Enzo Boeri

Prevalence of Drug-Resistant HIV-1 Variants in Untreated Individuals in Europe: Implications for Clinical Management

BACKGROUNDnInfection with drug-resistant human immunodeficiency virus type 1 (HIV-1) can impair the response to combination therapy. Widespread transmission of drug-resistant variants has the disturbing potential of limiting future therapy options and affecting the efficacy of postexposure prophylaxis.nnnMETHODSnWe determined the baseline rate of drug resistance in 2208 therapy-naive patients recently and chronically infected with HIV-1 from 19 European countries during 1996-2002.nnnRESULTSnIn Europe, 1 of 10 antiretroviral-naive patients carried viruses with > or = 1 drug-resistance mutation. Recently infected patients harbored resistant variants more often than did chronically infected patients (13.5% vs. 8.7%; P=.006). Non-B viruses (30%) less frequently carried resistance mutations than did subtype B viruses (4.8% vs. 12.9%; P<.01). Baseline resistance increased over time in newly diagnosed cases of non-B infection: from 2.0% (1/49) in 1996-1998 to 8.2% (16/194) in 2000-2001.nnnCONCLUSIONSnDrug-resistant variants are frequently present in both recently and chronically infected therapy-naive patients. Drug-resistant variants are most commonly seen in patients infected with subtype B virus, probably because of longer exposure of these viruses to drugs. However, an increase in baseline resistance in non-B viruses is observed. These data argue for testing all drug-naive patients and are of relevance when guidelines for management of postexposure prophylaxis and first-line therapy are updated.

Lamivudine monotherapy in HIV-1-infected patients harbouring a lamivudine-resistant virus: a randomized pilot study (E-184V study).

Objective:We compared the immunological and clinical outcomes of lamivudine monotherapy and complete therapy interruption in the treatment of HIV-1-infected patients harbouring lamivudine-resistant virus. Methods:This 48-week, open-label pilot study randomly assigned HIV-infected patients receiving lamivudine-containing HAART and harbouring the M184V mutation to monotherapy with lamivudine 300 mg once daily (lamivudine group) or the discontinuation of all antiretroviral drugs (TI group). The primary endpoint was the occurrence of immunological or clinical failure; immunological failure was defined as the first report of a CD4 T-cell count less than 350 cells/μl, and clinical failure as the occurrence of a Centers for Disease Control and Prevention grade B or C event. The data were analysed on the basis of the intention-to-treat principle. Results:By week 48, 20 of 29 patients in the TI group (69%; 95% CI 51–83%) and 12 of 29 in the lamivudine group (41%; 95% CI 26–59%) had discontinued the study because of immunological or clinical failure, which was significantly delayed in the lamivudine group (P = 0.018). Only patients in the TI group (6/29, 20.7%) experienced grade 3–4 clinical adverse events at least possibly related to HIV-1 (P = 0.02). The mean decline in CD4 cell percentage, viral rebound and recovery of HIV-1 replication capacity were significantly lower in the lamivudine group. The 24-week virological and immunological response after therapy resumption in patients who prematurely discontinued the study was similar in the two groups. Conclusion:In HIV-1-infected patients harbouring a lamivudine-resistant virus, lamivudine monotherapy may lead to a better immunological and clinical outcome than complete therapy interruption.

Tracing the HIV-1 subtype B mobility in Europe: a phylogeographic approach

BackgroundThe prevalence and the origin of HIV-1 subtype B, the most prevalent circulating clade among the long-term residents in Europe, have been studied extensively. However the spatial diffusion of the epidemic from the perspective of the virus has not previously been traced.ResultsIn the current study we inferred the migration history of HIV-1 subtype B by way of a phylogeography of viral sequences sampled from 16 European countries and Israel. Migration events were inferred from viral phylogenies by character reconstruction using parsimony. With regard to the spatial dispersal of the HIV subtype B sequences across viral phylogenies, in most of the countries in Europe the epidemic was introduced by multiple sources and subsequently spread within local networks. Poland provides an exception where most of the infections were the result of a single point introduction. According to the significant migratory pathways, we show that there are considerable differences across Europe. Specifically, Greece, Portugal, Serbia and Spain, provide sources shedding HIV-1; Austria, Belgium and Luxembourg, on the other hand, are migratory targets, while for Denmark, Germany, Italy, Israel, Norway, the Netherlands, Sweden, Switzerland and the UK we inferred significant bidirectional migration. For Poland no significant migratory pathways were inferred.ConclusionSubtype B phylogeographies provide a new insight about the geographical distribution of viral lineages, as well as the significant pathways of virus dispersal across Europe, suggesting that intervention strategies should also address tourists, travellers and migrants.

Cross-resistance Profile of the Novel Integrase Inhibitor Dolutegravir (S/GSK1349572) Using Clonal Viral Variants Selected in Patients Failing Raltegravir

Novel integrase inhibitors are in advanced clinical development, and cross-resistance data are needed to consider the possibility to plan a sequential usage within this class of antiretroviral drugs. Ex vivo phenotypic assays were conducted on 11 wild-type and 27 fully replicating recombinant viruses obtained from 11 patients failing previous raltegravir-containing regimens. Dolutegravir maintained its activity in vitro on viruses with mutations in position 143 and 155. However, viruses with mutation Q148R associated with secondary mutations and the combination Q148H+G140S were instead associated with a reduced level of susceptibility to dolutegravir in vitro.

Dynamic patterns of human immunodeficiency virus type 1 integrase gene evolution in patients failing raltegravir-based salvage therapies.

Objective:Evaluate HIV-1 subtype B integrase gene evolution in patients failing raltegravir (RAL)-based savage regimens by clonal analysis of the replicating viral quasispecies. Design:Seven triple class failure HIV-1 (subtype B)-infected patients, followed at San Raffaele Hospital and enrolled in the RAL Expanded Access Program (MK0518-023), were evaluated. Patients were followed up for 24–48 weeks and due to the absence of other active drugs, RAL was maintained in their regimens even if resistance mutations were detected. Methods:Immunologic and virologic parameters were recorded every 4 weeks, and amplification and clonal analysis of viral populations were performed at baseline and every 4–12 weeks in all patients. Results:Resistance to RAL appeared initially associated with selection of single variants (Y143R, Q148R N155H) in the majority of patients; however, in three patients, complex patterns of viral mutations were observed. The clonal analysis of viral quasispecies allowed to describe the evolution of each viral population and the progressive accumulation of RAL resistance-associated mutations and polymorphisms associated with therapy failure. Conclusion:The complex patterns of resistance mutations observed, including novel variants evolved under continuous RAL pressure, suggesting that they are the result of the equilibrium between drug resistance and enzyme function. Despite the efficacy of this compound, our data discourage its use in a functional monotherapy and maintaining RAL even in presence of RAL resistance-associated mutations may lead to the progressive formation of viral reservoirs with multiple integrase inhibitor-resistant variants that may limit the future efficacy of other integrase inhibitors due to cross-resistance.

Anti-Cell Antibodies in Exposed Seronegative Individuals with HIV Type 1-Neutralizing Activity

Despite repeated exposures to HIV-1, some individuals remain seronegative. This study reports that sera from a fraction of exposed seronegative (ESN) subjects showed HIV-neutralizing activity; 5 of 17 ESN sera and none of 17 controls neutralized two different HIV-1 primary isolates (range of neutralizing titers: 1/20 to 1/60). The neutralizing activity was associated with the IgG fraction of 4 of 4 neutralizing ESN sera. Moreover, in 11 of 17 and 9 of 17 ESN sera (but none of the control sera) we found antibodies against HLA class I and CD4, respectively. One of the ESN sera (EU22) neutralized efficiently the primary virus derived from the seropositive partner and showed a good broadly cross-reactive neutralization. Immunoadsorption of two IgG fractions from EU19 and EU22 on peripheral blood mononuclear cells (PBMC) removed virus-neutralizing antibodies. The correlations between the ESN status and neutralizing activity (p<0.05), anti-HLA antibodies (p<0.0002), and anti-CD4 antibodies (p<0.001) were statistically significant. However, there was no statistically significant correlation between neutralizing activity and either anti-HLA or anti-CD4 antibodies. It can therefore be said that exposure to HIV-1 without seroconversion is, in some individuals, associated with HIV-neutralizing antibodies (not directed against viral antigens) and/or with anti-cell autoantibodies, which are possibly specific for cellular antigens involved in the infection/entry process.

Pretreatment of chronic active hepatitis C in patients coinfected with HIV and hepatitis C virus reduces the hepatotoxicity associated with subsequent antiretroviral therapy.

Chronic hepatitis C virus (HCV) is an independent risk factor for antiretroviral-related hepatotoxicity, but little is known about the frequency of severe liver toxicity in patients with HIV-HCV coinfection first treated for HCV (pretreated). The aim of this prospective study of 105 patients was to compare the incidence of progression to severe antiretroviral-related liver toxicity in 66 patients pretreated (36 with interferon-alpha [IFNalpha], 30 with IFNalpha plus ribavirin), and 39 patients not pretreated. The subjects could choose whether to receive anti-HCV therapy. Severe liver toxicity was defined as alanine aminotransferase (ALT) level > or =5-times the upper limit of normal in patients with normal baseline levels and > or =3.5-times in those with increased baseline levels. The authors also estimated the hepatotoxicity-related risk of discontinuing antiretroviral therapy. During antiretroviral therapy, 10 subjects (9.5%) experienced severe hepatotoxicity: 4 of 66 pretreated patients and 6 of 39 untreated patients (24-month survival: 94% +/- 2.9% vs. 85% +/- 5.8%). After adjusting for baseline CD4 cell counts, ALT levels, histologic scores, HCV and HIV viremia, HCV genotype (genotype 1 in 29% of pretreated patients and 20% of patients not pretreated), and previous anti-HCV therapy, the risk of discontinuing anti-HIV treatment was significantly higher in the anti-HCV untreated patients (RR = 10.4; 95% CI: 1.6-66; p =.0127) and in those with increased baseline ALT levels (RR = 1.014; 95% CI: 1.006-1.021; p =.0005). The authors data suggest that previous treatment of chronic active HCV is an independent factor associated with a decrease of severe liver toxicity as the result of a subsequent antiretroviral regimen. The authors also confirm that the baseline level of ALT is an important prognostic factor for increased liver damage during antiretroviral therapy.

Genotypic/phenotypic patterns of HIV-1 integrase resistance to raltegravir

OBJECTIVESnTo understand the dynamic viral evolution observed during failure on raltegravir-containing regimens, we studied the genotypic and phenotypic patterns of resistance to raltegravir and the residual replication capacity (rRC) of HIV-1 variants selected in vivo.nnnMETHODSnClonal genotypic analyses were performed on sequential HIV-1 integrase sequences amplified from 11 failing patients and sampled every 4-24 weeks for up to 64 weeks. Fully replicating recombinant viruses were generated using modified vectors in which selected viral integrase genes amplified from patients plasma were cloned. rRC was measured by a novel multiple cycle competition assay. Resistance to raltegravir and the rRC of resistant HIV-1 variants selected in vivo were evaluated in purified CD4+ T cells.nnnRESULTSnIn all of the patients but one, failure was associated with selection of mutations in positions 143, 148 or 155. Unlike mutations at position 143 (Y143S/K/R), identified alone or in combination with others, mutations at position 148 and 155 were always found in combination. A wide range of resistance levels to raltegravir [from 10- to 770-fold change in 50% inhibitory concentration (IC(50)) compared with baseline] was observed using recombinant viral clones. Finally, rRC was not significantly altered in highly resistant variants.nnnDISCUSSIONnTwo patterns of viral evolution were observed in the resistant viral populations, driving the variants towards a fast (most of them with G140S + Q148H mutations) or progressive increase in resistance to raltegravir. These results may have implications either for the evaluation of genotypic results, or for the correct clinical use of the compound.

Effect of genotypic resistance on the virological response to highly active antiretroviral therapy in cerebrospinal fluid

Paired plasma and cerebrospinal fluid (CSF) specimens drawn from 15 HIV-infected patients with neurological disease before and after a median 6-week duration of highly active antiretroviral therapy (HAART) were studied to assess the short-term virological response of CSF and whether this can be predicted on the basis of baseline resistance mutations. After treatment, the median plasma and CSF viral load (VL) decreased by, respectively, 2.08 log10 (p = 0.0001) and 0.91 log10 copies/ml (p = 0.007) in comparison with baseline. A plasma virological response was observed in all but one patient, whereas the posttreatment CSF VL increased, remained unchanged, or decreased at a substantial lower rate than in plasma of six CSF non/slow responders (40%). Direct sequencing of baseline specimens showed that none of these patients had reverse transcriptase (RT) or primary protease resistance mutations in the CSF alone, but two had RT mutations conferring high-level resistance to drugs included in the HAART regimen in both CSF and plasma. The other four patients had no RT or primary protease resistance mutations. There was no significant difference in the nucleotide diversity of the CSF and plasma RT sequences, baseline plasma or CSF VL, the CSF-to-plasma VL ratio, the number of CSF cells, the CD4+ cell counts, or the history of antiretroviral treatment between the CSF non-slow responders and the other patients. During this short-term follow-up and despite a plasma response, a significant proportion of HAART-treated patients with neurological symptoms showed a slow or absent CSF response. Most of these cases were not associated with the presence of resistant HIV strains in the CSF.

Rules-based HIV-1 genotypic resistance interpretation systems predict 8 week and 24 week virological antiretroviral treatment outcome and benefit from drug potency weighting

OBJECTIVESnTo test retrospectively the ability of four freely available rules-based expert systems to predict short- and medium-term virological outcome following an antiretroviral treatment switch in pre-treated HIV-1 patients.nnnMETHODSnThe HIV-1 genotype interpretation systems (GISs) HIVdb, ANRS, Rega and AntiRetroScan were tested for their accuracy in predicting response to highly active antiretroviral therapy using 8 week (n = 765) and 24 week (n = 634) follow-up standardized treatment change episodes extracted from the Italian Antiretroviral Resistance Cohort Analysis (ARCA) database. A genotypic sensitivity score (GSS) was derived for each genotype-treatment pair for the different GISs and tested as a predictor of virological treatment outcome by univariable and multivariable logistic regression as well as by receiver operating characteristic curve analysis. The two systems implementing drug potency weights (AntiRetroScan and Rega) were evaluated with and without this correction factor.nnnRESULTSnAll four GSSs were strong predictors of virological treatment outcome at both 8 and 24 weeks after adjusting for baseline viro-immunological parameters and previous drug exposure (odds ratios ranging from 2.04 to 2.43 per 1 unit GSS increase; P < 0.001 for all the systems). The accuracy of AntiRetroScan and Rega was significantly increased by drug potency weighting with respect to the unweighted versions (P <or= 0.001). HIVdb and ANRS also increased their performance with the same drug potency weighting adopted by AntiRetroScan and Rega, respectively (P < 0.001 for both analyses).nnnCONCLUSIONSnCurrently available GISs are valuable tools for assisting antiretroviral treatment choices. Drug potency weighting can increase the accuracy of all systems.