AstraZeneca/az’s pipeline ADC candidate puxitatug samrotecan generated high response rates in B7-H4–selected endometrial cancer data shown at ASCO. In the Phase 1/2a BLUESTAR study (NCT05123482), the company reported a confirmed objective response rate of 47.1% and median progression-free survival of 7.2 months at 2.4 mg/kg. In a heavily pretreated subgroup that had also received platinum-based chemotherapy and prior anti–PD-1/PD-L1 therapy, the confirmed ORR climbed to 60.6% with a median PFS of 7.1 months. The ADC also showed activity in ovarian cancer, with a 24.4% confirmed ORR at the same dose level. Investigators said these findings supported FDA Breakthrough Therapy Designation for B7-H4–selected recurrent or progressive endometrial cancer following prior platinum and immunotherapy, reinforcing the ADC’s role as a targeted option in a population with limited choices.