Suzhou, China, May 29, 2026 - Alphamab Oncology (stock code: 9966.HK) today announced that HER2 bispecific antibody 恩尼妥® (Anbenitamab Injection, KN026), independently developed by the Company, and co-developed with JMT-Bio Technology Co., Ltd., a wholly-owned subsidiary of CSPC Pharmaceutical Group Co., Ltd. (stock code: 1093.HK), has obtained approval for marketing from the National Medical Products Administration (NMPA) for use in combination with chemotherapy for the treatment of adult patients with locally advanced or metastatic HER2-positive gastric cancer/gastroesophageal junction cancer (GC/GEJ) who have previously received at least one trastuzumab-containing regimen.
Anbenitamab nearly doubles overall survival (OS) in patients with second- or third-line advanced GC compared to chemotherapy, setting a new record in the history of second-line HER2‑positive GC treatment. As the first domestically developed HER2 bispecific antibody approved for marketing in China, it is expected to reshape the treatment landscape.
China has a high incidence of GC, with approximately 358,700 new cases and approximately 260,400 deaths each year, among which 30% to 40% of patients are already at an advanced stage at the time of initial diagnosis, and the five-year survival rate after systemic treatment is less than 15%. HER2 positive expression is strongly associated with poor prognosis in GC. Given its distinct biological characteristics and high targetability, HER2 has remained an important focus for the evolution of clinical treatment strategies. For over a decade since trastuzumab, in combination with chemotherapy, established its role as the standard first-line targeted therapy in 2010, progress in second-line anti-HER2 treatment for patients with disease progression following trastuzumab therapy has been slow, with limited clinical benefits, which remains far from sufficient to address the urgent therapeutic needs of these patients.
Anbenitamab is a HER2 bispecific antibody independently developed by the Company using the proprietary CRIB (Charge Repulsion Induced Bispecific) platform. Anbenitamab can simultaneously and precisely bind to two non‑overlapping epitopes of the HER2 receptor (domain IV and domain II). By specifically binding to multiple HER2 proteins on the tumor cell membrane, it induces HER2 clustering, enhances HER2 internalization, accelerates HER2 receptor degradation and down-regulation, comprehensively blocks downstream signaling pathways, and inhibits tumor cell proliferation. In addition, besides ADCC and CDC activities, Anbenitamab also exhibits significant ADCP activity, leading to stronger tumor‑killing effects. This innovative design precisely addresses unmet clinical needs, with efficacy advantages that significantly surpass existing treatment options.
This marketing approval is based on the results of the pivotal phase II/III clinical study (KC-WISE), which enrolled patients with HER2 positive GC/GEJ who had failed at least one prior line of therapy. The study results demonstrated that, compared to standard chemotherapy, the Anbenitamab combination therapy significantly prolonged median progression free survival (mPFS) to 7.1 months, with a hazard ratio (HR) of 0.25, and median overall survival (mOS) to 19.6 months, with an HR of 0.29. The benefits were consistent across all patient subgroups, with similar positive trends observed for objective response rate (ORR) and duration of response (DOR). The adverse reactions were primarily chemotherapy-induced hematological toxicities, which were clinically manageable and controllable. Compared with similar competing products, it has lower incidence rates of cardiotoxicity, diarrhea, and infusion-related reactions, demonstrating significant safety advantage.
HER2 postive GC/GEJ is the first approved indication of Anbenitamab. Additionally, in March 2026, the phase III clinical study of Anbenitamab in combination with docetaxel (albumin-bound) for injection (HB1801) as neoadjuvant treatment for HER2 positive early or locally advanced breast cancer (BC) met its primary endpoint of total pathological complete response (tpCR), with results that were both statistically significant and clinically meaningful. The results from the pivotal phase III registrational clinical study of Anbenitamab in combination with HB1801 for the first-line treatment of HER2 positive BC are expected to be announced this year, which is anticipated to further expand the treatment landscape and bring high-quality, long‑term survival benefits to more patients with HER2‑positive tumors.
About 恩尼妥® (Anbenitamab Injection)
恩尼妥® (Anbenitamab injection, KN026) is an anti-HER2 bispecific antibody independently developed by the Company using the proprietary Fc-based heterodimer bispecific platform technology called CRIB (Charge Repulsion Induced Bispecific). Anbenitamab can simultaneously bind two non-overlapping epitopes of HER2, resulting in HER2 signal blockade. Through antibody-induced receptor clustering, it enhances antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) effects while promoting the down-regulation of HER2 receptors on the cell surface.
In May 2026, 恩尼妥® obtained approval for marketing in China for use in combination with chemotherapy for the treatment of adult patients with locally advanced or metastatic HER2 positive gastric cancer/gastroesophageal junction cancer (GC/GEJ) who have previously received at least one trastuzumab-containing regimen. Currently, multiple registrational clinical trials of Anbenitamab for indications such as first-line treatment of HER2 positive breast cancer (BC), neoadjuvant and adjuvant treatment of HER2 positive BC and first-line treatment of HER2 positive GC/GEJ are ongoing.
Anbenitamab has been granted Orphan Drug Designation by the U.S. Food and Drug Administration (FDA) for the treatment of HER2-positive or low expressing GC; it has been granted Breakthrough Therapy Designation by NMPA for the treatment of patients with HER2-positive GC/GEJ who have failed first-line standard treatment.
In August 2021, the Company entered an agreement with JMT-Bio Technology Co., Ltd. (JMT-Bio), a wholly-owned subsidiary of CSPC Pharmaceutical Group Co., Ltd. (CSPC) (stock code: 1093.HK), for the development and commercialization of KN026 in Mainland China. JMT-Bio was granted exclusive license rights of KN026 for the development and commercialization in the indications of BC and GC/GEJ in Mainland China (excluding Hong Kong, Macau and Taiwan).
About Alphamab Oncology
Alphamab Oncology (Stock Code: 9966.HK) is an innovative biopharmaceutical company focused on oncology. Leveraging proprietary platforms-including single-domain antibodies, bispecific antibodies, glycan-specific conjugation, linker-payloads, dual-payload ADCs, and high-concentration subcutaneous formulations, the Company has built a differentiated and globally competitive pipeline, covering cutting-edge candidates in ADCs, bispecific antibodies, and single-domain antibodies.
Two products have received market approval: Envafolimab (KN035, brand name: 恩维达®), the world's first subcutaneously injected PD-(L)1 inhibitor, offering greater convenience and accessibility in cancer treatment; and Anbenitamab (KN026, brand name: 恩尼妥®), the first domestically developed HER2 bispecific antibody approved for marketing in China, redefining the standard of treatment for second‑line HER2‑positive gastric cancer. Six bispecific ADC, dual-payload ADC candidates have entered clinical stages, and next-generation ADC pipelines are advancing rapidly. The Company has established strategic partnerships with organizations including CSPC, ArriVent, and Glenmark, covering both product development and technology platforms.
Our overarching mission is to make cancer manageable and curable by addressing unmet clinical needs in oncology. Alphamab Oncology is continuously dedicated to the development of effective, safe, and globally competitive anti-tumor drugs, enabling patients to achieve long-term, high-quality survival and delivering China-innovated cancer therapies to benefit patients worldwide.
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