Wednesday, May 29, 2013

Cancer Drug Viewed As Treatment For Alzheimer’s Disease Doesn't Meet Criteria For Repeatability

Advances in Medicine

An article, by Helen Shen, in Nature News casts doubt that a cancer drug can also effectively treat Alzheimer’s disease.

Shen writes:
Bexarotene, a cancer drug touted as a potential treatment for Alzheimer’s disease, may not be the blockbuster remedy scientists were hoping for, according to several analyses published in Science on 24 May 1–4. Four independent research groups report that they failed to fully replicate striking results published in the journal last year 5 by Gary Landreth, a neuroscientist at Case Western Reserve University School of Medicine in Cleveland, Ohio, and his colleagues.
Landreth's team reported that the drug bexarotene could lower brain concentrations of the β-amyloid protein that has long been suspected as a key contributor to Alzheimer’s disease, and could even reverse cognitive impairments in diseased mice. But the study garnered particular attention for its claim that the drug could clear 50% of amyloid plaques — sticky clumps of the protein thought to interfere with brain function—in as little as 72 hours. “That attracted a lot of folks to try to replicate these studies,” says Philip Wong, a neuroscientist at Johns Hopkins University in Baltimore, Maryland. “No drug at the present moment can do things like that.”
None of the follow-up studies published this week replicated the effects of bexarotene on plaques. Two groups did, however, confirm Landreth’s finding that the drug reduced levels of a soluble, free-floating form of β-amyloid, which can aggregate in plaques 4. Not all of the papers examined memory in mice, but one group led by Radosveta Koldamova, a neuroscientist at the University of Pittsburgh in Pennsylvania, found that bexarotene treatment led to cognitive improvements1.
Such mixed results fail the Scientific Method, which is the foundation of modern science. Although it might be a setback for finding ways to treat Alzheimer’s, a debilitating and cruel disease, it is actually a step toward progress. If you read about scientific breakthroughs that occurred in the past, hard work and determination were the keys to success.

Science, and the advancement of medicine, is often a case of one step forward and two steps back. The best scientists understand this and continue to press forward. As the article says: “As the debate over plaques continues, Koldamova says that the cognitive improvement she and Landreth observed suggests that bexarotene is still very promising. ‘Patients don’t go to the doctor because they have plaques. They go because they have memory decline,’ she says.”

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You can read the rest of the article at [Nature]