Antengene Corporation Limited (SEHK: 6996.HK), a China-based, commercial-stage global biotech company focused on discovering, developing and commercialising medicines for hematologic malignancies and solid tumors, announced on Sunday that the latest results from the ongoing Phase I/II CLINCH study of ATG-022 (CLDN18.2 antibody-drug conjugate [ADC]) were presented in a Poster Presentation at the European Society for Medical Oncology Congress 2025 (ESMO 2025) in Berlin, Germany.

ATG-022 is a CLDN18.2-targeted ADC with sub-nM affinity and fast internalisation. Using a VC-MMAE linker-payload (DAR 4), ATG-022 has demonstrated potent activity across tumors with high, low, and 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 once every three weeks (0.3-3.0 mg/kg Q3W) to evaluate the safety, tolerability, and pharmacokinetics; CLDN18.2-positive (greater than or equal to IHC 1+, 1%) patients are treated at 1.8 mg/kg or 2.4 mg/kg in dose expansion to evaluate the efficacy and safety.

ATG-022 has been granted two Orphan Drug designations (ODDs) by the US Food and Drug Administration (FDA) for the treatment of gastric cancer and pancreatic cancer, and in August 2025 obtained Breakthrough Therapy Designation from China's National Medical Products Administration (NMPA) for treating CLDN18.2-positive, HER-2 negative unresectable or metastatic gastric or gastroesophageal junction adenocarcinoma (GC/GEJC) who have received at least two prior lines of therapy.

According to Antengene, 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. In addition to GC/GEJC, preliminary efficacy has been observed in other non-GI tumor types which will be reported at upcoming conferences.

Antengene said that 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. Antengene is also preparing for combination therapy studies involving ATG-022 to further advance its clinical development.