Long-term Safety and Efficacy of Once-Weekly Lonapegsomatropin in Adults With Growth Hormone Deficiency: Results From a 52-Week Open-Label Extension Trial.

OBJECTIVE: To evaluate long-term safety and efficacy of once-weekly lonapegsomatropin in adults with growth hormone (GH) deficiency. METHODS: This 52-week, multicenter, open-label extension trial enrolled adults with GH deficiency who completed the 38-week phase 3 foresiGHt trial, in which participants received lonapegsomatropin, placebo, or somatropin.1 In the extension, all participants received lonapegsomatropin. Safety assessment included adverse events (AEs), laboratory values, vital signs, immunogenicity, 12-lead electrocardiograms, and fundoscopy. Body composition (trunk percent fat, trunk fat mass, visceral adipose tissue, total body lean mass, trunk lean mass, and appendicular lean mass) was measured by dual-energy X-ray absorptiometry, and patient-reported outcomes were evaluated. RESULTS: Following foresiGHt completion, 220 (88.7%) participants enrolled in the extension. Across foresiGHt and the extension, common lonapegsomatropin-associated AEs were nasopharyngitis, upper respiratory infection, and headache. Injection site reactions were infrequent (5.1%) and mild or moderate. After up to 90 weeks of treatment, body composition was maintained in participants continuing lonapegsomatropin, and improved relative to foresiGHt baseline in those initiating or switching to lonapegsomatropin. Clinically meaningful improvements in patient-reported outcomes from foresiGHt baseline were observed; 43.5%, 40.6%, and 35.8% of participants achieving a ≥10-point improvement in Treatment Related Impact Measure-Adult GH Deficiency (TRIM-AGHD) total score among those continuing, initiating, or switching to lonapegsomatropin, respectively. CONCLUSIONS: Once-weekly lonapegsomatropin was generally well tolerated and was associated with sustained improvements in body composition and patient-reported outcomes for up to 90 weeks. These findings extend prior evidence and support the long-term benefits of lonapegsomatropin in adults with GH deficiency, including those switching from somatropin.