Regeneron and CytomX have extended their cancer therapy partnership to a $4 billion deal. The collaboration combines CytomX’s Probody technology with Regeneron’s Veloci-Bi platform to develop conditionally active bispecific antibodies for hard-to-treat tumors. Under the new terms, Regeneron funds all activities, while CytomX receives a $37 million nomination payment for two targets, with options for six more, plus royalties and milestones.