Natural killer cells in hepatocellular carcinoma: current status and perspectives for future immunotherapeutic approaches

Hepatocellular carcinoma (HCC) is currently the fifth most common malignancy and the third leading cause of cancer-related mortalities worldwide. In the last few years, treatments for HCC have significantly improved from a mere surgical resection to a series of minimally invasive therapies and targeted drugs. However, recurrence frequently occurs even upon curative therapeutics, and drug therapies generally produce disappointing results, with the overall prognosis dismal. This challenging clinical scenario warrants new effective and life-prolonging strategies for patients with HCC. Compelling evidence suggests that NK cells play a critical role in the immune function of the liver and in the immune defenses against HCC, indicating that HCC might be an ideal target for NK cell-based immunotherapies. To obtain comprehensive insights into the putative influence of NK cells on HCC, this paper summarizes current knowledge on NK cells in HCC and discusses the usefulness and prospects of NK cell-based immunotherapies. Critical issues that require consideration for the successful clinical translation of NK cell-based therapies are also addressed. If appropriately used and further optimized, NK cell-based therapies could dominate important roles in the future immunotherapeutic market of HCC.