A phase 3 ENGOT-ENG-NSGO/GOG-3031/RUBY update showed durable disease control with dostarlimab plus chemotherapy in dMMR/MSI-H endometrial cancer. At a median follow-up of 55.6 months, 4-year progression-free survival reached 57.9% with dostarlimab versus 15.7% with chemotherapy alone. Mixture cure modeling in the abstract estimated that 54% of patients had potential curative benefit with the combination regimen. Updated OS results were also included, with a reported median OS of 44.6 months versus 28.2 months for chemotherapy alone (HR 0.69). The readout, expected to shape discussions for ASCO 2026, elevates the chance that the therapy could become a key option for biomarker-defined patients where durability has historically been difficult to achieve.