Dr Mirza on Long-Term Response Data for Dostarlimab Plus Chemo in Advanced Endometrial Cancer

“[Findings from] the phase 3 RUBY trial have completely changed the [treatment] of our patients in locally advanced and recurrent endometrial cancer with the addition of dostarlimab to standard-of-care carboplatin [plus] paclitaxel.”

Mansoor R. Mirza, MD, chief oncologist at Rigshospitalet, Copenhagen University Hospital, discusses updated findings from the phase 3 ENGOT-EN6-NSGO/GOG-3031/RUBY trial (NCT03981796) evaluating the efficacy of dostarlimab-gxly (Jemperli) plus carboplatin and paclitaxel compared with placebo plus carboplatin and paclitaxel in patients with primary advanced or recurrent endometrial cancer.

Data from the RUBY trial have supported a paradigm shift in the frontline management of endometrial cancer, Mirza begins. Dostarlimab, an anti–PD-1 monoclonal antibody, administered in combination with standard chemotherapy, demonstrated statistically and clinically significant improvements in progression-free survival (PFS) and overall survival (OS) across molecular subgroups.

Long-term response findings presented at the 2025 SGO Annual Meeting on Women’s Cancers showed at a median follow-up of 37.2 months, patients from the overall population treated in the dostarlimab arm (n = 245) experienced an overall response rate of 61.2% vs 57.0% for those treated in the placebo arm (n = 249). The median duration of response was 10.6 months (95% CI, 8.2-18.4) in the dostarlimab arm vs 6.2 months (95% CI, 4.4-6.7) in the placebo arm.

Mirza notes that clinical responses were observed early during therapy, with separation in progression-free survival curves beginning around cycle 2. This early onset of activity was maintained through extended follow-up, and updated analyses confirmed a sustained improvement in duration of response for the dostarlimab arm compared with placebo.

The trial design included dostarlimab initiation concurrent with chemotherapy and continuation as maintenance therapy. This approach contributed to early symptom improvement, enhanced quality of life, and durable disease control, Mirza adds.

These results helped establish a new standard of care for patients with advanced or recurrent endometrial cancer, particularly those with mismatch repair–deficient tumors, he concludes.