AIDS MDs try changes with therapy
July 11, 2000
DURBAN, South Africa (AP) - Doctors are cautiously taking patients off their AIDS drugs for a few weeks at a time to see if breaks in therapy are safe and perhaps even more effective than giving the grueling treatment continuously.
The new approach, described Tuesday at the 13th International AIDS Conference, departs from the commonly held dogma that even a brief interruption in drug treatment will allow the AIDS virus to come roaring back in a mutant form that is impossible to control.
Intentionally interrupted therapy is still considered experimental. But doctors say it potentially has several important advantages, including lower cost, fewer side effects and temporary relief from a demanding pill schedule. Furthermore, it could make AIDS therapy more practical and affordable in poor parts of the world, where the sophisticated combinations of medicines are simply beyond the reach of most people with HIV.
Dr. Anthony Fauci, head of the U.S. National Institute of Allergy and Infectious Diseases, described promising but still early results with the approach.
"Patients are absolutely delighted at the prospect of spending half of their lives off therapy," Fauci said of those taking part in his experiments.
However, Fauci noted at least a dozen teams around the world are studying the approach - which he calls structured intermittent therapy - and it will be at least a year before doctors know whether it is safe. Until then, he cautioned against interrupting treatment outside carefully conducted studies.
"The long-term effect on the emergence of resistance and the ultimate clinical course of patients remains to be determined," he said.
Several years ago, when combination therapy revolutionized the treatment of AIDS, some researchers optimistically theorized that it might be possible to cure AIDS by wiping out the virus. Later, though, it became clear that the virus continues to reproduce at extremely low levels and hides in long-living cells of the lymph tissue, where it is beyond the reach of drugs.
"We won't cure HIV with the present drugs," said Dr. Mauro Schechter of the University of Rio de Janeiro.
Instead, he said, doctors need new strategies for using the available medicines to hold HIV in check, and interrupted therapy "will be a big thing in the near future."
Some doctors experimenting with the approach monitor patients' virus levels and put them back on their pills when HIV returns strongly. However, Fauci's team cycles patients on and off therapy without regard to virus levels.
In one experiment, intended to enroll 70 people, patients take drugs for two months followed by a one-month break. The virus soon comes back when people stop their drugs, but all measurable levels disappear when treatment resumes, and no resistant viruses have been seen so far.
Fauci said that after two to three cycles, the virus appears to come back less strongly in some people, suggesting that the immune system may gear up to control the virus better when it is exposed to HIV in brief bursts.
In theory, disease-fighting blood cells called CD8 T-cells might be stimulated this way to actually control HIV without the need for further drugs. However, Fauci said this is probably a long shot for most patients.
In a smaller pilot study, patients are taking their drugs on a week-on, week-off schedule. In this experiment, the virus never returns to more than minimal levels.
Fauci said abruptly stopping all drugs is key to preventing the growth of drug-resistant viruses, which often happens when patients cut back on their drugs but still take them.
Dr. David Ho of the Aaron Diamond AIDS Research Center in New York City said interrupted treatment "is a worthy area of pursuit," but he said it remains to be seen whether drug-resistant viruses eventually emerge.
One common problem of AIDS treatment is that patients' viruses often grow resistant to their drugs, even then they take them on schedule, and they must switch to new combinations. Dr. Scott Holmberg of the U.S. Centers for Disease Control and Prevention said Fauci's method may also help lengthen the time people can use each regimen.
In a study of 1,300 patients, he found that on average people could stay on a regimen about 11 months before it lost its punch. Their second combination worked for eight months and their third for six.
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Jim |
