Long-Term Safety of Elagolix With Add-Back in Women With Endometriosis-Associated Pain: 36-Month Results [ID: 1368036]

INTRODUCTION: Herein, we report updated safety results to 36 months from an ongoing phase 3, 48-month study evaluating the long-term safety of elagolix (ELA) with add-back (AB) for endometriosis-associated pain (EAP) (NCT03213457). METHODS: Premenopausal women with moderate-to-severe EAP were randomized in this IRB-approved study 4:1:2 to receive 12-month blinded treatment with ELA 200 mg twice daily (BID)+AB, ELA 200 mg BID for 6 months followed by 6-month ELA+AB, or placebo; followed by open-label ELA+AB for all patients for 36 months. This 36-month analysis assessed long-term safety, including bone mineral density (BMD). RESULTS: Throughout the open-label treatment period up to 36 months, BMD mean percent change from baseline measurements remained relatively stable at the total hip and lumbar spine and showed a decrease between 1% and 2% in the femoral neck over the open-label period. At 36 months, mean percent change from baseline in BMD for patients treated with ELA+AB throughout the study was −0.77% (spine, n=94); −0.36% (total hip, n=92); and −1.39% (femoral neck, n=92). The overall safety profile of ELA+AB, including AEs and SAEs, observed up to 36 months of treatment continues to be consistent with that previously observed at 12 and 24 months. CONCLUSION: This was the longest evaluation of ELA+AB to date. ELA+AB continued to maintain a favorable safety profile with minimal long-term effect on BMD and no newly identified safety events to 36 months. Combined with previously reported efficacy data, these safety data suggest ELA+AB may provide a long-term therapeutic option for women with EAP beyond 24 months.