Phase II Study of Irinotecan Liposomes in First-line Treatment of Metastatic Colorectal Cancer

Inclusion Criteria: * 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. Exclusion Criteria: * Known or suspected central nervous system metastasis. * Received irinotecan/irinotecan liposomes/bevacizumab before enrollment. * Had undergone surgery and other oncologic treatments within the first 4 weeks of enrollment. * Previous treatment-related toxicity didn't return to NCI-CTCAE v5.0 I or below(except hair loss and peripheral neuropathy). * The use of CYP3A, CYP2C8, and UGT1A1 inhibitors or inducers couldn't be discontinued or were not discontinued within 2 weeks prior to enrollment. * Severe gastrointestinal dysfunction, gastrointestinal perforation, intraperitoneal abscess, and fistula. * Intestinal obstruction, signs and symptoms of intestinal obstruction, or the stent has been previously implanted and the stent has not been removed before the screening period. * Interstitial lung disease. * Tendency of arterial embolism and massive bleeding within 6 months before enrollment (except surgical bleeding). * Patients with fluid accumulation that couldn't reach a stable state but small amount of ascites on imaging without clinical symptoms could be enrolled. * Any serious or uncontrolled systemic disease, including uncontrolled high blood pressure, heart disease, active bleeding, active viral infection, etc. * Have had other malignancies within the past 5 years or currently, except cured cervical carcinoma in situ, uterine carcinoma in situ, and non-melanoma skin cancer. * Patients of childbearing age who refuse to take contraceptives, women who are pregnant or breastfeeding. * The researchers didn't consider it appropriate to participate in this study.