Patients with recurrent or metastatic advanced colorectal cancer (mCRC) often face the clinical dilemma as this unresectable disease is continuously progressing and endangering the patients' lives. In the current study, we explored the clinical feasibility of KH903 in combination with FOLFIRI chemotherapy as a new clinical indication for mCRC.Patients (N = 122) were randomized 1:1 to 4mg/kg q1w KH903 or 5mg/kg q2w KH903, and both groups of patients were treated with the fixed regimen of FOLFIRI (every 2 weeks) along with the KH903 therapy. The primary endpoint was progression-free survival (PFS), and the secondary endpoints were Overall Survival (OS), objective response rate (ORR), and disease control rate (DCR).As of December 30, 2020, median (m)PFS was 5.68 months (95% CI, 4.67-7.13) with 4mg/kg q1w versus 5.19 months (95% CI, 4.04, 5.78) with 5mg/kg q2w (HR, 0.76; 95% CI, 0.50-1.16),and mOS was 13.14 months (95% CI, 10.61-19.52) versus 16.03 months (95% CI, 10.28- NE), respectively (HR, 1.11; 95% CI, 0.65-1.89), The ORR was 15.9% and 11.9% for both groups, respectively, and The DCR for both groups was 85.7% and 83.1%, respectively. Grade 3 or higher treatment-related adverse event rates for both groups were 68.3% vs.52.5%, respectively.KH903 in combination with FORFIRI in second-line treatment of patients with mCRC showed prolonged mPFS and mOS, comparing to the similar agents (Avastin®, ZALTRAP®, Cyramza®) and no new safety signals were observed.Copyright © 2024. Published by Elsevier Inc.