Ottavia Viganò

Switching to unboosted atazanavir reduces bilirubin and triglycerides without compromising treatment efficacy in UGT1A1*28 polymorphism carriers

OBJECTIVES Hyperbilirubinaemia is a frequent complication of atazanavir-containing antiretroviral therapy and its severity is related to UDP-glucuronosyl transferase (UGT) 1A1*28 polymorphism. The aim of this study was to evaluate the safety and outcome of unboosted atazanavir-containing regimens based on the genetic constitution. METHODS Fifty-one HIV-1-infected patients on boosted atazanavir were prospectively enrolled in the study. Twenty-five patients with a UGT1A1*28 allele switched to 400 mg of unboosted atazanavir. RESULTS At baseline, UGT1A1 heterozygous and homozygous patients had significantly higher bilirubin levels than wild-type (P = 0.012 and P < 0.001, respectively). After ritonavir removal, a reduction was observed in total bilirubin (from 4.09 to 1.82 mg/dL; P < 0.001), γ-glutamyl transpeptidase (P = 0.015), triglycerides (P = 0.03) and total cholesterol (P = 0.05). No significant changes in CD4 T cell count and no increases in viral load were observed 12 months after unboosting. Plasma drug monitoring after ritonavir removal revealed the presence of therapeutic atazanavir concentrations in all patients except one with poor therapy adherence. CONCLUSIONS UGT1A1*28 is significantly related to hyperbilirubinaemia in HIV-1 patients receiving atazanavir. Genotyping before the initiation of antiretroviral therapy can reduce the emergence of severe hyperbilirubinaemia. Unboosted atazanavir-containing therapy is safe and efficacious in patients with an undetectable viral load with a UGT1A1*28 polymorphism, allowing the use of atazanavir in patients otherwise likely unable to receive it.

Comparative evaluation of seven resistance interpretation algorithms and their derived genotypic inhibitory quotients for the prediction of 48 week virological response to darunavir-based salvage regimens

BACKGROUND the darunavir genotypic inhibitory quotient (gIQ) has been suggested as one of the predictors of virological response to darunavir-containing salvage regimens. Nevertheless, which resistance algorithm should be used to optimize the calculation of gIQ is still debated. The aim of our study was to compare seven different free-access resistance algorithms and their derived gIQs as predictors of 48 week virological response to darunavir-based salvage therapy in the clinical setting. METHODS patients placed on two nucleoside reverse transcriptase inhibitors + 600/100 mg of darunavir/ritonavir twice daily  ±  enfuvirtide were prospectively evaluated. Virological response was assessed at 48 weeks. Darunavir resistance interpretation was performed according to seven different algorithms, of which two were weighted algorithms. Analysis of other factors potentially associated with virological response at 48 weeks was performed. RESULTS fifty-six treatment-experienced patients were included. Overall, 35 patients (62.5%) had a virological response at 48 weeks. Receiver operator characteristic curve analysis showed that De Meyers weighted score (WS) and its derived gIQ (gIQ WS) were the most accurate parameters defining virological response, and related cut-offs showed the best sensitivity/specificity pattern. In univariate logistic regression analysis, baseline log viral load (P = 0.028), optimized background score ≥ 2 (P = 0.048), WS >5 (P = 0.001) and WS gIQ ≥ 600 (P < 0.0001) were independently associated with virological response. In multivariate analysis, only baseline log viral load (P = 0.008) and WS gIQ ≥ 600 (P < 0.0001) remained in the model. CONCLUSIONS in our study, although different resistance interpretation algorithms and derived gIQs were associated with virological response, gIQ WS was the most accurate predictive model for achieving a successful virological response.

Unusual codon 69 insertions: influence on human immunodeficiency virus type 1 reverse transcriptase drug susceptibility

INTRODUCTION Multiple amino acid changes in the reverse transcriptase (RT) enzyme of the human immunodeficiency virus 1 (HIV-1) confer simultaneous resistance to most nucleoside RT inhibitors (NRTI). It may take place through different pathways: one of these is the codon 69 insertion, which can involve several 2-amino acid patterns. MATERIALS AND METHODS We are reporting the case of three patients treated with various antiretroviral compounds. For these subjects we have conducted both a genotypical and a phenotypical analysis in order to understand what kind of influence these insertions may have on HIV-1 RT drug susceptibility. Plasma samples from these patients have been extracted and the RT region has been amplified, cloned and sequenced; meanwhile their PBMCs have been separated, cultivated and then tested for drug susceptibility. RESULTS Data obtained from the cloning assay showed that the patients had different mutational patterns but constant multiple resistance to NRTI. In particular, they harbored mutations related to Zidovudine (ZDV), 3TC and various NRTIs. Moreover, all three samples had a T69S substitution followed by three different dual amino acid insertions: SG, TG and VG. Several phenotypic experiments revealed that the viruses were resistant to 3TC as well as to ZDV and ABC. Different results were obtained using d4T and ddI. DISCUSSION In our three patients, all mutation inserts impaired the use of NRTI, particularly ZDV and 3TC. Patient 001 presented a pattern that should not cause a high phenotypic resistance to 3TC per se, and so we can argue that the concomitant presence of the insertion T69S (SG) makes this isolate moderately resistant to this drug. We observed a similar phenomenon in subject 003. d4T was less involved in the resistance generation caused by the RT insertion (in one out of three cases). Moreover, we identified a new 2aa insertion (TG) that has, to the best of our knowledge, never been reported before. A careful survey of novel RT genotypic insertion is thus warranted.

Letter to the Editor: Successful Rescue Therapy with Raltegravir (MK-0518) and Etravirine (TMC125) in an HIV-Infected Patient Failing All Four Classes of Antiretroviral Drugs

It is mandatory to find antiretroviral therapies that offer increased efficacy in treatmentexperienced patients with HIV-1 infection, a population whose extensive drug resistance restricts treatment options and has a severe effect on infection management.1 The aim in salvage therapy in patients who were highly treatmentexperienced and in whom multiple regimens had failed was so far limited to the new protease inhibitors (PI) and combination with enfuvirtide.2,3 The new antiretrovirals currently in expanded access programs, such as raltegravir and etravirine, show unprecedented level of virologic efficacy. Raltegravir, formerly MK0518, the first integrase inhibitor under clinical development, showed high potency in multidrug-resistant HIV patients including those resistant to currently available antiretroviral drugs.4 Etravirine, formerly TMC-125, a second-generation non-nucleoside reverse transcriptase inhibitor (NNRTI) appears to be effective against a variety of HIV viruses that are resistant to efavirenz and nevirapine.5 Few data are available regarding the performance of these drugs combinations in heavily PI-experienced patients, including those for whom tipranavir, darunavir, and enfuvirtide have failed. Hereby, we describe the outcome of salvage therapy based on raltegravir and etravirine in a heavily antiretroviral-experienced patient. A 37-year-old Caucasian male, CDC status C3, had experienced multiple failures to all current classes of antiretroviral agents. Specifically, he had failed eight ritonavir-boosted PI combinations, including tenofovir-lamivudine-enfuvirtide-tipranavir/ritonavir, given in May 2004 with replacement of the latest with darunavir/ritonavir in December 2006. Plasma HIV-RNA levels were measured at baseline and during therapy using a commercial assay, the Versant HIV-1 RNA 3.0 Assay (bDNA; Siemens Medical Solutions Diagnostics, Malvern, PA), with a dynamic range of 50–500,000 HIV-1 RNA copies per milliliter. CD4 cell count was determined by direct immunofluorescence in flow cytometry (Beckman Coulter, Fullerton, CA). Genetic analysis of the pol gene including both HIV-1 reverse transcriptase (codons 4-99) and protease (codons 35-247) regions was performed using the Trugene HIV-1 Genotyping Kit (Siemens Medical Solutions Diagnostics).

New HIV protease inhibitors for drug-resistant viruses

Several second-generation protease inhibitors have been developed over the last few years. These compounds have been used in preregistrative clinical trials or are currently in various Phases (I, II or III) of their progress towards use in HIV-1-infected patients. All drugs in this category have been designed in order to reach high plasma levels and possibly overcome the issue of cross-resistance among the compounds belonging to this class. Taking into account the rapid occurrence of protease inhibitor cross-resistance, clinicians who are treating patients living with HIV/AIDS will need new active protease inhibitors in the near future. These newly developed compounds will be the subject of our review.

Efficacy, Tolerability and Virological Consequences of Long-Term Use of Unboosted Atazanavir Plus 2 NRTIs in HIV-Infected Patients

PURPOSE Switch to unboosted atazanavir (ATV) is an attractive option due to convenience and tolerability in HIV-positive patients. With limited available data we investigated the determinants of long-term efficacy and the consequences of virological failure of unboosted atazanavir-based regimens. METHODS Retrospective analysis in two Italian large outpatient clinics including demographic, immunovirological, resistance and pharmacokinetic data. RESULTS 249 patients receiving atazanavir (400 mg once-daily) plus 2 NRTIs were included; 163 were males (65.5%) and median age was 47 years (42-51.5). Median CD4+ T-cell count was 396/uL (261-583); 146 (58.6%) presented a viral load < 50 copies/mL. Over a median follow up of 157 weeks (106-203) 193 patients (77.5%) were still on treatment with 10 (4%) and 2 (0.8%) stopping for virological failure or toxicity, respectively. Ten patients with virological failure presented newly selected resistance associated mutations (RAMs) for NRTIs (2/10) or ATV (4/10, one I50L). Total cholesterol and triglycerides showed significant decreases at 48 [-4 mg/dL and -41 mg/dL] and 96 weeks [-14 mg/dL and -54 mg/dL] as compared to baseline. At multivariate analysis a genotypic sensitivity score ≤ 1, atazanavir RAMs > 1 and suboptimal adherence were independently associated with virological failure; in lamivudine/emtricitabine-treated patients the presence of M184V (without other NRTI RAMs) was not associated with virological failure. CONCLUSION Unboosted-atazanavir containing regimens were efficacious (with uncommon virological failures) and well-tolerated (with improvements in lipid profile over time) treatments in HIV-positive patients. Isolated M184V in lamivudine/emtricitabine recipients was not associated with higher failure rates supporting the use of functional ATV-based dual therapies as maintenance strategies.

New Macrocyclic Amines Showing Activity as HIV Entry Inhibitors Against Wild Type and Multi-Drug Resistant Viruses

Considering as a lead molecule the chemokine CXCR4 receptor antagonist AMD-3100, which shows significant anti-HIV activity in vitro and in vivo, we investigated a series of structurally related macrocyclic polyamines incorporating o,o’-phenanthroline or 2,2’-bipyridyl scaffolds as potential antiviral agents with lower toxicity and increased activity against both wild type X4-tropic and dual tropic HIV strains. The antiviral activity of these compounds was evaluated by susceptibility assays in PBMC (Peripheral Blood Mononuclear Cells) and compared to that of AMD-3100. The newly investigated compounds showed IC50s values in the low micromolar range and significantly inhibited the viral replication of wild type X4-tropic isolate and dual tropic strains. These macrocyclic polyamines constitute a promising class of HIV entry inhibitors.

Efficacy and safety of a dual boosted protease inhibitor-based regimen, atazanavir and fosamprenavir/ritonavir, against HIV: experience in a pediatric population

BackgroundAlthough dual-boosted protease inhibitors regimen is not recommended in children with HIV infection, such a strategy could be useful in subjects with a complex resistance profile. This study was aimed at assessing the long term efficacy and safety of a double-boosted protease inhibitor combination, fosamprenavir (fAVP) and atazanavir/ritonavir (ATV/r) in a cohort of HIV-infected children and adolescents who had failed with nucleoside reverse transcriptase inhibitors.MethodsSeven vertically infected children and adolescents who had previously failed highly active antiretroviral therapy and were resistant to nucleoside reverse transcriptase inhibitors, received a dual protease inhibitor (PI) regimen including fAVP plus ATV/r for 42 months. The patients were assessed at baseline, every month for the first 24 weeks of therapy and every 3 months until month 32. Physical examination, CD4+ cell count, HIV-RNA viral load, lipid profile and hepatic function were assessed throughout the follow up.ResultsDuring the study no serious adverse events were reported. CD4 absolute number increased over-time in all subjects. At baseline the median HIV-RNA was 6562 cp/mL (ranging 1048 -102772 cp/mL) and rapidly decreased below the limit of detection (50 cp/mL) after 2 months of the new treatment and remained undetectable in all cases through the entire study period. At the beginning of the study all cases showed a normal lipid profile. During the study period, 4/7 subjects showed total cholesterol, low density lipoprotein and triglyceride levels >97th cent.le for the males and 94th cent.le for the females. HDL cholesterol showed protective values. Hepatic enzymes remained stable during the entire observation, whereas total bilirubin showed toxicity II/III grade in 6/7 subjects. No change in fat redistribution and insulin resistance was observed.ConclusionDual-boosted protease inhibitor therapy was virologically and immunologically effective and it could be considered as a possible alternative to a rescue regimen in children and adolescents. However, hypercholesterolemia and hypertriglyceridemia need close follow-up and may limit the use of this therapeutic option.

Does GSS Still Maintain Relevance on HAART Outcome After the Introduction of Newest Active Antiretroviral Drugs? 48 Weeks Results

BACKGROUND Since recent observations demonstrated that extended resistance to protease inhibitors, nucleosidic and non - nucleosidic retrotranscriptase inhibitors (PI, NRTI, NNRTI) is a marker of disease progression and death, it is a matter of the greatest importance that experienced human immunodeficiency virus (HIV) - infected patients with limited therapeutic options receive a suppressive therapy pending the availability of at least two new antiretroviral drugs. Aim of the present study is to evaluate if the GSS score, calculated by analyzing the resistance to historical antiretroviral drugs and drug classes, is still relevant since several new potent drugs and drug classes entered the current clinical use. METHODS Taking into account patients without suppression of HIV replication for ≥ 6 months from October 2008 and October 2009, we analyzed viroimmunological and resistance data of 38 outpatients starting their last antiretroviral regimen including at least one of the following: maraviroc, enfuvirtide, raltegravir, etravirine, darunavir/ritonavir or tipranavir/ritonavir. Mutations present in all available genotypic resistance tests were recorded for each patient and then correlated to GSS value, assessed using the last genotypic ribonucleic acid (RNA) resistance test. GSS was studied as predictor of virological treatment outcome by univariate and multivariate logistic regression. RESULTS At 48 weeks, undetectable viral load was obtained in 80% of patients without difference between GSS classes (HIV-RNA median < 50 copies/ml); 95.8% of patients with baseline HIV-RNA < 50,000 copies/ml obtained virological suppression (p=0.003). 48 weeks CD4+ median value was 412 cells/μl considering GSS1 and 300 cells/μl for combined GSS2 and GSS3 scores. Data also showed a > 60% recurrence of specific mutations for NRTI: M41L, M184IV, L210W, T215FY, K219EQ and 75% for D67N. K103N and Y181CIV mutations for NNRTI persisted in 35% of cases and their prevalence incresed in parallel with the number of GRTs. About 60% of tests reported L10FIRVC, M36ILV, M46IL, I54VLAMTS, V82AFTSLI, and L90M mutations in the protease region. 63P mutation was found in a total number of GRTs close to 80%. This percentages, when correlated to GSS, revealed a distinct pattern for most mutations, that showed a greater prevalence for GSS = 2. Conversely, only NNRTI 181CIV and NRTI 210W showed larger numbers in GSS1 and GSS3. CONCLUSIONS Single drugs belonging to new antiretroviral classes did not correlate to viroimmunological success for any GSS. High frequency and recurrence over GRTs for specific mutations confirm their key role following the exposure to ARVs classes. A baseline HIV-RNA < 50,000 cp/ml is a predictor of therapeutic success and a carefully selected HAART based upon the evaluation of GRTs can favorably influence the immunovirologic response.

Analysis of determinants of long-term efficacy of unboosted atazanavir-based regimens in the clinical setting

7‐11 November 2010, Tenth International Congress on Drug Therapy in HIV Infection, Glasgow, UK