(Reuters) - Shares of Auspex Pharmaceuticals Inc soared about 60 percent on Tuesday after the drug developer said its product for treating chorea, or involuntary movement associated with Huntington's disease, met the main goal in a late-stage study.
The shares jumped about to $40 in extended trading after closing at $25.09 on Nasdaq.
Patients administered SD-809, Auspex's lead drug, showed an improvement in a standardized score measuring involuntary movement, compared with those given a placebo.
The drug also significantly improved the patients' quality of life, lowering rates of depression and anxiety.
About 90 percent of those suffering from Huntington's disease develop chorea, characterized by involuntary, excessive movements that can impact all parts of the body and interfere with motor functions.
The company said it was also running an additional trial to see if chorea management remained under control when patients were switched overnight to SD-809 from H Lundbeck's tetrabenazine, the current standard of care.
Data from the study suggested that the chorea score for the drug improved by a point in the first and fourth weeks, Auspex said.
Tetrabenazine, marketed as Xenazine in the United States, is expected to lose its market exclusivity for treatment of Chorea in August 2015. If approved, SD-809 may compete with generic versions of the drug.
"Given the well-known side effects of tetrabenazine, which holds a black box warning for suicidality and depression ... we expect SD-809 to gain significant share over generics if approved," William Blair analyst Tim Lugo said.
The drug's safety profile was better than expected and it also met several secondary goals which should significantly differentiate it over tetrabenazine, he added.
Huntington's Disease is a genetic disorder that causes certain cells of the brain to die over time. Since there is no cure for Huntington's disease or way to stop its progress, treatments focus on managing symptoms.
Auspex said it was also evaluating the drug for treatment of Tourette syndrome, a neurological disorder, and idiopathic pulmonary fibrosis, a type of lung disease.
The company plans to apply for the drug's regulatory approval by mid-2015.
Reporting by Amrutha Penumudi in Bengaluru; Editing by Joyjeet Das and Richard Chang