Development and preclinical characterization of a humanized antibody targeting CXCL12.

Purpose: Our goal was to develop a potent humanized antibody against mouse/human CXCL12. This report summarized its in vitro and in vivo activities. Experimental Design: Cell surface binding and cell migration assays were used to select neutralizing hamster antibodies, followed by testing in several animal models. Monoclonal antibody (mAb) 30D8 was selected for humanization based on its in vitro and in vivo activities. Results: 30D8, a hamster antibody against mouse and human CXCL12 alpha, CXCL12 beta, and CXCL12 gamma, was shown to dose-dependently block CXCL12 alpha binding to CXCR4 and CXCR7, and CXCL12 alpha-induced Jurkat cell migration in vitro. Inhibition of primary tumor growth and/or metastasis was observed in several models. 30D8 alone significantly ameliorated arthritis in a mouse collagen-induced arthritis model (CIA). Combination with a TNF-alpha antagonist was additive. In addition, 30D8 inhibited 50% of laser-induced choroidal neovascularization (CNV) in mice. Humanized 30D8 (hu30D8) showed similar in vitro and in vivo activities as the parental hamster antibody. A crystal structure of the hu30D8 Fab/CXCL12 alpha complex in combination with mutational analysis revealed a "hot spot" around residues Asn(44)/Asn(45) of CXCL12 alpha and part of the RFFESH region required for CXCL12 alpha binding to CXCR4 and CXCR7. Finally, hu30D8 exhibited fast clearance in cynomolgus monkeys but not in rats. Conclusion: CXCL12 is an attractive target for treatment of cancer and inflammation-related diseases; hu30D8 is suitable for testing this hypothesis in humans. (C)2013 AACR.