On January 19, 2011, the FDA expressed concerns about an Alzheimer’s brain imaging PET scan that is said to detect amyloid plaques in the brain. They were concerned about whether technicians can properly even read the scans, and they were concerned about how useful the scans are in assessing the neurodegenerative disease.
FDA staff found "high variability" in reading the scans where imaging readers didn’t always produce the same interpretation for each image and “no convincing evidence of benefit. "
Nevertheless, on January 21, 2011, an FDA advisory committee "recommended unanimously" its approval of the Avid Radiopharmaceuticals (now a subsidiary of Eli Lilly) scan.
The New York Times front page article (Jan 21) failed to report any of the FDA’s concerns.
Instead Times science reporter Gina Kolata, transcribed the sweeping, unfounded, promotional claims of the proponents of this latest ill-advised medical screen. We say, ill-advised because the amyloid detecting PET scan is likely to misdiagnose millions of people and because it has absolutely no clinical value for patients.
An informative report by EMAXHEALTH is posted below.
The Times’ reporter–as is her "journalistic" practice-has given the PET screen promoters the entire space in her front page report–thereby lending credibility to their implausible claims:
“It’s a landmark day for our field,” said Dr. P. Murali Doraiswamy, an Alzheimer’s researcher at Duke University who was one of the Avid trial investigators.
“This is a big deal,” said Dr. Pierre N. Tariot, director of the memory disorders center at the Banner Alzheimer’s Institute in Phoenix. Asked if he would be using the scans, Dr. Tariot replied, “Absolutely.”Dr. Tariot is an investigator in studies by Avid, now a subsidiary of Eli Lilly & Company, and its competitors.
Dr. Reisa Sperling, director of the Center for Alzheimer’s Research and Treatment at, who is another consultant to Avid-Eli Lilly, is quoted in The Times stating that the FDA panel’s vote “has moved us a monumental step forward,” adding that with the scans “we will not just be guessing clinically.”
Dr. Norman Foster, who heads the University of Utah Center for Alzheimer’s Imaging and Research, is quoted saying the approval of the Avid scan "would be a historic advance in neurology and in the daily management of patients with memory complaints….The preventable costs are enormous. The emotional toll is incalculable."
Reality check: the assumption that amyloid plaques are the causal evidence for diagnosing Alzheimer’s Disease is a matter of intense controversy.
Indeed, even Dr. Doraiswamy acknowledges: "Some people have plaque without having Alzheimer’s, so if a scan shows plaque, doctors will have to use their clinical judgment, taking into account a patient’s symptoms, in deciding what the scan results mean."
Dr. Sanjay Pimplikar a neurologist at the Cleveland Clinic argued against the use of these tests to diagnose Alzheimer’s in an OpEd in the Times, July, 2010. He argued against such scans because their predictive potential is uncertain, at best.
"we now know that roughly one-third of all elderly adults have such plaques in their brains yet function normally. And eleven clinical trials, recently made public by a group of drug companies, that were aimed at reducing these plaques in Alzheimer’s patients all failed to show cognitive improvement, even when the brains were cleared of plaques."
"Thus, the presence of plaques cannot predict with any accuracy or specificity that an individual is going to acquire the disease — and researchers are increasingly looking beyond the amyloid hypothesis for an adequate explanation for Alzheimer’s."
Kolata didn’t ask, and Dr. Foster doesn’t say, how the PET scan would advance neurology or the daily management of patients.
Since there is as yet no medical treatment that can slow or reverse the disease, the only "historic advance" will be the billions of dollars to be made by stakeholders from useless, costly PET scans, and ineffective drugs with adverse side-effects that will, no doubt, be widely prescribed for people whose scans show plaques.
The danger of overdiagnosis is very real. Dr. Pimplikar cited the example of the treatment of prostate cancer:
A study in the Journal of the National Cancer Institute, Prostate Cancer Diagnosis and Treatment After the Introduction of Prostate-Specific Antigen Screening: 1986-2005, found that in the two decades after the test was introduced, prostate cancer was detected in more than 1 million additional men being diagnosed and treated for prostate cancer in the United States. The growth is particularly dramatic for younger men. Given the considerable time that has passed since PSA screening began, most of this excess incidence must represent overdiagnosis. "
Whose interests are being served? Certainly not the public nor patients suffering from Alzheimer’s.
Vera Hassner Sharav
Denise Reynolds RD on 2011-01-19
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.
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 in using the drug with PET scans.
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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