Checkpoint inhibitors of PD-1/PD-L1 show activity as a single agent, though with response rates of less than 20%, cures occurring in less than 5% of patients in most indications and somewhat increased responsiveness in select indications, such as melanoma, microsatellite instability-high tumors, and Hodgkin’s disease [9]. The gene discussed is PDCD1; the disease is melanoma.