The efficacy and safety of setmelanotide in individuals with Bardet-Biedl syndrome or Alstrom syndrome: Phase 3 trial design

Background: A phase 2 trial has suggested that treatment with the melanocortin-4 receptor (MC4R) agonist setmelanotide is associated with a decrease in hunger and weight-related outcomes in participants with Bardet-Biedl syndrome (BBS) and Alstrom syndrome. Here, we present the study design of an ongoing, randomized, double-blind, placebo-controlled, phase 3 trial to assess the long-term efficacy and safety of setmelanotide for the treatment of obesity and hyperphagia in individuals with BBS or Alstrom syndrome (ClinicalTrials.gov identifier: NCT03746522). Methods: It was initially planned that similar to 30 participants aged >= 6 years with a clinical diagnosis of BBS or Alstrom syndrome would be enrolled. Participants with obesity as defined by a body mass index >= 30 kg/m(2) (in those aged >= 16 years) or a weight >97th percentile (in those aged 6-15 years) are included. Participants are initially randomized in a 1:1 ratio to receive setmelanotide or placebo for 14 weeks (period 1). Following period 1, all participants receive 38 weeks of open-label treatment with setmelanotide (period 2). In each treatment period, setmelanotide is administered at 3 mg once a day following completion of dose escalation. The primary endpoint is the proportion of participants aged >= 12 years achieving a clinically meaningful reduction from baseline (>= 10%) in body weight after similar to 52 weeks (eg, following period 2). Safety and tolerability are assessed by frequency of adverse events. Conclusions: This pivotal trial is designed to evaluate the efficacy and safety of setmelanotide for the treatment of obesity and hyperphagia in individuals with BBS and Alstrom syndrome. Submission category: Study Design, Statistical Design, Study Protocols.