Poster Presentation Clinical Oncology Society of Australia Annual Scientific Meeting 2024

Post-Progression Survival Outcomes in Patients with Primary Advanced or Recurrent Endometrial Cancer (pA/rEC) in the ENGOT-EN6-NSGO/GOG-3031/RUBY Trial Who Received Follow-up Immunotherapy (#226)

Mansoor R. Mirza 1 , Cara Mathews 2 , Lucy Gilbert 3 , Line Bjørge 4 , Kari L. Ring 5 , Mikalai Pishchyk 6 , Kathryn Pennington 7 , Yakir Segev 8 , Matthew A. Powell 9 , Toon Van Gorp 10 , David Bender 11 , Kellie Schneider 12 , Rachel Miller 13 , Amy Armstrong 14 , Guilherme Cantuaria 15 , Radhika Gogoi 16 , Ashish Banerjee 17 , Grace Antony 18 , Shadi Stevens 18 , Giorgio Valabrega 19 , Lisa M. Landrum 20
  1. Rigshospitalet, Copenhagen University Hospital, Copenhagen, and Nordic Society of Gynaecologic Oncology-Clinical Trial Unit, Copenhagen, Denmark
  2. Women and Infants Hospital of Rhode Island, Providence, Rhode Island, USA
  3. Division of Gynecologic Oncology, , McGill University Health Centre and the Gerald Bronfman Department of Oncology, McGill University, Montreal, QC, Canada
  4. Haukeland University Hospital, Bergen, and University of Bergen, Bergen, Norway
  5. University of Virginia Health System, Charlottesville, VA, USA
  6. Medical Oncology 1, IRCCS Regina Elena National Cancer Institute, Rome, Italy
  7. Fred Hutchinson Cancer Center, University of Washington Medical Center, Seattle, WA, USA
  8. Carmel Medical Center, Technion-Israel Institute of Technology, Haifa, Israel
  9. National Cancer Institute-sponsored NRG Oncology; Washington University School of Medicine, St. Louis, Missouri, USA
  10. University Hospital Leuven, Leuven Cancer Institute, KU Leuven, Belgium and the Belgian and Luxembourg Gynaecological Oncology Group (BGOG), Belgium and Luxembourg
  11. Department of Obstetrics and Gynecology, University of Iowa, Iowa City, IA, USA
  12. Department of Gynecologic Oncology, Novant Health Cancer Institute, Charlotte, NC, USA
  13. Department of Obstetrics and Gynecology, Markey Cancer Center, Lexington, KY, USA
  14. Division of Gynecologic Oncology, University Hospitals Cleveland Medical Center, Case Comprehensive Cancer Center, Cleveland, OH, USA
  15. Northside Hospital, University Gynecologic Oncology, Atlanta, GA, USA
  16. Department of Gynecologic Oncology, Karmanos Cancer Institute, Wayne State University, Detroit, MI, USA
  17. GSK, Melbourne, Australia
  18. GSK, London, UK
  19. Department of Oncology, Ordine Mauriziano Torino and University of Torino, Torino, Italy
  20. Indiana University Health & Simon Cancer Center, Indianapolis, IN, USA

Aims: In Part 1 of the phase 3 ENGOT-EN6-NSGO/GOG-3031/RUBY trial (NCT03981796; funding: GSK), dostarlimab+carboplatin-paclitaxel (CP) significantly improved PFS (HR 0.64) and OS (HR 0.69) vs placebo+CP in the overall population of patients with pA/rEC. Limited data are available on outcomes with follow-up anticancer treatment (FUACT) after dostarlimab+CP. Here we report post-progression survival outcomes of patients in the overall and mismatch repair proficient/microsatellite stable (MMRp/MSS) populations who received FUACT of immunotherapy (IO).

Methods: Patients were randomized 1:1 to receive dostarlimab/placebo+CP Q3W (6 cycles) followed by dostarlimab/placebo monotherapy Q6W for ≤3 years. At interim analysis 2 (37.2 mo of follow-up), updated post hoc analyses of OS adjusted for treatment switching via rank-preserving structural failure time (RPSFT) were performed in the overall and MMRp/MSS populations of pts who received FUACT of IO and for patients receiving pembrolizumab-lenvatinib (PEM-LEN) in the MMRp/MSS population.

Results: In total, 494 patients were randomized. FUACT of IO was received by 137 and 102 patients in the overall and MMRp/MSS populations, respectively; PEM-LEN was received by 65 patients in the MMRp/MSS population.

Approximately twice as many patients received FUACT of IO in the placebo+CP versus dostarlimab+CP arm. When adjusted for subsequent IO, RPSFT analyses showed HRs of 0.63 (overall) and 0.76 (MMRp/MSS) for dostarlimab+CP vs placebo+CP, consistent with the unadjusted HRs for OS in the primary analysis. In the MMRp/MSS population receiving subsequent PEM-LEN, HR of RPSFT-adjusted OS was also consistent at 0.77.

Conclusions: Adjusted OS using RPSFT for subsequent use of IO in the overall and MMRp/MSS populations, including PEM-LEN in the MMRp/MSS population, showed limited impact on survival benefits, supporting frontline use of dostarlimab+CP as standard of care in all patients with pA/rEC.

Previously presented at the European Society of Medical Oncology Congress 2024, poster/oral: 731P, Mirza MR, et al. – reused with permission.