PDCD1 and cancer: Inhibition of the PDCD1/PD-L pathway has already been shown to have substantial therapeutic efficacy and a good safety profile in relapsed or refractory Hodgkin Lymphoma (Ansell et al, 2015), advanced melanoma (Wolchok et al, 2013) and other advanced cancers, including non–small-cell lung cancer and renal-cell cancer (Brahmer et al, 2012), and an inhibitory PDCD1 antibody has recently gained US Food and Drug Administration approval for patients with advanced or unresectable melanoma (Momtaz & Postow, 2014).