A Novel Anti-Pdl1 X Anti-Vegfr2 Bispecific Antibody For Enhanced Antitumor Immunity

The importance of VEGF/VEGFR2 signaling in cancer growth and metastasis has been clearly highlighted by the therapeutic benefits of bevacizumab (Avastin), a humanized antibody to VEGF, and Cyramza, a fully human antibody to VEGFR2, in multiple cancer treatment modalities. Recently, immune checkpoint antagonistic antibodies to PD1 and PDL1 have shown some success in a variety of clinical settings across multiple cancer types. The overall clinical efficacy of these individual antibody therapies has been, however, rather limited and, only evident in a fraction of patients. To this end, combinations of antibodies against both VEGF/VEGFR2 and PD1/PDL1 may represent promising approaches to further enhance the antitumor efficacy of individual antibody therapies. In this study, we engineered a bispecific anti-PDL1 x anti-VEGFR2 antibody using two fully human antibodies derived from antibody phage display libraries. In this bispecific format, a high affinity single chain antibody to PDL1 was genetically fused to the C-terminus of the heavy chain of a conventional IgG antibody against VEGFR2. The bispecific antibody was efficiently expressed in mammalian cells and could be purified to homogeneity via single step affinity chromatography. The bispecific antibody retained the binding activity of its parental antibodies to PDL1 and VEGFR2, and strongly blocked both VEGF/VEGFR2 and PDL1/PD1 interaction. Further, the bispecific antibody inhibited VEGF-stimulated VEGFR2 phosphorylation and proliferation of endothelial cells, and promoted proliferation of human T cells and secretion of cytokine such as IL2 and INFγ. The bispecific antibody is currently being evaluated in vivo in relevant animal models. Citation Format: Dan Lu, Zhanna Polonskaya, Haifan Zhang, Xenia Luna, Stella Martomo, Zhikai Zhang, Zhaojing Zhong, Yan Wu, Jeegar Patel, James Tonra, Larry Witte, Sam Waksal, Zhenping Zhu. A novel anti-PDL1 x anti-VEGFR2 bispecific antibody for enhanced antitumor immunity. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 572.