Identification and characterization of fully human anti-CD22 monoclonal antibodies

Abstract

CD22 is a member of the B cell receptor family and is implicated in B cell function and development. It is expressed on multiple forms of B cell lymphoma and is an attractive cancer therapeutic target. We report here the identification of two fully human anti-CD22 antibodies using phage display methodology. Both antibodies exhibit specific binding to cell surface-associated CD22 in multiple B cell lines. Through ELISA using mammalian cell-expressed sub-domains of CD22 as binding antigen, we mapped the binding epitopes of the newly identified CD22 antibodies to be within the Ig-like domains 5 to 7 of CD22. Their epitopes do not overlap with those of several therapeutic antibodies currently in preclinical or clinical development. These antibodies have potential as cancer therapeutic candidates and research reagents.

Anti-CD22–chimeric antigen receptors targeting B-cell precursor acute lymphoblastic leukemia

“…20 The creation of the m971 scFv was also previously described. 18 For integration into the CAR vector, BL22, and HA22 scFv sequences were modified by removal of the first 2 amino acids, and a huGM-CSFR leader sequence was added. 21 The CH2CH3 domains from IgG1 (Gene ID: 3500 IGHG1, aa 176-407) were included where designated.…”

“…15 Both BL22 and HA22 mediate antitumor activity in B-cell precursor acute lymphocytic leukemia and therefore we tested their antigen binding domains for efficacy in the context of CAR therapy. 16,17 We also developed a CAR incorporating an alternative fully human scFv, derived from mAb m971, 18 which binds a more membrane proximal epitope on CD22, to investigate the impact of epitope selection on the efficacy of CAR-based therapy. In this report, we demonstrate that epitope specificity has a major impact on CAR efficacy because CD22-CARs incorporating the m971 binding domain mediate much more potent antileukemic activity in preclinical models than CD22-CARs of similar affinity targeting distinct epitopes.…”

Chimeric antigen receptors that trigger phagocytosis

“…Because CAR-P Megf10 performed well in our initial screen, we developed ɑCD22 CAR-P Megf10 using a previously developed ɑCD22 antibody fragment ( Fig. 1a) (Xiao et al 2009;Haso et al 2013). Consistent with our results using ɑCD19-based CARs, ɑCD22 CAR-P Megf10 promoted engulfment of CD22 beads ( Fig.…”

Establishment of Novel Monoclonal Fabs Specific for Epstein-Barr Virus Encoded Latent Membrane Protein 1

“…To screen the Fab library, we first constructed a vector which contained a DNA fragment encoding the LMP1 gene extracellular domain segments (residues 45-51, 97-106, and 161-163, separated by amino acid GGGS for each segment) fused with Fc fusion protein (LMP1-Fc) in a backbone vector pSegTag as described previously (Xiao et al 2009). The plasmid encoding LMP1-Fc was transfected into 293T cells and the secreted LMP1-Fc protein was purified by Protein A agarose beads as bait for subsequent library panning.…”