Auspex Pharmaceutical’s experimental medicine designed to reduce abnormal movements associated with Huntington’s disease is on track for a US filing next year after hitting targets in a Phase III trial.

SD-809 is being assessed for the treatment of chorea, which is characterised by involuntary, excessive movements impacting all parts of the body and develops in around 90% of HD patients.

"For many individuals with Huntington's disease, chorea is a key symptom impacting safety, function and quality of life. New, safe and tolerable therapies for chorea treatment are clearly needed to make this disease an increasingly treatable condition," said Samuel Frank, associate professor of neurology, Boston University School of Medicine and principal trial investigator. 

Top-line data from the Phase III study show that the drug hit its primary target of inducing a meaningful improvement (2.5 points) on the Total Maximal Chorea (TMC) score of the Unified Huntington's Disease Rating Scale (UHDRS), as well as hitting secondary endpoints including quality of life measures.

“These clear and unequivocal results are clinically meaningful and suggest that SD-809 may play an important role in the treatment of Huntington's disease symptoms,” said Prof Frank.

Well tolerated

On the safety side, SD-809 was well tolerated, with was no difference in the rate of dose reduction between the drug and placebo (6.7% in each group). There was one patient with two serious adverse events (cholecystitis and agitated depression) in the treatment group, and one patient with one serious adverse event (exacerbation of COPD) in the placebo group, the firm noted.

“Any drug that suppresses chorea associated with Huntington's disease, with such a low rate of somnolence and depression, as suggested by these findings, would be a welcome addition to the treatment options available for my patients,” said trial investigator Joseph Jankovic, professor of neurology and director of the Parkinson's Disease Center and Movement Disorders Clinic, Baylor College of Medicine, commenting on the findings.

Auspex said it plans to submit a New Drug Application in the US by mid-2015, and stressed it remains “fully committed” to assessing the promise of SD-809 in other movement disorders, such as tardive dyskinesia and Tourette syndrome.