Research was conducted in both Russia and western nations into potential applications as a neuroprotective drug to combat Alzheimer's disease and, possibly, as a nootropic, as well. After a major phase III clinical trial for Alzheimer's disease (AD) treatment failed to show any benefit, three other AD trials continued. Major industry-based development in this indication essentially stopped after another Phase III trial suffered the same fate in 2012. Dimebon failed in the phase III trial for Huntington disease.
Latrepirdine is an orally active, small molecule compound that has been shown to inhibit brain cell death in animal models of Alzheimer's disease and Huntington's disease. Research suggests it may also have cognition-enhancing effects in healthy individuals, in the absence of neurodegenerative disease pathology. However, because of negative results in human clinical trials, the drug remains unlicensed for any neurodegenerative condition.
Alzheimer's disease: failed in Phase III clinical trials
Latrepirdine attracted renewed interest in 2009 after being shown in small preclinical trials to have positive effects on persons suffering from Alzheimer’s disease. Animal studies showing potential beneficial effects on Alzheimer's disease models were shown in Russian research in 2000. Preliminary results from human trials have also been promising. In an initial six-month phase II trial, results have shown significant improvement over placebo at 12 months. Latrepirdine showed promising results in a phase III-equivalent, double-blind trial in Russia with mild–moderate stage patients. In April 2009, Pfizer and Medivation initiated a phase III trial (CONCERT study) aiming for FDA approval. In March 2010, Pfizer announced that this clinical trial failed to show any benefit for the treatment of Alzheimer's disease patients.
In March 2010, the results of a clinical trial phase III were released; the investigational Alzheimer's disease drug dimebon failed in the pivotal CONNECTION trial of patients with mild-to-moderate disease.
With CONNECT, the remaining Pfizer and Medivation Phase III trial for latrepirdine in Alzheimer's disease failed in 2012, effectively ending the development in this indication.
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