Recombinant Human Growth Hormone, Testosterone Improves Ambulation, Disease Burden in Facioscapulohumeral Muscular Dystrophy

Using daily recombinant human growth hormone (rHGH) combined with testosterone injections every 2 weeks, findings from a single-center study showed that patients with facioscapulohumeral muscular dystrophy (FSHD) experienced improvements in ambulation, strength, muscle mass, and disease burden. Investigators concluded that placebo-controlled trials are needed to investigate and confirm the benefit of this therapeutic approach.

Known as STARFISH (NCT03123913), the study featured 20 men with FSHD who received daily rHGH of Genotropin and testosterone for 24 weeks with a 12-week washout period. Individuals were between 18 and 65 years old, had a genetically confirmed diagnosis, had hematocrit of less than 50%, were able to walk continuously for 6 minutes, and had prostate-specific antigen of less than 4.0 ng/ml. Those with diabetes, obesity, cardiovascular disease, untreated thyroid disease, and deep vein thrombosis, among other exclusions, were not permitted.

Led by Chad R. Heatwole, MD, MS, director, Center for Health and Technology, University of Rochester, all but 1 participant completed the study, with no individuals experiencing a serious adverse event (AE). Soreness at the rHGH/testosterone injection site, occurring in 6 participants, was the most common AE in the trial. Travel distance and the COVID-19 pandemic were the reasons for the 1 individual drop out.

FSHD, a progressive muscular dystrophy, occurs in 4 of every 100,000 people globally, with no approved therapies to treat. Around 20% of these individuals will need a wheelchair by age 50, and over 70% experience debilitating pain and fatigue. After 24 weeks of treatment, patients saw increases in 6-minute walk distance by 37.3 meters (P = .0007) and lean body mass improvements of 2.2 kg (P <.0001). Furthermore, treatment resulted in body fat reduced by 1.3 kg (P = .04), and overall strength, as measured by standardized QMT, increased by 3% (P = .03). FSHD-Health Index, a commonly used measure to assess total disease burden, was reduced by 19% (6 points; P = .04) in comparison with baseline.

Genotropin has been indicated in Canada for the treatment of children who have growth failure due to an inadequate secretion of endogenous growth hormone and growth failure in short children born small for gestational age and who fail to achieve catch-up growth by 2 to 4 years or late. Additionally, it is indicated for short stature associated with Turner syndrome in patients who epiphyses are not closed, idiopathic short stature, and adults with growth hormone deficiency of adult- or childhood-onset. The recommended dose of Genotropin in adults is 0.15 mg to 0.3 mg per day up to a maximum of 1.33 mg per day.

Although this was the first study to observe rHGH in FSHD, this approach has been tested in other neuromuscular conditions, including a case-study of a patient with calpainopathy, a common type of autosomal recessive limb-girdle muscular dystrophy, in 2017. In that analysis, the patient was treated with daily injections of somatropine, an rHGH, except for a 6-month pause, over a period of 4.5 years. Using repeated muscle dynamometry tests and 6-minut walk tests, strength improved in most muscle groups on treatment, deteriorated in the 6-month off treatment, and improved again when treatment was resumed.