Efficacy and Safety of up to 2 Years of Treatment With TransCon hGH (Lonapegsomatropin) in Treatment-Naïve and Treatment-Experienced Children With Growth Hormone Deficiency

Efficacy and Safety of Somapacitan Relative to Somatrogon and Lonapegsomatropin in Pediatric Growth Hormone Deficiency: Systematic Literature Review and Network Meta-analysis

INTRODUCTION

Since direct comparisons of long-acting growth hormones (LAGHs) are lacking, analyses were performed to indirectly compare the efficacy and safety of somapacitan versus somatrogon and lonapegsomatropin in children with growth hormone deficiency (GHD).

METHODS

A systematic literature review (SLR) identified studies of once-weekly LAGHs for the treatment of pediatric GHD. Indirect comparisons (ICs) using a Bayesian hierarchical network meta-analysis and a random effects model were performed using daily growth hormone (GH) 0.034 mg/kg/day (base case) or 0.024-0.034 mg/kg/day (alternative analyses) as the common comparator to compare height outcomes to 52 weeks [annualized height velocity, height velocity standard deviation score (SDS), and height SDS]. Identified evidence did not allow IC of safety or longer-term efficacy outcomes so these were qualitatively described.

RESULTS

The SLR identified two somapacitan trials, three somatrogon trials (one included in alternative analyses only), and one lonapegsomatropin trial comparing the LAGH with daily GH in treatment-naïve pre-pubertal children for IC. ICs revealed no differences at 52 weeks between somapacitan versus somatrogon and lonapegsomatropin, as well as daily GH, with respect to all growth outcomes considered in children with GHD. All three LAGHs had sustained efficacy and were generally well tolerated, with comparable efficacy and safety to daily GH, with the exception of observed injection site pain for somatrogon.

CONCLUSION

No efficacy and safety differences were identified in comparisons of once weekly somapacitan versus somatrogon and lonapegsomatropin, as well as daily GH. All treatments were generally well tolerated, with the exception of observed injection site pain for somatrogon.

Spotlight on Lonapegsomatropin Once-Weekly Injection and Its Potential in the Treatment of Growth Hormone Deficiency in Pediatric Patients

Lonapegsomatropin, a long-acting GH therapy (LAGH), was approved by the United States Food and Drug Administration in August 2021 for the treatment of pediatric growth hormone deficiency (GHD). Lonapegsomatropin is a prodrug consisting of unmodified GH transiently conjugated to methoxypolyethylene glycol which enables time-release of GH with a half-life of ~25 hours allowing for once-weekly administration. Clinical trials of lonapegsomatropin have demonstrated positive efficacy results in children (phase 2 and 3) and adults (phase 2) with GHD. The phase 3 trial in children with GHD established non-inferiority and statistical superiority of height velocity with lonapegsomatropin (11.2 cm/yr) compared to daily GH (10.3 cm/yr), with no concerning side effects with lonapegsomatropin. Similar growth responses have been reported in other LAGH products in phase 2 (somapacitan) and phase 3 (somatrogon) trials. Lonapegsomatropin is distributed in temperature-stable, prefilled cartridges at 9 different doses that can be prescribed based upon specific weight brackets designed to deliver approximately 0.24 mg/kg/wk. An electronic delivery device is required to combine the powdered medication with the diluent and deliver the medication subcutaneously through a small gauge needle to the recipient. The pharmacodynamic data from the clinical trials of lonapegsomatropin has been used to develop models to estimate an average IGF-1 value drawn at any time during the weekly injection interval. This average IGF-1 value may be used to for safety monitoring and/or to guide dose adjustment. New LAGH products, including lonapegsomatropin, may potentially improve patient adherence, quality of life and clinical outcomes, particularly in patients with poor adherence to daily GH injections in the future. With the availability of new LAGH products, clinicians will need to identify the best candidates for LAGH therapy and understand how to monitor and adjust therapy. Long-term surveillance studies are needed to demonstrate adherence, efficacy, cost-effectiveness and safety of LAGH preparations.

Lonapegsomatropin: Pediatric First Approval

Lonapegsomatropin (lonapegsomatropin-tcgd; SKYTROFA^®), a long-acting prodrug of somatropin (human growth hormone), is in development by Ascendis Pharma as a treatment for growth hormone deficiency in pediatric and adult patients. Lonapegsomatropin received its first approval in August 2021 in the USA for the treatment of pediatric patients at least 1 year of age (and weighing ≥ 11.5 kg) with growth failure due to inadequate secretion of endogenous growth hormone. Lonapegsomatropin is administered as a once-weekly subcutaneous injection; the sustained release of somatropin from lonapegsomatropin eliminates the need for daily somatropin injections. This article summarizes the milestones in the development of lonapegsomatropin leading to this first pediatric approval for the treatment of growth hormone deficiency.