Thousand Oaks biotech giant Amgen has upped its investment in Chinese oncology research firm BeiGene by $421 million.

Amgen’s new investment, announced July 13, will allow the company maintain its ownership interest in BeiGene at 20.3 percent following a direct offering by the Chinese firm.

Amgen shares rose more than 1 percent following the news to $251.32, staying near 52-week highs set the prior week.

The investment builds on a $2.8 billion deal that closed in January, in which BeiGene agreed to contribute $1.25 billion to bring 20 oncology treatments from Amgen’s pipeline to market. The deal includes rights to commercialize three of Amgen’s products in China, as well bring several others currently in development to market in the country.

Beigene agreed to split profits or losses on the drugs for the first seven years, with another six products to extend for five more years.

“This additional investment reflects Amgen’s confidence in the progress the companies are making in their ongoing oncology collaboration in China, the world’s second largest pharmaceutical market,” Amgen said in a news release.