Clinical Progress in Virotherapy: Application and Future Prospects in Head and Neck Cancer

Virus-based cancer therapy (virotherapy) is currently being researched as a novel form of immunotherapy and has already entered the clinical application phase. Among various types of virotherapy, oncolytic virotherapy involves infecting tumors with tumor-selective viruses, such as herpes simplex virus, adenoviruses, and vaccinia virus, and utilizing their replicative capacity to induce cell destruction within tumors. In addition, this therapy aims to enhance tumor immunity by changing the tumor microenvironment through viral infection. Genetic deletion in viruses is used to reduce their virulence and confer tumor selectivity, while the expression of foreign genes is utilized to enhance antitumor effects. Oncolytic viruses for head and neck cancer (HNC) are administered locally or systemically and are sometimes used as adjuvant therapy or in combination with immune checkpoint inhibitors. Another form of virotherapy involves non-replicating viruses, which are used to produce antitumor cytokines or as cancer vaccines expressing tumor antigens. Research on the efficacy of cancer vaccines in preventing postoperative recurrence is currently underway. A number of challenges have yet to be overcome for further advances in virotherapy, including the efficient delivery of viruses to tumor cells, avoiding viral inactivation in the bloodstream, ensuring efficient replication of the virus, and enhancing antitumor immunity. The development of effective strategies based on the findings of clinical studies will lead to improvements in virotherapy for HNC.