Study of Testosterone and Recombinant Human Growth Hormone in Facioscapulohumeral Muscular Dystrophy

Effective therapies for facioscapulohumeral muscular dystrophy (FSHD) are currently limited. Recombinant human growth hormone (rHGH) combined with testosterone (combination therapy) may have meaningful clinical effects on ambulation, strength, muscle mass, and disease burden. As such, combination therapy has the potential to limit disease progression and functional decline in individuals with muscular dystrophy. The objective of this study was to evaluate the safety, tolerability, and potential efficacy of combination therapy in adult men with FSHD.

This investigator-initiated, single-center (University of Rochester), single-arm, proof-of-concept study evaluated the safety and tolerability of combination therapy in ambulatory adult men with FSHD. Participants received daily rHGH combined with testosterone enanthate injections every 2 weeks for 24 weeks, followed by a 12-week washout period. Participants underwent serial safety and laboratory assessments to monitor safety and tolerability during the study. Participants were also evaluated for changes from baseline in lean body mass (LBM) and fat mass, measured by dual-energy X-ray absorptiometry; ambulation, measured by 6-minute walk distance; strength; clinical function, measured using the FSHD-Composite Outcome Measure (FSHD-COM); and patient-reported disease burden, measured by the FSHD Health Index (FSHD-HI).

Nineteen of 20 participants completed the study, with no participants experiencing a serious adverse event. The most common adverse event was mild injection site reaction at the rHGH and/or testosterone injection site. After 24 weeks, LBM improved by 2.21 kilograms (95% CI 1.35-3.07; p < 0.0001), fat mass decreased by 1.30 kilograms (95% CI -2.56 to -0.04; p = 0.04), 6-minute walk distance increased by 37.3 m (95% CI 18.3-56.9; p = 0.001), overall strength (average % of predicted normal) increased by 3% (95% CI 0.3-5.6; p = 0.03), clinical function (FSHD-COM) improved by 2.4 points (95% CI 4.0-0.8; p = 0.006), and total disease burden (FSHD-HI) decreased by 6.1 points (95% CI -12.0 to -0.2; p = 0.04).

Combination therapy was safe and well tolerated in men with FSHD. Participants experienced improvements in ambulation, strength, muscle mass, and disease burden after receiving this study intervention. Larger randomized, double-blind, placebo-controlled trials are needed to further investigate this promising therapeutic approach.

Registered on ClinicalTrials.gov: NCT03123913.