Antengene Advances ATG-022 Into Phase III Gastric Cancer Study

Shanghai and Hong Kong, PRC, September 21, 2026

Antengene Initiates Pivotal Phase III CLINCH-3 Trial

The CLINCH-3 study is a randomized, controlled, open-label, multicenter Phase III clinical trial evaluating the efficacy and safety of ATG-022 against treatment selected by investigators in patients with CLDN18.2-positive advanced gastric or GEJ adenocarcinoma. The study is led by Professor Lin Shen of Peking University Cancer Hospital and was initiated in China, with plans to expand into a multi-regional clinical trial (MRCT). The company said the study is intended to support a potential future application for ATG-022 as a monotherapy in this patient population.

ATG-022 previously received Breakthrough Therapy Designation (BTD) from the Center for Drug Evaluation of China’s National Medical Products Administration. According to Antengene, the designation supported regulatory communication and helped facilitate advancement of the pivotal clinical program. The first-patient dosing milestone follows earlier Phase I/II clinical evaluation of ATG-022 in patients with advanced gastric and GEJ adenocarcinoma.

Phase I/II Data Support Further ATG-022 Development

The Phase III program is supported by clinical findings reported from the earlier CLINCH Phase I/II studies. As of June 26, 2026, Antengene reported that patients with moderate-to-high CLDN18.2 expression receiving the recommended Phase II dose of 1.8 mg/kg achieved an objective response rate (ORR) of 46.7%, with a confirmed ORR of 40.0% and a disease control rate (DCR) of 86.7%. Median overall survival had not been reached after a median follow-up of 14.03 months in that group. The company also reported activity among patients with low or ultra-low CLDN18.2 expression treated at doses ranging from 1.8 to 2.4 mg/kg, with an ORR of 28.6% and a DCR of 52.4%. Multiple complete responses were also reported. These findings are from an earlier-stage clinical program and are being followed by the controlled Phase III study, which is intended to provide more definitive evidence of the investigational therapy’s efficacy and safety.

Antengene reported that the incidence of Grade 3 or higher treatment-related adverse events in the 1.8 mg/kg cohort was 21.0% at the June 2026 data cutoff, compared with 19.4% at the previous December 2025 cutoff. The company said the rate remained broadly stable despite additional treatment exposure and follow-up, while 9.7% of patients experienced dose reductions because of treatment-related adverse events.

Antengene Expands ATG-022 Development Strategy

Beyond CLINCH-3, Antengene is pursuing additional development pathways for ATG-022 in gastric cancer and other solid tumors. The company’s CLINCH-2 study is evaluating ATG-022 in the first-line setting in combination with standard-of-care chemotherapy and anti-PD-1 therapy, targeting a broader CLDN18.2-positive population. Meanwhile, a CLINCH basket study is investigating the candidate in CLDN18.2-positive non-gastric solid tumors. The company said these complementary studies are intended to explore the potential of ATG-022 across different treatment settings and tumor types. However, ATG-022 remains an investigational therapy, and its efficacy and safety in the Phase III setting have yet to be established. The CLINCH-3 trial will therefore be an important step in determining whether the encouraging earlier-stage findings translate into clinically meaningful outcomes in a larger controlled study.

The advancement of ATG-022 into Phase III clinical development represents another milestone for Antengene’s oncology pipeline and reflects the company’s broader focus on developing targeted therapies for cancers with significant unmet medical needs. The ongoing clinical program will provide additional evidence on the potential role of CLDN18.2-targeted ADC therapy in advanced gastric and GEJ adenocarcinoma.

Source: Antengene press release