Persistence of oncolytic Coxsackie virus A7 in subcutaneous human glioblastoma xenografts in mice in the context of experimental therapy
Natural non-pathogenic and vaccine strains of human enteroviruses are currently considered as promising agents capable of treating various kinds of cancer, including glioblastoma multiforme, the most aggressive brain tumor with so far no effective therapy. Enteroviruses can selectively replicate in cancer cells and cause tumor lysis. However, the ability of enteroviruses to persist in tumor tissue for a long period of time and to replicate in several successive cycles while spreading from cell to cell remains largely unclear. This study aimed to determine the possibility of completely destroying subcutaneous mouse xenografts of human glioblastomas through a single intravenous administration of virus-carrying peripheral blood leukocytes, as well as to find out the duration of persistence of the virus in the body of experimental animals in the context of viral therapy. Neurospheres were formed in vitro by incubating fragments of patients-derived glioblastomas and used to initiate subcutaneous tumors in immunodeficient mice. It was established that human peripheral blood leukocytes infected in vitro can effectively deliver Coxsackie A7 virus to the tumor cells. A single injection of 2 × 104 virus-infected leukocytes led to a gradual regression of tumors, while the virus presence was constantly detectable in the blood of mice, up to the complete regression of the tumors. The study allows to make the conclusion that blood leukocytes can effectively deliver Coxsackie A7 virus to the tumor. In the absence of a full-fledged immune response in mice, the viruses persist in tumors leading to their complete destruction.