FLASH radiation reprograms lipid metabolism and macrophage immunity and sensitizes medulloblastoma to CAR-T cell therapy.

FLASH radiotherapy holds promise for treating solid tumors given the potential lower toxicity in normal tissues but its therapeutic effects on tumor immunity remain largely unknown. Using a genetically engineered mouse model of medulloblastoma, we show that FLASH radiation stimulates proinflammatory polarization in tumor macrophages. Single-cell transcriptome analysis shows that FLASH proton beam radiation skews macrophages toward proinflammatory phenotypes and increases T cell infiltration.