Two-year real-world experience with somatrogon in children and adolescents with growth hormone deficiency.

Introduction: Growth hormone deficiency (GHD) in children and adolescents is a chronic condition requiring long-term therapy with recombinant human growth hormone (rhGH). Daily injections pose adherence challenges, prompting the development of long-acting GH (LAGH) formulations, such as once-weekly somatrogon. While phase III trials have demonstrated its efficacy, real-world data are limited. Methods: This retrospective study evaluated all pediatric patients with GHD who initiated somatrogon between March 2023 and January 2025 at a tertiary endocrine center in Italy and completed at least 6 months of treatment. Results: Forty patients (50% naïve; 50% switched from daily rhGH) were included. At 6 months, height SDS increased significantly in both naïve (Δ +0.19) and switch patients (Δ +0.17), with no significant difference between groups. However, by 18 and 24 months, naïve patients showed significantly greater height gains, with a median cumulative Δ of +0.81 at 18 months. IGF-1 SDS increased significantly only in the naïve group. Median gain in height SDS at 12 months in naïve patients (+0.37) was lower than reported in registration trials, likely reflecting the broader clinical heterogeneity of real-world populations. Treatment was well tolerated, with no discontinuations and few mild adverse events. Several families reported improved adherence and quality of life. Conclusions: In this first real-world cohort, somatrogon was safe and effective in supporting linear growth, although height gains were lower than in clinical trials. Weekly administration may offer practical benefits, especially for patients with complex needs or poor adherence to daily injections.