Study of the Efficacy and Safety of Nicotinamide in Patients With Friedreich Ataxia

Friedreich ataxia is the most frequent early-onset autosomal recessive hereditary ataxia. It is caused by a pathological expansion of a GAA repeat in the first intron of the frataxin gene (FXN) and results in decreased levels of FXN protein. FXN deficiency results in a relentlessly progressive neurodegenerative condition which frequently presents around puberty. Patients gradually lose coordination, become dysarthric and are frequently wheel-chair bound as adolescents. There is no disease modifying therapy and many patients die prematurely of cardiomyopathy. It was subsequently found that the FXN gene is silenced at the chromatin level by the formation of heterochromatin and that this heterochromatin formation can be antagonized by histone deacetylase inhibitors (HDACi) (Chan et al., 2013). A recent proof-of-concept clinical study on ten patients with Friedreich ataxia demonstrated that FXN levels can be restored to those seen in asymptomatic carriers using the class III HDACi nicotinamide at a dose that is well tolerated by patients (Libri et al., 2014). Since carriers are asymptomatic, this degree of restoration of FXN expression might be expected to halt disease progression. Nicotinamide readily crosses the blood brain barrier and has previously been given at high doses for long periods to normal individuals without serious adverse effects (Gale et al., 2004; Knip et al., 2000). This study will be the first to provide clinical evidence for the efficacy and safety of nicotinamide in patients with Friedreich´s ataxia.