Alphamab Oncology Announces the Results of a Phase III Clinical Study of Anbenitamab (KN026) were Published in Annals of Oncology

SUZHOU, China, Jan. 27, 2026 /PRNewswire/ -- Alphamab Oncology (Stock Code: 9966.HK) announced that the results from a phase III clinical study for the treatment of HER2-positive gastric or gastroesophageal junction cancer (GC/GEJ) of 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), were recently published in the top-tier oncology journal Annals of Oncology (IF:65.4). The publication is titled: "Anbenitamab in previously treated HER2-positive gastric cancer (KC-WISE): pre-specified interim analysis of a randomized, phase III clinical trial". The study was led by Professor Jianming Xu and his team from the Chinese PLA General Hospital as the principal investigators.

Annals of Oncology is the official journal of the European Society for Medical Oncology (ESMO) and the Japanese Society of Medical Oncology (JSMO). It is dedicated to publishing groundbreaking oncology and translational research that changes clinical practice and improves patient outcomes. With an outstanding impact factor of 65.4, the journal is committed to advancing the standards of cutting-edge research, accelerating the exploration of novel technologies, and facilitating their clinical application worldwide.

This study is a randomized, double-blind, controlled, multicenter Phase III clinical trial (NCT05427383) aiming at evaluating the efficacy and safety of anbenitamab combined with chemotherapy versus standard treatment in patients with HER2-positive GC/GEJ who had previously failed first-line therapy containing trastuzumab. The study enrolled patients with HER2-positive GC/GEJ who had disease progression after at least first-line trastuzumab-based treatment. Enrolled patients were randomized in a 1:1 ratio to receive either anbenitamab combined with chemotherapy (Anbenitamab Group) or standard-of-care therapy (SOC Control Group). Randomization was stratified according to the combined chemotherapy (taxane or irinotecan), HER2 expression (IHC 3+ or IHC 2+ with FISH amplification), and previous lines of therapy (1 or ≥2). The primary efficacy endpoints were progression-free survival (PFS) and overall survival (OS) assessed by an Independent Review Committee (IRC). Secondary endpoints included other efficacy measures such as objective response rate (ORR), duration of response (DoR), and disease control rate (DCR) as assessed by the IRC and investigators, investigator-assessed PFS, safety, and immunogenicity.

The study results (as of the cut-off date April 3, 2025) demonstrated that the Anbenitamab Group delivered highly encouraging outcomes:

• Significant improvement in PFS: The Anbenitamab Group achieved a significantly prolonged median PFS. The median PFS was 7.1 months in the Anbenitamab Group versus 2.7 months in the SOC Control Group (HR 0.25, p<0.0001), representing a 75% reduction in the risk of disease progression or death.
• Clinically meaningful survival benefit: In patients with second-line HER2-positive gastric cancer, the Anbenitamab Group achieved a median OS approaching 20 months for the first time. The median OS was 19.6 months and 11.5 months in the Anbenitamab and Control groups, respectively (HR 0.29, p<0.0001), corresponding to a 71% reduction in the risk of death.
• Favorable safety and tolerability profile: The Anbenitamab Group exhibited a favorable tolerability profile. The incidence of treatment-emergent adverse events (TEAEs) was identical in both groups (97%). Importantly, despite a notably higher median treatment duration received in the Anbenitamab Group compared to the Control Group (6.5 cycles vs. 3.0 cycles), the incidence of grade ≥3 TEAEs was only slightly higher in the Anbenitamab Group (61% vs. 52%). The rates of serious adverse events (SAEs) and cardiac toxicity were comparable between the two groups. Furthermore, no treatment-related adverse events (TRAEs) leading to death occurred in the Anbenitamab Group.

In conclusion, the positive results robustly demonstrate that anbenitamab combined with chemotherapy has the potential to become a new standard of care for patients with HER2-positive gastric cancer who have failed at least one prior line of trastuzumab-containing therapy, and is well positioned to reshape the treatment landscape for second-line or later-line HER2-positive gastric cancer.

About Anbenitamab (KN026)

Anbenitamab (KN026) is an anti-HER2 bispecific antibody independently developed by Alphamab Oncology 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 ADCC and CDC effects while promoting the down-regulation of HER2 receptors on the cell surface.

In September 2025, the first New Drug Application (NDA) for anbenitamab injection has been accepted by the National Medical Products Administration (NMPA) for the treatment of HER2-positive gastric cancer (GC). Currently, several pivotal clinical trials of KN026 for second-line or above HER2-positive GC/gastroesophageal junction cancer (GEJ), first-line HER2-positive breast cancer (BC), neoadjuvant treatment of HER2-positive BC are being conducted.

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 an 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.

One product has 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. The NMPA has accepted the new drug application for KN026 (Anbenitamab Injection), a HER2 bispecific antibody, for second-line or later HER2-positive gastric cancer. Four bispecific ADC candidates have entered clinical stages, and next-generation ADC pipelines — such as dual-payload ADCs — 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, delivering China-innovated cancer therapies to benefit patients worldwide.

SOURCE Alphamab Oncology