QureBio, a clinical-stage biotechnology company developing bispecific antibodies and engineered biopharmaceuticals for cancer and inflammatory diseases, has disclosed Phase Ib/II clinical data for its lead programme Q-1802 through an abstract submission to the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting.

The abstract titled “Phase I/II Trial of Anti-CLDN18.2/PD-L1 Recombinant Humanised Bispecific Antibody Q-1802 Plus XELOX in Treatment-Naïve CLDN18.2-Positive Advanced GC/GEJ,” reports encouraging safety and efficacy outcomes in patients with advanced Gastric or Gastroesophageal Junction (GC/GEJ) cancer.

The study enrolled 62 eligible patients with CLDN18.2-positive (≥40 percent tumour cells with 2 plus/3 plus membranous staining), HER2-negative, treatment-naïve, unresectable locally advanced or metastatic GC/GEJ. Patients received Q-1802 at doses of 10 mg/kg or 20 mg/kg every two weeks in combination with standard XELOX chemotherapy.

No dose-limiting toxicities were observed, and the maximum tolerated dose was not reached. The most common Q-1802-related grade 3 or higher treatment-emergent adverse events included thrombocytopenia (8.1 percent), neutropenia (6.5 percent), anaemia, white blood cell count decrease and hypokalaemia (4.8 percent each). Permanent discontinuation due to treatment-related adverse events occurred in 6.5 percent of patients, with no treatment-related deaths reported.

Among 60 efficacy-evaluable patients, the Overall Response Rate (ORR) was 70.0 percent, the Disease Control Rate (DCR) reached 98.3 percent, and median progression-free survival (mPFS) was 11.3 months. In patients receiving the 10 mg/kg dose with high CLDN18.2 expression, ORR was 73.0 percent with with an mPFS of 11.3 months. Outcomes further improved in patients with both high CLDN18.2 expression and PD-L1 CPS ≥5, where ORR increased to 81.8 percent. and mPFS to 12.2 months.

Based on these findings, investigators concluded that Q-1802 combined with XELOX demonstrated manageable safety and promising antitumour activity as a first-line treatment for CLDN18.2-positive, HER2-negative advanced GC/GEJ. The results support advancement into a Phase III trial, with Q-1802 at 10 mg/kg selected as the recommended dose.

QureBio’s Phase III trial of Q-1802 has recently received approval from China’s National Medical Products Administration (NMPA) Center for Drug Evaluation (CDE).