HIV drugs also inhibit retrovirus linked to prostate cancer

Some drugs, known to fight HIV, also inhibit a retrovirus recently linked to prostate cancer and chronic fatigue syndrome (CFS), according to a new study from University of Utah and Emory University/Veterans Affair Medical Center (VA) researchers.

The finding means that if the retrovirus XMRV (Xenotropic murine leukemia virus-related virus) is proved to cause prostate cancer or CFS, it is possible that those two illnesses might one day be treatable with drugs aimed at HIV.

"These results offer hope to infected persons, but we are still at the early stages of our understanding of the potential link between XMRV and these diseases. Not all studies that have looked for XMRV have been able to detect it in prostate cancers or in samples from chronic fatigue syndrome. Even if XMRV is established to be the cause of prostate cancer or chronic fatigue syndrome, we will need to see the results of clinical trials before these drugs can be used in a clinical setting. We, along with other investigators, are working as hard as we possibly can to get to that point, but it is important to caution patients that we are not there yet," said Dr Ila R Singh.

The researchers tested 45 compounds used to treat HIV and other viral infections to see how effectively they worked against XMRV in cultured human breast cancer and prostate cancer cells.

The most potent drug at inhibiting XMRV was raltegravir, made and marketed to treat HIV by Merck & Co, which inhibited XMRV replication in cultured cells at concentrations known to inhibit HIV in humans.

Three other drugs, L-00870812, Zidovudine (ZDV or AZT), and tenofovir disoproxil fumarate (TDF), also effectively prevented virus replication.

"Our study showed that these drugs inhibited XMRV at lower concentrations when two of them were used together, suggesting that possible highly potent 'cocktail' therapies might inhibit the virus from replicating and spreading. This combination of therapies might also have the added benefit of delaying or even preventing the virus from mutating into forms that are drug-resistant," said co-investigator Raymond F Schinazi.

Currently, the researchers are investigating the development of viral resistance to raltegravir and other active drugs.

The study has been published in PLoS One.