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Lilly study: 1 in 5 Alzheimer's patients misdiagnosed

May 20, 2013

Nearly one in five patients diagnosed with Alzheimer’s disease doesn’t actually have the memory-sapping malady, according to a new study sponsored by Eli Lilly and Co.

The study results, which will be released Monday afternoon, are part of Indianapolis-based Lilly’s campaign to get the federal Medicare program to pay for use of its imaging agent Amyvid, which received U.S. market approval last year.

Wall Street analysts do not expect Amyvid to be a blockbuster product for Lilly. For example, Goldman Sachs analyst Jami Rubin predicts its sales will total just $80 million annually by 2017.

But Amyvid could be a huge help in Lilly’s efforts to bring drugs to market to treat Alzheimer’s. Since there are currently no effective treatments for the disease, any drug that did help with treatment would be an instant blockbuster.

Lilly’s experimental drug solanezumab could have sales topping $4 billion annually if it proves effective in patients with mild Alzheimer’s disease. The drug failed its clinical trials last year when tested in a mix of mild and moderate Alzheimer’s patients, but it showed encouraging results in patients with only mild Alzheimer’s disease.

Lilly officials are going to run a new trial for solanezumab focusing only on mild Alzheimer’s patients—or perhaps even patients with a precursor to Alzheimer’s, referred to as mild cognitive impairment or prodromal Alzheimer’s.

The only way to identify such patients is by using a special kind of imaging test that will show deposits of a protein called amyloid—which is one of two telltale signs of Alzheimer’s disease. The imaging test is called PET, or positron emission tomography.

Before Amyvid, however, the only way to view these plaques was during an autopsy. Now, doctors and researchers can look at amyloid plaques in living patients.

“Amyloid PET imaging in my opinion may be the most important recent advance in AD therapeutic research. … It has allowed us to have complete confidence in the diagnosis of AD dementia, something that was lacking before we used amyloid imaging,” said Dr. Paul Aisen, professor of neurosciences at the University of California-San Diego, during a Jan. 30 meeting of the Medicare Evidence Development & Coverage Advisory Committee.

Aisen, whose research has been behind some of the high-profile failures of experimental drugs aimed at Alzheimer’s, has been in discussions with Lilly on a new research project. He expects that some of the drugs that have failed to be effective in patients with full-blown Alzheimer’s will be effective in earlier stages of the disease.

“Treatments that are only marginally effective in dementia are going to be highly effective in preclinical AD, I predict, and that will mean that eventually we will be screening the population with amyloid PET scans or spinal taps in their 50s to … prevent the development of AD dementia,” Aisen said.

Not everyone agrees with him. For example, panelists on the Medicare advisory commission pointed out that Amyvid has not been directly studied as a predictor of Alzheimer’s disease and that 20 percent to 30 percent of patients who do have amyloid plaques in their brain show no symptoms of cognitive impairment at all.

But if Aisen is right, Amyvid might get wider usage—and more sales—than analysts are currently predicting.

Medicare, even if it pays for patients to use Amyvid, might save the roughly $38,000 it costs per year to treat an Alzheimer’s patient—at least for the 20 percent of them who have been misdiagnosed.

But most significantly for Lilly and other drugmakers, it could open up a field of customers far larger than the 5.2 million Americans that currently have the disease—or even than the 7.1 million expected to have it by 2025.

An international survey conducted in 2011 by researchers at the Harvard School of Public Health found that two-thirds of adults would take a predictive Alzheimer's test were one made available to them.

Lilly is expressly not asking for such widespread testing—at this point. But if it were to occur, the number of patients identified with Alzheimer’s and other forms of dementia could be enormous.

“This study underscores the importance of using objective tools, such as amyloid PET imaging, in addition to clinical assessment as part of a physician’s diagnostic evaluation of patients with cognitive decline,” said Michael Witte, a clinical research scientist at Lilly, who was the lead author of the study on Amyvid released Monday.

That study, conducted in partnership with the Indiana University School of Medicine’s neuroscience institute, tested 199 patients, age 55 or older, who had been diagnosed with either mild or moderate Alzheimer’s disease. Of those patients, 35 of them, or 18 percent, showed few or no amyloid plaques when given a PET scan using Amyvid--meaning they did not actually have Alzheimer's disease.
 

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