PDCD1 and cancer: Recently, the growing application of ICIs such as programmed cell death protein 1/programmed cell death 1 ligand 1 (PD-1/PD-L1) and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) inhibitors in treating various cancers has brought attention to HBV reactivation due to the immune balance disruption caused by these therapies (Shiravand et al., 2022; Lasagna et al., 2021; Godbert et al., 2021).