On Oct 19, 2025, at the European Society for Medical Oncology (ESMO) Annual Congress in Berlin, Germany, AskGene Pharma Inc—a subsidiary of ASK Pharm—presented updated clinical data in a poster presentation on its investigational biologic ASKB589 (CLDN18.2-targeting mAb) plus CAPOX/PD-1 inhibitor in first-line treatment of advanced gastric cancer.
The data disclosed at ESMO further confirm the significant and durable antitumor activity of the ASKB589 triple-combination report, for the first time, OS benefit in patients with previously untreated advanced G/GEJ adenocarcinoma expressing CLDN18.2 at medium-to-high levels:
For patients with CLDN18.2 moderate-to-high expression Phase IV G/GEJ adenocarcinoma who received first-line treatment with ASKB589 triple-combination and Phase IV G/GEJ adenocarcinoma, the mPFS was 12.45 months, and the mOS was 21.36 months.
For patients with high CLDN18.2 expression, the mPFS was 15.01 months, and the mOS was 22.34 months.
Research Summary
Poster Title：Updated efficacy of ASKB589 plus CAPOX/PD-1 inhibitor in first - line metastatic G/GEJ adenocarcinoma: Phase Ib/II study
Number: 946P
Presentation Date: October 19, 2025 (local time in Germany)
Principal Investigator: Lin Shen, Peking University Cancer Hospital
This Phase Ib/II clinical trial (NCT05632939) includes both dose-escalation and dose-expansion phases and enrolls patients with CLDN18.2-positive gastric or GEJ adenocarcinoma. The study aims to evaluate the safety, tolerability, and antitumor activity of ASKB589 plus CAPOX/PD-1 inhibitor in first-line therapy for locally advanced, recurrent, or metastatic G/GEJ adenocarcinoma.
Enrolled Patients
A total of 62 patients with CLDN18.2-positive, treatment-naive G/GEJ adenocarcinoma were enrolled. In the dose-expansion phase, 53 patients received ASKB589 at 6 mg/kg plus CAPOX/PD-1 inhibitor, including 47 patients with Phase IV G/GEJ adenocarcinoma exhibiting medium-to-high CLDN18.2 expression (≥40% & 2+/3+).
Efficacy Results
Among the 47 patients with medium-to-high CLDN18.2 expression and Phase IV disease in the dose-expansion cohort:
cORR: 76.1%
mDOR: 13.9 months
DCR: 100%
As of August 30, 2025, with a median follow-up of 26.71 months (range: 19.9–28.8 months), disease progression or death had occurred in 61.7% (29/47) of these patients.
mPFS: 12.45 months (95% CI: 7.92–19.25)
mOS: 21.36 months (95% CI: 15.87–25.00)
In the subgroup with high CLDN18.2 expression:
cORR: 81.8%
mPFS: 15.01 months (95% CI: 9.56–19.25)
mOS: 22.34 months (95% CI: 19.15–25.00)
Conclusion
With extended follow-up, the Phase Ib/II study of ASKB589 plus CAPOX/PD-1 inhibitor in first - line treatment of locally advanced, recurrent, or metastatic gastric/GEJ adenocarcinoma continues to demonstrate deep and durable tumor responses, complete disease control, and clear survival benefits. These results strongly support the ongoing pivotal Phase III clinical trial evaluating ASKB589 plus CAPOX/PD-1 inhibitor.