June 11, 2007 - Scientists reported some progress in their search for new drugs to treat Alzheimer’s disease Monday, even while researchers studying a closely watched new drug said they must rework their data to determine if it is effective.
Researchers attending a major scientific meeting in Washington have not achieved any “magic bullets” against the brain-wasting effects of Alzheimer’s disease. At the same time, they say they’re optimistic that a series of new treatments could prove to slow or reverse the disease.
Scientists studying one promising new drug, called Alzhemed, had hoped to announce major new findings this week. But the study leader announced that statistical issues would force scientist to reanalyze their results before determining if the drug works.
Reworking of data is often a red flag for regulators approving new drugs because it can be a sign the product did not work as hoped under a company’s original study design. But researcher Paul Aisen, MD, insisted at the annual meeting of the Alzheimer’s Association that the move was part of the overall study plan.
“This process does not indicate that the drug didn’t work,” said Aisen, a professor of neurology at Georgetown University, who is leading the Alzhemed study for Neurochem Inc.
The drug works in theory by blocking the formation of amyloid, an inflammation-causing protein known to be a key cause Alzheimer’s disease.
Aisen suggested that some early data were “in favor of treatment” instead of placebo pills, but he said he would not speculate further on whether the drug appears effective.
“At this point, conclusions can’t be drawn,” he said.
If the drug proves worthy, it could be a major step in Alzheimer’s treatment. Existing drugs on the market mostly slow the disease’s unrelenting progression or ease some symptoms. Observers eagerly await Alzhemed’s results because it could actually be a breakthrough in treating the underlying disease itself.
But for now, that breakthrough remains unproven.
Sam Gandy, MD, who leads the Alzheimer’s Association scientific advisory council, called the delay “science as usual.”
“This is exactly what we should expect: incremental progress,” said Sam Gandy, “We don’t expect there to be one single compound” that will prove to be a cure for the disease.
Russian Drug Advances
Researchers are also eyeing another drug, called Dimebon, which is also showing some promise in early clinical trials.
Researchers have observed that the drug can delay the onset of memory loss and deteriorating functioning that are the hallmark of Alzheimer’s. Of a total of 183 Russian patients, Alzheimer's patients who used the drug three times per day had better memory scores after three months than those who took placebo.
Dimebon was sold as an antihistamine in Russia during the 1980s. Regulators there then found that it has many of the same chemical properties as already-approved Alzheimer’s drugs like Aricept. It is now slated for a major clinical study in the U.S. beginning next year.
Rachelle Doody, MD, of Baylor College of Medicine in Houston, who leads the drug’s American research team, said patients who took the drug also showed no change in their ability to perform normal activities like cleaning the house or talking on the phone, “while those on placebo have had a slow but steady progression” of their disease.
A Shake a Day?
Another company is placing its bets on a treatment that makes an end run around poor sugar metabolism in the brains of many Alzheimer’s patients.
The drug, called Ketasyn, which comes in the form of a shake-like drink, delivers a dose of proteins called ketone bodies to the brain. Brain cells can use ketones as an alternative energy source so that they don’t have to rely on glucose.
If it works, one advantage of Ketasyn could be that patients can begin taking it as soon as doctors detect poor sugar metabolism in their brains. In many patients that’s a decade or more before the onset of Alzheimer’s symptoms.
This is far upstream of some of the other therapies you’ve been hearing about,” said Lauren Costantini, MD, a vice president of Accera Inc., the drug’s maker.
Of a study of 152 patients who received either Ketasyn or placebo, those who were given Ketasyn had improvement in mental test scores compared with those on placebo at 45 days.
The drug doesn’t seem to work in everyone. Patients positive for a gene known as ApoE4, a known factor in Alzheimer's disease, didn’t respond to Ketasyn. But those who don’t have the gene showed better memory and thinking after three months than those who took placebo.
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