Dimebon, aka latrepirdine, failed to show efficacy in a Phase 3 clinical trial of people with Huntington’s disease, according to data released 11 April by the drug’s sponsors, Medivation Inc. and Pfizer. Over the course of six months, patients taking 20 mg Dimebon three times a day showed no improvement over controls on the two primary endpoints of cognition (as judged by the Mini-Mental State Examination) and global improvement (according to the Clinician’s Interview-Based Impression of Change plus caregiver input). The HORIZON trial, a collaboration between the drug’s sponsors, the Huntington Study Group and the European Huntington’s Disease Network, enrolled 403 patients at 64 sites in North America, Australia, and Europe.
Dimebon initially made a big splash when Phase 2 data from a trial in Russia indicated it not only slowed progression of Alzheimer’s disease (AD), but actually reversed cognitive decline. Those data did not hold up in a Phase 3 trial (see ARF related news story). As with the AD trials, the HORIZON trial failed to recapitulate positive effects seen in Phase 2 (see ARF related news story).
According to the sponsors, the Phase 3 CONCERT trial of Dimebon in AD patients will continue as planned. Results are expected in early 2012.—Tom Fagan.