Adoptive cell therapy with chimeric antigen receptor (CAR) engineered T lymphocytes has recently shown great success for the treatment of hematologic malignancies. Similar strategies based on enhancing T cell function and redirecting these lymphocytes against solid tumors are being developed, however, early attempts have resulted in unexpected toxicity of normal cells expressing shared antigen or cross-reactive antigens. A primary challenge in translating new CARs to therapeutic platforms is the lack of robust models to predict potential adverse events pre-clinically. To address this challenge, we developed an in vitro system consisting of thirteen expanded primary human cell types. To detect potential off-tumor on-target effects on normal tissues, we co-cultured CARs directed against human epidermal growth factor receptor (EGFR) in our primary cell panel. Flow cytometric and chromium release assays were used to measure intracellular cytokine production by effectors and specific cell lysis of targets, respectively. T cells expressing a CAR against wild-type EGFR elicited strong effector cytokine production and effectively lysed both tumor and normal cells expressing EGFR. In contrast, T cells engineered to express a humanized CAR against mutant EGFR variant III (EGFRvIII), a tumor-specific antigen, reacted only with tumors and did not react to the panel of primary cell targets. This demonstrated a lack of potential cross-reactivity related to off-tumor on-target effects in the normal cell types represented here, suggesting improved safety for clinical use. The thirteen primary cell types we have generated form a panel of normal cells to test novel CAR T cells for potential toxicity and an adequate therapeutic index prior to first-in-human studies.
Citation Format: Alexandria P. Cogdill, Alina Boesteanu, Kathleen Haines, Joseph Fraietta, John Scholler, Andreas Loew, Pramod Thekkat, Jennifer Brogdon, Marcela V. Maus, Carl June, Laura A. Johnson. A biologic screen to evaluate potential toxicity of chimeric antigen receptor modified T cells against primary normal human tissues. [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy: A New Chapter; December 1-4, 2014; Orlando, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2015;3(10 Suppl):Abstract nr B05.
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