Efficacy and safety of TMC125 (etravirine) in treatment-experienced HIV-1-infected patients in DUET-1: 24-week results from a randomised, double-blind, placebo-controlled trial

NNRTIs: pharmacological data

One of the choice criteria for antiretroviral therapy, once the viral load is controlled, is long-term treatment safety. Safety, despite similarities in each therapeutic class, can differ significantly from one agent to another, according to their respective pharmacokinetic and pharmacodynamic properties. We reviewed data on two very well-known NNRTIs, efavirenz and nevirapine, in this context. The pharmacokinetic properties of both agents are presented along with their impact on residual viremia and viral reservoirs, as well as their clinical consequences. The implications for the penetration of these antiretroviral drugs in the CNS and in female and male genital tracts are also discussed. Pharmacogenetics could become an interesting tool. Finally, the availability of new NNRTIs has recently boosted this therapeutic class, even if their long-term properties remain to be assessed. The consideration of all this data stresses the importance of communication among clinicians, virologists, and pharmacologists before choosing a treatment.

Efficacy and safety outcomes among treatment-experienced women and men treated with etravirine in gender, race and clinical experience

The GRACE (Gender, Race and Clinical Experience) trial enrolled treatment-experienced, HIV-1-infected patients, mainly women, in North America, to assess outcomes with a darunavir/ritonavir-based regimen, which could include etravirine (ETR). We present outcomes at week 48 for men and women receiving ETR. Virologic response (HIV-1 RNA <50 copies/ml) and safety were assessed; descriptive statistics are reported. To evaluate the independent contribution of ETR treatment, a post hoc analysis including a multivariate model assessed factors predictive of virologic response for the entire GRACE population (429 patients). Of 207 patients who received ETR (women, 57.5%; black or Hispanic, 81.7%), 71.4% of women and 79.5% of men completed the study. Week 48 virologic response rates in women and men (intent-to-treat population) were 58.0% and 61.4%, respectively. After censoring patients who discontinued treatment for reasons other than virologic failure, response rates were 79.3% and 73.0%, respectively. Overall, ETR was well tolerated. Women experienced more nausea (24.4% vs. 11.4%) and rash-related events (21.0% vs. 15.9%), but less diarrhea (15.1% vs. 21.6%), compared with men. Grade 3-4 hypertriglyceridemia was more common in men (9.3%) than women (1.1%). In total, 11 (9.2%) women and 7 (8.0%) men discontinued ETR due to adverse events. In the multivariate model of the entire GRACE population, ETR use was independently associated with improved virologic response. ETR is effective and well tolerated in treatment-experienced patients with HIV-1, with similar outcomes among women and men.

[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.

Novel clinical trial designs for the development of new antiretroviral agents

The resounding success of combination antiretroviral efficacy for both treatment-naïve and treatment-experienced patients - with 70-90% viral suppression rates in recent studies - has made registration trials for new agents challenging. With the inevitable specter of drug resistance, new agents must have a pathway to approval. The Forum for Collaborative HIV Research obtained input from concerned stakeholders including industry, clinical sciences, community advocacy, and regulatory sciences (Food and Drug Administration and European Medicines Agency) to discuss how safety and efficacy of new agents could be demonstrated. Recognizing the shortfalls of superiority or noninferiority trials in this environment, a new trial design for treatment-experienced patients, minimizing the risk for drug resistance but allowing full assessment of safety, was proposed. The antiviral efficacy of an active investigational drug would be assessed by comparison to placebo as an add-on to a failing regimen in a short, 10-14-day study followed by institution of an optimized background regimen (OBR) in both arms with investigational drug given to all patients. The follow-on stage would assess dose response, safety, durability of initial response, and development of resistance. Additionally, a second safety trial could be conducted comparing patients randomized to the investigational agent with a new OBR to those on a new OBR and placebo. Finally, approval decisions could consider other long-term safety endpoints. Exposing treatment-naïve patients to investigational agents remains a controversial issue; stakeholders have different interpretations of risk-benefit for trials in this population that necessitate careful consideration before initiating trials in them.

Etravirine and rilpivirine resistance in HIV-1 subtype CRF01_AE-infected adults failing non-nucleoside reverse transcriptase inhibitor-based regimens

BACKGROUND

We studied prevalence of etravirine (ETR) and rilpivirine (RPV) resistance in HIV-1 subtype CRF01_AE infection with first-line non-nucleoside reverse transcriptase inhibitor (NNRTI) failure.

METHODS

A total of 225 adults failing two nucleoside reverse transcriptase inhibitors (NRTIs) plus 1 NNRTI in Thailand with HIV RNA>1,000 copies/ml were included. Genotypic resistance results and HIV-1 subtype were interpreted by Stanford DR database. ETR resistance was calculated by the new Monogram weighted score (Monogram WS; ≥ 4 indicating high-level ETR resistance) and by DUET weighted score (DUET WS; 2.5-3.5 and ≥ 4 resulted in intermediate and reduce ETR response, respectively). RPV resistance interpretation was based on previous reports.

RESULTS

Median (IQR) age was 38 (34-42) years, 41% were female and CDC A:B:C were 22%:21%:57%. HIV subtypes were 96% CRF01_AE and 4% B. Antiretrovirals at failure were lamivudine (100%), stavudine (93%), nevirapine (90%) and efavirenz (10%) with a median (IQR) duration of 3.4 (1.8-4.5) years. Median (IQR) CD4(+) T-cell count and HIV RNA were 194 (121-280) cells/mm³ and 4.1 (3.6-4.6) log₁₀ copies/ml, respectively. The common NNRTI mutations were Y181C (41%), G190A (22%) and K103N (19%). The proportion of patients with Monogram WS score ≥ 4 was 61.3%. By DUET WS, 49.8% and 7.5% of patients were scored 2.5-3.5 and ≥4, respectively. Only HIV RNA ≥ 4 log₁₀ copies/ml at failure was associated with both Monogram WS ≥ 4 (OR 2.3, 95% CI 1.3-3.9; P=0.003) and DUET WS ≥ 2.5 (OR 1.9, 95% CI 1.1-3.3; P=0.02). The RVP resistance-associated mutations (RAMs) detected were K101P (1.8%), Y181I (2.7%) and Y181V (3.6%). All patients with RPV mutation had ETR resistance. No E138R/E138K mutations were detected.

CONCLUSIONS

Approximately 60% of patients had high-level ETR resistance. The role of ETR in second-line therapy is limited in late NNRTI failure settings. RVP RAMs were uncommon, but cross-resistance between ETR and RVP was high.

Biotransformation of the antiretroviral drug etravirine: metabolite identification, reaction phenotyping, and characterization of autoinduction of cytochrome P450-dependent metabolism

Etravirine (ETR) is a second-generation non-nucleoside reverse transcriptase inhibitor prescribed for the treatment of HIV-1. By using human liver microsomes (HLMs), cDNA-expressed cytochromes P450 (P450s), and UDP-glucuronosyltransferases (UGTs), the routes of ETR metabolism were defined. Incubations with cDNA-expressed P450 isozymes and chemical inhibition studies using HLMs indicated that CYP2C19 is primarily responsible for the formation of both the major monohydroxylated and dihydroxylated metabolites of ETR. Tandem mass spectrometry suggested that these metabolites were produced via monomethylhydroxylation and dimethylhydroxylation of the dimethylbenzonitrile moiety. Formation of these monohydroxy and dihydroxy metabolites was decreased by 75 and 100%, respectively, in assays performed using HLMs that were genotyped as homozygous for the loss-of-function CYP2C19*2 allele compared with formation by HLMs genotyped as CYP2C19*1/*1. Two monohydroxylated metabolites of lower abundance were formed by CYP3A4, and interestingly, although CYP2C9 showed no activity toward the parent compound, this enzyme appeared to act in concert with CYP3A4 to form two minor dihydroxylated products of ETR. UGT1A3 and UGT1A8 were demonstrated to glucuronidate a CYP3A4-dependent monohydroxylated product. In addition, treatment of primary human hepatocytes with ETR resulted in 3.2-, 5.2-, 11.8-, and 17.9-fold increases in CYP3A4 mRNA levels 6, 12, 24, and 72 h after treatment. The presence of the pregnane X receptor antagonist sulforaphane blocked the ETR-mediated increase in CYP3A4 mRNA expression. Taken together, these data suggest that ETR and ETR metabolites are substrates of CYP2C19, CYP3A4, CYP2C9, UGT1A3, and UGT1A8 and that ETR is a PXR-dependent modulator of CYP3A4 mRNA levels.

Pooled week 96 results of the phase III DUET-1 and DUET-2 trials of etravirine: further analysis of adverse events and laboratory abnormalities of special interest

OBJECTIVES

The aim of the study was to investigate the frequency and severity of adverse events (AEs) and laboratory abnormalities of interest over 96 weeks of treatment with etravirine or placebo in the pooled TMC125 DUET (Demonstrate Undetectable viral load in patients Experienced with ARV Therapy) trials.

METHODS

Treatment-experienced, HIV-1-infected patients randomly received etravirine 200 mg twice a day (bid) or placebo, plus a background regimen. The frequency and severity of neuropsychiatric, rash, hepatic and lipid AEs were analysed; frequencies were also adjusted for total patient-years of exposure (PYE).

RESULTS

A total of 599 and 604 patients received etravirine and placebo, respectively (median treatment duration 96.0 and 69.6 weeks, respectively). There was no significant difference between the treatment groups in the frequency of neuropsychiatric AEs. However, a significant difference in the frequency of rash was observed (20.5% vs. 11.8%, respectively; P < 0.0001); rash was generally mild to moderate in severity; the rate of discontinuation because of rash was low (2.2% vs. 0% in the etravirine and placebo groups, respectively). The frequency of hepatic AEs was low and similar between the treatment groups (8.7% vs. 7.1%, respectively; P = 0.3370); hepatic enzyme levels did not increase over time. Lipid-related laboratory abnormalities and changes over time in lipid levels were generally comparable between treatment groups. Adjusting for treatment exposure, the frequency of AEs remained similar between treatment groups, with the exception of rash [13.7 vs. 9.3 per 100 PYE; relative risk (95% confidence interval) 1.48 (1.02-1.95)].

CONCLUSIONS

The frequency of AEs of interest was generally similar between the treatment groups, both overall and when adjusted for treatment exposure, with the exception of rash which was more frequent in the etravirine group.

Dual therapy based on a ritonavir-boosted protease inhibitor as a novel salvage strategy for HIV-1-infected patients on a failing antiretroviral regimen

OBJECTIVES

To assess the efficacy and safety of dual-antiretroviral therapy containing a ritonavir-boosted protease inhibitor (PI/r) in treatment-experienced patients failing a current antiretroviral regimen.

METHODS

Retrospective analysis of 60 consecutive HIV-1-infected patients who started a dual-antiretroviral rescue regimen containing a PI/r, in three hospitals in Spain. Virological failure was defined as confirmed HIV RNA >50 copies/mL at treatment week 24 or later. The percentage of patients remaining free of therapeutic failure was estimated using the Kaplan-Meier method, by intent-to-treat analysis (missing, changes and virological failure = therapeutic failure).

RESULTS

Median baseline characteristics of patients were: 13 years on antiretroviral therapy (four prior highly active antiretroviral therapy regimens and eight different drugs), 380 CD4 cells/mm(3) and HIV RNA 3.04 log(10) copies/mL. All patients had resistance mutations to at least two drug classes, although only 9.3% had specific mutations to darunavir. A darunavir-based regimen was started in 47 (78.4%) patients, combined with etravirine (26.7%), tenofovir (26.7%) or raltegravir (25%). Three (5%) patients discontinued treatment due to side effects. At the end of follow-up, 86.7% of patients remained free of therapeutic failure; the percentages of patients with no therapeutic failure at treatment weeks 24, 48 and 96 were 96.6% (95% CI, 91.9-101.3); 90.1% (95% CI, 81.9-98.3) and 79.8% (95% CI, 66.1-93.5), respectively.

CONCLUSIONS

Our results suggest that a dual-therapy rescue regimen including a PI/r is convenient, well tolerated and potent enough to achieve persistent viral suppression in selected pre-treated patients with low viral load and few PI resistance mutations.

Pharmacokinetics and short-term safety and tolerability of etravirine in treatment-experienced HIV-1-infected children and adolescents

OBJECTIVES

To evaluate the pharmacokinetics, weight-based dose selection and short-term safety and tolerability of etravirine in HIV-1-infected children and adolescents.

DESIGN

Phase I, nonrandomized, open-label study in two stages.

METHODS

Children and adolescents aged at least 6 years to 17 years or less on a stable lopinavir/ritonavir-based antiretroviral regimen with HIV-1 RNA plasma viral load less than 50 copies/ml were enrolled. In both stages, etravirine (4 mg/kg twice daily in stage I, 5.2 mg/kg twice daily in stage II), added to the existing antiretroviral regimen, was administered for 7 days followed by a morning dose and 12-h pharmacokinetic assessment on day 8. Pharmacokinetic parameters were determined using noncompartmental analysis. Data were compared with those previously established in HIV-1-infected adults on a similar etravirine (200 mg twice daily) combination antiretroviral regimen.

RESULTS

Twenty-one patients were recruited to each stage; 19 and 20 had evaluable pharmacokinetics in stages I and II, respectively. Mean (SD) maximum plasma concentrations in stages I and II were 495 (453) and 757 ng/ml (680), respectively; area under the plasma concentration-time curve over 12 h was 4050 (3602) and 6141 ng h/ml (5586), respectively. Statistical/qualitative comparisons showed comparable exposures with adults in stage II; however, the upper 90% confidence interval fell outside the predefined range. Plasma viral load remained undetectable on day 8 in all patients, and etravirine was well tolerated at both doses.

CONCLUSION

Etravirine 5.2 mg/kg was well tolerated in this study and this dose was selected for further investigation in clinical trials.

Role of non-nucleoside reverse transcriptase inhibitors in treating HIV-infected children

The first-generation non-nucleoside reverse transcriptase inhibitors (NNRTIs), efavirenz and nevirapine, fulfil key roles in antiretroviral therapy for HIV-infected paediatric patients, from lowering the incidence of mother-to-child transmission during pregnancy and birth to treatment throughout childhood and adolescence. Both agents have established efficacy, safety and tolerability profiles, and also offer advantages over other classes of therapy in terms of regimen simplicity and availability across different treatment settings. Although the role of NNRTIs in paediatric treatment strategies is largely determined by experience in adult patients, results of the recent phase II/III PENPACT-1 trial in infants and children aged between 30 days and 18 years have shown that there are no significant differences in 4-year virological, immunological or clinical outcomes between NNRTIs and protease inhibitors as first- and second-line agents. However, results from the IMPAACT P1060 study (cohort 2), conducted in resource-limited settings, showed that infants under 36 months unexposed to NNRTIs were significantly more likely to fail treatment when started on a nevirapine-based regimen than those on a lopinavir/ritonavir-based regimen. Unfortunately, the use of efavirenz and nevirapine in children can be limited by rapid development of high-level resistance to one or both agents, which may reduce the availability of viable treatment options, particularly in resource-limited settings. Several therapeutic strategies addressing this issue are currently under investigation, but a significant need for new NNRTI-based treatment options remains. The more recently approved NNRTI, etravirine, has demonstrated efficacy and safety benefits in HIV-1-infected, NNRTI-resistant adult patients, with a higher genetic barrier to the development of resistance relative to the first-generation NNRTIs. Another NNRTI, rilpivirine (TMC278), is approved for use in HIV-1-infected, treatment-naïve adult patients and has demonstrated an improved tolerability profile compared with efavirenz. Although available data on etravirine in children are currently limited, ongoing trials will provide important information on the potential for their use in novel paediatric treatment strategies. This review examines the role of efavirenz and nevirapine in paediatric antiretroviral therapy in children within different treatment settings. In addition, this review also outlines available clinical data on etravirine and rilpivirine in the context of how these antiretrovirals may address some of the limitations of efavirenz and nevirapine in paediatric patients.

Newer drugs and earlier treatment: impact on lifetime cost of care for HIV-infected adults

OBJECTIVE

To determine the component costs of care to optimize treatment with limited resources.

DESIGN

We used the Cost-Effectiveness of Preventing AIDS Complications Model of HIV disease and treatment to project life expectancy and both undiscounted and discounted lifetime costs (2010 €).

METHODS

We determined medical resource utilization among HIV-infected adults followed from 1998 to 2005 in northern France. Monthly HIV costs were stratified by CD4 cell count. Costs of CD4, HIV RNA and genotype tests and antiretroviral therapy (ART) were derived from published literature. Model inputs from national data included mean age 38 years, mean initial CD4 cell count 372 cells/μl, ART initiation at CD4 cell counts less than 350 cells/μl, and ART regimen costs ranging from €760 to 2570 per month.

RESULTS

The model projected a mean undiscounted life expectancy of 26.5 years and a lifetime undiscounted cost of €535,000/patient (€320,700 discounted); 73% of costs were ART related. When patients presented to care with mean CD4 cell counts of 510 cells/μl and initiated ART at CD4 cell counts less than 500 cells/μl or HIV RNA more than 100,000 copies/ml, life expectancy was 27.4 years and costs increased 1-2%, to €546,700 (€324,500 discounted). When we assumed introducing generic drugs would result in a 50% decline in first-line ART costs, lifetime costs decreased 4-6%, to €514,200 (€302 ,800 discounted).

CONCLUSION

As HIV disease is treated earlier with more efficacious drugs, survival and thus costs of care will continue to increase. The availability in high-income countries of widely used antiretroviral drugs in generic form could reduce these costs.

Intracellular and plasma pharmacokinetics of 400 mg of etravirine once daily versus 200 mg of etravirine twice daily in HIV-infected patients

OBJECTIVES

To compare intracellular and plasma etravirine concentrations when etravirine was given at 200 mg/12 h versus 400 mg/24 h and to evaluate whether the results would support once-daily dosing.

METHODS

This was an open-label sequential study in which eight patients on protease inhibitor (PI)-sparing regimens containing etravirine were included. Full pharmacokinetic profiles were performed while on 200 mg of etravirine/12 h and after switching to 400 mg of etravirine/24 h. Intracellular and plasma levels were determined by liquid chromatography coupled with mass spectrometry. Pharmacokinetic parameters were calculated by non-compartmental analysis and compared by geometric mean ratios (GMRs) using 200 mg of etravirine/12 h as the reference group.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01121809.

RESULTS

The geometric mean (GM) for etravirine AUC(0-τ) (5602 versus 5076 ng · h/mL, GMR 0.91), C(max) (403 versus 495 ng/mL, GMR 1.23) and C(min) (139 versus 102 ng/mL, GMR 0.74) were similar with both dosing schedules at the intracellular level. In plasma, the GMRs for AUC(0-τ), C(max) and C(min) were 1.31, 1.76 and 0.99, respectively. The mean intracellular penetration, evaluated as intracellular and plasma AUC(0-τ) ratios, was 81% when etravirine was dosed twice daily and 56% with once-daily dosing.

CONCLUSIONS

Our results show that intracellular etravirine levels were similar with both dosing regimens in patients with PI-sparing regimens, while etravirine plasma AUC(0-τ) and C(max) were 30% and 76% higher with the once-daily regimen, respectively. Thus, a once-daily dosing regimen is supported not only by plasma etravirine pharmacokinetic profiles but also by intracellular levels.

Immunologic criteria are poor predictors of virologic outcome: implications for HIV treatment monitoring in resource-limited settings

BACKGROUND

Viral load (VL) quantification is considered essential for determining antiretroviral treatment (ART) success in resource-rich countries. However, it is not widely available in resource-limited settings where the burden of human immunodeficiency virus infection is greatest. In the absence of VL monitoring, switches to second-line ART are based on World Health Organization (WHO) clinical or immunologic failure criteria.

METHODS

We assessed the performance of CD4 cell criteria to predict virologic outcomes in a large ART program in Nigeria. Laboratory monitoring consists of CD4 cell count and VL at baseline, then every 6 months. Failure was defined as 2 consecutive VLs >1000 copies/mL after at least 6 months of ART. Virologic outcomes were compared with the 3 WHO-defined immunologic failure criteria.

RESULTS

A total of 9690 patients were included in the analysis (median follow-up, 33.2 months). A total of 1225 patients experienced failure by both immunologic and virologic criteria, 872 by virologic criteria only, and 1897 by immunologic criteria only. The sensitivity of CD4 cell criteria to detect viral failure was 58%, specificity was 75%, and the positive-predictive value was 39%. For patients with both virologic and immunologic failure, VL criteria identified failure significantly earlier than CD4 cell criteria (median, 10.4 vs 15.6 months; P < .0001).

CONCLUSIONS

Because of the low sensitivity of immunologic criteria, a substantial number of failures are missed, potentially resulting in accumulation of resistance mutations. In addition, specificity and predictive values are low, which may result in large numbers of unnecessary ART switches. Monitoring solely by immunologic criteria may result in increased costs because of excess switches to more expensive ART and development of drug-resistant virus.

In vitro resistance profile of the candidate HIV-1 microbicide drug dapivirine

Antiretroviral-based microbicides may offer a means to reduce the sexual transmission of HIV-1. Suboptimal use of a microbicide may, however, lead to the development of drug resistance in users that are already, or become, infected with HIV-1. In such cases, the efficacy of treatments may be compromised since the same (or similar) antiretrovirals used in treatments are being developed as microbicides. To help predict which drug resistance mutations may develop in the context of suboptimal use, HIV-1 primary isolates of different subtypes and different baseline resistance profiles were used to infect primary cells in vitro in the presence of increasing suboptimal concentrations of the two candidate microbicide antiretrovirals dapivirine (DAP) and tenofovir (TFV) alone or in combination. Infections were ongoing for 25 weeks, after which reverse transcriptase genotypes were determined and scrutinized for the presence of any clinically recognized reverse transcriptase drug resistance mutations. Results indicated that suboptimal concentrations of DAP alone facilitated the emergence of common nonnucleoside reverse transcriptase inhibitor resistance mutations, while suboptimal concentrations of DAP plus TFV gave rise to fewer mutations. Suboptimal concentrations of TFV alone did not frequently result in the development of resistance mutations. Sensitivity evaluations for stavudine (d4T), nevirapine (NVP), and lamivudine (3TC) revealed that the selection of resistance as a consequence of suboptimal concentrations of DAP may compromise the potential for NVP to be used in treatment, a finding of potential relevance in developing countries.

[Safety and effectiveness of salvage therapy in HIV patients]

INTRODUCTION

The treatment used after failure of at least two lines of antiretroviral treatment in HIV patients is called salvage therapy. The study aims to describe the characteristics of HIV patients subjected to such a regimen, and determine the safety and effectiveness of treatment with tipranavir (TPV), darunavir (DRV), enfuvirtide (ENF) and etravirine (ETR) combined with an optimised antiretroviral regimen.

PATIENTS AND METHODS

HIV patients treated with ENF, TPV, DRV or ETR in a tertiary hospital infectious diseases department subjected to at least 12 weeks treatment. The patient characteristics are described and the effectiveness, durability and adherence to the treatment analysed.

RESULTS

There were 28 patients studied, with an average of 10 treatment regimens prior to starting salvage therapy (SD=3.5; 95% CI, 8.9-11.1). A total of 85.7% patients had treatment adherence >90%. For ENF, 70.8% of the treatment lines were suspended during follow-up. After salvage therapy, the percentage of patients with viral load (VL) <400 copies/ml doubled, and cases with undetectable CV (<50 copies/ml) almost tripled. The treatments used did not change the liver or kidney profiles; however, they changed the lipid profile and increased the percentage of patients with hyperglycaemia.

CONCLUSIONS

The salvage therapy studied was effective. Good adherence to the therapy is critical for its effectiveness.

Combating HIV resistance - focus on darunavir

Darunavir is a second-generation protease inhibitor designed to have antiviral efficacy against HIV-1 isolates harboring multiple resistance mutations to protease inhibitors. Pivotal trials conducted in treatment-experienced HIV-infected individuals have demonstrated significantly greater virological suppression when darunavir was added to an optimized background treatment compared with a control protease inhibitor. This virological suppression was associated with an increase in CD4 counts and was sustained over time. Darunavir resistance-associated mutations have been defined as V11I, V32I, L33F, I47V, I50V, I54L/M, G73S, L76V, I84V, and L89V. In clinical trials, baseline darunavir susceptibility was a strong predictor of virological response. Prior use of fosamprenavir was associated with darunavir resistance mutations. Darunavir has a high genetic barrier and has a distinct resistance profile. Although some cross-resistance exists with other second-generation protease inhibitors such as tipranavir, different resistance mutation patterns have been observed upon failure to these regimens. It was found that mutations at 47V, 54M, 85V, and 73T were most prevalent in isolates resistant to both PIs. Mutations 48V, 50V, and 54L were associated with resistance to darunavir but not to tipranavir. 82S and 82T were associated with resistance to tipranavir but not to darunavir. Therefore, darunavir provides potent virological efficacy as well as high genetic barrier that can be useful to preserve treatment options in HIV-infected, treatment-experienced individuals.

F18, a novel small-molecule nonnucleoside reverse transcriptase inhibitor, inhibits HIV-1 replication using distinct binding motifs as demonstrated by resistance selection and docking analysis

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) are one of the key components of antiretroviral therapy drug regimen against human immunodeficiency virus type 1 (HIV-1) replication. We previously described a newly synthesized small molecule, 10-chloromethyl-11-demethyl-12-oxo-calanolide A (F18), a (+)-calanolide A analog, as a novel anti-HIV-1 NNRTI (H. Xue et al., J. Med. Chem. 53:1397-1401, 2010). Here, we further investigated its antiviral range, drug resistance profile, and underlying mechanism of action. F18 consistently displayed potent activity against primary HIV-1 isolates, including various subtypes of group M, circulating recombinant form (CRF) 01_AE, and laboratory-adapted drug-resistant viruses. Moreover, F18 displayed distinct profiles against 17 NNRTI-resistant pseudoviruses, with an excellent potency especially against one of the most prevalent strains with the Y181C mutation (50% effective concentration, 1.0 nM), which was in stark contrast to the extensively used NNRTIs nevirapine and efavirenz. Moreover, we induced F18-resistant viruses by in vitro serial passages and found that the mutation L100I appeared to be the dominant contributor to F18 resistance, further suggesting a binding motif different from that of nevirapine and efavirenz. F18 was nonantagonistic when used in combination with other antiretrovirals against both wild-type and drug-resistant viruses in infected peripheral blood mononuclear cells. Interestingly, F18 displayed a highly synergistic antiviral effect with nevirapine against nevirapine-resistant virus (Y181C). Furthermore, in silico docking analysis suggested that F18 may bind to the HIV-1 reverse transcriptase differently from other NNRTIs. This study presents F18 as a new potential drug for clinical use and also presents a new mechanism-based design for future NNRTI.

Reverse Transcriptase Genotypes in Pediatric Patients Failing Initial Antiretroviral Therapy in Gaborone, Botswana

Background

Limited data are available on patterns of resistance mutations in pediatric patients in southern Africa, where HIV-1 subtype C (HIV-1C) predominates.

Methods

Retrospective chart review of pediatric patients. Nucleoside reverse transcriptase inhibitor (NRTI)- and nonnucleoside reverse transcriptase inhibitor (NNRTI)-associated resistance mutations quantified from population-based sequencing genotypic resistance assay results taken at time of first-line antiretroviral therapy (ART) failure (first-line ART = stavudine [d4T] or zidovudine [ZDV] + lamivudine [3TC] + nevirapine [NVP] or efavirenz [EFV]).

Results

Total number of patients with resistance assays analyzed is 45. Nucleoside reverse transcriptase inhibitor-associated mutation frequencies noted were M184V (n = 41; 91.1%); thymidine analogue mutations (TAMs; n = 20; 44.4%); >1 TAM (n = 9; 20%); TAM-2 pathway (n = 10; 22.2%); TAM-1 pathway (n = 7; 15.6%); TAM-1 and TAM-2 pathways (n = 3; 6.7%); K65R (n = 2; 4.4%); Q151M (n = 1; 2.2%); and L74V (n = 0; 0%). Nonnucleoside reverse transcriptase inhibitor-associated mutation frequencies noted were associated with notable resistance to either/both NVP and EFV (n = 40; 88.9%); K103N (n = 15; 33.3%); ≥1 mutations associated with etravirine (ETR) failure (K101E, Y181C, and G190A; n =20; 44.4%); and ≥2 notable NNRTI mutations (n = 12; 26.7%).

Conclusions

In this cohort, low-genetic barrier mutations were common, as were TAMs, including more than 1 TAM. Mutations compromising nonthymidine analogue backbones were rare, suggesting that it is likely that children who fail first-line NRTI backbones containing d4T or ZDV/3TC would still respond to abacavir (ABC), didanosine (ddI), and, for adolescents, tenofovir (TDF). Our data support the empiric continuation of 3TC in second-line regimens.

Viral suppression rates in salvage treatment with raltegravir improved with the administration of genotypic partially active or inactive nucleoside/tide reverse transcriptase inhibitors

BACKGROUND

Nucleoside reverse transcriptase inhibitors (NRTIs) are often administered in salvage therapy even if genotypic resistance tests (GRTs) indicate high-level resistance, but little is known about the benefit of these additional NRTIs.

METHODS

The effect of <2 compared with 2 NRTIs on viral suppression (HIV-1 RNA < 50 copies/mL) at week 24 was studied in salvage patients receiving raltegravir. Intent-to-treat and per-protocol analyses were performed; last observation carried forward imputation was used to deal with missing information. Logistic regressions were weighted to create a pseudopopulation in which the probability of receiving <2 and 2 NRTIs was unrelated to baseline factors predicting treatment response.

RESULTS

One-hundred thirty patients were included, of whom 58.5% (n = 76) received <2 NRTIs. NRTIs were often replaced by other drug classes. Patients with 2 NRTIs received less additional drug classes compared with patients with <2 NRTIs [median (IQR): 1 (1-2) compared with 2 (1-2), P Wilcoxon < 0.001]. The activity of non-NRTI treatment components was lower in the 2 NRTIs group compared with the <2 NRTIs group [median (IQR) genotypic sensitivity score: 2 (1.5-2.5) compared with 2.5 (2-3), P Wilcoxon < 0.001]. The administration of <2 NRTIs was associated with a worse viral suppression rate at week 24. The odds ratios were 0.34 (95% confidence interval: 0.13 to 0.89, P = 0.027) and 0.19 (95% confidence interval: 0.05 to 0.79, P = 0.023) when performing the last observation carried forward and the per-protocol approach, respectively.

CONCLUSIONS

Our findings showed that partially active or inactive NRTIs contribute to treatment response, and thus the use of 2 NRTIs in salvage regimens that include raltegravir seems warranted.

Nephrotoxicity of HAART

Highly active antiretroviral therapy (HAART) and other medical therapies for HIV-related infections have been associated with toxicities. Antiretroviral therapy can contribute to renal dysfunction directly by inducing acute tubular necrosis, acute interstitial nephritis, crystal nephropathy, and renal tubular disorders or indirectly via drug interactions. With the increase in HAART use, clinicians must screen patients for the development of kidney disease especially if the regimen employed increases risk of kidney injury. It is also important that patients with chronic kidney disease (CKD) are not denied the best combinations, especially since most drugs can be adjusted based on the estimated GFR. Early detection of risk factors, systematic screening for chronic causes of CKD, and appropriate referrals for kidney disease management should be advocated for improved patient care. The interaction between immunosuppressive therapy and HAART in patients with kidney transplants and the recent endorsement of tenofovir/emtricitabine by the Centers for Disease Control (CDC) for preexposure prophylaxis bring a new dimension for nephrotoxicity vigilance. This paper summarizes the common antiretroviral drugs associated with nephrotoxicity with particular emphasis on tenofovir and protease inhibitors, their risk factors, and management as well as prevention strategies.

The HIV-Infected Adolescent

HIV-infected adolescents represent a unique, yet diverse, population requiring specialized medical and psychosocial HIV care. Perinatally infected and behaviorally infected adolescents often have differing therapeutic needs, but may share common difficulties, including medication nonadherence, high-risk sexual behavior, psychosocial stressors, and concomitant psychiatric disorders. Addressing these needs within a culturally sensitive framework and in the context of a population-specific approach to treatment is paramount to optimizing care. Harm reduction for this group to maximize their health and limit HIV transmission to others is also critical with respect to the rising incidence of newly diagnosed HIV-positive adolescents. Implementing a formal, multidisciplinary program that involves individual youths and their families for improved transition to adult HIV care will afford such adolescents a better chance for a healthy adulthood.

Short communication: high effectiveness of etravirine in routine clinical practice in treatment-experienced HIV type 1-infected patients

The effectiveness of etravirine has not been thoroughly investigated in routine clinical practice, where adherence rates and the heterogeneous nature of patients differ from the clinical trial setting. We evaluated the effectiveness of rescue regimens containing etravirine and the factors associated with treatment response. Multicenter retrospective cohort of all consecutive patients was recruited in a routine clinical practice setting. Patients were taking rescue regimens containing etravirine plus an optimized background regimen. The primary endpoint was the percentage of patients with HIV-1 RNA <50 copies/ml at week 48. The secondary endpoints were those factors associated with treatment response to etravirine. Endpoints were evaluated using univariate and multivariate analysis. A total of 122 patients were included with a median viral load of 11,938 (1055-55,500) copies/ml at baseline. The most frequent drugs in the backbone were darunavir/ritonavir in 98 (80.3%) patients and raltegravir in 76 (62.3%). In the full dataset analysis, 73% (89/122; 95% CI, 64-81%) of patients responded to treatment at week 48; in the on-treatment analysis, 82% (89/109; 95% CI, 71-87%) responded. The factors associated with treatment failure to etravirine [HR (95% CI)] were baseline CD4(+) T cell count <200 cells/mm(3) [2.45 (1.17-5.16)] and use of raltegravir [0.47 (0.22-0.99)] and darunavir [0.45 (0.21-0.98)] as backbone drugs. Skin rash was the only adverse event directly related to etravirine and led to withdrawal in three patients (2.5%). In routine clinical practice, rescue ETR-containing regimens are well tolerated and achieve rates of virological suppression higher than those observed in its pivotal clinical trials, especially when combined with darunavir and raltegravir.

Twenty-six years of HIV science: an overview of anti-HIV drugs metabolism

From the identification of HIV as the agent causing AIDS, to the development of effective antiretroviral drugs, the scientific achievements in HIV research over the past twenty-six years have been formidable. Currently, there are twenty-five anti-HIV compounds which have been formally approved for clinical use in the treatment of AIDS. These compounds fall into six categories: nucleoside reverse transcriptase inhibitors (NRTIs), nucleotide reverse transcriptase inhibitors (NtRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), protease inhibitors (PIs), cell entry inhibitors or fusion inhibitors (FIs), co-receptor inhibitors (CRIs), and integrase inhibitors (INIs). Metabolism by the host organism is one of the most important determinants of the pharmacokinetic profile of a drug. Formation of active or toxic metabolites will also have an impact on the pharmacological and toxicological outcomes. Therefore, it is widely recognized that metabolism studies of a new chemical entity need to be addressed early in the drug discovery process. This paper describes an overview of the metabolism of currently available anti-HIV drugs.

Endothelial, inflammatory, coagulation, metabolic effects and safety of etravirine in HIV-uninfected volunteers

The innate proatherosclerotic properties of non-nucleoside reverse transcriptase inhibitors have not previously been examined. Therefore, we performed a pilot study of etravirine (ETR) in healthy volunteers over 28 days. This investigation also allowed us to evaluate the safety of ETR over a period commonly used for HIV postexposure prophylaxis. ETR 200 mg twice daily was given to 28 healthy HIV-uninfected volunteers over 28 days. Flow-mediated dilation (FMD) of the brachial artery and circulating markers of inflammation, coagulation, and metabolism were measured at entry and at day 28. These circulating markers were also measured at day 35. Of the initial 28 subjects, 23 completed both entry and day 28 procedures. Two subjects were discontinued due to development of rash. No other major toxicities developed. The change in FMD over 28 days was minimal and not significant (0.03 [-3.21, 0.97] %; p=0.36). The post hoc estimated detectable absolute change in FMD with the 23 subjects in our study was 2.26%, which is an effect size that has been associated with future cardiovascular event rates in the general population; thus our study had sufficient power to find clinically relevant changes in FMD. In addition, there were no significant changes in any of the circulating markers from entry to day 28 or from day 28 to day 35. ETR did not demonstrate any innate proatherosclerotic properties over 28 days in these HIV-uninfected volunteers. ETR was generally well tolerated. Larger studies are warranted to confirm that ETR can be used safely as part of HIV postexposure prophylaxis regimens.

Selection of nonnucleoside reverse transcriptase inhibitor-associated mutations in HIV-1 subtype C: evidence of etravirine cross-resistance

Prevalence of etravirine genotypic resistance was assessed among 92 HIV-1C-infected patients failing nevirapine and efavirenz-based regimens from a cohort of 552 Indian patients. Overall, prevalence of etravirine cross-resistance identified using the Tibotec Weighted Score was 41% (31.5% intermediately-resistant and 9.8% fully-resistant). The most frequently described nonnucleoside reverse transcriptase inhibitor-associated mutations included Y181 (35.9%), K101 (20.7%), G190 (17.4%), and V108 (15.2%). The resistant group demonstrated higher viral load (P = 0.01) and longer duration of antiretroviral treatment (P = 0.03) compared with the susceptible group.

Virological response with fully active etravirine: pooled results from the DUET-1 and DUET-2 trials

The objective of this subanalysis of the Phase III DUET trials was to examine virological response to an etravirine-containing regimen in patients harbouring virus fully sensitive to etravirine. Full etravirine sensitivity was defined as fold change in 50% effective concentration (FC) ≤3 or weighted genotypic score ≤2. At Week 48 in the etravirine group, 74% of patients with etravirine FC ≤3 and 77% with etravirine genotypic score ≤2 had viral load <50 HIV-1 RNA copies/mL, versus 48% and 46%, respectively, in the placebo group (P < 0.0001). Response rates increased with baseline phenotypic sensitivity score, but were consistently higher with etravirine (56-82%) than placebo (2-72%). Similar observations were made in patients harbouring virus with full etravirine and darunavir sensitivity. Our findings support current recommendations to include three active agents in treatment-experienced patients' regimens.

Clinical evaluation of the determination of plasma concentrations of darunavir, etravirine, raltegravir and ritonavir in dried blood spot samples

Background: Measurement of drug levels in plasma is currently the gold standard for pharmacological studies. However, venous sampling is not feasible in some populations (e.g., neonates) or may be difficult in certain situations, such as nonhospital-based settings. Dried blood spots (DBS) can be obtained by a simple fingerprick and the subsequent collection of blood on a filter card, allowing patient-friendly sample collection in non-hospital-based settings. Despite these advantages, thus far no clinical evaluation has been performed for the use of DBS concentrations as surrogates for plasma levels. Our purpose was to clinically evaluate DBS sampling for the determination of plasma concentrations for the novel antiretroviral drugs etravirine, darunavir/ritonavir and raltegravir. Results: DBS concentrations were measured in 11 HIV-infected patients using LC–MS/MS. DBS concentrations were proportional to plasma concentrations. All drug concentrations were higher in DBS than in plasma samples. The plasma:DBS ratio and the respective relative standard error of estimate (RSE) of darunavir, etravirine, raltegravir and ritonavir were 0.632 (4.97% RSE), 0.523 (4.84% RSE), 0.617 (14.9% RSE) and 0.592 (2.99% RSE), respectively. Hematocrit did not explain variability in our study. Conclusions: DBS are reproducibly correlated to plasma levels and can be used for monitoring antiretroviral drug exposure in HIV-infected patients.

Connection domain mutations in HIV-1 reverse transcriptase do not impact etravirine susceptibility and virologic responses to etravirine-containing regimens

Connection domain mutations (CDMs) in HIV-1 reverse transcriptase (RT) alter susceptibility to some nucleoside/nonnucleoside RT inhibitors (NRTIs/NNRTIs). Their effects on susceptibility and virologic responses to etravirine were analyzed. Seventeen CDMs were evaluated: L283I, E312Q, G333D, G333E, G335C, G335D, N348I, A360I, A360T, A360V, V365I, T369I, A371V, A376S, I393L, E399D, and E399G. CDM prevalence and effects on virologic responses were analyzed retrospectively using clinical data. The effects on etravirine susceptibility were assessed in clinical samples and confirmed using site-directed mutants. The most prevalent CDMs (>10%) were A371V, E399D, A376S, N348I, A360T, G333E, and L283I. CDM presence was positively correlated with thymidine analogue-associated mutations, but not with NNRTI resistance-associated mutations (RAMs). The presence or number of CDMs did not significantly reduce etravirine susceptibility, although small reductions were seen in samples with G333D, N348I, A360V, T369I, and A376S. N348I, E399G, and N348I/T369I were associated with reduced etravirine susceptibility when present with K103N, L100I, or Y181C. N348I or T369I was associated with reduced etravirine susceptibility when present with K101P or K103R/V179D. Virologic responses to an etravirine-containing regimen were slightly diminished when G333D, G335D, or A376S was present, but this was not confirmed in subgroups with higher baseline resistance or without etravirine RAMs. CDMs alone do not confer substantial reductions in etravirine susceptibility but can further reduce etravirine susceptibility in combination with certain NNRTI mutations. Since virologic responses to etravirine were not affected by CDMs, the clinical impacts of these mutations on etravirine susceptibility appear to be minimal.

Self-report of current and prior antiretroviral drug use in comparison to the medical record among HIV-infected patients receiving primary HIV care

OBJECTIVE

Patient antiretroviral (ARV) therapy knowledge is essential for regimen adherence, successful therapeutic response, and minimization of resistance evolution. Moreover, a complete and accurate patient ARV history is needed to construct efficacious and tolerable future regimens. In this study we assessed the ability of HIV-infected patients receiving care in a university infectious diseases clinic to accurately recall current and past ARVs.

METHODS

A convenience sample (n = 205) of UNC HIV Clinical Cohort participants (n = 1840) completed a comprehensive in-person interview. Patients were asked about current and ever ARV use and were provided proprietary and generic ARV names and photographs. Self-reported sensitivity for current and ever ARV use (proportion that correctly identified all recorded ARVs), was calculated using the medical record as the gold standard.

RESULTS

One hundred and eighty-five patients had received ARVs at some point after enrollment in the cohort study (ever users). For current ARV use (n = 138), self-reported sensitivity was 63% (95% CI: 54-71). For ever use (n = 185), sensitivity was 18% (95% CI: 13-24).

CONCLUSION

Self-reported cumulative ARV use is not accurate. Since HIV-infected patients are prescribed a number of medications over their treatment course, it is necessary to develop new medication reconciliation techniques that are not dependent on patient memory or knowledge in order to improve patient outcomes.

Pharmacokinetic interactions between etravirine and non-antiretroviral drugs

Etravirine (formerly TMC125) is a non-nucleoside reverse transcriptase inhibitor (NNRTI) with activity against wild-type and NNRTI-resistant strains of HIV-1. Etravirine has been approved in several countries for use as part of highly active antiretroviral therapy in treatment-experienced patients. In vivo, etravirine is a substrate for, and weak inducer of, the hepatic cytochrome P450 (CYP) isoenzyme 3A4 and a substrate and weak inhibitor of CYP2C9 and CYP2C19. Etravirine is also a weak inhibitor of P-glycoprotein. An extensive drug-drug interaction programme in HIV-negative subjects has been carried out to assess the potential for pharmacokinetic interactions between etravirine and a variety of non-antiretroviral drugs. Effects of atorvastatin, clarithromycin, methadone, omeprazole, oral contraceptives, paroxetine, ranitidine and sildenafil on the pharmacokinetic disposition of etravirine were of no clinical relevance. Likewise, etravirine had no clinically significant effect on the pharmacokinetics of fluconazole, methadone, oral contraceptives, paroxetine or voriconazole. No clinically relevant interactions are expected between etravirine and azithromycin or ribavirin, therefore, etravirine can be combined with these agents without dose adjustment. Fluconazole and voriconazole increased etravirine exposure 1.9- and 1.4-fold, respectively, in healthy subjects, however, no increase in the incidence of adverse effects was observed in patients receiving etravirine and fluconazole during clinical trials, therefore, etravirine can be combined with these antifungals although caution is advised. Digoxin plasma exposure was slightly increased when co-administered with etravirine. No dose adjustments of digoxin are needed when used in combination with etravirine, however, it is recommended that digoxin levels should be monitored. Caution should be exercised in combining rifabutin with etravirine in the presence of certain boosted HIV protease inhibitors due to the risk of decreased exposure to etravirine. Although adjustments to the dose of clarithromycin are unnecessary for the treatment of most infections, the use of an alternative macrolide (e.g. azithromycin) is recommended for the treatment of Mycobacterium avium complex infection since the overall activity of clarithromycin against this pathogen may be altered when co-administered with etravirine. Dosage adjustments based on clinical response are recommended for clopidogrel, HMG-CoA reductase inhibitors (e.g. atorvastatin) and for phosphodiesterase type-5 inhibitors (e.g. sildenafil) because changes in the exposure of these medications in the presence of co-administered etravirine may occur. When co-administered with etravirine, a dose reduction or alternative to diazepam is recommended. When combining etravirine with warfarin, the international normalized ratio (INR) should be monitored. Systemic dexamethasone should be co-administered with caution, or an alternative to dexamethasone be found as dexamethasone induces CYP3A4. Caution is also warranted when co-administering etravirine with some antiarrhythmics, calcineurin inhibitors (e.g. ciclosporin) and antidepressants (e.g. citalopram). Co-administration of etravirine with some antiepileptics (e.g. carbamazepine and phenytoin), rifampicin (rifampin), rifapentine or preparations containing St John's wort (Hypericum perforatum) is currently not recommended as these are potent inducers of CYP3A and/or CYP2C and may potentially decrease etravirine exposure. Antiepileptics that are less likely to interact based on their known pharmacological properties include gabapentin, lamotrigine, levetiracetam and pregabalin. Overall, pharmacokinetic and clinical data show etravirine to be well tolerated and generally safe when given in combination with non-antiretroviral agents, with minimal clinically significant drug interactions and no need for dosage adjustments of etravirine in any of the cases, or of the non-antiretroviral agent in the majority of cases studied.

The relationship of CCR5 antagonists to CD4+ T-cell gain: a meta-regression of recent clinical trials in treatment-experienced HIV-infected patients

PURPOSE

Lower CD4+ T-cell counts are related to increased morbidity and mortality despite virologic suppression. CCR5 antagonists are associated with robust CD4+ T-cell responses. We examined the relationship of CCR5 antagonists to CD4+ T-cell gains.

DESIGN

Meta-regression of recent phase 2-3 trials evaluating new antiretroviral agents in treatment-experienced subjects.

METHODS

We analyzed the relationship of CCR5 antagonists to CD4+ T-cell count increase 24 weeks after initiating the new regimen using a linear model with generalized estimating equations controlling for differing rates of virologic suppression. Each treatment group was treated as a data point weighted by sample size.

RESULTS

We included 46 treatment groups from 17 trials (11 groups from 5 trials used CCR5 antagonists). Controlling for average baseline HIV-1 RNA and proportion of subjects achieving HIV-1 RNA <50 copies/mL, use of a CCR5 antagonist was associated with an additional significant CD4+ T-cell gain of +30/μL (95% CI, 19-42) at 24 weeks compared to treatment groups not using a CCR5 antagonist.

CONCLUSIONS

Use of a CCR5 antagonist was associated with an enhanced CD4+ T-cell count response independent of virologic suppression. This observation supports further evaluation of CCR5 antagonists in patients with discordant immunologic and virologic responses to ART.

Pharmacokinetic interactions of maraviroc with darunavir-ritonavir, etravirine, and etravirine-darunavir-ritonavir in healthy volunteers: results of two drug interaction trials

The effects of darunavir-ritonavir at 600 and 100 mg twice daily (b.i.d.) alone, 200 mg of etravirine b.i.d. alone, or 600 and 100 mg of darunavir-ritonavir b.i.d. with 200 mg etravirine b.i.d. at steady state on the steady-state pharmacokinetics of maraviroc, and vice versa, in healthy volunteers were investigated in two phase I, randomized, two-period crossover studies. Safety and tolerability were also assessed. Coadministration of 150 mg maraviroc b.i.d. with darunavir-ritonavir increased the area under the plasma concentration-time curve from 0 to 12 h (AUC12) for maraviroc 4.05-fold relative to 150 mg of maraviroc b.i.d. alone. Coadministration of 300 mg maraviroc b.i.d. with etravirine decreased the maraviroc AUC12 by 53% relative to 300 mg maraviroc b.i.d. alone. Coadministration of 150 mg maraviroc b.i.d. with etravirine-darunavir-ritonavir increased the maraviroc AUC12 3.10-fold relative to 150 mg maraviroc b.i.d. alone. Maraviroc did not significantly affect the pharmacokinetics of etravirine, darunavir, or ritonavir. Short-term coadministration of maraviroc with darunavir-ritonavir, etravirine, or both was generally well tolerated, with no safety issues reported in either trial. Maraviroc can be coadministered with darunavir-ritonavir, etravirine, or etravirine-darunavir-ritonavir. Maraviroc should be dosed at 600 mg b.i.d. with etravirine in the absence of a potent inhibitor of cytochrome P450 3A (CYP3A) (i.e., a boosted protease inhibitor) or at 150 mg b.i.d. when coadministered with darunavir-ritonavir with or without etravirine.

Safety and tolerability of lersivirine, a nonnucleoside reverse transcriptase inhibitor, during a 28-day, randomized, placebo-controlled, Phase I clinical study in healthy male volunteers

BACKGROUND

Lersivirine is a nonnucleoside reverse transcriptase inhibitor undergoing clinical development for the treatment of HIV-1.

OBJECTIVE

The goal of this study was to investigate the safety and tolerability of multiple oral doses of lersivirine administered to healthy male subjects to assist in the planning of longer term studies.

METHODS

This was a randomized, double-blind, double-dummy, placebo-controlled, parallel-group, multicenter, Phase I clinical study in fasting, healthy male volunteers. Subjects were randomly assigned in a ratio of 7:7:4:4 to receive lersivirine 500 mg BID, lersivirine 750 mg once daily, efavirenz 600 mg once daily, or placebo once daily for 28 days. Safety and tolerability were assessed throughout the study by continuous collection of adverse events (AEs), including adverse drug reactions, illnesses with onset during the study, exacerbation of previous illnesses, and clinically significant changes in physical examination findings. Vital sign measurements and ECGs were performed at screening; on day 1 (predose and 2, 3, and 4 hours postdose); on days 7, 14, 21, and 28 (predose); at discharge; and at follow-up. Safety laboratory tests (including hematology, chemistry, and urinalysis) were performed at screening; days 0, 7, 14, 21, and 27; and at follow-up.

RESULTS

Of the 66 healthy male subjects enrolled (age range, 21-51 years; body mass index, 18.1-29.9 kg/m(2)), 40 were white, 22 were Asian, 3 were black, and 1 was of mixed race. There were no clinically significant laboratory abnormalities, including changes in lipid profile, liver or renal function test results, or ECG findings. Overall, 86% (18/21) of subjects in the lersivirine 500-mg BID group, 81% (17/21) in the lersivirine 750-mg once-daily group, 92% (11/12) in the efavirenz 600-mg once-daily group, and 92% (11/12) in the placebo group experienced at least one treatment-related AE. Eight subjects were permanently discontinued from the study; 4 subjects in the efavirenz group (3 of whom participated in the trial at the Brussels study center) were permanently discontinued due to AEs considered to be treatment related. No subjects receiving lersivirine permanently discontinued the study due to treatment-related AEs, although one subject temporarily discontinued treatment. In addition, 4 subjects withdrew consent (2 subjects [1 of whom was at the Brussels study center] receiving lersivirine 750 mg once daily and 2 subjects [1 of whom was at the Brussels study center] receiving efavirenz). There were no deaths or serious AEs in any of the study groups.

CONCLUSION

Lersivirine appeared to be well tolerated after 28 days of continuous dosing in this small, selected group of young, healthy male volunteers.

Characterization of the E138K resistance mutation in HIV-1 reverse transcriptase conferring susceptibility to etravirine in B and non-B HIV-1 subtypes

We have selected for resistance to etravirine (ETR) and efavirenz (EFV) in tissue culture using three subtype B, three subtype C, and two CRF02_AG clinical isolates, grown in cord blood mononuclear cells. Genotypic analysis was performed at baseline and at various weeks of selection. Phenotypic resistance in regard to ETR, EFV, and nevirapine (NVP) was evaluated at weeks 25 to 30 for all ETR-selected viruses and in viral clones that contained specific resistance mutations that were inserted by site-directed mutagenesis into pNL-4.3 and AG plasmids. The results show that ETR selected mutations at positions V90I, K101Q, E138K, V179D/E/F, Y181C, V189I, G190E, H221H/Y, and M230L and that E138K was the first of these to emerge in most instances. The time to the emergence of resistance was longer in the case of ETR (18 weeks) compared to EFV (11 weeks), and no differences in the patterns of emergent mutations could be documented between the B and non-B subtypes. Viral clones containing E138K displayed low-level phenotypic resistance to ETR (3.8-fold) and modestly impaired replication capacity (2-fold) compared to wild-type virus. ETR-selected virus showed a high degree of cross-resistance to NVP but not to EFV. We identified K101Q, E138K, V179E, V189I, G190E, and H221Y as mutations not included among the 17 currently recognized resistance-associated mutations for ETR.

No pol mutation is associated independently with the lack of immune recovery in patients infected with HIV and failing antiretroviral therapy

An investigation was undertaken to determine whether specific pol mutations hinder long-term immune recovery regardless of virological response. In total, 826 patients with >50 HIV RNA copies/ml, who underwent genotypic resistance testing between 1 January 2000 and 31 December 2003 after >3 years of antiretroviral treatment, and were followed up for >3 years after genotypic resistance testing, were analyzed retrospectively. The outcome of the study was the lack of immune recovery after >3 years of follow-up, defined as a slope by linear regression <0. The viremia detectability ratio was defined as the number of HIV RNA values of >50 copies/ml divided by the number of HIV RNA measurements during follow-up. Logistic regression was used for univariable and multivariable analysis. Median (Q1, Q3) values at baseline were the following: age 40 (37, 45) years, years on antiretroviral therapy 4.45 (3.65, 5.47), HIV RNA 3.91 (3.39, 4.53) log(10) copies/ml, CD4+ T-cell 358 (211, 524)/µl. After 3.13 years of follow-up, 375 patients (45.4%) showed a lack of immune recovery. The risk of lack of immune recovery increased independently with increasing baseline CD4+ counts (OR=1.104 per 50-cell increase, 95% CI=1.069-1.142, P<0.0001), increasing viremia detectability ratio during follow-up (OR=1.145 per 0.1-unit increase, 95% CI=1.093-1.202, P<0.0001), and with earlier calendar years of resistance testing (overall effect: P=0.0007). In conclusion, no pol mutation is associated independently with the lack of immune recovery.

Early antiretroviral therapy for patients with acute aids-related opportunistic infections: a cost-effectiveness analysis of ACTG A5164

PURPOSE

ACTG A5164 demonstrated that early antiretroviral therapy (ART) in HIV-infected patients with acute opportunistic infections (OIs) reduced death and AIDS progression compared to ART initiation 1 month later. We project the life expectancies, costs, and incremental cost-effectiveness ratios (ICERs) of these strategies.

METHOD

using an HIV simulation model, we compared 2 strategies for patients with acute OIs: (1) an intervention to deliver early ART, and (2) deferred ART. Parameters from ACTG A5164 included initial mean CD4 count (47/microL), linkage to outpatient care (87%), and immune reconstitution inflammatory syndrome 1 month after ART initiation (7%). The estimated intervention cost was $1,650/patient.

RESULTS

early ART lowered projected 1-year mortality from 10.4% to 8.2% and increased life expectancy from 10.07 to 10.39 quality-adjusted life-years (QALYs). Lifetime costs increased from $385,220 with deferred ART to $397,500 with early ART, primarily because life expectancy increased, producing an ICER of $38,600/QALY. Results were most sensitive to increased intervention cost and decreased virologic efficacy in the early ART strategy.

CONCLUSIONS

an intervention to initiate ART early in patients with acute OIs improves survival and meets US cost-effectiveness thresholds. Programs should be developed to implement this strategy at sites where HIV-infected patients present with OIs.

Drug interactions of new antiretroviral drugs

A systematic review was made of the drug interactions of new antiretroviral drugs. In order to do this a search was made in Pubmed to find articles published from January 2007 to September 2009 and the full-text articles which contained information about new antiretroviral drugs were selected. This search was then complemented with information from the technical specifications of the drugs and consultations made on webpages specialized in antiretroviral interactions: www.interaccioneshiv.com and www.hiv-druginteractions.org. The information about the possible interactions of new antiretroviral drugs with one another and with the therapeutic groups which are most widely used in patients infected with the human immunodeficiency virus was analyzed.

Impact of the background regimen on virologic response to etravirine: pooled 48-week analysis of DUET-1 and -2

PURPOSE

This subgroup analysis of the phase 3 DUET trials examined the impact of the background regimen on virologic response to etravirine in treatment-experienced patients.

METHODS

Patients received etravirine 200 mg or placebo, both twice daily with a background regimen of darunavir/ritonavir, investigator-selected nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs), and optional enfuvirtide. Virologic response at week 48 (viral load <50 HIV-1 RNA copies/mL) was analyzed by the number and activity of background agents.

RESULTS

Baseline phenotypic sensitivity score (PSS), enfuvirtide use, darunavir fold change in 50% effective concentration (FC), and number of baseline darunavir resistance-associated mutations (RAMs) were significant predictors of response to etravirine (P < .0001, P = .0018, P < .0001, and P = .0120, respectively). The number of active NRTIs was not a significant predictor of response (P = .0626). The highest response rates in etravirine-treated patients were associated with PSS ≥2, de novo enfuvirtide use, darunavir FC ≤10, ≤1 darunavir RAM, and ≥2 active NRTIs. Virologic response was consistently higher in etravirine-treated patients than placebo-treated patients, regardless of the activity of the background regimen. Response rates according to baseline PSS were 46% to 79% in the etravirine group versus 6% to 75% in the placebo group.

CONCLUSION

The results of this subanalysis demonstrate higher virologic response rates with increased activity of the background regimen in both treatment groups, with the highest responses achieved in patients using ≥2 active agents in addition to etravirine.