Induction of T cell dysfunction and NK-like T cell differentiation in vitro and in patients after CAR T cell treatment [scTCR-seq]

Chimeric antigen receptor (CAR) T cell therapy has achieved remarkable success in hematological malignancies but remains largely ineffective in solid tumors. A major factor leading to the reduced efficacy of CAR T cell therapy is T cell dysfunction, and the mechanisms mediating this dysfunction are under investigation. Here we establish a robust in vitro model to study mesothelin-redirected CAR T cell dysfunction in pancreatic cancer. Continuous antigen exposure results in hallmark features of exhaustion including reduced proliferation capacity and cytotoxicity, and severe defects in cytokine production. Here we identified a transcriptional signature at both population and single-cell levels in CAR T cells after chronic antigen exposure. In addition, TCR lineage tracing revealed a CD8+ T-to-NK-like T cell plasticity that results in reduced antigen- dependent tumor cell killing. The transcription factors SOX4 and ID3 are specifically expressed in the dysfunctional CAR NK-like T cells and are predicted to be master regulators of the dysfunction gene expression signature and of the post-thymic acquisition of an NK-like T cell fate. Finally, we identified the emergence of CAR NK-like T cells in a subset of patients after infusion of CAR T cells. The findings gleaned from this study reveal new approaches to improve the efficacy of CAR T cell therapy in solid tumors by preventing or revitalizing CAR T cell dysfunction and shed light on the plasticity of human CAR T cells. Examines presence of T cell receptor (TCR) peptides by single-cell sequencing in CD8+ T cells from two donors. One experimental variable: exposure (values: control day 0 and continuous antigen exposure).