Clinically-Relevant Weight Loss is Achieved Independently of Early Weight Loss Response to Once-Weekly Subcutaneous Semaglutide 2.4 MG (STEP 4)

Background: Semaglutide, a glucagon-like peptide-1 analogue, is being investigated in people with overweight or obesity. A post-hoc analysis of the STEP 4 trial was conducted to identify whether early weight loss is predictive of later weight loss with maintenance once-weekly subcutaneous (s.c.) semaglutide 2.4 mg. Methods: STEP 4 was a randomized, double-blind, phase 3 withdrawal trial (NCT03548987). Adults aged ≥18 years with either body mass index (BMI) ≥27 kg/m2 with ≥1 weight-related comorbidity or BMI ≥30 kg/m2, without type 2 diabetes, underwent a 20-week run-in period. Participants reaching the maintenance dose of once-weekly s.c. semaglutide 2.4 mg at week 20 (regardless of weight loss achieved) were randomized 2:1 to semaglutide 2.4 mg or placebo, as adjunct to lifestyle intervention, for an additional 48 weeks. Percent change in body weight from week 0 to 68 was estimated using a mixed model for repeated measurements analysis with treatment, week 20 responder status, and the interaction between treatment and week 20 responder status as factors, and baseline body weight as a covariate, all nested within visit (based on the trial product estimand [treatment effect assuming treatment adherence and without use of rescue intervention] for the on-treatment period). Participants were considered responders if they achieved ≥5% weight loss at week 20. Whether the week 20 response to semaglutide predicted the achievement of clinically-relevant weight loss (≥5%) by week 68 was also assessed. Results: In STEP 4, 902 participants initiated semaglutide at week 0, of whom 803 were randomized at week 20 (semaglutide: n=535, placebo: n=268; characteristics at week 0 for all randomized participants: mean age 46 years, body weight 107.2 kg, BMI 38.4 kg/m2; 79.0% female; 83.7% white). For the 88.0% of participants randomized to semaglutide and who were responders at week 20, mean body weight change from week 0 to 68 was -19.7%. For non-responders at week 20, mean body weight change was -6.4% with continued semaglutide vs -0.3% with switch to placebo. Of all participants randomized to semaglutide, 86.2% achieved a clinically-relevant weight loss (≥5%) at week 68. Being a responder at week 20 was highly predictive of achieving this outcome (positive predictive value: 96.4%), whereas being a non-responder at week 20 had limited predictive value (negative predictive value: 42.9%). Conclusion: In the STEP 4 trial, the vast majority of participants who were randomized to the maintenance dose of once-weekly s.c. semaglutide 2.4 mg at week 20 had lost ≥5% body weight by week 68, with most achieving this by week 20. Overall weight loss with semaglutide was greater among early responders, but non-responders also achieved a clinically-relevant weight loss by week 68 if semaglutide treatment was continued.