Oncofetal TNC CAR T Cell Therapy for Pediatric Sarcoma

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Project Abstract The long-term goal of this project is to develop an adoptive immunotherapy with T cells expressing chimeric antigen receptors (CARs) for recurrent and refractory pediatric sarcoma, which prognosis remains poor. CAR T cell therapy has demonstrated success for hematological malignancies in clinical studies; however, CAR T cells have been less effective for solid tumors in the clinic. While limited efficacy is multifactorial, a significant roadblock for solid tumor CAR T cell therapy is the lack of targetable antigens. One prominent ECM protein is tenascin C (TNC), and cancer cells, including sarcoma cells, express oncofetal tenascin C (TNC) spice variants, which can contain an additional C domain (C.TNC). Since C.TNC expression correlates with the malignant phenotype of cancer cells, we posit that it is an ideal CAR target. In support of this application, we have generated a 2nd generation C.TNC-specific CAR with a CD28 costimulatory domain (C.TNC-CAR). I now hypothesize that C.TNC-CAR T cells recognize and kill C.TNC-positive tumor cells and can be optimized to have potent antitumor in preclinical pediatric sarcoma models. We have demonstrated in preliminary studies that C.TNC-CAR T cells recognize and kill C.TNC+ sarcoma cell lines in vitro. In this project now, we propose to investigate this hypothesis in two interrelated research aims. Aim 1 focuses on understanding the mechanism of our ECM-targeting C.TNC-CAR T cells, and Aim 2 then compares the effector function of C.TNC-CAR T cells in in vivo sarcoma xenograft models evaluating expansion, persistence, and anti-tumor activity. Techniques to be employed include flow cytometry, ELISAs, co-cultures and cytotoxicity assays, and CRISPR-Cas9 genome editing. This project was designed to train me in techniques to generate and characterize genetically modified T cells expressing CARs as well as introduce me into the evolving field of cancer cell therapy. This proposal and training will be performed at St. Jude Children’s Research Hospital, an NCI-designated comprehensive cancer center. If successful, the results of this proposal could have immediate applications for pediatric sarcomas. In addition, it should have a significant impact on a broad range of other pediatric and adult solid tumors that also express C.TNC.