Clinical outcomes of switching to lonapegsomatropin from somatropin for treatment of pediatric growth hormone deficiency

Abstract Objectives This study aimed to assess differences in insulin-like growth factor 1 (IGF-1) levels following the transition from somatropin to lonapegsomatropin in patients with pediatric growth hormone deficiency (GHD). Secondary objectives included the evaluation of dose titrations based on IGF-1 levels, changes in annualized height velocity (AHV) and body mass index (BMI), and assessing reported adverse effects associated with lonapegsomatropin therapy. Methods A single-center, retrospective review was conducted including patients diagnosed with pediatric GHD initially treated with somatropin who transitioned to lonapegsomatropin between January 1, 2022, and December 31, 2023. Results Fourteen patients (median age: 9 years) were included. The median somatropin dose was 0.18 mg/kg/week (range, 0.09 to 0.29) at the time of transition and patients were initiated on a median lonapegsomatropin dose of 0.23 mg/kg/week (range, 0.15 to 0.26). This resulted in an IGF-1 increase of 2.3 SDS post-switch. Dose adjustments were made based on IGF-1 levels. Five patients required immediate dose reductions; four of these required further adjustments due to persistent elevation. There were no serious adverse effects reported. Conclusions Lonapegsomatropin may be a favorable option to reduce injection burden for those with pediatric GHD, though the manufacturer’s recommended starting dose of 0.24 mg/kg/week may require individualization. Careful monitoring and dose adjustment based on IGF-1 levels are necessary to maintain safety and efficacy.