Vilaprisan for the treatment of symptomatic endometriosis: results from a terminated phase 2b randomized controlled trial

Abstract

ObjectiveEvaluate efficacy and safety of two doses of vilaprisan versus placebo in participants with symptomatic endometriosis. DesignMulticenter, randomized, double-blind, placebo-controlled, parallel-group phase 2b trial (NCT03573336). The initially planned sample size was 315 patients. Recruitment was paused to assess long-term toxicity findings in rodents; although findings were assessed as likely to be of limited clinical relevance in humans, the study was closed by the sponsor. During the pause, enrolled patients completed 3 or 6 months of treatment per their assigned regimen. ParticipantsPre-menopausal adults with confirmed endometriosis and moderate-to-severe pelvic pain (≥4/10 on a numerical rating scale) were enrolled. Inclusion required protocol adherence, including ≥24 diary entries, and an average pain score of ≥3.5. InterventionParticipants were randomly assigned 1:1:1 to receive vilaprisan 2 mg, vilaprisan 4 mg, or placebo. Main Outcome MeasuresPrimary outcome was change in 7-day mean “worst pain” (per the Endometriosis Symptom Diary item 1) from baseline to Month 3. All analyses were descriptive only. ResultsEight participants were randomly assigned to treatment before the study pause: six received vilaprisan (4 mg, n=4; 2 mg, n=2) and two received placebo. The six vilaprisan recipients experienced an improvement in endometriosis-associated pelvic pain, whereas the two placebo recipients experienced no change or increased pain; all eight participants had decreased use of pain medication. Bleeding intensity decreased from baseline in the vilaprisan group. ConclusionThe study findings suggest that vilaprisan may improve outcomes in patients with endometriosis. Further studies in larger populations would be needed to accurately assess treatment effects.