ii) PD-1 blockade may promote the proliferation of T regulatory cells (Tregs) (41) and myeloid-derived suppressor cells (MDSCs) (42), increasing immuno-suppression and then the reactivation of HBV; iii) MDSC levels were considered as a novel biomarker for related immune dysfunction, such as irAEs (43), and inflammatory Treg reprogramming was suggested a feature of immunotherapy-induced irAEs (44), this may explain that irAEs occurrence was a risk factor for HBVr. Here, PDCD1 is linked to immune system disorder.