GSK Initiates Two Global Phase III Trials of B7-H4 ADC Mocertatug Rezetecan in Ovarian and Endometrial Cancers

▎Armstrong

On December 16, 2025, GSK registered a global Phase III clinical trial for the new B7H4 ADC drug GSK5733584, aimed at treating endometrial cancer and ovarian cancer, on the Clinicaltrials.gov website. The trial plans to enroll 600 and 450 participants, respectively.GSK5733584 is HS-20089, which GSK China introduced from Hansoh Pharma.

The generic name of Hansoh Pharma's B7H4 ADC new drug HS-20089 is Mocertatug rezetecan.

The amino acid sequence of HS-20089 is as follows,The toxin uses Hengrui's SHR-9265 (rezetecan) with a DAR value of 4.

HS-20089 has received breakthrough therapy designation for ovarian cancer in China.

Summary

AstraZeneca's AZD8205 is the first B7H4 ADC to enter global Phase III clinical trials, using TOP1i as the payload. It demonstrated excellent efficacy potential in Phase 1/2 clinical trials for endometrial cancer, with an ORR of 34.6-38.5% and an mPFS of 7.0 months. In terms of safety, it showed lower hematological toxicity, with no discontinuation events due to side effects. GSK China/Hansoh Pharma subsequently initiated two global Phase III clinical trials for ovarian cancer and endometrial cancer.