Phase III RUBY trial of Jemperli (dostarlimab) plus chemotherapy meets endpoint of overall survival in patients with primary advanced or recurrent endometrial cancer

The trial met its primary endpoint of overall survival (OS), demonstrating a statistically significant and clinically meaningful benefit in the overall patient population.

A clinically meaningful OS benefit was observed in both prespecified subpopulations in the trial: mismatch repair deficient (dMMR)/microsatellite instability-high (MSI-H) and mismatch repair proficient (MMRp)/microsatellite stable (MSS) patient subgroups. OS is one of two primary endpoints in the RUBY Part 1 trial. Previously, the trial met its other primary endpoint of progression-free survival (PFS), demonstrating a 72% and 36% reduction in the risk of disease progression or death observed in the dMMR/MSI-H population (HR: 0.28 [95% CI: 0.16-0.50]) and overall patient population (HR: 0.64 [95% CI: 0.51–0.80]), respectively.

Hesham Abdullah, Senior Vice President, Global Head Oncology, R&D, GSK, said: “With these headline results from Part 1 of the phase III RUBY trial, dostarlimab plus chemotherapy has become the only immuno-therapy combination to show a survival benefit in this broader patient population in this treatment setting. We look forward to sharing detailed results of this analysis with regulatory authorities and the larger scientific community.”

Full results from this latest analysis from the trial will be published in a medical journal and presented at an upcoming scientific meeting.

The safety and tolerability profile of dostarlimab plus carboplatin and paclitaxel was generally consistent with the known safety profiles of the individual agents. The most common treatment-emergent adverse events ( greater than 25%) in patients receiving dostarlimab plus chemotherapy were nausea, alopecia, fatigue, peripheral neuropathy, anemia, arthralgia, constipation, diarrhoea and myalgia.

Currently, Jemperli has regulatory approvals in a certain subset of patients with endometrial cancer based on the previously reported positive results for the primary endpoint of progression-free survival in Part 1 of the RUBY trial. In July 2023, Jemperli received FDA approval in combination with carboplatin and paclitaxel, followed by Jemperli as a single agent for the treatment of adult patients with primary advanced or recurrent endometrial cancer that is mismatch repair deficient (dMMR), as determined by an FDA-approved test, or microsatellite instability-high (MSI-H). Jemperli was also approved in the United Kingdom in October 2023 in combination with platinum-containing chemotherapy for the treatment of adult patients with dMMR/MSI-H primary advanced or recurrent endometrial cancer and who are candidates for systemic therapy. The application remains under review in the European Union (EU), Australia, Canada, Switzerland and Singapore.