Alphamab Oncology Announces Biparatopic HER2-targeting ADC JSKN003 Received Approval to Initiate a Phase III Clinical Study for Colorectal Cancer

SUZHOU, China, Oct. 27, 2025 /PRNewswire/ -- Alphamab Oncology (stock code: 9966.HK) announced that the biparatopic HER2-targeting antibody-drug conjugate (ADC) JSKN003, 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 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: JSKN003-005) for the treatment of HER2-positive advanced colorectal cancer (CRC). This marks the fourth Phase III clinical study initiated for JSKN003, following the trials in HER2 low-expressing breast cancer, platinum-resistant ovarian cancer and HER2-positive breast cancer.

Colorectal cancer is among the most common malignancies worldwide. According to data from the International Agency for Research on Cancer (IARC), there were approximately 1.93 million newly diagnosed cases and about 903,900 deaths attributed to CRC globally in 2022, ranking third in incidence and second in mortality among all cancers. China has a high incidence of CRC, with over 500,000 new cases diagnosed annually. Approximately 83% of patients are initially diagnosed at an advanced stage, and about 44% already have distant metastases to organs such as the liver or lungs. Despite advances in systemic therapies, the 5-year survival rate for patients with metastatic CRC remains below 20%, indicating a poor prognosis. There are currently no HER2-targeted therapies approved in China for CRC. For patients with HER2-positive advanced CRC who have failed prior treatments with oxaliplatin, fluorouracil and irinotecan, the median progression-free survival (mPFS) of approved therapies is only 2.0 to 3.7 months, and the median overall survival (mOS) is approximately 7 to 10 months. There remains a significant unmet clinical need within this patient population.

JSKN003 is a biparatopic HER2-targeting ADC independently developed based on Anbenitamab. It specifically binds to HER2 on the surface of tumor cells, internalizes, and releases a topoisomerase I inhibitor to exert its anti-tumor effects. JSKN003 demonstrates significant differentiated advantages compared to similar ADC drugs, showing favorable safety, tolerability, and superior anti-tumor activity compared to existing treatments in early clinical studies. In October 2025, JSKN003 monotherapy for the treatment of HER2-positive advanced CRC in patients who have failed prior treatments with oxaliplatin, fluorouracil, and irinotecan was granted Breakthrough Therapy Designation by the CDE.

JSKN003-005 is a randomized, open-label, controlled, multicenter Phase III clinical study designed to evaluate the efficacy and safety of JSKN003 versus investigator's choice of regimen (regorafenib/fruquintinib/trifluridine tipiracil) in HER2-positive advanced CRC patients who have failed prior oxaliplatin, fluorouracil, and irinotecan therapy.

About JSKN003

JSKN003 is developed by site-specific conjugation to the Fc glycans of anbenitamab, resulting in a homogeneous and stable ADC with a DAR of 4. JSKN003 binds to two HER2 epitopes on tumor cells and release topoisomerase I inhibitors through cellular endocytosis, exerting anti-tumor effects.

Compared to similar ADCs, JSKN003 demonstrates better serum stability, reduced hematological toxicity, and stronger tumor inhibition and bystander effect, resulting in significantly wider therapeutic window.

Multiple registrational studies of JSKN003 are ongoing, including trials in HER2-positive breast cancer (BC), all-comer platinum-resistant ovarian cancer (PROC), HER2-low BC, and HER2-positive colorectal cancer (CRC).

JSKN003 has been granted Orphan Drug Designation (ODD) by the U.S. Food and Drug Administration (FDA) for gastric cancer (GC) and gastroesophageal junction cancer (GEJ); It has been granted two Breakthrough Therapy Designations by the National Medical Products Administration (NMPA) for platinum-resistant recurrent epithelial ovarian cancer, primary peritoneal cancer, or fallopian tube cancer and HER2-positive advanced CRC that has failed prior oxaliplatin, fluorouracil, and irinotecan therapy.

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). JMT-Bio was granted the exclusive license and sublicense rights to develop, sell, offer for sale and commercialize JSKN003, for tumor-related indications in mainland China (excluding Hong Kong, Macau or Taiwan). Alphamab retains exclusive production rights for JSKN003.

About Alphamab Oncology

Alphamab Oncology is an innovative biopharmaceutical company focused on oncology. On December 12, 2019, the Company was successfully listed on the Main Board of the Hong Kong Stock Exchange (Stock Code: 9966.HK).

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