Long-term safety and efficacy of elagolix treatment in women with endometriosis-associated pain: Primary results from two phase 3 extension studies

Fertility and Sterility | September 13, 2017

Surrey E, et al. - The long-term safety and efficacy of elagolix, an oral, non-peptide gonadotropin-releasing hormone antagonist, for the management endometriosis-associated pain were assessed in this study. In dysmenorrhea (DYS) and non-menstrual pelvic pain (NMPP), elagolix provided sustained reductions in these two long-term extension studies (Elaris EM-III and Elaris EM-IV). With hypoestrogenic effects, the safety/tolerability was consistent. There were no new safety concerns with long-term elagolix use.


  • From two, extension studies (Elaris EM-III, n=287; Elaris EM-IV, n=282), the authors enrolled participants18-49 year old women with surgically diagnosed endometriosis and moderate/severe endometriosis-associated pain.
  • They assessed baseline prior to dosing in the pivotal studies.
  • The proportion of responders (pain reduction and stable/decreased rescue analgesic use) based on the average monthly dysmenorrhea (DYS) and non-menstrual pelvic pain (NMPP) scores were the co-primary efficacy endpoints.
  • New incidences of adverse events (AE) during the extension study, clinical laboratory tests, and changes in bone mineral density (BMD) were included in safety assessments.


  • Across both extension studies/dose groups, the reductions in DYS and NMPP following 6M of elagolix treatment reported in the pivotal studies were maintained over 12M of treatment.
  • At both doses, over 50% of women were responders for DYS and NMPP following 12M of elagolix treatment.
  • In this study, the proportion of women with new incidences of hot flush ranged between 4-8%.
  • The authors observed a dose-dependent decrease from baseline in BMD in the extension at M6 in both studies/dose groups.

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