* Agents designed to detect tau tangles in brain
* Agents will be used first to test Alzheimer's drugs-Lilly exec
CHICAGO, April 17 (Reuters) - In a move to shore up its lead in Alzheimer's diagnostics, Eli Lilly and Co on Wednesday said it will acquire two imaging agents from Siemens designed to light up brain deposits of tau, an Alzheimer's protein linked with cell death.
The two agents are radiopharmaceutical tracers, which are used with positron emission tomography, or PET scans, to highlight specific proteins in the brain. Terms of the deal with the conglomerate's Siemens Medical Solutions USA unit were not disclosed.
In April 2012, Lilly became the first company to win U.S. marketing approval for use of its radioactive tracer known as Amyvid to detect the presence of brain plaques made up of the protein beta amyloid, an early sign of Alzheimer's disease.
The deal with Siemens follows the announcement last April of a research collaboration between General Electric Co's GE Healthcare Medical Diagnostics business and Clino Ltd, a venture of Japan's Tohoku University, to develop imaging tracers that can identify the presence of tau proteins in people with Alzheimer's.
Like the GE deal, the goal of Lilly's acquisition is to develop imaging agents that speed the development of effective treatments for Alzheimer's.
Lilly said it plans to use the new technology first in its Alzheimer's drug research and development programs. The company also has the option to commercialize the tracers, which are meant to be used with PET scanners.
There are currently no approved diagnostics that can detect tau in living patients, which makes research difficult. Typically detected during an autopsy, tau is known for forming tangles inside brain cells. The protein is believed to develop later in the progression of Alzheimer's, when the disease has begun to kill off brain cells.
Because the presence of tau often signals the advance of Alzheimer's in the brain, Dan Skovronsky, chief executive of Avid Radiopharmaceuticals, Lilly's wholly owned subsidiary focused on molecular imaging, sees the compounds as a potential way of measuring whether an experimental treatment is working.
"It could answer one of the major unmet needs in Alzheimer's disease, which is a marker for disease progression and treatment response," Skovronsky said in an interview.
While amyloid accumulates early in Alzheimer's and then remains stable, autopsy studies suggest that tau increases as symptoms get worse, he said.
Skovronsky envisions using tau tangles as a surrogate marker for disease progression, in much the same way that cholesterol buildup in the arteries is used as a marker for heart disease.
"It's early and we don't know if that would work or not, but that is a pretty exciting hope," said Skovronsky, whose team is charged with validating and developing the tracers.
So far, no drug has been found to prevent the advance of Alzheimer's, the leading cause of dementia that now affects some 5 million Americans and 38 million people worldwide.
Lilly is developing a number of experimental Alzheimer's treatments, including solanezumab, which is now being tested in a number of trials among patients with very early Alzheimer's.