Weekly somapacitan efficacy matches daily rhGH over 3 years in GHD

medwireNews: The 3-year findings of the REAL 3 trial show that weekly somapacitan continued to deliver equivalent height gains and safety results to that achieved with standard daily recombinant human growth hormone (rhGH) treatment in children with growth hormone deficiency (GHD).

“Somapacitan may provide an alternative to daily GH treatment in children with GHD, with a reduced treatment burden as a result of fewer injections than daily GH”, write the researchers in The Journal of Clinical Endocrinology & Metabolism.

The 57 children who participated in REAL 3 were randomly assigned to receive the long-acting rhGH somapacitan at a weekly dose of 0.04, 0.08 or 0.16 mg/kg, or daily rhGH. At baseline, the average age across the four groups ranged from 5.8 to 6.1 years and height standard deviation score (SDS) ranged from –4.1 to –3.4.

After 1 year of treatment, all children taking somapacitan continued on the 0.16 mg/kg dose for a further 2 years; 53 children completed the full 3 years of the trial.

The average height velocity for children taking somapacitan (all dose groups pooled) was 9.9 and 8.3 cm/year at years 2 and 3, respectively, and for daily rhGH it was 9.0 and 7.6 cm/year.

There were no significant differences in height velocity between weekly and daily treatment. Children who took the highest somapacitan dose for the full duration of the trial achieved a height velocity that was a nonsignificant 0.8 cm/year greater than that achieved with daily treatment at year 3.

By year 3, height SDS had improved by 2.5 with somapacitan and by 2.1 with daily rhGH, to give a year 3 height SDS of –1.4 in both groups.

During the first year of the trial, participants taking somapacitan had dose-dependent increases in insulin-like growth factor (IGF)-I. After those on lower doses switched to 0.16 mg/kg, the average IGF-I SDS was similar in the somapacitan and daily rhGH groups after 3 years of treatment, at 1.22 and 1.30, respectively.

“Importantly, at year 3, mean IGF-I SDS remained within the normal range across all treatment arms”, say Lars Sävendahl (Karolinska University Hospital, Solna, Sweden) and study co-authors.

They note, however, that IGF-I levels remain fairly constant in children taking daily rhGH, whereas in those taking weekly rhGH, they increased during the first few days after the injection, before declining to a low level just before the next dose.

“The reported IGF-I SDS value therefore depends on the time of sampling, as the maximum levels are higher, and the trough values are lower with long-acting GH than those with daily GH”, the team explain.

But they stress that IDF-I SDS was measured near its maximum level in the somapacitan groups, and “should be taken into consideration when comparing the level of somapacitan- and daily GH-induced IGF-I SDS at these time points.”

The ratio of bone age to chronological age increased from 0.57 to 0.87 in the pooled somapacitan groups and from 0.56 to 0.69 in the daily rhGH group.

Adverse events were mostly mild and unrelated to treatment, and occurred at similar rates in the somapacitan and daily rhGH groups. Injection site reactions were the predominant events considered probably related to treatment.

By Eleanor McDermid

medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2022 Springer Healthcare Ltd, part of the Springer Nature Group

J Clin Endocrinol Metab 2021; doi:10.1210/clinem/dgab928
Martin Savage
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