The Combination of Immunotherapy and Stereotactic Ablative Radiotherapy in MSS Oligometastatic Colorectal Cancer

This is a prospective, single-center, single-arm phase II clinical trial. This study aims to evaluate the safety and tolerability of stereotactic ablative radiotherapy (SABR) in combination with Sintilimab, and to examine the impact of the combination therapy on tumor control, long-term survival and quality of life in patients with microsatellite stable (MSS) oligometastatic colorectal cancer.
A total of 60 MSS oligometastatic colorectal cancer patients will be recruited and receive multisite SABR followed by immunotherapy of Sintilimab within one week from completion. Sintilimab will be given at a fixed dose of 200mg (100mg if weight < 50 kg) via intravenous infusion on the first day of each cycle, repeated every three weeks. The dosing will continue for up to two years until disease progression, unacceptable toxicity or patient withdrawal. The tumor regression, disease control, adverse events and long-term survival will be analyzed.