GSK’s Dostarlimab Demonstrates Improvement in PFS for Individuals With Endometrial Cancer

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Dostarlimab (Jemperli; GSK) plus the standard-of-care chemotherapy followed by dostarlimab demonstrated a clinically meaningful and statistically significant improvement in progression free survival (PFS) for adults with primary advanced or recurrent endometrial cancer, according to the interim results for part 1 of the RUBY/ENGOT-EN6/GOG3031/NSGO (NCT03981796) phase 3 trial.

“These positive results from the RUBY trial bring us 1 step closer to addressing the significant unmet needs of endometrial cancer patients and add to the growing body of evidence on dostarlimab, strengthening our belief in its potential to transform cancer treatment as a backbone immuno-oncology therapy,” Hesham Abdullah DRSc, senior vice president and global head of oncology at GSK, said in a statement.

Dostarlimab plus carboplatin-paclitaxel demonstrated PFS in the mismatch repair deficient (dMMR)/microsatellite instability-high (MSI-H) population and the overall population compared with the placebo.

The PFS was approximately 36.1% for the dostarlimab arm compared with 18.1% for the placebo arm at 24 months. For dMMR/MSI-H, the PFS was 61.4% and 18.1%, respectively, at 24 months.

Additionally, investigators found that there was a significant reduction in risk of disease progression or death in individuals with dMMR/MSI-H primary advanced or recurrent endometrial cancer in the dostarlimab plus chemotherapy treatment arm compared with the placebo plus chemotherapy arm.

The results of the first interim analysis showed that there was a clinically meaningful overall survival (OS) trend in the overall population among individuals who received the dostarlimab combination.

The OS for the overall patient population was 71.3% for the dostarlimab arm and 56% for the placebo arm at 24 months. Additionally, the OS for those with dMMR/MSI-H was 83.3% and 58.7%, respectively, at 24 months.

“Clinical practice has been waiting decades for a meaningful advancement in the standard of care for primary advanced or recurrent endometrial cancer. The results from the RUBY clinical trial, especially given the difficult-to-treat histologies included in the trial, demonstrate support for a new treatment standard with the addition of dostarlimab to current standard-of-care chemotherapy,” Mansoor Raza Mirza, MD, chief oncologist at Copenhagen University Hospital in Denmark, said in the statement.

The safety and tolerability profile of dostarlimab plus carboplatin-paclitaxel was generally consistent with the known safety profiles of each individual agent. The most common treatment-emergent adverse events (TEAEs) in both treatment arms for both populations were alopecia, fatigue, and nausea. Investigators reported 10% more TEAEs that were severe and serious in the dostarlimab arm compared with the placebo arm in the overall population.

Investigators reported that the analysis was done at 33% maturity and statistical significance was not reached at this time, so further analysis and follow up is planned.

The data were shared as part of the European Society for Medical Oncology Virtual Plenary, presented at the Society of Gynecologic Oncology Annual Meeting on Women’s Cancer, and published in The New England Journal of Medicine.

Reference

Phase 3 RUBY clinical trial demonstrates potential of Jemperli (dostarlimab) plus chemotherapy to redefine the treatment of primary advanced or recurrent endometrial cancer versus chemotherapy alone. News release. GSK. March 27, 2023. Accessed March 29, 2023. https://www.gsk.com/en-gb/media/press-releases/phase-iii-ruby-clinical-trial-demonstrates-potential-of-jemperli-plus-chemotherapy-to-redefine-the-treatment-of-primary-advanced-or-recurrent-endometrial-cancer/