Abstract PR04: CRISPR-mediated PTPN2 deletion in CAR T cells enhances anti-tumor efficacy

Abstract Chimeric Antigen Receptor T cell (CAR T) immunotherapy has been remarkably successful in the treatment of B-Cell Acute Lymphoblastic Leukemia (B-ALL). However, beyond hematological malignancies, CAR T cells have been ineffective in treating solid tumors. Novel approaches for enhancing the ability of CAR T cells to combat solid tumors are urgently required. Protein tyrosine phosphatases (PTPs) are enzymes that regulate a wide range of physiological processes including metabolism, cellular growth, proliferation and differentiation by controlling tyrosine phosphorylation-dependent signaling. PTPs are key regulators of T cell signaling and contribute to the maintenance of immune tolerance. Studies from our group have shown that PTPN2 plays pivotal role in negatively regulating T cell receptor (TCR) signaling by dephosphorylating and inactivating the Src family protein tyrosine kinase LCK (Wiede, Shields et al. 2011). PTPN2 also attenuates cytokine signaling by dephosphorylating JAK-1, JAK-3 and their target substrates STAT-1, -3 and -5 in a cell context-dependent manner (Simoncic, Lee-Loy et al. 2002, ten Hoeve, de Jesus Ibarra-Sanchez et al. 2002, Wiede, Shields et al. 2011, Wiede, La Gruta et al. 2014). Since CARs signal via LCK, and cytokine signaling is critical for CAR T cell function, we postulated that inhibiting PTPN2 might bolster the anti-tumor activity of CAR T cells. Here we used CRISPR-Cas9-ribonucleoprotein (RNP)-mediated genome editing to delete PTPN2 in CAR T cells. Using this approach PTPN2 was efficiently deleted in CAR T cells and the deletion of PTPN2 significantly enhanced the anti-tumor efficacy of CAR T cells in vitro and in vivo. This abstract is also being presented as Poster P004. Citation Format: Xin Du, Florian Wiede, Phillip K. Darcy, Tony Tiganis. CRISPR-mediated PTPN2 deletion in CAR T cells enhances anti-tumor efficacy [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2021 Oct 5-6. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(1 Suppl):Abstract nr PR04.