Eli Lilly and Company has acquired two investigational positron emission tomography (PET) tracers from Siemens Medical Solutions USA, Inc. The tracers are intended to image tau (or neurofibrillary) tangles in the brain, one of two known hallmarks of Alzheimer's disease.

Based on studies of samples obtained at autopsy, the amount and location of tau tangles in an Alzheimer's disease patient's brain is thought to correlate with the severity of the disease. There are currently no approved diagnostics to detect tau tangles in living patients, creating challenges for scientists working to understand the progression of the disease and how therapies may impact it.

Lilly will initially focus on incorporating this new technology into its anti-amyloid and anti-tau research and development (R&D) programmes. Use of a tau tangle tracer could enable tailoring and early identification of at-risk patients, as well as potentially provide a marker for treatment response.

Lilly also has the option to commercialize the tracers. The tracers will be developed and validated by a team at Avid Radiopharmaceuticals, Lilly's wholly owned subsidiary focused on molecular imaging.

Financial terms of the deal are not being disclosed.

"The acquisition of these tau tangle tracers builds on our 25-year commitment of investing in Alzheimer's disease research and development to bring new medicines to patients facing the terrible consequences of Alzheimer's disease," said Jan M Lundberg, Ph.D., executive vice president, science and technology, and president, Lilly Research Laboratories. "We are hopeful that this technology will both enhance our understanding of tau and its role in Alzheimer's disease, and contribute to the development of our anti-amyloid and anti-tau based therapies to treat this disease."

"PET imaging is a valuable tool in the fight against Alzheimer's disease, and Siemens is committed to helping fight this growing threat to our aging population," said James Williams, CEO, Siemens Molecular Imaging business unit. "Lilly's continued development of these tau PET tracers combined with Siemens' ongoing investment in innovative PET imaging solutions is another great example of how Siemens is collaborating with pharmaceutical companies in an effort to provide new hope to patients and their families."

There are two defining pathologies linked to the development of Alzheimer's disease: the accumulation of amyloid-beta protein that forms beta-amyloid plaques outside of neurons, and the accumulation of tau protein that forms tau tangles inside them.The formation of tau tangles is thought to block the transport of nutrients and essential molecules throughout the cell, leading to neurodegeneration, or the progressive loss of structure or function of neurons. The formation of tau tangles mostly occurs after beta-amyloid plaques have developed, but unlike beta-amyloid plaques the evolution of tau tangle pathology is believed to closely mirror cognitive decline.

Scientists theorize that both beta-amyloid plaques and tau tangles are required for the development of Alzheimer's disease, with the accumulation of amyloid beta representing the early trigger that initiates the disease process and tau tangles playing a secondary but critical role in the process of neuronal toxicity and death. For this reason, Lilly has established R&D programmes to explore both the amyloid and tau hypotheses. Today's acquisition will inform and help progress Lilly's multiple approaches to treating Alzheimer's disease, with the goal of speeding innovation to patients worldwide.

Lilly, a leading innovation-driven corporation, is developing a growing portfolio of pharmaceutical products by applying the latest research from its own worldwide laboratories and from collaborations with eminent scientific organisations.