Efficacy Study of Epoetin Alfa in Friedreich Ataxia

Overview

Friedreich's ataxia (FRDA) is a rare genetic disorder characterised by severe neurological disability and cardiomyopathy. Friedreich's ataxia is the consequence of frataxin deficiency. Although several drugs have been proposed, there is no available treatment. Four trials recently demonstrated that erythropoietin can increase the intracellular levels of frataxin. The present project is aimed at testing a long term therapeutic approach using erythropoietin, which is an already available and commercialised drug. The study will test the effect of erythropoietin on exercise capacity, which is reduced in patients with FRDA. Additional objectives of the study will be the drug's safety and tolerability, and its effect on frataxin, blood vessel reactivity, heart functional indexes, and disease progression.

Friedreich's ataxia (FA) is an autosomal recessive ataxia caused by a trinucleotide GAA expansion in the first intron of the FXN gene. The gene encodes for a 210aa mitochondrial protein called frataxin, whose mRNA and protein levels are severely reduced in FA. It has been suggested that frataxin is involved in iron-sulphur cluster and heme biogenesis, iron binding/storage, and chaperone activity. Clinically, the age of onset is generally around puberty and, as the disease progresses, there is increasing ataxia of the limbs, and eventually most patients are wheelchair bound by the twenties. Cardiomyopathy with myocardial hypertrophy occurs very often and is the predominant cause of death. Type II diabetes, scoliosis, foot deformities, optic atrophy, and deafness are other relatively frequent symptoms. Erythropoietin (EPO) is a glycoprotein that acts as a main regulator for erythropoiesis. Evidence suggests that both EPO and its receptor are expressed in the nervous tissue, and neuroprotective effects have been shown in animal models of cerebral ischemic damage. EPO increases frataxin levels in cultured human lymphocytes from FRDA patients. However, frataxin protein increase is not preceded by mRNA increase, suggesting that a post-transcriptional mechanism is involved. To date, four phase II clinical trials have been published regarding the use of EPO in FRDA patients.