Chemotherapeutic elimination (green) of the tumor is a complex challenge. Mathematical modeling of tumor-immune interactions reveals that optimal therapy, which may initially seem black and white, requires delicate navigation through a complex multidimensional landscape personalized to each patient. Cytotoxic efficacy (purple) must be balanced with supporting patient antitumor immune responses stimulated by lymphodepletion (blue). Optimal therapy treads an intermediate path (gold) that maintains dosing within a maximally effective window. The authors acknowledge the help of Dr. Chandler D. Gatenbee who provided coding expertise on the coloring for the image. For details, see article by Park and colleagues on page 5302.