Addition of Immunotherapy Continues to Show Survival Benefit in Prolonged Follow-up in NRG Oncology Trial for Primary Advanced Stage or Recurrent Endometrial Cancer

05/29/2026

Previously, immature overall survival results of the NRG Oncology GY018 (NRG-GY018) trial suggested that the use of the immunotherapy drug pembrolizumab in combination with chemotherapy improved overall survival for patients with advanced stage or recurrent endometrial cancer when compared to chemotherapy alone. Notably, this benefit was observed in both the mismatch repair proficient (pMMR) and mismatch repair deficient (dMMR) populations. An analysis of the study data, with prolonged follow-up, demonstrated that there was a sustained numerical benefit in overall survival for patients who received pembrolizumab with chemotherapy even when a large proportion of the initial placebo treated patients received post-protocol immunotherapy. These results were presented during the Gynecologic Oncology Session at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting.

“These findings are particularly important because they address a long-standing gap in the treatment of advanced and recurrent endometrial cancer which historically has been plagued by poor outcomes and limited therapeutic progress,” stated Ramez N. Eskander, MD, of the University of California, San Diego and the lead author of the NRG-GY018 abstract. “The fact that the survival advantage persisted in the dMMR and pMMR EC populations, adds great confidence to the use pembrolizumab in combination with chemotherapy in treatment of appropriately selected patients, irrespective of MMR status.  In the pMMR EC cohort, the persistent non-statistically significant but notable benefit in overall survival, despite substantial post study immunotherapy utilization, may suggest that early incorporation of this regimen provides greatest clinical benefit.”

Despite the change in treatment for the patients on the reference arm of this study, patients that initially received pembrolizumab and chemotherapy on the experimental arm among the pMMR group still experienced a 9.3-month median overall survival benefit in the prolonged follow-up analysis.

Patients on NRG-GY018 randomly assigned  809 patients to receive either pembrolizumab or placebo with carboplatin and paclitaxel chemotherapy. Overall survival analysis data were cut off on April 14, 2026, with information fraction of 43% and 82% in the dMMR and pMMR EC cohorts, respectively.

In the prolonged follow-up, the addition of pembrolizumab resulted in a sustained overall survival benefit in the dMMR endometrial cancer cohort. At 48 months, 79% of the dMMR patients treated with pembrolizumab were alive versus 60% of the patients treated with placebo, HR 0.56 (95% CI 0.34 to 0.92). This benefit continued despite at least 93% of dMMR endometrial cancer patients in the control arm, who received subsequent treatment, receiving post-study immunotherapy. In the pMMR population, the median overall survival was 44.4 months versus 35.1 months for the patients receiving placebo. Again, the survival benefit continued despite at least 81% of pMMR endometrial cancer patients in the control arm receiving post-study immunotherapy.

This  project was supported by the NRG Oncology Operations grant U10CA180868 and the NRG Oncology SDMC grant U10CA180822 from the National Cancer Institute (NCI), part of the National Institutes of Health and conducted by the NCI National Clinical Trials Network. Funding and support were also received from Merck & Co., Inc. through a Cooperative Research and Developmental Agreement with NCI. NRG-GY018 was conducted with funding supplemental to the CRADA from Merck in an Agreement between Merck and The GOG Foundation d/b/a NRG Oncology Philadelphia East.

Special Podcast Episode

Follow The NRG Oncology Podcast on Spotify, Apple Podcasts, and YouTube for a special episode interviewing Dr. Ramez Eskander on the findings of the 2026 ASCO Presentation for NRG-GY018. Podcast information and playable episodes are available on the NRG website as well.

Citation
Eskander RN, Sill MW, Beffa L, Moore RG, Hope JM, Musa FB, Mannel RS, Shahin MS, Cantuaria GH, Girda E, Matthews C, Kavecansky J, Leath III CA, Gien L, Hinchcliff EM, Lele SB, Landrum L, Backes F, Powell MA, Aghajanian C. Pembrolizumab Plus Chemotherapy In Advanced Or Recurrent Endometrial Cancer: Updated Overall Survival And Exploratory Analysis Of Response To Post-Study Immune Checkpoint Inhibition In The NRG GY018 Phase 3 Randomized Trial. Paper presented during the Gynecologic Oncology Session at the annual meeting of the American Society of Clinical Oncology. Chicago, IL. (2026, May).

About NRG Oncology
NRG Oncology conducts practice-changing, multi-institutional clinical and translational research to improve the lives of patients with cancer. Founded in 2012, NRG Oncology is a Pennsylvania-based nonprofit corporation that integrates the research of the legacy National Surgical Adjuvant Breast and Bowel Project (NSABP), Radiation Therapy Oncology Group (RTOG), and Gynecologic Oncology Group (GOG) programs. The research network seeks to carry out clinical trials with emphasis on sex-specific malignancies, including gynecologic, breast, and prostate cancers, and on localized or locally advanced cancers of all types. NRG Oncology’s extensive research organization comprises multidisciplinary investigators, including medical oncologists, radiation oncologists, surgeons, physicists, pathologists, and statisticians, and encompasses more than 1,300 research sites located world-wide with predominance in the United States and Canada. NRG Oncology is supported primarily through grants from the National Cancer Institute (NCI) and is one of five research groups in the NCI’s National Clinical Trials Network. www.nrgoncology.org