Mehmet Altan from the University of Texas MD Anderson Cancer Center in Houston, USA, and colleagues demonstrated this mutually exclusive pattern of B7-H4 and PD-L1 activity two independent populations—a finding that could explain why drugs designed to boost anti-cancer immunity by blocking PD-1/PD-L1 signaling only work for a fraction of patients with breast cancer. This evidence concerns the gene CD274 and breast carcinoma.