Dr Mirza on Dostarlimab Plus Chemotherapy in Endometrial Cancer

Mansoor Raza Mirza, MD, chief oncologist, Department of Oncology, Rigshospitalet, Copenhagen University Hospital, discusses findings from the phase 3 RUBY trial (NCT03981796) in patients with endometrial cancer.

Carboplatin plus paclitaxel is the frontline standard of care for patients with primary advanced or recurrent endometrial cancer. RUBY is evaluating the combination of dostarlimab-gxly (Jemperli), a PD-1 inhibitor, plus carboplatin and paclitaxel vs placebo, carboplatin, and paclitaxel in patients with primary advanced or recurrent endometrial cancer. In February, 2023, the FDA approved dostarlimab monotherapy in patients with recurrent or advanced mismatch repair–deficient (dMMR) endometrial cancer who have progressed on or after prior platinum-based therapy.

The primary end points of RUBY are progression-free survival (PFS) and overall survival (OS). Of the 494 patients enrolled in this trial, 47.8%, 18.6%, and 33.6% had recurrent, primary stage III, and primary stage IV disease, respectively.

Findings from the interim analysis of RUBY show an improved PFS in the dMMR population, Mirza says. At a median follow-up of 24.79 months, in the dMMR population, the 2-year PFS rate was 61.4%, with a hazard ratio (HR) of 0.28. Notably, after 12 months of follow-up, no additional patients in this population had disease progression, indicating that some of the patients treated with the dostarlimab combination may have been cured, Mirza emphasizes. In the overall population, the PFS in patients who received the dostarlimab combination had an HR of 0.64.

Additionally, treatment with dostarlimab produced a trend toward OS improvement in both the dMMR and mismatch repair–proficient (pMMR) subgroups, although these data are only 33% mature, Mirza explains. The HRs for OS in the intent-to-treat and dMMR populations were 0.64 and 0.30, respectively. Although more follow-up time is needed to determine the efficacy of the dostarlimab combination, these interim findings are promising, Mirza notes. The OS data in the dMMR and pMMR subgroups are also still immature, warranting continued follow-up, Mirza says. Overall, these PFS and OS findings, particularly in the dMMR subgroup, are unprecedented, Mirza concludes.

Editor’s Note: Dr Mirza reports being on the advisory board for AstraZeneca, Biocad, GSK, Karyopharm, Merck, Roche, and Zailab; being an invited speaker for AstraZeneca and GSK; a member of the Board of Directors for Karyopharm; holding stocks or shares in Karyopharm; receiving research grants (inst.) from Apexigen, AstraZeneca, GSK, and Ultimovacs; and being a trial chair for Deciphera (inst.).