Ruling out Alzheimer's:
Two new chemicals that could revolutionize our ability to diagnose dementia correctly are near final approval. The similar chemicals, florbetapir by Ely Lilly and flutemetamol from GE, will be the first imaging agents to offer a practical way to help detect signs of amyloid plaque in the brain.
Only 60% of people with dementia suffer from Alzheimer's, though doctors may be quick to diagnose any signs of dementia as Alzheimer's. While doctors use brain scans and mental exercise tests to determine when a patient probably has the disease, a definitive diagnosis can currently be made only through an autopsy after death. This reality sometimes results in a dangerous misdiagnosis. For example, some types of dementia are reversible and a misdiagnosis of Alzheimer's can result in missing the opportunity to reverse the dementia. Another example is Lewy Body dementia, which is initially misdiagnosed as Alzheimer's 80% of the time. This may result in the dangerous prescribing of antipsychotics, helpful in Alzheimer's but potentially lethal in Lewy Body dementia.
This new type of brain scan could quickly rule out an Alzheimer's diagnosis.
What's holding these imaging agents back are the FDA's “major concerns” about the lack of standardized tools to decipher the results of this new type of brain scan and their significance to patient health.
The FDA just handed down its opinion on the first agent, florbetapir, also known by the brand name Amyvid. The U.S. Food and Drug Administration's (FDA) Peripheral and Central Nervous System Drugs Advisory Committee decided in a 13-3 vote that it could not yet approve Amyvid™ (florbetapir). At the same time, they voted unanimously (16-0) to recommend approval of Amyvid conditional on a reader training program that demonstrates better reader accuracy and consistency. That is to say, the scans were useful but doctors need to improve how they read and interpret the scans before this imaging agent can be rolled out for prime time. The FDA supported that the scans were essentially effective and there were no significant safety concerns.
The FDA committee also agreed that a negative scan would be useful in ruling out Alzheimer's. In an Amyvid statement, the FDA's committee found Amyvid "clinically useful in indicating that Alzheimer's pathology is unlikely to be the cause of a patient's cognitive decline."
Amyvid was developed by Avid Radiopharmaceuticals. Ely Lilly acquired Avid Radiopharmaceuticals, Inc. in December 2010. Amyvid was the first beta-amyloid imaging compound to enter multi-center, investigational new drug (IND) clinical studies in the United States. Amyvid was recently assigned priority review designation by the FDA.
The committee is a key hurdle but it is up to the FDA to offer final approval. The FDA considers the committee's recommendations. They take the advice of their Advisory Committees into consideration when reviewing investigational drugs, but are not bound by their recommendations.
"We appreciate the careful and thoughtful review of our data today by the Committee," said Daniel M. Skovronsky, M.D., Ph.D., CEO, Avid Radiopharmaceuticals, Inc. "We are encouraged that they recommended a clear path toward approval."
I found this article on Alzheimer's Weekly.
Alzheimer's A Caretakers Journal
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