Dostarlimab (PD-1) + carboplatin/paclitaxel shows 57.9% 4-year PFS and ~54% “cure fraction” in dMMR/MSI-H endometrial cancer (RUBY)

Dostarlimab (Jemperli) is an anti–PD-1 monoclonal antibody combined with carboplatin–paclitaxel (CP) as first-line therapy for primary advanced or recurrent dMMR/MSI-H endometrial cancer in the Phase 3, randomized RUBY Part 1 trial (ENGOT-EN6-NSGO/GOG-3031; NCT03981796). With median follow-up 55.6 months, 4-year PFS was 57.9% (95% CI, 42.3%–70.6%) with dostarlimab+CP vs 15.7% (95% CI, 7.2%–27.0%) with CP alone; only 4 new PFS events were reported since the initial analysis despite ~2.5 additional years of follow-up, consistent with a durable plateau. A mixture cure model estimated a 54% “cured” fraction (95% CI, 35%–72%) with dostarlimab+CP; for benchmarking, PD-1+CP is now an SOC concept in this setting (e.g., pembrolizumab+CP in KEYNOTE-868/NRG-GY018: dMMR cohort mPFS NR vs 6.5 mo; HR 0.30), so RUBY’s long-term PFS plateau and modeled cure fraction largely speak to durability rather than “beating chemo,” which is already clearly inferior for dMMR disease.