VIRUSMYTH HOMEPAGE

IN STUDY, CYCLING AIDS DRUGS ON AND OFF APPEARS TO DO NO HARM

By David Brown

The Washington Post 8 February 2001

Chicago -- Some people infected with the AIDS virus may be able to cycle their drugs on and off at weekly intervals with little or no damage to their health, researchers reported today.

This observation came from a study of only 10 patients, and thus is far from definitive. If the finding holds up, however, it will amount to a consolation prize in the so far fruitless search for a way to get at least some people who are infected with the human immunodeficiency virus (HIV) off their medicine for good. Cycling the drugs on and off would effectively cut in half the amount of time a patient would have to bear the intrusion of the treatment.

"This is a big deal to people," said Anthony S. Fauci, whose research group made the finding in patients being studied at the National Institute of Allergy and Infectious Diseases, which he heads. "These people are positively inclined to being off-drug 50 percent of the time."

Originally, Fauci and his collaborators hoped that patients infected with HIV could be weaned off antiviral drugs for prolonged periods. The strategy was this: After fully suppressing viral replication with combination therapy, patients would periodically stop their drugs for brief periods. The regrowth of the virus would stimulate, but not overwhelm, the immune system. With each cycle, the body would be able to control the virus longer, or push it lower, without the help of pharmaceuticals.

Unfortunately, "that is not happening," Fauci told a gathering of researchers at the 8th Annual Retrovirus Conference, the international AIDS meeting held each winter in the United States.

In a study of 24 patients who underwent numerous cycles of two-months-on, one-month-off treatment, none showed the hoped-for effect. In virtually every patient, the virus rebounded vigorously in the off month (although restarting treatment was always able to suppress it.)

A companion experiment, however, showed the more promising results. In it, the cycles were seven days on and seven days off. In the off weeks, the virus invariably remained fully suppressed. However, its reappearance was only a matter of time. Two patients failed to resume their treatments after seven days, and HIV was detectable in their bloodstreams soon after.

A few of these patients have gone through these cycles for 10 months and show no evidence of damage to their immune systems or the development of resistant strains of the virus. Inadequate or intermittent drug doses usually promote the evolution of drug-resistant viruses. The sudden stopping and restarting of fully potent therapies in these patients appear to keep that from happening.

It is not known, however, whether resistance will develop eventually. Another important question is whether cycling will reduce the incidence of the drugs' side effects, such as the redistribution of body fat, called lipodystrophy syndrome, that occurs in about 20 percent of the people on the drug combinations.

More patients and more time will be required to determine whether this half-loaf therapy is just as good as the whole. Fauci warned that it is still an unproved regimen. "We don't want people to do this on their own," he said.

Elsewhere at the meeting, researchers reported that drug-resistant strains of HIV are fairly common among people who are newly infected and have never taken any antiviral drugs. This shows that the universe of viruses in circulation now contains a fair number of these mutants.

In a study in eight cities in the United States and Canada, 8 percent of the people starting treatment for the first time harbored a virus that was resistant to at least one of the three classes of antiviral drugs on the market. Four percent had a virus that was resistant to two or more. A study done in France showed that 10 percent of viral samples taken from just-infected people were resistant to at least one drug class. In a Swiss study, 5 percent of new infections involved a drug-resistant virus -- a decrease from the previous two years.

Also yesterday, the Centers for Disease Control and Prevention detailed a major new push to increase the number of high-risk people to be tested for HIV in the United States, and to increase safe-behavior and personal health messages to those already infected. The latter group has received relatively little attention in public health campaigns.

VIRUSMYTH HOMEPAGE