MON-245 Outcomes Of Phentermine-topiramate In Youth Living With Duchenne Muscular Dystrophy

Abstract Disclosure: L. Chen: None. P.S. Zeitler: None. Background: Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disorder primarily affecting males that is often associated with obesity due to low energy expenditure and treatment with high-dose corticosteroids. Obesity has a serious impact on quality of life in individuals with DMD and is consistently among the top concerns of families. Yet the evidence-base for weight management tailored to this population remains limited. With the recent approvals of weight-loss medications in the adolescent age group, there has been interest among individuals with DMD and their families for trials. Phentermine/topiramate (PHEN/TPM), a combination FDA-approved for weight management in adolescents, offers potential benefits but concerns have been raised about side effects specific to DMD, such as the impact of stimulant medication on cardiac status. Objective: We report the clinical outcomes of PHEN/TPM therapy for individuals with DMD at Children's Hospital Colorado (CHCO). Methods: Individuals with a genetic diagnosis of DMD who were prescribed phentermine and/or topiramate from January 1, 2015, to April 25, 2025 were identified from the electronic medical record system. A final cohort of 6 individuals treated for at least 6 months and having clinic-obtained weights documented was identified for analysis. Results: All patients were male, aged 9.9 - 16.9 years, with baseline weight 45 -108.2 kg and BMI 29.5 - 39.7 kg/m². Treatment duration ranged from 0.6 to 4.2 years. In the first year after treatment, the mean changes in BMI, BMI SD, and weight SD were -4.67 kg/m2 (95% CI: -9.24 to -0.11), -0.68 (95% CI: -1.21 to -0.15), and -0.90 (95% CI: -1.77 to -0.02), respectively. For the treatment course, annual changes in BMI, BMI SD, and weight SD were -2.35 kg/m2 (95% CI: -6.71 to 2.01), -0.39 (95% CI: -0.86 to 0.07), and -0.55 (95% CI: -1.5 to 0.4), respectively. A statistically significant increase in heart rate (HR) was noted at 0.5 yr treatment duration (+11 bpm, 95% CI: 0.5 to 21.5, p = 0.0425), but there was no significant longitudinal trend for either HR (+0.66 bpm/year, 95% CI: -1.75 to 3.37, p = 0.598; between-patient SD = 11.18 bpm) or left ventricular ejection fraction (LVEF) (+0.29%/year, 95% CI: -0.66 to 1.22, p = 0.533; between-patient SD = 5.31%) was noted. Two patients developed kidney stones; one of them discontinued topiramate after 4.2 years. No unexpected or DMD specific adverse events were reported. Conclusions: Treatment with PHEN/TPM in patients with DMD was associated with clinically relevant reductions in BMI SD and weight SD and was generally well tolerated. Two individuals developed kidney stones, a known risk with topiramate, and risk factors need to be better understood. There were no significant changes in HR or LVEF during treatment in this small group of individuals. Presentation: Monday, July 14, 2025