to KIR2DL1/2/3 or KIR2DL1/2. In some embodiments, the second binding domain comprises a heavy chain variable region (VH) and a light chain variable region (VL), the VH and VL having amino acid sequences selected from the pairs of amino acid sequences set forth in the group consisting of: a. SEQ ID NO: 101 and SEQ ID NO: 102, respectively; b. SEQ ID NO: 109 and SEQ ID NO: 110, respectively; c. SEQ ID NO:117 and SEQ ID NO: 118, respectively; d. SEQ ID NO:125 and SEQ ID NO:126, respectively; e. SEQ ID NO: 133 and SEQ ID NO: 134, respectively; f. SEQ ID NO:141 and SEQ ID NO:142, respectively; g. SEQ ID NO: 149 and SEQ ID NO: 150, respectively; and h. SEQ ID NO: 157 and SEQ ID NO: 158, respectively.

In some embodiments, the second binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3, and ICDR1 , ICDR2, and ICDR3, respectively, the CDRs having amino acid sequences selected from the sets of amino acid sequences set forth in from the group consisting of: a. SEQ ID NO: 103 to SEQ ID NO: 108, respectively; b. SEQ ID NO:111 to SEQ ID NO:116, respectively; c. SEQ ID NO:119 to SEQ ID NO: 124, respectively; d. SEQ ID NO: 127 to SEQ ID NO: 132, respectively; f. SEQ ID NO: 135 to SEQ ID NO: 140, respectively; g. SEQ ID NO: 143 to SEQ ID NO: 148, respectively; h. SEQ ID NO: 151 to SEQ ID NO: 156, respectively; and i. SEQ ID NO: 159 and SEQ ID NO: 164, respectively.

In some embodiments, the binding agent does not contain an Fc domain. In some embodiments, the binding agent includes an Fc domain. In some embodiments, the Fc domain is selected from an lgG1 and an lgG4 Fc domain. In some embodiments, the binding agent has substantially no effector function activity. In some embodiments, the Fc domain is an IgG 1 Fc domain. In some embodiments, the Fc domain is an lgG1 Fc null.

In some embodiments, the binding agent is bivalent, trivalent, or tetravalent. In some embodiments, the binding agent is bivalent or tetravalent. In some embodiments, the binding agent is bispecific. Also provided are methods of suppressing or reducing an immune response induced by administration of a viral vector (e.g., an immune response to a viral vector capsid, a transduced cell, and/or a transgenic protein), by administering a pharmaceutical composition comprising the binding agent of any of the embodiments described herein and a pharmaceutically acceptable carrier.

Also provided are methods comprising administering nucleic acids encoding the binding agent of any of the embodiments described herein. Further provided are methods comprising administering a vector comprising any of the embodiments of nucleic acids described herein. Further also provided are cell lines comprising any of the embodiments of nucleic acids or vectors described herein.

In some embodiments, provided is a method of suppressing or reducing an immune response induced by administration of a viral vector, comprising contacting CD8+KIR+ T regulatory cells (Tregs) with any of the embodiments of binding agents or pharmaceutical compositions described herein in an amount effective to activate or stimulate the CD8+KIR+ Tregs (activated Tregs), whereby the immune response induced by administration of the viral vector is reduced. In some embodiments, the immune response targets a viral vector capsid or a viral vector-transduced cell.

In some embodiments of the methods of suppressing or reducing an immune response, the binding agent specifically binds to CD8 and an inhibitory KIR protein or proteins on CD8+KIR+ Tregs. In some embodiments, the binding agent specifically binds to CD3 and an inhibitory KIR protein on CD8+KIR+ Tregs. In some embodiments, the binding agent specifically binds to CD5 and an inhibitory KIR protein on CD8+KIR+ Tregs. In some embodiments, the binding agent specifically binds to PD-1 and an inhibitory KIR protein on CD8+KIR+ Tregs. In some embodiments, the binding agent specifically binds to ICOS and an inhibitory KIR protein on CD8+KIR+ Tregs. In some embodiments, the binding agent specifically binds to CXCR3 and an inhibitory KIR protein on CD8+KIR+ Tregs. In some embodiments, the CD8+KIR+ Tregs are MHC class I restricted. In some embodiments, the CD8+KIR+ Tregs are not MHC HLA E (Qa-1 b) restricted.

In some embodiments of the methods of suppressing an immune response, the methods further include administering an immunosuppressive agent to the subject. In some embodiments, the administration of the binding agent to the subject results in an improved treatment outcome in the subject.

In some embodiments of the methods of suppressing an immune response, the binding agent is administered intravenously. In some embodiments, the binding agent is administered subcutaneously. In some embodiments, the binding agent is administered in a dose of about 0.01 mg/kg to about 20 mg/kg. In some embodiments, the binding agent has substantially no effector function activity.

In some embodiments, provided is the use of any of the embodiments of the binding agents or the pharmaceutical compositions described herein for the suppression or reduction of an immune response induced by administration of a viral vector in a subject by activating or stimulating CD8+KIR+ Tregs. In some embodiments, provided is the use of any of the embodiments of the binding agents or the pharmaceutical compositions described herein for the reduction of an immune response by undesired immune cells by activating or stimulating CD8+KIR+ Tregs. In some embodiments, provided is the use of any of the embodiments of the binding agents or the pharmaceutical compositions described herein for the reduction of autoantibody titer in a subject by activating or stimulating CD8+KIR+ Tregs.

These and other aspects of the present invention may be more fully understood by reference to the following detailed description, non-limiting examples of specific embodiments, and the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows various formats of IgG-scFv bispecific antibodies.

Figure 2 shows various formats of certain bispecific antibodies.

Figure 3 shows various formats of additional bispecific antibodies.

Figures 4A to 4D show the effects of Ly49 blockade on CD8+Ly49+ T regulatory cells and MOG responsive CD4+ T cells.

Figures 5A to 5C show characteristics of T cells prevalent in Celiac patients. Celiac patients have an increased prevalence of CD8+KIR+ T cells (Figure 5A); have increase in percentage of CD8+ T cells with intracellular IFNgamma and perforin (Figure 5B); and have an increase in percentage of CD8+ T cells with intracellular Granzyme B (Figure 5C). Figures 6A to 6B show that Celiac patients have more CD8+KIR+ T cells (Figure 6A) and CD8+KIR+ICOS+ T cells (Figure 6B) compared to healthy controls.

Figures 7A to 7B show show that gluten peptide restimulation of CD8+KIR+ T cells from Celiac patients increases degranulation (Figure 7A, left) and Granzyme B levels (Figure 7A, right), compared to unstimulated cells or those stimulated with control flu peptides. Gluten peptide restimulation also leads to a reduction in reactive CD4+ T cells, as compared to unstimulated cells or those restimulated with control flu peptides (Figure 7B).

Figures 8A to 8B show that KIR blockade ("KIR block") of CD8+ Tregs results in increased intracellular Granzyme B levels (Figure 8A) and increased degranulation (CD107) (Figure 8B).

Figure 9 shows that KIR blockade ("KIR block") of CD8+CD16+ T cells reduced CD4+ T cell activation and proliferation (CD69) in samples from three Celiac patients.

Figures 10A to 10C show that IFN-y production by AAV-reactive CD4+ T cells is reduced in the presence of a CD8+ Treg activating bispecific molecule. Figures 10A, 10B, and 10C show the IFN-y response to AAV5, AAV6, and AAV8 class II peptide pools when incubated with the KIRxCD8 bispecific CD8+ Treg modulator on day 2 post activation or day 5 post activation.

Figure 11 shows the percent decrease in IFN-y response when incubated with the KIRxCD8 bispecific CD8+ Treg modulator.

DETAILED DESCRIPTION

Definitions

For convenience, certain terms in the specification, examples and claims are defined here. Unless stated otherwise, or implicit from context, the following terms and phrases have the meanings provided below. The definitions are provided to aid in describing particular embodiments, and are not intended to limit the claimed invention, because the scope of the invention is limited only by the claims. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. As used herein and unless otherwise indicated, the terms "a" and "an" are taken to mean "one", "at least one", or "one or more". Unless otherwise required by context, singular terms used herein shall include pluralities and plural terms shall include the singular.

Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to".

As used herein, the term "consisting essentially of" refers to those elements required for a given embodiment. The term permits the presence of elements that do not materially affect the basic and novel or functional characteristic(s) of that embodiment.

The term "consisting of" refers to compositions, methods, and respective components thereof as described herein, which are exclusive of any element not recited in that description of the embodiment.

Other than in the examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein should be understood as modified in all instances by the term "about". The term "about" when used in connection with percentages can mean +/-1 %.

The term "statistically significant" or "significantly" refers to statistical significance and generally means a two standard deviation (2SD) difference, above or below a reference value.

The terms "decrease", "reduce", "reduced", "reduction", "decrease", and "inhibit" are all used herein generally to mean a decrease by a statistically significant amount relative to a reference.

The terms "increased", "increase", "enhance", or "activate" are all used herein to generally mean an increase by a statically significant amount relative to a reference.

The terms "isolated" or "partially purified" as used herein refer in the case of a nucleic acid, polypeptide, or protein, to a nucleic acid, polypeptide, or protein separated from at least one other component (e.g., nucleic acid or polypeptide or protein) that is present with the nucleic acid, polypeptide, or protein as found in its natural source and/or that would be present with the nucleic acid, polypeptide, or protein when expressed by a cell, or secreted in the case of secreted polypeptides and proteins. A chemically synthesized nucleic acid, polypeptide, or protein, or one synthesized using in vitro transcription/translation, is considered "isolated". The terms "purified" or "substantially purified" refer to an isolated nucleic acid, polypeptide, or protein that is at least 95% by weight the subject nucleic acid, polypeptide, or protein, including, for example, at least 96%, at least 97%, at least 98%, at least 99%, or more.

As used herein, the terms "protein" and "polypeptide" are used interchangeably herein to designate a series of amino acid residues each connected to each other by peptide bonds between the alpha-amino and carboxyl groups of adjacent residues. The terms "protein" and "polypeptide" also refer to a polymer of protein amino acids, including modified amino acids (e.g., phosphorylated, glycated, glycosylated, etc.) and amino acid analogs, regardless of its size or function. "Protein" and "polypeptide" are often used in reference to relatively large polypeptides, whereas the term "peptide" is often used in reference to small polypeptides, but usage of these terms in the art overlaps. The terms "protein" and "polypeptide" are used interchangeably herein when referring to an encoded gene product and fragments thereof. Thus, exemplary polypeptides or proteins include gene products, naturally occurring proteins, homologs, orthologs, paralogs, fragments, and other equivalents, variants, fragments, and analogs of the foregoing.

A "vector" is a nucleic acid molecule that is capable of transporting another nucleic acid. Vectors may be, for example, plasmids, cosmids, viruses, a RNA vector, or a linear or circular DNA or RNA molecule that may include chromosomal, non-chromosomal, semi-synthetic, or synthetic nucleic acids. Exemplary vectors are those capable of autonomous replication (episomal vector) or expression of nucleic acids to which they are linked (expression vectors).

Exemplary viral vectors include retrovirus, adenovirus, parvovirus (e.g., adeno-associated viruses), coronavirus, negative strand RNA viruses such as orthomyxovirus (e.g., influenza virus), rhabdovirus (e.g., rabies and vesicular stomatitis virus), paramyxovirus (e.g., measles and Sendai), positive strand RNA viruses such as picornavirus and alphavirus, and double-stranded DNA viruses including adenovirus, herpesvirus (e.g., Herpes Simplex virus types 1 and 2, Epstein-Barr virus, cytomegalovirus), and poxvirus (e.g., vaccinia, fowlpox, and canarypox). Other viruses include Norwalk virus, togavirus, flavivirus, reoviruses, papovavirus, hepadnavirus, and hepatitis virus, for example. Examples of retroviruses include avian leukosis-sarcoma, mammalian C-type, B-type viruses, D type viruses, HTLV- BLV group, lentivirus, spumavirus (Coffin, J. M., Retroviridae: The viruses and their replication, In Fundamental Virology, Third Edition, B. N. Fields et al., Eds., Lippincott-Raven Publishers, Philadelphia, 1996). Viral vectors may be used to deliver genes, RNA interference molecules (such as shRNAs), or other genetic material.

"Adeno-associated virus (AAV) vector", as used herein, refers to AAV-based vectors for delivery of exogenous genetic material. AAV is a single-stranded, nonenveloped DNA virus having a genome that encodes proteins for replication (rep) and the capsid (cap), flanked by two inverted terminal repeat (ITR) sequences, which serve as the origin of replication of the viral genome. AAV also contains a packaging sequence, allowing packaging of the viral genome into an AAV capsid. The nucleic acid sequence of the AAV vector may be single-stranded ("single-stranded AAV" or "ssAAV") or self-complementary ("self-complementary AAV" or "scAAV"). AAV vectors may be recombinant AAV vectors ("rAAV vectors"), produced by recombinant methods. AAV vectors may be based on any AAV serotype. In some embodiments, the AAV vector is a mammalian serotype AAV vector and/or the rAAV vector includes an AAV genome and ITRs derived from a mammalian serotype AAV. In some embodiments, the rAAV vector is based on a mammalian AAV isolated from humans or non-human primates. rAAV vectors may comprise a wild-type or engineered capsid sequence but encapsidate a genome having a therapeutic gene expression cassette flanked by ITRs with only some or no AAV protein-coding sequences remaining. rAAV vectors may have one or more AAV wild type genes deleted in whole or in part. In some embodiments, the rAAV vector is replication defective. In some embodiments, the rAAV vector lacks a functional rep protein and/or capsid protein. In some embodiments, rAAV vectors may be vectors comprising an AAV genome and AAV capsid derived from the same AAV serotype. In some embodiments, rAAV vectors are pseudotyped, meaning the rAAV vectors comprise an AAV genome derived from one AAV serotype and an AAV capsid derived at least in part from a different AAV serotype.

In some embodiments, the AAV vector capsid is from AAV1 , AAV2, AAV3, AAV4, AAV5, AAV6, AAV7, AAV8, AAV9, AAVrh.8, AAVrh.10, AAVrh.43, AAVrh.74, or AAVhu.37, or a variant thereof. In some embodiments, a particular capsid sequence is selected to allow for tissue-specific delivery.

In some embodiments, the ITRs are selected from any one of serotypes AAV1 , AAV2, AAV3, AAV4, AAV5, AAV6, AAV7, AAV8, AAV9, AAV.RhW, AAV11 , and variants thereof. In some embodiments, one or both of the AAV ITRs is modified, e.g., by insertion, deletion, or substitution, provided that the ITRs provide for functional rescue, replication, and packaging.

Methods of packaging recombinant AAV vector into AAV capsids using host cell culture are known in the art. In some embodiments, one or more of the required components for packaging the rAAV vector (e.g., rep sequence, cap sequence, and/or accessory functions) may be provided by a stable host cell that has been engineered to contain the one or more required components (e.g., by a vector). Expression of the required components for AAV packaging may be under control of an inducible or constitutive promoter in the host packaging cell. AAV helper vectors are commonly used to provide transient expression of AAV rep and/or cap genes, which function in trans, to complement missing AAV functions that are necessary for AAV replication. In some embodiments, AAV helper vectors lack AAV ITRs and can neither replicate nor package themselves. AAV helper vectors can be in the form of a plasmid, phage, transposon, cosmid, virus, or virion.

Recombinant AAV vectors of the present disclosure may be encapsidated by an AAV capsid to form a rAAV particle. A "rAAV particle" or "rAAV virion" refers to an infectious, replication-defective virus including an AAV protein shell, encapsidating a transgene of interest which is flanked on both sides by AAV ITRs. A rAAV particle is produced in a suitable host cell that has sequences specifying a rAAV vector, AAV helper functions, and accessory functions introduced therein to render the host cell capable of encoding AAV polypeptides that are required for packaging the rAAV vector (containing the transgene sequence of interest) into infectious rAAV particles for subsequent gene delivery to a target cell.

In some embodiments, rAAV particles may be produced using the triple transfection method (see, e.g., U.S. Patent No. 6,001 ,650, incorporated herein by reference for its teachings relevant to this method). In this approach, the rAAV particles are produced by transfecting a host cell with a rAAV vector (comprising a transgene) to be packaged into rAAV particles, an AAV helper vector, and an accessory function vector. In some embodiments, the AAV helper function vector supports efficient AAV vector production without generating any detectable wild-type AAV virions (e.g., AAV virions containing functional rep and cap genes). The accessory function vector encodes nucleotide sequences for non-AAV derived viral and/or cellular functions upon which AAV is dependent for replication (e.g., "accessory functions"). The accessory functions include those functions required for AAV replication, including, without limitation, those moieties involved in activation of AAV gene transcription, stage specific AAV mRNA splicing, AAV DNA replication, synthesis of cap expression products, and AAV capsid assembly. Viral-based accessory functions can be derived from any of the known helper viruses such as adenovirus, herpesvirus (other than herpes simplex virus type-1), and vaccinia virus. In some embodiments, a double transfection method, wherein the AAV helper function and accessory function are cloned on a single vector, is used to generate rAAV particles.

"Lentiviral vector", as used herein, means HIV-based lentiviral vectors for gene delivery, which can be integrative or non-integrative, have relatively large packaging capacity, and can transduce a range of different cell types. Lentiviral vectors are usually generated following transient transfection of three (packaging, envelope, and transfer) or more plasmids into producer cells. Like HIV, lentiviral vectors enter the target cell through the interaction of viral surface glycoproteins with receptors on the cell surface. On entry, the viral RNA undergoes reverse transcription, which is mediated by the viral reverse transcriptase complex. The product of reverse transcription is a double-stranded linear viral DNA, which is the substrate for viral integration into the DNA of infected cells. "Expression cassette", as used herein, refers to a DNA construct containing a nucleic acid molecule that is operably-linked to a suitable control sequence capable of effecting the expression of the nucleic acid molecule in a suitable host. Such control sequences may include one or more of transcription initiation sequences, termination sequences, promoter sequences, enhancer sequences, repressor sequences, splice site sequences, polyadenylation (polyA) signal sequences, or any combination thereof.

As used herein, the term "transgene" refers to an exogenous nucleic acid that has been transferred naturally or by genetic engineering means into another cell and is capable of being transcribed, and optionally translated.

CD3epsilon is a protein that is expressed on T cells, including regulatory T cells. CD3epsilon polypeptides include, but are not limited to, those having the amino acid sequence set forth in NP000724.1 ; this sequence is incorporated by reference herein.

CD5 is a protein expressed on T cells and B cells. CD5 polypeptides include, but are not limited to, those having the amino acid sequence set forth in NP_055022.2 and NP_001333385.1 ; these sequences are incorporated by reference herein.

CD8alpha is a protein that is expressed on T cells, including regulatory T cells. CD8alpha polypeptides include, but are not limited to, those having the amino acid sequences set forth in NP_001759.3, NP001139345.1 , NP_741969.1 , NP_001369627.1 , NP_757362.1 , NP_001171571.1 , NP_742100.1 , NP_742099.1 , and NP_004922; these sequences are incorporated by reference herein.

KIR3DL1 is a protein expressed on NK cells and on some T cells. It is also known as CD158E1 , KIR, KIR2DL5B, KIR3DL1/S1 , NKAT-3, NKAT3, NKB1 , and NKB1 B. KIR3DL1 polypeptides include, but are not limited to, those having the amino acid sequences set forth in NP_037421.2 and NP_001309097.1 ; these sequences are incorporated by reference herein.

KIR3DL2 is a protein expressed on NK cells and on some T cells. It is also known as 3DL2, CD158K, KIR-3DL2, NKAT-4, NKAT4, NKAT4B, and p140. KIR3DL2 polypeptides include, but are not limited to, those having the amino acid sequences set forth in NP_006728.2 and NP_001229796.1 ; these sequences are incorporated by reference herein.

KIR2DL1 is a protein expressed on NK cells and on some T cells. It is also known as CD158A, KIR-K64, KIR221 , KIR2DL3, NKAT, NKAT-1 , NKAT1 , and p58.1. KIR2DL1 polypeptides include, but are not limited to, those having the amino acid sequence set forth in NP_055033.2; this sequence is incorporated by reference herein.

KIR2DL2 is a protein expressed on NK cells and on some T cells. It is also known as CD158B1 , CD158b, NKAT-6, NKAT6, and p58.2. KIR2DL2 polypeptides include, but are not limited to, those having the amino acid sequence set forth in NP_055034.2; this sequence is incorporated by reference herein.

KIR2DL3 is a protein expressed on NK cells and on some T cells. It is also known as CD158B2, CD158b, GL183, KIR-023GB, KIR-K7b, KIR-K7c, KIR2DL, KIR2DS5, KIRCL23, NKAT, NKAT2, NKAT2A, NKAT2B, and p58. KIR2DL3 polypeptides include, but are not limited to, those having the amino acid sequence set forth in NP_056952.2; this sequence is incorporated by reference herein.

CD27 is also referred to as TNF receptor superfamily member 7, S152, LPFS2, T14, TNFRSF7, and Tp55. CD27 polypeptides include, but are not limited to, those having the amino acid sequence set forth in NP_001233.2; this sequence is incorporated by reference herein.

CD38 is also referred to as ADP-ribosyl cyclase/cyclic ADP-ribose hydrolase 1 , ADPRC1 , and ADPRC 1 . CD38 polypeptides include, but are not limited to, those having the amino acid sequence set forth in NP_001766.2; this amino acid sequence is incorporated by reference herein.

CD39 is also known as ectonucleoside triphosphate diphosphohydrolase 1 , SPG64 ATPDase, and NTPDase-1. It encodes plasma membrane protein that hydrolyzes extracellular ATP and ADP to AMP. CD39 polypeptides include, but are not limited to, those having the amino acid sequences disclosed in NP_001307845.1 , NP_001157651 .1 , NP_001157650.1 , NP_001091645.1 , NP_001767.3, NP_001299583.1 , NP_001157655.1 , NP_001157654.1 , and NP_001157653.1 ; these amino acid sequences are incorporated by reference herein. CD40L, or CD40 ligand, is also referred to as CD154, HIGM1 , IGM, IMD3, T- BAM, TNFSF5, TRAP, gp39, and hCD40L. It is expressed on the surface of T cells. CD40L polypeptides include, but are not limited to, those having the amino acid sequence set forth in NP_000065.1 ; this sequence is incorporated by reference herein.

CD45 is referred to as protein tyrosine phosphatase receptor type C, B220, CD45R, GP180, L-CA, LCA, LY5, and T200. It has many isoforms, including CD45RA, CD45Rb, and CD45RO. CD45 RA and CD45Rb are expressed on naive T cells. CD45RO is expressed on memory T cells. CD45R0 polypeptides include, but are not limited to, those having the amino acid sequence disclosed in P08575-4. CD45RA polypeptides include, but are not limited to, those having the amino acid sequence disclosed in P08575-8. CD45RB polypeptides include, but are not limited to, those having the amino acid sequence disclosed in P08575-9. See UniProtKB database. These sequences are incorporated by reference herein.

CD73 is also referred to 5' nucleotidase ecto, CALJA, CD73, E5NT, NT, NT5, NTE, eN, and eNT. CD73 polypeptides include, but are not limited to, those disclosed in NP_001191742.1 and NP_002517.1 ; these amino acid sequences are incorporated by reference herein.

CD103, or integrin subunit alpha E (ITGAE), is also referred to as HUMINAE. CD103 polypeptides include, but are not limited to, those having the amino acid sequence disclosed in NP_002199.3; this amino acid sequence is incorporated by reference herein.

CD122, or interleukin 2 receptor subunit beta, is also referred to as IL15RB, IMD63, and P70-75. CD122 polypeptides include, but are not limited to, those having the amino acid sequences disclosed in NP_001333152.1 , NP_001333151.1 , and NP_000869.1 ; these amino acid sequences are incorporated by reference herein.

CD166, or activated leukocyte cell adhesion molecule (ALCAM), is also referred to as MEMD. CD166 polypeptides include, but are not limited to, those having the amino acid sequences set forth in NP_001618.2, NP_001230209.1 , NP_001230210.1 , and NP_001230212.1 ; these amino acid sequences are incorporated by reference herein. CD177 is also referred to as HNA-2a, HNA2A, NB1 , NB1 GP, PRV-1 , and PRV1. CD177 polypeptides include, but are not limited to, those having the amino acid sequence set forth in NP_065139.2; this amino acid sequence is incorporated by reference herein.

CCR7, or C-C motif chemokine receptor 7, is also referred to as BLR2, CC- CKR-7, CCR-7, CD197, CDw197, CMKBR7, and EBI1. CCR7 polypeptides includes, but are not limited to, those having the amino acid sequences set forth in NP_001829.1 , NP_001288643.1 , NP_001288645.1 , NP_001288646.1 and NP_001288647.1 ; these amino acid sequences are incorporated by reference herein.

C.XCR3, or C-X-C motif chemokine receptor 3, is also referred to as GPR9, MigR, CD182, CD183, Mig-R, CKR-L2, CMKAR3, and IP10-R. CXCR3 polypeptides include, but are not limited to, those having the amino acid sequences set forth in NP_001495.1 and NP_001136269.1 ; these amino acid sequences are incorporated by reference herein.

CXCR5, or C-X-C motif chemokine 5, is also referred to as BLR1 , CD185, and MDR15. CXCR5 polypeptides include, but are not limited to, those having the amino acid sequences set forth in NP_001707.1 and NP_116743.1 ; these amino acid sequences are incorporated by reference herein.

HLA-DR is a class II histocompatibility antigen composed of two chains. HLA-DR alpha chain polypeptides include, but are not limited to, those having the amino acid sequence set forth in NP_061984.2. HLA-DR beta chain polypeptides include, but are not limited to, those having the amino acid sequences set forth in NP_002116.2, NP_072049.2, NP_001346123.1 , and NP_001346122.1 . These amino acid sequences are incorporated by reference herein.

ICOS, or inducible T cell costimulatory, is also referred to as AILIM, CD278, and CVID1 . ICOS polypeptides include, but are not limited to, those having the amino acid sequence set forth in NP_036224.1 ; this amino acid sequence is incorporated by reference herein.

LAG-3, or CD223, is also referred to as lymphocyte activating 3. LAG-3 polypeptides include, but are not limited to, those having the amino acid sequence set forth in NP_002277.4; this amino acid sequence is incorporated by reference herein. OX-40 is also referred to as TNF receptor superfamily member 4 or TNFRSF4, ACT35, CD134, IMD16, and TXGP1 L. OX-40 polypeptides include, but are not limited to, those having the amino acid sequence set forth in NP_003318.1 ; this amino acid sequence is incorporated by reference herein.

PD-1 is also referred to as programmed cell death protein 1 . PD-1 polypeptides include, but are not limited to, those having the amino acid sequence set forth in NP_005009.2; this amino acid sequence is incorporated by reference herein.

S1000A8/9, or S100A8 and S100A9, respectively, are Ca²⁺ binding proteins belonging to the S100 family. S100A8 or S100-A8 is also referred to as 60B8AG, CAGA, CFAG, CGLA, CP-10, L1Ag, MA387, MIF, MRP8, NIF, and P8. S100A8 polypeptides include, but are not limited to, those having the amino acid sequences set forth in NP_001306125.1 , NP_001306126.1 , NP_001306127.1 , NP_001306130.1 , and NP_002955.2. S100A9, or S100-A9, is also referred to as 60B8AG, CAGB, CFAG, CGLB, L1AG, LIAG, MAC387, MIF, MRP14, NIF, and P14. S100A9 polypeptides include, but are not limited to, those having the amino acid sequence set forth in NP_002956.1 . These amino acid sequences are incorporated by reference herein.

TIM-3, also referred to as Hepatitis A virus cellular receptor 2 (HAVCR2), is also known as CD366, HAVcr-2, KIM-3, SPTCL, TIM3, TIMD-3, and TIMD3. TIM-3 polypeptides include, but are not limited to, those having the amino acid sequence set forth in NP_116171.3; this amino acid sequence is incorporated by reference herein.

TLT-2, or triggering receptor expressed on myeloid cells like 2 (TREML2), is also referred to as C6orf76 or dJ238O23.1 . TLT-2 polypeptides include, but are not limited to, those having the amino acid sequence set forth in NP_079083.2; this amino acid sequence is incorporated by reference herein.

2B4, or CD244, is also referred to as NAIL, NKR2B4, Nmrk, and SLAMF4. 2B4 polypeptides include, but are not limited to, those having the amino acid sequences set forth in NP_057466.1 , NP_001160135.1 , or NP_001160136.1 ; these amino acid sequences are incorporated by reference herein. 41 BB, or TNF receptor superfamily member 9 (TNFSF9), is also referred to as ILA, 4-1 BB, CD137, and CDw137. 41 BB polypeptides include, but are not limited to, those having the amino acid sequence set forth in NP_001552.2; this amino acid sequence is incorporated by reference herein.

As used herein, an "epitope" refers to the amino acids conventionally bound by an immunoglobulin VHA/L pair, such as the antibodies and other binding agents described herein. An epitope can be formed on a polypeptide from contiguous amino acids or noncontiguous amino acids juxtaposed by tertiary folding of a protein. Epitopes formed from contiguous amino acids are typically retained on exposure to denaturing solvents, whereas epitopes formed by tertiary folding are typically lost on treatment with denaturing solvents. An epitope typically includes at least 3, and more usually, at least 5, about 9, or about 8-10 amino acids in a unique spatial conformation. An epitope defines the minimum binding site for an antibody or other binding agent, and thus represent the target of specificity of an antibody, antigen binding portion thereof or other immunoglobulin-based binding agent. In the case of a single domain antibody, an epitope represents the unit of structure bound by a variable domain in isolation.

As used herein, "specifically binds" refers to the ability of a binding agent (e.g., an antibody or antigen binding portion thereof) described herein to bind to a target with a KD 10’⁵ M (10000 nM) or less, e.g., 1 Q-⁶ M, 1 Q-⁷ M, 1Q-⁸ M, 1 Q-⁹ M, 10’¹⁰ M, 10’¹¹ M, 10’¹² M, or less. Specific binding can be influenced by, for example, the affinity and avidity of the antibody or other binding agent and the concentration of target polypeptide. A person of ordinary skill in the art can determine appropriate conditions under which the antibodies and other binding agents described herein selectively bind to a target antigen using any suitable methods, such as titration of a binding agent in a suitable cell binding assay. A binding agent specifically bound to a target is not displaced by a non-similar competitor. In certain embodiments, a binding agent, such as an antibody or antigen-binding portion thereof is said to specifically bind to its target when it preferentially recognizes its target antigen in a complex mixture of proteins and/or macromolecules.

In some embodiments, a binding agent, such as an antibody or antigenbinding portion thereof or other binding agent as described herein specifically binds to a target polypeptide with a dissociation constant (KD) of 10’⁵ M (10000 nM) or less, e.g., 10’⁶ M, 10’⁷ M, 10’⁸ M, 10’⁹ M, 10’¹⁰ M, 10’¹¹ M, 10’¹² M, or less. In some embodiments, an antibody or antigen-binding portion thereof or other binding agent as described herein specifically binds to a target polypeptide with a dissociation constant (KD) of from about 10’⁵ M to 10’⁶ M. In some embodiments, an antibody or antigen-binding portion thereof or other binding agent as described herein specifically binds to a target polypeptide with a dissociation constant (KD) of from about 10’⁶ M to 10’⁷ M. In some embodiments, an antibody or antigen-binding portion thereof or other binding agent as described herein specifically binds to a target polypeptide with a dissociation constant (KD) of from about 10’⁷ M to 10’⁸ M. In some embodiments, an antibody or antigen-binding portion thereof or other binding agent as described herein specifically binds to a target polypeptide with a dissociation constant (KD) of from about 10’⁸ M to 10’⁹ M. In some embodiments, an antibody or antigen-binding portion thereof or other binding agent as described herein specifically binds to a target polypeptide with a dissociation constant (KD) of from about 10’⁹ M to 10’¹° M. In some embodiments, an antibody or antigen-binding portion thereof or other binding agent as described herein specifically binds to a target polypeptide with a dissociation constant (KD) of from about 10’¹° M to 10’¹¹ M. In some embodiments, an antibody or antigen-binding portion thereof or other binding agent as described herein specifically binds to a target polypeptide with a dissociation constant (KD) of from about 10’¹¹ M to 10’¹² M. In some embodiments, an antibody or antigen-binding portion thereof or other binding agent as described herein specifically binds to a target polypeptide with a dissociation constant (KD) of less than 10’¹² M.

Other terms are defined herein within the description of the various aspects of the invention.

Modulation of CD8+KIR+ Regulatory T cells

Provided herein are methods using binding agents comprising binding domains that specifically bind to antigens expressed on CD8+KIR+ regulatory T cells (Tregs). In some embodiments, the CD8+KIR+ Tregs are MHC class I restricted. In some embodiments, the CD8+KIR+ Tregs are not MHC Qa-1 (HLA-E) restricted. Also provided are methods of using the binding agents for modulating an immune response to a virus. In some embodiments, the method comprises using the binding agents for suppressing or reducing an immune response induced by administration of a viral vector. In some embodiments, the method comprises using the binding agents for preventing an immune response induced by administration of a viral vector.

As used herein, "modulating an immune response" may refer to increasing, decreasing, or preventing an immune response.

The binding agents include a first binding domain that specifically binds to a T cell antigen expressed on the CD8+KIR+ Tregs, other than a KIR protein, and a second binding domain that specifically binds to an inhibitory KIR protein expressed on the CD8+KIR+ Tregs. In some embodiments, the first binding domain specifically binds to an antigen selected from CD3, CD8, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD103 (ITGAE), CD122, CD166, CD177, CCR7, CXCR3, CXCR5, HLA-DR, ICOS, LAG-3/CD223, OX-40, PD-1 , S1000A8/9, TIM-3, TLT-2, 2B4, CD5, and 41 BB. In some embodiments, the first binding domain specifically binds to an antigen selected from CD3, CD5, CD8, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD103 (ITGAE), CD122, CD166, CD177, CCR7, CXCR3, CXCR5, HLA-DR, ICOS, LAG-3/CD223, OX-40, PD-1 , S1000A8/9, TIM-3, TLT-2, 2B4, and 41 BB. In some embodiments, the first binding domain specifically binds to a subunit of an antigen selected from CD3, CD8, CD40L, CD122, HLA-DR, OX-40, S1000A8/9, and 41 BB/CD137.

In some embodiments, the first antigen is selected from a functional agonist that can activate the CD8 KIR+ Tregs. In some embodiments, such an antigen is, for example, CD3, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD122, ICOS, OX-40, 2B4, 41 BB, and HLA-DR. In some embodiments, such an antigen is, for example, CD3, CD5, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD122, ICOS, OX-40, 2B4, 41 BB, and HLA-DR. In some embodiments, the first binding domain has agonist activity when bound to such an antigen.

In some embodiments, the first antigen is selected from a functional antagonist to reduce functional inhibition of CD8 KIR+ Tregs. In some embodiments, such as antigen is, for example, LAG-3/CD223, TIM-3, PD-1 , S1000A8/9, and TLT2. In some embodiments, the first binding domain has antagonist activity (e.g., blocking activity) when bound to such an antigen.

In some embodiments, the first antigen is a tethering moiety to enhance specificity of binding agent to CD8 KIR+ Tregs. In some embodiments, such an antigen is, for example, CD3, CD8, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD103 (ITGAE), CD122, CD166, CD177, CCR7, CXCR3, CXCR5, HLA-DR, ICOS, LAG-3/CD223, OX-40, PD-1 , S1000A8/9, TIM-3, TLT-2, 2B4, and 41 BB. In some embodiments, such an antigen is, for example, CD3, CD5, CD8, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD103 (ITGAE), CD122, CD166, CD177, CCR7, CXCR3, CXCR5, HLA-DR, ICOS, LAG-3/CD223, OX-40, PD-1 , S1000A8/9, TIM-3, TLT-2, 2B4, and 41 BB. In some embodiments, the first binding domain specifically binds to such an antigen.

In some embodiments, the first antigen is a tethering moiety to enhance tissue specificity. In some embodiments, such an antigen is, for example, CD103 (ITGAE), CD166, CD177, CXCR3, and S1000A8/9. In some embodiments, the first binding domain specifically binds to such an antigen.

In some embodiments, the first antigen is an agonist to enhance CD8 KIR+ Treg cell migration. In some embodiments, such an antigen is, for example, CCR7, CXCR3, or CXCR5. In some embodiments, the first binding domain specifically binds to such an antigen.

In some embodiments, the first antigen is selected from PD-1 , ICOS, and CXCR3. In some embodiments, the first binding domain specifically binds to such an antigen.

In some embodiments, the first antigen is selected from CD3 or CD8. In some embodiments, the first antigen is selected from CD3, CD5, or CD8. In some embodiments, the first antigen is selected from a subunit of CD3 or CD8. In some embodiments, the first antigen is CD3epsilon. In some embodiments, the first antigen is CD8alpha.

The second binding domain of the binding agent specifically binds to an inhibitory KIR protein (killer cell immunoglobulin like receptor protein). The inhibitory KIR protein can be, for example, KIR3DL1 , KIR3DL2, KIR2DL1 , KIR2DL2, or KIR2DL3 or a combination thereof, such as specifically binding to KIR2DL1/2/3 or KIR2DL1/2 proteins. In some embodiments, the KIR protein is selected from KIR3DL1 , KIR3DL2, KIR2DL1 , KIR2DL2, or KIR2DL3 or a combination thereof, such as KIR2DL1/2/3 or KIR2DL1/2 proteins. In some embodiments, the second binding domain is a KIR protein antagonist that blocks KIR protein interaction with its binding partner.

A binding agent can be any suitable agent that includes binding domains for both antigens. In some embodiments, a binding agent is bispecific (i.e., having binding domains for two different antigens). In some embodiments, a binding agent is bivalent (i.e., having two binding domains). In some embodiments, the binding agent is tetravalent (i.e., having four binding domains).

The binding domains of the binding agents can be derived from antibodies or from non-antibody formats. In some embodiments, a binding domain is derived from an antibody or antigen binding portions thereof (i.e., an antibody fragment). In some embodiments, the antibody fragment is a Fab, Fab', F(ab')2, Fv, scFv, or a single domain antibody (also referred to as a VHH, VNAR, sdAb, or nanobody). In some embodiments, a binding domain is or is derived from an anticalin, affibody, avimer, DARPin, or adnectin.

In some embodiments, the binding agent is a bispecific antibody, a diabody, an antibody Fc fusion, scFv1-ScFv2, an SCFV12-FC-SCFV22, an IgG-scFv, a DVD-lg, a triomab/quadroma, a two-in-one IgG, a scFv2-Fc, a TandAb, an scFv-HSA-scFv, an scFv-VHH, a Fab-scFv-Fc, a Fab-VHH-Fc, a dAb-IgG, an IgG-VHH, a Tandem scFv-Fc, a (SCFV1 )2-FC-(VHH)2, a BiTe, a DART, a crossmab, an anticalin, an affibody, an avimer, a DARPin, an adnectin, a scFv-Fc, a one-armed tandem scFV- Fc, or a DART-Fc (see, e.g., Figures 1-3). In some embodiments, the IgG-scFv is an lgG(H)-scFv, scFv-(H)lgG, lgG(L)-scFv, scFv-(L)lgG, 2scFV-lgG, or lgG-2scFv (as shown in Figure 1).

In some embodiments, the binding agent comprises a first binding domain comprising a heavy chain variable region and a light chain variable region. In some embodiments, the heavy and light chain variable regions of the first binding domain specifically bind to an antigen expressed on a CD8+KIR+ Treg, such as CD3, CD8, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD103 (ITGAE), CD122, CD166, CD177, CCR7, CXCR3, CXCR5, HLA-DR, ICOS, LAG-3/CD223, OX-40, PD-1 , S1000A8/9, TIM-3, TLT-2, 2B4, and 41 BB. In some embodiments, the heavy and light chain variable regions of the first binding domain specifically bind to an antigen expressed on a CD8+KIR+ Treg, such as CD3, CD5, CD8, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD103 (ITGAE), CD122, CD166, CD177, CCR7, CXCR3, CXCR5, HLA-DR, ICOS, LAG-3/CD223, OX-40, PD-1 , S1000A8/9, TIM-3, TLT-2, 2B4, and 41 BB. In some embodiments, the heavy and light chain variable regions of the first binding domain specifically bind to a subunit of an antigen expressed on a CD8+KIR+ Treg, such as CD3, CD8, CD40L, CD122, HLA-DR, OX-40, S1000A8/9, and 41 BB/CD137. In some embodiments, the heavy and light chain variable regions of the first binding domain specifically bind to a subunit of an antigen expressed on a CD8+KIR+ Treg, such as CD3, CD5, CD8, CD40L, CD122, HLA-DR, OX-40, S1000A8/9, and 41 BB/CD137.

In some embodiments, the first antigen is a tethering moiety to enhance tissue specificity. In some embodiments, such an antigen is, for example, CD103 (ITGAE), CD166, CD177, CXCR3, or S1000A8/9. In some embodiments, the first binding domain specifically binds to such an antigen.

In some embodiments, the first antigen is an agonist to enhance CD8 KIR+ Tregs cell migration. In some embodiments, such an antigen is, for example, CCR7, CXCR3, or CXCR5. In some embodiments, the first binding domain specifically binds to such an antigen.

Antibodies for use in the binding domains described herein are known in the art.

Antibodies to CD3 have been described in, for example, US Patent Nos. 5,929,212; 5,885,573; and 8,551 ,478 and in International Patent Publication WO201 8223004.

Antibodies to CD8 have been described in, for example, Published US Patent Application Nos. 20190382488 and 20190071500 and International Patent Publication WO2014164553 and WO2017134306.

Antibodies to CD5 have been described in, for example, Published US Patent Application Nos. 2018/0104308, 2011/0250203, and 2008/0254027.

Antibodies to CD27 have been described in, for example, Published US Patent Application Nos. 20210009706, 20200247898, and 20200131272. Antibodies to CD38 have been described in, for example, Published US Patent Application Nos. 20200408765, 20200399391 , 20090304710, and 20050158305.

Antibodies to CD39 have been described in, for example, Published US Patent Application Nos. 20190062448, 20130273062, and 20100303828.

Antibodies to CD40L have been described in, for example, Published US Patent Application Nos. 20190092868, 20100092482, 20030031668, and 20010018041.

Antibodies to CD45RA, CD45RB and CD45RO have been described in, for example, Published US Patent Application Nos. 20030232009 and 20020168362 and are available from commercial sources.

Antibodies to CD73 have been described in, for example, Published US Patent Application Nos. 20200148781 , 20200071404, 20190256598, and 20160145350.

Antibodies to CD103 (ITGAE) have been described in, for example, Published US Patent Application No. 20050266001.

Antibodies to CD122 have been described in, for example, Published US Patent Application Nos. 20180362655 and 20110250213.

Antibodies to CD166 have been described in, for example, Published US Patent Application Nos. 20160355587 and 20090269787.

Antibodies to CD177 have been described in, for example, Published US Patent Application No. 20190125832.

Antibodies to CCR7 have been described in, for example, Published US Patent Application Nos. 20200216548, 20180237529, and 20150344580.

Antibodies to CXCR3 have been described in, for example, Published US Patent Application Nos. 20190119391 , 20190008955, and 20130251733.

Antibodies to CXCR5 have been described in, for example, Published US Patent Application Nos. 20190169283, 20160053014, and 20130236476.

Antibodies to HLA-DR have been described in, for example, Published US Patent Application Nos. 20180355043 and 20190071503.

Antibodies to ICOS have been described in, for example, Published US Patent Application Nos. 20160304610 and 20110243929. Antibodies to LAG-3/CD223 have been described in, for example, Published US Patent Application Nos. 20210009687, 20200277372, 20200071403, and 20190276538.

Antibodies to 0X40 have been described in, for example, Published US Patent Application Nos. 20140377284, 20140308276, and 20100196359.

Antibodies to PD-1 have been described in, for example, Published US Patent Application Nos. 20190322749, 20190309069, 20170313774, and 20110171215.

Antibodies to S1000A8/9 have been described in, for example, Published US Patent Application Nos. 20180256710 and 20200023045.

Antibodies to TIM-3 have been described in, for example, Published US Patent Application Nos. 20180072804, 20170306016, and 20150086574.

Antibodies to TLT-2 have been described in, for example, Published US Patent Application No. 20130216540.

Antibodies to 2B4 are available, for example, from commercial vendors.

Antibodies to 41 BB have been described in, for example, Published US Patent Application Nos. 20170198050 and 20200347144.

In some embodiments, the first binding domain specifically binds to CD3epsilon and the heavy and light chain variable regions have the amino acid sequences set forth in SEQ ID NO:1 and SEQ ID NO:2, respectively; SEQ ID NO:9 and SEQ ID NO: 10, respectively; SEQ ID NO: 17 and SEQ ID NO: 18, respectively; SEQ ID NO:25 and SEQ ID NO:26, respectively; SEQ ID NO:33 and SEQ ID NO:34, respectively; SEQ ID NO:41 and SEQ ID NO:34, respectively; SEQ ID NO:45 and SEQ ID NO:34, respectively; SEQ ID NO:49 and SEQ ID NQ:50, respectively; SEQ ID NO:57 and SEQ ID NO:58, respectively; SEQ ID NO:65 and SEQ ID NO:66, respectively; or SEQ ID NO:65 and SEQ ID NO: 166, respectively.

In some embodiments, the first binding domain specifically binds to CD3epsilon and the heavy and light chain variable regions have the amino acid sequences set forth in SEQ ID NO:1 and SEQ ID NO:2, respectively; SEQ ID NO:9 and SEQ ID NO: 10, respectively; SEQ ID NO: 17 and SEQ ID NO: 18, respectively; SEQ ID NO:25 and SEQ ID NO:26, respectively; SEQ ID NO:33 and SEQ ID NO:34, respectively; SEQ ID NO:41 and SEQ ID NO:34, respectively; SEQ ID NO:45 and SEQ ID NO:34, respectively; SEQ ID NO:49 and SEQ ID NQ:50, respectively; SEQ ID NO:57 and SEQ ID NO:58, respectively; SEQ ID NO:65 and SEQ ID NO:66, respectively; or SEQ ID NO:65 and SEQ ID NO: 166, respectively; wherein the framework regions of the heavy and light chain variable regions are optionally modified with from 1 to 8, 1 to 6, 1 to 4 or 1 to 2 amino acid substitutions, deletions or insertions, and wherein the CDRs of the heavy or light chain variable regions are not modified.

In some embodiments, the first binding domain comprises an amino acid sequence (e.g., a VH, VL, hCDR1 , hCDR1 , hCDR3, ICDR1 , ICDR2, and/or ICDR3) according to any one or more of SEQ ID NOs:1-72 and 166-169.

In some embodiments, the first binding domain specifically binds to CD8alpha and the heavy and light chain variable regions have the amino acid sequences set forth in SEQ ID NO:73 and SEQ ID NO:74, respectively; or SEQ ID NO:81 and SEQ ID NO:82, respectively; or the binding domain comprises a VHH chain having the amino acid sequence set forth in SEQ ID NO:89, SEQ ID NO:93, or SEQ ID NO:97.

In some embodiments, the first binding domain specifically binds to CD8alpha and the heavy and light chain variable regions have the amino acid sequences set forth in SEQ ID NO:73 and SEQ ID NO:74, respectively; or SEQ ID NO:81 and SEQ ID NO:82, respectively; or the binding domain comprises a VHH chain having the amino acid sequence set forth in SEQ ID NO:89, SEQ ID NO:93, or SEQ ID NO:97, respectively; wherein the framework regions of the heavy and light chain variable regions or VHH chain are optionally modified with from 1 to 8, 1 to 6, 1 to 4, or 1 to 2 amino acid substitutions, deletions, or insertions, and wherein the CDRs of the heavy or light chain variable regions or the VHH chain are not modified.

In some embodiments, the first binding domain comprises an amino acid sequence (e.g., a VH, VL, hCDR1 , hCDR1 , hCDR3, ICDR1 , ICDR2, and/or ICDR3) according to any one or more of SEQ ID NQs:73-100.

In some embodiments, the first binding domain specifically binds to CD3epsilon and the heavy chain variable regions has complementarity determining regions hCDR1 , hCDR2, and hCDR3, the light chain variable region ICDR1 , ICDR2, and ICDR3, and the amino acid sequences of the heavy and light chain variable region CDRs are set forth in SEQ ID NO:3 to SEQ ID NO:8, respectively; SEQ ID NO:11 to SEQ ID NO:16, respectively; SEQ ID NO:19 to SEQ ID NO:24, respectively; SEQ ID NO:27 to SEQ ID NO:32, respectively; SEQ ID NO:35 to SEQ ID NQ:40, respectively; SEQ ID NO:42 to SEQ ID NO:44 and SEQ ID NO:38 to SEQ ID NQ:40, respectively; SEQ ID NO:46 to SEQ ID NO:48 and SEQ ID NO:38 to SEQ ID NQ:40, respectively; SEQ ID NO:51 to SEQ ID NO:56, respectively; SEQ ID NO:59 to SEQ ID NO:64, respectively; or SEQ ID NO:67 to SEQ ID NO:72, respectively. In some embodiments, the first binding domain specifically binds to CD3epsilon and comprises light chain variable region ICDR1 , ICDR2, and ICDR3 having the amino acid sequences set forth in SEQ ID NOs:167, 168, and 169, respectively.

In some embodiments, the first binding domain specifically binds to CD8alpha and has heavy chain variable regions having complementarity determining regions hCDR1 , hCDR2, and hCDR3 and the light chain variable region has ICDR1 , ICDR2, and ICDR3, the amino acid sequences of the heavy and light chain variable region CDRs are set forth in SEQ ID NO:75 to SEQ ID NQ:80, respectively; or SEQ ID NO:83 to SEQ ID NO:88, respectively; or the first binding domain includes a VHH chain having hCDR1 , hCDR2, and hCDR3, and the amino acid sequences of the VHH CDRs are set forth in SEQ ID NQ:90 to SEQ ID NO:92, respectively; SEQ ID NO:94 to SEQ ID NO:96, respectively; or SEQ ID NO:98 to SEQ ID NO: 100, respectively.

In some embodiments, the first binding domain specifically binds to ICOS and the heavy and light chain variable regions have the amino acid sequences set forth in SEQ ID NQ:170 and SEQ ID NO:171 , respectively.

In some embodiments, the first binding domain specifically binds to ICOS and the heavy and light chain variable regions have the amino acid sequences set forth in SEQ ID NO: 170 and SEQ ID NO: 171 , respectively; wherein the framework regions of the heavy and light chain variable regions are optionally modified with from 1 to 8, 1 to 6, 1 to 4, or 1 to 2 amino acid substitutions, deletions, or insertions, and wherein the CDRs of the heavy or light chain variable regions are not modified.

In some embodiments, the first binding domain comprises an amino acid sequence (e.g., a VH, VL, hCDR1 , hCDR1 , hCDR3, ICDR1 , ICDR2, and/or ICDR3) according to any one or more of SEQ ID NOs: 170-177. In some embodiments, the first binding domain specifically binds to PD-1 and the heavy and light chain variable regions have the amino acid sequences set forth in SEQ ID NO: 178 and SEQ ID NO: 179, respectively.

In some embodiments, the first binding domain specifically binds to PD-1 and the heavy and light chain variable regions have the amino acid sequences set forth in SEQ ID NO: 178 and SEQ ID NO: 179, respectively; wherein the framework regions of the heavy and light chain variable regions are optionally modified with from 1 to 8, 1 to 6, 1 to 4, or 1 to 2 amino acid substitutions, deletions, or insertions, and wherein the CDRs of the heavy or light chain variable regions are not modified.

In some embodiments, the first binding domain comprises an amino acid sequence (e.g., a VH, VL, hCDR1 , hCDR1 , hCDR3, ICDR1 , ICDR2, and/or ICDR3) according to any one or more of SEQ ID NOs: 178-185.

In some embodiments, the first binding domain specifically binds to CXCR3 and the heavy and light chain variable regions have the amino acid sequences set forth in SEQ ID NO: 186 and SEQ ID NO: 187, respectively.

In some embodiments, the first binding domain specifically binds to CXCR3 and the heavy and light chain variable regions have the amino acid sequences set forth in SEQ ID NO: 186 and SEQ ID NO: 187, respectively; wherein the framework regions of the heavy and light chain variable regions are optionally modified with from 1 to 8, 1 to 6, 1 to 4, or 1 to 2 amino acid substitutions, deletions, or insertions, and wherein the CDRs of the heavy or light chain variable regions are not modified.

In some embodiments, the first binding domain comprises an amino acid sequence (e.g., a VH, VL, hCDR1 , hCDR1 , hCDR3, ICDR1 , ICDR2, and/or ICDR3) according to any one or more of SEQ ID NOs: 186-193.

In some embodiments, the first binding domain specifically binds to CD5 and the heavy and light chain variable regions have the amino acid sequences set forth in SEQ ID NO: 194 and SEQ ID NO: 195, respectively.

In some embodiments, the first binding domain specifically binds to CD5 and the heavy and light chain variable regions have the amino acid sequences set forth in SEQ ID NO: 194 and SEQ ID NO: 195, respectively; wherein the framework regions of the heavy and light chain variable regions are optionally modified with from 1 to 8, 1 to 6, 1 to 4, or 1 to 2 amino acid substitutions, deletions, or insertions, and wherein the CDRs of the heavy or light chain variable regions are not modified.

In some embodiments, the first binding domain comprises an amino acid sequence (e.g., a VH, VL, hCDR1 , hCDR1 , hCDR3, ICDR1 , ICDR2, and/or ICDR3) according to any one or more of SEQ ID NOs: 194-201.

In some embodiments, the binding agent comprises a second binding domain comprising a heavy chain variable region and a light chain variable region. The second binding domain of the binding agent specifically binds to an inhibitory KIR protein (killer cell immunoglobulin like receptor protein). The inhibitory KIR protein can be KIR3DL1 , KIR3DL2, KIR2DL1 , KIR2DL2, or KIR2DL3 or a combination thereof, such as specifically binding to KIR2DL1/2/3 or KIR2DL1/2 proteins.

Antibodies to inhibitory KIR proteins are known in the art.

Antibodies to KIR3DL1 have been described in, for example, US Patent No. 5,770,387 and International Patent Publication WO2018148223.

Antibodies to KIR3DL2 have been described in, for example, Published US Application No. 20200199228 and 20150232556.

Antibodies to KIR2DL1 , KIR2DL2, KIR2DL3, and combinations thereof have been described in, for example, US Patent Nos. 10,668,180 and 10,253,095, International Patent Publication W02006003179, Published US Application Nos. 20150290316 and 20130251711 and European Patent No. 3072522.

In some embodiments, the second binding domain specifically binds to KIR3DL1 and the heavy and light chain variable regions have the amino acid sequences set forth in SEQ ID NO: 133 and SEQ ID NO: 134, respectively; SEQ ID NO:141 and SEQ ID NO:142, respectively; or SEQ ID NO:149 and SEQ ID NQ:150, respectively.

In some embodiments, the first binding domain specifically binds to KIR3DL1 and the heavy and light chain variable regions have the amino acid sequences set forth in SEQ ID NO: 133 and SEQ ID NO: 134, respectively; SEQ ID NO: 141 and SEQ ID NO: 142, respectively; or SEQ ID NO: 149 and SEQ ID NO: 150, respectively; wherein the framework regions of the heavy and light chain variable regions are optionally modified with from 1 to 8, 1 to 6, 1 to 4, or 1 to 2 amino acid substitutions, deletions, or insertions, and wherein the CDRs of the heavy or light chain variable regions are not modified.

In some embodiments, the first binding domain specifically binds to KIR3DL2 and the heavy and light chain variable regions have the amino acid sequences set forth in the amino acid sequences set forth in SEQ ID NO: 157 and SEQ ID NO: 158, respectively.

In some embodiments, the first binding domain specifically binds to KIR3DL2 and the heavy and light chain variable regions have the amino acid sequences set forth in SEQ ID NO: 157 and SEQ ID NO: 158, respectively; wherein the framework regions of the heavy and light chain variable regions are optionally modified with from 1 to 8, 1 to 6, 1 to 4, or 1 to 2 amino acid substitutions, deletions, or insertions, and wherein the CDRs of the heavy or light chain variable regions are not modified.

In some embodiments, the first binding domain specifically binds to KIR2DL1/2/3 and the heavy and light chain variable regions have the amino acid sequences set forth in SEQ ID NO: 101 and SEQ ID NO: 102, respectively; SEQ ID NQ:109 and SEQ ID NQ:110, respectively; SEQ ID NO:117 and SEQ ID NO:118, respectively; or SEQ ID NO: 125 and SEQ ID NO: 126, respectively.

In some embodiments, the first binding domain specifically binds to KIR2DL1/2/3 and the heavy and light chain variable regions have the amino acid sequences set forth in SEQ ID NO: 101 and SEQ ID NO: 102, respectively; SEQ ID NQ:109 and SEQ ID NQ:110, respectively; SEQ ID NO:117 and SEQ ID NO:118, respectively; or SEQ ID NO: 125 and SEQ ID NO: 126, respectively; wherein the framework regions of the heavy and light chain variable regions are optionally modified with from 1 to 8, 1 to 6, 1 to 4, or 1 to 2 amino acid substitutions, deletions or insertions, and wherein the CDRs of the heavy or light chain variable regions are not modified.

In some embodiments, the first binding domain specifically binds to KIR3DL1 and the heavy chain variable region has complementarity determining regions (CDR) hCDR1 , hCDR2, and hCDR3, the light chain variable region has ICDR1 , ICDR2, and ICDR3,and the amino acid sequences of the heavy and light chain variable region CDRs have the amino acid sequences set forth in SEQ ID NO: 135 to SEQ ID NO: 140, respectively; SEQ ID NO: 143 to SEQ ID NO: 148, respectively; or SEQ ID NO: 151 to SEQ ID NO: 156, respectively.

In some embodiments, the first binding domain specifically binds to KIR3DL2 and the heavy chain variable region has complementarity determining regions hCDR1 , hCDR2, and hCDR3, the light chain variable region has ICDR1 , ICDR2, and ICDR3, and the amino acid sequences of the heavy and light chain variable region CDRs are set forth in the amino acid sequences of SEQ ID NO: 159 to SEQ ID NO: 164, respectively.

In some embodiments, the first binding domain specifically binds to KIR2DL1/2/3 and the heavy chain variable region has complementarity determining regions hCDR1 , hCDR2, and hCDR3, the light chain variable region has ICDR1 , ICDR2, and ICDR3, the amino acid sequences of the heavy and light chain variable region CDRs are set forth in SEQ ID NO: 103 to SEQ ID NO: 108, respectively; SEQ ID NO:111 to SEQ ID NO:116, respectively; SEQ ID NO:119 to SEQ ID NO:124, respectively; or SEQ ID NO: 127 to SEQ ID NO: 132, respectively.

Binding Agents

The binding agent can be any suitable agent that includes at least a first binding domain and a second binding domain, wherein the first binding domain that specifically binds to a first antigen that is selected from antigens expressed on CD8+KIR+ T regulatory cells (Tregs), other than a KIR protein; and a second binding domain that specifically binds to an inhibitory KIR protein, wherein the binding agent binds to CD8+KIR+ Tregs.

In some embodiments, a binding agent is bispecific (i.e. , having binding domains for two different antigens). In some embodiments, a binding agent is bivalent (i.e., having two binding domains). In some embodiments, the binding agent is tetravalent (i.e., having four binding domains). In some embodiments, the binding agent is trivalent, hexavalent, or octavalent.

The binding domains of the binding agents can be derived from antibodies or from non-antibody formats. In some embodiments, a binding domain is derived from an antibody or antigen binding portion thereof (i.e., an antigen binding antibody fragment). In some embodiments, the antibody fragment is a Fab, Fab', F(ab')2, Fv, scFv, or a single domain antibody (also referred to as a VHH, VNAR, sdAb, or nanobody). In some embodiments, a binding domain is derived from an anticalin, affibody, avimer, DARPin, adnectin, or a receptor ectodomain Fc fusion protein.

In some embodiments, the binding agent is a bispecific antibody, a diabody, an antibody Fc fusion, scFv1-ScFv2, an SCFV12-FC-SCFV22, an IgG-scFv, a DVD-lg, a triomab/quadroma, a two-in-one IgG, a scFv2-Fc, a TandAb, an scFv-HSA-scFv, an scFv-VHH, a Fab-scFv-Fc, a Fab-VHH-Fc, a dAb-IgG, an IgG-VHH, a Tandem scFv-Fc, a (SCFV1 )2-FC-(VHH)2, a BiTe, a DART, a crossmab, an anticalin, an affibody, an avimer, a DARPin, an adnectin, a scFv-Fc, a one-armed tandem scFv- Fc, or a DART-Fc. In some embodiments, the IgG-scFv is an lgG(H)-scFv, scFv- (H)lgG, lgG(L)-scFv, scFv-(L)lgG, 2scFV-lgG, or lgG-2scFv (as shown in Figure 1 ).

As used herein, the term "antibody" refers to immunoglobulin molecules and immunologically active portions of immunoglobulin molecules, i.e. , molecules that contain an antigen binding site (antigen binding portion) that specifically binds to a target antigen. The term generally refers to antibodies comprised of two immunoglobulin heavy chain variable regions and two immunoglobulin light chain variable regions including full length antibodies (having heavy and light chain constant regions) and antigen-binding portions thereof; including, for example, an intact monoclonal antibody, a Fab, a Fab', a F(ab')2, a Fv, a disulfide linked Fv, a scFv, a single domain antibody (dAb), a diabody, a multi-specific antibody, a dual specific antibody, a bispecific antibody, and single chain antibodies (see, e.g., Huston et al., Proc. Natl. Acad. Sci. U.S.A., 85, 5879-5883 (1988) and Bird et al., Science 242, 423-426 (1988), which are incorporated herein by reference).

In an antibody, each heavy chain is composed of a variable region (abbreviated as VH) and a constant region. The heavy chain constant region may include three domains CH1 , CH2, and CH3 and optionally a fourth domain, CH4. Each of these domains is referred to as an "Fc domain". As used herein, when a binding agent includes an Fc domain, it can include one or more Fc domains, or an entire Fc region, unless otherwise specified by context. Each light chain is composed of a variable region (abbreviated as VL) and a constant region or constant domain. The light chain constant region is a CL domain. The VH and VL regions may be further divided into hypervariable regions referred to as complementarity- determining regions (CDRs) and interspersed with conserved regions referred to as framework regions (FR). Each VH and VL region thus consists of three CDRs and four FRs that are arranged from the N terminus to the C terminus in the following order: FR1 , CDR1 , FR2, CDR2, FR3, CDR3, and FR4. This structure is well known to those skilled in the art.

As used herein, an "antigen-binding portion" of an antibody refers to the portions of an antibody as described herein having the VH and VL sequences or the heavy and light chain variable region CDRs. In accordance with the term "antigenbinding portion" of an antibody, examples of antigen binding portions include a Fab, a Fab', a F(ab')2, a Fv, a disulfide linked Fv, a scFv, a single domain antibody (dAb), a diabody, and single chain antibodies. As used herein, the terms Fab, F(ab')2 and Fv refer to the following: (i) an Fab fragment, i.e. a monovalent fragment composed of the VL, VH, CL and CH1 domains; (ii) an F(ab')2 fragment, i.e., a bivalent fragment comprising two Fab fragments linked to one another in the hinge region via a disulfide bridge; and (iii) an Fv fragment composed of the VL and VH domains of an antibody. Although the two domains of the Fv fragment, namely VL and VH, are encoded by separate coding regions, they may further be linked to one another using a synthetic linker, e.g. a poly-G4S amino acid sequence ('(G4S)n' disclosed as SEQ ID NO: 165, wherein n =1 to 5), making it possible to prepare them as a single protein chain in which the VL and VH regions combine in order to form monovalent molecules (known as single chain Fv (ScFv)). The term "antigen-binding portion" of an antibody is also intended to include such single chain antibodies.

Other forms of single chain antibodies such as "diabodies" are likewise included here. Diabodies are bivalent, bispecific antibodies in which VH and VL domains are expressed on a single polypeptide chain, but using a linker connecting the VH and VL domains that is too short for the two domains to be able to combine on the same chain, thereby forcing the VH and VL domains to pair with complementary domains of a different chain (VL and VH, respectively), and to form two antigen-binding sites (see, e.g., Holliger, R, et al. (1993) Proc. Natl. Acad. Sci. USA 90:64446448; Poljak, R. J, et al. (1994) Structure 2:1121-1123).

An immunoglobulin constant region, or Fc region, refers to a heavy or light chain constant region. Human heavy chain and light chain constant region amino acid sequences are known in the art. A constant region can be of any suitable type, which can be selected from the classes of immunoglobulins, IgA, IgD, IgE, IgG, and IgM. Several immunoglobulin classes can be further divided into isotypes, e.g., IgGI, lgG2, lgG3, lgG-4, or IgAI, and lgA2. The heavy-chain constant regions (Fc) that corresponds to the different classes of immunoglobulins can be a, 5, E, y, and p, respectively. The light chains can be one of either kappa (or K) and lambda (or A).

In some embodiments the binding agent lacks an Fc region or domains thereof. In some embodiments, the binding agent has an entire Fc region or an Fc domain thereof. In some embodiments, the binding agent has an Fc region or Fc domain of an IgG 1 isotype. In some embodiments, the binding agent has an Fc region or Fc domain of an lgG2 isotype. In some embodiments, the binding agent has an Fc region or Fc domain of an lgG3 isotype. In some embodiments, the binding agent has an Fc region or Fc domain of an lgG4 isotype. In some embodiments, an Fc domain can have a hybrid isotype comprising constant regions from two or more isotypes. In some embodiments, an Fc region or Fc domain can be an lgG1 or lgG4 constant region.

In some embodiments, the C-terminus of an Fc domain (e.g., the heavy chain) can be a complete C-terminus ending with the amino acid residues PGK. In some embodiments, the C-terminus of the Fc domain also can be a shortened C-terminus in which one or two of the C terminal amino acid residues have been removed. In some embodiments, the C-terminus of the Fc domain is a shortened C-terminus ending PG. In some embodiments, a binding agent comprising a heavy chain including a C-terminal CH3 domain comprises the C-terminal glycine-lysine dipeptide (G446 and K447, numbering according to Kabat Ell index). In some embodiments, a binding agent comprising a heavy chain including a C-terminal CH3 domain comprises a C-terminal glycine residue (G446, numbering according to Kabat Ell index).

The binding agents as described herein are multispecific, typically bispecific binding agents. In some embodiments, the binding agents are multispecific antibodies or antibody-like molecules, such as bispecific antibodies. Multispecific antibodies are monoclonal antibodies that have binding specificities for at least two different sites or antigens. The binding agents described herein typically have binding specificities for different antigens. Bispecific antibodies can be prepared as full length antibodies or antibody fragments. Bispecific and multi-specific antibodies include the following: an scFv1-ScFv2, an SCFV12-FC-SCFV22, an IgG-scFv, a DVD- Ig, a triomab/quadroma, a two-in-one IgG, a scFv2-Fc, a TandAb, an scFv-HSA- scFv, an scFv-VHH, a Fab-scFv-Fc, a Fab-VHH-Fc, a dAb-IgG, an IgG-VHH, a Tandem scFv-Fc, and a (scFv1 )2-Fc-(VHH)2, a scFv-Fc, a one-armed tandem scFv- Fc, and a DART-Fc. In some embodiments, the IgG-scFv is an lgG(H)-scFv, scFv- (H)lgG, lgG(L)-scFv, svFc-(L)lgG, 2scFV-lgG, or lgG-2scFv (as shown in Figure 1 ).

Techniques for making multispecific antibodies include, but are not limited to, recombinant co-expression of two immunoglobulin heavy chain-light chain pairs having different specificities (see Milstein and Cuello, Nature 305: 537 (1983)), WO 93/08829, and Traunecker et al., EMBO J. 10: 3655 (1991 )), and "knob-in-hole" engineering (see, e.g., U.S. Pat. No. 5,731 ,168). Multi-specific antibodies may also be made by engineering electrostatic steering effects for making antibody Fc- heterodimeric molecules (WO 2009/089004A1); cross-linking of two or more antibodies or fragments (see, e.g., U.S. Pat. No. 4,676,980, and Brennan et al., Science, 229: 81 (1985)); using leucine zippers to produce bi-specific antibodies (see, e.g., Kostelny et al., J. Immunol., 148(5): 1547-1553 (1992)); using "diabody" technology for making bispecific antibody fragments (see, e.g., Hollinger et al., Proc. Natl. Acad. Sci. USA, 90:6444-6448 (1993)); using single-chain Fv (scFv) dimers (see, e.g., Gruber et al., J. Immunol., 152:5368 (1994)); and preparing trispecific antibodies as described, e.g., in Tutt et al. J. Immunol. 147: 60 (1991 ).

Engineered antibodies with three or more functional antigen binding sites, including "Octopus antibodies," are also included herein (see, e.g., US 2006/0025576A1).

The binding agents (e.g., antibodies or antigen binding fragments) herein also include a "Dual Acting FAb" or "DAF" comprising an antigen binding site that binds to two different antigens (see, e.g., US 2008/0069820 and Bostrom et al., 2009, Science 323:1610-14). "Crossmab" antibodies are also included herein (see, e.g., WO 2009/080251 , WO 2009/080252, W02009/080253, W02009/080254, and WO20 13/026833). In some embodiments, the binding agents comprise different antigen-binding sites, fused to one or the other of the two subunits of the Fc domain; thus, the two subunits of the Fc domain may be comprised in two non-identical polypeptide chains. Recombinant co-expression of these polypeptides and subsequent dimerization leads to several possible combinations of the two polypeptides. To improve the yield and purity of the bispecific molecules in recombinant production, it will thus be advantageous to introduce in the Fc domain of the binding agent a modification promoting the association of the desired polypeptides.

Accordingly, in particular aspects relates to a binding agent comprising (a) at least a first binding domain, (b) a second binding domain, and (c) a Fc domain composed of a first and a second subunit capable of stable association, wherein the Fc domain comprises a modification promoting the association of the first and second subunit of the Fc domain. The site of most extensive protein-protein interaction between the two subunits of a human IgG Fc domain is in the CH3 domain of the Fc domain. Thus, in one aspect said modification is in the CH3 domain of the Fc domain.

In a specific aspect, the Fc modification is a so-called "knob-into-hole" modification, comprising a "knob" modification in one of the two subunits of the Fc domain and a "hole" modification in the other one of the two subunits of the Fc domain. In a particular aspect, the first subunit of the Fc domain comprises the amino acid substitutions S354C and T366W (Ell numbering) and the second subunit of the Fc domain comprises the amino acid substitutions Y349C, T366S, and Y407V (numbering according to Kabat Ell index).

The knob-into-hole technology is described, e.g., in U.S. Pat. Nos. 5,731 ,168; 7,695,936; Ridgway et al., Prot Eng 9, 617-621 (1996) and Carter, J Immunol Meth 248, 7-15 (2001 ). Generally, the method involves introducing a protuberance ("knob") at the interface of a first polypeptide and a corresponding cavity ("hole") in the interface of a second polypeptide, such that the protuberance can be positioned in the cavity so as to promote heterodimer formation and hinder homodimer formation. Protuberances are constructed by replacing small amino acid side chains from the interface of the first polypeptide with larger side chains (e.g., tyrosine or tryptophan). Compensatory cavities of identical or similar size to the protuberances are created in the interface of the second polypeptide by replacing large amino acid side chains with smaller ones (e.g., alanine or threonine).

Accordingly, in some embodiments, in a CH3 domain of an Fc domain an amino acid residue is replaced with an amino acid residue having a larger side chain volume, thereby generating a protuberance within the CH3 domain which is positionable in a cavity within a CH3 domain of a second Fc domain, and in the CH3 domain of the second Fc domain an amino acid residue is replaced with an amino acid residue having a smaller side chain volume, thereby generating a cavity within the CH3 domain of the second Fc domain within which the protuberance within the CH3 domain of the first Fc domain is positionable. The protuberance and cavity can be made by altering the nucleic acid encoding the polypeptides, e.g., by site-specific mutagenesis, or by peptide synthesis. In some embodiments, in the CH3 domain of the first Fc domain the threonine residue at position 366 is replaced with a tryptophan residue (T366W), and in the CH3 domain of the second Fc domain the tyrosine residue at position 407 is replaced with a valine residue (Y407V). In some embodiments, in the second Fc domain additionally the threonine residue at position 366 is replaced with a serine residue (T366S) and the leucine residue at position 368 is replaced with an alanine residue (L368A).

In some embodiments, in the first Fc domain additionally the serine residue at position 354 is replaced with a cysteine residue (S354C), and in the second Fc domain additionally the tyrosine residue at position 349 is replaced by a cysteine residue (Y349C). Introduction of these two cysteine residues results in the formation of a disulfide bridge between the two Fc domains that further stabilizes the dimer (Carter (2001 ), J Immunol Methods 248, 7-15). In some embodiments, the first Fc domain comprises the amino acid substitutions S354C and T366W (Ell numbering) and the second Fc domain comprises the amino acid substitutions Y349C, T366S, and Y407V (numbering according to Kabat Ell index).

In some embodiments, a modification promoting association of the first and the second Fc domains comprises a modification mediating electrostatic steering effects, e.g., as described in PCT publication WO 2009/089004. Generally, this method involves replacement of one or more amino acid residues at the interface of the two Fc domains by charged amino acid residues so that homodimer formation becomes electrostatically unfavorable but heterodimerization electrostatically favorable.

In some embodiments, a binding agent comprises one or more scFvs or "single-chain variable fragments". An scFv is a fusion protein of the variable regions of the heavy (VH) and light chain (VL) variable regions of an antibody, connected with a short linker peptide of ten to about 25 amino acids. The linker is usually rich in glycine for flexibility, as well as serine or threonine for solubility, and can either connect the N-terminus of the VH with the C-terminus of the VL, or vice versa. This protein retains the specificity of the original antibody, despite removal of the constant regions and the introduction of the linker. scFv antibodies are described in, e.g., Houston, J. S., Methods in Enzymol. 203 (1991 ) 46-96. Methods for making scFv molecules and designing suitable peptide linkers are described in, e.g., U.S. Pat. No. 4,704,692; U.S. Pat. No. 4,946,778; Raag and Whitlow, FASEB 9:73-80 (1995) and Bird and Walker, TIBTECH, 9: 132-137 (1991 ).

Binding agents that are scFv-Fcs have been described by Sokolowska- Wedzina et al., Mol. Cancer Res. 15(8): 1040-1050, 2017.

In some embodiments, a binding agent is a "bispecific T cell engager" or BiTE (see, e.g., W02004/106381 , W02005/061547, W02007/042261 , and W02008/119567). This approach utilizes two antibody variable domains arranged on a single polypeptide. For example, a single polypeptide chain can include two single chain Fv (scFv) fragments, each having a variable heavy chain (VH) and a variable light chain (VL) domain separated by a polypeptide linker of a length sufficient to allow intramolecular association between the two domains. This single polypeptide further includes a polypeptide spacer sequence between the two scFv fragments. Each scFv recognizes a different epitope, and these epitopes may be specific for different proteins, such that both proteins are bound by the BiTE.

As it is a single polypeptide, the bispecific T cell engager may be expressed using any prokaryotic or eukaryotic cell expression system known in the art, e.g., a CHO cell line. However, specific purification techniques (see, e.g., EP1691833) may be necessary to separate monomeric bispecific T cell engagers from other multimeric species, which may have biological activities other than the intended activity of the monomer. In one exemplary purification scheme, a solution containing secreted polypeptides is first subjected to a metal affinity chromatography, and polypeptides are eluted with a gradient of imidazole concentrations. This eluate is further purified using anion exchange chromatography, and polypeptides are eluted using with a gradient of sodium chloride concentrations. Finally, this eluate is subjected to size exclusion chromatography to separate monomers from multimeric species. In some embodiments, a binding agent that is a bispecific antibody is composed of a single polypeptide chain comprising two single chain FV fragments (scFV) fused to each other by a peptide linker.

A single-domain antibody is an antibody fragment consisting of a single monomeric variable antibody domain. Single domains antibodies can be derived from the variable domain of the antibody heavy chain from camelids (e.g., nanobodies or VHH fragments). Furthermore, the term single-domain antibody includes an autonomous human heavy chain variable domain (aVH) or VNAR fragments derived from sharks (see, e.g., Hasler et al., Mol. Immunol. 75:28-37, 2016). Techniques for producing single domain antibodies (DABs or VHH) are known in the art, as disclosed for example in Cossins et al. (2006, Prot Express Purif 51 :253-259 and Li et al., Immunol. Lett. 188:89-95, 2017). Single domain antibodies may be obtained, for example, from camels, alpacas, or llamas by standard immunization techniques. (See, e.g., Muyldermans et al., TIBS 26:230-235, 2001 ; Yau et al., J Immunol Methods 281 :161-75, 2003; and Maass et al., J Immunol Methods 324:13-25, 2007.) A VHH may have potent antigen-binding capacity and can interact with novel epitopes that are inacessible to conventional VH-VL pairs (see, e.g., Muyldermans et al., 2001 ). Alpaca serum IgG contains about 50% camelid heavy chain only IgG antibodies (HCAbs) (see, e.g., Maass et al., 2007). Alpacas may be immunized with antigens and VHHs can be isolated that bind to and neutralize the target antigen (see, e.g., Maass et al., 2007). PCR primers that amplify alpaca VHH coding sequences have been identified and may be used to construct alpaca VHH phage display libraries, which can be used for antibody fragment isolation by standard biopanning techniques well known in the art (see, e.g., Maass et al., 2007).

In some embodiments, a binding agent is a IgG-scFV. IgG-scFv formats include lgG(H)-scFv, scFv-(H)lgG, lgG(L)-scFv, svFc-(L)lgG, 2scFV-lgG, and IgG- 2scFv. These and other bispecific antibody formats and methods of making them have been described in for example, Brinkmann and Kontermann, MAbs 9(2): 182- 212 (2017); Wang et al., Antibodies, 2019, 8, 43; Dong et al., 2011 , MAbs 3:273-88; Natsume et al., J. Biochem. 140(3):359-368, 2006; Cheal et al., Mol. Cancer Then 13(7): 1803-1812, 2014; and Bates and Power, Antibodies, 2019, 8, 28.

Igg-like dual-variable domain antibodies (DVD-lg) have been described by Wu et al., 2007, Nat Biotechnol 25:1290-97; Hasler et al., Mol. Immunol. 75:28-37, 2016 and in WO 08/024188 and WO 07/024715. Triomabs have been described by Chelius et al., MAbs 2(3):309-319, 2010. 2-in-1-lgGs have been described by Kontermann et al., Drug Discovery Today 20(7):838-847, 2015. Tandem antibody or TandAb have been described by Kontermann et al. (id.). ScFv-HSA-scFv antibodies have also been described by Kontermann et al. (id.).

In some embodiments, the binding agent is a scaffold antigen binding protein, such as for example, fibronectin and designed ankyrin repeat proteins (DARPins), which have been used as alternative scaffolds for antigen-binding domains, see, e.g., Gebauer and Skerra, Engineered protein scaffolds as next-generation antibody therapeutics. Curr Opin Chem Biol 13:245-255 (2009) and Stumpp et al., Darpins: A new generation of protein therapeutics. Drug Discovery Today 13: 695-701 (2008). In some embodiments, a scaffold antigen binding protein is selected from the group consisting of Lipocalins (Anticalin), a Protein A-derived molecule such as Z-domain of Protein A (Affibody), an A-domain (Avimer/Maxibody), a serum transferrin (transbody); a designed ankyrin repeat protein (DARPin), a fibronectin (AdNectin), a C- type lectin domain (Tetranectin); a variable domain of a new antigen receptor betalactamase (VNAR fragments), a human gamma-crystallin or ubiquitin (Affilin molecules); a kunitz type domain of human protease inhibitors, and microbodies such as the proteins from the knottin family, peptide aptamers and fibronectin (adnectin).

Lipocalins are a family of extracellular proteins which transport small hydrophobic molecules such as steroids, bilins, retinoids, and lipids. They have a rigid beta-sheet secondary structure with a number of loops at the open end of the conical structure which can be engineered to bind to different target antigens. Anticalins are between 160-180 amino acids in size, and are derived from lipocalins. For further details, see Biochim Biophys Acta 1482: 337-350 (2000), U.S. Pat. No. 7,250,297B1 , and US20070224633.

Designed Ankyrin Repeat Proteins (DARPins) are derived from Ankyrin which is a family of proteins that mediate attachment of integral membrane proteins to the cytoskeleton. A single ankyrin repeat is a 33-residue motif consisting of two alphahelices and a beta-turn. They can be engineered to bind different target antigens by randomizing residues in the first alpha-helix and a beta-turn of each repeat. Their binding interface can be increased by increasing the number of modules (a method of affinity maturation). For further details, see J. Mol. Biol. 332, 489-503 (2003), PNAS 100(4), 1700-1705 (2003) and J. Mol. Biol. 369, 1015-1028 (2007), and US20040132028A1.

Fc Domain Modifications to Alter Effector Function

In some embodiments, an Fc region or Fc domain has substantially no binding to at least one Fc receptor selected from FcyRI (CD64), FcyRIIA (CD32a), FcyRIIB (CD32b), FcyRIIIA (CD16a), and FcyRIIIB (CD16b). In some embodiments, an Fc region or domain exhibits substantially no binding to any of the Fc receptors selected from FcyRI (CD64), FcyRIIA (CD32a), FcyRIIB (CD32b), FcyRIIIA (CD16a), and FcyRIIIB (CD16b). As used herein, "substantially no binding" refers to weak to no binding to a selected Fcgamma receptor or receptors. In some embodiments, "substantially no binding" refers to a reduction in binding affinity (e.g., increase in Kd) to a Fc gamma receptor of at least 1000-fold. In some embodiments, an Fc domain or region is an Fc null. As used herein, an "Fc null" refers to an Fc region or Fc domain that exhibits weak to no binding to any of the Fcgamma receptors. In some embodiments, an Fc null domain or region exhibits a reduction in binding affinity (e.g., increase in Kd) to Fc gamma receptors of at least 1000-fold.

In some embodiments, an Fc domain has reduced or substantially no effector function activity. As used herein, "effector function activity" refers to antibody dependent cellular cytotoxicity (ADCC), antibody dependent cellular phagocytosis (ADCP) and/or complement dependent cytotoxicity (CDC). In some embodiments, an Fc domain exhibits reduced ADCC, ADCP, or CDC activity, as compared to a wildtype Fc domain. In some embodiments, an Fc domain exhibits a reduction in ADCC, ADCP, and CDC, as compared to a wildtype Fc domain. In some embodiments, an Fc domain exhibits substantially no effector function (i.e., the ability to stimulate ADCC, ADCP, or CDC). As used herein, "substantially no effector function" refers to a reduction in effector function activity of at least 1000-fold, as compared to a wildtype Fc domain.

In some embodiments, an Fc domain has reduced or no ADCC activity. As used herein reduced or no ADCC activity refers to a decrease in ADCC activity of an Fc domain by of a factor of at least 10, at least 20, at least 30, at least 50, at least 100, or at least 500.

In some embodiments, an Fc domain has reduced or no CDC activity. As used herein reduced or no CDC activity refers to a decrease in CDC activity of an Fc domain by of a factor of at least 10, at least 20, at least 30, at least 50, at least 100, or at least 500.

In vitro and/or in vivo cytotoxicity assays can be conducted to confirm the reduction/depletion of ADCC and/or CDC activity. For example, Fc receptor (FcR) binding assays can be conducted to ensure that the antibody lacks Fcgamma receptor (hence likely lacking ADCC activity). The primary cells for mediating ADCC, NK cells, express FcgammaRIII only, whereas monocytes express FcgammaRI, FcgammaRII, and FcgammaRIII. FcR expression on hematopoietic cells is summarized in Table 3 on page 464 of Ravetch and Kinet, Annu. Rev. Immunol. 9:457-492 (1991 ). Non-limiting examples of in vitro assays to assess ADCC activity of a molecule of interest are described in U.S. Pat. No. 5,500,362 (see, e.g., Hellstrom, I. et al. Proc. Nat'l Acad. Sci. USA 83:7059-7063 (1986)) and Hellstrom, I et al., Proc. Nat'l Acad. Sci. USA 82:1499-1502 (1985); U.S. Pat. No. 5,821 ,337 (see Bruggemann, M. et al., J. Exp. Med. 166:1351-1361 (1987)). Alternatively, nonradioactive assays methods may be employed (see, e.g., ACTI™ non-radioactive cytotoxicity assay for flow cytometry (CellTechnology, Inc. Mountain View, Calif.; and CytoTox 96™ non-radioactive cytotoxicity assay (Promega, Madison, Wis.). Useful effector cells for such assays include peripheral blood mononuclear cells (PBMC) and Natural Killer (NK) cells. Alternatively, or additionally, ADCC activity of the molecule of interest may be assessed in vivo, e.g., in an animal model such as that disclosed in Clynes et al., Proc. Nat'l Acad. Sci. USA 95:652-656 (1998). C1q binding assays may also be carried out to confirm that an antibody or Fc domain or region is unable to bind C1q and hence lacks CDC activity or has reduced CDC activity. See, e.g., C1q and C3c binding ELISA in WO 2006/029879 and WO 2005/100402. To assess complement activation, a CDC assay may be performed (see, for example, Gazzano-Santoro et al., J. Immunol. Methods 202:163 (1996); Cragg, M. S. et al., Blood 101 :1045-1052 (2003); and Cragg, M. S. and M. J. Glennie, Blood 103:2738-2743 (2004)).

In some embodiments, an Fc domain has reduced or no ADCP activity. As used herein reduced or no ADCP activity refers to a decrease in ADCP activity of an Fc domain by of a factor of at least 10, at least 20, at least 30, at least 50, at least 100, or at least 500.

ADCP binding assays may also be carried out to confirm that an antibody or Fc domain or region lacks ADCP activity or has reduced ADCP activity. See, e.g., LIS20190079077 and LIS20190048078 and the references disclosed therein.

Antibodies with reduced effector function activity include those with substitution of one or more of Fc region residues 238, 265, 269, 270, 297, 327, and 329 (see U.S. Pat. No. 6,737,056). Such Fc mutants include Fc mutants with substitutions at two or more of amino acid positions 265, 269, 270, 297 and 327, including the so-called "DANA" Fc mutant with substitution of residues 265 and 297 to alanine (see U.S. Pat. No. 7,332,581 ). Certain antibody variants with diminished binding to FcRs are also known. (See, e.g., U.S. Pat. No. 6,737,056; WO 2004/056312, and Shields et al., J. Biol. Chem. 9(2): 6591-6604 (2001 ).)

In certain embodiments, a binding agent comprises an Fc domain or region with one or more amino acid substitutions which diminish FcgammaR binding, e.g., substitutions at positions 234 and 235 of the Fc region (EU numbering of residues). In some embodiments, the substitutions are L234A and L235A (LALA). In some embodiments, the Fc domain further comprises D265A and/or P329G in an Fc region derived from a human lgG1 Fc region. In some embodiments, the substitutions are L234A, L235A, and P329G (LALA-PG) in an Fc region derived from a human lgG1 Fc region. (See, e.g., WO 2012/130831 ). In some embodiments, the substitutions are L234A, L235A, and D265A (LALA-DA) in an Fc region derived from a human lgG1 Fc region. In some embodiments, alterations are made in the Fc region that result in altered (i.e., either diminished) C1q binding and/or Complement Dependent Cytotoxicity (CDC), e.g., as described in U.S. Pat. No. 6,194,551 , WO 99/51642, and Idusogie et al. J. Immunol. 164: 4178-4184 (2000).

Modification of Binding Domains

In some embodiments, a binding domain may be modified by a conservative substitution or substitutions. For conservative amino acid substitutions, a given amino acid can be replaced by a residue having similar physiochemical characteristics, e.g., substituting one aliphatic residue for another (such as lie, Vai, Leu, or Ala for one another), or substitution of one polar residue for another (such as between Lys and Arg; Glu and Asp; or Gin and Asn). Other such conservative amino acid substitutions, e.g., substitutions of entire regions having similar hydrophobicity characteristics, are well known. Polypeptides comprising conservative amino acid substitutions can be tested in any one of the assays described herein to confirm that a desired activity, e.g., antigen-binding activity and specificity of a native or reference polypeptide is retained.

For conservative substitutions, amino acids can be grouped according to similarities in the properties of their side chains (in A. L. Lehninger, in Biochemistry, second ed., pp. 73-75, Worth Publishers, New York (1975)): (1 ) non-polar: Ala (A), Vai (V), Leu (L), lie (I), Pro (P), Phe (F), Trp (W), Met (M); (2) uncharged polar: Gly (G), Ser (S), Thr (T), Cys (C), Tyr (Y), Asn (N), Gin (Q); (3) acidic: Asp (D), Glu (E); and (4) basic: Lys (K), Arg (R), His (H).

Alternatively, for conservative substitutions naturally occurring residues can be divided into groups based on common side-chain properties: (1 ) hydrophobic: Norleucine, Met, Ala, Vai, Leu, lie; (2) neutral hydrophilic: Cys, Ser, Thr, Asn, Gin; (3) acidic: Asp, Glu; (4) basic: His, Lys, Arg; (5) residues that influence chain orientation: Gly, Pro; and (6) aromatic: Trp, Tyr, Phe. Non-conservative substitutions will entail exchanging a member of one of these classes or another class.

Particular conservative substitutions include, for example; Ala to Gly or to Ser; Arg to Lys; Asn to Gin or to His; Asp to Glu; Cys to Ser; Gin to Asn; Glu to Asp; Gly to Ala or to Pro; His to Asn or to Gin; lie to Leu or to Vai; Leu to lie or to Vai; Lys to Arg, to Gin, or to Glu; Met to Leu, to Tyr, or to lie; Phe to Met, to Leu, or to Tyr; Ser to Thr; Thr to Ser; Trp to Tyr; Tyr to Trp; and/or Phe to Vai, to lie, or to Leu.

In some embodiments, a conservatively modified variant of a binding domain preferably is at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or more, identical to the reference VH or VL sequence, wherein the VH and VL CDRs are not modified. The degree of homology (percent identity) between the reference and modified sequence can be determined, for example, by comparing the two sequences using freely available computer programs commonly employed for this purpose on the world wide web (e.g., BLASTp or BLASTn with default settings).

Modification of a native (or reference) amino acid sequence can be accomplished by any of a number of techniques known to one of skill in the art. Mutations can be introduced, for example, at particular sites by synthesizing oligonucleotides containing the desired mutant sequence, flanked by restriction sites enabling ligation to fragments of the native sequence. Following ligation, the resulting reconstructed sequence encodes a variant having the desired amino acid insertion, substitution, or deletion. Alternatively, oligonucleotide-directed site-specific mutagenesis procedures can be employed to provide an altered nucleotide sequence having particular codons altered according to the substitution, deletion, or insertion desired. Techniques for making such alterations are very well established and include, for example, those disclosed by Walder et al. (Gene 42:133, 1986); Bauer et al. (Gene 37:73, 1985); Craik (BioTechniques, January 1985, 12-19); Smith et al. (Genetic Engineering: Principles and Methods, Plenum Press, 1981 ); and U.S. Pat. Nos. 4,518,584 and 4,737,462, which are herein incorporated by reference in their entireties.

CD8+KIR+ Regulatory T Cells

The regulatory T cells are characterized by the phenotype of being CD8+ KIR+ and are typically MHC Class I restricted. In humans, the CD8+Kir+ regulatory T cells express inhibitory KIR proteins. In some embodiments, the KIR proteins expressed by the cells can include one or more of the inhibitory KIR proteins, e.g., KIR2DL1 , KIR2DL2, KIR2DL3, KIR2DL5, KIR3DL1 , and KIR3DL2; and may specifically include one or more of KIR2DL2, KIR2DL3, and KIR3DL1 . In some embodiments, the CD8+KIR+ regulatory T cells are not HLA E (Qa-1 b) restricted. (See, e.g., Lohwasser et al., International Immunology 13:321 -327 (2001 ) and Sarantopoulos et al., J. Clin. Invest. 114(9): 1218-1221 (2004) for a general explanation of murine Qa-1b and human HLA E restriction.) In some embodiments, the CD8+KIR+ regulatory T cells can also be characterized as being CD44+, CD122+, and are not HLA E (Qa-1 b) restricted. In some embodiments, the CD8+KIR+ regulatory T cells can also be characterized as being CD28-. In some embodiments, the CD8+KIR+ regulatory T cells can also be characterized as being CD28-, CD44+, and CD122+. In some embodiments, the CD8+KIR+ regulatory T cells can also be characterized as being CD28-, CD44+, and CD122+ and are not HLA E (Qa-1b) restricted.

In some embodiments, the CD8+KIR+ Tregs express the following antigens: CD3, CD8, PD-1 , CD16, CD122, CD39, CXCR3, ICOS, CD103, and inhibitory KIR proteins.

In some embodiments, CD8+KIR+ Tregs express one or more of the following antigens: CD3, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD103 (ITGAE), CD122, CD166, CD177, CCR7, CXCR3, CXCR5, HLA-DR, ICOS, LAG-3/CD223, OX-40, PD-1 , S1000A8/9, TIM-3, TLT-2, 2B4, and 41 BB. In some embodiments, CD8+KIR+ Tregs express one or more of the following antigens: CD3, CD5, CD16, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD103 (ITGAE), CD122, CD166, CD177, CCR7, CXCR3, CXCR5, HLA-DR, ICOS, KLRB1 , KLRG1 , LAG-3/CD223, NKG2C, NKG2D, OX-40, PD-1 , S1000A8/9, TIM-3, TLT-2, 2B4, and 41 BB. In some embodiments, CD8+KIR+ Tregs express one or more of the following antigens: CD39, KLRB1 , KLRG1 , NKG2C, NKG2D, CXCR3, and CD122.

Production of Binding Agents

In various embodiments, binding agents can be produced in human, murine, or other animal-derived cells lines. Recombinant DNA expression can be used to produce the binding agents. This allows the production of antibodies as well as a spectrum of antigen binding portions and other binding agents (including fusion proteins) in a host species of choice. The production of antibodies, antigen binding portions thereof and other binding agents in bacteria, yeast, transgenic animals, and chicken eggs are also alternatives for cell-based production systems. The main advantages of transgenic animals are potential high yields from renewable sources.

As used herein, the term "nucleic acid" or "nucleic acid sequence" or "polynucleotide sequence" or "nucleotide" refers to a polymeric molecule incorporating units of ribonucleic acid, deoxyribonucleic acid, or an analog thereof. The nucleic acid can be either single-stranded or double-stranded. A singlestranded nucleic acid can be one strand nucleic acid of a denatured double-stranded DNA. In some embodiments, the nucleic acid can be a cDNA, e.g., a nucleic acid lacking introns.

Nucleic acid molecules encoding the amino acid sequence of an antibody, or antigen binding portion thereof, as well as other binding agents can be prepared by a variety of methods known in the art. These methods include, but are not limited to, preparation of synthetic nucleotide sequences encoding of an antibody, antigen binding portion or other binding agent(s). In addition, oligonucleotide-mediated (or site-directed) mutagenesis, PCR-mediated mutagenesis, and cassette mutagenesis can be used to prepare nucleotide sequences encoding an antibody or antigen binding portion as well as other binding agents. A nucleic acid sequence encoding at least an antibody, antigen binding portion thereof, binding agent, or a polypeptide thereof, as described herein, can be recombined with vector DNA in accordance with conventional techniques, such as, for example, blunt-ended or staggered-ended termini for ligation, restriction enzyme digestion to provide appropriate termini, filling in of cohesive ends as appropriate, alkaline phosphatase treatment to avoid undesirable joining, and ligation with appropriate ligases. Techniques for such manipulations are disclosed, e.g., by Maniatis et al., Molecular Cloning, Lab. Manual (Cold Spring Harbor Lab. Press, NY, 1982 and 1989), and Ausubel et al., Current Protocols in Molecular Biology (John Wiley & Sons), 1987-1993, and can be used to construct nucleic acid sequences and vectors that encode an antibody or antigen binding portion thereof or a VH and/or VL polypeptide thereof. Where the binding agent comprises antibodies or antigen binding portions thereof, in some embodiments, a VH polypeptide is encoded by a first nucleic acid. In some embodiments, a VL polypeptide is encoded by a second nucleic acid. In some embodiments, the VH and VL polypeptides are encoded by one nucleic acid.

A nucleic acid molecule, such as DNA, is said to be "capable of expressing" a polypeptide if it contains nucleotide sequences that contain transcriptional and translational regulatory information and such sequences are "operably linked" to nucleotide sequences that encode the polypeptide. An operable linkage is a linkage in which the regulatory DNA sequences and the DNA sequence sought to be expressed (e.g., an antibody or antigen binding portion thereof) are connected in such a way as to permit gene expression of a polypeptide(s) or antigen binding portions in recoverable amounts. The precise nature of the regulatory regions needed for gene expression may vary from organism to organism, as is well known in the analogous art. See, e.g., Sambrook et al., 1989; Ausubel et al., 1987-1993.

Accordingly, the expression of an antibody or antigen-binding portion thereof or other binding agent as described herein can occur in either prokaryotic or eukaryotic cells. Suitable hosts include bacterial or eukaryotic hosts, including yeast, insects, fungi, bird, and mammalian cells either in vivo or in situ, or host cells of mammalian, insect, bird, or yeast origin. The mammalian cell or tissue can be of human, primate, hamster, rabbit, rodent, cow, pig, sheep, horse, goat, dog, or cat origin, but any other mammalian cell may be used. Further, by use of, for example, the yeast ubiquitin hydrolase system, in vivo synthesis of ubiquitin-transmembrane polypeptide fusion proteins can be accomplished. The fusion proteins so produced can be processed in vivo or purified and processed in vitro, allowing synthesis of an antibody or antigen binding portion thereof as described herein with a specified amino terminus sequence. Moreover, problems associated with retention of initiation codon-derived methionine residues in direct yeast (or bacterial) expression may be avoided. (See, e.g., Sabin et al., 7 Bio/Technol. 705 (1989); Miller et al., 7 Bio/Technol. 698 (1989).) Any of a series of yeast gene expression systems incorporating promoter and termination elements from the actively expressed genes coding for glycolytic enzymes produced in large quantities when yeast are grown in medium rich in glucose can be utilized to obtain recombinant antibodies or antigenbinding portions thereof or other binding agents. Known glycolytic genes can also provide very efficient transcriptional control signals. For example, the promoter and terminator signals of the phosphoglycerate kinase gene can be utilized.

Production of antibodies or antigen-binding portions thereof and other binding agents in insects can be achieved, for example, by infecting an insect host with a baculovirus engineered to express a polypeptide by methods known to those of ordinary skill in the art. See Ausubel et al., 1987-1993.

In some embodiments, the introduced nucleic acid sequence (encoding an antibody or antigen binding portion thereof or a polypeptide thereof or other binding agent) is incorporated into a plasmid or viral vector capable of autonomous replication in a recipient host cell. Any of a wide variety of vectors can be employed for this purpose and are known and available to those of ordinary skill in the art. See, e.g., Ausubel et al., 1987-1993. Factors of importance in selecting a particular plasmid or viral vector include: the ease with which recipient cells that contain the vector may be recognized and selected from those recipient cells which do not contain the vector; the number of copies of the vector which are desired in a particular host; and whether it is desirable to be able to "shuttle" the vector between host cells of different species.

Exemplary prokaryotic vectors known in the art include plasmids such as those capable of replication in E. coli. Other gene expression elements useful for the expression of DNA encoding antibodies or antigen-binding portions thereof and other binding agents include, but are not limited to, (a) viral transcription promoters and their enhancer elements, such as the SV40 early promoter, (Okayama et al., 3 Mol. Cell. Biol. 280 (1983)), Rous sarcoma virus LTR (Gorman et al., 79 PNAS 6777 (1982)), and Moloney murine leukemia virus LTR (Grosschedl et al., 41 Cell 885 (1985)); (b) splice regions and polyadenylation sites such as those derived from the SV40 late region (Okayarea et al., 1983), and (c) polyadenylation sites such as in SV40 (Okayama et al., 1983). Immunoglobulin-encoding DNA genes can be expressed as described by Liu et al., infra, and Weidle et al., 51 Gene 21 (1987), using as expression elements the SV40 early promoter and its enhancer, the mouse immunoglobulin H chain promoter enhancers, SV40 late region mRNA splicing, rabbit S-globin intervening sequence, immunoglobulin and rabbit S-globin polyadenylation sites, and SV40 polyadenylation elements. For immunoglobulin encoding nucleotide sequences, the transcriptional promoter can be, for example, human cytomegalovirus, the promoter enhancers can be cytomegalovirus and mouse/human immunoglobulin.

In some embodiments, for expression of DNA coding regions in rodent cells, the transcriptional promoter can be a viral LTR sequence, the transcriptional promoter enhancers can be either or both the mouse immunoglobulin heavy chain enhancer and the viral LTR enhancer, and the polyadenylation and transcription termination regions. In other embodiments, DNA sequences encoding other proteins are combined with the above-recited expression elements to achieve expression of the proteins in mammalian cells.

Each coding region or gene fusion is assembled in, or inserted into, an expression vector. Recipient cells capable of expressing the variable region(s) or antigen binding portions thereof are then transfected singly with nucleotides encoding an antibody or an antibody polypeptide or antigen-binding portion thereof, or are co-transfected with a polynucleotide(s) encoding VH and a VL chain coding regions. The transfected recipient cells are cultured under conditions that permit expression of the incorporated coding regions and the expressed antibody chains or intact antibodies or antigen binding portions are recovered from the culture.

In some embodiments, the nucleic acids containing the coding regions encoding an antibody or antigen-binding portion thereof are assembled in separate expression vectors that are then used to co-transfect a recipient host cell. Each vector can contain one or more selectable genes. For example, in some embodiments, two selectable genes are used, a first selectable gene designed for selection in a bacterial system and a second selectable gene designed for selection in a eukaryotic system, wherein each vector has a set of coding regions. This strategy results in vectors which first direct the production, and permit amplification, of the nucleotide sequences in a bacterial system. The DNA vectors so produced and amplified in a bacterial host are subsequently used to co-transfect a eukaryotic cell, and allow selection of a co-transfected cell carrying the desired transfected nucleic acids (e.g., encoding antibody heavy and light chains). Non-limiting examples of selectable genes for use in a bacterial system are the gene that confers resistance to ampicillin and the gene that confers resistance to chloramphenicol. Selectable genes for use in eukaryotic transfectants include the xanthine guanine phosphoribosyl transferase gene (designated gpt) and the phosphotransferase gene from Tn5 (designated neo). Alternatively, the fused nucleotide sequences encoding VH and VL chains can be assembled on the same expression vector.

For transfection of the expression vectors and production of the antibodies or antigen binding portions thereof or other binding agents, the recipient cell line can be a Chinese Hamster ovary cell line (e.g., DG44) or a myeloma cell. Myeloma cells can synthesize, assemble, and secrete immunoglobulins encoded by transfected immunoglobulin genes and possess the mechanism for glycosylation of the immunoglobulin. For example, in some embodiments, the recipient cell is the recombinant Ig-producing myeloma cell SP2/0. SP2/0 cells only produce immunoglobulins encoded by the transfected genes. Myeloma cells can be grown in culture or in the peritoneal cavity of a mouse, where secreted immunoglobulin can be obtained from ascites fluid.

An expression vector encoding an antibody or antigen-binding portion thereof or other binding agent can be introduced into an appropriate host cell by any of a variety of suitable means, including such biochemical means as transformation, transfection, protoplast fusion, calcium phosphate-precipitation, and application with polycations such as diethylaminoethyl (DEAE) dextran, and such mechanical means as electroporation, direct microinjection and microprojectile bombardment. Johnston et al., 240 Science 1538 (1988), as known to one of ordinary skill in the art.

Yeast provides certain advantages over bacteria for the production of immunoglobulin heavy and light chains. Yeasts carry out post-translational peptide modifications including glycosylation. A number of recombinant DNA strategies exist that utilize strong promoter sequences and high copy number plasmids which can be used for production of the desired proteins in yeast. Yeast recognizes leader sequences of cloned mammalian gene products and secretes polypeptides bearing leader sequences (i.e., pre-polypeptides). See, e.g., Hitzman et al., 11th Inti. Conf. Yeast, Genetics & Molec. Biol. (Montpelier, France, 1982).

Yeast gene expression systems can be routinely evaluated for the levels of production, secretion and the stability of antibodies, and assembled antibodies and antigen binding portions thereof. Various yeast gene expression systems incorporating promoter and termination elements from the actively expressed genes coding for glycolytic enzymes produced in large quantities when yeasts are grown in media rich in glucose can be utilized. Known glycolytic genes can also provide very efficient transcription control signals. For example, the promoter and terminator signals of the phosphoglycerate kinase (PGK) gene can be utilized. Another example is the translational elongation factor 1 alpha promoter. A number of approaches can be taken for evaluating optimal expression plasmids for the expression of immunoglobulins in yeast. See, e.g., II DNA Cloning 45, (Glover, ed., IRL Press, 1985) and U.S. Publication No. US 2006/0270045 A1 .

Bacterial strains can also be utilized as hosts for the production of the antibody molecules or antigen binding portions thereof or other binding agents described herein. E. coli K12 strains such as E. coli W3110, Bacillus species, enterobacteria such as Salmonella typhimurium or Serratia marcescens, and various Pseudomonas species can be used. Plasmid vectors containing replicon and control sequences which are derived from species compatible with a host cell are used in connection with these bacterial hosts. The vector carries a replication site, as well as specific genes which are capable of providing phenotypic selection in transformed cells. A number of approaches can be taken for evaluating the expression plasmids for the production of antibodies and antigen binding portions thereof in bacteria (see Glover, 1985; Ausubel, 1987, 1993; Sambrook, 1989; Colligan, 1992-1996).

Host mammalian cells can be grown in vitro or in vivo. Mammalian cells provide post-translational modifications to immunoglobulin molecules including leader peptide removal, folding and assembly of VH and VL chains, glycosylation of the antibody molecules, and secretion of functional antibody and/or antigen binding portions thereof.

Mammalian cells which can be useful as hosts for the production of antibody proteins, in addition to the cells of lymphoid origin described above, include cells of fibroblast origin, such as Vero or CHO-K1 cells. Exemplary eukaryotic cells that can be used to express immunoglobulin polypeptides include, but are not limited to, COS cells, including COS 7 cells; 293 cells, including 293-6E cells; CHO cells, including CHO-S, CHO-K1 and DG44 cells; PERC6™ cells (Crucell); and NSO cells. In some embodiments, a particular eukaryotic host cell is selected based on its ability to make desired post-translational modifications to the heavy chains and/or light chains. For example, in some embodiments, CHO cells produce polypeptides that have a higher level of sialylation than the same polypeptide produced in 293 cells.

In some embodiments, one or more antibodies or antigen-binding portions thereof or other binding agents can be produced in vivo in an animal that has been engineered or transfected with one or more nucleic acid molecules encoding the polypeptides, according to any suitable method.

In some embodiments, an antibody or antigen-binding portion thereof is produced in a cell-free system. Non-limiting exemplary cell-free systems are described, e.g., in Sitaraman et al., Methods Mol. Biol. 498: 229-44 (2009); Spirin, Trends Biotechnol. 22: 538-45 (2004); and Endo et al., Biotechnol. Adv. 21 : 695-713 (2003).

Many vector systems are available for the expression of the VH and VL chains in mammalian cells (see Glover, 1985). Various approaches can be followed to obtain intact antibodies. As discussed above, it is possible to co-express VH and VL chains and optionally the associated constant regions in the same cells to achieve intracellular association and linkage of VH and VL chains into complete tetrameric H2L2 antibodies or antigen-binding portions thereof. The co-expression can occur by using either the same or different plasmids in the same host. Nucleic acids encoding the VH and VL chains or antigen binding portions thereof can be placed into the same plasmid, which is then transfected into cells, thereby selecting directly for cells that express both chains. Alternatively, cells can be transfected first with a plasmid encoding one chain, for example the VL chain, followed by transfection of the resulting cell line with a VH chain plasmid containing a second selectable marker. Cell lines producing antibodies, antigen-binding portions thereof or other binding agents via either route could be transfected with plasmids encoding additional copies of peptides, VH, VL, or VH plus VL chains in conjunction with additional selectable markers to generate cell lines with enhanced properties, such as higher production of assembled antibodies or antigen binding portions thereof or enhanced stability of the transfected cell lines.

Additionally, plants have emerged as a convenient, safe and economical alternative expression system for recombinant antibody production, which are based on large scale culture of microbes or animal cells. Antibodies or antigen binding portions can be expressed in plant cell culture, or plants grown conventionally. The expression in plants may be systemic, limited to sub-cellular plastids, or limited to seeds (endosperms). See, e.g., U.S. Patent Pub. No. 2003/0167531 ; U.S. Pat. No. 6,080,560; U.S. Pat. No. 6,512,162; and WO 0129242. Several plant-derived antibodies have reached advanced stages of development, including clinical trials (see, e.g., Biolex, N.C.).

For intact antibodies, the variable regions (VH and VL) of the antibodies are typically linked to at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin. Human constant region DNA sequences can be isolated in accordance with well-known procedures from a variety of human cells, such as immortalized B-cells (see, e.g., WO 87/02671 ; which is incorporated by reference herein in its entirety). An antibody can contain both light chain and heavy chain constant regions. The heavy chain constant region can include CH1 , hinge, CH2, CH3, and, sometimes, CH4 regions. In some embodiments, the CH2 domain can be deleted or omitted.

Alternatively, techniques described for the production of single chain antibodies (see, e.g., U.S. Pat. No. 4,946,778; Bird, Science 242:423-42 (1988); Huston et al., Proc. Natl. Acad. Sci. USA 85:5879-5883 (1988); and Ward et al., Nature 334:544-54 (1989); which are incorporated by reference herein in their entireties) can be adapted to produce single chain antibodies that specifically bind to the desired antigen. Single chain antibodies are formed by linking the heavy and light chain variable regions of the Fv region via an amino acid bridge, resulting in a single chain polypeptide. Techniques for the assembly of functional Fv fragments in E. coli can also be used (see, e.g., Skerra et al., Science 242:1038-1041 (1988); which is incorporated by reference herein in its entirety). Method of making other binding agents are described supra.

Intact (e.g., whole) antibodies, their dimers, individual light and heavy chains, or antigen binding portions thereof can be recovered and purified by known techniques, e.g., immunoadsorption or immunoaffinity chromatography, chromatographic methods such as HPLC (high performance liquid chromatography), ammonium sulfate precipitation, gel electrophoresis, or any combination of these. See generally, Scopes, Protein Purification (Springer-Verlag, N.Y., 1982). Substantially pure antibodies or antigen binding portions thereof of at least about 90% to 95% homogeneity are advantageous, as are those with 98% to 99% or more homogeneity, particularly for pharmaceutical uses. Once purified, partially or to homogeneity as desired, an intact antibody or antigen binding portions thereof can then be used therapeutically or in developing and performing assay procedures, immunofluorescent staining, and the like. See generally, Vols. I & II Immunol. Meth. (Lefkovits & Pernis, eds., Acad. Press, NY, 1979 and 1981).

Pharmaceutical Formulations

In some aspects the binding agents relate to compositions comprising active ingredients (i.e. , including a binding agent as described herein or a nucleic acid encoding an antibody or antigen-binding portion thereof or other binding agent as described herein). In some embodiments, the composition is a pharmaceutical composition. As used herein, the term "pharmaceutical composition" refers to the active agent in combination with a pharmaceutically acceptable carrier accepted for use in the pharmaceutical industry. The phrase "pharmaceutically acceptable" is employed herein to refer to those compounds, materials, compositions, and/or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit/risk ratio.

The preparation of a pharmacological composition that contains active ingredients dissolved or dispersed therein is well understood in the art and need not be limited based on any particular formulation. Typically such compositions are prepared as injectable either as liquid solutions or suspensions; however, solid forms suitable for rehydration, or suspensions, in liquid prior to use can also be prepared. A preparation can also be emulsified or presented as a liposome composition. An antibody or antigen binding portion thereof or other binding agent can be mixed with excipients that are pharmaceutically acceptable and compatible with the active ingredient and in amounts suitable for use in the therapeutic methods described herein. Suitable excipients are, for example, water, saline, dextrose, glycerol, ethanol or the like and combinations thereof. In addition, if desired, a pharmaceutical composition can contain minor amounts of auxiliary substances such as wetting or emulsifying agents, pH buffering agents and the like which enhance or maintain the effectiveness of the active ingredient (e.g., an antibody or antigen binding portion thereof or other binding agent). The pharmaceutical compositions as described herein can include pharmaceutically acceptable salts of the components therein. Pharmaceutically acceptable salts include the acid addition salts (formed with the free amino groups of a polypeptide) that are formed with inorganic acids such as, for example, hydrochloric or phosphoric acids, or such organic acids as acetic, tartaric, mandelic, and the like. Salts formed with the free carboxyl groups can also be derived from inorganic bases such as, for example, sodium, potassium, ammonium, calcium or ferric hydroxides, and such organic bases as isopropylamine, trimethylamine, 2-ethylamino ethanol, histidine, procaine, and the like.

Physiologically tolerable carriers are well known in the art. Exemplary liquid carriers are sterile aqueous solutions that contain the active ingredients (e.g., an antibody and/or antigen binding portions thereof or other binding agent) and water, and may contain a buffer such as sodium phosphate at physiological pH value, physiological saline or both, such as phosphate-buffered saline. Still further, aqueous carriers can contain more than one buffer salt, as well as salts such as sodium and potassium chlorides, dextrose, polyethylene glycol and other solutes. Liquid compositions can also contain liquid phases in addition to and to the exclusion of water. Exemplary of such additional liquid phases are glycerin, vegetable oils such as cottonseed oil, and water-oil emulsions. The amount of an active agent that will be effective in the treatment of a particular disorder or condition will depend on the nature of the disorder or condition, and can be determined by standard clinical techniques.

In some embodiments, a pharmaceutical composition comprising an antibody or antigen-binding portion thereof or other binding agent or a nucleic acid encoding an antibody or antigen-binding portion thereof or other binding agent as described herein can be a lyophilisate.

In some embodiments, a syringe comprising a therapeutically effective amount of a binding agent, or a pharmaceutical composition described herein is provided. Methods of Suppressing, Reducing, or Preventing an Immune Response to a Virus, such as an Immune Response Induced by Administration of a Viral Vector

In some aspects, the binding agents as described herein can be used in a method(s) comprising administering a binding agent or a pharmaceutical composition as described herein to a subject having an immune response to a virus, such as an immune response induced by administration of a viral vector. In some embodiments, the subject is in need of treatment with the viral vector. In some embodiments, provided are methods of suppressing, reducing, or preventing an immune response induced by administration of a viral vector, comprising administering any of the binding agents described herein or the pharmaceutical compositions described herein, to a subject in need thereof.

As used herein, "an immune response to a virus" or "an immune response to a viral vector" may refer to any immune response to a virus, a viral vector, or antigenic portions thereof, e.g., viral proteins or fragments thereof. In some embodiments, the immune response may be activation or proliferation of CD4+ T cells. The immune response may be characterized by, for example, pro- inflammatory cytokine (e.g., IFN-y) production by CD4+ T cells.

As used herein, to "activate or stimulate" CD8+KIR+ Tregs, or activated CD8+KIR+ Tregs, refers to an increase of the regulatory T cell functions of such cells, such as the ability to suppress an immune response. Activation or stimulation of CD8+KIR+ Tregs may include removal of a suppressive effect on such cells, so as to restore the CD8+KIR+ Tregs (e.g., restore balance to the immune system or restore balanced immune activity in the subject prior to receiving the viral vector). Activation or stimulation of CD8+KIR+ Tregs may also include results of such activation or stimulation, including removal of CD4+ cells, B cells, or other cells mediating an immune response, such as by elimination, for example, cytolysis, of such cells.

In some embodiments, the CD8+KIR+ Tregs are contacted with the binding agent in vivo. In some embodiments, the CD8+KIR+ Tregs are contacted with the binding agent ex vivo. The activated CD8+KIR+ Tregs can then be administered in an effective amount to a subject in need thereof. In some embodiments, the activated CD8+KIR+ Tregs exert a suppressive effect on other immune cells, such as CD4+ T cells, antibody producing B cells, antigen presenting dendritic cells, or antigen presenting cells. In some embodiments, the activated CD8+KIR+ Tregs exert a suppressive effect on other immune cells, such as CD4+ T cells, antibody producing B cells, and antigen presenting dendritic cells. In some embodiments, the activated CD8+KIR+ Tregs deplete other immune cells, such as CD4 T cells, antibody producing B cells, and antigen presenting dendritic cells. In some embodiments, the activated CD8+KIR+ Tregs modulate the activity of undesired immune cells and decrease the titer of antibodies in the subject. In some embodiments, the activated CD8+KIR+ Tregs decrease the titer of antibodies in the subject.

In some embodiments, the binding agent is selected from any of the binding agents described herein, in each case that has reduced effector function activity or has substantially no effector function activity. In some embodiments, the reduced effector function activity is reduced or no ADCC, ADCP, or CDC effector function activity. In some embodiments, having substantially no effector function activity means having substantially no ADCC, ADCP, and CDC effector function activity. In some embodiments, a binding agent lacks an Fc domain or region and has reduced effector function or substantially no effector function. In some embodiments, a binding agent has an Fc domain or region with reduced effector function or substantially no effector function due to amino acid substitutions in the Fc domain or region. In some embodiments, a binding agent has an Fc domain or region with reduced effector function or substantially no effector function due to amino acid substitutions in the Fc domain or region, such as Fc null substitutions. In some embodiments, a binding agent lacks an Fc domain or region or has an Fc domain or region with reduced binding to one or more Fcgamma receptors or is an Fc null domain. In some embodiments, a binding agent lacks an Fc domain or region. In some embodiments, a binding agent has an Fc domain or region with reduced binding to one or more Fcgamma receptors or is an Fc null domain. In some embodiments, a binding agent has an Fc domain or region with reduced binding to one or more Fcgamma receptors due to amino acid substitutions in the Fc domain or region. Without intending to be bound by any particular theory, the reduction or absence of effector function activity by a binding agent may limit the interaction of the binding agent with other cell types (i.e. , non-CD8+KIR+ Tregs) and/or limit depletion of the CD8+KIR+ Tregs bound by the binding agent.

The methods described herein include administering a therapeutically effective amount of a binding agent to a subject. As used herein, the phrases "therapeutically effective amount", "amount effective", "effective amount", and "effective dose" refer to an amount of the binding agent as described herein that provides a therapeutic benefit in the treatment of, management of, prevention of relapse, or delay of or prevention of onset of, a disease, e.g., an amount that provides a statistically significant decrease in at least one symptom, sign, or marker of a disease. Determination of a therapeutically effective amount is well within the capability of those skilled in the art. Generally, a therapeutically effective amount can vary with the subject's history, age, condition, and sex, as well as the severity and type of the medical condition in the subject, and administration of other pharmaceutically active agents.

It is contemplated that the methods herein reduce symptoms, pathology, disease progression, or disease flares in a subject. As used herein, a "subject" refers to a human or animal. Usually the animal is a vertebrate such as a primate, rodent, domestic animal, or game animal. Primates include chimpanzees, cynomolgus monkeys, spider monkeys, and macaques, e.g., Rhesus. Rodents include mice, rats, woodchucks, ferrets, rabbits, and hamsters. Domestic and game animals include cows, horses, pigs, deer, bison, buffalo, feline species, e.g., domestic cat, canine species, e.g., dog, fox, wolf, avian species, e.g., chicken, emu, ostrich, and fish, e.g., trout, catfish, and salmon. In certain embodiments, the subject is a mammal, e.g., a primate, e.g., a human. The terms, "patient", "individual", and "subject" are used interchangeably herein.

Preferably, the subject is a mammal. The mammal can be a human, nonhuman primate, mouse, rat, dog, cat, horse, or cow, but is not limited to these examples. Mammals other than humans can be advantageously used, for example, as subjects that represent animal models of, for example, various autoimmune diseases. In addition, the methods described herein can be used to treat domesticated animals and/or pets. A subject can be male or female. In certain embodiments, the subject is a human.

A subject can be one who has been previously diagnosed with or identified as suffering from a disease and in need of treatment. Alternatively, a subject can also be one who has not been previously diagnosed as having a disease in need of treatment. A subject can be one who exhibits one or more risk factors for a condition or one or more complications related to a disease who does not exhibit risk factors. A "subject in need" of treatment for a disease can be a subject having that disease or diagnosed as having that disease.

As used herein, the terms "treat", "treatment", "treating", or "amelioration" when used in reference to a disease, disorder, or medical condition, refer to therapeutic treatments for a condition, wherein the object is to reverse, alleviate, ameliorate, inhibit, slow down, or stop the progression or severity of a symptom or condition. The term "treating" includes reducing or alleviating at least one adverse effect or symptom of a condition or disease. Treatment is generally "effective" if one or more symptoms or clinical markers are reduced. Alternatively, treatment is "effective" if the progression of a condition is reduced or halted. That is, "treatment" may include not just the improvement of symptoms or markers, but also a cessation or at least slowing of progress or worsening of symptoms that would be expected in the absence of treatment. Beneficial or desired clinical results include, but are not limited to, reduction in one or more symptoms, reducing disease flares in the subject, alleviation of one or more symptom(s), diminishment of extent of the deficit, stabilized (i.e. , not worsening) state of a disease, or a prevention, delay, or slowing of onset or progression of the disease. As used herein, the term "administering," refers to contacting a binding agent as described herein or a nucleic acid encoding the binding agent as described herein (e.g., by administration to a subject) by a method or route which results in binding of the binding agent to the CD8+KIR+ Tregs. Similarly, a pharmaceutical composition comprising a binding agent as described herein or a nucleic acid encoding the binding agent as described herein disclosed herein can be administered by any appropriate route which results in an effective treatment in the subject. The dosage ranges for a binding agent depend upon the potency, and encompass amounts large enough to produce the desired effect e.g., reduction in one or more symptoms, reducing disease flares in the subject, alleviation of one or more symptom(s), diminishment of extent of the deficit, stabilized (i.e. , not worsening) state of a disease, or a prevention, delay, or slowing of onset or progression of a disease. The dosage should not be so large as to cause unacceptable adverse side effects. Generally, the dosage will vary with the age, condition, and sex of the subject and can be determined by one of skill in the art. The dosage can also be adjusted by the individual physician in the event of any complication. In some embodiments, the dosage ranges from about 0.01 mg/kg body weight to about 20 mg/kg body weight. In some embodiments, the dosage ranges from about 0.5 mg/kg body weight to about 15 mg/kg body weight. In some embodiments, the dose range is from about 0.5 mg/kg body weight to about 5 mg/kg body weight. Alternatively, the dose range can be titrated to maintain serum levels between 1 ug/mL and 1000 ug/mL.

In some embodiments, a subject receives a single dose of any of the binding agents described herein, such as for the suppression or reduction of an immune response induced by administration of a viral vector. In some embodiments, a subject receives a single dose of any of the binding agents described herein, such as for prevention of an immune response induced by administration of a viral vector. In some embodiments, a subject receives repeated doses of any of the binding agents described herein, such as for reduction of an immune response induced by administration of a viral vector. In some embodiments, a subject receives repeated doses of any of the binding agents described herein, such as for prevention of an immune response induced by administration of a viral vector. In some embodiments, the doses are administered weekly, biweekly, every three weeks, monthly, bimonthly, or every 6 months for several weeks, months, or years. The duration of treatment depends upon the subject's clinical progress and responsiveness to treatment.

In some embodiments, a dose can be administered intravenously. In some embodiments, an intravenous administration can be an infusion occurring over a period of from about 10 minutes to about 4 hours. In some embodiments, an intravenous administration can be an infusion occurring over a period of from about 30 minutes to about 90 minutes. In some embodiments, a dose can be administered subcutaneously.

Pharmaceutical compositions containing any of the binding agents described herein can be administered in a unit dose. The term "unit dose" when used in reference to a pharmaceutical composition refers to physically discrete units suitable as unitary dosage for the subject, each unit containing a predetermined quantity of active material (e.g., a binding agent), calculated to produce the desired therapeutic effect in association with the required physiologically acceptable diluent, i.e. , carrier, or vehicle.

In some embodiments, administration of any of the binding agents described herein can result in an improved treatment outcome, alleviation of one or more symptom(s), and/or prevention, delay, or slowing of onset or progression of a disease.

In some embodiments, the present disclosure provides a binding agent as described herein for use in suppressing, reducing, or preventing an immune response to a virus in a subject, such as an immune response induced by administration of a viral vector.

In some embodiments, the present disclosure provides for the use of a binding agent as described herein for suppressing, reducing, or preventing an immune response to a virus, such as an immune response induced by administration of a viral vector.

In some embodiments, the present disclosure provides for the coadministration of a binding agent as described herein with a viral vector. In some embodiments, the present disclosure provides for the administration of a binding agent as described herein before or after administration of a viral vector.

Also provided by the present disclosure are uses of the binding agents or pharmaceutical compositions described herein in the manufacture of a medicament for suppressing, reducing, or preventing an immune response to a virus, such as an immune response induced by administration of a viral vector.

In some embodiments, a binding agent or a pharmaceutical composition of any of the binding agents described herein, is administered with an immunosuppressive agent, such as a corticosteroid(s). In some embodiments, the immunosuppressive agent is one or more of: a calcineurin inhibitor, e.g., a cyclosporin or an ascomycin, e.g., cyclosporin A (NEORAL®), FK506 (tacrolimus), pimecrolimus, an mTOR inhibitor, e.g., rapamycin or a derivative thereof, e.g., sirolimus (RAPAMUNE®), everolimus (Certican®), temsirolimus, zotarolimus, biolimus-7, biolimus-9, a rapalog, e.g., ridaforolimus, azathioprine, campath 1 H, a S1 P receptor modulator, e.g., fingolimod or an analogue thereof, an anti-IL-8 antibody, mycophenolic acid or a salt thereof, e.g., sodium salt, e.g., mycophenolate mofetil (CELLCEPT®), OKT3 (ORTHOCLONE OKT3®), Prednisone, ATGAM®, THYMOGLOBULIN®, Brequinar Sodium, OKT4, T10B9.A-3A, 33B3.1 , 15- deoxyspergualine, tresperimus, leflunomide ARAVA®, CTLAI-lg, anti-CD25, anti- IL2R , basiliximab (SIMULECT®), Daclizumab (ZENAPAX®), mizorbine, methotrexate, dexamethasone, ISAtx-247, SDZ ASM 981 (pimec rolimus, Elidel®), CTLA4lg (Abatacept), belatacept, LFA3lg, etanercept (sold as Enbrel® by Immunex), adalimumab (Humira®), infliximab (Remicade®), an anti-LFA-1 antibody, natalizumab (Antegren®), Enlimomab, gavilimomab, antithymocyte immunoglobulin, siplizumab, alefacept efalizumab, rituximab, pentase, mesalazine, asacol, codeine phosphate, benorylate, fenbufen, naprosin, diclofenac, etodolac, and indomethacin, tocilizumab (Actemra), siltuximab (Sylvant), secukibumab (Cosentyx), ustekinumab (Stelara), risankizumab, sifalimumab, aspirin, ibuprofen, imlifidase, a proteasome inhibitor, arsenic trioxide, and rabbit anti-thymocyte globulin. See, e.g., Chu et al., Frontiers in Immunology 2021 12:658038.

In some embodiments, a binding agent or a pharmaceutical composition of any of the binding agents described herein, is administered with an anti-inflammatory agent, such as a corticosteroid(s). In some embodiments, the anti-inflammatory agent is one or more of: methotrexate, dexamethasone, dexamethasone alcohol, dexamethasone sodium phosphate, fluromethalone acetate, fluromethalone alcohol, lotoprendol etabonate, medrisone, prednisolone acetate, prednisolone sodium phosphate, difluprednate, rimexolone, hydrocortisone, hydrocortisone, lodoxamide tromethamine, aspirin, ibuprofen, suprofen, piroxicam, meloxicam, flubiprofen, naproxan, ketoprofen, tenoxicam, diclofenac sodium, ketotifen fumarate, diclofenac sodium, nepafenac, bromfenac, flurbiprofen sodium, suprofen, celecoxib, naproxen, rofecoxib, glucocorticoids, diclofenac, and any combination thereof. In some embodiments, the anti-inflammatory agent is one or more nonsteroidal antiinflammatory drugs (NSAIDs), such as naproxen sodium (Anaprox), celecoxib (Celebrex), sulindac (Clinoril), oxaprozin (Daypro ), salsalate (Disalcid), diflunisal (Dolobid), piroxicam (Feldene), indomethacin (Indocin), etodolac (Lodine), meloxicam (Mobic), naproxen (Naprosyn), nabumetone (Relafen), ketorolac tromethamine (Toradol), naproxen/ esomeprazole (Vimovo), and diclofenac (Voltaren), and combinations thereof.

Exemplary Embodiments

The present invention is further illustrated by the following embodiments which should not be construed as limiting.

1 . A binding agent that binds to CD8+KIR+ T regulatory cells (Tregs) for use in a method of modulating an immune response to a virus in a subject.

2. A binding agent that binds to CD8+KIR+ T regulatory cells (Tregs) for use in a method of suppressing or reducing an immune response to a virus in a subject.

3. A binding agent that binds to CD8+KIR+ T regulatory cells (Tregs) for use in a method of preventing an immune response to a virus in a subject.

4. A method of modulating an immune response to a virus in a subject, the method comprising administering to the subject a binding agent that binds to CD8+KIR+ T regulatory cells (Tregs).

5. A method of suppressing or reducing an immune response to a virus in a subject, the method comprising administering to the subject a binding agent that binds to CD8+KIR+ T regulatory cells (Tregs).

6. A method of preventing an immune response to a virus in a subject, the method comprising administering to the subject a binding agent that binds to CD8+KIR+ T regulatory cells (Tregs).

7. The use of a binding agent that binds to CD8+KIR+ T regulatory cells (Tregs) in the manufacture of a medicament for modulating an immune response to a virus in a subject. 8. The use of a binding agent that binds to CD8+KIR+ T regulatory cells (Tregs) in the manufacture of a medicament for suppressing or reducing an immune response to a virus in a subject.

9. The use of a binding agent that binds to CD8+KIR+ T regulatory cells (Tregs) in the manufacture of a medicament for preventing an immune response to a virus in a subject.

10. A pharmaceutical composition comprising a binding agent that binds to CD8+KIR+ T regulatory cells (Tregs) and a pharmaceutically acceptable carrier, for use in a method of modulating an immune response to a virus in a subject.

11 . A pharmaceutical composition comprising a binding agent that binds to CD8+KIR+ T regulatory cells (Tregs) and a pharmaceutically acceptable carrier, for use in a method of suppressing or reducing an immune response to a virus in a subject.

12. A pharmaceutical composition comprising a binding agent that binds to CD8+KIR+ T regulatory cells (Tregs) and a pharmaceutically acceptable carrier, for use in a method of preventing an immune response to a virus in a subject.

13. A method of modulating an immune response to a virus in a subject, the method comprising administering to the subject a pharmaceutical composition comprising a binding agent that binds to CD8+KIR+ T regulatory cells (Tregs) and a pharmaceutically acceptable carrier.

14. A method of suppressing or reducing an immune response to a virus in a subject, the method comprising administering to the subject a pharmaceutical composition comprising a binding agent that binds to CD8+KIR+ T regulatory cells (Tregs) and a pharmaceutically acceptable carrier.

15. A method of preventing an immune response to a virus in a subject, the method comprising administering to the subject a pharmaceutical composition comprising a binding agent that binds to CD8+KIR+ T regulatory cells (Tregs) and a pharmaceutically acceptable carrier.

16. The use of a pharmaceutical composition, comprising a binding agent that binds to CD8+KIR+ T regulatory cells (Tregs) and a pharmaceutically acceptable carrier, in the manufacture of a medicament for modulating an immune response to a virus in a subject. 17. The use of a pharmaceutical composition, comprising a binding agent that binds to CD8+KIR+ T regulatory cells (Tregs) and a pharmaceutically acceptable carrier, in the manufacture of a medicament for suppressing or reducing an immune response to a virus in a subject.

18. The use of a pharmaceutical composition, comprising a binding agent that binds to CD8+KIR+ T regulatory cells (Tregs) and a pharmaceutically acceptable carrier, in the manufacture of a medicament for preventing an immune response to a virus in a subject.

19. The composition, method, or use of any one of the preceding embodiments, wherein the virus is a viral vector.

20. The composition, method, or use of embodiment 19, wherein the viral vector has been, is, or will be administered to the subject.

21 . The composition, method, or use of embodiment 19 or embodiment 20, wherein the immune response to the viral vector is induced by administration of a viral vector to the subject.

22. The composition, method, or use of any one of the preceding embodiments, wherein the binding agent comprises:

(a) a first binding domain that specifically binds to a first antigen, the first antigen selected from antigens expressed on CD8+KIR+ Tregs other than a KIR protein; and

(b) a second binding domain that specifically binds to an inhibitory KIR protein.

23. The composition, method, or use of embodiment 22, wherein the first antigen is selected from the group consisting of CD3, CD5, CD8, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD103 (ITGAE), CD122, CD166, CD177, CCR7, CXCR3, CXCR5, HLA-DR, ICOS, LAG-3/CD223, OX-40, PD-1 , S1000A8/9, TIM-3, TLT-2, 2B4, and 41 BB.

24. The composition, method, or use of embodiment 22 or embodiment 23, wherein the first antigen is CD3, CD8, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD103 (ITGAE), CD122, CD166, CD177, CCR7, CXCR3, CXCR5, HLA-DR, ICOS, LAG-3/CD223, OX-40, PD-1 , S1000A8/9, TIM-3, TLT-2, 2B4, or 41 BB. 25. The composition, method, or use of any one of embodiments 22-24, wherein the first antigen is selected from the following groups of antigens: a. CD3, CD5, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD122, ICOS, OX-40, 2B4, 41 BB, and HLA-DR; b. LAG-3/CD223, TIM-3, PD-1 , S1000A8/9, and TLT2; c. CD3, CD5, CD8, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD103 (ITGAE), CD122, CD166, CD177, CCR7, CXCR3, CXCR5, HLA-DR, ICOS, LAG-3/CD223, OX-40, PD-1 , S1000A8/9, TIM-3, TLT-2, 2B4, and 41 BB; d. CD103 (ITGAE), CD166, CD177, CXCR3, and S1000A8/9; e. CCR7, CXCR3, and CXCR5; f. PD-1 , ICOS, and CXCR3; g. CD3, CD5, and CD8; and h. CD3 and CD8.

26. The composition, method, or use of any one of embodiments 22-25, wherein the first antigen is selected from the following groups of antigens: a. CD3, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD122, ICOS, OX-40, 2B4, 41 BB, and HLA-DR; b. LAG-3/CD223, TIM-3, PD-1 , S1000A8/9, and TLT2; c. CD3, CD8, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD103 (ITGAE), CD122, CD166, CD177, CCR7, CXCR3, CXCR5, HLA-DR, ICOS, LAG-3/CD223, OX-40, PD-1 , S1000A8/9, TIM-3, TLT-2, 2B4, and 41 BB; d. CD103 (ITGAE), CD166, CD177, CXCR3, and S1000A8/9; e. CCR7, CXCR3, and CXCR5; and f. CD3 and CD8.

27. The composition, method, or use of any one of the preceding embodiments, wherein the binding agent is a bispecific antibody, a diabody, an antibody Fc fusion, an scFv1-ScFv2, an SCFV12-FC-SCFV22, an IgG-scFv, a DVD-lg, a triomab/quadroma, a two-in-one IgG, a scFv2-Fc, a TandAb, an scFv-HSA-scFv, an scFv-VHH, a Fab-scFv-Fc, a Fab-VHH-Fc, a dAb-IgG, an IgG-VHH, a Tandem scFv-Fc, a (SCFV1 )2-FC-(VHH)2, a BiTe, a DART, an anticalin, an affibody, an avimer, a DARPin, an adnectin, a CrossMab, a scFv-Fc, a one-armed tandem scFv-Fc, or a DART-Fc.

28. The composition, method, or use of any one of embodiments 22-27, wherein either the first or second binding domain is selected from an antibody or antigen binding portion thereof, and the other binding domain is an antibody fragment.

29. The composition, method, or use of embodiment 28, wherein the antigen binding portion is a Fab, Fab', F(ab')2, Fv, scFv, or a single domain antibody, such as a VHH, VNAR, sdAb, or nanobody.

30. The composition, method, or use of any one of embodiments 22-29, wherein the first binding domain comprises a heavy chain variable region and a light chain variable region.

31 . The composition, method, or use of any one of embodiments 22-30, wherein the second binding domain comprises a heavy chain variable region and a light chain variable region.

32. The composition, method, or use of any one of embodiments 22-31 , wherein the first binding domain specifically binds to CD8 or a subunit of CD8, optionally CD8alpha.

33. The composition, method, or use of embodiment 32, wherein the first binding domain comprises a heavy chain variable region (VH) and a light chain variable region (VL), the VH and VL regions having amino acid sequences selected from the pairs of amino acid sequences set forth in the group consisting of: a. SEQ ID NO:81 and SEQ ID NO:82, respectively; and b. SEQ ID NO:73 and SEQ ID NO:74, respectively; or the first binding domain comprises a VHH chain, the VHH chain having the amino acid sequence selected from the amino acid sequences set forth in the group consisting of: c. SEQ ID NO:89; d. SEQ ID NO:93; and e. SEQ ID NO:97.

34. The composition, method, or use of embodiment 32, wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO:81 and a light chain variable region (VL) having the amino acid sequence set forth in SEQ ID NO:82.

35. The composition, method, or use of embodiment 32, wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO:73 and a light chain variable region (VL) having the amino acid sequence set forth in SEQ ID NO:74.

36. The composition, method, or use of embodiment 32, wherein the first binding domain comprises a VHH chain having the amino acid sequence set forth in SEQ ID NO:89.

37. The composition, method, or use of embodiment 32, wherein the first binding domain comprises a VHH chain having the amino acid sequence set forth in SEQ ID NO:93.

38. The composition, method, or use of embodiment 32, wherein the first binding domain comprises a VHH chain having the amino acid sequence set forth in SEQ ID NO:97.

39. The composition, method, or use of embodiment 32, wherein the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3, and ICDR1 , ICDR2, and ICDR3, respectively, the CDRs having amino acid sequences selected from the sets of amino acid sequences set forth in the group consisting of: a. SEQ ID NO:83 to SEQ ID NO:88, respectively; and b. SEQ ID NO:75 to SEQ ID NQ:80, respectively; or the first binding domain includes a VHH chain having hCDR1 , hCDR2, and hCDR3, the VHH CDRs having the amino acid sequences selected from the sets of amino acid sequences set forth in the group consisting of: c. SEQ ID NQ:90 to SEQ ID NO:92, respectively; d. SEQ ID NO:94 to SEQ ID NO:96, respectively; and e. SEQ ID NO:98 to SEQ ID NO: 100, respectively.

40. The composition, method, or use of embodiment 32, wherein the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3, and ICDR1 , ICDR2, and ICDR3, respectively, the CDRs having amino acid sequences as set forth in SEQ ID NO:83 to SEQ ID NO:88, respectively.

41 . The composition, method, or use of any one of embodiments 22-31 , wherein the first binding domain specifically binds to CD3 or a subunit of CD3, optionally CD3epsilon.

42. The composition, method, or use of embodiment 41 , wherein the first binding domain comprises a heavy chain variable region (VH) and a light chain variable region (VL), the VH and VL amino acid sequences selected from the pairs of amino acids sequences set forth in the group consisting of: a. SEQ ID NO:1 and SEQ ID NO:2, respectively; b. SEQ ID NO:9 and SEQ ID NO: 10, respectively; c. SEQ ID NO: 17 and SEQ ID NO: 18, respectively; d. SEQ ID NO:25 and SEQ ID NO:26, respectively; e. SEQ ID NO:33 and SEQ ID NO:34, respectively; f. SEQ ID NO:41 and SEQ ID NO:34, respectively; g. SEQ ID NO:45 and SEQ ID NO:34, respectively; h. SEQ ID NO:49 and SEQ ID NQ:50, respectively; i. SEQ ID NO:57 and SEQ ID NO:58, respectively; j. SEQ ID NO:65 and SEQ ID NO:66, respectively; and k. SEQ ID NO:65 and SEQ ID NO: 166, respectively.

43. The composition, method, or use of embodiment 41 , wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO:1 and a light chain variable region (VL) having the amino acid sequence set forth in SEQ ID NO:2.

44. The composition, method, or use of embodiment 41 , wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO:9 and a light chain variable region (VL) having the amino acid sequence set forth in SEQ ID NO: 10.

45. The composition, method, or use of embodiment 41 , wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO: 17 and a light chain variable region (VL) having the amino acid sequence set forth in SEQ ID NO: 18. 46. The composition, method, or use of embodiment 41 , wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO:25 and a light chain variable region (VL) having the amino acid sequence set forth in SEQ ID NO:26.

47. The composition, method, or use of embodiment 41 , wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO:33 and a light chain variable region (VL) having the amino acid sequence set forth in SEQ ID NO:34.

48. The composition, method, or use of embodiment 41 , wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO:41 and a light chain variable region (VL) having the amino acid sequence set forth in SEQ ID NO:34.

49. The composition, method, or use of embodiment 41 , wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO:45 and a light chain variable region (VL) having the amino acid sequence set forth in SEQ ID NO:34.

50. The composition, method, or use of embodiment 41 , wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO:49 and a light chain variable region (VL) having the amino acid sequence set forth in SEQ ID NQ:50.

51 . The composition, method, or use of embodiment 41 , wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO:57 and a light chain variable region (VL) having the amino acid sequence set forth in SEQ ID NO:58.

52. The composition, method, or use of embodiment 41 , wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO:65 and a light chain variable region (VL) having the amino acid sequence set forth in SEQ ID NO:66.

53. The composition, method, or use of embodiment 41 , wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO:65 and a light chain variable region (VL) having the amino acid sequence set forth in SEQ ID NO: 166. 54. The composition, method, or use of embodiment 41 , wherein the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3, and ICDR1 , ICDR2, and ICDR3, respectively, the CDRs having amino acid sequences selected from the sets of amino acid sequences set forth in the group consisting of: a. SEQ ID NO:3 to SEQ ID NO:8, respectively; b. SEQ ID NO: 11 to SEQ ID NO: 16, respectively; c. SEQ ID NO: 19 to SEQ ID NO:24, respectively; d. SEQ ID NO:27 to SEQ ID NO:32, respectively; e. SEQ ID NO:35 to SEQ ID NQ:40, respectively; f. SEQ ID NO:42 to SEQ ID NO:44 and SEQ ID NO:38 to SEQ ID NQ:40, respectively; g. SEQ ID NO:46 to SEQ ID NO:48 and SEQ ID NO:38 to SEQ ID NQ:40, respectively; h. SEQ ID NO:51 to SEQ ID NO:56, respectively; i. SEQ ID NO:59 to SEQ ID NO:64, respectively; j. SEQ ID NO:67 to SEQ ID NO:72, respectively; and k. SEQ ID NOs:67-69 and 167-169, respectively.

55. The composition, method, or use of any one of embodiments 22-31 , wherein the first binding domain specifically binds to ICOS.

56. The composition, method, or use of embodiment 55, wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence of SEQ ID NQ:170 and a light chain variable region (VL) having the amino acid sequence of SEQ ID NO: 171.

57. The composition, method, or use of embodiment 55, wherein the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3 amino acid sequences according to SEQ ID NOs:172, 173, and 174, respectively, and ICDR1 , ICDR2, and ICDR3 amino acid sequences according to SEQ ID NOs: 175, 176, and 177, respectively. 58. The composition, method, or use of any one of embodiments 22-31 , wherein the first binding domain specifically binds to PD-1 .

59. The composition, method, or use of embodiment 58, wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence of SEQ ID NO: 178 and a light chain variable region (VL) having the amino acid sequence of SEQ ID NO: 179.

60. The composition, method, or use of embodiment 58, wherein the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3 amino acid sequences according to SEQ ID NQs:180, 181 , and 182, respectively, and ICDR1 , ICDR2, and ICDR3 amino acid sequences according to SEQ ID NOs: 183, 184, and 185, respectively.

61 . The composition, method, or use of any one of embodiments 22-31 , wherein the first binding domain specifically binds to CXCR3.

62. The composition, method, or use of embodiment 61 , wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence of SEQ ID NO:186 and a light chain variable region (VL) having the amino acid sequence of SEQ ID NO: 187.

63. The composition, method, or use of embodiment 61 , wherein the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3 amino acid sequences according to SEQ ID NOs: 188, 189, and 190, respectively, and ICDR1 , ICDR2, and ICDR3 amino acid sequences according to SEQ ID NOs: 191 , 192, and 193, respectively.

64. The composition, method, or use of any one of embodiments 22-31 , wherein the first binding domain specifically binds to CD5.

65. The composition, method, or use of embodiment 64, wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence of SEQ ID NO:194 and a light chain variable region (VL) having the amino acid sequence of SEQ ID NO: 195.

66. The composition, method, or use of embodiment 64, wherein the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3 amino acid sequences according to SEQ ID NOs:196, 197, and 198, respectively, and ICDR1 , ICDR2, and ICDR3 amino acid sequences according to SEQ ID NOs: 199, 200, and 201 , respectively.

67. The composition, method, or use of any one of embodiments 22-66, wherein the inhibitory KIR protein is selected from KIR3DL1 , KIR3DL2, KIR2DL1 , KIR2DL2, and KIR2DL3 or a combination thereof.

68. The composition, method, or use of embodiment 67, wherein the second binding domain specifically binds to KIR2DL1/2/3 or KIR2DL1/2.

69. The composition, method, or use of any one of embodiments 22-68, wherein the second binding domain comprises a heavy chain variable region (VH) and a light chain variable region (VL), the VH and VL regions having amino acid sequences selected from the pairs of amino acid sequences set forth in the group consisting of: a. SEQ ID NO: 101 and SEQ ID NO: 102, respectively; b. SEQ ID NO: 109 and SEQ ID NO: 110, respectively; c. SEQ ID NO:117 and SEQ ID NO: 118, respectively; d. SEQ ID NO:125 and SEQ ID NO:126, respectively; e. SEQ ID NO: 133 and SEQ ID NO: 134, respectively; f. SEQ ID NO:141 and SEQ ID NO:142, respectively; g. SEQ ID NO: 149 and SEQ ID NO: 150, respectively; and h. SEQ ID NO: 157 and SEQ ID NO: 158, respectively.

70. The composition, method, or use of any one of embodiments 22-68, wherein the second binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NQ:101 and a light chain variable region (VL) set forth in SEQ ID NO: 102.

71 . The composition, method, or use of any one embodiments 22-68, wherein the second binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO: 109 and a light chain variable region (VL) having the amino acid sequence set forth inSEQ ID NO: 110.

72. The composition, method, or use of any one embodiments 22-68, wherein the second binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO:117 and a light chain variable region (VL) having the amino acid sequence set forth inSEQ ID NO:118.

73. The composition, method, or use of any one embodiments 22-68, wherein the second binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO: 125 and a light chain variable region (VL) having the amino acid sequence set forth inSEQ ID NO:126.

74. The composition, method, or use of any one embodiments 22-68, wherein the second binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO: 133 and a light chain variable region (VL) having the amino acid sequence set forth inSEQ ID NO:134.

75. The composition, method, or use of any one embodiments 22-68, wherein the second binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO: 141 and a light chain variable region (VL) having the amino acid sequence set forth inSEQ ID NO:142.

76. The composition, method, or use of any one embodiments 22-68, wherein the second binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO: 149 and a light chain variable region (VL) having the amino acid sequence set forth inSEQ ID NQ:150.

77. The composition, method, or use of any one embodiments 22-68, wherein the second binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO: 157 and a light chain variable region (VL) having the amino acid sequence set forth inSEQ ID NO: 158.

78. The composition, method, or use of any one of embodiments 22-68, wherein the second binding domain comprises a heavy chain variable region (VH) and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3, and ICDR1 , ICDR2, and ICDR3, respectively, the CDRs having the amino acid sequence selected from the sets of amino acid sequences set forth in the group consisting of: a. SEQ ID NO: 103 to SEQ ID NO: 108, respectively; b. SEQ ID NO:111 to SEQ ID NO:116, respectively; c. SEQ ID NO:119 to SEQ ID NO: 124, respectively; d. SEQ ID NO: 127 to SEQ ID NO: 132, respectively; e. SEQ ID NO: 135 to SEQ ID NO: 140, respectively; f. SEQ ID NO: 143 to SEQ ID NO: 148, respectively; g. SEQ ID NO: 151 to SEQ ID NO: 156, respectively; and h. SEQ ID NO:159 and SEQ ID NO:164, respectively.

79. The composition, method, or use of any one of the preceding embodiments, where the binding agent does not contain an Fc domain.

80. The composition, method, or use of any one of embodiments 1-78, further comprising an Fc domain.

81 . The composition, method, or use of embodiment 80, wherein the Fc domain is selected from an lgG1 and an lgG4 Fc domain.

82. The composition, method, or use of any one of the preceding embodiments, wherein the binding agent has substantially no effector function activity.

83. The composition, method, or use of any one of embodiments 80-82, wherein the Fc domain is an lgG1 Fc domain.

84. The composition, method, or use of any one of embodiments 80-83, wherein the Fc domain is an lgG1 Fc null.

85. The composition, method, or useof any one of the preceding embodiments, wherein the binding agent is bivalent, trivalent, or tetravalent.

86. The composition, method, or useof any one of the preceding embodiments, wherein the binding agent is bivalent or tetravalent.

87. The composition, method, or use of any one of the preceding embodiments, wherein the binding agent is bispecific.

88. The composition, method, or use of any one of the preceding embodiments, wherein the virus or viral vector is a retrovirus, adenovirus, parvovirus, coronavirus, ortho-myxovirus, rhabdovirus, paramyxovirus, picornavirus, alphavirus, herpesvirus, poxvirus, Norwalk virus, togavirus, flavivirus, reoviruses, papovavirus, hepadnavirus, or hepatitis virus.

89. The composition, method, or use of any one of embodiments 1-87, wherein the virus or viral vector is an adeno-associated virus (AAV) vector. 90. The composition, method, or use of embodiment 89, wherein the AAV vector is AAV1 , AAV2, AAV3, AAV4, AAV5, AAV6, AAV7, AAV8, AAV9, AAVrh.8,

AAVrh.10, AAVrh.43, AAVrh.74, or AAVhu.37, or a variant thereof.

91 . The method of any one of embodiments 1 -88, wherein the virus or viral vector is an adenovirus vector.

92. The method of any one of embodiments 1-88, wherein the viral vector is a lentivirus vector.

93. The composition, method, or use of any one of the preceding embodiments, wherein the binding agent is administered as a pharmaceutical composition comprising the binding agent and a pharmaceutically acceptable carrier.

94. The composition, method, or use of any one of embodiments 1-40 and 67- 93, wherein the binding agent specifically binds to CD8 and the inhibitory KIR protein on CD8+KIR+ Tregs.

95. The composition, method, or use of any one of embodiments 1 -31 , 41-54, and 67-93, wherein the binding agent specifically binds to CD3 and the inhibitory KIR protein on CD8+KIR+ Tregs.

96. The composition, method, or use of any one embodiments 1-31 , 64-66, and 67-93, wherein the binding agent specifically binds to CD5 and the inhibitory KIR protein on CD8+KIR+ Tregs.

97. The composition, method, or use of any one of embodiments 1 -31 , 58-60, and 67-93, wherein the binding agent specifically binds to PD-1 and the inhibitory KIR protein on CD8+KIR+ Tregs.

98. The composition, method, or use of any one of embodiments 1 -31 , 55-57, and 67-93, wherein the binding agent specifically binds to ICOS and the inhibitory KIR protein on CD8+KIR+ Tregs.

99. The composition, method, or use of any one of embodiments 1 -31 , 61-63, and 67-93, wherein the binding agent specifically binds to CXCR3 and the inhibitory KIR protein on CD8+KIR+ Tregs.

100. The composition, method, or use of any one of embodiments 1-99, wherein the CD8+KIR+ Tregs are MHC class I restricted.

101. The composition, method, or use of any one of embodiments 1 -100, wherein the CD8+KIR+ Tregs are not MHC HLA E (Qa-1b) restricted. 102. The composition, method, or use of any one of embodiments 1-101 , further comprising administering an immunosuppressive agent to the subject.

103. The composition, method, or use of any one of embodiments 1-102, wherein the administration of the binding agent to the subject results in an improved treatment outcome in the subject.

104. The composition, method, or use of any one of embodiments 1-103, wherein the binding agent is administered intravenously.

105. The composition, method, or use of any one of embodiments 1-103, wherein the binding agent is administered subcutaneously.

106. The composition, method, or use of any one of embodiments 1-105, wherein the binding agent is administered in a dose of about 0.01 mg/kg to about 20 mg/kg.

107. The composition, method, or use of any one of the preceding embodiments, wherein administration of the binding agent activates or stimulates CD8+KIR+ Tregs.

108. The composition, method, or use of any one of the preceding embodiments, wherein administration of the binding agent reduces an undesired immune response by immune cells by activating or stimulating CD8+KIR+ Tregs.

109. The composition, method, or use of any one of the preceding embodiments, wherein administration of the binding agent reduces antibody titer in a subject by activating or stimulating CD8+KIR+ Tregs.

110. A CD8+KIR+ T regulatory cell (Treg) for use in a method of suppressing or reducing an immune response to a virus in a subject.

111. A method of suppressing or reducing an immune response to a virus in a subject, comprising administering a CD8+KIR+ T regulatory cell (Treg).

112. The use of a CD8+KIR+ T regulatory cell (Treg) in the manufacture of a medicament for suppressing or reducing an immune response to a virus in a subject.

113. A CD8+KIR+ T regulatory cell (Treg) for use in a method of preventing an immune response to a virus in a subject.

114. A method of preventing an immune response to a virus in a subject, comprising administering a CD8+KIR+ T regulatory cell (Treg). 115. The use of a CD8+KIR+ T regulatory cell (Treg) in the manufacture of a medicament for preventing an immune response to a virus in a subject.

116. The composition, method, or use of any one of embodiments 110-115, wherein the virus is a viral vector.

117. The composition, method, or use of embodiment 116, wherein the viral vector has been, is, or will be administered to the subject.

118. The composition, method, or use of embodiment 116 or embodiment 117, wherein the immune response to the viral vector is induced by administration of a viral vector to the subject.

119. The composition, method, or use of any one of embodiments 110-118, wherein the Treg has been contacted with the binding agent according to any one of embodiments 1-109.

120. The composition, method, or use of embodiment 119, wherein the CD8+KIR+ Treg has been contacted with the binding agent ex vivo.

Examples

EXAMPLE 1 : Testing of Mono and Bispecific Molecules on CD8+KIR+ Treg Cell Activation and Cytotoxicity Against Pathogenic Immune Cells in an Autoimmune Disorder

To test a panel of monospecific and bispecific molecules (including inhibitory KIR blockers) for the functional recovery of CD8 KIR+ Treg cell activation and cytotoxicity-mediated elimination of pathogenic immune cells, such as autoreactive CD4 T cells, primary CD8+ KIR+ T cells will be incubated with escalating concentrations of a CD3 agonist antibody, which will mimic peptide/MHC binding of CD8 KIR+ T cell receptors in the presence of increasing concentrations of inhibitory KIR blocking molecules. It can be expected that blockade of the inhibitory KIR signal will reduce the activation threshold of TCR engagement required for CD8 KIR+ Treg cell activation resulting in a specific and increased activation status of CD8 KIR+ T cells. The increased activation of CD8+KIR+ Treg cells will be confirmed by the increase of secretion of certain cytokines (e.g., IFNgamma, IL-10, TNFalpha, IL-35 or subunits thereof, etc), the increase of expression markers associated with activation (e.g., CD69, CD25, CD62L, CD44, CD45) and an increase of proliferation. The panel of mono- and bi-specific molecules will be examined based on their potency by inducing CD8 KIR+ Treg cell mediated functional consequences, and will be subsequently tested using Celiac patient peripheral blood mononuclear cell- derived CD8 KIR+ Treg cells in response to gluten restimulated CD4 T cells. Increased activation and enhanced activity toward pathogenic immune cells by CD8KIR+ Treg cells will be confirmed by an increase of secretion of certain cytokines (e.g., IFNgamma, IL-10, TNFalpha, and/or IL-35 or subunits thereof, etc.), an increase of expression markers (e.g., CD69, CD25, CD62L, CD44, and/or CD45), a decrease in inhibitory molecules (LAG-3, TIM-3, and/or PD-1 ), an increase of proliferation, increased inhibition of autoreactive CD4+ T cells and other pathogenic immune cells, such as autoantibody producing B cells, self-antigen presenting dendritic cells and self-APC.

EXAMPLE 2: Testing of Mono and Bispecific Molecules on CD8+KIR+ Treg Cell Activation and Cytotoxicity in an Infection Model

A panel of monospecific and bispecific molecules, (including inhibitory KIR blockers) will be tested for the functional recovery of CD8 KIR+ Treg cell activation and cytotoxicity mediated direct and indirect elimination of pathogen infected cells. Human CMV specific T cells (Cellero) will be cultured with increasing doses of a virally derived dominant epitope (pp65), which binds the MHC class I molecule HLA- A2. Peptides will be loaded onto an HLA-A2 expressing lymphoma cell line T2. For testing of specific inhibitory KIR molecule functions, either the MHC I deficient lymphoma T1 cell line or the K562 cell line will be transfected with relevant cognate MHC class I molecules (e.g., HLA-C2 when blocking KIR2DL1). To confirm that KIR blockade specifically and effectively reestablishes the elimination of pathogen infected cells, CD8 Treg cell activation, cytotoxicity, cytokine production, and proliferation will be examined. The degree of target cell elimination and apoptosis using Annexin V staining and proliferation will also be determined. As controls we will use, for example, irrelevant influenza hemaglutinin peptides (negative control), CD3 antibody bead activation (positive control), or the MHC deficient lymphoma T1 cell line or parent K562 cells (negative controls). To detect activation with greater sensitivity we will transfect, for example, Jurkat cells with SHP1/2 or NFAT reporter to show enhanced activation upon inhibitory KIR blockade and/or agonist binding to prioritize molecules for use.

EXAMPLE 3: Testing of Mono and Bispecific Molecules on CD8+KIR+ Treg Cell Activation and Cytotoxicity in a Cancer Model

CD8+KIR+ Treg cells will be tested against a panel of tumor cell lines with high antigenic burden in the presence of a panel of KIR bispecific molecules to determine if KIR blockade improves CD8 KIR Treg cell activation and target cell killing. KIR bispecific molecules will be tested alone or in combination with other KIR bispecific molecules and in combination with other immune checkpoint inhibitors. As an example, studies will test anti-CD3 agonist antibody dose escalation in conjunction with KIR molecule dose escalation in coculture with tumor cell lines to include, for example: A549 (NSCLC), H1229 (NSCLC), A375 (Melanoma), SK-Mel 3 (Melanoma), Caki-1 (RCC), and/or 786- O (RCC). Dependence of haplotype on responses will be determined using for example primary NY-ESO-1 specific T cells (Cellero) vs NY-ESO1 peptide pulsed T2 (HLA-A2 restricted cell line) and/or HLA-A2 K562. To assess if a subset of HLA expression by tumor cell targets is required for optimal responses (e.g., HLA-B binding KIR3DL1 or KIR2DL1/2/3 binding HLA-C), the relevant HLA molecules will be overexpressed in either K562 or T1 cells and pulsed with relevant dominant epitopes (https://antibodies.cancer.gov/detail/MajorHistocompatibilityComplexClasslCPeptide 1 ).

EXAMPLE 4: Testing of Mono- and Bispecific Molecules on CD8+KIR+ Treg Cell Activation and Cytotoxicity in a GVHD Transplantation Model

Following hematopoietic stem cell transplant and other transplant procedures, a serious and life threatening complication can occur in which donor-derived cells recognize allogeneic host tissues as foreign and become activated, destroying healthy cells of the recipient, which is known as graft vs. host disease (GVHD). Alloreactive GVHD results in transplant associated morbidity in up to 50% of transplant recipients, and accounts for approximately 20% of deaths following transplant. KIR blockade on CD8+KIR+ Tregs may reduce the seventy of graft vs host disease in the event that transplanted cells destroy healthy tissues and recognize it as foreign. To test the impact of KIR blockade on GVHD severity, a well- characterized GVHD model will be used, in which human immune cells are injected into NOD/SCID/gamma chain (NSG) deficient mice, and subsequent multi-organ acute pathology observed as a result of human cell activation and destruction of mouse tissues. KIR blocking mono- and bispecific molecules will be injected every 72 hours for the duration of the 30-45 day study, and endpoint analysis will include serum pro-inflammatory cytokines, activation marker expression of human T cells, disease scoring (including survival and body weight), and histopathological analysis of gut tissues for inflammation and epithelial cell killing. This study will support the utility of KIR blockade as a method to reduce seventy of GVHD while preserving transplant engraftment, as well as determine the effect of KIR blockade on systemic diseases that may impact multiple organs and tissues.

EXAMPLE 5: Ly49 Blockade Increases the Activity of CD8+Ly49+ T Regulatory Cells

The effects of Ly49 blockade on CD8+Ly49+ Tregs were confirmed in vitro. Briefly, cells were isolated from the spleens and lymph nodes of C57BL/6 mice 10 days after EAE induction using a standard MOG peptide protocol at day 10 (see Saligrama et al., Nature 572:481 -487 (2019)). CD4+ T cells, CD8+ CD28- regulatory T cells, and CD8+CD28+ were isolated using magnetic separation and stimulated with CD3/CD28 in the presence of no blocking antibody (control) or F(ab')2 fragments of blocking antibody LY49 C/l (clone 5e6; lacking the Fc portion of the antibody) (anti-Ly49) and cultured 1 :1 with CD4 T cells.

In the presence of Ly49 blockade there was a statistically significant increase in CD8+ Treg activation (Figure 4A), production of immunosuppressive cytokines (Figure 4B), cytolytic activity (Granzyme B) (Figure 40), and an increase in CD4 T cell production of anti-inflammatory IL-10 cytokine (Figure 4D). Similar results were observed with cells stimulated with CD3/CD28 in the presence of full length Ly49 C/l blocking antibody (clone 5E6) (data not shown). These results confirm that CD8+Ly49+ T cells exhibit an increase in activation by Ly49 blockade. Supernatants from the cells (above) were collected at 48 hours after the initiation of the co-culture and analyzed for a variety of analytes (cytokines) using a Bioplex assay. The results of this analysis indicated that Ly49 blockade suppresses the following proinflammatory cytokines in samples from mice treated with MOG and suppressor peptide as compared to mice treated with MOG peptide alone: RANTES, IL-6, IL-18, GM-CSF, TNFalpha, and IFNgamma (data not shown). In addition, IL-2 and IL-15 levels were decreased in samples from mice treated with MOG and suppressor peptide as compared to mice treated with MOG peptide (data not shown). Levels of the anti-inflammatory cytokines IL-22 and MCP-3 were decreased in samples from mice treated with MOG and suppressor peptide as compared to mice treated with MOG peptide (data not shown).

EXAMPLE 6: CD8 KIR+ T Cells Have Greater Cytolytic Potential than CD8 T Cells Negative for KIR Expression in Celiac Patients

Peripheral blood mononuclear cells (PBMCs) were obtained from Celiac patients and from healthy donors. The PBMCs were enriched for CD8+ T cells, and then stained for several surface markers, including CD8 and a mix of pan-inhibitory KIR reactive peptides, and sorted to obtain CD8+KIR+ T cells and CD8+KIR- cells. After sorting, the PBMCs were stimulated with gluten peptides. Six days after stimulation, the CD8 Treg cells were evaluated for intracellular Granzyme, perforin, and IFNgamma levels.

PBMCs from Celiac patients had a greater percentage of CD8+KIR+ Treg cells (Figure 5A). The KIR+ CD8+ T cells had a greater percentage of cells with perforin, and intracellular IFNgamma and Granzyme B as compared to CD8+KIR- T cells (Figure 5B and 5C. These results indicate that Celiac patients harbor CD8+ KIR+ T cells with greater cytolytic potential than CD8+ T cells negative for KIR.

EXAMPLE 7: Celiac Patients Have More KIR+ CD8+ T cells and More ICOS Expression on KIR+ CD8+ T Cells Than From Healthy Controls

PBMCs from Celiac patients (six) or healthy donors were analyzed by flow cytometry and gated on CD8+ T cells. PBMCs from Celiac patients had more CD3+/PanKIR+ T cells than PBMCs from healthy donors (Figure 6A). PBMCs from Celiac patients had more CD3+/PanKIR+/ICOS+ cells than PBMCs from healthy donors (Figure 6B). These results indicate that Celiac patients have more ICOS expression on KIR+ CD8+ T cells.

EXAMPLE 8: Gluten Restimulation Increases Granzyme B Levels and Degranulation of CD8+KIR+ Tregs and Loss of CD4+ T Cells

To determine the effects of the gluten restimulation on the CD8+KIR+ T cells, PMBCs from Celiac patients were stimulated with gluten peptides for 12 days to enrich for both CD4 reactive cells and CD8+ Treg cells in the presence of IL-7 and 15. CD8 Tregs and CD4 T cells were then selected and combined 1 :1 with autologous APCs pulsed with no peptide, flu peptides, or gluten peptides. 48 hours later, the cells were analyzed by flow cytometry.

Restimulation with the gluten peptides increased degranulation, as measured by CD107 (Figure 7A, left), and Granzyme B levels (Figure 7B, right), as compared to restimulation with control flu peptides or unstimulated cells. (598 refers to PBMCs from patient 598.) Restimulation with gluten peptides also caused a reduction of the percentage of viable CD4+ cells, while restimulation with flu peptide did not (Figure 7B). These results indicate that the antigenic response by CD8+KIR+ Tregs is specific, consistent with the source of the Tregs from Celiac patients, and are rapid and sustained. These results show that CD8+ Treg cells are up-regulated and CD4+ T cell activation is down-regulated, and that pathogenic CD4+ T cells are eliminated.

EXAMPLE 9: KIR Blockade Increases Granzyme B Content and Degranulation of CD8+ T Cells

CD8+CD16+ T cells were selected from 3 patients diagnosed with Celiac disease and cultured 1 :1 with CD4 T cells and 1ug/ml anti-CD3 agonist antibody (clone OKT3) in the presence or absence of 100ug/ml KIR2DL1/2/3 and KIR3DL1 antagonist antibodies (50ug each). 48 hours later, CD8 Treg cells were analyzed using flow cytometry.

KIR blockade ("KIR block") increased intracellular Granzyme B levels (Figure 8A) and degranulation (CD107) (Figure 8B). EXAMPLE 10: KIR Blockade Decreases CD4 T Cell Activation

CD8+ CD16+ T cells were selected from 3 patients diagnosed with Celiac disease and cultured 1 :1 with CD4+ T cells and 1 ug/ml anti-CD3 agonist antibody (clone OKT3) in the presence or absence of 100ug/ml KIR2DL1/2/3 and KIR3DL1 antagonist antibodies (50ug each). 48 hours later, CD8+ Treg cells were analyzed using flow cytometry.

KIR blockade reduced CD4+ T cell activation and proliferation (CD69) in samples from all three patients (Figure 9).

EXAMPLE 11 : Association Between Select KIR Proteins and HLA Ligand Expression in CD8 Treg Cells in Celiac Disease

Celiac patient PBMCs were stained with antibodies directed toward KIR2DL1/2/3 and KIR3DL1 . After gating on CD8 T cells, the percentage positivity of the cells for the KIR ligands and HLA haplotype was determined. (HLA and KIR typing were performed in collaboration with Scisco Genetics.)

CD8+ T cells from patients expressed KIRs as follows: 3 of 3 expressed KIR2DL and 2 of 3 expressed KIR3DL in peripheral blood. HLA ligands for the select KIRs are overrepresented in the Celiac patient samples. 9 of 10 patients had at least one copy of HLA-C 07:01 :01 and 10 of 10 patients had at least one copy of HLA-B 08:01 :01.

EXAMPLE 12: Characterization of Bispecific Molecules That Co-Bind to CD8 and KIR2DL

A CrossMab was prepared using a Fab that binds to KIR2L1/2/3 (prepared from IPH2102 IgG 1 r mAb (parental antibody VH and VL sequences, SEQ ID NOs:101 and 102, respectively)) and an scFv that binds to CD8alpha (prepared from Mb1 b lgG1 r mAb (parental antibody VH and VL sequences, SEQ ID NOs:81 and 82)). The Fab and scFv were attached to an IgG 1 hinge-CH2-CH3 in which the CH3 domain was engineered to contain the "knobs-into-holes" mutations to enforce correct association of the two heterodimeric heavy chains. The "knob" heavy chain included mutations S354C and T366W. The "hole" heavy chain included mutations Y349C, T366S, L368A, and Y407V. The KIR2L1/2/3 - CD8alpha CrossMAb was tested for co-binding to KIR2DL1 or KIR2DL3 and CD8alpha by biolayer interferometry using an Octet instrument. For the co-binding studies, the CrossMAb was captured to AHC (anti-human Fc) biosensors using 2-fold dilutions ranging from 0.3125 ug/ml to 20 ug/ml. The analytes (KIR2DL1 , KIR2DL3, and CD8alpha) were kept constant at 100 nM. Analyte co-binding following capture was analyzed in two ways: first the association of KIR2DL1 or KIR2DL3 followed directly by the association of CD8alpha, or the association of CD8alpha followed by the direct association of KIRDL1 or KIR2DL3. KIR2DL1 , KIR2DL3, and CD8alpha were tagged with a hexahistidine peptide. The CrossMab was able to co-bind targets KIR2DL1 or KIR2DL3 and CD8alpha.

CrossMAb affinity for KIR2DL1 , KIR2DL3, and CD8alpha ligands was measured and compared to the anti-CD8alpha and anti-KIR2DL1/L2/L3 parental antibodies using the Octet instrument. For kinetic analysis, the CrossMAb was captured to AHC (anti-human Fc) biosensors using a load concentration of 1.25 ug/ml. Each analyte (KIR2DL1 , KIR2DL3, and CD8alpha) concentration ranged from 6.25 nM to 200 nM. Analyte binding following capture was analyzed first for the association of KIR2DL1 , KIR2DL3, or CD8alpha followed by the dissociation of each analyte independently. This ensured that ka (on rate), kd (off rate), and KD values could be obtained and directly compared to the parental antibodies. The kinetic analysis revealed that the CrossMab retained affinity for targets KIR2DL1 , KIR2DL3, and CD8alpha.

The affinities of the parental antibodies anti-KIR2DL1/L2/L3 IPH2102 lgG1 r mAb and anti-CD8alpha Mb1 b IgG 1 r mAb were also analyzed. For kinetic analysis, the parental antibodies were separately captured to AHC (anti-human Fc) biosensors using a load concentration of 1.25 ug/ml. For IPH2102 lgG1 r mAb, the KIR2DL1 or KIR2DL3 analytes ranged from 6.25 nM to 200 nM. Analyte binding following capture was analyzed first for association of KIR2DL1 or KIR2DL3 followed by the dissociation of each analyte independently. Likewise, for the Mb1 b IgG 1 r mAb, the CD8alpha analyte ranged from 6.25 nM to 200 nM. Analyte binding following capture was analyzed first for association followed by the dissociation of CD8alpha.

Table 1 . Comparison of affinities between the parental antibodies and the CrossMAb.

EXAMPLE 13: Analyses of PBMC Samples from Patients Diagnosed with Other

Autoimmune Diseases

PCMCs from patients having Lupus, Ulcerative colitis, Crohn’s Disease, Multiple Sclerosis, and Type 1 Diabetes were analyzed using flow cytometry and bioplex assays. CD8+KIR+ Treg cells were identified in these patient samples. The Tregs were found to express CXCR3, CD39, and other cells surface markers, consistent with the CD8+ Tregs from Celiac disease patients (data not shown). The CD8+ Tregs were found to produce soluble analytes associated with CD8+ Treg cell function, including IFNgamma and IL-22 (data not shown).

EXAMPLE 14: Ex vivo Restimulation of Naive PBMCs using AAV Vectors Treatment-naive PBMCs collected from healthy individuals are restimulated ex vivo using AAV vectors, to determine whether CD8+ Tregs are impacted and become dysfunctional following AAV treatment.

PBMCs are treated with AAV vectors. As controls, a subset of PBMCs are unstimulated (negative control), and other autologous PBMCs are stimulated to induce polyclonal expansion and inflammatory responses (positive control). Three days later, cells and supernatants are collected for analysis.

The presence and prevalence of CD8+ Tregs before and following treatment with demonstrated immunogenic and non-immunogenic AAV vectors are determined. CD8+ Treg cells are analyzed using flow cytometry to gauge prevalence and phenotypic characteristics of CD8+ Tregs. Function of CD8+ Treg cells is also assessed, determined using functional markers (e.g., intracellular markers of cytolytic potential) and hallmark cytokines indicative of function or failure to function. The presence and prevalence of CD4+ T cells, and whether they have changed in response to AAV treatment, is also determined. Activation state of and select cytokine production by CD4+ T cells is also assessed. Supernatants are collected and soluble chemokines and cytokines are evaluated.

EXAMPLE 15: Analyses of Cells from Animal AAV Infection Models

Cells from animal models of AAV infection are analyzed to determine the presence of CD8+KIR+ Treg cells, and identify cell surface markers such as CXCR3 and CD39. The production of soluble analytes associated with CD8+ Treg cell function, including IFNgamma and IL-22, by the CD8+ Treg cells is also assessed.

EXAMPLE 16: Analyses of PBMC Samples from AAV Seropositive Patients

PBMCs from AAV seropositive patients are analyzed using flow cytometry and bioplex assays to determine the presence and prevalence/enrichment of CD4+ T cells and CD8+KIR+ Treg cells, and identify cell surface markers such as CXCR3 and CD39. The production of soluble analytes associated with CD8+ Treg cell function, including IFNgamma and IL-22, by the CD8+ Treg cells is also assessed.

EXAMPLE 17: IFN-y Production by AAV-Reactive CD4+ T cells is Reduced in the Presence of a CD8+ Treg Activating Bispecific Molecule

PBMCs from 6 healthy donors (Stemcell, Vancouver, Canada) were thawed and pulsed with Class Il-restricted peptide pools (1 pg peptide per 1x10⁶ cells; JPT Peptide Technologies, Berlin, Germany) spanning the capsid proteins of adeno- associated virus 5 (AAV5), AAV6, and AAV8. A Class Il-restricted peptide pool generated from CMV, EBV, flu, and tetanus antigens (CEFT; JPT Peptide Technologies) was used as a positive control and DMSO was added to untreated cells. Cells were expanded for 2 weeks in human T cell media (huTCM) (X-VIVO (Lonza, Basel, Switzerland), 5% human serum, 1 % pen/strep, and 1 % GlutaMax). On days 7 and 10, huTCM supplemented with 5 ng/ml IL-2 (Biolegend, San Diego, CA) was added to the cultures. A peptide restimulation assay was performed on Day 15. Frozen PBMCs from the same donors were thawed and mixed 1 :1 with expanded lymphocytes in 96- well plates (1x10⁵ of each cell population per well). Cells were restimulated with the peptide mix they were initially exposed to or with DMSO as a vehicle control, and all conditions were set up in the presence or absence of 10 pg/ml a KIRxCD8 bispecific binding protein. The KIRxCD8 bispecific binding protein was prepared using a Fab that binds to KIR2L1/2/3 (prepared from IPH2102 lgG1 r mAb, parental antibody VH and VL sequences, SEQ ID NOs:101 and 102, respectively) and an scFv that binds to CD8alpha (prepared from Mb1b lgG1 r mAb, parental antibody VH and VL sequences, SEQ ID NOs:81 and 82, respectively). The Fab and scFv were attached to an lgG1 hinge-CH2-CH3 in which the CH3 domain was engineered to contain the "knobs-into-holes" mutations to enforce correct association of the two heterodimeric heavy chains. The "knob" heavy chain included mutations S354C and T366W. The "hole" heavy chain included mutations Y349C, T366S, L368A, and Y407V. Supernatants were collected on Day 2 and Day 5 and IFN-y concentration determined using a ll-PLEX human IFN-y assay (Mesoscale Diagnostics, Rockville, MD). 25 pl of undiluted supernatant was assayed and kit instructions were followed to generate a standard curve. Values above 27000 pg/ml were software extrapolated as this value represents the assays upper limit of detection.

Results were analyzed using MSD Discovery Workbench and plotted in GraphPad Prism. Donor PBMCs showed variable responses to the AAV peptide pools. Except for Donor 10, all donors showed a reduction in IFN-y production in the presence of the KIRxCD8 bispecific binding protein on both day 2 and day 5 (Figures 10A, 10B, and 10C and 11 , where Figure 11 shows the results as the percent of reduction in IFN-y concentration in the presence of the KIRxCD8 bispecific binding protein). While Donor 9 showed only minimal response to the AAV peptides tested, a reduction in IFN-y concentration in the presence of the KIRxCD8 bispecific binding protein was still observed (Figures 10A, 10C).

EXAMPLE 18: Sequences

Exemplary binding protein amino acid sequences are shown in Table 2. Table 2. Exemplary binding protein amino acid sequences.

While specific embodiments have been illustrated and described, it will be readily appreciated that the various embodiments described above can be combined to provide further embodiments, and that various changes can be made therein without departing from the spirit and scope of the invention.

All of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications, and non-patent publications referred to in this specification or listed in the Application Data Sheet, including U.S. Provisional Patent Application No. 63/272064 filed October 26, 2021 , are incorporated herein by reference, in their entireties, unless explicitly stated otherwise. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications, and publications to provide yet further embodiments.

These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.

Claims

CLAIMS What is claimed is:

1 . A binding agent that binds to CD8+KIR+ T regulatory cells (Tregs) for use in a method of suppressing, reducing, or preventing an immune response to a viral vector in a subject.

2. A method of suppressing, reducing, or preventing an immune response to a viral vector in a subject, the method comprising administering to the subject a binding agent that binds to CD8+KIR+ T regulatory cells (Tregs).

3. The use of a binding agent that binds to CD8+KIR+ T regulatory cells (Tregs) in the manufacture of a medicament for suppressing, reducing, or preventing an immune response to a viral vector in a subject.

4. The composition, method, or use of any one of claims 1-3, wherein the viral vector has been, is, or will be administered to the subject.

5. The composition, method, or use of claim 4, wherein the immune response to the viral vector is induced by administration of a viral vector to the subject.

6. The composition, method, or use of any one of the preceding claims, wherein the binding agent comprises:

7. The composition, method, or use of claim 6, wherein the first antigen is selected from the group consisting of CD3, CD5, CD8, CD27, CD38, CD39, CD40L, CD45RA, CD45RB, CD45RO, CD73, CD103 (ITGAE), CD122, CD166, CD177, CCR7, CXCR3, CXCR5, HLA-DR, ICOS, LAG-3/CD223, OX-40, PD-1 , S1000A8/9, TIM-3, TLT-2, 2B4, and 41 BB.

8. The composition, method, or use of any one of the preceding claims, wherein the binding agent is a bispecific antibody, a diabody, an antibody Fc fusion, an scFv1-ScFv2, an SCFV12-FC-SCFV22, an IgG-scFv, a DVD-lg, a triomab/quadroma, a two-in-one IgG, a scFv2-Fc, a TandAb, an scFv-HSA-scFv, an scFv-VHH, a Fab-scFv-Fc, a Fab-VHH-Fc, a dAb-IgG, an IgG-VHH, a Tandem scFv- Fc, a (SCFV1 )2-FC-(VHH)2, a BiTe, a DART, an anticalin, an affibody, an avimer, a DARPin, an adnectin, a CrossMab, a scFv-Fc, a one-armed tandem scFv-Fc, or a DART-Fc.

9. The composition, method, or use of any one of claims 6-8, wherein either the first or second binding domain is selected from an antibody or antigen binding portion thereof, and the other binding domain is an antibody fragment.

10. The composition, method, or use of claim 9, wherein the antigen binding portion is a Fab, Fab', F(ab')2, Fv, scFv, or a single domain antibody, such as a VHH, VNAR, sdAb, or nanobody.

11 . The composition, method, or use of any one of claims 6-10, wherein the first binding domain and/or the second binding domain comprises a heavy chain variable region and a light chain variable region.

12. The composition, method, or use of any one of claims 6-11 , wherein the first binding domain specifically binds to CD8 or a subunit of CD8, optionally CD8alpha.

13. The composition, method, or use of claim 12, wherein the first binding domain comprises a heavy chain variable region (VH) and a light chain variable region (VL), the VH and VL regions having amino acid sequences selected from the pairs of amino acid sequences set forth in the group consisting of: a. SEQ ID NO:81 and SEQ ID NO:82, respectively; and b. SEQ ID NO:73 and SEQ ID NO:74, respectively; or the first binding domain comprises a VHH chain, the VHH chain having the amino acid sequence selected from the amino acid sequences set forth in the group consisting of: c. SEQ ID NO:89; d. SEQ ID NO:93; and e. SEQ ID NO:97.

14. The composition, method, or use of claim 12, wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO:81 and a light chain variable region (VL) having the amino acid sequence set forth in SEQ ID NO:82.

15. The composition, method, or use of claim 12, wherein the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3, and ICDR1 , ICDR2, and ICDR3, respectively, the CDRs having amino acid sequences selected from the sets of amino acid sequences set forth in the group consisting of: a. SEQ ID NO:83 to SEQ ID NO:88, respectively; and b. SEQ ID NO:75 to SEQ ID NQ:80, respectively; or the first binding domain includes a VHH chain having hCDR1 , hCDR2, and hCDR3, the VHH CDRs having the amino acid sequences selected from the sets of amino acid sequences set forth in the group consisting of: c. SEQ ID NQ:90 to SEQ ID NO:92, respectively; d. SEQ ID NO:94 to SEQ ID NO:96, respectively; and e. SEQ ID NO:98 to SEQ ID NO: 100, respectively.

16. The composition, method, or use of claim 12, wherein the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3, and ICDR1 , ICDR2, and ICDR3, respectively, the CDRs having amino acid sequences as set forth in SEQ ID NO:83 to SEQ ID NO:88, respectively.

17. The composition, method, or use of any one of claims 6-11 , wherein the first binding domain specifically binds to CD3 or a subunit of CD3, optionally CD3epsilon.

18. The composition, method, or use of claim 17, wherein the first binding domain comprises a heavy chain variable region (VH) and a light chain variable

108 region (VL), the VH and VL amino acid sequences selected from the pairs of amino acids sequences set forth in the group consisting of: a. SEQ ID NO:1 and SEQ ID NO:2, respectively; b. SEQ ID NO:9 and SEQ ID NO: 10, respectively; c. SEQ ID NO: 17 and SEQ ID NO: 18, respectively; d. SEQ ID NO:25 and SEQ ID NO:26, respectively; e. SEQ ID NO:33 and SEQ ID NO:34, respectively; f. SEQ ID NO:41 and SEQ ID NO:34, respectively; g. SEQ ID NO:45 and SEQ ID NO:34, respectively; h. SEQ ID NO:49 and SEQ ID NQ:50, respectively; i. SEQ ID NO:57 and SEQ ID NO:58, respectively; j. SEQ ID NO:65 and SEQ ID NO:66, respectively; and k. SEQ ID NO:65 and SEQ ID NO: 166, respectively.

19. The composition, method, or use of claim 17, wherein the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3, and ICDR1 , ICDR2, and ICDR3, respectively, the CDRs having amino acid sequences selected from the sets of amino acid sequences set forth in the group consisting of: a. SEQ ID NO:3 to SEQ ID NO:8, respectively; b. SEQ ID NO: 11 to SEQ ID NO: 16, respectively; c. SEQ ID NO: 19 to SEQ ID NO:24, respectively; d. SEQ ID NO:27 to SEQ ID NO:32, respectively; e. SEQ ID NO:35 to SEQ ID NQ:40, respectively; f. SEQ ID NO:42 to SEQ ID NO:44 and SEQ ID NO:38 to SEQ ID

NQ:40, respectively;

109 g. SEQ ID NO:46 to SEQ ID NO:48 and SEQ ID NO:38 to SEQ ID NO:40, respectively; h. SEQ ID NO:51 to SEQ ID NO:56, respectively; i. SEQ ID NO:59 to SEQ ID NO:64, respectively; j. SEQ ID NO:67 to SEQ ID NO:72, respectively; and k. SEQ ID NOs:67-69 and 167-169, respectively.

20. The composition, method, or use of any one of claims 6-11 , wherein the first binding domain specifically binds to ICOS.

21 . The composition, method, or use of claim 20, wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence of SEQ ID NQ:170 and a light chain variable region (VL) having the amino acid sequence of SEQ ID NO: 171.

22. The composition, method, or use of claim 20, wherein the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3 amino acid sequences according to SEQ ID NOs:172, 173, and 174, respectively, and ICDR1 , ICDR2, and ICDR3 amino acid sequences according to SEQ ID NOs: 175, 176, and 177, respectively.

23. The composition, method, or use of any one of claims 6-11 , wherein the first binding domain specifically binds to PD-1 .

24. The composition, method, or use of claim 23, wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence of SEQ ID NO:178 and a light chain variable region (VL) having the amino acid sequence of SEQ ID NO: 179.

25. The composition, method, or use of claim 23, wherein the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3 amino acid sequences according to SEQ ID NOs: 180, 181 , and 182, respectively,

110 and ICDR1 , ICDR2, and ICDR3 amino acid sequences according to SEQ ID NOs: 183, 184, and 185, respectively.

26. The composition, method, or use of any one of claims 6-11 , wherein the first binding domain specifically binds to CXCR3.

27. The composition, method, or use of claim 26, wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence of SEQ ID NO: 186 and a light chain variable region (VL) having the amino acid sequence of SEQ ID NO: 187.

28. The composition, method, or use of claim 26, wherein the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3 amino acid sequences according to SEQ ID NOs: 188, 189, and 190, respectively, and ICDR1 , ICDR2, and ICDR3 amino acid sequences according to SEQ ID NOs: 191 , 192, and 193, respectively.

29. The composition, method, or use of any one of claim 6-11 , wherein the first binding domain specifically binds to CD5.

30. The composition, method, or use of claim 29, wherein the first binding domain comprises a heavy chain variable region (VH) having the amino acid sequence of SEQ ID NO:194 and a light chain variable region (VL) having the amino acid sequence of SEQ ID NO: 195.

31 . The composition, method, or use of claim 29, wherein the first binding domain comprises a heavy chain variable region and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3 amino acid sequences according to SEQ ID NOs: 196, 197, and 198, respectively, and ICDR1 , ICDR2, and ICDR3 amino acid sequences according to SEQ ID NOs: 199, 200, and 201 , respectively.

32. The composition, method, or use of any one of claims 6-31 , wherein the inhibitory KIR protein is selected from KIR3DL1 , KIR3DL2, KIR2DL1 , KIR2DL2, and KIR2DL3 or a combination thereof.

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33. The composition, method, or use of claim 32, wherein the second binding domain specifically binds to KIR2DL1/2/3 or KIR2DL1/2.

34. The composition, method, or use of any one of claim 6-33, wherein the second binding domain comprises a heavy chain variable region (VH) and a light chain variable region (VL), the VH and VL regions having amino acid sequences selected from the pairs of amino acid sequences set forth in the group consisting of: a. SEQ ID NO: 101 and SEQ ID NO: 102, respectively; b. SEQ ID NO: 109 and SEQ ID NO: 110, respectively; c. SEQ ID NO:117 and SEQ ID NO: 118, respectively; d. SEQ ID NO:125 and SEQ ID NO:126, respectively; e. SEQ ID NO: 133 and SEQ ID NO: 134, respectively; f. SEQ ID NO:141 and SEQ ID NO:142, respectively; g. SEQ ID NO: 149 and SEQ ID NO: 150, respectively; and h. SEQ ID NO: 157 and SEQ ID NO: 158, respectively.

35. The composition, method, or use of any one of claims 6-33, wherein the second binding domain comprises a heavy chain variable region (VH) having the amino acid sequence set forth in SEQ ID NO: 101 and a light chain variable region (VL) set forth in SEQ ID NO: 102.

36. The composition, method, or use of any one of claims 6-33, wherein the second binding domain comprises a heavy chain variable region (VH) and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3, and ICDR1 , ICDR2, and ICDR3, respectively, the CDRs having the amino acid sequence selected from the sets of amino acid sequences set forth in the group consisting of: a. SEQ ID NO: 103 to SEQ ID NO: 108, respectively; b. SEQ ID NO:111 to SEQ ID NO:116, respectively; c. SEQ ID NO:119 to SEQ ID NO: 124, respectively; d. SEQ ID NO: 127 to SEQ ID NO: 132, respectively;

112 e. SEQ ID NO: 135 to SEQ ID NO: 140, respectively; f. SEQ ID NO: 143 to SEQ ID NO: 148, respectively; g. SEQ ID NO: 151 to SEQ ID NO: 156, respectively; and h. SEQ ID NO:159 and SEQ ID NO:164, respectively.

37. The composition, method, or use of any one of claims 6-33, wherein the second binding domain comprises a heavy chain variable region (VH) and a light chain variable region, the heavy and light chain variable regions comprising hCDR1 , hCDR1 , and hCDR3, and ICDR1 , ICDR2, and ICDR3, respectively, the CDRs having the amino acid sequences set forth in SEQ ID NQ:103 to SEQ ID NQ:108, respectively.

38. The composition, method, or use of any one of the preceding claims, where the binding agent does not contain an Fc domain.

39. The composition, method, or use of any one of claims 1-37, wherein the binding agent further comprises an Fc domain.

40. The composition, method, or use of any one of the preceding claims, wherein the binding agent has substantially no effector function activity.

41 . The composition, method, or useof any one of the preceding claims, wherein the binding agent is bivalent, trivalent, or tetravalent.

42. The composition, method, or use of any one of the preceding claims, wherein the binding agent is bispecific.

43. The composition, method, or use of any one of the preceding claims, wherein the virus or viral vector is a retrovirus, adenovirus, parvovirus, coronavirus, ortho-myxovirus, rhabdovirus, paramyxovirus, picornavirus, alphavirus, herpesvirus, poxvirus, Norwalk virus, togavirus, flavivirus, reoviruses, papovavirus, hepadnavirus, or hepatitis virus.

44. The composition, method, or use of any one of claims 1-42, wherein the virus or viral vector is an adeno-associated virus (AAV) vector.

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45. The composition, method, or use of claim 44, wherein the AAV vector is AAV1 , AAV2, AAV3, AAV4, AAV5, AAV6, AAV7, AAV8, AAV9, AAVrh.8, AAVrh.10, AAVrh.43, AAVrh.74, or AAVhu.37, or a variant thereof.

46. The composition, method, or use of any one of the preceding claims, wherein the binding agent is administered as a pharmaceutical composition comprising the binding agent and a pharmaceutically acceptable carrier.

47. The composition, method, or use of any one of claims 1-46, wherein the CD8+KIR+ Tregs (i) are MHC class I restricted, or (ii) are not MHC HLA E (Qa-1 b) restricted.

48. The composition, method, or use of any one of claims 1-47, further comprising administering an immunosuppressive agent to the subject.

49. The composition, method, or use of any one of claims 1-48, wherein the binding agent is administered intravenously or subcutaneously.

50. The composition, method, or use of any one of claims 1-49, wherein the binding agent is administered in a dose of about 0.01 mg/kg to about 20 mg/kg.

51 . The composition, method, or use of any one of the preceding claims, wherein administration of the binding agent activates or stimulates CD8+KIR+ Tregs.

52. A CD8+KIR+ T regulatory cell (Treg) for use in a method of suppressing, reducing, or preventing an immune response to a viral vector in a subject.

53. A method of suppressing, reducing, or preventing an immune response to a viral vector in a subject, comprising administering a CD8+KIR+ T regulatory cell (Treg).

54. The use of a CD8+KIR+ T regulatory cell (Treg) in the manufacture of a medicament for suppressing, reducing, or preventing an immune response to a viral vector in a subject.

55. The composition, method, or use of any one of claims 52-54, wherein the

Treg has been contacted with the binding agent according to any one of embodiments 1-51.

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56. The composition, method, or use of claim 55, wherein the CD8+KIR+ Treg has been contacted with the binding agent ex vivo.

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