FDA approves another Alzheimer's imaging agent with no market in sight

The FDA has approved the second imaging agent that can be used to detect a toxic protein found clustered in the fogged brains of Alzheimer's patients, but there's no guarantee it will ever find much of a market.

The agency approved GE Healthcare's ($GE) Vizamyl (flutemetamol F18 injection), saying that doctors can use it to rule out Alzheimer's if the telltale clusters of beta amyloid are absent. But as the FDA's release notes, it can't be used alone to diagnose the disease--at least until more is known about the role that amyloid plays. Nor does it replace any of the current diagnostic tools now in place.

For Eli Lilly ($LLY), the same limited approval has played havoc with its effort to market Amyvid, the first such imaging agent approved by the FDA. Medicare recently refused to reimburse for the agent, effectively wiping out commercialization plans that are focused almost entirely on older people. Essentially, about the only marketable use for the agent is in clinical trials. Sales of Amyvid have been minuscule. Eli Lilly and other drugmakers are pushing along potential new drugs for Alzheimer's, but the field has delivered one disappointment after the next in recent years.

Navidea Biopharmaceuticals ($NAVB) has a third amyloid beta imaging agent in development. Like Amyvid and Vizamyl, NAV4694 binds to amyloid beta and lights up in a PET scan. The availability of these imaging agents without an amyloid beta drug to use them with--and in the absence of a consensus about the role of the toxic protein in the pathology of the disease--will leave a question mark over their commercial viability.

GE, though, remains upbeat. Merck ($MRK) licensed the agent for use in its studies of the experimental Alzheimer's drug MK-8931, a BACE inhibitor that Merck has been moving into a Phase II/III trial.

"Vizamyl represents a new and important option to augment the current methods we have available to evaluate patients with symptoms of Alzheimer's disease," said William Klunk, co-director of the Alzheimer Disease Research Center, in a GE release. "The ability to detect or exclude the presence of beta amyloid plaques in the brain may help physicians make more accurate assessments of patients with suspected cognitive disorders, including AD."

- here's the FDA's release
- read GE's release