Targeting PTPN2 enhances human CAR T cell efficacy and the development of long-term memory in mouse xenograft models

Chimeric antigen receptor (CAR) T cells have been ineffective against solid tumors, where the hostile tumor microenvironment limits CAR T cell function and persistence. Protein tyrosine phosphatase N2 (PTPN2) attenuates T cell receptor and cytokine signaling to maintain T cell tolerance. Here, we used CRISPR-Cas9 gene editing or an inhibitor to target PTPN2 in human CAR T cells specific for the Lewis Y (LeY) neoantigen, which is expressed in most epithelial tumors. Targeting PTPN2 increased CAR and cytokine signaling, including interferon signaling, and enhanced the antigen-induced expansion, activation, and cytotoxicity of anti-LeY CAR T cells in vitro and in vivo. The deletion of PTPN2 in CAR T cells repressed the growth of human tumor and patient-derived xenografts in mice, when compared with unedited CAR T cells, and prolonged mouse survival. The administration of inhibitor also enhanced the ability of α-LeY CAR T cells to repress tumor growth. Cellular indexing of transcriptomes and epitopes by sequencing analysis of splenic PTPN2-deficient CD8⁺ CAR T cells in tumor-bearing mice revealed that PTPN2 deficiency favored the generation of CD45RA⁺ CAR T cells expressing markers of long-lived stem cell memory (SCM) CAR T cells. Flow cytometric analysis reaffirmed that the deletion or inhibition of PTPN2 promoted the intratumoral accumulation of SCM CD8⁺ CAR T cells and the overall persistence of CD8⁺ CAR T cells. These data support the use of gene editing or small-molecule inhibitors targeting PTPN2 in human CAR T cells to treat solid tumors.