On October 25, the U.S. Food and Drug Administration (FDA) approved Vizamyl (flutemetamol) for use with positron emission tomography (PET) brain imaging in adults being evaluated for Alzheimer's disease (AD) and dementia. The approval was the FDA’s second approval for a radioactive diagnostic drug to detect images of beta-amyloid—a factor that may fuel the progression of AD. Amyvid was the first such drug approved.
“This is an advancement for AD research and clinical work,” said psychiatrist Sandra Jacobson, M.D., an associate research professor at the University of Arizona College of Medicine, in an interview with Psychiatric News.
“This technology enables the physician to identify patients with significant amyloid accumulation in cerebral gray matter, so that the patient with early or even presymptomatic Alzheimer’s disease can be identified.”
As a radioactive tracer, Vizamyl works by binding to beta-amyloid, which in turn, emits light to produce an image detected by the PET scanner. A negative Vizamyl scan means that there is little or no beta-amyloid accumulation in the brain and that the cause of the dementia is probably not AD, according to the FDA. A positive scan means that there is probably a moderate or greater amount of amyloid in the brain, but it does not establish a diagnosis of AD or other dementia.
The effectiveness of Vizamyl was measured in two clinical trials with a total of 384 participants with varying degrees of cognitive function. All study subjects were injected with the drug and underwent PET imaging. Results showed that Vizamyl accurately detected beta-amyloid in the brain. In addition, the study confirmed that the scans were reproducible and could be interpreted accurately by trained readers.
The safety of the radioactive drug was further established in a study of 761 participants. Safety risk included hypersensitivity reactions and radiation exposure. Common side effects included flushing, headache, increased blood pressure, nausea, and dizziness.
Because of Vizamyl’s success as an effective and low-risk drug, Jacobson said that “the question now comes down to whether flutemetamol [Vizamyl] is superior to florbetapir [Amyvid]. CMS [Centers for Medicare and Medicaid Services] asked for more evidence regarding florbetapir’s utility before further consideration of Medicare coverage. Will the same hold true for flutemetamol? At this point, it is too early to tell.”
Vizamyl is manufactured for GE Healthcare by Medi-Physics Inc.
