Comparing Chidamide+Sintilimab+Bev With Standard Second-line FOLFIRI+Bev in Advanced MSS/pMMR mCRC

Subjects will be randomized in a 1:1 ratio into either the chidamide + sintilimab + bevacizumab group or the standard second-line FOLFIRI + bevacizumab therapy group. The treatment option for the chidamide + sintilimab + bevacizumab (study group) is 200 mg of sintilimab IV Drip Q3W, 30 mg of chidamide PO BIW, and bevacizumab 7.5 mg/kg IV Drip Q3W, with a maximum treatment duration of 2 years. The treatment option for the standard second-line FOLFIRI + bevacizumab therapy group (control group) is bevacizumab 5 mg/kg IV Drip Q2W, irinotecan 180 mg/m2 IV Drip Q2W, calcium folinate 400 mg/m2 IV Q2W or calcium levofolinate 200 mg/m2 IV Drip Q2W, 5-fluorouracil 400 mg/m2 IV +2400 mg/m2 CIV Q2W, with a maximum treatment duration of 2 years. The primary endpoint of this study is the progression-free survival (PFS), defined as the time from random assignment of the subject to disease progression or death from any cause. All eligible patients will be randomly assigned to either the trial or control group in a 1:1 ratio based on the following stratification factors: Whether the primary focus is located in the right-sided colorectum; Whether bevacizumab has been administered in the first-line treatment.