Auspex Pharmaceuticals, a privately held biopharmaceutical company, has enrolled its first patient in a multi-centre phase III pivotal trial of its lead investigational drug, SD-809 for the treatment of involuntary movements (chorea) associated with Huntington's disease (HD). The top-line data from the trial, designated the First-HD study, are expected in 2014.

"SD-809 is a deuterated form of tetrabenazine with pharmacokinetic properties that allow for more consistent blood levels and less frequent dosing. This may lead to improved medication compliance and patient outcomes," said David A Stamler, MD, Auspex chief medical officer. "We are enthusiastic to be conducting this study in partnership with the Huntington Study Group, an international network of experienced clinical trial investigators at leading academic centres that care for HD patients and families."

First-HD, or "First time use of SD-809 in HD", is a randomized, double-blind, placebo-controlled study that will test the efficacy, safety and tolerability of SD-809 in the management of chorea symptoms in 90 HD patients who have not previously taken tetrabenazine. The primary endpoint for the study will be Total Maximal Chorea (TMC) score. Secondary endpoints will include treatment success measurements based on patient and clinical global impressions of change. Participants will be involved in this trial for approximately four months. In parallel with First-HD, Auspex will be conducting an open-label study of SD-809 in experienced tetrabenazine users and subjects who complete First-HD (Alternatives for Reducing Chorea in HD or ARC-HD Trial).

Principal Investigators for the First-HD study are Dr Samuel Frank at Boston University School of Medicine, and Dr Claudia Testa at Virginia Commonwealth University.

SD-809 is a novel investigational drug in phase III pivotal trials for the treatment of chorea associated with Huntington's disease. SD-809 inhibits vesicular monoamine transporter Type 2 (VMAT-2), decreasing the amount of dopamine available to work at nerve terminals, and thereby reducing involuntary movements. In early clinical studies, SD-809 has shown an improved pharmacokinetic (PK) profile compared to tetrabenazine, the only FDA-approved treatment. This improved PK results in more consistent blood levels of drug and may enable once or twice daily dosing of SD-809 compared with tetrabenazine, which is usually given three times per day.

The Huntington Study Group (HSG) is an independent not-for-profit network of more than 200 clinical investigators, coordinators, and scientists from 100 participating universities and clinics in the United States, Canada, Europe, Australia, New Zealand and South America who provide comprehensive care for Huntington disease (HD) patients and families and carry out multi-center clinical research including observational studies and controlled clinical trials. The mission of the HSG is to relieve the burden of illness and develop treatments that make a difference for HD patients and families.

Auspex Pharmaceuticals is a leader in the use of deuterium in medicinal chemistry, and is focused on the potential treatment of hyperkinetic movement disorders including Huntington's disease, Tourette syndrome and tardive dyskinesia.