Eisai and Biogen Idec have teamed up to develop and commercialise two of the former's investigational Alzheimer's disease drugs.

The agreement, which also provides Eisai with an option to jointly develop two Biogen candidates for AD, initially will be centered on E2609, a beta-site amyloid precursor protein cleaving enzyme (BACE) inhibitor, and BAN2401, an anti-amyloid beta antibody. Both of the drugs, which are in and are about to enter Phase II, have the potential to reduce amyloid beta plaques that form in the brains of patients with AD and to stop the formation of new plaques, "potentially improving symptoms and suppressing disease progression," the companies said.

Eisai will serve as the operational and regulatory lead in the co-development of the drugs and seek marketing authorisations. In the major markets such as the USA and the European Union, Biogen will co-promote and both companies will share overall costs, including R&D expenses.

Financial terms have not been disclosed but Eisai will bank an upfront fee and a fixed amount of development, approval and commercial milestone payments.

Biogen chief executive George Scangos said the pact is "a natural fit with our mission to develop therapies for patients with severe neurodegenerative diseases". He added that Eisai’s candidates "have demonstrated compelling early data and complement our AD research while extending our pipeline in this critical area".

Eisai developed the AD blockbuster Aricept (donepezil) and chief executive Haruo Naito said that through the collaboration with Biogen, "a company that specializes in neurodegenerative diseases, I believe we will be able to further enhance our existing R&D capacities for developing next-generation AD treatments".