Abstract 3151: T cells engineered to express a chimeric antigen receptor targeting chondroitin sulfate proteoglycan 4 (CSPG4) specifically kill medulloblastoma and produce inflammatory cytokines

Abstract

Abstract Human T-cells expressing chimeric antigen receptors (CARs) recognizing common cancer antigens have shown great promise in the clinic with the potential for significant anti-tumor responses. CSPG4 is a chondroitin sulfate proteoglycan previously shown to be overexpressed in melanoma and breast cancer, as well as glioblastoma stem cells. CARs directed against CSPG4 have recently shown promising pre-clinical efficacy against these tumors. We evaluated the feasibility of targeting CSPG4 using CAR T cell therapy in medulloblastoma and neuroblastoma. Response to standard therapies for advanced neuroblastoma and medulloblastoma is poor and carries significant toxicities, which may be ameliorated by immunotherapy. We found that multiple medulloblastoma and neuroblastoma cell lines (DAOY, D283 Med, D425 Med, UW-228, and SKNAS) express CSPG4 at high levels, as does 143b osteosarcoma as a positive control. By contrast, CSPG4 in normal tissue is expressed only on pericytes and in low levels on small bowel as previously assessed by protein array [Beard et al, J Immunother Cancer 2014]. To evaluate therapeutic efficacy, a second generation CAR with a CD3ζ signaling domain and CD28 co-stimulatory domain containing the TP41.2 anti-CSPG4 scFv was transduced using a γ-retrovirus into T cells. CAR T cells were found to specifically kill 20% of DAOY, 50% of D283 Med, and 50% of 143b cancer cells at a 20:1 effector-to-target ratio in a 4-hour chromium release cytotoxicity assay, while not affecting CSPG4 negative control SY5Y (neuroblastoma) and DND41 (T cell leukemia) cells. Both CD4 and CD8 CAR T cells were also shown to produce IFNγ after exposure to 143b cells. Cytokine production in response to other CSPG4+ lines is ongoing as are cytotoxicity studies with neuroblastomas. For our in vivo model, we have begun to evaluate the efficacy of CAR T cells delivered either intravenously or via intratumoral injection against DAOY and D283 Med cells that have been orthotopically implanted in the cerebellum of immunodeficient NOD/SCID/IL2Rγ-/- mice. These results, if successful, will inform the development of a new clinical protocol for the treatment of children and young adults with medulloblastoma and neuroblastoma. Citation Format: Christopher M. Rota, Nicholas Tschernia, Steven Feldman, Crystal Mackall, Daniel W. Lee. T cells engineered to express a chimeric antigen receptor targeting chondroitin sulfate proteoglycan 4 (CSPG4) specifically kill medulloblastoma and produce inflammatory cytokines. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3151. doi:10.1158/1538-7445.AM2015-3151