Somatrogon©, a long-acting human growth hormone (hGH) molecule, is a once-weekly injectable, created using recombinant technology, for the treatment of pediatric and adult growth hormone deficiency (GHD). The molecule consists of the natural peptide sequence of native growth hormone and the 28 amino acids of the C-Terminus Peptide (CTP) of the human chorionic gonadotropin hormone. This molecule, as compared to current GH replacement therapies, is intended to reduce the injection frequency from a daily to once a week in adults and children with GHD.
Adult growth hormone deficiency (AGHD) afflicts approximately 50,000 people in the U.S. There are two main causes: damage or trauma to the pituitary or hypothalamus gland, and being born with a growth hormone deficiency (GHD). Whereas growth hormone (GH) is principally used to assist growth in children, GH is necessary for GHD patients to maintain muscle, bone and fat tissues in a healthy balance and quality of life. With this deficiency, fat is deposited more easily around the middle of the abdomen; there's a decrease in muscle; bones become weaker resulting in osteoporosis; and cholesterol levels become higher, with a decrease in the "good" HDL cholesterol. hGH is also used in adults with AIDS-induced weight loss. Currently, approved recombinant growth hormone products require daily injections.
Pediatric GHD, or pGHD, is defined as growth failure associated with inadequate GH production. Approximately 80% of the more than $3 billion market for hGH therapy is for pGHD. Current standard of care treatment of pGHD patients is using once daily subcutaneous injections of recombinant hGH.
In October 2019, OPKO completed a pivotal Phase 3 clinical trial of Somatrogon© as a treatment for pGHD patients. Top-line results from the study demonstrated that treatment with Somatrogon©, dosed once-weekly in pre-pubertal children with GHD, was non-inferior to somatropin dosed once-daily with respect to height velocity at 12 months of treatment (the primary endpoint); the least square mean was higher in the Somatrogon© group (10.12 cm/year) than in the somatropin group (9.78 cm/year); the treatment difference (Somatrogon© – somatropin) in height velocity (cm/year) was 0.33 with a two-sided 95% confidence interval of the difference of (-0.39, 1.05). In addition, change in height standard deviation scores at six and 12 months, key secondary endpoints, were higher in the Somatrogon© dosed once-weekly cohort in comparison to the somatropin dosed once-daily cohort. Moreover, at six months, change in height velocity, another key secondary endpoint, was higher in the Somatrogon© dosed once-weekly cohort in comparison to the somatropin dosed once-daily cohort. These common measures of growth are employed in the clinical setting to measure the potential level of catch-up growth that subjects may experience relative to heights of age and gender matched peers. The enrollment of this Phase 3 global study was completed in August 2018, enrolling and dosing 224 patients in 21 countries. In addition, a Phase 3 product registration clinical study in Japanese pGHD patients has been initiated and completed enrollment in February 2019. This study is designed to evaluate the comparability of once weekly doses of Somatrogon© to once daily doses of Genotropin.