Alphamab Oncology (stock code: 9966.HK) announced that the first patient has been successfully dosed in the Phase III clinical study (Study ID: JSKN003-005) of the biparatopic HER2-targeting antibody-drug conjugate (ADC) JSKN003, for the treatment of HER2-positive advanced colorectal cancer (CRC). JSKN003 is 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).

Colorectal cancer is among the most common malignancies worldwide. 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. Early clinical data of JSKN003 are promising, and JSKN003 has been granted Breakthrough Therapy Designation by the Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA) for this indication. According to the data presented at the 2025 European Society for Medical Oncology (ESMO) Congress, JSKN003 demonstrated an objective response rate (ORR) of 68.8% and a mPFS of 11.04 months in 32 patients with HER2-positive advanced colorectal cancer, showing a clear therapeutic advantage over existing therapies.

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. The primary endpoint is PFS assessed by blinded independent central review (BICR) according to RECIST v1.1. Secondary endpoints include OS, as well as investigator-assessed PFS and ORR, disease control rate (DCR), duration of response (DOR), time to response (TTR), and other endpoints evaluated by BICR/investigator according to RECIST v1.1. The rapid progression of this study marks a critical stage in the development of JSKN003 for colorectal cancer, and is expected to provide patients with a new therapeutic option.