GSK and the GOG Foundation kicked off the first patient in a global phase 3 trial for mocertatug rezetecan in platinum-resistant ovarian cancer. The study, GOG-3132/BEHOLD-Ovarian01 (NCT07286266), is designed to compare the investigational therapy against standard-of-care chemotherapy. The enrollment milestone marks the shift from earlier development into a pivotal phase intended to generate registrational evidence. For investors and competing developers, it also increases the number of active late-stage options seeking to address a difficult-line setting where response durability remains a core challenge. A phase 3 start also tends to accelerate manufacturing and timelines for regulatory interaction, as sponsors align dose logistics and endpoints across multiple geographies.