Japan’s Eisai and US based Biogen announced the expansion  of their existing collaboration agreement to develop and commercialise investigational therapies for Alzheimer’s Disease. As per the terms, the expanded deal leverages each company's geographic strengths for commercialisation and also adjusts the respective share of profits from potential sales of the drug.

Under the deal, Biogen will receive 55 percent of the potential profits in the US and 68.5 percent of the potential profits in Europe, and Eisai will receive 80 percent of the potential profits in Japan and Asia (excluding China and South Korea). The companies will have a 50:50 co-promotion split of potential profits in the rest of the world.

Mr Michel Vounatsos, Biogen’s chief executive, said, "Through this new agreement, we believe we have improved our ability to maximize the value of aducanumab and expand the potential reach of our industry-leading multiple sclerosis portfolio. The ongoing collaboration between Biogen and Eisai leverages our respective expertise and strengths in our efforts to bring new treatments to patients and families affected by Alzheimer's disease."

 Biogen will also lead the ongoing Phase III development of aducanumab and will remain solely responsible for all development costs for the drug until April 2018, after which point Eisai will reimburse Biogen for 15 percent of expenses from April 2018 through December 2018, and 45 percent from January 2019 onwards.

The companies will continue to jointly develop elenbecestat (E2609), a beta amyloid cleaving enzyme (BACE) inhibitor, and BAN2401, while the firm also announced an agreement to co-promote Biogen's multiple sclerosis treatments, Avonex (interferon beta-1a), Tysabri (natalizumab) and Tecfidera (dimethyl fumarate) in Japan to certain accounts.

Additionally, Eisai and Biogen have agreed to co-promote Biogen's multiple sclerosis (MS) treatments, AVONEX (interferon beta-1a), TYSABRI (natalizumab) and TECFIDERA (dimethyl fumarate) in Japan to those accounts that Biogen currently does not call upon.

Eisai will also distribute and book sales for AVONEX, TYSABRI, TECFIDERA and PLEGRIDY® (peginterferon beta-1a) in India and other Asia-Pacific markets (excluding China).

Eisai CEO Haruo Naito commented, “Genetic epidemiological studies such as the Icelandic genetic research as well as the knowledge recently gained from various clinical studies such as the aducanumab Phase 1b trial have deepened our conviction in the amyloid hypothesis. We hope to establish a new treatment paradigm for fighting dementia by expanding the strategic collaboration between Biogen, a company that leverages its cutting-edge bio-technology to develop innovative therapies for people living with serious neurological and neurodegenerative diseases, and Eisai, a company which possesses a rich pipeline based on holistic approaches. In accordance with this new paradigm, we plan to further co-develop the collaboration products and hope to advance the world's potentially first new treatment for Alzheimer's disease based on the amyloid hypothesis. Through the collaboration and by leveraging each company's respective strengths in each region, we hope to maximize the benefits for patients and their families.”