Alphamab Oncology Announces the Phase III Clinical Study of Anbenitamab (KN026) Combined with HB1801 as Neoadjuvant Treatment for Breast Cancer Has Met the Primary Endpoint

SUZHOU, China, April 1, 2026 /PRNewswire/ -- Alphamab Oncology (stock code: 9966.HK) today announced that HER2 bispecific antibody 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), in combination with Docetaxel for Injection (Albumin-bound) (HB1801), has met the pre-specified primary endpoint of total pathological complete response (tpCR) in a Phase III clinical study (KN026-004) for the  neoadjuvant treatment of HER2-positive early or locally advanced breast cancer (BC). Compared with the current standard of care (trastuzumab plus pertuzumab and docetaxel±carboplatin, i.e., the TCbHP regimen), the Anbenitamab combination therapy significantly improved tpCR, with both statistical and clinical significance.

KN026-004 is the world's first registrational study to demonstrate in a head-to-head Phase III trial that a HER2 bispecific antibody is superior to the combination of trastuzumab and pertuzumab (two monoclonal antibodies), marking a historic breakthrough for bispecific antibodies in the neoadjuvant treatment of breast cancer. Detailed data will be presented at an upcoming international academic conference. The positive results of KN026-004 offer a promising new neoadjuvant option for patients with HER2-positive early breast cancer – one that delivers better efficacy.

Study Design

KN026-004 is a randomized, controlled, open-label, multicenter Phase III study designed to enroll approximately 520 patients with early or locally advanced HER2-positive breast cancer, randomized 1:1 to the experimental arm (Anbenitamab + HB1801 ± carboplatin) or the control arm (trastuzumab + pertuzumab + docetaxel ± carboplatin). The primary endpoint is tpCR assessed by a blinded independent review committee (BIRC).

Key Clinical Advantages

Shorter Regimen: KN026-004 adopts a single-stage, continuous 6-cycle regimen (Anbenitamab + HB1801 ± carboplatin), allowing patients to undergo radical surgery approximately 6 weeks earlier. In contrast, the recently approved trastuzumab deruxtecan (T-DXd, i.e., DS-8201) sequential THP regimen requires 8 cycles – patients first receive 4 cycles of T-DXd followed by 4 cycles of THP, where T-DXd essentially replaces only 4 cycles of dose-dense doxorubicin plus cyclophosphamide (ddAC) used in the traditional regimen. KN026-004 achieves continuous, uninterrupted HER2 signal blockade with a simpler 6-cycle regimen, requiring no drug switching or segmented treatment.

Significant Clinical Value: The bispecific antibody regimen eliminates treatment gaps and avoids efficacy fluctuations that may occur when switching between different drugs in sequential regimens. The partner chemotherapy HB1801 is an albumin-bound formulation of docetaxel that requires no steroid premedication, expected to maintain efficacy while reducing the toxicity burden associated with conventional docetaxel. Anbenitamab is a non-ADC bispecific antibody, thus avoiding serious adverse events unique to ADC drugs such as interstitial lung disease, offering a more manageable safety profile. Additionally, physicians may decide whether to combine carboplatin based on the patient's specific condition.

Full Treatment-Cycle Coverage

In addition to the neoadjuvant Phase III study (KN026-004) that has met its primary endpoint, the adjuvant Phase III study (KN026-007) completed first patient dosing in March 2026 and plans to enroll approximately 1,800 patients with high recurrence risk after surgery.

Domestically developed bispecific antibody Anbenitamab and the innovative chemical drug HB1801 offer significant cost advantages. If approved and subsequently included in the national reimbursement drug list, they are expected to benefit a wider population of HER2-positive breast cancer patients.

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), and the application is currently under review. 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 and adjuvant 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 HB1801

HB1801 is one of the representative drugs independently developed by the Group's nanomedicine technology platform. Currently, multiple modified drugs developed based on this technology platform have been approved for launch, including mitoxantrone liposome, irinotecan liposome and paclitaxel (albumin-bound). Docetaxel is a paclitaxel analogue that is currently widely used in clinical practice both domestically and overseas for the monotherapy or combination therapy of multiple solid tumors such as breast cancer, non-small cell lung cancer, gastric cancer and pancreatic cancer. However, docetaxel has high hydrophobicity, and current formulations need to use polysorbate 80 (Tween-80) and ethanol as solvents, leading to many limitations in clinical application: it is easy to cause severe allergic reactions, can only be administered at low concentration and low drip rate; the product has poor compatibility and stability, requiring the use of infusion devices without polyvinyl chloride (PVC) material and making clinical use inconvenient. HB1801 encapsulates docetaxel in human serum albumin. Because it does not contain Tween-80 and ethanol, it has the following advantages compared with docetaxel injection: (1) Safety: no hormone pretreatment is required, it can be administered rapidly at high concentration, with higher safety and patient compliance; (2) Efficacy: it has significant effects in multiple preclinical tumor models, and can be administered at a larger dose clinically, further improving efficacy.

Results of multiple early clinical studies at different stages showed that HB1801 demonstrated better anti-tumor efficacy and safety than docetaxel injection, achieving the goal of reducing toxicity and increasing efficacy. Currently, HB1801 has entered the pivotal registrational Phase III clinical trial stage in indications such as breast cancer and gastric cancer.

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. Five 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, enabling patients to achieve long-term, high-quality survival and delivering China-innovated cancer therapies to benefit patients worldwide.

SOURCE Alphamab Oncology