With amyloid plaque imaging poised to burst into clinical practice, could the technology be used inappropriately? The question is no longer academic. Amyvid, the F18-labeled tracer recently approved by the Food and Drug Administration (see ARF related news story), is already available for use from radiopharmacies at 16 sites across the U.S. (see Part 1 of this series). The Society of Nuclear Medicine and Molecular Imaging and the Alzheimer's Association have assembled a 14-member Amyloid Imaging Task Force to develop guidelines for, among others, radiologists, neurologists, and general practice physicians, who will use this technology most. The task force has been meeting since April of this year and plans to issue draft recommendations to the research community this July.

"Our objective is to try to form a recommendation as to how this technology should be used in clinical practice, and perhaps even in research," said task force member Maria Carrillo of the Alzheimer's Association, headquartered in Chicago. "We will try to come up with a list of recommendations not only for the healthcare community, but for family members who are wondering if their loved ones should get an amyloid imaging scan," she said.

The task force meets by conference call once every two weeks and will review more than 120 scientific publications on the clinical use of amyloid positron emission tomography (PET) tracers. The group wants to recommend when and why the scan should be used, since indications on the FDA label are relatively brief and only address safety and efficacy, said committee co-chair Satoshi Minoshima, a PET expert at the University of Washington, Seattle. The task force will go a step further and recommend what kind of patient may actually benefit from the technology. For now, and until there is a treatment to prevent or cure AD, the technology will not help everyone, he said.

"We are also looking beyond the published evidence to ask experts in the field what they think could be appropriate in circumstances about which there are no published evidence," said Keith Johnson, of Massachusetts General Hospital in Boston, also a co-chair of the committee. He was careful to point out that Amyvid is but the first of several plaque-imaging PET compounds that could be FDA approved in the near future. Others include florbetaben from Piramal Healthcare, flutemetamol from GE Healthcare (see ARF related update), and AZD4694 by AstraZeneca (see ARF related news story).

The group aims to present a draft at the Alzheimer's Association International Conference (AAIC) in 2012, to be held in Vancouver, Canada, said Carrillo. There, the scientific community will be able to offer feedback. When in its final form, at a date to be determined late in 2012, the guidelines will be published in the Association’s journal Alzheimer's and Dementia and on the SNM and Association websites, said Carrillo. They will appear in videos and educational materials that target families, caregivers, and the public at large.

The committee has reached no decisions yet, but Johnson already foresees a few broad areas of agreement. First, this technology is inappropriate for clinical use in cognitively normal people who, even if they have subjective memory complaints, have no formal evidence of cognitive impairment. On the other end of the spectrum, in Johnson’s view, the technology is inappropriate if there is little doubt that AD is present. If, however, there is substantial doubt about whether measurable impairment is due to AD, and when the information obtained would significantly alter medical management, then an amyloid PET scan could be useful. The full consensus of the committee will remain unknown until at least the AAIC conference. What's more, this task force will likely be the start of a longer process, said Johnson. There may be other efforts around the globe coming up with similar guidelines, and any policies will probably require revisiting as the literature on the topic evolves, Johnson said.

For now, Lilly is following the FDA-approved indication. "We applaud the Alzheimer's Association and Society of Nuclear Medicine's commitment to providing their members with guidance on this new technology," said a company representative. However, she added, "the Amyvid label contains guidance that is based on FDA-approved science and should always be the first resource for information on how, and in whom, to use Amyvid."

The FDA's label is not the be-all end-all of the matter, insists Minoshima. "FDA approval for the safety and efficacy of commercial tracers has to be carefully translated to [ensure the] appropriate use of the technology for the benefit of patients," he told Alzforum in an e-mail. The indication says nothing, for instance, about people who have subjective memory complaints or who are certain to have AD. "In this regard, careful considerations and discussions are necessary," said Minoshima. The other 12 members of the task force include seven academics: Nicolaas Bohnen, University of Ann Arbor, Michigan; Kevin Donohoe, Beth Israel Deaconess Medical Center, Boston, Massachusetts; Norm Foster, University of Utah, Salt Lake City; Peter Herscovitch, National Institutes of Health, Bethesda, Maryland; Jason Karlawish, University of Pennsylvania, Philadelphia; Christopher Rowe, Austin Hospital, Melbourne, Australia; and William Klunk, University of Pittsburgh, Pennsylvania. Completing the panel are Kristi Mitchell and Virginia Papas from the Society of Nuclear Medicine and Molecular Imaging and three representatives from the Alzheimer’s Association, Bill Thies, Maria Carrillo, and Dean Hartley.—Gwyneth Dickey Zakaib.

This concludes a two-part series. See also Part 1.

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References

News Citations

  1. FDA Approves Amyvid for Clinical Use
  2. Coming to a City Near You: Tracer to Picture Brain Amyloid
  3. Miami: Updates on J-ADNI, 18F Tracers, Biopsies
  4. Geneva: The AstraZeneca Ligand—The Fairest of Them All?

External Citations

  1. Alzheimer's and Dementia

Further Reading

Papers

  1. . Amyloid burden and metabolic function in early-onset Alzheimer's disease: parietal lobe involvement. Brain. 2012 Jul;135(Pt 7):2115-25. PubMed.
  2. . In vitro characterization of [(18)F]-florbetaben, an Aβ imaging radiotracer. Nucl Med Biol. 2012 Apr 11; PubMed.
  3. . The prognostic value of amyloid imaging. Eur J Nucl Med Mol Imaging. 2012 Jul;39(7):1207-19. PubMed.
  4. . Using PET with (18)F-AV-45 (florbetapir) to quantify brain amyloid load in a clinical environment. Eur J Nucl Med Mol Imaging. 2012 Apr;39(4):621-31. PubMed.