Semaglutide Treatment, Appetite, and Eating Behavior: Long-term Effects

This trial consists of a single 72-week treatment period during which two studies will be conducted. Study 1 (i.e., long-term treatment trial; weeks 0-60) is a 60-week, single center, double-blinded, randomized controlled, parallel group design trial, and Study 2 (i.e., re-randomized medication withdrawal trial; weeks 60-72) is a separate, 12-week, double-blind, re-randomized medication withdrawal trial. The long-term treatment trial (Study 1) will randomly assign (in a 3:2 semaglutide:placebo ratio) 120 subjects with a body mass index (BMI) ≥30 kg/m2, or ≥27 kg/m2 with ≥1 obesity-related co-morbidities, to 60 weeks of: 1) placebo with moderate intensity lifestyle intervention (as used in STEP 1); or 2) semaglutide 2.4 mg with the same lifestyle intervention. All subjects will receive 60 weeks of trial product, which will be up-titrated over 16 weeks in those assigned to semaglutide 2.4 mg. They will complete assessments of energy intake, appetite, food reward, mood, symptoms of disordered eating, and anthropomorphic measurements at baseline (week 0) and weeks 20, 40, and 60. The primary aim in the initial long-term treatment trial will be to compare the long-term effect of semaglutide 2.4 mg vs placebo on ad libitum energy intake during a lunch meal at weeks 20, 40, and 60. Confirmatory secondary aims will test the effect of semaglutide 2.4 mg at weeks 20, 40 and 60 on subjective appetite ratings (both measured during a standardized breakfast in the lab and as experienced more globally over the past week), explicit food reward, as measured with the Power of Food Scale (24), and implicit food reward, as measured with the Leeds Food Preference Task (25, 26). Measures of food cravings, mood, eating disorder symptoms, and self-report measures of eating behavior will be considered supportive secondary endpoints and will provide additional evidence of the medication's safety and efficacy. Following the completion of Study 1 at week 60, all subjects who complete a week 60 assessment and remain on drug will be enrolled in Study 2. Semaglutide-treated subjects will be re-randomized (in a 1:4 semaglutide:placebo ratio) to receive semaglutide 2.4 mg or placebo for 12 weeks. All subjects originally assigned to placebo will continue with that medication for an additional 12 weeks. Both researchers and subjects will remain blinded to subjects' original and re-randomized (or continued) treatment assignments. The goal of this re-randomized medication withdrawal period will be to compare the 80% of subjects originally assigned to semaglutide 2.4 mg who receive placebo at week 60 (semaglutide-to-placebo group) to the subjects originally randomized to placebo (continuous-placebo group) on all primary and secondary outcome measures at week 72 (after controlling for Study 1 baseline/week 0 values). All subjects will terminate trial product at cumulative week 72 and will return to clinic for a final safety visit at week 76. Outcome assessments including ad libitum energy intake, subjective measures of appetite, food reward, eating behavior, mood, and eating disorder symptoms will occur at weeks 0, 20, 40, and 60 of Study 1 and at week 12 (72 weeks from original randomization) of the re-randomized treatment period. Measurements of body weight, waist circumference, blood pressure, pulse, and global, past-week appetite and food cravings (COEQ) also will be collected every 4 weeks throughout both treatment studies.