Abstract A023: VEGF-neutralization by armored CAR-T cells remodel the tumor microenvironment and enhance antitumor efficacy against solid tumors

Abstract Adoptive cell therapy using T cells engineered to express chimeric antigen receptors (CARs) has only shown limited responses against solid tumors, and improved CAR-T cell designs are needed to achieve more potent and durable responses. One of the major factors limiting CAR-T cell activity within solid tumors is the highly immunosuppressive solid tumor microenvironment (TME) which promotes immune-cell dysfunction and tumor immune escape. Specifically, vascular endothelial growth factor A (VEGF-A) presents as a physical barrier through its pro-angiogenic properties and contribution to excessive tumor vascularization, giving rise to abnormal and dysfunctional vessels with impaired perfusion thus leading to intra-tumoral hypoxia. Furthermore, VEGF-A serves as a chemical barrier by suppressing T-cell activation and cytotoxicity, upregulating immune checkpoints on T cells, inhibiting dendritic cell maturation, and recruiting immunosuppressive cells. Here, we present a strategy to enhance CAR-T cell efficacy and reprogram the TME by engineering CAR-T cells to secrete a novel VEGF-A–neutralizing single-chain variable fragment (scFv). We demonstrate that scFv-secreting CAR-T cells (CAR-αVEGF T cells) achieve superior anti-tumor efficacy against models of ovarian cancer and brain cancer compared to conventional CAR-T cells that do not secret anti–VEGF-A scFvs. Notably, the enhanced efficacy exhibited by CAR-αVEGF T cells is not replicated by combining conventional CAR-T cells with anti-VEGF antibody therapy. Mechanistically, treatment with CAR-αVEGF T cells reduces or reverses multiple adverse effects associated with on-target CAR-T cell therapy, including intra-tumoral infiltration of myeloid cells, exaggerated vasculature abnormalities, and hypoxia. Treatment with CAR-αVEGF T cells also results in an enrichment of immune-stimulatory and anti-tumor signatures among intra-tumoral immune cells. These findings indicate that blocking of intra-tumoral VEGF by αVEGF-scFv armored CAR-T cells enable favorable remodeling of the immunosuppressive TME, resulting in more potent CAR-T cell therapies. Citation Format: Torahito A Gao, Justin D Clubb, Ryan M Shih, Tanya Singh, Gabriella Dibernardo, Amanda Shafer, Amber Bouren, Melanie A Ceja, Sophie Ong, Christine Brown, Hideho Okada, Sanaz Memarzadeh, Han-Chung Wu, Yvonne Y Chen. VEGF-neutralization by armored CAR-T cells remodel the tumor microenvironment and enhance antitumor efficacy against solid tumors [abstract]. In: Proceedings of the AACR IO Conference: Discovery and Innovation in Cancer Immunology: Revolutionizing Treatment through Immunotherapy; 2025 Feb 23-26; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Immunol Res 2025;13(2 Suppl):Abstract nr A023.