To evaluate the clinical efficacy and safety of TAS-102 combined with bevacizumab and tislelizumab in third-line or above treatment in patients with advanced colorectal adenocarcinoma with liver metastasis.

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.