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 been granted breakthrough therapy designation (BTD) by the U.S. Food and Drug Administration (FDA) for the treatment of adult patients with advanced or metastatic platinum-resistant recurrent epithelial ovarian cancer, primary peritoneal, or fallopian tube cancers (PROC) expressing HER2 (IHC 1+, 2+ and 3+) who have received prior treatment with bevacizumab.

Previously, JSKN003 has received approval from FDA to initiate a phase II clinical study for the treatment of PROC not restricted by HER2 expression, has been granted Fast Track Designation (FTD) by the FDA for PROC and has been granted Orphan Drug Designation (ODD) by the FDA for gastric cancer and gastroesophageal junction cancer (GC/GEJ). It has also been granted BTDs by the Center for Drug Evaluation (CDE) of the National Medical Products Administration of China (NMPA) for both PROC and colorectal cancer (CRC). The grant of this BTD further demonstrates the international regulatory community's recognition of JSKN003's clinical potential and its importance as a novel therapeutic candidate. The phase III clinical trial of JSKN003 for the treatment of PROC in China is currently undergoing smoothly.

The grant of BTD for JSKN003 is based on the pooled analysis of the phase I clinical study in Australia (JSKN003-101, NCT05494918) and the phase I/II clinical study in China (JSKN003-102, NCT05744427). The relevant efficacy and safety data of PROC were released at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting.

Ovarian cancer (OC) is one of the most common malignant tumors of the female reproductive system. Most patients are diagnosed at an advanced stage, and the disease is characterized by a high recurrence rate and significant treatment challenges. The standard treatment regimens recommended by authoritative guidelines both domestically and internationally include surgery combined with platinum-based chemotherapy and targeted therapy maintenance. However, about 80% of OC cases recur, and eventually progress to PROC, leaving patients with limited effective treatment options and poor prognosis. The U.S. National Comprehensive Cancer Network (NCCN) recommended single-agent non-platinum chemotherapy with or without bevacizumab as preferred regimens for PROC. However, these non-platinum chemotherapies demonstrate limited efficacy, with an objective response rate (ORR) of only 10% to 15%, a median progression-free survival (mPFS) of only 3 to 4 months, and a median overall survival (OS) of approximately 12 months, highlighting an urgent need for new treatment options. The grant of BTD by FDA will further expedite the clinical development and regulatory review of JSKN003 and bring new choice to patients with PROC worldwide.