Metabolic reprogramming through PIM3 inhibition reverses hypoxia-induced CAR-T cell dysfunction in solid tumors.

backgroundChimeric antigen receptor (CAR)-T cell therapy has shown remarkable success in hematologic malignancies but faces significant challenges in solid tumors due to the immunosuppressive tumor microenvironment (TME). Among these, hypoxia plays a vital role, yet the molecular mediators that link hypoxia to CAR-T dysfunction remain incompletely understood.

methodsAnti-mesothelin (MSLN) CAR-T cells were cultured under normoxic (21% O

resultsHypoxia reduced CAR-T proliferation, increased apoptosis, lowered memory phenotypes, raised exhaustion, and weakened cytotoxicity in short-term and long-term assays. Transcriptomic and metabolic analyses showed metabolic reprogramming with increased glycolysis and reduced oxidative phosphorylation. Among the dysregulated genes, the serine/threonine-protein kinase PIM3 emerged as a previously underexplored mediator of hypoxia-driven dysfunction. Genetic or pharmacologic inhibition of PIM3 counteracted hypoxia-induced impairment, enhancing memory phenotypes of CAR-T cells, and improving their anti-tumor activity both in vitro and in vivo.

conclusionsThis work identifies PIM3 as a previously underexplored target that links hypoxia to CAR-T cell dysfunction and demonstrates that PIM3 inhibition can reverse these effects. These findings provide a mechanistic rationale for incorporating PIM3 inhibition into CAR-T cell manufacturing or engineering to improve their therapeutic potential in hypoxic solid tumors.