Updated findings from the RUBY phase 3 trial suggested a durable progression-free survival benefit from dostarlimab plus chemotherapy in mismatch repair–deficient (dMMR)/microsatellite instability–high (MSI-H) primary advanced or recurrent endometrial cancer. At a median follow-up of 55.6 months, the 4-year PFS rate was 57.9% with dostarlimab compared with 15.7% with chemotherapy alone. Mixture cure modeling estimated that 54% of patients had potential for cure with the combination. The abstract also reported an overall survival improvement in the overall population of 44.6 months versus 28.2 months (HR 0.69). The data were shared ahead of ASCO 2026. For oncology stakeholders, the readout strengthens the evidence base for PD-1 blockade in biomarker-defined endometrial cancer and highlights the potential for long-term disease control beyond median PFS endpoints.