Antibodies targeting TIGIT and uses thereof

Abstract

The present disclosure relates to antibodies, such as monoclonal antibodies (mAbs) or antigen-binding fragments thereof, that specifically recognize TIGIT, and methods of making and using the same.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority benefit of International Application No. PCT / CN2022 / 115189, titled "Antibodies targeting TIGIT and uses thereof", filed on August 26, 2022, the content of which is incorporated herein by reference in its entirety.

[0003] Sequence listing

[0004] The following content submitted as an XML file is incorporated herein by reference in its entirety: a sequence listing in computer - readable form (CRF) (filename: IEC232086PCT_SQL.xml, date of record: August 25, 2023, size: 190,264 bytes). Technical field

[0005] This disclosure relates to antibodies that specifically recognize TIGIT, such as monoclonal antibodies (mAbs) or antigen - binding fragments thereof, and methods for their preparation and use. Background art

[0006] T - cell immunoreceptor with Ig and ITIM domains (TIGIT, also known as Vstm3 or WUCAM) is an immune receptor belonging to the CD28 family. This 26 kDa protein contains an extracellular IgV domain, a type I transmembrane region, an intracellular immunoglobulin - tail tyrosine (ITT) - like motif in the cytoplasm, and a C - terminal immunoreceptor tyrosine - based inhibitory motif (ITIM). In naive T cells and NK cells, TIGIT is barely detectable on the cell surface, but is upregulated after activation of T cells and NK cells. In the tumor microenvironment, TIGIT is detected at high levels on regulatory T cells (Tregs), exhausted T cells, and NK cells. TIGIT has multiple ligands, including CD155 (necl - 5 or poliovirus receptor (PVR)), CD112 (nectin - 2 or poliovirus receptor - related protein 2 (PVRL2)), and CD113 (nectin - 3 or PVRL3). TIGIT can bind CD155 (PVR) with high affinity, while binding CD112 and CD113 with low affinity. Recent reports also show that TIGIT undergoes cis - interaction with CD226 (PTA1 or DNAM - 1).

[0007] TIGIT exerts its inhibitory immune checkpoint function through several mechanisms. First, upon binding to its main ligand CD155 (PVR), subsequent phosphorylation of TIGIT in its ITIM domain transduces inhibitory signals to downregulate IFN-γ expression in T cells and NK cells via the NF-κB pathway. Second, since TIGIT interacts with PVR with a higher affinity compared to CD226, it competes with CD226 and attenuates the stimulatory signals transduced by CD226. Third, binding of PVR to TIGIT on dendritic cells can lead to upregulation of IL-10 expression and downregulation of IL-12 expression, thus weakening the anti-tumor immune response of dendritic cells. Finally, recent studies have shown that TIGIT can directly bind to CD226 in cis to inhibit CD226 dimerization, which is essential for T cell activation. Thus, TIGIT acts as an important negative regulator in the immune response in infection and cancer, and blocking TIGIT signaling has been proposed as a method to enhance T cell and NK cell immunity for cancer treatment. Summary of the Invention

[0008] The present disclosure provides antibodies that specifically bind to TIGIT (e.g., human TIGIT) and block binding to PVR / CD155, thereby reducing or eliminating TIGIT-mediated immunosuppression. Also provided are pharmaceutical compositions comprising these antibodies, nucleic acids encoding these antibodies, vectors and host cells for preparing these antibodies, and methods of using these antibodies to treat a subject. The antibodies disclosed herein have shown better tumor suppression than two anti-TIGIT reference antibodies (even at suboptimal doses in late clinical stages), thus bringing great promise for treating diseases involving immunosuppression.

[0009] In one aspect, the present disclosure provides an antibody or an antigen-binding fragment thereof that binds to TIGIT, the antibody or the antigen-binding fragment thereof comprising:

[0010] (i) an HCDR1 containing a sequence selected from SEQ ID NO: 84 - 86, 98 - 100, 71, 118, 124, 130, 136, 142, 148 or 154, such as a sequence selected from SEQ ID NO: 84 - 85, 98 - 99, 71, 118, 124, 130, 136, 142, 148 or 154;

[0011] (ii) an HCDR2 containing a sequence selected from SEQ ID NO: 87 - 91, 101 - 107, 72 - 74, 119, 125, 131, 137, 143, 149 or 155, such as a sequence selected from SEQ ID NO: 87 - 90, 101 - 106, 72 - 73, 119, 125, 131, 137, 143, 149 or 155;

[0012] (iii) An HCDR3 containing a sequence of SEQ ID NO: 92, 108, 75, 120, 126, 132, 138, 144, 150 or 156;

[0013] (iv) An LCDR1 containing a sequence of SEQ ID NO: 93 - 95, 109 - 113, 76 - 78, 121, 127, 133, 139, 145, 151 or 157, such as a sequence of SEQ ID NO: 93 - 94, 109 - 112, 76 - 77, 121, 127, 133, 139, 145, 151 or 157;

[0014] (v) An LCDR2 containing a sequence of SEQ ID NO: 96, 114 - 116, 79 - 82, 122, 128, 134, 140, 146, 152 or 158, such as a sequence of SEQ ID NO: 96, 114 - 115, 79 - 81, 122, 128, 134, 140, 146, 152 or 158; and

[0015] (vi) An LCDR3 containing a sequence of SEQ ID NO: 97, 117, 83, 123, 129, 135, 141, 147, 153 or 159.

[0016] TIGIT-6

[0017] In certain embodiments, the antibody or antigen - binding fragment thereof of the present disclosure comprises:

[0018] (i) An HCDR1 containing a sequence of GYTX1TENX2MH (SEQ ID NO: 86), where X1 is I or F and X2 is T or A;

[0019] (ii) An HCDR2 containing a sequence of GINPNX3X4GTSYX5QX6FX7G (SEQ ID NO: 91), where X3 is N or Q, X4 is G or A, X5 is N or S, X6 is Q or K, and X7 is K or Q;

[0020] (iii) An HCDR3 containing a sequence of SEQ ID NO: 92;

[0021] (iv) An LCDR1 containing a sequence of X8ASQDX9KTALA (SEQ ID NO: 95), where X8 is K or Q and X9 is V or I;

[0022] (v) An LCDR2 containing a sequence of SEQ ID NO: 96; and

[0023] (vi) An LCDR3 containing the sequence of SEQ ID NO:97.

[0024] In certain embodiments, the HCDR1 contains the sequence of SEQ ID NO:84 or 85. In certain embodiments, the HCDR2 contains the sequence of SEQ ID NO:87, 88, 89 or 90. In certain embodiments, the LCDR1 contains the sequence of SEQ ID NO:93 or 94.

[0025] In certain embodiments, the antibody or its antigen-binding fragment comprises:

[0026] (1) An HCDR1, an HCDR2 and an HCDR3 containing the amino acid sequences of SEQ ID NO:84, 87 and 92 respectively; and an LCDR1, an LCDR2 and an LCDR3 containing the amino acid sequences of SEQ ID NO:93, 96 and 97 respectively; or,

[0027] (2) An HCDR1, an HCDR2 and an HCDR3 containing the following amino acid sequences: (a) SEQ ID NO:85, 87 and 92 respectively; or (b) SEQ ID NO:84, 88 and 92 respectively; or (c) SEQ ID NO:84, 89 and 92 respectively; and an LCDR1, an LCDR2 and an LCDR3 containing the amino acid sequences of SEQ ID NO:93, 96 and 97 respectively; or,

[0028] (3) An HCDR1, an HCDR2 and an HCDR3 containing the following amino acid sequences: (a) SEQ ID NO:84, 87 and 92 respectively; or (b) SEQ ID NO:84, 88 and 92 respectively; or (c) SEQ ID NO:84, 89 and 92 respectively; or (d) SEQ ID NO:84, 90 and 92 respectively; or (e) SEQ ID NO:85, 89 and 92 respectively; or (f) SEQ ID NO:85, 90 and 92 respectively; and an LCDR1, an LCDR2 and an LCDR3 containing the amino acid sequences of SEQ ID NO:94, 96 and 97 respectively.

[0029] In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein: the VH comprises the sequence of SEQ ID NO:4 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises the sequence of SEQ ID NO:5 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto. In certain embodiments, the VH comprises the sequence of SEQ ID NO:4; and / or the VL comprises the sequence of SEQ ID NO:5.

[0030] In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein: the VH comprises a framework region (FR) derived from the human immunoglobulin heavy chain variable region sequence QVG74320 of GenBank; and / or the VL comprises a framework region (FR) derived from the human immunoglobulin light chain variable region sequence ACY78416 of GenBank.

[0031] In certain embodiments, the VH comprises the sequence of SEQ ID NO:30, 31, 33, 34, 36, 37, 38 or 39 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0032] In certain embodiments, the VL comprises the sequence of SEQ ID NO:32 or 35 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0033] In certain embodiments, the antibody or antigen-binding fragment thereof comprises a VH and a VL, wherein:

[0034] (1) The VH comprises the sequence of SEQ ID NO: 30, 31, 33, 34 or 36 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises the sequence of SEQ ID NO: 32 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or

[0035] (2) The VH comprises the sequence of SEQ ID NO: 31, 34, 36, 37, 38 or 39 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises the sequence of SEQ ID NO: 35 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0036] In certain embodiments, the VH comprises the sequence of SEQ ID NO: 36, 37, 38 or 39 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises the sequence of SEQ ID NO: 35 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto. In certain embodiments, the VH comprises the sequence of SEQ ID NO: 36, 37, 38 or 39; and / or the VL comprises the sequence of SEQ ID NO: 35.

[0037] In certain embodiments, (a) the VH comprises the sequence of SEQ ID NO:36; and / or the VL comprises the sequence of SEQ ID NO:35; (b) the VH comprises the sequence of SEQ ID NO:37; and / or the VL comprises the sequence of SEQ ID NO:35; (c) the VH comprises the sequence of SEQ ID NO:38; and / or the VL comprises the sequence of SEQ ID NO:35; or, (d) the VH comprises the sequence of SEQ ID NO:39; and / or the VL comprises the sequence of SEQ ID NO:35.

[0038] TIGIT-19

[0039] In certain embodiments, the antibody or antigen-binding fragment thereof of the present disclosure comprises:

[0040] (i) HCDR1 containing the sequence of GYX1FX2RYSMY (SEQ ID NO:100), wherein X1 is A or T, and X2 is S or T;

[0041] (ii) HCDR2 containing the sequence of FIDX3YX4GGSTYX5QX6FX7G (SEQ ID NO:107), wherein X3 is P or A, X4 is N or S, X5 is N or A, X6 is R or K, and X7 is R or Q;

[0042] (iii) HCDR3 containing the sequence of SEQ ID NO:108;

[0043] (iv) LCDR1 containing the sequence of RX8SX9XIYX 10 YLS (SEQ ID NO:113), wherein X8 is P or A, X9 is E or Q, X 11 is N or S, and X 10 is T or S; 11 is T or S;

[0044] (v) LCDR2 containing the sequence of NAKX 12 LPX 13 (SEQ ID NO:116), wherein X 12 is T or S, and X 13 is E or S; and

[0045] (vi) LCDR3 containing the sequence of SEQ ID NO:117.

[0046] In certain embodiments, the HCDR1 comprises the sequence of SEQ ID NO:98 or 99. In certain embodiments, the HCDR2 comprises the sequence of SEQ ID NO:101, 102, 103, 104, 105 or 106. In certain embodiments, the LCDR1 comprises the sequence of SEQ ID NO:109, 110, 111 or 112. In certain embodiments, the LCDR2 comprises the sequence of SEQ ID NO:114 or 115.

[0047] In certain embodiments, the antibody or its antigen-binding fragment comprises:

[0048] (1) HCDR1, HCDR2 and HCDR3 containing the amino acid sequences of SEQ ID NO:98, 101 and 108, respectively; and LCDR1, LCDR2 and LCDR3 containing the amino acid sequences of SEQ ID NO:109, 114 and 117, respectively; or,

[0049] (2) HCDR1, HCDR2 and HCDR3 containing the amino acid sequences of SEQ ID NO:98, 101 and 108, respectively; and LCDR1, LCDR2 and LCDR3 having the following amino acid sequences: (a) SEQ ID NO:109, 115 and 117, respectively; or (b) SEQ ID NO:110, 115 and 117, respectively; or (c) SEQ ID NO:111, 115 and 117, respectively; or (d) SEQ ID NO:112, 115 and 117, respectively; or,

[0050] (3) HCDR1, HCDR2 and HCDR3 having the following amino acid sequences: (a) SEQ ID NO:98, 102 and 108, respectively; or (b) SEQ ID NO:98, 103 and 108, respectively; or (c) SEQ ID NO:99, 102 and 108, respectively; or (d) SEQ ID NO:99, 104 and 108, respectively; or (e) SEQ ID NO:99, 105 and 108, respectively; and LCDR1, LCDR2 and LCDR3 containing the amino acid sequences of SEQ ID NO:109, 114 and 117, respectively; or,

[0051] (4) HCDR1, HCDR2 and HCDR3 containing the amino acid sequences of SEQ ID NO:99, 105 and 108, respectively; and LCDR1, LCDR2 and LCDR3 having the following amino acid sequences: (a) SEQ ID NO:109, 115 and 117, respectively; or (b) SEQ ID NO:112, 115 and 117, respectively; or,

[0052] (5) HCDR1, HCDR2, and HCDR3 having the amino acid sequences of SEQ ID NO: 99, 106, and 108, respectively; and LCDR1, LCDR2, and LCDR3 having the following amino acid sequences: (a) SEQ ID NO: 109, 115, and 117, respectively; or (b) SEQ ID NO: 112, 115, and 117, respectively.

[0053] In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein: the VH comprises the sequence of SEQ ID NO: 10 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto; and / or the VL comprises the sequence of SEQ ID NO: 11 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto. In certain embodiments, the VH comprises the sequence of SEQ ID NO: 10; and / or the VL comprises the sequence of SEQ ID NO: 11.

[0054] In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein: the VH comprises a framework region (FR) derived from the human immunoglobulin heavy chain variable region sequence AXA20212 of GenBank; and / or the VL comprises a framework region (FR) derived from the human immunoglobulin light chain variable region sequence ABA70776 of GenBank.

[0055] In certain embodiments, the VH comprises the sequence of SEQ ID NO: 40, 46, 47, 48, 49, 50, or 51 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto.

[0056] In certain embodiments, the VL comprises the sequence of SEQ ID NO: 41, 42, 43, 44, or 45 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto.

[0057] In certain embodiments, the antibody or antigen-binding fragment thereof comprises VH and VL, wherein:

[0058] (1) the VH comprises the sequence of SEQ ID NO: 40 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto; and / or the VL comprises the sequence of SEQ ID NO: 41, 42, 43, 44, or 45 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto; or,

[0059] (2) the VH comprises the sequence of SEQ ID NO: 46, 47, 48, 49, or 50 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto; and / or the VL comprises the sequence of SEQ ID NO: 41 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto; or,

[0060] (3) The VH comprises the sequence of SEQ ID NO:50 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity therewith; and / or the VL comprises the sequence of SEQ ID NO:42 or 45 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity therewith; or,

[0061] (4) The VH comprises the sequence of SEQ ID NO:51 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity therewith; and / or the VL comprises the sequence of SEQ ID NO:42 or 45 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity therewith.

[0062] In certain embodiments, the VH comprises the sequence of SEQ ID NO:50 or 51 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity therewith; and / or the VL comprises the sequence of SEQ ID NO:42 or 45 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity therewith. In certain embodiments, the VH comprises the sequence of SEQ ID NO:50 or 51; and / or the VL comprises the sequence of SEQ ID NO:42 or 45.

[0063] In certain embodiments, (a) the VH comprises the sequence of SEQ ID NO:50; and / or the VL comprises the sequence of SEQ ID NO:42; (b) the VH comprises the sequence of SEQ ID NO:50; and / or the VL comprises the sequence of SEQ ID NO:45; (c) the VH comprises the sequence of SEQ ID NO:51; and / or the VL comprises the sequence of SEQ ID NO:42; or (d) the VH comprises the sequence of SEQ ID NO:51; and / or the VL comprises the sequence of SEQ ID NO:45.

[0064] TIGIT-3

[0065] In certain embodiments, the antibody or antigen-binding fragment thereof disclosed herein comprises:

[0066] (i) an HCDR1 comprising the sequence of SEQ ID NO:71;

[0067] (ii) an HCDR2 comprising the sequence of TIKSX1GGSTNLX2DSVKG (SEQ ID NO:74), wherein X1 is D or S and X2 is P or A;

[0068] (iii) an HCDR3 comprising the sequence of SEQ ID NO:75;

[0069] (iv) an LCDR1 comprising the sequence of X3ASQDX4KTAX5A (SEQ ID NO:78), wherein X3 is K or R, X4 is V or I, and X5 is V or L;

[0070] (v) an LCDR2 comprising the sequence of WX6STRX7X8 (SEQ ID NO:82), wherein X6 is S or A, X7 is H or Q, and X8 is T or S; and

[0071] (vi) an LCDR3 comprising the sequence of SEQ ID NO:83.

[0072] In certain embodiments, the HCDR2 comprises the sequence of SEQ ID NO:72 or 73. In certain embodiments, the LCDR1 comprises the sequence of SEQ ID NO:76 or 77. In certain embodiments, the LCDR2 comprises the sequence of SEQ ID NO:79, 80 or 81.

[0073] In certain embodiments, the antibody or antigen-binding fragment thereof comprises:

[0074] (1) HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NO:71, 72, and 75, respectively; and LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NO:76, 79, and 83, respectively; or,

[0075] (2) HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NO:71, 73, and 75, respectively; and LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NO:76, 79, and 83, respectively; or,

[0076] (3) HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NO:71, 72, and 75, respectively; and LCDR1, LCDR2, and LCDR3 comprising the following amino acid sequences: (a) SEQ ID NO:76, 79, and 83, respectively; or (b) SEQ ID NO:77, 79, and 83, respectively; or (c) SEQ ID NO:76, 80, and 83, respectively; or (d) SEQ ID NO:76, 81, and 83, respectively; or,

[0077] (4) HCDR1, HCDR2, and HCDR3 comprising the amino acid sequences of SEQ ID NO:71, 73, and 75, respectively; and LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences of SEQ ID NO:77, 81, and 83, respectively.

[0078] In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein: the VH comprises the sequence of SEQ ID NO:2 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises the sequence of SEQ ID NO:3 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto. In certain embodiments, the VH comprises the sequence of SEQ ID NO:2; and / or the VL comprises the sequence of SEQ ID NO:3.

[0079] In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein: the VH comprises a framework region (FR) derived from the human immunoglobulin heavy chain variable region sequence BAC02278 of GenBank; and / or the VL comprises a framework region (FR) derived from the human immunoglobulin light chain variable region sequence QTX15665 of GenBank.

[0080] In certain embodiments, the VH comprises the sequence of SEQ ID NO: 22 or 23 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0081] In certain embodiments, the VL comprises the sequence of SEQ ID NO: 24, 25, 26, 27, 28 or 29 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0082] In certain embodiments, the antibody or antigen-binding fragment thereof comprises a VH and a VL, wherein:

[0083] (1) the VH comprises the sequence of SEQ ID NO: 22 or 23 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises the sequence of SEQ ID NO: 3 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0084] (2) The VH comprises the sequence of SEQ ID NO: 22 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises the sequence of SEQ ID NO: 24, 25, 26 or 27 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0085] (3) The VH comprises the sequence of SEQ ID NO: 23 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises the sequence of SEQ ID NO: 28 or 29 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0086] In certain embodiments, the VH comprises the sequence of SEQ ID NO: 23 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises the sequence of SEQ ID NO: 28 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto. In certain embodiments, the VH comprises the sequence of SEQ ID NO: 23; and / or the VL comprises the sequence of SEQ ID NO: 28.

[0087] TIGIT-15, -18, -52, -63, -87, -94, -100

[0088] In certain embodiments, the antibodies or antigen-binding fragments thereof disclosed herein comprise: HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 having the amino acid sequences set forth in SEQ ID NO: 118, 119, 120, 121, 122, and 123, respectively.

[0089] In certain embodiments, the antibodies or antigen-binding fragments thereof disclosed herein comprise: a VH having the sequence set forth in SEQ ID NO: 6 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto; and / or a VL having the sequence set forth in SEQ ID NO: 7 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto.

[0090] In certain embodiments, the antibodies or antigen-binding fragments thereof disclosed herein comprise: HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 having the amino acid sequences set forth in SEQ ID NO: 124, 125, 126, 127, 128, and 129, respectively.

[0091] In certain embodiments, the antibodies or antigen-binding fragments thereof disclosed herein comprise: a VH having the sequence set forth in SEQ ID NO: 8 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto; and / or a VL having the sequence set forth in SEQ ID NO: 9 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto.

[0092] In certain embodiments, the antibodies or antigen-binding fragments thereof disclosed herein comprise: HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 having the amino acid sequences set forth in SEQ ID NO: 130, 131, 132, 133, 134, and 135, respectively.

[0093] In certain embodiments, the antibody or antigen-binding fragment thereof of the present disclosure comprises: a VH containing the sequence of SEQ ID NO:12 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a VL containing the sequence of SEQ ID NO:13 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0094] In certain embodiments, the antibody or antigen-binding fragment thereof of the present disclosure comprises: HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 containing the amino acid sequences of SEQ ID NO:136, 137, 138, 139, 140 and 141, respectively.

[0095] In certain embodiments, the antibody or antigen-binding fragment thereof of the present disclosure comprises: a VH containing the sequence of SEQ ID NO:14 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a VL containing the sequence of SEQ ID NO:15 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0096] In certain embodiments, the antibody or antigen-binding fragment thereof of the present disclosure comprises: HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 containing the amino acid sequences of SEQ ID NO:142, 143, 144, 145, 146 and 147, respectively.

[0097] In certain embodiments, an antibody or antigen-binding fragment thereof disclosed herein comprises: a VH containing the sequence of SEQ ID NO:16 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a VL containing the sequence of SEQ ID NO:17 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0098] In certain embodiments, an antibody or antigen-binding fragment thereof disclosed herein comprises: HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 containing the amino acid sequences of SEQ ID NO:148, 149, 150, 151, 152 and 153, respectively.

[0099] In certain embodiments, an antibody or antigen-binding fragment thereof disclosed herein comprises: a VH containing the sequence of SEQ ID NO:18 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a VL containing the sequence of SEQ ID NO:19 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0100] In certain embodiments, an antibody or antigen-binding fragment thereof disclosed herein comprises: HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 containing the amino acid sequences of SEQ ID NO:154, 155, 156, 157, 158 and 159, respectively.

[0101] In certain embodiments, an antibody or antigen-binding fragment thereof of the present disclosure comprises: a VH containing the sequence of SEQ ID NO:20 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a VL containing the sequence of SEQ ID NO:21 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0102] In certain embodiments, an antibody or antigen-binding fragment thereof of the present disclosure as defined in any of the foregoing embodiments may further comprise a heavy chain constant region (CH) that comprises an amino acid sequence derived from a human immunoglobulin heavy chain constant region.

[0103] In certain embodiments, the heavy chain constant region is an IgG heavy chain constant region, such as an IgG1, IgG2, IgG3 or IgG4 heavy chain constant region. In certain embodiments, the heavy chain constant region comprises the amino acid sequence of SEQ ID NO:69.

[0104] In certain embodiments, the heavy chain constant region has effector function (e.g., ADCC) or enhanced effector function (e.g., ADCC).

[0105] In certain embodiments, an antibody or antigen-binding fragment thereof of the present disclosure as defined in any of the foregoing embodiments may further comprise a light chain constant region (CL) that comprises an amino acid sequence derived from a human immunoglobulin light chain constant region.

[0106] In certain embodiments, the light chain constant region is a κ light chain constant region. In certain embodiments, the light chain constant region comprises the amino acid sequence of SEQ ID NO:70.

[0107] In certain embodiments, the antibody or antigen-binding fragment thereof is derived from TIGIT-6, which comprises:

[0108] a heavy chain containing the sequence of SEQ ID NO:56, 58, 59, 60 or 61 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or

[0109] A light chain comprising an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity to the sequence of SEQ ID NO: 57 or 62.

[0110] In certain embodiments, the antibody or antigen-binding fragment thereof comprises:

[0111] (1) A heavy chain comprising an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity to the sequence of SEQ ID NO: 56; and / or a light chain comprising an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity to the sequence of SEQ ID NO: 57; or,

[0112] (2) A heavy chain comprising an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity to the sequence of SEQ ID NO: 58, 59, 60 or 61; and / or a light chain comprising an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity to the sequence of SEQ ID NO: 62.

[0113] In certain embodiments, the antibody or antigen-binding fragment thereof is derived from TIGIT-19, which comprises:

[0114] A heavy chain comprising an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity to the sequence of SEQ ID NO: 63, 65 or 66; and / or

[0115] A light chain comprising a sequence of SEQ ID NO: 64, 67 or 68 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0116] In certain embodiments, the antibody or antigen-binding fragment thereof comprises:

[0117] (1) A heavy chain comprising a sequence of SEQ ID NO: 63 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a light chain comprising a sequence of SEQ ID NO: 64 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0118] (2) A heavy chain comprising a sequence of SEQ ID NO: 65 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a light chain comprising a sequence of SEQ ID NO: 67 or 68 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0119] (3) A heavy chain comprising a sequence of SEQ ID NO: 66 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a light chain comprising a sequence of SEQ ID NO: 67 or 68 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0120] In certain embodiments, the antibody or antigen-binding fragment thereof is derived from TIGIT-3, which comprises:

[0121] a heavy chain comprising the sequence of SEQ ID NO:52 or 54 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or

[0122] a light chain comprising the sequence of SEQ ID NO:53 or 55 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0123] In certain embodiments, the antibody or antigen-binding fragment thereof comprises:

[0124] (1) a heavy chain comprising the sequence of SEQ ID NO:52 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a light chain comprising the sequence of SEQ ID NO:53 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0125] (2) a heavy chain comprising the sequence of SEQ ID NO:54 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a light chain comprising the sequence of SEQ ID NO:55 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0126] In certain embodiments, the antibodies or antigen-binding fragments thereof of the present disclosure as defined in any of the foregoing embodiments are selected from the group consisting of: scFv, Fab, Fab', (Fab')2, Fv fragments, diabodies, bispecific antibodies, multispecific antibodies, chimeric antibodies, and humanized antibodies.

[0127] In another aspect, the present disclosure provides an immunoconjugate comprising an antibody or antigen-binding fragment thereof of the present disclosure and an effector molecule. In certain embodiments, the effector molecule is a therapeutic agent. In certain embodiments, the therapeutic agent is selected from the group consisting of: drugs, toxins, radioisotopes, proteins, peptides, and nucleic acids.

[0128] In another aspect, the present disclosure provides a bispecific or multispecific antibody comprising an antibody or antigen-binding fragment thereof of the present disclosure. In certain embodiments, the bispecific or multispecific antibody specifically binds TIGIT (e.g., human TIGIT) and a second target. In certain embodiments, the bispecific or multispecific antibody comprises a first antigen-binding domain from an antibody or antigen-binding fragment thereof of the present disclosure and a second antigen-binding domain from an antibody against the second target. In certain embodiments, the second target is a different immune regulatory receptor.

[0129] In another aspect, the present disclosure provides an isolated nucleic acid molecule comprising a nucleotide sequence encoding an antibody or antigen-binding fragment thereof of the present disclosure, or its heavy chain variable region and / or light chain variable region, or a bispecific or multispecific antibody of the present disclosure.

[0130] In another aspect, the present disclosure provides a vector (e.g., a cloning vector or an expression vector) comprising the isolated nucleic acid molecule of the present disclosure.

[0131] In another aspect, the present disclosure provides a host cell comprising the isolated nucleic acid molecule of the present disclosure or the vector of the present disclosure.

[0132] In another aspect, provided is a method for producing an antibody or antigen-binding fragment thereof of the present disclosure, or a bispecific or multispecific antibody of the present disclosure, the method comprising culturing a host cell comprising the isolated nucleic acid molecule of the present disclosure or the vector of the present disclosure under conditions permitting the expression of the antibody or antigen-binding fragment thereof or the bispecific or multispecific antibody, and recovering the antibody or antigen-binding fragment thereof or the bispecific or multispecific antibody from the culture of the cultured host cell.

[0133] In another aspect, the present disclosure provides a pharmaceutical composition comprising an antibody or an antigen-binding fragment thereof of the present disclosure, or an immunoconjugate of the present disclosure, or a bispecific or multispecific antibody of the present disclosure, or an isolated nucleic acid molecule, vector, or host cell of the present disclosure, and a pharmaceutically acceptable carrier and / or excipient. In certain embodiments, the pharmaceutical composition of the present disclosure may further comprise an additional therapeutic agent. In certain embodiments, the additional therapeutic agent is an anti-tumor agent. In certain embodiments, the additional therapeutic agent is an additional immune checkpoint inhibitor, such as an anti-PD-1 antibody, an anti-PD-L1 antibody, an anti-TIM-3 antibody, an anti-LAG-3 antibody, or an anti-CTLA-4 antibody. In certain embodiments, the additional therapeutic agent is a cytotoxic agent, such as an alkylating agent, an anti-mitotic agent, an anti-tumor antibiotic, an anti-metabolite, a topoisomerase inhibitor, a tyrosine kinase inhibitor, or a radionuclide.

[0134] In another aspect, there is provided the use of an antibody or an antigen-binding fragment thereof of the present disclosure, or an immunoconjugate of the present disclosure, or a bispecific or multispecific antibody of the present disclosure, or an isolated nucleic acid molecule, vector or host cell of the present disclosure, or a pharmaceutical composition of the present disclosure, for the manufacture of a medicament for use in: (a) increasing immune cell activation in a subject in response to an antigen; (b) enhancing the immune response in a subject; (c) reducing or eliminating TIGIT-mediated immunosuppression in a subject; (d) reducing or depleting regulatory T cells in a tumor of a subject; (e) treating a tumor of a subject; and / or (f) treating an infectious disease of a subject.

[0135] In another aspect, there is provided an antibody or an antigen-binding fragment thereof of the present disclosure, or an immunoconjugate of the present disclosure, or a bispecific or multispecific antibody of the present disclosure, or an isolated nucleic acid molecule, vector or host cell of the present disclosure, or a pharmaceutical composition of the present disclosure, for use in: (a) increasing immune cell activation in a subject in response to an antigen; (b) enhancing the immune response in a subject; (c) reducing or eliminating TIGIT-mediated immunosuppression in a subject; (d) reducing or depleting regulatory T cells in a tumor of a subject; (e) treating a tumor of a subject; and / or (f) treating an infectious disease of a subject.

[0136] In another aspect, the present disclosure provides a method that (a) increases activation of immune cells in a subject in response to an antigen; (b) enhances the immune response in the subject; (c) reduces or eliminates TIGIT-mediated immunosuppression in the subject; (d) reduces or depletes regulatory T cells in the tumor of the subject; (e) treats the tumor of the subject; and / or (f) treats an infectious disease of the subject; wherein the method comprises administering to a subject in need thereof a therapeutically effective amount of an antibody or an antigen-binding fragment thereof of the present disclosure, or an immunoconjugate of the present disclosure, or a bispecific or multispecific antibody of the present disclosure, or an isolated nucleic acid molecule, vector or host cell of the present disclosure, or a pharmaceutical composition of the present disclosure.

[0137] In certain embodiments, the tumor is a solid tumor, such as ovarian cancer, endometrial cancer, breast cancer, lung cancer (small cell or non-small cell), colon cancer, prostate cancer, cervical cancer, pancreatic cancer, gastric cancer, esophageal cancer, hepatocellular carcinoma (liver cancer), renal cell carcinoma (kidney cancer), head and neck tumors, mesothelioma, melanoma, sarcoma or brain tumors (e.g., gliomas, such as glioblastoma).

[0138] In certain embodiments, the tumor is a hematological malignancy, such as leukemia, lymphoma and myeloma, including acute myeloid leukemia, adult T-cell leukemia, T-cell large granular lymphocyte leukemia, acute lymphoblastic leukemia, chronic lymphocytic leukemia, chronic myelogenous leukemia, acute monocytic leukemia, Hodgkin lymphoma and non-Hodgkin lymphoma, and multiple myeloma.

[0139] In certain embodiments, the tumor is metastatic cancer, refractory cancer or recurrent cancer.

[0140] In certain embodiments, the subject is a mammal, such as a human.

[0141] In certain embodiments, the antibody or an antigen-binding fragment thereof, or the immunoconjugate of the present disclosure, or the bispecific or multispecific antibody of the present disclosure, or the pharmaceutical composition is used in combination with another therapeutic agent or another therapy. In certain embodiments, the other therapeutic agent is an anti-tumor agent. In certain embodiments, the other therapeutic agent is another immune checkpoint inhibitor, such as an anti-PD-1 antibody, an anti-PD-L1 antibody, an anti-TIM-3 antibody, an anti-LAG-3 antibody or an anti-CTLA-4 antibody. In certain embodiments, the other therapeutic agent is a cytotoxic agent, such as an alkylating agent, an anti-mitotic agent, an anti-tumor antibiotic, an anti-metabolite, a topoisomerase inhibitor, a tyrosine kinase inhibitor or a radionuclide. In certain embodiments, the other therapy is a standard cancer treatment, such as surgery, chemotherapy, radiotherapy, targeted therapy, immunotherapy, hormone therapy, gene therapy or palliative care.

[0142] Further features and advantages of certain embodiments of the present disclosure will become more fully apparent from the following description of its embodiments and the accompanying drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0143] Figure 1 . TIGIT / CD155 blocking reporter assay of chimeric antibodies. Antibodies 4.1D3 and Hu1217-2-2 were used as positive controls.

[0144] Figure 2a . Monovalent binding affinity between human TIGIT and chimeric / humanized anti-TIGIT antibodies. Antibodies 4.1D3 and Hu1217-2-2 were used as positive controls.

[0145] Figure 2b . Monovalent binding affinity between cynomolgus monkey TIGIT and chimeric / humanized anti-TIGIT antibodies. Antibodies 4.1D3 and Hu1217-2-2 were used as positive controls.

[0146] Figure 3a . TIGIT / CD155 blocking reporter assay of TIGIT-3 humanized antibody. Antibodies 4.1D3 and Hu1217-2-2 were used as positive controls.

[0147] Figure 3b . TIGIT / CD155 blocking reporter assay of TIGIT-6 humanized antibody. Antibodies 4.1D3 and Hu1217-2-2 were used as positive controls.

[0148] Figure 3c . TIGIT / CD155 blocking reporter assay of TIGIT-19 humanized antibody. Antibodies 4.1D3 and Hu1217-2-2 were used as positive controls.

[0149] Figure 4a . Activation of CMV-specific human primary T cells by TIGIT-3 chimeric / humanized antibodies. Antibodies 4.1D3 and Hu1217-2-2 were used as positive controls.

[0150] Figure 4b . Activation of CMV-specific human primary T cells by TIGIT-6 chimeric / humanized antibodies. Antibodies 4.1D3 and Hu1217-2-2 were used as positive controls.

[0151] Figure 4c . Activation of CMV-specific human primary T cells by TIGIT-19 chimeric / humanized antibodies. Antibodies 4.1D3 and Hu1217-2-2 were used as positive controls.

[0152] Figure 5a. Killing of human primary total T cells (CD3+) by chimeric and humanized anti-TIGIT antibodies via ADCC. Anti-CD3 IgG1 Hu38E4 was used as a positive control.

[0153] Figure 5b . Killing of human primary total helper T cells (CD4+) by chimeric and humanized anti-TIGIT antibodies via ADCC. Anti-CD3 IgG1 Hu38E4 was used as a positive control.

[0154] Figure 5c . Killing of human primary total cytotoxic T cells (CD8+) by chimeric and humanized anti-TIGIT antibodies via ADCC. Anti-CD3 IgG1 Hu38E4 was used as a positive control.

[0155] Figure 5d . Killing of human primary Treg cells (FOXP3+CD4+) by chimeric and humanized anti-TIGIT antibodies via ADCC. Anti-CD3 IgG1 Hu38E4 was used as a positive control.

[0156] Figure 6. In vivo efficacy of humanized anti-TIGIT antibody. Figure 6a Showing the inhibition of tumor growth by humanized anti-TIGIT antibody. Figure 6b Showing the change in mouse body weight. Detailed implementation mode

[0157] Definition

[0158] In this disclosure, unless otherwise specified, the scientific and technical terms used herein have the meanings commonly understood by those skilled in the art. To better understand this disclosure, the definitions and explanations of the terms are provided below.

[0159] As used herein, the term "TIGIT" refers to the T cell immunoreceptor with Ig and ITIM domains (a member of the PVR (poliovirus receptor) family of immunoglobulins), which binds to PVR / CD155 and nectin-2 / CD112. TIGIT is also known as TIGIT, WUCAM, Vstm3, and Vsig9. "Human TIGIT" refers to the TIGIT protein encoded by the wild-type human TIGIT gene. An exemplary amino acid sequence of the human TIGIT protein is provided as SEQ ID NO:1.

[0160] As used herein, the term "antibody" refers to an immunoglobulin molecule capable of specifically binding a target (such as a carbohydrate, polynucleotide, lipid, polypeptide, etc.) through at least one antigen recognition site located in the variable region of the immunoglobulin molecule. Unless otherwise specified or clear from the context, the term "antibody" as used herein can include a whole antibody and any antigen-binding fragment thereof (i.e., "antigen-binding portion") or a single chain. In one embodiment, an "antibody" typically consists of two pairs of polypeptide chains (each pair having a "light" (L) chain and a "heavy" (H) chain). Antibody light chains can be classified as kappa light chains and lambda light chains. Heavy chains can be classified as μ, δ, γ, α, or ε, and the isotypes of antibodies can be defined as IgM, IgD, IgG, IgA, and IgE, respectively. Within the light and heavy chains, the variable region and the constant region are joined by a "J" region of about 12 or more amino acids, and the heavy chain further contains a "D" region of about 3 or more amino acids. Each heavy chain consists of a heavy chain variable region (V H ) and a heavy chain constant region (C H ). The heavy chain constant region consists of three domains (C H 1, C H 2, and C H 3). Each light chain consists of a light chain variable region (V L ) and a light chain constant region (C L ). The light chain constant region consists of one domain C L . The V H and V L regions can also be subdivided into hypervariable regions (called complementarity-determining regions (CDRs)), which are interspersed with relatively conserved regions called framework regions (FRs). Each of V H and V L consists of three CDRs and four FRs arranged in the following order: from the amino terminus to the carboxy terminus, FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4. The variable regions (V H and V L ) of each heavy chain / light chain pair form the antibody binding site. The term "antibody" is not limited by any specific method used to produce the antibody; for example, it includes recombinant antibodies, monoclonal antibodies, and polyclonal antibodies.

[0161] As used herein, the term "complementary determining region" or "CDR" refers to the amino acid residues in the variable region of an antibody that are responsible for antigen binding. The precise boundaries of these amino acid residues can be defined according to various numbering systems known in the art, e.g., according to the Kabat numbering system (Kabat et al., Sequences of Proteins of Immunological Interest, 5th ed. Public Health Service, National Institutes of Health, Bethesda, Md., 1991), the Chothia numbering system (Chothia & Lesk (1987) J. Mol. Biol. 196:901-917; Chothia et al. (1989) Nature 342:878-883), the AbM numbering system (Martin, in Antibody Engineering, Vol. 2, Chapter 3, Springer Verlag), or the IMGT numbering system (Lefranc et al., Dev. Comparat. Immunol. 27:55-77, 2003). For a given antibody, a person of ordinary skill in the art can readily identify the CDRs defined by each numbering system. In addition, the correspondence between different numbering systems is well known to those of ordinary skill in the art (e.g., see Lefranc et al., Dev. Comparat. Immunol. 27:55-77, 2003). In certain embodiments, the CDRs of the antibodies of the present disclosure are defined according to the Kabat, AbM, IMGT, or Chothia numbering system or any combination thereof. Unless otherwise specified or clear from the context, the CDRs of the antibodies of the present disclosure are preferably defined according to the Abm numbering system (for HCDR1) and the Kabat numbering system (for HCDR2 and 3, LCDR1-3).

[0162] As used herein, the term "framework region" or "FR" residues refers to those amino acid residues in the variable region of an antibody other than the CDR residues as defined above.

[0163] As used herein, the term "antigen-binding fragment" of an antibody refers to a polypeptide that comprises a fragment of a full-length antibody and that retains the ability to specifically bind the same antigen to which the full-length antibody binds and / or competes with the full-length antibody for specific binding to the antigen, and that polypeptide is also referred to as an "antigen-binding portion". Antigen-binding fragments of antibodies can be produced by recombinant DNA techniques or by enzymatic or chemical cleavage of intact antibodies. In certain embodiments, the antigen-binding fragment comprises fragments of Fab, Fab', F(ab')2, Fd, Fv, dAb, and complementarity determining regions (CDRs), single-chain antibodies (e.g., scFv), chimeric antibodies, diabodies, and polypeptides that comprise at least a portion of an antibody, where the at least a portion is sufficient to confer specific antigen-binding ability to the polypeptide.

[0164] As used herein, the term "Fd fragment" refers to an antibody fragment consisting of the V H and C H 1 domains; the term "dAb fragment" refers to an antibody fragment consisting of the V H domain; the term "Fab fragment" refers to an antibody fragment consisting of the V L 、V H 、C L and C H 1 domains; the term "F(ab')2 fragment" refers to an antibody fragment that comprises two Fab fragments that are linked by disulfide bridges in the hinge region.

[0165] As used herein, the term "Fv fragment" refers to an antibody fragment consisting of the V L and V H domains of a single arm of an antibody. The Fv fragment is generally considered to be the smallest antibody fragment that can form a complete antigen-binding site. It is believed that six CDRs confer antigen-binding specificity to an antibody. However, even a single variable region (e.g., an Fd fragment that contains only three CDRs specific for an antigen) is capable of recognizing and binding an antigen, but with an affinity less than that of the entire binding site.

[0166] As used herein, the term "scFv" refers to a single polypeptide chain that comprises VL and VH domains and has a general structure of NH2-VL-linker-VH-COOH or NH2-VH-linker-VL-COOH. Suitable linkers of the prior art consist of repeated GGGGS amino acid sequences or variants thereof. For example, a linker having the amino acid sequence (GGGGS)4 can be used, but variants thereof can also be used. In some cases, a disulfide bond may also exist between the VH and VL of the scFv.

[0167] As used herein, the term "bispecific antibody" refers to a dimer of scFv, which consists of VH and VL domains linked by a short peptide linker. The linker is too short to form an intra-chain pairing of the VH and VL domains. Instead, two such scFv fragments are co-expressed to form a multimer through an inter-chain pairing (cross-pairing) of the VH and VL domains.

[0168] Each antigen-binding fragment maintains the ability to specifically bind the same antigen that the full-length antibody binds to, and / or competes with the full-length antibody for specific binding to the antigen. Antigen-binding fragments can be obtained from a given antibody (e.g., the intact antibodies provided herein) using conventional techniques known to those of skill in the art (e.g., recombinant DNA techniques or enzymatic or chemical cleavage methods), and the antigen-binding fragments can be screened for specificity in the same manner as intact antibodies.

[0169] As used herein, the terms "mAb" and "monoclonal antibody" refer to an antibody or a fragment of an antibody from a population of highly homologous antibody molecules (i.e., a population of antibody molecules that are identical except for natural mutations that may occur spontaneously). Monoclonal antibodies have high specificity for a single epitope of an antigen. In contrast to monoclonal antibodies, polyclonal antibodies generally contain at least two or more different antibodies that typically recognize different epitopes on an antigen.

[0170] Monoclonal antibodies can be obtained by hybridoma technology, which relies on fusing B cells from an immunized animal (e.g., a mouse) with immortalized myeloma cells and growing these cells under conditions where only the fused cells can survive. The resulting growing fused cells are called hybridomas. Each hybridoma produces only one immunoglobulin, which is derived from one B cell from the immunized animal. Antibodies secreted by many hybridoma clones are screened for binding to the antigen of interest, and clones with the desired specificity are selected and amplified. The products of these individual clones are monoclonal antibodies, and each monoclonal antibody is specific for a single epitope on the antigen used to immunize the animal.

[0171] Monoclonal antibodies can also be obtained by recombinant genetic engineering techniques. DNA molecules encoding the heavy and light chain genes of a monoclonal antibody can be isolated from hybridoma cells by PCR amplification using primers specific for the genes. The obtained DNA molecules are inserted into an expression vector and then transfected into host cells (such as E. coli cells, COS cells, CHO cells, or other myeloma cells that do not produce immunoglobulins), and cultured under appropriate conditions to obtain the desired recombinant antibody.

[0172] As used herein, the term "murine antibody" refers to an antibody obtained by hybridoma technology by fusing B cells from immunized mice with immortalized myeloma cells, followed by screening and purification; or an antibody secreted by a plasma cell, which is formed by the differentiation and proliferation of B cells after antigen invasion into the mouse.

[0173] As used herein, the term "chimeric antibody" refers to an antibody in which a portion of its light chain and / or heavy chain is derived from one antibody (which may be derived from a specific species or belong to a specific antibody type or subtype), and another portion of its light chain and / or heavy chain is derived from another antibody (which may be derived from the same or a different species or belong to the same or a different antibody type or subtype), provided that the antibody still retains the activity of binding to the antigen of interest. For example, the term "chimeric antibody" may include an antibody (e.g., a human-mouse chimeric antibody) in which the variable regions of the heavy and light chains of the antibody are from a first antibody (e.g., a mouse antibody), while the constant regions of the heavy and light chains of the antibody are from a second antibody (e.g., a human antibody).

[0174] The chimeric antibodies of the present disclosure can be prepared based on the sequences of the murine monoclonal antibodies prepared above. The DNA encoding the heavy and light chains can be obtained from the target murine hybridoma and engineered using standard molecular biology techniques to contain non-murine (e.g., human) immunoglobulin sequences. To prepare chimeric antibodies, methods known in the art can be used to link the variable regions of murine immunoglobulins to the constant regions of human immunoglobulins. For example, the DNA encoding VH can be operably linked to another DNA molecule encoding the heavy chain constant region to obtain a full-length heavy chain gene. The sequences of human heavy chain constant region genes are known in the art (see, e.g., Kabat, E.A. et al. (1991) Sequences of Proteins of Immunological Interest, 5th ed., U.S. Department of Health and Human Services, NIH Publication No. 91-3242), and DNA fragments containing these regions can be obtained by standard PCR amplification. The heavy chain constant region can be an IgG1, IgG2, IgG3, IgG4, IgA, IgE, IgM, or IgD constant region, but typically an IgG (e.g., IgG1 or IgG4) constant region is preferred. For example, the DNA encoding VL can be operably linked to another DNA molecule encoding the light chain constant region CL to obtain a full-length light chain gene (and Fab light chain gene). The sequences of human light chain constant region genes are known in the art (see, e.g., Kabat, E.A. et al. (1991) Sequences of Proteins of Immunological Interest, 5th ed., U.S. Department of Health and Human Services, NIH Publication No. 91-3242), and DNA fragments containing these regions can be obtained by standard PCR amplification. The light chain constant region can be a κ or λ constant region, but typically a κ constant region is preferred.

[0175] As used herein, the term "humanized antibody" refers to a genetically engineered non-human antibody whose amino acid sequence has been modified to increase its homology to the sequence of a human antibody. Typically, all or part of the CDR regions of a humanized antibody are derived from a non-human antibody (the donor antibody), and all or part of the non-CDR regions (e.g., variable region FRs and / or constant regions) are derived from a human immunoglobulin (the acceptor antibody). Humanized antibodies typically retain the desired properties of the donor antibody, including but not limited to the ability to specifically bind TIGIT (e.g., human TIGIT), the ability to block binding to PVR / CD155, etc. The donor antibody can be an antibody from a mouse, rat, rabbit, or non-human primate (e.g., cynomolgus monkey) with the desired properties.

[0176] The humanized antibodies of the present disclosure can be prepared based on the sequences of murine monoclonal antibodies prepared above. DNA encoding the heavy and light chains can be obtained from the target murine hybridoma and engineered using standard molecular biology techniques to contain non-mouse (e.g., human) immunoglobulin sequences. To prepare humanized antibodies, murine CDR regions can be grafted onto human framework sequences using any method known in the art. In cases where there is a loss of affinity of these straight-graft antibodies, several framework residues can be mutated back to their murine counterparts (i.e., backmutated) to restore the binding affinity of the antibody. At the same time, some CDR residues can also be mutated to their human counterparts to increase the humanization of the antibody, or to some other residues to remove potential post-translational modification sites, or both.

[0177] In context, the expected properties of the antibodies of the present disclosure include at least one of the following: (a) the ability to specifically bind TIGIT (e.g., human TIGIT); (b) the ability to block the binding of TIGIT to PVR / CD155; (c) reducing or eliminating TIGIT-mediated immunosuppression; (d) reducing or depleting, e.g., regulatory T cells in a tumor; (e) the ability to reduce or inhibit Treg activity; (f) increasing immune cell activation; (g) enhancing the immune response; (h) treating tumors; and / or (i) treating infectious diseases.

[0178] As used herein, the term "bispecific antibody" refers to an artificial hybrid antibody that has two different heavy chain / light chain pairs, resulting in two antigen-binding sites that are specific for different antigens. Bispecific antibodies can be produced by a variety of methods, including linking a first antibody or a fragment thereof to a second antibody or a fragment thereof, e.g., by chemical conjugation, gene fusion, non-covalent association, or other means. "Multispecific antibody" refers to an artificial hybrid antibody that has more than two different binding specificities, including, for example, trispecific antibodies or tetra-specific antibodies.

[0179] As used herein, the term "specifically bind" or "specifically binding" means that two molecules bind in a non-random manner, such as the reaction between an antibody and the antigen it targets. In some embodiments, an antibody that specifically binds an antigen (or an antibody that is specific for an antigen) refers to an antibody that binds the antigen with an affinity (K -5 M (e.g., less than about 10 -6 M, 10 -7 M, 10 -8 M, 10 -9 M or 10 -10 M or less). D )

[0180] As used herein, the term "K D "" refers to the dissociation constant of a specific antibody-antigen interaction and is used to describe the binding affinity of an antibody to an antigen. The smaller the dissociation constant, the tighter the antibody binds and the higher the affinity between the antibody and the antigen. Typically, an antibody (e.g., an antibody of the present disclosure) has a dissociation constant of less than about 10 -5 M (e.g., less than about 10 -6 M, 10 -7 M, 10 -8 M, 10 -9 M or 10 -10 M or smaller)K D Binding antigen (e.g., human TIGIT), the K D Determined, for example, by surface plasmon resonance (SPR) in a BIACORE apparatus.

[0181] As used herein, the term "vector" refers to a nucleic acid vector into which a polynucleotide can be inserted. When a vector allows expression of a protein encoded by a polynucleotide inserted therein, the vector is referred to as an expression vector. The vector can be transformed, transduced or transfected into a host cell to express the genetic material elements carried in the host cell. Vectors are well known to those skilled in the art, including but not limited to plasmids, phages, cosmids, artificial chromosomes (such as yeast artificial chromosomes (YAC), bacterial artificial chromosomes (BAC) or P1-derived artificial chromosomes (PAC)); phages (such as lambda phages or M13 phages) and animal viruses. Animal viruses that can be used as vectors include but are not limited to retroviruses (including lentiviruses), adenoviruses, adeno-associated viruses, herpes viruses (such as herpes simplex viruses), poxviruses, baculoviruses, papillomaviruses, papovaviruses (such as SV40). The vector may include multiple elements for controlling expression, including but not limited to promoter sequences, transcription initiation sequences, enhancer sequences, selection elements and reporter genes. In addition, the vector may include an origin of replication.

[0182] As used herein, the term "host cell" refers to a cell into which a vector can be introduced or transformed, including but not limited to prokaryotic cells (such as Escherichia coli or Bacillus subtilis), and eukaryotic cells (such as mammalian cells (e.g., mouse cells or human cells), insect cells or yeast cells). Suitable eukaryotic cells include but are not limited to NSO cells, Vero cells, Hela cells, COS cells, CHO cells, HEK293 cells, BHK cells or MDCKII cells.

[0183] As used herein, the term "identity" refers to the degree of match between two polypeptides or between two nucleic acids. When the two sequences being compared have the same base or amino acid monomer subunit at a site (e.g., each of two DNA molecules has adenine at a site, or each of two polypeptides has lysine at a site), the two molecules are identical at that site. The percent identity between two sequences is a function of the number of identical sites shared by the two sequences relative to the total number of sites being compared × 100. For example, if 6 out of 10 sites of two sequences are matched, the two sequences have 60% identity. For example, the DNA sequences: CTGACT and CAGGTT have 50% identity (3 out of 6 sites are matched). Generally, the comparison of two sequences is performed in a manner that produces the maximum identity. Such alignment can be carried out by using a computer program such as the Align program (DNAstar, Inc.) based on the method of Needleman et al. (J. Mol. Biol. 48:443-453, 1970). The percent identity between two amino acid sequences can also be determined using the algorithm of E. Meyers and W. Miller (Comput. Appl. Biosci., 4:11-17 (1988)) incorporated into the ALIGN program (version 2.0), using a PAM120 weight residue table, a gap length penalty of 12, and a gap penalty of 4. In addition, the percent identity between two amino acid sequences can be determined by the algorithm of Needleman and Wunsch (J. Mol. Biol. 48:444-453 (1970)) incorporated into the GAP program in the GCG software package (available at http: / / www.gcg.com), using a Blossum 62 matrix or a PAM250 matrix, and a gap weight of 16, 14, 12, 10, 8, 6, or 4 and a length weight of 1, 2, 3, 4, 5, or 6.

[0184] As used herein, the term "pharmaceutically acceptable carrier and / or excipient" refers to a carrier and / or excipient that is pharmacologically and / or physiologically compatible with a subject and active ingredients well known in the art (see, e.g., Remington's Pharmaceutical Sciences. Edited by Gennaro AR, 19th edition, Pennsylvania: Mack Publishing Company, 1995), and includes but is not limited to: pH regulators, surfactants, adjuvants, ionic strength enhancers, diluents, reagents for maintaining osmotic pressure, reagents for delaying absorption, preservatives. For example, pH regulators include but are not limited to phosphate buffered saline. Surfactants include but are not limited to cationic, anionic or non-ionic surfactants such as Tween-80. Ionic strength enhancers include but are not limited to sodium chloride. Preservatives include but are not limited to various antibacterial and antifungal agents such as parabens, chlorobutanol, phenol, sorbic acid, etc. Reagents for maintaining osmotic pressure include but are not limited to sugars, NaCl, etc. Reagents for delaying absorption include but are not limited to monostearate and gelatin. Diluents include but are not limited to water, aqueous buffers (e.g., buffered saline), alcohols and polyols (e.g., glycerol), etc. Preservatives include but are not limited to various antibacterial and antifungal agents such as thimerosal, 2-phenoxyethanol, parabens, chlorobutanol, phenol, sorbic acid, etc. Stabilizers have the meaning commonly understood by those skilled in the art, and they can stabilize the desired activity of the active ingredients in the drug (including but not limited to sodium glutamate, gelatin, SPGA, sugars (e.g., sorbitol, mannitol, starch, sucrose, lactose, dextran, or glucose), amino acids (e.g., glutamic acid, glycine), proteins (e.g., dried whey, albumin or casein) or their degradation products (e.g., lactalbumin hydrolysate), etc.). In certain exemplary embodiments, the pharmaceutically acceptable carrier or excipient includes a sterile injectable liquid (e.g., an aqueous or non-aqueous suspension or solution). In certain exemplary embodiments, such sterile injectable liquid is selected from the group consisting of: water for injection (WFI), bacteriostatic water for injection (BWFI), sodium chloride solution (e.g., 0.9% (w / v) NaCl), glucose solution (e.g., 5% glucose), solution containing surfactant (e.g., 0.01% polysorbate 20), pH buffer solution (e.g., phosphate buffer solution), Ringer's solution and any combination thereof.

[0185] As used herein, the terms "treatment / treating" refer to methods performed for obtaining a beneficial or desired clinical outcome. For the purposes of this disclosure, beneficial or desired clinical outcomes include, but are not limited to, alleviation of symptoms, reduction of the extent of the disease, stabilization (i.e., non-worsening) of the disease state, delay or slowing of disease progression, and alleviation (partially or completely) of symptoms, whether detectable or undetectable. In addition, "treatment" also refers to an extended survival period compared to the expected survival period (if no treatment is received). In certain embodiments, the beneficial or desired clinical outcomes described herein include, but are not limited to: slowing of tumor progression, cancer regression, enhancement of the anti-tumor immune response, reduction of tumor growth or size, tumor necrosis, reduction in the severity of at least one disease symptom, increase in the frequency and duration of asymptomatic periods of the disease, prevention of damage or disability caused by the affliction of the disease, or otherwise improvement of the disease symptoms of the patient.

[0186] As used herein, the term "subject" refers to any human or non-human animal that is administered a prophylactic or therapeutic treatment. The term "non-human animal" includes all vertebrates, e.g., mammals and non-mammals, such as non-human primates, sheep, dogs, cows, chickens, amphibians, reptiles, etc.

[0187] As used herein, the term "effective amount" refers to an amount sufficient to achieve or at least partially achieve the desired effect. For example, an effective amount for treating a disease refers to an amount effective to cure or at least partially block the disease and its complications in a patient suffering from the disease. Determination of such an effective amount is within the capabilities of those skilled in the art. For example, the amount effective for a therapeutic use depends on the severity of the disease to be treated, the overall status of the patient's immune system, the overall condition of the patient (such as age, weight, and gender), the route of drug administration, additional therapies used concurrently, etc.

[0188] As used herein, the term "immune cell" includes cells of hematopoietic origin that play a role in the immune response, such as lymphocytes, e.g., B cells and T cells; natural killer (NK) cells; myeloid cells, such as monocytes, macrophages, eosinophils, mast cells, basophils, and granulocytes.

[0189] As used herein, the term "immune response" refers to the action of immune cells (e.g., lymphocytes, antigen-presenting cells, phagocytes or granulocytes) and soluble macromolecules produced by immune cells or the liver (including antibodies, cytokines and complement), which results in selective damage or destruction of, or removal from the body of, invading pathogens, pathogen-infected cells or tissues, cancer cells or normal human cells or tissues (in the context of autoimmunity or pathological inflammation). In the present disclosure, the term "antigen-specific T cell response" refers to an immune response produced by T cells, which is generated when T cells are stimulated by a T cell-specific antigen. Non-limiting examples of responses produced by T cells following antigen-specific stimulation include proliferation of T cells and production of cytokines such as IFN-γ and / or IL-2.

[0190] As used herein, the term "effector function" refers to those biological activities attributable to the Fc region of an antibody (Fc region of a native sequence or amino acid sequence variant), which vary with the isotype of the antibody. Examples of antibody effector functions include, but are not limited to, Fc receptor binding affinity, antibody-dependent cell-mediated cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), antibody-dependent cell phagocytosis (ADCP), downregulation of cell surface receptors (e.g., B cell receptors), B cell activation, cytokine secretion, half-life / clearance of antibodies and antigen-antibody complexes, etc. Methods for altering the effector function of an antibody are known in the art, for example by introducing mutations in the Fc region.

[0191] As used herein, the term "antibody-dependent cell-mediated cytotoxicity (ADCC)" refers to a form of cytotoxicity in which cytotoxic effector cells specifically bind to target cells attached to an antigen through the binding of Ig to an Fc receptor (FcR) present on the cytotoxic cell (e.g., natural killer (NK) cells, neutrophils or macrophages), and then kill the target cells by secreting cytotoxins. Methods for detecting the ADCC activity of an antibody are known in the art and can be evaluated, for example, via a flow cytometry-based ADCC assay as described in Example 5.

[0192] As used herein, the terms "cancer" and "tumor" are used interchangeably and refer to a large group of diseases characterized by uncontrolled growth of abnormal cells in the body. Unregulated cell division can lead to the formation of malignant tumors or cells that invade adjacent tissues and may metastasize to distant parts of the body via the lymphatic system or bloodstream. Cancer includes both benign and malignant cancers as well as dormant tumors or micrometastases. Cancer also includes hematological malignancies.

[0193] As used herein, the term "about", when used in connection with a numerical value or range of numerical values, means a deviation of up to 10% higher (e.g., up to 5% higher, up to 2% higher, or up to 1% higher) and up to 10% lower (e.g., up to 5% lower, up to 2% lower, or up to 1% lower) from the stated value or range is still within the intended meaning of the stated value or range.

[0194] The antibodies of the present disclosure

[0195] In one aspect, the present disclosure provides an antibody or an antigen-binding fragment thereof that binds to TIGIT (e.g., human TIGIT), the antibody or antigen-binding fragment thereof comprising:

[0196] (i) an HCDR1 containing a sequence of SEQ ID NO: 84 - 86, 98 - 100, 71, 118, 124, 130, 136, 142, 148, or 154, such as a sequence of SEQ ID NO: 84 - 85, 98 - 99, 71, 118, 124, 130, 136, 142, 148, or 154;

[0197] (ii) an HCDR2 containing a sequence of SEQ ID NO: 87 - 91, 101 - 107, 72 - 74, 119, 125, 131, 137, 143, 149, or 155, such as a sequence of SEQ ID NO: 87 - 90, 101 - 106, 72 - 73, 119, 125, 131, 137, 143, 149, or 155;

[0198] (iii) an HCDR3 containing a sequence of SEQ ID NO: 92, 108, 75, 120, 126, 132, 138, 144, 150, or 156;

[0199] (iv) an LCDR1 containing a sequence of SEQ ID NO: 93 - 95, 109 - 113, 76 - 78, 121, 127, 133, 139, 145, 151, or 157, such as a sequence of SEQ ID NO: 93 - 94, 109 - 112, 76 - 77, 121, 127, 133, 139, 145, 151, or 157;

[0200] (v) an LCDR2 containing a sequence of SEQ ID NO: 96, 114 - 116, 79 - 82, 122, 128, 134, 140, 146, 152, or 158, such as a sequence of SEQ ID NO: 96, 114 - 115, 79 - 81, 122, 128, 134, 140, 146, 152, or 158; and

[0201] (vi) An LCDR3 comprising a sequence of SEQ ID NO: 97, 117, 83, 123, 129, 135, 141, 147, 153 or 159.

[0202] TIGIT-6

[0203] In certain embodiments, the antibody or antigen-binding fragment thereof of the present disclosure is derived from the murine antibody TIGIT-6 (having VH of SEQ ID NO: 4 and VL of SEQ ID NO: 5).

[0204] In certain embodiments, the antibody or antigen-binding fragment thereof comprises:

[0205] (i) An HCDR1 comprising or consisting of the sequence: GYTX1TENX2MH (SEQ ID NO: 86), where X1 is I or F and X2 is T or A;

[0206] (ii) An HCDR2 comprising or consisting of the sequence: GINPNX3X4GTSYX5QX6FX7G (SEQ ID NO: 91), where X3 is N or Q, X4 is G or A, X5 is N or S, X6 is Q or K, and X7 is K or Q;

[0207] (iii) An HCDR3 comprising or consisting of the sequence: SEQ ID NO: 92;

[0208] (iv) An LCDR1 comprising or consisting of the sequence: X8ASQDX9KTALA (SEQ ID NO: 95), where X8 is K or Q and X9 is V or I;

[0209] (v) An LCDR2 comprising or consisting of the sequence: SEQ ID NO: 96; and

[0210] (vi) An LCDR3 comprising or consisting of the sequence: SEQ ID NO: 97.

[0211] In certain embodiments, the HCDR1 comprises or consists of the sequence: SEQ ID NO: 84 or 85. In certain embodiments, the HCDR2 comprises or consists of the sequence: SEQ ID NO: 87, 88, 89 or 90. In certain embodiments, the LCDR1 comprises or consists of the sequence: SEQ ID NO: 93 or 94.

[0212] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2, and HCDR3 of VH as shown in SEQ ID NO: 4, 30, 31, 33, 34, 36, 37, 38, or 39; and LCDR1, LCDR2, and LCDR3 of VL as shown in SEQ ID NO: 5, 32, or 35. In certain embodiments, the CDRs are defined according to the Kabat, AbM, IMGT, or Chothia numbering system or any combination thereof. In certain embodiments, the CDRs are defined according to the Abm numbering system (for HCDR1) and the Kabat numbering system (for HCDR2 and 3, LCDR1-3).

[0213] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2, and HCDR3 of VH as shown in SEQ ID NO: 4; and LCDR1, LCDR2, and LCDR3 of VL as shown in SEQ ID NO: 5.

[0214] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2, and HCDR3 of VH as shown in SEQ ID NO: 30, 31, 33, 34, or 36; and LCDR1, LCDR2, and LCDR3 of VL as shown in SEQ ID NO: 32.

[0215] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2, and HCDR3 of VH as shown in SEQ ID NO: 31, 34, 36, 37, 38, or 39; and LCDR1, LCDR2, and LCDR3 of VL as shown in SEQ ID NO: 35.

[0216] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2, and HCDR3 of VH as shown in SEQ ID NO: 36, 37, 38, or 39; and LCDR1, LCDR2, and LCDR3 of VL as shown in SEQ ID NO: 35.

[0217] In certain embodiments, the antibody or antigen-binding fragment thereof comprises:

[0218] (a) HCDR1, HCDR2, and HCDR3 of VH as shown in SEQ ID NO: 36; and LCDR1, LCDR2, and LCDR3 of VL as shown in SEQ ID NO: 35;

[0219] (b) HCDR1, HCDR2, and HCDR3 of VH as shown in SEQ ID NO:37; and LCDR1, LCDR2, and LCDR3 of VL as shown in SEQ ID NO:35;

[0220] (c) HCDR1, HCDR2, and HCDR3 of VH as shown in SEQ ID NO:38; and LCDR1, LCDR2, and LCDR3 of VL as shown in SEQ ID NO:35; or

[0221] (d) HCDR1, HCDR2, and HCDR3 of VH as shown in SEQ ID NO:39; and LCDR1, LCDR2, and LCDR3 of VL as shown in SEQ ID NO:35.

[0222] In certain embodiments, the antibody or its antigen-binding fragment comprises:

[0223] HCDR1, HCDR2, and HCDR3 respectively comprising or consisting of the amino acid sequences of SEQ ID NO:84, 87, and 92; and LCDR1, LCDR2, and LCDR3 respectively comprising or consisting of the amino acid sequences of SEQ ID NO:93, 96, and 97; or,

[0224] HCDR1, HCDR2, and HCDR3 respectively comprising or consisting of the amino acid sequences of SEQ ID NO:85, 87, and 92; and LCDR1, LCDR2, and LCDR3 respectively comprising or consisting of the amino acid sequences of SEQ ID NO:93, 96, and 97; or,

[0225] HCDR1, HCDR2, and HCDR3 respectively comprising or consisting of the amino acid sequences of SEQ ID NO:84, 88, and 92; and LCDR1, LCDR2, and LCDR3 respectively comprising or consisting of the amino acid sequences of SEQ ID NO:93, 96, and 97; or,

[0226] HCDR1, HCDR2, and HCDR3 respectively comprising or consisting of the amino acid sequences of SEQ ID NO:84, 89, and 92; and LCDR1, LCDR2, and LCDR3 respectively comprising or consisting of the amino acid sequences of SEQ ID NO:93, 96, and 97; or,

[0227] HCDR1, HCDR2, and HCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:84, 87, and 92; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:94, 96, and 97; or,

[0228] HCDR1, HCDR2, and HCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:84, 88, and 92; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:94, 96, and 97; or,

[0229] HCDR1, HCDR2, and HCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:84, 89, and 92; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:94, 96, and 97; or,

[0230] HCDR1, HCDR2, and HCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:84, 90, and 92; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:94, 96, and 97; or,

[0231] HCDR1, HCDR2, and HCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:85, 89, and 92; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:94, 96, and 97; or,

[0232] HCDR1, HCDR2, and HCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:85, 90, and 92; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:94, 96, and 97.

[0233] In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein: the VH comprises or consists of the sequence of SEQ ID NO:4 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of the sequence of SEQ ID NO:5 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto. In certain embodiments, the VH comprises or consists of the sequence of SEQ ID NO:4; and / or the VL comprises or consists of the sequence of SEQ ID NO:5.

[0234] In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein: the VH comprises a framework region (FR) derived from the human immunoglobulin heavy chain variable region sequence QVG74320 of GenBank; and / or the VL comprises a framework region (FR) derived from the human immunoglobulin light chain variable region sequence ACY78416 of GenBank.

[0235] In certain embodiments, the VH comprises or consists of the sequence of SEQ ID NO:30, 31, 33, 34, 36, 37, 38 or 39 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0236] In certain embodiments, the VL comprises or consists of the sequence of SEQ ID NO:32 or 35 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0237] In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein:

[0238] The VH comprises or consists of: the sequence of SEQ ID NO:30 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:32 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or

[0239] The VH comprises or consists of: the sequence of SEQ ID NO:31 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:32 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or

[0240] The VH comprises or consists of: the sequence of SEQ ID NO:33 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:32 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or

[0241] The VH comprises or consists of: the sequence of SEQ ID NO:34 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:32 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or

[0242] The VH comprises or consists of: the sequence of SEQ ID NO:36 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:32 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or

[0243] The VH comprises or consists of: the sequence of SEQ ID NO:31 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:35 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or

[0244] The VH comprises or consists of: the sequence of SEQ ID NO:34 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:35 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or

[0245] The VH comprises or consists of: the sequence of SEQ ID NO:36 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:35 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or

[0246] The VH comprises or consists of: the sequence of SEQ ID NO:37 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:35 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or

[0247] The VH comprises or consists of: the sequence of SEQ ID NO:38 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:35 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or

[0248] The VH comprises or consists of: the sequence of SEQ ID NO:39 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:35 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0249] In certain embodiments, (a) the VH comprises the sequence of SEQ ID NO:36; and / or the VL comprises the sequence of SEQ ID NO:35; (b) the VH comprises the sequence of SEQ ID NO:37; and / or the VL comprises the sequence of SEQ ID NO:35; (c) the VH comprises the sequence of SEQ ID NO:38; and / or the VL comprises the sequence of SEQ ID NO:35; or (d) the VH comprises the sequence of SEQ ID NO:39; and / or the VL comprises the sequence of SEQ ID NO:35.

[0250] TIGIT-19

[0251] In certain embodiments, the antibody or antigen-binding fragment thereof of the present disclosure is derived from the murine antibody TIGIT-19 (having the VH of SEQ ID NO:10 and the VL of SEQ ID NO:11).

[0252] In certain embodiments, the antibody or antigen-binding fragment thereof comprises:

[0253] (i) An HCDR1 comprising or consisting of the sequence: GYX1FX2RYSMY (SEQ ID NO:100), where X1 is A or T and X2 is S or T;

[0254] (ii) An HCDR2 comprising or consisting of the sequence: FIDX3YX4GGSTYX5QX6FX7G (SEQ ID NO:107), where X3 is P or A, X4 is N or S, X5 is N or A, X6 is R or K, and X7 is R or Q;

[0255] (iii) An HCDR3 comprising or consisting of the sequence of SEQ ID NO:108;

[0256] (iv) An LCDR1 comprising or consisting of: RX8SX9X 10 IYX 11 YLS (SEQ ID NO:113), where X8 is P or A, X9 is E or Q, X 10 is N or S, X 11 is T or S;

[0257] (v) An LCDR2 comprising or consisting of: NAKX 12 LPX 13 (SEQ ID NO:116), where X 12 is T or S, X 13 is E or S; and

[0258] (vi) An LCDR3 comprising or consisting of the sequence of SEQ ID NO:117.

[0259] In certain embodiments, the HCDR1 comprises or consists of the sequence of SEQ ID NO:98 or 99. In certain embodiments, the HCDR2 comprises or consists of the sequence of SEQ ID NO:101, 102, 103, 104, 105, or 106. In certain embodiments, the LCDR1 comprises or consists of the sequence of SEQ ID NO:109, 110, 111, or 112. In certain embodiments, the LCDR2 comprises or consists of the sequence of SEQ ID NO:114 or 115.

[0260] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2, and HCDR3 of VH as shown in SEQ ID NO: 10, 40, 46, 47, 48, 49, 50, or 51; and LCDR1, LCDR2, and LCDR3 of VL as shown in SEQ ID NO: 11, 41, 42, 43, 44, or 45. In certain embodiments, the CDRs are defined according to the Kabat, AbM, IMGT, or Chothia numbering system or any combination thereof. In certain embodiments, the CDRs are defined according to the Abm numbering system (for HCDR1) and the Kabat numbering system (for HCDR2 and 3, LCDR1-3).

[0261] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2, and HCDR3 of VH as shown in SEQ ID NO: 10; and LCDR1, LCDR2, and LCDR3 of VL as shown in SEQ ID NO: 11.

[0262] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2, and HCDR3 of VH as shown in SEQ ID NO: 40; and LCDR1, LCDR2, and LCDR3 of VL as shown in SEQ ID NO: 41, 42, 43, 44, or 45.

[0263] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2, and HCDR3 of VH as shown in SEQ ID NO: 46, 47, 48, 49, or 50; and LCDR1, LCDR2, and LCDR3 of VL as shown in SEQ ID NO: 41.

[0264] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2, and HCDR3 of VH as shown in SEQ ID NO: 50; and LCDR1, LCDR2, and LCDR3 of VL as shown in SEQ ID NO: 42 or 45.

[0265] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2, and HCDR3 of VH as shown in SEQ ID NO: 51; and LCDR1, LCDR2, and LCDR3 of VL as shown in SEQ ID NO: 42 or 45.

[0266] In certain embodiments, the antibody or antigen-binding fragment thereof comprises:

[0267] HCDR1, HCDR2, and HCDR3 each containing or consisting of: the amino acid sequences of SEQ ID NO:98, 101, and 108; and LCDR1, LCDR2, and LCDR3 each containing or consisting of: the amino acid sequences of SEQ ID NO:109, 114, and 117; or,

[0268] HCDR1, HCDR2, and HCDR3 each containing or consisting of: the amino acid sequences of SEQ ID NO:98, 101, and 108; and LCDR1, LCDR2, and LCDR3 each containing or consisting of: the amino acid sequences of SEQ ID NO:109, 115, and 117; or,

[0269] HCDR1, HCDR2, and HCDR3 each containing or consisting of: the amino acid sequences of SEQ ID NO:98, 101, and 108; and LCDR1, LCDR2, and LCDR3 each containing or consisting of: the amino acid sequences of SEQ ID NO:110, 115, and 117; or,

[0270] HCDR1, HCDR2, and HCDR3 each containing or consisting of: the amino acid sequences of SEQ ID NO:98, 101, and 108; and LCDR1, LCDR2, and LCDR3 each containing or consisting of: the amino acid sequences of SEQ ID NO:111, 115, and 117; or,

[0271] HCDR1, HCDR2, and HCDR3 each containing or consisting of: the amino acid sequences of SEQ ID NO:98, 101, and 108; and LCDR1, LCDR2, and LCDR3 each containing or consisting of: the amino acid sequences of SEQ ID NO:112, 115, and 117; or,

[0272] HCDR1, HCDR2, and HCDR3 each containing or consisting of: the amino acid sequences of SEQ ID NO:98, 102, and 108; and LCDR1, LCDR2, and LCDR3 each containing or consisting of: the amino acid sequences of SEQ ID NO:109, 114, and 117; or,

[0273] HCDR1, HCDR2, and HCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:98, 103, and 108; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:109, 114, and 117; or,

[0274] HCDR1, HCDR2, and HCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:99, 102, and 108; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:109, 114, and 117; or,

[0275] HCDR1, HCDR2, and HCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:99, 104, and 108; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:109, 114, and 117; or,

[0276] HCDR1, HCDR2, and HCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:99, 105, and 108; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:109, 114, and 117; or,

[0277] HCDR1, HCDR2, and HCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:99, 105, and 108; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:109, 115, and 117; or,

[0278] HCDR1, HCDR2, and HCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:99, 105, and 108; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:112, 115, and 117; or,

[0279] HCDR1, HCDR2, and HCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:99, 106, and 108; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:109, 115, and 117; or,

[0280] HCDR1, HCDR2, and HCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:99, 106, and 108; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NO:112, 115, and 117.

[0281] In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein: the VH comprises the sequence of SEQ ID NO:10 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto; and / or the VL comprises the sequence of SEQ ID NO:11 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto. In certain embodiments, the VH comprises the sequence of SEQ ID NO:10; and / or the VL comprises the sequence of SEQ ID NO:11.

[0282] In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein: the VH comprises a framework region (FR) derived from the human immunoglobulin heavy chain variable region sequence AXA20212 in GenBank; and / or the VL comprises a framework region (FR) derived from the human immunoglobulin light chain variable region sequence ABA70776 in GenBank.

[0283] In certain embodiments, the VH comprises or consists of the sequence of SEQ ID NO: 40, 46, 47, 48, 49, 50 or 51, or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0284] In certain embodiments, the VL comprises or consists of the sequence of SEQ ID NO: 41, 42, 43, 44 or 45, or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0285] In certain embodiments, the antibody or its antigen-binding fragment comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein:

[0286] the VH comprises or consists of the sequence of SEQ ID NO: 40, or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of the sequence of SEQ ID NO: 41, or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0287] the VH comprises or consists of the sequence of SEQ ID NO: 40, or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of the sequence of SEQ ID NO: 42, or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0288] The VH comprises or consists of: the sequence of SEQ ID NO:40 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:43 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0289] The VH comprises or consists of: the sequence of SEQ ID NO:40 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:44 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0290] The VH comprises or consists of: the sequence of SEQ ID NO:40 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:45 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0291] The VH comprises or consists of: the sequence of SEQ ID NO:46 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:41 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0292] The VH comprises or consists of: the sequence of SEQ ID NO:47 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:41 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0293] The VH comprises or consists of: the sequence of SEQ ID NO:48 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:41 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0294] The VH comprises or consists of: the sequence of SEQ ID NO:49 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:41 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0295] The VH comprises or consists of: the sequence of SEQ ID NO:50 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:41 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0296] The VH comprises or consists of: the sequence of SEQ ID NO:50 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:42 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0297] The VH comprises or consists of: the sequence of SEQ ID NO:50 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:45 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0298] The VH comprises or consists of: the sequence of SEQ ID NO:51 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:42 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto;

[0299] The VH comprises or consists of: the sequence of SEQ ID NO:51 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:45 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0300] In certain embodiments, (a) the VH comprises the sequence of SEQ ID NO:50; and / or the VL comprises the sequence of SEQ ID NO:42; (b) the VH comprises the sequence of SEQ ID NO:50; and / or the VL comprises the sequence of SEQ ID NO:45; (c) the VH comprises the sequence of SEQ ID NO:51; and / or the VL comprises the sequence of SEQ ID NO:42; or (d) the VH comprises the sequence of SEQ ID NO:51; and / or the VL comprises the sequence of SEQ ID NO:45.

[0301] TIGIT-3

[0302] In certain embodiments, the antibody or antigen-binding fragment thereof of the present disclosure is derived from the murine antibody TIGIT-3 (having a VH of SEQ ID NO:2 and a VL of SEQ ID NO:3).

[0303] In certain embodiments, the antibody or antigen-binding fragment thereof comprises:

[0304] (i) an HCDR1 comprising or consisting of the sequence of SEQ ID NO:71;

[0305] (ii) an HCDR2 comprising or consisting of the sequence TIKSX1GGSTNLX2DSVKG (SEQ ID NO:74), wherein X1 is D or S and X2 is P or A;

[0306] (iii) an HCDR3 comprising or consisting of the sequence of SEQ ID NO:75;

[0307] (iv) an LCDR1 comprising or consisting of the sequence X3ASQDX4KTAX5A (SEQ ID NO:78), wherein X3 is K or R, X4 is V or I, and X5 is V or L;

[0308] (v) an LCDR2 comprising or consisting of the sequence WX6STRX7X8 (SEQ ID NO:82), wherein X6 is S or A, X7 is H or Q, and X8 is T or S; and

[0309] (vi) an LCDR3 comprising or consisting of the sequence of SEQ ID NO:83.

[0310] In certain embodiments, the HCDR2 comprises the sequence of SEQ ID NO:72 or 73. In certain embodiments, the LCDR1 comprises the sequence of SEQ ID NO:76 or 77. In certain embodiments, the LCDR2 comprises the sequence of SEQ ID NO:79, 80 or 81.

[0311] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2 and HCDR3 of VH as shown in SEQ ID NO:2, 22 or 23; and LCDR1, LCDR2 and LCDR3 of VL as shown in SEQ ID NO:3, 24, 25, 26, 27, 28 or 29. In certain embodiments, the CDRs are defined according to the Kabat, AbM, IMGT or Chothia numbering system or any combination thereof. In certain embodiments, the CDRs are defined according to the Abm numbering system (for HCDR1) and the Kabat numbering system (for HCDR2 and 3, LCDR1-3).

[0312] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2 and HCDR3 of VH as shown in SEQ ID NO:2; and LCDR1, LCDR2 and LCDR3 of VL as shown in SEQ ID NO:3.

[0313] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2 and HCDR3 of VH as shown in SEQ ID NO:22 or 23; and LCDR1, LCDR2 and LCDR3 of VL as shown in SEQ ID NO:3.

[0314] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2 and HCDR3 of VH as shown in SEQ ID NO:22; and LCDR1, LCDR2 and LCDR3 of VL as shown in SEQ ID NO:24, 25, 26 or 27.

[0315] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2 and HCDR3 of VH as shown in SEQ ID NO:23; and LCDR1, LCDR2 and LCDR3 of VL as shown in SEQ ID NO:28 or 29.

[0316] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2 and HCDR3 of VH as shown in SEQ ID NO:23; and LCDR1, LCDR2 and LCDR3 of VL as shown in SEQ ID NO:28.

[0317] In certain embodiments, the antibody or antigen-binding fragment thereof comprises:

[0318] HCDR1, HCDR2, and HCDR3 that respectively contain or consist of the amino acid sequences of SEQ ID NO:71, 72, and 75; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of the amino acid sequences of SEQ ID NO:76, 79, and 83; or,

[0319] HCDR1, HCDR2, and HCDR3 that respectively contain or consist of the amino acid sequences of SEQ ID NO:71, 73, and 75; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of the amino acid sequences of SEQ ID NO:76, 79, and 83; or,

[0320] HCDR1, HCDR2, and HCDR3 that contain or consist of the amino acid sequences of SEQ ID NO:71, 72, and 75; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of the amino acid sequences of SEQ ID NO:76, 79, and 83; or,

[0321] HCDR1, HCDR2, and HCDR3 that contain or consist of the amino acid sequences of SEQ ID NO:71, 72, and 75; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of the amino acid sequences of SEQ ID NO:77, 79, and 83; or,

[0322] HCDR1, HCDR2, and HCDR3 that contain or consist of the amino acid sequences of SEQ ID NO:71, 72, and 75; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of the amino acid sequences of SEQ ID NO:76, 80, and 83; or,

[0323] HCDR1, HCDR2, and HCDR3 that contain or consist of the amino acid sequences of SEQ ID NO:71, 72, and 75; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of the amino acid sequences of SEQ ID NO:76, 81, and 83; or,

[0324] HCDR1, HCDR2, and HCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NOs: 71, 73, and 75; and LCDR1, LCDR2, and LCDR3 that respectively contain or consist of: the amino acid sequences of SEQ ID NOs: 77, 81, and 83.

[0325] In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein: the VH comprises the sequence of SEQ ID NO: 2 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto; and / or the VL comprises the sequence of SEQ ID NO: 3 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto. In certain embodiments, the VH comprises the sequence of SEQ ID NO: 2; and / or the VL comprises the sequence of SEQ ID NO: 3.

[0326] In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein: the VH comprises a framework region (FR) derived from the human immunoglobulin heavy chain variable region sequence BAC02278 in GenBank; and / or the VL comprises a framework region (FR) derived from the human immunoglobulin light chain variable region sequence QTX15665 in GenBank.

[0327] In certain embodiments, the VH comprises the sequence of SEQ ID NO: 22 or 23 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto.

[0328] In certain embodiments, the VL comprises or consists of: the sequence of SEQ ID NO:24, 25, 26, 27, 28 or 29, or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0329] In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein:

[0330] the VH comprises or consists of: the sequence of SEQ ID NO:22, or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:3, or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0331] the VH comprises or consists of: the sequence of SEQ ID NO:23, or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:3, or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0332] The VH comprises or consists of: the sequence of SEQ ID NO:22 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:24 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0333] The VH comprises or consists of: the sequence of SEQ ID NO:22 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:25 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0334] The VH comprises or consists of: the sequence of SEQ ID NO:22 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:26 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0335] The VH comprises or consists of: the sequence of SEQ ID NO:22 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:27 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0336] The VH comprises or consists of: the sequence of SEQ ID NO:23 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:28 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0337] The VH comprises or consists of: the sequence of SEQ ID NO:23 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or the VL comprises or consists of: the sequence of SEQ ID NO:29 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0338] In certain embodiments, the VH comprises or consists of: the sequence of SEQ ID NO:23; and / or the VL comprises or consists of: the sequence of SEQ ID NO:28.

[0339] TIGIT-15, -18, -52, -63, -87, -94, -100

[0340] In certain embodiments, the antibodies or antigen-binding fragments thereof of the present disclosure are derived from murine antibodies TIGIT-15, -18, -52, -63, -87, -94, or -100.

[0341] In certain embodiments, the antibodies or antigen-binding fragments thereof of the present disclosure comprise HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 that respectively contain or consist of the amino acid sequences of SEQ ID NOs: 118, 119, 120, 121, 122, and 123.

[0342] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2, and HCDR3 of VH as shown in SEQ ID NO: 6; and LCDR1, LCDR2, and LCDR3 of VL as shown in SEQ ID NO: 7. In certain embodiments, the CDRs are defined according to the Kabat, AbM, IMGT, or Chothia numbering system or any combination thereof. In certain embodiments, the CDRs are defined according to the Abm numbering system (for HCDR1) and the Kabat numbering system (for HCDR2 and 3, LCDR1-3).

[0343] In certain embodiments, the antibodies or antigen-binding fragments thereof of the present disclosure comprise: VH that contains or consists of the sequence of SEQ ID NO: 6 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto; and / or VL that contains or consists of the sequence of SEQ ID NO: 7 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto.

[0344] In certain embodiments, the antibodies or antigen-binding fragments thereof of the present disclosure comprise HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 that respectively contain or consist of the amino acid sequences of SEQ ID NOs: 124, 125, 126, 127, 128, and 129.

[0345] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2, and HCDR3 of VH as set forth in SEQ ID NO:8; and LCDR1, LCDR2, and LCDR3 of VL as set forth in SEQ ID NO:9. In certain embodiments, the CDRs are defined according to the Kabat, AbM, IMGT, or Chothia numbering system or any combination thereof. In certain embodiments, the CDRs are defined according to the Abm numbering system (for HCDR1) and the Kabat numbering system (for HCDR2 and 3, LCDR1-3).

[0346] In certain embodiments, the antibody or antigen-binding fragment thereof disclosed herein comprises: a VH comprising or consisting of the sequence of SEQ ID NO:8 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto; and / or a VL comprising or consisting of the sequence of SEQ ID NO:9 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto.

[0347] In certain embodiments, the antibody or antigen-binding fragment thereof disclosed herein comprises: HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprising or consisting of the amino acid sequences of SEQ ID NOs: 130, 131, 132, 133, 134, and 135, respectively.

[0348] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2, and HCDR3 of VH as set forth in SEQ ID NO:12; and LCDR1, LCDR2, and LCDR3 of VL as set forth in SEQ ID NO:13. In certain embodiments, the CDRs are defined according to the Kabat, AbM, IMGT, or Chothia numbering system or any combination thereof. In certain embodiments, the CDRs are defined according to the Abm numbering system (for HCDR1) and the Kabat numbering system (for HCDR2 and 3, LCDR1-3).

[0349] In certain embodiments, the antibodies or antigen-binding fragments thereof disclosed herein comprise a VH comprising or consisting of the sequence of SEQ ID NO:12 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a VL comprising or consisting of the sequence of SEQ ID NO:13 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0350] In certain embodiments, the antibodies or antigen-binding fragments thereof disclosed herein comprise HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprising or consisting of the amino acid sequences of SEQ ID NO:136, 137, 138, 139, 140, and 141, respectively.

[0351] In certain embodiments, the antibody or antigen-binding fragment thereof comprises HCDR1, HCDR2, and HCDR3 of the VH as shown in SEQ ID NO:14; and LCDR1, LCDR2, and LCDR3 of the VL as shown in SEQ ID NO:15. In certain embodiments, the CDRs are defined according to the Kabat, AbM, IMGT, or Chothia numbering system or any combination thereof. In certain embodiments, the CDRs are defined according to the Abm numbering system (for HCDR1) and the Kabat numbering system (for HCDR2 and 3, LCDR1-3).

[0352] In certain embodiments, the antibodies or antigen-binding fragments thereof disclosed herein comprise a VH comprising or consisting of the sequence of SEQ ID NO:14 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a VL comprising or consisting of the sequence of SEQ ID NO:15 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0353] In certain embodiments, the antibody or antigen-binding fragment thereof of the present disclosure comprises: HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 that respectively contain or consist of the amino acid sequences of SEQ ID NOs: 142, 143, 144, 145, 146, and 147.

[0354] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2, and HCDR3 of VH as shown in SEQ ID NO: 16; and LCDR1, LCDR2, and LCDR3 of VL as shown in SEQ ID NO: 17. In certain embodiments, the CDRs are defined according to the Kabat, AbM, IMGT, or Chothia numbering system or any combination thereof. In certain embodiments, the CDRs are defined according to the Abm numbering system (for HCDR1) and the Kabat numbering system (for HCDR2 and 3, LCDR1-3).

[0355] In certain embodiments, the antibody or antigen-binding fragment thereof of the present disclosure comprises: VH that contains or consists of the sequence of SEQ ID NO: 16 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto; and / or VL that contains or consists of the sequence of SEQ ID NO: 17 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto.

[0356] In certain embodiments, the antibody or antigen-binding fragment thereof of the present disclosure comprises: HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 that respectively contain or consist of the amino acid sequences of SEQ ID NOs: 148, 149, 150, 151, 152, and 153.

[0357] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2, and HCDR3 of VH as shown in SEQ ID NO:18; and LCDR1, LCDR2, and LCDR3 of VL as shown in SEQ ID NO:19. In certain embodiments, the CDRs are defined according to the Kabat, AbM, IMGT, or Chothia numbering system or any combination thereof. In certain embodiments, the CDRs are defined according to the Abm numbering system (for HCDR1) and the Kabat numbering system (for HCDR2 and 3, LCDR1-3).

[0358] In certain embodiments, the antibody or antigen-binding fragment thereof disclosed herein comprises: a VH comprising or consisting of the sequence of SEQ ID NO:18 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto; and / or a VL comprising or consisting of the sequence of SEQ ID NO:19 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto.

[0359] In certain embodiments, the antibody or antigen-binding fragment thereof disclosed herein comprises: HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 respectively comprising or consisting of the amino acid sequences of SEQ ID NO:154, 155, 156, 157, 158, and 159.

[0360] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: HCDR1, HCDR2, and HCDR3 of VH as shown in SEQ ID NO:20; and LCDR1, LCDR2, and LCDR3 of VL as shown in SEQ ID NO:21. In certain embodiments, the CDRs are defined according to the Kabat, AbM, IMGT, or Chothia numbering system or any combination thereof. In certain embodiments, the CDRs are defined according to the Abm numbering system (for HCDR1) and the Kabat numbering system (for HCDR2 and 3, LCDR1-3).

[0361] In certain embodiments, the antibody or antigen-binding fragment thereof of the present disclosure comprises a VH containing or consisting of the sequence of SEQ ID NO:20 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a VL containing or consisting of the sequence of SEQ ID NO:21 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0362] Constant region

[0363] The antibody or antigen-binding fragment thereof of the present disclosure may further comprise a constant region sequence derived from a mammalian (e.g., murine or human) immunoglobulin.

[0364] In certain embodiments, the antibody or antigen-binding fragment thereof of the present disclosure comprises a constant region sequence derived from a human immunoglobulin.

[0365] Any immunoglobulin constant region can be used in the antibodies disclosed herein. In certain embodiments, the heavy chain constant region can be the heavy chain constant region of a human IgG, IgE, IgM, IgD, IgA or IgY immunoglobulin molecule, any class (e.g., IgG1, IgG2, IgG3, IgG4, IgA1 and IgA2) or any subclass of an immunoglobulin molecule (e.g., IgG2a and IgG2b). The light chain constant region can be λ or κ. In certain embodiments, the heavy chain constant region is an IgG heavy chain constant region, such as an IgG1, IgG2, IgG3 or IgG4 heavy chain constant region. In certain embodiments, the light chain constant region is κ.

[0366] The choice of constant region depends in part on whether antibody-dependent complement and / or cell-mediated cytotoxicity is desired. In certain embodiments, a heavy chain constant region with less or reduced effector function is preferred. In certain embodiments, a heavy chain constant region with effector function or enhanced effector function is preferred. In certain embodiments, a heavy chain constant region with ADCC or enhanced ADCC is preferred.

[0367] In certain embodiments, the heavy chain of the antibody or antigen-binding fragment thereof of the present disclosure comprises a heavy chain constant region (CH) that comprises an amino acid sequence derived from a human immunoglobulin heavy chain constant region.

[0368] In certain embodiments, the antibody or antigen-binding fragment thereof of the present disclosure comprises a heavy chain constant region that is a wild-type heavy chain constant region.

[0369] In certain embodiments, the antibody or antigen-binding fragment thereof of the present disclosure comprises a heavy chain constant region that is a variant of the wild-type heavy chain constant region. One or more mutations (e.g., one or more amino acid substitutions) can be introduced into the Fc region of the constant region to alter (increase, decrease, or eliminate) one or more effector functions of the antibody, such as ADCC, CDC, or ADCP, compared to an antibody without the one or more mutations.

[0370] In certain embodiments, the heavy chain constant region comprises or consists of the amino acid sequence of SEQ ID NO:69.

[0371] In certain embodiments, the light chain of the antibody or antigen-binding fragment thereof of the present disclosure comprises a light chain constant region (CL) that comprises an amino acid sequence derived from the human immunoglobulin light chain constant region.

[0372] In certain embodiments, the light chain constant region comprises or consists of the amino acid sequence of SEQ ID NO:70.

[0373] Full-length antibody

[0374] The antibody of the present disclosure can be an antibody comprising two heavy chains and two light chains having a conventional "Y" structure.

[0375] In certain embodiments, the antibody or antigen-binding fragment thereof is derived from TIGIT-6, which comprises: a heavy chain comprising or consisting of the sequence of SEQ ID NO:56, 58, 59, 60, or 61 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto; and / or a light chain comprising or consisting of the sequence of SEQ ID NO:57 or 62 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) sequence identity thereto.

[0376] In certain embodiments, the antibody or antigen-binding fragment thereof comprises:

[0377] A heavy chain comprising or consisting of: the sequence of SEQ ID NO:56 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a light chain comprising or consisting of: the sequence of SEQ ID NO:57 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0378] A heavy chain comprising or consisting of: the sequence of SEQ ID NO:58 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a light chain comprising or consisting of: the sequence of SEQ ID NO:62 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0379] A heavy chain comprising or consisting of: the sequence of SEQ ID NO:59 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a light chain comprising or consisting of: the sequence of SEQ ID NO:62 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0380] A heavy chain comprising or consisting of: the sequence of SEQ ID NO:60 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a light chain comprising or consisting of: the sequence of SEQ ID NO:62 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0381] A heavy chain comprising or consisting of: the sequence of SEQ ID NO:61 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a light chain comprising or consisting of: the sequence of SEQ ID NO:62 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0382] In certain embodiments, the antibody or antigen-binding fragment thereof is derived from TIGIT-19, which comprises: a heavy chain comprising or consisting of: the sequence of SEQ ID NO:63, 65 or 66 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a light chain comprising or consisting of: the sequence of SEQ ID NO:64, 67 or 68 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0383] In certain embodiments, the antibody or antigen-binding fragment thereof comprises:

[0384] a heavy chain comprising or consisting of: the sequence of SEQ ID NO:63 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a light chain comprising or consisting of: the sequence of SEQ ID NO:64 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0385] a heavy chain comprising or consisting of: the sequence of SEQ ID NO:65 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a light chain comprising or consisting of: the sequence of SEQ ID NO:67 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0386] a heavy chain comprising or consisting of: the sequence of SEQ ID NO:65 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a light chain comprising or consisting of: the sequence of SEQ ID NO:68 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0387] a heavy chain comprising or consisting of: the sequence of SEQ ID NO:66 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a light chain comprising or consisting of: the sequence of SEQ ID NO:67 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0388] a heavy chain comprising or consisting of: the sequence of SEQ ID NO:66 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a light chain comprising or consisting of: the sequence of SEQ ID NO:68 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0389] In certain embodiments, the antibody or antigen-binding fragment thereof is derived from TIGIT-3, which comprises: a heavy chain comprising or consisting of: the sequence of SEQ ID NO:52 or 54 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a light chain comprising or consisting of: the sequence of SEQ ID NO:53 or 55 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0390] In certain embodiments, the antibody or antigen-binding fragment thereof comprises:

[0391] A heavy chain comprising or consisting of: the sequence of SEQ ID NO:52 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a light chain comprising or consisting of: the sequence of SEQ ID NO:53 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; or,

[0392] A heavy chain comprising or consisting of: the sequence of SEQ ID NO:54 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto; and / or a light chain comprising or consisting of: the sequence of SEQ ID NO:55 or an amino acid sequence having at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100%) sequence identity thereto.

[0393] Antigen-binding fragment

[0394] The antibodies of the present disclosure may also be Fab fragments, Fab', F(ab)2, Fv, scFv or any other type of fragment of an antibody having a conventional "Y" - shaped structure that substantially retains the ability to specifically bind to TIGIT (e.g., human TIGIT) and block the binding of TIGIT (e.g., human TIGIT) to PVR / CD155.

[0395] In certain embodiments, the antibodies or antigen - binding fragments of the present disclosure are selected from the group consisting of: scFv, Fab, Fab', (Fab')2, Fv fragments, diabodies, bispecific antibodies, multispecific antibodies, chimeric antibodies or humanized antibodies.

[0396] The antibodies or antigen - binding fragments of the present disclosure have one or more of the following properties: (1) high specificity and high affinity for TIGIT (e.g., human TIGIT and / or cynomolgus monkey TIGIT), e.g., as measured by SPR, the KD is about 1×10 -9 M or less, preferably about 1×10 -10M or less, more preferably about 1×10 -11 M or less; (2) blocking the binding of TIGIT (e.g., human TIGIT) to PVR / CD155, e.g., as measured by a TIGIT / CD155 blocking reporter assay as defined in Example 3, with an EC50 of about 10 nM or less, about 9 nM or less, about 5 nM or less; (3) increasing T cell activation as compared to T cell activation in the absence of an anti-TIGIT antibody, e.g., as measured by the secretion of IFN-γ and / or IL-2 promoted when T cells are contacted with the antibody; (4) reducing or depleting Tregs, e.g., as measured by a flow cytometry-based ADCC assay as described in Example 5 when effector cells are contacted with PBMC target cells in the presence of an anti-TIGIT antibody; (5) treating a tumor, e.g., as measured by tumor growth inhibition in a CT26 tumor model; (6) treating an infectious disease.

[0397] Also provided are "conservative sequence modifications" of the antibody sequences provided herein, i.e., nucleotide sequence modifications and amino acid sequence modifications that do not eliminate the binding of the antibody encoded by the nucleotide sequence or containing the amino acid sequence to an antigen. For example, the modifications can be introduced by standard techniques known in the art, such as site-directed mutagenesis and PCR-mediated mutagenesis. The resulting modified antibodies can be screened for their binding activity.

[0398] Conservative sequence modifications include conservative amino acid substitutions, where an amino acid residue is replaced with an amino acid residue having a similar side chain. Families of amino acid residues having similar side chains have been defined in the art. These families include amino acids having basic side chains (e.g., lysine, arginine, histidine), amino acids having acidic side chains (e.g., aspartic acid, glutamic acid), amino acids having uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine, tryptophan), amino acids having nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine), amino acids having β-branched side chains (e.g., threonine, valine, isoleucine), and amino acids having aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine). Accordingly, non-essential amino acid residues predicted in the antibodies disclosed herein can preferably be replaced with another amino acid residue from the same side chain family. Methods for identifying nucleotide and amino acid conservative substitutions that do not abolish antigen binding are well known in the art. See, e.g., Brummell et al., Biochem. 32:1180-1187 (1993); Kobayashi et al., Protein Eng. 12(10):879-884 (1999); and Burks et al., Proc. Natl. Acad. Sci. USA 94:412-417 (1997)).

[0399] Derivatized antibody

[0400] The antibodies or antigen-binding fragments thereof disclosed herein can be derivatized, e.g., conjugated to another molecule (e.g., another polypeptide or protein). Generally, derivatization (such as labeling) of the antibody or its antigen-binding fragment does not adversely affect its binding to TIGIT. Accordingly, the antibodies or antigen-binding fragments thereof disclosed herein are also intended to include such derivatized forms. For example, the antibodies or antigen-binding fragments thereof disclosed herein can be functionally linked (by chemical conjugation, genetic fusion, non-covalent linkage, or other means) to one or more other molecular moieties, such as another antibody (e.g., to form a bispecific antibody), a detection agent, a pharmaceutical agent, and / or a protein or polypeptide capable of mediating the association of the antibody or its antigen-binding fragment with another molecule (such as avidin or a polyhistidine tag).

[0401] Labeled antibody

[0402] In certain embodiments, the antibodies or antigen-binding fragments thereof of the present disclosure are labeled, such as with a detectable label. A detectable label can be any substance that can be detected directly or indirectly (e.g., through an enzymatic reaction or molecular interaction). In certain embodiments, the label can be detected by fluorescence, spectroscopy, photochemistry, biochemistry, immunology, electro, optics, or chemical means. In certain embodiments, the detectable label can be suitable for immunoassays (e.g., enzyme-linked immunosorbent assay, radioimmunoassay, fluorescence immunoassay, chemiluminescent immunoassay, etc.). In certain embodiments, the label is selected from enzymes, radionuclides, fluorescent dyes, luminescent substances (e.g., chemiluminescent substances), or biotin. In certain embodiments, the label can be linked to the antibodies or antigen-binding fragments thereof of the present disclosure via linkers of different lengths to reduce potential steric hindrance.

[0403] In certain embodiments, the labeled antibodies or antigen-binding fragments thereof as described herein can be used to detect the presence of TIGIT in a biological sample. As used herein, the term "detect" encompasses both quantitative and qualitative detection. In certain embodiments, the biological sample is blood, serum, or other liquid samples of biological origin. In certain embodiments, the biological sample includes cells or tissues.

[0404] In certain embodiments, methods for detecting TIGIT in cells are provided, the method comprising contacting the cells with the labeled antibodies or antigen-binding fragments thereof as described herein. In certain embodiments, methods for detecting the presence of TIGIT in a biological sample are provided. In certain embodiments, the method comprises detecting the presence of TIGIT protein in the biological sample. In certain embodiments, the TIGIT is human TIGIT. In certain embodiments, the method comprises contacting the biological sample with the labeled antibodies or antigen-binding fragments thereof as described herein under conditions that permit binding of the antibody or antigen-binding fragment to TIGIT, and detecting the signal from the label. Such methods can be in vitro or in vivo methods. In certain embodiments, methods for diagnosing a disease associated with TIGIT expression (e.g., a tumor or an infectious disease) in an individual are provided, the method comprising administering to the individual the labeled antibodies or antigen-binding fragments thereof as described herein, and detecting the label in the individual. In certain embodiments, the labeled antibodies or antigen-binding fragments thereof as described herein are used to select subjects eligible for therapy with any anti-TIGIT therapeutic agent (e.g., an antibody or antigen-binding fragment, an immunoconjugate, or a bispecific or multispecific antibody as described herein), wherein TIGIT is a biomarker for patient selection.

[0405] Immunoconjugate

[0406] In another aspect, there is provided an immunoconjugate comprising an antibody or an antigen-binding fragment thereof as described herein and an effector molecule. Exemplary effector molecules include, but are not limited to, drugs, toxins, radioisotopes, proteins, peptides, and nucleic acids. In certain embodiments, the effector molecule is a therapeutic agent.

[0407] In certain embodiments, the immunoconjugates of the present disclosure comprise an antibody or an antigen-binding fragment thereof as described herein, which is conjugated to one or more cytotoxic agents such as chemotherapeutic agents or drugs, growth inhibitors, toxins (e.g., protein toxins, enzymatically active toxins of bacterial, fungal, plant, or animal origin, or fragments thereof), or radioisotopes.

[0408] In certain embodiments, the immunoconjugates of the present disclosure are antibody-drug conjugates (ADCs), wherein an antibody or an antigen-binding fragment thereof as described herein is conjugated to one or more drugs, including but not limited to maytansinoids (see U.S. Patent Nos. 5,208,020, 5,416,064, and European Patent EP 0425235 B1); auristatins, such as monomethyl auristatin drug moieties DE and DF (MMAE and MMAF) (see U.S. Patent Nos. 5,635,483, 5,780,588, and 7,498,298); dolastatin; calicheamicin or its derivatives (see U.S. Patent Nos. 5,712,374, 5,714,586, 5,739,116, 5,767,285, 5,770,701, 5,770,710, 5,773,001, and 5,877,296; Hinman et al., Cancer Res. 53:3336-3342 (1993); and Lode et al., Cancer Res. 58:2925-2928 (1998)); and anthracyclines, such as daunomycin or doxorubicin (see Kratz et al., Current Med. Chem. 13:477-523 (2006); Jeffrey et al., Bioorganic & Med. Chem. Letters 16:358-362 (2006); Torgov et al., Bioconj. Chem. 16:717-721 (2005); Nagy et al., Proc. Natl. Acad. Sci. USA 97:829-834 (2000); Dubowchik et al., Bioorg. & Med. Chem. Letters 12:1529-1532 (2002); King et al., J. Med. Chem. 45:4336-4343 (2002); and U.S. Patent No. 6,630,579); methotrexate; vindesine; taxanes, such as docetaxel, paclitaxel, larotaxel, tesetaxel, and ortataxel; trichothecene; and CC1065.

[0409] In certain embodiments, the immunoconjugates of the present disclosure comprise an antibody or an antigen-binding fragment thereof as described herein conjugated to an enzymatically active toxin or a fragment thereof, the enzymatically active toxin or a fragment thereof including but not limited to diphtheria A chain, a non-binding active fragment of diphtheria toxin, exotoxin A chain (from Pseudomonas aeruginosa), ricin A chain, abrin A chain, modeccin A chain, alpha-sarcin, aleurites fordii protein, dianthin, pokeweed antiviral proteins (PAPI, PAPII, and PAP-S), momordica charantia inhibitor, jatrophin, croton toxin, saponaria officinalis inhibitor, cladophyllin, mitogellin, restrictocin, phenomycin, enomycin, and tricothecene.

[0410] In certain embodiments, the immunoconjugates of the present disclosure comprise an antibody or an antigen-binding fragment thereof as described herein conjugated to a radioactive atom to form a radio conjugate. A variety of radioisotopes can be used to produce radio conjugates. Examples include At 211 , I 131 , I 125 , Y 90 , Re 186 , Re 188 , Sm 153 , Bi 212 , P 32 , Pb 212 and radioisotopes of Lu. When the radio conjugate is used for detection, it can comprise a radioactive atom for scintigraphic studies, such as Tc99m or I123, or a spin label for nuclear magnetic resonance (NMR) imaging (also known as magnetic resonance imaging, "MRI"), such as iodine-123, iodine-131, indium-111, fluorine-19, carbon-13, nitrogen-15, oxygen-17, gadolinium, manganese, or iron.

[0411] Conjugates of antibodies and cytotoxic agents can be prepared using a variety of bifunctional protein coupling agents such as N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP), succinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate (SMCC), iminothiolane (IT), bifunctional derivatives of imidoesters (such as dimethyl adipimidate HCl), active esters (such as disuccinimidyl suberate), aldehydes (such as glutaraldehyde), bisazides (such as bis(p-azidobenzoyl)hexanediamine), diazotized derivatives (such as bis(p-diazobenzoyl)-ethylenediamine), diisocyanates (such as toluene 2,6-diisocyanate) and bifunctional fluorine compounds (such as 1,5-difluoro-2,4-dinitrobenzene). For example, ricin immunotoxins can be prepared as described by Vitetta et al., Science 238:1098 (1987). Carbon-14 labeled 1-benzylisothiocyanato-3-methyl-diethylenetriaminepentaacetic acid (MX-DTPA) is an exemplary chelating agent for conjugating radio nucleotides to antibodies. See WO 94 / 11026. The linker can be a "cleavable linker" that facilitates the release of the cytotoxic drug in the cell. For example, acid-labile linkers, peptidase-sensitive linkers, photo-labile linkers, dimethyl linkers or disulfide-containing linkers can be used (Chari et al., Cancer Res. 52:127-131 (1992); U.S. Patent No. 5,208,020).

[0412] The immunoconjugates or ADCs herein clearly contemplate but are not limited to such conjugates prepared with crosslinking reagent agents, which include but are not limited to BMPS, EMCS, GMBS, HBVS, LC-SMCC, MBS, MPBH, SBAP, SIA, SIAB, SMCC, SMPB, SMPH, sulfo-EMCS, sulfo-GMBS, sulfo-KMUS, sulfo-MBS, sulfo-SIAB, sulfo-SMCC and sulfo-SMPB and SVSB (succinimidyl-(4-vinylsulfone)benzoate) that are commercially available (e.g., from Pierce Biotechnology, Inc., Rockford, IL., U.S.A).

[0413] Bispecific antibody

[0414] The antibodies or antigen-binding fragments thereof disclosed herein can be used to form bispecific or multispecific antibodies. The antibodies or antigen-binding fragments thereof disclosed herein can be part of a bispecific or multispecific antibody that includes a second functional module (e.g., a second antibody) having a binding specificity different from that of the antibodies or antigen-binding fragments thereof disclosed herein, such that it is capable of binding to at least two different binding sites and / or target molecules. For example, the antibodies or antigen-binding fragments thereof disclosed herein can be linked to a second antibody or antigen-binding fragment thereof that specifically binds to any protein that can serve as a potential target for combination therapy. To generate bispecific or multispecific antibodies, the antibodies or antigen-binding fragments thereof disclosed herein can be linked (e.g., by chemical conjugation, gene fusion, non-covalent association, or other means) to one or more other binding molecules (e.g., additional antibodies, antibody fragments, peptides, or binding mimetics).

[0415] Thus, in another aspect, the present disclosure provides bispecific or multispecific antibodies comprising the antibodies or antigen-binding fragments thereof disclosed herein.

[0416] In certain embodiments, the bispecific or multispecific antibody specifically binds to TIGIT (e.g., human TIGIT) and a second target. In certain embodiments, the bispecific or multispecific antibody comprises a first antigen-binding domain from the antibodies or antigen-binding fragments thereof disclosed herein and a second antigen-binding domain from an antibody against the second target.

[0417] In certain embodiments, the second target is a different immune regulatory receptor.

[0418] Production of antibodies

[0419] The antibodies disclosed herein can be obtained by genetic engineering recombinant techniques. For example, DNA molecules encoding the heavy and light chains of the antibodies disclosed herein can be obtained by chemical synthesis or PCR amplification. The resulting DNA molecules are inserted into an expression vector and then transfected into host cells, such as HEK293 cells or other cells that do not produce immunoglobulins. Then, the transfected host cells are cultured under specific conditions, and these transfected host cells express the antibodies disclosed herein.

[0420] The antigen-binding fragments disclosed herein can be obtained by hydrolysis of a whole antibody molecule. Alternatively, these antigen-binding fragments can be produced directly from recombinant host cells (reviewed in Hudson, Curr. Opin. Immunol. 11:548-557 (1999); Little et al., Immunol. Today, 21:364-370 (2000)). For example, Fab' fragments can be obtained directly from recombinant host cells; and Fab' fragments can be chemically conjugated to form F(ab')2 fragments (Carter et al., Bio / Technology, 10:163-167 (1992)). In addition, Fv, Fab, or F(ab')2 fragments can also be isolated directly from recombinant host cell cultures. Other techniques for preparing these antigen-binding fragments are well known to those of ordinary skill in the art.

[0421] In another aspect, the present disclosure provides an isolated nucleic acid molecule that comprises a nucleotide sequence encoding an antibody or an antigen-binding fragment thereof disclosed herein, or a heavy chain variable region and / or a light chain variable region thereof, or a bispecific or multispecific antibody disclosed herein.

[0422] In certain embodiments, the isolated nucleic acid molecule comprises a first nucleotide sequence and a second nucleotide sequence encoding a heavy chain variable region and a light chain variable region, respectively, of an antibody or an antigen-binding fragment thereof disclosed herein.

[0423] In certain embodiments, the isolated nucleic acid molecule comprises a first nucleotide sequence and a second nucleotide sequence encoding a heavy chain and a light chain, respectively, of an antibody or an antigen-binding fragment thereof disclosed herein.

[0424] In certain embodiments, the isolated nucleic acid molecule comprises different nucleotide sequences encoding different polypeptide chains of a bispecific or multispecific antibody.

[0425] In another aspect, the present disclosure provides a vector (e.g., a cloning vector or an expression vector) that comprises the isolated nucleic acid molecule disclosed herein.

[0426] In certain embodiments, the vector disclosed herein is, for example, a plasmid, a cosmid, a phage, etc. In certain embodiments, the vector can express an antibody or an antigen-binding fragment thereof disclosed herein in a subject (e.g., a mammal (such as a human)).

[0427] In certain embodiments, the vector comprises a first nucleotide sequence and a second nucleotide sequence encoding a heavy chain variable region and a light chain variable region, respectively, of an antibody or an antigen-binding fragment thereof disclosed herein. The first nucleotide sequence and the second nucleotide sequence can be located on the same or different vectors.

[0428] In certain embodiments, the vector comprises a first nucleotide sequence and a second nucleotide sequence encoding the heavy chain and the light chain, respectively, of an antibody or an antigen-binding fragment thereof disclosed herein. The first nucleotide sequence and the second nucleotide sequence may be located on the same or different vectors.

[0429] In certain embodiments, the vector comprises different nucleotide sequences encoding different polypeptide chains of a bispecific or multispecific antibody. The different nucleotide sequences may be located on the same or different vectors.

[0430] In another aspect, the present disclosure provides a host cell comprising or transformed with the isolated nucleic acid molecule disclosed herein or the vector disclosed herein. Such host cells include, but are not limited to, prokaryotic cells (such as Escherichia coli cells) and eukaryotic cells (such as yeast cells, insect cells, plant cells, and animal cells (e.g., mammalian cells such as mouse cells and human cells)).

[0431] In another aspect, provided is a method for producing an antibody or an antigen-binding fragment thereof disclosed herein, or a bispecific or multispecific antibody disclosed herein, the method comprising culturing a host cell comprising the isolated nucleic acid molecule disclosed herein or the vector disclosed herein under conditions permitting the expression of the antibody or an antigen-binding fragment thereof or the bispecific or multispecific antibody, and recovering the antibody or an antigen-binding fragment thereof or the bispecific or multispecific antibody from the culture of the cultured host cell.

[0432] Pharmaceutical composition

[0433] In one aspect, the present disclosure provides a pharmaceutical composition comprising an antibody or an antigen-binding fragment thereof disclosed herein, or an immunoconjugate disclosed herein, a bispecific or multispecific antibody disclosed herein, or an isolated nucleic acid molecule, vector, or host cell disclosed herein, and a pharmaceutically acceptable carrier and / or excipient.

[0434] In certain embodiments, the pharmaceutical composition comprises an antibody or an antigen-binding fragment thereof disclosed herein. In certain embodiments, the pharmaceutical composition comprises an effective amount of an antibody or an antigen-binding fragment thereof disclosed herein. In certain embodiments, the antibody or an antigen-binding fragment thereof is the only active ingredient contained in the pharmaceutical composition.

[0435] In certain embodiments, the pharmaceutical composition comprises an immunoconjugate disclosed herein. In certain embodiments, the pharmaceutical composition comprises an effective amount of an immunoconjugate disclosed herein. In certain embodiments, the immunoconjugate is the only active ingredient contained in the pharmaceutical composition.

[0436] In certain embodiments, the pharmaceutical composition comprises a bispecific or multispecific antibody of the present disclosure. In certain embodiments, the pharmaceutical composition comprises an effective amount of a bispecific or multispecific antibody of the present disclosure. In certain embodiments, the bispecific or multispecific antibody is the only active ingredient contained in the pharmaceutical composition.

[0437] In certain embodiments, the pharmaceutical composition of the present disclosure may further comprise an additional therapeutic agent. In certain embodiments, the additional therapeutic agent is an anti-tumor agent. In certain embodiments, the additional therapeutic agent is an additional immune checkpoint inhibitor, such as an anti-PD-1 antibody, an anti-PD-L1 antibody, an anti-TIM-3 antibody, an anti-LAG-3 antibody, or an anti-CTLA-4 antibody. In certain embodiments, the additional therapeutic agent is a cytotoxic agent, such as an alkylating agent, an anti-mitotic agent, an anti-tumor antibiotic, an anti-metabolite, a topoisomerase inhibitor, a tyrosine kinase inhibitor, or a radionuclide.

[0438] In certain embodiments, the antibody or antigen-binding fragment thereof of the present disclosure, or the immunoconjugate or bispecific or multispecific antibody of the present disclosure and the additional therapeutic agent may be provided as separate components or as components of a single composition. The antibody or antigen-binding fragment thereof of the present disclosure, or the immunoconjugate or bispecific or multispecific antibody of the present disclosure may be used in combination simultaneously, separately, or sequentially with other agents.

[0439] The pharmaceutical composition may be provided in unit dosage forms (i.e., a dose for single administration).

[0440] The pharmaceutical composition may be formulated using one or more pharmaceutically acceptable carriers and / or excipients. The formulation depends on the selected route of administration. For parenteral administration, the pharmaceutical composition is preferably sterile and substantially isotonic and manufactured under GMP conditions. For example, the antibodies disclosed herein may be formulated in an aqueous injection solution, preferably in a physiologically compatible buffer, such as water for injection (WFI), bacteriostatic water for injection (BWFI), sodium chloride solution (e.g., 0.9% (w / v) NaCl), glucose solution (e.g., 5% glucose), surfactant-containing solution (e.g., 0.01% polysorbate 20), pH buffer solution (e.g., phosphate buffer solution), Ringer's solution. The solution may contain formulations such as suspending agents, stabilizers, and / or dispersing agents. Alternatively, the antibody may be in lyophilized form for constitution with a suitable vehicle (e.g., sterile pyrogen-free water) prior to use.

[0441] The pharmaceutical compositions described herein can be used to increase immune cell activation, enhance the immune response, reduce or eliminate TIGIT-mediated immunosuppression, reduce or deplete regulatory T cells, and / or treat conditions such as tumors or infectious diseases.

[0442] Uses and methods

[0443] The antibodies or antigen-binding fragments thereof disclosed herein can specifically bind to TIGIT (e.g., human TIGIT) and block the binding to PVR / CD155, thereby reducing or eliminating TIGIT-mediated immunosuppression. Thus, the antibodies described herein can be used for treatment in a variety of therapeutic applications, including treating diseases associated with immunosuppression, e.g., inhibiting tumor growth and treating infections.

[0444] In one aspect, the present disclosure provides a method of increasing the activation of immune cells (e.g., T cells and / or NK cells) in a subject (e.g., a human) in response to an antigen, the method comprising administering to a subject in need thereof a therapeutically effective amount of an antibody or antigen-binding fragment thereof, an immunoconjugate, a bispecific or multispecific antibody, an isolated nucleic acid molecule, a vector, a host cell, or a pharmaceutical composition disclosed herein. In certain embodiments, the subject has a tumor and the antigen is a tumor antigen. In another embodiment, the subject has an infectious disease, e.g., caused by a pathogen (e.g., a virus, a bacterium, a fungus, or a protozoan), and the antigen is an infectious disease antigen, e.g., on the surface of the pathogen.

[0445] In one aspect, the present disclosure provides a method of enhancing an immune response in a subject (e.g., a human), the method comprising administering to a subject in need thereof a therapeutically effective amount of an antibody or antigen-binding fragment thereof, an immunoconjugate, a bispecific or multispecific antibody, an isolated nucleic acid molecule, a vector, a host cell, or a pharmaceutical composition disclosed herein. In certain embodiments, the subject has a tumor and the immune response against the tumor is enhanced. In another embodiment, the subject has an infectious disease, e.g., caused by a pathogen (e.g., a virus, a bacterium, a fungus, or a protozoan), and the immune response against the pathogen is enhanced. In certain embodiments, the immune response is an antigen-specific T cell response.

[0446] In one aspect, the present disclosure provides methods for reducing or eliminating TIGIT-mediated immunosuppression in a subject (e.g., a human), the method comprising administering to a subject in need thereof a therapeutically effective amount of an antibody or antigen-binding fragment thereof, an immunoconjugate, a bispecific or multispecific antibody, an isolated nucleic acid molecule, a vector, a host cell, or a pharmaceutical composition disclosed herein. In certain embodiments, the subject has a tumor, e.g., in which TIGIT (e.g., TIGIT-mediated signaling or regulatory T cells expressing TIGIT) inhibits an anti-tumor immune response. In another embodiment, the subject has an infectious disease, e.g., caused by a pathogen (e.g., a virus, a bacterium, a fungus, or a protozoan), and in which TIGIT (e.g., TIGIT-mediated signaling or regulatory T cells expressing TIGIT) inhibits an anti-pathogen immune response.

[0447] In one aspect, the present disclosure provides methods for reducing or depleting regulatory T cells in a tumor of a subject (e.g., a human), the method comprising administering to a subject in need thereof a therapeutically effective amount of an antibody or antigen-binding fragment thereof, an immunoconjugate, a bispecific or multispecific antibody, an isolated nucleic acid molecule, a vector, a host cell, or a pharmaceutical composition disclosed herein. In certain embodiments, the subject has a tumor, e.g., in which TIGIT (e.g., TIGIT-mediated signaling or regulatory T cells expressing TIGIT) inhibits an anti-tumor immune response.

[0448] In one aspect, the present disclosure provides methods for treating a tumor in a subject (e.g., a human), the method comprising administering to a subject in need thereof a therapeutically effective amount of an antibody or antigen-binding fragment thereof, an immunoconjugate, a bispecific or multispecific antibody, an isolated nucleic acid molecule, a vector, a host cell, or a pharmaceutical composition disclosed herein. In certain embodiments, the subject has a tumor, e.g., in which TIGIT (e.g., TIGIT-mediated signaling or regulatory T cells expressing TIGIT) inhibits an anti-tumor immune response.

[0449] In one aspect, the present disclosure provides methods for treating an infectious disease in a subject (e.g., a human), the method comprising administering to a subject in need thereof a therapeutically effective amount of an antibody or antigen-binding fragment thereof, an immunoconjugate, a bispecific or multispecific antibody, an isolated nucleic acid molecule, a vector, a host cell, or a pharmaceutical composition disclosed herein. In certain embodiments, the subject has an infectious disease, e.g., caused by a pathogen (e.g., a virus, a bacterium, a fungus, or a protozoan), and in which TIGIT (e.g., TIGIT-mediated signaling or regulatory T cells expressing TIGIT) inhibits an anti-pathogen immune response.

[0450] In another aspect, the present disclosure provides the use of an antibody or antigen-binding fragment thereof, immunoconjugate, bispecific or multispecific antibody, isolated nucleic acid molecule, vector, host cell, or pharmaceutical composition disclosed herein in the manufacture of a medicament for use in: (a) increasing immune cell activation in a subject in response to an antigen; (b) enhancing the immune response in a subject; (c) reducing or eliminating TIGIT-mediated immunosuppression in a subject; (d) reducing or depleting regulatory T cells in a tumor of a subject; (e) treating a tumor of a subject; and / or (f) treating an infectious disease of a subject.

[0451] In another aspect, the present disclosure relates to an antibody or antigen-binding fragment thereof, immunoconjugate, bispecific or multispecific antibody, isolated nucleic acid molecule, vector, host cell, or pharmaceutical composition disclosed herein for use in: (a) increasing immune cell activation in a subject in response to an antigen; (b) enhancing the immune response in a subject; (c) reducing or eliminating TIGIT-mediated immunosuppression in a subject; (d) reducing or depleting regulatory T cells in a tumor of a subject; (e) treating a tumor of a subject; and / or (f) treating an infectious disease of a subject.

[0452] In certain embodiments, tumors involved in the methods or uses of modulating immune function and the methods or uses of treatment described herein include, but are not limited to, solid tumors and hematological malignancies. The tumors can also be metastatic cancer, refractory cancer, or recurrent cancer. Such tumors may or may not express TIGIT or CD155. Antibodies against TIGIT are effective against cancers that do not express TIGIT because inhibiting the interaction of TIGIT with CD155 stimulates an immune response against such cancers. Examples of solid tumors include, but are not limited to, ovarian cancer, endometrial cancer, breast cancer, lung cancer (small cell or non-small cell), colon cancer, prostate cancer, cervical cancer, pancreatic cancer, gastric cancer, esophageal cancer, hepatocellular carcinoma (liver cancer), renal cell carcinoma (kidney cancer), head and neck tumors, mesothelioma, melanoma, sarcoma, and brain tumors (e.g., gliomas, such as glioblastoma). Examples of hematological malignancies include leukemia, lymphoma, and myeloma, including acute myeloid leukemia, adult T-cell leukemia, T-cell large granular lymphocyte leukemia, acute lymphoblastic leukemia, chronic lymphocytic leukemia, chronic myelogenous leukemia, acute monocytic leukemia, Hodgkin lymphoma, non-Hodgkin lymphoma, and multiple myeloma. In certain embodiments, the tumor involves TIGIT-mediated inhibition of the anti-tumor immune response, e.g., via TIGIT-mediated signaling or regulatory T cells expressing TIGIT. In certain embodiments, the tumor comprises one or more of the following: (a) high levels of infiltrating TIGIT-positive T cells and / or NK cells; (b) elevated expression of PVR and / or nectin-2 on tumor cells or tumor-infiltrating myeloid cells.

[0453] In certain embodiments, infectious diseases involved in the methods or uses of modulating immune function and the methods or uses of treatment described herein include, but are not limited to, infections caused by any pathogen (such as a virus, bacterium, fungus, or protozoan). In certain embodiments, the infectious disease involves TIGIT-mediated inhibition of the anti-pathogen immune response, e.g., via TIGIT-mediated signaling or regulatory T cells expressing TIGIT.

[0454] In certain embodiments, in any of the methods or uses for modulating immune function or for treatment described herein, the antibodies, immunoconjugates, or bispecific or multispecific antibodies of the present disclosure can be used alone. Alternatively, the antibodies, immunoconjugates, or bispecific or multispecific antibodies of the present disclosure can be used in combination with additional therapeutic agents. In certain embodiments, the additional therapeutic agent is an anti-tumor agent. In certain embodiments, the additional therapeutic agent is an additional immune checkpoint inhibitor, such as an anti-PD-1 antibody, an anti-PD-L1 antibody, an anti-TIM-3 antibody, an anti-LAG-3 antibody, or an anti-CTLA-4 antibody. In certain embodiments, the additional therapeutic agent is a cytotoxic agent, such as an alkylating agent, an anti-mitotic agent, an anti-tumor antibiotic, an anti-metabolite, a topoisomerase inhibitor, a tyrosine kinase inhibitor, or a radionuclide. In certain embodiments, the antibodies, immunoconjugates, or bispecific or multispecific antibodies of the present disclosure are used in combination with additional therapies (e.g., standard cancer treatments such as surgery, chemotherapy, radiotherapy, targeted therapy, immunotherapy, hormone therapy, gene therapy, or palliative care).

[0455] In certain embodiments, in any of the methods or uses for modulating immune function or for treatment described herein, the antibodies or antigen-binding fragments thereof, immunoconjugates, bispecific or multispecific antibodies, or pharmaceutical compositions of the present disclosure can be formulated into any dosage form known in the medical art, e.g., tablets, pills, suspensions, emulsions, solutions, gels, capsules, powders, granules, elixirs, lozenges, suppositories, injections (including injection solutions, sterile powders for injection, and concentrated solutions for injection), inhalants, sprays, etc. The preferred dosage form depends on the intended route of administration and therapeutic use. One preferred dosage form is an injection. Such an injection can be a sterile injectable solution. Alternatively, for convenience of storage and use, the sterile injectable solution can be prepared as a sterile lyophilized powder (e.g., by vacuum drying or freeze drying).

[0456] In certain embodiments, in any of the methods or uses for modulating immune function or for treatment described herein, the antibodies or antigen-binding fragments thereof, immunoconjugates, bispecific or multispecific antibodies, or pharmaceutical compositions of the present disclosure can be administered by any suitable method known in the art (including but not limited to oral, buccal, sublingual, ocular, topical, parenteral, rectal, intrathecal, intracytoplasmic, inguinal, intravesical, local (e.g., powder, ointment, or drops), or nasal routes). However, for many therapeutic uses, the preferred route of administration / mode is parenteral administration (e.g., intravenous injection or bolus, subcutaneous injection, intraperitoneal injection, intramuscular injection). Those skilled in the art will understand that the route of administration and / or mode will vary depending on the intended purpose. In a preferred embodiment, the antibodies disclosed herein are administered by intravenous injection or bolus.

[0457] In certain embodiments, in any of the methods or uses for modulating immune function and the methods or uses for treatment described herein, the subject is a human. In certain embodiments, the subject has a tumor. In certain embodiments, the tumor comprises one or more of the following: (a) a high level of infiltrating TIGIT-positive T cells and / or NK cells; (b) elevated expression of PVR and / or nectin-2 on tumor cells or tumor-infiltrating myeloid cells.

[0458] In certain embodiments, in any of the methods or uses for modulating immune function and the methods or uses for treatment described herein, the antibody has effector function (e.g., ADCC) or enhanced effector function (e.g., ADCC).

[0459] Examples

[0460] The following examples discuss the generation, characterization, and humanization of monoclonal antibodies against human TIGIT and also provide exemplary methods by which the binding, blocking, ADCC, and tumor growth inhibitory activities of the antibodies described in this application can be determined.

[0461] Unless otherwise indicated, the examples provided below are for illustrative purposes only and are not intended to be limiting. Thus, the present invention should in no way be construed as limited to the following examples, but should be construed to cover any and all variations that become apparent from the teachings provided herein.

[0462] Example 1: Immunization, Single-Cell Sorting, and Sequencing

[0463] Female Balb / c mice were intraperitoneally immunized with recombinant human TIGIT (SEQ ID NO:1, ACROBiosystems, catalog number: TIT-H5254): Each mouse received 50 μg (for primary immunization) or 25 μg every 14 days (for three boosts) of the protein in Freund's complete adjuvant (Sigma-Aldrich) over a 56-day period. Spleen and lymph nodes were harvested on day 60. Single-cell sorting and sequencing of TIGIT-specific antibodies from mouse memory B cells were performed as previously described (von Boehmer L., Liu C., Ackerman S., Gitlin A.D., Wang Q., Gazumyan A., Nussenzweig M.C. Sequencing and cloning of antigen-specific antibodies from mouse memory B cells. Nat. Protoc. 2016;11:1908-1923). Briefly, single-cell suspensions of spleen and lymph nodes were generated, and then total B cells were magnetically separated and stained with fluorescently labeled antibodies. Fluorescently labeled antigen-specific mouse memory B cells were sorted by FACS into lysis buffer in 96-well plates. For each cell, cDNA was generated by two-step reverse transcription (RT) using random primers. Variable heavy and light chain domains were then amplified by nested PCR. The first PCR was performed with a primer mixture annealing to the V(D)J leader sequence and an immunoglobulin constant region reverse primer. The second PCR was performed with a primer annealing to the 5' end of the variable (V) gene and an immunoglobulin nested constant region reverse primer. The PCR products were then purified and sequenced.

[0464] Example 2: Generation of anti-TIGIT chimeric antibodies

[0465] The sequences generated in Example 1 were analyzed, and non-productive and redundant sequences were removed. Full-length chimeric IgG was constructed using paired VH and VL sequences, i.e., the VH and VL gene fragments were cloned into mammalian expression vectors to be in-frame with the human IgG1 heavy chain constant region (SEQ ID NO:69) and κ light chain constant region (SEQ ID NO:70), respectively. HEK293 cells were transfected with the resulting heavy and light chain plasmids. Two days after transfection, the supernatant was harvested. ELISA was performed to detect the presence of anti-TIGIT antibodies in the supernatant. Ten clones listed in Table 1 were confirmed to bind human TIGIT.

[0466] Table 1. Variable domain sequence IDs of the selected chimeric antibodies

[0467]

[0468] Prepare plasmids of the confirmed conjugates and use them to transfect HEK293 cells. The supernatant was collected 4 days after transfection. The chimeric antibody was purified by protein A affinity chromatography and size exclusion chromatography. As positive controls, two anti-TIGIT antibodies 4.1D3 and Hu1217-2-2 were also internally generated using the sequences in the published patents (US20210032328 A1 and WO 2019129261 A1, respectively).

[0469] Example 3: In vitro characterization of anti-TIGIT chimeric antibodies

[0470] Binding of CHO cell lines overexpressing TIGIT and blockade of TIGIT-CD155 interaction

[0471] To determine the cell-binding activity of the chimeric antibody, CHO-K1 cells expressing human and cynomolgus monkey TIGIT were first incubated with the antibodies generated in Example 2 (at a concentration range from 1 pM to 100 nM), and then incubated with a fluorophore-labeled secondary polyclonal antibody against human Fc. To determine the activity of the chimeric antibody in blocking the interaction between TIGIT and CD155, 10 μg / mL of biotinylated CD155-Fc protein (Acrobiosystems) was added to a mixture of the chimeric antibody (at a concentration range from 0.002 nM to 300 nM) and human TIGIT-CHO-K1 cells. The bound CD155-Fc was detected with fluorophore-labeled streptavidin. The binding and blocking activities of the anti-TIGIT chimeric antibodies are summarized in Table 2. Most of the chimeric antibodies, except for TIGIT-52, have similar or better binding and blocking activities compared to the positive controls 4.1D3 and Hu1217-2-2.

[0472] Table 2. Binding and blocking activities of anti-TIGIT chimeric antibodies

[0473]

[0474] Affinity determination by surface plasmon resonance (SPR)

[0475] The binding affinities of the chimeric antibodies to human and cynomolgus macaque TIGIT proteins were determined by surface plasmon resonance (SPR) on a BIAcore T200 instrument (GE Healthcare). The experiment was conducted as follows: The antibodies were captured onto a sensor chip pre-coated with goat anti-human pAb (40 μg / mL) through the interaction between the polyclonal antibody and human Fc. Increasing concentrations (320, 160, 80, 40, 20, 10, 5, 2.5, 1.25 nM) of His-tagged human or cynomolgus macaque TIGIT were passed over the surface of the sensor chip and allowed to bind to the antibody for 100 s, followed by injection of running buffer to allow dissociation of the complex. The association rate (k a ) and dissociation rate (k d ) were calculated based on the association and dissociation curves, and the equilibrium dissociation constant (K D ) was calculated using these rates. The affinity results are summarized in Table 3.

[0476] Table 3. Monovalent binding affinities of anti-TIGIT antibodies

[0477]

[0478]

[0479] TIGIT / CD155 blockade reporter assay

[0480] A reporter assay was performed using a TIGIT / CD155 blocking reporter cell line (GenScript). Briefly, effector cells (NFAT-Luc / Jurkat cell line overexpressing TIGIT) were plated overnight and then incubated with anti-TIGIT antibodies (concentration range from 0.002 nM to 300 nM), followed by addition of CD155 aAPC / CHO-K1 cells. After 6 hours of induction at 37 °C, 5% CO2, Bio-Glo TM luciferase assay reagent was added and luminescence was measured. Among all 10 chimeric antibodies, TIGIT-52, TIGIT-87, and TIGIT-100 showed low blocking activity, while the remaining antibodies showed significant blocking activity ( Figure 1 and Table 4). The dose-response relationship was fitted to a three-parameter dose-response curve using Prism 6 (GraphPad Software, San Diego, CA). Among all chimeric antibodies, TIGIT-3, TIGIT-6, and TIGIT-19 showed comparable or slightly superior blocking activity to 4.1D3 and Hu1217-2-2.

[0481] Table 4. Results of the TIGIT / CD155 blocking reporter assay.

[0482] mAb Minimum value (RLU) Maximum value (RLU) EC50 (nM) TIGIT-3 11194 42758 2.77 TIGIT-6 10879 49765 9.42 TIGIT-15 7720 51896 17.43 TIGIT-18 10358 50641 31.3 TIGIT-19 11140 41602 3.28 TIGIT-52 11784 14166 >100 TIGIT-63 11161 28672 46.81 TIGIT-87 9305 17037 >100 TIGIT-94 9955 59846 92.78 TIGIT-100 4521 11714 >100 4.1D3 12562 44193 9.28 Hu1217-2-2 10478 51680 15.56

[0483] Example 4: Humanization of Anti-TIGIT mAb

[0484] Define the positions of the three heavy-chain CDRs (HC-CDRs) in the VH chain and the three light-chain CDRs (LC-CDRs) in the VL chain according to the Abm numbering system (for HCDR1) and the Kabat numbering system (for HCDR2 and 3, LCDR1-3). The sequences of the CDRs indicated herein are provided in Table 12. Three anti-TIGIT mAbs, namely TIGIT-3, TIGIT-6, and TIGIT-19, were selected for humanization using CDR grafting technology (see, e.g., U.S. Patent No. 5,225,539). Briefly, the variable chain sequences of the murine antibodies were compared with the human heavy-chain and κ-chain germline sequences. The most appropriate human frameworks for constructing the CDR-grafted heavy and light chains were identified (Table 5). First, direct grafting was performed. In cases where the affinity of these directly grafted antibodies was lost, several framework residues were mutated back to their murine counterparts (i.e., back-mutations) to restore the binding affinity of the antibody. At the same time, some CDR residues were mutated to their human counterparts to increase the humanization of the antibody, or to some other residues to remove potential post-translational modification sites, or both. The full-length IgG heavy and light chains were constructed using these humanized VH and VL sequences. Heavy and light chain plasmids were prepared and used to produce IgG from HEK293 cells. The supernatants of the transfected HEK293 cells were collected and SPR assays were performed as described in Example 3. Mutations that did not significantly reduce the binding affinity were retained, while mutations that abolished the binding activity were discarded.

[0485] Table 5. Human Receptor Sequence Accession Numbers

[0486] mAb VH receptor Vκ receptor TIGIT-3 BAC02278 QTX15665 TIGIT-6 QVG74320 ACY78416 TIGIT-19 AXA20212 ABA70776

[0487] Humanization of TIGIT-3

[0488] Four rounds of humanization design were carried out for TIGIT-3. For the humanization of the TIGIT-3 VH sequence (hereinafter referred to as 3VH), several back mutations were introduced into the directly transplanted sequence to generate the humanized VH sequence of 3VH3 (SEQ ID NO:22). According to Table 6, the pairing of 3VH3 with the mouse VL sequence (hereinafter referred to as 3VL) does not affect the binding affinity (Table 6, SPR experiment 1). The germline mutations of changing several mouse amino acid residues to their germline counterparts (i.e., D54S and P61A in HCDR2 (3VH3.M4, SEQ ID NO:23)) further increased the sequence humanization and did not reduce the binding affinity for human TIGIT (Table 6, SPR experiment 2). The sequence of 3VL1 (SEQ ID NO:24) was prepared by directly transplanting the mouse 3VL CDR onto the Vκ receptor. Pairing it with the humanized 3VH3 resulted in a ~100-fold decrease in affinity. On the other hand, germline mutations in LCDR1 (i.e., 3VL1.M1, SEQ ID NO:25) and LCDR2 (i.e., 3VL1.M3, SEQ ID NO:26 and 3VL1.M4, SEQ ID NO:27) into 3VL1 did not further significantly reduce the binding affinity (Table 6, SPR experiment 3). Therefore, the M1 and M4 mutations were combined to further increase the humanization of the VL sequence. At the same time, back mutations were also introduced into 3VL1 to generate the sequences of 3VL4.M6 (SEQ ID NO:28) and 3VL5.M6 (SEQ ID NO:29). These humanized VLs were paired with 3VH3.M4. The binding affinity for human TIGIT was restored, with the affinity decrease as little as 2-fold (Table 6, SPR experiment 4).

[0489] Table 6. Binding Affinity of Engineered TIGIT-3 Antibodies

[0490]

[0491]

[0492] Humanization of TIGIT-6

[0493] Two rounds of humanization design were carried out for TIGIT-6. For the humanization of the TIGIT-6 VH sequence (hereinafter referred to as 6VH), several back mutations were introduced into the directly transplanted sequence to generate humanized VH sequences of 6VH5 (SEQ ID NO:30) and 6VH6 (SEQ ID NO:31). The mouse 6VL CDR was directly transplanted onto the Vκ acceptor to obtain the sequence of 6VL1 (SEQ ID NO:32). According to Table 7, pairing of 6VH5 or 6VH6 with the 6VL1 sequence did not significantly affect the binding affinity (SPR experiment 1). Germline mutations in HCDR1 (6VH6.M1, SEQ ID NO:33), HCDR2 (6VH6.M3, SEQ ID NO:34) and LCDR1 (6VL1.M1, SEQ ID NO:35) further increased the humanization of the sequence without significantly reducing the binding affinity to human TIGIT (Table 7, SPR experiment 1). To remove the potential asparagine deamidation Asn-Gly motif in the HCDR2 of 6VH6.M3, N55Q or G56A mutations (6VH6.M4, SEQ ID NO:36; and 6VH6.M5, SEQ ID NO:37) were also constructed. The germline mutations designed in the HCDR1 of 6VH6.M1 were combined with 6VH6.M4 and 6VH6.M5 to further increase the humanization of the VH sequence, generating the sequences of 6VH6.M6 (SEQ ID NO:38) and 6VH6.M7 (SEQ ID NO:39). The binding affinities of these clones were measured and no significant loss of affinity was observed (Table 7, SPR experiment 2).

[0494] Table 7. Humanization of TIGIT-6

[0495]

[0496]

[0497] Humanization of TIGIT-19

[0498] Two rounds of humanization design were carried out for TIGIT-19. For the humanization of the TIGIT-19 VH sequence (hereinafter referred to as 19VH), several back mutations were introduced into the directly transplanted sequence to generate the humanized VH sequence of 19VH4 (SEQ ID NO: 40). The mouse 19VL CDR was directly transplanted onto the Vκ acceptor to obtain the sequence of 19VL1 (SEQ ID NO: 41). According to Table 8, pairing the 19VH4 and 19VL1 sequences slightly improved the binding affinity (about 4-fold). Germline mutations in LCDR2 (19VL1.M4, SEQ ID NO: 42) did not change the binding affinity for human TIGIT; while additional germline mutations in LCDR1 (19VL1.M5, SEQ ID NO: 43; 19VL1.M6, SEQ ID NO: 44; and 19VL1.M7, SEQ ID NO: 45) slightly reduced the binding affinity for human TIGIT (Table 8, SPR experiment 2). Germline mutations were made in HCDR to obtain the sequences of 19VH4.M4 (SEQ ID NO: 46), 19VH4.M5 (SEQ ID NO: 47), 19VH4.M6 (SEQ ID NO: 48), and 19VH4.M7 (SEQ ID NO: 49). Compared with 19VH4, the binding affinity of these germline clones was also slightly reduced. To remove the potentially acid-labile Asp-Pro motif in HCDR2, the P53A mutation was introduced into 19VH4.M6 and 19VH4.M7, generating the sequences of 19VH4.M9 (SEQ ID NO: 50) and 19VH4.M10 (SEQ ID NO: 51). The binding affinity of 19VH4.M9 was comparable to that of 19VH4.M6 (Table 8, SPR experiment 2), indicating that the P53A mutation did not reduce the binding affinity.

[0499] Table 8. Humanization of TIGIT-19

[0500]

[0501]

[0502] Example 5: In vitro characterization of humanized anti-TIGIT antibodies

[0503] Select and generate several humanized antibodies as described in Example 2. Purified antibodies were characterized in vitro using the following assays.

[0504] Affinity determination by SPR

[0505] As described in Example 3, the binding affinity of the humanized antibodies to human and cynomolgus monkey TIGIT proteins was determined by SPR. The SPR sensorgrams are shown in Figure 2, and the affinity results are summarized in Table 9. For all anti-TIGIT antibodies, there is at least one humanized antibody that retains the human TIGIT binding affinity. However, for TIGIT-3, the monovalent cynomolgus monkey TIGIT binding affinity is significantly reduced. For TIGIT-6, the monovalent cynomolgus monkey TIGIT binding affinity is much lower than the human TIGIT binding affinity for both the mouse antibody and the humanized antibody. The same is true for Hu1217-2-2 and 4.1D3.

[0506]

[0507] Binding of CHO cell lines overexpressing TIGIT and blockade of TIGIT-CD155 interaction

[0508] To evaluate the cumulative strength of the bivalent binding interaction with both human and cynomolgus monkey TIGIT, the EC50 values of the antibodies binding to the cell line overexpressing TIGIT were determined by FACS as described in Example 3. The activity of the antibodies in blocking the interaction between human TIGIT and CD155 was performed as described in Example 3. The binding and blocking activities of the chimeric and humanized anti-TIGIT antibodies are summarized in Table 10. For all anti-TIGIT antibodies, there is at least one humanized antibody that retains the human and cynomolgus monkey TIGIT cell binding activity and the human CD155 blocking activity. Most of the chimeric antibodies and humanized antibodies showed binding to the human and cynomolgus monkey TIGIT overexpressing cell lines with similar binding EC50 values, except that huTIGIT-6-4 bound to the cynomolgus monkey TIGIT overexpressing cell line with an EC50 value more than 10-fold that of the EC50 value for binding to the human TIGIT overexpressing cell line. The chimeric and humanized TIGIT-3, TIGIT-6, and TIGIT-19 antibodies all showed significant CD155 blocking activity, especially TIGIT-19, which showed better blocking activity compared to Hu1217-2-2 and 4.1D3.

[0509] Table 10. Binding and blocking activities of chimeric and humanized anti-TIGIT antibodies

[0510]

[0511] TIGIT / CD155 blockade reporter assay

[0512] The TIGIT / CD155 blockade reporter assay was performed using the chimeric and humanized antibodies as described in Example 3. As can be seen from Figure 3 and Table 11, the humanized antibodies showed similar functional activities to the chimeric antibodies. The humanized TIGIT-3, TIGIT-6, and TIGIT-19 antibodies all showed significant potencies, especially the humanized TIGIT-19 antibody, which showed slightly better potency compared to Hu1217-2-2 and 4.1D3, consistent with the results of the CD155 blockade assay shown above.

[0513] Table 11. Results of the TIGIT / CD155 blockade reporter assay for chimeric and humanized antibodies.

[0514] mAb Minimum value (RLU) Maximum value (RLU) EC50 (nM) TIGIT-3 55769 148160 2.10 huTIGIT-3-1 54393 152061 4.92 TIGIT-6 51389 138747 4.90 huTIGIT-6-1 51180 131330 9.10 huTIGIT-6-2 49833 128550 9.03 huTIGIT-6-3 49371 135116 11.10 huTIGIT-6-4 46792 128189 14.84 TIGIT-19 47576 129732 2.75 huTIGIT-19-1 53916 143724 2.05 huTIGIT-19-2 55244 155389 2.39 huTIGIT-19-3 53730 141701 2.65 huTIGIT-19-4 51260 148216 4.28 Hu1217-2-2 52926 163113 11.10 4.1D3 55332 142067 9.69

[0515] Activation of CMV-specific human T cells by chimeric and humanized anti-TIGIT antibodies

[0516] The functional activities of the anti-TIGIT antibodies were further evaluated using naturally-derived human cytomegalovirus (CMV)-specific T cells. Briefly, PBMCs from HLA-A*02:01-positive healthy donors were stimulated for one week with 2 μg / mL of the nonamer peptide 495 NLVPMVATV 503 (residues 495 - 503 of CMV matrix protein pp65; hereinafter referred to as CMVpp65 495-503 peptide) in AIM-V with 10% FBS, which was synthesized by GenScript. After stimulation, cytotoxic T lymphocytes were enriched using a CD8+ T cell isolation kit (Miltenyi Biotech, catalog number: 130-096-495). CMV-specific T cells proliferated and accounted for >20% of CD8+ T cells. More than 50% of CD8+ T cells expressed TIGIT. The TIGIT expression level was also increased 10-fold compared to unstimulated T cells. The purified T cells were used as effector cells and incubated overnight in AIM-V with 10% FBS with HLA-A*02:01-positive HepG2 cells (these cells were pulsed with pp65 peptide (5 μg / mL, >4 hours)) at an effector-to-target cell ratio of approximately 1:4 in the presence or absence (media only) of anti-TIGIT antibodies or isotype controls. As shown in Figure 4, all anti-TIGIT antibodies promoted IFN-γ secretion in a dose-dependent manner, indicating that all of these antibodies are functional.

[0517] ADCC effector function of chimeric and humanized anti-TIGIT antibodies

[0518] TIGIT is constitutively expressed by regulatory T cells (Tregs). Tregs show a higher proportion of TIGIT+ cells and a higher number of TIGIT receptors / cell than other immune populations (Preillon J. et al. Restoration of T-cell effector function, eepletion of Tregs, and direct killing of tumor cells: the multiple mechanisms of action of a-TIGIT antagonist antibodies. Mol Cancer Ther. 2021:20(1):121-131). Therefore, we measured the ability of anti-TIGIT mAbs to induce direct killing of Tregs by flow cytometry-based antibody-dependent cell cytotoxicity (ADCC) assays. Briefly, human PBMCs from healthy donors were stimulated with PHL-A (1 μg / mL, 72 h) to upregulate TIGIT expression. The activated PBMCs were used as target cells. An effector cell line, NK92-CD16aVV cells, was internally generated by transfecting NK92 cells (ATCC) with a CD16V158 (V158 allele) expression plasmid. Effector cells were co-cultured with the aforementioned PBMC target cells at an effector-to-target cell ratio of 1:1 for 48 h in the absence (media only) or presence of anti-TIGIT antibodies (30 μg / mL) or Hu1217-2-2 / IgG1mf (Hu1217-2-2 antibody with an engineered Fc with no effector function, patent number WO 2019129261A1) or isotype control (30 μg / mL) or positive control anti-CD3 antibody Hu38E4 (5 μg / mL, Biolegend). Compared with Hu1217-2-2 / IgG1mf and human IgG1 isotype control, all anti-TIGIT antibodies could cause a moderate reduction of Treg cells via ADCC. However, no significant killing of total T cells or CD8+ T cells or FoxP3-CD4+ T cells was observed (Figure 5).

[0519] Example 6: In Vivo Efficacy of Humanized Anti-TIGIT Antibodies

[0520] The in vivo efficacy of anti-TIGIT antibodies was investigated in human TIGIT knock-in Balb / c mice using a syngeneic CT26 tumor model. Briefly, CT26 tumor cells were cultured and 5×10 5cells. Tumor size was measured using calipers, and tumor volume was calculated as length × width × width / 2. When the average tumor volume reached approximately 100 mm 3 the mice were randomly divided into groups of 5 or 6 mice and treated with the antibody. The test article was administered intraperitoneally at 0.4 mg / kg once every 4 days. Body weight was measured throughout the study. When the tumor volume reached 2000 mm 3 or when the study ended (20 days after treatment), the animals were sacrificed. As Figure 6a shown, even at suboptimal doses, the anti-TIGIT antibodies inhibited tumor growth to some extent compared to the isotype and vehicle controls, especially huTIGIT-6-2, which showed the highest tumor growth inhibition. The other 3 humanized antibodies also showed significant tumor growth inhibitory activity. There were no signs of weight loss throughout the study ( Figure 6b ).

[0521] Sequence

[0522] Table 12

[0523]

[0524]

[0525]

[0526]

[0527]

[0528]

[0529]

[0530]

[0531]

[0532]

[0533]

[0534]

[0535]

[0536]

[0537]

[0538]

[0539]

Claims

1. An antibody or antigen-binding fragment thereof that binds to TIGIT, said antibody or antigen-binding fragment comprising: (i) An HCDR1 comprising a sequence containing SEQ ID NO: 84-86, 98-100, 71, 118, 124, 130, 136, 142, 148 or 154; (ii) An HCDR2 comprising a sequence containing SEQ ID NO: 87-91, 101-107, 72-74, 119, 125, 131, 137, 143, 149 or 155; (iii) An HCDR3 comprising a sequence containing SEQ ID NO: 92, 108, 75, 120, 126, 132, 138, 144, 150 or 156; (iv) An LCDR1 comprising a sequence containing SEQ ID NO: 93-95, 109-113, 76-78, 121, 127, 133, 139, 145, 151 or 157; (v) An LCDR2 comprising a sequence containing SEQ ID NO: 96, 114-116, 79-82, 122, 128, 134, 140, 146, 152, or 158; and (vi) An LCDR3 comprising a sequence containing SEQ ID NO: 97, 117, 83, 123, 129, 135, 141, 147, 153 or 159.

2. The antibody or antigen-binding fragment thereof according to claim 1, said antibody or antigen-binding fragment comprising: (i) An HCDR1 comprising a sequence containing GYTX1TENX2MH (SEQ ID NO: 86), wherein X1 is I or F, and X2 is T or A; (ii) An HCDR2 comprising a sequence containing GINPNX3X4GTSYX5QX6FX7G (SEQ ID NO: 91), wherein X3 is N or Q, X4 is G or A, X5 is N or S, X6 is Q or K, and X7 is K or Q; (iii) An HCDR3 comprising a sequence containing SEQ ID NO: 92; (iv) An LCDR1 comprising a sequence containing X8ASQDX9KTALA (SEQ ID NO: 95), wherein X8 is K or Q, and X9 is V or I; (v) An LCDR2 comprising a sequence containing SEQ ID NO: 96; and (vi) An LCDR3 comprising a sequence containing SEQ ID NO: 97; Preferably, said HCDR1 comprises a sequence of SEQ ID NO: 84 or 85; Preferably, said HCDR2 comprises a sequence of SEQ ID NO: 87, 88, 89 or 90; Preferably, said LCDR1 comprises a sequence of SEQ ID NO: 93 or 94.

3. The antibody or antigen-binding fragment thereof according to claim 2, said antibody or antigen-binding fragment comprising: (1) HCDR1, HCDR2, and HCDR3 having the amino acid sequences of SEQ ID NO:84, 87, and 92, respectively; and LCDR1, LCDR2, and LCDR3 having the amino acid sequences of SEQ ID NO:93, 96, and 97, respectively; (2) HCDR1, HCDR2, and HCDR3 having the following amino acid sequences: (a) SEQ ID NO:85, 87, and 92, respectively; or (b) SEQ ID NO:84, 88, and 92, respectively; or (c) SEQ ID NO:84, 89, and 92, respectively; and LCDR1, LCDR2, and LCDR3 having the amino acid sequences of SEQ ID NO:93, 96, and 97, respectively; or, (3) HCDR1, HCDR2, and HCDR3 having the following amino acid sequences: (a) SEQ ID NO:84, 87, and 92, respectively; or (b) SEQ ID NO:84, 88, and 92, respectively; or (c) SEQ ID NO:84, 89, and 92, respectively; or (d) SEQ ID NO:84, 90, and 92, respectively; or (e) SEQ ID NO:85, 89, and 92, respectively; or (f) SEQ ID NO:85, 90, and 92, respectively; and LCDR1, LCDR2, and LCDR3 having the amino acid sequences of SEQ ID NO:94, 96, and 97, respectively.

4. The antibody or antigen-binding fragment thereof according to claim 2 or 3, wherein the antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein: The VH comprises the sequence of SEQ ID NO:4 or an amino acid sequence having at least 80% sequence identity therewith; and / or the VL comprises the sequence of SEQ ID NO:5 or an amino acid sequence having at least 80% sequence identity therewith; Preferably, the VH comprises the sequence of SEQ ID NO:4; and / or the VL comprises the sequence of SEQ ID NO:

5.

5. The antibody or antigen-binding fragment thereof according to claim 2 or 3, wherein the antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein: The VH comprises a framework region (FR) derived from the human immunoglobulin heavy chain variable region sequence QVG74320 of GenBank; and / or the VL comprises a framework region (FR) derived from the human immunoglobulin light chain variable region sequence ACY78416 of GenBank; Preferably, the VH comprises the sequence of SEQ ID NO:30, 31, 33, 34, 36, 37, 38, or 39 or an amino acid sequence having at least 80% sequence identity therewith; Preferably, the VL comprises the sequence of SEQ ID NO:32 or 35 or an amino acid sequence having at least 80% sequence identity therewith.

6. The antibody or antigen-binding fragment thereof according to claim 5, wherein: (1) The VH comprises the sequence of SEQ ID NO:30, 31, 33, 34, or 36 or an amino acid sequence having at least 80% sequence identity therewith; and / or the VL comprises the sequence of SEQ ID NO:32 or an amino acid sequence having at least 80% sequence identity therewith; or (2) The VH contains the sequence of SEQ ID NO: 31, 34, 36, 37, 38 or 39 or an amino acid sequence having at least 80% sequence identity therewith; and / or the VL contains the sequence of SEQ ID NO: 35 or an amino acid sequence having at least 80% sequence identity therewith; Preferably, (a) the VH contains the sequence of SEQ ID NO: 36; and / or the VL contains the sequence of SEQ ID NO: 35; (b) the VH contains the sequence of SEQ ID NO: 37; and / or the VL contains the sequence of SEQ ID NO: 35; (c) the VH contains the sequence of SEQ ID NO: 38; and / or the VL contains the sequence of SEQ ID NO: 35; or (d) the VH contains the sequence of SEQ ID NO: 39; and / or the VL contains the sequence of SEQ ID NO:

35.

7. The antibody or antigen-binding fragment thereof according to claim 1, wherein the antibody or antigen-binding fragment thereof comprises: (i) HCDR1 containing the sequence of GYX1FX2RYSMY (SEQ ID NO: 100), wherein X1 is A or T and X2 is S or T; (ii) HCDR2 containing the sequence of FIDX3YX4GGSTYX5QX6FX7G (SEQ ID NO: 107), wherein X3 is P or A, X4 is N or S, X5 is N or A, X6 is R or K, and X7 is R or Q; (iii) HCDR3 containing the sequence of SEQ ID NO: 108; (iv) Comprising RX8SX9X 10 IYX 11 LCDR1 having the sequence of YLS (SEQ ID NO:113), wherein X8 is P or A, X9 is E or Q, X 10 is N or S, X 11 is T or S; (v) containing NAKX 12 LPX 13 (SEQ ID NO:116) of LCDR2, where X 12 is T or S, X 13 is E or S; and (vi) LCDR3 containing the sequence of SEQ ID NO: 117; Preferably, the HCDR1 contains the sequence of SEQ ID NO: 98 or 99; Preferably, the HCDR2 contains the sequence of SEQ ID NO: 101, 102, 103, 104, 105 or 106; Preferably, the LCDR1 contains the sequence of SEQ ID NO: 109, 110, 111 or 112; Preferably, the LCDR2 contains the sequence of SEQ ID NO: 114 or 115.

8. The antibody or antigen-binding fragment thereof according to claim 7, wherein the antibody or antigen-binding fragment thereof comprises: (1) HCDR1, HCDR2 and HCDR3 containing the amino acid sequences of SEQ ID NO: 98, 101 and 108 respectively; and LCDR1, LCDR2 and LCDR3 containing the amino acid sequences of SEQ ID NO: 109, 114 and 117 respectively; (2) HCDR1, HCDR2, and HCDR3 having the amino acid sequences of SEQ ID NO:98, 101, and 108, respectively; and LCDR1, LCDR2, and LCDR3 having the following amino acid sequences: (a) SEQ ID NO:109, 115, and 117, respectively; or (b) SEQ ID NO:110, 115, and 117, respectively; or (c) SEQ ID NO:111, 115, and 117, respectively; or (d) SEQ ID NO:112, 115, and 117, respectively; (3) HCDR1, HCDR2, and HCDR3 having the following amino acid sequences: (a) SEQ ID NO:98, 102, and 108, respectively; or (b) SEQ ID NO:98, 103, and 108, respectively; or (c) SEQ ID NO:99, 102, and 108, respectively; or (d) SEQ ID NO:99, 104, and 108, respectively; or (e) SEQ ID NO:99, 105, and 108, respectively; and LCDR1, LCDR2, and LCDR3 having the amino acid sequences of SEQ ID NO:109, 114, and 117, respectively; (4) HCDR1, HCDR2, and HCDR3 having the amino acid sequences of SEQ ID NO:99, 105, and 108, respectively; and LCDR1, LCDR2, and LCDR3 having the following amino acid sequences: (a) SEQ ID NO:109, 115, and 117, respectively; or (b) SEQ ID NO:112, 115, and 117, respectively; or, (5) HCDR1, HCDR2, and HCDR3 having the amino acid sequences of SEQ ID NO:99, 106, and 108, respectively; and LCDR1, LCDR2, and LCDR3 having the following amino acid sequences: (a) SEQ ID NO:109, 115, and 117, respectively; or (b) SEQ ID NO:112, 115, and 117, respectively.

9. The antibody or antigen-binding fragment thereof according to claim 7 or 8, wherein the antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein: The VH comprises the sequence of SEQ ID NO:10 or an amino acid sequence having at least 80% sequence identity therewith; and / or the VL comprises the sequence of SEQ ID NO:11 or an amino acid sequence having at least 80% sequence identity therewith; Preferably, the VH comprises the sequence of SEQ ID NO:10; and / or the VL comprises the sequence of SEQ ID NO:

11.

10. The antibody or antigen-binding fragment thereof according to claim 7 or 8, wherein the antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein: The VH comprises the framework region (FR) of the human immunoglobulin heavy chain variable region sequence AXA20212 from GenBank; and / or the VL comprises the framework region (FR) of the human immunoglobulin light chain variable region sequence ABA70776 from GenBank; Preferably, the VH comprises the sequence of SEQ ID NO:40, 46, 47, 48, 49, 50, or 51 or an amino acid sequence having at least 80% sequence identity therewith; Preferably, the VL comprises the sequence of SEQ ID NO: 41, 42, 43, 44 or 45 or an amino acid sequence having at least 80% sequence identity therewith.

11. The antibody or antigen-binding fragment thereof according to claim 10, wherein: (1) the VH comprises the sequence of SEQ ID NO: 40 or an amino acid sequence having at least 80% sequence identity therewith; and / or the VL comprises the sequence of SEQ ID NO: 41, 42, 43, 44 or 45 or an amino acid sequence having at least 80% sequence identity therewith; or, (2) the VH comprises the sequence of SEQ ID NO: 46, 47, 48, 49 or 50 or an amino acid sequence having at least 80% sequence identity therewith; and / or the VL comprises the sequence of SEQ ID NO: 41 or an amino acid sequence having at least 80% sequence identity therewith; or, (3) the VH comprises the sequence of SEQ ID NO: 50 or an amino acid sequence having at least 80% sequence identity therewith; and / or the VL comprises the sequence of SEQ ID NO: 42 or 45 or an amino acid sequence having at least 80% sequence identity therewith; or, (4) the VH comprises the sequence of SEQ ID NO: 51 or an amino acid sequence having at least 80% sequence identity therewith; and / or the VL comprises the sequence of SEQ ID NO: 42 or 45 or an amino acid sequence having at least 80% sequence identity therewith; Preferably, (a) the VH comprises the sequence of SEQ ID NO: 50; and / or the VL comprises the sequence of SEQ ID NO: 42; (b) the VH comprises the sequence of SEQ ID NO: 50; and / or the VL comprises the sequence of SEQ ID NO: 45; (c) the VH comprises the sequence of SEQ ID NO: 51; and / or the VL comprises the sequence of SEQ ID NO: 42; or (d) the VH comprises the sequence of SEQ ID NO: 51; and / or the VL comprises the sequence of SEQ ID NO:

45.

12. The antibody or antigen-binding fragment thereof according to claim 1, the antibody or antigen-binding fragment thereof comprising: (i) an HCDR1 containing the sequence of SEQ ID NO: 71; (ii) an HCDR2 containing the sequence of TIKSX1GGSTNLX2DSVKG (SEQ ID NO: 74), wherein X1 is D or S and X2 is P or A; (iii) an HCDR3 containing the sequence of SEQ ID NO: 75; (iv) an LCDR1 containing the sequence of X3ASQDX4KTAX5A (SEQ ID NO: 78), wherein X3 is K or R, X4 is V or I, and X5 is V or L; (v) an LCDR2 containing the sequence of WX6STRX7X8 (SEQ ID NO: 82), wherein X6 is S or A, X7 is H or Q, and X8 is T or S; and (vi) An LCDR3 containing the sequence of SEQ ID NO:83; Preferably, the HCDR2 contains the sequence of SEQ ID NO:72 or 73; Preferably, the LCDR1 contains the sequence of SEQ ID NO:76 or 77; Preferably, the LCDR2 contains the sequence of SEQ ID NO:79, 80 or 81.

13. The antibody or antigen-binding fragment thereof according to claim 12, wherein the antibody or antigen-binding fragment thereof comprises: (1) HCDR1, HCDR2 and HCDR3 containing the amino acid sequences of SEQ ID NO:71, 72 and 75 respectively; and LCDR1, LCDR2 and LCDR3 containing the amino acid sequences of SEQ ID NO:76, 79 and 83 respectively; or, (2) HCDR1, HCDR2 and HCDR3 containing the amino acid sequences of SEQ ID NO:71, 73 and 75 respectively; and LCDR1, LCDR2 and LCDR3 containing the amino acid sequences of SEQ ID NO:76, 79 and 83 respectively; or, (3) HCDR1, HCDR2 and HCDR3 containing the amino acid sequences of SEQ ID NO:71, 72 and 75; and LCDR1, LCDR2 and LCDR3 containing the following amino acid sequences: (a) SEQ ID NO:76, 79 and 83 respectively; or (b) SEQ ID NO:77, 79 and 83 respectively; or (c) SEQ ID NO:76, 80 and 83 respectively; or (d) SEQ ID NO:76, 81 and 83 respectively; or, (4) HCDR1, HCDR2 and HCDR3 containing the amino acid sequences of SEQ ID NO:71, 73 and 75 respectively; and LCDR1, LCDR2 and LCDR3 containing the amino acid sequences of SEQ ID NO:77, 81 and 83 respectively.

14. The antibody or antigen-binding fragment thereof according to claim 12 or 13, wherein the antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein: The VH contains the sequence of SEQ ID NO:2 or an amino acid sequence having at least 80% sequence identity thereto; and / or the VL contains the sequence of SEQ ID NO:3 or an amino acid sequence having at least 80% sequence identity thereto; Preferably, the VH contains the sequence of SEQ ID NO:2; and / or the VL contains the sequence of SEQ ID NO:

3.

15. The antibody or antigen-binding fragment thereof according to claim 12 or 13, wherein the antibody or antigen-binding fragment thereof comprises a heavy-chain variable region (VH) and a light-chain variable region (VL), wherein: The VH contains the framework region (FR) of the human immunoglobulin heavy chain variable region sequence BAC02278 from GenBank; and / or the VL contains the framework region (FR) of the human immunoglobulin light chain variable region sequence QTX15665 from GenBank; Preferably, the VH contains the sequence of SEQ ID NO:22 or 23 or an amino acid sequence having at least 80% sequence identity thereto; Preferably, the VL contains the sequence of SEQ ID NO:24, 25, 26, 27, 28 or 29 or an amino acid sequence having at least 80% sequence identity thereto.

16. The antibody or antigen-binding fragment thereof according to claim 15, wherein: (1) The VH comprises the sequence of SEQ ID NO: 22 or 23 or an amino acid sequence having at least 80% sequence identity therewith; and / or the VL comprises the sequence of SEQ ID NO: 3 or an amino acid sequence having at least 80% sequence identity therewith; or, (2) The VH comprises the sequence of SEQ ID NO: 22 or an amino acid sequence having at least 80% sequence identity therewith; and / or the VL comprises the sequence of SEQ ID NO: 24, 25, 26 or 27 or an amino acid sequence having at least 80% sequence identity therewith; or, (3) The VH comprises the sequence of SEQ ID NO: 23 or an amino acid sequence having at least 80% sequence identity therewith; and / or the VL comprises the sequence of SEQ ID NO: 28 or 29 or an amino acid sequence having at least 80% sequence identity therewith; Preferably, the VH comprises the sequence of SEQ ID NO: 23; and / or the VL comprises the sequence of SEQ ID NO:

28.

17. The antibody or antigen-binding fragment thereof according to claim 1, wherein the antibody or antigen-binding fragment thereof comprises: (1) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 respectively containing the amino acid sequences of SEQ ID NO: 118, 119, 120, 121, 122 and 123; Preferably, the VH comprises the sequence of SEQ ID NO: 6 or an amino acid sequence having at least 80% sequence identity therewith; and / or the VL comprises the sequence of SEQ ID NO: 7 or an amino acid sequence having at least 80% sequence identity therewith; or, (2) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 respectively containing the amino acid sequences of SEQ ID NO: 124, 125, 126, 127, 128 and 129; Preferably, the VH comprises the sequence of SEQ ID NO: 8 or an amino acid sequence having at least 80% sequence identity therewith; and / or the VL comprises the sequence of SEQ ID NO: 9 or an amino acid sequence having at least 80% sequence identity therewith; or, (3) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 respectively containing the amino acid sequences of SEQ ID NO: 130, 131, 132, 133, 134 and 135; Preferably, the VH comprises the sequence of SEQ ID NO: 12 or an amino acid sequence having at least 80% sequence identity therewith; and / or the VL comprises the sequence of SEQ ID NO: 13 or an amino acid sequence having at least 80% sequence identity therewith; or, (4) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 having the amino acid sequences set forth in SEQ ID NO: 136, 137, 138, 139, 140, and 141, respectively; Preferably, VH comprises the sequence of SEQ ID NO: 14 or an amino acid sequence having at least 80% sequence identity thereto; and / or VL comprises the sequence of SEQ ID NO: 15 or an amino acid sequence having at least 80% sequence identity thereto; or, (5) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 having the amino acid sequences set forth in SEQ ID NO: 142, 143, 144, 145, 146, and 147, respectively; Preferably, VH comprises the sequence of SEQ ID NO: 16 or an amino acid sequence having at least 80% sequence identity thereto; and / or VL comprises the sequence of SEQ ID NO: 17 or an amino acid sequence having at least 80% sequence identity thereto; or, (6) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 having the amino acid sequences set forth in SEQ ID NO: 148, 149, 150, 151, 152, and 153, respectively; Preferably, VH comprises the sequence of SEQ ID NO: 18 or an amino acid sequence having at least 80% sequence identity thereto; and / or VL comprises the sequence of SEQ ID NO: 19 or an amino acid sequence having at least 80% sequence identity thereto; or, (7) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 having the amino acid sequences set forth in SEQ ID NO: 154, 155, 156, 157, 158, and 159, respectively; Preferably, VH comprises the sequence of SEQ ID NO: 20 or an amino acid sequence having at least 80% sequence identity thereto; and / or VL comprises the sequence of SEQ ID NO: 21 or an amino acid sequence having at least 80% sequence identity thereto.

18. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 17, wherein the antibody or antigen-binding fragment thereof further comprises: a heavy chain constant region (CH) containing an amino acid sequence derived from a human immunoglobulin heavy chain constant region; Preferably, the heavy chain constant region is an IgG heavy chain constant region, such as an IgG1, IgG2, IgG3, or IgG4 heavy chain constant region; preferably, the heavy chain constant region comprises the amino acid sequence of SEQ ID NO: 69; Preferably, the heavy chain constant region has effector function (e.g., ADCC) or enhanced effector function (e.g., ADCC); Preferably, the antibody or antigen-binding fragment thereof further comprises: a light chain constant region (CL) containing an amino acid sequence derived from a human immunoglobulin light chain constant region; Preferably, the light chain constant region is a κ light chain constant region; preferably, the light chain constant region comprises the amino acid sequence of SEQ ID NO:

70.

19. The antibody or antigen-binding fragment thereof according to claim 18, wherein the antibody or antigen-binding fragment thereof comprises: a heavy chain comprising the sequence of SEQ ID NO: 56, 58, 59, 60 or 61 or an amino acid sequence having at least 80% sequence identity thereto; and / or a light chain comprising the sequence of SEQ ID NO: 57 or 62 or an amino acid sequence having at least 80% sequence identity thereto; Preferably, the antibody or antigen-binding fragment thereof comprises: (1) a heavy chain comprising the sequence of SEQ ID NO: 56 or an amino acid sequence having at least 80% sequence identity thereto; and / or a light chain comprising the sequence of SEQ ID NO: 57 or an amino acid sequence having at least 80% sequence identity thereto; or, (2) a heavy chain comprising the sequence of SEQ ID NO: 58, 59, 60 or 61 or an amino acid sequence having at least 80% sequence identity thereto; and / or a light chain comprising the sequence of SEQ ID NO: 62 or an amino acid sequence having at least 80% sequence identity thereto.

20. The antibody or antigen-binding fragment thereof according to claim 18, wherein the antibody or antigen-binding fragment thereof comprises: a heavy chain comprising the sequence of SEQ ID NO: 63, 65 or 66 or an amino acid sequence having at least 80% sequence identity thereto; and / or a light chain comprising the sequence of SEQ ID NO: 64, 67 or 68 or an amino acid sequence having at least 80% sequence identity thereto; Preferably, the antibody or antigen-binding fragment thereof comprises: (1) a heavy chain comprising the sequence of SEQ ID NO: 63 or an amino acid sequence having at least 80% sequence identity thereto; and / or a light chain comprising the sequence of SEQ ID NO: 64 or an amino acid sequence having at least 80% sequence identity thereto; or, (2) a heavy chain comprising the sequence of SEQ ID NO: 65 or an amino acid sequence having at least 80% sequence identity thereto; and / or a light chain comprising the sequence of SEQ ID NO: 67 or 68 or an amino acid sequence having at least 80% sequence identity thereto; or, (3) a heavy chain comprising the sequence of SEQ ID NO: 66 or an amino acid sequence having at least 80% sequence identity thereto; and / or a light chain comprising the sequence of SEQ ID NO: 67 or 68 or an amino acid sequence having at least 80% sequence identity thereto.

21. The antibody or antigen-binding fragment thereof according to claim 18, wherein the antibody or antigen-binding fragment thereof comprises: a heavy chain comprising the sequence of SEQ ID NO: 52 or 54 or an amino acid sequence having at least 80% sequence identity thereto; and / or a light chain comprising the sequence of SEQ ID NO: 53 or 55 or an amino acid sequence having at least 80% sequence identity thereto; Preferably, the antibody or antigen-binding fragment thereof comprises: (1) a heavy chain comprising the sequence of SEQ ID NO:52 or an amino acid sequence having at least 80% sequence identity thereto; and / or a light chain comprising the sequence of SEQ ID NO:53 or an amino acid sequence having at least 80% sequence identity thereto; or, (2) a heavy chain comprising the sequence of SEQ ID NO:54 or an amino acid sequence having at least 80% sequence identity thereto; and / or a light chain comprising the sequence of SEQ ID NO:55 or an amino acid sequence having at least 80% sequence identity thereto.

22. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 21, wherein the antibody or antigen-binding fragment thereof is selected from the group consisting of: scFv, Fab, Fab', (Fab')2, Fv fragment, diabody, bispecific antibody, multispecific antibody, chimeric antibody, and humanized antibody.

23. An immunoconjugate comprising the antibody or antigen-binding fragment thereof according to any one of claims 1 to 22 and an effector molecule.

24. The immunoconjugate according to claim 23, wherein the effector molecule is a therapeutic agent selected from the group consisting of: drugs, toxins, radioisotopes, proteins, peptides, and nucleic acids.

25. A bispecific or multispecific antibody comprising the antibody or antigen-binding fragment thereof according to any one of claims 1 to 22; Preferably, the bispecific or multispecific antibody specifically binds to TIGIT (e.g., human TIGIT) and a second target; preferably, the second target is a different immune regulatory receptor.

26. An isolated nucleic acid molecule comprising a nucleotide sequence encoding the antibody or antigen-binding fragment thereof according to any one of claims 1 to 22, or its heavy chain variable region and / or light chain variable region, or the bispecific or multispecific antibody according to claim 25.

27. A vector comprising the isolated nucleic acid molecule according to claim 26.

28. A host cell comprising the isolated nucleic acid molecule according to claim 26 or the vector according to claim 27.

29. A method of generating an antibody or an antigen-binding fragment thereof as claimed in any one of claims 1 to 22 or a bispecific or multispecific antibody as claimed in claim 25, the method comprising: Culturing a host cell comprising the isolated nucleic acid molecule according to claim 26 or the vector according to claim 27, or the host cell according to claim 28, under conditions that permit expression of the antibody or antigen-binding fragment thereof or the bispecific or multispecific antibody; and recovering the antibody or antigen-binding fragment thereof or the bispecific or multispecific antibody from the culture of the cultured host cell.

30. A pharmaceutical composition, the pharmaceutical composition comprising an antibody or antigen-binding fragment thereof as described in any one of claims 1 to 22, an immunoconjugate as described in claim 23 or 24, a bispecific or multispecific antibody as described in claim 25, an isolated nucleic acid molecule as described in claim 26, a vector as described in claim 27, or a host cell as described in claim 28, and a pharmaceutically acceptable carrier and / or excipient.

31. The pharmaceutical composition as described in claim 30, the pharmaceutical composition further comprising an additional therapeutic agent; Preferably, the additional therapeutic agent is an anti-tumor agent; Preferably, the additional therapeutic agent is an additional immune checkpoint inhibitor, such as an anti-PD-1 antibody, an anti-PD-L1 antibody, an anti-TIM-3 antibody, an anti-LAG-3 antibody, or an anti-CTLA-4 antibody; Preferably, the additional therapeutic agent is a cytotoxic agent, such as an alkylating agent, an anti-mitotic agent, an anti-tumor antibiotic, an anti-metabolite, a topoisomerase inhibitor, a tyrosine kinase inhibitor, or a radionuclide.

32. Use of an antibody or antigen-binding fragment thereof as described in any one of claims 1 to 22, an immunoconjugate as described in claim 23 or 24, a bispecific or multispecific antibody as described in claim 25, an isolated nucleic acid molecule as described in claim 26, a vector as described in claim 27, a host cell as described in claim 28, or a pharmaceutical composition as described in claim 30 or 31 in the manufacture of a drug for use in: (a) increasing activation of immune cells in a subject in response to an antigen; (b) enhancing the immune response in a subject; (c) reducing or eliminating TIGIT-mediated immunosuppression in a subject; (d) reducing or depleting regulatory T cells in a tumor of a subject; (e) treating a tumor of a subject; and / or (f) treating an infectious disease of a subject; Preferably, the tumor is a solid tumor, such as ovarian cancer, endometrial cancer, breast cancer, lung cancer (small cell or non-small cell), colon cancer, prostate cancer, cervical cancer, pancreatic cancer, gastric cancer, esophageal cancer, hepatocellular carcinoma (liver cancer), renal cell carcinoma (kidney cancer), head and neck tumors, mesothelioma, melanoma, sarcoma, or a brain tumor (e.g., glioma, such as glioblastoma); Preferably, the tumor is a hematological malignancy, such as leukemia, lymphoma, and myeloma, including acute myeloid leukemia, adult T-cell leukemia, T-cell large granular lymphocyte leukemia, acute lymphoblastic leukemia, chronic lymphocytic leukemia, chronic myelogenous leukemia, acute monocytic leukemia, Hodgkin lymphoma, and non-Hodgkin lymphoma, and multiple myeloma; Preferably, the tumor is metastatic cancer, refractory cancer, or recurrent cancer; Preferably, the subject is a mammal, such as a human; Preferably, the antibody or antigen-binding fragment thereof, the immunoconjugate, the bispecific or multispecific antibody, or the pharmaceutical composition is used in combination with an additional therapeutic agent or an additional therapy; Preferably, the additional therapeutic agent is an anti-tumor agent; Preferably, the additional therapeutic agent is an additional immune checkpoint inhibitor, such as an anti-PD-1 antibody, an anti-PD-L1 antibody, an anti-TIM-3 antibody, an anti-LAG-3 antibody, or an anti-CTLA-4 antibody; Preferably, the additional therapeutic agent is a cytotoxic agent, such as an alkylating agent, an anti-mitotic agent, an antitumor antibiotic, an antimetabolite, a topoisomerase inhibitor, a tyrosine kinase inhibitor, or a radionuclide; Preferably, the additional therapy is a standard cancer treatment, such as surgery, chemotherapy, radiotherapy, targeted therapy, immunotherapy, hormone therapy, gene therapy, or palliative care.

33. An antibody or antigen-binding fragment thereof according to any one of claims 1 to 22, an immunoconjugate according to claim 23 or 24, a bispecific or multispecific antibody according to claim 25, an isolated nucleic acid molecule according to claim 26, a vector according to claim 27, a host cell according to claim 28, or a pharmaceutical composition according to claim 30 or 31, for use in: (a) increasing activation of immune cells in a subject in response to an antigen; (b) enhancing the immune response in a subject; (c) reducing or eliminating TIGIT-mediated immunosuppression in a subject; (d) reducing or depleting regulatory T cells in a tumor of a subject; (e) treating a tumor of a subject; and / or (f) treating an infectious disease of a subject; Preferably, the tumor is a solid tumor, such as ovarian cancer, endometrial cancer, breast cancer, lung cancer (small cell or non-small cell), colon cancer, prostate cancer, cervical cancer, pancreatic cancer, gastric cancer, esophageal cancer, hepatocellular carcinoma (liver cancer), renal cell carcinoma (kidney cancer), head and neck tumors, mesothelioma, melanoma, sarcoma, or a brain tumor (e.g., glioma, such as glioblastoma); Preferably, the tumor is a hematological malignancy, such as leukemia, lymphoma, and myeloma, including acute myeloid leukemia, adult T-cell leukemia, T-cell large granular lymphocyte leukemia, acute lymphoblastic leukemia, chronic lymphocytic leukemia, chronic myelogenous leukemia, acute monocytic leukemia, Hodgkin lymphoma, and non-Hodgkin lymphoma, and multiple myeloma; Preferably, the tumor is metastatic cancer, refractory cancer, or recurrent cancer; Preferably, the subject is a mammal, such as a human; Preferably, the antibody or antigen-binding fragment thereof, the immunoconjugate, the bispecific or multispecific antibody, or the pharmaceutical composition is used in combination with an additional therapeutic agent or an additional therapy; Preferably, the additional therapeutic agent is an antitumor agent; Preferably, the additional therapeutic agent is an additional immune checkpoint inhibitor, such as an anti-PD-1 antibody, an anti-PD-L1 antibody, an anti-TIM-3 antibody, an anti-LAG-3 antibody, or an anti-CTLA-4 antibody; Preferably, the additional therapeutic agent is a cytotoxic agent, such as an alkylating agent, an anti-mitotic agent, an antitumor antibiotic, an antimetabolite, a topoisomerase inhibitor, a tyrosine kinase inhibitor, or a radionuclide; Preferably, the additional therapy is a standard cancer treatment such as surgery, chemotherapy, radiotherapy, targeted therapy, immunotherapy, hormone therapy, gene therapy, or palliative care.

34. A method that (a) increases activation of immune cells responsive to an antigen in a subject; (b) enhances the immune response in the subject; (c) reduces or eliminates TIGIT-mediated immunosuppression in the subject; (d) reduces or depletes regulatory T cells in a tumor of the subject; (e) treats a tumor of the subject; and / or (f) treats an infectious disease of the subject; wherein the method comprises administering to a subject in need thereof a therapeutically effective amount of an antibody or an antigen-binding fragment thereof as described in any one of claims 1 to 22, an immunoconjugate as described in claim 23 or 24, a bispecific or multispecific antibody as described in claim 25, an isolated nucleic acid molecule as described in claim 26, a vector as described in claim 27, a host cell as described in claim 28, or a pharmaceutical composition as described in claim 30 or 31; Preferably, the tumor is a solid tumor such as ovarian cancer, endometrial cancer, breast cancer, lung cancer (small cell or non-small cell), colon cancer, prostate cancer, cervical cancer, pancreatic cancer, gastric cancer, esophageal cancer, hepatocellular carcinoma (liver cancer), renal cell carcinoma (kidney cancer), head and neck tumors, mesothelioma, melanoma, sarcoma, or brain tumors (e.g., gliomas such as glioblastoma); Preferably, the tumor is a hematological malignancy such as leukemia, lymphoma, and myeloma, including acute myeloid leukemia, adult T-cell leukemia, T-cell large granular lymphocyte leukemia, acute lymphoblastic leukemia, chronic lymphocytic leukemia, chronic myelogenous leukemia, acute monocytic leukemia, Hodgkin lymphoma, and non-Hodgkin lymphoma, and multiple myeloma; Preferably, the tumor is metastatic cancer, refractory cancer, or recurrent cancer; Preferably, the subject is a mammal such as a human; Preferably, the antibody or its antigen-binding fragment, the immunoconjugate, the bispecific or multispecific antibody, or the pharmaceutical composition is used in combination with an additional therapeutic agent or an additional therapy; Preferably, the additional therapeutic agent is an anti-tumor agent; Preferably, the additional therapeutic agent is an additional immune checkpoint inhibitor such as an anti-PD-1 antibody, an anti-PD-L1 antibody, an anti-TIM-3 antibody, an anti-LAG-3 antibody, or an anti-CTLA-4 antibody; Preferably, the additional therapeutic agent is a cytotoxic agent such as an alkylating agent, an anti-mitotic agent, an anti-tumor antibiotic, an anti-metabolite, a topoisomerase inhibitor, a tyrosine kinase inhibitor, or a radionuclide; Preferably, the additional therapy is a standard cancer treatment such as surgery, chemotherapy, radiotherapy, targeted therapy, immunotherapy, hormone therapy, gene therapy, or palliative care.

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