Another shot at treating Alzheimer's with Dimebon?

As recently as January, tests to use Medivation's ($MDVN) Dimebon (latrepirdine) as a treatment for Alzheimer's disease were deemed to be an abject failure. But today, scientists at Mount Sinai School of Medicine and their international colleagues respond to that assessment with a hearty "not so fast." They see a new round of promising mouse trials as giving the drug another chance because it seemed to generate stunning results by targeting the neurodegenerative condition at an earlier stage.

Details are published in the latest issue of the journal Molecular Psychiatry. But as the scientists explain, the genesis of their study began in 2010, right around when a pivotal late-stage trial for the drug failed to hit co-primary and secondary endpoints. At that time, Medivation's shares subsequently collapsed at the news and layoffs ensued. (Earlier this year, Pfizer ($PFE) wrote off its $725 million partnership with Medivation after a 12-month study of the drug showed it didn't generate any significant improvement for patients--seemingly the final nail in the coffin.) And the company has moved on to other development programs.

For the new study, lead researcher Sam Gandy, director of the Mount Sinai Center for Cognitive Health, started looking at the drug's mechanism of action in mice before the fateful 2010 news, which countered more promising human studies in Russia in 2008, where the drug was initially approved in the 1980s as an antihistamine. (The drug even generated disappointing results in 2011 in a late-stage study for Huntington's disease.)

In a statement, Gandy said his team's data even in 2010 encouraged them to proceed, despite the disappointing Phase III news. For their trial, they gave latrepirdine or placebo randomly to mice engineered to have early stages of Alzheimer's disease. Results were stunning, with the drug stopping loss of memory and neuropathology progression. What's more, the team determined that the drug beefed up the autophagy process, which offers protection against neurodegeneration in the brain.

"The findings from our animal model studies indicated that this drug should not be discarded, and that, if its mechanism of action can be optimized, it still has potential," Gandy said in a statement. 

Perhaps. The scientists say their results could lead again to human clinical trials, but this time in patients who have earlier stages of Alzheimer's. In the meanwhile, animal studies continue. But there is a long road ahead. Drugs that show promise in mice don't always work the same way in humans. And while Dimebon/latrepirdine may have new life as a drug that can tackle Alzheimer's--at least at an earlier stage of the disease--it will be years before that theory can be definitively tested.

- read the release

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