On October 20, 2025 Antengene Corporation Limited ("Antengene", SEHK: 6996.HK) reported the latest results from the ongoing Phase I/II CLINCH study of ATG-022 (CLDN18.2 ADC), were presented in a Poster Presentation at ESMO (Free ESMO Whitepaper) 2025.

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Details of the Poster Presentation:
Title: Phase I/II study of CLDN18.2 ADC ATG-022 in patients with advanced gastric/gastroesophageal junction cancer (CLINCH)
Abstract Number: 2907
Presentation Number: 2113P

ATG-022 and CLINCH Study Overview

ATG-022 is a CLDN18.2-targeted ADC with sub-nM affinity and fast internalization. Using a VC-MMAE linker-payload (DAR 4), ATG-022 has demonstrated potent activity across tumors with high/low/ultra-low CLDN18.2 expression.
The ongoing Phase I/II CLINCH study consists of dose escalation and dose expansion phases. In dose escalation, patients with advanced solid tumors regardless of CLDN18.2 expression receive ATG-022 (0.3-3.0 mg/kg Q3W) to evaluate safety, tolerability, and pharmacokinetics; CLDN18.2-positive (≥IHC 1+, 1%) patients are treated at 1.8 or 2.4 mg/kg in dose expansion to evaluate the efficacy and safety.
Key Results Presented

Efficacy:
Among GC/GEJC patients with moderate/high CLDN18.2 expression (IHC 2+ >20%), the 2.4 mg/kg dose cohort observed 1 CR, 11 PRs and 15 SDs, resulting in 40% ORR (12/30) and 90% DCR (27/30). The median PFS was 6.97 months and the 12-month OS rate was 66.2%. In the 1.8 mg/kg dose cohort, there were 1 CR, 9 PRs, and 11 SDs, giving a 40% ORR (10/25) and 84% DCR (21/25).
Among GC/GEJC patients with low/ultra-low CLDN18.2 expression (IHC 2+ ≤20%), patients treated at the efficacious dose of 1.8-2.4 mg/kg achieved 1 CR and 5 PRs, resulting in 33.3% ORR (6/18) and 50%DCR (9/18). The CR patient has demonstrated durable response and has been on the study for 22+ months.
Safety:
At 2.4 mg/kg in the dose expansion, 45.8% of patients had ≥1 TEAEs, 60.4% of patients had grade ≥3 TEAEs.
In the dose-expansion phase, the 1.8 mg/kg cohort demonstrated excellent safety and tolerability, with only 13.6% of patients reporting serious TEAEs and 18.2% reporting Grade ≥3 TEAEs. The favorable safety profile of this dose level support its potential use in first-line combination regimens with chemotherapy and immune checkpoint inhibitors.
Conclusions and Outlook

ATG-022 demonstrated a manageable safety profile and encouraging antitumor effects in GC/GEJC adenocarcinoma patients with a broad range of CLDN18.2 expressions, thus supporting further clinical investigation in patients with variable CLDN18.2 expressions.
Preliminary efficacy has also been observed in other non-GI tumor types which will be reported at upcoming conferences.
The 2.4 mg/kg cohort showed a favorable safety profile, while the 1.8 mg/kg cohort demonstrated even better safety and tolerability. These findings provide strong support for advancing ATG-022 in combination with immune checkpoint inhibitors and chemotherapy in first-line treatment settings, paving the way to significantly expand its clinical reach and commercial potential.

(Press release, Antengene, OCT 20, 2025, View Source [SID1234656837])