Anti-HER2 Bispecific ADC JSKN003 Received Approval to Initiate a Phase III Clinical Study for the Treatment of HER2-positive Breast Cancer

SUZHOU, China, Feb. 6, 2025 /PRNewswire/ -- Alphamab Oncology (Stock Code: 9966.HK) and CSPC Pharmaceutical Group Co., Ltd. ("CSPC") (Stock Code: 1093.HK) jointly announced that anti-HER2 biparatopic antibody-drug conjugate (ADC) JSKN003 has received approval from the Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA) to initiate a Phase III clinical study (Study ID: JSKN003-301). The study aims to compare the efficacy and safety of JSKN003 versus trastuzumab emtansine (T-DM1) for the treatment of HER2-positive advanced breast cancer. This marks the third Phase III clinical study initiated for JSKN003, following the trials in HER2 low-expressing breast cancer and platinum-resistant ovarian cancer.

Breast cancer is one of the most common malignant tumors among women worldwide and the most prevalent cancer in women in China. HER2-positive breast cancer accounts for 20% to 25% of all breast cancer cases in China, and it is the most aggressive and highly malignant subtype, prone to recurrence, metastasis, and worse prognosis. In recent years, targeted therapies and combination treatments have emerged and significantly improved the diagnosis and treatment of HER2-positive breast cancer. However, recurrent and metastatic breast cancer still poses a severe threat to patients' health, with a significant unmet clinical need.

JSKN003 is an anti-HER2 bispecific ADC developed inhouse with Alphamab's proprietary Glycan-specific conjugation platform. The antibody molecule KN026 is site-specifically modified via enzyme catalytic reaction and click chemistry to achieve a drug-to-antibody ratio (DAR) of approximately 4. It can bind HER2 on the surface of tumor cells, and release topoisomerase I inhibitors (TOPIi) through cellular endocytosis, thereby exert anti-tumor effects. Compared with its ADC counterparts, JSKN003 demonstrated better serum stability and stronger bystander effect, which effectively expands the therapeutic window. Multiple clinical studies at various stages of JSKN003 conducted in China and Australia have demonstrated favorable tolerability and safety profile, with promising efficacy of JSKN003 in heavily pretreated patients with advanced solid tumors, especially in patients with HER2-expressing breast cancer, platinum-resistant ovarian cancer (PROC), or high HER2-expressing solid tumors.

JSKN003-301 is a randomized, controlled, open-label, multicenter, Phase III clinical study aimed at evaluating the efficacy and safety of JSKN003 compared to emtansine (T-DM1) in the treatment of patients with HER2-positive, unresectable locally advanced or metastatic breast cancer who have previously received trastuzumab or taxane-based therapies. The primary endpoint of the study is progression-free survival (PFS) as assessed by the Blinded Independent Review Committee (BIRC).

About JSKN003

JSKN003 is an anti-HER2 bispecific antibody-drug conjugate (bis-ADC), which is developed inhouse with Alphamab's proprietary Glycan-specific conjugation platform. JSKN003 can bind HER2 on the surface of tumor cells and release topoisomerase I inhibitors (TOPIi) through cellular endocytosis, thereby exert anti-tumor effects. Compared with its ADC counterparts, JSKN003 demonstrated better serum stability and stronger bystander effect, which effectively expands the therapeutic window.

Multiple clinical studies at various stages of JSKN003 are currently being conducted in China and Australia. Clinical research results have demonstrated favorable tolerability and safety profile, with promising efficacy of JSKN003 in heavily pretreated patients with advanced solid tumors, especially in patients with HER2-expressing breast cancer, platinum-resistant ovarian cancer (PROC), or high HER2-expressing solid tumors.

In September 2024, the Company entered a licensing agreement with JMT-Bio Technology Co., Ltd. ("JMT-Bio"), a wholly-owned subsidiary of CSPC Pharmaceutical Group Co., Ltd. ("CSPC") (stock code: 1093.HK), pursuant to which, JMT-Bio was granted the exclusive license and sublicense rights to develop, sell, offer for sale and commercialize JSKN003, for the treatment of tumor-related indications (the "Field") in mainland China (excluding Hong Kong, Macau or Taiwan) (the "Territory") and become the sole marketing authorization holder for JSKN003 for the Field in the Territory. Alphamab retains the sole right to supply JSKN003.

About Alphamab Oncology

Alphamab Oncology is a leading biopharmaceutical company committed to the development, manufacturing, and commercialization of cutting-edge biotherapeutics for the treatment of cancer. On December 12, 2019, the company was successfully listed on the Main Board of the Hong Kong Stock Exchange, trading under the stock code 9966.

Our integrated platform seamlessly combines research, development, and manufacturing capabilities for biologics. We take pride in our extensive intellectual property portfolio, which encompasses protein/antibody engineering, antibody screening, and multi-module/multi-functional antibody modification.

Distinguished by a globally competitive pipeline, Alphamab Oncology specializes in antibody-drug conjugation (ADC), single domain antibody, and bispecific antibodies. Notably, Envafolimab, the world's first subcutaneously injectable PD-L1 inhibitor, was approved by Chinese authorities in 2021, making a significant breakthrough in the convenience and accessibility of cancer treatment. Three assets are currently undergoing Phase III or pivotal clinical trials, and several other bispecific ADC new drug candidates are in early clinical stage. Multiple strategic collaborations based on innovative products or technology platforms have been established with partners such as CSPC, Arrivent, and Glenmark.

Our overarching mission is to make cancer manageable and curable by addressing unmet clinical needs in oncology. Alphamab Oncology is dedicated to the development of safe, effective and affordable drugs, leveraging a global competitive edge.

SOURCE Alphamab Oncology