Dual therapy based on a ritonavir-boosted protease inhibitor as a novel salvage strategy for HIV-1-infected patients on a failing antiretroviral regimen

To assess the efficacy and safety of dual-antiretroviral therapy containing a ritonavir-boosted protease inhibitor (PI/r) in treatment-experienced patients failing a current antiretroviral regimen. Retrospective analysis of 60 consecutive HIV-1-infected patients who started a dual-antiretroviral rescue regimen containing a PI/r, in three hospitals in Spain. Virological failure was defined as confirmed HIV RNA 50 copies/mL at treatment week 24 or later. The percentage of patients remaining free of therapeutic failure was estimated using the KaplanMeier method, by intent-to-treat analysis (missing, changes and virological failuretherapeutic failure). Median baseline characteristics of patients were: 13 years on antiretroviral therapy (four prior highly active antiretroviral therapy regimens and eight different drugs), 380 CD4 cells/mm(3) and HIV RNA 3.04 log(10) copies/mL. All patients had resistance mutations to at least two drug classes, although only 9.3 had specific mutations to darunavir. A darunavir-based regimen was started in 47 (78.4) patients, combined with etravirine (26.7), tenofovir (26.7) or raltegravir (25). Three (5) patients discontinued treatment due to side effects. At the end of follow-up, 86.7 of patients remained free of therapeutic failure; the percentages of patients with no therapeutic failure at treatment weeks 24, 48 and 96 were 96.6 (95 CI, 91.9101.3); 90.1 (95 CI, 81.998.3) and 79.8 (95 CI, 66.193.5), respectively. Our results suggest that a dual-therapy rescue regimen including a PI/r is convenient, well tolerated and potent enough to achieve persistent viral suppression in selected pre-treated patients with low viral load and few PI resistance mutations.