STEP TEENS reports 16.1 percent BMI reduction in adolescents

Results from the STEP TEENS trial show that once-weekly semaglutide 2.4 mg cut body mass index by an average of 16.1 percent over 68 weeks in adolescents with obesity, while BMI rose 0.6 percent in the placebo group ^[1]. The findings were first presented at ObesityWeek 2022 in November ^[1].

STEP TEENS was a double-blind, parallel-group, randomized, placebo-controlled trial that enrolled 201 adolescents with obesity ^[1]. Participants received either subcutaneous semaglutide 2.4 mg once weekly or placebo for 68 weeks ^[1]. Everyone in the trial — including the placebo group — also received behavioral lifestyle therapy focused on a healthy diet and exercise ^[1].

The primary endpoint was the mean percentage change in BMI at week 68. Semaglutide beat placebo on that measure, with a 16.1 percent decrease compared with a 0.6 percent increase ^[1]. A supportive secondary endpoint looked at how many participants hit a meaningful threshold: 77 percent of those on semaglutide had a BMI reduction of 5 percent or more, compared with 20 percent on placebo ^[1].

BMI, rather than pounds lost, is the standard yardstick in pediatric obesity trials because children and teens are still growing, and BMI is interpreted against age- and sex-based percentiles.

From trial data to a label change

Novo Nordisk, which makes semaglutide and sells it for weight management under the brand name Wegovy, later announced that the U.S. Food and Drug Administration had approved an expanded indication based on the STEP TEENS results ^[1]. That made semaglutide the first injectable anti-obesity prescription medication cleared for use in pediatric patients ^[1].

The expanded label covers adolescents 12 years and older with an initial BMI at or above the 95th percentile for their age and sex ^[1]. As with adults, the label directs that it be used alongside a reduced-calorie meal plan and increased physical activity ^[1].

Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist that was first approved by the FDA to treat diabetes and, later, obesity or overweight in adults ^[1]. One clinician quoted after the approval described how it works: "The drug works by making people feel full sooner and suppressing the appetite so people do not feel as hungry. One of the ways it does this is by slowing emptying of the stomach so there is a feeling of satiety," said Ibiye Owei, MD, of Texas Tech University Health Sciences Center ^[1].

Detailed safety and side-effect results from STEP TEENS, including rates of nausea, vomiting or study dropouts, have not been reported here. Whether teens keep the BMI reduction after stopping the drug also has not been addressed in the trial results described.

Why it matters for patients

An estimated 1 in 5 U.S. adolescents between ages 12 and 19 have obesity ^[1]. Until this label change, families looking for medical treatment beyond diet and exercise had fewer prescription options, and the most effective intervention for many teens was bariatric surgery.

The size of the BMI change reported in STEP TEENS is in the range clinicians describe as substantial. "It is one of the most effective treatments available for either condition, outside of bariatric surgery," said Kathleen Dungan, MD, an endocrinologist at The Ohio State University Wexner Medical Center, who added that there is evidence semaglutide "may reduce the risk for developing diabetes and may be particularly useful in individuals who have prediabetes" ^[1].

The approval also frames adolescent obesity as a long-term medical condition rather than a matter of effort. Experts quoted after the decision described it as a "serious, chronic, progressive disease" shaped by genetics as well as socioeconomic and environmental factors, and one that requires long-term management to head off problems such as high blood pressure, high cholesterol and type 2 diabetes ^[1]. Aaron S. Kelly, PhD, co-director of the Center for Pediatric Obesity Medicine at the University of Minnesota, said the approval "offers an additional tool to address this serious, chronic, progressive disease" ^[1].

Practical questions that families face — insurance coverage for teens, cost, and how long treatment continues — were not addressed in the trial results or the approval announcement.