CSPC Pharma (01093) has announced that updated overall survival (OS) results from a Phase III clinical study of Anbenatamab injection (brand name: Ennitol®) combined with chemotherapy for the treatment of human epidermal growth factor receptor 2 (HER2)-positive advanced gastric cancer/gastroesophageal junction adenocarcinoma (GC/GEJA) in patients who had previously failed trastuzumab treatment were presented as a rapid oral presentation at the 2026 European Society for Medical Oncology (ESMO) Congress on October 23, 2026, having been selected as a Late-breaking Abstract (LBA).

The drug was jointly developed by the Group and Jiangsu Alphamab Biopharmaceuticals Co., Ltd. The Phase III clinical study (Study Number: KC-WISE) is a randomized, double-blind, controlled, multicenter Phase III trial (NCT05427383) led by Professor Xu Jianming of the Chinese People's Liberation Army General Hospital and sponsored by the Group, designed to conduct a head-to-head comparison of the efficacy and safety of Anbenatamab combined with chemotherapy versus standard treatment in HER2-positive GC/GEJA patients who have failed trastuzumab treatment.

The study randomized a total of 246 subjects, with 125 in the Anbenatamab group and 121 in the control group. The data presented at this congress had a cutoff date of July 15, 2026, with median follow-up times of 22.8 months and 22.3 months for the two groups, respectively.

In terms of efficacy, a total of 157 death events occurred across both groups, including 66 cases (52.8%) in the Anbenatamab group and 91 cases (75.2%) in the control group. The median overall survival (mOS) in the Anbenatamab group reached 19.6 months, significantly superior to 9.6 months in the control group (hazard ratio (HR)=0.39; 95% confidence interval (CI): 0.28–0.54; P<0.0001), representing a substantial 61% reduction in the risk of death compared with standard treatment. Subgroup analysis showed that the OS benefit was consistent across all prespecified subgroups. As assessed by the Independent Review Committee (IRC), the median progression-free survival (mPFS) was 7.1 months in the Anbenatamab group and 2.7 months in the control group (HR=0.35; 95% CI: 0.26–0.48; P<0.0001). The PFS results assessed by investigators were similar to the IRC assessment conclusions, further validating that the regimen can significantly delay disease progression.

In terms of safety, the most common ≥Grade 3 treatment-emergent adverse events (TEAEs) in the Anbenatamab group and the control group included neutropenia (33.1% vs 24.8%), leukopenia (27.4% vs 25.6%), and anemia (25.8% vs 14.0%). No treatment-related deaths occurred in the Anbenatamab group, while 5 treatment-related deaths were reported in the control group. Overall, the Anbenatamab group demonstrated a favorable safety profile with manageable risks.

The updated OS data presented at the 2026 ESMO Congress further confirmed that Anbenatamab combined with chemotherapy for second-line and beyond treatment of HER2-positive advanced GC/GEJA patients provides significant benefits in both short-term tumor shrinkage and long-term survival, with an overall manageable safety profile, and is expected to reshape the clinical treatment landscape for HER2-positive advanced GC/GEJA.

Anbenatamab is a HER2 bispecific antibody targeting two non-overlapping epitopes of HER2, capable of simultaneously binding to two non-overlapping epitopes of HER2 and blocking the HER2 signaling pathway. Through antibody-induced receptor clustering, it enhances antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) effects, while also promoting HER2 receptor internalization and downregulation of cell surface HER2 receptors.

Based on the previously breakthrough interim PFS analysis results of the KC-WISE study, Anbenatamab injection (Ennitol®) was approved for marketing by the National Medical Products Administration (NMPA) of the People's Republic of China in May 2026 for use in combination with chemotherapy for second-line and beyond treatment of HER2-positive advanced GC/GEJA patients.

The Group is the sole Marketing Authorization Holder (MAH) for the approved indication of Anbenatamab injection (Ennitol®) in mainland China and is also the sole holder of the Ennitol® trademark. As the independent sponsor, the Group fully leads the clinical development design and full-process management of Anbenatamab injection (Ennitol®). Leveraging its mature incubation ecosystem, efficient clinical operational capabilities, comprehensive resource coordination mechanisms, and well-established commercialization system, the Group is expected to rapidly integrate full-chain advantages to bring the product to market.