Poster 20: Pridopidine (ACR16) in Huntington's Disease: An Update on the MermaiHD and HART Studies

Abstract

Background Pridopidine (ACR16) belongs to a novel class of compounds called dopaminergic stabilizers. Initial studies in patients with Huntington's disease (HD) have been encouraging, demonstrating some beneficial effects, including improvement in motor function and affective symptoms. To further investigate the potential for pridopidine as a symptomatic treatment in HD, two clinical trials are ongoing. Methods The MermaiHD study (Multinational EuRopean Multicentre ACR16 study In HD) is a phase 3, double-blind, placebo-controlled study in eight European countries. Patients are randomized to pridopidine (45 mg q.d. or 45 mg b.i.d.) or placebo in equal proportions. This 6-month study is followed by a 6-month, open-label extension. The HART study (HD ACR16 Randomized Trial) is a double-blind, placebo-controlled, phase IIb study in the U.S. and Canada. It is of 3 months duration, and patients are randomly assigned to pridopidine (10, 22.5, or 45 mg b.i.d.) or placebo. The primary efficacy endpoint for both studies is the effect of pridopidine on patients' voluntary motor function as measured by the modified motor score—a subscale of the Unified HD Rating Scale. Secondary endpoints include the overall clinical impression of the patients, cognitive function, and the severity of neuropsychiatric symptoms. Results The MermaiHD study has recruited the targeted population of 420 patients. A substantial number of patients have finished the 6-month blinded treatment period and have now entered the open-label extension. Early results from the double-blind MermaiHD study are expected to be available in early 2010. Conclusions Data from these studies will inform on the potential of pridopidine to improve symptoms in patients with HD.