Weekly therapy safe, comparable to daily injections in pediatric GH deficiency
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Children with growth hormone deficiency assigned long-acting recombinant GH therapy experienced an increase in height velocity similar to children assigned daily injections, study data show.
Somatrogon (Opko Health and Pfizer) is a long-acting recombinant human GH in development for once-weekly treatment of children with GH deficiency, Cheri Deal, PhD, MD, FRCPC, chief of endocrinology and diabetes and full professor at Sainte-Justine Mother-Child University of Montreal Hospital, said during a presentation at ENDO Online.
Somatrogon contains the amino acid sequence of human GH and three copies of the carboxy-terminal peptide derived from human chorionic gonadotropin, which extends the half-life of the drug and supports weekly administration, she said.
In a 12 month, phase 2 trial comparing weekly somatrogon with daily somatropin, researchers found that the two therapies had a similar risk-benefit profile, Deal said.
“We know that daily injections of somatropin has a well-established safety and efficacy profile in children with GH deficiency,” Deal said. “Thus, this somatrogon phase 3 study was designed as a noninferiority study of weekly somatrogon vs. daily somatropin in subjects with pediatric GH deficiency.”
Deal and colleagues analyzed data from 224 prepubertal children with GH deficiency and naive to GH therapy randomly assigned once-weekly somatrogon (0.66 mg/kg; n = 109; mean age, 8 years; 75.2% boys) or once-daily somatropin (0.24 mg/kg; n = 115; mean age, 8 years; 68.7% boys) for 12 months. Children were stratified by geographic region, peak GH level and age. Mean height standard deviation score (SDS) was –2.94 for the somatrogon group and –2.78 for the somatropin group. Primary endpoint was height velocity at month 12; secondary endpoints were height velocity at month 6, change in height SDS at months 6 and 12, insulin-like growth factor I and IGF-I SDS, immunogenicity and safety.
At month 12, mean height velocity was 10.12 cm per year for children in the somatrogon group and 9.78 cm per year for children in the somatropin group, with the treatment difference of 0.33 cm per year favoring somatrogon, Deal said.
“The lower bound of the two-sided 95% confidence interval of this treatment difference was –0.33, well above the preestablished noninferiority margin ... and confirmed the robust response that we all see in naive, GH-deficient patients,” Deal said.
Mean height velocity at month 6 was greater for children in the somatrogon group (mean, 10.60 cm/year vs. 10.04 cm/year), as was change in height SDS at month 6 (mean, 0.54 vs. 0.48) and at month 12 (mean, 0.92 vs. 0.87).
Most adverse events were mild to moderate in severity, Deal said, adding that somatrogon was generally well-tolerated and comparable to daily somatropin. Glucose metabolism remained stable and within the normal range, Deal said.
“Weekly somatrogon administration gave a robust, sustained and statistically noninferior increase in height velocity compared with daily GH treatment, while raising and maintaining IGF-1 within the normal range,” Deal said.
As Healio previously reported, Pfizer and Opko entered into a worldwide agreement in 2014 for the development and commercialization of somatrogon for the treatment of GH deficiency. Under the agreement, Opko is responsible for conducting the clinical program and Pfizer is responsible for registering and commercializing the product.
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Deal CL, et al. Somatrogon growth hormone in the treatment of pediatric growth hormone feficiency: results of the pivotal pediatric phase 3 clinical trial. ENDO Online; June 8-19, 2020.
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