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,"
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.