CD3 ANTIGEN BINDING FRAGMENTS AND COMPOSITIONS COMPRISING SAME

1 - 127 . (canceled)

128 . A polypeptide comprising an antigen binding fragment, wherein the antigen binding fragment comprises light chain complementarity-determining regions (CDR-L) and heavy chain complementarity-determining regions (CDR-H), and wherein the antigen binding fragment:

a. specifically binds to cluster of differentiation 3 T cell receptor (CD3); and

b. comprises CDR-H1, CDR-H2, and CDR-H3, wherein the CDR-H3 comprises an amino acid sequence of SEQ ID NO:10.

129 . The polypeptide of claim 128 , wherein the CDR-H1 comprises an amino acid sequence of SEQ ID NO: 8; and wherein the CDR-H2 comprises an amino acid sequence of SEQ ID NO: 9.

130 . The polypeptide of claim 128 , wherein the antigen binding fragment exhibits a higher thermal stability, as evidenced by in an in vitro assay,

(i) a higher melting temperature (T m ) relative to that of an antigen binding fragment consisting of a sequence shown in SEQ ID NO:41, or

(ii) upon incorporating said anti-CD3 antigen binding fragment into an anti-CD3 bispecific antibody, the bispecific antibody exhibits a higher Tm relative to a control bispecific antibody, wherein said anti-CD3 bispecific antibody comprises said anti-CD3 binding fragment and a reference antigen binding fragment that binds to an antigen other than CD3, and wherein said control bispecific antigen binding fragment consists of SEQ ID NO:41 and said reference antigen binding fragment.

131 . The polypeptide of claim 130 , wherein the T m of the antigen binding fragment is at least 2° C. greater than the T m of an antigen binding fragment consisting of a sequence of SEQ ID NO:41.

132 . The polypeptide of claim 130 , wherein the CDR-H1 comprises an amino acid sequence of SEQ ID NO: 8; and wherein the CDR-H2 comprises an amino acid sequence of SEQ ID NO: 9.

133 . The polypeptide of claim 128 , wherein the antigen binding fragment comprises FR-H1, FR-H2, FR-H3, FR-H4, each exhibiting at least 86% sequence identity to an amino acid of SEQ ID NOs: 22, 23, 25, and 26, respectively.

134 . The polypeptide of claim 128 , wherein the antigen binding fragment comprises FR-L1, FR-L2, FR-L3, FR-L4, each exhibiting at least 86% sequence identity to amino acid sequences of SEQ ID NOs: 12, 13, 18, and 19, respectively.

135 . The polypeptide of claim 128 , wherein the CDR-L comprises:

a. a CDR-L1 having an amino acid sequence of SEQ ID NOs: 1 or 2,

b. a CDR-L2 having an amino acid sequence of SEQ ID NOs: 4 or 5, and

c. a CDR-L3 having an amino acid sequence of SEQ ID NO:6.

136 . The polypeptide of claim 128 , wherein the CDR-L comprises:

a. a CDR-L1 having an amino acid sequence of SEQ ID NO:1;

b. a CDR-L2 having an amino acid sequence of any one of SEQ ID NOs: 4 or 5; and

c. a CDR-L3 having an amino acid sequence of SEQ ID NOs: 6 or 7.

137 . The polypeptide of claim 128 , wherein the CDR-L comprises:

a. a CDR-L1 having an amino acid sequence of SEQ ID NO:2;

b. a CDR-L2 having an amino acid sequence of any one of SEQ ID NOs: 4 or 5; and

c. a CDR-L3 having an amino acid sequence of SEQ ID NO:6.

138 . The polypeptide of claim 128 , wherein the CDR-L comprises:

a. a CDR-L1 having an amino acid sequence of SEQ ID NO: 1;

b. a CDR-L2 having an amino acid sequence of SEQ ID NO: 4; and

c. a CDR-L3 having an amino acid sequence of SEQ ID NO: 6.

139 . The polypeptide of claim 128 , wherein the CDR-L comprises:

a. a CDR-L1 having an amino acid sequence of SEQ ID NO:2;

b. a CDR-L2 having an amino acid sequence of SEQ ID NO:5; and

c. a CDR-L3 having an amino acid sequence of SEQ ID NO:6.

140 . The polypeptide of claim 128 , wherein the antigen binding fragment further comprises a light chain framework region (FR-L) and a heavy chain framework region (FR-H), and wherein the antigen binding fragment comprises:

a. a FR-L1 having an amino acid sequence of SEQ ID NO:12;

b. a FR-L2 having an amino acid sequence of SEQ ID NO:13;

c. a FR-L3 having an amino acid sequence of any one of SEQ ID NOs:14-17;

d. a FR-L4 having an amino acid sequence of SEQ ID NO:19;

e. a FR-H1 having an amino acid sequence of SEQ ID NO:20 or SEQ ID NO:21;

f. a FR-H2 having an amino acid sequence of SEQ ID NO:23;

g. a FR-H3 having an amino acid sequence of SEQ ID NO:24; and

h. a FR-H4 having an amino acid sequence of SEQ ID NO:26.

141 . The polypeptide of claim 128 , wherein the antigen binding fragment further comprises a light chain framework region (FR-L) and a heavy chain framework region (FR-H), and wherein the antigen binding fragment comprises:

a. a FR-L1 having an amino acid sequence of SEQ ID NO:12;

b. a FR-L2 having an amino acid sequence of SEQ ID NO:13;

c. a FR-L3 having an amino acid sequence of SEQ ID NO:14;

d. a FR-L4 having an amino acid sequence of SEQ ID NO:19;

e. a FR-H1 having an amino acid sequence of SEQ ID NO:20;

f. a FR-H2 having an amino acid sequence of SEQ ID NO:23;

g. a FR-H3 having an amino acid sequence of SEQ ID NO:24; and

h. a FR-H4 having an amino acid sequence of SEQ ID NO:26.

142 . The polypeptide of claim 128 , wherein the antigen binding fragment further comprises a light chain framework region (FR-L) and a heavy chain framework region (FR-H), and wherein the antigen binding fragment comprises:

a. a FR-L1 having an amino acid sequence of SEQ ID NO:12;

b. a FR-L2 having an amino acid sequence of SEQ ID NO:13;

c. a FR-L3 having an amino acid sequence of SEQ ID NO:15;

d. a FR-L4 having an amino acid sequence of SEQ ID NO:19;

e. a FR-H1 having an amino acid sequence of SEQ ID NO:21;

f. a FR-H2 having an amino acid sequence of SEQ ID NO:23;

g. a FR-H3 having an amino acid sequence of SEQ ID NO:24; and

h. a FR-H4 having an amino acid sequence of SEQ ID NO:26.

143 . The polypeptide of claim 128 , wherein the antigen binding fragment further comprises a light chain framework region (FR-L) and a heavy chain framework region (FR-H), and wherein the antigen binding fragment comprises:

a. a FR-L1 having an amino acid sequence of SEQ ID NO:12;

b. a FR-L2 having an amino acid sequence of SEQ ID NO:13;

c. a FR-L3 having an amino acid sequence of SEQ ID NO:16;

d. a FR-L4 having an amino acid sequence of SEQ ID NO:19;

e. a FR-H1 having an amino acid sequence of SEQ ID NO:21;

f. a FR-H2 having an amino acid sequence of SEQ ID NO:23;

g. a FR-H3 having an amino acid sequence of SEQ ID NO:24; and

h. a FR-H4 having an amino acid sequence of SEQ ID NO:26.

144 . The polypeptide of claim 128 , wherein the antigen binding fragment further comprises a light chain framework region (FR-L) and a heavy chain framework region (FR-H), and wherein the antigen binding fragment comprises:

a. a FR-L1 having an amino acid sequence of SEQ ID NO:12;

b. a FR-L2 having an amino acid sequence of SEQ ID NO:13;

c. a FR-L3 having an amino acid sequence of SEQ ID NO:17;

d. a FR-L4 having an amino acid sequence of SEQ ID NO:19;

e. a FR-H1 having an amino acid sequence of SEQ ID NO:21;

f. a FR-H2 having an amino acid sequence of SEQ ID NO:23;

g. a FR-H3 having an amino acid sequence of SEQ ID NO:24; and

h. a FR-H4 having an amino acid sequence of SEQ ID NO:26.

145 . The polypeptide of claim 128 , wherein the antigen binding fragment comprises a variable heavy (VH) amino acid sequence having at least 90% sequence identity to an amino acid sequence of SEQ ID NO:28 or SEQ ID NO:31.

146 . The polypeptide of claim 128 , wherein the antigen binding fragment comprises a variable light (VL) amino acid sequence having at least 90% sequence identity to an amino acid sequence of any one of SEQ ID NOs: 27, 29, 30, 32, or 33.

147 . The polypeptide of claim 128 , wherein the antigen binding fragment comprises an amino acid sequence having at least 95% sequence identity to an amino acid sequence of any one of SEQ ID NOs:36-40.

148 . The polypeptide of claim 128 , wherein the antigen binding fragment specifically binds human or cynomolgus monkey (cyno) CD3.

149 . The polypeptide of claim 128 , wherein the antigen binding fragment specifically binds human and cynomolgus monkey (cyno) CD3.

150 . The polypeptide of claim 128 , wherein the antigen binding fragment binds a CD3 complex subunit selected from CD3 epsilon, CD3 delta, CD3 gamma, CD3 zeta, CD3 alpha and CD3 beta epsilon unit of CD3.

151 . The polypeptide of claim 128 , wherein the antigen binding fragment binds a CD3 epsilon fragment of CD3.

152 . The polypeptide of claim 128 , wherein the antigen binding fragment exhibits an isoelectric point (p1) that is less than or equal to 6.6.

153 . The polypeptide of claim 128 , wherein the antigen binding fragment exhibits a p1 that is between 6.0 and 6.6, inclusive.

154 . The polypeptide of claim 128 , wherein the antigen binding fragment exhibits a p1 that is at least 0.1 pH units lower than the p1 of a reference antigen binding fragment consisting of a sequence shown in SEQ ID NO: 41.

155 . The polypeptide of claim 128 , wherein the antigen binding fragment specifically binds human or cyno CD3 with a dissociation constant (K d ) constant between about between about 10 nM and about 400 nM, as determined in an in vitro antigen-binding assay comprising a human or cyno CD3 antigen.

156 . The polypeptide of claim 128 , wherein the antigen binding fragment specifically binds human or cyno CD3 with a dissociation constant (K d ) of less than about 10 nM as determined in an in vitro antigen-binding assay.

157 . The polypeptide of claim 128 , wherein the antigen binding fragment exhibits a binding affinity to CD3 that is at least 2-fold weaker relative to that of an antigen binding fragment consisting of an amino acid sequence of SEQ ID NO:41, as determined by the respective dissociation constants (K d ) in an in vitro antigen-binding assay.

158 . A pharmaceutical composition comprising the polypeptide of claim 128 and one or more pharmaceutically suitable excipients.

159 . A method of treating a disease in a subject, comprising administering to the subject in need thereof one or more therapeutically effective doses of the pharmaceutical composition of claim 158 .

160 . An isolated nucleic acid, the nucleic acid comprising (a) a polynucleotide encoding a polypeptide of claim 128 ; or (b) the complement of the polynucleotide of (a).