"Drug Holidays" Not Beneficial for Fighting HIV

Despite hopes that taking regularly scheduled breaks from combination therapy would train the immune system to keep HIV under control, a new study published online in the Proceedings of the National Academy of Sciences Early Edition (2002;10.1073/pnas.202372199) fails to detect any benefit of such drug holidays. Interest in drug holidays is high because, although combination therapy has been life-extending for many people, the drugs are expensive and can have serious side effects. In addition, some people have a hard time sticking to the complicated daily regimen of pills.

A few reports have suggested that structured, physician- supervised breaks from combination therapy may improve the ability of the immune system to fend off HIV. The hope was that repeatedly exposing the immune system to HIV during short drug vacations might lower the set-point viral load.

In a study of 97 patients with chronic HIV infection, however, that did not turn out to be the case. Dr. Annette Oxenius, of the Eidgenossische Technische Hochschule in Zurich, Switzerland, found that viral load was slightly lower after drug vacations, but the difference was very small.

Taking a break from combination therapy did not affect CD8 T cells that specifically target HIV. Only those patients who had vigorous CD8 responses to HIV before taking a break continued to do so afterwards. The researchers concluded that structured treatment interruption is "generally unable" to alter how a person's immune system responds to HIV. The authors point out, however, that the study included patients who were chronically infected with HIV. Research has shown that structured treatment interruptions for newly infected patients can alter the immune response to HIV.

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