Figure 1.

Irradiation of liver tumors with and without immunotherapy. (a) Liver tumors usually acquire radio-resistance through programmed-death ligand-1 (PD-L1) upregulation after radiation since the PD-L1/ programmed-death-1 (PD-1) axis induces CD8 T-cell exhaustion and results in tumor escape from the host immune response. (b) In order to overcome limitations of PDL1 expression upregulation and to reduce the rate of tumor recurrence in primary liver tumors, an immune-based treatment approach targeting PDL1 or PD-1 might be of help in harnessing an immune response to effectively kill liver tumor cells and reduce the rate of tumor recurrence.