Somatropin improves growth outcomes in children with ISS

Daily use of somatropin, a recombinant human growth hormone (rhGH), led to significantly improved growth outcomes, particularly height standard deviation scores (HT-SDSs), in prepubertal children with idiopathic short stature (ISS), according to a recent study.

“Greater improvement in HT-SDS was observed [with somatropin treatment, wherein], … the mean HT-SDS of subjects who received somatropin reached normal range (≥-2.25) after a year of treatment, indicating that GH treatment has a positive impact on growth,” said the researchers.

The researchers conducted a multicentre, open-label, phase III trial involving 481 children with ISS (mean age 5.8 years, mean height 106.0 cm, mean weight 17.0 kg) at 11 clinical sites in China. Participants were randomized in a 3:1 ratio to receive subcutaneous injections of somatropin 0.05 mg/kg/day (treatment group; n=362) or no treatment (control group; n=119) for 52 weeks. [Front Endocrinol (Lausanne) 2022;doi:10.3389/fendo.2022.864908]

At baseline, HT-SDSs were comparable between the treatment and control groups at -2.64 and -2.67, respectively.

By week 52, subjects who received somatropin had a statistically significant improvement in HT-SDS than those in the control group (mean change from baseline, 1.04 vs 0.20; p<0.001; least squares mean [LSM] difference, 0.85), which indicates the superiority of somatropin treatment over no treatment.

When the analysis was further stratified by age, subjects aged ≤7 years treated with somatropin demonstrated a greater increase in HT-SDS compared with those aged >7 years (1.08 vs 0.85). “[This result suggests] that starting GH treatment earlier may yield better growth outcomes,” the researchers noted.

Somatropin-treated subjects also showed a statistically significant increase in height compared with the control group at 52 weeks (mean change from baseline, 10.19 vs 5.85 cm; p<0.001; LSM difference, 4.27).

There was also a significant increase in BA/CA* ratio, height velocity (HV), and IGF-1 SDS** among those treated with somatropin vs the control group (mean change from baseline, 0.040 vs 0.004, 5.17 vs 0.75 cm/year, and 2.31 vs 0.22, respectively).

Additionally, an increase in predicted adult height (PAH) was observed in the somatropin group vs the control group (mean change from baseline, 6.28 vs 1.55 cm), particularly in younger vs older children (6.67 vs 4.50 cm).

The most commonly reported treatment-emergent adverse events (AEs) were upper respiratory tract infection (66.0 percent), fever (19.6 percent), and cough (10.8 percent) in the somatropin group. AEs occurred in 23 subjects in the somatropin group, but all were considered mild or moderate in severity and no deaths were reported.

“[Overall,] daily somatropin at a dose of 0.05 mg/kg/day demonstrated superiority to no treatment in terms of gain in HT-SDS, [particularly in children aged ≤7 years,] and HV increment, [as well as] a significant increase in height gain, PAH, and IGF-SDS after 52 weeks of treatment in prepubertal children with ISS,” said the researchers.

“Somatropin was well tolerated with a favourable safety profile,” they added.

*BA/CA: Bone age for chronological age

**IGF-1 SDS: Insulin-like growth factor-1 standard deviation score