Predictive factors of virological success to salvage regimens containing protease inhibitors in HIV-1 infected children.

Background: The impact of HIV drug resistance mutations in salvage therapy has been widely investigated in adults. By contrast, data available of predictive value of resistance mutations in pediatric population is scarce.

Methods: A multicenter, retrospective, observational study was conducted in children who received rescue salvage antiretroviral therapy after virologic failure. CD4 counts and viral load were determined at baseline and 6 months after rescue intervention. Genotypic HIV-1 resistance test and virtual phenotype were assessed at baseline.

Results: A total of 33 children met the inclusion criteria and were included in the analysis. The median viral load (VL) and median percentage of CD4+ at baseline was 4.0 HIV-RNA log copies/ml and 23.0% respectively. The median duration that children were taking the new rescue regimen was 24.3 weeks (23.8-30.6). Overall, 47% of the 33 children achieved virological response at 24 weeks. When we compared the group of children who achieved virological response with those who did not, we found out that mean number of PI related mutations among the group of responders was 3.8 vs. 5.4 (p = 0.115). Moreover, the mean number of susceptible drugs according to virtual phenotype clinical cut-off for maximal virologic response was 1.7 vs. 0.8 and mean number of susceptible drugs according to virtual phenotype cut-off for minimal virlologic response was 2.7 vs. 1.3 (p < 0.01 in all cases). Eighteen children were rescued with a regimen containing a boosted-PI and virological response was significantly higher in those subjects compared with the others (61.1% vs. 28.6%, p < 0.01).

Conclusion: Salvage treatment containing ritonavir boosted-PIs in children with virological failure was very efficient. The use of new tools as virtual phenotype could help to improve virologic success in pediatric population.