ESPE Abstracts

Objectives: Somatrogon is a long-acting recombinant human growth hormone (GH) approved by the EMA as a once weekly treatment for children with pediatric GH deficiency (GHD). A global phase 3 study compared the efficacy and safety of once-weekly somatrogon with once-daily Genotropin in pediatric subjects with GHD. The objective of this subgroup analysis was to evaluate the efficacy and safety of once-weekly somatrogon vs once-daily Genotropin in the subset of Asian subjects.

Methods: This open-label phase 3 study enrolled 224 subjects who were randomized 1:1 to receive either once-weekly somatrogon (0.66 mg/kg/week) or once-daily Genotropin (0.24 mg/kg/week) for 12 months. Randomization was stratified by geographic region, peak GH level, and age. The primary endpoint of the study was height velocity (HV) at month 12; secondary endpoints included HV at month 6, change in height SDS at months 6 and 12, IGF-1, IGF-I SDS, and bone maturation. This subgroup analysis focused on 45 Asian subjects from Australia, Great Britain, India, New Zealand, South Korea, Spain, Taiwan and the United States of America.

Results: Within this subgroup of Asian subjects, both treatment groups (somatrogon:n=24; Genotropin:n=21) had similar demographic and baseline characteristics. The least squares mean HV at month 12 was 10.94 cm/year in the somatrogon group and 9.56 cm/year in the Genotropin group with missing data imputed; the treatment difference of 1.38 cm/year favored somatrogon. The lower bound of the two-sided 95% confidence interval of the treatment difference (somatrogon–Genotropin) was −0.14 for this subgroup, similar to that for the overall study population (−0.24), for which the efficacy of once-weekly somatrogon was demonstrated to be non-inferior to once-daily Genotropin. The observed HV at month 6 was higher in the somatrogon group than in the Genotropin group (11.23 vs 8.31 cm/year). The somatrogon group also showed greater improvement in height SDS and IGF-1 SDS from baseline at months 6 and 12, compared with the Genotropin group. Both treatment groups had a similar proportion of subjects with adverse events (somatrogon: 83.3%; Genotropin: 76.2%) and serious adverse events were recorded for one and two subjects in the somatrogon and Genotropin groups, respectively.

Conclusions: The efficacy and safety results from this analysis of Asian subjects in the global study are consistent with those from the overall study population, in which non-inferiority of once-weekly somatrogon to once-daily Genotropin was demonstrated. Clinicaltrials.gov:NCT02968004