AK112 Plus FOLFIRI Versus Bevacizumab Plus FOLFIRI as Second-line Treatment of MSS/pMMR Metastatic Colorectal Cancer

AK112：20mg/kg，Q2W。Administered over 60 minutes (±10 minutes). For intolerable cases, infusion duration may extend up to 120 minutes. During treatment, dosing delays are allowed for up to 12 weeks (calculated from the last dose). AK112 may be resumed after 12 weeks under the following conditions: If treatment is paused due to glucocorticoid tapering for managing immune-related adverse events (irAEs);If treatment is paused due to adverse events unrelated or deemed unrelated to AK112; Resumption is permitted only if the investigator judges continued therapy beneficial, following discussion with relevant medical personnel.

FOLFIRI：Irinotecan, 180 mg/m² IV over 30-90 minutes (Day 1); Leucovorin (LV), 400 mg/m² IV over 2 hours (Day 1); 5-FU, 400mg/m²IV Day1, then 1200 mg/(m².d) ×2 days (total 2400 mg/m² ,IV over 46-48 hours).Q2W.

Bevacizumab：5 mg/kg，Q2W. The initial intravenous infusion should last approximately 90 minutes. If the first infusion is well tolerated, the duration of the second infusion can be reduced to approximately 60 minutes. Should the participant also tolerate the 60-minute infusion well, then all subsequent infusions may be administered over a period of approximately 30 minutes. Continuous monitoring for potential infusion-related reactions during the drip is required; if an infusion-related reaction occurs, the infusion rate should be promptly reduced or the infusion temporarily halted.