Amgen Inc. today announced that it has entered into a strategic collaboration in immune-oncology with CytomX Therapeutics Inc. in San Francisco.

The Thousand Oaks biotech will co-develop CytomX Probody, which can direct cytotoxic T cells, a type of white blood cell that kills cancer, in tumor microenvironments. According to Amgen, the preclinical studies have proved that the CytomX Probody have induced tumor regressions.

Under the agreement, Amgen will lead later development and commercialization. The company will make upfront payment of $40 million and purchase $20 million of CytomX common stock. CytomX will be eligible to receive up to $455 million in development, regulatory and commercial milestones.

“Our collaboration with CytomX leverages Amgen’s development leadership in bispecifics and expands our immuno-oncology capabilities with an additional and complementary bispecific technology,” Sean Harper, executive vice president of research and development at Amgen, said in a statement.

The announcement was made after the market closed on Tuesday. Shares of Amgen (AMGN) closed up 6 cents, or less than a percent, at $187.23 on the Nasdaq.