July 27, 2012
In a tentative first step toward a possible AIDS cure, U.S. researchers have used the cancer drug vorinostat to revive and unmask latent HIV in clinical trial patients' immune cells. The ability of the HIV genome, or reproductive code, to hide out in cells only and revive after decades has posed a major obstacle to a cure. Exposing the virus in its hiding place would allow scientists to target and destroy its host white blood cells: CD4+T cells.
According to David Margolis, co-author of the study, "This is proof of the concept, of the idea that the virus can be specifically targeted in a patient by a drug, and essentially opens up the way for this class of drugs to be studied for use in this way," he said in an interview at the 19th International AIDS Conference.
The eight patients in the clinical trial were also on antiretroviral drugs, which stop HIV from multiplying but have to be taken for life because they do not kill the hidden cells. "After a single dose of the drug, at least for a moment in time, [vorinostat] is flushing the virus out of hiding," Margolis said. It is the first drug to do so.
Although the virus would die without a host cell, Margolis added, "If it is only 99 percent true and 1 percent of the virus escapes, it won't succeed. That is why we have to be careful about our work and what we claim about it."
In published comments, HIV researcher Steven Deeks said that while promising, the study raises ethical concerns about giving potentially toxic drugs to HIV-infected people who are otherwise healthy. Also, HIV immunologist Quentin Sattentau said other types of reservoir cells, including those in the brain, may not respond to this treatment.
[PNU editor's note: The study, "Administration of Vorinostat Disrupts HIV-1 Latency in Patients on Antiretroviral Therapy," was published in Nature (2012;487:482-485).]