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Objectives: To explore the durability of three first-line tenofovir/emtricitabine-based regimens in combination with atazanavir/ritonavir, efavirenz or lopinavir/ritonavir in HIV-1-infected patients., Patients and Methods: A retrospective, longitudinal, multicentre analysis of adult patients enrolled in the Antiretroviral Resistance Cohort Analysis (ARCA), a national prospective observational cohort of HIV-1-infected patients followed up at more than 100 clinical and laboratory units in Italy. Patients eligible were those starting first-line antiretroviral therapy between 1 June 2004 and 15 April 2011 and who were followed up for at least 6 months. The primary endpoint was durability, defined as the time from antiretroviral therapy initiation to first treatment modification. Time-dependent events were analysed by the Kaplan-Meier approach and the Cox proportional hazard model., Results: There are 26,000 HIV-infected patients in the ARCA database, of whom 1654 met study inclusion criteria. Six hundred and thirty-nine (38.6%) received efavirenz, 321 (19.4%) received atazanavir/ritonavir and 694 (41.9%) received lopinavir/ritonavir as a first-line regimen. Over a total observation period of 88 months, equivalent to more than 2805 person-years of follow-up, 618 patients underwent treatment modification. Lopinavir/ritonavir, given twice daily, was associated with a higher discontinuation rate than efavirenz- and atazanavir-based regimens [hazard ratio (HR) 1.83, 95% confidence interval (CI) 1.56-2.15, P = 0.001]. Comparing the once-daily regimens, the rate of discontinuation of efavirenz was higher than that of atazanavir/ritonavir (HR 1.39, 95% CI 1.06-1.83, P = 0.016)., Conclusions: Significant differences in treatment duration were observed among the three studied regimens. Once-daily regimens exhibited greater durability than the twice-daily regimen. Among the specific regimens examined, tenofovir/emtricitabine plus atazanavir/ritonavir showed the greatest durability.

Background: APV102002 was an open-label study comparing a dual-boosted HIV-1 protease inhibitor (PI) [fosamprenavir/lopinavir/ritonavir (FPV/LPV/RTV; 1400 mg/533 mg/133 mg twice daily)] and a high dose of FPV/RTV 1400 mg/100 mg twice daily (HD-FPV/RTV) versus the standard FPV/RTV 700 mg/100 mg twice-daily (STD-FPV/RTV) regimen for 24 weeks., Methods: Adult patients with prior failure to two or more PI-based regimens and on a failing PI regimen were randomized to STD-FPV/RTV (n = 24), HD-FPV/RTV (n = 25) or FPV/LPV/RTV (n = 25). The primary aim was to test week 24 superiority of HD-FPV/RTV and FPV/LPV/RTV over STD-FPV/RTV as measured by plasma HIV-1 RNA average area under the curve minus baseline (AAUCMB)., Results: There was no difference in the week 24 AAUCMB between the regimens. The proportion of patients with <50 copies/mL of plasma HIV RNA was 21%, 24% and 20%, respectively, by time to loss of virological response (TLOVR) analysis. High baseline drug resistance provided some explanation for the low efficacy. A lower baseline background drug resistance and higher fosamprenavir genotypic inhibitory quotient led to better antiviral responses. The plasma amprenavir trough concentartion (C(tau)) was 49% higher in the HD-FPV/RTV arm than in the STD-FPV/RTV arm and similar in the FPV/LPV/RTV and STD-FPV/RTV arms. The plasma lopinavir C(tau) was similar to historical data with standard LPV/RTV 400 mg/100 mg twice daily. All regimens were relatively well tolerated, although diarrhoea was more frequent in the HD-FPV/RTV and FPV/LPV/RTV arms, and hypertriglyceridaemia and increased total cholesterol were more common in the FPV/LPV/RTV arm., Conclusions: While the strategies of higher dose FPV/RTV and dual FPV/LPV/RTV were relevant at the time of study initiation, new therapies for antiretroviral-experienced patients make such strategies of limited interest. In addition, this study failed to demonstrate antiviral superiority of the HD-FPV/RTV or FPV/LPV/RTV regimen over the STD-FPV/RTV twice-daily regimen in highly treatment-experienced patients.