AstraZeneca will expand its collaboration with Eli Lilly to develop an experimental Alzheimer's drug, sticking with an approach that has been a mainstay of research despite recent setbacks.

Astra said it would team up with Lilly to develop a drug known as MEDI1814, currently being tested on humans in the first stage of development. It is designed to prevent a protein called beta amyloid from forming plaques in the brain, which is believed to play a pivotal role in Alzheimer's.

Last month, the failure of Lilly's experimental drug solanezumab to slow cognitive decline cast doubt on this approach to fighting the debilitating disease.

Astra said it was exploring promising new avenues within the amyloid beta pathway.

"MEDI1814 has a unique mechanism among antibodies in clinical development and could provide a distinct approach to treating Alzheimer's disease," Mene Pangalos, an Executive Vice President at the British group said in a statement.

The two companies are already working together on late-stage trials in a different class of Alzheimer's drugs called BACE inhibitors, which are given as pills and work differently to block beta amyloid production.

Merck & Co is currently viewed as in the lead in the BACE inhibitor race with its product verubecestat.

Other companies with antibody treatments targeting beta amyloid in development include Biogen and Roche, which has a tie-up with biotech firm AC Immune.

Currently approved drugs only ease some of the symptoms of Alzheimer's and any treatment that successfully interferes with the cause of the disease would be virtually guaranteed multi-billion dollar annual sales, industry analysts have said.