Public Citizen Objects to Approval of Lilly’s Amyloid Tracer
I’m not sure what it means when Public Citizen and I are in
agreement. Possibly the Earth’s about to blow up. Or we’re both really right about opposing a really wrong issue—like the possible FDA approval of Lilly’s amyloid-imaging
tracer, Amyvid (or florbetapir F18 injection for PET).
I’ve taken my objections about the dubious clinical utility of this product to a blog, namely this one (see here, here, and here, for instance),* and Public Citizen’s taken overlapping objections to its own web site. As well, the pharma watchdog group is expressing its dissent in a more formal and official manner: namely, in a newly submitted letter to the editors of JAMA, who published a seminal, but problematic, company-funded study of the tracer back in January (access to both the published study and the letter require subscription).
Public Citizen seems to be particularly troubled by the inter-reader variability of Amyvid-enhanced PET images, as expressed previously by FDA reviewers. Moreover, the group is really disturbed that the study authors did not provide individuals scores of the 3 PET readers but, instead, supplied a median score. (For details and excerpted text from the JAMA letter, read yesterday’s post at Pharmalot.) Public Citizen is also concerned that the study authors compared the PET results from widely disparate groups: relatively young adults** and end-of-life elderly. And even then, the readers apparently still had trouble agreeing on rating scores, in some cases.
Public Citizen concluded that inter-reader variability would “only get worse,” once the tracer is approved and its enhanced images are read by a wider group of variably trained physicians. “As a result,” the group predicted, “tens of thousands
of patients will have either a false-positive test or a false-negative
test. This will lead to unnecessary anxiety and treatment in some
patients, false reassurance in others and a waste of millions of
* Or alternatively, perform a search of this blog with “florbetapir.”
** As opposed to cognitively normal and healthy elderly.
Photograph: Atrophied brain from person with AD from National Institute on Alcohol Abuse and Alcoholism.