Weekly Somatrogon Treatment Aids in Pediatric Growth Hormone Deficiency

Cheri L. Deal, MD, PhD, FRCPC

An effective human growth hormone (hGH) administered weekly could treat pediatric growth hormone deficiency (GHD), while reducing the necessary injections needed.

A team, led by Cheri L. Deal, MD, PhD, FRCPC, University of Montreal, examined whether a weekly dose of somatrogon could be more beneficial to patients with pediatric growth hormone deficiency than daily doses of genotropin.

Deal explained in a presentation for the ENDO Online 2020 virtual conference the early results show somatrogon is a viable treatment option, reducing the need for daily injections.

“Weekly somatrogon administration gave a robust, sustained, and statistically non-inferior increase in height velocity compared to daily growth hormone treatment,” Deal said.

Somatrogon is a long-acting recombinant human growth hormone containing amino acid sequences of hGH and 3 copies of the carboxyterminal peptide (CTP) derived from human chorionic gonadotropin.

In a 12-month phase 2 trial, investigators found once weekly somatrogon compared to daily genotropin in children with GHD demonstrated that 0.66 mg/kg/weekly of the drug had a similar benefit-risk profile as 0.24 mg/kg/weekly of genotropin.

In an open-label extension of the study, the investigators produced an additional 5 years of longitudinal efficacy and safety data with the selected dosage.

In a phase 3 global trial, investigators examined the non-inferiority of once weekly somatrogon hGH-CTP compared to daily hGH for 12 months in treatment-naive prepubertal children with GHD.

The trial included 224 patients who were randomized to receive the study drug once weekly (0.66 mg/kg) or once daily genotropin (0.24 mg/kg/week) for 12 months.

The investigators stratified the randomization by geographic region, peak GH level, and age.

The team sought primary endpoints of the height velocity at month 12 and secondary endpoints of health velocity at month 6, changes in height standard deviation score (SDS) at month 6 and 12, IGF-1 and IGF-1 SDS, immunogenicity, and safety.

At baseline, the mean age and height of SDS of the study drug arm (n = 109, 75.2% male) and genotropin (n = 115, 68.7% male) groups were 7.83 (2.66) and -2.94 (1.29) and 7.61 (2.37) and 2.78 (1.27), respectively.

Only 1 participant in each arm of the trial discontinued treatment, with 95% of the participants entering the open-label extension study. At the end of the trial, the mean height velocity was 10.12 cm per year in the study drug group and 9.78 cm per year in the genotropin group.

The lower bound of the two-sided 95% confidence interval of the treatment difference was -0.39, which was higher than the pre-established non-inferiority margin and demonstrated non-inferiority of once weekly somatrogon compared to daily genotropin therapy.

In addition, height velocity at month 6 (10.60 cm/year vs. 10.04 cm/year), change in height SDS at months 6 (0.54 vs 0.48) and 12 (0.92 vs 0.87 were higher in the somatrogon-treated cohort.

While the investigators did identify adverse events, the majority were mild-to-moderate in severity (somatrogon: 78.9%, genotropin: 79.1%).

Overall, weekly somatogenic was well-tolerated and comparable to the daily doses of genotropin.

“Top-line results from the pivotal phase 3 trial demonstrate that Somatrogon (hGH-CTP) given once weekly by sc injection is non-inferior to Genotropin (hGH) given once daily and that once weekly somatrogon administration was generally well-tolerated in patients with pGHD,” the authors wrote.

The study, “OR10-06 Somatrogon Growth Hormone in the Treatment of Pediatric Growth Hormone Deficiency: Results of the Pivotal Pediatric Phase 3 Clinical Trial,” was published online in the Journal of Endocrine Society.