MONDAY, Dec. 3, 2001 (HealthDayNews) -- In a potentially major advance for the treatment of HIV, scientists say an on-off cycle of antiviral drugs safely controls the infection and may produce fewer long-term side effects.
A pilot study, led by researchers at the National Institutes of Health (NIH), shows that a week of treatment followed by a week off doesn't undermine the the drugs' ability to suppress the AIDS virus or protect immune cells. The strategy would cut the amount of medication patients must take by 50 percent and would halve the annual per-patient cost of treatment, which now runs from $15,000 to $18,000 in this country.
"That to me is a very profound aspect to [the work] if it's borne out in randomized controlled trials," says lead study author Dr. Mark Dybul, assistant director for medical affairs at the National Institute of Allergy and Infectious Diseases. A cheaper regimen would be extremely important in Africa and other parts of the developing world where even cut-rate AIDS drugs are well beyond the reach of the typical patient, Dybul says. More than nine in 10 HIV-positive people in the world can't afford to pay for effective AIDS treatment.
However, Dybul says the results need verification in larger studies, which the NIH has already organized. "It's just too early to say that this is something anyone should try on their own."
Dybul and his colleagues report their findings in the latest online issue of the Proceedings of the National Academy of Sciences.
Highly active antiretroviral therapy (HAART) and its drug "cocktails" have turned HIV from a uniformly deadly disease into a chronic infection that can be controlled, apparently indefinitely. But the drugs are expensive and come with side effects: In at least 30 percent of patients, they lead to spikes and abnormalities in cholesterol and other blood fats that may presage cardiovascular problems.
The study, which included 10 men already undergoing multi-drug therapy for HIV, grew from the observation that virus levels typically remain quiet for about a week after stopping medication. As a result, the researchers reasoned, pausing therapy for that long, but not much longer, was safe.
Dybul's group followed the patients for 32 to 68 weeks, or between 16 and 34 "on" cycles. They regularly measured viral loads and counted blood cells called lymphocytes, particularly the CD4 T cells that HIV attacks.
All the patients were given a regimen of four HAART drugs: stavudine, lamivudine, indinavir and ritonavir. At the beginning of the trial, the patients had HIV levels of less than 50 copies per milliliter of plasma (considered undetectable) and CD4 counts of at least 300 cells per cubic millimeter of blood.
Despite the scaled back treatment, none of the men developed a significant increase in HIV levels or a drop in T cells. Nor did the researchers find evidence that the patients' immune cells were becoming infected with the virus or that the virus was accumulating in reservoirs where it likes to hide.
What's more, instead of increases in blood fats, the patients on the cycled therapy saw cholesterol fall by 22 percent and triglycerides by 51 percent after 24 weeks. And the remaining fat molecules appeared to be normal.
Dybul says the intermittent treatment probably won't ease the malaise that comes from taking up to 10 potent pills a day. But by keeping cholesterol and triglycerides in check, it may save patients from heart attacks, strokes and other cardiac conditions in years to come.
Dr. Bernard Hirschel, a Swiss AIDS expert who is studying a similar regimen, says the approach has "potentially wide applicability" to HIV-positive people. But, he says compliance could become an issue if patients decide to wait more than a week between "on" cycles. "That's a possibility, and we'll just have to see how the 'ordinary' patient takes the drugs," Hirschel says.
Indeed, seven days isn't an arbitrary number, says Dybul, citing one patient in the trial who went off treatment for 10 days and saw his viral load shoot up to 3,000 copies per milliliter. "You do have to stick to this structure. You can't just stop and start," he says.
Hirschel also is studying whether HAART is effective if it's used to drive HIV levels into submission, then suspended until the immune system begins to flag. He says that approach "is likely to fail in some patients who have high rebounds [of virus copies] and a rapid fall in CD4 cells without treatment."
What To Do: To find out more about AIDS and HIV, try AEGiS or the Centers for Disease Control and Prevention.
