SAT-091 First Report of Disease-Specific Patient-Reported Outcomes from a Randomized Phase 2 Trial of Once-Weekly Somapacitan vs Daily GH in Children with GHD

Somapacitan is a long-acting, reversible albumin-binding growth hormone (GH) derivative being developed for once-weekly dosing in adults and children with GH deficiency (GHD). The efficacy, safety and tolerability of somapacitan were compared with daily GH in children with GHD in a multicenter, randomized, controlled, double-blinded to dose, phase 2 trial (REAL 3, NCT02616562). Treatment-naïve, prepubertal children with GHD were randomized 1:1:1:1 to once-weekly sc somapacitan (0.04, 0.08 or 0.16 mg/kg/week [wk]) or daily sc GH (Norditropin®; 0.034 mg/kg/day) during the 26-wk main trial period and 26-wk extension. Efficacy of the 0.16 mg/kg/wk dose was similar to that of daily GH, judged by height standard deviation scores (SDS) and insulin-like growth factor-I SDS, and, at wk 52, height velocity was statistically significantly greater with somapacitan 0.16 mg/kg/wk vs daily GH. Safety and tolerability of somapacitan were consistent with the profile of daily GH. Here, we report the results of a pre-planned analysis of patient-reported outcomes (PROs) collected during REAL 3. This is, to our knowledge, the first report of a disease-specific PRO score from a randomized trial in GHD. PROs were investigated using the Growth Hormone Deficiency - Child Impact Measure observer-report (GHD-CIM ObsRO). This is a new, validated questionnaire, developed according to US FDA guidance, to assess the impact of GHD on physical functioning, and social and emotional wellbeing in children aged 4 to <13 years, to be completed by caregivers. Minimal important differences (MID) in scores were determined based on Patient and Clinician Global Impression of Severity. Changes from baseline to wk 52 in GHD-CIM ObsRO scores were compared between daily GH and each dose of somapacitan, and were analyzed using an analysis of covariance model. A total of 59 patients were randomized (somapacitan n=45; daily GH n=14); the full analysis set included 57 children (somapacitan: 0.04 mg/kg/wk n=14; 0.08 mg/kg/wk n=15; 0.16 mg/kg/wk n=14; daily GH n=14). Mean age was 5.9 years; 60% were male; 11 children were <4 years old at baseline. For the change from baseline in GHD-CIM ObsRO score, the estimated treatment differences (ETDs) between somapacitan 0.16 mg/kg/wk and daily GH at wk 52 exceeded the MID in favor of somapacitan for the emotional wellbeing (ETD -9.34; MID 7) and social wellbeing domains (ETD -10.12; MID 5), as well as total score (ETD -7.43; MID 5). The somapacitan 0.16 mg/kg/wk group showed a numerical improvement over daily GH across all GHD-CIM ObsRO domains and total score, although none of the ETDs reached statistical significance. At 52 wks, the difference in GHD-CIM ObsRO scores between somapacitan 0.16 mg/kg/wk and daily GH exceeded the MID for the total score, and for the emotional and social wellbeing domains, suggesting clinically relevant improvement for these parameters in favor of somapacitan in children with GHD.