ArriVent reports 44.8% response rate for ARR-217 in colorectal cancer

ArriVent BioPharma, Inc. disclosed initial Phase 1 data for its antibody-drug conjugate ARR-217, reporting a 44.8% objective response rate in patients with colorectal cancer treated at a dose of 6 mg/kg. The company presented these findings as an oral presentation at the 2026 European Society for Medical Oncology Congress. The data, based on a cutoff of August 5, 2026, indicates that 13 of 29 patients in that specific dosing cohort achieved an objective response.

ARR-217, also identified as MRG007, is a cadherin-17 (CDH17)-targeting antibody-drug conjugate developed in partnership with Lepu Biopharma Co., Ltd. ArriVent holds exclusive rights to develop and commercialize the drug worldwide outside of Greater China. The ongoing multicenter, open-label study, registered as NCT07066657, is conducted in the US and China to evaluate safety, tolerability, efficacy, and pharmacokinetics in patients with unresectable, locally advanced, or metastatic solid tumors. As of the data cutoff, 123 patients with heavily pretreated gastrointestinal malignancies had been treated across six dose levels ranging from 2 mg/kg to 8 mg/kg.

In addition to the primary endpoint in the 6 mg/kg cohort, the company reported a 93.1% disease control rate in that group. For patients receiving doses of 4 mg/kg or higher, the objective response rate was 34.2%, with a disease control rate of 91.8%. Bing Yao, Ph.D., Chief Executive Officer of ArriVent, stated that the responses observed in this heavily pretreated population, combined with a manageable safety profile, provide a foundation for advancing the drug into a Phase 1b dose optimization study. Yao noted that ARR-217 is the first ADC from the company's pipeline to enter clinical development.

The safety profile was generally characterized by Grade 1 and 2 treatment-related adverse events. Across all dose levels, 30.1% of patients experienced Grade 3 or higher treatment-related adverse events, with neutropenia occurring in 12.2% and diarrhea in 8.9%. In the specific cohort receiving 6 mg/kg every three weeks, Grade 3 or higher adverse events occurred in 20.4% of patients, including diarrhea in 2.0%. The company reported no Grade 5 treatment-related adverse events or interstitial lung disease.

ArriVent has advanced ARR-217 into a Phase 1b dose optimization study at doses of 5 mg/kg and 6 mg/kg administered every three weeks. The company expects to release further dose optimization data in 2027. A virtual webinar to discuss the ARR-217 program data is scheduled for Monday, October 26, 2026, at 8 am ET.