Semaglutide is a GLP1-RA that was previously approved for treatment of T2DM at a 1.0 mg weekly s.c. dose and approved for chronic weight management at a 2.4mg weekly s.c. dose on June 4, 2021. Four double-blind, randomized placebo-controlled trials that tested semaglutide 2.4mg SQ once weekly for obesity treatment have recently been published.
In the STEP-1 trial, among 1961 adults with overweight plus comorbid conditions or obesity, those randomized to receive semaglutide lost 15.3kg (14.9% of initial weight), which was 12.7kg (12.4%) more weight loss than those randomized to receive placebo. The percent of participants with ≥5%, ≥10%, ≥15%, and ≥20% weight losses with semaglutide were 86.4%, 69.1.8%, 50.5%, and 32.0, much higher than with placebo (31.5%, 12.0%, 4.9%, and 1.7% respectively).
The STEP-2 trial of weight management in 1210 participants with type 2 diabetes (who typically lose less weight than those without diabetes) found those randomized to receive semaglutide 2.4mg lost 9.7kg (9.6%), which was 6.1kg (6.2%) more weight loss than those randomized to placebo. 25.8% of semaglutide-treated (versus 3.2% of placebo-treated) participants lost ≥15% of their body weight.
STEP-3 assessed the additional contribution of semaglutide to intensive behavioral treatment in 611 adults with overweight/obesity. Participants in the semaglutide group lost 16.8kg (16.0%), which was 10.6kg (10.3%) more weight loss than participants in the placebo group, with 55.8% of semaglutide-treated (versus 13.2% of placebo-treated) participants losing ≥15%. Importantly, the retention rates in the semaglutide studies were much higher than in most anti-obesity medication trials, with >90% of participants having a body weight assessment at week 68 and/or attending the week 75 final study visit, providing confidence in the validity of the findings.
The STEP-4 trial of 803 adults without diabetes, which examined the effect of continued semaglutide 2.4mg for 68 weeks vs. switch to placebo at 20 weeks, found an additional 7.9% weight loss among those who continued drug treatment, compared with a weight gain of +6.9% among those switched to placebo, for a final placebo-subtracted weight loss of 14.8%. This study confirmed the necessity of continued anti-obesity pharmacotherapy for sustained benefit. Adverse events with semaglutide were primarily gastrointestinal, and similar to other GLP1-RA. An increased incidence of gallbladder-related disorders was observed, as is typical whenever large, rapid weight losses are induced. Reductions in cardiovascular risk factors, including systolic blood pressure, lipids, and glycated hemoglobin, also were observed. Semaglutide 2.4mg is now being tested in a large multisite cardiovascular outcomes trial (CVOT) in participants without diabetes but at high CVD risk (ClinicalTrials.gov Identifier: NCT03574597).
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I’ve removed the reference numbers from that because it was confusing and put in some paragraphs. If you want to read the paper (2021) I took it from, it’s here:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8277731/