U.S. drugmaker AbbVie is betting on the potential of the body's immune system to fight Alzheimer's by signing a drug development deal worth more than $200 million with unlisted biotech company Alector.

AbbVie said on Tuesday it was paying $205 million upfront and could make a further $20 million equity investment to work with San Francisco-based Alector on the new approach to tackling the memory-robbing disease.

The idea of using immunotherapy in Alzheimer's mirrors the success of immuno-oncology in cancer, where drugs that help the immune system battle tumours are revolutionizing care.

Scientists at AbbVie and Alector believe there is growing evidence that immune deficiencies within the central nervous system play an important role in the progression of neurodegenerative disorders like Alzheimer's.

"We anticipate that immuno-neurology therapies will have as much of an impact on brain disorders as immuno-oncology is having on cancer," said Alector's chief executive, Arnon Rosenthal.

The novel research effort comes against the backdrop of a series of failures in other attempts to fight Alzheimer's, although the development of immune-based treatments is still at a very early stage.

Under the terms of the agreement AbbVie and Alector have agreed to research a portfolio of antibody targets and AbbVie has an option on global development and commercial rights to two targets.

Assuming drugs from the program eventually make it to market, the two companies will share profits equally.

Alector was founded in 2013 and is backed by investors including OrbiMed, Polaris, Google Ventures, Topspin Partners and Mission Bay Capital, as well as drugmakers Merck, AbbVie and Amgen.

This article was provided by Reuters.