Combining radiation with immune checkpoint inhibitors therapy for HCC: From the alteration of the immune microenvironment by radiotherapy

Hepatocellular carcinoma (HCC), one of the deadliest cancers all over the world, had a limited prognosis in the past. Recently, the remarkable efficacy of immune checkpoint inhibitors (ICIs) therapy has been shown in various solid tumors. What's more, the occurrence of HCC is associated with immune escape and therefore various ICIs have been applied to clinical trials for HCC. However, the special immune environment of the liver creates the complex tumor microenvironment (TME) of HCC, which impairs the overall survival (OS) and overall response rate (OCR) of ICIs as a monotherapy. Lately, various therapies have been used in combination with ICIs therapy to improve its clinical efficacy. Among which, radiotherapy is widely concerned because of its unique immunoreaction. A large number of basic and clinical studies have demonstrated that the combined radiotherapy and ICIs therapy has advantages in improving the OCR and efficacy, as compared with ICIs therapy alone. Herein, this article reviews the studies on the advantages and possible mechanisms of the combination of radiotherapy and ICIs therapy for HCC.