RF26 | PMON335 Once-Weekly Somapacitan Versus Daily Growth Hormone in Children Born Small for Gestational Age: Results From a Randomized Phase 2 Trial

Treatment of persistent short stature in children born small for gestational age (SGA) requires daily growth hormone (GH) injections that can be burdensome for patients and caregivers. Once-weekly somapacitan is a long-acting GH currently in phase 3 development for replacement therapy in children with GH deficiency. We report the 26-week results of the first phase 2, multinational, randomized, open-label, controlled, dose-finding trial (NCT03878446) investigating the efficacy and safety of somapacitan as treatment for short stature in children born SGA compared with daily GH (Norditropin®, Novo Nordisk A/S). A total of 62 (35.5% female) GH-treatment-naïve, prepubertal children received 0.16, 0.20 or 0.24 mg/kg/week subcutaneous (s.c.) somapacitan, or 0.035 or 0.067 mg/kg/day s.c. daily GH for 26 weeks (main phase). All children are subsequently included in an extension to this trial. The primary outcome was annualized height velocity (HV). At week 26, the estimated mean HV was: 8.9, 11.0 and 11.3 cm/year for 0.16 mg/kg/week (n=12), 0.20 mg/kg/week (n=13) and 0.24 mg/kg/week (n=12) somapacitan, respectively, versus 10.3 and 11.9 cm/year for 0.035 mg/kg/day (n=12) and 0.067 mg/kg/day (n=13) daily GH, respectively. A dose-dependent response in the estimated mean HV was observed with both somapacitan and daily GH. The effect of somapacitan on HV was not statistically significantly different compared with daily GH. A similar pattern was observed for change from baseline in height standard deviation score (SDS) and change from baseline in HV SDS. Consistent dose-dependent increases were observed in insulin-like growth factor-I (IGF-I) SDS with both somapacitan and daily GH. Exposure-response modeling of somapacitan exposure versus HV and IGF-I SDS vs. HV indicated an exposure-dependent increase in HV for both these parameters. Somapacitan was well tolerated at all doses investigated, with no safety or local tolerability issues identified. There were no clinically relevant findings with respect to glucose metabolism, and no detection of anti-drug antibodies in any of the dose groups. In conclusion, all investigated doses of weekly somapacitan were efficacious and well tolerated throughout the study period. Based on the totality of data on improvements in height-based parameters combined with exposure-response analyses, a somapacitan dose of 0.24 mg/kg/week appears as the most efficacious dose, providing similar efficacy, safety and tolerability to daily GH 0.067 mg/kg/day after 26 weeks of treatment. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m., Monday, June 13, 2022 12:51 p.m. - 12:56 p.m.