Post hoc subgroup analysis of Asian children with paediatric GHD from the global phase 3 efficacy and safety study of once-weekly somatrogon vs. once-daily somatropin.

Objectives: Somatrogon is a long-acting recombinant human growth hormone used to treat patients with paediatric growth hormone deficiency (pGHD). This global phase 3 study compared the efficacy and safety of once-weekly somatrogon with once-daily somatropin in children with GHD.

Methods: Prepubertal patients were randomized 1:1 to once-weekly somatrogon (0.66 mg/kg/week) or once-daily somatropin (0.24 mg/kg/week) for 12 months. The primary endpoint was height velocity (HV) at month 12; secondary endpoints included HV at month 6 and change in height standard deviation score (SDS) at months 6 and 12 and insulin-like growth factor 1 (IGF-1) SDS.

Results: This post hoc subgroup analysis focused specifically on Asian children (somatrogon: n=24 and mean age=7.76 years; somatropin: n=21 and mean age=8.10 years) across eight countries. Mean HV at month 12 was 10.95 cm/year (somatrogon) and 9.58 cm/year (somatropin); the treatment difference of 1.38 cm/year favoured somatrogon. The lower bound of the two-sided 95 % CI of the treatment difference (somatrogon-somatropin) was -0.20, similar to the overall study population (-0.24). Compared with the somatropin group, the somatrogon group had numerically higher HV at month 6 (8.31 vs. 11.23 cm/year); a similar trend was observed for height SDS and IGF-1 SDS at months 6 and 12. Safety and tolerability were similar between treatment groups; adverse events occurred in 83 % of somatrogon-treated children and 76 % of somatropin-treated children.

Conclusions: This subgroup analysis demonstrated that somatrogon efficacy and safety in Asian children were consistent with the overall study population, where once-weekly somatrogon was non-inferior to once-daily somatropin. Clinicaltrials.gov: NCT02968004.