Amgen Inc. announced Wednesday that it has entered into an exclusive contract with Tokyo-based pharmaceutical company Daiichi Sankyo Co. Ltd. to commercialize nine biosimilar drugs in Japan. Under the terms of the deal, the Thousand Oaks biotech will develop and manufacture the biosimilars, and Daiichi Sankyo will be in charge of distribution and sales. Amgen will have limited ability to co-promote the drugs in Japan during the span of the agreement but will maintain its distribution and commercialization rights outside of the country. Financial terms of the deal were not disclosed. “Amgen is excited to collaborate with Daiichi Sankyo as we seek to drive adoption and build confidence in biosimilars as a means of enhancing patient access to more affordable therapeutic options worldwide.” Scott Foraker, Amgen’s vice president and general manager of biosimilars, said in a statement. Biosimilars are drugs that are highly comparable to their original bioengineered counterparts but can’t be exact replicas as they are manufactured in living cells. The contract encompasses several biosimilars in late-stage development, including one for arthritis medication Humira, which generated over $14 billion in sales last year. Amgen shares closed up $2.22, or 1.4 percent, to $162.74 on the Nasdaq.