Antibodies and methods for depleting regulatory bio cells and use in combination with immune checkpoint inhibitors

An antibody that specifically binds to human CD22 comprising a heavy chain variable region and a light chain variable region, the heavy chain variable region (“VH”) comprising three complementarity determining regions (CDR):

• VH CDR1, VH CDR2, and VH CDR3, and the light chain variable region (“VL”) comprising three complementarity determining regions:
• VL CDR1, VL CDR2, and VL CDR3, wherein:
• (a) the VH comprises CDR1 of SEQ ID NO:
• 27, CDR2 of SEQ ID NO:
• 29, and CDR3 of SEQ ID NO:
• 32 and the VL comprises CDR1 of SEQ ID NO:
• 40, CDR2 of SEQ ID NO:
• 41, and CDR3 of SEQ ID NO:
• 42;
• (b) the VH comprises CDR1 of SEQ ID NO:
• 27, CDR2 of SEQ ID NO:
• 30, and CDR3 of SEQ ID NO:
• 32 and the VL comprises CDR1 of SEQ ID NO:
• 37, CDR2 of SEQ ID NO:
• 38, and CDR3 of SEQ ID NO:
• 39;
• (c) the VH comprises CDR1 of SEQ ID NO:
• 28, CDR2 of SEQ ID NO:
• 31, and CDR3 of SEQ ID NO:
• 33 and the VL comprises CDR1 of SEQ ID NO:
• 34, CDR2 of SEQ ID NO:
• 35, and CDR3 of SEQ ID NO:
• 36;
• or
• (d) the VH comprising CDR1 of SEQ ID NO:
• 27, CDR2 of SEQ ID NO:
• 30, and CDR3 of SEQ ID NO:
• 32 and the VL comprising CDR1 of SEQ ID NO:
• 43, CDR2 of SEQ ID NO:
• 44, and CDR3 of SEQ ID NO:
• 45.