Dostarlimab Plus Chemotherapy Demonstrates Significant Overall Survival Benefit in Endometrial Cancer


In the RUBY phase 3 trial, dostarlimab (Jemperli; GSK) with niraparib (Zejula; GSK) had significant progression free survival compared to the standard of care.

Dostarlimab (Jemperli; GSK) plus chemotherapy showed statistically significant and clinically meaningful overall survival (OS) and progression free survival (PFS) in parts 1 and 2, respectively, of the RUBY/ENGOT-EN6/GOG3031/NSGO phase 3 trial for adults with primary advanced or recurrent endometrial cancer, according to a press release from the company.1

3d illustration proteins with lymphocytes, t cells or cancer cells | Image Credit: Design Cells -

Image Credit: Design Cells -

The data were presented as a late-breaking plenary session at the Society of Gynecologic Oncology 2024 Annual Meeting on Women’s Cancer from March 16 to March 18.1

“The positive data presented today further show how dostarlimab-based regimens could benefit a broader set of patients with endometrial cancer. The results we’ve seen to date comprise the growing body of evidence supporting the role of dostarlimab as the backbone of our immuno-oncology development program. Our goal is to continue to identify ways to use dostarlimab alone and in combination with other therapies to help improve outcomes for patients with limited treatment options,” Hesham Abdullah, MD, MSc, senior vice president and global head of oncology and research and development at GSK, said in the press release.1

According to the National Library of Medicine, the prevalence of endometrial cancer in the United State is approximately 25.7 per 100,000 women per year, with a peak diagnostic range of 55 to 64 years of age. Furthermore, the organization said that even with a lower risk of endometrial cancer, deaths due to this cancer in Black women are greater than in White women at 8.1 per 100,000 deaths per year versus 4.2 per 100,000 deaths per year.2

About The Ruby Trial

Trial Name: A Study to Evaluate Dostarlimab Plus Carboplatin-paclitaxel Versus Placebo Plus Carboplatin-paclitaxel in Participants With Recurrent or Primary Advanced Endometrial Cancer ID: NCT03981796

Sponsor: Tesaro Inc

Completion Date (Estimated): November 2026

The RUBY trial was intended to evaluate which patients with primary advanced or recurrent endometrial cancer could benefit from treatment with dostarlimab plus chemotherapy, with or without the addition of niraparib (Zejula; GSK) as maintenance. In part 1 of the trial, investigators evaluated dostarlimab plus carboplatin-paclitaxel followed by dostarlimab compared to chemotherapy and the placebo followed by the placebo. In part 2, they investigated dostarlimab plus the standard-of-care chemotherapy followed by dostarlimab plus niraparib as maintenance therapy compared to chemotherapy plus the placebo followed by the placebo, according to the press release.1

In part 1, investigators found that in the overall population, dostarlimab and chemotherapy reduced the risk of death by 31% compared to chemotherapy alone, with a median OS of 16.4 months. Furthermore, in the mismatch repair proficient (MMRp)/microsatellite stable (MSS) population, they found that the combination reduced the risk of death by 21% with an improvement of 7 months for the median OS.1

Grade 3 or higher and serious treatment-emergent adverse events (TEAEs) were approximately 12% higher for dostarlimab and chemotherapy compared to the placebo and chemotherapy. The safety profile for the combination was consistent with the mechanism of actions of dostarlimab and similar to those reported by other PD-(L)1 inhibitors, according to the press release. The discontinuation rate of dostarlimab or the placebo due to TEAEs was 19.1% and 8.1%, respectively.1

In part 2, dostarlimab plus chemotherapy followed by dostarlimab and niraparib demonstrated a statistically significant reduction in the risk of disease progression or death by 40%, with a median PFS of 6.2 months, according to the press release. In the MMRp/MSS population, the combination reduced the risk of disease progression or death by 37%, with a median PFS of 6 months.1

Further, grade 3 or higher and serious TEAEs were approximately 36% and 24% higher, respectively, in the combination arm and the placebo arm. Discontinuation of dostarlimab or the placebo due to TEAEs occurred in 24.1% and 5.2% of patients, respectively. Discontinuation of niraparib or the placebo was 15.7% and 4.2%, respectively, according to the press release.1

GSK expects the FDA to accept the regulatory submission based on the RUBY part 1 data for an expanded indication in the overall population in the first half of 2024, according to the news release.1

  1. Positive RUBY phase III data show potential for Jemperli (dostarlimab) combinations in more patients with primary advanced or recurrent endometrial cancer. News release. GSK. March 16, 2024. Accessed March 21, 2024.
  2. Mahdy H, Casey MJ, Crotzer D. Endometrial Cancer. [Updated 2022 Sep 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024.
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