Pharmaceutical giant Daiichi Sankyo Co. said Tuesday it has reached an agreement to wholly acquire Plexxikon Inc., a California-based drugmaker, for $805 million (about ¥66 billion) to strengthen its research and development of cancer drugs.

The two companies have also agreed that Daiichi Sankyo will pay up to $130 million to the U.S. firm if Plexxikon succeeds in commercializing a late-stage oncology drug currently undergoing clinical tests, meaning the buyout price could total ¥76.6 billion.

Established in 2001, Plexxikon has about 45 employees and engages mainly in development of drugs for cancer, inflammatory disorders, and heart and kidney illnesses. It has been jointly working on R&D with Roche Holding Ltd. of Switzerland.