CN118103406A - Activatable polypeptide complexes - Google Patents

Abstract

The present disclosure relates to activatable Heteromultimeric Bispecific Polypeptide Complexes (HBPC) and methods of making and using the same.

Description

Activatable polypeptide complexes

Cross Reference to Related Applications

The present application claims priority from U.S. provisional application number 63/256,417, filed on 10/15 of 2021, and U.S. provisional application number 63/370,897, filed on 8/9 of 2022, which are incorporated herein by reference in their entirety.

Reference to a sequence Listing submitted electronically via EFS-WEB

The contents of the electronically submitted sequence listing submitted in the present application (4681_002PC02_seqlipping_ST26. Xml; size: 190,193 bytes; and date of creation: 10 month 13 of 2022) are incorporated herein by reference in their entirety.

Technical Field

The present disclosure relates to activatable Heteromultimeric Bispecific Polypeptide Complexes (HBPC) and methods of making and using the same.

Background

The generation and activation of tumor antigen-specific T cells is involved in the mediation of immune-mediated developmental control and tumor regression. This requires the synergistic action of multiple T cell co-stimulatory receptors and T cell negative regulatory or co-inhibitory receptors to control T cell activation, proliferation and acquisition or loss of effector function. However, tumor-specific T cell responses are difficult to establish and maintain in cancer patients due to the multiple immune escape mechanisms of tumor cells. However, attempts have been made to use T cells for cancer treatment. Such methods include the use of T cells to bind bispecific antibodies that bind to a surface target antigen on cancer cells and also bind to a T cell surface polypeptide (such as CD 3) on T cells. Generally, by binding to each target, T cells engage bispecific antibodies (bispecifics) bringing T cells into close physical proximity with cancer cells and allowing cytotoxic T cell proteins and enzymes to attack the tumor cells and cause apoptosis, thereby killing the cancer cells.

While this is a potentially promising class of therapeutic agents for the treatment of cancer, there are several obstacles to overcome such as in-target off-tumor toxicity and manufacturing challenges. Thus, there is a need for immunotherapeutic options with improved safety features and improved manufacturability.

Disclosure of Invention

Provided herein is an activatable Heteromultimeric Bispecific Polypeptide Complex (HBPC) comprising: (a) A first polypeptide comprising (i) a single chain variable fragment (scFv) comprising a first heavy chain variable domain (VH 1) and a first light chain variable domain (VL 1), wherein the VH1 and the VL1 together form a first targeting domain that specifically binds a first target, (ii) a first masking moiety (MM 1), (iii) a first cleavable moiety (CM 1), (iv) a second heavy chain variable domain (VH 2), and (v) a first monomeric Fc domain (Fc 1); (b) A second polypeptide comprising (i) a second light chain variable domain (VL 2), wherein the VH2 and the VL2 together form a second targeting domain that specifically binds a second target, (ii) a second masking moiety (MM 2), and (iii) a second cleavable moiety (CM 2); and (c) a third polypeptide comprising (i) a second monomeric Fc domain (Fc 2), and (ii) no immunoglobulin variable domain. In some aspects, the first target is a T cell antigen polypeptide and the second target is a cancer cell surface antigen. In some aspects, the first target is a cancer cell surface antigen and the second target is a T cell antigen polypeptide. In some aspects, the T cell antigen polypeptide is the epsilon chain of CD 3.

In some aspects, the first polypeptide further comprises a heavy chain CH1 domain between the antigen targeting domain VH2 and the monomeric Fc domain.

In some aspects, the first polypeptide further comprises an immunoglobulin hinge region (HR 1) between the CH1 domain and the first monomeric Fc domain.

In some aspects, the first polypeptide comprises the following structural arrangement from amino terminus to carboxy terminus: MM1-CM1-scFv-VH2-CH1-HR1-Fc1, wherein each "-" is independently a direct or indirect linkage.

In some aspects of activatable HBPC described herein, the second polypeptide further comprises a light chain constant domain CL1. In some aspects, the second polypeptide comprises the following structural arrangement from amino terminus to carboxy terminus: MM2-CM2-VL2-CL1, wherein each "-" is independently a direct or indirect linkage.

In some aspects of activatable HBPC described herein, the third polypeptide further comprises an immunoglobulin hinge region (HR 2). In some aspects, the third polypeptide comprises the following structural arrangement from amino terminus to carboxy terminus: HR2-Fc2, wherein "-" is a direct or indirect linkage.

In some aspects of activatable HBPC described herein, the first polypeptide HR1 and the second polypeptide HR2 comprise the same amino acid sequence. In some aspects, the first polypeptide HR1 and the second polypeptide HR2 comprise different amino acid sequences.

In some aspects of activatable HBPC described herein, the first, second, and/or third polypeptides comprise one or more linkers.

In some aspects, a linker contained in one or more of the following positions may be activated HBPC: (a) between MMl and CMl; (b) between MM2 and CM 2; (b) Between the heavy and light variable domains of the scFv; (c) between the heavy chain variable domain and the CH1 domain; (d) between the CH1 domain and the hinge region; (e) between the hinge region and the Fc domain; (g) between CM2 and the light chain variable domain; (h) between the light chain variable domain and CL; (i) between the CH1 domain and the second Fc domain; (j) between the CH1 domain and the hinge region; and/or (k) between the hinge region and the second Fc domain. In some aspects, the linker comprises from about 1 to about 20 amino acids.

In some aspects of activatable HBPC described herein, MM1 is connected to CM1 via a linker L1. In some aspects, MM2 is connected to CM2 via a linker L2. In some aspects, the activatable bispecific polypeptide complex comprises both L1 and L2. In some aspects, MM2 is connected to CM2 via linker L3, and CM2 is connected to scFv via linker L4. In some aspects of the present invention,

In some aspects of activatable HBPC described herein, the amino acid sequences of L1, L2, L3, and/or L4 are identical. In some aspects, the amino acid sequence of at least one of L1, L2, L3, and/or L4 is different.

In some aspects of activatable HBPC described herein, the amino acid sequence of CM1 and the amino acid sequence of CM2 are identical. In some aspects, the amino acid sequence of CM1 and the amino acid sequence of CM2 are different.

In some aspects of activatable HBPC described herein, CM1 and CM2 each comprise a substrate for a protease present in the tumor microenvironment. In some aspects, CM1 and CM2 each independently comprise a substrate for the same protease. In some embodiments, CM1 and CM2 comprise substrates for different proteases. In some aspects, CM1 and CM2 each independently comprise a substrate for a protease selected from the group of proteases shown in table 3. In some aspects, at least one of CM1 and CM2 comprises a substrate for a protease selected from the group consisting of: serine proteases and Matrix Metallopeptidases (MMPs). In some aspects, CM1 and/or CM2 comprises the amino acid sequence of SEQ ID NO. 2, SEQ ID NO. 14, SEQ ID NO. 73-111 or SEQ ID NO. 156-159.

In some aspects of activatable HBPC described herein, MM1 and/or MM2 comprises from about 5 amino acids to about 40 amino acids.

In some aspects of activatable HBPC described herein, each linker is independently selected from the group consisting of: (i) A glycine-serine based linker selected from the group consisting of: (GS) n, wherein n is an integer of at least 1 and in some aspects, wherein n is an integer of between 1 and 10, (GGS) n, wherein n is an integer of at least 1 and in some aspects, wherein n is an integer of between 1 and 10, (GGGS) n (SEQ ID NO: 40), wherein n is an integer of at least 1 and in some aspects, wherein n is an integer of between 1 and 10, (GGGGS) n (SEQ ID NO: 126), wherein n is an integer of at least 1, (GSGGS) n (SEQ ID NO: 41), wherein n is an integer of at least 1 and in some aspects, wherein n is integers of between 1 and 10 ,GSSGGSGGSG(SEQ ID NO:12),GGSG(SEQ ID NO:42),GGSGG(SEQ ID NO:43),GSGSG(SEQ ID NO:44),GSGGG(SEQ ID NO:45),GGGSG(SEQ ID No:46) and GSSSG(SEQ ID NO:47),GGGGSGGGGSGGGGSGS(SEQ ID NO:48),GGGGSGS(SEQ ID NO:49),GGGGSGGGGSGGGGS(SEQ ID NO:50),GGGGSGGGGSGGGGSGGGGS(SEQ ID NO:51),GGGGS(SEQ ID NO:52),GGGGSGGGGS(SEQ ID NO:53),GGGS(SEQ ID NO:54),GGGSGGGS(SEQ ID NO:55),GGGSGGGSGGGS(SEQ ID NO:56),GSSGGSGGSGG(SEQ ID NO:57),GGGSGGGGSGGGGSGGGG SGGGGS(SEQ ID NO:58),GGGSSGGS(SEQ ID NO:127) and GS; and (ii) linkers comprising glycine and serine and at least one of lysine, threonine or proline, such as, for example, linkers ：GSTSGSGKPGSSEGST(SEQ ID NO:59)、SKYGPPCPPCPAPEFLG(SEQ ID NO:60)、GGSLDPKGGGGS(SEQ ID NO:61)、PKSCDKTHT CPPCPAPELLG(SEQ ID NO:62)、GKSSGSGSESKS(SEQ ID NO:63)、GSTSGSGKSSEGKG(SEQ ID NO:64)、GSTSGSGKSSEGSGSTKG(SEQ ID NO:65) and GSTSGSGKPGSGEGSTKG (SEQ ID NO: 66) selected from the group consisting of.

In some aspects of activatable HBPC described herein, the first polypeptide comprises a Hinge (HR) having the amino acid sequence of SEQ ID NO. 34 (hinge 1). In some aspects of activatable HBPC described herein, the second polypeptide comprises a Hinge (HR) having the amino acid sequence of SEQ ID NO. 35 (hinge 2).

Also provided herein are compositions comprising activatable HBPC as described herein and a pharmaceutically acceptable carrier. In some aspects, the composition comprises water and activatable HBPC. In some aspects, the composition comprises 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95% or up to 99% water.

Also provided herein are kits comprising the pharmaceutical compositions described herein.

Also disclosed herein are nucleic acids comprising nucleotide sequences encoding the first, second, and/or third polypeptides described herein that can activate HBPC. In some aspects, a nucleic acid comprising a nucleotide sequence encoding a first polypeptide that is activatable HBPC is provided. In some aspects, nucleic acids comprising a nucleotide sequence encoding a second polypeptide that can activate HBPC are provided. In some aspects, a nucleic acid comprising a nucleotide sequence encoding a third polypeptide that is activatable HBPC is provided. Also provided herein are vectors comprising the nucleic acids described herein. Also provided herein are host cells comprising the vectors described herein.

Also provided herein are methods of producing activatable bispecific polypeptide complexes, the methods comprising: (a) Culturing the host cell in a liquid medium under conditions sufficient to produce said activatable HBPC; and (b) recovering the activatable HBPC.

Also provided herein are methods of treating a disease in a subject, the method comprising administering to the subject a therapeutically effective amount of an activatable Heteromultimeric Bispecific Polypeptide Complex (HBPC) or a pharmaceutical composition thereof. In some aspects, the subject is a human. In some aspects, the disease is cancer.

Also provided herein are activatable Heteromultimeric Bispecific Polypeptide Complexes (HBPC) and pharmaceutical compositions thereof for use in inhibiting tumor growth in a subject in need thereof.

Also provided herein are activatable Heteromultimeric Bispecific Polypeptide Complexes (HBPC) and pharmaceutical compositions thereof for use in the manufacture of a medicament for the treatment of cancer.

Also provided herein is an activatable Heteromultimeric Bispecific Polypeptide Complex (HBPC) comprising: (a) A first polypeptide comprising (i) a single chain variable fragment (scFv), wherein the scFv comprises a first heavy chain variable domain (VH 1) and a first light chain variable domain (VL 1), wherein VH1 and VL1 together form a T cell antigen targeting domain that specifically binds a T cell antigen polypeptide, (ii) a first masking moiety (MM 1), and (iii) a first cleavable moiety (CM 1); (iii) A heavy chain variable domain (VH 2) that specifically binds a cancer cell surface antigen when paired with a light chain variable domain (VL 2), (iv) a first monomeric Fc domain (Fc 1), (v) a heavy chain CH1 domain, and (vi) an immunoglobulin hinge region between the CH1 domain and the Fc 1; (b) A second polypeptide comprising (i) a light chain variable domain (VL 2) that specifically binds a cancer cell surface antigen when paired with VH2, (ii) a second masking moiety (MM 2), (iii) a second cleavable moiety (CM 2), and (iv) a light chain constant domain CL1; and (c) a third polypeptide comprising a second monomeric Fc domain (Fc 2) and an immunoglobulin hinge region (HR 2), wherein the third polypeptide does not comprise an immunoglobulin variable domain, and; wherein the first polypeptide comprises the following structural arrangement from amino terminus to carboxy terminus: MM1-CM1-scFv1-VH2-CH1-HR1-Fc1, the second polypeptide comprising from amino terminus to carboxy terminus the following structural arrangement: MM2-CM2-VL2-CL1, and the third polypeptide has the following structural arrangement from amino terminus to carboxy terminus: HR2-Fc2, wherein each "-" is independently a direct or indirect linkage.

Also provided herein is an activatable Heteromultimeric Bispecific Polypeptide Complex (HBPC) comprising: (a) A first polypeptide comprising (i) a single chain variable fragment (scFv) that specifically binds a cancer cell surface antigen, (ii) a first masking moiety (MM 1), (iii) a first cleavable moiety (CM 1); and (iv) a heavy chain variable domain (VH 2) that binds a T cell antigen polypeptide when paired with a second polypeptide light chain variable domain (VL 2), (v) a first monomeric Fc domain (Fc 1), (vi) a heavy chain CH1 domain, and (vii) an immunoglobulin hinge region (HR 1) between the CH1 domain and the first monomeric Fc domain; (b) A second polypeptide comprising (i) a light chain variable domain (VL 2) of a specific binding T cell antigen polypeptide when paired with the first polypeptide VH2, (ii) a second masking moiety (MM 2), (iii) a second cleavable moiety (CM 2) and (iv) a light chain constant domain CL1; and (c) a third polypeptide comprising a second monomeric Fc domain (Fc 2) and an immunoglobulin hinge region (HR 2); wherein the first polypeptide comprises the following structural arrangement from amino terminus to carboxy terminus: MM1-CM1-scFv1-VH2-CH1-HR1-Fc1, the second polypeptide comprising from amino terminus to carboxy terminus the following structural arrangement: MM2-CM2-VL2-CL1, and the third polypeptide has the following structural arrangement from amino terminus to carboxy terminus: HR2-Fc2, wherein each "-" represents a direct or indirect linkage, and wherein the third polypeptide does not comprise an immunoglobulin variable domain.

Also provided herein is an activatable Heteromultimeric Bispecific Polypeptide Complex (HBPC) comprising: (a) A first polypeptide comprising (i) a single chain variable fragment (scFv) that specifically binds a cancer cell surface antigen, (ii) a first masking moiety (MM 1), and (iii) a first cleavable moiety (CM 1); and a heavy chain variable domain (VH 2), (iii) a first monomeric Fc domain (Fc 1), a heavy chain CH1 domain, and an immunoglobulin hinge region between the CH1 domain and the first monomeric Fc domain; (b) A second polypeptide comprising (i) a light chain variable domain (VL 2) of a specific binding T cell antigen polypeptide when paired with the first polypeptide VH2, (ii) a second masking moiety (MM 2), (iii) a second cleavable moiety (CM 2) and a light chain constant domain CL1; and (c) a third polypeptide comprising a second monomeric Fc domain (Fc 2) and an immunoglobulin hinge region; wherein the first polypeptide has the following structural arrangement from amino terminus to carboxy terminus: MM1-CM1-scFv1-VH2-CH1-HR1-Fc1; the second polypeptide has the following structural arrangement from amino terminus to carboxy terminus: MM2-CM2-VL2-CL1, and the third polypeptide has the following structural arrangement from amino terminus to carboxy terminus: HR2-Fc2, wherein each "-" is independently a direct or indirect linkage, and wherein the third polypeptide does not comprise an immunoglobulin variable domain.

Also provided herein is a Heteromultimeric Bispecific Polypeptide Complex (HBPC) comprising: (a) A first polypeptide comprising (i) a single chain variable fragment (scFv) comprising a first heavy chain variable domain (VH 1) and a first light chain variable domain (VL 1), wherein the VH1 and the VL1 together form a first targeting domain that specifically binds a first target, (ii) a second heavy chain variable domain (VH 2), and (iii) a first monomeric Fc domain (Fc 1); (b) A second polypeptide comprising a second light chain variable domain (VL 2), wherein the VH2 and the VL2 together form a second targeting domain that specifically binds a second target; and (c) a third polypeptide comprising a second monomeric Fc domain (Fc 2) and not comprising an immunoglobulin variable domain.

Drawings

Fig. 1 is a schematic diagram of activatable HBPC as described herein.

Figure 2A shows CI106 (activatable dual arm, bivalent anti-CD 3, anti-EGFR bispecific antibody control), complex-57 (activatable HBPC) and complex-67 (activatable HBPC) and binding of activated CI106, activated complex-57 and activated complex-67 to EGFR.

FIG. 2B shows CI106 (control), complex-57 (activatable HBPC), complex-67 (activatable HBPC), and binding of activated CI106, activated Complex-57, and activated Complex-67 to CD 3.

Figure 3A shows cytotoxicity on HT29 cells after treatment with activated CI106 (control), complex-57 and complex-67, and CI106 (double arm, bivalent bispecific control construct) and complex-57.

FIG. 3B shows cytotoxicity on HT29 cells after treatment with CI106 (control), complex-67, activated CI106 (control), and activated complex-67.

FIG. 4 shows tumor volumes over time in HT29-luc2 xenograft tumor models following treatment with vehicle, 1.0mg/kg CI106 (control), and 0.2, 0.6, and 1.8mg/kg complex-67.

Figure 5 shows tumor volumes over time in HCT116 xenograft tumor models following treatment with vehicle, 0.3mg/kg and 1mg/kg activated complex-67 and complex-67.

FIG. 6 shows the percent (%) of monomer versus concentration for CI106 (control), complex-57, and complex-67.

FIG. 7 shows cytotoxicity (as a percentage of cell lysis) of masked activatable HBPC (complex-339), unmasked activatable HBPC control (complex-342), activatable polypeptide in alternative form 2 (complex-231), and unmasked control polypeptide in alternative form 2 (complex-164).

Figures 8A-8C show flow cytometry evaluation of binding of CI107 to EGFR and CD3 expressed on the surface of HT29 cells (a), HCT116 cells (B) or Jurkat cells (C). Apparent Kd was calculated by duplicate experiments in HT29 cells and triplicate experiments in Jurkat cells.

FIGS. 9A-9D show the percent cytotoxicity mediated by CI107 in HCT116-Luc2 cells (A, C) and HT29-Luc2 cells (B, D). After 48 hours of incubation, HCT116-Luc2 or HT29-Luc2 cell viability and cytotoxicity were measured relative to untreated controls (A, B). After 16 hours of incubation, CD69 expression was measured by flow cytometry. MFI, average fluorescence intensity (C, D).

FIGS. 10A-10E show cytokine release measured after 16 hours of incubation after treatment with CI 107. (A) IFN-gamma, (B) IL-2, (C) IL-6, (D) MCP-1, and (E) TNF-alpha.

FIGS. 11A-11B show tumor volumes after treatment with test TCB in mice bearing HT29-Luc2 tumors and transplanted with human PBMC. (A) Mice were treated once a week for 3 weeks (n=8 per group) with vehicle (PBS) or 0.3mg/kg CI020, CI011, CI040, or CI 048. Tumor volumes were measured twice weekly. (B) NSG mice bearing HT29-Luc2 tumors and transplanted with human PBMCs were treated with vehicle or 1mg/kg of CI020, CI011, CI040 or CI 048. Tumors were harvested 7 days after dosing and immunohistochemistry for CD3 was performed. Dark staining indicated cd3+ cells.

Figures 12A-12B show tumor volumes after treatment with CI107 once a week for 3 weeks in HT29 (a) and HCT116 (B) xenograft tumors. Tumor volumes were measured twice weekly. * p <0.5; * P <0.01; * P <0.0001.

FIGS. 13A-13B show IL-6 (A) and IFN-gamma (B) levels measured 8 hours after administration of CI 107.

Fig. 13C shows the level (C) of aspartate Aminotransferase (AST) measured by serum chemistry analysis 48 hours after administration of CI 107.

FIG. 13D shows plasma concentrations of Act-CI107 and CI107 measured by ELISA using anti-idiotype capture and anti-human Fc detection. The CI107 line represents data from 3 individual animals given 2.0mg/kg CI 107; act-TCB line represents individual animals given 0.06mg/kg or 0.18mg/kg of Act-TCB.

Detailed Description

In order that the present disclosure may be more readily understood, certain terms are first defined. As used in the present application, each of the following terms shall have the meanings set forth below, unless the context clearly dictates otherwise. Additional definitions are set forth throughout this application.

Definition of the definition

As used herein, the term "activatable polypeptide complex" refers to a polypeptide having at least one variable heavy domain and at least one variable light domain that together form an antigen binding region, a Masking Moiety (MM) and a Cleavable Moiety (CM), wherein the MM is linked to the antigen binding region (directly or indirectly) by the CM, which CM is cleavable by a protease.

When used in conjunction with the term "heteromultimeric bispecific polypeptide complex" or "HBPC", the term "activatable" refers herein to HBPC whose binding activity is compromised by the presence of one or more masking moieties attached to the structure of HBPC. The terms "activated" and "act-" may both be used to refer to activated HBPC. The terms "activated" and "unmasked" are used interchangeably herein.

The term "polypeptide" as used herein refers to the generic term for polymers of amino acid residues.

The term "T cell" as used herein is defined as a lymphocyte of thymic origin that is involved in a variety of cell-mediated immune responses. The term "regulatory T cell" as used herein refers to a CD4 ⁺CD25⁺FoxP3⁺ T cell having inhibitory properties. "Treg" is an abbreviation for regulatory T cells used herein.

The term "helper T cell" as used herein refers to a CD4 ⁺ T cell. Helper T cells recognize antigens that bind to MHC class II molecules. There are at least two types of helper T cells: th ₁ and Th ₂, which produce different cytokines. Helper T cells become CD25 ⁺ upon activation, but only transiently become FoxP3 ⁺.

The term "cytotoxic T cell" as used herein refers to a CD8 ⁺ T cell. Cytotoxic T cells recognize antigens that bind to MHC class I molecules.

The term "variable region" or "variable domain" refers to a domain of an antigen binding protein (e.g., an antibody) heavy or light chain that is involved in binding the antigen to an antigen. The variable regions or domains (VH and VL, respectively) of antigen binding proteins such as heavy and light chains of antibodies may be further subdivided into regions of hypervariability (regions of hypervariability) (or hypervariability (hypervariable region), which may be hypervariable in sequence and/or form structurally defined loops), such as hypervariability regions (HVRs) or Complementarity Determining Regions (CDRs) interspersed with regions that are more conserved, referred to as Framework Regions (FR). In general, there are 3 HVRs (HVR-H1, HVR-H2, HVR-H3) or CDRs (CDR-H1, CDR-H2, CDR-H3) in each heavy chain variable region, and 3 HVRs (HVR-L1, HVR-L2, HVR-L3) or CDRs (CDR-L1, CDR-L2, CDR-L3) in each light chain variable region. "framework region" and "FR" are known in the art to refer to the non-HVR or non-CDR portions of the variable regions of the heavy and light chains. In general, there are 4 FRs (FR-H1, FR-H2, FR-H3 and FR-H4) in each full-length heavy chain variable region, and 4 FRs (FR-L1, FR-L2, FR-L3 and FR-L4) in each full-length light chain variable region. Within each VH and VL, three HVRs or CDRs and four FRs are typically arranged from amino-terminus to carboxy-terminus in the following order: FR1, HVR1, FR2, HVR2, FR3, HVR3, FR4 in the case of HVR, or FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4 in the case of CDR (see also Chothia and Lesk j.mot.biol.,195,901-917 (1987)). A single VH or VL domain may be sufficient to confer antigen binding specificity. In addition, antibodies that bind a particular antigen can be isolated using VH or VL domains from antibodies that bind the antigen to screen libraries of complementary VL or VH domains, respectively. See, for example, portolano et al J.Immunol.150:880-887 (1993); clarkson et al Nature 352:624-628 (1991).

The term "heavy chain variable region" (VH) as used herein refers to a region comprising heavy chains HVR-H1, FR-H2, HVR-H2, FR-H3 and HVR-H3. For example, the heavy chain variable region may comprise heavy chains CDR-H1, FR-H2, CDR-H2, FR-H3 and CDR-H3. In some aspects, the heavy chain variable region further comprises at least a portion of FR-H1 and/or at least a portion of FR-H4.

The term "heavy chain constant region" as used herein refers to a region comprising at least three heavy chain constant domains C _H1、C_H and C _H. Non-limiting exemplary heavy chain constant regions include gamma, delta, and alpha. Non-limiting exemplary heavy chain constant regions also include epsilon and mu.

The term "light chain variable region" (VL) as used herein refers to a region comprising light chains HVR-L1, FR-L2, HVR-L2, FR-L3 and HVR-L3. In some aspects, the light chain variable region comprises light chains CDR-L1, FR-L2, CDR-L2, FR-L3 and CDR-L3. In some aspects, the light chain variable region further comprises FR-L1 and/or FR-L4.

The term "light chain constant region" as used herein refers to a region comprising light chain constant domain C _L. Non-limiting exemplary light chain constant regions include lambda and kappa.

The term "light chain" (LC) as used herein refers to a polypeptide comprising at least a light chain variable region with or without a leader sequence. In some aspects, the light chain comprises at least a portion of a light chain constant region. The term "full length light chain" as used herein refers to a polypeptide comprising a light chain variable region and a light chain constant region, with or without a leader sequence.

The term "antibody" refers to an immunoglobulin molecule or an immunologically active portion of an Immunoglobulin (IG) molecule, i.e., a molecule that contains an antigen binding site that specifically binds (immunoreacts with) an antigen. An "antigen binding portion" (also referred to as an "antigen binding fragment") of an antibody or polypeptide refers to one or more portions of the antibody or polypeptide that specifically bind to a target antigen. Antibodies and antigen binding portions include, but are not limited to, polyclonal antibodies, monoclonal antibodies, chimeric antibodies, domain antibodies, single chain antibodies, fab and F (ab') ₂ fragments, scFv, fd fragments, fv fragments, single domain antibody (sdAb) fragments, dual affinity re-targeting antibodies (DARTs), dual variable domain immunoglobulins; isolated Complementarity Determining Regions (CDRs), and combinations of two or more isolated CDRs, optionally linked by a synthetic linker, and Fab expression libraries. Non-human antibodies (e.g. camelidae antibodies) may be humanised by recombinant means to reduce their immunogenicity in humans.

The CDR sequences specified herein are determined according to the Kabat numbering system (i.e., "Kabat CDRs") as described in Abhinandan, k.r. and Martin,A.C.R.(2008)"Analysis and improvements to Kabat and structural ly correct numbering of antibody variabledomains",Molecular Immunology,45,3832-3839, which are incorporated herein by reference in their entirety. The Kabat CDR is defined as CDR-L1: residues L24-L34; CDR-L2: residues L50-L56; CDR-L3: residues L89-L97; CDR-H1: residues H31-H35; CDR-H2: residues H50-H65; and CDR-H3: residues H95-H102, wherein "L" refers to the light chain variable domain and "H" refers to the heavy chain variable domain.

By "specific binding" or "immunospecific binding" is meant that the targeting domain, antibody or antigen binding fragment reacts with one or more epitopes of the desired antigen and does not react with other polypeptides or binds with much lower affinity (Kd >10 ^-6), where a smaller Kd represents a greater affinity. Methods well known in the art can be used to quantify the immunological binding properties of a selected polypeptide. One such method requires measuring the rate of antigen binding site/antigen complex formation and dissociation, where those rates depend on the concentration of the complexing partners, the affinity of the interactions, and geometric parameters that affect the rates equally in both directions. Thus, the "association rate constant" (k _on) and "dissociation rate constant" (k _off) can be determined by calculating the concentration and the actual rate of association and dissociation. (see Nature 361:186-87 (1993)). The ratio of k _off/k_on allows to cancel all parameters independent of affinity and is equal to the dissociation constant Kd. (see generally, davies et al (1990) Annual Rev Biochem 59:439-473). In some aspects, the antigen targeting domain, antibody or antigen binding fragment that specifically binds to its corresponding antigen exhibits a Kd of less than about 10 μm, and in some aspects less than about 100 μm, relative to the target antigen.

The immunoglobulin may be derived from any known isotype, including but not limited to IgA, secretory IgA, igG, and IgM. Subclasses of IgG are also well known to those skilled in the art and include, but are not limited to, human IgG1, igG2, igG3, and IgG4. "isotype" refers to the class or subclass of antibodies (e.g., igM or IgG 1) encoded by the heavy chain constant region gene.

An "anti-antigen" antibody or polypeptide refers to an antibody or polypeptide that specifically binds to an antigen. For example, an anti-CD 3 polypeptide specifically binds to CD3.

As used herein, the terms "MM" and "masking moiety" are used interchangeably to refer to a peptide that interferes with the binding of a targeting domain to its corresponding antigen. For example, MM1 is a peptide that interferes with the binding of a first targeting domain to a first target, and MM2 is a peptide that interferes with the binding of a second targeting domain to a second target. The extent to which the masking moiety interferes with the binding of the targeting domain to its corresponding target is quantified by its "masking efficiency". The terms "masking efficiency" and "ME" are used interchangeably herein to refer to the ratio determined as follows:

as used herein, the terms "CM" and "cleavable moiety" are used interchangeably to refer to a peptide that is susceptible to cleavage by a protease. Protease-mediated CM cleavage results in release of the MM from the activatable HBPC structure, thereby generating an "activated" (i.e., unmasked) product, wherein each respective "activated" (i.e., unmasked) first and/or second targeting domain is free to bind to its respective target.

The term "isolated polynucleotide" as used herein refers to a recombinant polynucleotide or a polynucleotide of synthetic origin that is (1) not associated with all or a portion of a polynucleotide where the "isolated polynucleotide" is found in nature, according to its source, (2) operably linked to a polynucleotide where it is not linked in nature, or (3) not found in nature as part of a larger sequence. Polynucleotides according to the present disclosure include nucleic acid molecules encoding the first, second and third polypeptides.

The term "operably linked" as used herein means that the components described are in a relationship permitting them to function in their intended manner. A control sequence "operably linked" to a coding sequence is linked in a manner such that expression of the coding sequence is achieved under conditions compatible with the control sequence.

As discussed herein, minor variations in the amino acid sequences described herein (i.e., each reference sequence) are considered to be encompassed by the present disclosure, provided that the resulting analog sequence retains at least 75%, more preferably at least 80%, 90%, 95% and most preferably 99% sequence identity to the reference sequence. In particular, conservative amino acid substitutions are contemplated. Conservative substitutions are those that occur within the family of amino acids of interest in terms of the nature of their side chains. Amino acids can be divided into the following families: (1) the acidic amino acid is aspartic acid, glutamic acid; (2) The basic amino acid is lysine, arginine, histidine; (3) The nonpolar amino acids are alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan; and (4) the uncharged polar amino acids are glycine, asparagine, glutamine, cysteine, serine, threonine, tyrosine. Hydrophilic amino acids include arginine, asparagine, aspartic acid, glutamine, glutamic acid, histidine, lysine, serine, and threonine. Hydrophobic amino acids include alanine, cysteine, isoleucine, leucine, methionine, phenylalanine, proline, tryptophan, tyrosine and valine. Other amino acid families include (i) serine and threonine, which are aliphatic-hydroxy families; (ii) Asparagine and glutamine, which are amide-containing families; (iii) Alanine, valine, leucine and isoleucine, which are aliphatic families; and (iv) phenylalanine, tryptophan, and tyrosine, which are aromatic families. For example, in the polypeptides and polypeptide complexes described herein, it is reasonably expected that the isolated replacement of leucine with isoleucine or valine, the isolated replacement of aspartic acid with glutamic acid, the isolated replacement of threonine with serine, or the similar replacement of an amino acid with a structurally related amino acid will not have a significant impact on the binding or properties of the resulting molecule, particularly where the replacement does not involve amino acids within the CDR or framework regions. Whether an amino acid change results in a functional polypeptide complex can be readily determined by measuring the specific activity of the resulting molecule (i.e., the resulting analog sequence). Assays are described in detail herein. Preferred amino and carboxyl termini of the analogs occur near the boundaries of the functional domain. Structural and functional domains can be identified by comparing nucleotide and/or amino acid sequence data to public or proprietary sequence databases. Preferably, computerized comparison methods are used to identify sequence motifs or predicted protein conformational domains that occur in other proteins having known structure and/or function. Methods for identifying protein sequences folded into a known three-dimensional structure are known. See, e.g., bowie et al Science 253:164 (1991). Thus, the foregoing examples demonstrate that, in light of the present disclosure, one of skill in the art can identify sequence motifs and structural conformations that can be used to define structural and functional domains.

Conservative amino acid substitutions should not substantially alter the structural characteristics of the reference sequence (e.g., the replacement amino acids should not tend to disrupt the helix present in the reference sequence, or disrupt other types of secondary structures that characterize the reference sequence). Examples of art-recognized secondary and tertiary structures of polypeptides are described in Proteins, structures and Molecular Principles (Cright on, eds., W.H. Freeman and Company, new York (1984)); introduct ion to Protein Structure (c.branden and j.toole editions, garland Publ ishing, new York, n.y. (1991)); and Thornton et al Nature 354:105 (1991).

Exemplary amino acid substitutions also include those of: (1) reducing susceptibility to proteolysis in regions of the activatable polypeptide other than in the cleavable linker comprising CM, (2) reducing susceptibility to oxidation, (3) altering the binding affinity for forming a protein complex, (4) altering the binding affinity to an antigen, and (4) conferring or modifying other physicochemical or functional properties of such analogs. Such amino acid substitutions can be identified using known mutagenesis methods and/or directed molecular evolution methods using the assays described herein. See, for example, international publication No. WO 2001/032672, U.S. patent No. 7,432,083, U.S. publication No. 2004/0180340, and U.S. patent No. 6,297,053, each of which is incorporated herein by reference. Analogs can be prepared by introducing one or more mutations in the reference sequence within activatable HBPC. For example, single or multiple amino acid substitutions may be made in a naturally occurring reference sequence (preferably in the portion of the polypeptide outside of the domain that forms intermolecular contacts).

As used herein, "pharmaceutically acceptable" or "pharmacologically compatible" means that the material is not biologically or otherwise undesirable, e.g., the material may be incorporated into a pharmaceutical composition for administration to an individual or subject without causing any significant undesirable biological effects or interacting in a deleterious manner with any of the other components of the composition in which it is contained. Pharmaceutically acceptable carriers or excipients, for example, meet the criteria required for toxicological and manufacturing testing, and/or are included in the inactive ingredient guidelines (INACTIVE INGREDIENT Guide) established by the U.S. food and drug administration.

As used herein, "patient" includes any patient with cancer. The terms "subject" and "patient" are used interchangeably herein.

The term "cancer," "cancerous," or "malignant" refers to or describes a physiological condition in a mammal that is typically characterized by unregulated cell growth. Examples of cancers include, for example, melanomas such as unresectable or metastatic melanomas, leukemias, lymphomas, blastomas, carcinomas and sarcomas. More specific examples of such cancers include chronic myelogenous leukemia, acute lymphoblastic leukemia, philadelphia chromosome positive acute lymphoblastic leukemia (ph+all), squamous cell carcinoma, small cell lung carcinoma, non-small cell lung carcinoma, glioma, gastrointestinal cancer, renal cancer, ovarian cancer, liver cancer, colorectal cancer, endometrial cancer, renal cancer, prostate cancer, thyroid cancer, neuroblastoma, pancreatic cancer, glioblastoma multiforme, cervical cancer, gastric cancer, bladder cancer, liver cancer, breast cancer, colon cancer, and head and neck cancer, gastric cancer, germ cell tumor, pediatric sarcoma, natural killer cells of the sinuses, multiple myeloma, acute Myelogenous Leukemia (AML), and chronic lymphocytic leukemia (CML).

The term "tumor" as used herein refers to any mass of tissue produced by excessive cell growth or proliferation, benign (non-cancerous) or malignant (cancerous), including pre-cancerous lesions.

"Administering" refers to physically introducing a composition comprising a therapeutic agent into a subject using any of a variety of methods and delivery systems known to those of skill in the art. Routes of administration of the formulations disclosed herein include intravenous, intramuscular, subcutaneous, intraperitoneal, spinal or other parenteral routes of administration, for example by injection or infusion. The phrase "parenteral administration" as used herein means modes of administration other than enteral and topical administration, typically by injection, and includes, but is not limited to, intravenous, intramuscular, intraarterial, intrathecal, intralymphatic, intralesional, intracapsular, intraorbital, intracardiac, intradermal, intraperitoneal, transtracheal, subcutaneous, subcuticular, intra-articular, subcapsular, subarachnoid, intraspinal, epidural and intrasternal injection and infusion, and in vivo electroporation. In some aspects, the formulation is administered by a non-parenteral route, and in some aspects orally. Other non-parenteral routes include topical, epidermal or mucosal routes of administration, such as intranasal, vaginal, rectal, sublingual or topical administration. Administration may also be performed, for example, once, multiple times, and/or over one or more extended periods of time.

"Treatment" or "therapy" of a subject refers to any type of intervention or treatment performed on the subject or administration of an active agent to the subject with the purpose of reversing, alleviating, ameliorating, inhibiting, slowing the progression, development, severity, or recurrence of symptoms, complications or disorders or biochemical indicators associated with the disease.

As used herein, "effective treatment" refers to treatment that produces a beneficial effect, such as ameliorating at least one symptom of a disease or disorder. The beneficial effect may be in the form of an improvement over baseline, i.e., an improvement over the measured or observed results obtained prior to initiation of treatment according to the method. The beneficial effects may also take the form: inhibit, slow, delay or stabilize the adverse progression of tumor markers. An effective treatment may refer to alleviation of at least one symptom associated with cancer. Such effective treatment may, for example, reduce pain in the patient, reduce the size and/or number of lesions, may reduce or prevent metastasis of a tumor, and/or may slow down tumor growth.

The term "effective amount" refers to the amount of an agent that provides a desired biological, therapeutic, and/or prophylactic result. The result may be a reduction, improvement, alleviation, delay and/or relief of one or more of the signs, symptoms, or causes of a disease, or any other desired alteration of a biological system. With respect to solid tumors, an effective amount includes an amount sufficient to cause shrinkage of the tumor and/or to reduce the growth rate of the tumor (such as inhibiting tumor growth) or delay other unwanted cell proliferation. In some aspects, an effective amount is an amount sufficient to prevent or delay tumor recurrence. The effective amount may be administered in one or more administrations. An effective amount of the drug or composition may: (i) reducing the number of cancer cells; (ii) reducing tumor size; (iii) Inhibit, delay, slow to some extent, and can stop cancer cell infiltration into peripheral organs; (iv) Inhibit (i.e., slow down to some extent and can stop) tumor metastasis; (v) inhibiting tumor growth; (vi) preventing or delaying the onset and/or recurrence of a tumor; and/or (vii) alleviate to some extent one or more symptoms associated with cancer.

By "immune response" is meant the action of cells of the immune system (e.g., T lymphocytes, B lymphocytes, natural Killer (NK) cells, macrophages, eosinophils, mast cells, dendritic cells, and neutrophils) and soluble macromolecules (including antibodies, cytokines, and complements) produced by any of these cells or liver, spleen, and/or bone marrow, which results in the selective targeting, binding, injury, destruction, and/or clearance of an invading pathogen, pathogen-infected cell or tissue, cancer cell or other abnormal cell, or normal human cell or tissue in the case of autoimmune or pathological inflammation.

Schematic representations (e.g., fig. 1) of activatable polypeptides of the present disclosure are not intended to be exclusive. Other sequence elements (such as linkers, spacers, and signal sequences) may be present before, after, or between the sequence elements listed in such schematics. It will also be appreciated that MM and CM may be linked to the VH of an antibody or polypeptide rather than to the VL of an antibody or polypeptide, and vice versa.

Use of an alternative (e.g., "or") is understood to mean any one, two, or any combination thereof, of a plurality of alternatives. As used herein, the indefinite article "a/an" is to be understood to mean "one or more" of any recited or enumerated ingredients.

The term "and/or" as used herein shall be taken to mean a specific disclosure of each of two specified features or components, with or without the other. Thus, the term "and/or" as used in phrases such as "a and/or B" herein is intended to include "a and B", "a or B", "a" (alone) and "B" (alone). Also, use of the term "and/or" as in a phrase such as "A, B and/or C" is intended to include each of the following: A. b and C; A. b or C; a or C; a or B; b or C; a and C; a and B; b and C; a (alone); b (alone); and C (alone).

It should be understood that wherever aspects are described herein by the expression "comprising/including (compris ing)", other similar aspects described as "consisting of … …" and/or "consisting essentially of … …" are also provided.

The term "about" refers to a value or composition of a particular value or composition that is within acceptable error as determined by one of ordinary skill in the art, which will depend in part on how the value or composition is measured or determined, i.e., the limitations of the measurement system. For example, "about" or "substantially comprising" may mean within 1 or more than 1 standard deviation according to convention in the art. Alternatively, "about" or "substantially comprising" may mean a range of up to 10% or 20% (i.e., ±10% or ±20%). For example, about 3mg may include any number between 2.7mg and 3.3mg (for 10%) or between 2.4mg and 3.6mg (for 20%). Furthermore, in particular with respect to biological systems or methods, the term may mean at most one order of magnitude or at most 5 times the value. When a particular value or composition is provided in the application and claims, unless otherwise indicated, the meaning of "about" should be assumed to be within an acceptable error range for the particular value or composition.

As described herein, unless otherwise indicated, any concentration range, percentage range, ratio range, or integer range should be understood to include any integer value within the recited range and to include fractions thereof (e.g., tenths and hundredths of integers) as appropriate.

Unless defined otherwise, 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 disclosure pertains. For example the Concise Dictionary of Biomedicine and Molecular Biology, juo, pei-Show, 2 nd edition, 2002, CRC Press; the Dictionary of Celland Molecular Biology, 5 th edition, 2013,Academic Press; and the Oxford Dictionary Of Biochemistry And Molecular Biology,2006,Oxford University Press provide a comprehensive dictionary of many of the terms used in the present disclosure to the technician.

Units, prefixes, and symbols are expressed in terms of their international units system (Syst degrees me International de Unites, SI). Numerical ranges include numbers defining the range. The headings provided herein are not limitations of the various aspects of the disclosure which can be had by reference to the specification as a whole. Thus, the terms defined above are more fully defined by reference to the specification as a whole.

Aspects of the disclosure are described in more detail in the following subsections.

Activatable Heteromultimeric Bispecific Polypeptide Complex (HBPC)

The present disclosure provides activatable heteromultimeric bispecific polypeptide complexes comprising:

(a) A first polypeptide comprising:

(i) A single chain variable fragment (scFv), wherein said scFv comprises a first heavy chain variable domain (VH 1) and a first light chain variable domain (VL 1), wherein VH1 and VL1 together form a first targeting domain that specifically binds a first target,

(Ii) A first masking section (MM 1),

(Iii) A first cleavable moiety (CM 1), said first cleavable moiety comprising a first substrate for a first protease,

(Iv) A second heavy chain variable domain (VH 2), and

(V) A first monomeric Fc domain (Fc 1);

(b) A second polypeptide comprising:

(i) A second light chain variable domain (VL 2), wherein VH2 and VL2 together form a second targeting domain that specifically binds a second target,

(Ii) A second masking portion (MM 2), and

(Iii) A second cleavable moiety (CM 2) comprising a second substrate for a second protease; and

(C) A third polypeptide comprising:

(i) A second monomer Fc domain (Fc 2),

Wherein the third polypeptide does not comprise an immunoglobulin variable domain; and

Wherein MM1 is a peptide that interferes with binding of the first targeting domain to the first target and MM2 is a peptide that interferes with binding of the second targeting domain to the second target.

In some aspects, activatable HBPC of the present disclosure selectively activates under conditions more prevalent in the tumor microenvironment. However, the ability to bind its target is compromised before such activation occurs. Thus, activatable bispecific antibodies of the present disclosure (i.e., activatable HBPC) have the potential to reduce target-related toxicity by minimizing off-target binding. Structurally, the activatable HBPC of the present disclosure has only one binding domain (i.e., "monovalent") for each target. Furthermore, these activatable HBPC do not appear to exhibit significant concentration-dependent aggregation, thus making it possible to manufacture activatable HBPC (activatable bispecific antibodies) at relatively high product purity and high productivity levels.

In some aspects, the first polypeptide comprises the following structural arrangement from amino terminus to carboxy terminus: MM1-CM1-scFv-VH2-Fc1, wherein each "-" is independently a direct or indirect linkage. As used herein, "direct linkage" refers to direct conjugation of two peptides of HBPC, and "indirect linkage" refers to conjugation using a linking molecule, such as a spacer or linker. As shown below, activatable HBPC having the above structure advantageously exhibits increased activity (when activated) and masking efficiency, as well as improved anti-aggregation properties, as compared to activatable bispecific antibodies having alternative structures.

In some aspects, one of the first and second targets is a surface antigen on an immune effector cell, such as, for example, a leukocyte, such as on a T cell, on a Natural Killer (NK) cell, on a mononuclear effector cell (such as, for example, a bone marrow monocyte), on a macrophage, and/or on another immune effector cell. As used herein, the terms "target" and "antigen" are used interchangeably. Suitable immune effector cell targets include, for example, CD3, CD27, CD28, GITR, HVEM, ICOS, NKG2D, OX, and the like. In some aspects of the disclosure, at least one of the first target and the second target is CD3. In certain aspects, the first target is CD3.

In certain aspects, the first target and the second target are different biological targets, and accordingly, the first targeting domain (i.e., VL1 and VH 1) and the second targeting domain (i.e., VL2 and VH 2) are different. In some aspects, one of the first target and the second target is a CD3 polypeptide (and accordingly, one of the first targeting domain and the second targeting domain is a CD3 polypeptide targeting domain). In some aspects, the single chain variable fragment (scFv) comprises VH1 and VL1 that together form a first targeting domain of a T cell antigen polypeptide (i.e., a first target) and VH2 and VL2 that together form a second targeting domain of a cancer cell surface antigen, such as, for example, a tumor-associated antigen or a tumor-specific antigen (i.e., a second target). Exemplary cancer cell surface antigens include, but are not limited to: EGFR (epidermal growth factor receptor); a PSA; PAP; CEA; AFP; HCG; LDH; enolase 2; CA 15-3 and CA 27.29, exemplary targets are provided in Table 1. In other aspects, the single chain variable fragment (scFv) comprises VH1 and VL1 that together form a first targeting domain of a cancer cell surface antigen (i.e., a first target) and VH2 and VL2 that together form a second targeting domain of a T cell antigen polypeptide.

Table 1: exemplary targets

In one aspect, the cancer cell antigen is a growth factor receptor. Growth factor receptors are receptors that bind growth factors. Growth factors are naturally occurring substances that are capable of stimulating cell growth. There are many different types of growth factors including adrenomedullin, epidermal growth factor, fibroblast growth factor, hepatocyte growth factor, transforming growth factor and tumor necrosis factor. Each type of growth factor has a particular function or cellular process that it can aid in regulation. The growth factor receptor domain is cysteine-rich and is present in a variety of eukaryotic proteins. The receptor is involved in signal transduction by enzymes such as tyrosine kinases. Although there are different types of growth factor receptors, they have a general structure that contains a growth factor receptor domain that acts as a disulfide-binding fold containing a β -hairpin with two adjacent disulfide bonds.

In some aspects of the disclosure, the first polypeptide comprises the following structural arrangement from amino terminus to carboxy terminus: MM1-CM1-scFv-VH2-Fc1, wherein each "-" is independently a direct or indirect linkage.

In some aspects, the T cell antigen polypeptide is CD3. The term "CD3" or "cluster of differentiation 3" as used herein refers to a six-chain protein complex that is a subunit of a T cell receptor complex. (Janeway et al, page 166, 9 edition) TCRα:β heterodimers associate with the CD3 subunit to complete the TCR cell surface antigen receptor. The homodimers of two CD3 epsilon chains, one CD3 gamma chain and one CD3 delta chain, and multiple CD3 zeta chains constitute a T cell receptor complex that is involved in recognizing peptides that bind to class I and II major histocompatibility complexes and are involved in T cell activation. CD3 antigen is expressed by mature T lymphocytes and a subset of thymocytes. CD3 as used herein may be from any vertebrate source, including mammals such as primates (e.g., humans) and rodents (e.g., mice and rats). The term encompasses "full length" unprocessed CD3 (e.g., unprocessed or unmodified CD3 epsilon or CD3 gamma) as well as any form of CD3 produced by processing in a cell. The term also encompasses naturally occurring variants of CD3, including, for example, splice variants or allelic variants. The anti-CD 3 targeting domain described herein can specifically bind to human wild-type CD3E (NCBI accession No. nm_ 000733.3).

In some aspects of the disclosure, the T cell antigen polypeptide is the epsilon chain of CD 3. In some aspects, an scFv (e.g., an anti-CD 3 scFv) comprises a heavy chain variable domain (VH 1) and a light chain variable domain (VL 1).

In some aspects, the disclosure provides antibodies or antigen-binding fragments (e.g., scfvs) thereof comprising VH CDRs 1-3 and VL CDRs 1-3 of the anti-CD 3 antibodies provided in table 2. In another aspect, the antibody or antigen-binding fragment thereof (e.g., scFv) comprises VH CDR1-3 or SEQ ID NO:3-5 and VL CDR1-3 of SEQ ID NO:6-8, respectively. In another aspect, the antibody or antigen-binding fragment thereof (e.g., scFv) comprises VH CDR1-3 or SEQ ID NO:128, 4, 130, respectively, and VL CDR1-3 of SEQ ID NO:131-133, respectively. In another aspect, the antibody or antigen-binding fragment thereof (e.g., n scFv) comprises VH CDR1-3 or SEQ ID NO:3-5, respectively, and VL CDR1-3 of SEQ ID NO:144, 7, 146, respectively. In another aspect, an antibody or antigen-binding fragment thereof (e.g., scFv) comprises VH CDR1-3 or SEQ ID NO:128, 4, 130, respectively, and VL CDR1-3 of SEQ ID NO:145, 132, 133, respectively.

The variable domains and/or scFv of any of a variety of anti-CD 3 antibodies known in the art are suitable for use in the activatable HBPC of the present disclosure. In some embodiments, the scFv is specific for binding to CD3 epsilon and is or is derived from an antibody or fragment thereof that binds to CD3 epsilon, e.g., CH2527, FN18, H2C, OKT3, SP34, 2C11, UCHT1, I2C, V9, variants thereof, and the like. anti-CD 3 antibodies (and/or variable domains thereof) and masking moieties suitable for use in activatable HBPC of the present disclosure include, for example, international publication nos: those described in WO 2013/163631, WO 2015/013671, WO 2016/014974, WO 2019/075405 and WO 2019/213444, each of which is incorporated herein by reference in its entirety. Activatable HBPC of the present disclosure may comprise any of the illustrative anti-CD 3 VL CDRs and VH CDRs listed in table 2.

Table 2.

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Other suitable anti-CD 3 masking moieties (e.g., MMl) include, for example, YSLWGCEW GCDRGLY(SEQ ID NO:150)、GYRWGCEWNCGGITT(SEQ ID NO:68)、YSACEMFGEVECCFC(SEQ ID NO:151)、WYSGGCEAFCGILSS(SEQ ID NO:148)、GYSGGCEFRCYQLYS(SEQ ID NO:152)、KFCHCGYYCRVCTLK(SEQ ID NO:153)、LGCNNLWGNEFCHPV(SEQ ID NO:154) and GHPCWGNESYCHTHS (SEQ ID NO: 155).

In some aspects of the disclosure, the first polypeptide further comprises a heavy chain CH1 domain disposed between VH2 and the monomeric Fc domain. In some aspects of the disclosure, the first polypeptide further comprises an immunoglobulin hinge region (HR 1) disposed between the CH1 domain and the first monomeric Fc domain.

In some aspects of the disclosure, the first polypeptide comprises the following structural arrangement from amino terminus to carboxy terminus: MM1-CM1-scFv-VH2-CH1-HR1-Fc1, wherein each "-" is independently a direct or indirect linkage.

In some aspects, the cancer cell antigen is a tumor cell differentiation antigen or other tumor-associated antigen. Some antigens expressed on tumor cells are also expressed at least some stage of differentiation of non-malignant cells of the cell lineage in which the tumor develops. Thus, these lineage specific antigens can be considered differentiation markers. Differentiation markers are found on cancer cells because malignant cells typically express at least some genes that are characteristic of the normal cell type from which the tumor cells originate. Thus, the presence of these normally differentiated antigens can help limit the cytocidal effect of the therapeutic antibodies on the single cell lineage.

An illustrative schematic of the activatable HBPC of the present disclosure is provided in fig. 1, depicting (a) a first polypeptide comprising a first masking moiety (MM 1) 100, a first cleavable moiety (CM 1) 101, scFv 102 (comprising VH1 and VL1 sequences connected by a linker), a second heavy chain variable domain, VH2 (top) and CH1 domain (bottom) (collectively denoted 103), said 103 being connected to a first Fc domain 104 by a hinge region 109; and

(B) A second polypeptide comprising a second masking moiety (MM 2) 105, a second cleavable moiety (CM 2) 106, and a second light chain variable domain VL2 (top) and a constant light domain (bottom) (collectively 107); and

(C) A third polypeptide comprising a hinge region 110 and a second Fc domain 108. As shown in fig. 1, the first and second Fc domains bind to each other, and the second heavy chain variable domain (VH 2) and the second light chain variable domain (VL 2) form a second targeting domain that specifically binds to a second target. In some aspects, the scFv is an anti-CD 3 scFv, wherein the first target is CD3 and VH2 and VL2 form a tumor-associated or tumor-specific antigen binding domain (i.e., wherein the second target is a tumor-associated antigen or tumor-specific antigen). Illustrative anti-CD 3, anti-EGFR activatable HBPC and other anti-CD 3, anti-tumor associated antigens HBPC are described in more detail in the examples below.

In some aspects of the disclosure, activatable HBPC comprises an exemplary anti-CD 3 scFv comprising a heavy chain CDR1 (VH CDR1, also referred to herein as CDRH 1), CDR2 (VH CDR2, also referred to herein as CDRH 2), and CDR3 (VH CDR3, also referred to herein as CDRH 3); and variable light chain CDR1 (VL CDR1, also referred to herein as CDRL 1), CDR2 (VL CDR2, also referred to herein as CDRL 2) and CDR3 (VL CDR3, also referred to herein as CDRL 3).

In some aspects of the disclosure, the scFv comprises a heavy chain variable domain (VH 1) comprising: (i) CDR1 comprising amino acid sequence KYAMN (SEQ ID NO: 3), (ii) CDR2 comprising amino acid sequence RIRSKYNNYATYYADSVKD (SEQ ID NO: 4), and (iii) CDR3 comprising amino acid sequence HGNFGNSYISYWAY (SEQ ID NO: 5); and a light chain variable domain (VL 1) comprising (i) a CDR1 comprising amino acid sequence GSSTGAVTSGNYPN (SEQ ID NO: 6), (ii) a CDR2 comprising amino acid sequence GTKFLAP (SEQ ID NO: 7), and (iii) a CDR3 comprising amino acid sequence VLWYSNRWV (SEQ ID NO: 8).

In some aspects of the disclosure, VH1 comprises a heavy chain variable domain that is at least 90% identical, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to SEQ ID No. 9. In some aspects of the disclosure, VL1 comprises a light chain variable domain that is at least 90% identical, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical to SEQ ID NO. 10.

In some aspects of the disclosure, the first polypeptide scFv comprises a heavy chain variable SEQ ID NO 9. In some aspects of the disclosure, the first polypeptide scFv comprises the light chain variable domain of SEQ ID NO. 10.

In some aspects, when VH1 comprises: (i) a VH CDR1 comprising amino acid sequence KYAMN (SEQ ID NO: 3), (ii) a VH CDR2 comprising amino acid sequence RIRSKYNNYATYYADSVKD (SEQ ID NO: 4) and (iii) a VH CDR3 comprising amino acid sequence HGNFGNSYISY WAY (SEQ ID NO: 5); and VL1 comprises (i) a VL CDR1 comprising amino acid sequence GSSTGAVTSGNYPN (SEQ ID NO: 6), (ii) a VL CDR2 comprising amino acid sequence GTKFLAP (SEQ ID NO: 7) and (iii) a VL CDR3 comprising amino acid sequence VLWYSNRWV (SEQ ID NO: 8), MM1 comprises the amino acid sequence of SEQ ID NO: 1.

In an alternative aspect, the single chain variable fragment comprises a heavy chain variable domain (VH 1) comprising: (i) a VH CDR1 comprising amino acid sequence TYAMN (SEQ ID NO: 128), (ii) a VH CDR2 comprising amino acid sequence RIRSKYNNYATYYADSVKD (SEQ ID NO: 129) and (iii) a VH CDR3 comprising amino acid sequence HGNFGNSYVSWFAY (SEQ ID NO: 130); and a light chain variable domain (VL 1) comprising (i) a VL CDR1 comprising amino acid sequence RSSTGAVTTSNYAN (SEQ ID NO: 131), (ii) a VL CDR2 comprising amino acid sequence GTNKRAP (SEQ ID NO: 132) and (iii) a VL CDR3 comprising amino acid sequence ALWYSNLWV (SEQ ID NO: 133).

In some of these aspects of the disclosure, VH1 comprises the amino acid sequence of SEQ ID NO: 134. In certain aspects of the disclosure, VL1 comprises the amino acid sequence of SEQ ID NO: 135. In a specific aspect of the disclosure, the scFv comprises the amino acid sequence of SEQ ID NO. 122 (which comprises SEQ ID NO:134 and 135).

In some aspects of the disclosure, VH1 comprises an amino acid sequence that is at least 90% identical, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to SEQ ID No. 134. In some aspects of the disclosure, VL1 comprises an amino acid sequence that is at least 90% identical, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to SEQ ID NO 135.

In some aspects of the disclosure, the first polypeptide single chain variable fragment comprises a heavy chain variable domain (VH 1) comprising: (i) a VH CDR1 comprising amino acid sequence TYAMN (SEQ ID NO: 128), (ii) a VH CDR2 comprising amino acid sequence RIRSKYNNYA TYYADSVKD (SEQ ID NO: 129), (iii) a VH CDR3 comprising amino acid sequence HGNFGNSYVSWFAY (SEQ ID NO: 130), and comprising a heavy chain variable domain that is at least 90% identical, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical to SEQ ID NO: 135.

In some aspects of the disclosure, VL1 comprises an amino acid sequence comprising (i) a VL CDR1 comprising amino acid sequence RSSTGAVTTSNYAN (SEQ ID NO: 131), (ii) a VL CDR2 comprising amino acid sequence GTNKRAP (SEQ ID NO: 132), (iii) a VL CDR3 comprising amino acid sequence ALWYSNLWV (SEQ ID NO: 133), wherein the amino acid sequence of VLl is at least 90% identical, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical to SEQ ID NO: 135.

In some of these aspects, when VH1 comprises (i) a VH CDR1 comprising amino acid sequence TYAMN (SEQ ID NO: 128), (ii) a VH CDR2 comprising amino acid sequence RIRSKYNNYATYYADSVKD (SEQ ID NO: 129) and (iii) a VH CDR3 comprising amino acid sequence HGNFGNSYVSWFAY (SEQ ID NO: 130); and VL1 comprises (i) a VL CDR1 comprising amino acid sequence RSSTGAVTTSNYAN (SEQ ID NO: 131), (ii) a VL CDR2 comprising amino acid sequence GTNKRAP (SEQ ID NO: 132), (iii) a VL CDR3 comprising amino acid sequence ALWYSNLWV (SEQ ID NO: 133), MM1 comprises the amino acid sequence of SEQ ID NO: 72.

As described above, the first polypeptide further comprises a monomeric Fc domain (Fc 1). Fc domains known in the art are suitable for use in activatable HBPC of the present disclosure and described in more detail below.

In some aspects of activatable HBPC described herein, the first polypeptide further comprises a heavy chain CH1 domain disposed between VH2 and Fc 1. In some aspects of the activatable Heteromultimeric Bispecific Polypeptide Complexes (HBPC) described herein, the first polypeptide further comprises an immunoglobulin hinge region disposed between VH2 and Fc 1. In some aspects where a CH1 domain is present, an immunoglobulin hinge sequence is disposed between the CH1 domain and the Fc1 domain.

In some aspects of activatable HBPC described herein, the first polypeptide comprises the following structural arrangement from amino terminus to carboxy terminus: the MM1-CM1-scFv-VH2-CH 1-hinge region (HR 1) -Fc1, wherein each "-" is independently linked directly or indirectly (e.g., via a linker).

In some aspects of activatable HBPC described herein, the first polypeptide further comprises one or more optional linkers, which are described in more detail herein below.

In some aspects of the disclosure, activatable HBPC comprises a first polypeptide that comprises an Fc1 having the amino acid sequence shown in SEQ ID NO. 23 or SEQ ID NO. 24. In some aspects of the disclosure, activatable HBPC comprises a first polypeptide that comprises a hinge region having the sequence of hinge-1 (SEQ ID NO: 34) or hinge-2 (SEQ ID NO: 35).

In some aspects of the disclosure, activatable HBPC comprises a second polypeptide that comprises a targeting domain that comprises a light chain variable domain (VL 2) that comprises VL CDR1, VL CDR2, and VL CDR3.

In some aspects of activatable HBPC described herein, the second polypeptide comprises one or more linkers. In some aspects, MM2 is connected to CM2 via a linker.

In some aspects, the activatable HBPC second polypeptide described herein further comprises a linker that comprises from about 1 to about 20 amino acids. Joints suitable for use in the present disclosure are discussed in more detail below.

In some aspects, the second polypeptide further comprises a constant light chain domain (CL). Exemplary CLs include any CL known in the art. In some aspects, the second polypeptide comprises a CL having the amino acid sequence of SEQ ID NO. 25. In certain of these aspects, the second polypeptide comprises the following structural arrangement from amino terminus to carboxy terminus: MM2-CM2-VL2-CL, wherein each "-" is independently directly or indirectly (e.g., via a linker) linked.

In some aspects, the activatable HBPC third polypeptide described herein comprises a monomeric Fc domain (Fc 2) and does not comprise an immunoglobulin variable domain. Fc2 may comprise any of the Fc domains discussed herein.

In some aspects, activatable HBPC disclosed herein comprises a third polypeptide that comprises the following structural arrangement from amino terminus to carboxy terminus: hinge region-Fc 2, wherein each "-" is independently directly or indirectly (e.g., via a linker) linked. In some aspects, "-" is a direct bond. In certain aspects, the third polypeptide consists essentially of or consists of a hinge region and Fc 2. In some aspects, the third polypeptide comprises Fc2, said Fc2 having an amino acid sequence comprising SEQ ID NO. 28 (optionally, having a C-terminal lysine, SEQ ID NO. 29). In one aspect, the third polypeptide comprises a hinge comprising the amino acid sequence of SEQ ID NO. 35; and Fc2, said Fc2 comprising the amino acid sequence of SEQ ID NO. 28 (optionally with a C-terminal lysine, SEQ ID NO. 29). In certain aspects, the first polypeptide comprises a hinge comprising the amino acid sequence of SEQ ID NO. 34; and Fc1, said Fc1 comprising the amino acid sequence of SEQ ID NO. 23 (optionally with a C-terminal lysine, SEQ ID NO: 137).

As provided above, in some aspects, the third polypeptide can comprise a linker, e.g., between the hinge region and Fc 2. The linker may comprise any of the linkers discussed herein. In certain aspects, the third polypeptide does not comprise a linker.

The structural arrangement of components in activatable HBPC described herein (i.e., including the first, second, and third polypeptides described above) advantageously exhibits increased activity (when activated) and improved resistance to aggregation as compared to activatable polypeptides having different structural arrangements of the same components. The examples provided herein demonstrate that the activatable HBPC structure of the present disclosure imparts beneficial properties as compared to other forms of masked bispecific constructs. The results were consistent across different classes of constructs and appeared to be independent of the type of antibody variable domains, masking moieties and other sequence variables.

Activatable HBPC provided herein includes a first masking portion and a second masking portion (MM 1 and MM2, respectively). Each MM has an amino acid sequence coupled or otherwise linked to activatable HBPC and located within activatable HBPC so as to interfere with the binding of HBPC to its target. Thus, the dissociation constant (Kd) of activatable HBPC is typically greater than the Kd of the corresponding activated HBPC (or HBPC alone). Any of a variety of known techniques may be used to identify suitable first and second MMs. For example, peptide MMs may be identified using methods described in U.S. patent application publication nos. 2009/0062142 and 2012/0244154 and PCT publication No. WO 2014/026136, each of which is hereby incorporated by reference in its entirety.

In some aspects, VH1 and VL1 together form a domain that specifically binds to a T cell antigen polypeptide (i.e., a first target), and MM1 is MM1 that reduces the ability of the heteromultimeric bispecific polypeptide complex to specifically bind to a T cell antigen polypeptide. In some aspects, VH2 and VL2 together form a domain that specifically binds to a cancer cell antigen (i.e., the second target), and MM2 is MM2 that reduces the ability of the activatable heteromultimeric bispecific polypeptide complex to specifically bind to the cancer cell antigen. In some aspects, MM1 and/or MM2 specifically bind to an antigen binding domain.

For example, masking moieties suitable for use in the practice of the present disclosure in combination with a variety of antibody binding domains include any masking moiety known in the art, including, for example, those described in PCT publication No. WO2013/163631、WO 2013/192550、WO 2014/052462、WO 2015/066279、WO 2016/014974、WO 2016/149201、WO 2016/179285、WO 2016/179257、WO 2016/179335、WO 2017/011580、WO 2016/014974、WO 2019/075405 and WO 2019/213444, each of which is incorporated herein by reference in its entirety. anti-CD 3 masking moieties suitable for use in the practice of the present disclosure include any of those known in the art, including those described, for example, in PCT publication nos. WO 2016/014974, WO 2019/075405, and WO 2019/213444, each of which is incorporated herein by reference in its entirety.

In some aspects of activatable HBPC provided herein, MM1 and/or MM2 comprise 5 amino acids to about 40 amino acids or any range therebetween, and include both 5 amino acids and 40 amino acids.

When the first and second substrates (and thus the first and second CMs) are cleaved by the first and second proteases, respectively, activatable HBPC of the present disclosure is activated, thereby unbindling the masking moiety from HBPC. In this aspect, each CM has one or more protease cleavable sequence sites. The resulting activated HBPC is thus free to bind to the first and second targets. In some aspects, the first and second substrates (and thus the first and second CMs) are the same. In these aspects, the first and second substrates (and the first and second CMs) may be cleaved by the same protease, i.e., the first protease and the second protease are the same. In some aspects, the first and second substrates are different (and, thus, the first and second CMs are different). In certain of these aspects, the first and second proteases are the same. In other of these aspects, the first and second proteases are different.

In some aspects, CM is specific for proteases that are up-regulated in the tumor microenvironment. Such activatable HBPC utilizes deregulated protease activity in tumor cells for targeted Heteromultimeric Bispecific Polypeptide (HBPC) activation at therapeutic and/or diagnostic sites. Numerous studies have demonstrated the correlation of aberrant protease levels, such as uPA, legumain, MT-SP1, matrix Metalloproteinase (MMP), in solid tumors. In some aspects, the CM may serve as a substrate for more than one serine protease (e.g., a proteolytic enzyme (matriptase) and/or uPA).

In some aspects, CM1 and/or CM2 comprises an amino acid sequence that is a substrate for a protease listed in table 3 below. In certain aspects, CMl and CM2 each independently comprise an amino acid sequence that is a substrate for a protease listed in table 3 below.

TABLE 3 exemplary proteases

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In some aspects of activatable HBPC described herein, CMl and/or CM2 comprises from about 3 amino acids to about 15 amino acids. In some aspects, CM1 and/or CM2 may comprise two or more cleavage sites. In some aspects, CM1 may comprise two or more cleavage sites for one protease. In some aspects, CM2 may comprise two or more cleavage sites for two or more proteases. In some aspects, the first protease and the second protease are the same protease. In some embodiments, CM1 and CM2 comprise different substrates of the same protease. In some embodiments, CM1 and CM2 comprise the same amino acid sequence. In some aspects, CM1 and CM2 comprise different amino acid sequences. In some aspects, CM1 comprises the amino acid sequence of SEQ ID NO: 73. In some aspects, CM1 comprises the amino acid sequence of SEQ ID NO. 2. In some aspects, CM2 comprises the amino acid sequence of SEQ ID NO. 14. In certain aspects, activatable HBPC described herein comprises CM1 comprising the amino acid sequence of SEQ ID NO. 2 and CM2 comprising the amino acid sequence of SEQ ID NO. 14. In some aspects, activatable HBPC described herein comprises CM1 comprising the amino acid sequence of SEQ ID NO. 73 and CM2 comprising the amino acid sequence of SEQ ID NO. 14.

Exemplary CMs suitable for use in activatable HBPC described herein include those known in the art. Exemplary CMs include, but are not limited to, for example, table 4 and international publication numbers: those described in WO 2009/025846, WO 2010/081173, WO 2015/01371, WO 2015/048329, WO 2015/116933, WO 2016/014974 and WO 2016/118629, each of which is incorporated herein by reference in its entirety.

In some aspects, CMl and/or CM2 comprises the amino acid sequences listed in table 4 below. In certain aspects, CM1 and CM2 each independently comprise an amino acid sequence set forth in table 4 below.

TABLE 4 cleavable moiety

CM SEQ ID NO.	CM sequence
		2	GLSGRSDDH
14	ISSGLLSGRSDQH
		73	LSGRSDDH
74	ISSGLLSGRSDQH
		75	LSGRSDNH
76	TSTSGRSANPRG
		77	VHMPLGFLGP
78	AVGLLAPP
		79	QNQALRMA
80	ISSGLLSS
		81	ISSGLLSGRSDNH
82	LSGRSGNH
		83	LSGRSDIH
84	LSGRSDQH
		85	LSGRSDTH
86	LSGRSDYH
		87	LSGRSDNP
88	LSGRSANP
		89	LSGRSANI
90	LSGRSDNI
		91	ISSGLLSGRSANPRG
92	AVGLLAPPTSGRSANPRG
		93	AVGLLAPPSGRSANPRG
94	ISSGLLSGRSDDH
		95	ISSGLLSGRSDIH
96	ISSGLLSGRSDTH
		97	ISSGLLSGRSDYH
98	ISSGLLSGRSDNP
		99	ISSGLLSGRSANP
100	ISSGLLSGRSANI
		101	AVGLLAPPGGLSGRSDDH
102	AVGLLAPPGGLSGRSDIH
		103	AVGLLAPPGGLSGRSDQH
104	AVGLLAPPGGLSGRSDTH
		105	AVGLLAPPGGLSGRSDYH
106	AVGLLAPPGGLSGRSDNP
		107	AVGLLAPPGGLSGRSANP
108	AVGLLAPPGGLSGRSANI
		109	ISSGLLSGRSDNI
110	AVGLLAPPGGLSGRSDNI
		111	ISSGLLSGRSGNH
156	ALAHGLF
		157	APRSALAHGLF
158	ISSGLLSGRSNI
		159	LSGRSNI

In some aspects of the activatable Heteromultimeric Bispecific Polypeptides (HBPC) of the disclosure, the first polypeptide comprises one or more linkers between the MM and the CM. In some aspects, MM1 is connected to CM1 via a linker. In some aspects, MM2 is connected to CM2 via a linker. In some aspects, MM1 is linked to CM1 via linker L1, and CM1 is linked to the anti-CD 3 scFv via linker L2. In some aspects, MM2 is connected to CM2 via linker L3, and CM2 is connected to scFv via linker L4. In some aspects, the amino acid sequences of L1, L2, L3, and/or L4 are identical. In some aspects, the amino acid sequences of L1, L2, L3, and/or L4 are different.

In some aspects, activatable HBPC comprises a linker between the CM and the targeting domain or variable domain thereof. Linkers suitable for use in the activatable Heteromultimeric Bispecific Polypeptides (HBPC) described herein are generally linkers that provide flexibility to the activatable Heteromultimeric Bispecific Polypeptide (HBPC) to facilitate inhibition of binding of the activatable polypeptide to a target. Such joints are commonly referred to as flexible joints. Suitable linkers can be readily selected and can have any suitable different length, such as 1 amino acid (e.g., gly) to 20 amino acids, 2 amino acids to 15 amino acids, 3 amino acids to 12 amino acids, including 4 amino acids to 10 amino acids, 5 amino acids to 9 amino acids, 6 amino acids to 8 amino acids, or 7 amino acids to 8 amino acids, and can be 1, 2, 3,4,5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acids in length.

Exemplary flexible linkers include glycine polymer (G) n, glycine-serine polymers (including, for example, (GS) n, (GSGGS) n, and (GGGS) n (SEQ ID NO:41 and SEQ ID NO:40, respectively), where n is an integer of at least 1), glycine-alanine polymers, alanine-serine polymers, and other flexible linkers known in the art. Glycine and glycine-serine polymers are relatively unstructured and thus may be able to act as neutral tethers between components. Glycine acquired significantly more phi-psi space than even alanine and was much less restricted than residues with longer side chains (see Scheraga, rev. Computational chem.11173-142 (1992)). One of ordinary skill will recognize that the design of the activatable polypeptide may include a linker that is wholly or partially flexible, such that the linker may include a flexible linker as well as one or more portions that impart a less flexible structure to provide the desired structure.

The activatable bispecific polypeptide complex described herein (i.e., HBPC) can comprise a linker in one or more of the following positions: (a) Between MMl and CMl and/or between CM1 and scFv (i.e., between CM1 and the heavy chain variable domain of scFv (VH 1) or between CM1 and the light chain variable domain of scFv (VL 1); (b) between MM2 and CM 2; (b) Between the heavy and light variable domains of the scFv; (c) between the heavy chain variable domain and the CH1 domain; (d) between the CH1 domain and the hinge region; (e) between the hinge region and the Fc domain; (g) between CM2 and the light chain variable domain; (h) between the light chain variable domain and CL; (i) between the CH1 domain and the second Fc domain; (j) between the CH1 domain and the hinge region; and/or (k) between the hinge region and the second Fc domain.

In some aspects, the linker is selected from the group consisting of: (i) A glycine-serine based linker selected from the group consisting of: (GS) n, wherein n is an integer of at least 1, and in some aspects, n is an integer of between 1 and 10, (GGS) n, wherein n is an integer of at least 1, and in some aspects, n is an integer of between 1 and 10, (GGGS) n (SEQ ID NO: 40), wherein n is an integer of at least 1, and in some aspects, wherein n is an integer of between 1 and 10, (GGGGS) n (SEQ ID NO: 126), wherein n is an integer of at least 1, (GSGGS) n (SEQ ID NO: 41), wherein n is an integer of at least 1, and in some aspects, wherein n is integers ,GSSGGSGGSG(SEQ ID NO:12),GGSG(SEQ ID NO:42),GGSGG(SEQ ID NO:43),GSGSG(SEQ ID NO:44),GSGGG(SEQ ID NO:45),GGGSG(SEQ ID No:46) and GSSSG(SEQ ID NO:47),GGGGSG GGGSGGGGSGS(SEQ ID NO:48),GGGGSGS(SEQ ID NO:49),GGGGSGGGGSGGGGS(SEQ ID NO:50),GGGGSGGGGSGGGGSG GGGS(SEQ ID NO:51),GGGGS(SEQ ID NO:52),GGGGSGGGGS(SEQ ID NO:53),GGGS(SEQ ID NO:54),GGGSGGGS(SEQ ID NO:55),GGGSGGGSGGGS(SEQ ID NO:56),GSSGGSGGSG(SEQ ID NO:57),GGGSGGGGSGGGGSGGGGSGGGGS(SEQ ID NO:58),GGGSSGGS(SEQ ID NO:127) between 1 and 10, and GS; and (ii) linkers ：GSTSGSGKPGSSEGST(SEQ ID NO:59)、SKYGPPCPPCPAPE FLG(SEQ ID NO:60)、GGSLDPKGGGGS(SEQ ID NO:61)、PKSCD KTHTCPPCPAPELLG(SEQ ID NO:62)、GKSSGSGSESKS(SEQ ID NO:63)、GSTSGSGKSSEGKG(SEQ IDNO:64)、GSTSGSGK SSEGSGSTKG(SEQ ID NO:65) and GSTSGSGKPGSGEGSTKG (SEQ ID NO: 66) selected from the group consisting of glycine and serine and at least one of lysine, threonine or proline.

In some aspects of the disclosure, activatable heteromultimeric bispecific polypeptide complexes may comprise components other than those described above. Such components may include spacers. The term "spacer" herein refers to an amino acid residue or peptide incorporated into the free ends of the first, second and/or third polypeptides, and a spacer suitable for use in the practice of the present disclosure includes any single amino acid residue or any peptide. Suitable spacers include, for example, international publication No.: any of those described in WO 2016/014974, WO 2019/075405 and WO 2019/213444, each of which is incorporated herein by reference in its entirety.

In some aspects, a spacer may comprise from about 1 amino acid to about 10 amino acids (e.g., about 1,2,3, 4,5,6, 7, 8, or 9 amino acids) or any number therebetween. In some aspects of the activatable heteromultimeric bispecific polypeptide complexes described herein, the spacer is located at the N-terminus relative to MM1 and/or MM 2. In some aspects, the spacer has the sequence QGQSGS (SEQ ID NO: 116). In some aspects, the spacer has the sequence QGQSGQG (SEQ ID NO: 117). In some aspects, the spacer has the sequence QGQSGS (SEQ ID NO: 118). In some aspects, the spacer has the sequence QGQSGQG (SEQ ID NO: 119).

In some aspects, the first and second Fc domains (Fc 1 and Fc2, respectively) of the activatable heteromultimeric bispecific polypeptide complexes described herein are IgG1 Fc domains or IgG4 Fc domains (e.g., human IgG1 Fc domains or human IgG4 Fc domains) or variants thereof. In some aspects, fc1 and/or Fc2 are modified variants of a native (e.g., human) IgG1 Fc domain. In some aspects, fc1 and/or Fc2 are modified variants of a native (e.g., human) IgG4 Fc domain.

In some aspects of the disclosure, the Fc domain used as Fc1 and/or Fc2 is a mutant form of the native Fc amino acid sequence. Mutations may confer desirable beneficial properties on the activatable heteromultimeric bispecific polypeptide (and correspondingly activated HBPC). For example, it is known that certain mutations in the FcRn binding site may modulate effector function (see, e.g., petkova et al, int l.Immunol.18:1759-1769,2006; deng et al, MAbs 4:101-109,2012; and Olafson et al, methods mol. Biol.907:537-556, 2012.) any known mutation that comprises a regulatable effector function in the Fc domain is suitable. For example, the N297A or N297G mutation in the Fc amino acid sequence can be used to reduce IgG effector functions (e.g., ADCC and CDC), which can reduce target independent toxicity (see, e.g., lund et al, mol. Immunol.29:35-39,1992). Fc domains suitable for use in the context of the present disclosure include any Fc domain known in the art, including, but not limited to, any known heterodimeric Fc (e.g., knob in hole(s), etc.).

In some aspects, the activatable heteromultimeric bispecific polypeptide complexes disclosed herein further comprise an immunoglobulin hinge region. Suitable hinge regions include any hinge region known in the art. For example, from any five main classes of immunoglobulins: the hinge regions of IgA, igD, igE, igG and IgM or subclasses (isotypes) thereof (e.g., igG1, igG2, igG3, igG4, igA1, and IgA 2) are suitable for use in the present disclosure. Different classes of immunoglobulins have different and well known subunit structures and three-dimensional configurations.

In some aspects of the activatable heteromultimeric bispecific polypeptide complexes described herein, fc1 comprises an amino acid sequence that is at least 90% identical, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical to SEQ ID No. 23, optionally having a C-terminal lysine (i.e., SEQ ID No. 24).

In some aspects, the third polypeptide further comprises a monomeric Fc domain (Fc 2) that binds to Fc 1. In some aspects, fc2 comprises an amino acid sequence that 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%, or at least 99% identical to SEQ ID NO. 28. In some aspects, fc2 comprises SEQ ID NO:28 (optionally with a terminal lysine (i.e., SEQ ID NO: 29)).

In some aspects, the third polypeptide comprises a hinge region having an amino acid sequence selected from the group consisting of SEQ ID NOS: 34 and 35.

As provided elsewhere herein, the form or structure of the activatable heteromultimeric bispecific polypeptide complexes disclosed herein can include any number of optional additional components, including linkers and spacers. By way of example only, structures set forth below are intended to be aspects. However, the aspects shown below are not meant to limit the disclosure in any way.

In some aspects, the activatable heteromultimeric bispecific polypeptide complex comprises a first polypeptide having structure (I).

First polypeptide structure (I):

(S1) -MM1- (L1) -CM1-L2-VH1-L3-VL1- (L4) -VH2- (L5) - (CH 11) - (L6) - (hinge 1) - (L7) -Fc1,

Wherein the method comprises the steps of

S1 is an optional spacer;

MM1 is the masking moiety of the first targeting domain

(L1), (L4), (L5), (L6) and (L7) are each independently an optional linker,

L2 and L3 are linkers and are,

(CH 11) is an optional CH1 domain,

(Hinge 1) is an optional hinge region, and

Fc1 as described above.

In some aspects, the activatable heteromultimeric bispecific polypeptide complex comprises a second polypeptide having structure (II).

Second polypeptide structure (II):

(S2)-(L8)-MM2-(L9)-CM2-(L10)-VL2-(CL)

Wherein the method comprises the steps of

S2 is an optional spacer,

(L8), (L9) and (L10) are each independently an optional linker,

MM2 is the masking moiety of the second targeting domain, and

VL2 is as described above; and

And (CL) is an optional light chain constant domain.

In some aspects, the activatable heteromultimeric bispecific polypeptide complex comprises a third polypeptide having structure (III).

Third polypeptide structure (III):

(S3) - (CH 12) - (L11) - (hinge 2) - (L12) -Fc2

Wherein,

S3 is an optional spacer,

(CH 12) is an optional CH1 domain,

(L11) and (L12) are each independently an optional linker, and

Fc2 as described above.

Suitable linkers, spacers, MMs, CMs, fc domains, CH1 (i.e., CH11 and CH 12) domains, hinge regions, and CLs for use in structures (I), (II), and (III) include any known in the art or described herein.

In some aspects of the disclosure, activatable HBPC comprises: (a) A first polypeptide comprising (i) a single chain variable fragment (scFv) comprising a first heavy chain variable domain (VH 1) and a first light chain variable domain (VL 1), wherein the VH1 and the VL1 together form a T cell antigen targeting domain that specifically binds a T cell antigen polypeptide, (ii) a first masking moiety (MM 1), (iii) a first cleavable moiety (CM 1), (iv) a second heavy chain variable domain (VH 2), (v) a first monomeric Fc domain (Fc 1), (vi) a heavy chain CH1 domain, and (vii) a first immunoglobulin hinge region (HR 1) between the CH1 domain and the Fc 1; (b) A second polypeptide comprising (i) a light chain variable domain (VL 2), wherein VH2 and VL2 together form a cancer cell surface antigen targeting domain that specifically binds a cancer cell surface antigen, (ii) a second masking moiety (MM 2), (iii) a second cleavable moiety (CM 2), and (iv) a light chain constant domain CL1; and (c) a third polypeptide comprising (i) a second monomeric Fc domain (Fc 2) and an immunoglobulin hinge region, and (ii) no immunoglobulin variable domain.

In certain aspects, the first polypeptide comprises the following structural arrangement from amino terminus to carboxy terminus:

MM1-CM1-scFv1-VH2-CH1-HR1-Fc1；

The second polypeptide comprises the following structural arrangement from amino terminus to carboxy terminus:

MM2-CM2-VL2-CL1；

And the third polypeptide has the following structural arrangement from amino terminus to carboxy terminus: HR2-Fc2, wherein each "-" is independently directly or indirectly (e.g., via a linker) linked. In some aspects, the third polypeptide consists essentially of or consists of HR2-Fc2, wherein each "-" is independently directly or indirectly (e.g., via a linker) linked.

In some aspects, the first polypeptide HR1 and the second polypeptide HR2 comprise the same amino acid sequence. In some aspects, the first polypeptide HR1 and the second polypeptide HR2 comprise different amino acid sequences.

The present disclosure also provides a heteromultimeric bispecific polypeptide complex (e.g., an activatable HBPC component HBPC described herein) comprising: (a) A first polypeptide comprising (i) a single chain variable fragment (scFv) comprising a first heavy chain variable domain (VH 1) and a first light chain variable domain (VL 1), wherein the VH1 and the VL1 together form a first targeting domain that specifically binds a first target, (ii) a second heavy chain variable domain (VH 2), and (iii) a first monomeric Fc domain (Fc 1); (b) A second polypeptide comprising a second light chain variable domain (VL 2), wherein the VH2 and the VL2 together form a second targeting domain that specifically binds a second target; and (c) a third polypeptide comprising a second monomeric Fc domain (Fc 2) and wherein the third polypeptide does not comprise an immunoglobulin variable domain. In some aspects, the HBPC constructs described above may be generated by "activating" activatable HBPC as described herein. Any of the VH1, VL1 (and scFv), VH2, VL2, fc1, fc2 and optionally linker, HR1, HR2 and CH1 components described herein as suitable for use in the activatable HBPC of the present disclosure are suitable for use in the HBPC construct described above. HBPC have a structure comprising the following elements: (a) A first polypeptide comprising (i) a single chain variable fragment (scFv) comprising a first heavy chain variable domain (VH 1) and a first light chain variable domain (VL 1), wherein the VH1 and the VL1 together form a first targeting domain that specifically binds a first target, (ii) a second heavy chain variable domain (VH 2), and (iii) a first monomeric Fc domain (Fc 1); (b) A second polypeptide comprising a second light chain variable domain (VL 2), wherein the VH2 and the VL2 together form a second targeting domain that specifically binds a second target; and (c) a third polypeptide comprising a second monomeric Fc domain (Fc 2) and not comprising an immunoglobulin variable domain.

Medicine box

Provided herein are kits comprising one or more of activatable HBPC or HBPC thereof as described herein, wherein the kits are for use in diagnosis or treatment. In certain aspects, provided herein are packages or kits comprising one or more containers filled with one or more components of the compositions described herein, such as one or more activatable HBPC or antigen-binding fragments thereof provided herein, and optionally instructions for use. In some aspects, the kit contains a composition described herein and any diagnostic, prophylactic or therapeutic agent, such as those described herein.

Therapeutic uses and methods

In some aspects, presented herein are methods of treating a disease (e.g., cancer) comprising administering to a subject in need thereof an activatable antibody HBPC as described herein or HBPC thereof or a pharmaceutical composition thereof as described herein. In some aspects, presented herein are methods of inhibiting tumor growth in a subject in need thereof, the methods comprising administering to a subject in need thereof an activatable HBPC or HBPC as described herein or a pharmaceutical composition thereof as described herein. In some aspects, the disclosure relates to activatable HBPC as described herein or HBPC thereof or a pharmaceutical composition provided herein for use as a medicament. Typically, the subject is a human, but non-human mammals, including transgenic mammals, can also be treated.

The amount of activatable HBPC or HBPC or a combination thereof that will be effective to treat a disorder will depend on the nature of the disease. The precise dosage to be employed in the composition will also depend on the route of administration and the severity of the disease.

Non-limiting examples of diseases include: cancer, rheumatoid arthritis, crohn's disease, SLE, cardiovascular injury, ischemia, and the like. For example, indications may include leukemia, including T-cell acute lymphoblastic leukemia (T-ALL), lymphoblastic disease (including multiple myeloma), and solid tumors, including lung, colorectal, prostate, pancreatic, and breast cancers, including triple negative breast cancers. For example, an indication may include a bone disease or cancer metastasis, regardless of the origin of the primary tumor; breast cancer, including, as non-limiting examples, ER/pr+ breast cancer, her2+ breast cancer, triple negative breast cancer; colorectal cancer; endometrial cancer; stomach cancer; glioblastoma; head and neck cancer, such as squamous cell carcinoma of head and neck; esophageal cancer; lung cancer, such as, by way of non-limiting example, non-small cell lung cancer; multiple myeloma ovarian cancer; pancreatic cancer; prostate cancer; sarcomas, such as osteosarcoma; renal cancer, such as, by way of non-limiting example, renal cell carcinoma; and/or skin cancer, such as squamous cell carcinoma, basal cell carcinoma, or melanoma, as non-limiting examples.

Polynucleotide

In some aspects, provided herein are polynucleotides (referred to herein as "first polynucleotides", "second polynucleotides", and "third polynucleotides", respectively) comprising nucleotide sequences encoding the first, second, and/or third polypeptides of the activatable HBPC and HBPC constructs of the present disclosure. Suitable polynucleotides include any polynucleotide encoding any of the first, second and/or third polypeptides or portions thereof described herein. Exemplary sets of polynucleotide sequences encoding the first, second and third polypeptides are provided herein below.

The polynucleotides of the present disclosure may be sequence optimized for optimal production from the host organism selected for expression, e.g., by codon/RNA optimization, substitution with heterologous signal sequences, and elimination of mRNA instability elements. Methods for generating optimized nucleic acids encoding activatable HBPC or HBPC thereof for recombinant expression by introducing codon changes (e.g., codon changes encoding the same amino acid due to degeneracy of the genetic code) and/or eliminating the inhibitory region in the mRNA can thus be accomplished by employing the methods described, for example, in U.S. patent No. 5,965,726;6,174,666;6,291,664;6,414,132; and the optimization method described in 6,794,498.

Polynucleotides encoding the polypeptides described herein, or antigen-binding fragments thereof, or domains thereof, can be produced from nucleic acids from suitable sources (e.g., hybridomas) using methods well known in the art (e.g., PCR and other molecular cloning methods). For example, PCR amplification can be performed using genomic DNA obtained from hybridoma cells producing the antibody of interest, using synthetic primers that hybridize to the 3 'and 5' ends of known sequences. Such PCR amplification methods can be used to obtain nucleic acids comprising sequences encoding the light and/or heavy chains of an antibody or antigen binding fragment thereof. Such PCR amplification methods can be used to obtain nucleic acids comprising sequences encoding the variable light chain region and/or variable heavy chain region of an antibody or antigen binding fragment thereof. The amplified nucleic acid may be cloned into a vector for expression in a host cell and further cloned, for example, to produce chimeric and humanized antibodies or antigen-binding fragments thereof.

The polynucleotides provided herein may be RNA or DNA. DNA includes cDNA, genomic DNA, and synthetic DNA, and DNA may be double-stranded or single-stranded. If single stranded, the DNA may be the coding strand or the non-coding (antisense) strand. In some aspects, the polynucleotide is a cDNA or DNA lacking one or more endogenous introns. In some aspects, the polynucleotide is a non-naturally occurring polynucleotide. In some aspects, the polynucleotide is recombinantly produced. In some aspects, the polynucleotide is isolated. In some aspects, the polynucleotide is substantially pure. In some aspects, the polynucleotide is purified from a native component.

Vector, host cell and production method

Provided herein are one or more vectors comprising polynucleotides encoding a first, second, and/or third polypeptide of the disclosure (corresponding to the first, second, and third polynucleotides, respectively). In some aspects, such vectors may be used for recombinant production of an activatable HBPC (or HBPC) polypeptide from a host cell, as described in more detail herein below. In some aspects, the vector comprises a first, second, and/or third polynucleotide operably linked to one or more promoter sequences. In certain aspects, the disclosure provides a plurality of vectors that collectively comprise polynucleotides encoding the first, second, and third polypeptides (i.e., first, second, and third polynucleotides), wherein the plurality of vectors comprises at least one vector comprising no more than two or no more than one of the first, second, and third polynucleotides. In these aspects, the first, second, and third polynucleotide sequences in the plurality of vectors are typically operably linked to one or more promoter sequences.

Also provided herein are recombinant host cells comprising any of the above polynucleotides and/or vectors for recombinant expression of a polynucleotide encoding a polypeptide of activatable HBPC or HBPC of the present disclosure. A variety of host expression vector systems can be used to express the polypeptides described herein (see, e.g., U.S. patent No. 5,807,715). Such host expression systems represent vehicles by which the coding sequences of interest can be produced and subsequently purified, and also represent cells that can express the antibodies or antigen-binding fragments thereof described herein in situ when transformed or transfected with the appropriate nucleotide coding sequences. Exemplary host cells suitable for use as recombinant expression hosts for the polynucleotides described above include mammalian cell systems (e.g., COS1 or COS), CHO, BHK, MDCK, HEK 293, NS0, PER.C6, VERO, CRL7O3O, hsS Bst, heLa and NIH 3T3, HEK-293T, hepG2, SP210, R1.1, B-W, L-M, BSC1, BSC40, YB/20, BMT10 cells, and the like). Vectors used to construct recombinant mammalian host cells may include promoters derived from the genome of the mammalian cell (e.g., metallothionein promoter) or promoters derived from mammalian viruses (e.g., adenovirus late promoter; vaccinia virus 7.5K promoter). In some aspects, the recombinant host cell is a CHO cell or an NS0 cell.

In some aspects, recombinant expression of a polypeptide described herein (e.g., a first, second, and/or third polypeptide) involves construction of an expression vector containing the first, second, and/or third polynucleotide. Vectors comprising polynucleotides encoding activatable HBPC or HBPC of the present disclosure can be readily produced by recombinant DNA techniques using techniques well known in the art. Methods well known to those of skill in the art may be used to construct expression vectors containing one or more polynucleotides encoding those polypeptides described herein (e.g., first, second, and/or third polypeptides) and appropriate transcriptional and translational control signals. These methods include, for example, recombinant DNA techniques in vitro, synthetic techniques, and in vivo gene recombination. Replicable vectors comprising a nucleotide sequence operably linked to a promoter are also provided. Such vectors may, for example, comprise nucleotide sequences encoding the constant regions of polypeptides described herein (e.g., first, second, and/or third polypeptides) (see, e.g., international publication nos. WO 86/05807 and WO 89/01036; and U.S. Pat. No. 5,122,464), and the variable domains of the polypeptides may be cloned into such vectors to express either the complete VH, the complete VL, or both the complete VH and VL.

The expression vector may be transferred to a cell (e.g., a host cell) by conventional techniques, and the resulting cell may then be cultured by conventional techniques to produce activatable HBPC or HBPC as described herein. Accordingly, provided herein are host cells containing a polynucleotide encoding HBPC described herein operably linked to a promoter for expression of such sequences in the host cells. In some aspects, the host cell contains a vector comprising one or more polynucleotides encoding activatable HBPC or HBPC or domains thereof as described herein. In some aspects, the host cell contains three different vectors, a first vector comprising a first polynucleotide encoding a first polypeptide described herein, a second vector comprising a second polynucleotide encoding a second polypeptide described herein, and a third vector comprising a third polynucleotide encoding a third polypeptide described herein.

In some aspects, provided herein are populations of vectors that collectively comprise polynucleotides encoding the first, second, and third polypeptides, wherein each vector comprises only one or two of the polynucleotides encoding the first, second, and third polypeptides. In certain aspects, provided herein are single vectors comprising polynucleotides encoding the first, second, and third polypeptides (i.e., the first, second, and third polynucleotides, respectively).

In some aspects, the present disclosure provides a method of producing activatable HBPC of the present disclosure, the method comprising: (a) Culturing a host cell comprising one or more polynucleotides encoding a polypeptide of the present disclosure (e.g., a first polynucleotide, a second polynucleotide, and/or a third polynucleotide, and a vector comprising the foregoing polynucleotides) in a liquid culture medium under conditions sufficient to produce activatable HBPC; and (b) recovering the activatable HBPC.

In a particular aspect, provided herein are methods for producing activatable HBPC of the present disclosure, the methods comprising expressing first, second, and third polypeptides thereof in a host cell. More specifically, provided herein is a method of generating activatable HBPC, the method comprising: (a) Culturing a host cell comprising one or more polynucleotides encoding polypeptides of the present disclosure in a liquid medium under conditions sufficient to produce the activatable HBPC; and (b) recovering the activatable HBPC. In another aspect, the method further comprises purifying the biological harvest (cell-free expression product) of the activatable HBPC or other in-process composition, including subjecting the aqueous composition comprising activatable HBPC to a unit operation such as, for example, affinity chromatography, size exclusion chromatography, ion exchange chromatography, ceramic hydroxyapatite chromatography, and the like. In certain aspects, the unit operation is ceramic hydroxyapatite chromatography.

In a further aspect, provided herein are methods for producing HBPC of the present disclosure, the methods comprising expressing in a host cell first, second, and third polypeptides thereof. More specifically, provided herein are methods of producing HBPC of the present disclosure, the methods comprising: (a) Culturing a host cell comprising one or more polynucleotides encoding polypeptides of the present disclosure in a liquid medium under conditions sufficient to produce the HBPC; and (b) recovering said HBPC. In another aspect, the method further comprises purifying HBPC or other in-process composition biological harvest (cell-free expression product) comprising subjecting the aqueous composition comprising activatable HBPC to a unit operation such as, for example, affinity chromatography, size exclusion chromatography, ion exchange chromatography, ceramic hydroxyapatite chromatography, and the like. In certain aspects, the unit operation is ceramic hydroxyapatite chromatography.

Composition and method for producing the same

In some aspects, activatable HBPC of the present disclosure or HBPC thereof can be used in pharmaceutical compositions that can be used in any of the therapeutic applications disclosed herein. In certain aspects, the pharmaceutical composition comprises a therapeutically effective amount of one or more activatable HBPC together with a pharmaceutically acceptable diluent or carrier. In another aspect, the pharmaceutical composition comprises a therapeutically effective amount of one or more activatable HBPC, pharmaceutically acceptable diluents, carriers, solubilizers, emulsifiers, preservatives and/or adjuvants. Acceptable formulation materials are non-toxic to recipients at the dosages and concentrations employed. The pharmaceutical composition may be formulated as a liquid, frozen or lyophilized composition.

In certain aspects, the pharmaceutical compositions may contain formulation materials for adjusting, maintaining, or maintaining, for example, the pH, osmolarity, viscosity, clarity, color, isotonicity, odor, sterility, stability, dissolution or release rate, absorption or permeation of the composition. Suitable formulation materials include, but are not limited to, amino acids; an antimicrobial agent; an antioxidant; a buffering agent; a filler; a chelating agent; complexing agent; a filler; carbohydrates such as mono-or disaccharides; a protein; coloring agents, flavoring agents, and diluents; an emulsifying agent; a hydrophilic polymer; a low molecular weight polypeptide; salt-forming counterions (such as sodium); a preservative; solvents (such as glycerol, propylene glycol or polyethylene glycol); sugar alcohols; a suspending agent; a surfactant or wetting agent; a stability enhancer; a tension enhancer; a delivery vehicle; and/or pharmaceutical adjuvants. Additional details and options of suitable agents that may be incorporated into the pharmaceutical composition are provided, for example, in Remington's Pharmaceutical Sciences, 22 nd edition, (Loyd v. Allen et al) Pharmaceutical Press (2013); ansel et al Pharmaceutical Dosage Forms and Drug DELIVERY SYSTEMS, 7 th edition, lippencott WILLIAMS AND WILKINS (2004); and Kibbe et al, handbook of Pharmaceutical Excipients, 3 rd edition, pharmaceutical Press (2000).

The components of the pharmaceutical composition are selected according to, for example, the intended route of administration, the form of delivery and the dosage required. See, e.g., remington's Pharmaceutical Sciences, 22 nd edition, (Loyd v. Allen edit) Pharmaceutical Press (2013). The composition is selected to affect the physical state, stability, in vivo release rate, and in vivo clearance rate of the disclosed antigen binding proteins. The primary vehicle or carrier in the pharmaceutical composition may be aqueous or non-aqueous in nature. For example, a suitable vehicle or carrier may be water for injection or a physiological saline solution. In certain aspects, the antigen binding protein composition may be prepared for storage in the form of a lyophilized cake or aqueous solution by mixing the selected composition with the desired purity and optionally a formulation. In addition, in certain aspects, the antigen binding proteins can be formulated as lyophilizates using suitable excipients.

In certain formulations, the activatable HBPC concentration is at least 2mg/ml、5mg/ml、10mg/ml、20mg/ml、30mg/ml、40mg/ml、50mg/ml、60mg/ml、70mg/ml、80mg/ml、90mg/ml、100mg/ml、110mg/ml、120mg/ml、130mg/ml、140mg/ml or 150mg/ml. In other formulations, the activatable HBPC has a concentration of 10-20mg/ml, 20-40mg/ml, 40-60mg/ml, 60-80mg/ml, or 80-100 mg/ml.

Some compositions comprise a buffer or a pH adjuster. Representative buffers include, but are not limited to: organic acid salts (e.g., citrate, acetate, ascorbate, gluconate, carbonate, tartrate, succinate, or phthalate); tris; phosphate buffer; and in some cases, amino acids as described below. In certain aspects, buffers are used to maintain the composition at physiological pH or at a slightly lower pH, typically in the pH range of about 5 to about 8. Some compositions have a pH of about 5-6, 6-7, or 7-8. In other aspects, the pH is 5.5-6.5, 6.5-7.5, or 7.5-8.5.

The free amino acids or proteins are used as fillers, stabilizers and/or antioxidants in some compositions. As an example, lysine, proline, serine and alanine can be used to stabilize proteins in the formulation. Glycine can be used in lyophilization to ensure proper cake structure and characteristics. Arginine can be used to inhibit protein aggregation in both liquid and lyophilized formulations. Methionine may be used as an antioxidant. In some aspects glutamine and asparagine are included. Amino acids are included in some formulations due to their buffering capacity. Such amino acids include, for example, alanine, glycine, arginine, betaine, histidine, glutamic acid, aspartic acid, cysteine, lysine, leucine, isoleucine, valine, methionine, phenylalanine, aspartame, and the like. Certain formulations also comprise protein excipients such as serum albumin (e.g., human Serum Albumin (HSA) and recombinant human albumin (rHA)), gelatin, casein, and the like.

Some compositions comprise a polyol. Polyols include sugars (e.g., mannitol, sucrose, trehalose, and sorbitol) and polyols such as glycerol and propylene glycol, as well as polyethylene glycol (PEG) and related substances. Polyols are low chaotropic (kosmotropic). They are useful stabilizers in both liquid and lyophilized formulations for protecting proteins from physical and chemical degradation processes. Polyols are also useful in adjusting the tonicity of the formulation.

Some compositions comprise mannitol as a stabilizer. It is typically used with lyoprotectants such as sucrose. Sorbitol and sucrose can be used to adjust tonicity and can be used as stabilizers to protect against freeze-thaw stress during transportation or to prevent bulk products during the manufacturing process. PEG can be used to stabilize proteins and can be used as a cryoprotectant, and as such can be used in the present disclosure.

Sugars, including monosaccharides, disaccharides, trisaccharides, tetrasaccharides, and oligosaccharides; derivatized sugars such as sugar alcohols, aldonic acids, esterified sugars, and the like; and polysaccharides or sugar polymers may be included in some formulations. For example, suitable carbohydrate excipients include monosaccharides such as fructose, maltose, galactose, glucose, D-mannose, sorbose, and the like; disaccharides such as lactose, sucrose, trehalose, cellobiose, and the like; polysaccharides such as raffinose, melezitose, maltodextrin, dextran, starch and the like; and alditols such as mannitol, xylitol, maltitol, lactitol, xylitol, sorbitol (glucitol), inositol, and the like.

Surfactants may be included in certain formulations. Surfactants are typically used to prevent, minimize or reduce protein adsorption to surfaces and subsequent aggregation at gas-liquid, solid-liquid and liquid-liquid interfaces, and to control protein conformational stability. Suitable surfactants include, for example, polysorbate 20, polysorbate 80, other fatty acid esters of sorbitan esters, triton surfactants, lecithin, tyloxapol (tyloxapal) and poloxamer 188.

In some aspects, one or more antioxidants are included in the pharmaceutical composition. Antioxidant excipients may be used to prevent oxidative degradation of the protein. Reducing agents, oxygen/radical scavengers and chelating agents are useful antioxidants in this regard. Antioxidants are generally water-soluble and maintain their activity throughout the shelf life of the product. EDTA is another useful antioxidant.

Certain formulations contain metal ions that are protein cofactors and are necessary for the formation of protein coordination complexes. Metal ions can also inhibit some processes that degrade proteins. For example, magnesium ions (10-120 mM) can be used to inhibit isomerization of aspartic acid to isoaspartic acid.

Tonicity enhancing agents may also be included in certain formulations. Examples of such agents include alkali metal halides, preferably sodium or potassium chloride, mannitol and sorbitol.

One or more preservatives may be included in certain formulations. Preservatives are necessary when developing multi-dose parenteral formulations that involve more than one withdrawal from the same container. Their main function is to inhibit microbial growth and ensure sterility of the product throughout the shelf life or terms of use of the pharmaceutical product. Suitable preservatives include phenol, m-cresol, p-cresol, o-cresol, chlorocresol, benzyl alcohol, phenylmercuric nitrite, phenoxyethanol, benzyl alcohol, formaldehyde, chlorobutanol, magnesium chloride (e.g., hexahydrate), alkyl p-hydroxybenzoates (methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate, and the like), benzalkonium chloride, benzethonium chloride, sodium dehydroacetate, thimerosal, benzoic acid, salicylic acid, chlorhexidine, or mixtures thereof in an aqueous diluent.

The pharmaceutical compositions of the present disclosure are formulated to be compatible with their intended route of administration. Examples of routes of administration are Intravenous (IV), intradermal, inhalation, transdermal, topical, transmucosal, and rectal administration.

Formulation components suitable for parenteral administration (e.g., intravenous, subcutaneous, intraocular, intraperitoneal, intramuscular) include sterile diluents such as water for injection, saline solutions, fixed oils, polyethylene glycols, glycerol, propylene glycol, or other synthetic solvents; antibacterial agents such as benzyl alcohol or methylparaben; antioxidants such as ascorbic acid or sodium bisulfite; chelating agents such as EDTA; buffers, such as acetates, citrates or phosphates, and agents for modulating tonicity, such as sodium chloride or dextrose.

For intravenous administration, suitable carriers include physiological saline, bacteriostatic water, cremophor EL ^TM (BASF, parsippany, N.J.), or Phosphate Buffered Saline (PBS). The carrier should be stable under the manufacturing conditions and should be antimicrobial preserved. The carrier may be a solvent or dispersion medium containing, for example, water, ethanol, polyols (e.g., glycerol, propylene glycol, and liquid polyethylene glycol), and suitable mixtures thereof.

Further guidance regarding suitable formulations depending on the form of delivery is provided, for example, in Remington's Pharmaceutical Sciences, 22 nd edition, (Loyd v. Allen et al) Pharmaceutical Press (2013).

The pharmaceutical formulation may be sterile. Sterilization may be accomplished by any suitable method, such as filtration through a sterile filtration membrane. Where the composition is lyophilized, filter sterilization may be performed before or after lyophilization and reconstitution.

As shown in examples 7 and 8, activatable HBPC described herein exhibits a relative resistance to aggregation even at relatively high concentrations. Thus, in another aspect, provided herein is a composition comprising any activatable HBPC and water described herein, wherein activatable HBPC is present at a concentration of at least 1mg/mL, and wherein the composition comprises at least 95% monomer activatable HBPC, or at least about 96% monomer activatable HBPC, or at least about 97% monomer activatable HBPC, or at least about 98% monomer activatable HBPC, or at least about 99% monomer activatable HBPC. As used herein, the term "monomer activatable HBPC" refers to activatable HBPC in a non-aggregated form. In certain of these aspects, the composition comprises at least about 2mg/ml and at least 95% monomer activatable HBPC, or at least about 96% monomer activatable HBPC, or at least about 97% monomer activatable HBPC, or at least about 98% monomer activatable HBPC, or at least about 99% monomer activatable HBPC. In some aspects, the composition comprises at least about 3mg/ml and at least 95% monomer activatable HBPC, or at least about 96% monomer activatable HBPC, or at least about 97% monomer activatable HBPC, or at least about 98% monomer activatable HBPC, or at least about 99% monomer activatable HBPC. In some aspects, the composition comprises at least about 4mg/ml and at least 95% monomer activatable HBPC, or at least about 96% monomer activatable HBPC, or at least about 97% monomer activatable HBPC, or at least about 98% monomer activatable HBPC, or at least about 99% monomer activatable HBPC. The percentage of monomer activatable HBPC can be readily determined by, for example, size Exclusion (SE) -HPLC, as shown in example 7, wherein the percentage of monomer activatable HBPC is determined to correspond to the percentage of peak area of monomer activatable HBPC based on the total peak area.

Examples

The embodiments in this embodiment section are provided by way of illustration and not limitation.

Example 1: construction and expression of activatable heteromultimeric bispecific polypeptides

Two illustrative activatable Heteromultimeric Bispecific Polypeptide Complexes (HBPC), namely complex-57 and complex-67, were prepared having the structure shown in figure 1. Each of these activatable HBPC constructs has three polypeptides as shown in figure 1. The scFv was anti-CD 3 epsilon in each case, and the second targeting domain (i.e., VH2 and VL 2) in each case targeted EGFR. The EGFR targeting domain in each construct is the same, but the CD3 epsilon targeting domain is different.

The components of complex-67 are listed in tables 5A-5C and the components of construct complex-57 are listed in tables 6A-6C.

TABLE 5A Complex-67 first polypeptide

* The corresponding polynucleotide sequence is SEQ ID NO. 112 (NO terminal lysine is present in the purified protein, whether or not terminal lysine is present in the gene) or SEQ ID NO. 139.

⁺⁺ Contains an N-terminal spacer, SEQ ID NO 33.

^Δ Fc1 is located at the C-terminus of the CH1 (SEQ ID NO: 26) -hinge (SEQ ID NO: 34) sequence.

TABLE 5B Complex-67 second polypeptide

* The corresponding polynucleotide sequence is SEQ ID NO. 113 or alternatively SEQ ID NO. 115.

⁺⁺ Contains an N-terminal spacer, SEQ ID NO:117.

TABLE 5C third polypeptide component of Complex-67

^* The corresponding polynucleotide sequence is SEQ ID NO. 114 (NO terminal lysine is present in the purified protein, whether or not terminal lysine is present in the gene) or SEQ ID NO. 141. ⁺⁺ Comprising a hinge (SEQ ID NO: 35) at the N-terminus of Fc 2.

The amino acid sequence and polynucleotide sequence encoding complex-67 are provided below. The composition of the polypeptide sequence is as follows: the spacer sequence is in brackets, the masking sequence is underlined, the linker is bold, the substrate (i.e., cleavable moiety) is italic, and the CD3 binding agent is italic and underlined.

First polypeptide

In some aspects, the first polypeptide has the amino acid sequence of SEQ ID NO. 120 (without a spacer, but with a C-terminal lysine) or the amino acid sequence of SEQ ID NO. 120 (without a C-terminal lysine).

In the second polypeptide depicted below, the spacer sequence is underlined in brackets, the masking sequence is underlined, the linker is bold, and the substrate (i.e., the cleavable moiety) is italicized.

Second polypeptide

In the third polypeptide depicted below, the hinge region is bold and underlined, and the remainder of the sequence is Fc2.

Third polypeptide

DKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPCEEQYGSTYRCVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYDTTPPVLDSDGSFFLYSDLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPG(SEQ ID NO:32), Optionally with a C-terminal lysine (SEQ ID NO: 36).

Nucleic acid

Polynucleotide encoding a first polypeptide (SEQ ID NO: 112)

CAAGGACAATCTGGCTCTGTGTCCACCACCTGTTGGTGGGACCCTCCATGCACACCTAATACCGGCAGCTCTGGTGGCTCTGGCGGAAGCGGAGGACTGTCTGGCAGATCCGATGATCACGGCGGAGGATCTGAGGTGCAGCTGGTTGAATCTGGTGGCGGACTGGTTCAGCCTGGCGGATCTCTGAAACTGAGCTGTGCCGCCAGCGGCTTCACCTTCAACAAATACGCCATGAACTGGGTCCGACAGGCCCCTGGCAAAGGCCTTGAATGGGTCGCCAGAATCAGAAGCAAGTACAACAACTATGCCACCTACTACGCCGACAGCGTGAAGGACAGATTCACCATCAGCCGGGACGACAGCAAGAACACCGCCTACCTGCAGATGAACAACCTGAAAACCGAGGACACCGCCGTGTACTACTGTGTGCGGCACGGCAACTTCGGCAACAGCTACATCAGCTACTGGGCCTATTGGGGCCAGGGCACACTGGTCACAGTTTCTAGTGGCGGAGGCGGATCTGGCGGCGGTGGAAGTGGCGGCGGAGGTTCTCAAACAGTGGTCACCCAAGAGCCTAGCCTGACCGTTTCTCCTGGCGGAACCGTGACACTGACATGCGGATCTTCTACAGGCGCCGTGACCAGCGGCAACTACCCTAATTGGGTGCAGCAGAAGCCAGGCCAGGCTCCTAGAGGACTGATCGGCGGCACAAAGTTTCTGGCTCCCGGAACACCAGCCAGATTCAGCGGTTCTCTGCTCGGAGGAAAGGCCGCTCTGACACTTTCTGGCGTGCAGCCTGAGGATGAGGCCGAGTACTATTGCGTGCTGTGGTACAGCAACAGATGGGTGTTCGGCGGAGGCACCAAGCTGACAGTTCTTGGAGGTGGCGGTAGCCAGGTCCAGCTGAAACAATCTGGACCCGGACTCGTGCAGCCAAGCCAGAGCCTGTCTATCACCTGTACCGTGTCCGGCTTCAGCCTGACCAATTACGGCGTGCACTGGGTTCGACAATCTCCCGGCAAGGGACTCGAATGGCTGGGAGTGATTTGGAGCGGCGGCAACACCGACTACAACACCCCATTCACCAGCAGACTGAGCATCAACAAGGACAACAGCAAGTCCCAGGTGTTCTTCAAGATGAACTCCCTGCAGAGCCAGGATACCGCCATCTATTACTGCGCTCGGGCCCTGACCTACTATGACTACGAGTTTGCCTACTGGGGACAGGGAACCCTCGTGACAGTGTCTGCTGCTAGCACAAAGGGCCCTAGCGTTTTCCCACTGGCTCCCAGCAGCAAGTCTACATCCGGTGGAACAGCCGCTCTGGGCTGCCTGGTCAAGGATTACTTTCCCGAGCCAGTGACCGTGTCCTGGAATAGCGGAGCACTGACATCTGGCGTGCACACATTTCCAGCCGTGCTGCAGTCTAGCGGCCTGTACTCTCTGTCCAGCGTTGTGACAGTGCCCAGCAGCTCTCTGGGCACCCAGACCTACATCTGCAATGTGAACCACAAGCCTAGCAACACCAAGGTGGACAAGAAGGTGGAACCCAAGAGCTGCGATAAGACACACACCTGTCCTCCATGTCCTGCTCCAGAGCTGCTCGGAGGCCCTTCCGTGTTTCTGTTCCCTCCAAAGCCTAAGGACACCCTGATGATCAGCAGAACCCCTGAAGTGACCTGCGTGGTGGTGGATGTGTCCCACGAGGATCCCGAAGTGAAGTTCAATTGGTACGTCGACGGCGTGGAAGTGCACAATGCCAAGACCAAGCCTTGCGAGGAACAGTACGGCAGCACCTACAGATGCGTGTCCGTGCTGACAGTGCTGCACCAGGATTGGCTGAACGGCAAAGAGTACAAGTGCAAGGTGTCCAACAAGGCCCTGCCTGCTCCTATCGAGAAAACCATCAGCAAGGCCAAGGGCCAGCCTAGAGAACCCCAGGTGTACACACTGCCTCCAAGCCGGAAAGAGATGACCAAGAATCAGGTGTCCCTGACCTGCCTGGTCAAGGGCTTCTACCCTTCCGATATCGCCGTGGAATGGGAGAGCAATGGACAGCCCGAGAACAACTACAAGACAACCCCTCCTGTGCTGAAGTCCGACGGCTCATTCTTCCTGTACAGCAAGCTGACCGTGGACAAGAGCAGATGGCAGCAGGGCAACGTGTTCAGCTGCAGCGTGATGCACGAGGCCCTGCACAACCACTACACCCAGAAGTCCCTGTCTCTGAGCCCCGGCAAA

In variants of this exemplary polynucleotide, the codon encoding the C-terminal lysine may not be present (i.e., SEQ ID NO: 139).

Polynucleotide encoding a second polypeptide (SEQ ID NO: 113)

CAAGGCCAGTCTGGCCAAGGTCTTAGTTGTGAAGGTTGGGCGATGAATAGAGAACAATGTCGAGCCGGAGGTGGCTCGAGCGGCGGCTCTATCTCTTCCGGACTGCTGTCCGGCAGATCCGACCAGCACGGCGGAGGATCCCAAATCCTGCTGACACAGTCTCCTGTCATACTGAGTGTCTCCCCCGGCGAGAGAGTCTCTTTCTCATGTCGGGCCAGTCAGTCTATTGGGACTAACATACACTGGTACCAGCAACGCACCAACGGAAGCCCGCGCCTGCTGATTAAATATGCGAGCGAAAGCATTAGCGGCATTCCGAGCCGCTTTAGCGGCAGCGGCAGCGGCACCGATTTTACCCTGAGCATTAACAGCGTGGAAAGCGAAGATATTGCGGATTATTATTGCCAGCAGAACAACAACTGGCCGACCACCTTTGGCGCGGGCACCAAACTGGAACTGAAACGTACGGTGGCTGCACCATCTGTCTTCATCTTCCCGCCATCTGATGAGCAGTTGAAATCTGGAACTGCCTCTGTTGTGTGCCTGCTGAATAACTTCTATCCCAGAGAGGCCAAAGTACAGTGGAAGGTGGATAACGCCCTCCAATCGGGTAACTCCCAGGAGAGTGTCACAGAGCAGGACAGCAAGGACAGCACCTACAGCCTCAGCAGCACCCTGACGCTGAGCAAAGCAGACTACGAGAAACACAAAGTCTACGCCTGCGAAGTCACCCATCAGGGCCTGAGCTCGCCCGTCACAAAGAGCTTCAACAGGGGAGAGTGT

The second polypeptide of complex-67 is also encoded by a polynucleotide having the sequence of SEQ ID NO. 115.

Polynucleotide encoding a third polypeptide (SEQ ID NO: 114)

GATAAGACCCACACCTGTCCTCCATGTCCTGCTCCAGAACTGCTCGGCGGACCTTCCGTGTTCCTGTTTCCTCCAAAGCCTAAGGACACCCTGATGATCAGCAGAACCCCTGAAGTGACCTGCGTGGTGGTGGATGTGTCCCACGAGGATCCCGAAGTGAAGTTCAATTGGTACGTGGACGGCGTGGAAGTGCACAACGCCAAGACAAAGCCCTGCGAGGAACAGTACGGCAGCACCTACAGATGCGTGTCCGTGCTGACAGTGCTGCACCAGGATTGGCTGAACGGCAAAGAGTACAAGTGCAAGGTGTCCAACAAGGCCCTGCCTGCTCCTATCGAGAAAACCATCAGCAAGGCCAAGGGCCAGCCTAGAGAACCCCAGGTGTACACACTGCCTCCAAGCCGGGAAGAGATGACCAAGAACCAGGTGTCCCTGACCTGCCTGGTCAAGGGCTTCTACCCTTCCGATATCGCCGTGGAATGGGAGAGCAATGGACAGCCCGAGAACAACTACGACACCACACCTCCAGTGCTGGACAGCGACGGCTCATTCTTCCTGTACAGCGACCTGACCGTGGACAAGAGCAGATGGCAGCAGGGCAACGTGTTCAGCTGCAGCGTGATGCACGAGGCCCTGCACAACCACTACACCCAGAAGTCCCTGAGCCTGTCTCCTGGCAAA

In variants of this exemplary polynucleotide, the codon encoding the C-terminal lysine may not be present (i.e., SEQ ID NO: 141).

Another exemplary activatable HBPC of the present disclosure is described herein that comprises a first polypeptide having the amino acid sequence of SEQ ID NO:38 (encoded by the polynucleotide sequence of SEQ ID NO:142 (NO terminal lysine in the purified protein, whether or not present in the gene) or SEQ ID NO: 143; a second polypeptide having the amino acid sequence of SEQ ID NO. 31 (encoded by the polynucleotide sequence of SEQ ID NO. 113 or SEQ ID NO. 115); and a third polypeptide having the amino acid sequence of SEQ ID NO. 32 (encoded by the polynucleotide sequence of SEQ ID NO. 114 (NO terminal lysine is present in the purified protein regardless of the presence or absence of terminal lysine in the gene) or SEQ ID NO. 141.

TABLE 6A Complex-57 first polypeptide

^* The corresponding polynucleotide sequence is SEQ ID NO. 160 (NO terminal lysine is present in the purified protein, whether or not terminal lysine is present in the gene) or SEQ ID NO. 142.

⁺⁺ Contains an N-terminal spacer (SEQ ID NO: 117).

^Δ Fc1 is located at the C-terminus of the CH1 (SEQ ID NO: 26) -hinge (SEQ ID NO: 34) sequence.

TABLE 6B Complex-57 second polypeptide

* The corresponding polynucleotide sequence is SEQ ID NO. 113 or alternatively SEQ ID NO. 115.

⁺⁺ Contains an N-terminal spacer, SEQ ID NO:117.

TABLE 6C Complex-57 third polypeptide

^* The corresponding polynucleotide sequence is SEQ ID NO. 114 (NO terminal lysine is present in the purified protein, whether or not present in the gene) or SEQ ID NO. 141.

⁺⁺ Comprising a hinge (SEQ ID NO: 35) at the N-terminus of Fc 2.

Construction of control activatable anti-EGFR, anti-CD 3 heteromultimeric bispecific polypeptides

The control activatable bispecific antibody construct, referred to herein as "CI106", is prepared as described in international patent application publication No. WO 2019/075405, which is incorporated herein by reference. CI106 is an activatable dual-arm bivalent bispecific antibody construct that consists of four polypeptides corresponding to two identical heavy chains (two first polypeptides) and the same light chain (two second polypeptides), wherein each heavy chain and light chain forms one arm of the bispecific antibody construct. Bispecific antibodies are "bivalent" in that they have two binding domains of each type (i.e., two EGFR binding domains and two CD3 binding domains). The amino acid sequence of the light chain is identical to the amino acid sequence of the second polypeptide of complex-67 and complex-57. The heavy chain of CI106 and the first polypeptide of complex-67 have the same spacer, cleavable moiety, anti-EGFR VH, and cleavable moiety components. The heavy chain of CI106 and the first polypeptide of complex-57 have the same spacer, anti-CD 3 MM/MM1, cleavable moiety, anti-CD 3 VL/VH (and the same anti-CD 3 scFv) and anti-EGFR VH components. For CI106, all four targeting domains (two anti-CD 3 binding domains and two anti-EGFR binding domains) were masked. The components of CI106 are provided in tables 7A-7B.

TABLE 7A CI106 heavy chain Components

* The corresponding polynucleotide sequence is SEQ ID NO. 125 (the protein appears to lose terminal lysines during expression/purification).

⁺⁺ Contains an N-terminal spacer (SEQ ID NO: 116).

^Δ The Fc domain is located at the C-terminus of the CH1 (SEQ ID NO: 26) -hinge (SEQ ID NO: 34) sequence.

TABLE 7B light chain Components of CI106

* The corresponding polynucleotide sequence is SEQ ID NO. 113 or alternatively SEQ ID NO. 115.

++ Contains the N-terminal spacer and SEQ ID NO. 117.

Example 2: can activate the binding of anti-EGFR, anti-CD 3 heteromultimeric bispecific polypeptide to EGFR ⁺ HT-29 cells and CD3 epsilon ⁺ Jurkat cells

To confirm whether the described anti-EGFR and anti-CD 3 masking peptides are capable of inhibiting binding of activatable heteromultimeric bispecific polypeptide complexes to EGFR and CD3, a flow cytometry-based binding assay was performed.

HT-29-luc2 (PERKIN ELMER, inc., waltham, MA (previously CALIPER LIFE SCIENCES, inc.) and Jurkat (clone E6-1, ATCC, TIB-152) cells were cultured in RPMI-1640+glutamax (Life Technologies, catalog No. 72400-047) supplemented with 10% heat-inactivated fetal bovine serum (HI-FBS, life Technologies, catalog No. 10438-026) as activatable HBPC, which activatable HBPC was proteolytically cleaved to produce an activated form, activatable HBPC was also produced, which activatable HBPC was subsequently not proteolytically cleaved prior to the experiment, the activated CI106 (bivalent dual-arm bispecific construct), activated complex-57 (HBPC) and activated complex-67 (HBPC) were tested, and the activatable (masked) HBPC complex-57, (masked) HBPC complex-67 and dual bivalent-bispecific duplex, such as that in the combination of MC 106 and CD3 (ML) and anti-CD 3, was used as the anti-binding agent in combination of the anti-CD 106 and anti-CD 3 (CD 15) and anti-scFv 106 (CD 3 and anti-CD 15) were also produced.

HT29-luc2 cells were detached with Versene ^TM (Life Technologies, catalog 15040-066), washed at about 150,000 cells/Kong Tupu in 96-well plates, and resuspended in 50. Mu.L of activated or activatable (masked) HBPC. Jurkat cells were counted and plated as described for HT29-luc2 cells. Titration of activated (unmasked) HBPC or activatable (masked) HBPC was started from the concentrations shown in figures 2A and 2B, followed by 3-fold serial dilutions in FACS staining buffer +2% FBS (BD Pharmingen, catalog No. 554656). Cells were incubated at 4℃for about 1 hour with shaking, harvested and washed with 2X 200. Mu.L of FACS staining buffer. Cells were resuspended in 50 μl of Alexa Fluor 488 conjugated anti-human IgG Fc (10 μg/ml Jackson ImmunoResearch) and incubated with shaking at 4 ℃ for about 1 hour. Cells were harvested, washed and resuspended in a final volume of 200. Mu.L of FACS staining buffer containing 2.5. Mu.g/mL 7-AAD (BD Biosciences, catalog number 559925). Cells stained with the secondary antibody alone served as negative controls. Data was collected on Attune NxT flow cytometer and usedV10 (Treestar) the Median Fluorescence Intensity (MFI) of living cells was calculated. Background-subtracted MFI data were plotted in GRAPHPAD PRISM using curve-fitting analysis.

As shown in fig. 2A-2B, activatable HBPC (complex-57 and complex-67) and CI106 (masked) exhibited reduced binding to both EGFR and CD3 targets relative to activated (unmasked) complex-57, activated (unmasked) complex-67, and activated (unmasked) CI 106. The right shift of the binding curve indicates a decrease in binding. In this cell binding experiment, the EGFR masking efficiency was 105 for complex-57, 338 for complex-67, and 594 for CI 106.

Example 3: activatable and activatable HBPC biological activity

The biological activity of activatable (masked) and activatable (unmasked) HBPC was determined using a cytotoxicity assay. Human PBMC were purchased from Stemcell Technologies (Vancouver, canada) and co-cultured with the EGFR-expressing cancer cell line HT29-luc2 (PERKIN ELMER, inc., waltham, mass. (previously CALIPER LIFE SCIENCES, inc)) in RPMI-1640+glutamax supplemented with 5% heat-inactivated human serum (Sigma, catalog H3667) at a 5:1E (CD3+):T ratio. Titration of activated (unmasked) CI106 (control), activated (unmasked) complex-57 (HBPC) and activated (unmasked) complex-67 (HBPC) and CI106 (control), complex-57 (activatable HBPC) and complex-67 (activatable HBPC) were tested. After 48 hours, cytotoxicity was assessed using ONE-GloTM luciferase assay system (Promega, madison, WI catalogue E6130). At the position ofLuminescence was measured on M200 Pro (TECAN TRADING AG, switzerland). Percent cytotoxicity was calculated and plotted in GRAPHPAD PRISM by curve fit analysis. The potency of activated molecules was compared by calculating the EC50 ratio. Masking efficiency was calculated as the ratio of intact to activated EC50 per molecule.

As shown in fig. 3A and 3B, activatable (masked) HBPC has an offset dose response curve relative to activatable (unmasked) HBPC.

In this assay, the data in FIG. 3A shows that the masking efficiency of CI106 is 29,650, and that of complex-57 is 1,034. The data in fig. 3B shows that the masking efficiency of CI106 is 26,537 and that of complex-67 is 7,141. Based on multiple experiments using this assay, complex-57 generally exhibited a 10-42 fold reduction in potency compared to complex-67.

Example 4: HBPC induces regression of established HT29 tumors in mice

In this example, the ability of activatable (masked) HBPC complex-67 and control CI106 to induce regression of established HT29 xenograft tumors or reduce growth of those tumors in NSG mice transplanted with human PBMCs was analyzed.

Human colon cancer cell line HT29-luc2 (PERKIN ELMER, inc., waltham, mass.) was cultured according to established procedures. Purified, frozen human PBMC were obtained from Hemacare, inc. (Van Nuys, CA). NSG (NOD. Cg-PRKDCSCID IL rg ^tm1Wjl/SzJ) mice were obtained from The Jackson Laboratories (Bar Harbor, ME).

On day 0, 100. Mu.L of 2X10 ⁶ HT29-luc2 cells in RPMI+ Glutamax serum-free medium was inoculated subcutaneously on the right flank of each mouse. On day 3, previously frozen PBMCs from a single donor were administered (intraperitoneally (i.p.)) at a CD3 ⁺ T cell to tumor cell ratio of 1:1. When tumor volumes reached 150-200mm ³ (about day 12), mice were randomly grouped, allocated to treatment groups and dosed intravenously according to table 8. Tumor volumes and body weights were measured twice weekly. The dosage level of complex-67 was adjusted to account for the molecular weight difference between CI106 and complex-67.

Table 8 group and dose of HT29-luc2 xenograft study.

As shown in fig. 4, which depicts a plot of tumor volume versus days after initial therapeutic dose (day 0), there is a dose-dependent effect of complex-67 on growth of HT29-luc2 xenograft tumors. At equivalent doses (1 mg/kg of CI106 and 0.6mg/kg of complex-67), complex-67 exhibited more potent anti-tumor activity than control CI 106; p=0.0099 RMNOVA and Dunnett's).

Example 5: tumor regression of established HCT116 tumors in mice following treatment with activatable HBPC

Activated (unmasked) HBPC act-complex-67 and activatable (masked) HBPC complex-67 were analyzed for their ability to induce regression of established HCT116 xenograft tumors or reduce growth of the tumors in NSG mice transplanted with human T cells. According to established procedures, the human colon cancer cell line HCT116 (ATCC) was cultured in RPMI+Glutamax+10% FBS. Tumor models were performed as described in example 4. Mice were dosed according to table 9.

Table 9. Group and dose of hct116 xenograft study.

As shown in fig. 5, which depicts a plot of tumor volume versus study day after initial treatment dose (day 0), both molecules showed tumor regression at all doses tested.

Example 6: evaluation of the percentage of monomer after purification by ceramic hydroxyapatite Chromatography (CHT)

The double masked CI106 control and activatable (masked) HBPC complex-67 were purified using a ceramic hydroxyapatite chromatography column to compare the amount of dimerization at high concentrations during purification. This was assessed by analysis of the percentage of monomer at each step in the purification process.

Samples were loaded onto CHT type I, 40 μm bead columns (Biorad catalogue: 157-0040 and # 157-0041) loaded with 20g/L resin. The column was washed with equilibration buffer 10mM NaPO4, 100mM histidine buffer pH 6.5, then eluted with 10mM NaPO4, 100mM histidine 200mM lysine-HCl buffer (pH 6.5) (for CI 106) and 10mM NaPO4, 100mM histidine 100mM lysine-HCl buffer (pH 6.5) (for complex-67) in 2mL fractions. CI106 was collected in 2mL fractions, and then five fractions were combined to form an eluate. For CI106, peak collection starts around 25mAU and stops around 300 mAU. Composite-67 was collected in a tube, with peak collection starting at 100mAU and stopping at 500 mAU. Followed by a 500mM NaPO4 (pH 7.0) stripping buffer step. The protein concentration of each fraction was quantified by UV absorption at a wavelength of 280 nm. The percentage of monomer in each fraction was determined by SE-HPLC (analytical scale size exclusion chromatography) based on total peak area.

In the binding phase of chromatography, the protein binds first to the top part of the column and moves down the column only when the upper part becomes full. This results in a high concentration of molecules on the column. The CI106 and complex-67 in multimeric form bound to the column with stronger binding force than in monomeric form and therefore stronger buffer was required to be completely removed from the column. Thus, when the column is eluted with a weaker buffer and then stripped with a stronger buffer, the eluent has a lower percentage of dimers (higher percentage of monomers) than the stripper. As shown in table 10, complex-67 (activatable HBPC) operation resulted in an increase in the percentage of 7.6% monomer in the eluent, leaving the high molecular weight material on the column until the stripping step, which resulted in a recovery of 77% in the eluent. Comparing it to the CI106 run, the CI106 run resulted in a 5.4% to 65.0% decrease in the monomer percentage in the eluate, although more dimer material (only 30.6% monomer) remained on the column until stripping, resulting in 81% recovery in the eluate.

Table 10.Cht chromatographic results

These results indicate that complex-67 did not undergo additional dimerization when at high concentration on the column, resulting in removal of almost all of the high molecular species in the eluate, with 98.5% monomer, as compared to only 65% for CI106. For CI106, more polymer material was present in the eluent reservoir than at the original load. However, because dimerization occurs when CI106 is subjected to high concentrations on the column, CI106 cannot be purified by this method or any estimated binding/elution chromatography method.

The improved behavior of complex-67 enables purification of high monomer complex-67 by CHT type 1 chromatography.

Example 7: assessment of concentration-dependent dimerization by concentration in a centrifugal concentrator

After centrifugation concentration and overnight incubation at the highest concentration, the percent monomers of the protein a and SEC purified formulations of complex-67 (activatable HBPC), complex-57 (activatable HBPC) and CI106 controls were compared.

Complex-67, complex-57 and CI106 were purified with protein A and SEC and then formulated in low pH buffers (10 mM acetate, 100mM lysine, pH 6). Sample 1:15 was diluted into PBS (753-45-01) and concentrated using Pierce ^TM protein concentrator PES 10K MWCO 0.5ml (Thermo Fisher catalog number 88513) by centrifugation at 14,000RPM for 2 minutes at each concentration. The highest concentration samples were stored overnight and the percent monomer was evaluated. The resulting concentrations and the percentages of monomer amounts are shown in table 11 and fig. 6.

TABLE 11 monomer activatable HBPC percent vs total protein concentration

Fig. 6 and table 11 show that as the concentration increases, complex-67 remains in solution at a high percentage of monomer (98% -99%) and very low aggregation. Comparing this to CI106, CI106 showed significant concentration-dependent dimerization with increasing concentration. Complex-57 showed very little concentration-dependent dimerization with a stable percentage of monomer remaining with increasing concentration. The percent monomer was also maintained during the overnight incubation at the highest concentration for complex-67, demonstrating the stability of the percent monomer at higher concentrations.

Example 8: comparison of alternative similar structures

In one group a group of activatable bispecific constructs targeting CD3 and a tumor-associated antigen (antigen a) is prepared, and in another group a group of activatable bispecific constructs targeting CD3 and a tumor-associated antigen (antigen B) is prepared. Neither antigen a nor antigen B is EGFR. Each group contains activatable HBPC of the present disclosure and other activatable dual masked monovalent, bispecific constructs referred to as substitute (form) 1 and substitute (form) 2 that differ from each other and from the activatable HBPC of the present disclosure in structure arrangement having the same components as activatable HBPC (i.e., the same anti-CD 3scFv, the same anti-tumor associated antigen VH and VL sequences, the same anti-CD 3 masking moiety and the same anti-tumor associated antigen masking moiety). The properties of each construct in each set were characterized as described in examples 9 and 10.

Example 9: comparison of monovalent, bispecific forms of double masking

The cytotoxicity assays were used to determine the biological activity and masking efficiency of the anti-CD 3, anti-antigen a bispecific constructs described in example 8 (i.e., in the form of activatable HBPC, alternative (form) 1, and alternative (form) 2 of the present disclosure). Ovcar-8 cells were co-cultured with human T cells at a ratio of 1:10 and serially treated with dilutions of the molecules in tables 12, 13 and 14. After 48 hours, cytotoxicity was assessed using CELL TITER Glo (Promega) according to the manufacturer's instructions. Masking efficiency was calculated as the ratio of the intact to activated EC ₅₀ for each molecule. The amino acid sequences of the anti-CD 3 scFv, the anti-CD 3 masking moiety, the anti-tumor associated antigens VH and VL, the anti-tumor associated antigen masking moiety, and the two cleavable moieties are identical in three different forms (i.e., activatable HBPC, substitution (form) 1, and substitution (form) 2 of the present disclosure). The masking efficiencies of activatable HBPC, substitute 1 and substitute 2 molecules and the corresponding unmasked control molecules are presented in tables 12 (anti-antigen a masking moiety ML21 and anti-CD 3 masking moiety ML 15), 13 (anti-antigen a masking moiety ML24 and anti-CD 3 masking moiety ML 15) and 14 (anti-antigen a masking moiety ML34 and anti-CD 3 masking moiety ML 15). Activatable HBPC exhibited the highest masking efficiency in each case, as shown below. Since the components in each form type are the same, the results indicate that the improvement in masking efficiency of activatable HBPC is due to the specific arrangement of the components of the activatable HBPC form that compare alternative (form) 1 and alternative (form) 2.

TABLE 12 masking efficiency of form-masks ML21 and ML 15-antigen A

TABLE 13 masking efficiency of form-masks ML24 and ML 15-antigen A

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TABLE 14 masking efficiency of form-masks ML34 and ML 15-antigen A

In table 13, activatable HBPC shows that the masking efficiency is increased 15-fold relative to substitute 2 and the masking efficiency is increased 2-4-fold relative to substitute 1. In Table 13 HBPC shows that the masking efficiency is 6460-8274, while the ME of alternative 2 is 112. In table 13, activatable HBPC shows that the masking efficiency is increased 68 times relative to substitute 2 and the masking efficiency is increased 10 times relative to substitute 1. In table 14, HBPC has a masking efficiency of 2491, while alternate 1 and alternate ME are 248. In Table 15, complex-463 was prepared in alternate 1 and 2 forms, and two assays were performed for complex-463 in alternate 1 form. HBPC shows a masking efficiency in the range 1500-2100ME, or HBPC increased by about 6-10 times relative to alternative 1ME and about 47 times relative to alternative 2.

These results indicate that the improvement in masking efficiency appears to be due to the specific structural arrangement of activatable HBPC of the present disclosure.

Example 10: cytotoxicity of activatable HBPC and surrogate bispecific molecules in CHO cell lines

Masking efficiency and cytotoxicity of activatable HBPC, surrogate 1 and surrogate 2 molecules (targeting CD3 and antigen B, respectively) were determined. CHO cells expressing antigen B were co-cultured with human PBMCs at a ratio of 1:10 and serially treated with dilutions of the molecules in table 15. After 48 hours of incubation, cytotoxicity was determined using Cytotox Glo (Promega) according to the manufacturer's instructions. Masking efficiency was calculated as the ratio of the intact to activated EC ₅₀ for each molecule. The results are shown in table 15 below.

TABLE 15 masking efficiency and cytotoxicity-antigen B

^*,**,+ Multiple experiments

HBPC may be activated to provide the best results. FIG. 7 shows cytotoxicity (as a percentage of cell lysis) of masked activatable HBPC (control-39), unmasked activatable HBPC control (complex-342), activatable polypeptide in the alternative (form 2) (complex-231) and unmasked alternative (form 2) control (complex-164).

The results indicate that the arrangement of components in the specific structure of activatable HBPC described herein appears to be associated with higher masking efficiency as compared to the masking efficiency of activatable monovalent, bispecific constructs having the same components arranged in alternative forms.

The magnitude of the masking efficiencies observed for activatable anti-CD 3, anti-antigen A HBPC and activatable anti-CD 3, anti-antigen B HBPC are consistent with the masking efficiencies observed for complex-67 and complex-57. These beneficial results appear to be independent of the particular target domain/amino acid sequence used.

Example 11: safety and efficacy of activatable anti-EGFR, anti-CD 3 TCB construct CI107

In this study, the safety and efficacy of CI107, an anti-EGFR, anti-CD 3 TCB construct with the same structural form as the CI106 control (described above), was evaluated in a preclinical model to assess the therapeutic potential for treating EGFR expressing tumors. CI107 is prepared as described in International patent application publication No. WO 2019/075405, which is incorporated herein by reference. The CI107 TCB construct is alternatively referred to in this example as a "T cell engagement bispecific antibody" or "TCB".

Method of

Animal study

All animal studies were conducted according to institutional animal care and use committee regulations governing the facility at which each study was conducted. Mouse xenograft studies were performed by CytomX Therapeutics, inc (CytomX), and cynomolgus monkey studies were performed by ALTASCIENCES (Everett, WA). All animal studies followed the USDA animal welfare act and the guidelines for laboratory animal care and use.

Material

All TCBs and other constructs described in this study (including CI107, CI128, CI020, CI011, CI040, CI048 and CI 104) were produced by CytomX Therapeutics, inc. CI107, CI128, CI020, CI011, CI040, and CI104 have the same structural form as CI 106. CI048 corresponds to the activated CI011. Activated TCB is produced by treatment with urokinase-type plasminogen activator (uPA) in vitro, followed by SEC purification (Desnoyers 2013). HT29-Luc2 cells were obtained from CALIPER LIFE SCIENCES (Hopkitton, mass.) and HCT116 and Jurkat cells were obtained from the American Type Culture Collection (ATCC). Human Peripheral Blood Mononuclear Cells (PBMC) were obtained as cryopreserved vials of cells from individual donors of HemaCare Corporation (Northridge, CA), allCells (Alameda, CA) or STEMCELL Technologies (Seattle, WA). NOD. Cg-PRKCDSCID IL g tm1Wjl/SzJ (NSG) mice were obtained from Jackson Laboratories (Sacramento, calif.).

Cell binding assay

HT29 and Jurkat cells were maintained in complete medium. HT29 cells were harvested using Versene ^TM cell dissociation buffer. Cells were centrifuged at 250x g min to 10 min and resuspended in FACS buffer containing 2% FBS (BD Pharminogen). Cells were plated in V-bottom 96-well plates at 150,000/Kong Tupu and treated with various concentrations of complex-07 or in vitro protease activated CI104 obtained by 3-fold serial dilutions in FACS buffer, starting with 1.5 μm CI107 for both HT29 and Jurkat cells, 0.05 μm activated CI104 for HT29 cells, and 0.5 μm activated CI104 for Jurkat cells. Cells were incubated at 4℃for 1 hour, washed twice with FACS buffer and resuspended in 10. Mu.g/ml Alexa Fluor 647 anti-human Fc secondary antibody. The cells were then incubated at 4℃for 30-60 minutes in the dark, washed twice with FACS buffer, resuspended in FACS buffer containing 7-AAD and analyzed on a MACSQuant flow cytometer (Miltenyi Biotech). The average fluorescence intensity data was corrected for secondary antibody background signal, plotted in GRAPHPAD PRISM, and EC50 values calculated.

Cytotoxicity assays

HCT116-Luc2 or HT29-Luc2 was plated at 10,000 cells/well in rpmi+5% human serum into 96-well white flat bottom tissue culture treatment plates (Costar # 3917). Human PBMC were freshly thawed and washed twice with RPMI+5% human blood, and 100,000 PBMC were added to wells containing HCT116-Luc2 or HT29-Luc2 in RPMI+5% human serum. Protease activated TCB or CI107 was then added to the wells at different concentrations obtained by 3-fold serial dilutions. The control wells contained untreated target cells + effector cells, target cells only, effector cells only, or medium only. Plates were then incubated at 37℃and 5% CO2 for about 48 hours. Cell viability was measured using ONE-Glo luciferase assay system (Promega, # e6120) and Tecan microplate reader. The percent cytotoxicity was calculated as follows: (1- (experimental RLU/untreated mean RLU)). 100.

In vitro T cell activation and cytokine analysis

T cell activation was measured by inducing CD69 expression in PBMC co-cultured with HT29-Luc2 or HCT116-Luc2 cells. HT29-Luc2 or HCT116-Luc2 cells were plated at 10,000 cells/Kong Tupu in U-bottom non-stick panels. Human PBMCs were freshly thawed and washed twice with serum-containing RPMI and 100,000 PBMCs per well were added to the tumor cell-containing plates. Duplicate plates containing PBMCs alone were inoculated for flow cytometry compensation controls. Three-fold serial dilutions of CI107, activated CI107 or CI128 were prepared in medium and added to plated cells. Cells were incubated at 37℃and 5% CO ₂ for 16 hours. To prepare for flow cytometry analysis, plates were centrifuged at 250x g for 10-15 minutes. The supernatant was removed for cytokine analysis, fc blocking solution (Human TruStain FcX, bioLegend) was added to each well and the plates incubated for 10 minutes. A mixture of antibodies or appropriate compensation controls containing anti-CD 45-FITC (BioLegend), anti-CD 3-Pacific blue (BioLegend), anti-CD 8a-APC (BioLegend) and anti-CD 69-PE-Cy7 (BioLegend) was added to the wells and the plates were incubated for 30-60 minutes at 4℃with shaking in the absence of light. The plates were then washed with FACS buffer and resuspended in FACS buffer containing 7-AAD. Fluorescence was measured using Attune flow cytometry and 15,000 events representing PBMCs were collected.

For cytokine analysis, meso Scale Discovery U-PLEX plate assay (Meso Scale Diagnostics, rockville, mass.) was used. U-PLEX plates were prepared according to the manufacturer's protocol to evaluate the levels of MCP-1, TNF- α, IL-6, IL-2 and IFN- γ. Supernatant samples collected from HT29-Luc2 or HCT116-Luc2 co-cultured with PBMC and treated with masked (activatable) CI107, activated (also referred to herein as "act-") CI107 or CI128 were diluted, added to plates and processed according to manufacturer's instructions.

In vivo efficacy study

For in vivo experiments, the effect of TCB on tumor growth was measured in mice bearing HT29-Luc2 or HCT116 tumors and transplanted with human T cells generated by Intraperitoneal (IP) injection of human PBMCs. On day 0, 200 ten thousand HT29-Luc2 or HCT116 cells were subcutaneously injected into the flank of female NSG mice in 100 μl serum-free RPMI. Frozen PBMCs from individual donors were thawed freshly and administered by intraperitoneal injection on day 3 in 100-200 μl rpmi+ Glutamax serum-free medium. The percentage of cd3+ T cells of PBMCs was previously characterized and the number of PBMCs to be used for in vivo administration was based on a cd3+ T cell to tumor cell ratio of 1:1. Mice were randomized using tumor measurements on about day 12 prior to Intravenous (IV) administration of TCB, control article or vehicle. Animals were given test articles once a week for 3 weeks, and tumor volumes and body weights were recorded twice a week. The activated TCB CI104 was used for in vivo studies. The CI104 construct differs from CI107 only in the cleavable linker used to tether the CD3 mask to the scFv. After in vitro protease activation to completely remove the mask, activated CI104 was identical to activated CI107 and can be used to evaluate the activity of activated CI107, and subsequent in vitro cytotoxicity studies demonstrated that the activity of activated CI104 was identical to the activity of activated CI 107.

Non-human primate safety study

Depending on the test article, male cynomolgus monkeys received a slow intravenous bolus of the test article on day 1, or received once on days 1 and 15. Clinical observations were made twice daily after administration of the test article. Blood samples were collected at various time points post-dosing for analysis of cytokine release, serum chemistry, hematology, and toxicology. Serum samples were subjected to cytokine analysis using Life Technologies Monkey Magnetic-Plex Panel kit (Thermo FISHER SCIENTIFIC, waltham, mass.). For toxicological analysis, samples were processed into plasma prior to shipment and stored at-60 ℃ to-86 ℃ for analysis by AIT Bioscience (Indianapolis IN) or CytomX. Plasma concentrations of test articles were measured by ELISA using anti-idiotype capture antibodies and anti-human IgG (Fc) capture antibodies. The toxicokinetic analysis was performed by Northwest PK Solutions using Phoenix WinNonlin v 6.4.4 (Certara, princeton, NJ) using a non-compartmental analysis.

Results

CI107 was designed as a double masked (activatable) double arm bivalent bispecific molecule containing anti-EGFR and anti-CD 3 domains. CI107 was generated using a cetuximab-derived antibody with an SP 34-derived anti-CD 3 ε scFv fused to the N-terminus of the heavy chain. CI107 has a human IgG1Fc domain with mutations that silence Fc function. To generate CI107, specific masking peptides of the anti-EGFR antibody component were fused to the N-terminus of the light chain using a protease cleavable substrate linker flanked by flexible Gly-Ser rich peptide linkers, as previously described (Desnoyers 2013). Similarly, masking peptides specific for the anti-CD 3 component were added to scFv using protease cleavable substrate linkers. CI107 compromises Fc effector function to minimize cross-linking with Fc gamma R expressing cells. The design aims to maximize target binding and activity in the protease-rich tumor microenvironment while minimizing binding and activity in normal tissues. All comparative TCBs used in this example contained EGFR and CD3 binding domains, masks and linker peptides with varying degrees of cleavable. CI011 and CI040 are first generation versions of CI104 and CI 107. The CI104 and CI107 molecules contain optimized CD3 scFv, next generation cleavable linkers, and additional Fc silent mutations. CI104 and CI107 have the same mask, but differ in the CD3 protease linker, as do EGFR and CD3 binding domains; however, following protease activation, the activated TCB is identical. CI128 was used as a non-targeted control, where EGFR binding was replaced with an unrelated antibody (anti-RSV).

Masking impairs binding to EGFR on the cell surface.

To assess whether masking of EGFR binding domains impairs binding to EGFR expressed on the cell surface, CI107 was measured and binding of activated TCB constructs (i.e., act-TCB) to EGFR expressing HT29 and HCT116 cells was compared.

Target cells were incubated with increasing concentrations of CI107 or the comparably activated constructs and binding was assessed by flow cytometry. As shown in fig. 8A and 8B, the presence of EGFR mask in CI107 significantly attenuated binding to EGFR expressed on the cell surface compared to activated TCB CI 107. The calculated Kd for binding of the activated TCB construct to HT29 cells was 0.17nM, while the Kd for binding of CI107 was 91.28nM, representing a greater than 500-fold reduction in binding compared to activated TCB. Similar results were obtained using HCT116 cells. Binding of CI128 was also assessed, CI128 being a non-targeted control TCB containing the same anti-CD 3 molecule as CI107, but lacking EGFR targeting. This control did not bind to HT29 or HCT116 cells (see fig. 8A and 8B).

Masking impairs binding to CD3 on the lymphocyte surface.

To determine whether masking of the anti-CD 3 binding domain impairs binding of CI107 to CD3 on the lymphocyte surface, binding of CI107 and activated CI107 (i.e., activated TCB) to Jurkat cells was measured. As shown in FIG. 8C, activated TCB binds to Jurkat cells with a Kd of 0.62nM. However, binding of CI107 was not detected, and Kd could not be calculated. Activated control CI128 bound Jurkat cells with similar affinity as activated TCB.

Taken together, these data indicate that double masking of the anti-EGFR and anti-CD 3 binding domains in CI107 reduces binding to EGFR or CD3 expressing cells.

Masking reduces cytotoxicity and T cell activation in PBMC co-culture.

To determine whether targeting EGFR with CI107 could result in anti-tumor cell effects, an in vitro cytotoxicity assay was performed. Luciferase-expressing HT29 or HCT116 cells were co-cultured with human PBMCs and incubated with increasing concentrations of CI107, activated TCB, or non-targeted control CI 128. After 48 hours of incubation, the viability of HCT116-Luc2 or HT29-Luc2 cells was measured by a luciferase assay. As shown in fig. 9A, treatment with control CI128 resulted in minimal cytotoxicity on HCT116-Luc2 cells co-cultured with PBMCs, indicating that cytotoxic activity required conjugation of both EGFR and CD 3. In contrast, masked CI107 and activated CI107 (i.e., act-TCB) have cytotoxic effects on HCT116-Luc2 cells. However, activated TCBs produced cytotoxicity at much lower concentrations than the masked form, with EC50 values of 0.44pM and 7297pM, respectively. Similar results were observed in HT29-Luc2 cells, with an EC50 value of 0.25pM for activated TCB, as compared to 3678pM for CI107 (FIG. 9B). Thus, double masking of the anti-EGFR and anti-CD 3 domains in CI107 resulted in approximately 15,000 fold reduction in PBMC-mediated cytotoxic activity without protease activation.

Treatment with CI107 induced CD69 expression, CD69 being a marker of T cell activation.

To determine whether CI107 resulted in T cell activation, CD69 levels in PBMC co-cultured with HCT116-Luc2 or HT29-Luc2 cells were measured after treatment with masked CI107, activated CI107 (i.e., act-TCB) and control CI 128. CD69 serves as a marker of T cell activation; after TCR/CD3 engagement, CD69 expression is rapidly induced on the surface of T lymphocytes and acts as a costimulatory molecule for T cell activation and proliferation. Human PBMC co-cultured with HCT116-Luc2 or HT29-Luc2 cells were treated with increasing concentrations of CI107, activated TCB (i.e., activated CI 107) or control CI128 for 16 hours and CD69 expression levels were measured by flow cytometry. As shown in FIG. 9C, CI107 resulted in induction of CD69 expression on CD8+ T cells co-cultured with HCT116-Luc2 cells, with an EC50 of 14178pM. In contrast, treatment with activated CI107 resulted in CD69 induction with an EC50 of 7.65pM, reflecting an approximately 18,000 fold shift in T cell activation profile compared to CI 107. No T cell activation was observed with the non-EGFR targeted control CI128, indicating that CD3 alone engagement was insufficient to activate T cells. Similarly, treatment of PBMCs from the same donor co-cultured with HT29-Luc2 cells resulted in CD69 induction, with a masked CI107 EC50 value of 65971pM, compared to an activated TCB EC50 value of 8.75pM, reflecting an approximately 7500 fold difference in CD69 induction capacity (fig. 9D).

Treatment with CI107 resulted in cytokine release.

To further evaluate T cell activation in PBMCs co-cultured with EGFR-expressing cancer cells following treatment with TCB, cytokine release was assessed following treatment with CI107, activated TCB (i.e., activated CI 107), or control CI 128. The levels of IFN-gamma, IL-2, IL-6, MCP-1 and TNF-alpha were measured 16 hours after treatment with increasing concentrations of TCB. As shown in fig. 10A-10E, treatment with CI107 at a concentration in the range of 104pM resulted in the release of each cytokine measured. In contrast, activated TCB resulted in cytokine release after treatment with concentrations in the range of 1-100 pM. These results are generally consistent between different PBMC donor cells and cancer cell lines (HCT 116-Luc2 vs HT29-Luc 2).

Taken together, these data indicate that double masking of EGFR and CD3 binding domains in CI107 reduces T cell activation in the absence of protease activation.

The sensitivity of TCB to proteolytic cleavage is related to anti-tumor efficacy in vivo and T cells in tumors.

The antitumor efficacy of TCB was evaluated in vivo. Immunocompromised mice bearing HT29-Luc2 tumors and transplanted with human PBMC were treated weekly for 3 weeks with vehicle (PBS) or 0.3mg/kg TCB containing linkers with different protease sensitivities (CI 011, CI 040), non-cleavable linkers (CI 020) or unmasked bispecific therapeutic CI048. CI020 is expected to have minimal anti-tumor activity due to the non-cleavable linker, while unmasked CI048 is expected to have maximal efficacy. Both CI011 and CI040 contain EGFR and CD3 masks, with different protease sensitivity due to different linker peptides; the protease sensitivity of CI040 is higher than CI011.

As shown in fig. 11A, treatment with unmasked TCB CI048 resulted in tumor regression within one week after initiation of treatment. Similarly, treatment with masked CI011 and CI040 also resulted in tumor regression or arrest; the regression observed with CI040 was associated with higher cleavable linkers in this molecule compared to CI 011. In contrast, treatment with CI020 containing a non-cleavable linker did not affect tumor growth, indicating that protease cleavage was necessary for anti-tumor activity in TCB.

To determine if the anti-tumor efficacy mediated by the TCB tested correlates with T cell presence in the tumor, tumors were harvested one week after animals received either a 1mg/kg dose of masked TCB or activated TCB and immunohistochemistry for CD3 was performed. As shown in fig. 11B, very few T cells were observed in tumor tissue after treatment with vehicle or non-cleavable CI 020. In contrast, an increase in T cell number was observed following treatment with TCB CI040 or TCB CI048 activated by in vitro proteases. Likewise, TCBs with higher protease sensitivity (CI 040) result in a greater number of T cells in the tumor.

Taken together, these data indicate that TCBs can produce intratumoral T cells and in vivo antitumor efficacy that correlates with sensitivity to protease cleavage by EGFR and CD3 binding domain masks.

Treatment with CI107 induced a dose-dependent regression of established xenograft tumors.

The effect of CI107 on tumor growth in vivo was evaluated. NSG mice were subcutaneously implanted with HT29 cells, then PBMCs were intraperitoneally injected, and PBMCs were allowed to implant for approximately 11 days. Animals were then treated once a week with vehicle, 0.5mg/kg CI107, or 1.5mg/kg CI107 for 3 weeks. As shown in FIG. 12A, treatment with 0.5mg/kg CI107 resulted in tumor arrest, and 1.5mg/kg CI107 began to result in tumor regression approximately one week after the initiation of treatment.

The in vivo efficacy of CI107 was also evaluated in HCT116 tumors. Following tumor and PBMC implantation, animals were treated with vehicle, 0.3mg/kg CI107, 1mg/kg CI107, or 0.3mg/kg activated TCB. As shown in FIG. 12B, 0.3mg/kg CI107 delayed HCT116 tumor growth, while 1mg/kg CI107 and 0.3mg of activated TCB resulted in similar levels of tumor regression and stasis during treatment.

These data demonstrate that CI107 induces dose-dependent inhibition of tumor growth and regression in HT29 and HCT116 xenograft tumors, and that the antitumor activity of CI107 at 3-fold higher doses is similar to that of activated TCB.

The masked CI107 provides increased safety in cynomolgus monkeys relative to the activated CI 107.

Preclinical tolerance of CI107 was evaluated in cynomolgus study. Animals received a single administration of 0.06mg/kg or 0.18mg/kg of activated CI107 (i.e., act-TCB) and 0.6mg/kg, 2.0mg/kg, 4.0mg/kg or 6.0mg/kg of CI107, and the animals were subsequently subjected to clinical observations. Animals treated with 0.18mg/kg of activated TCB experienced severe clinical effects including vomiting, loss of appetite, pale complexion, hunchback posture and poor appearance, with adverse effects observed as early as 2 hours up to 10 days post-administration. Animals treated with 0.06mg/kg of activated TCB experienced moderate and transient clinical effects, including emesis and humpback posture on day 1 post-administration; based on the rapid regression of these effects, 0.06mg/kg was defined as the Maximum Tolerated Dose (MTD) of activated TCB. In contrast, animals treated with 2.0mg/kg CI107 experienced only a short and slight clinical effect (emesis on day 2), and animals treated with 0.6mg/kg CI107 did not experience any adverse effects. Animals treated with 4.0mg/kg CI107 experienced moderate clinical effects (including emesis at 4, 8 and 24 hours post-dose and anorexia at day 2). Animals treated with 6.0mg/kg CI107 were found to die on day 2. Clinical signs noted before death include humpback posture, pale complexion, vomiting and liquid stool after administration. Thus, 4.0mg/kg is considered to be the MTD of CI 107. Overall, the masked CI107 achieved a greater than 60-fold improvement in tolerability compared to the activated TCB.

Cytokine levels were also examined after treatment with activated CI107 or masked CI 107. As shown in FIG. 13, the levels of IL-6 (13A) and IFN-gamma (13B) were elevated in animals treated with activated TCB 8 hours after dosing. In contrast, minimal changes in IL-6 or IFN-gamma were observed following treatment with 0.6mg/kg or 2.0mg/kg CI 107; elevated levels of these cytokines were observed only after treatment with 4.0mg/kg CI 107. Consistent with clinical observations, CI107 varied cytokine release dose-response by more than 60-fold.

Analysis of serum chemistry also demonstrated the difference between activated TCB and CI 107. As shown in fig. 13C, treatment with activated TCB resulted in a dose-dependent increase in aspartate Aminotransferase (AST) (a marker of hepatocyte injury) 48 hours after administration. In contrast, no AST change was observed after treatment with CI107 at any tolerating dose level, indicating improved tolerability with this masked TCB.

To determine whether masking of EGFR and CD3 binding domains affects pharmacokinetics, plasma concentrations of activated TCB (i.e., activated CI 107) and masked CI107 after administration were measured. As shown in fig. 13D, activated TCB was rapidly cleared from the circulation within 24 hours after administration. In contrast, CI107 remained in plasma for up to 7 days after dosing, suggesting that masking may increase exposure relative to activated TCB. AUC (0-7) after single administration of 0.06mg/kg of activated TCB was 0.04 days nM (n=1), while AUC (0-7) after administration of 2mg/kg of CI107 was 331.7 days nM (average of n=3), indicating a greater than 8,000 fold increase in tolerogenic exposure.

This suggests that the improvement in tolerability and pharmacokinetics observed with masked CI107 is consistent with the expected attenuation of binding to EGFR and CD3 in normal tissue environments.

TABLE 16 sequence listing

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The scope of the present disclosure is not limited by the aspects described herein. Indeed, various modifications of the disclosure in addition to those described will become apparent to those skilled in the art from the foregoing description and accompanying drawings. Such modifications are intended to fall within the scope of the appended claims.

All references (e.g., publications or patents or patent applications) cited herein are hereby incorporated by reference in their entirety and for all purposes to the same extent as if each individual reference (e.g., publication or patent application) was specifically and individually indicated to be incorporated by reference in its entirety for all purposes.

Some aspects are within the following claims.

Claims (54)

1. An activatable Heteromultimeric Bispecific Polypeptide Complex (HBPC) comprising:

(a) A first polypeptide comprising (i) a single chain variable fragment (scFv) comprising a first heavy chain variable domain (VH 1) and a first light chain variable domain (VL 1), wherein the VH1 and the VL1 together form a first targeting domain that specifically binds a first target, (ii) a first masking moiety (MM 1), (iii) a first cleavable moiety (CM 1), (iv) a second heavy chain variable domain (VH 2), and (v) a first monomeric Fc domain (Fc 1);

(b) A second polypeptide comprising (i) a second light chain variable domain (VL 2), wherein the VH2 and the VL2 together form a second targeting domain that specifically binds a second target, (ii) a second masking moiety (MM 2), and (iii) a second cleavable moiety (CM 2); and

(C) A third polypeptide comprising (i) a second monomeric Fc domain (Fc 2), and (ii) no immunoglobulin variable domain;

wherein MM1 is a peptide that interferes with the binding of the first targeting domain to the first target, and MM2 is a peptide that interferes with the binding of the second targeting domain to the second target.

2. The activatable bispecific polypeptide complex of claim 1, wherein the first target is a T cell antigen polypeptide and the second target is a cancer cell surface antigen.

3. The activatable bispecific polypeptide complex of claim 1, wherein the first target is a cancer cell surface antigen and the second target is a T cell antigen polypeptide.

4. The activatable bispecific polypeptide complex of any one of claims 1-3, wherein the T cell antigen polypeptide is the epsilon chain of CD 3.

5. The activatable bispecific polypeptide complex of any one of claims 1-4, wherein the first polypeptide further comprises a heavy chain CH1 domain between the cancer cell surface antigen targeting domain VH2 and the monomeric Fc domain.

6. The activatable bispecific polypeptide complex of any one of claims 1-5, wherein the first polypeptide further comprises an immunoglobulin hinge region (HR 1) between the CH1 domain and the first monomeric Fc domain.

7. The activatable bispecific polypeptide complex of claim 6, wherein the first polypeptide comprises the following structural arrangement from amino terminus to carboxy terminus:

MM1-CM1-scFv-VH2-CH1-HR1-Fc1, wherein each "-" is independently a direct or indirect linkage.

8. The activatable bispecific polypeptide complex of any one of claims 1-7, wherein the second polypeptide further comprises a light chain constant domain CL1.

9. The activatable bispecific polypeptide complex of claim 8, wherein the second polypeptide comprises the following structural arrangement from amino terminus to carboxy terminus: MM2-CM2-VL2-CL1.

10. The activatable bispecific polypeptide complex of any one of claims 1-9, wherein the third polypeptide further comprises an immunoglobulin hinge region (HR 2).

11. The activatable bispecific polypeptide complex of any one of claims 1-10, wherein the third polypeptide comprises the following structural arrangement from amino terminus to carboxy terminus: HR2-Fc2.

12. The activatable bispecific polypeptide complex of claim 6 or claim 10, wherein the first polypeptide HR1 and the second polypeptide HR2 comprise the same amino acid sequence.

13. The activatable bispecific polypeptide complex of claim 6 or claim 10, wherein the first polypeptide HR1 and the second polypeptide HR2 comprise different amino acid sequences.

14. The activatable bispecific polypeptide complex of any one of claims 1-13, wherein the first polypeptide, the second polypeptide, and/or the third polypeptide comprises one or more linkers.

15. The activatable bispecific polypeptide complex of claim 14 comprising a linker in one or more of the following positions:

(a) Between MM1 and CM 1;

(b) Between MM2 and CM 2;

(b) Between the heavy and light variable domains of the scFv;

(c) Between the heavy chain variable domain and the CH1 domain;

(d) Between the CH1 domain and the hinge region;

(e) Between the hinge region and the Fc domain;

(g) Between CM2 and the light chain variable domain;

(h) Between the light chain variable domain and CL;

(i) Between the CH1 domain and the second Fc domain;

(j) Between the CH1 domain and the hinge region; and/or

(K) Between the hinge region and the second Fc domain.

16. The activatable bispecific polypeptide complex of claim 14 or 15, wherein the one or more linkers comprise about 1 to about 20 amino acids.

17. The activatable bispecific polypeptide complex of any one of claims 1-16, wherein MM1 is linked to CM1 via linker L1.

18. The activatable bispecific polypeptide complex of any one of claims 1-16, wherein MM2 is linked to CM2 via linker L2.

19. The activatable bispecific polypeptide complex of any one of claims 17 or 18, wherein the activatable bispecific polypeptide complex comprises both L1 and L2.

20. The activatable bispecific polypeptide complex of claim 19, wherein MM2 is linked to CM2 via linker L3 and CM2 is linked to scFv via linker L4.

21. The activatable bispecific polypeptide complex of any one of claims 14-20, wherein the amino acid sequences of L1, L2, L3 and/or L4 are identical.

22. The activatable bispecific polypeptide complex of any one of claims 14-20, wherein the amino acid sequence of at least one of L1, L2, L3 and/or L4 is different.

23. The activatable bispecific polypeptide complex of any one of claims 1-22, wherein the amino acid sequence of CM1 and the amino acid sequence of CM2 are identical.

24. The activatable bispecific polypeptide complex of any one of claims 1-22, wherein the amino acid sequence of CM1 and the amino acid sequence of CM2 are different.

25. The activatable bispecific polypeptide complex of any one of claims 1-25, wherein CM1 and CM2 each comprise a substrate for a protease present in the tumor microenvironment.

26. The activatable bispecific polypeptide complex of any one of claims 1-25, wherein CM1 and CM2 each independently comprise a substrate for the same protease.

27. The activatable bispecific polypeptide complex of any one of claims 1-25, wherein CM1 and CM2 comprise substrates for different proteases.

28. The activatable bispecific polypeptide complex of any one of claims 23-27, wherein CM1 and CM2 each independently comprise a substrate for a protease selected from the group of proteases shown in table 3.

29. The activatable bispecific polypeptide complex of any one of claims 23-27, wherein at least one of CM1 and CM1 comprises a substrate for a protease selected from the group consisting of: serine proteases and Matrix Metallopeptidases (MMPs).

30. The activatable bispecific polypeptide complex of any one of claims 1-29, wherein CM1 and/or CM2 comprises the amino acid sequence of SEQ ID No. 2, SEQ ID No. 14, SEQ ID No. 73-111 or SEQ ID No. 156-159.

31. The activatable bispecific polypeptide complex of any one of claims 1-30, wherein the MM1 and/or the MM2 comprises about 5 amino acids to about 40 amino acids.

32. The activatable bispecific polypeptide complex of any one of claims 15-31, wherein each linker is independently selected from the group consisting of:

(i) A glycine-serine based linker selected from the group consisting of: (GS) n, where n is an integer between 1 and 10, (GGS) n, where n is an integer of at least 1, (GGGS) n (SEQ ID NO: 40), (GGGGS) n (SEQ ID NO: 126), where n is an integer of at least 1, (GSGGS) n (SEQ ID NO: 41), where n is integers of at least 1 ,GSSGGSGGSG(SEQ ID NO:12),GGSG(SEQ ID NO:42),GGSGG(SEQ ID NO:43),GSGSG(SEQ ID NO:44),GSGGG(SEQ ID NO:45),GGGSG(SEQ ID NO:46) and GSSSG(SEQ ID NO:47),GGGGSGGGGSGGGGSGS(SEQ ID NO:48),GGGGSGS(SEQ ID NO:49),GGGGSGGGGSGGGGS(SEQ ID NO:50),GGGG SGGGGSGGGGSGGGGS(SEQ ID NO:51),GGGGS(SEQ ID NO:52),GGGGSGGGGS(SEQ ID NO:53),GGGS(SEQ ID NO:54),GGGSGGGS(SEQ ID NO:55),GGGSGGGSGGGS(SEQ ID NO:56),GSSGGSGGSG(SEQ ID NO:57),GGGSGGGGSGGGGSGGGGSGG GGS(SEQ ID NO:58),GGGSSGGS(SEQ ID NO:127) and GS; and (ii) linkers ：GSTSGSGKPGSSEGST(SEQ ID NO:59)、SKYGPPCPPCPAPEFLG(SEQ ID NO:60)、GGSLDPKGGGGS(SEQ ID NO:61)、PKSCDKTHTCPPCPAPELLG(SEQ ID NO:62)、GKSSGSGSESKS(SEQ ID NO:63)、GSTSGSGKSSEGKG(SEQ ID NO:64)、GSTSGSGKSSEGSGSTKG(SEQ ID NO:65) and GSTSGSGK PGSGEGSTKG (SEQ ID NO: 66) selected from the group consisting of glycine and serine and at least one of lysine, threonine or proline.

33. The activatable bispecific polypeptide complex of any one of claims 1-32, wherein the first polypeptide comprises a hinge (hinge 1) having the amino acid sequence of SEQ ID No. 34.

34. The activatable bispecific polypeptide complex of any one of claims 1-33, wherein the second polypeptide comprises a hinge (hinge 2) having the amino acid sequence of SEQ ID No. 35.

35. A pharmaceutical composition comprising the activatable bispecific polypeptide complex of any one of claims 1-34 and a pharmaceutically acceptable carrier.

36. A composition comprising water and the activatable bispecific polypeptide complex of any one of claims 1-34.

37. The composition of claim 36, comprising 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95% or up to 99% water.

38. A kit comprising the pharmaceutical composition of claim 35 or the composition of claim 36.

39. A nucleic acid comprising a nucleotide sequence encoding the first, second and/or third polypeptide of the activatable bispecific polypeptide complex of any one of claims 1-34.

40. A nucleic acid comprising a nucleotide sequence encoding the first polypeptide of the activatable bispecific polypeptide complex of any one of claims 1 to 34.

41. A nucleic acid comprising a nucleotide sequence encoding the second polypeptide of the activatable bispecific polypeptide complex of any one of claims 1 to 34.

42. A nucleic acid comprising a nucleotide sequence encoding the third polypeptide of the activatable bispecific polypeptide complex of any one of claims 1 to 34.

43. A vector comprising the nucleic acid of any one of claims 39-42.

44. A host cell comprising the vector of claim 43.

45. A method of producing an activatable bispecific polypeptide complex, the method comprising:

(a) Culturing the host cell of claim 44 in a liquid medium under conditions sufficient to produce said activatable HBPC; and

(B) Recovering the activatable HBPC.

46. A method of treating a disease in a subject, the method comprising administering to the subject a therapeutically effective amount of the activatable bispecific polypeptide complex of any one of claims 1-34 or the pharmaceutical composition of claim 35 or 36.

47. The method of claim 46, wherein the subject is a human.

48. The method of claim 46 or 47, wherein the disease is cancer.

49. The activatable bispecific polypeptide complex of any one of claims 1-34 or the pharmaceutical composition of claim 35 or the composition of claim 36 for use in inhibiting tumor growth in a subject in need thereof.

50. Use of an activatable bispecific polypeptide complex according to any one of claims 1-34 or a pharmaceutical composition according to claim 35 or a composition according to claim 36 in the manufacture of a medicament for the treatment of cancer.

51. An activatable bispecific polypeptide complex comprising:

(a) A first polypeptide comprising (i) a single chain variable fragment (scFv), wherein the scFv comprises a first heavy chain variable domain (VH 1) and a first light chain variable domain (VL 1), wherein VH1 and VL1 together form a T cell antigen targeting domain that specifically binds a T cell antigen polypeptide, (ii) a first masking moiety (MM 1), and (iii) a first cleavable moiety (CM 1); (iv) A second heavy chain variable domain (VH 2), (v) a first monomeric Fc domain (Fc 1), (vi) a heavy chain CH1 domain, and (vii) an immunoglobulin hinge region between the CH1 domain and the Fc 1;

(b) A second polypeptide comprising (i) a light chain variable domain (VL 2) that specifically binds a cancer cell surface antigen when paired with the VH2, (ii) a second masking moiety (MM 2), (iii) a second cleavable moiety (CM 2), and (iv) a light chain constant domain CL1; and

(C) A third polypeptide comprising a second monomeric Fc domain (Fc 2) and an immunoglobulin hinge region (HR 2), wherein the third polypeptide does not comprise an immunoglobulin variable domain, and;

wherein the first polypeptide comprises the following structural arrangement from amino terminus to carboxy terminus: MM1-CM1-scFv1-VH2-CH1-HR1-Fc1;

the second polypeptide comprises the following structural arrangement from amino terminus to carboxy terminus: MM2-CM2-VL2-CL1; and

The third polypeptide has the following structural arrangement from amino terminus to carboxyl terminus: HR2-Fc2, wherein each "-" is independently a direct or indirect linkage.

52. An activatable Heteromultimeric Bispecific Polypeptide Complex (HBPC) comprising:

(a) A first polypeptide comprising (i) a single chain variable fragment (scFv) that specifically binds a cancer cell surface antigen, (ii) a first masking moiety (MM 1), and (iii) a first cleavable moiety (CM 1); (iv) A heavy chain variable domain (VH 2), (v) a first monomeric Fc domain (Fc 1), (vi) a heavy chain CH1 domain, and (vii) an immunoglobulin hinge region between the CH1 domain and the first monomeric Fc domain;

(b) A second polypeptide comprising (i) a light chain variable domain (VL 2) of a specific binding T cell antigen polypeptide when paired with the first polypeptide VH2, (ii) a second masking moiety (MM 2), (iii) a second cleavable moiety (CM 2) and (iv) a light chain constant domain CL1; and

(C) A third polypeptide comprising a second monomeric Fc domain (Fc 2) and an immunoglobulin hinge region;

wherein the first polypeptide comprises the following structural arrangement from amino terminus to carboxy terminus: MM1-CM1-scFv1-VH2-CH1-HR1-Fc1;

the second polypeptide comprises the following structural arrangement from amino terminus to carboxy terminus: MM2-CM2-VL2-CL1; and

The third polypeptide has the following structural arrangement from amino terminus to carboxyl terminus: HR2-Fc2, wherein each "-" is independently a direct or indirect linkage, and wherein the third polypeptide does not comprise an immunoglobulin variable domain.

53. An activatable Heteromultimeric Bispecific Polypeptide Complex (HBPC) comprising:

(a) A first polypeptide comprising (i) a single chain variable fragment (scFv) that specifically binds a cancer cell surface antigen, (ii) a first masking moiety (MM 1), and (iii) a first cleavable moiety (CM 1); and a heavy chain variable domain (VH 2), (iv) a first monomeric Fc domain (Fc 1), (v) a heavy chain CH1 domain, and an immunoglobulin hinge region between the CH1 domain and (vii) the first monomeric Fc domain;

(b) A second polypeptide comprising (i) a light chain variable domain (VL 2) of a specific binding T cell antigen polypeptide when paired with the first polypeptide VH2, (ii) a second masking moiety (MM 2), (iii) a second cleavable moiety (CM 2) and (iv) a light chain constant domain CL1; and

(C) A third polypeptide consisting of a second monomeric Fc domain (Fc 2) and an immunoglobulin hinge region;

Wherein the first polypeptide has the following structural arrangement from amino terminus to carboxy terminus: MM1-CM1-scFv1-VH2-CH1-HR1-Fc1;

The second polypeptide has the following structural arrangement from amino terminus to carboxy terminus: MM2-CM2-VL2-CL1; and

The third polypeptide has the following structural arrangement from amino terminus to carboxyl terminus: HR2-Fc2, wherein each "-" is independently a direct or indirect linkage, and wherein the third polypeptide does not comprise an immunoglobulin variable domain.

54. A Heteromultimeric Bispecific Polypeptide Complex (HBPC) comprising:

(a) A first polypeptide comprising (i) a single chain variable fragment (scFv) comprising a first heavy chain variable domain (VH 1) and a first light chain variable domain (VL 1), wherein the VH1 and the VL1 together form a first targeting domain that specifically binds a first target, (ii) a second heavy chain variable domain (VH 2), and (iii) a first monomeric Fc domain (Fc 1);

(b) A second polypeptide comprising a second light chain variable domain (VL 2), wherein the VH2 and the VL2 together form a second targeting domain that specifically binds a second target; and

(C) A third polypeptide comprising a second monomeric Fc domain (Fc 2) and not comprising an immunoglobulin variable domain.