Bezafibrate as treatment in males for Barth syndrome: CARDIOMAN, a double-blind, placebo-controlled crossover RCT

Abstract

Background: Barth syndrome is a rare, life-threatening X-linked recessive mitochondrial disorder of lipid metabolism primarily affecting males. Previous research suggests that bezafibrate may ameliorate cellular lipid abnormalities and reduce cardiac dysfunction in an animal model.

Objectives: Estimate the effect of bezafibrate on clinical, biochemical, and quality-of-life outcomes.

Investigate whether within-participant clinical changes parallel in vitro changes in cardiolipin ratio/profile and mitochondrial morphology when each participant’s cells are cultured with bezafibrate.

Investigate as for objective 2, culturing each participant’s cells with resveratrol.

Describe the most feasible methods and standardised outcome measures to optimise the conduct of future trials and evaluations in Barth syndrome.

Describe features of the research infrastructure which optimised recruitment, retention and communication with families and people with Barth syndrome.

Describe the perceptions of participants and their families about the research and any important potential barriers to participation.

Design: Randomised, placebo-controlled, crossover trial of bezafibrate versus placebo.

Setting: NHS hospital providing UK-wide Barth Syndrome Service.

Participants: Males aged ≥ 6 years with a confirmed diagnosis of Barth syndrome with stable cardiac status, able to swallow tablets of bezafibrate/placebo. Exclusions were: hypersensitivity or allergy to bezafibrate or any component of bezafibrate; hepatic, liver or renal dysfunction; gallbladder disease; or recent deterioration in general health.

Interventions: Fifteen weeks of bezafibrate in one period and placebo in a second period, or vice versa (randomly allocated), with at least a 1-month washout between periods.

Main outcome measures: The primary outcome was peak VO2; secondary outcomes were cardiac function rest and exercise echocardiography and magnetic resonance imaging, cardiolipin ratio, quality of life, dynamic skeletal muscle P-magnetic resonance spectroscopy, mitochondrial studies and neutrophil counts, and adverse events. Outcomes were measured at baseline and the end of each period.

Results: Eleven males were studied; all attended all three assessments. There was no difference in peak VO2 between periods (0.66 ml/kg/min lower with bezafibrate than placebo, 95% confidence interval 2.34 to 1.03; p = 0.43). There was a trend towards a higher left ventricular ejection fraction with bezafibrate when measured by echocardiography but not magnetic resonance imaging, and better echocardiography-derived rest longitudinal and circumferential strain with bezafibrate. There was no difference in quality of life or cardiolipin ratio between periods. Skeletal muscle 31P magnetic resonance spectroscopy was performed cross-sectionally and showed a trend to higher Tau and lower Qmax indices in the bazafibrate group. Two participants had serious, expected adverse reactions when taking bezafibrate; otherwise, bezafibrate was well tolerated.

Limitations: The sample size was very small; the bezafibrate dose may have been too low or 15 weeks too short to observe an effect; measurements of mitochondrial content and membrane potential were highly variable; P-magnetic resonance spectroscopy was available only at the final assessment.

Conclusions: This study did not show significant improvement in the primary and secondary outcomes with bezafibrate treatment.

Future work: Elamipretide, studied in a small crossover trial in the USA, is another potential intervention which may be worth evaluating in an international study.