[0018]In another embodiment, the invention provides an antibody or antigen binding fragment that binds to human TIGIT comprising: (i) a heavy chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 57; (ii) a heavy chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 58; (iii) a heavy chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 59; (iv) a light chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 60; (v) a light chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 61; and (vi) a light chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 62. In one embodiment, the antibody or antigen binding fragment thereof is humanized. In one embodiment, the antibody or antigen binding fragment thereof comprises 1, 2 or 3 amino acid substitutions in the heavy chain CDRs (SEQ ID NOs: 57-59) or in the light chain CDRs (SEQ ID NOs: 60-62), and retains one or more of its functional characteristics. In one embodiment, the antibody or antigen binding fragment thereof optionally has at least one of the following functional characteristics: (i) binds to human TIGIT with a KD value of about 1×10-9 M to about 1×10-12 M as determined by surface plasmon resonance (e.g., BIACORE) or a similar technique (e.g. KinExa or OCTET), (ii) cross-reacts with cynomolgous and rhesus TIGIT; (iii) blocks binding of human TIGIT to human CD155 and human CD112; (iv) increases T cell activation; (v) stimulates antigen-specific T-cell production of IL-2 and IFNγ; (vi) blocks induction of T cell suppression of activation induced by TIGIT ligation with cognate ligands CD155 and CD112.
[0019]In another embodiment, the invention also provides an antibody or antigen binding fragment thereof that binds to human TIGIT comprising: (i) a heavy chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 88; (ii) a heavy chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 147; (iii) a heavy chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 153; (iv) a light chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 91; (v) a light chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 148; and (vi) a light chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 93. In one embodiment, the antibody or antigen binding fragment thereof comprises: (i) a heavy chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 88; (ii) a heavy chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 89, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 134 or 135; (iii) a heavy chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 90, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166 or 167; (iv) a light chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 91; (v) a light chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 92, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121 or 122; and (vi) a light chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 93. In one embodiment, the antibody or antigen binding fragment thereof comprises: (i) a heavy chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 88; (ii) a heavy chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 89, 134 or 135; (iii) a heavy chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 90; (iv) a light chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 91; (v) a light chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 92; and (vi) a light chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 93. In one embodiment, the antibody or antigen binding fragment thereof comprises: (i) a heavy chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 88; (ii) a heavy chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 134; (iii) a heavy chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 90; (iv) a light chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 91; (v) a light chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 92; and (vi) a light chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 93. In one embodiment, the antibody or antigen binding fragment thereof is humanized. In one embodiment, the antibody or antigen binding fragment thereof comprises: (i) a heavy chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 88; (ii) a heavy chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 134; (iii) a heavy chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 154; (iv) a light chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 91; (v) a light chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 92; and (vi) a light chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 93. In one embodiment, the antibody or antigen binding fragment thereof is humanized. In one embodiment, the antibody or antigen binding fragment thereof comprises: (i) a heavy chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 88; (ii) a heavy chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 134; (iii) a heavy chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 155; (iv) a light chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 91; (v) a light chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 92; and (vi) a light chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 93. In one embodiment, the antibody or antigen binding fragment thereof is humanized. In one embodiment, the antibody or antigen binding fragment thereof comprises: (i) a heavy chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 88; (ii) a heavy chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 134; (iii) a heavy chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 156; (iv) a light chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 91; (v) a light chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 92; and (vi) a light chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 93. In one embodiment, the antibody or antigen binding fragment thereof is humanized. In one embodiment, the antibody or antigen binding fragment thereof comprises: (i) a heavy chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 88; (ii) a heavy chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 134; (iii) a heavy chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 157; (iv) a light chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 91; (v) a light chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 92; and (vi) a light chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 93. In one embodiment, the antibody or antigen binding fragment thereof is humanized. In one embodiment, the antibody or antigen binding fragment thereof comprises: (i) a heavy chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 88; (ii) a heavy chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 134; (iii) a heavy chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 158; (iv) a light chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 91; (v) a light chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 92; and (vi) a light chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 93. In one embodiment, the antibody or antigen binding fragment thereof is humanized. In one embodiment, the antibody or antigen binding fragment thereof comprises: (i) a heavy chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 88; (ii) a heavy chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 134; (iii) a heavy chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 159; (iv) a light chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 91; (v) a light chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 92; and (vi) a light chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 93. In one embodiment, the antibody or antigen binding fragment thereof is humanized. In one embodiment, the antibody or antigen binding fragment thereof comprises: (i) a heavy chain variable region CDR1 comprising the amino acid sequence of SEQ ID NO: 88; (ii) a heavy chain variable region CDR2 comprising the amino acid sequence of SEQ ID NO: 134; (iii) a heavy chain variable region CDR3 comprising the amino acid sequence of SEQ ID NO: 160; (iv) a light chain variable region CDR1 comprising the amino acid sequen