Lilly Banks on Amyloid PET Tracer

Eli Lilly continues to bark up the amyloid tree despite the tepid performance of anti-amyloid drugs* in Alzheimer trials. The Indiana company announced Monday that it is acquiring Avid Radiopharmaceuticals, a Philly-based molecular-imaging firm that owns florbetapir. For a total purchase price of up to $800 million, Lilly will get access to the radiolabelled (18F) tracer for PET imaging.

In recently presented (but not peer-reviewed) phase 3 results, florbetapir was shown to identify amyloid deposits in the brain and differentiate Alzheimer disease from other dementias (eg, frontotemporal dementia) in a small number of patients. According to the Indianapolis Business Journal, Lilly has been using florbetapir as a diagnostic aid in its trials of the anti-amyloid mAb solanezumab and the gamma secretase inhibitor semagacestat. (N.B. Investigation of the latter drug was abandoned by the company in August because of relatively worse cognition with the agent in late-phase AD studies. Phase 3 development of the anti-amyloid mAb solanezumab continues.)

At The Medicine Show blog, Forbes reporter Matthew Herper identifies Lilly's new acquisition as a "smart purchase." "[I]f it really is able to aide [sic] in diagnosing Alzheimer’s the market for it could be big," writes Herper. Points are also given for news that the tracer's marketing application has been submitted to the FDA.

But I'm less sanguine about the the financial outlook for florbetapir. PET imaging, amyloid tracer or no, is unlikely to be used on any kind of grand routine scale for identifying AD. Despite the fact that the condition can only be definitively diagnosed now at autopsy, recognition during life is not difficult, and AD can be clinically and radiographically differentiated from other dementia types without the use of PET imaging. Moreover, although amyloid plaques are generally more extensive in AD than in normal aging, they are not an absolute marker for the illness: At the end of the eight decade of life, up to 80% of normal-aging brains will show amyloid plaques. For the foreseeable future, I see florbetapir only as an adjunct to clinical investigation—which is just how Lilly's been using the agent.

mAb = monoclonal antibody; PET = positron emission tomography.

* Think Pfizer's and JNJ's white-knuckle development of bapineuzumab.

Photograph of atrophied brain from person with AD: National Institute on Alcohol Abuse and Alcoholism.