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It seems it is only a matter of time before Eli Lilly’s (NYSE:LLY) newly-acquired Alzheimer’s disease diagnostic, florbetapir, wins FDA approval. The outcome of Thursday’s advisory committee review certainly indicated the panel of experts were convinced of its ultimate potential.

However, despite Alzheimer’s research attracting huge amounts of attention and research dollars, Lilly’s purchase of florbetapir last November and its subsequent regulatory progress has not piqued much interest, from the financial community at least. This is possibly because disease-modifying Alzheimer’s drugs are not available, and are likely to be years away from the market. Considering florbetapir’s most important role, for now at least, could be as an imaging tool to help get these drugs to market, a definitive rubber stamp from regulators is actually pretty important.

Binding plaques

Florbetapir, also known as AV-45 and which Eli Lilly has branded Amyvid, is an imaging agent which binds to the characteristic beta-amyloid plaques found in the brains of Alzheimer’s patients. This essentially dyes the plaques, which can then be seen on a PET scan.

Rather than resulting in an Alzheimer’s diagnosis, Amyvid will help doctors rule out the degenerative brain disease. For although there is much differing opinion on the role the beta-amyloid plaques actually play in causing the disease and its progression, their presence is widely believed to be a hallmark.

As such, if these protein tangles do not show up on a scan, Alzheimer’s can be ruled out as a reason for dementia.

Analyzing the brain scans was always going to be the tricky part, and this indeed is what caused the FDA’s experts to withhold support at this stage. They voted 13 to 3 against approval at this stage, saying interpretation of the scans was inconsistent, and a proper training program needed.

However, they unanimously said the tool should be made available if Lilly can show interpretation of the data can be improved (Event – Eli Lilly’s breakthrough Alzheimer’s diagnostic awaits adcom recommendation, January 12, 2011).

Dedication

Lilly paid $300m for Avid Radiopharmaceuticals, the maker of Amyvid, last year, and will pay what is likely to be a chunky milestone on approval (Eli Lilly snaps up leading Alzheimer's diagnostic, November 8, 2010). Although a complete response letter is now likely, due by the end of April, Lilly is likely to push on quickly with attempts to appease the FDA.

Access to PET scanners is limited, and with the cost of a scan already around $6,000, adding Amyvid to the process does not make for a cheap diagnostic tool. This will hamper uptake, particularly while treatment options for dementias remain limited, especially for early stages of the disease. Analysts covering Eli Lilly do not appear to have assigned any sales to the product yet.

Amyvid, and other Alzheimer’s and dementia diagnostics, will really come into their own when therapies become available and early diagnosis becomes more important, although it is possible that simpler tools will be available by then, blood tests for example.

In the meantime, with a lot of research into therapies that target beta-amyloid, Amyvid could well find an important role in clinical trials. Eli Lilly has one of the most advanced agents pursuing this avenue, solanezumab, which breaks up the beta-amyloid clumps. Amyvid should be able to track this happening.

It will be interesting to see how FDA endorsement of an Alzheimer’s imaging agent, should it come, helps steer the direction of beta-amyloid research.

Source: Eli Lilly's Alzheimer's Diagnostic Steps Closer to Market