Hansoh Pharmaceutical Group Co., Ltd. has announced positive phase 2 clinical trial results for HS-20089, a B7-H4-targeted antibody-drug conjugate $(ADC)$, in patients with platinum-resistant ovarian cancer $(PROC)$. The findings were presented in a poster session at the European Society for Medical Oncology (ESMO) 2025 Annual Meeting and will be featured in an oral presentation at the IGCS 2025 Annual Global Meeting in Cape Town, South Africa. HS-20089 (licensed to GSK as GSK5733584) demonstrated a confirmed objective response rate $(ORR)$ of 48.5%, a duration of response (DoR) of 6.8 months, a median progression-free survival (mPFS) of 6.4 months, and a median overall survival (mOS) of 14.6 months at a dose of 4.8 mg/kg. The safety profile was manageable, consistent with phase 1 data, and no new safety signals were observed. The phase 2 study included heavily pretreated PROC patients regardless of tumor B7-H4 expression. A phase 3 study of HS-20089 is currently ongoing (NCT06855069).