ATHENS, Ohio -- Scientists at Ohio University and a California-based biotechnology company have used a nonviral gene expression system invented here several years ago to eliminate human cancer cells in animals, achieving a 60 percent tumor regression rate without the potential dangers associated with conventional viral gene therapy techniques.
Scientists in the university's Edison Biotechnology Institute are collaborating on the project with Progenitor Inc., which has licensed the T7 gene expression system used in the studies. If further tests of the method prove as successful as these early studies, scientists could begin human trials in the next year or two.
For the study, scientists used a gene therapy protocol widely used in research of human cancer in animal models: They stimulated cellular expression of a herpes simplex virus-thymidine kinase (HSV-TK) gene in tumors, then treated the tumor-bearing animals with the drug ganciclovir. In their studies, 30 percent of the tumors were permanently eliminated.
While similar tests of the HSV-TK/ganciclovir protocol have suggested it effectively kills cancer cells, previous studies used viral vectors to deliver the HSV-TK gene to the cells. Since viral vectors aren't transient, it's possible the viruses could infect healthy cells and cause mutations that could become part of the genome. For this and other reasons, scientists have been looking for a nonviral delivery system to use with gene therapy treatments, says Xiao Chen, lead author of the study and an assistant professor of clinical research at Ohio University's Edison Biotechnology Institute and College of Osteopathic Medicine.
The work was published in the latest issue of the journal Human Gene Therapy, published March 20.
"Viral gene therapy vectors are very efficient in delivery of
therapeutic genes to certain targeted cells, but there are safety concerns
associated with the viral vectors,"
Contact: Kelli Whitlock