GSK’s B7-H4 ADC shows 62% response in platinum-resistant ovarian cancer, PFS 11 months

GSK’s global head of oncology R&D presented new early-stage data on its B7-H4‑directed antibody‑drug conjugate, mo‑rez, at the ESMO conference in Madrid. The update focused on the ongoing Behold‑1 trial in patients with platinum‑resistant ovarian cancer (PROC) and advanced or recurrent endometrial cancer.

In the PROC cohort, 45 patients received the phase‑3 dose of 5.8 mg/kg and were followed for about 13 months. The therapy achieved a confirmed objective response rate of 62%, with a median duration of response of 12.2 months and a median progression‑free survival of 11.1 months. These efficacy metrics match an earlier readout from April.

GSK’s Hesham Abdullah, MD, described the durability of response and PFS as "quite encouraging" for this patient group, which typically sees PFS in the six‑to‑eight‑month range. He emphasized that the data reinforce the company’s confidence in the ADC platform.

Overall, 71% of the patients reported treatment‑related events, underscoring the need to balance efficacy with safety as the program moves toward multiple phase‑3 studies.