In patients followed beyond 48 weeks, the rate of virological failure at 48 weeks was at most 20%. Virological failure was more likely where patients had previously failed on both amprenavir and saquinavir and as the number of previously failed PI regimens increased. As a component of therapy for treatment-experienced patients, darunavir

can achieve a similar efficacy and tolerability in clinical practice to that seen in clinical trials. Clinicians should consider whether a patient has failed on both amprenavir and saquinavir and the number of failed BKM120 cell line PI regimens before prescribing darunavir. Patients with multi-drug-resistant HIV now have a number of treatment options, including the protease inhibitors (PIs) darunavir and tipranavir, the nonnucleoside reverse transcriptase Inhibitor Library chemical structure inhibitor (NNRTI) etravirine, the integrase inhibitor raltegravir, the chemokine (C-C motif) receptor 5 (CCR5) antagonist maraviroc and the fusion inhibitor enfuvirtide [1]. Darunavir, a second-generation PI, was designed for PI-resistant HIV [2]. After 48 weeks of treatment with darunavir, 45% of highly treated patients achieved a viral load below 50 HIV-1 RNA copies/mL [3],

with this percentage rising to 71 and 84% in moderately treated and treatment-naïve patients, respectively [4,5]. After treatment failure on multiple regimens, patients should be given a salvage therapy with at least two active drugs [6], and use of darunavir in combination with etravirine, enfuvirtide or raltegravir

improves efficacy [3,7–9]. Mutations resistant to darunavir [10–14], while infrequent, are more prevalent after treatment failure on amprenavir or saquinavir and as the number of failed PI regimens increases [15]. Darunavir has shown good results in clinical trials but few data are available from clinical practice. We report on the efficacy and tolerability of darunavir in the Swiss HIV Cohort Study (SHCS) as a salvage therapy for treatment-experienced patients and we assess risk factors associated with its virological failure. The SHCS is a prospective cohort with continuing enrolment of HIV-infected adults [16]. Our population of interest Pyruvate dehydrogenase was all patients in the SHCS whose first use of darunavir was as a component of salvage therapy. We defined a salvage therapy as any therapy used after a patient recorded a viral load above 1000 copies/mL given prior exposure to PI- and NNRTI-based therapies for more than 90 days each. Our sample from this population was all those with viral load and CD4 cell count measured up to 180 days before starting darunavir, and with at least one viral load measured 12 weeks or more after starting darunavir. We followed the patients in this sample for up to 72 weeks. Virological failure is the failure to achieve viral suppression or viral rebound after suppression.