AIDS “drug holidays” may be dangerous in patients whose virus has become drug-resistant, a new study released Wednesday showed.
Giving such breaks from treatment helped the disease progress faster and did little to save lives or improve the quality of health when signs of drug resistance were appearing, researchers reported in Thursday’s New England Journal of Medicine.
“We had hoped that a structured treatment interruption would be beneficial for people experiencing treatment failure due to multidrug-resistant HIV,” Dr. Jody Lawrence of the University of California, San Francisco, who led the study, said in a statement.
“However, our results indicate that this strategy does not work and should be avoided by this group of HIV-infected individuals. Continuing therapy guided by HIV drug resistance testing proved to be a better approach.”
The so-called drug holidays are being tried in a variety of HIV patients and some studies have suggested they can give patients a break from the side effects of the drugs without putting them at risk.
But this latest study suggested it was dangerous to do so in patients whose virus had evolved to resist the effects of the drugs.
Doctors considered interrupting treatment once resistance to the drugs has developed because, when the drugs are stopped, the AIDS virus tends to mutate back to a form that is sensitive to the highly active anti-retroviral therapy, known as HAART, used as the first line of treatment.
The Lawrence team found that in 64 percent of the 138 test patients whose treatment was interrupted for 16 weeks, the virus indeed reverted to a more sensitive form.
However, those people did not do as well as the 132 patients who were immediately switched to new medicines.
While AIDS progressed in 16 percent of the people who had a drug holiday, the disease got worse in only 9 percent of those who immediately received a different HAART cocktail.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, which sponsored the research, cautioned that the new study only included cases where the AIDS virus was detectable in the blood and the virus particles had become resistant to drugs.
“For individuals who are being successfully treated with anti-HIV medications, other studies have shown that cycles of treatment interruptions for shorter periods may be of potential benefit to conserve medications and reduce drug-related toxicities,” Fauci said in a statement.
In a commentary, Dr. Bernard Hirschel of Cantonal University Hospital in Geneva, Switzerland, said the idea the AIDS virus, if left alone, will become more sensitive to drugs may be an illusion.
If there are 5,000 drug-resistant virus particles in each milliliter of blood, they may quickly become outnumbered by 100,000 drug-sensitive particles, but still remain and can linger for years, he said.
“Thus, it is hard to see what could be achieved by interrupting treatment for a few weeks,” Hirschel wrote.