Pfizer Inc and Medivation, Inc announced the initiation of Contact and Constellation, two phase-3 trials of the investigational drug dimebon (latrepirdine) in patients with moderate-to-severe Alzheimer’s disease (AD).

The Contact study will assess as primary endpoints the potential benefits of adding dimebon to ongoing treatment with donepezil HCI tablets, the leading AD medication worldwide, on neuropsychiatric symptoms and activities of daily living. The Constellation study will evaluate as primary endpoints the effects of adding dimebon to memantine HCI, another standard of care, on cognition, memory and activities of daily living.

“Alzheimer’s disease is a growing global epidemic with an unmet clinical need. Many patients with moderate-to-severe Alzheimer’s disease experience behavioral and neuropsychiatric symptoms, which are among the leading causes of placement in care facilities for these patients,” said Pierre N Tariot, director of the Memory Disorders Center at the Banner Alzheimer’s Institute and study investigator. “These studies are intended to evaluate the potential added benefits of dimebon in combination with current standards of Alzheimer’s care.”

In preclinical studies, dimebon has been shown to protect brain cells from damage and enhance brain cell survival, potentially by stabilizing and improving mitochondrial function. The dimebon mechanism is distinct from currently available AD medications.

“Pfizer and Medivation are committed to developing dimebon as a treatment that may meaningfully improve the lives of patients across the full spectrum of Alzheimer’s disease severity,” said Lynn Seely, chief medical officer for Medivation. “The initiation of the Contact and Constellation studies is an important milestone in the broad clinical development of dimebon.”

These studies are part of a comprehensive phase-3 clinical development program, currently consisting of seven trials, to assess the safety and efficacy of dimebon across all stages of Alzheimer’s disease, as monotherapy and in combination with currently available Alzheimer’s treatments, and in Huntington disease.

Latrepirdine is the proposed generic (nonproprietary) name for dimebon.

Contact phase-3 randomized, double-blind, placebo-controlled study will enroll approximately 600 patients with moderate-to-severe AD and neuropsychiatric symptoms at approximately 75 sites in Europe and South America. Patients who are already taking donepezil will be randomized to also receive either dimebon 20 mg three times daily or placebo for six months.

Constellation phase-3 randomized, double-blind, placebo-controlled study will enroll approximately 570 patients with moderate-to-severe AD at approximately 80 sites in the United States, Canada and Europe. Patients already taking memantine will be randomized to also receive either dimebon 20 mg three times daily or placebo for six months.

Medivation and Pfizer have a global collaboration to develop and commercialize dimebon for the treatment of Alzheimer's disease and Huntington disease.