CSPC PHARMA (01093): Updated overall survival (OS) results from the Phase III clinical study of Anntibody for the treatment of HER2-positive advanced gastric/gastroesophageal junction adenocarcinoma were presented as a rapid oral presentation at the 2026 ESMO Annual Meeting

CSPC PHARMA (01093) announced that the updated overall survival (OS) analysis results from the Phase III clinical study (Study No.: KC-WISE) of Anntibody Injection (trade name: Ennituo), jointly developed by the Group and Jiangsu Alphamab Biopharmaceuticals Co., Ltd., in combination with chemotherapy for the treatment of human epidermal growth factor receptor 2 (HER2)-positive advanced gastric/gastroesophageal junction adenocarcinoma (GC/GEJA) in patients who had previously failed trastuzumab treatment, were selected as a Late-breaking Abstract (LBA) at the 2026 European Society for Medical Oncology (ESMO) Annual Meeting on October 23, 2026, and were presented as a rapid oral presentation. The KC-WISE study is a randomized, double-blind, controlled, multicenter Phase III clinical study (NCT05427383), led by Professor Xu Jianming of the Chinese People's Liberation Army General Hospital as principal investigator and sponsored by the Group, aiming to conduct a head-to-head comparison of the efficacy and safety of Anntibody combined with chemotherapy versus standard of care in HER2-positive GC/GEJA patients who had failed trastuzumab treatment. A total of 246 subjects were randomized in the study, including 125 in the Anntibody group and 121 in the control group. The data announced this time were cut off as of July 15, 2026, with median follow-up durations of 22.8 months and 22.3 months in the two groups, respectively. Efficacy: A total of 157 death events occurred in the two groups, including 66 (52.8%) in the Anntibody group and 91 (75.2%) in the control group. The median overall survival (mOS) in the Anntibody group reached 19.6 months, significantly superior to 9.6 months in the control group (hazard ratio (HR)=0.39; 95% confidence interval (CI): 0.280.54; P<0.0001), representing a substantial 61% reduction in the risk of death compared with standard of care. 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) in the Anntibody group and the control group was 7.1 months and 2.7 months, respectively (HR=0.35; 95% CI: 0.260.48; P<0.0001); the PFS results assessed by investigators were similar to the IRC assessment conclusions, further verifying that the regimen can significantly delay disease progression. Safety: The most common Grade 3 treatment-emergent adverse events (TEAEs) in the Anntibody 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 Anntibody group, while 5 treatment-related deaths were reported in the control group. Overall, the Anntibody group had a favorable safety profile with manageable risks. The updated OS data announced at the 2026 ESMO Annual Meeting further confirm that Anntibody combined with chemotherapy for second-line and later 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. Anntibody is a HER2 bispecific antibody targeting two non-overlapping epitopes of HER2, which can simultaneously bind to two non-overlapping epitopes of HER2 and block the HER2 signaling pathway; through antibody-induced receptor clustering, it enhances antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) effects, while 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, Anntibody Injection (Ennituo) 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 later treatment of HER2-positive advanced GC/GEJA patients. The Group is the sole Marketing Authorization Holder (MAH) in mainland China for the approved indication of Anntibody Injection (Ennituo) and the sole holder of the Ennituo trademark. As an independent sponsor, the Group fully leads the clinical development design and end-to-end management of Anntibody Injection (Ennituo). Leveraging its mature incubation ecosystem, efficient clinical operations 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.