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Introduction: There are multiple reasons to switch from a virologically successful antiretroviral regimen. Some of them are related to toxicity. Lately, combination antiretroviral treatment (cART) switches have often been related to drug-drug interactions which may also eventually entail safety issues as well. Areas covered: The purpose of this review is to analyze causes of switching between virologically successful cART regimes related to safety issues. The most relevant papers were selected and summarized. Expert opinion: Switching cART has been a popular strategy to address safety issues throughout the antiretroviral era. The myriad of switching studies have paralleled the study and release into clinical practice of new antiretroviral drugs with different and often improved safety profiles. Most of them have been successful in improving antiretroviral toxicity while keeping HIV replication under control. However, it should be taken into account that, whenever a new drug is given, there is a possibility of new drug-related toxicity. Notwithstanding that, an increase in cART switching is foreseen, given the fact that we have a wide antiretroviral drug armamentarium and that people living with HIV are ageing and thus more prone to developing age-related co-morbidities whose therapies may entail new interactions and eventually new toxicities.

Background: The risk of liver enzyme elevation (LEE) after different ritonavir-boosted protease inhibitors (PI/r) has not been fully assessed in real-life settings and in populations with high rates of hepatitis C virus (HCV) coinfection. Methods: Patients introducing a new PI/r between 1998 and 2012 were included, if transaminases and HCV antibody (Ab) were assessed before treatment initiation. Time to grade 3 and 4 LEE were assessed using univariable and multivariable conditional Cox analyses, stratified by HCV serostatus. Results: A total of 6193 HIV-infected patients (3242 HCV-Ab negative and 2951 HCV-Ab positive) were included. Incidence of grade 3 LEE was 1.05, 7.66, and 8.08 per 100 patient-years of followup among HCV-Ab negative, HCV-Ab-positive and HCV-RNA-positive patients, respectively. Among HCV-Ab-negative patients, no differences were detected between different PI/r. Use of darunavir/ritonavir was not associated with LEE among HCV-coinfected patients. Atazanavir/ritonavir use was associated with grade 3 LEE but only among HCV-Ab-positive patients (versus LPV/r, hazard ratio: 1.39; 95% confidence interval: 1.1 to 1.75). This risk was not confirmed in a subanalysis restricted to HCV-RNA-positive patients (versus LPV/r, hazard ratio: 1.16; 95% confidence interval: 0.87 to 1.55). Other independent predictors of grade 3 LEE among HCV-Ab-positive patients were older age, male gender, being treatment naive, nonnucleoside reverse transcriptase inhibitor coadministration, increased aspartate aminotransferase at baseline, overweight, positive HCV-RNA, and advanced estimated liver fibrosis. Conclusions: Occurrence of hepatotoxicity was a rare finding among HCV-Ab-negative patients and was not influenced by the type of PI/r. In particular, the use of darunavir/ritonavir, previously linked with severe cases of hepatotoxicity, was not associated with a greater risk of LEE, irrespective from HCV serostatus.

Protease inhibitor (PI)-resistant HIV-1 has hardly ever been detected at failed boosted PI-based first-line antiretroviral regimens in clinical trials. However, this phenomenon has not been investigated in clinical practice. To address this gap, data from patients starting a first-line lopinavir/ritonavir (LPV/rtv)-based therapy with available baseline HIV-1 RNA load, a viral genotype and follow-up viral load after 3 and 6 months of treatment were extracted from the Italian Antiretroviral Resistance Cohort Analysis (ARCA) observational database. Based on survival analysis, 39 (7.1%) and 43 (7.8%) of the 548 examined patient cases had an HIV-1 RNA >500 and >50 copies/ml, respectively, after 6 months of treatment. Cox proportional hazard models detected baseline HIV-1 RNA (RH 1.79, 95%CI 1.10-2.92 per 1-log(10) increase, P=0.02) and resistance to the nucleoside backbone (RH 1.04, 95%CI 1.02-1.06 per 10-point increase using the Stanford HIVdb algorithm, P<0.001) as independent predictors of HIV-1 RNA at >500 copies/ml, but not at the >50 copies/ml cutoff criteria. Higher baseline viral load, older patient age, heterosexual route of infection and use of tenofovir/emtricitabine were predictors of failure at month 3 using the 50-copy and/or 500-copy threshold. Resistance to LPV/rtv did not occur or increase in any of the available 36 follow-up HIV-1 genotypes. Resistance to the nucleoside backbone (M184V) developed in four cases. Despite the likely differences in patient population and adherence, both the low rate of virological failure and the lack of development of LPV/rtv resistance documented in clinical trials are thus confirmed in clinical practice.

(i) To compare early decrease of HIV plasma viral load (pVL) after two standard-combinations of highly active antiretroviral therapy (HAART) (ii) To evaluate variations of proviral HIV-DNA load on conditions of sustained pVL undetectability. Two different sub-studies of a multicentre prospective randomized controlled trial which compared two first-line HAART (i.e., zidovudine+lamivudine+lopinavir/ritonavir versus tenofovir+lamivudine+ efavirenz). Only patients enrolled at the coordinating centre (University of Brescia) were included in the two sub-studies. In the first sub-study, we calculated pVL decrease with respect to baseline at any of the following time-point: days 1, 3, 7, 14 and 28. Decreases of the pVL were compared between the two treatment groups. In the second sub-study, we'analyzed, variation of proviral HIV-DNA load in CD4+ T-cells from baseline to week 52 only in patients who maintained the same treatment regimen and had sustained undetectable pVL. In either studies, linear regression analysis was used to investigate what factors could influence variations of pVL and of proviral HIV-DNA load. (i) 64 patients were studied. A significant decrease of pVL was found from day 3 on, without statistically significant differences between the two study groups. However, after adjusting for possible confounders, tenofovir+lamivudine+efavirenz resulted to be associated with greater pVL decreases. (ii) 45 patients were studied. Mean proviral HIV-DNA load decreased from 1,610 (95%CI: 879-2,341) to 896 (95% CI 499-1,293) copies/106 cells (P=0.05). Linear regression analysis showed that the decrease of proviral DNA load during follow-up was independently and inversely correlated with age. Further studies are needed to compare pVL decay between antiretroviral regimens and assess whether proviral HIV-DNA load is a surrogate marker of treatment effectiveness. © 2008 Bentham Science Publishers Ltd.