Alphamab Oncology (9966) reported research updates on JSKN003 at the ESMO Congress 2025, detailing its progress in clinical studies targeting various HER2-expressing malignancies. The presentation included efficacy and safety findings for primary platinum-refractory ovarian cancer (OC) and HER2+ metastatic colorectal cancer (CRC), as well as an overview of a Phase III study in platinum-resistant recurrent epithelial ovarian cancer.

The JSKN003-102 study involved 26 patients with primary platinum-refractory OC, showing an objective response rate (ORR) of 32.0%, disease control rate (DCR) of 72.0%, and median progression-free survival (PFS) of 4.1 months. Grade 3 or higher treatment-related adverse events (TRAEs) were reported in four participants, and two instances of interstitial lung disease (ILD) were noted, both classified as Grades 1/2. In the HER2+ metastatic CRC cohort, 33 patients were enrolled, yielding an ORR of 68.8% and a DCR of 96.9%. Among the 31 BRAF V600E wild-type patients, the ORR reached 71.0%, with a median duration of response (DoR) of 9.89 months and a median PFS of 11.04 months. Grade 3 or higher TRAEs occurred in seven patients, and four experienced mostly mild ILD.

A Phase III trial (JSKN003-306) comparing JSKN003 with physician’s choice of chemotherapy in platinum-resistant recurrent ovarian cancer is in progress, with a plan to enroll 556 patients across multiple sites in China. JSKN003, a biparatopic HER2-targeting antibody-drug conjugate, employs a glycosite-specific approach and topoisomerase I inhibitor payload designed to enhance HER2 binding and boost anti-tumor activity. Alphamab Oncology maintains a pipeline of antibody-based therapies and has licensed JSKN003 in mainland China for multiple tumor-related indications.