Puxitatug samrotecan (AZD8205) generated high response rates in B7-H4–selected recurrent or progressive endometrial cancer in the BLUESTAR Phase 1/2a program, including a 47.1% confirmed objective response rate at 2.4 mg/kg. In the subgroup of patients previously treated with platinum chemotherapy and anti–PD-1/PD-L1 therapy, confirmed ORR rose to 60.6%, with median PFS around 7 months. The data supported an FDA Breakthrough Therapy Designation for the B7-H4–selected endometrial population after prior platinum and immunotherapy, while also showing activity in heavily pretreated ovarian cancer, where confirmed ORR was 24.4%.