SBRT + PD-1 Monoclonal Antibody in Unresectable Colorectal Liver Metastases

Stereotactic body radiation therapy (SBRT) is a highly precise form of external beam radiation therapy used to treat tumors in various parts of the body. Enrolled patients will initiate SBRT treatment within 2 weeks after the first course of chemotherapy. Intensity-modulated radiation therapy (IMRT) will be used, with the gross tumor volume (GTV) receiving a dose of 8-12 Gy in 5 fractions, resulting in a total dose of 40-60 Gy. The biologically effective dose (BED) is equivalent to 72-132 Gy. The treatment will be administered from Monday to Friday.

PD-1 monoclonal antibody is a type of immunotherapy drug designed to treat various cancers by targeting the programmed death receptor-1 (PD-1) pathway.The PD-1 monoclonal antibody used in this study is sintilimab at a dose of 200 mg, administered via intravenous infusion on Day 1. Participants will be considered eligible only if they have completed four or more cycles of PD-1 monoclonal antibody treatment both before and after SBRT.

Chemotherapy regimens based on fluorouracil (5-FU), such as CAPOX with a 3-week cycle or mFOLFOX6/FOLFIRI/FOLFOXIRI with a 2-week cycle, may be combined with targeted therapy. During chemotherapy or chemoradiotherapy, optimal supportive care will be provided.