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A Mayo Clinic research team has devised a new virus-based gene therapy delivery system to help fight cancer.
The approach relies on 'therapeutic hitchhikers', particles derived from retroviruses (ribonucleaic acid-containing viruses that incorporate into the genomes of infected cells and then produce a therapeutic gene).
The viral particles attach to a specific kind of T-cell in the immune system and 'hitchhike' to the tumor because T-cells home in on tumors naturally; T-cells are the immune system's major line of defense against tumors.
By hitching a ride on the T-cells, the therapeutic particles can hit their tumor target while avoiding detection (and destruction) by the immune system. When the Mayo team experimented with the hitchhiking approach in mice using human and mouse cancer cells, they observed significant cure rates of metastatic - or spreading - tumors.
"Any clinical situation in which cells home to disease sites - such as inflammation or autoimmune disease - might benefit from this approach,"
"Our work is an important contribution to the maturation of the field of gene therapy because ultimately treating cancers by gene therapy depends on scientists' ability to specifically target tumor cells in the patient and this specific-delivery feature has eluded researchers for a variety of reasons. But by devising a way for viruses to hitch rides on antigen-specific T-cells, we've been able to get over multiple obstacles to gene therapy," he said.
The Mayo investigators have invented a simpler method for using modified viruses to transport therapeutic genes to tumors. They are the first to exploit traits of retroviruses during the infection process of a cell in which attachment to the cell can occur in a nonspecific way.
This opens up new opportunities for using viruses therapeutically because this method of attachment allows researchers not only to target particular cells, but also to more easily gain entry into the cells, which they must do to deliver therapeutic genes to destroy tumors. The T-cells also help kill tumors.