Treatment Online

Alzheimer's Drug Passes Phase I Trial
> 1/28/2008 3:30:35 PM

The pharmaceutical company CoMentis has announced the successful completion of the Phase I trial for its Alzheimer's Disorder (AD) drug CTS-21166. The drug delivers a molecule designed by Dr. Arun Ghosh, a professor at Purdue, to inhibit beta-secretase. At the turn of the millennia, Dr. Ghosh identified beta-secretase as a vulnerable part of the process that leads from amyloid-beta to neural plaque, AD, and then eventually death. Seeing that beta-secretase is a necessary builder of the amyloid-beta plaques suspected of causing AD, he started a company to discover whether safe beta-secretase inhibitors could be produced.

This first human trial met its goal. 48 healthy patients orally ingested 7 different doses of the drug (one being a placebo), and their levels of amyloid-beta dropped proportionally until it reached a 60% fall. There were no negative health consequences, though there were also no measurable positive ones because the patients did not yet have the disorder that this treatment is meant to prevent. This lack of evidence points to a crucial assumption that the research rests on: amyloid-beta causes AD. If this proves not to be true, then the measuring stick for this drug is faulty.

While science ideally builds brick by solid brick, in practice it often climbs overeagerly on shaky assumptions. A recent example of this is the new research showing that Vytorin, a popular heart-attack drug, does not actually reduce the risk of a cardiac event. It received FDA approval because it does a good job reducing cholesterol, and the reigning assumption was that cholesterol causes arterial damage and heart-attacks. This latest finding suggests that the link between cholesterol and heart-attack is either illusory or at least more complicated than previously thought. There are many rival hypotheses for what causes AD, and we should not assume that a drug that interrupts amyloid-beta production will automatically improve cognitive function.

The Phase II trial for CTS-21166 is set to begin this year. If the drug demonstrates observable benefits for AD patients, then we will be one step closer to confirming the amyloid-beta theory and to finding an effective treatment. If patients are not helped, then we will have to rethink the disease and try again.

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