Study to Test Stereotactic Radiotherapy with Anti-PD1 Immunotherapy in Adults with Metastatic Solid Tumors Showing Progression After Initial Response

What this Trial Is About

Researchers are evaluating stereotactic radiotherapy to restore the effectiveness of anti-PD1 immunotherapy in patients with metastatic solid tumors who initially responded well to immunotherapy for more than six months but later experienced disease progression. The study focuses on the abscopal effect, where radiation to one tumor site may impact other untreated metastases. Participants will receive stereotactic radiotherapy in three sessions, each delivering 8 Gy of radiation lasting about 20 minutes, spaced 72 hours apart on Day 1, Day 4, and Day 7. This treatment is given alongside ongoing anti-PD1 immunotherapy. Prior to radiotherapy, a CT scan without contrast is performed to plan precise treatment. The radiotherapy device is used according to its approved medical indications. During the study, participants will be closely monitored with assessments up to 12 months after radiotherapy. Researchers will measure tumor response using iRECIST and RECIST 1.1 criteria on both irradiated and untreated lesions to evaluate the abscopal effect. They will also track progression-free survival, overall survival, adverse events, and timing of any new systemic treatments. The primary outcome is the objective response rate at 3 months post-radiotherapy in patients with confirmed progression after initial immunotherapy response.

A Study to Assess the Ability of Stereotactic Radiotherapy to Restore the Efficacy of Immunotherapy in Patients With Metastatic Cancer.