Somapacitan in Children Born SGA: 52-week Efficacy, Safety, and IGF-I Response Results from the Phase 2 REAL5 Study

Abstract Context Somapacitan, a once-weekly reversible albumin-binding growth hormone (GH) derivative, is evaluated in short children born small for gestational age (SGA). Objective Evaluate efficacy, safety, tolerability as well as total and bioactive insulin-like growth factor I (IGF-I) response of once-weekly somapacitan compared to daily GH in children born SGA. Methods REAL5 is a randomized, multicenter, open-label, controlled phase 2 study comprising a 26-week main phase, a 26-week extension, and an ongoing 4-year safety extension (NCT03878446), conducted at 38 sites across 12 countries. A total of 62 GH-treatment-naïve, prepubertal short children born SGA were randomized; 61 completed 52-weeks of treatment. Patients were randomized (1:1:1:1:1) to somapacitan (0.16, 0.20, or 0.24 mg/kg/week) or daily GH (0.035 or 0.067 mg/kg/day), all administered subcutaneously. Results Estimated mean height velocity (HV; cm/year) at week 52 was 8.5, 10.4, and 10.7 cm/year for somapacitan 0.16, 0.20, and 0.24 mg/kg/week, respectively, and 9.3 and 11.2 cm/year for daily GH 0.035 and 0.067 mg/kg/day, respectively. Dose-dependent increases in total IGF-I, as well as peak IGF-I bioactivity, were observed for both treatments and were similar between comparator groups. For somapacitan, exposure-response modeling indicated highest efficacy with 0.24 mg/kg/week after 52 weeks of treatment. Similar safety and tolerability were demonstrated across all groups. Conclusion A sustained dose-dependent growth response was demonstrated for somapacitan after 52 weeks of treatment. Overall, somapacitan 0.24 mg/kg/week provides similar efficacy, safety, and tolerability, as well as comparable bioactive and total IGF-I response, as daily GH (0.067 mg/kg/day) in children born SGA.