Lonapegsomatropin once-weekly vs. daily Somatropin doses investigated in prepubertal Turner Syndrome

Turner Syndrome (TS) is a genetic disorder affecting females, characterized by the absence or partial absence of one X chromosome. A primary clinical manifestation is short stature, often necessitating growth hormone (GH) therapy. Current standard-of-care involves daily subcutaneous injections of recombinant human somatropin, which can lead to significant treatment burden and adherence issues. Long-acting growth hormone formulations, such as lonapegsomatropin, aim to reduce injection frequency, potentially improving patient compliance and overall treatment outcomes in individuals with growth hormone deficiency.

This open-label, dose-finding trial will randomize approximately 48 prepubertal individuals with Turner Syndrome into four arms. Participants will receive either one of three different doses of once-weekly lonapegsomatropin or a daily injection of somatropin. The study duration is 104 weeks, followed by an optional 78-week open-label extension. The primary objective is to investigate the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of lonapegsomatropin, comparing its efficacy and safety profile against the established daily somatropin regimen to determine optimal dosing.

This trial description outlines the planned investigation rather than reporting completed findings. The study is designed to assess the comparative performance of once-weekly lonapegsomatropin across three distinct dose levels against a daily somatropin regimen in prepubertal individuals with Turner Syndrome. The primary focus will be on evaluating safety and tolerability profiles for each treatment arm over 104 weeks. Secondary objectives include characterizing the pharmacokinetics and pharmacodynamics of lonapegsomatropin, which are crucial for understanding drug exposure and biological response. The trial aims to identify a lonapegsomatropin dose that provides comparable efficacy to daily somatropin, potentially measured by growth velocity and IGF-1 levels, while offering the convenience of once-weekly administration. This structured dose-finding approach is anticipated to provide critical data for future therapeutic strategies.

The trial will randomize approximately 48 individuals (with 12 individuals per arm) to investigate three doses of lonapegsomatropin or daily somatropin over 104 weeks.