Fruquintinib Combined With Sintilimab ± Radiotherapy for Third-line Treatment of Colorectal Cancer With Liver Metastases

Inclusion Criteria: * ECOG PS 0-2 * Histologically confirmed colorectal adenocarcinoma with liver metastases (8th edition AJCC) * MSS/pMMR subtype * Previously received standard first- and second-line systemic anti-tumor therapy * At least one measurable lesion as defined by RECIST 1.1 criteria * Access to tumor samples for biomarker assessment * Expected survival of ≥3 months * Normal function of major organ systems (within 14 days before enrollment) * No systemic corticosteroid treatment within 7 days before treatment initiation, excluding physiological corticosteroid replacement therapy. * Fertile males or females with the potential for pregnancy must use highly effective contraception methods during the trial. Exclusion Criteria: * Patients diagnosed with malignancies other than colorectal cancer within 3 years prior to enrollment. * Participating in an interventional clinical study or receiving other investigational drugs or treatments with study devices within the past 4 weeks before enrollment. * Previously received the following therapies: anti-PD-1, anti-PD-L1, or anti-PD-L2 drugs, or drugs targeting another T cell co-stimulatory or co-inhibitory receptor (e.g., CTLA-4, OX-40, CD137), fruquintinib, etc. * Received traditional Chinese medicine or immune-modulating drugs with anti-tumor indications within the past 2 weeks before enrollment (excluding local use for controlling pleural effusion). * Experienced active autoimmune diseases requiring systemic therapy within the past 2 years before enrollment. Replacement therapy is not considered systemic therapy. * Diagnosed with immune deficiency or received systemic corticosteroid therapy or any other form of immunosuppressive therapy within 7 days before the first dose of investigational treatment. After consultation with the sponsor, the use of physiological doses of corticosteroids may be approved. * Received liver radiotherapy within the past 2 weeks before enrollment. * Known presence of central nervous system metastases and/or carcinomatous meningitis. * Received systemic corticosteroid therapy within 7 days before enrollment.