P2RY2 is a purinergic immune checkpoint linking extracellular ATP to immune evasion and adaptive resistance to immunotherapy

Extracellular ATP (eATP) accumulates substantially in the tumor microenvironment (TME) and rises further during immunotherapy. While canonically an immune-activating "danger" signal, eATP also promotes immunosuppression in tumors, thus far largely attributed to its metabolite, adenosine. Here, we identify direct eATP signaling through P2RY2 as a dominant, adenosine-independent mechanism of immune resistance. Specifically, eATP-P2RY2 signaling serves as the primary upstream driver of COX-1/2 upregulation and consequent accumulation of immunosuppressive PGE2 in the TME, uncovering the long-sought TME-specific trigger of pathological COX-PGE2 hyperactivation in solid tumors. Genetic deletion or pharmacologic inhibition of P2RY2 eliminates both baseline and therapy-induced intratumoral PGE2, restores antitumor T cell responses, and reverses resistance to CAR-T, TCR-T, checkpoint blockade, and TIL therapies. Given that persistently elevated eATP is a hallmark of solid tumors, our work reveals a fundamental mechanism by which tumors hijack innate "danger" signaling to establish immune suppression and develop adaptive resistance to immunotherapy. These findings establish P2RY2 as a purinergic immune checkpoint with translational potential for combinatorial cancer immunotherapies. HIGHLIGHTSO_LIeATP in the TME drives baseline and therapy-induced immune evasion via P2RY2 C_LIO_LIeATP-P2RY2 signaling is the primary cause of PGE2 accumulation in the TME C_LIO_LIP2RY2 propels a feedback loop that enforces adaptive resistance to immunotherapies C_LIO_LIP2RY2 blockade reprograms the TME and restores immunotherapy responsiveness C_LI