medwireNews: The long-acting TransCon growth hormone (GH) has shown comparable efficacy and safety to standard daily somatropin in children with GH deficiency (GHD) in a phase II trial.

TransCon GH consists of GH transiently bound to methoxypolyethylene glycol by a proprietary linker, allowing the active drug to be released over the course of 7 days, say Pierre Chatelain (Université Claude Bernard Lyon 1, France) and study co-authors.

In their trial, maximum GH levels occurred between 12 and 24 hours after injection, before slowly returning to baseline, “without significant accumulation”, for all three doses used – 0.14, 0.21 and 0.30 mg/kg per week.

The 53 participating GHD patients were around 8 years old and had peak GH levels below 10 ng/ml on stimulation and a height standard deviation score (SDS) of around –3.0. During 26 weeks of treatment, the 13 patients taking daily somatropin achieved an annualised height velocity of 11.6 cm, and the 14 taking the nearest equivalent TransCon GH dose of 0.21 mg/kg per week achieved 12.9 cm/year.

The 26 patients taking the 0.14 and 0.30 mg/kg per week doses achieved annualised height velocities of 11.9 and 13.9 cm, respectively. There were no significant differences between the groups.

Safety of TransCon GH was similar to that of daily somatropin, with adverse events being mild or moderate and mostly unrelated to treatment. No patients developed neutralising anti-GH antibodies, and the one instance of non-neutralising antibodies did not appear to affect treatment; this patient’s annualised growth velocity was 19.0 cm, which was above the median for their dose (0.14 mg/kg per week).

Seven patients taking TransCon GH recorded an insulin-like growth factor-1 SDS above 2.0 at some point in the trial, with one patient on the highest dose having an SDS above 3.0. But all of these increases were transient and none required GH dose modification.

“It is well established that the simpler a regimen, the more likely a patient will adhere to it”, write the researchers in The Journal of Clinical Endocrinology & Metabolism.

They add: “Given that TransCon GH is administered weekly—a more acceptable frequency for children and adolescents with GHD—it stands to reason that when six injections in a week are eliminated and dosing follows an easy-to-remember schedule, compliance may improve and optimal adult height is more likely to be achieved.”

The team therefore believes that their findings support advancing TransCon GH to phase III study.

By Eleanor McDermid

J Clin Endocrinol Metab 2017; Advance online publication

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