Biogen Alzheimer's approval could open the door for other similar drugs

The story of Biogen's new Alzheimer's drug can be linked back to a nearly forgotten experimental compound developed by two companies that no longer exist.

In 2006, drugmakers Elan and Wyeth began a Phase 1 study of an antibody drug called bapineuzumab that worked similarly to Biogen's. Both bind to and remove a protein called amyloid beta that piles up into toxic plaques in the brains of patients with Alzheimer's disease.