Results from a Phase 3 clinical trial found that deutetrabenazine (SD-809), an investigational drug developed by Teva Pharmaceutical Industries, improved chorea among Huntington’s disease patients. But the researchers caution that more studies are needed to ascertain the treatment’s long-term effectiveness and safety.
Data from the trial showing that the drug improved swallowing and overall motor function in Huntington’s patients was presented earlier this year at the 68th American Academy of Neurology (AAN) meeting in Vancouver.
The new report by the Huntington Study Group — titled “Effect of Deutetrabenazine on Chorea Among Patients With Huntington Disease“ — was published in the journal JAMA and focused specifically on chorea, the typical symptoms characterizing the illness.
Patients were randomized to receive either SD-809 or placebo, with both patients and study staff unaware of who received the active drug. Both groups consisted of 45 Huntington’s patients, and the drug or placebo was adjusted to reach an optimal dose over eight weeks. This dose was then maintained for four more weeks, followed by a one-week washout period.
Patients were on average 53.7 years old, and 44.4 percent were women. The report shows that SD-809 improved chorea, with average scores decreasing by 4.4 points in treated patients and 1.9 points in the placebo group. [Baseline total maximal chorea scores of the 90 enrolled patients were 8 or higher.]
Also, 51 percent of patients receiving the drug reported the treatment was successful. Measuring treatment success with clinical tools produced a slightly lower number, with 42 percent of SD-809 treated patients meeting the definition for success.
The authors underscore that although the trial results are promising, more studies assessing both SD-809’s clinical effectiveness and its safety on a longer time scale are needed, and such trials are likely to continue after a possible approval of the drug.
The U.S. Food and Drug Administration (FDA) issued a Complete Response Letter in June, answering Teva’s New Drug Application (NDA) for SD-809, submitted last year. A complete response letter suggests changes that must be made before an application is approved. In this case, the FDA requested Teva examine the blood levels of certain metabolites in the patients, but did not make mention of further clinical studies.