New study refutes Targretin claim for treatment of Alzheimer's

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Last year, scientists reported what seemed like a breakthrough approach to treating Alzheimer's disease. In the journal Science, researchers suggested that the drug bexarotene--marketed as Targretin--could rapidly break apart beta amyloid plaque deposits characteristically found in the brains of Alzheimer's patients.

The authors of the study published Feb. 9, 2012, claimed that, in mice, the drug eradicated most of the plaques and rapidly reversed symptoms of Alzheimer's, including pathological, cognitive and memory deficits related to the onset of the disease. But new research suggests those findings may have been too good to be true.

In separate studies that attempted to replicate the original one, researchers from the University of Chicago, Northwestern University, Massachusetts General Hospital, Washington University in St. Louis and the University of Tübingen in Germany found that bexarotene did not reduce the number of plaques in the brains of three different strains of mice during or after treatment. The findings were published in the May 24 issue of the journal Science.

Bexarotene has yet to be tested as a treatment for Alzheimer's disease in humans, but the new study results raise concerns about patient safety.

"Anecdotally, we have all heard that physicians are treating their Alzheimer's patients with bexarotene, a cancer drug with severe side effects," said co-author Robert Vassar, professor of cell and molecular biology at Northwestern University Feinberg School of Medicine, in a statement. "This practice should be ended immediately, given the failure of three independent research groups to replicate the plaque-lowering effects of bexarotene."

The FDA approved bexarotene in 1999 to treat refractory cutaneous T-cell lymphoma, a type of skin cancer, but once approved, drugs are often prescribed for off-label use. The drug can cause serious side effects, including pancreatitis, thyroid problems, headaches, fatigue, weight gain, depression, nausea and vomiting and rash.

- here's the press release
- read the technical comment in Science

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