Antibody targeting CD22 and CD79B

A method of modulating B cell activation, inhibiting aberrant B cell activation, decreasing B cell proliferation, decreasing cytokine production or reducing B cell activation in a subject, comprising administering an effective amount of a bispecific antibody or bispecific binding fragment to the subject for a time sufficient to modulate B cell activation, inhibit aberrant B cell activation, decrease B cell proliferation, decrease cytokine production or reduce B cell activation, wherein the bispecific antibody or bispecific binding fragment comprises a) a first antigen-binding arm that binds cluster of differentiation 79B protein (CD79B), comprising a first variable heavy domain (VH1) and further comprising a first variable light domain (VL1);

• and b) a second antigen-binding arm that binds cluster of differentiation 22 (CD22), comprising a second variable heavy domain (VH2) and further comprising a second variable light domain (VL2), wherein:
• the VH1 comprises the HCDR1 of SEQ ID NO:9, the HCDR2 of SEQ ID NO:
• 10, and the HCDR3 of SEQ ID NO:
• 11, and the VL1 comprises the LCDR1 of SEQ ID NO:12, the LCDR2 of SEQ ID NO:
• 13, and the LCDR3 of SEQ ID NO:
• 14;
• and wherein
• the VH2 comprises the HCDR1 of SEQ ID NO:
• 1, the HCDR2 of SEQ ID NO:2, and the HCDR3 of SEQ ID NO:3, and the VL2 comprising the LCDR1 of SEQ ID NO:4, the LCDR2 of SEQ ID NO:5, and the LCDR3 of SEQ ID NO:6.

A bispecific antibody or bispecific binding fragment comprising:

• a) a first antigen-binding arm that binds cluster of differentiation 79B protein (CD79B), comprising a first variable heavy domain (VH1) and further comprising a first variable light domain (VL1), wherein the first antigen-arm that binds CD79B comprises at least one selected from the group consisting of:
• (i) the VH1 comprises the HCDR1 of SEQ ID NO:9, the HCDR2 of SEQ ID NO:
• 10, and the HCDR3 of SEQ ID NO:11;
• and the VL1 comprises the LCDR1 of SEQ ID NO:
• 12, the LCDR2 of SEQ ID NO:
• 13, and the LCDR3 of SEQ ID NO:
• 14;
• (ii) the VH1 comprises the HCDR1 of SEQ ID NO:17, the HCDR2 of SEQ ID NO:
• 18, and the HCDR3 of SEQ ID NO:
• 19;
• and the VL1 comprises the LCDR1 of SEQ ID NO:20, the LCDR2 of SEQ ID NO:21, and the LCDR3 of SEQ ID NO:22;
• (iii) the VH1 comprises the HCDR1 of SEQ ID NO:25, the HCDR2 of SEQ ID NO:26, and the HCDR3 of SEQ ID NO:27;
• and the VL1 comprises the LCDR1 of SEQ ID NO:28, the LCDR2 of SEQ ID NO:29, and the LCDR3 of SEQ ID NO:30;
• (iv) the VH1 comprises the HCDR1 of SEQ ID NO:33, the HCDR2 of SEQ ID NO:34, and the HCDR3 of SEQ ID NO:35;
• and the VL1 comprises the LCDR1 of SEQ ID NO:36, the LCDR2 of SEQ ID NO:37, and the LCDR3 of SEQ ID NO:38;
• (v) the VH1 comprises the HCDR1 of SEQ ID NO:41, the HCDR2 of SEQ ID NO:42, and the HCDR3 of SEQ ID NO:43;
• and the VL1 comprises the LCDR1 of SEQ ID NO:44, the LCDR2 of SEQ ID NO:45, and the LCDR3 of SEQ ID NO:46;
• (vi) the VH1 comprises the HCDR1 of SEQ ID NO:49, the HCDR2 of SEQ ID NO:50, and the HCDR3 of SEQ ID NO:51;
• and the VL1 comprises the LCDR1 of SEQ ID NO:52, the LCDR2 of SEQ ID NO:53, and the LCDR3 of SEQ ID NO:54;
• and
• (vii) the VH1 comprises the HCDR1 of SEQ ID NO:57, the HCDR2 of SEQ ID NO:58, and the HCDR3 of SEQ ID NO:59;
• and the VL1 comprises the LCDR1 of SEQ ID NO:60, the LCDR2 of SEQ ID NO:61, and the LCDR3 of SEQ ID NO:62;
• and
• b) a second antigen-binding arm that binds cluster of differentiation 22 (CD22), comprising a second variable heavy domain (VH2) and further comprising a second variable light domain (VL2).