Safety of enfuvirtide in combination with an optimized background of antiretrovirals in treatment-experienced HIV-1-infected adults over 48 weeks

Structural Insight into Paramyxovirus and Pneumovirus Entry Inhibition

Paramyxoviruses and pneumoviruses infect cells through fusion (F) protein-mediated merger of the viral envelope with target membranes. Members of these families include a range of major human and animal pathogens, such as respiratory syncytial virus (RSV), measles virus (MeV), human parainfluenza viruses (HPIVs), and highly pathogenic Nipah virus (NiV). High-resolution F protein structures in both the metastable pre- and the postfusion conformation have been solved for several members of the families and a number of F-targeting entry inhibitors have progressed to advanced development or clinical testing. However, small-molecule RSV entry inhibitors have overall disappointed in clinical trials and viral resistance developed rapidly in experimental settings and patients, raising the question of whether the available structural information may provide a path to counteract viral escape through proactive inhibitor engineering. This article will summarize current mechanistic insight into F-mediated membrane fusion and examine the contribution of structural information to the development of small-molecule F inhibitors. Implications are outlined for future drug target selection and rational drug engineering strategies.

Immunostimulatory effects on THP-1 cells by peptide or protein pharmaceuticals associated with injection site reactions

Injection site reaction (ISR) is a common side-effect associated with the use of peptide or protein pharmaceuticals. These types of pharmaceuticals-induced activation of antigen-presenting cells is assumed to be a key step in the pathogenesis of immune-mediated ISR. The present study was designed to evaluate the immunostimulatory properties of peptide or protein pharmaceuticals using human monocytic THP-1 cells. Here, THP-1 cells, with or without phorbol-12-myristate-13-acetate (PMA) pretreatment, were exposed to enfuvirtide and glatiramer acetate (positive controls) or evolocumab (negative control) for 6 or 24 h. PMA treatment differentiated non-adherent monocytic THP-1 (nTHP-1) cells into adherent macrophagic THP-1 (pTHP-1) cells that highly express CD11b and CD36. Enfuvirtide increased the release of cytokines, e.g. TNFα, MIP-1β, and MCP-1, and expression of CD86 and CD54 on nTHP-1 cells at 24 h. Similar immunostimulatory properties of glatiramer acetate were observed both in the nTHP-1 and pTHP-1 cells at 6 h, but the responses were very weak in the pTHP-1 cells. Evolocumab did not affect cytokine secretion or cell surface marker expression in either cell type. Taken together, these in vitro THP-1 cell assays revealed the immunostimulatory properties of enfuvirtide and glatiramer acetate. This assay platform thus could serve as a powerful tool in evaluating potential immune-related ISR risks of peptide or protein pharmaceuticals in humans.

Effectiveness of nutritional treatment and synbiotic use on gastrointestinal symptoms reduction in HIV-infected patients: Randomized clinical trial

BACKGROUND & AIMS

Gastrointestinal symptoms are among the most frequent reported complaints by people living with HIV and AIDS (PLWHA). Treatments that aim to attenuate these symptoms are important to avoid low adherence to antiretroviral therapy and to improve the quality of life. This study aimed to evaluate the effectiveness of nutritional treatment and synbiotic use in PLWHA on reducing gastrointestinal symptoms.

METHODS

A randomized clinical trial nested to an outpatient cohort was conducted to evaluate the effectiveness of two treatments for gastrointestinal symptoms reduction in adult patients with antiretroviral therapy presenting at least one gastrointestinal symptom: 1) nutritional treatment + placebo (6 g maltodextrin) and 2) nutritional treatment + synbiotic (Lactobacillus and Bifidobacterium strains + 6 g fructooligosaccharides). Placebo and synbiotic were consumed twice a day during six months. The primary outcome variable was percentage reduction in the incidence of diarrhea, and secondary outcomes the decrease in the incidence of nausea and/or vomiting, dyspepsia, heartburn, constipation, flatulence, and the presence of three or more gastrointestinal symptoms.

RESULTS

Out of 283 patients evaluated for eligibility, 64 met inclusion criteria to enter in this study with 1:1 allocation ratio. Both analyzed groups were homogeneous regarding sociodemographic, clinical and lifestyle variables at baseline. In the intergroup analysis, no difference was found between groups except for heartburn, which had a higher reduction in the placebo group (0.01). Regarding the intragroup analysis, in the placebo group a significant decrease in diarrhea (p = 0.02) and heartburn (p < 0.01) were observed while there was a significant reduction for nausea e/or vomit (p = 0.01), dyspepsia (p = 0.10), diarrhea (p = 0.01) and constipation (p = 0.08) in the synbiotic group.

CONCLUSIONS

Diarrhea decreased in both groups, but no statistical difference between treatments was observed. The use of synbiotic appeared to reduce a greater number of symptoms although there were no statistical differences in the intergroup analysis. This clinical trial was registered at ClinicalTrials.gov (NCT02180035).

Cost-Effectiveness of Single- Versus Generic Multiple-Tablet Regimens for Treatment of HIV-1 Infection in the United States

Background

The possibility of incorporating generics into combination antiretroviral therapy and breaking apart once-daily single-tablet regimens (STRs), may result in less efficacious medications and/or more complex regimens with the expectation of marked monetary savings. A modeling approach that assesses the merits of such policies in terms of lifelong costs and health outcomes using adherence and effectiveness data from real-world U.S. settings.

Methods

A comprehensive computer-based microsimulation model was developed to assess the lifetime health (life expectancy and quality adjusted life-years—QALYs) and economic outcomes in HIV-1 infected patients initiating STRs compared with multiple-table regimens including generic medications where possible (gMTRs). The STRs considered included tenofovir disoproxil fumarate/emtricitabine and efavirenz or rilpivirine or elvitegravir/cobicistat. gMTRs substitutions included each counterpart to STRs, including generic lamivudine for emtricitabine and generic versus branded efavirenz.

Results

Life expectancy is estimated to be 1.301 years higher (discounted 0.619 QALY gain) in HIV-1 patients initiating a single-tablet regimen in comparison to a generic-based multiple-table regimen. STRs were associated with an average increment of $26,547.43 per patient in medication and $1,824.09 in other medical costs due to longer survival which were partially offset by higher inpatients costs ($12,035.61) with gMTRs treatment. Overall, STRs presented incremental lifetime costs of $16,335.91 compared with gMTRs, resulting in an incremental cost-effectiveness ratio of $26,383.82 per QALY gained.

Conclusions

STRs continue to represent good value for money under contemporary cost-effectiveness thresholds despite substantial price reductions of generic medications in the U. S.

Nanoformulation of antiretroviral drugs enhances their penetration across the blood brain barrier in mice

Eradication of virus by sanctuary sites is a main goal in HIV management. The central nervous system (CNS) is a classic model of sanctuary where viral replication occurs despite a complete viral suppression in peripheral blood. In recent years, nanotechnologies have provided a great promise in the eradication of HIV from the CNS. We hereby demonstrate for the first time that the structurally complex antiretroviral drug enfuvirtide (Enf), which normally is unable to penetrate the cerebrospinal fluid, is allowed to cross the blood brain barrier (BBB) in mice by conjugation with a nanoconstruct. Iron oxide nanoparticles coated with an amphiphilic polymer increase Enf translocation across the BBB in both in vitro and in vivo models. The mechanism involves the uptake of nanoconjugated-Enf in the endothelial cells, the nanocomplex dissociation and the release of the peptide, which is eventually excreted by the cells in the brain parenchyma.

FROM THE CLINICAL EDITOR

Despite the success of cocktail therapy of antiretroviral drugs, the complete eradication of HIV remains elusive, due to existence of viral sanctuary sites. The authors showed in this study that an antiretroviral drug complexed with iron oxide nanoparticles and coated with PMA amphiphilic polymer crosses the blood brain barrier. Furthermore, there was significant anti-viral activity. The results would aid further drug designs to eradicate HIV.

Quality of Life and Tolerability After Administration of Enfuvirtide with a Thin-Walled Needle: QUALITÉ Study

PURPOSE

Use of enfuvirtide-containing regimens leads to virologic and immunologic benefits and quality of life (QoL) improvements. This study (QUALITE) was designed to primarily identify baseline predictors of QoL improvements and characterize injection site reaction (ISR) signs/symptoms using a thinner/shorter needle.

METHOD

Enfuvirtide-naïve, antiretroviral (ARV)-experienced patients with CD4 counts >50 cells/mm3 enrolled in this prospective, 12-week, multisite, open-label study. Patients self-administered enfuvirtide, 90 mg bid, using thin-walled, 31-gauge/8-mm needles in combination with other ARVs. QoL was evaluated with MOS-HIV.

RESULTS

Of the 361 patients enrolled, 346 contributed to QoL assessments. Baseline median HIV RNA and CD4 counts were 4.21 log10 copies/mL and 203 cells/mm3, respectively. Although no baseline factors were predictive of week 12 QoL improvement, 9 of 11 MOS-HIV domain scores improved significantly, including physical function (p = .0002) and mental health (p = .0006). Through week 12, 87% of patients reported ISRs; 59% and 28% reported worst pain/discomfort grade < or = 1 and grade > or = 2, respectively, and none were considered serious. Patients reported that self-injection minimally impacted daily functioning or activities.

CONCLUSION

Although no predictors of QoL were identified, significant improvements in QoL were observed with minimal clinically significant ISRs (grade > or = 2) using the 31-gauge/8-mm needle.

Virologic and Immunologic Impact and Durability of Enfuvirtide-Based Antiretroviral Therapy in HIV-Infected Treatment-Experienced Patients in a Clinical Setting

OBJECTIVE

To evaluate the effectiveness and safety of enfuvirtide-based therapy in treatment-experienced patients in a clinical setting.

METHOD

Retrospective study of treatment-experienced patients receiving enfuvirtide-based therapy for a minimum of 2 months. Endpoints included virologic suppression, virologic rebound, immunologic response, and adverse events.

RESULTS

Sixty-four patients were eligible for inclusion in the analysis. Median baseline viral load and CD4+ count were 4.7 log10 copies/mL (interquartile range [IQR], 4.0-5.2) and 150 cells/mm3 (IQR, 60-250), respectively. At month 12, viral load declined by a median of 2.53 log10 copies/mL (IQR, 0.97-3.12). The unadjusted median time to virologic suppression was 7.7 months (95% CI 4.1-10.4 months). Baseline viral load and number of protease inhibitors in the current regimen were significantly associated with virologic suppression following multivariate analysis (hazard ratio [HR] 0.45, 95% CI 0.31-0.63, p < .0001, and HR 0.51, 95% CI 0.27-0.94, p = .03, respectively). Among the 42 patients who attained sustained virologic suppression, 10 experienced virologic rebound during a median follow-up of 13.3 months (IQR, 7.0-19.1). Injection site reactions were reported in 33 (52%) patients, resulting in treatment discontinuation in nine patients.

CONCLUSION

Enfuvirtide-based therapy provides durable antiretroviral activity for treatment-experienced patients in a clinical setting.

Improvement of HIV fusion inhibitor C34 efficacy by membrane anchoring and enhanced exposure

OBJECTIVES

The aim of the present work was to evaluate the interaction of two new HIV fusion inhibitors {HIVP3 [C34-polyethylene glycol (PEG)₄-cholesterol] and HIVP4 [(C34-PEG₄)₂-cholesterol]} with membrane model systems and human blood cells in order to clarify where and how the fusion inhibitors locate, allowing us to understand their mechanism of action at the molecular level, and which strategies may be followed to increase efficacy.

METHODS

Lipid vesicles with defined compositions were used for peptide partition and localization studies, based on the intrinsic fluorescence of HIVP3 and HIVP4. Lipid monolayers were employed in surface pressure studies. Finally, human erythrocytes and peripheral blood mononuclear cells (PBMCs) isolated from blood samples were used in dipole potential assays.

RESULTS

Membrane partition, dipole potential and surface pressure assays indicate that the new fusion inhibitors interact preferentially with cholesterol-rich liquid-ordered membranes, mimicking biological membrane microdomains known as lipid rafts. HIVP3 and HIVP4 are able to interact with human erythrocytes and PBMCs to a similar degree as a previously described simpler drug with monomeric C34 and lacking the PEG spacer, C34-cholesterol. However, the pocket-binding domain (PBD) of both HIVP3 and HIVP4 is more exposed to the aqueous environment than in C34-cholesterol.

CONCLUSIONS

The present data allow us to conclude that more efficient blocking of HIV entry results from the synergism between the membranotropic behaviour and the enhanced exposure of the PBD.

Closing the door to human immunodeficiency virus

The pandemic of human immunodeficiency virus type one (HIV-1), the major etiologic agent of acquired immunodeficiency disease (AIDS), has led to over 33 million people living with the virus, among which 18 million are women and children. Until now, there is neither an effective vaccine nor a therapeutic cure despite over 30 years of efforts. Although the Thai RV144 vaccine trial has demonstrated an efficacy of 31.2%, an effective vaccine will likely rely on a breakthrough discovery of immunogens to elicit broadly reactive neutralizing antibodies, which may take years to achieve. Therefore, there is an urgency of exploring other prophylactic strategies. Recently, antiretroviral treatment as prevention is an exciting area of progress in HIV-1 research. Although effective, the implementation of such strategy faces great financial, political and social challenges in heavily affected regions such as developing countries where drug resistant viruses have already been found with growing incidence. Activating latently infected cells for therapeutic cure is another area of challenge. Since it is greatly difficult to eradicate HIV-1 after the establishment of viral latency, it is necessary to investigate strategies that may close the door to HIV-1. Here, we review studies on non-vaccine strategies in targeting viral entry, which may have critical implications for HIV-1 prevention.

HIV integrase inhibitors in ART-experienced patients

PURPOSE OF REVIEW

We review the most recent clinical trials of integrase inhibitors (INIs) in antiretroviral therapy (ART)-experienced patients, including trails of new strategies such as intensification and simplification therapy with this new class of compounds.

RECENT FINDINGS

After the excellent results of the first-generation INIs [raltegravir (RAL) and elvitegravir] in the treatment of ART-experienced patients, dolutegravir--a new second-generation compound in this drug class--adds the possibility of rescuing ART-experienced patients after virologic failure to first-generation INIs like RAL. RAL may have a role in an intensification strategy--adding RAL to a suppressive ART therapy--that could have an effect in avoiding new cycles of infection and cellular activation. On the contrary, RAL has clearly shown efficacy in switching away from boosted protease inhibitors (PI/r). This simplification strategy may be an interesting option in patients suffering from side effects of boosted protease inhibitors. In simplification, the length of time of HIV suppression before the switch may be used as a marker of probable success.

SUMMARY

In ART-experienced patients INIs are a new and exciting part of the armamentarium for the control of HIV replication. INIs could play an interesting role in strategies such as intensification or simplification.

Cost-Effectiveness of Antiretroviral Therapy for Multidrug-Resistant HIV: Past, Present, and Future

In the early years of the highly active antiretroviral therapy (HAART) era, HIV with resistance to two or more agents in different antiretroviral classes posed a significant clinical challenge. Multidrug-resistant (MDR) HIV was an important cause of treatment failure, morbidity, and mortality. Treatment options at the time were limited; multiple drug regimens with or without enfuvirtide were used with some success but proved to be difficult to sustain for reasons of tolerability, toxicity, and cost. Starting in 2006, data began to emerge supporting the use of new drugs from the original antiretroviral classes (tipranavir, darunavir, and etravirine) and drugs from new classes (raltegravir and maraviroc) for the treatment of MDR HIV. Their availability has enabled patients with MDR HIV to achieve full and durable viral suppression with more compact and cost-effective regimens including at least two and often three fully active agents. The emergence of drug-resistant HIV is expected to continue to become less frequent in the future, driven by improvements in the convenience, tolerability, efficacy, and durability of first-line HAART regimens. To continue this trend, the optimal rollout of HAART in both rich and resource-limited settings will require careful planning and strategic use of antiretroviral drugs and monitoring technologies.

The effects of enfuvirtide therapy on body composition and metabolic parameters over 48 weeks in the TORO body imaging substudy

OBJECTIVE

The aim of the study was to compare the metabolic and morphological effects of enfuvirtide plus an optimized background (OB) regimen vs. OB alone (control group) in treatment-experienced patients in the T-20 vs. Optimized Regimen Only (TORO) studies.

METHODS

Body composition and metabolic changes were investigated in patients over 48 weeks, based on fasting chemistries, body weight, and other anthropometric measurements. Dual-energy X-ray absorptiometry (DEXA) and computed tomography (CT) scans were performed in a patient subgroup (n=155) at baseline and at weeks 24 and 48.

RESULTS

At week 48, mean changes from baseline were similar between treatment groups for glucose, insulin, C-peptide, total cholesterol, low-density lipoprotein (LDL) cholesterol, very low density lipoprotein (VLDL) cholesterol, high-density lipoprotein (HDL) cholesterol and triglyceride levels. The enfuvirtide group experienced a significant increase in body weight [mean change from baseline +0.99 kg; 95% confidence interval (CI) +0.54, +1.44] and, in those who had body scans, there was a significant increase in truncal fat (by DEXA: median change +419.4 g; 95% CI+71.3, +767.5) and total fat [visceral adipose tissue (VAT)+subcutaneous adipose tissue (SAT) by single-slice abdominal CT scan: median change +25.5 cm(2) ; 95% CI+8.9, +42.0] over 48 weeks; significant increases in these parameters were not seen in the control group. There was no significant change in truncal:peripheral fat ratio in either the enfuvirtide or the control group.

CONCLUSION

The addition of enfuvirtide to an OB regimen does not appear to have unfavourable effects on fat distribution or metabolic parameters.

Enfuvirtide: from basic investigations to current clinical use

IMPORTANCE OF THE FIELD

Drug resistance is a major challenge in the treatment of HIV infection. Enfuvirtide is the first entry inhibitor to have been approved for clinical use.

AREAS COVERED IN THIS REVIEW

Relevant information through searches of MEDLINE (1998 to June 2010) and meeting abstracts of major HIV/AIDS conferences (2003 - June 2010) using the search terms 'enfuvirtide', 'T-20' and 'fusion inhibitor'.

WHAT THE READER WILL GAIN

Enfuvirtide blocks HIV fusion to host cells. It works against the different HIV-1 variants but is not active against HIV-2. The recommended dosage of enfuvirtide is 90 mg b.i.d. subcutaneously. The two large Phase III pivotal clinical trials TORO 1 and 2 showed that enfuvirtide is an effective therapeutic option as rescue therapy in combination with other active antiretroviral drugs. Resistance to enfuvirtide is conferred by mutations in the HR1 region of gp41. Single and double mutations have been shown to result in high-level resistance to enfuvirtide. Postmarketing studies have been helpful to define more precisely the place of enfuvirtide in the sequence of antiretroviral therapy.

TAKE HOME MESSAGE

The emergence of new compounds and new classes of drugs, highly active against multiresistant virus but more convenient to administer than enfuvirtide, will probably prevent the extensive use of enfuvirtide. This drug remains attractive in some subgroups of patients because of its excellent systemic tolerance and the lack of interactions with the major cytochrome P450 isoenzymes.

Impact on health-related quality of life of a switch from enfuvirtide to raltegravir among multidrug-resistant HIV-1-infected patients: a randomized open-label trial (EASIER-ANRS 138)

BACKGROUND

among multidrug-resistant HIV-1-infected patients, enfuvirtide has demonstrated sustained efficacy, but long-term use is inconvenient due to twice-daily subcutaneous injections which often induce injection-site reactions. We investigated whether a switch from enfuvirtide to raltegravir, an orally available HIV-integrase inhibitor, may improve health-related quality of life (HRQoL).

METHODS

170 multidrug-resistant HIV-1-infected patients who were receiving enfuvirtide-based regimens were randomised to the maintenance of enfuvirtide or the switch to raltegravir at day 0. At week 24, all patients received raltegravir up to week 48. HRQoL was assessed at baseline and weeks 24 and 48 using a self-report MOS-HIV questionnaire. HRQoL scores were compared between arms using analysis of covariance (ANCOVA) models.

RESULTS

at week 24, least-squares means changes from baseline for the maintenance and the substitution arms were -5.3 and +5.8 (P = .001) for the pain score, -4.7 and +4.8 (P = .02) for the social functioning score, and -1.3 and +2.0 (P = .003) for the physical summary score, respectively.

CONCLUSION

among multidrug-resistant HIV-1-infected patients, a switch from enfuvirtide to raltegravir resulted in statistically significant improvements in multiple HRQoL dimensions over 24 weeks in comparison to the maintenance under enfuvirtide.

Novel antiretroviral combinations in treatment-experienced patients with HIV infection: rationale and results

Novel antiretroviral drugs offer different degrees of improvement in activity against drug-resistant HIV, short- and long-term tolerability, and dosing convenience compared with earlier drugs. Those drugs approved more recently and commonly used in treatment-experienced patients include the entry inhibitor enfuvirtide, protease inhibitors (PIs) [darunavir and tipranavir], a C-C chemokine receptor (CCR) type 5 antagonist (maraviroc), an integrase inhibitor (raltegravir) and etravirine, a non-nucleoside reverse transcriptase inhibitor (NNRTI). Novel agents in earlier stages of development include a CCR5 monoclonal antibody (PRO 140) administered subcutaneously once weekly, once-daily integrase inhibitors (elvitegravir and S/GSK1349572), and several nucleoside (nucleotide) reverse transcriptase inhibitors and NNRTIs. Bevirimat, a maturation inhibitor, has compromised activity in the presence of relatively common Gag polymorphisms. Viral suppression is necessary to control the evolution of drug resistance, reduce chronic immune activation that probably underlies the excess morbidity and mortality in HIV-infected patients, and reduce viral transmission, including transmitted drug resistance. In general, the proportion of viraemic patients who achieve suppression increases with the number of active pharmacokinetically compatible antiretroviral drugs in the regimen. In the ANRS139-TRIO trial, 86% of highly treatment-experienced patients treated with darunavir-ritonavir, etravirine and raltegravir had HIV RNA <50 copies/mL at 48 weeks. In patients who had received at least 12 weeks of a stable regimen and had no darunavir resistance-associated mutations, once-daily darunavir boosted with ritonavir 100 mg was virologically noninferior with better lipid effects than with the twice-daily dosing, which requires a 200 mg total daily dose of ritonavir. Raltegravir plus a boosted PI is being investigated for second-line therapy in patients not responding to NNRTI-based first-line treatment in resource-limited settings (RLS). However, concerns about this potential strategy include the low barrier against resistance of raltegravir, limited penetration of some PIs into the CNS and the unknown impact of integrase polymorphisms seen more commonly in non-B subtype HIV-1. In patients who have already achieved viral suppression, novel agents may be used to simplify the dosing schedule, lower costs (such as by switching to boosted PI monotherapy), reduce adverse events or preserve antiretroviral drug options, especially since the absence of an HIV eradication strategy implies the need for life-long combination antiretroviral therapy. Switching enfuvirtide to raltegravir eliminated painful injection-site reactions without compromising virological suppression. Two studies found different virological outcomes when patients were switched from lopinavir/ritonavir to raltegravir, but there was an improvement in the lipid profile. Simplifying to darunavir-ritonavir monotherapy after suppression of plasma HIV RNA to <50 copies/mL has been found to be safe with no emergence of resistance in cases of viral rebound, but longer-term data are needed. The initial suggestion that maraviroc may possess unique CD4+ T-cell boosting effects was not confirmed in several clinical trials. Improved understanding of HIV pathogenesis has opened new frontiers for research such as identifying the sources, consequences and optimal management of residual viraemia in those with plasma HIV RNA <50 copies/mL. Globally, however, one of the most urgent priorities is providing the increasing number of treatment-experienced virologically failing patients in RLS with access to optimal treatment, including those treatments based on novel antiretroviral agents.

Modelling the effects of adherence to the HIV fusion inhibitor enfuvirtide

Recently, the first drug in a new class of antiretroviral HIV drugs was approved, the fusion inhibitor enfuvirtide. We develop a mathematical model that describes the binding of the virus to T cells. We model the effect of enfuvirtide upon this process using impulsive differential equations. We find equilibria and determine stability in the case of no therapy and then when therapy is taken with perfect adherence. We determine analytical thresholds for the dosage and dosing intervals to ensure the disease-free equilibrium remains stable. We also explore the effects of partial adherence. Our theoretical results suggest that partial adherence may, at times, be worse than no therapy at all, but at other times may in fact as good as perfect adherence. It follows that patients should be counselled on the importance of adherence to this new antiretroviral drug.

Implementation of raltegravir in routine clinical practice: selection criteria for choosing this drug, virologic response rates, and characteristics of failures

BACKGROUND

Raltegravir (RAL) achieved remarkable virologic suppression rates in randomized-clinical trials, but today efficacy data and factors for treatment failures in a routine clinical care setting are limited.

METHODS

First, factors associated with a switch to RAL were identified with a logistic regression including patients from the Swiss HIV Cohort Study with a history of 3 class failure (n = 423). Second, predictors for virologic outcome were identified in an intent-to-treat analysis including all patients who received RAL. Last observation carried forward imputation was used to determine week 24 response rate (HIV-1 RNA >or= 50 copies/mL).

RESULTS

The predominant factor associated with a switch to RAL in patients with suppressed baseline RNA was a regimen containing enfuvirtide [odds ratio 41.9 (95% confidence interval: 11.6-151.6)]. Efficacy analysis showed an overall response rate of 80.9% (152/188), whereas 71.8% (84/117) and 95.8% (68/71) showed viral suppression when stratified for detectable and undetectable RNA at baseline, respectively. Overall CD4 cell counts increased significantly by 42 cells/microL (P < 0.001). Characteristics of failures were a genotypic sensitivity score of the background regimen <or=1, very low RAL plasma concentrations, poor adherence, and high viral load at baseline.

CONCLUSIONS

Virologic suppression rates in our routine clinical care setting were promising and comparable with data from previously published randomized-controlled trials.

Fuzeon-induced collagenophagic granuloma: a peculiar granulomatous injection site reaction to Fuzeon--a case report and review of literature

Enfuvirtide (ENF, T-20, or Fuzeon [Hoffman-La Roche Inc, Nutley, NJ, and Trimeris, Inc, Durham, NC]) is an HIV-1 fusion inhibitor and is the only injectable antiretroviral drug available. Injection site reactions (ISRs) are the most frequently reported adverse events, occurring in about 98% of patients. A granuloma annulare-like granulomatous ISR has been reported. We report a granulomatous ISR that is different from granuloma annulare and granuloma annulare-like reaction because it is rich in multinucleated giant cells engulfing altered collagen. We call this type of ISR a collagenophagic granuloma. Most previous reports-with the exception of 1 report-about ISRs with ENF treatment have used punch biopsies, which lack the depth to analyze the reticular dermis and subcutaneous tissue and, therefore, may have missed ISRs, which look like granuloma annulare, and the collagenophagic granulomatous reaction.

Prescribing and using self-injectable antiretrovirals: how concordant are physician and patient perspectives?

Background

The selection of agents for any treatment regimen is in part influenced by physician and patient attitudes. This study investigated attitudinal motivators and barriers to the use of self-injectable antiretroviral agents among physicians and patients and measured the degree of concordance between physician and patient perspectives.

Methods

Attitudes toward prescribing and usage of self-injectable antiretroviral therapy (SIAT) were assessed by structured interview in 2 cohorts sampled from the European Union and the USA: 499 HIV-treating physicians and 603 treatment-experienced HIV-infected patients. Motivators and barriers to prescribing SIAT were identified from statistical analysis of the associations between physicians' ratings of enfuvirtide-based therapy compared to standard oral-based therapy and 2 indicators of enfuvirtide prescribing behavior. Patients' attitudes were assessed by their responses to a written profile of enfuvirtide and their ratings of the likelihood of accepting a treatment offer.

Results

Both indicators of SIAT prescribing behavior were predicted by the same pattern of physician beliefs. Nonprescribing was associated with: (1) the belief that offering enfuvirtide would be perceived negatively by patients, leading to treatment refusal and nonadherence; (2) the belief that prescribing enfuvirtide is harder to justify in terms of time/resources; and (3) a lack of confidence in the efficacy and use of enfuvirtide in practice (all p < 0.05). However, physicians' beliefs were not in concordance with patients' views. After reading a profile of enfuvirtide, 76% patients said that they would be moderately or highly likely to accept a treatment offer, although most (72%) had not discussed enfuvirtide with their doctor. Patients' beliefs predicted the likelihood of accepting enfuvirtide.

Conclusion

Physician and patient beliefs about SIAT influence prescribing behavior and compliance yet may not be concordant, with patients having more positive attitudes towards SIAT than anticipated by physicians.

Canadian consensus guidelines for the optimal use of etravirine in the treatment of HIV-infected adults

BACKGROUND AND OBJECTIVES

A group of five Canadian physicians with significant experience in HIV management was convened. Their goal was to develop guidance specifically for Canadian HIV-treating physicians on the appropriate use of etravirine (TMC125, Intelence, Tibotec BVBA, Belgium) in adult HIV-infected patients.

METHODS

Evidence from the published literature, conference presentations and expert opinions of the group members were used to develop the recommendations. Feedback on the draft recommendations was obtained from this core group, and from seven other physicians across Canada with clinical HIV treatment expertise and experience in the use of etravirine, as well as two Canadian scientists with HIV expertise. The final recommendations represent the core group's consensus agreement, taking all feedback into consideration.

RESULTS AND CONCLUSIONS

The recommendations were developed to guide physicians in the optimal use of etravirine. The issues considered included HIV disease status, antiretroviral treatment history, drug resistance profiles, predictors of response to etravirine, background antiretroviral regimen and drug-drug interactions.

Antiretroviral therapy in HIV-infected patients with multidrug-resistant virus: applying the guidelines to practice

Abstract Current treatment guidelines recommend maintenance of HIV-1 viral load below detectable levels (<50 copies per milliliter), even in extensively treated patients with multidrug-resistant HIV-1. Given recent advances in drug development and the availability of new agents with activity against antiretroviral-resistant HIV-1 viral strains, this goal is increasingly attainable for treatment-experienced patients. A stepwise approach to management of patients harboring antiretroviral-resistant HIV is presented, including assessment of adherence, a description of the use of resistance testing and utilization of new antiretroviral agents.

Reassessment of enfuvirtide's role in the management of HIV-1 infection

BACKGROUND

The development of new protease inhibitors, new non-nucleoside reverse transcriptase inhibitors and novel therapeutic drug classes has dramatically changed the approach to managing HIV-1 patients with multidrug resistant virus. This has led many clinicians to reevaluate the clinical utility of enfuvirtide.

OBJECTIVES

To summarize recent literature on enfuvirtide and to reassess enfuvirtide's role in the management of HIV-1 infection.

METHODS

MEDLINE (1990 to February Week 2 2008) and EMBASE (1990 to 2008 week 8) databases were searched using the following terms: 'enfuvirtide', 'Fuzeon', 'T20', 'HIV fusion inhibitors', and 'HIV entry inhibitor'; limits: English language. Reference lists of articles deemed relevant were hand searched for additional publications. Significant abstracts from recent international HIV conferences were also identified.

CONCLUSION

Enfuvirtide can optimize the response to new combinations of HIV-1 drug regimens in multiresistant patients. Its inclusion as an active agent is effective but use is impacted by its high cost, inconvenient route of administration and cosmetic side-effect profile.

Postmarketing use of enfuvirtide in veterans: provider compliance with criteria for use, overall efficacy, and tolerability

BACKGROUND

Most enfuvirtide outcomes data come from controlled trials of limited duration rather than from routine experience. Because of its uniqueness, the Veterans Health Administration (VHA) implemented specific enfuvirtide prescribing and follow-up criteria (criteria for use; CFU) and then assessed providers' compliance with these criteria and outcomes.

OBJECTIVE

To report routine medical care experience with the prescribing, efficacy, and tolerability of enfuvirtide in a nonselective group of treatment-experienced, older, HIV-infected veterans.

METHODS

Veterans receiving at least one outpatient prescription for enfuvirtide between April 2003 and July 2005 were identified from the VHA's HIV Clinical Case Registry (CCR:HIV). Targeted retrospective chart extraction was completed to address inclusion/exclusion criteria and to evaluate patients' continued use, adherence, and tolerance. CCR:HIV data were used for determination of demographics, prescription records, and laboratory results. The final cohort was used to assess providers' compliance with VHA's CFU for enfuvirtide.

RESULTS

Of 275 evaluable subjects, between 52% and 93% who were prescribed enfuvirtide met each VHA CFU. Median change in CD4 cells and viral load from baseline to 6 months was +39 cells/mm(3) and -0.79 log(10) (p < 0.001) and at 2 years was +72 cells/mm(3) and -1.57 log(10) (p < 0.001); 41% and 55% of veterans achieved viral load less than 400 copies/mL at 6 months and 2 years, respectively. Seventy percent of veterans experienced injection site reactions (11% were treatment-limiting). New or worsening adverse effects occurred in 56% of veterans: 32% gastrointestinal, 19% musculoskeletal, and 10% respiratory. Seventy percent of veterans discontinued enfuvirtide within 2 years; the largest portion (12%) stopped treatment within the first month. Documented reasons for discontinuation included patient request (42%), suboptimal response/progression (24%), toxicity (18%), death (13%), and transfer of care outside of the VHA (3%).

CONCLUSIONS

In this treatment-experienced veteran cohort, providers prescribed enfuvirtide in accordance with most CFU, and favorable treatment responses were sustained in patients able to remain on therapy. Challenges that providers and patients face include ongoing education and support for successful long-term use.

Staphylococcus aureus brain abscess in an HIV-infected patient exposed to enfuvirtide

Brain abscesses are common among HIV-infected immunocompromised patients. Encephalitis caused by Toxoplasma gondii infection has to be presumed, on which treatment is initiated. The authors report an unusual case of a brain abscess caused by Staphylococcus aureus in an HIV-infected patient exposed to enfuvirtide, for which this empirical strategy failed.

Managing antiretroviral therapy: changing regimens, resistance testing, and the risks from structured treatment interruptions

The management of patients receiving therapy for human immunodeficiency virus infection has improved in recent years owing to factors such as new classes of antiretroviral drugs, new agents in existing classes, and reduced resistance rates when chronically infected patients begin treatment with preferred regimens. Transmitted resistance variants in approximately 10% of treatment-naive patients underline the need for pretreatment resistance testing, to improve rates of virologic efficacy. Structured treatment interruptions to reduce drug exposure and toxicity should not be used outside well-controlled research studies, since this practice has been associated with increased rates of death and disease progression.

Impact of education and support on the tolerability and quality of life in a cohort of HIV-1 infected patients treated with enfuvirtide (SURCOUF Study)

The aim of this study was to evaluate the quality of life and the intensity of the injection site reactions during the first 6 months of treatment with enfuvirtide according to the counseling and training provided by nurses and physicians. In this prospective, 6-month cohort, 61 HIV-1 infected adult patients starting enfuvirtide have been included. At baseline, 82% of the patients have either read information documents (23%) or received counseling (59%); 18% were self-injectors, 27.8% had a dual disposition (self-injector + third person), and 49.2% were injected by a third person. At month 6, among the 43 patients still on enfuvirtide, 59% have had no change in injection disposition, and 52% have the dual disposition. Quality of life and enfuvirtide acceptance improved during 6 months. With adequate education and choice of injection dispositions, treatment with enfuvirtide can lead to quality-of-life improvements.

Safety, tolerability and pharmacokinetics of enfuvirtide administered by a needle-free injection system compared with subcutaneous injection

Background

Injection site reactions (ISRs) can present a challenge to patients when using enfuvirtide (ENF). This study compared ISRs associated with use of a needle-free injection device (NFID) with those associated with a standard 27-gauge half-inch needle/syringe (NS).

Methods

In this single-blind, crossover study, 58 ENF-naive participants were randomized to self-administer ENF with the NFID for 4 weeks (followed by 4 weeks using NS) or with the NS for 4 weeks (followed by 4 weeks using the NFID). A primary composite endpoint of painful ISR was defined as the combination of grade 1–3 ongoing pain plus either associated grade 3–4 (≥25 mm) induration or grade 2–4 nodules/cysts (>20 mm). An ISR summary score described ISR frequency/severity. Self-reported device preference was also evaluated at baseline and at study completion.

Results

Fewer participants using NFID experienced the primary composite endpoint of painful ISRs (10/28; 35.7%) compared with NS (20/28; 71.4%) ( P=0.004). There was a trend towards a reduced incidence/severity of ISR signs and symptoms with NFID, with significant reductions seen in pain/discomfort and pruritus ( P<0.05 and P<0.01, respectively). At the end of the study, most participants (22/25; 88%) expressed a preference for NFID. Haematoma was the sole NFID-related serious adverse event, but this did not lead to discontinuation.

Conclusions

Compared with a standard NS, use of an NFID to administer ENF was associated with a substantially lower incidence of painful ISRs, was generally safe and well-tolerated, and was preferred by most participants in the study.

Patients' perception and effectiveness of a treatment containing enfuvirtide when used in HIV-infected patients without very advanced disease

PURPOSE

To evaluate the satisfaction with self-injected enfuvirtide (ENF) and the clinical outcome of HIV-infected patients without very advanced disease.

METHOD

ESPPE is a multicenter observational study that included 103 evaluated patients showing baseline characteristics predictive of positive outcome: CD4 >100 cells/mm3, viral load (VL) <100,000 copies/mL, previous treatment with a maximum of 10 antiretroviral drugs, and concomitant use of 2 active drugs. By using validated surveys, patients were questioned 6 months after the prescription of ENF about their quality of life (QoL) and acceptance of self-injections and adherence to the treatment.

RESULTS

At 6 months, the mean CD4 increase was 121 cells/mm3 (p < .05) and 65% (intent-to-treat, ENF stopped=failure) had VL <50 copies/mL (p < .001). Fourteen patients discontinued the treatment, mostly due to intolerance (6). The majority (>89%) assessed all items relating QoL as "excellent," "very good," or "good." The treatment satisfaction index on a visual analog scale scored a median of 8.1 out of 10; when participants were asked about the interference of injections on their daily activities, 87% answered "never" or "only sometimes."

CONCLUSION

Effectiveness and patients' perception about ENF remain good when ENF was used in patients without very advanced disease. QoL was not impaired after ENF use.

Outcomes of multidrug-resistant patients switched from enfuvirtide to raltegravir within a virologically suppressive regimen

Enfuvirtide has been a cornerstone of salvage therapy for multidrug-resistant HIV. Raltegravir provides another novel class option, with the advantages of easier administration and improved tolerability. Thirty-five adults electively replaced enfuvirtide with raltegravir while the rest of their regimen was unchanged. All maintained virologic suppression after a median of 7 months except one who experienced a transiently detectable viral load after 5 months. The new regimen was well tolerated with no apparent new drug-related adverse clinical or laboratory events.

An open-label safety study of enfuvirtide injection with a needle-free injection device or needle/syringe: the Biojector 2000 Open-label Safety Study (BOSS)

Enfuvirtide (ENF) administration by needle/syringe is commonly associated with injection site reactions (ISRs). This study assessed ISRs and participant preference between a needle-free injection device (NFID) and a 27-gauge 1/2-inch needle/syringe (NS). A total of 349 participants with human immunodeficiency virus infection, who had difficulty tolerating long-term administration of ENF by NS, underwent randomization (2:1) to ENF administered twice daily by NFID for 8 weeks, or by NS for 4 weeks followed by NFID for 4 weeks. The objectives of the study were to compare ISRs associated with ENF injection using NFID or NS based on a composite endpoint, ISR incidence/severity, overall ISR scores, and discontinuations. In the NFID group, ISRs improved as the percentage of participants meeting the composite endpoint decreased from baseline (40.1%) to week 4 (25.4%) and remained stable at week 8 (21.2%). In the NS --> NFID group, the percentage meeting the composite endpoint worsened from baseline (36.5%) to week 4 (45.1%), but improved at week 8 (26.1%) after switching. Between-participant comparison showed a statistically significant greater improvement from baseline to week 4 in overall ISR score in the NFID group compared to the NS group. Within-participant comparison of the NS --> NFID group showed a significantly greater decrease in overall ISR score from baseline to week 8. In responses to a questionnaire, 87.2% of the participants surveyed preferred the NFID delivery system over NS. NFID is an alternative injection method that may reduce the incidence and severity of treatment-limiting ISRs associated with ENF administration.

Canadian Consensus Recommendations for the Optimal Use of Enfuvirtide in HIV/AIDS Patients

BACKGROUND AND OBJECTIVES

An eight-member group consisting of Canadian infectious disease and immunology specialists and a family physician with significant experience in HIV management was convened to update existing recommendations, specifically intended for use by Canadian HIV-treating physicians, on the appropriate use of enfuvirtide in HIV/AIDS patients with resistance to other antiretroviral drugs.

METHODS

Evidence from the literature and expert opinions of the group members formed the basis of the guidelines. Comments on the draft guidelines were obtained from other physicians across Canada with HIV expertise. The final guidelines represent the group's consensus agreement.

RESULTS AND CONCLUSIONS

The recommendations were developed to guide physicians in optimal practices in patient selection for enfuvirtide treatment and subsequent patient management. The issues considered include positive predictors of response to enfuvirtide, stage of disease, optimization of the background regimen, early indicators of enfuvirtide response, and patient education and support.

Does iatrogenic scleroderma due to injection-site reaction to enfuvirtide impair absorption of the drug?

BACKGROUND

Chronic iatrogenic scleroderma is a possible obstacle to the absorption of subcutaneously administered drugs. This study correlated the clinical and histopathological pattern of injection-site reactions (ISRs) to the pharmacokinetics of enfuvirtide in patients with HIV.

METHODS

Fourteen patients treated with an enfuvirtide-based antiretroviral regimen for a median of 45 weeks were enrolled and their ISRs were evaluated. Twelve patients with evidence of ISRs underwent cutaneous biopsies using a 4-mm punch. The maximum plasma enfuvirtide concentration (Cmax) and the area under the enfuvirtide concentration-time curve (AUC) were assessed using blood sampling.

RESULTS

Four different macroscopic patterns of ISR were identified: A--no evidence of cutaneous lesions; B--transient infiltrative lesions that auto-resolved within 24 hours; C--transient nodular lesions that auto-resolved within 7-15 days; and D--stable lesions after more than 30 days. Histological examination showed three morphological patterns: (1) acute urticaria/vasculitis-like pattern, (2) subacute pattern and (3) chronic scleroderma-like pattern. No differences among patients with the various patterns of ISRs were observed, except for a higher Cmax and AUC in patients with pattern 1.

CONCLUSIONS

These results confirm that although iatrogenic scleroderma is not related to impaired enfuvirtide absorption, higher Cmax and AUC values are observed in patients with urticaria/vasculitis-like patterns.

A Randomized Study to Evaluate Injection Site Reactions using Three Different Enfuvirtide Delivery Mechanisms (the OPTIONS Study)

Background

The antiretroviral enfuvirtide (ENF) is injected subcutaneously using a 27-gauge needle. Injection site reactions (ISRs) can affect long-term ENF tolerability. Alternative ENF delivery methods may ameliorate ISRs.

Methods

We conducted a multicentre, open-label, randomized controlled trial in which patients receiving ENF were randomized to continue receiving ENF by a 27-gauge needle, a shorter 31-gauge needle or a gas-powered, needle-free injection device (NFID). The primary study endpoint was the proportion of participants with <grade 2 ISR induration at week 12.

Results

Sixty patients received treatment and were included in the intention-to-treat population. The cohort was predominantly male (95%) with a mean age of 49.1 (SD ±7.7) years who had injected ENF for a mean of 821 (SD ±561) days. Response rates for ISR induration at week 12 were 38%, 25% and 42% for the 27-gauge, 31-gauge and NFID groups, respectively (all pairwise treatment comparison P-values >0.2). There was no significant between-group difference for any ISR endpoint, except for changes in the composite ISR score (that is, no ongoing pain of ≥grade 1 or ISR for ongoing pain ≥grade 1 with induration ISR <grade 3 and for nodules <grade 2), which favoured the 27-gauge needle and NFID groups over the 31-gauge group ( P=0.012 and 0.047, respectively). Plasma HIV RNA load was unaffected. There were seven adverse events related to the delivery system: five attributed to the NFID. At week 12, 85% of participants elected to use the NFID.

Conclusion

Needle-free ENF injection offers a reasonable, reliable alternative to needle-based injecting in this population, at least in the short term.

A large prospective study assessing injection site reactions, quality of life and preference in patients using the Biojector vs standard needles for enfuvirtide administration

OBJECTIVES

To determine the severity of injection site reactions (ISRs), patient quality of life (QoL) and preference when enfuvirtide is administered by the Biojector (Bioject, Medical Technologies, Inc., Tualatin, OR, USA) relative to standard needles.

METHODS

A total of 201 HIV-positive patients on stable enfuvirtide-based therapy (n=184) or initiating such therapy (n=17) were evaluated prospectively after switching from standard needles to the Biojector system. Patients used needles for a minimum of 2 weeks prior to switching to the Biojector. Questionnaires to assess the incidence and severity of ISRs (31-item score) and QoL [Medical Outcomes Study HIV Health Survey (MOS-HIV)] were administered at baseline and following a minimum of 14 days of Biojector use.

RESULTS

The median changes in ISR score and number of ISRs following a median of 1.0 month [interquartile range (IQR) 0.9, 1.3] of Biojector use were -3 (IQR -7, 1) and -1 (IQR -3, 1), respectively. The severity of pain (P<0.0001), induration (P<0.0001), pruritus (P<0.0001), nodules (P<0.0001) and erythema (P<0.0001) all decreased with the Biojector. Administration of enfuvirtide with the Biojector was associated with an improved patient QoL (P<0.0001), and was preferred by 72% of patients.

CONCLUSIONS

Compared with needles, the Biojector was associated with a decreased severity of ISRs and improved QoL in patients taking enfuvirtide.

Darunavir: Pharmacokinetics and Drug Interactions

Darunavir (TMC114) is a new HIV protease inhibitor that has demonstrated substantial antiretroviral activity against wild-type HIV-1 virus and multidrug-resistant strains. Darunavir inhibits and is primarily metabolized by cytochrome P450 3A (CYP3A) isoenzymes and is coadministered with low-dose ritonavir (darunavir/r); ritonavir is an inhibitor of CYP3A isoenzymes and pharmacologically enhances darunavir, resulting in increased plasma concentrations and allowing for a lower daily dose. The t1/2 (terminal elimination half-life) of darunavir is 15 h in the presence of ritonavir. An extensive darunavir/r drug-drug interaction programme has been undertaken, covering a wide range of therapeutic areas. Studies conducted in HIV-negative healthy volunteers and in HIV-infected patients show that the potential for interactions is well characterized and the interactions are manageable. For most drugs investigated, no dose adjustments of darunavir/r or the co-administered drug are required. This article reviews all the pharmacokinetic and drug-drug interaction studies conducted to date for darunavir/r, providing guidance on how to co-administer darunavir/r with many other antiretroviral or non-antiretroviral medications commonly used in HIV-infected individuals.

Safety and efficacy of enfuvirtide for 48 weeks as part of an optimized antiretroviral regimen in pediatric human immunodeficiency virus 1-infected patients

BACKGROUND

Enfuvirtide is the only entry inhibitor approved for the treatment of human immunodeficiency virus (HIV)-1 infection. It is approved for use in adults and dosage recommendations exist for children aged 6 years or older.

METHODS

T20-310 was a multicenter, open-label, nonrandomized, noncomparative study of the safety and efficacy of 2.0 mg/kg (maximum 90 mg) twice-daily subcutaneous enfuvirtide for 48 weeks in 52 treatment-experienced, HIV-1-infected pediatric patients (3-16 years) receiving optimized background therapy.

RESULTS

Enfuvirtide was generally well tolerated, and no new patterns of adverse events compared with adults were observed. Mild-to-moderate injection-site reactions were the most common adverse event. Of those participants on treatment for 48 weeks, the median change from baseline in HIV-1 RNA was -1.17 log10 copies/mL (n = 32), and there was a median CD4 change of +106 (n = 25) cells/mm3 and +4.7 CD4%. Seventeen (32.7%) patients achieved a viral load decrease of > or =1 log10 copies/mL and 11 (21.2%) achieved HIV-1 RNA <400 copies/mL. Virologic and immunologic treatment responses were substantially better for children (<11 years) than adolescents. Steady-state mean enfuvirtide C(trough) levels were stable during 24 weeks with no differences between children and adolescents.

CONCLUSIONS

Enfuvirtide is an effective treatment for HIV-1 infection in children and adolescents receiving optimized background therapy and has a favorable safety profile. Efficacy in adolescents was inferior; probably related to unique adherence challenges. The long-term safety and efficacy of enfuvirtide in pediatric patients is comparable to that observed in adults.

TORO: ninety-six-week virologic and immunologic response and safety evaluation of enfuvirtide with an optimized background of antiretrovirals

The additional 48-week optional treatment extension of the T-20 versus Optimized Regimen Only (TORO) studies evaluated long-term safety and efficacy of enfuvirtide (ENF) through week 96 in patients receiving ENF plus optimized background (OB) and patients switching to ENF plus OB from OB alone. Patient randomization was 2:1 to ENF plus OB (n = 663) and OB (n = 334), of which 89.7% and 89.8% were male, 89.3% and 88.6% were Caucasian, and median age was 41 and 42 years, respectively. HIV risk factors were comparable between the ENF plus OB and OB groups with the major factors being 65.2% versus 66.2% homosexual contact, 17.8% versus 19.8% heterosexual contact, 4.1% versus 4.8% bisexual contact, respectively, and 6.9% injection drug use in both groups. OB patients were allowed to switch to ENF plus OB at virologic failure before week 48 and required to switch at week 48 to continue in the study (n = 230). Efficacy and safety assessments were conducted for each group. At week 96, 55% of ENF plus OB subjects completed the study and 26.5% achieved a viral load of less than 400 copies per milliliter (17.5% achieved less than 50 copies per milliliter). Viral load and CD4 mean change from baseline was -2.1 and -1.1 log(10) HIV-1-RNA copies per milliliter and +166 and +116 CD4 cells/mm(3) for ENF plus OB and switch patients, respectively. No new ENF-related safety issues emerged in weeks 48-96. Injection site reactions led to discontinuation in 7% and 10% of ENF plus OB and switch patients, respectively. In conclusion, these data demonstrate durable efficacy and safety of ENF over 96 weeks and that early use of ENF in combination with other agents for the treatment of antiretroviral-experienced HIV-infected subjects is beneficial.

Recomendaciones españolas sobre el uso adecuado de enfuvirtida

Enfuvirtide is a high-cost, parenterally administered drug commonly used in late phases of HIV infection, when its efficacy may be compromised. To optimize enfuvirtide use, consensus recommendations for this purpose have been formulated by 247 physicians attending patients with HIV infection in Spain. A literature review was performed in which grades of evidence and recommendations were defined according to the origin of the data (randomized clinical trials, non-randomized studies, expert opinion). Twenty-eight local consensus meetings were held between May and September 2005 to discuss the most important aspects related to the use of enfuvirtide, following a pre-established system used in all the meetings. The main conclusions were as follows: a) enfuvirtide use is often excessively delayed and is given to patients with little chance of treatment success; b) enfuvirtide is indicated in patients who require antiretroviral treatment and for whom an optimum treatment with three other fully effective drugs cannot be designed; c) the most important prognostic factor is the availability of at least one other completely active drug; d) there is no infallible method to avoid the development of local reactions, but measures are available to decrease their incidence and severity; and e) patient counseling and training for correct administration of the drug are essential to improve adherence, the repercussions of local reactions and, of course, the efficacy of the treatment.

Current status of antiretroviral therapy

At present, there are 22 FDA-approved antiretroviral agents, which are categorised into four classes of drugs. Several others are in various stages of basic and clinical development. The authors of this paper review the general characteristics of each class of antiretrovirals, as well as individual investigational agents that are in advanced clinical development. A brief synopsis of US and WHO antiretroviral treatment guidelines is also provided.

A cohort study of enfuvirtide immunological and virological efficacy in clinical practice

The aim of the study was to evaluate, under routine circumstances, the immunological and virological efficacy of antiretroviral regimens containing enfuvirtide in multi-class experienced HIV-1 infected patients. This retrospective monocentric study analyzed the clinical, immunological, and virological data of 18 HIV-1 infected patients who started enfuvirtide and completed at least 3 months of therapy. Following 3 months of enfuvirtide therapy, 11 (61%) patients had HIV-1 RNA below 400 copies/ml, among whom 8 (44%) patients below 50 copies/ml. In the ten patients still receiving enfuvirtide after 12 months, the median increase in CD4 cell count was 159 cells/microl (range, -25 to +301) and the mean decrease in HIV-1 RNA was 2.5 +/- 1.4 log(10) copies/ml; in six of these patients, viral load remained below 50 copies/ml. Five patients discontinued enfuvirtide for virological failure but none as a consequence of adverse event. Mutations located within the 36-45 amino acid domain of HR1 region of gp41 and associated to enfuvirtide resistance were found in all seven patients with persistent viral replication. In addition, a new mutation, A50V, emerged in one patient with late viral rebound. Its disappearance after treatment discontinuation suggests that it could play a role in resistance to enfuvirtide. In conclusion, enfuvirtide may be a good therapeutic option as rescue therapy in treatment-experienced patients. However, the mutations conferring resistance to enfuvirtide develop rapidly when viral load is not controlled confirming that enfuvirtide should be prescribed in association with an active background regimen.