Lack of impact of protease inhibitor resistance-associated mutations on the outcome of HIV-1-infected patients switching to darunavir-based dual therapy.

Background: Little is known about the impact of baseline resistance-associated mutations (RAMs) on the outcomes of alternative therapeutic strategies such as dual regimens. We assessed the efficacy of boosted darunavir plus raltegravir (DRV + RAL) dual regimen as a simplification strategy in virologically suppressed patients with protease inhibitors RAMs.Methods: Retrospective, multicentre study on the evolution of 228 heavily pretreated patients who switched to boosted DRV + RAL according to genotypic sensitivity score (GSS). Patients were classified as full susceptible (GSS = 2; n = 177), or with reduced darunavir susceptibility (GSS < 2; n = 51).Results: Median (range) number of prior antiretroviral regimens was 9 (6-14), with a median (range) of 2 (1-3), 4 (3-6), and 5 (2-9) major mutations to non-nucleoside reverse transcriptase inhibitors, nucleoside reverse transcriptase inhibitors, and protease inhibitors, respectively. The median time of virological suppression before simplification was 49 months (IQR 39.8-63.5). Patients with reduced darunavir GSS showed a higher number of protease inhibitors-RAMs (9.3 vs 4.5, p < .01) and were suppressed for longer time (median, 61 months). At week 96, the rate of virological failure was low (two cases, 0.9%; 95% confidence interval, CI, 0.4-2.7%), and the efficacy, excluding non-virological reasons, was 96.8% (95%CI, 90.2-98.4%), without differences according to GSS or protease inhibitors-RAMs. Furthermore, significant improvements in CD4+ counts and CD4/CD8 ratio were observed (p < .01) in both groups.Conclusions: Treatment simplification to a dual regimen of boosted DRV + RAL after long-term virological suppression was not associated with a high risk of treatment failure, even in patients harbouring protease inhibitors-resistant HIV infection.