Responder Analyses from a Phase 2b Dose-Ranging Study of Bremelanotide

Background Responder analyses are used to determine whether changes that occur during a clinical trial are clinically meaningful; for subjective endpoints such as those based on patient-reported outcomes (PROs), responder analyses are particularly useful. Aim To identify the minimal clinically important difference (MCID) for selected scores on questionnaires assessing female sexual functioning and to use these differences to analyze the response in a large, controlled, phase 2b, dose-finding study of bremelanotide in premenopausal women with hypoactive sexual desire disorder (HSDD) and mixed HSDD/female sexual arousal disorder (FSAD). Methods The responder analyses were performed for the change from baseline to end of study for a total of 7 endpoints. Each PRO endpoint was assessed using at least 1 of 4 types of responder analyses: a planned analysis anchored to MCIDs based on expert estimates (historical anchors); post hoc analyses based on self-reported global benefit; receiver operating characteristic (ROC) curves; and cumulative distribution function. The prespecified analysis groups were all female sexual dysfunction (FSD)-based diagnoses (all study participants), those with HSDD alone, and a combined group of those with FSAD alone plus those with mixed HSDD/FSAD. Post hoc analyses were also performed for subjects with mixed HSDD/FSAD with a primary diagnosis of HSDD. Outcomes MCIDs based on the ROC curves for changes in Female Sexual Function Index–desire domain, Female Sexual Distress Scale–Desire/Arousal/Orgasm (FSDS-DAO) total score, FSDS-DAO item 13 and 14 scores, and number of satisfying sexual events. Results Outcomes matched those based on input from clinical experts. For all 7 endpoints, responder rates at the 1.75 mg dose in the overall modified intention-to-treat population achieved statistical significance compared with placebo (P ≤ .03). Clinical Implications These responder definitions were subsequently used in the bremelanotide phase 3 registration studies (RECONNECT) that evaluated the safety and efficacy of the bremelanotide 1.75 mg subcutaneous dose in premenopausal women with HSDD. Strengths & Limitations MCIDs for this study were based on changes from a single-blind phase to account for changes due to the placebo effect. These analyses were restricted to a study population composed only of premenopausal women with a clinical diagnosis of HSDD and/or FSAD and were based on data from the same clinical trial. Conclusion Bremelanotide was safe and well tolerated and demonstrated significant improvement in efficacy vs placebo in the phase 2b trial. The multiple responder analyses offer a valuable approach for determining clinically important effects of bremelanotide for HSDD and FSAD.