O-305 SPIRIT long-term extension study: two-year efficacy and safety of relugolix combination therapy in women with endometriosis-associated pain

Abstract Study question To assess the long-term efficacy and safety of once-daily Relugolix combination therapy (Relugolix-CT) in the treatment of endometriosis-associated pain over two years. Summary answer Relugolix-CT previously demonstrated sustained improvement of endometriosis-associated pain and was generally well tolerated over 52 weeks. Research is ongoing: two-year results will be reported. What is known already SPIRIT 1&2 were international, Phase 3, replicate, randomized, double-blind, placebo-controlled studies of Relugolix-CT (relugolix 40mg, estradiol 1mg, norethisterone acetate 0.5mg) in premenopausal women with moderate-to-severe endometriosis-associated pain, which were followed by the open-label, 80-week, long-term extension. 52-week results showed sustained improvement in dysmenorrhea and non-menstrual pelvic pain (NMPP) with 84.8% and 73.3% of responders, respectively. Efficacy was evidenced by reductions in dysmenorrhea (82.8%,) NMPP (62.9%,) proportion of women using opioids, and improvements in function. Relugolix-CT was generally well tolerated. Bone mineral density (BMD) assessment showed minimal initial decline (<1%) from baseline followed by stabilization from Week 24 to 52. Study design, size, duration Women who completed the 24-week pivotal studies (SPIRIT 1&2) were eligible to enroll in an 80-week open-label, single-arm, long-term extension study of safety and efficacy, representing up to 104 weeks of treatment in total. All women enrolled in the long-term extension study received once-daily oral Relugolix-CT. Analyses were performed based on the initial randomized treatment groups in pivotal studies: Relugolix-CT, delayed Relugolix-CT (relugolix 40mg alone for 12 weeks, then Relugolix-CT for 12 weeks), or placebo. Participants/materials, setting, methods Primary endpoints are proportion of dysmenorrhea and NMPP responders at Weeks 52 and 104 based on daily Numerical Rating Scale (NRS) scores (0=no pain, 10=worst pain imaginable) and analgesic use. Responders are women who achieved a predefined, clinically meaningful reduction from baseline in NRS score and no increase in analgesic use. Secondary efficacy endpoints include change in Endometriosis Health Profile-30 pain domain scores, use of opioids/analgesics. Safety endpoints include adverse events and BMD (percent change). Main results and the role of chance Of 1251 randomized patients in SPIRIT 1&2, 1044 (83.4%) completed the pivotal studies; 802 (76.8%) enrolled in the long-term extension, and 681 (84.9%) completed 52 weeks of treatment. Baseline demographics and clinical characteristics of the long-term extension population were consistent with those of the pivotal study population. The study remains ongoing at the time of writing. Efficacy and safety data with Relugolix-CT for up to Week 104, will be presented at the scientific session of the 2022 congress. Limitations, reasons for caution The study was conducted as an open-label study without a control group over the 80 weeks of the extension period. Wider implications of the findings Through 52 weeks of treatment, Relugolix-CT demonstrated sustained improvement of dysmenorrhea, NMPP, function, and reduced need for opiates in women with endometriosis-associated pain. No new safety concerns were identified, and treatment was associated with BMD loss <1%. Data from 104 weeks of treatment will be presented at the 2022 congress. Trial registration number NCT03654274