The agreement, worth up to $1.4 billion, focuses on immuno-oncology drugs.

A new strategic collaboration in the area of immuno-oncology will focus on the development of bispecific antibody constructs. Amgen and California-based CytomX Therapeutics will co-develop CytomX Probody T-cell-engaging bispecific antibody construct against the epidermal growth factor receptor (EGFR), a target expressed on multiple human cancer types.

Probody T-cell engaging bispecifics are antibody constructs capable of directing cytotoxic T-cells in tumor microenvironments, according to the press statement. “In preclinical studies, CytomX's Probody versions of EGFRxCD3 bispecific therapeutics induced tumor regressions and increased the therapeutic window for this high potential cancer target,” the companies noted.

The deal is valued up to $1.4 billion. CytomX will be responsible for early development efforts, and Amgen will head up the later development and commercialization stages. Both companies will share the global late-stage development costs. CytomX will receive a $40 million upfront payment from Amgen, which will also purchase $20 million of CytomX common stock. Amgen will pay CytomX up to an additional $455 million if it reaches development, regulatory and commercial milestones. Amgen will commercialize and approve product on a global basis, and CytomX may opt into profit share in the US and receive tiered, double-digit royalties on net product sales outside of the US.

Also as part of the collaboration, Amgen has the exclusive worldwide rights to develop and commercialize up to three additional, undisclosed targets. If Amgen chooses to pursue all three, CytomX could receive up to an additional $950 million in upfront and milestone payments and high single-digit to mid-double digit royalty payments on any resulting products.

CytomX, meanwhile, will receive rights from Amgen to an undisclosed preclinical T-cell engaging bispecific program for which is will pay Amgen milestone and royalty payments on any products that are commercialized.

"Probody-based T-cell engaging bispecific antibodies offer significant potential in treating cancers by employing localized therapeutic activity within tumor tissue," said Sean McCarthy, D.Phil., President and Chief Executive Officer of CytomX Therapeutics. "Through this collaboration, we are positioned to combine Amgen's industry-leading expertise in leveraging bispecifics to activate a patient's immune-system with CytomX's ability to design potent new therapies that exploit unique conditions in the tumor microenvironment. Development of Probody-based T-cell engaging bispecifics further validates the broad applicability of the Probody platform in addressing unmet needs in oncology."

Added Sean E. Harper, M.D., Executive Vice President of Research and Development at Amgen: "Our collaboration with CytomX leverages Amgen's development leadership in bispecifics and expands our immuno-oncology capabilities with an additional and complementary bispecific technology. EGFR is a particularly compelling target on which to employ the CytomX Probody platform given its potential to localize activity within tumors while limiting potential toxicity."