Clinical Summary: 

• Design/Population: An updated analysis from the phase 3 RUBY trial evaluated long-term progression-free survival outcomes and curative potential among patients with dMMR/MSI-H primary advanced or recurrent endometrial cancer treated with dostarlimab plus carboplatin/paclitaxel.
• Key Outcomes: At a median follow-up of 55.6 months, the 4-year PFS rate was 57.9% with dostarlimab plus chemotherapy compared with 15.7% with chemotherapy alone. Mixture cure modeling estimated that 54% of patients treated with the dostarlimab-based regimen may achieve curative potential.
• Clinical Relevance: These findings suggest that frontline dostarlimab plus chemotherapy may provide durable long-term disease control and possible cure for a substantial proportion of patients with dMMR/MSI-H endometrial cancer.

Updated results from the phase 3 RUBY trial demonstrate that dostarlimab plus chemotherapy provides durable progression-free survival (PFS) benefit to patients with mismatch repair-deficient or microsatellite instability-high (dMMR/MSI-H) primary advanced or recurrent endometrial cancer, with mixture cure modeling suggesting that a substantial proportion of patients may achieve long-term curative potential.

These results were presented by Matthew Powell, MD, Siteman Cancer Center, St. Louis, Missouri, at the American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, Illinois.

For this analysis, investigators applied mixture cure modeling to long-term PFS data to estimate the proportion of patients potentially achieving cure. Patients categorized as “cured” within the model were assumed to have no ongoing risk of recurrence-related mortality and mortality rates comparable to those of the matched general population. 

At analysis, 4 new PFS events were reported. The 4-year PFS rate was 57.9% in the dostarlimab plus chemotherapy arm and 15.7% in the chemotherapy arm. Mixture cure modeling estimated that 54% of patients treated with dostarlimab plus chemotherapy could be considered “cured.” Investigators noted that the model-generated PFS curves closely aligned with the Kaplan-Meier curves observed in RUBY and accurately captured the long-term survival plateau, supporting the robustness of the model predictions.

“With a minimum of 4 years of follow-up, updated PFS analyses demonstrated that the majority of patients remained alive and progression-free, illustrating durable disease control,” concluded Dr Powell. “These analyses may assist oncologists in understanding long-term survival outcomes and the proportion of patients with a curative potential.”

Source: 

Powell MA, Zub O, Raashouu-Jensen N, et al. Long-term survival rates and cure modeling with dostarlimab plus chemotherapy in mismatch repair deficient/microsatellite instability-high (dMMR/MSI-H) primary advanced or recurrent endometrial cancer in the ENGOT-EN6-NSGO/GOG-3031/RUBY trial. Presented at the ASCO Annual Meeting. May 29 - June 2, 2026. Chicago, Illinois. Abstract 5501.