PDCD1 and neoplasm: Application of immune checkpoint inhibition (ICI) such as anti–programmed cell death-protein 1 (PD-1) or PD-L1 with radiotherapy may further improve local and distant tumor control in preclinical models based on a synergistic antitumor effect (Formenti and Demaria 2009; Vanpouille-Box et al. 2017; Alsaab et al. 2017).