Abstract 125: Development of humanized VEGFA models to assess preclinical efficacy of novel therapeutics in vivo

Abstract VEGFA is an essential growth factor required for angiogenesis in the context of normal wound healing as well as malignant tissue growth, ultimately facilitating the delivery of oxygen and nutrients to fuel cellular survival, expansion, and repair. VEGFA signaling has also been reported to exert effects on cancer cells and immune cells directly, with evidence suggesting that the pathway can both support tumor growth and inhibit immune surveillance. Thus, targeting VEGFA has been intensely explored as a therapeutic strategy for several cancer indications. Here, we generated a novel humanized VEGFA model (B-hVEGFA mice) to explore the ability of novel VEGFA-targeting therapeutics to curb cancer cell growth and angiogenesis in vivo. This was achieved by replacing the murine Vegfa gene with the corresponding human VEGFA coding region. We confirmed exclusive expression of human VEGF in lung homogenates of the humanized model at levels comparable to murine VEGF quantified in wild-type C57BL/6 mice. Immunohistochemical analysis at 8 weeks of age demonstrates no significant difference in the CD31+ area in several organs of the humanized mice when compared to wild-type C57BL/6 mice, including kidney, heart, liver, and eye. To assess the functional utility of this model in evaluating VEGFA modulators, tumor studies were conducted: murine colon cancer MC38 cells that were also engineered to express VEGFA in a similar manner (B-hVEGFA MC38 cells) were subcutaneously implanted into homozygous B-hVEGFA mice. Treatment with bevacizumab analog essentially abolished tumor growth in the humanized mice, while control tumors continued to expand over the 3 week study. To further evaluate the role of novel combination therapies or bispecific antibodies targeting VEGFA and PD-1, we also generated a triple humanized model expressing human VEGF, PD-1, and PD-L1 (B-hPD-1/hPD-L1/hVEGFA mice) by crossing B-hVEGFA mice with our B-hPD-1/hPD-L1 mice model, which expresses the extracellular domains of human PD-1 and PD-L1. Flow cytometric analysis of this model is currently underway to validate the model for further efficacy testing. Together, these humanized VEGF models provide robust in vivo platforms to evaluate novel VEGFA therapeutic candidates. Citation Format: Shujin Zhang, Chonghui Liu, Jin Guo, Zhiyuan Shen, James Jin, Bahetiyaer Huwatibieke, Yang Shen. Development of humanized VEGFA models to assess preclinical efficacy of novel therapeutics in vivo abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 125.