Group Alleges Critical Omission From Imaging Agent Study

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imageU.S. consumer group Public Citizen is alleging that researchers with ties to Eli Lilly and Co. withheld from the Journal of the American Medical Association (JAMA) important information that should have been included in a study of Amyvid (florbetapir), an imaging agent for Alzheimer’s disease. Published on January 19, the study assessed the effectiveness of PET scans using Amyvid, which aims to detect the beta-amyloid plaque associated with Alzheimer’s disease in the brains of living persons via PET scans. The U.S. Food and Drug Administration (FDA) this past March declined to approve the imaging agent, citing the need to ensure the scans can be accurately read.

In a letter that appeared in yesterday’s online edition of JAMA, Public Citizen claims the study’s authors excluded data pertaining to how accurately the scans were interpreted from one physician to the next. "By withholding important information, the authors misled the journal and its readers to believe that this test for identifying brain abnormalities was more reliable than it actually is," write Michael Carome, MD, deputy director of Public Citizen's Health Research Group, and Sidney Wolfe, MD. Carome and Wolfe hold that the authors of the paper submitted to JAMA median values for PET scan reader scores, but failed to also provide critical individual reader score data submitted to the FDA by Eli Lilly unit Avid Radiopharmaceuticals on September 17, 2010. Moreover, they assert, “FDA analyses of these data show substantial interreader variability among independent, extensively trained readers of the florbetapir-PET scans for individuals in the autopsy cohort, emphasizing that florbetapir-PET imaging fails to provide an accurate and reliable assessment of amyloid burden."

The May 11 issue of JAMA also includes a rebuttal letter from Christopher M. Clark, MD, the study’s lead author, and his colleagues, stating that the median was the pre-specified, FDA-endorsed, primary endpoint. Clark is associated with Lilly’s Amyvid development group. Lilly is seeking to market Amyvid for use with PET scans to rule out beta-amyloid plaque, but not to diagnose the disease. Both Lilly and the Avid Radiopharmaceuticals unit have said they are working to address the questions raised by the FDA advisory panel and will continue to do so in an ongoing dialogue.