[Oncolytic virus therapy for malignant brain tumors].
Department of Neurosurgery and Translational Research Center, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyoku, Tokyo 113 8655, Japan.
Oncolytic viruses are genetically engineered, recombinant viruses or naturally occurring, attenuated viruses that infect, replicate selectively within, and destroy tumor cells. These viruses are nontoxic to normal tissues, and progeny viruses released from destroyed tumor cells can spread and infect surrounding tumor cells. In addition, most oncolytic viruses can elicit specific antitumor immunity in the course of tumor cell destruction. Currently, the main route of virus administration is direct intratumoral injection that enables maximum virus delivery to tumor cells and minimum systemic adverse events. Several types of oncolytic viruses have been tested in clinical trials for recurrent malignant glioma, among which genetically engineered herpes simplex viruses type 1 seems to be the most promising because of its high tumor selectivity (indicating safety) and potency (indicating efficacy). Oncolytic virus therapy has been developed for various types of cancers other than glioma, including malignant melanoma and prostate, breast, head & neck and colon cancers. Thus far, oncolytic viruses that are inoculated intratumorally, are shown to be safe; adverse events typically observed are usually transient and include local inflammation and flu-like symptoms. Oncolytic viruses can be used in combination with chemotherapy or other conventional therapies, which, in some cases, can lead to synergistic effects. This review summarizes the recent advances in clinical and preclinical research on oncolytic virus therapy for malignant brain tumors.