Amgen Inc. will expand its reach in the Japanese market through a joint venture with Tokyo firm Astellas Pharma Inc., the company said Wednesday.

The Thousand Oaks biopharmaceutical giant and Astellas will work together to develop and commercialize five drugs already in Amgen’s pipeline. Those include cardiovascular, bone disease and cancer treatments

Astellas is Japan's second largest drug company and gained a presence in Southern California when it acquired Santa Monica cancer drug developer Agensys Inc. in 2007, a deal that was valued at nearly $500 million at the time. Astellas has since expanded Agensys operations here.

In addition to drug development, Amgen and Astellas are creating a joint venture company in Tokyo to establish facilities within the country. It will be staffed by employees from both companies, and will eventually become a wholly-owned Amgen subsidiary. Financial details were not disclosed.

“This alliance will help accelerate development and commercialization of Amgen medicines for patients in Japan,” said Amgen Chief Executive Robert Bradway in a statement.

Earlier this month, Amgen signed a similar agreement with a Chinese firm and executives have said at recent investors meetings that they were looking at ways to expand the company’s presence in Asian markets.

The Chinese joint venture is with Zhejiang Beta Co. Ltd. of Zhejiang. It will distribute Vectibix, a metastatic colorectal cancer treatment, in China.

Additionally, Amgen is building a $200 million manufacturing facility in Singapore.

Shares of Amgen lost $1.81, or nearly 2 percent, to close at $104.39 on the Nasdaq.