CD274 and neoplasm: The rationale of blocking the PD-1/PD-L1 pathway in these settings is to reduce or eliminate immunosuppressive signals between immune cells and infected or tumor cells.4 The addition of checkpoint inhibitors to in vitro and in vivo models of infectious disease enhances immune activation and reduces viral load.5, 6, 7 On the basis of these results, clinical studies are ongoing using an anti-PD-L1 antibody (NCT02028403) and anti-PD-1 antibody (NCT02408861) in patients with HIV, and an anti-PD-1 antibody in patients with hepatitis C virus (NCT01658878, NCT00703469).