Hope on the Horizon
Phase 3 RUBY trial demonstrated positive outcomes for patients with primary advanced or recurrent endometrial cancer.
During today’s session, “Focused Forum VII: Beyond the Standard — Innovations in Endometrial Cancer Care,” five physician-scientists presented their latest research on the most common form of gynecologic cancer. In the United States, there are approximately 70,000 cases of endometrial cancer each year, with 30% of individuals requiring treatment for disease spread or recurrence.
One speaker, Matthew A. Powell, MD, reviewed his abstract, “Four-year survival outcomes with dostarlimab plus chemotherapy in dMMR/MSI-H primary advanced or recurrent endometrial cancer in the ENGOT-EN6-NSGO/GOG-3031/RUBY trial.” Dr. Powell is the Ira C. and Judith Gall Professor in the division of gynecologic oncology, Washington University School of Medicine in St. Louis, Missouri. He will also be inducted as the SGO’s new president at the conclusion of the SGO 2026 Annual Meeting.
A fundamental finding from the RUBY trial, he said, was the validated efficacy and safety results of dostarlimab in combination with carboplatin and paclitaxel with a minimum four-year follow-up. This includes clinically meaningful improvements in progression-free survival (PFS) and overall survival (OS) compared to placebo plus chemotherapy.
Dr. Powell said he wasn’t necessarily surprised by the positive findings but was happy to have confirmed the lasting effects of the therapeutic regimen.
“We were very encouraged that dostarlimab plus carboplatin-paclitaxel showed sustained long-term PFS and OS benefits in patients with dMMR/MSI-H primary advanced or recurrent endometrial cancer. It is looking like these patients are cured of their disease,” he said.
The phase 3 RUBY trial evaluated progression-free patients at one-, two-, and three-year checkpoints to assess the probability of them surviving beyond those times. Patients in the dMMR/MSI-H cohort who received dostarlimab plus chemotherapy and were progression-free at one-year had an 88.6% chance of remaining progression-free at four years, Dr. Powell said. This is a statistically significant conditional survival analysis.
The study also demonstrated a robust OS benefit at four years in the dostarlimab plus chemo population. Median OS had a 66% reduction in mortality risk (0.34 hazard ratio), which was consistent with earlier analysis, Dr. Powell reported. The safety profile of dostarlimab plus carboplatin-paclitaxel also remained similar to previously reported data.
Dr. Powell was senior author and lead U.S. investigator for the previous paper, “Dostarlimab for Primary Advanced or Recurrent Endometrial Cancer,” that was published March 2023 in the New England Journal of Medicine.
“This study, and those similar, have changed the standard of care for these patients with previously likely incurable cancer,” Dr. Powell said.
The research team has already launched a follow-up trial through the NCI-sponsored NRG oncology group called NRG GY-035.
“The subsequent trial will evaluate adding bevacizumab to these immunotherapy-containing regimens for patients who have tumors with mutation in the p53 gene,” Dr. Powell said. “We look forward to developing additional therapies to help these patients.”
