Regorafenib Alone or in Combination With High/Low-dose Radiotherapy Plus Toripalimab for Metastatic Colorectal Cancer

The study compares the efficacy and safety of regorafenib alone or in combination with stereotactic ablative radiotherapy (SABR) and low-dose radiotherapy (LDRT) plus toripalimab in patients with microsatellite stable metastatic colorectal cancer (MSS mCRC). Patients are randomly assigned (1:1) into the control arm and the experimental arm. Control arm: a total of 45 patients will receive regorafenib monotherapy. Experimental arm: a total of 45 patients will first receive 1 cycle of regorafenib and toripalimab followed by SABR/LDRT radiotherapy. Regorafenib and toripalimab will be continued after the completion of radiotherapy. The objective response rate (ORR), survival benefits, and adverse effects will be analyzed.