Vascular endothelial growth factor (VEGF) and its receptor (VEGFR) play a fundamental role in tumor growth and angiogenesis. Signalling through VEGF/VEGFR not only induces cancer angiogenesis but also affects immune cells, making VEGF/VEGFR a pair of well-documented cancer therapeutic targets. Recently more and more studies have focused on combination of anti-VEGF/VEGFR agents and immune checkpoint inhibitors in preclinical and clinical settings. BD0801 is a humanized rabbit anti-VEGF monoclonal antibody currently in clinical development stage. In this study, we have revealed that BD0801 presents more potent activity than Bevacizumab in blockade of VEGF/VEGFR2 binding (IC50=275 ng/ml for BD0801; IC50=1451 ng/ml for Bevacizumab) and VEGFR2 activation in HUVEC assays. BD0801 also showed enhanced inhibitory effects on the proliferation (IC50=87 ng/ml for BD0801; IC50=476 ng/ml for Bevacizumab) and migration of the HUVECs, compared to Bevacizumab. We found that BD0801 exhibits dose-dependent tumor growth inhibitory activities in both lung cancer PC9 xenograft and lung cancer 3LL murine syngeneic tumor models. In addition, we obtained PK parameters of BD0801 using lung cancer PC9 tumor bearing mice and successfully made correlations between the in vitro function, PK profile and in vivo efficacy of BD0801. Notably, combination of BD0801 with either anti-PD-1, or anti-PD-L1 antibodies showed synergistic anti-tumor efficacy in both lung and colorectal cancer mouse models. Mechanistic studies were conducted to reveal possible mechanism of actions (MOA) underlying the modification in tumor microenvironment. Our data demonstrated that the MOA of the anti-tumor synergy may involve enhanced T-cell mediated immunity, including increased tumor infiltration of CD8+ and CD4+ T cells and reduced double positive CD8+PD-1+ T cells, as well as improved vasculature normalization. Taken together, these data provide a foundation for combining BD0801 with immunotherapy for cancer treatment and support further clinical development plans for BD0801 toward this direction.

Citation Format: Liting Xue, Haoyu Zhang, Qian Wang, Feng Li, Xinxin Li, Xiaohong Yu, Zhihong Lu, Yue Huang, Wenqing Yang. Combination of an anti-angiogenic antibody with PD1/PDL1 blockade agents produces synergistic anti-tumor efficacy in preclinical models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2651.