Mutations Related to Antiretroviral Resistance Identified by Ultra-Deep Sequencing in HIV-1 Infected Children under Structured Interruptions of HAART.

Although Structured Treatment Interruptions (STI) are currently not considered an alternative strategy for antiretroviral treatment, their true benefits and limitations have not been fully established. Some studies suggest the possibility of improving the quality of life of patients with this strategy; however, the information that has been obtained corresponds mostly to studies conducted in adults, with a lack of knowledge about its impact on children. Furthermore, mutations associated with antiretroviral resistance could be selected due to sub-therapeutic levels of HAART at each interruption period. Genotyping methods to determine the resistance profiles of the infecting viruses have become increasingly important for the management of patients under STI, thus low-abundance antiretroviral drug-resistant mutations (DRM's) at levels under limit of detection of conventional genotyping (<20% of quasispecies) could increase the risk of virologic failure. In this work, we analyzed the protease and reverse transcriptase regions of the pol gene by ultra-deep sequencing in pediatric patients under STI with the aim of determining the presence of high- and low-abundance DRM's in the viral rebounds generated by the STI. High-abundance mutations in protease and high- and low-abundance mutations in reverse transcriptase were detected but no one of these are directly associated with resistance to antiretroviral drugs. The results could suggest that the evaluated STI program is virologically safe, but strict and carefully planned studies, with greater numbers of patients and interruption/restart cycles, are still needed to evaluate the selection of DRM's during STI.

Drug resistance mutations during structured interruptions of HAART in two HIV-1-infected children.

Information concerning structured treatment interruptions (STI) of the Highly Active Antiretroviral Therapy (HAART) and their risk for selecting antiretroviral drug resistance in children is scarce. In this study, we searched for antiretroviral drug resistance mutations at the end of five viral rebounds of two children with HIV and a chronically undetectable viral load (VL) who underwent an STI program. The HAART was interrupted for 4 weeks and then restarted and continued for 12 weeks for three cycles. 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. Treatment of both the patients based on zidovudine+lamivudine+ritonavir remained identical during the study. The reverse transcriptase (RT)- and protease (PR)-coding regions were sequenced at the end of each viral rebound. One patient experienced progressively lower viral rebounds (269000-31300 at the first and third rebounds, respectively), while the other patient did not experience such a reduction, and the VL of both the patients fell to undetectable levels during therapy. In the five viral rebounds examined, no mutations for resistance to protease inhibitors (PIs) were found and the analysis indicated susceptibility to all PIs currently in clinical use. Although the mutation K103R associated with non-nucleoside reverse transcriptase inhibitor resistance was found in two viral rebounds of one patient, the analysis indicated the absence of resistance to RT inhibitors. As no mutation related to antiretroviral drug resistance was found, our results suggest that the STI program evaluated may have a low risk of selecting antiretroviral drug resistance. Nevertheless, further studies evaluating larger cohorts over longer periods are required before definitive conclusions about the safety of STI of HAART in children may be drawn.

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.

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.