Poster Presentation 2025 Joint Meeting of the COSA ASM and IPOS Congress

Patient-reported outcomes (PROs) in patients with ER+, HER2- advanced breast cancer (ABC) treated with imlunestrant, investigator’s choice standard endocrine therapy, or imlunestrant+abemaciclib: Results from the phase III EMBER-3 trial (126765)

Giuseppe Curigliano 1 2 , Joyce O'Shaughnessy 3 , François-Clément Bidard 4 , Sung-Bae Kim 5 , Eriko Tokunaga 6 , Philippe Aftimos 7 , Cristina Saura 8 , Lisa A Carey 9 , Meena Okera 10 , Everton Melo 11 , Flora Zagouri 12 , Manuel Ernesto Magallanes Maciel 13 , Nuri Karadurmus 14 , Shakeela Bahadur 15 , Rebecca M Soeck 16 , Xuejing Aimee Wang 16 , Suzanne Young 16 , Komal L Jhaveri 17 18 , Nadia Harbeck 19 20 , Dion Marinkovich 21
  1. University of Milano, Milano, Italy
  2. Italy and European Institute of Oncology, IRCCS, Milano, Italy
  3. Baylor University Medical Center, Texas Oncology, US Oncology, Dallas, Texas, USA
  4. Institut Curie and University of Versailles Saint-Quentin-en-Yvelines-Paris-Saclay University, Paris, France
  5. Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of South Korea
  6. National Hospital Organization (NHO) Kyushu Cancer Center, Fukuoka, Japan
  7. Institut Jules Bordet Hôpital Universitaire de Bruxelles, Brussels, Belgium
  8. Vall d'Hebron University Hospital, Vall d'Hebron Institute of Oncology, Barcelona, Spain
  9. University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
  10. Cancer Research SA, Adelaide, South Australia, Australia
  11. Hospital do Câncer de Londrina, Londrina, Brazil
  12. Department of Clinical Therapeutics, Medical School of National and Kapodistrian University of Athens, “Alexandra” General Hospital of Athens, Athens, Greece
  13. Centro Oncologico Internacional, Mexico City, Mexico
  14. Gülhane Education and Research Hospital, University of Health Sciences, Ankara, Turkey
  15. Mayo Clinic Arizona, Scottsdale, Arizona, USA
  16. Eli Lilly and Company, Indianapolis, Indiana, USA
  17. Memorial Sloan Kettering Cancer Center , New York, USA
  18. Weill Cornell Medical College , New York, USA
  19. Brustzentrum, Frauenklinik and CCC Munich, LMU University Hospital, Munich, Germany
  20. Ludwig Maximilians University Munich University Hospital, Munich, Germany
  21. Eli Lilly Australia, Sydney, Australia

In EMBER-3, patients with ER+, HER2- ABC with disease progression on or after aromatase inhibitor-based therapy, achieved significant PFS improvement with imlunestrant vs standard therapy (SOC: fulvestrant/exemestane) in patients with ESR1 mutations (ESR1m), and with imlunestrant+abemaciclib vs imlunestrant in all patients, regardless of ESR1m. Exploratory PRO analyses are presented here.

EORTC QLQ-C30 was administered at baseline and every 8 weeks until treatment discontinuation, with a longitudinal mixed model for repeated measures used to calculate mean change difference (MCD) from baseline. A 10-point change or difference was defined as clinically meaningful. PRO-CTCAE (diarrhea frequency) was administered weekly (0 [never] - 4 [almost constantly]). PRO-CTCAE (injection site reaction [ISR]) was administered to fulvestrant recipients weekly for 2 weeks post-injection (yes/no [pain/swelling/redness]).

In patients with ESR1m, EORTC QLQ-C30 scores were generally maintained, with treatment differences favoring imlunestrant vs SOC. Patients with ESR1m on imlunestrant had improved global health status (GHS)/QOL and physical function (PF) scores from baseline, while scores with SOC declined (MCD between treatments:7.4 [1.3,13.6]; 4.0 [-0.7,8.7]). In the overall population, GHS/QOL and functional scores were generally maintained, with treatment differences favoring imlunestrant vs SOC vs imlunestrant+abemaciclib. Most fulvestrant recipients (72%) reported ISR at any time while on treatment, with 47% reporting ISR at the majority of their assessments. Patients reported similarly low rates of “frequent” or “almost constant” diarrhea with imlunestrant (3%) and SOC (2%) and higher rates with imlunestrant+abemaciclib (22%).

GHS/QOL and PF were maintained across treatment arms in the EMBER-3 trial, despite the increased frequency of diarrhea in the imlunestrant+abemaciclib arm. The importance of ISR as a clinically relevant AE is demonstrated by the high incidence of patient-reported ISR with fulvestrant. These results support the efficacy and safety of imlunestrant as monotherapy or combined with abemaciclib as an all-oral targeted therapy option.