Novo Nordisk: semaglutide clears obesity threshold in 40% of children
Novo Nordisk has reported positive topline results from the STEP Young phase 3 trial, showing that once-weekly subcutaneous semaglutide, combined with lifestyle modification, produced significant BMI reductions in children aged 6 to under 12 years living with obesity.
The trial met its primary endpoint of superior BMI reduction at week 68 compared with placebo, with both arms receiving a reduced-calorie diet and increased physical activity throughout. The headline finding is that 40.4% of children in the semaglutide group were reclassified below the CDC obesity threshold by the end of the 68-week period, compared with none in the placebo group. More than 85% of the 165 enrolled children had class II or III severe obesity at baseline, making the magnitude of response clinically notable.
Trial design and data
The STEP Young study was a randomised, double-blind, placebo-controlled multinational trial. Children received a maximum dose of either 1.7 mg or 2.4 mg of semaglutide weekly, determined by their weight at enrolment. The 40.4% figure is based on a treatment-product estimand, meaning it reflects the estimated effect under full adherence. Supportive secondary endpoints covering cardiovascular risk factors, glucose metabolism, anthropometric measures, and body composition via DXA scanning are also being evaluated at weeks 68 and 104, though those detailed results were not released in the topline announcement.
Ania M. Jastreboff, Professor of Medicine at Yale and director of the Yale Obesity Research Center, noted that most participants entered the trial with severe obesity, yet roughly two in five reached a BMI percentile below the obesity cut-off within approximately one year of treatment. Full data will be presented at ObesityWeek 2026, held 14 to 17 November in Washington DC.
The company reported that the safety and tolerability profile observed in STEP Young was consistent with findings from prior semaglutide and liraglutide trials in adults and adolescents, with no new safety signals identified. Importantly, no concerns relating to growth or pubertal development were flagged, a question that will attract close scrutiny from paediatric endocrinologists and regulators alike.
Market context and regulatory path
The paediatric obesity treatment landscape has historically been sparse. Eli Lilly's tirzepatide has generated considerable attention in adults and adolescents, and several GLP-1-based programmes are now exploring younger age groups, intensifying competition for the pre-adolescent segment. Novo Nordisk already holds approvals for semaglutide 2.4 mg (Wegovy) in adults and in adolescents aged 12 and over in major markets; extending that label to younger children would open a new commercial avenue at a time when global prevalence data show an estimated 177 million children aged 5 to 19 living with obesity in 2025, a figure the World Obesity Federation projects will reach 228 million by 2040.
The STEP Young programme was conducted under regulatory post-marketing requirements for the semaglutide phase 3 development plan, suggesting Novo Nordisk is building a structured evidence base to support a future label extension. The EMA and FDA will each require their own review processes, and the absence of a namedregulatory submission timeline in this announcement means a paediatric label in the 6-to-11 age group remains a medium-term rather than near-term prospect. Investors will look for the full dataset from ObesityWeek and any subsequent regulatory meeting disclosures as the clearest signals on timing.