Pfizer, OPKO One Step Closer to Approval of Pediatric Growth Hormone Deficiency Drug

Pfizer and OPKO Health are one step closer to receiving approval for their jointly developed pediatric growth hormone deficiency (GHD) drug, somatrogon, after the U.S. FDA recently accepted the companies’ regulatory submission for the therapy.

The FDA accepted for filing the initial Biologics License Application for the long-acting human growth hormone, which has been studied and will potentially be indicated for the treatment of children with GHD. The target action data for an FDA decision is October 2021.

“The FDA’s filing acceptance is an encouraging step closer to our goal of providing a long-acting, once-weekly therapy for pediatric patients living with GHD,” according to a statement made by Brenda Cooperstone, M.D., the Chief Development Officer of Rare Disease at Pfizer Global Product Development. “If approved, somatrogon could help reduce the burden of daily growth hormone injections on children, their loved ones, and caregivers.”

Investigational new biologic product somatrogon comprises the amino acid sequence of human growth hormone coupled with a copy of the C-terminal peptide derived from the beta chain of human chorionic gonadotropin located at the N-terminus as well as two copies of C-terminal peptide located at the C-terminus. Pfizer and OPKO entered into a collaboration deal on the development and commercialization of somatrogon for GHD in 2014.

Positive data from a global Phase III trial is supporting the submission from Pfizer and OPKO Health. In the study, pediatric patients with GHD were treated with once-weekly somatrogon to identify safety and efficacy signals of the drug. The study met the primary endpoint of non-inferiority compared with somatropin (GENOTROPIN®) as assessed by the annual height velocity at 1 year. Somatropin has been available for decades, but daily injections of this treatment, as assessed in the Phase III trial, can lead to lack of compliance.

Top-line findings from this late-stage trial showed that the least square mean was significantly higher in patients treated with somatrogon versus those treated with somatropin (10.12 vs 9.78 cm/year, respectively; treatment difference=0.33; 95% CI -0.39-1.05). Also, researchers of the study noted that treatment with once-weekly somatrogon was associated with higher changes in height standard deviation scores at 6 and 12 months compared with treatment with once-daily somatropin.

An additional key secondary endpoint in the trial – change in height velocity at 6 months – was also higher in the once-weekly somatrogon group compared with the once-daily somatropin cohort. In addition, once-weekly treatment with somatrogon in the study was generally well tolerated and comparable to once-daily somatropin, specifically in regard to the types, numbers and severity of adverse events.

“For 35 years, Pfizer has been committed to improving the outcomes of patients living with GHD,” added Dr. Cooperstone, “and somatrogon is another example of how we are working to positively impact quality of life and treatment compliance to help ensure those patients can reach their full potential.”