Weekly somatrogon vs daily somatropin: a propensity score-matched analysis of growth outcomes from clinical data vs KIGS

Objectives: Somatrogon is a long-acting growth hormone utilized for treatment of pediatric patients with growth hormone deficiency (GHD). This matched cohort analysis compared the first 3 years of height outcomes for somatrogon-treated patients from a Phase 3 somatrogon study (NCT02968004) with historical data from somatropin-treated patients in the Kabi/Pfizer International Growth Study (KIGS). Methods: In the somatrogon study, patients with GHD were randomized to once-weekly somatrogon (0.66 mg/kg/week) or once-daily somatropin (0.24 mg/kg/week) for 12 months, followed by an open-label extension, during which all patients received somatrogon (0.66 mg/kg/week or lower dose as per protocol). Patients in the somatrogon study (somatrogon cohort) were matched with patients with GHD from KIGS (KIGS cohort) who had received somatropin (0.20-0.30 mg/kg/week), using propensity score matching according to baseline characteristics of geographic region, gender, age, peak GH, and height standard deviation score (HtSDS) (ie, peak GH and HtSDS at study entry). Results: 155 patients in the somatrogon study were matched to 155 somatropin-treated patients from KIGS. The somatrogon and KIGS cohorts had similar mean annualized height velocity through Years (Y) 1 to 3 of treatment (Y1: 10.03 vs 9.57; Y2: 7.70 vs 7.33; Y3: 7.15 vs 6.56). Mean changes in HtSDS (from baseline) through Y1-3 were comparable between both cohorts, though the somatrogon cohort appeared to have larger changes in Y2-3. Conclusion: Somatrogon-treated patients in the Phase 3 study had similar height outcomes compared with matched somatropin-treated patients in KIGS, strengthening the expectation that once-weekly somatrogon will have comparable efficacy to somatropin in real-world treatment of pediatric patients with GHD.