New Approach to AIDS Therapy Raises Hope for Cure
A new therapeutic approach may help to remove dormant HIV infection that current treatments do not address, according to preliminary findings of a recent study published in the 13 August 2005 issue of The Lancet.
Researchers have found that valproic acid, a drug commonly used to prevent convulsions, can significantly decrease latent AIDS-virus levels within the body. "This finding, though not definitive, suggests that new approaches will allow the cure of HIV in the future," says study co-author David Margolis.
Existing therapies for HIV help to suppress the virus to very low levels. However, they do not eradicate it, as the HIV virus can sequester itself in a latent form inside immune cells. Most current anti-HIV drugs or “antiretrovirals” work to prevent these stored viruses from reactivating, but patients must take the drugs indefinitely for them to be effective. Antiretrovirals are unable to reach dormant HIV viruses.
For a person to be HIV-free – and potentially cured of AIDS – all dormant HIV viruses would have to be eradicated. The recent study is exciting because valproic acid appears to reduce levels of the dormant HIV virus, thus moving one step closer to a cure for AIDS.
Study Protocol and Results
Researchers at the University of Texas gave valproic acid to four patients already taking a combination of standard anti-HIV AIDS drugs, referred to as “highly-active antiretroviral therapy (HAART)”. The dosage of valproic acid was 500-750 mg twice daily in oral doses 16-18 weeks.
At the end of the study, researchers discovered that the number of dormant HIV cells in three patients had dropped by 75%. Also, when treatment ceased, the number of HIV cells rose to previous levels.
Comments
AIDS researcher Jean-Pierre Routy, at McGill University in Montreal, Canada, who did not participate in the study, believes it may be too early to talk about a “cure for HIV”, according to McAlary Reports. However, Routy believes the results show promise, based on their indication that valproic acid has potential to reduce levels of latent HIV virus.
"We can start to attack the virus where it is hiding," reported Routy, according to McAlary Reports. "We can hope one day that we can kill it or remove it from the body or kill the cells infected by the virus. So, yes, it’s a glimpse of hope for sure."
Other scientists cautious about the study’s results include John Siliciano, a Johns Hopkins University physician who in the 1990s helped to discover dormant HIV, reportedly told the Associated Press that, a drug has to kill virtually all cells containing latent HIV virus – not merely 75 percent of them – in order to be useful.
David Ho, an AIDS researcher at Rockefeller University in New York, believes that the finding is only a modest step forward. He noted in an NBC television interview that the test used in the study involved imprecise methods for measuring HIV, therefore the actual drop in cells containing latent HIV latent could be below 75%.
"It [the virus] is extremely difficult to get rid of, so scientists do not want to raise false hope," said Mr. Ho (McAlary Reports). "It’s a very interesting observation, but we have to be cautious to see if this observation could be confirmed."
The researchers involved in the study published in The Lancet are broadening their studies to include larger experimental groups of HIV patients, according to McAlary Reports. They believe that, if their recent findings are confirmed, the HIV virus could be attacked in stages by a variety of drugs, starting with existing combination-therapies to suppress the HIV virus, then moving on to other drugs such as valproic acid that may further reduce virus levels in the body.
Sources:
Experimental
AIDS Therapy Offers Hope of Eventual Cure, David McAlary,
McAlary Reports, Washington, 12 August 2005.
Depletion of latent HIV-1 infection in vivo: a proof-of-concept
study. G. Lehrman et al., The Lancet, Volume 366, pages
549-555, 2005.
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