Giving periodic infusions of anti-CTLA-4 antibodies to patients with advanced melanoma or ovarian cancer who have been immunized with a GVAX vaccine unleashes a strong immune response to tumors, with less-harsh side effects. Besides demonstrating the potential usefulness of a vaccine-and-antibody approach, the new study suggests a way of refining treatment strategies even further, based on the biological events that antibody treatment sets in motion.