Evaluation of the Efficacy and Safety of Bevacizumab Combined With PD-1 Monoclonal Antibody in Preoperative Neoadjuvant Therapy for MSS Colorectal Cancer With Liver Metastases

Inclusion Criteria:

1. Men and women aged 18-75 years old;
2. Histologically or radiographically proven colon or rectal adenocarcinoma with liver metastases；
3. ECOG performance status score of 0 to 2；
4. Clinical staged any T with liver metastases (M+);
5. MSS status;
6. Adequate haematological, hepatic, and renal function: neutrophil count ≥1.5×109 /L; platelet count ≥75×109 /L; serum total bilirubin ≤1.5×upper normal limits (UNL); aspartate aminotransferase ≤2.5×UNL; alanine aminotransferase ≤2.5×UNL; serum creatinine ≤1.5 x UNL.

Exclusion Criteria:

1. MSI status;
2. Colorectal cancer without liver metastases;
3. Relapsed colorectal cancer;
4. Complicated with active bleeding, perforation, or requiring emergency surgery;
5. Previous systemic anticancer therapy for colorectal cancer disease;
6. Any active or history of autoimmune disease, or history of syndrome that required systemic steroids or immunosuppressive medications;
7. Patients with other active concurrent non-colorectal cancer;
8. Patients with interstitial lung disease, non-infectious pneumonia or uncontrollable systemic diseases (such as: diabetes, hypertension, pulmonary fibrosis and acute pneumonia);
9. Patients with any Grade 2 or above toxicity as classified by the common terminology criteria for adverse events (CTCAE) (version 5.0) (except for anemia, alopecia and skin pigmentation) which is induced by previous treatment and has not subside;
10. Previously received anti-programmed death-1 (PD-1) or its ligand (PD-L1) antibody, anti- cytotoxic T lymphocyte-associated antigen 4 (cytotoxic T-lymphocyte-associated Protein 4, CTLA-4) antibody Women in pregnancy or lactation;
11. Known positive history or positive test for Human Immunodeficiency Virus or Acquired Immunodeficiency Syndrome (AIDS);
12. History of known or suspected allergies to any related drugs used in the trial; Women who are pregnant or nursing.