Bristol-Myers Squibb will give Nektar Therapeutics $1.85 billion up front and potentially another $1.78 billion to jointly develop Nektar’s protein-based cancer immunotherapy NKTR-214. BMS is betting on combining NKTR-214, currently in a Phase I/II trial, with its two approved antibody checkpoint inhibitors, Opdivo and Yervoy. Trials are planned for nine tumor types. NKTR-214 is a prodrug of the immune-system-activating cytokine interleukin-2, already a cancer treatment. The drug binds the interleukin-2 receptor, leading to stimulated immune cells that target tumors.