Poster Presentation Clinical Oncology Society of Australia Annual Scientific Meeting 2024

Time Course of Adverse Events in Primary Advanced or Recurrent Endometrial Cancer Treated with Dostarlimab Plus Chemotherapy in the ENGOT-EN-6-NSGO/GOG-3031/RUBY Trial (#225)

Elizabeth Lokich 1 , Trine L. Jørgensen 2 , Destin Black 3 , David Cibula 4 , Lucy Gilbert 5 , Antonella Savarese 6 , Matthew A. Powell 7 , Rebecca Herbertson 8 , Sarah E. Gill 9 , Bradley J. Monk 10 , Nicole Nevadunsky 11 , Kari L. Ring 12 , Noelle Cloven 13 , Iwona Podzielinski 14 , Tashanna Myers 15 , Ashish Banerjee 16 , Christine Dabrowski 17 , Shadi Stevens 18 , Lyndsay Willmott 19 , Mansoor R. Mirza 20
  1. Women and Infants Hospital of Rhode Island, Providence, Rhode Island, USA
  2. Department of Oncology, Odense University Hospital, Odense, Denmark
  3. Willis-Knighton Cancer Center, Willis-Knighton Health System, Gynecologic Oncology Associates, Shreveport, LA, USA
  4. Department of Gynaecology, Obstetrics, and Neonatology, General University Hospital in Prague, First Faculty of Medicine, Charles University, Prague, Czech Republic
  5. Division of Gynecologic Oncology, , McGill University Health Centre and the Gerald Bronfman Department of Oncology, McGill University, Montreal, QC, Canada
  6. Medical Oncology 1, IRCCS Regina Elena National Cancer Institute, Rome, Italy
  7. National Cancer Institute sponsored NRG Oncology, Washington University School of Medicine, St Louis, MO, USA
  8. Sussex Cancer Centre, Royal Sussex County Hospital, Brighton, UK
  9. St. Joseph's/Candler Gynecologic Oncology & Surgical Specialists, Candler Hospital, Savannah, GA, USA
  10. GOG Foundation; Florida Cancer Specialists and Research Institute, West Palm Beach, FL, USA
  11. Department of Obstetrics, Gynecology, and Women’s Health, Montefiore Medical Center, Bronx, NY, USA
  12. University of Virginia Health System, Charlottesville, VA, USA
  13. Texas Oncology, Fort Worth, TX, USA
  14. Department of Gynecologic Oncology, Parkview Health, Fort Wayne, IN, USA
  15. Baystate Medical Center, Division of Gynecologic Oncology, University of Massachusetts-Chan Baystate, Springfield, MA, USA
  16. GSK, Melbourne, Australia
  17. GSK, Collegeville, PA, USA
  18. GSK, London, UK
  19. Arizona Oncology, Phoenix, AZ, USA
  20. Rigshospitalet, Copenhagen University Hospital, Copenhagen, and Nordic Society of Gynaecologic Oncology-Clinical Trial Unit, Copenhagen, Denmark

Aims: Safety has been reported for immunotherapy+chemotherapy combinations in endometrial cancer (EC), although the timing of adverse events (AEs) and the longer-term AE profile is not yet clear. This analysis examines the time course of study treatment–related AEs (TRAEs) during the phase 3 RUBY trial (NCT03981796; funding: GSK study 213361) of dostarlimab+carboplatin-paclitaxel (CP) versus placebo+CP in patients with primary advanced or recurrent EC (pA/rEC).

Methods: Patients with pA/rEC were randomized 1:1 to dostarlimab+CP or placebo+CP Q3W (6 cycles), then dostarlimab or placebo monotherapy Q6W for up to 3 years. AEs were assessed per Common Terminology Criteria for Adverse Events v4.03 and summarized by quarter.

Results: The safety population included 487 patients who received ≥1 dose of treatment (dostarlimab+CP: n=241; placebo+CP: n=246). TRAEs occurred in 97.9% and 98.8% of patients in the dostarlimab+CP and placebo+CP arms, respectively. The most common TRAEs in the dostarlimab+CP and placebo+CP groups were alopecia (52.3% and 48.4%), fatigue (47.7% and 48.0%), and nausea (45.6% and 40.7%). In both arms, the majority of the most common TRAEs (≥30%) and grade ≥3 TRAEs (≥10%) occurred within the first 3–6 months of treatment; TRAEs occurred after the first 12 months in 2.5% and 0.4% of the dostarlimab+CP and placebo+CP arms, respectively. The timing of immune-related AEs was generally consistent with this finding.

Conclusions: Most TRAEs seen in the RUBY trial occurred within the first 3–6 months, with limited differences between arms. This timing is consistent with the patients’ receipt of chemotherapy. Few patients experienced onset of new TRAEs in the dostarlimab+CP arm after 12 months. These data further support a favorable long-term benefit-risk profile of dostarlimab+CP in patients with pA/rEC. 

©2024 American Society of Clinical Oncology, Inc. Reused with permission. This abstract was accepted and previously presented at the 2024 ASCO Annual Meeting. All rights reserved.