Gasdermin E–mediated target cell pyroptosis by CAR T cells triggers cytokine release syndrome

TLDR

Cytokine release syndrome (CRS) limits the efficacy of CAR T‑cell therapy in cancer patients, yet its underlying mechanism is poorly understood. This study demonstrates that tumor‑cell pyroptosis initiates CRS during CAR T‑cell therapy. CAR T cells secrete granzyme B, which activates caspase‑3 in target cells to cleave gasdermin E, triggering pyroptosis; the resulting factors activate macrophage caspase‑1 to cleave gasdermin D, releasing cytokines that drive CRS. Knocking out GSDME, depleting macrophages, or inhibiting caspase‑1 abolishes CRS in mouse models, while in patients GSDME and lactate dehydrogenase levels correlate with CRS severity and the amount of perforin/granzyme B released by CAR T cells determines pyroptosis induction.

Abstract

Cytokine release syndrome (CRS) counteracts the effectiveness of chimeric antigen receptor (CAR) T cell therapy in cancer patients, but the mechanism underlying CRS remains unclear. Here, we show that tumor cell pyroptosis triggers CRS during CAR T cell therapy. We find that CAR T cells rapidly activate caspase 3 in target cells through release of granzyme B. The latter cleaves gasdermin E (GSDME), a pore-forming protein highly expressed in B leukemic and other target cells, which results in extensive pyroptosis. Consequently, pyroptosis-released factors activate caspase 1 for GSDMD cleavage in macrophages, which results in the release of cytokines and subsequent CRS. Knocking out GSDME, depleting macrophages, or inhibiting caspase 1 eliminates CRS occurrence in mouse models. In patients, GSDME and lactate dehydrogenase levels are correlated with the severity of CRS. Notably, we find that the quantity of perforin/granzyme B used by CAR T cells rather than existing CD8+ T cells is critical for CAR T cells to induce target cell pyroptosis.