Dienogest for Treatment of Endometriosis in Women: A 28-Week, Open-Label, Extension Study.

Background: Dienogest provided significantly greater reduction in endometriosis-associated pelvic pain (EAPP) than placebo in a 24-week, randomized, double-blind study of Chinese women with endometriosis. The current open-label extension study investigated the efficacy and safety of dienogest for 28 additional weeks in this population. Patients and Methods: Women with endometriosis were eligible to enroll at completion of the 24-week, placebo-controlled study (n = 220). All women, regardless of prior study treatment, received dienogest 2 mg once daily for up to 28 weeks. Absolute change in EAPP from baseline on a 1-100 mm visual analog scale (VAS), bleeding pattern, adverse events (AEs), laboratory parameters, and bone mineral density (BMD) were evaluated. Results: The open-label study was completed by 203 (92.3%) women. At the end of open-label study, mean (SD) change from baseline in EAPP score on VAS was -43.1 mm (26.54 mm) and -39.8 mm (31.15 mm) in the prior-dienogest and prior-placebo groups, respectively. Other assessments confirmed that dienogest maintained or enhanced efficacy after 28 weeks of additional treatment. Dienogest initiation was associated with longer, but fewer, spotting/bleeding episodes. Bleeding frequency and intensity decreased progressively during continued treatment. Treatment-emergent AEs, generally mild or moderate, led to withdrawal in 2 (0.9%) patients during the open-label study. Dienogest had no effect on BMD. Conclusions: Dienogest 2 mg once daily is effective and safe in the long-term management of EAPP in Chinese women with endometriosis, with progressive decreases in EAPP and bleeding irregularities during continued treatment. Efficacy and safety results of this study were consistent with previous studies in Caucasian patients.