CRISPR discovery platforms for T cell therapies

Adoptive T cell therapies have been transformative in treating a subset of hematological malignancies. However, many patients fail to respond or face relapse, with even more limited success in treating solid tumors. Targeted gene editing has the potential to enhance T cell therapeutic function and improve clinical responses. We recently developed a platform for CRISPR KO screens in primary human T cells which nominated RASA2 as a therapeutic target for T cell engineering. Here, we identify RASA2 as a signaling checkpoint in human T cells that is downregulated upon acute TCR stimulation but increases gradually with chronic antigen exposure. RASA2 ablation enhanced sensitivity to antigen and also improved both T cell acute effector function and long-term persistence. Antigen titration showed that RASA2 ablation enhances MAP kinase signaling and CAR-T cell cytolytic activity in response to low antigen levels. Repeated tumor antigen stimulation revealed that RASA2-deficient TCR-T and CAR-T cells show a striking advantage in persistent cancer-killing in vitro. Deletion of RASA2 in multiple preclinical models of TCR- and CAR-T cell therapies prolonged survival across animals xenografted with either liquid or solid tumors. Our findings from multiple genome-wide screens and preclinical studies highlight RASA2 as a promising new target to enhance both persistence and effector function in TCR-T and CAR-T cell therapies for cancer treatment.