Phase 2 double-blind, randomized trial of etravirine versus efavirenz in treatment-naive patients: 48-week results

Once-daily etravirine/raltegravir (400/800 mg q24h) dual therapy maintains viral suppression over 48 weeks in HIV-infected patients switching from a twice-daily etravirine/raltegravir (200/400 mg q12h) regimen

BACKGROUND

Etravirine/raltegravir dual therapy has been shown to be highly effective as a twice-daily (q12h) regimen in suppressed HIV-infected patients enrolled in the ANRS-163 study.

OBJECTIVES

As a once-daily (q24h) regimen is easier for daily life, we aimed to evaluate the capacity of etravirine/raltegravir (400/800 mg) q24h to maintain viral suppression in patients on etravirine/raltegravir q12h.

METHODS

Patients on a suppressive etravirine/raltegravir q12h regimen for at least 96 weeks were switched to etravirine/raltegravir q24h in this prospective, multicentre, open-label, single-arm study. Primary outcome was the rate of virological failure (VF: confirmed pVL >50 copies/mL, single pVL >400 copies/mL or single pVL >50 copies/mL with ART change) at Week 48 (W48). Secondary outcomes included treatment strategy success rate (no VF and no treatment discontinuation), regimen tolerability, plasma drug concentrations and resistance profile in the case of VF.

RESULTS

A total of 111 patients were enrolled, with a median (IQR) age of 57 years (52-62), CD4 count of 710 cells/mm3 (501-919) and viral suppression for 7.9 years (5.9-10.7). Two patients experienced viral rebound at W24 and W48, leading to a VF rate of 2.0% (95% CI 0.5-7.8) at W48, associated with INSTI resistance in one case. Both had past NNRTI mutations. Ten patients discontinued treatment for adverse events (n = 2), investigator or patient decisions (n = 3), lost to follow-up (n = 3), death (n = 1) or pregnancy (n = 1). Overall, the strategy success rate was 89% (95% CI 81.5-93.6) at W48. In a subgroup of 64 patients, median (IQR) plasma C24h concentrations were 401 ng/mL (280-603) for etravirine and 62 ng/mL (31-140) for raltegravir.

CONCLUSIONS

Switching patients virally suppressed on etravirine/raltegravir q12h to the same regimen but given q24h was highly effective in maintaining virological suppression in HIV-infected patients.

Clinical Pharmacokinetics and Pharmacodynamics of Etravirine: An Updated Review

Etravirine is a second-generation non-nucleoside reverse transcriptase inhibitor (NNRTI) for the treatment of human immunodeficiency virus type 1 infection. It is a potent inhibitor of HIV reverse transcriptase and retains activity against wild-type and most NNRTI-resistant HIV. The pharmacokinetic profile of etravirine and clinical data support twice-daily dosing, although once-daily dosing has been investigated in treatment-naïve and treatment-experienced persons. Despite similar pharmacokinetic and pharmacodynamic results compared with twice-daily dosing, larger studies are needed to fully support once-daily etravirine dosing in treatment-naïve individuals. Etravirine is reserved for use in third- or fourth-line antiretroviral treatment regimens, as recommended, for example, in treatment guidelines by the US Department of Health and Human Services-Guidelines for the Use of Antiretroviral Agents in Adults and Adolescents Living with HIV. Etravirine exhibits the potential for bi-directional drug-drug interactions with other antiretrovirals and concomitant medications through its interactions with cytochrome P450 (CYP) isozymes: CYP3A4, CYP2C9, and CYP2C19. This review summarizes the pharmacokinetic and pharmacodynamic parameters of etravirine, with particular attention to information on drug-drug interactions and use in special patient populations, including children/adolescents, women, persons with organ dysfunction, and during pregnancy.

Efficacy, pharmacokinetics and neurocognitive performance of dual, NRTI-sparing antiretroviral therapy in acute HIV-infection

OBJECTIVES

The aim of this study was to evaluate penetration of antiretrovirals into compartments and efficacy of a dual, NRTI-sparing regimen in acute HIV infection (AHI).

DESIGN

Single-arm, open-label pilot study of participants with AHI initiating ritonavir-boosted darunavir 800 mg once daily and etravirine 400 mg once daily or 200 mg twice daily within 30 days of AHI diagnosis.

METHODS

Efficacy was defined as HIV RNA less than 200 copies/ml by week 24. Optional sub-studies included pharmacokinetics analysis from genital fluids (weeks 0-4, 12, 48), cerebrospinal fluid (CSF) (weeks 2-4, 24 and 48) and endoscopic biopsies (weeks 4-12 and 36-48). Neuropsychological performance was assessed at weeks 0, 24 and 48.

RESULTS

Fifteen AHI participants were enrolled. Twelve (80%) participants achieved HIV RNA less than 200 copies/ml by week 24. Among 12 participants retained through week 48, nine (75%) remained suppressed to less than 50 copies/ml. The median time from ART initiation to suppression less than 200 and less than 50 copies/ml was 59 and 86 days, respectively. The penetration ratios for etravirine and darunavir in gut associated lymphoid tissue were 19.2 and 3.05, respectively. Most AHI participants achieving viral suppression experienced neurocognitive improvement. Of the three participants without overall improvement in neurocognitive functioning as measured by impairment ratings (more than two tests below 1 SD), two had virologic failure.

CONCLUSION

NRTI-sparing ART started during AHI resulted in rapid viral suppression similar to NRTI-based regimens. More novel and compact two-drug treatments for AHI should be considered. Early institution of ART during AHI appears to improve overall neurocognitive function and may reduce the risk of subsequent neurocognitive impairment. CLINICALTRIALS.GOV:: NCT00855413.

Non-Nucleoside Reverse Transcriptase Inhibitors Join Forces with Integrase Inhibitors to Combat HIV

In the treatment of acquired immune deficiency syndrome (AIDS), the diarylpyrimidine (DAPY) analogs etravirine (ETR) and rilpivirine (RPV) have been widely effective against human immunodeficiency virus (HIV) variants that are resistant to other non-nucleoside reverse transcriptase inhibitors (NNRTIs). With non-inferior or improved efficacy, better safety profiles, and lower doses or pill burdens than other NNRTIs in the clinic, combination therapies including either of these two drugs have led to higher adherence than other NNRTI-containing treatments. In a separate development, HIV integrase strand transfer inhibitors (INSTIs) have shown efficacy in treating AIDS, including raltegravir (RAL), elvitegravir (EVG), cabotegravir (CAB), bictegravir (BIC), and dolutegravir (DTG). Of these, DTG and BIC perform better against a wide range of resistance mutations than other INSTIs. Nevertheless, drug-resistant combinations of mutations have begun to emerge against all DAPYs and INSTIs, attributable in part to non-adherence. New dual therapies that may promote better adherence combine ETR or RPV with an INSTI and have been safer and non-inferior to more traditional triple-drug treatments. Long-acting dual- and triple-therapies combining ETR or RPV with INSTIs are under study and may further improve adherence. Here, highly resistant emergent mutations and efficacy data on these novel treatments are reviewed. Overall, ETR or RPV, in combination with INSTIs, may be treatments of choice as long-term maintenance therapies that optimize efficacy, adherence, and safety.

Current and emerging non-nucleoside reverse transcriptase inhibitors (NNRTIs) for HIV-1 treatment

Introduction: Non-nucleoside reverse transcriptase inhibitors (NNRTIs) are essential components of highly active antiretroviral therapy against HIV-1 infections. Here, we provide a comprehensive overview of approved and emerging NNRTIs. Areas covered: This review covers the latest trend of NNRTIs regarding their pharmacodynamics, pharmacokinetics, mechanisms of drug action, drug resistance as well as new applications such as two-drug regimens and long-acting formulations. Expert opinion: Since the first NNRTI, nevirapine, was approved in 1996, antiviral drug discovery led to the approval of seven NNRTIs, including nevirapine, delavirdine (discontinued), etravirine, elsulfavirine, efavirenz, rilpivirine, and doravirine. The latter three compounds with favorable pharmacodynamic profiles and minimal adverse effects are often combined with one integrase inhibitor or two NRTIs in once-daily fixed-dose tablets. NNRTI-anchored regimens have been approved as initial therapies in treatment-naïve patients (efficacy: 72% to 86%) or maintaining therapies in virologically-suppressed patients (efficacy: 91% to 95%). Future development of NNRTIs includes: (i) better resistance and cross-resistance profiles; (ii) reduction of drug burden by optimizing two-drug or three-drug combinations; and (iii) improvement of patient adherence by novel long-acting formulations with weekly or monthly administration. Overall, NNRTIs play an important role in the management of HIV-1 infections, especially in resource-limited countries.

Synthetic routes and structure-activity relationships (SAR) of anti-HIV agents: A key review

The worldwide increase of AIDS, an epidemic infection in constant development has an essential and still requires potent antiretroviral chemotherapeutic agents for reducing the integer of deaths caused by HIV. Thus, there is an urgent need for new anti-HIV drug candidates with increased strength, new targets, superior pharmacokinetic properties, and compact side effects. From this viewpoint, we first review present strategies of anti-HIV drug innovation and the synthesis of heterocyclic or natural compound as anti-HIV agents for facilitating the development of more influential and successful anti-HIV agents.

Pharmacokinetics of darunavir/cobicistat and etravirine alone and co-administered in HIV-infected patients

Objectives

To determine the effect of etravirine on the pharmacokinetics of darunavir/cobicistat and vice versa. Safety and tolerability of this combination were also evaluated.

Methods

Open-label, fixed-sequence trial in two cohorts of HIV-infected patients on therapy with darunavir/cobicistat 800/150 mg once daily (DRV cohort; n = 15) or etravirine 400 mg once daily (ETR cohort; n = 15). Etravirine or darunavir/cobicistat were added on days 1-14 and 1-7 in participants in the DRV or ETR cohort, respectively. Full pharmacokinetic profiles were obtained on days 0 and 14 in the DRV cohort, and on days 0 and 7 in the ETR cohort. Darunavir, cobicistat and etravirine pharmacokinetic parameters [AUC0-24, Cmax and trough concentrations in plasma (C24)] were calculated for each individual by non-compartmental analysis and were compared using linear mixed-effects models. Adverse events and HIV-1 RNA in plasma were monitored.

Results

Etravirine co-administration decreased cobicistat AUC0-24, Cmax and C24 by 30%, 14% and 66%, respectively. Although darunavir AUC0-24 and Cmax were unchanged by etravirine, darunavir C24 was 56% lower for darunavir/cobicistat co-administered with etravirine relative to darunavir/cobicistat alone. Etravirine pharmacokinetics were unchanged by darunavir/cobicistat. Treatments were well tolerated, and HIV-1 RNA remained undetectable in all participants.

Conclusions

Although etravirine pharmacokinetics was unchanged by darunavir/cobicistat, there was a significant decrease in cobicistat exposure and in darunavir C24 when darunavir/cobicistat was co-administered with etravirine. Boosting darunavir with ritonavir instead of with cobicistat may be preferred if darunavir is to be combined with etravirine in clinical practice.

Efavirenz: What is known about the cellular mechanisms responsible for its adverse effects

The HIV infection remains an important health problem worldwide. However, due to the efficacy of combined antiretroviral therapy (cART), it has ceased to be a mortal condition, becoming a chronic disease instead. Efavirenz, the most prescribed non-nucleoside analogue reverse transcriptase inhibitor (NNRTI), has been a key component of cART since its commercialization in 1998. Though still a drug of choice in many countries, its primacy has been challenged by the arrival of newer antiretroviral agents with better toxicity profiles and treatment adherence. The major side effects related to EFV have been widely described in clinical studies, however the mechanisms that participate in their pathogenesis remain largely ununderstood. This review provides an insight into the cellular and molecular mechanisms responsible for the development of the most significant undesired effects induced by efavirenz, both short- and long-term, revealed by in vitro and in vivo experimental pharmacological research. Growing evidence implicates the drug in energy metabolism, mitochondrial function, and other cellular processes involved in stress responses including oxidative stress, inflammation and autophagy.

Cytochrome 2B6 polymorphism and efavirenz-induced central nervous system symptoms : a substudy of the ANRS ALIZE trial

OBJECTIVES

Single nucleotide polymorphisms in the cytochrome P450 (CYP) 2B6 gene have been associated with high interindividual variation in efavirenz pharmacokinetics. However, clinical data on the relationship of CYP2B6 polymorphisms with the occurrence of efavirenz-induced central nervous system (CNS) symptoms are limited.

METHODS

We analysed four polymorphisms in the CYP2B6 (516 G>T), CYP3A5 (6986 A>G) and ATP-binding cassette, sub-family B, member 1 (ABCB1) (2677 G>T/A and 3435 C>T) genes in HIV-infected adults virologically suppressed on a protease inhibitor-based regimen who switched to a regimen containing emtricitabine, didanosine and efavirenz in the setting of the ANRS ALIZE trial. Kaplan-Meier methods and Cox regression analysis were used to investigate their association with efavirenz plasma levels and CNS events up to 48 months after switching.

RESULTS

In total, 191 patients with a median age of 41 years, who were 87% male and 85% Caucasian, were enrolled in the study. Variant allelic frequencies were 0.49, 0.93, 0.59 and 0.63 for CYP2B6 516, CYP3A5 392, ABCB1 2677 and ABCB1 3435, respectively. The median efavirenz plasma concentration (MEPC) was 2.2 mg/L [interquartile range (IQR) 1.7-2.8 mg/L] and was significantly higher in patients with the deficient CYP2B6 516T. Overall, 242 CNS events were reported in 104 individuals (54%). No correlation was found between MEPC and CNS events. The occurrence of a first CNS event was lower in patients with the CYP2B6 516 G/G genotype vs. CYP2B6 516 T genotypes [50% (IQR: 40-60%) vs. 66% (IQR: 56-75%), respectively; P = 0.02]. In an adjusted Cox regression model, there was a tendency towards a higher risk of a first CNS event among carriers of the variant CYP2B6 516 T allele (relative risk 1.4 [95% CI, 0.99-2.1]; P?=?.06), compared with noncarriers.

CONCLUSIONS

The deficient CYP2B6 516 T allele is associated with higher efavirenz plasma drug levels and more frequent CNS-related symptoms.

Comparative Safety and Neuropsychiatric Adverse Events Associated With Efavirenz Use in First-Line Antiretroviral Therapy: A Systematic Review and Meta-Analysis of Randomized Trials

INTRODUCTION

Efavirenz (EFV) is widely used for the treatment of antiretroviral-naive HIV-positive individuals, but there are concerns about the risk of adverse neuropsychiatric events. We systematically reviewed the safety of EFV in first-line therapy.

METHODS

Four databases were searched until October 2014 for randomized trials comparing EFV against non-EFV-based regimens for the treatment of antiretroviral-naive HIV-positive adults and children. The primary outcome was drug discontinuation as a result of any adverse event. Relative risks and proportions were pooled using random-effects meta-analysis.

RESULTS

Forty-two trials were included for review. A lower relative and absolute risk of discontinuations due to adverse drug reactions was seen with EFV compared to nevirapine. The relative and absolute risk of discontinuation was greater for EFV compared with low-dose EFV, rilpivirine, tenofovir, atazanavir, and maraviroc. The relative risk of discontinuation was greater for EFV compared with dolutegravir and raltegravir, but absolute risks were not significantly different. There was no difference in the risk of any severe clinical adverse events for any comparison. With the exception of dizziness, fewer than 10% of patients exposed to EFV experienced any other specific type of neuropsychiatric event. No suicides were reported.

CONCLUSIONS

This review found that over 90% of patients remained on an EFV-based first-line regimen after an average follow-up time of 78 weeks. The relative risk of discontinuations due to adverse events was higher for EFV compared with most other first-line options, but absolute differences were less than 5% for all comparisons.

Antiretroviral activity and safety of once-daily etravirine in treatment-naive HIV-infected adults: 48-week results

BACKGROUND

Etravirine (ETR), a non-nucleoside reverse transcriptase inhibitor approved for 200 mg twice-daily dosing in conjunction with other antiretrovirals (ARVs), has pharmacokinetic properties which support once-daily dosing.

METHODS

In this single-arm, open-label study, 79 treatment-naive HIV-infected adults were assigned to receive ETR 400 mg plus tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) 300/200 mg once daily to assess antiviral activity, safety and tolerability. ARV activity at 48 weeks was determined by proportion of subjects with HIV-1 RNA<50 copies/ml (intention-to-treat, missing = failure).

RESULTS

Of 79 eligible subjects, 90% were men, 62% African-American and 29% Caucasian. At baseline, median (Q1, Q3) age was 29 years (23, 44) and HIV-1 RNA 4.52 log10 copies/ml (4.07, 5.04). A total of 69 (87%) completed a week 48 visit and 61 (77%, 95% CI 66%, 86%) achieved HIV-1 RNA<50 copies/ml at week 48. At time of virological failure, genotypic resistance-associated mutations were detected in three participants, two with E138K (one alone and one with additional mutations). Median (95% CI) CD4(+) cell count increase was 163 (136, 203) cells/µl. Fifteen (19.0%) participants reported a new sign/symptom or lab abnormality ≥ Grade 3 and three participants (3.8%) permanently discontinued ETR due to toxicity. Two participants had psychiatric symptoms of any grade. There were no deaths.

CONCLUSIONS

In this study of ARV-naive HIV-positive adults, once-daily ETR with TDF/FTC had acceptable antiviral activity and was well-tolerated. Once-daily ETR may be a plausible option as part of a combination ARV regimen for treatment-naive individuals. ClinicalTrials.gov NCT00959894.

Efavirenz and the CNS: what we already know and questions that need to be answered

The NNRTI efavirenz has long been one of the most frequently employed antiretroviral drugs in the multidrug regimens used to treat HIV infection, in accordance with its well-demonstrated antiretroviral efficacy and favourable pharmacokinetics. However, growing concern about its adverse effects has sometimes led to efavirenz being replaced by other drugs in the initial treatment selection or to switching of therapy to efavirenz-free regimens in experienced patients. Neurological and neuropsychiatric reactions are the manifestations most frequently experienced by efavirenz-treated patients and range from transitory effects, such as nightmares, dizziness, insomnia, nervousness and lack of concentration, to more severe symptoms including depression, suicidal ideation or even psychosis. In addition, efavirenz has recently been associated with mild/moderate neurocognitive impairment, which is of specific relevance given that half of the patients receiving ART eventually suffer some form of HIV-associated neurocognitive disorder. The mechanisms responsible for efavirenz-induced neurotoxicity are unclear, although growing evidence points to disturbances in brain mitochondrial function and bioenergetics. This review offers a comprehensive overview of the current evidence on the interaction that efavirenz displays with the CNS, including the penetration and concentration of the drug in the brain. We discuss the prevalence, types and specificities of its side effects and recently uncovered cellular mechanisms that may be involved in their development.

Liver toxicity and risk of discontinuation in HIV/hepatitis C virus-coinfected patients receiving an etravirine-containing antiretroviral regimen: influence of liver fibrosis

OBJECTIVES

The aim of the study was to establish the risk of liver toxicity in HIV/hepatitis C virus (HCV)-coinfected patients receiving etravirine, according to the degree of liver fibrosis.

METHODS

A prospective cohort study of 211 HIV-infected patients initiating an etravirine-containing regimen was carried out. HCV coinfection was defined as a positive HCV RNA test, and baseline liver fibrosis was assessed by transient elastography. Hepatotoxicity was defined as clinical symptoms, or an aspartate aminotransferase (AST) or alanine aminotransferase (ALT) value > 5-fold higher than the upper limit of normal if baseline values were normal, or 3.5-fold higher if values were altered at baseline.

RESULTS

Overall, 145 patients (69%) were HCV coinfected, with a lower nadir (165 versus 220 cells/μL, respectively; p = 0.03) and baseline (374 versus 498 cells/μL, respectively; p = 0.04) CD4 count than monoinfected patients. Etravirine was mainly used with two nucleoside reverse transcriptase inhibitors (129; 61%) or with a boosted protease inhibitor (PI) (28%), with no significant differences according to HCV serostatus. Transient elastography in 117 patients (81%) showed a median (range) stiffness value of 8.25 (3.5-69) kPa, with fibrosis stage 1 in 43 patients (37%) and fibrosis stage 4 in 28 patients (24%). During an accumulated follow-up time of 449.3 patient-years (median 548 days), only one patient with advanced fibrosis (50.8 kPa) had grade 3-4 liver toxicity (0.7%). Transaminases changed slightly, with no significant differences compared with baseline fibrosis, and nine and six patients had grade 1 and 2 transaminase increases, respectively. Also, HCV coinfection was not associated with a higher risk of discontinuation (25% discontinued versus 21% of monoinfected patients; p = 0.39, log-rank test) or virological failure (8% versus 12%, respectively; p = 0.4).

CONCLUSIONS

Our data suggest that etravirine is a safe option for HIV/HCV-coinfected patients, including those with significant liver fibrosis.

Efavirenz-Based Regimens in Antiretroviral-Naive HIV-Infected Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Efavirenz, a non-nucleoside reverse-transcriptase inhibitor (NNRTI) is one of the most commonly prescribed antiretroviral drugs. The present article provides a systematic overview and meta-analysis of clinical trials comparing efavirenz and other active drugs currently recommended for treatment of HIV-infected, antiretroviral-naive patients. Electronic databases (Pubmed, Embase, the Cochrane Library, Trip Database) were searched up till 23 December 2013 for randomized controlled clinical trials published as a peer-reviewed papers, and concerning efavirenz-based regimens used as initial treatment for HIV infection. Thirty-four studies were included in the systematic review, while twenty-six trials were suitable for the meta-analysis. Efavirenz was compared with drugs from four different classes: NNRTIs other than efavirenz (nevirapine or rilpivirine), integrase strand transfer inhibitors (InSTIs), ritonavir-boosted protease inhibitors (bPI) and chemokine (C-C motif) receptor 5 (CCR5) antagonists (maraviroc), all of them were added to the background regimen. Results of the current meta-analysis showed that efavirenz-based regimens were equally effective as other recommended regimens based on NNRTI, ritonavir-boosted PI or CCR5 antagonist in terms of efficacy outcomes (disease progression and/or death, plasma viral HIV RNA <50 copies/ml) while statistically significant more patients treated with InSTI achieved plasma viral load <50 copies/ml at week 48. In comparison with both InSTI-based and CCR5-based therapy, efavirenz-based treatment was associated with a higher risk of therapy discontinuation due to adverse events. However, comparisons of efevirenz-based treatment with InSTI-based and CCR5-based therapy were based on a limited number of trials, therefore, conclusions from these two comparisons must be confirmed in further reliable randomized controlled studies. Results of our meta-analysis support the present clinical guidelines for antiretroviral-naive, HIV-infected patients, in which efavirenz is one of the most preferred regimens in the analyzed population. Beneficial safety profile of InSTI-based and CCR5-based therapy over efavirenz-based treatment needs further studies.

Differential activation of human constitutive androstane receptor and its SV23 and SV24 splice variants by rilpivirine and etravirine

BACKGROUND AND PURPOSE

Rilpivirine and etravirine are second-generation non-nucleoside reverse transcriptase inhibitors (NNRTIs) indicated for the treatment of HIV/AIDS. The constitutive androstane receptor (CAR) regulates the expression of genes involved in various biological processes, including the transport and biotransformation of drugs. We investigated the effect of rilpivirine and etravirine on the activity of the wild-type human CAR (hCAR-WT) and its hCAR-SV23 and hCAR-SV24 splice variants, and compared it with first-generation NNRTIs (efavirenz, nevirapine, and delavirdine).

EXPERIMENTAL APPROACH

Receptor activation, ligand-binding domain (LBD) transactivation, and co-activator recruitment were investigated in transiently transfected, NNRTI-treated HepG2 cells. Nuclear translocation of green fluorescent protein-tagged hCAR-WT and CYP2B6 gene expression were assessed in NNRTI-treated human hepatocytes.

KEY RESULTS

Rilpivirine and etravirine activated hCAR-WT, but not hCAR-SV23 or hCAR-SV24, and without transactivating the LBD or recruiting steroid receptor coactivators SRC-1, SRC-2, or SRC-3. Among the first-generation NNRTIs investigated, only efavirenz activated hCAR-WT, hCAR-SV23, and hCAR-SV24, but none of them transactivated the LBD of these receptors or substantively recruited SRC-1, SRC-2, or SRC-3. Rilpivirine, etravirine, and efavirenz triggered nuclear translocation of hCAR-WT and increased hCAR target gene (CYP2B6) expression.

CONCLUSION AND IMPLICATIONS

NNRTIs activate hCAR-WT, hCAR-SV23, and hCAR-SV24 in a drug-specific and isoform-selective manner. The activation occurs by a mechanism that does not appear to involve binding to the LBD or recruitment of SRC-1, SRC-2, or SRC-3.

The Intelence aNd pRezista Once A Day Study (INROADS): a multicentre, single-arm, open-label study of etravirine and darunavir/ritonavir as dual therapy in HIV-1-infected early treatment-experienced subjects

OBJECTIVES

Following antiretroviral therapy failure, patients are often treated with a three-drug regimen that includes two nucleoside/tide reverse transcriptase inhibitors [N(t)RTIs]. An alternative two-drug nucleoside-sparing regimen may decrease the pill burden and drug toxicities associated with the use of N(t)RTIs. The Intelence aNd pRezista Once A Day Study (INROADS; NCT01199939) evaluated the nucleoside-sparing regimen of etravirine 400 mg with darunavir/ritonavir 800/100 mg once-daily in HIV-1-infected treatment-experienced subjects or treatment-naïve subjects with transmitted resistance.

METHODS

In this exploratory phase 2b, single-arm, open-label, multicentre, 48-week study, the primary endpoint was the proportion of subjects who achieved HIV-1 RNA < 50 copies/mL at week 48 [confirmed virological response (CVR), non-virological failure (VF) censored]. Key secondary endpoints included assessments of changes from baseline to week 48 in viral load, immunological response, pharmacokinetics/pharmacodynamics, safety, tolerability, metabolic and bone markers and body fat.

RESULTS

Forty-one of the 54 enrolled subjects completed the study. Adverse events (7%) and VF (7%) were the most common reasons for discontinuation. The week 48 CVR rate in the intent-to-treat (ITT) non-VF censored population was 89% (primary endpoint). Seven subjects experienced VF. Common adverse events were diarrhoea (15%), rash (15%) and upper respiratory tract infection (11%). Mild/moderate lipid elevations, minimal changes in limb fat distribution and bone mineral density and no clinically relevant changes in glucose metabolism were observed.

CONCLUSIONS

Etravirine 400 mg and darunavir/ritonavir 800/100 mg as a two-drug once-daily regimen in treatment-experienced subjects or treatment-naïve subjects with transmitted resistance was virologically efficacious and well tolerated.

Moving away from Ritonavir, Abacavir, Tenofovir, and Efavirenz (RATE)--agents that concern prescribers and patients: a feasibility study and call for a trial

Objectives

Regimens sparing RATE (ritonavir, abacavir, tenofovir, efavirienz) agents might have better long-term safety. We conducted a feasibility exercise to assess the potential for a randomised trial evaluating RATE-sparing regimens.

Design

Observational.

Methods

We first calculated RATE-sparing options available to an average patient receiving RATE agents. We reviewed treatment history and all resistance assays from patients attending the St. Vincent’s Hospital (Sydney) clinic and receiving ≥2 RATE agents (n = 120). A viable RATE-sparing regimen with 2 or 3 fully-active agents was constructed from the following six ‘safer’ agents: rilpivirine or etravirine; atazanavir; raltegravir; maraviroc; and lamivudine. Activity for each drug was predicted as 1 (full-activity), 0.5 or 0 (no activity) using the Stanford mutation database. The utility of maraviroc was calculated assuming both maraviroc activity and inactivity where unknown. The analysis was restricted to regimens for which supporting evidence was identified in the literature or conference proceedings. Finally, we calculated the proportion of patients in the nationally representative Australian HIV Observational Database (AHOD) cohort receiving ≥2 RATE agents (n = 1473) to measure the potential population-level uptake of RATE-sparing agents.

Results

Assuming full maraviroc activity, 117(97.5%) and 107(89.2%) individuals had at least one option with 2 or 3 active RATE-sparing agents, respectively. Assuming no maraviroc activity this decreased to 113(94.2%) and 104(86.7%), respectively. In AHOD, 837(56.8%) patients were receiving ≥2 RATE agents.

Conclusion

Feasible treatment switch options sparing RATE agents exist for the majority of patients. Understanding the pros and cons of switching stable patients onto new RATE-sparing regimens requires evidence derived from randomised controlled trials.

Switching safely: pharmacokinetics, efficacy and safety of switching efavirenz to maraviroc twice daily in patients on suppressive antiretroviral therapy

BACKGROUND

CYP3A4 induction by efavirenz (EFV) persists after drug cessation; we assessed the pharmacokinetics (PK), efficacy and safety of maraviroc (MVC) administered to HIV-infected individuals switching from EFV-containing therapy.

METHODS

Patients with R5-tropic virus and suppressed viral load on two nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) plus EFV switched EFV to MVC 600 mg twice daily for 14 days, and then to MVC 300 mg twice daily. Following screening, three intensive PK visits were performed (sampling was pre-dose and 1, 2, 4, 6, 8 and 12 h post-dose): day 1 (VISIT 1, MVC 600 mg twice daily), day 14 (VISIT 2, steady-state MVC 600 mg twice daily) and day 28 post regimen switch (VISIT 3, steady-state MVC 300 mg twice daily); MVC trough concentration (Ctrough) was determined 3, 6 and 10 days following regimen switch and viral loads up to week 24. MVC PK parameters on visits 1 and 2 and MVC Ctrough on day 6 were compared to visit 3 (reference) via geometric mean ratios (GMR) and 95% CIs.

RESULTS

Twelve males completed the study. MVC PK parameters at visit 1 versus visit 3 were: GMR and 95% CI 12-h area under the curve (AUC0-12) 1.25 (1.00, 1.58); Cmax 1.64 (1.16, 2.31); Ctrough 0.61 (0.46, 0.80). Visit 2 MVC PK parameters were significantly higher than visit 3: GMR and 95% CI AUC0-12 2.31 (1.84, 2.90); Cmax 2.42 (1.87, 3.12); Ctrough 2.25 (1.74, 2.91). MVC was well tolerated with no grade 3/4 adverse events; all subjects maintained viral suppression to the end of the study.

CONCLUSIONS

The EFV induction effect necessitated increased MVC dose to 600 mg twice daily following switch and persisted for approximately one week after EFV cessation. This is less than the 2-week induction observed when switching EFV to etravirine and highlights the importance of studying different tail interactions. Higher dose MVC was well tolerated. All measured MVC Ctrough concentrations exceeded wild-type 90% inhibitory concentration.

When can HIV clinical trials detect treatment effects on drug resistance?

Methods of sampling patients for resistance testing, and statistical analyses of HIV drug resistance, have not been standardised in HIV clinical trials. We analysed methods of genotyping and rates of treatment-emergent drug resistance from 27 clinical trials identified from a MEDLINE search. Sample size calculations were conducted using NQUERY software, assuming 5% significance level, 80% power and 1:1 randomisation. The percentage of patients with treatment-emergent IAS-USA mutations after 96 weeks ranged from 1.8% to 9.1% for first-line 2NRTI/NNRTI treatments, 0.6% to 6.3% for first-line 2NRTI/PI/r treatments and 0.0% to 2.0% in switch trials of boosted PIs. The prevalence of drug resistance was higher in trials with no screening for drug resistance at baseline, where the HIV RNA cut-off for genotyping was >50 copies/mL, where patients were tested for drug resistance after discontinuation of treatment, and where follow-up times were 96 weeks or longer. HIV clinical trials could be designed to detect differences in the risk of HIV drug resistance between treatments, as an analysis supporting HIV RNA suppression as the primary endpoint. However, this would require a standardised approach, with intent-to-treat analyses, testing of all samples with HIV RNA>50 copies/mL and genotyping after drug discontinuation.

Clinical and virological efficacy of etravirine plus two active Nucleos(t)ide analogs in an heterogeneous HIV-infected population

Etravirine (ETV) is recommended in combination with a boosted protease inhibitor plus an optimized background regimen for salvage therapy, but there is limited experience with its use in combination with two nucleos(t)ide reverse-transcriptase inhibitors (NRTIs). This multicenter study aimed to assess the efficacy of this combination in two scenarios: group A) subjects without virologic failure on or no experience with non-nucleoside reverse-transcriptase inhibitors (NNRTIs) switched due to adverse events and group B) subjects switched after a virologic failure on an efavirenz- or nevirapine-based regimen. The primary endpoint was efficacy at 52 weeks analysed by intention-to-treat. Virologic failure was defined as the inability to suppress plasma HIV-RNA to <50 copies/mL after 24 weeks on treatment, or a confirmed viral load >200 copies/mL in patients who had previously achieved a viral suppression or had an undetectable viral load at inclusion. Two hundred eighty seven patients were included. Treatment efficacy rates in group A and B were 88.0% (CI_95, 83.9–92.1%) and 77.4% (CI₉₅, 65.0–89.7%), respectively; the rates reached 97.2% (CI₉₅, 95.1–99.3%) and 90.5% (CI₉₅, 81.7–99.3), by on-treatment analysis. The once-a-day ETV treatment was as effective as the twice daily dosing regimen. Grade 1–2 adverse events were observed motivating a treatment switch in 4.2% of the subjects. In conclusion, ETV (once- or twice daily) plus two analogs is a suitable, well-tolerated combination both as a switching strategy and after failure with first generation NNRTIs, ensuring full drug activity.

Trial registration

ClinicalTrials.gov NCT01437241

Antiretroviral treatment in HIV-1 infected pediatric patients: focus on efavirenz

Efavirenz is a non-nucleoside reverse transcriptase inhibitor (NNRTI), used for the treatment of human immunodeficiency virus (HIV)-1 infection. Approved by the US Food and Drug Administration in 1998, its indication was recently extended to include children as young as 3 months of age. The World Health Organization and many national guidelines consider efavirenz to be the preferred NNRTI for first-line treatment of children over the age of 3 years. Clinical outcomes of patients on three-drug antiretroviral regimens which include efavirenz are as good as or better than those for patients on all other currently approved HIV medications. Efavirenz is dosed once daily and has pediatric-friendly formulations. It is usually well tolerated, with central nervous system side effects being of greatest concern. Efavirenz increases the risk of neural tube defects in nonhuman primates and therefore its use during the first trimester of pregnancy is limited in some settings. With minimal interactions with antituberculous drugs, efavirenz is preferred for use among patients with HIV/tuberculosis coinfection. Efavirenz can be rendered inactive by a single point mutation in the reverse transcriptase enzyme. Newer NNRTI drugs such as etravirine, not yet approved for use in children under the age of 6 years, may maintain their activity following development of efavirenz resistance. This review highlights key points from the existing literature regarding the use of efavirenz in children and suggests directions for future investigation.

Switching to an etravirine-containing regimen due to drug intolerance in clinical practice

BACKGROUND

Drug intolerance is one of the main reasons for switching antiretroviral therapy in HIV-infected patients. Etravirine (ETR) has demonstrated good tolerability in clinical trials and may be an option for patients who switch therapy due to adverse events.

METHODS

We retrospectively reviewed all patients who had switched to an ETR-containing regimen in our center due to side effects. Virological suppression, ETR discontinuation, and reasons for discontinuation were studied.

RESULTS

A total of 78 patients started treatment with ETR in our center due to previous regimen toxicity. Most of them were men (83.3%), and the median time of infection was 14 years (IQR, 6.5-20 years). HIV RNA was <35 copies/mL in 88.3% of patients, although 33% had archived non-nucleos(t)ide reverse transcriptase inhibitor (NNRTI) mutations that did not compromise ETR efficacy. Efavirenz was the drug most often replaced (38.5%), followed by atazanavir (20.5%) and lopinavir (6.4%). The fixed combination of Trizivir was changed in another 10.3% of patients. After a median follow-up of 14 months (IQR, 6-23), the rate of virologic suppression was 79.5% and 98.4% in intention-to-treat and on-treatment analysis, respectively. Seven patients discontinued treatment due to adverse events (3 gastrointestinal disturbances, 2 rashes, 1 swelling, and 1 neuropathy). ETR was combined with 2 nucleos(t)ide analogues in 75.4% of patients.

CONCLUSION

In HIV patients who report drug side effects, switching to an ETR-containing regimen is a safe strategy in terms of virological suppression and toxicity.

Etravirine in treatment-experienced, HIV-1-infected children and adolescents: 48-week safety, efficacy and resistance analysis of the phase II PIANO study

OBJECTIVES

PIANO (Paediatric study of Intelence As an NNRTI Option; TMC125-C213; NCT00665847) assessed the safety/tolerability, antiviral activity and pharmacokinetics of etravirine plus an optimized background regimen (OBR) in treatment-experienced, HIV-1-infected children (≥ 6 to < 12 years) and adolescents (≥ 12 to < 18 years) over 48 weeks.

METHODS

In a phase II, open-label, single-arm study, 101 treatment-experienced patients (41 children; 60 adolescents) with screening viral load (VL) ≥ 500 HIV-1 RNA copies/mL received etravirine 5.2 mg/kg (maximum dose 200 mg) twice a day (bid) plus OBR.

RESULTS

Sixty-seven per cent of patients had previously used efavirenz or nevirapine. At week 48, the most common treatment-related grade ≥ 2 adverse event (AE) was rash (13%); 12% experienced grade 3 AEs. Only two grade 4 AEs occurred (both thrombocytopaenia, not etravirine related). At week 48, 56% of patients (68% children; 48% adolescents) achieved a virological response (VL<50 copies/mL; intent-to-treat, noncompleter=failure). Factors predictive of response were adherence > 95%, male sex, low baseline etravirine weighted genotypic score and high etravirine trough concentration (C0h ). Seventy-six patients (75%) completed the trial; most discontinuations occurred because of protocol noncompliance or AEs (8% each). Sixty-five per cent of patients were > 95% adherent by questionnaire and 39% by pill count. Forty-one patients experienced virological failure (VF; time-to-loss-of-virological-response non-VF-censored algorithm) (29 nonresponders; 12 rebounders). Of 30 patients with VF with paired baseline/endpoint genotypes, 18 (60%) developed nonnucleoside reverse transcriptase inhibitor (NNRTI) mutations, most commonly Y181C. Mean etravirine area under the plasma concentration-time curve over 12 h (AUC0-12h ; 5216 ng h/mL) and C0h (346 ng/mL) were comparable to adult target values.

CONCLUSIONS

Results with etravirine 5.2 mg/kg bid (with OBR) in this treatment-experienced paediatric population and etravirine 200 mg bid in treatment-experienced adults were comparable. Etravirine is an NNRTI option for treatment-experienced paediatric patients.

Etravirine as a Switching Option for Patients with HIV RNA Suppression: A Review of Recent Trials

Unlike other nonnucleoside reverse transcriptase inhibitors, etravirine is only approved for use in treatment-experienced patients. In the DUET 1 and 2 trials, 1203 highly treatment-experienced patients were randomized to etravirine or placebo, in combination with darunavir/ritonavir and optimized background treatment. In these trials, etravirine showed significantly higher rates of HIV RNA suppression when compared with placebo (61% versus 40% at Week 48). There was no significant rise of lipids or neuropsychiatric adverse events, but there was an increase in the risk of rash with etravirine treatment. In the SENSE trial, which evaluated etravirine and efavirenz in 157 treatment-naïve patients in combination with 2 nucleoside analogues, there was a lower risk of lipid elevations and neuropsychiatric adverse events with etravirine when compared to efavirenz. Etravirine has been evaluated in three randomized switching studies. In the SSAT029 switch trial, 38 patients who had neuropsychiatric adverse events possibly related to efavirenz showed an improvement in these after switching to etravirine. The Swiss Switch-EE recruited 58 individuals without neuropsychiatric adverse events who were receiving efavirenz, and no benefit was shown when switching to etravirine. In the Spanish ETRA-SWITCH trial (n = 46), there were improvements in lipids when individuals switched from a protease inhibitor to etravirine. These switching trials were conducted in patients with full HIV RNA suppression: <50 copies/mL and with no history of virological failure or resistance to therapy. The results from these three randomized switching studies suggest a possible new role for etravirine, in combination with two nucleoside analogues, as a switching option for those with HIV RNA suppression but who are reporting adverse events possibly related to antiretroviral therapy. However a large well-powered trial would need to be conducted to strengthen the evidence from the pilot studies conducted so far.

Randomised study to assess the efficacy and safety of once-daily etravirine-based regimen as a switching strategy in HIV-infected patients receiving a protease inhibitor-containing regimen. Etraswitch study

Background

Etravirine (ETR) was approved for patients with virological failure and antiretroviral resistance mutations. It has also shown antiviral efficacy in antiretroviral-naïve patients. However, data on the switching from protease inhibitors (PI) to ETR are lacking.

Methods

HIV-1-infected patients with suppressed viral load (VL) during a PI-containing regimen (>12 months) and no previous virological failure were randomized to switch from the PI to ETR (400 mg/day, dissolved in water) (ETR group, n = 22) or to continue with the same regimen (control group, n = 21). Percentage of patients with VL≤50 copies/mL were assessed at week 48, as well as changes in CD4 T-cell counts and metabolic profile.

Results

We included 43 patients [72.9% male, 46.3 (42.2; 50.6) years]. Two patients receiving ETR (grade-1 diarrhea and voluntary discontinuation) and another in the control group (simplification) discontinued therapy early. No patients presented virological failure (two consecutive VL>50 copies/mL); treatment was successful in 95.2% of the control group and 90.9% of the ETR group (intention-to-treat analysis, missing = failure) (p = 0.58). CD4+ T-cell counts did not significantly vary [+49 cells/µL in the ETR group (p = 0.25) and −4 cells/µL in the control group (p = 0.71)]. The ETR group showed significant reductions in cholesterol (p<0.001), triglycerides (p = <0.001), and glycemia (p = 0.03) and higher satisfaction (0–10 scale) (p = 0.04). Trough plasma concentrations of ETR were similar to observed in studies using ETR twice daily.

Conclusion

Switch from a PI-based regimen to a once-daily combination based on ETR maintained undetectable VL during 48 weeks in virologically suppressed HIV-infected patients while lipid profile and patient satisfaction improved significantly.

Trial Registration

ClinicalTrials.gov NCT01034917

Antiretroviral regimens sparing agents from the nucleoside(tide) reverse transcriptase inhibitor class: a review of the recent literature

The nucleoside(tide) reverse transcriptase inhibitors (NRTIs) have traditionally been an important 'back-bone' of an antiretroviral therapy (ART) regimen. However all agents have been associated with both short- and long-term toxicity. There have also been concerns regarding the efficacy and safety of a treatment sequencing strategy in which those with past exposure and/or resistance to one or more NRTIs are re-exposed to 'recycled' NRTIs in subsequent ART regimens. Newer, potent and possible safer, agents from various ART classes continue to become available. There has therefore been growing interest in evaluating NRTI-sparing regimens. In this review, we examined studies of NRTI-sparing regimens in adult HIV-positive patients with varying degrees of ART experience. We found that in treatment experienced patients currently on a failing regimen with detectable viral load, there now exists a robust evidence for the use of NRTI-sparing regimens including raltegravir with a boosted-protease inhibitor with or without a third agent. In those on a virologically suppressive regimen switching to a NRTI-sparing regimen or in those ART-naïve patients initiating an NRTI-sparing regimen, evidence is sparse and largely comes from small exploratory trials or observational studies. Overall, these studies suggest that caution needs to be exercised in carefully selecting the right candidate and agents, especially in the context of a dual-therapy regimen, to minimise the risks of virological failure. There is residual toxicity conferred by the ritonavir boost in protease-inhibitor containing NRTI-sparing regimens. Fully-powered studies are needed to explore the place of N (t)RTI-sparing regimens in the sequencing of ART. Additionally research is required to explore how to minimise the adverse effects associated with ritonavir-based pharmacoenhancement.

[Consensus Statement by GeSIDA/National AIDS Plan Secretariat on antiretroviral treatment in adults infected by the human immunodeficiency virus (Updated January 2013)]

OBJECTIVE

This consensus document is an update of combined antiretroviral therapy (cART) guidelines for HIV-1 infected adult patients.

METHODS

To formulate these recommendations a panel composed of members of the GeSIDA/National AIDS Plan Secretariat (Grupo de Estudio de Sida and the Secretaría del Plan Nacional sobre el Sida) reviewed the efficacy and safety advances in clinical trials, cohort and pharmacokinetic studies published in medical journals (PubMed and Embase) or presented in medical scientific meetings. The strength of the recommendations and the evidence which support them are based on a modification of the criteria of Infectious Diseases Society of America.

RESULTS

cART is recommended in patients with symptoms of HIV infection, in pregnant women, in serodiscordant couples with high risk of transmission, in hepatitisB co-infection requiring treatment, and in HIV nephropathy. cART is recommended in asymptomatic patients if CD4 is <500cells/μl. If CD4 are >500cells/μl cART should be considered in the case of chronic hepatitisC, cirrhosis, high cardiovascular risk, plasma viral load >100.000 copies/ml, proportion of CD4 cells <14%, neurocognitive deficits, and in people aged >55years. The objective of cART is to achieve an undetectable viral load. The first cART should include 2 reverse transcriptase inhibitors (RTI) nucleoside analogs and a third drug (a non-analog RTI, a ritonavir boosted protease inhibitor, or an integrase inhibitor). The panel has consensually selected some drug combinations, for the first cART and specific criteria for cART in acute HIV infection, in tuberculosis and other HIV related opportunistic infections, for the women and in pregnancy, in hepatitisB or C co-infection, in HIV-2 infection, and in post-exposure prophylaxis.

CONCLUSIONS

These new guidelines update previous recommendations related to first cART (when to begin and what drugs should be used), how to monitor, and what to do in case of viral failure or adverse drug reactions. cART specific criteria in comorbid patients and special situations are similarly updated.

New therapeutic landscape of NNRTIs for treatment of HIV: a look at recent data

INTRODUCTION

A key objective with highly active antiretroviral therapy for the treatment of HIV infection has been the optimization of antiretroviral drug combinations for individual patients.

AREAS COVERED

Overall, non-nucleoside reverse transcriptase inhibitor (NNRTI)-based regimens (in combination with two nucleoside reverse transcriptase inhibitors (NRTIs)) have become mainstays for initial ARV regimens. Early NNRTIs, efavirenz and nevirapine, are similarly efficacious, but differ according to their toxicity profiles. Newer NNRTIs, rilpivirine and etravirine are also efficacious. Etravirine was designed to overcome common first-line NNRTI resistance mutations, and serves as a second line agent.

EXPERT OPINION

As a class, NNRTIs are key components of ARV regimens. Currently, there are 3 NNRTIs that may be used in first-line regimens, and one in second-line regimens. ARV regimen optimization depends on matching individual drug efficacy, safety, resistance, and toxicity profiles to particular patients. Once-daily dosing options are essential to treatment simplification strategies, which have been shown to enhance regimen compliance and durabiltiy. These are especially important due to the low genetic barrier to resistance generally associated with NNRTIs. As newer drugs are introduced, especially as part of once-daily, single-tablet regimens, this will expand the number of convenient and efficacious treatment options available.

Etravirine for the treatment of HIV/AIDS

INTRODUCTION

Etravirine (TMC125) is an orally administered second-generation non-nucleoside reverse transcriptase inhibitor (NNRTI) that is approved in treatment-experienced patients as addition to an optimized background therapy (OBT).

AREAS COVERED

A Medline search was conducted of Phase II - IV clinical trials, as well as a review of abstracts from major HIV and infectious disease conferences from 2010 - 2013, involving etravirine.

EXPERT OPINION

Etravirine is a well-tolerated NNRTI with a good safety profile and a higher genetic barrier for resistance compared to first-generation NNRTIs. Rash is a potential side effect but remains mostly mild to moderate. The necessity of taking it twice daily with food (200 mg bid.), potential pharmacokinetic interactions and low concentrations in the central nervous system (CNS) represent limitations. The efficacy of once daily etravirine (400 mg qid.) and the use in treatment modification/simplification strategies requires further research. Despite its favorable profile, etravirine is currently not sufficiently investigated nor approved for use in treatment-naïve patients which should be balanced against its potential as a backup NNRTI and the broad cross-resistance conferred by etravirine failure to other NNRTIs. Etravirine should be avoided following treatment failure with regimens containing rilpivirine, another second-generation NNRTI.

Does once-daily etravirine have a role in the management of HIV-1 infection?

When individualizing therapy for HIV-positive patients and for those in whom the 'preferred regimens' of the US Department of Health and Human Services HIV treatment guidelines are not appropriate, a once-daily non-nucleoside with a fixed-dose combination of two nucleosides may be considered in patients who are adherence challenged, intolerant to other regimens but with no viral resistance, or in those in whom the pill burden or actual pill size was too great to accept. Despite having a 30- to 40-h elimination half-life, etravirine was never considered for once-daily dosing during development due to an unacceptably high pill burden in phase II trials. However, a recently published study, SENSE, enrolled 157 HIV-positive patients in a multinational, randomized, placebo-controlled, double-blind trial that investigated 400 mg etravirine once daily with two nucleosides versus a comparator arm that included efavirenz and two nucleosides. The primary objective was to assess neuropsychiatric tolerability over the 48-week study period, with comparative efficacy as a secondary objective. Using the intent-to-treat time to loss of virologic response (ITT-TLOVR) analysis at 48 weeks, 76 % of patients receiving etravirine had an undetectable viral load of <50 copies/mL compared with 74 % of patients receiving efavirenz. This translates to a suppression rate difference of 1.6 % favouring etravirine (95 % CI -12.0-15.2) and met the non-inferiority criteria of a delta of -12 %. Baseline viral load was not observed to impact clinical response rates. Pharmacokinetically and clinically, studies indicate the efficacy and safety of utilizing once-daily etravirine in the treatment-naive population. While it is not appropriate for all patients, once-daily etravirine is best utilized for patients in whom caloric requirements, pill burden, pill size, potential adverse reactions, concomitant medications/drug interactions, psychosocial factors and patient preference preclude the use of a 'preferred' regimen. Etravirine dissolution in water allows for the flexibility of once-daily dosing with one fixed-dose combination tablet followed by an etravirine/water 'chaser'.

Design of HIV noninferiority trials: where are we going?

Since the introduction of zidovudine, a nucleoside analogue reverse transcriptase inhibitor, there has been continuous improvement in the efficacy of antiretroviral treatments. Briefly, antiretroviral therapy moved from the era of zidovudine monotherapy to a combination of two analogues of the reverse transcriptase and then to triple-drug therapy with the introduction of protease inhibitors in 1996. The efficacy of triple-drug combinations was further consolidated with the introduction of the non-nucleoside analogue reverse transcriptase inhibitor. Beyond 1996, the impressive improvement in efficacy has implied that death and clinical endpoints could not be reasonably used as primary efficacy endpoints. Recent studies used plasma viral load as surrogate endpoints to evaluate efficacy of antiretroviral combinations. Progress in antiretroviral efficacy has also led to a move from superiority to noninferiority design. Methodological issues in noninferiority design have been already criticized, but recent trials provide a good opportunity for discussing some key features of that design. Recent studies are used to illustrate some inconsistencies in the choice of response rates, power and noninferiority margin. It appears that HIV noninferiority trials are overpowered by assuming lower success rates than those observed, enrolling a large number of patients and choosing a large margin. Consequently, failure to demonstrate noninferiority is uncommon. Novel designs or endpoints should be introduced emphasizing the expected benefits in terms of toxicity, adherence, resistance or costs.

The nucleoside reverse transcriptase inhibitors, nonnucleoside reverse transcriptase inhibitors, and protease inhibitors in the treatment of HIV infections (AIDS)

The majority of the drugs currently used for the treatment of HIV infections (AIDS) belong to either of the following three classes: nucleoside reverse transcriptase inhibitors (NRTIs), nonnucleoside reverse transcriptase inhibitors (NNRTIs), and protease inhibitors (PIs). At present, there are 7 NRTIs, 5 NNRTIs, and 10 PIs approved for clinical use. They are discussed from the following viewpoints: (i) chemical formulae; (ii) mechanism of action; (iii) drug combinations; (iv) clinical aspects; (v) preexposure prophylaxis; (vi) prevention of mother-to-child transmission; (vii) their use in children; (viii) toxicity; (ix) adherence (compliance); (x) resistance; (xi) new NRTIs, NNRTIs, or PIs in (pre)clinical development; and (xii) the prospects for a "cure" of the disease.

Switch from etravirine twice daily to once daily in non-nucleoside reverse transcriptase inhibitor (NNRTI)-resistant HIV-infected patients with suppressed viremia: the Monetra study

BACKGROUND

Etravirine (ETR) is recommended as twice-daily dosing in pretreated patients. There are no data regarding the use of ETR once daily in HIV-experienced patients with prior resistance to first-generation non-nucleoside reverse transcripase inhibitors (NNRTIs).

OBJECTIVES

To evaluate the capacity of once-daily ETR to maintain suppressed viremia over 48 weeks after switching from ETR twice daily in NNRTI-experienced patients.

METHODS

In this pilot open-label study, patients with plasma viral load (pVL) <50 copies/mL on a stable ETR 200 mg bid regimen were enrolled to switch to ETR 400 mg qd and followed up over 48 weeks. The primary endpoint was the proportion of patients with pVL <50 copies/mL at week 24. Secondary endpoints included the rate of pVL< 50 copies/mL at week 48, ETR pharmacokinetic parameters, and tolerability and resistance profile.

RESULTS

Twenty-four patients were included. They had extensive antiretroviral treatment for a median of 14 years (range, 1-19). All except for 2 had prior resistance to NNRTIs. Seven patients discontinued ETR once daily prior to week 48 for virological failure (3), protocol deviation (3), and side effects (1). At week 24, 95% of patients maintained pVL< 50 copies/mL (95% CI, 78.4-99.7) and 85% at week 48 (95%CI, 65.6-95.8). Two of the 3 patients with virological failure had ETR resistance mutations prior to initiation. The median ETR C(trough) level remained stable after switching from twice daily 515 ng/mL (340-758) to once daily 422 ng/mL (264-655).

CONCLUSION

These results suggest that ETR is effective as a once-daily regimen in patients with prior NNRTI experience when HIV is sensitive to ETR. The stability of C(trough) concentrations on a once-daily regimen confirms the once-daily profile of the drug in experienced patients.

Impact of baseline HIV-1 RNA levels on initial highly active antiretroviral therapy outcome: a meta-analysis of 12,370 patients in 21 clinical trials*

BACKGROUND

Individual randomized trials of first-line antiretroviral treatment do not consistently show an association between higher baseline HIV-1 RNA and lower efficacy.

METHODS

A MEDLINE search identified 21 HIV clinical trials with published analyses of antiretroviral efficacy by baseline HIV-1 RNA, using a standardized efficacy endpoint of HIV-1 RNA suppression <50 copies/mL at week 48.

RESULTS

Among 21 clinical trials identified, eight evaluated only nonnucleoside reverse transcriptase inhibitor (NNRTI)-based combinations, eight evaluated only protease inhibitor-based regimens and five compared different treatment classes. Ten of the trials included tenofovir (TDF)/emtricitabine (FTC) as only nucleoside reverse transcriptase inhibitor (NRTI) backbone, in addition but not restricted to abacavir (ABC)/lamivudine (3TC) (n = 7), zidovudine (ZDV)/3TC (n = 4) and stavudine (d4T)/3TC (n = 1). Across trials, the mean percentage of patients achieving HIV-1 RNA < 50 copies/mL at week 48 was 81.5% (5322 of 6814) for patients with baseline HIV-1 RNA < 100 000, vs. 72.6% (3949 of 5556) for patients with HIV-1 RNA > 100 000 copies/mL. In the meta-analysis, the absolute difference in efficacy between low and high HIV-1 RNA subgroups was 7.4% [95% confidence interval (CI) 5.9-8.9%; P < 0.001]. This difference was consistent in trials of NNRTI-based treatments (difference = 6.9%; 95% CI 4.3-9.6%), protease inhibitor-based treatments (difference = 8.4%; 95% CI 6.0-10.8%) and integrase or chemokine (C-C motif) receptor 5 (CCR5)-based treatments (difference = 6.0%; 95% CI 2.1-9.9%) and for trials using TDF/FTC (difference = 8.4%; 95% CI 6.0-10.8%); there was no evidence for heterogeneity of this difference between trials (Cochran's Q test; not significant).

CONCLUSIONS

In this meta-analysis of 21 first-line clinical trials, rates of HIV-1 RNA suppression at week 48 were significantly lower for patients w ith baseline HIV-1 RNA > 100 000 copies/mL (P < 0.001). This difference in efficacy was consistent across trials of different treatment classes and NRTI backbones.

Herb-drug interaction between Echinacea purpurea and etravirine in HIV-infected patients

The aim of this open-label, fixed-sequence study was to investigate the potential of the botanical supplement Echinacea purpurea to interact with etravirine, a nonnucleoside reverse transcriptase inhibitor of HIV. Fifteen HIV-infected patients receiving antiretroviral therapy with etravirine (400 mg once daily) for at least 4 weeks were included. E. purpurea root/extract-containing capsules were added to the antiretroviral treatment (500 mg every 8 h) for 14 days. Etravirine concentrations in plasma were determined by high-performance liquid chromatography immediately before and 1, 2, 4, 6, 8, 10, 12, and 24 h after a morning dose of etravirine on day 0 and etravirine plus E. purpurea on day 14. Individual etravirine pharmacokinetic parameters were calculated by noncompartmental analysis and compared between days 0 and 14 by means of the geometric mean ratio (GMR) and its 90% confidence interval (CI). The median age was 46 years (interquartile range, 41 to 50), and the median body weight was 76 kg (interquartile range, 68 to 92). Echinacea was well tolerated, and all participants completed the study. The GMR for etravirine coadministered with E. purpurea relative to etravirine alone was 1.07 (90% CI, 0.81 to 1.42) for the maximum concentration, 1.04 (90% CI, 0.79 to 1.38) for the area under the concentration-time curve from 0 to 24 h, and 1.04 (90% CI, 0.74 to 1.44) for the concentration at the end of the dosing interval. In conclusion, the coadministration of E. purpurea with etravirine was safe and well tolerated in HIV-infected patients; our data suggest that no dose adjustment for etravirine is necessary.

Assessing the effectiveness of antiretroviral regimens in cohort studies involving HIV-positive injection drug users

OBJECTIVE

We compared the effectiveness of different highly active antiretroviral therapy (HAART) regimens considering, separately, history of injection drug use (IDU) (yes/no). DESIGN, METHODS: A total of 1163 HIV-infected patients initiated HAART between 1 January 2000 and 28 February 2009 in British Columbia, Canada, and were followed until 28 February 2010. HAART effectiveness was measured by the ability to achieve viral suppression below 50 copies/ml at 6 months. We compared HAART regimens containing efavirenz and boosted atazanavir. We developed logistic regression models using different techniques to control for potential confounders.

RESULTS

Among the 1163 patients, 796 (68%) achieved viral suppression at 6 months (32% reporting a history of IDU). Different confounding models yielded very similar odds ratios for achieving viral suppression. Boosted atazanavir-based HAART demonstrated to be the most effective regimen, showing a surprisingly higher benefit for patients with a history of IDU (odds ratios from different models ranged from 1.74-1.95 to 1.45-1.51).

CONCLUSIONS

The literature has conflicting results regarding the effectiveness of HAART to treat HIV infection among those with a history of IDU. We have shown that most patients, with and without a history of IDU, were able to achieve viral suppression at 6 months. Boosted atazanavir-based HAART was the most resilient regimen and it was more effective than efavirenz-based HAART among IDUs. Given the limited inclusion of IDU in clinical trials of HAART's efficacy, a randomized clinical trial comparing different first-line HAART regimens among IDU is warranted based on these results.

[Consensus document of Gesida and Spanish Secretariat for the National Plan on AIDS (SPNS) regarding combined antiretroviral treatment in adults infected by the human immunodeficiency virus (January 2012)]

This consensus document has been prepared by a panel consisting of members of the AIDS Study Group (Gesida) and the Spanish Secretariat for the National Plan on AIDS (SPNS) after reviewing the efficacy and safety results of clinical trials, cohort and pharmacokinetic studies published in medical journals, or presented in medical scientific meetings. Gesida has prepared an objective and structured method to prioritise combined antiretroviral treatment (cART) in naïve patients. Recommendations strength (A, B, C) and the evidence which supports them (I, II, III) are based on a modification of the Infectious Diseases Society of America criteria. The current antiretroviral treatment (ART) of choice for chronic HIV infection is the combination of three drugs. ART is recommended in patients with symptomatic HIV infection, in pregnancy, in serodiscordant couples with high transmission risk, hepatitis B fulfilling treatment criteria, and HIV nephropathy. Guidelines on ART treatment in patients with concurrent diagnosis of HIV infection and an opportunistic type C infection are included. In asymptomatic patients ART is recommended on the basis of CD4 lymphocyte counts, plasma viral load and patient co-morbidities, as follows: 1) therapy should be started in patients with CD4 counts <350 cells/μL; 2) when CD4 counts are between 350 and 500 cells/μL, therapy will be recommended and only delayed if patient is reluctant to take it, the CD4 are stabilised, and the plasma viral load is low; 3) therapy could be deferred when CD4 counts are above 500 cells/μL, but should be considered in cases of cirrhosis, chronic hepatitis C, high cardiovascular risk, plasma viral load >10(5) copies/mL, proportion of CD4 cells <14%, and in people aged >55 years. ART should include 2 reverse transcriptase inhibitors nucleoside analogues and a third drug (non-analogue reverse transcriptase inhibitor, ritonavir boosted protease inhibitor or integrase inhibitor). The panel has consensually selected and given priority to using the Gesida score for some drug combinations, some of them co-formulated. The objective of ART is to achieve an undetectable viral load. Adherence to therapy plays an essential role in maintaining antiviral response. Therapeutic options are limited after ART failures, but an undetectable viral load may be possible nowadays. Adverse events are a fading problem of ART. Guidelines in acute HIV infection, in women, in pregnancy, and to prevent mother-to-child transmission and pre- and post-exposition prophylaxis are commented upon. Management of hepatitis B or C co-infection, other co-morbidities, and the characteristics of ART in HIV-2 infection are included.

Women and HIV: motherhood and more

PURPOSE OF REVIEW

The number of women living with HIV continues to increase globally. With the availability of efficacious antiretroviral therapy, there is a pressing need to ensure women are treated effectively throughout their life course. This article reviews information on ways that HIV affects women and discusses recent treatment and prevention approaches.

RECENT FINDINGS

Because women are at greater risk of heterosexual HIV acquisition than men, new data on biomedical approaches to prevention are of particular relevance. International guidelines for the treatment of pregnant women with HIV now place greater weight on the well being of the mother as well as the prevention of vertical transmission. Although effective HIV treatment for women is associated with better health, longer life, reduced infectiousness and prevention of acquisition of HIV, there is evidence that women experience more adverse effects, discontinue medication more frequently and have more problems with adherence than men.

SUMMARY

Efficacious anti-HIV drugs exist, but the particular circumstances for women may compromise their effectiveness. Globally, women's access to therapy remains inadequate. More data are needed about the best approaches to HIV therapy for women to include the biological, psychological, social and cultural factors that influence the way women experience HIV infection.