Radiation jolt may wake up fading immunotherapy

This study tests whether precise, high-dose radiation (stereotactic radiotherapy) can restore the effectiveness of anti-PD1 immunotherapy in patients with metastatic solid tumors. Participants are those who initially responded well to immunotherapy for at least 6 months but then saw their cancer progress. The radiation is given in three short sessions to one tumor, with the hope that it triggers an 'abscopal effect'—shrinking not only the treated tumor but also other distant metastases. The study enrolls 35 patients and measures tumor response at 3 months.