In recent years, immune checkpoint inhibitors have been used in a variety of cancers, including melanoma,16 Hodgkin’s lymphoma17 and lung cancer.18 However, in a recent trial of PD‐1 inhibition in recurrent GBM, only a small proportion of patients showed a response to this treatment.3 PD‐1 blockade is thought to act by disrupting the inhibition of PD‐1+ T cells by inhibitory ligands (i.e. PD‐L1), enabling cytotoxic T‐cell‐mediated tumor cell attack. Here, CD274 is linked to cancer.