Updated phase 3 findings for dostarlimab plus carboplatin and paclitaxel in dMMR/MSI-H endometrial cancer show durable disease control, with full data expected at ASCO 2026. The update draws from the ENGOT-ENG-NSGO/GOG-3031/RUBY trial (NCT03981796), reported via abstract release. At a median follow-up of 55.6 months, the descriptive progression-free survival rate at four years was 57.9% with dostarlimab versus 15.7% with chemotherapy alone. Mixture cure modeling estimated that 54% of patients had curative potential with the combination regimen. In the overall study, median OS was reported as 44.6 months versus 28.2 months (HR 0.69). For dMMR/MSI-H patients, the long follow-up strengthens the case that immunotherapy-containing regimens may deliver sustained benefit in a subset defined by tumor biology rather than line of therapy alone.