When anti-PD-1 antibody (nivolumab) and anti-CTLA4 antibody (ipilimumab) are used together to treat cancer, the combination induced a high response rate with deeper responses than either antibody alone; at the same time, there were higher rates of immune-related toxicities than would be expected with either agent alone [53, 54]. The gene discussed is CTLA4; the disease is cancer.