Pfizer and OPKO Health announced positive topline results from a phase 3 study evaluating somatrogon once-weekly injection in children aged 3 to 17 years with growth hormone deficiency (GHD).

Somatrogon is a new molecular entity with an extended half-life that allows for once-weekly administration. The investigational agent contains the natural sequence of growth hormone and 1 copy of the C-terminal peptide from the beta chain of human chorionic hCG at the N-terminus and 2 copies at the C-terminus.

The 24-week multicenter, open-label, crossover C0311002 study compared the patient perception of treatment burden with use of somatrogon to somatropin (Genotropin®; Pfizer) in 87 children aged 3 to 17 years with GHD. Patients were randomized to receive subcutaneous injections of somatrogon once-weekly followed by somatropin once-daily, or vice versa. The primary end point was treatment burden, assessed as the difference in mean overall Life Interference total scores between weekly and daily injection schedules.

Findings showed that somatrogon improved treatment burden with a mean overall Life Interference total score of 8.63 after 12 weeks vs 24.13 for somatropin. Somatrogon demonstrated a favorable treatment difference of -15.49 (95% CI, -19.71, -11.27; P <.0001) at the nominal 0.05 level. Moreover, there was an overall benefit in treatment experience (key secondary end points) observed with somatrogon once-weekly compared with somatropin once-daily.

As for safety, the incidence of treatment-emergent adverse events was comparable between somatrogon and somatropin, and mild to moderate in severity. There were no serious adverse events reported, and 1 patient discontinued somatrogon due to a nonserious treatment-emergent adverse event. 

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“We’re encouraged by findings to date that demonstrate once-weekly somatrogon, if approved, has the potential to reduce lifestyle interference, support patient preference, and improve adherence as compared to a daily treatment,” said Brenda Cooperstone, MD, Chief Development Officer, Rare Disease, Pfizer Global Product Development.

Results from a global phase 3 trial involving 224 pre-pubertal, treatment-naive children with GHD found somatrogon to be noninferior to somatropin, as measured by annual height velocity at 12 months.

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Pfizer announces positive phase 3 top-line results for once-weekly investigational long-acting human growth hormone to treat children with growth hormone deficiency. [press release]. New York, NY and Miami, FL: Pfizer; October 8, 2020.