The common first-line treatment for children with growth hormone deficiency (GHD) is daily injection of somatropin (recombinant human GH). Daily injections represent a high treatment burden, which may lead to poor adherence and suboptimal overall treatment outcomes.

Lonapegsomatropin has been developed as a long-acting, once-weekly prodrug for the treatment of GHD. In a randomized, active-controlled phase III heiGHt trial, investigators evaluated the efficacy and safety of once-weekly lonapegsomatropin versus daily somatropin among 161 treatment-naïve, prepubertal patients with GHD. Patients were enrolled from 73 sites across 15 countries. The study findings were published in The Journal of Clinical Endocrinology & Metabolism by Paul S. Thornton and colleagues.

Study participants were randomized 2:1 to receive either lonapegsomatropin 0.24 mg hGH/kg per week (n=105), or an equivalent weekly dose of somatropin delivered daily (n=56).

The primary endpoint was annualized height velocity (AHV) at week 52. Secondary efficacy endpoints included change from baseline in height standard deviation scores (SDS).

At 52-week follow-up, the least square (LS) mean AHV with lonapegsomatropin was 11.2 cm/year versus 10.3 cm/year with daily somatropin (p = 0.009). The researchers noted that lonapegsomatropin demonstrated both noninferiority and superiority over daily somatropin. Patients treated with lonapegsomatropin also experienced increases in LS mean height SDS from baseline to week 52 (1.10 versus 0.96; p = 0.01).

The authors reported that bone age/chronological age ratio, adverse events, tolerability, and immunogenicity were similar between groups.

“The trial met its primary objective of noninferiority in AHV and further showed superiority of lonapegsomatropin compared to daily somatropin, with similar safety, in treatment-naïve children with GHD,” the authors concluded. However, the study is potentially limited by its open-label design, which may introduce bias.