PDCD1 and disease arising from reactivation of latent virus: As the contrainteraction among viruses, cancers, and PD-1/PD-L1 inhibitors remains unclear, physicians shall bear in mind the reactivation of latent infection and opportunistic infection as potential AEs when managing cancer patients with PD-1/PD-L1 blockade, especially for patients from endemic areas (Lee et al., 2016; Reungwetwattana and Adjei, 2016).