Abstract 4818: CSPG4-targeting CAR-macrophages inhibit melanoma growth

Abstract Macrophages are abundant in the tumor microenvironment of solid tumors like melanoma, and while often pro-tumorigenic, macrophages also possess inherent anti-tumor capabilities. Recent studies have highlighted the potential of CAR-Ms, or chimeric antigen receptor expressing macrophages, to recognize and kill cancer cells. As both phagocytes and antigen-presenting cells, macrophages offer a unique toolset compared to cytotoxic CAR-T cells, potentially improving efficacy in solid tumors. We engineered primary human blood monocyte-derived macrophages to express CAR constructs with an scFV targeting chondroitin sulfate proteoglycan 4 (CSPG4), an antigen commonly overexpressed in solid tumors including melanoma and glioblastoma. Using melanoma as an initial model, we evaluated the impact of CSPG4-targeting CAR-Ms on melanoma growth in vitro and in vivo. We found that CSPG4-targeting CAR-Ms lead to increased phagocytosis of melanoma cells and increased melanoma cytotoxicity compared to control CAR-Ms. Furthermore, CSPG4-targeting CAR-Ms inhibit melanoma spheroid growth in 3D and inhibit melanoma growth in mice. Interestingly, priming CSPG4-targeting CAR-Ms with CSPG4-expressing cancer cells leads to increased phagocytosis and infiltration of melanoma spheroids compared to control CAR-Ms or unprimed CSPG4-targeting macrophages. Together, these results suggest that CSPG4-targeting CAR-M immunotherapy is a promising solid tumor immunotherapy approach for treating melanoma. Citation Format: Daniel Greiner, Minna Roh-Johnson. CSPG4-targeting CAR-macrophages inhibit melanoma growth [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 4818.