Immunotherapy for hepatocellular carcinoma: current status and future perspectives.

The discovery of the immune checkpoint mechanism has contributed greatly to recent advances in cancer treatment. The anticytotoxic T lymphocyte-associated protein 4 antibody ipilimumab was first approved as a therapeutic drug for malignant melanoma in the USA in 2011; since then, antiprogrammed cell death 1 (PD-1) antibody and antiprogrammed death-ligand 1 (PD-L1) antibody have also been approved and clinically introduced and are indicated for the treatment of various cancers. Numerous clinical studies are now underway to evaluate the efficacy of immune checkpoint inhibitors for patients with many kinds of cancer, including hepatocellular carcinoma (HCC), and the outcomes of these trials are highly anticipated. Synergic effects of immune checkpoint inhibitors used in combination with molecular targeted agents or local therapy have also been suggested, resulting in expectations regarding the use of these drugs in combination with existing standard treatment methods for HCC. Thus, the treatment of HCC is now entering an age of significant innovation triggered by the clinical introduction of immune checkpoint inhibitors.