Cancer Drugs Force HIV to Mutate to Death- Voice of America News (08.24.10):: Joe DeCapua

Existing drugs approved to treat cancer and tested for anti-HIV activity proved potent in a new study, researchers report. After treatment, HIV mutated itself to death - and did so fairly quickly.
"Well, we were specifically looking for drugs that had already been approved by the [Food and Drug Administration] for other purposes," said study co-author professor Louis Mansky, director of the Institute for Molecular Virology at the University of Minnesota. "And we were screening to look for ones that may have been overlooked in the past for anti-HIV activity."
"HIV has this propensity for rapidly mutating and evolving," Mansky said. "And this is really in a lot of ways the main reason why there hasn't been an effective vaccine developed and why there's continual problems with drug resistance."
With a combination of cancer drugs decitabine and gemcitabine, Mansky and colleagues reported they were able to reduce HIV infectivity in tissue samples by 73 percent, though at concentrations that showed minimal antiviral activity when each drug was used alone. "Decreased infectivity coincided with a significant increase in mutation frequency and a shift in the HIV mutation spectrum," they reported.
"The drugs do not directly inhibit the virus from replicating," Mansky said. "What they do is to basically cause the virus to elevate its mutation rate. And through that process, allow it to continue to replicate and basically kill off its infectivity by this process of lethal mutagenesis, which is elevating the mutation rate to the point where the virus is no longer infectious."
Further research will involve animal studies, Mansky said, and proving that the drugs are not only efficacious but also safe. In addition, the cancer drugs, which are given intravenously, would need to be formulated as a pill.
The full study, "Exploiting Drug Repositioning for Discovery of a Novel HIV Combination Therapy," was published in the Journal of Virology (2010;84(18):9301-9309).