ArriVent's ARR-217 ADC hits 44.8% ORR in late-line CRC at ESMO

Phase 1 data for the CDH17-targeted ADC showed a 44.8% objective response rate at the 6 mg/kg dose in heavily pretreated colorectal

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ArriVent BioPharma presented initial Phase 1 data for ARR-217, its cadherin-17 (CDH17)-targeted antibody-drug conjugate (ADC), at the European Society for Medical Oncology Congress in October 2026, reporting a 44.8% objective response rate at the 6 mg/kg dose level in patients with previously treated colorectal cancer.

The results come from an ongoing multicenter, open-label study conducted across sites in the United States and China. As of the 5 August data cutoff, 123 patients with heavily pretreated gastrointestinal malignancies had been dosed across six cohorts ranging from 2 mg/kg to 8 mg/kg. The colorectal cancer subgroup, comprising 113 of those patients, was the primary focus of the efficacy readout.

Trial results

At the 6 mg/kg every-three-weeks dosing schedule, 13 of 29 evaluable CRC patients achieved an objective response, including seven confirmed partial responses. Disease control rate at that dose reached 93.1%. Broadening the analysis to all patients treated at 4 mg/kg or above, the ORR across 73 CRC patients was 34.2%, with a disease control rate of 91.8%.

On safety, 30.1% of patients across all doses experienced Grade 3 or higher treatment-related adverse events, with neutropenia at 12.2% and diarrhoea at 8.9% as the most common. At the 6 mg/kg dose specifically, Grade 3 or higher events fell to 20.4%. No Grade 5 events and no cases of interstitial lung disease were observed, the latter being a notable signal given that ILD has been a class-level concern for certain ADC payloads.

Bing Yao, chief executive of ArriVent, said the responses in a heavily pretreated population, combined with a manageable safety profile, provided "a strong foundation for advancing ARR-217 into a Phase 1b dose optimisation study," with further data from 5 mg/kg and 6 mg/kg cohorts expected in 2027.

Market context

ARR-217 targets CDH17, a cell-adhesion molecule that is overexpressed across colorectal and other gastrointestinal cancers but shows limited expression in healthy tissue, making it an attractive ADC target. ArriVent licensed ex-Greater China rights from Lepu Biopharma under a collaboration deal; the asset is also known as MRG007.

The ADC space has grown rapidly in oncology following regulatory successes with trastuzumab deruxtecan and sacituzumab govitecan, and gastrointestinal cancers represent an area of active development interest. Late-line CRC in particular remains a setting with limited approved options beyond regorafenib, TAS-102, and pembrolizumab in microsatellite-instability-high tumours, giving novel mechanisms room to differentiate on both efficacy and tolerability.

Several other CDH17-targeting and broader GI-focused ADC programmes are in early clinical or preclinical stages at smaller biotechs and larger pharmaceutical companies, meaning ArriVent will need the Phase 1b dose-optimisation data, and eventually randomised evidence, to support a competitive profile. The 44.8% ORR at 6 mg/kg is an encouraging early signal, but the patient numbers at individual dose levels remain small and the dataset includes a mix of confirmed and unconfirmed responses. Investors and clinicians will look to 2027 readouts for a more mature efficacy and durability picture.

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