FDA issues new draft guidance on Alzheimer's drug testing

The Food and Drug Administration issued draft guidance (PDF) today outlining how drug manufacturers could enroll patients who are in the early stages of Alzheimer's disease in clinical trials in an effort to urge development of new treatments.

Few new drugs have been developed to treat the symptoms of Alzheimer's disease.

The FDA has approved three new drugs since 1998. During the same timeframe, at least 101 drugs have failed to gain approval, according to a report released in September by the Pharmaceutical Research and Manufacturers of America.

The agency acknowledges that the standard approach to enrolling patients with Alzheimer's disease in clinical trials has had “major limitations,” notably in instances where the patients have yet to demonstrate clinical impairment from the disease.

The FDA went on to say it may consider biomarkers as supportive secondary outcome measures but would not consider approving a drug based on the use of a biomarker as a surrogate outcome measure.

“The scientific community and the FDA believe that it is critical to identify and study patients with very early Alzheimer's disease before there is too much irreversible injury to the brain,” said Dr. Russell Katz, director of the neurology products division in the FDA's Center for Drug Evaluation and Research, in a statement. “It is in this population that most researchers believe that new drugs have the best chance of providing meaningful benefit to patients.”

However, the FDA said that assessing the impact of a treatment on patients with early Alzheimer's disease has been difficult because clinical impairment has yet to emerge in many of those patients.

Drugs developed to treat patients with noticeable dementia are required by the FDA to show an effect on a patient's abnormal thinking, in addition to how well he or she functions.

The absence of validated, non-invasive biomarkers and the progression of the disease are two challenges manufacturers face when enrolling and retaining patients in clinical trials, according to the PhRMA report. Both of those factors lead to longer and more expensive trials.

The FDA's proposal to consider biomarkers as a secondary outcome measure could eventually lead to biomarkers being recognized as a primary outcome measure, which would produce shorter and likely less expensive clinical trials, said Maria Carrillo, vice president of medical and scientific relations at the Alzheimer's Association.

“It opens the door for prevention trials,” she said.

The number of people with Alzheimer's disease is expected to triple to 13.8 million people by 2050, compared to 4.7 million in 2010, according to a study published Wednesday in Neurology. The study attributes the increase to an aging Baby Boomer population.

“Our study draws attention to an urgent need for more research, treatments and preventive strategies to reduce this epidemic,” said Jennifer Weuve, co-author and assistant professor of medicine at the Rush University Medical Center's health aging institute, in a news release.

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