Teva Pharmaceuticals (NYSE:TEVA) SD-809 (deutetrabenazine) is showing tolerability improvements over tetrabenazine after patients are switched to SD-809 in a Phase III extension study, according to a source familiar with the situation.
The Alternatives for Reducing Chorea in HD (ARC-HD) trial (NCT01897896) has already reported some results in December 2014, and the study entered a long term extension Phase. The study is testing the safety, tolerability and pharmacokinetics of SD-809 in patients who have switched from tetrabenazine to the drug and is due to complete in December 2016, according to ClinicalTrials.gov.
It is crucial that SD-809 continues to demonstrate tolerability benefits over tetrabenazine given that the latter drug has now gone generic in Europe and North America, explained a neurologist who is not involved in the clinical development of SD-809.
The company received a Complete Response Letter (CRL) from the FDA on 31 May for SD-809. A Teva press release noted that this was due to concerns over metabolites. The source noted that the concerns over metabolites may largely stem from the fact that SD-809 is the first deuterated product to be considered for approval. No additional efficacy or safety was required, according to the Teva press release. The company will submit the additional data categorising the metabolites within the next two weeks, the source added.
Analyst reports predict sales of between USD 500-USD 700m for SD-809.