STM-06: POLARIS-POlymetastic Lesion Ablative Radiotherapy With Immunotherapy Study

This is a non-randomized two-arm trial, specifically a pilot study in which patients with advanced solid tumor cancer with 3-10 metastatic lesions who are on immunotherapy will receive ablative RT to up to 10 lesions. After study intervention, participants will undergo ctDNA collection at 8 weeks after completion of ablative RT Post-treatment disease assessments, including imaging and serial ctDNA monitoring, as well as any additional treatments, will be at the discretion of the treating oncologist. Approximately 28 subjects (14 per cohort) will be enrolled. For subjects who do not complete the full planned course of RT for any reason, a final study visit should be performed approximately 30 days after the last fraction of radiation. If a subject is discontinued from the study with an ongoing adverse event or an unresolved clinically significant laboratory result, the clinical investigative team will attempt to provide follow-up until a satisfactory clinical resolution of the laboratory result or adverse event is achieved.