Fighting HIV with HIV: New Gene Therapy Promising
HIV Gene Therapy
Researchers at the University of Pennsylvania School of Medicine report the first clinical test of a new gene therapy based on a disabled AIDS virus carrying genetic material that inhibits HIV replication. For the first application of the new vector five subjects with chronic HIV infection who had failed to respond to at least two antiretroviral regimens were given a single infusion of their own immune cells that had been genetically modified for HIV resistance.
The researchers, led by Carl June, MD, and Bruce Levine, PhD, of the Abramson Family Cancer Research Institute and the Department of Pathology and Laboratory Medicine, along with Rob Roy MacGregor, MD, Professor of Medicine, report their findings in the online edition of the Proceedings of the National Academy of Sciences. Viral loads of the patients remained stable or decreased during the study, and one subject showed a sustained decrease in viral load. T-cell counts remained steady or increased in four patients during the nine-month trial. Additionally, in four patients, immune function specific to HIV improved.
Overall, the study results are significant, say the researchers, because it is the first demonstration of safety in humans for a lentiviral vector (of which HIV is an example) for any disease. Additionally, the vector, called VRX496, produced encouraging results in some patients where other treatments have failed.
"The goal of this phase I trial was safety and feasibility and the results established that" says June. "But the results also hint at something much more."
Each patient received one infusion of his or her own gene-modified T cells. The target dose was 10 billion cells, which is about 2 to 10 percent of the number of T cells in an average person. The T-cell count was unchanged early after the infusions. "We were able to detect the gene-modified cells for months, and in one or two patients, a year or more later," says Levine. "That's significant