Rare Disease Report

SD-809 (Austedo) To Treat Chorea in Huntington's Disease?

JANUARY 12, 2015
RDR Staff

At the JP Morgan healthcare conference today, Pratik Shah, President & CEO of Auspex Pharmaceuticals talked about the company’s pipeline with a focus on SD-809 (Austedo) which they plan to file with the FDA later this year. 

Last December,  Auspex reported positive topline results from a Phase III clinical trial evaluating SD-809 in chorea associated with Huntington's disease.  In that randomized, double-blind, placebo-controlled, parallel-group trial, patients with Huntington’s disease (n=90) received SD-809 or placebo and monitored for 13 weeks. The primary endpoint was the change from baseline to maintenance therapy in the Total Maximal Chorea (TMC) score of the Unified Huntington's Disease Rating Scale (UHDRS). Numerous pre-specified secondary endpoints were also tested [treatment success based on patient global impression of change (PGIC) and clinical global impression of change (CGIC), quality of life and balance.]

At the end of the study, patients taking SD-809 achieved a meaningful improvement of 2.5 points on the TMC score from baseline to maintenance therapy compared to placebo (p < 0.0001). The secondary endpoints were also very impressive with significant differences in PGIC and CGIC scores. Equally important, the drug was well tolerated and safe with no differences being reported with adverse events  between patients given SD-809 and those given placebo.

Based on the results, shares of Auspex jumped 60% from approximately $25 per share in December to its current $60 per share.

At present, the only option available for treating chorea in patients with Huntington’s disease is Xenazine (tetrabenazine) and that drug will lose its market exclusivity in August 2015 and be subject to generic competition. Auspex is optimistic that their drug will be able to compete with Xenazine - or generic versions of Xenazine - since it is safer drug. Xenazine comes with a warning about QTc prolongation. In a press release earlier today, Auspex stated they have just completed a study showing SD-809 to have no effect on QTc.

Dr Shah also noted the drug is in early develop to treat patients with tardive dyskinesia and tics associated with Tourette syndrome.

SD-809 is a small molecule inhibitor of vesicular monoamine 2 transporter, or VMAT2, that is designed to regulate the levels of a specific neurotransmitter, dopamine, in the brain.

images obtained from Auspex Pharmaceuticals' presentation at the J.P. Morgan healthcare conference.

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