On the left are 11C-labeled PiB PET scans of a patient with mild Alzheimer’s disease (AD) viewed from the top of the head down (top left) and from the side of the head (bottom left). The images on right show similar PET scans from a healthy elderly person (control) with no memory impairment. Image source: Chester Mathis, PhD, University of Pittsburgh, Pennsylvania

Eli Lilly and its wholly owned subsidiary, Avid Radiopharmaceuticals, have received a complete response letter from the FDA for their new drug application (NDA), denying the approval of florbetapir F-18 injection (Amyvid), a PET imaging agent under investigation for the detection of beta-amyloid plaque in the brains of living patients, citing concerns about reader interpretation training.

According to the Indianapolis-based Lilly, the complete response was “primarily focused on the need to establish a reader training program for market implementation that helps to ensure reader accuracy and consistency of interpretations of existing Amyvid scans.”

"Lilly and Avid have been engaged in an active and ongoing dialogue with the FDA," said Wei-Li Shao, Lilly brand director for Amyvid. "We remain confident in the data submission package for Amyvid." Since questions on the reader training program were raised by FDA reviewers late last year, Lilly and Avid said they have been working to address these questions and will continue to do so in an ongoing dialogue with the FDA.

Clinical studies for Amyvid are still being conducted in the European Union, North America, South America, Australia and Asia.

On Jan. 20, the FDA Peripheral and Central Nervous System Drugs Advisory Committee decided not to approve florbetapir based on the currently available data (13-3); but voted unanimously (16-0) to recommend approval of Amyvid conditional on a reader training program that demonstrates reader accuracy and consistency through a re-read of previously acquired scans

Lilly acquired Avid Radiopharmaceuticals, which developed Amyvid, in December 2010. Amyvid was the first beta-amyloid imaging compound to enter multicenter, investigational new drug clinical studies in the U.S. Amyvid was recently assigned priority review designation by the FDA.