Amgen Inc. on Wednesday said that it plans to expand its presence in the Japanese market through a joint venture with Tokyo's Astellas Pharma Inc., which itself has a strong presence in the Los Angeles area.

The Thousand Oaks biotech giant recently signed a similar partnership 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.

Astellas Pharma, which is Japan's second largest drug company, 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 a half billion dollars at the time. Astellas has since expanded Agensys operations here.

In this new deal, Amgen and Astellas will work together to develop and commercialize five drugs in Amgen’s pipeline. Those include treatments for cardiovascular, bone disease and cancer.

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

In addition to drug development, the companies are creating a joint venture company in Tokyo to establish facilities within the country. It will be staffed by Amgen and Astellas employees, and will eventually become a wholly-owned Amgen subsidiary.

Financial details of the deal were not disclosed.

The Chinese joint venture was announced earlier this month with Zhejiang Beta Co. Ltd., of Zhejiang. It will distribute Vectibix, a metastatic colorectal cancer treatment, in China.

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

Shares of Amgen closed down $1.81, or 2 percent, to $104.39 on the Nasdaq.