Nov. 23, 2000 -- The hottest new AIDS therapy strategy just got hotter. New findings offer a recipe for stopping and restarting AIDS drugs until the immune system can control the virus all by itself. Researchers also show how treatment vaccines could help people whose immune systems are already damaged by the AIDS virus.
"We consider this study as paving the way for a therapeutic [HIV] vaccine," Julianna Lisziewicz, PhD, tells WebMD. "After this data, we are much closer to such a vaccine. We are very excited that the immune system can control the virus -- there is more and more evidence now."
Still very much on the drawing board, the strategy -- called structured treatment interruption -- calls for periodically stopping and restarting HIV treatment. The idea is to let the immune system get a good look at the AIDS virus -- without being destroyed in the process. For some patients, the immune responses that result are so effective that they no longer have to take drugs to fight the virus. However, so far, the interruptions appear to work only for those who begin treatment in the first months after HIV infection -- before the virus does too much damage.
And now a team led by Lisziewicz and Franco Lori, MD, of the Research Institute for Genetic and Human Therapy, reports in the journal Science that treatment interruptions can be superior to currently used HIV drugs -- commonly know as HIV drug "cocktails."
The researchers infected monkeys with a deadly AIDS virus and six weeks later began treating them with drug cocktails. One group of animals followed a treatment interruption schedule: They had their treatment stopped and started every three weeks. Another group of animals took the drugs continuously. After 21 weeks, all of the animals stopped treatment for good.
Virus levels stayed low in the animals that had their treatment interrupted, and all of them stayed healthy. For the animals on continuous therapy -- all of which suffered side effects from drugs -- virus levels shot up soon after they stopped taking drugs, and only half of this group eventually developed boosted immune systems.
Experts differ on how important treatment interruptions are likely to be in real life. John Moore, PhD, tells WebMD that along with the development of more drugs, approaches like treatment interruptions must also be developed as part of HIV therapy. "[Treatment interruptions must] be validated, but it seems plausible, ... and I think it will be adopted regularly in years to come." Moore is a professor of microbiology and immunology at Weill Medicine College of Cornell University and a researcher at the Aaron Diamond AIDS Research Center in New York.
Treatment interruptions are "more a hope than a certainty," Mark Feinberg, MD, PhD, tells WebMD. "Preliminary data suggests that [treatment interruptions are] not going to be all that effective by itself." Feinberg is associate director of the Emory/Atlanta Center for AIDS Research and an associate professor of medicine and microbiology at Emory University.
Human studies show that treatment interruptions work for patients treated very soon after HIV infection. Lisziewicz thinks this window of opportunity can last for up to nine months. Most patients are in this category -- and that is where the idea of treatment vaccines come in.
Monkeys that were able to fight off the AIDS virus after treatment interruptions developed high levels of a kind of immune cell that recognizes and kills other cells that have become infected with HIV. The Lori/Lisziewicz team has come up with a viruslike vaccine that they hope will be able to stimulate these cells even in people with HIV-damaged immune systems, and early studies are under way. Other research teams are using different approaches to attempt the same feat.
Meanwhile, when it comes to treatment interruptions, all experts contacted by WebMD urge patients not to 'try this at home.'
"We are most concerned that patients will read this report and say, 'I have only to take three weeks on and three weeks off' ... but we do not know whether this is a recipe patients can take," Lisziewicz says. "There is still danger in [treatment interruptions] because you are playing with a very dangerous virus." She says it is very important to wait for the results of more research in large human studies.