Structured interruptions of highly active antiretroviral therapy in cycles of 4 weeks off/12 weeks on therapy in children having a chronically undetectable viral load cause progressively smaller viral rebounds.

ABSTRACT

OBJECTIVES: To evaluate the viral, immune and clinical impact of a structured treatment interruption (STI) program of highly active antiretroviral therapy (HAART) in three cycles of 4 weeks off/12 weeks on therapy in a cohort of children with HIV infection under chronic viral control. METHODS: Using a single-group time series experimentation design and following informed consent, the HAART of children with HIV and a chronically undetectable viral load (VL) was discontinued for 4 weeks and then restarted and continued for 12 weeks for a total of three cycles. The VL, CD4+/CD8+ lymphocytes, and clinical status were evaluated at the end of each STI and at 6 and 12 weeks after HAART was resumed. RESULTS: Four children with a median age of 10.3 years (range 6.5-11.2 years) were included in the study. Their clinical immune categories were A1 (n=2), A2 (n=1), and B3 (n=1). Treatment of all four patients was with zidovudine (AZT)+lamivudine (3TC)+ritonavir (RTV). At the end of the first STI, VL was a median 214000 copies/ml (range 27400-616000), corresponding to 5.3 log(10) (range 4.4-5.8). At the end of the second STI, VL was a median 72400 copies/ml (range 17800-126000) or 4.7 log(10) (range 4.2-5.1), which corresponds to a rebound 0.6 log(10) lower than the first. At the end of the third STI, VL was a median 28200 copies/ml (range 5370-140000) or 4.45 log(10) (range 3.7-5.1), a rebound 0.85 log(10) lower than the first. All rebounds were followed by a decrease in the VL to undetectable levels during the treatment periods. CD8+ T lymphocyte counts increased during viral rebounds and an initial decrease in CD4+ T lymphocyte counts was followed by a tendency to increase even exceeding CD8+ T cell counts. Only one event of transitory severe immunosuppression occurred. There were no symptoms related to the HIV infection. CONCLUSIONS: The STI of HAART in cycles of 4 weeks off/12 weeks on therapy in children with chronically undetectable VL can cause progressively lower viral rebounds followed by a decrease to undetectable levels, with a low risk of severe immunosuppression and without the occurrence of symptoms related to HIV.