PDCD1 and cancer: Monoclonal α-PD-1 antibodies are approved for use in humans against many cancers, including melanoma, lung cancer, and renal cell carcinoma.28–30 The prospect of blocking the PD-1/PD-L1 axis to functionally restore exhausted HBV-specific T cells is supported by studies showing significantly more proliferation and higher IFN-γ secretion among HBV-specific T cells expanded in vitro.13,31,32 The first clinical use of α-PD-1 antibodies in patients with CHB led to a decline in HBsAg serum levels of ≥0.5 log10 among 3/12 patients, with a single patient achieving total HBsAg loss.33