• 18\

⁃ 85 years old.

• Histopathologically confirmed patient with an inoperable metastatic colorectal adenocarcinoma.

• RAS/BRAF v600e mutant or right half colon cancer is known.

• pMMR/MSS is known.

• The unresectable stage of metastatic disease has not received any systemic antitumor therapy.

• For subjects previously receiving neoadjuvant or adjuvant therapy, the date of first discovery of disease progression must be at least 6 months removed from the date of last administration of neoadjuvant or adjuvant therapy.

• ECOG 0\

⁃ 1, patients ≥75 years old need an ECOG score of 0

• The presence of at least 1 measurable lesion that can be evaluated according to the RECIST v1.1 criteria.

• Normal bone marrow and organ function: ① Neutrophils (ANC) ≥1.5×10\^9/L, platelets (PLT) ≥100×10\^9/L, hemoglobin (Hb) ≥80g/L, albumin (ALB) ≥30 g/L, white blood cells (WBC) ≥3.0×10\^9/L, and no bleeding tendency; ② AST, ALT and alkaline phosphatase (ALP) were all ≤2.5× upper limit of normal range (ULN), and ≤5×ULN when liver metastases occurred; The total bilirubin level doesn't exceed the upper limit of the agency's normal range; Serum creatinine (Cr) ≤1.5×ULN or creatinine clearance ≥40 ml/min (calculated according to Cockroft-Gault)

• Understand the situation of this study, patients and/or legal representatives voluntarily agree to participate in this study and sign informed consent form.