WO2022098910A1

WO2022098910A1 - Icos antibodies for treatment of lymphomas

Info

Publication number: WO2022098910A1
Application number: PCT/US2021/058110
Authority: WO
Inventors: Gianluca Carlesso; Peter Emtage; David Close; Lillian Lai-Yun SIU; Julio Chavez; Jeffrey A. Moscow
Original assignee: Medimmune, Llc; University Health Network; H. Lee Moffitt Cancer Center And Research Institute Inc.; The Usa, As Represented By The Secretary, Department Of Health And Human Services
Priority date: 2020-11-04
Filing date: 2021-11-04
Publication date: 2022-05-12

Abstract

The present disclosure provides anti-ICOS antibodies and antigen-binding fragments thereof for the treatment of T-Cell lymphomas, including, e.g., peripheral T-cell lymphomas, angioimmunoblastic T-cell lymphomas, cutaneous T-cell lymphomas, and follicular lymphomas.

Description

ICOS ANTIBODIES FOR TREATMENT OF LYMPHOMAS

REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority benefit of U.S. Provisional Application No. 63/109,767, filed on November 4, 2020, which is herein incorporated by reference in its entirety.

STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT

[0002] This invention was created in the performance of a Cooperative Research and Development Agreement with the National Institutes of Health, an Agency of the Department of Health and Human Services. This invention was made with government support under grant CAI 86644 awarded by the National Cancer Institute. The Government of the United States has certain rights in this invention.

NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT

[0003] For purposes of 35 U.S.C. 103(c)(2), a joint research agreement was executed between Medlmmune, LLC and National Cancer Institute in an invention regarding an anti-ICOS monoclonal antibody and dosing methods thereof.

REFERENCE TO SEQUENCE LISTING SUBMITTED ELECTRONICALLY

[0004] The content of the electronically submitted sequence listing in ASCII text file

(Name: 2943_174PC01_Seqlisting_ST25.txt; Size: 18,844 bytes; and Date of Creation: November 4, 2021) filed with the application is incorporated herein by reference in its entirety.

BACKGROUND

[0005] Inducible T-cell costimulator (ICOS) is a type I transmembrane protein comprising an extracellular (Ig) V-like domain. ICOS signaling on T cells is mediated through interaction with a cell surface ligand, ICOSL (also called B7 related protein 1 or B7RP-1). ICOS expression is low on naive human T-cells but becomes upregulated within hours after T-cell receptor (TCR) engagement. ICOS expression persists on activated T-cells subpopulations such as the T helper (Th) cells, Thl, and Thl7, and T follicular helper (TFH) cells.

[0006] TFH cells are a CD4+ T-cell subset that participates in germinal center maintenance/proliferation. Proliferation of TFH is a postulated mechanism of pathogenesis for T-cell lymphomas (e.g., angioimmunoblastic T-cell lymphoma (AITL), peripheral T- cell lymphoma (PTCL), and others). ICOS is highly expressed in TFH and hence in AITL, PTCL follicular hyperplasia (FH) type, some cutaneous T-cell lymphomas (CTCL), and follicular lymphomas (FL). Given that ICOS expression is concentrated on activated T helper cell populations, methods of using an anti-ICOS antibody (e.g., with enhanced effector function) are needed to improve the treatment of T-cell-mediated diseases and disorders.

BRIEF SUMMARY OF THE INVENTION

[0007] Provided herein are methods of treating a T-Cell Lymphoma (TCL) in a subject thereof. In certain aspects, the method comprises administering to the subject in need thereof about 0.01 mg/kg to about 3 mg/kg of an anti-inducible T-cell costimulator (ICOS) antibody or antigen-binding fragment thereof.

[0008] Provided herein are methods of treating Relapsed/Refractor (R/R) Peripheral T- Cell Lymphoma (PTCL) in a subject in need thereof. In certain aspects, the method comprises administering to the subject about 0.01 mg/kg to about 3 mg/kg of an anti- ICOS antibody or antigen-binding fragment thereof.

[0009] Provided herein are methods of treating Angioimmunoblastic T-Cell Lymphoma (AICL) in a subject in need thereof. In certain aspects, the method comprises administering to the subject about 0.01 mg/kg to about 3 mg/kg of an anti-ICOS antibody or antigen-binding fragment thereof.

[0010] In certain aspects, the subject in need thereof had greater than 100 CD4+ T- cells/pl before administration of the anti-ICOS antibody or antigen-binding fragment thereof.

[0011] In certain aspects, the anti-ICOS antibody or antigen binding fragment thereof kills T-follicular helper (TFH) cells in the subject in need thereof. In certain aspects, the administration reduces a cellular population of CD4+ TFH cells in the subject. [0012] Provided herein are methods of killing T-follicular helper (TFH) cells in a subject in need thereof. In certain aspects, the method comprises administering to the subject about 0.01 mg/kg to about 3 mg/kg of an anti-ICOS antibody or antigen-binding fragment thereof.

[0013] Provided herein are methods of reducing a cellular population of CD4+ TFH cells in a subject in need thereof. In certain aspects, the method comprises administering to the subject about 0.01 mg/kg to about 3 mg/kg of an anti-ICOS antibody or antigen-binding fragment thereof.

[0014] In certain aspects, the subject in need thereof has a T-cell lymphoma.

[0015] In certain aspects, about 3 mg/kg of the anti-ICOS antibody or antigen-binding fragment thereof is administered. In certain aspects, 3 mg/kg, 1 mg/kg, 0.3 mg/kg, 0.1 mg/kg, or 0.01 mg/kg of the anti-ICOS antibody or antigen-binding fragment thereof is administered.

[0016] In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered once every three weeks. In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered for at least six cycles. In certain aspects, he anti-ICOS antibody or antigen-binding fragment thereof is administered for twelve cycles. In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered intravenously.

[0017] In certain aspects, the TCL is selected from the group consisting of Peripheral T- Cell Lymphoma (PTCL), Angioimmunoblastic T-Cell Lymphoma (AICL), Cutaneous T- cell Lymphoma (CTCL), or Follicular Lymphoma (FL). In certain aspects, the CTCL is mycosis fungoides.

[0018] In certain aspects, the TCL is FL, and the subject has received an autologous cell transplantation prior to the administration of the anti-ICOS antibody or antigen-binding fragment thereof. In certain aspects, the PTCL is follicular type PTCL. In certain aspects, the lymphoma is refractory to at least one therapy. In certain aspects, the lymphoma is refractory to at least two therapies.

[0019] In certain aspects, the subject in need thereof had greater than 200 CD4+ T- cells/pl before administration of the anti-ICOS antibody or antigen-binding fragment thereof. [0020] In certain aspects, the lymphoma expresses ICOS. In certain aspects, the lymphoma expresses ICOS, PD1, and CXCR5.

[0021] In certain aspects, the anti-ICOS antibody induces antibody-dependent cellular cytotoxicity (ADCC) of cells of the lymphoma.

[0022] In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof decreases CD4+ T-cells in the subject in need thereof. In certain aspects, the CD4+ T- cells are decreased by at least 50%. In certain aspects, the CD4+ T-cells are decreased within 21 days of the first administration of the anti-ICOS antibody or antigen-binding fragment thereof.

[0023] In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof reduces circulating ICOS+ T-follicular helper (TFH) cells in the subject. In certain aspects, the circulating ICOS+ TFH cells are reduced by at least 80%. In certain aspects, the circulating ICOS+ TFH cells are reduced within 21 days of the first administration of the anti-ICOS antibody or antigen-binding fragment thereof. In certain aspects, the anti- ICOS antibody or antigen-binding fragment thereof reduces circulating ICOS+ CD4+ cells in the subject in need thereof.

[0024] In certain aspects, the circulating ICOS+ CD4+ cells are reduced by at least 80%.

[0025] In certain aspects, the ICOS+ CD4+ cells are regulatory T-cells (Tregs). In certain aspects, the circulating ICOS+ CD4+ cells are reduced within 21 days of the first administration of the anti-ICOS antibody or antigen-binding fragment thereof.

[0026] In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof reduces circulating ICOS+ CD8+ cells in the subject in need thereof.

[0027] In certain aspects, the circulating ICOS+ CD8+ cells are reduced by at least 50%. In certain aspects, the circulating ICOS+ CD8+ cells are reduced within 21 days of the first administration of the anti-ICOS antibody or antigen-binding fragment thereof.

[0028] In certain aspects, the administration increases an overall response rate. In certain aspects, the administration increases progression-free survival.

[0029] In certain aspects, the subject in need thereof is human.

[0030] In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof comprises the heavy chain variable region (VH) CDR1, VH CDR2, VH CDR3, light chain variable region (VL) CDR1, VL CDR2, and VL CDR3 of sequences of ICG91. In certain aspects, the CDRs are the Kabat-defined CDRs, the Chothia-defined CDRs, or the AbM-defined CDRs. In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof comprises a light chain CDR1 sequence of SEQ ID NO: 1, a light chain CDR2 sequence of SEQ ID NO:2, and a light chain CDR3 sequence of SEQ ID NO:3; and a heavy chain CDR1 sequence of SEQ ID NO:4, a heavy chain CDR2 sequence of SEQ ID NO:5, and a heavy chain CDR3 sequence of SEQ ID NO:6.

[0031] In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof comprises a heavy chain variable region comprising the a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:7. In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof comprises a light chain variable region comprising the amino acid sequence of SEQ ID NO:8. In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof comprises an IgGl heavy chain constant region. In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof comprises a kappa light chain constant region. In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof comprises an engineered IgGl Fc region.

[0032] In certain aspects, the engineered IgGl Fc region comprises complex N- glycoside-linked sugar chains in which fucose is not bound to N-acetylglucosamine in the reducing end of the sugar chain. In certain aspects, the anti-ICOS antibody or antigenbinding fragment thereof comprising the engineered IgGl Fc region mediates enhanced ADCC activity as compared to the level of ADCC activity mediated by a parent antibody comprising the same heavy chain variable region and light chain variable region sequences and a wild type Fc region.

[0033] In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO:9. In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof comprises a light chain comprising the amino acid sequence of SEQ ID NO: 10.

[0034] In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof is an antibody. In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof is an antigen-binding fragment comprises a Fab, Fab’, F(ab’)2, single chain Fv (scFv), disulfide linked Fv, V-NAR domain, IgNar, intrabody, IgGACH2, minibody, F(ab’)3, tetrabody, triabody, diabody, single-domain antibody, DVD-Ig, Fcab, mAb², (SCFV)2, or scFv-Fc. In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof is a monoclonal antibody or antigen-binding fragment thereof. In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof is a recombinant antibody or antigen-binding fragment thereof. In certain aspects, the anti- ICOS antibody or antigen-binding fragment thereof is a human antibody or antigenbinding fragment thereof. In certain aspects, e anti-ICOS antibody or antigen-binding fragment thereof is an antagonist antibody or antigen-binding fragment thereof.

[0035] In certain aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered in a pharmaceutical composition comprising about 80 mM sodium chloride, about 10 mM histidine, about 4% trehalose, and about 0.02% polysorbate, wherein the composition has a pH of about 6.

[0036] In certain aspects, the pharmaceutical composition comprises about 10 mg/ml of the ICOS antibody or antigen-binding fragment thereof. In certain aspects, a pharmaceutical composition comprises the anti-ICOS antibody or antigen-binding fragment thereof.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

[0037] FIG. 1 diagrams a clinical trial using ICG91-aFuc in lymphomas.

[0038] FIG. 2 shows the concentration of ICG91-aFuc in patients who received 0.1, 0.1 or 0.3 mg/kg doses of ICG91-aFuc. LLOQ = lower limit of quantitation. (Data < LLOQ are presented as Yi LLOQ for illustration purposes only.)

[0039] FIG. 3 shows a dose-dependent reduction in circulating ICOS+ CD4 T cells (left panel) and ICOS+ TFH cells (right panel).

[0040] FIG. 4 shows a waterfall plot of tumor size by dose level. DL1 : 0.01 mg/kg;

DL2: 0.1 mg/kg; DL3: 0.3 mg/kg; DL4: 1 mg/kg; DL5: 3 mg/kg.

[0041] FIG. 5 shows a waterfall plot of tumor size by lymphoma type.

[0042] FIG. 6 shows a spider plot of tumor size by dose level. DLL 0.01 mg/kg; DL2:

0.1 mg/kg; DL3: 0.3 mg/kg; DL4: 1 mg/kg; DL5: 3 mg/kg.

[0043] FIG. 7 shows a spider plot of tumor size by lymphoma type.

[0044] FIG. 8 shows the effect of ICG91-aFuc on lymphocyte counts. Lymphocyte counts (# of cells/L) were collected for each available time point (not available for 003). These counts were used to convert % -> cells/L for the flow cytometry data.

[0045] FIG. 9 shows the effect of ICG91-aFuc on circulating CD3+ T-cells.

[0046] FIG. 10 shows the effect of ICG91-aFuc on circulating CD8+ T-cells. [0047] FIG. 11 shows the effect of ICG91-aFuc on circulating CD4+ T-cells.

[0048] FIG. 12 shows the effect of ICG91-aFuc from DL1 to DL4, and between first cycle (Cl) week 2 (W) and third cycle (C3) week 1 (Wl) on lymphocytes, CD3+ T-cells, CD8+ T-cells, and CD4+ T-cells.

[0049] FIG. 13 shows the effect of ICG91-aFuc on regulatory T-cells (Tregs).

[0050] FIG. 14 shows the effect of ICG91-aFuc on ICOS+ Tregs.

[0051] FIG. 15 shows the effect of ICG91-aFuc on ICOS+ non-Treg CD4+ cells.

[0052] FIG. 16 summarizes the effect of ICG91-aFuc on ICOS+ CD4+ T-cells and

ICOS- CD4+ T-cells.

[0053] FIG. 17 shows the effect of ICG91-aFuc on Ki67+ Tregs. An increase in Ki67+ Tregs occurs in patient 004 (BR of PD), and generally decreases in patients with BR of SD or PR (although it increases in 006 at C5W1).

[0054] FIG. 18 shows the effect of ICG91-aFuc on Ki67+ non-Treg CD4+ cells.

[0055] FIG. 19 shows the effect of ICG91-aFuc on TCRy6+ cells.

[0056] FIG. 20 shows the effect of ICG91-aFuc on CD56+ (CD3-) cells.

[0057] FIG. 21 shows the effect of ICG91-aFuc on CD19+ (CD3- CD56-) cells

[0058] FIG. 22 shows the effect of ICG91-aFuc on CD3+, CD3+CD4+, and CD3+CD8+ cells.

[0059] FIG. 23 shows the effect of ICG91-aFuc on CD3+, CD3+CD4+, and CD3+CD8+ cells relative to baseline.

[0060] FIG. 24 shows the effect of ICG91-aFuc on CD3+CD4-CD278+ and CD3+CD4+CD278+ cells.

[0061] FIG. 25 shows the effect of ICG91-aFuc on CD3+CD4-CD278+ and CD3+CD4+CD278+ cells relative to baseline.

[0062] FIG. 26 shows the effect of ICG91 -aFuc on CD 14+, CD3 -CD 19+, and CD3 - CD58+CD16+ cells.

[0063] FIG. 27 shows the effect of ICG91 -aFuc on CD 14+, CD3 -CD 19+, and CD3 - CD58+CD16+ cells relative to baseline.

[0064] FIG. 28 shows the effect of ICG91-aFuc on CD3+CD4-CD278+ and CD3+CD4+CD278+ cells.

[0065] FIG. 29 shows the effect of ICG91-aFuc on CD3+CD4+ and CD3+CD4+CD45RA-CD183-CD185+CD278+ cells. DETAILED DESCRIPTION

I. Definitions

[0066] As used herein, the term “Inducible T-cell costimulator” or “ICOS” refers to mammalian ICOS polypeptides including, but not limited to, native ICOS polypeptides and isoforms of ICOS polypeptides. “ICOS” encompasses full-length, unprocessed EL polypeptides as well as forms of ICOS polypeptides that result from processing within the cell. The amino acid sequence for human ICOS is known in the art and the mature version of the protein (lacking the leader sequence) is provided herein as the sequence of SEQ ID NO: 11.

Mature Human ICOS (lacking leader sequence):

EINGSANYEMFIFHNGGVQILCKYPDIVQQFKMQLLKGGQILCDLTKTKGSGNTV SIKSLKFCHSQLSNNSVSFFLYNLDHSHANYYFCNLSIFDPPPFKVTLTGGYLHIYE SQLCCQLKFWLPIGCAAFVVVCILGCILICWLTKKKYSSSVHDPNGEYMFMRAV NTAKKSRLTDVTL (SEQ ID NO: 11)

The full length version of the protein (including leader sequence) is provided herein as the sequence of SEQ ID NO: 14.

Full length ICOS (including leader sequence):

MKSGLWYFFLFCLRIKVLTGEINGSANYEMFIFHNGGVQILCKYPDIVQQFKMQL LKGGQILCDLTKTKGSGNTVSIKSLKFCHSQLSNNSVSFFLYNLDHSHANYYFCN LSIFDPPPFKVTLTGGYLHIYESQLCCQLKFWLPIGCAAFVVVCILGCILICWLTKK KYSSSVHDPNGEYMFMRAVNTAKKSRLTDVTL (SEQ ID NO: 14)

The short isoform of ICOS is provided herein as the sequence of SEQ ID NO: 15. The short form has an in-frame truncation in the cytoplasmic domain caused by exon 4 skipping. The truncation results in a shorter cytoplasmic domain and lost PI3K binding site.

ICOS short isoform:

MKSGLWYFFLFCLRIKVLTGEINGSANYEMFIFHNGGVQILCKYPDIVQQFKMQL LKGGQILCDLTKTKGSGNTVSIKSLKFCHSQLSNNSVSFFLYNLDHSHANYYFCN LSIFDPPPFKVTLTGGYLHIYESQLCCQLKFWLPIGCAAFVVVCILGCILICWLTKK M (SEQ ID NO: 15)

[0067] An “ICOS+” cell refers to a cell that expresses ICOS.

[0068] An “ICOS polynucleotide,” “ICOS nucleotide,” or “ICOS nucleic acid” refer to a polynucleotide encoding ICOS.

[0069] The term “antibody” means an immunoglobulin molecule that recognizes and specifically binds to a target, such as a protein, polypeptide, peptide, carbohydrate, polynucleotide, lipid, or combinations of the foregoing through at least one antigen recognition site within the variable region of the immunoglobulin molecule. As used herein, the term “antibody” encompasses intact polyclonal antibodies, intact monoclonal antibodies, chimeric antibodies, humanized antibodies, human antibodies, fusion proteins comprising an antibody, and any other modified immunoglobulin molecule so long as the antibodies exhibit the desired biological activity. An antibody can be of any the five major classes of immunoglobulins: IgA, IgD, IgE, IgG, and IgM, or subclasses (isotypes) thereof (e.g. IgGl, IgG2, IgG3, IgG4, IgAl and IgA2), based on the identity of their heavy-chain constant domains referred to as alpha, delta, epsilon, gamma, and mu, respectively. The different classes of immunoglobulins have different and well known subunit structures and three-dimensional configurations. Antibodies can be naked or conjugated to other molecules such as toxins, radioisotopes, etc.

[0070] The term “antibody fragment” refers to a portion of an intact antibody. An “antigen-binding fragment,” “antigen-binding domain,” or “antigen-binding region,” refers to a portion of an intact antibody that binds to an antigen. An antigen-binding fragment can contain an antigen recognition site of an intact antibody (e.g., complementarity determining regions (CDRs) sufficient to specifically bind antigen). Examples of antigen-binding fragments of antibodies include, but are not limited to Fab, Fab’, F(ab’)2, and scFv fragments, linear antibodies, and single chain antibodies. An antigen-binding fragment of an antibody can be derived from any animal species, such as rodents e.g., mouse, rat, or hamster) and humans or can be artificially produced.

[0071] The terms “anti-ICOS antibody,” “ICOS antibody” and “antibody that binds to ICOS” refer to an antibody that is capable of specifically binding ICOS with sufficient affinity such that the antibody is useful as a diagnostic and/or therapeutic agent in targeting ICOS. As used herein, the terms “specifically binding,” “immunospecifically binding,” “immunospecifically recognizing,” and “specifically recognizing” are analogous terms in the context of antibodies or antigen-binding fragments thereof. These terms indicate that the antibody or antigen-binding fragment thereof binds to an epitope via its antigen-binding domain and that the binding entails some complementarity between the antigen binding domain and the epitope. Accordingly, an antibody that “specifically binds” to mature human ICOS (SEQ ID NO: 11) can also bind to ICOS from other species (e.g., cynomolgus monkey) and/or ICOS proteins produced from other human alleles, but the extent of binding to an un-related, non-ICOS protein is less than about 10% of the binding of the antibody to ICOS.

[0072] As used herein, the term “ICG91-Afuc” or “ICG91-aFuc” refers to a particular ICOS antibody (CRADA number 14-1-00035) comprising a heavy chain comprising the amino acid sequence of SEQ ID NO:9 and a light comprising the amino acid sequence of SEQ ID NO: 10, wherein the antibody comprises an Fc region comprising complex N- glycoside-linked sugar chains in which fucose is not bound to N-acetylglucosamine in the reducing end in the sugar chain.

[0073] Native antibodies are usually heterotetrameric glycoproteins of about 150,000 daltons, composed of two identical light (L) chains and two identical heavy (H) chains. Each light 40 chain is linked to a heavy chain by one covalent disulfide bond, while the number of disulfide linkages varies between the heavy chains of different immunoglobulin isotypes. Each heavy and light chain also has regularly spaced intrachain disulfide bridges. Each heavy chain has at one end a variable domain (VH) followed by a number of constant domains. Each light chain has a variable domain at one end (VL) and a constant domain at its other end; the constant domain of the light chain is aligned with the first constant domain of the heavy chain, and the light chain variable domain is aligned with the variable domain of the heavy chain. Light chains are classified as either lambda chains or kappa chains based on the amino acid sequence of the light chain constant region. The variable domain of a kappa light chain may also be denoted herein as VK. The term "variable region" may also be used to describe the variable domain of a heavy chain or light chain. Particular amino acid residues are believed to form an interface between the light and heavy chain variable domains. Such antibodies may be derived from any mammal, including, but not limited to, humans, monkeys, pigs, horses, rabbits, dogs, cats, mice, etc. [0074] The terms “VL” and “VL domain” are used interchangeably to refer to the light chain variable region of an antibody or antigen-binding fragment thereof.

[0075] The terms “VH” and “VH domain” are used interchangeably to refer to the heavy chain variable region of an antibody or antigen-binding fragment thereof.

[0076] The term "variable" refers to the fact that certain portions of the variable domains differ extensively in sequence among antibodies and are responsible for the binding specificity of each particular antibody for its particular antigen. However, the variability is not evenly distributed through the variable domains of antibodies. It is concentrated in segments called Complementarity Determining Regions (CDRs) both in the light chain and the heavy chain variable domains. The more highly conserved portions of the variable domains are called the framework regions (FW). The variable domains of native heavy and light chains each comprise four FW regions, largely adopting a P-sheet configuration, connected by three CDRs, which form loops connecting, and in some cases forming part of, the P-sheet structure. The CDRs in each chain are held together in close proximity by the FW regions and, with the CDRs from the other chain, contribute to the formation of the antigen-binding site of antibodies (see, Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (1991)). The constant domains are generally not involved directly in antigen binding, but may influence antigen binding affinity and may exhibit various effector functions, such as participation of the antibody in ADCC, CDC, antibodydependent phagocytosis and/or apoptosis.

[0077] The term "hypervariable region" when used herein refers to the amino acid residues of an antibody which are associated with its binding to antigen. The hypervariable regions encompass the amino acid residues of the "complementarity determining regions" or "CDRs" ( e.g., residues 24-34 (LI ), 50-56 (L2) and 89-97 (L3) of the light chain variable domain and residues 31-35 (Hl), 50-65 (H2) and 95-102 (H3) of the heavy chain variable domain; Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (1991)) and/or those residues from a "hypervariable loop" ( e.g., residues 26-32 (LI), SO- 52 (L2) and 91-96 (L3) in the light chain variable domain and 26-32 (Hl), 53-55 (H2) and 96-101 (H3) in the heavy chain variable domain; Chothia and Lesk, J. Mol. Biol., 196:901-917 (1987)). "Framework" or "FW" residues are those variable domain residues flanking the CDRs. FW residues are present in chimeric, humanized, human, domain antibodies, diabodies, vaccibodies, and linear antibodies.

[0078] The term “Kabat numbering” and like terms are recognized in the art and refer to a system of numbering amino acid residues in the heavy and light chain variable regions of an antibody or an antigen-binding fragment thereof. In some aspects, CDRs can be determined according to the Kabat numbering system (see, e.g., Kabat EA & Wu TT (1971) Ann NY Acad Sci 190: 382-391 and Kabat EA et al., (1991) Sequences of Proteins of Immunological Interest, Fifth Edition, U.S. Department of Health and Human Services, NIH Publication No. 91-3242). Using the Kabat numbering system, CDRs within an antibody heavy chain molecule are typically present at amino acid positions 31 to 35, which optionally can include one or two additional amino acids, following 35 (referred to in the Kabat numbering scheme as 35 A and 35B) (CDR1), amino acid positions 50 to 65 (CDR2), and amino acid positions 95 to 102 (CDR3). Using the Kabat numbering system, CDRs within an antibody light chain molecule are typically present at amino acid positions 24 to 34 (CDR1), amino acid positions 50 to 56 (CDR2), and amino acid positions 89 to 97 (CDR3). In some aspects of the present disclosure, the CDRs of the antibodies described herein have been determined according to the Kabat numbering scheme.

[0079] Chothia refers instead to the location of the structural loops (Chothia and Lesk, J. Mol. Biol. 196:901-917 (1987)). The end of the Chothia CDR-H1 loop when numbered using the Kabat numbering convention varies between H32 and H34 depending on the length of the loop (this is because the Kabat numbering scheme places the insertions at H35A and H35B; if neither 35A nor 35B is present, the loop ends at 32; if only 35A is present, the loop ends at 33; if both 35A and 35B are present, the loop ends at 34). The AbM hypervariable regions represent a compromise between the Kabat CDRs and Chothia structural loops, and are used by Oxford Molecular’s AbM antibody modeling software.

Loop Kabat AbM Chothia

LI L24-L34 L24-L34 L24-L34

L2 L50-L56 L50-L56 L50-L56

L3 L89-L97 L89-L97 L89-L97

Hl H31-H35B H26-H35B H26-H32..34

(Kabat Numbering)

Hl H31-H35 H26-H35 H26-H32 (Chothia Numbering)

H2 H50-H65 H50-H58 H52-H56

H3 H95-H102 H95-H102 H95-H102

[0080] As used herein, the term “constant region” and “constant domain” are interchangeable and have their common meanings in the art. The constant region is an antibody portion, e.g., a carboxyl terminal portion of a light and/or heavy chain which is not directly involved in binding of an antibody to antigen but which can exhibit various effector functions, such as interaction with the Fc receptor. The constant region of an immunoglobulin molecule generally has a more conserved amino acid sequence relative to an immunoglobulin variable domain.

[0081] As used herein, the term “heavy chain” when used in reference to an antibody can refer to any distinct type, e.g., alpha (a), delta (6), epsilon (a), gamma (y), and mu (p), based on the amino acid sequence of the constant domain, which give rise to IgA, IgD, IgE, IgG, and IgM classes of antibodies, respectively, including subclasses of IgG, e.g., IgGi, IgG₂, IgGs, and IgG4. Heavy chain amino acid sequences are well known in the art. In some aspects of the present disclosure, the heavy chain is a human heavy chain.

[0082] As used herein, the term “light chain” when used in reference to an antibody can refer to any distinct type, e.g., kappa (K) or lambda (X) based on the amino acid sequence of the constant domains. Light chain amino acid sequences are well known in the art. In some aspects of the present disclosure, the light chain is a human light chain.

[0083] As used herein "Fc region" includes the polypeptides comprising the constant region of an antibody excluding the first constant region immunoglobulin domain. Thus Fc refers to the last two constant region immunoglobulin domains of IgA, IgD, and IgG, and the last three constant region immunoglobulin domains of IgE and IgM, and the flexible hinge N-terminal to these domains. For IgA and IgM Fc may include the J chain. For IgG, Fc comprises immunoglobulin domains Cgamma2 and Cgamma3 (Cy2 and Cy3) and the hinge between Cgammal (Cyl) and Cgamma2 (Cy2). Although the boundaries of the Fc region may vary, the human IgG heavy chain Fc region is usually defined to comprise residues C226 or P230 to its carboxyl-terminus, wherein the numbering is according to the EU index as in Kabat et al. (1991, NIH Publication 91-3242, National Technical Information Service, Springfield, Va.). The "EU index as set forth in Kabat" refers to the residue numbering of the human IgGl EU antibody as described in Kabat et al. supra. Fc may refer to this region in isolation, or this region in the context of an antibody, antibody fragment, or Fc fusion protein. An Fc variant protein may be an antibody, Fc fusion, or any protein or protein domain that comprises an Fc region. Particularly preferred are proteins comprising variant Fc regions, which are nonnaturally occurring variants of an F region. The amino acid sequence of a non-naturally occurring Fc region (also referred to herein as a "variant Fc region") comprises a substitution, insertion and/or deletion of at least one amino acid residue compared to the wild type amino acid sequence. Any new amino acid residue appearing in the sequence of a variant Fc region as a result of an insertion or substitution may be referred to as a non-naturally occurring amino acid residue. Polymorphisms have been observed at a number of Fc positions, including but not limited to Kabat 270, 272, 312, 315, 356, and 358, and thus slight differences between the presented sequence and sequences in the prior art may exist.

[0084] The modifier "monoclonal" indicates the character of the antibody as being obtained from a substantially homogeneous population of antibodies, and is not to be construed as requiring engineering of the antibody by any particular method. The term "monoclonal" is used herein to refer to an antibody that is derived from a clonal population of cells, including any eukaryotic, prokaryotic, or phage clone, and not the method by which the antibody was engineered. For example, the monoclonal antibodies to be used in accordance with the methods and uses provided herein can be made by the hybridoma method first described by Kohler et al., Nature, 256:495 (1975), or may be made by any recombinant DNA method (see, e.g., U.S. Pat. No. 4,816,567), including isolation from phage antibody libraries using the techniques described in Clackson et al., Nature, 352:624-628 (1991) and Marks et al., J. Mol. Biol., 222:581-597 (1991), for example. These methods can be used to produce monoclonal mammalian, chimeric, humanized, and human, domain antibodies, diabodies, linear antibodies, etc.

[0085] A "human antibody" can be an antibody derived from a human or an antibody obtained from a transgenic organism that has been "engineered" to produce specific human antibodies in response to antigenic challenge and can be produced by any method known in the art. In certain techniques, elements of the human heavy and light chain loci are introduced into strains of the organism derived from embryonic stem cell lines that contain targeted disruptions of the endogenous heavy chain and light chain loci. The transgenic organism can synthesize human antibodies specific for human antigens, and the organism can be used to produce human antibody-secreting hybridomas. A human antibody can also be an antibody wherein the heavy and light chains are encoded by a nucleotide sequence derived from one or more sources of human DNA. A fully human antibody also can be constructed by genetic or chromosomal transfection methods, as well as phage display technology, or in vitro activated ICOS expressing T-cells, all of which are known in the art.

[0086] As used herein, "antagonist" antibody or antigen-binding fragment thereof refers to an antibody or antigen-binding fragment thereof that inhibits or decreases the biological activity of an antigen, (e.g., ICOS), to which the antibody immunospecifically binds.

[0087] "Antibody-dependent cell-mediated cytotoxicity" and "ADCC" refer to a cell- mediated reaction in which nonspecific cytotoxic cells (e.g., Natural Killer (NK) cells, neutrophils, and macrophages) recognize bound antibody on a target cell and subsequently cause lysis of the target cell. In one aspect, such cells are human cells. While not wishing to be limited to any particular mechanism of action, these cytotoxic cells that mediate ADCC generally express Fc receptors (FcRs). The primary cells for mediating ADCC, NK cells, express FcyRIII, whereas monocytes express FcyRI, FcyRII, FcyRIII and/or FcyRIV. FcR expression on hematopoietic cells is summarized in Ravetch and Kinet, Annu. Rev. Immunol., 9:457-92 (1991). To assess ADCC activity of a molecule, an in vitro ADCC assay, such as that described in U.S. Pat. No. 5,500,362 or 5,821,337 may be performed. Useful effector cells for such assays include peripheral blood mononuclear cells (PBMC) and Natural Killer (NK) cells. Alternatively, or additionally, ADCC activity of the molecules of interest may be assessed in vivo, e.g., in an animal model such as that disclosed in Clynes et al., Proc. Natl. Acad. Sci. (USA), 95:652-656 (1998).

[0088] "Complement dependent cytotoxicity" or "CDC" refers to the ability of a molecule to initiate complement activation and lyse a target in the presence of complement. The complement activation pathway is initiated by the binding of the first component of the complement system (Clq) to a molecule (e.g., an antibody) complexed with a cognate antigen. To assess complement activation, a CDC assay, e.g., as described in Gazzano- Santaro et al., J. Immunol. Methods, 202: 163 (1996), may be performed. "Antibody- dependent phagocytosis" or "opsonization" as used herein refers to the cell-mediated reaction wherein non-specific cytotoxic cells that express FcyRs recognize bound antibody on a target cell and subsequently cause phagocytosis of the target cell.

[0089] "Effector cells" are leukocytes which express one or more FcRs and perform effector functions. The cells express at least FcyRI, FCyRII, FcyRIII and/or FcyRIV and carry out ADCC effector function. Examples of human leukocytes which mediate ADCC include peripheral blood mononuclear cells (PBMC), natural killer (NK) cells, monocytes, cytotoxic T-cells and neutrophils.

[0090] The terms "Fc receptor" or "FcR" are used to describe a receptor that binds to the Fc region of an antibody. In one aspect, the FcR is a native sequence human FcR. Moreover, in certain aspects, the FcR is one which binds an IgG antibody (a gamma receptor) and includes receptors of the FcyRI, FcyRII, FcyRIII, and FcyRIV subclasses, including allelic variants and alternatively spliced forms of these receptors. FcyRII receptors include FcyRIIA (an "activating receptor") and FcyRIIB (an "inhibiting receptor"), which have similar amino acid sequences that differ primarily in the cytoplasmic domains thereof. Activating receptor FcyRIIA contains an immunoreceptor tyrosine-based activation motif (IT AM) in its cytoplasmic domain Inhibiting receptor FcyRIIB contains an immunoreceptor tyrosine-based inhibition motif (ITIM) in its cytoplasmic domain. (See, Daeron, Annu. Rev. Immunol., 15:203-234 (1997)). FcRs are reviewed in Ravetch and Kinet, Annu. Rev. Immunol., 9:457-92 (1991); Capel et al., Immunomethods, 4:25-34 (1994); and de Haas et al., J. Lab. Clin. Med., 126:330-41 (1995). Other FcRs, including those to be identified in the future, are encompassed by the term "FcR" herein. The term also includes the neonatal receptor, FcRn, which is responsible for the transfer of maternal IgGs to the fetus (Guyer et al., Immunol., 117:587 (1976) and Kim et al., J. Immunol., 24:249 (1994)).

[0091] "Affinity" of an antibody for an epitope to be used in the treatment( s) described herein is a term well understood in the art and means the extent, or strength, of binding of antibody to epitope. Affinity may be measured and/or expressed in a number of ways known in the art, including, but not limited to, equilibrium dissociation constant (KD or Kd), apparent equilibrium dissociation constant (KD¹ or Kd'), and IC50 (amount needed to effect 50% inhibition in a competition assay). It is understood that, as used herein, an affinity is an average affinity for a given population of antibodies which bind to an epitope. Values of KD' reported herein in terms of mg IgG per mL or mg/mL indicate mg Ig per mL of serum, although plasma can be used. When antibody affinity is used as a basis for administration of the treatment methods described herein, or selection for the treatment methods described herein, antibody affinity can be measured before and/or during treatment, and the values obtained can be used by a clinician in assessing whether a human patient is an appropriate candidate for treatment.

[0092] As used herein, the term "avidity" is a measure of the overall binding strength (i.e., both antibody arms) with which an antibody binds an antigen. Antibody avidity can be determined by measuring the dissociation of the antigen-antibody bond in antigen excess using any means known in the art, such as, but not limited to, by the modification of indirect fluorescent antibody as described by Gray et al., J. Viral. Meth., 44: 11-24. (1993).

[0093] An "epitope" is a term well understood in the art and means any chemical moiety that exhibits specific binding to an antibody. An "antigen" is a moiety or molecule that contains an epitope, and, as such, also specifically binds to antibody.

[0094] The term "antibody half-life" as used herein means a pharmacokinetic property of an antibody that is a measure of the mean survival time of antibody molecules following their administration. Antibody half-life can be expressed as the time required to eliminate 50 percent of a known quantity of immunoglobulin from the patient's body or a specific compartment thereof, for example, as measured in serum or plasma, i.e., circulating halflife, or in other tissues. Half-life may vary from one immunoglobulin or class of immunoglobulin to another. In general, an increase in antibody half-life results in an increase in mean residence time (MRT) in circulation for the antibody administered.

[0095] The term "isotype" refers to the classification of an antibody's heavy or light chain constant region. The constant domains of antibodies are not involved in binding to antigen, but exhibit various effector functions. Depending on the amino acid sequence of the heavy chain constant region, a given human antibody or immunoglobulin can be assigned to one of five major classes of immunoglobulins: IgA, IgD, IgE, IgG, and IgM. Several of these classes may be further divided into subclasses (isotypes), e.g., IgGl (gamma 1), IgG2 (gamma 2), IgG3 (gamma 3), and IgG4 (gamma 4), and IgAl and IgA2. The heavy chain constant regions that correspond to the different classes of immunoglobulins are called a, 6, a, y, and p respectively. The structures and three- dimensional configurations of different classes of immunoglobulins are well-known. Of the various human immunoglobulin classes, only human IgGl, IgG2, IgG3, IgG4, and IgM are known to activate complement. Human IgGl and IgG3 are known to mediate ADCC in humans. Human light chain constant regions may be classified into two major classes, kappa and lambda.

[0096] A polypeptide, antibody, polynucleotide, vector, cell, or composition which is “isolated” is a polypeptide, antibody, polynucleotide, vector, cell, or composition which is in a form not found in nature. Isolated polypeptides, antibodies, polynucleotides, vectors, cell or compositions include those which have been purified to a degree that they are no longer in a form in which they are found in nature. In some aspects of the present disclosure, an antibody, polynucleotide, vector, cell, or composition which is isolated is substantially pure. As used herein, “substantially pure” refers to material which is at least 50% pure (i.e., free from contaminants), at least 90% pure, at least 95% pure, at least 98% pure, or at least 99% pure.

[0097] The terms “polypeptide,” “peptide,” and “protein” are used interchangeably herein to refer to polymers of amino acids of any length. The polymer can be linear or branched, it can comprise modified amino acids, and it can be interrupted by non-amino acids. The terms also encompass an amino acid polymer that has been modified naturally or by intervention; for example, disulfide bond formation, glycosylation, lipidation, acetylation, phosphorylation, or any other manipulation or modification, such as conjugation with a labeling component. Also included within the definition are, for example, polypeptides containing one or more analogs of an amino acid (including, for example, unnatural amino acids, etc.), as well as other modifications known in the art. It is understood that, because the polypeptides of this disclosure are based upon antibodies, in some aspects of the present disclosure, the polypeptides can occur as single chains or associated chains.

[0098] As used herein, the term “host cell” can be any type of cell, e.g., a primary cell, a cell in culture, or a cell from a cell line. In some aspects of the present disclosure, the term “host cell” refers to a cell transfected with a nucleic acid molecule and the progeny or potential progeny of such a cell. Progeny of such a cell can be non- identical to the parent cell transfected with the nucleic acid molecule, e.g., due to mutations or environmental influences that can occur in succeeding generations or integration of the nucleic acid molecule into the host cell genome. [0099] The term “pharmaceutical formulation” refers to a preparation which is in such form as to permit the biological activity of the active ingredient to be effective, and which contains no additional components which are unacceptably toxic to a subject to which the formulation would be administered. The formulation can be sterile.

[0100] The terms “administer,” “administering,” “administration,” and the like, as used herein, refer to methods that can be used to enable delivery of a drug, e.g., an anti-ICOS antibody or antigen-binding fragment thereof to the desired site of biological action (e.g., intravenous administration). Administration techniques that can be employed with the agents and methods described herein are found in e.g., Goodman and Gilman, The Pharmacological Basis of Therapeutics, current edition, Pergamon; and Remington’s, Pharmaceutical Sciences, current edition, Mack Publishing Co., Easton, Pa.

[0101] As used herein, the terms “subject” and “patient” are used interchangeably. The subject can be an animal. In some aspects of the present disclosure, the subject is a human.

[0102] By the terms "treat," "treating" or "treatment of' ( or grammatically equivalent terms) it is meant that the severity of the subject's condition is reduced or at least partially improved or ameliorated and/or that some alleviation, mitigation, or decrease in at least one clinical symptom is achieved and/or there is an inhibition or delay in the progression of the condition.

[0103] As used herein, a "sufficient amount" or "an amount sufficient to" achieve a particular result refers to an amount of an antibody or composition that is effective to produce a desired effect, which is optionally a therapeutic effect (i.e., by administration of a therapeutically effective amount). For example, a "sufficient amount" or "an amount sufficient to" can be an amount that is effective to deplete ICOS expressing T-cells.

[0104] A "therapeutically effective" amount as used herein is an amount that provides some improvement or benefit to the subject. Stated in another way, a "therapeutically effective" amount is an amount that provides some alleviation, mitigation, and/or decrease in at least one clinical symptom. Clinical symptoms associated with the disorders that can be treated by the methods and uses provided herein are well-known to those skilled in the art. Further, those skilled in the art will appreciate that the therapeutic effects need not be complete or curative, as long as some benefit is provided to the subject. [0105] As used herein, "afucosylated" or an "afucosylated antibody" refers antibody in which the Fc region comprises a reduced level of fucose compared to a native antibody

[0106] As used herein, "lymphoma" refers to a group of blood malignancies that develop from lymphocytes. Types of lymphoma include, but are not limited to T-Cell lymphomas such as e.g., angioimmunoblastic T-cell lymphoma (AITL), peripheral T-cell lymphoma (PTCL), cutaneous T-cell lymphomas (CTCL), and follicular lymphoma (FL).

[0107] As used herein, the identity/similarity between two or more nucleic acid sequences, or two or more amino acid sequences, is expressed in terms of the identity or similarity between the sequences. Sequence identity may be measured in terms of percentage identity; the higher the percentage, the more identical the sequences are. Sequence similarity may be measured in terms of percentage identity or similarity (which takes into account conservative amino acid substitutions); the higher the percentage, the more similar the sequences are. Polypeptides or protein domains thereof that have a significant amount of sequence identity and also function the same or similarly to one another (for example, proteins that serve the same functions in different species or mutant forms of a protein that do not change the function of the protein or the magnitude thereof) may be called "homologs."

[0108] Sequence identity can be measured using sequence analysis software (for example, BLAST, BESTFIT, GAP, or PILEUP/PRETTYBOX programs). Such software matches identical or similar sequences by assigning degrees of homology to various substitutions, deletions, and/or other modifications. Conservative substitutions typically include substitutions within the following groups: glycine, alanine; valine, isoleucine, leucine; aspartic acid, glutamic acid, asparagine, glutamine; serine, threonine; lysine, arginine; and phenylalanine, tyrosine. In an exemplary approach to determining the degree of identity, a BLAST program can be used, with a probability score between e-3 and e-100 indicating a closely related sequence.

[0109] As used in the present disclosure and claims, the singular forms “a,” “an,” and “the” include plural forms unless the context clearly dictates otherwise.

[0110] It is understood that wherever aspects of the present disclosure are described herein with the language “comprising,” otherwise analogous aspects described in terms of “consisting of’ and/or “consisting essentially of’ are also provided. [OHl] Unless specifically stated or obvious from context, as used herein, the term “or” is understood to be inclusive. The term “and/or” as used in a phrase such as “A and/or B” herein is intended to include both “A and B,” “A or B,” “A,” and “B.” Likewise, the term “and/or” as used in a phrase such as “A, B, and/or C” is intended to encompass each of the following aspects: 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).

[0112] As used herein, the terms “about” and “approximately,” when used to modify a numeric value or numeric range, indicate that deviations of up to 10% above and down to 10% below the value or range remain within the intended meaning of the recited value or range. It is understood that wherever aspects are described herein with the language “about” or “approximately” a numeric value or range, otherwise analogous aspects referring to the specific numeric value or range (without “about”) are also provided.

[0113] Any compositions or methods provided herein can be combined with one or more of any of the other compositions and methods provided herein.

II. Methods of Treatment Using ICOS Antibodies and Antigen-Binding Fragments Thereof [0114] Provided herein are methods of administering an anti-ICOS antibody or antigenbinding fragment thereof described herein of a pharmaceutical composition thereof as described herein to a subject in need thereof, e.g., a subject with lymphoma.

[0115] As provided herein, administration of the anti-ICOS antibody or antigen-binding fragment thereof or a pharmaceutical composition thereof can treat a lymphoma, e.g., a T- cell lymphoma, in a subject (e.g., a human subject). The T-cell lymphoma can be a T-cell lymphoma that is derived from T follicular helper (TFH) cells. In some aspects, the T-cell lymphoma is angioimmunoblastic T-cell lymphoma (AITL) or peripheral T-cell lymphoma (PTCL), cutaneous T-cell lymphoma (CTCL), or follicular lymphoma (FL). In some aspects, the T-cell lymphoma is AITL or PTCL. The AITL or PTCL can be refractory to at least 1 line of therapy. In some aspects, the T-cell lymphoma is CTCL, e.g., mycosis fungoides. In some aspects, the T-cell lymphoma is FL. The FL can be grade 1, 2 or 3 A. The FL can be refractory to at least 2 lines of therapy. The subject with FL can be a subject that has received an autologous cell transplantation.

[0116] In some aspects, the T-cell lymphoma expresses ICOS. In some aspects, the T- cell lymphoma expresses ICOS, PD1, and CXCR5. [0117] In some aspects, administration of the anti-ICOS antibody or antigen-binding fragment thereof inhibits ICOS ligand binding.

[0118] In some aspects, administration of the anti-ICOS antibody or antigen-binding fragment thereof enhances antibody-dependent cellular cytotoxicity (ADCC) on cells of the lymphoma (e.g., T-cell lymphoma). In some aspects, the administration of the anti- ICOS antibody or antigen-binding fragment thereof enhances ADCC of AITL, PTCL, CTCL, or FH cells. In some aspects, the ADCC is enhanced as compared to the ADCC in the absence of the administration.

[0119] In some aspects, administration of the anti-ICOS antibody or antigen-binding fragment thereof decreases CD4+ T-cells. The administration of the anti-ICOS antibody or antigen-binding fragment thereof can reduce CD4+ T-cells by at least 20%, at least 30%, at least 40%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, or at least 80%. In some aspects, administration of the anti-ICOS antibody or antigen-binding fragment thereof can reduce CD4+ T-cells by 20% to 100%, 20% to 95%, 50% to 80%, 50% to 75%, 55% to 75%, or 56% to 68%. In some aspects, the CD4+ T-cells are reduced within 21 days of the first treatment.

[0120] In some aspects, administration of the anti-ICOS antibody or antigen-binding fragment thereof decreases circulating ICOS+CD4+ T-cells. The administration of the anti-ICOS antibody or antigen-binding fragment thereof can reduce ICOS+CD4+ T-cells by at least 30%, at least 40%, at least 50%, at least 70%, at least 70%, at least 80%, at least 85%, at least 90%, or at least 95%. In some aspects, administration of the anti-ICOS antibody or antigen-binding fragment thereof can reduce CD4+ T-cells by 30% to 100%, 80% to 100%, or 80% to 97%. In some aspects, the ICOS+CD4+ T-cells are reduced within 21 days of the first treatment.

[0121] In some aspects, administration of the anti-ICOS antibody or antigen-binding fragment thereof decreases circulating ICOS+CD4+ regulatory T-cells. (Tregs) In some aspects, ICOS+CD4+ Tregs are reduced within 21 days of the first treatment.

[0122] In some aspects, administration of the anti-ICOS antibody or antigen-binding fragment thereof decreases circulating ICOS+TFH cells. The administration of the anti- ICOS antibody or antigen-binding fragment thereof can reduce ICOS+TFH cells by at least 80%, at least 85%, at least 90%, at least 95%, or by 100%. In some aspects, In some aspects, the ICOS+TFH cells are reduced within 21 days of the first treatment. [0123] In some aspects, administration of the anti-ICOS antibody or antigen-binding fragment thereof decreases circulating ICOS+CD8+ T-cells. The administration of the anti-ICOS antibody or antigen-binding fragment thereof can reduce ICOS+CD8+ T-cells by at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%. In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof can reduce CD4+ T-cells by 50% to 90%, 50% to 80%, or 50% to 77%. In some aspects, the ICOS+CD8+ T-cells are reduced within 21 days of the first treatment.

[0124] In some aspects, administration of the anti-ICOS antibody or antigen-binding fragment thereof increases overall response rates (ORR), e.g. as compared to subjects who are not treated with the anti-ICOS antibody or antigen-binding fragment. In some aspects, administration of the anti-ICOS antibody or antigen-binding fragment thereof increases progression free survival (PFS), e.g. as compared to subjects who are not treated with the anti-ICOS antibody or antigen-binding fragment.

[0125] In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered intravenously.

[0126] In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered at a dose of about 0.01 mg/kg to about 3 mg/kg. In some aspects, the anti- ICOS antibody or antigen-binding fragment thereof is administered at a dose of 0.01 mg/kg, 0.1 mg/kg, 0.3 mg/kg, 1 mg/kg, or 3 mg/kg. In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered at a dose of about 3 mg/kg.

[0127] In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered once every three weeks (i.e., on a 3-week cycle). In some aspects, the anti- ICOS antibody or antigen-binding fragment thereof is administered once every three weeks for at least three cycles, e.g., three to twenty cycles. In some aspects, the anti- ICOS antibody or antigen-binding fragment thereof is administered once every three weeks for at least six cycles, e.g., six to twenty cycles. In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered once every three weeks for at least ten cycles, e.g., ten to twenty cycles. In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered once every three weeks for at least twelve cycles, e.g., twelve to twenty cycles. In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered once every three weeks for twelve cycles. [0128] In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered to a subject in need thereof that was previously treated for a T-cell lymphoma. In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered to a subject who has received at least one prior therapy for the T-cell lymphoma. In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered to a subject who has received at least two prior therapies for the T-cell lymphoma.

[0129] In some aspects, the T-cell lymphoma is a relapsed T-cell lymphoma. In some aspects, the T-cell lymphoma is a refractory T-cell lymphoma. In some aspects, the T- cell lymphoma is a relapsed or refractory T-cell lymphoma. In some aspects, the T-cell lymphoma is a relapsed and refractory T-cell lymphoma

[0130] In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered to a subject in need thereof that had greater than about 200 CD4+ T-cells/pl before the administration of the anti-ICOS antibody or antigen-binding fragment. In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered to a subject in need thereof (e.g., a subject with AITL) that had greater than about 100 CD4+ T-cells/pl before the administration of the anti-ICOS antibody or antigen-binding fragment.

[0131] In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered to a subject in need thereof that had an absolute neutrophil count (ANC) of greater than 1500 prior to the administration of the anti-ICOS antibody or antigen-binding fragment.

[0132] In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered to a subject in need thereof that had greater than 9 gr/dl of hemoglobin prior to the administration of the anti-ICOS antibody or antigen-binding fragment.

[0133] In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered to a subject in need thereof that had a platelet count (PLT) of greater than 75,000 prior to the administration of the anti-ICOS antibody or antigen-binding fragment.

[0134] In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered to a subject in need thereof that had adequate organ functions prior to the administration of the anti-ICOS antibody or antigen-binding fragment. [0135] I In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered to a subject in need thereof that had greater than about 200 CD4+ T-cells/pl, an absolute neutrophil count (ANC) of greater than 1500, and/or a platelet count (PLT) of greater than 75,000 before the administration of the anti-ICOS antibody or antigenbinding fragment.

[0136] In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof is administered to a subject in need thereof (e.g., a subject with AITL) that had greater than about 100 CD4+ T-cells/pl, an absolute neutrophil count (ANC) of greater than 1500, and/or a platelet count (PLT) of greater than 75,000 before the administration of the anti- ICOS antibody or antigen-binding fragment.

III. ICOS Antibodies and Antigen-Binding Fragments Thereof

[0137] Exemplary anti-ICOS antibodies and antigen-binding fragments thereof use in the methods and compositions provided herein are described in U.S. Patent No. 9,193,789 and U.S. Patent Application No. 2020/0216541, each of which is herein incorporated by reference in its entireties.

[0138] In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof for use in the methods and compositions provided herein comprises the six CDRs of the ICG91 antibody as provided in Tables 1 and 2.

Table 1. VL CDR Amino Acid Sequences

Table 2. VH CDR Amino Acid Sequences

[0139] In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof for use in the methods and compositions provided herein comprises a VH that is at least or about 80%, 85%, 90%, 95% or more identical to the amino acid sequence of SEQ ID NO:7, optionally wherein the VH comprises the 3 VH CDRS of the ICG91 antibody in Table 2. In some aspects, an anti-ICOS antibody or antigen-binding fragment thereof for use in the methods and compositions provided herein comprises a VL that is at least or about 80%, 85%, 90%, 95% or more identical to an amino acid sequence of SEQ ID NO: 8, optionally wherein the VL comprises the 3 VL CDRS of the ICG91 antibody in Table 1.

[0140] In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof for use in the methods and compositions provided herein comprises the variable heavy chain (VH) of the antibody listed in Table 3.

Table 3. VH Amino Acid Sequences

[0141] In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof for use in the methods and compositions provided herein comprises the variable light chain (VL) of the antibody listed in Table 4.

Table 4. VL Amino Acid Sequences

[0142] In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof for use in the methods and compositions provided herein comprises a variable heavy chain (VH) comprising the amino acid sequence in Table 3 and a variable light chain (VL) comprising the amino acid sequence in Table 4.

[0143] In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof for use in the methods and compositions provided herein comprises a heavy chain comprising the amino acid sequence in Table 5 and/or a light chain comprising the amino acid sequence in Table 6.

Table 5. Heavy Chain Amino Acid Sequence

Table 6. Light Chain Amino Acid Sequence

[0144] In some aspects of the present disclosure, an antibody or antigen-binding fragment thereof for use in the methods described herein is described by its VL domain alone, or its VH domain alone, or by its 3 VL CDRs alone, or its 3 VH CDRs alone. See, for example, Rader C et al., (1998) PNAS 95: 8910-8915, which is incorporated herein by reference in its entirety, describing the humanization of the mouse anti-avP3 antibody by identifying a complementing light chain or heavy chain, respectively, from a human light chain or heavy chain library, resulting in humanized antibody variants having affinities as high or higher than the affinity of the original antibody. See also Clackson T et al., (1991) Nature 352: 624-628, which is incorporated herein by reference in its entirety, describing methods of producing antibodies that specifically bind a specific antigen by using a specific VL domain (or VH domain) and screening a library for the complementary VH domain or (VL domain). The screen produced 14 new partners for a specific VH domain and 13 new partners for a specific VL domain, which were strong binders, as determined by ELISA. See also Kim SJ & Hong HJ, (2007) J Microbiol 45: 572-577, which is incorporated herein by reference in its entirety, describing methods of producing antibodies that specifically bind a specific antigen by using a specific VH domain and screening a library (e.g., human VL library) for complementary VL domains; the selected VL domains in turn could be used to guide selection of additional complementary (e.g., human) VH domains.

[0145] In some aspects, the CDRs of an antibody or antigen-binding fragment thereof can be determined according to the Chothia numbering scheme, which refers to the location of immunoglobulin structural loops (see, e.g., Chothia C & Lesk AM, (1987), J Mol Biol 196: 901-917; Al-Lazikani B etal., (1997) J Mol Biol 273: 927-948; Chothia C etal., (1992) J Mol Biol 227: 799-817; Tramontane A et a/., (1990) J Mol Biol 215(1): 175-82; and U.S. Patent No. 7,709,226). Typically, when using the Kabat numbering convention, the Chothia CDR-H1 loop is present at heavy chain amino acids 26 to 32, 33, or 34, the Chothia CDR-H2 loop is present at heavy chain amino acids 52 to 56, and the Chothia CDR-H3 loop is present at heavy chain amino acids 95 to 102, while the Chothia CDR- L1 loop is present at light chain amino acids 24 to 34, the Chothia CDR-L2 loop is present at light chain amino acids 50 to 56, and the Chothia CDR-L3 loop is present at light chain amino acids 89 to 97. The end of the Chothia CDR-H1 loop when numbered using the Kabat numbering convention varies between H32 and H34 depending on the length of the loop (this is because the Kabat numbering scheme places the insertions at H35A and H35B; if neither 35A nor 35B is present, the loop ends at 32; if only 35A is present, the loop ends at 33; if both 35A and 35B are present, the loop ends at 34).

[0146] In some aspects, provided herein are methods of administering antibodies and antigen-binding fragments thereof that specifically bind to ICOS (e.g., human ICOS) and comprise the Chothia VH and VL CDRs of the antibody listed in Tables 3 and 4. In some aspects of the present disclosure, provided herein are methods of administering antibodies or antigen-binding fragments thereof that specifically bind to ICOS (e.g, human ICOS) and comprise one or more CDRs, in which the Chothia and Kabat CDRs have the same amino acid sequence. In some aspects of the present disclosure, provided herein are methods of administering antibodies and antigen-binding fragments thereof that specifically bind to ICOS (e.g., human ICOS) and comprise combinations of Kabat CDRs and Chothia CDRs.

[0147] In some aspects of the present disclosure, the CDRs of an antibody or antigenbinding fragment thereof can be determined according to the IMGT numbering system as described in Lefranc M-P, (1999) The Immunologist 7: 132-136 and Lefranc M-P et al., (1999) Nucleic Acids Res 27: 209-212. According to the IMGT numbering scheme, VH- CDR1 is at positions 26 to 35, VH-CDR2 is at positions 51 to 57, VH-CDR3 is at positions 93 to 102, VL-CDR1 is at positions 27 to 32, VL-CDR2 is at positions 50 to 52, and VL-CDR3 is at positions 89 to 97. In some aspects of the present disclosure, provided herein are methods of administering antibodies and antigen-binding fragments thereof that specifically bind to ICOS (e.g., human ICOS) and comprise the IMGT VH and VL CDRs of the antibody listed in Tables 3 and 4, for example, as described in Lefranc M-P (1999) supra and Lefranc M-P et al., (1999) supra).

[0148] In some aspects, the CDRs of an antibody or antigen-binding fragment thereof can be determined according to MacCallum RM et al., (1996) J Mol Biol 262: 732-745. See also, e.g., Martin A. “Protein Sequence and Structure Analysis of Antibody Variable Domains,” in Antibody Engineering, Kontermann and Diibel, eds., Chapter 31, pp. 422- 439, Springer-Verlag, Berlin (2001). In some aspects of the present disclosure, provided herein are methods of administering antibodies or antigen-binding fragments thereof that specifically bind to ICOS (e.g, human ICOS) and comprise VH and VL CDRs of the antibody listed in Tables 3 and 4 as determined by the method in MacCallum RM et al.

[0149] In some aspects, the CDRs of an antibody or antigen-binding fragment thereof can be determined according to the AbM numbering scheme, which refers AbM hypervariable regions which represent a compromise between the Kabat CDRs and Chothia structural loops, and are used by Oxford Molecular’s AbM antibody modeling software (Oxford Molecular Group, Inc.). In some aspects of the present disclosure, provided herein are methods of administering antibodies or antigen-binding fragments thereof that specifically bind to ICOS (e.g, human ICOS) and comprise VH and VL CDRs of the antibody listed in Tables 3 and 4 as determined by the AbM numbering scheme.

[0150] Antibodies of the human IgG class, which have functional characteristics such a long half-life in serum and the ability to mediate various effector functions are used in certain aspects provided herein(Monoclonal Antibodies: Principles and Applications, Wiley -Liss, Inc., Chapter 1 (1995)). The human IgG class antibody is further classified into the following 4 subclasses: IgGl, IgG2, IgG3 and IgG4. A large number of studies have so far been conducted for ADCC and CDC as effector functions of the IgG class antibody, and it has been reported that among antibodies of the human IgG class, the IgGl subclass has the highest ADCC activity and CDC activity in humans (Chemical Immunology, 65, 88 (1997)).

[0151] Expression of ADCC activity and CDC activity of the human IgGl subclass antibodies generally involves binding of the Fc region of the antibody to a receptor for an antibody (hereinafter referred to as "FcyR") existing on the surface of effector cells such as killer cells, natural killer cells or activated macrophages. Various complement components can be bound. Regarding the binding, it has been suggested that several amino acid residues in the hinge region and the second domain of C region (hereinafter referred to as "Cy2 domain") of the antibody are important (Eur. J. Immunol., 23, 1098 (1993), Immunology, 86,319 (1995), Chemical Immunology, 65, 88 (1997)) and that a sugar chain in the Cy2 domain (Chemical Immunology, 65, 88 (1997)) is also important.

[0152] Anti-ICOS antibodies or antigen-binding fragments thereof can be modified with respect to effector function, e.g., so as to enhance ADCC of the antibody. This can be achieved by introducing one or more amino acid substitutions in the Fc region of an antibody. Cysteine residue(s) can also be introduced in the Fc region, allowing for interchain disulfide bond formation in this region. In this way a homodimeric antibody or antigen-binding fragment thereof can be generated that can have improved internalization capability and or increased complement-mediated cell killing and/or ADCC (Caron et al., J. Exp. Med., 176: 1191-1195 (1992) and Shapes, J. Immunol., 148: 2918-2922 (1992) ). Heterobifunctional cross-linkers can also be used to generate homodimeric antibodies or antigen-binding fragments thereof with enhanced anti-tumor activity (Wolff et al., Cancer Research, 53:2560-2565 (1993)). Antibodies or antigen-binding fragments thereof can also be engineered to have two or more Fc regions resulting in enhanced complement lysis and ADCC capabilities (Stevenson et al., Anti-Cancer Drug Design, (3)219-230 (1989)).

[0153] In some aspects of the present disclosure, provided herein are methods of administering antibodies or antigen-binding fragments thereof that comprise a heavy chain and a light chain. With respect to the heavy chain, in some aspects of the present disclosure, the heavy chain is a gamma heavy chain.

[0154] The constant region of a human IgGl heavy chain can comprise the following amino acid sequence:

ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPA VLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKRVEPKSCDKTHTCPP CPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVE VHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTIS KAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNY KTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSP GK

(SEQ ID NO: 12).

[0155] In some aspects of the present disclosure, an antibody or antigen-binding fragment thereof which immunospecifically binds to ICOS (e.g., human ICOS ) for use in the methods described herein comprises a heavy chain wherein the amino acid sequence of the VH domain comprises the CDR amino acid sequences set forth in Table 1 and wherein the constant region of the heavy chain comprises the amino acid sequence of a human gamma (y) heavy chain constant region, e.g., a human IgGl constant region.

[0156] In some aspects of the present disclosure, an antibody or antigen-binding fragment thereof which immunospecifically binds to ICOS (e.g., human ICOS) for use in the methods described herein comprises a heavy chain wherein the amino acid sequence of the VH domain comprises the amino acid sequence set forth in Table 3 and wherein the constant region of the heavy chain comprises the amino acid sequence of a human gamma (y) heavy chain constant region, e.g., human IgGl constant region.

[0157] With respect to the light chain, in some aspects of the present disclosure, the light chain of an antibody described herein is a kappa light chain. The constant region of a human kappa light chain can comprise the following amino acid sequence:

TVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESV

TEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC

(SEQ ID NO: 13). [0158] In some aspects of the present disclosure, an antibody or antigen-binding fragment thereof which immunospecifically binds to ICOS (e.g., human ICOS) for use in the methods described herein comprises a light chain wherein the amino acid sequence of the VL domain comprises the CDR amino acid sequences set forth in Table 2, and wherein the constant region of the light chain comprises the amino acid sequence of a human kappa light chain constant region.

[0159] In some aspects of the present disclosure, an antibody or antigen-binding fragment thereof which immunospecifically binds to ICOS (e.g., human ICOS) for use in the methods described herein comprises a light chain wherein the amino acid sequence of the VL domain comprises the sequence set forth in Table 4, and wherein the constant region of the light chain comprises the amino acid sequence of a human kappa light chain constant region.

[0160] In some aspects of the present disclosure, an antibody or antigen-binding fragment thereof which immunospecifically binds to ICOS (e.g., human EL) for use in the methods described herein comprises a VH domain and a VL domain comprising an amino acid sequence of any VH and VL domain described herein, and wherein the constant regions comprise the amino acid sequences of the constant regions of an IgG (e.g., a human IgGl) immunoglobulin molecule. In some aspects of the present disclosure, an antibody which immunospecifically binds to ICOS (e.g, human ICOS) for use in the methods described herein comprises a VH domain and a VL domain comprising an amino acid sequence of any VH and VL domain described herein, and wherein the constant regions comprise the amino acid sequences of the constant regions of an IgGl kappa (e.g. human IgGl kappa) immunoglobulin molecule.

[0161] In some aspects, an antigen-binding fragment as described herein, which immunospecifically binds to ICOS (e.g, human ICOS), is selected from the group consisting of a Fab, Fab’, F(ab’)2, and scFv, wherein the Fab, Fab’, F(ab’)2, or scFv comprises a heavy chain variable region sequence and a light chain variable region sequence of an anti-ICOS antibody or antigen-binding fragment thereof as described herein. A Fab, Fab’, F(ab’)2, or scFv can be produced by any technique known to those of skill in the art. In some aspects of the present disclosure, the Fab, Fab’, F(ab’)2, or scFv further comprises a moiety that extends the half-life of the antigen-binding fragment in vivo. The moiety is also termed a “half-life extending moiety.” Any moiety known to those of skill in the art for extending the half-life of a Fab, Fab’, F(ab’)2, or scFv in vivo can be used. For example, the half-life extending moiety can include a Fc region, a polymer, an albumin, or an albumin binding protein or compound. The polymer can include a natural or synthetic, optionally substituted straight or branched chain polyalkylene, polyalkenylene, polyoxylalkylene, polysaccharide, polyethylene glycol, polypropylene glycol, polyvinyl alcohol, methoxypolyethylene glycol, lactose, amylose, dextran, glycogen, or derivative thereof. Substituents can include one or more hydroxy, methyl, or methoxy groups. In some aspects of the present disclosure, the Fab, Fab’, F(ab’)2, or scFv can be modified by the addition of one or more C-terminal amino acids for attachment of the half-life extending moiety. In some aspects of the present disclosure the half-life extending moiety is polyethylene glycol or human serum albumin. In some aspects of the present disclosure, the Fab, Fab’, F(ab’)2, or scFv is fused to an Fc region.

[0162] In some aspects, the anti-ICOS antibodies or antigen-binding fragments thereof are afucosylated. In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof comprises an engineered Fc region wherein said engineered Fc region comprises a reduced level of fucose compared to a native antibody or fragment thereof. In some aspects, the anti-ICOS antibody or antigen-binding fragment thereof comprises an engineered Fc region comprising a reduced level of fucose, wherein said reduction in fucose level results in an increased affinity for an Fc ligand selected from the group consisting of: FcyRIA, FcyRIIA, FcyRIIB, FcyRIIIA, FcyRIIIB, FcyRIV, and Clq. In some aspects, an anti-ICOS antibody or antigen-binding fragment thereof comprises an engineered Fc region comprising a reduced level of fucose, wherein said reduction in fucose level results in an increased affinity for the FcyRIIIA protein. In a further aspect, an anti-ICOS antibody or antigen-binding fragment thereof comprises an engineered Fc region comprising a reduced level of fucose, wherein said reduction in fucose level results in an increased affinity for the Clq protein.

[0163] Other methods of engineering Fc regions of antibodies or antigen-binding fragments thereof so as to alter effector functions are known in the art (e.g., U.S. Patent Publication No. 2004/0185045 and PCT Publication No. WO 2004/016750, both to Koenig et al., which describe altering the Fc region to enhance the binding affinity for FcyRIIB as compared with the binding affinity for FCyRIIA; see also PCT Publication Nos. WO 99/58572 to Amlouret al., WO 99/51642 to Idusogie et al., and U.S. Pat. No. 6,395,272 to Deo et al.; the disclosures of which are incorporated herein in their entireties). Methods of modifying the Fc region to decrease binding affinity to FcyRIIB are also known in the art (e.g., U.S. Patent Publication No. 20010036459 and PCT Publication No. WO 01/79299, both to Ravetch et al., the disclosures of which are incorporated herein in their entireties). Modified antibodies or antigen-binding fragments thereof having variant Fc regions with enhanced binding affinity for FcyRIIIA and/or FcyRIIA as compared with a wildtype Fc region have also been described (e.g., PCT Publication No. WO 2004/063351, to Stavenhagen et al.; the disclosure of which is incorporated herein in its entirety).

[0164] At least four different types of FcyR have been found, which are respectively called Fey RI (CD64), FcyRII (CD32), FcyRIII (CD 16), and Fey RIV. In human, FcyRII and FcyRIII are further classified into FcyRIIa and FcyRIIb, and FcyRIIIa and FcyRIIIb, respectively. FcyR is a membrane protein belonging to the immunoglobulin superfamily, FcyRII, FcyRIII, and FcyRIV have an a chain having an extracellular region containing two immunoglobulin-like domains, FcyRI has an a chain having an extracellular region containing three immunoglobulin-like domains, as a constituting component, and the a chain is involved in the IgG binding activity. In addition, FcyRI and FcyRIII have a y chain or C, chain as a constituting component which has a signal transduction function in association with the a chain (Annu. Rev. Immunol., 18, 709 (2000), Annu. Rev. Immunol., 19, 275 (2001)). FcyRIV has been described by Bruhns et al., Clin. Invest. Med., (Canada) 27:3 D (2004).

[0165] To assess ADCC activity of an anti-ICOS antibody or antigen-binding fragments thereof of interest, an in vitro ADCC assay can be used, such as that described in U.S. Pat. No. 5,500,362 or 5,821,337. The assay may also be performed using a commercially available kit, e.g. CytoTox 96® (Promega). Useful effector cells for such assays include, but are not limited to peripheral blood mononuclear cells (PBMC), Natural Killer (NK) cells, and NK cell lines. NK cell lines expressing a transgenic Fc receptor (e.g. CD 16) and associated signaling polypeptide (e.g. FCERI-y) may also serve as effector cells (see, e.g. WO 2006/023148 A2 to Campbell). For example, the ability of any particular antibody or antigen-binding fragment thereof to mediate lysis of the target cell by complement activation and/or ADCC can be assayed. The cells of interest are grown and labeled in vitro; the antibody or antigen-binding fragment thereof is added to the cell culture in combination with immune cells which may be activated by the antigen antibody complexes; i.e., effector cells involved in the ADCC response. The antibody or antigenbinding fragment thereof can also be tested for complement activation. In either case, cytolysis of the target cells is detected by the release of label from the lysed cells. The extent of target cell lysis may also be determined by detecting the release of cytoplasmic proteins ( e.g. LDH) into the supernatant.

[0166] ADCC activity of a molecule of interest can also be assessed in vivo, e.g., in an animal model such as that disclosed in Clynes et al., Proc. Natl. Acad. Set. (USA) 95:652- 656 (1998). Moreover, techniques for modulating (i.e., increasing or decreasing) the level of ADCC, and optionally CDC activity, of an antibody or antigen-binding fragment thereof are well-known in the art. See, e.g., U.S. Pat. No. 6,194,551. Antibodies can be capable or can be modified to have the ability of inducing ADCC and/or CDC. Assays to determine ADCC function can be practiced using human effector cells to assess human ADCC function. Such assays can also include those intended to screen for antibodies that induce, mediate, enhance, block cell death by necrotic and/or apoptotic mechanisms. Such methods including assays utilizing viable dyes, methods of detecting and analyzing caspases, and assays measuring DNA breaks can be used to assess the apoptotic activity of cells cultured in vitro with an anti-ICOS antibody or antigen-binding fragment thereof of interest.

[0167] For example, Annexin V or TdT-mediated dUTP nick-end labeling (TUNEL) assays can be carried out as described in Decker et al., Blood (USA) 103:2718-2725 (2004) to detect apoptotic activity. The TUNEL assay involves culturing the cell of interest with fluorescein-labeled dUTP for incorporation into DNA strand breaks. The cells are then processed for analysis by flow cytometry. The Annexin V assay detects the appearance of phosphatidylserine (PS) on the outside of the plasma membrane of apoptotic cells using a fluorescein-conjugated Annexin V that specifically recognizes the exposed PS molecules. Concurrently, a viable dye such as propidium iodide can be used to exclude late apoptotic cells. The cells are stained with the labeled Annexin V and are analyzed flow cytometry.

[0168] In some aspects of the present disclosure, the anti-ICOS antibody or antigenbinding fragment thereof comprises an Fc region (e.g., an engineered IgGl Fc region) comprising complex N-glycoside-linked sugar chains in which fucose is not bound to N- acetylglucosamine in the reducing end in the sugar chain. In some aspects of the present disclosure, the anti-ICOS antibody or antigen-binding fragment thereof comprises an engineered Fc region (e.g., an engineered IgGl Fc region) comprising complex N- glycoside-linked sugar chains linked to Asn297 (also referred to as Asn305) in which fucose is not bound to N-acetylglucosamine in the reducing end. As demonstrated in US Patent Application Publication No. 2020/0216541, which is herein incorporated by reference in its entirety, fucose free anti-ICOS antibodies can mediate more effective depletion of ICOS bearing T-cells.

[0169] In some aspects of the present disclosure, the anti-ICOS antibody or antigenbinding fragment thereof has an N-linked biantennary complex-type or high mannosetype oligosaccharides attached to each heavy chain at Asn-305. In some aspects, the average size of the oligosaccharide moiety is approximately 1,560 Daltons.

[0170] In some aspects of the present disclosure, the anti-ICOS antibody or antigenbinding fragment thereof does not have CDC activity.

[0171] In some aspects of the present disclosure, the anti-ICOS antibody or antigenbinding fragment thereof does agonist activity.

[0172] In some aspects of the present disclosure, the anti-ICOS antibody or antigenbinding fragment thereof binds to human ICOS with an affinity of about 285 pM (e.g., as measured using Biacore).

[0173] In some aspects of the present disclosure, the anti-ICOS antibody or antigenbinding fragment thereof is capable inhibiting ICOS-ligand binding activity.

[0174] In some aspects of the present disclosure, the anti-ICOS antibody or antigenbinding fragment thereof is an antagonist antibody or antigen-binding fragment thereof.

[0175] In some aspects, the anti-ICOS antibody binds ICOS on a T-cell. In some aspects, the anti-ICOS antibody binds ICOS on a T follicular helper cell. In some aspects, the anti- ICOS antibody induces antibody complement dependent cytotoxicity (ADCC) of a target cell. In some aspects, the anti-ICOS antibody induces ADCC of a T-cell lymphoma, Angioimmunoblastic T-cell lymphoma, relapsed/refractor peripheral T-cell lymphoma, or T-follicular helper cell. IV. Manufacture/Production of Anti-ICOS Antibodies

[0176] Antibodies and antigen-binding fragments thereof that immunospecifically bind to ICOS (e.g., human ICOS) can be produced by any method known in the art for the synthesis of antibodies and antigen-binding fragments thereof, for example, by chemical synthesis or by recombinant expression techniques. An anti-ICOS antibody or antigenbinding fragment thereof can also be produced on a commercial scale using methods that are well-known in the art for large scale manufacturing of antibodies or antigen-binding fragments thereof. For example, this can be accomplished using recombinant expressing systems such as, but not limited to, those described below.

[0177] Recombinant expression of an antibody or antigen-binding fragment thereof, can comprise construction of one or more expression vectors comprising one or more polynucleotides that encode the antibody or antigen-binding fragment thereof. Once one or more polynucleotides encoding an antibody or antigen-binding fragment thereof, or a heavy or light chain of an antibody or antigen-binding fragment thereof, or portion thereof, has been obtained, the vector for the production of the antibody or antigenbinding fragment thereof can be produced by recombinant DNA technology using techniques well-known in the art. See, e.g., U.S. Pat. No. 6,331,415, which is herein incorporated by reference in its entirety. Thus, methods for preparing a protein by expressing a polynucleotide containing an antibody or antigen-binding fragmentencoding nucleotide sequence are described herein. Methods which are well known to those skilled in the art can be used to construct expression vectors containing antibody or antigen-binding fragment coding sequences and appropriate transcriptional and translational control signals. These methods include, for example, in vitro recombinant DNA techniques, synthetic techniques, and in vivo genetic recombination. Thus, replicable vectors comprising a nucleotide sequence encoding an antibody or antigenbinding fragment thereof, a heavy or light chain of an antibody or antigen-binding fragment thereof, a heavy or light chain variable domain of an antibody, antigen-binding fragment thereof or a portion thereof, or a heavy or light chain CDR, operably linked to a promoter can be used. Such vectors may include the nucleotide sequence encoding the constant region of the antibody or antigen-binding fragment thereof (see, e.g., International Publication Nos. WO 86/05807 and WO 89/01036; and U.S. Pat. No. 5,122,464) and the variable domain of the antibody or antigen-binding fragment thereof can be cloned into such a vector for expression of the entire heavy, the entire light chain, or both the entire heavy and light chains.

[0178] In another aspect, anti-ICOS antibodies or antigen-binding fragments thereof can be made using targeted homologous recombination to produce all or portions of the anti- ICOS antibodies or antigen-binding fragments thereof (see, U.S. Pat. Nos. 6,063,630, 6,187,305, and 6,692,737). In certain aspects, anti-ICOS antibodies or antigen-binding fragments thereof can be made using random recombination techniques to produce all or portions of the anti-ICOS antibodies or fragments (see, U.S. Pat. Nos. 6,361,972, 6,524, 818, 6,541,221, and 6,623,958). Anti-ICOS antibodies can also be produced in cells expressing an antibody or antigen-binding fragment thereof from a genomic sequence of the cell comprising a modified immunoglobulin locus using Cre-mediated site-specific homologous recombination (see, U.S. Pat. No. 6,091,001). The host cell line may be derived from human or nonhuman species including but not limited to mouse, and Chinese hamster. Human or humanized antibodies or antigen-binding fragments thereof can be in a human cell line. These methods can advantageously be used to engineer stable cell lines which permanently express the antibody or antigen-binding fragment thereof.

[0179] Once the expression vector is transferred to a host cell by conventional techniques, the transfected cells are then cultured by conventional techniques to produce an antibody or antigen-binding fragment thereof. Thus, host cells containing a polynucleotide encoding an antibody or fragment thereof, or a heavy or light chain thereof, or portion thereof, operably linked to a heterologous promoter can be used.

[0180] A variety of host-expression vector systems may be utilized to express an anti- ICOS antibody, antigen-binding fragment thereof, or portions thereof that can be used in the engineering and generation of anti-ICOS antibodies or antigen-binding fragments thereof (see, e.g., U.S. Pat. No. 5,807,715). For example, mammalian cells such as Chinese hamster ovary cells (CHO), in conjunction with a vector such as the major intermediate early gene promoter element from human cytomegalovirus is an effective expression system for antibodies (Foecking et al., Gene, 45:101 (1986); and Cockett et al., Bio/Technology, 8:2 (1990)). In addition, a host cell strain can be chosen which modulates the expression of inserted sequences, or modifies and processes the antibody or antigen-binding fragment thereof gene product in the specific fashion desired. Such modifications (e.g., glycosylation) and processing (e.g., cleavage) of protein products can be important for the function of the protein. Different host cells have characteristic and specific mechanisms for the post-translational processing and modification of proteins and gene products. Appropriate cell lines or host systems can be chosen to ensure the correct modification and processing of the antibody or portion thereof expressed. To this end, eukaryotic host cells which possess the cellular machinery for proper processing of the primary transcript, glycosylation, and phosphorylation of the gene product may be used. Such mammalian host cells include but are not limited to CHO, VERY, BHK, Hela, COS, MDCK, 293, 3T3, W138, BT483, Hs578T, HTB2, BT2O and T47D, NSO ( a murine myeloma cell line that does not endogenously produce any functional immunoglobulin chains), CRL 7030 and HsS78Bst cells.

[0181] Stable expression can be used for long-term, high-yield production of recombinant proteins. For example, cell lines which stably express the antibody or antigen-binding fragment thereof can be generated. Host cells can be transformed with an appropriately engineered vector comprising expression control elements ( e.g., promoter, enhancer, transcription terminators, polyadenylation sites, etc.), and a selectable marker gene. Following the introduction of the foreign DNA, cells can be allowed to grow for 1-2 days in an enriched media, and then be switched to a selective media. The selectable marker in the recombinant plasmid confers resistance to the selection and allows cells that stably integrated the plasmid into their chromosomes to grow and form foci which in turn can be cloned and expanded into cell lines. Plasmids that encode an anti-ICOS antibody or antigen-binding fragment thereof can be used to introduce the gene/cDNA into any cell line suitable for production in culture.

[0182] A host cell can be co-transfected with two expression vectors, the first vector encoding a heavy chain derived polypeptide and the second vector encoding a light chain derived polypeptide. The two vectors can contain identical or different selectable markers. A single vector which encodes, and is capable of expressing, both heavy and light chain polypeptides can also be used. In such situations, the light chain can be placed 5' to the heavy chain to avoid an excess of toxic free heavy chain (Proudfoot, Nature 322:562-65 (1986); and Kohler, 1980, Proc. Natl. Acad. Set. USA, 77:2197 (1980)). The coding sequences for the heavy and light chains can comprise cDNA or genomic DNA.

[0183] Once an antibody or antigen-binding fragment thereof has been produced by recombinant expression, it can be purified by any method known in the art for purification of an immunoglobulin molecule, for example, by chromatography (e.g., ion exchange, affinity, particularly by affinity for the specific antigens Protein A or Protein G, and sizing column chromatography), centrifugation, differential solubility, or by any other standard technique for the purification of proteins. Further, the antibodies or fragments thereof can be fused to heterologous polypeptide sequences described herein or otherwise known in the art to facilitate purification.

[0184] A composition comprising a plurality of ICOS antibodies or antigen-binding fragments thereof with complex N-glycoside-linked sugar chains linked to Asn297 (also referred to as Asn305) of the Fc region in which fucose is not bound to N- acetylglucosamine in the reducing end can prepared according to the methods set forth in

U.S. Pat. No. 6,946,292, which is herein incorporated by reference in its entirety. Briefly, fucosyltransferase knock-out CHO cells can transfected with a DNA plasmid expression vector preparation encoding the heavy and light chains of the antibody or antigen-binding fragment thereof. Transfected cells can be fed at day 3 and 6 and the antibody or antigenbinding fragment-containing conditioned medium can be harvested at day 9. Antibody or antigen-binding fragment can be purified from the conditioned medium using a pre-cast protein A column (GE Healthcare). Antibody or antigen-binding fragment can be eluted from the column with low pH buffer, neutralized, and dialyzed against PBS. The concentration of the purified antibody or antigen-binding fragment can be calculated from the solution's optical density at 280 nm.

[0185] In some aspects of the present disclosure, an antibody or antigen-binding fragment thereof administered according to the methods provided herein is isolated or purified. Generally, an isolated antibody or antigen-binding fragment thereof is one that is substantially free of other antibodies or antigen-binding fragments thereof with different antigenic specificities than the isolated antibody or antigen-binding fragment thereof. For example, in some aspects of the present disclosure, a preparation of an antibody or antigen-binding fragment thereof described herein is substantially free of cellular material and/or chemical precursors.

V. Pharmaceutical Compositions

[0186] Provided herein are methods of administering compositions comprising ICOS antibody or antigen-binding fragment thereof having the desired degree of purity in a physiologically acceptable carrier, excipient, or stabilizer (Remington’s Pharmaceutical Sciences (1990) Mack Publishing Co., Easton, PA). Acceptable carriers, excipients, or stabilizers are nontoxic to recipients at the dosages and concentrations employed. (See, e.g., Gennaro, Remington: The Science and Practice of Pharmacy with Facts and Comparisons: Drugfacts Plus, 20th ed. (2003); Ansel et al., Pharmaceutical Dosage Forms and Drug Delivery Systems, 7th ed., Lippencott Williams and Wilkins (2004); Kibbe et al., Handbook of Pharmaceutical Excipients, 3rd ed., Pharmaceutical Press (2000)). The compositions to be used for in vivo administration can be sterile. This is readily accomplished by filtration through, e.g., sterile filtration membranes.

[0187] Exemplary pharmaceutical compositions comprising ICOS antibodies or antigenbinding fragments thereof are provided, for example, in US Patent Application Publication No. 2020/0216541, which is herein incorporated by reference in its entirety.

[0188] In some aspects of the present disclosure, methods of administering a pharmaceutical composition are provided, wherein the pharmaceutical composition comprises (i) an ICOS antibody or antigen-binding fragment thereof comprising (a) the heavy chain variable region (VH) complementarity determining region (CDR) 1, VH CDR2, VH CDR3 and light chain variable region (VL) CDR1, CDR2, and CDR3 sequences of SEQ ID NOs: 1-6, respectively, (b) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO:7 and/or a variable light chain region comprising the amino acid sequence of SEQ ID NO:8, or (c) a heavy chain comprising the amino acid sequence of SEQ ID NOV and/or a light chain comprising the amino acid sequence of SEQ ID NOTO, and (ii) a pharmaceutically acceptable excipient.

[0189] In some aspects, the pharmaceutical composition comprises (i) an ICOS antibody or antigen-binding fragment thereof comprising (a) the heavy chain variable region (VH) complementarity determining region (CDR) 1, VH CDR2, VH CDR3 and light chain variable region (VL) CDR1, CDR2, and CDR3 sequences of SEQ ID NOs: 1-6, respectively, (b) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO:7 and/or a variable light chain region comprising the amino acid sequence of SEQ ID NO:8, or (c) a heavy chain comprising the amino acid sequence of SEQ ID NOV and/or a light chain comprising the amino acid sequence of SEQ ID NOTO, (ii) sodium chloride, (iii) histidine, (iv) trehalose, and (v) polysorbate. In some aspects, the pharmaceutical composition has a pH of about 6. In some aspects, the pharmaceutical composition comprises about 10 mg/ml of the ICOS antibody or antigen-binding fragment thereof. In some aspects, the pharmaceutical composition has a pH of about 6 and comprises about 10 mg/ml of the ICOS antibody or antigen-binding fragment thereof.

[0190] In some aspects, the pharmaceutical composition comprises (i) an ICOS antibody or antigen-binding fragment thereof comprising (a) the heavy chain variable region (VH) complementarity determining region (CDR) 1, VH CDR2, VH CDR3 and light chain variable region (VL) CDR1, CDR2, and CDR3 sequences of SEQ ID NOs: l-6, respectively, (b) a variable heavy chain region comprising the amino acid sequence of SEQ ID NO:7 and/or a variable light chain region comprising the amino acid sequence of SEQ ID NO:8, or (c) a heavy chain comprising the amino acid sequence of SEQ ID NOV and/or a light chain comprising the amino acid sequence of SEQ ID NO: 10, (ii) about 80 mM sodium chloride, (iii) about 10 mM histidine, (iv) about 4% trehalose, and (v) about 0.02% polysorbate. In some aspects, the pharmaceutical composition has a pH of about 6. In some aspects, the pharmaceutical composition comprises about 10 mg/ml of the ICOS antibody or antigen-binding fragment thereof. In some aspects, the pharmaceutical composition has a pH of about 6 and comprises about 10 mg/ml of the ICOS antibody or antigen-binding fragment thereof.

[0191] In some aspects, a pharmaceutical composition comprises an ICOS antibody or antigen-binding fragment thereof, wherein the antibody or fragment comprises an Fc region having complex N-glycoside linked sugar chains in which fucose is not bound to N-acetylglucosamine in the reducing end in the sugar chain.

[0192] In some aspects, a pharmaceutical composition comprising an ICOS antibody or antigen-binding fragment thereof is a liquid composition. In some aspects, the liquid composition is a stable liquid composition. In some aspects, the ICOS antibody or antigen-binding fragment thereof in the liquid composition loses no more than about 20% of its human ICOS binding activity during storage of the liquid composition at 5°C for 3 months; less than 5% of the antibody or antigen-binding fragment thereof forms an aggregate upon storage of the liquid composition at 40°C for 1 month (e.g., as determined by high performance size exclusion chromatography (HPSEC)); and/or less than 5% of the antibody or antigen-binding fragment is fragmented upon storage of the liquid composition at 40°C for 1 month (e.g., as determined by reversed phase high performance liquid chromatography (RP-HPLC)). [0193] In some aspects, a pharmaceutical composition comprising an ICOS antibody or antigen-binding fragment thereof is an aqueous composition. In some aspects, the liquid composition is a stable aqueous composition. In some aspects, the ICOS antibody or antigen-binding fragment thereof in the aqueous composition loses no more than about 20% of its human ICOS binding activity during storage of the aqueous composition at 5°C for 3 months; less than 5% of the antibody or antigen-binding fragment thereof forms an aggregate upon storage of the aqueous composition at 40°C for 1 month (e.g., as determined by HPSEC); and/or less than 5% of the antibody or antigen-binding fragment is fragmented upon storage of the aqueous composition at 40°C for 1 month (e.g., as determined by RP-HPLC).

[0194] Methods for measuring aggregates using HPSEC and methods for measuring fragmentation using RP-HPLC are described, for example, in US Patent Application Publication No. 2020/0216541, which is herein incorporated by reference in its entirety.

[0195] In some aspects, a pharmaceutical composition comprising an ICOS antibody or antigen-binding fragment thereof is in an injectable formulation. In some aspects, the injectable formulation is suitable for intravenous administration.

In some aspects, a pharmaceutical composition comprising an ICOS antibody or antigenbinding fragment thereof is contained within a pre-filled syringe

[0196] The following examples are offered by way of illustration and not by way of limitation.

EXAMPLES

[0197] The examples in this Section are offered by way of illustration, and not by way of limitation.

Example 1: Clinical Evaluation of Anti-ICOS Antibodies

[0198] An afucosylated antibody, ICG91-aFuc, comprising the heavy and light chain sequences of SEQ ID NOs:9 and 10, respectively, and having complex N-glycoside- linked sugar chains in which fucose is not bound to N-acetylglucosamine in the reducing end in the sugar chain) was evaluated clinically. The safety, pharmacokinetics (PK), and clinical activity of the ICG91-aFuc antibody against T-cell lymphomas were assessed in a Phase 1 clinical trial as diagrammed in Figure 1. The trial was a 3+3 study design that evaluated 5 dose levels (0.01-3 mg/kg). ICG91-aFuc was administered intravenously (IV) every 3 weeks for 12 cycles at 0.01 mg/kg, 0.1 mg/kg, 0.3 mg/kg, 1 mg/kg, or 3 mg/kg.

Subjects

[0199] Eligibility criteria included: age > 18 years, Eastern Cooperative Oncology Group (ECOG) score < 2, diagnosis of relapsed/refractory (R/R) peripheral T-Cell lymphoma (PTCL), angioimmunoblastic T-cell lymphoma (AITL), cutaneous T-cell lymphoma (CTCL), mycosis fungoides (MF), or follicular lymphoma (FL), that have received and are refractory to at least 1 line of therapy (at least 2 lines of therapy and post autologous cell transplantation for FL), adequate bone marrow function (absolute neutrophil count (ANC)>1500, hemoglobin (Hb)> 9gr/dl, and platelet count (PLT)>75,000) adequate organ functions, and CD4+ T-cells > 200 cells/uL (> 100 for AITL).

[0200] Seventeen (17) patients were enrolled and evaluable for safety and efficacy. The general characteristics of the patients are summarized in Table 7.

Table 7: General Patient Characteristics

[0201] The median age was 63 (range: 29-80). The female:male ratio was 5: 13. The histologic types included AITL (n= 12, 71%), PTCL-NOS (n=3, 18%) and CTCL (n=2, 12%). The median number of prior therapies was 7.5 (1 - 16). The lymphoma was stage III/IV in 83% of subjects, and 18% of subject had a prior autologous hematopoietic cell transplantation (HCT). Patient samples were studied using fluorescent-labeled monoclonal antibodies to generate immunofluorescent (IF) images to evaluate ICOS expression, and expression was observed including in cells expressing both ICOS and CD4. Pharmacokinetics

[0202] PK analyses demonstrated that ICG91-aFuc systemic exposure increased in a dose-dependent manner although the PK appeared to be non-linear at lower doses. Clearance decreased and half-life augmented with increases in ICG91-aFuc dose. The half-life was shorter than typical IgG antibodies at low doses. The PK exposure increased in Cycle 2 compared to Cycle 1 in the 0.1 mg/kg dose cohort. The PK results for the 0.1, 0.1 and 0.3 mg/kg dose cohorts are shown in Figure 2 and Table 8 below.

Table 8: ICG91-aFuc Pharmacokinetics

due to lack of data in the terminal phase. a A patient was excluded from NCA due to missing post-dose sample (Cmax).

[0203] The recommended phase 2 dose (RP2D) was determined to be the highest dose level of 3 mg/kg.

Safety and Immunogenicity

[0204] The most common grade 3/4 adverse events (AEs) were decreased CD4+ T-cells (64%), anemia (12%), hypophosphatemia (12%), thrombocytopenia (6%), infusion related reactions (6%). The treatment emergent adverse events (TEAE) are summarized in Table 9. Table 9: Treatment Emergent Adverse Events

[0205] No dose limiting toxicities (DLTs) were reported, and the maximum tolerated dose was not established.

[0206] Thus, ICG91-aFuc was safe, well tolerated.

Pharmacodynamics

[0207] Peripheral blood flow cytometry analysis of T-cell subsets showed that ICG91- aFuc caused a rapid and sustained decrease in CD4+ T-cells. It also resulted in reductions in circulating ICOS+ TFH, ICOS+CD4+ (including Tregs), and ICOS+CD8+ T-cells, especially on days 7-21 post treatment.

[0208] As shown in Figure 3, ICOS+ CD4+ T-cells decreased shortly after the first dose across all ICG91-aFuc dose groups. Rapid, complete, and sustained depletion of ICOS+ CD4+, and TFH T-cells occurred after the 0.3 mg/kg dose, and the 0.3 mg/kg dose resulted in a more sustained reduction of the targeted subpopulation of cells.

[0209] The effect of ICG91-aFuc on lymphocytes is shown in Figure 8 and Figure 12. The effect of ICG91-aFuc on circulating CD3+ T cells is shown in Figure 9 and Figure 12. The effect of ICG91-aFuc on circulating CD8+ T cells is shown in Figure 10 and 12. As shown in Figure 11 and Figure 12, the number of circulating CD4+ T cells decreased with increasing doses of ICG91-aFuc.

[0210] The effect of ICG91-aFuc on the number of circulating CD4+FOXP3+CD127- CD25+ T regulatory cells is shown in Figure 13 and on circulating ICOS+CD4+FOXP3+CD127-CD25+ T regulatory cells is shown in Figure 14. The effect of ICG91-aFuc on circulating ICOS+ non-regulatory CD4+FOXP3- T cells is shown in Figure 15. Figure 16 shows the effect of administration of ICG91-aFuc on ICOS+ CD4+ T cells and ICOS- CD4+ T cells. Figure 17 shows the effect of ICG91- aFuc on Ki67+CD4+FOXP3+CD127-CD25+ T regulatory cells. Figure 18 shows the effect of ICG91-aFuc on Ki67+CD4+FOXP3- non-regulatory cells. Figure 19 shows the effect of ICG91-aFuc on circulating TCRy6+ cells.

[0211] Figures 19-21 show the effect of ICG91-aFuc on circulating TCRy6+, CD56+(CD3-), and CD19+(CD3-CD56-) T cells.

[0212] Whole blood flow cytometry analysis was used to show the effect of ICG91-aFuc on circulating CD3+, CD3+CD4+, and CD3+CD8+ circulating T cells (FIGs. 22 and 23). Figures 24 and 25 show the effect of ICG91-aFuc on circulating CD3+CD4-CD278+ and CD3+CD4+CD278+ circulating T cells. Figures 26 and 27 show the effect of ICG91- aFuc on circulating CD 14+ CD3-CD19+, and CD3-CD58+CD16+.

[0213] The ICG91-aFuc reduced the number of CD3+CD4-CD278+ cells 7, 14, and 21 days after administration (FIG. 28). On day 7 post-dose, median CD4-ICOS+ T cell counts were reduced by 77.5% (range -60.0 to -94.3). Median reductions were at least 50% below baseline at days 14 and 21 although upper ranges increased to 0 and 126.3, respectively.

[0214] Administration of the ICG91-aFuc reduced the number of CD3+CD4+CD278+ T cells 7, 14, and 21 days after administration (FIG. 28). On day 7 post-dose, median CD4+ICOS+ T cell counts were reduced by 97.0% (range -38.0 to -99.7). Median reductions were at least 80% below baseline at days 14 and 21, although upper ranges increased to -16.6 and -1.9, respectively.

[0215] Administration of ICG91-aFuc decreased the number of CD3+CD4+ cells 7, 14, and 21 days after administration (FIG. 29). Median CD4+ T cells were decreased from baseline by 67.2% (-23.8% to -92.4%), 58.3% (-24.7% to -92.4%) and 56.1% (-10.4% to -97.5%) on days 7, 14 and 21, respectively. Administration of ICG91-aFuc decreased the number of CD3+CD4+CD45RA-CD183-CD185+CD278+ over all time points (FIG. 29). Median ICOS+ TFH cells, defined as CD3+CD4+CD45RA-CD183-CD185+CD278+ cells, are decreased from baseline by 100% on days 7, 14 and 21. Upper ranges were - 14.3, 28.6 and 14.3 on days 7, 14 and 21, respectively. Lower ranges were -100% at all timepoints. ICG91-aFuc

Clinical Efficacy

[0216] There were 4 (23.5%) partial remissions (PR) and 7 with stable disease (SD), all patients with AITL. Two patients (1 PR and 1 SD) remain on treatment. One patient completed treatment and remains in a stable PR for over a year without further treatment. One patient in PR underwent allogeneic hematopoietic transplantation (HCT) and remains in remission. Patients’ responses are summarized in Table 10.

Table 10: Patient Responses

DL = dose level; SD = stable disease; PR = partial response; PD = progressive disease; C

= cycle; and EOT = end of treatment. [0217] Figure 4 shows a plot of the size of target tumors as a percentage of baseline size in individual patients across the five dose levels. Figure 5 also shows the percent change in tumor size in patients receiving different doses. Figure 6 shows the size of target tumors as a percentage of baseline size in individual patients across different types of lymphomas. Figure 7 also shows the percent change in tumor size in patients with different types of lymphomas.

[0218] Overall, ICG91-aFuc showed positive clinical activity in poor-risk refractory and heavily pretreated AITL.

* * *

[0219] It is to be appreciated that the Detailed Description section, and not the Summary and Abstract sections, is intended to be used to interpret the claims. The Summary and Abstract sections may set forth one or more but not all exemplary aspects of the present disclosure as contemplated by the inventor(s), and thus, are not intended to limit the present disclosure and the appended claims in any way.

[0220] All references (e.g., publications or patents or patent applications) cited herein are incorporated herein by reference in their entirety and for all purposes to the same extent as if each individual reference (e.g., publication or patent or patent application) was specifically and individually indicated to be incorporated by reference in its entirety for all purposes.

Claims

WHAT IS CLAIMED IS: A method of treating a T-Cell Lymphoma (TCL) in a subject in need thereof, the method comprising administering to the subject in need thereof about 0.01 mg/kg to about 3 mg/kg of an anti-inducible T-cell costimulator (ICOS) antibody or antigen-binding fragment thereof. A method of treating Relapsed/Refractor (R/R) Peripheral T-Cell Lymphoma (PTCL) in a subject in need thereof, the method comprising administering to the subject about 0.01 mg/kg to about 3 mg/kg of an anti-ICOS antibody or antigen-binding fragment thereof. A method of treating Angioimmunoblastic T-Cell Lymphoma (AICL) in a subject in need thereof, the method comprising administering to the subject about 0.01 mg/kg to about 3 mg/kg of an anti-ICOS antibody or antigen-binding fragment thereof. The method of claim 3, wherein the subject in need thereof had greater than 100 CD4+ T- cells/pl before administration of the anti-ICOS antibody or antigen-binding fragment thereof. The method of any one of claims 1-4, wherein the anti-ICOS antibody or antigen binding fragment thereof kills T-follicular helper (TFH) cells in the subject in need thereof. The method of any one of claims 1-5, wherein the administration reduces a cellular population of CD4+ TFH cells in the subject. A method of killing T-follicular helper (TFH) cells in a subject in need thereof, the method comprising administering to the subject about 0.01 mg/kg to about 3 mg/kg of an anti-ICOS antibody or antigen-binding fragment thereof. A method of reducing a cellular population of CD4+ TFH cells in a subject in need thereof, the method comprising administering to the subject about 0.01 mg/kg to about 3 mg/kg of an anti-ICOS antibody or antigen-binding fragment thereof. The method of claim 7 or 8, wherein the subject in need thereof has a T-cell lymphoma. The method of any one of claims 1-9, wherein about 3 mg/kg of the anti-ICOS antibody or antigen-binding fragment thereof is administered. The method of any one of claims 1-9, wherein 3 mg/kg, 1 mg/kg, 0.3 mg/kg, 0.1 mg/kg, or 0.01 mg/kg of the anti-ICOS antibody or antigen-binding fragment thereof is administered. The method of any one of claims 1-11, wherein the anti-ICOS antibody or antigenbinding fragment thereof is administered once every three weeks. The method of any one of claims 1-12, wherein the anti-ICOS antibody or antigenbinding fragment thereof is administered for at least six cycles. The method of any one of claims 1-13, wherein the anti-ICOS antibody or antigenbinding fragment thereof is administered for twelve cycles. The method of any one of claims 1-14, wherein the anti-ICOS antibody or antigenbinding fragment thereof is administered intravenously. The method of claim 1 or 9, wherein the TCL is selected from the group consisting of Peripheral T-Cell Lymphoma (PTCL), Angioimmunoblastic T-Cell Lymphoma (AICL), Cutaneous T-cell Lymphoma (CTCL), or Follicular Lymphoma (FL). The method of claim 16, wherein the CTCL is mycosis fungoides. The method of claim 16, wherein the TCL is FL, and the subject has received an autologous cell transplantation prior to the administration of the anti-ICOS antibody or antigen-binding fragment thereof. The method of claim 16, wherein the PTCL is follicular type PTCL. The method of any one of claims 1-6 and 9-19, wherein the lymphoma is refractory to at least one therapy. The method of claim 20, wherein the lymphoma is refractory to at least two therapies. The method of any one of claims 1-21, wherein subject in need thereof had greater than

200 CD4+ T-cells/pl before administration of the anti-ICOS antibody or antigen-binding fragment thereof. The method of any one of claims 1-6 and 9-22, wherein the lymphoma expresses ICOS. The method of any one of claims 1-6 and 9-23, wherein the lymphoma expresses ICOS, PD1, and CXCR5. The method of any one of claims 1-6 and 9-24, wherein the anti-ICOS antibody induces antibody-dependent cellular cytotoxicity (ADCC) of cells of the lymphoma. The method of any one of claims 1-25, wherein the anti-ICOS antibody or antigenbinding fragment thereof decreases CD4+ T-cells in the subject in need thereof. The method of claim 26, wherein the CD4+ T-cells are decreased by at least 50%. The method of claim 26 or 27, wherein the CD4+ T-cells are decreased within 21 days of the first administration of the anti-ICOS antibody or antigen-binding fragment thereof. The method of any one of claims 1-28, wherein the anti-ICOS antibody or antigenbinding fragment thereof reduces circulating ICOS+ T-follicular helper (TFH) cells in the subject. The method of claim 29, wherein the circulating ICOS+ TFH cells are reduced by at least 80%. The method of claim 29 or 30, wherein the circulating ICOS+ TFH cells are reduced within 21 days of the first administration of the anti-ICOS antibody or antigen-binding fragment thereof. The method of any one of claims 1-31, wherein the anti-ICOS antibody or antigenbinding fragment thereof reduces circulating ICOS+ CD4+ cells in the subject in need thereof. The method of claim 32, wherein the circulating ICOS+ CD4+ cells are reduced by at least 80%. The method of claim 32 or 33, wherein the ICOS+ CD4+ cells are regulatory T-cells (Tregs). The method of any one of claims 32-34, wherein the circulating ICOS+ CD4+ cells are reduced within 21 days of the first administration of the anti-ICOS antibody or antigenbinding fragment thereof. The method of any one of claims 1-35 wherein the anti-ICOS antibody or antigen-binding fragment thereof reduces circulating ICOS+ CD8+ cells in the subject in need thereof. The method of claim 36, wherein the circulating ICOS+ CD8+ cells are reduced by at least 50%. The method of claim 36 or 37, wherein the circulating ICOS+ CD8+ cells are reduced within 21 days of the first administration of the anti-ICOS antibody or antigen-binding fragment thereof. The method of any one of claims 1-38, wherein the administration increases an overall response rate. The method of any one of claims 1-39, wherein the administration increases progression- free survival. The method of any one of claims 1-40, wherein the subject in need thereof is human. The method of any one of claims 1-41, wherein the anti-ICOS antibody or antigenbinding fragment thereof comprises the heavy chain variable region (VH) CDR1, VH CDR2, VH CDR3, light chain variable region (VL) CDR1, VL CDR2, and VL CDR3 of sequences of ICG91. The method of claim 42, wherein the CDRs are the Kabat-defined CDRs, the Chothia- defined CDRs, or the AbM-defined CDRs. The method of any one of claims 1-43, wherein the anti-ICOS antibody or antigenbinding fragment thereof comprises a light chain CDR1 sequence of SEQ ID NO: 1, a light chain CDR2 sequence of SEQ ID NO:2, and a light chain CDR3 sequence of SEQ ID NO:3; and a heavy chain CDR1 sequence of SEQ ID NO:4, a heavy chain CDR2 sequence of SEQ ID NO:5, and a heavy chain CDR3 sequence of SEQ ID NO:6. The method of any one of claims 1-44, wherein the anti-ICOS antibody or antigenbinding fragment thereof comprises a heavy chain variable region comprising the a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:7. The method of any one of claims 1-46, wherein the anti-ICOS antibody or antigenbinding fragment thereof comprises a light chain variable region comprising the amino acid sequence of SEQ ID NO: 8. The method of any one of claims 1-46, wherein the anti-ICOS antibody or antigenbinding fragment thereof comprises an IgGl heavy chain constant region. The method of any one of claims 1-47, wherein the anti-ICOS antibody or antigenbinding fragment thereof comprises a kappa light chain constant region. The method of any one of claims 1-48, wherein the anti-ICOS antibody or antigenbinding fragment thereof comprises an engineered IgGl Fc region. The method of claim 49, wherein the engineered IgGl Fc region comprises complex N- glycoside-linked sugar chains in which fucose is not bound to N-acetylglucosamine in the reducing end of the sugar chain. The method of claim 49 or 50, wherein the anti-ICOS antibody or antigen-binding fragment thereof comprising the engineered IgGl Fc region mediates enhanced ADCC activity as compared to the level of ADCC activity mediated by a parent antibody comprising the same heavy chain variable region and light chain variable region sequences and a wild type Fc region. The method of any one of claims 1-51, wherein the anti-ICOS antibody or antigenbinding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO:9. The method of any one of claims 1-52, wherein the anti-ICOS antibody or antigenbinding fragment thereof comprises a light chain comprising the amino acid sequence of SEQ ID NOAO. The method of any one of claims 1-53, wherein the anti-ICOS antibody or antigenbinding fragment thereof is an antibody. The method of any one of claims 1-54, wherein the anti-ICOS antibody or antigenbinding fragment thereof is an antigen-binding fragment comprises a Fab, Fab’, F(ab’)2, single chain Fv (scFv), disulfide linked Fv, V-NAR domain, IgNar, intrabody, IgGACH2, minibody, F(ab’)3, tetrabody, triabody, diabody, single-domain antibody, DVD-Ig, Fcab, mAb², (SCFV)2, or scFv-Fc. The method of claim any one of claims 1-55, wherein the anti-ICOS antibody or antigenbinding fragment thereof is a monoclonal antibody or antigen-binding fragment thereof. The method of claim any one of claims 1-56, wherein the anti-ICOS antibody or antigenbinding fragment thereof is a recombinant antibody or antigen-binding fragment thereof. The method of claim any one of claims 1-57, wherein the anti-ICOS antibody or antigenbinding fragment thereof is a human antibody or antigen-binding fragment thereof. The method of any one of claims 1-58, wherein the anti-ICOS antibody or antigenbinding fragment thereof is an antagonist antibody or antigen-binding fragment thereof. The method of any one of claims 1-59, wherein the anti-ICOS antibody or antigenbinding fragment thereof is administered in a pharmaceutical composition comprising about 80 mM sodium chloride, about 10 mM histidine, about 4% trehalose, and about 0.02% polysorbate, wherein the composition has a pH of about 6. The method of claim 60, wherein the pharmaceutical composition comprises about 10 mg/ml of the ICOS antibody or antigen-binding fragment thereof. A pharmaceutical composition comprising an anti-ICOS antibody or antigen-binding fragment thereof for use in the method of any one of claims 1-61.