Tislelizumab With Fruquintinib, Metronidazole, in Mismatch Repair-proficient or Microsatellite Stability, Advanced Colorectal Cancer: a Multicenter, Single Arm, Clinical Trial

Criteria the registry did not label

• No gender limit, age ≥ 18 years old and ≤ 80 years old
• Colorectal cancer (AJCC stage IV) diagnosed by histological or cytological biopsy as metastatic or unresectable, with immunohistochemical or genetic testing indicating MSS or MSH-L type
• Treatment requires third line or above, has previously received standard first and second line treatment, and the disease has progressed after treatment
• Before accepting tirelizumab, qPCR should be used to detect the Fn CT value \< 35 in fecal samples, and Fn is confirmed positive by agarose gel electrophoresis or Sanger sequencing
• ECOG score: 0-1 points
• Baseline blood routine and biochemical indicators meet the following criteria (no blood transfusion or use of colony stimulating factors 2 weeks prior to screening) Blood routine: hemoglobin ≥ 90g/L, absolute neutrophil count (ANC) ≥ 1.5 × 109/L, platelet ≥ 100 × 109/L Liver function: ALT and AST ≤ 2.5 x ULN, serum total bilirubin ≤ 1.5 x ULN (if there is liver metastasis, ALT and AST ≤ 5 x ULN, serum total bilirubin ≤ 3 x ULN), serum albumin ≥ 30g/L Renal function: serum creatinine ≤ 1.5 x upper limit of normal (ULN), or creatinine clearance rate ≥ 50 mL/min (calculated according to Cockcroft Gault formula). 7. Those who voluntarily participate in the trial and sign an informed consent form.