Antennova presented the latest data from its Phase I/II CLINCH study, evaluating ATN-022, a CLDN18.2 antibody-drug conjugate (ADC), in patients with advanced or metastatic gastric cancer, at the American Society of Clinical Oncology Gastrointestinal Cancers Symposium 2025 (ASCO GI 2025). The results indicate promising antitumor activity and a manageable safety profile.
The CLINCH study, conducted in China and Australia, included a dose escalation phase followed by a dose expansion phase. As of November 22, 2024, data from 21 gastric cancer patients in the dose expansion phase with CLDN 18.2 expression of IHC 2+ ≥ 20% who had at least one tumor evaluation showed an overall response rate (ORR) of 42.9% and a disease control rate (DCR) of 95.2%. This included 9 partial responses (PRs), with 8 confirmed PRs, and 11 stable diseases (SDs).
In a separate cohort of 10 gastric cancer patients with CLDN 18.2 expression of IHC 2+ < 20% treated at efficacious doses of 1.8 – 2.4 mg/kg, the ORR was 30.0% (1 complete response [CR] and 2 PRs, all PR/CR were confirmed with CLDN 18.2 expression of IHC 2+ < 5%), and the DCR was 50.0%. Notably, the patient with CR demonstrated a durable response, remaining on the study for over 14 months as of the data cutoff.
ATN-022: Targeting CLDN18.2 in Gastric Cancer
ATN-022, also known as ATG-022, is designed to target CLDN18.2, a member of the Claudin family of cell adhesion molecules. CLDN18.2 is often overexpressed in various primary malignant tumors, including gastric, esophageal, cholangiocarcinoma, and pancreatic cancers. The U.S. Food and Drug Administration (FDA) has granted Orphan Drug Designations to ATN-022 for both gastric and pancreatic cancers.
The observed efficacy across various levels of CLDN18.2 expression in gastric cancer patients suggests that ATN-022 could become a competitive treatment option. Enrollment of gastric cancer patients for dose optimization and patients with other solid tumors is ongoing in China and Australia, according to Antennova.
