Interrupting HIV Treatment: Can It Be Done?
Feb. 4, 2000 (San Francisco) -- While coming off toxic AIDS therapies for "drug holidays" is popular with patients, and some have had spectacular success, the approach has yet to prove itself as a method of boosting the body's natural immune system. At the very least, the results of these experiments are mixed. In several presentations here this week at an HIV conference, researchers showed what was gained, and lost, when patients interrupted treatment.
In what is apparently the largest study of drug interruption to date, Bernard Hirschel, MD, of University Hospital in Geneva, looked at 120 patients who were well controlled on what is considered the standard treatment today, highly active anti-retroviral therapy (HAART). Treatment was stopped for two weeks and restarted for eight weeks in four different cycles. About 70% of the patients experienced a rebound of the virus, but it was quickly brought under control.
The question remaining is, did anyone show an improvement in immune response as a result of the interruption? Hirschel says there were some modest jumps after the second drug-pause, but no clear pattern. Since the immune measurements were done in a test tube, it's not clear what actual impact the interruptions had on the disease. However, Hirschel says CD4 white blood cells, which orchestrate the overall immune response, bounced back, but other parts of the immune system did not. That was a disappointment for researchers.
"The likely best outcome is we identify a subgroup of patients where you can stop treatment and they do well for a long time," Hirschel tells WebMD.
It may also be possible to model a vaccine from knowledge gained during these drug holidays. "Then you can ask, is it really necessary to interrupt treatment to get this immune response? Maybe you can get a therapeutic vaccine that mimics the immune response, and then you don't need to interrupt," says Hirschel.
However, another study from the University of California, San Francisco indicated that a 12-week interruption cost patients precious CD4 cells, and it took about a year to get them back. The research also shows that in most of the 18 patients, HIV reverted to its wild state when it wasn't being challenged by drugs -- a measure of the virus' adaptability, and not a good state for the patient.