Clinical Summary:

• Design/Population: Updated 6-year follow-up from the phase 1 GARNET trial evaluated dostarlimab monotherapy in patients with  dMMR/MSI-H advanced or recurrent endometrial cancer following platinum-based chemotherapy.
• Key Outcomes: Dostarlimab continued to demonstrate durable responses, with median duration of response and overall survival not reached after 6 years of follow-up. Conditional survival analyses suggested a high likelihood of long-term survival among patients who remained alive after the first several years of treatment.
• Clinical Relevance: These findings reinforce dostarlimab as an effective treatment option following platinum-based therapy.

Updated results from the phase 1 GARNET trial demonstrated durable long-term clinical benefit with dostarlimab monotherapy among patients with mismatch repair-deficient/microsatellite instability-high (dMMR/MSI-H) advanced or recurrent endometrial cancer.

These findings were presented by Bhavana Pothur, MD, NYU Langone Health, New York, New York, at the European Society for Medical Oncology (ESMO) Gynecological Cancers Congress in Copenhagen, Denmark.

In this open-label, single-arm trial, 143 patients who experienced disease progression following platinum-based chemotherapy received up to 2 years of dostarlimab, with continued treatment permitted beyond 2 years at investigator discretion. Primary end points included objective response rate (ORR) and duration of response. Key secondary end points included disease control rate and overall survival (OS). 

At a median follow-up of 69 months, ORR was 45.5%, with complete responses in 22.4% of patients and partial responses in 23.1% of patients. The disease control rate was 60.1%. Neither median duration of response nor median OS had been reached. The estimated 6-year disease control rate was 73.1%, and the estimated 6-year OS rate was 50.1%.

Conditional survival analyses demonstrated increasingly favorable long-term outcomes among patients who remained alive over time. Among patients alive at 1 year, 68.9% were estimated to remain alive at 6 years. Among those alive at 2 years and 3 years, the probability of remaining alive at 6 years increased to 86% and 88.3%, respectively.

“The substantial long-term benefit observed supports dostarlimab monotherapy as a meaningful option in pts with dMMR/MSI-H [advanced or recurrent endometrial cancer] with disease progression following prior platinum therapy,” concluded study authors. 

Source: 

Oaknin A, Sabatier R, Pothuri B, et al. Six-year survival outcomes with dostarlimab monotherapy in patients (pts) with mismatch repair-deficient/microsatellite-high (dMMR/MSI-H) endometrial cancer (EC) in the GARNET trial. Presented at ESMO Gynecological Cancers Congress. June 17-19, 2026. Copenhagen, Denmark. Abstract 69O.