TAS-102 Combined With Bevacizumab and Tislelizumab Third-line or Above in the Treatment of Liver Metastasis in Colorectal Cancer

Inclusion Criteria: * Patients who provided informed consent and voluntarily enrolled * Patients with liver metastasis of advanced colorectal adenocarcinoma with MSS confirmed by pathology; * 18-75 years old; * Measurable target lesions according to RECIST V1.1 assessment criteria; * Progression after standard second-line treatment (irinotecan, oxaliplatin, or fluorouracil); * 0 \~ 2 points according to ECOG quality of life score; * Drugs can be taken orally * Estimated survival ≥3 months; * Women of childbearing age should comply with contraceptive measures if pregnancy test is negative; * Ascites with no obvious symptoms and no clinical intervention; * Adequate organ and bone marrow functions, ecg, blood, biochemical and other basic tests are not contraindications of chemotherapy; * Adherence to scheduled visits, treatment plans, laboratory tests, and other study procedures Willingness and ability. Exclusion Criteria: * Previous application of TAS-102; * Pregnant or lactating women; * No contraception during the reproductive period; * patients known to have a history of allergy to any study drug, similar drug or excipient; * Patients with risk of massive gastrointestinal bleeding or gastrointestinal obstruction; * Patients with a history of thromboembolism, except those caused by PICC; * Patients with active infection; * Patients with uncontrolled hypertension (systolic blood pressure ≥160 mmHg and diastolic blood pressure ≥90) MmHg); * Patients with brain metastases with clinical symptoms or imaging evidence; * Contraindications for treatment of other chronic diseases; * Previous immunotherapy-related myocarditis, pneumonia, colitis, hepatitis, kidney Inflammation and other conditions, the current AE is still ≥2; * According to THE NCI CTCAE 5.0 assessment criteria, there are all types of existing cases due to previous treatment Patients with grade ≥2 toxic reactions; * Other conditions that the investigator determines are not suitable for inclusion in the study. * Received any anti-tumor therapy and participated in other clinical studies within 4 weeks prior to enrollment.