Abstract
Despite recent advances in surgical techniques, chemotherapy and radiotherapy, the poor prognoses of malignant glioma patients have not changed in the past decades. The use of oncolytic viruses is a promising new strategy for treating cancer including malignant glioma. The basic concept of oncolytic virus therapy is to kill the tumor cells via infection with replication-competent viruses such as herpes simplex virus. This concept, however, was not practical until the recent progress in genetic engineering enabled a manipulation of the viral genome to restrict the virus replication to tumor cells. Oncolytic viruses can also serve as vectors that can provide an amplified transgene delivery within the tumor. Multiple oncolytic virus vectors have been tested in clinical trials for malignant gliomas, most by direct intratumoral administration, the results of which have demonstrated the feasibility and potential of this therapeutic approach. The efficacy of oncolytic virus therapy may be enhanced by combining it with other adjuvant therapies. There remain problems to be solved which include how to obtain maximum delivery of the virus to tumor cells via systemic administration without losing a substantial amount by attachment to the vessel wall, hemodilution, filtration in the liver, and inability to pass the blood-brain barrier. Nonetheless, the development of oncolytic virus therapy may lead to a breakthrough in the treatment for malignant gliomas.
