Study summary

Four years out, dostarlimab plus chemotherapy may have cured about half of a hard-to-treat group

RUBY 4-year follow-up · Phase 3, randomized · Published September 2026, Gynecologic Oncology

What was tested

Dostarlimab, an immunotherapy, added to chemotherapy, against chemotherapy alone, for advanced or recurrent endometrial cancer with mismatch-repair-deficient (dMMR) tumors, followed for about 4.5 years.

What they found

• Risk of death was 66% lower with dostarlimab; median survival was not yet reached.
• Only 4 more people progressed in the last 2.5 years of follow-up.
• A statistical model estimated 54% of people may be cured.

What it means

One of the strongest long-term immunotherapy results in any solid tumor. Applies specifically to dMMR tumors, found in about 1 in 4 endometrial cancers.