FDA Expresses Concern About Eli Lilly Alzheimers Imaging Test

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The US Food and Drug Administration (FDA) will meet later this week to discuss an imaging agent made by Eli Lilly and Co used with positron emission tomography (PET) to detect Alzheimer’s disease. The agency does not question the safety of the radioactive dye, but the concern is whether technicians can properly read the scans and how useful they are in assessing the neurodegenerative disease.

FDA Questions Clinical Usefulness of Amyvid

Florbetapir F 18 is an agent intended to detect the presence of beta-amyloid plaques in the brain. These plaques are a hallmark characteristic of Alzheimer’s disease and occur when beta-amyloid protein fragments accumulate between neurons, interrupting normal communication. The radioactive dye sticks to these brain plaques so that they are visible on a PET scan, possibly even before the patients begin to show symptoms of the disease.

In addition to detection of plaques, Florbetapir F 18 (also known by the proposed brand name Amyvid) could also be used in clinical trials for proposed treatments for Alzheimer’s. The drug is also being tested for use in Parkinson’s disease.

Read: PET Scan Can Detect Alzheimer's Symptoms

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Seven studies support the drug’s safety and efficacy, according to documents presented to the panel for discussion. The FDA says that “no troublesome safety signals have been detected”, but at least one of the major studies included too small of a sample size to draw wider conclusions.

The FDA’s main concern “relate to an apparent insufficient development of the reader training methods proposed for clinical use.” They cite a “high variability” in reading the scans, where imaging readers didn’t always produce the same interpretation for each image.

Avid, the original developer of the drug who was acquired by Eli Lilly in December, has proposed using a website to train nuclear medicine and radiology physicians in using the drug with PET scans.

Read: Accumulation of Beta Amyloid in Alzheimer's the Result of Impaired Clearance

The agency is also concerned about “clinical usefulness” as beta-amyloid plaques are but just one feature of the disease. The FDA staff has said that it sees “no convincing evidence of benefit from Amyvid PET.”

A panel of experts in central nervous system drugs will meet Thursday to discuss Florbetapir F 18 and offer its recommendations to the FDA for approval. The agency will likely make its final decision in March 2011.

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