Ablation of prostaglandin E2 signalling through dual receptor knockout in CAR T cells enhances therapeutic efficacy in solid tumours

Abstract The efficacy of chimeric antigen receptor (CAR) T cell therapy in solid cancers is limited by immunosuppression in the tumour microenvironment (TME). Prostaglandin E 2 (PGE 2 ) is a key factor locally inhibiting T cell function. We hypothesized that targeted ablation of PGE 2 signalling in CAR T cells may enhance their activity in PGE 2 -rich solid tumours. Here we generate knockout CAR T cells double deficient for the PGE 2 receptors EP2 and EP4 (EP2 −/− EP4 −/− ) by CRISPR–Cas9 engineering. EP2 −/− EP4 −/− CAR T cells expanded unabatedly in the presence of PGE 2 . Further, they effectively controlled syngeneic and human xenograft tumour models in vivo, which was accompanied by intratumoural accumulation and persistence of modified T cells. Improved anti-tumour activity was also observed against patient-derived tumour samples from patients with pancreatic ductal adenocarcinoma (PDAC), colorectal (CRC) and neuroendocrine (NET) cancer. Our data uncovers the detrimental impact of PGE 2 -mediated suppression on CAR T cell efficacy and highlights EP2 and EP4 targeting as a potential strategy.