Most skin cancer drugs that activate the immune system work by triggering immune cells, called T cells, to attack tumors, but when T cells are activated for too long, they can wear out and cease to function. A new study led by Penn State College of Medicine scientists finds that another type of immune cell—natural killer cells—can be harnessed to pick up the slack when T cells no longer work and may also reinvigorate T cells to attack melanoma tumors. The team has identified a unique combination drug strategy to activate this natural killer cell-mediated immunity in mice. The individual agents are clinically used but not in combination, and the combination still must be demonstrated to be effective in humans.