Comparison of initial combination antiretroviral therapy with a single protease inhibitor, ritonavir and saquinavir, or efavirenz

Simplicity and Efficacy of a Once-Daily Antiretroviral Regimen with Didanosine, Lamivudine, and Efavirenz in Naïve Patients: The VESD Study

PURPOSE

Our aim was to analyze the efficacy and safety of didanosine-lamivudine-efavirenz in a cohort of HIV patients starting antiretroviral therapy between January and September 2003.

METHOD

We undertook a prospective, open-label, observational, multicenter study.

RESULTS

163 patients were enrolled. Over a 48-week period, plasma HIV RNA levels declined sharply, with a median decrease at the end of the observation time of >4.62 log copies/mL. The proportion of patients achieving a plasma HIV RNA level below 50 copies/mL was 62.9% (intention-to-treat analysis) at the end of the study period. The mean CD4 cell count increased steadily over time by 199 cells/microL. Antiviral efficacy was similar in patients with a baseline HIV RNA level above or below 100,000 copies/mL. Overall, 57 (34.1%) patients interrupted therapy; 9 due to lack of treatment response, 18 due to adverse side-effects, and 30 patients lost to follow-up or who withdrew their consent. Adherence was very high (90%-95%) and quality of life was good or very good in 69%.

CONCLUSION

The once-daily combination of didanosine-lamivudine-efavirenz resulted in sustained viral suppression and was well-accepted by patients under real-life conditions, even immunosuppressed patients and those with a high viral load. Associated adverse events and virological failures were few.

Higher Rates of Viral Suppression with Nonnucleoside Reverse Transcriptase Inhibitors Compared to Single Protease Inhibitors Are Not Explained by Better Adherence

BACKGROUND

Although evidence suggests that antiretroviral (ARV) regimens containing nonnucleoside reverse transcriptase inhibitors (NNRTIs) are superior to single-protease inhibitor (PI)-based regimens at suppressing viral load, it is unclear how much of the improved viral suppression is due to intrinsic drug potency versus higher levels of adherence to simpler regimens. We therefore examined adherence and viral suppression in NNRTI and single-PI regimens in a cohort of largely ARV-experienced participants by using objective measures of adherence.

METHOD

Participants were recruited from the Research on Access to Care in the Homeless (REACH) Cohort and were included in the study if they were on single-PI-based or NNRTI-based highly active antiretroviral therapy (HAART) regimens for at least 3 months prior to study entry. Adherence was measured by unannounced pill counts at the participant's usual place of residence. The primary outcome was suppression of HIV viral RNA to <50 copies/mL.

RESULTS

Among 109 individuals who were followed for a median of 8.7 months, the odds of virologic suppression were approximately 8 times higher (p < .01) for participants on NNRTI-based regimens (n = 53) compared with those using single-PI-based regimens (n = 56) when controlling for adherence, as well as other potential confounders in a multivariable analysis. The only other independent predictors of viral suppression in multivariable modeling were ARV adherence (p < .01), CD4 nadir (p = .02), and continuous months on current regimen prior to the start of adherence monitoring (p < .01). There was no significant difference in adherence by unannounced pill counts in participants receiving NNRTI- versus single-PI-containing regimens.

CONCLUSION

A higher proportion of individuals using NNRTI-based regimens had viral suppression when compared to those taking single-PI-containing regimens, and this association was not confounded by higher levels of adherence. These results suggest that improved viral suppression on NNRTI regimens compared to single-PI regimens is more closely associated with regimen potency than higher levels of adherence.

Comparison of Single and Boosted Protease Inhibitor Versus Nonnucleoside Reverse Transcriptase Inhibitor–Containing cART Regimens in Antiretroviral-Naïve Patients Starting cART After January 1, 2000

BACKGROUND

Few published studies have considered both the short- and long-term virologic or immunologic response to combination antiretroviral therapy (cART) and the impact of different cART strategies.

PURPOSE

To compare time to initial virologic (<500 copies/mL) or immunologic (>200/mm3 cell increase) response in antiretroviral-naïve patients starting either a single protease inhibitor (PI; n = 183), a ritonavir-boosted PI regimen (n = 197), or a nonnucleoside reverse transcriptase inhibitor (NNRTI)-based cART regimen (n = 447) after January 1, 2000, and the odds of lack of virologic or immunologic response at 3 years after starting cART.

METHOD

Cox proportional hazards models and logistic regression.

RESULTS

After adjustment, compared to patients taking an NNRTI-regimen, patients taking a single-PI regimen were significantly less likely to achieve a viral load (VL) <500 copies/mL (relative hazard [RH] 0.74, 95% CI 0.54-0.84, p = .0005); there was no difference between the boosted-PI regimen and the NNRTI regimen (p = .72). There were no differences between regimens in the risk of >200/mm3 CD4 cell increase after starting cART (p > .3). At 3 years after starting cART, patients taking a single-PI-based regimen were more likely to not have virologic suppression (<500 copies/mL; odds ratio [OR] 1.60, 95% CI 1.06-2.40, p = .024), while there were no differences in the odds of having an immunologic response (>200/mm3 increase; p > .15). This model was adjusted for CD4 and VL at starting cART, age, prior AIDS diagnosis, year of starting cART, and region of Europe.

CONCLUSION

Compared to patients starting an NNRTI-based regimen, patients starting a single-PI regimen were less likely to be virologically suppressed at 3 years after starting cART. These results should be interpreted with caution, because of the potential biases associated with observational studies. Ultimately, clinical outcomes, such as new AIDS diagnoses or deaths, will be the measure of efficacy of cART regimens, which requires the follow-up of a very large number of patients over many years.

Use of observational data in evaluating treatments: antiretroviral therapy and HIV

Observational data are increasingly used in various therapeutic areas to evaluate the use, effectiveness and side effects of new treatments. Whilst randomized clinical trials remain the gold standard for evaluating the efficacy of new agents, they have a number of limitations for HIV, including the limited number of combinations that are compared and the costs of long-term follow-up. Observational data from seroconverter and clinical cohorts have been used to compare the short- and longer-term effectiveness of different therapy combinations and to evaluate the longer-term risks associated with antiretroviral therapy. Furthermore, they provide the opportunity to evaluate the relative success of more complex patterns of therapy, such as sequencing of different regimens over time. However, because of the nature of these data, a number of potential biases may arise which can influence interpretation.

Factors associated with remaining on initial randomized efavirenz-containing regimens

OBJECTIVE

Efavirenz (EFV) along with two nucleoside reverse transcriptase inhibitors (NRTIs) is a recommended initial antiretroviral regimen. Understanding characteristics related to EFV success is clinically useful.

DESIGN

Data from 2220 antiretroviral-naive participants randomized to EFV and two to three NRTIs in four ACTG trials as well as a long-term cohort were analysed.

METHODS

Logistic regression, using inverse probability of censoring weighting to address selective-follow-up bias, was used to identify factors associated with EFV success (no treatment interruptions of >30 days, HIV RNA < 200 copies/ml) 1 year post initiation and at years 2-5 if successful at year 1.

RESULTS

Pretreatment characteristics were median age 38 years, 82% male, 40% white, 10% history of IDU (HxIDU), median CD4+ T-lymphocyte 227 cells/μl and 33% HIV RNA more than 100 ,000 copies/ml. In a multivariable model, factors associated with year 1 EFV success were race [white odds ratio (OR) 1.5; P < 0.001; Hispanic OR 1.5; P = 0.003 vs. black], no pretreatment sign/symptom grade 3 or higher (OR 1.7; P = 0.008) and no HxIDU (OR 1.7; P = 0.001). Predictors of EFV success at years 2-5 were no HxIDU (years 2-5; ORs 1.9-2.2); self-reported complete (4 days prior to study visit) adherence during year 1 (years 2-4; ORs 1.6-1.9); fewer missed visits during year 1 (years 2, 4, 5; ORs 0.92-0.98/1% increase); HIV RNA less than 50 copies/ml at year 1 (years 2, 3; ORs 1.9-2.2); and older age (>50 vs. ≤30 years) (years 2-4: ORs 2.3-3.7).

CONCLUSION

Characteristics predictive of EFV success in the short-term and longer term differed except for HxIDU. Behaviours occurring during year 1 were associated with EFV success over 5 years.

Efficacy and safety of rilpivirine in treatment-naive, HIV-1-infected patients with hepatitis B virus/hepatitis C virus coinfection enrolled in the Phase III randomized, double-blind ECHO and THRIVE trials

OBJECTIVES

The efficacy and hepatic safety of the non-nucleoside reverse transcriptase inhibitors rilpivirine (TMC278) and efavirenz were compared in treatment-naive, HIV-infected adults with concurrent hepatitis B virus (HBV) and/or hepatitis C virus (HCV) infection in the pooled week 48 analysis of the Phase III, double-blind, randomized ECHO (NCT00540449) and THRIVE (NCT00543725) trials.

METHODS

Patients received 25 mg of rilpivirine once daily or 600 mg of efavirenz once daily, plus two nucleoside/nucleotide reverse transcriptase inhibitors. At screening, patients had alanine aminotransferase/aspartate aminotransferase levels ≤5× the upper limit of normal. HBV and HCV status was determined at baseline by HBV surface antigen, HCV antibody and HCV RNA testing.

RESULTS

HBV/HCV coinfection status was known for 670 patients in the rilpivirine group and 665 in the efavirenz group. At baseline, 49 rilpivirine and 63 efavirenz patients [112/1335 (8.4%)] were coinfected with either HBV [55/1357 (4.1%)] or HCV [57/1333 (4.3%)]. The safety analysis included all available data, including beyond week 48. Eight patients seroconverted during the study (rilpivirine: five; efavirenz: three). A higher proportion of patients achieved viral load <50 copies/mL (intent to treat, time to loss of virological response) in the subgroup without HBV/HCV coinfection (rilpivirine: 85.0%; efavirenz: 82.6%) than in the coinfected subgroup (rilpivirine: 73.5%; efavirenz: 79.4%) (rilpivirine, P = 0.04 and efavirenz, P = 0.49, Fisher's exact test). The incidence of hepatic adverse events (AEs) was low in both groups in the overall population (rilpivirine: 5.5% versus efavirenz: 6.6%) and was higher in HBV/HCV-coinfected patients than in those not coinfected (26.7% versus 4.1%, respectively).

CONCLUSIONS

Hepatic AEs were more common and response rates lower in HBV/HCV-coinfected patients treated with rilpivirine or efavirenz than in those who were not coinfected.

[Modeling of antiretroviral response from taxonomy of CD4 cells count trajectories in profound immunodeficiency setting]

Modeling of CD4 cells counts response was performed through a Non-Hierarchical-descendant process with profoundly immunocompromised symptomatic patients under nevirapine or efavirenz-based antiretroviral regimen in Abidjan. Similar CD4 cells count trajectories have been modelled in meta-trajectories linked to patients' classes. Global immunological response is similar between "nevirapine group" and "efavirenz group" but the model showed an internal variation of this response in each group. In the both groups, some variables presented a significant variation between classes: average CD4, CD4 Nadir, CD4 peak and average gain of CD4. In "nevirapine group", these following parameters vary significantly between classes: mean weight, mean haemoglobin count and mean increase in haemoglobin count and sex. It's also important to note that, all meta-trajectories began with distinctive categories of baseline CD4 cells counts. Other explanatory factors must be sought because the characteristics we have chosen to describe patients'classes, are not exhaustive.

In silico prediction of efavirenz and rifampicin drug-drug interaction considering weight and CYP2B6 phenotype

AIMS

This study aimed to test whether a pharmacokinetic simulation model could extrapolate nonclinical drug data to predict human efavirenz exposure after single and continuous dosing as well as the effects of concomitant rifampicin and further to evaluate the weight-based dosage recommendations used to counteract the rifampicin-efavirenz interaction.

METHODS

Efavirenz pharmacokinetics were simulated using a physiologically based pharmacokinetic model implemented in the Simcyp™ population-based simulator. Physicochemical and metabolism data obtained from the literature were used as input for prediction of pharmacokinetic parameters. The model was used to simulate the effects of rifampicin on efavirenz pharmacokinetics in 400 virtual patients, taking into account bodyweight and CYP2B6 phenotype.

RESULTS

Apart from the absorption phase, the simulation model predicted efavirenz concentration-time profiles reasonably well, with close agreement with clinical data. The simulated effects of rifampicin co-administration on efavirenz treatment showed only a minor decrease of 16% (95% confidence interval 13-19) in efavirenz area under the concentration-time curve, of the same magnitude as what has been clinically observed (22%). Efavirenz exposure depended on CYP2B6 phenotype and bodyweight. Increasing the efavirenz dose during concomitant rifampicin was predicted to be most successful in patients over 50 kg regardless of CYP2B6 status.

CONCLUSIONS

Our findings, although based on a simulation approach using limited in vitro data, support the current recommendations for using a 50 kg bodyweight cut-off for efavirenz dose increment when co-treating with rifampicin.

[Study of meta-trajectories of CD4 cells count from taxonomy in the antiretroviral response of efavirenz-based regimen with naive symptomatic patients in Abidjan]

INTRODUCTION

Sub-Saharan Africa remains the most affected region in the global AIDS epidemic. Côte d'Ivoire is one of the most affected countries by this epidemic. The collective search for deleterious determinants of the evolution of immunological markers (CD4 cells count) may help to optimize the therapeutic efficiency in this resource-limited country.

PATIENTS AND METHODS

We are interested in studying the antiretroviral response of efavirenz-based regimen (treatment of choice in first line) by the nonhierarchical-descendant model by taxonomy of CD4 cells count trajectories. From 87 CD4 cells count trajectories of symptomatic naive patients, classes of similar profiles grouped by the model have formed typical profiles of evolution as meta-trajectories. The analysis of these meta-trajectories was used to study the determinants of CD4 cells count evolution by classes of patients.

RESULTS

Four classes have been determined for an optimal taxonomy with a partition score of 0.72: P1 (n=27), P2 (n=15), P3 (n=24), P4 (n=21). Our model showed a variation between groups of CD4 cells count trajectories linked to explanatory factors by highlighting the predictive role of certain characteristics on antiretroviral response in Côte d'Ivoire (CD4 cells count baseline [P<0.01], CD4 percentage baseline [P<0.05], adherence [P<0.05]). The multiple correspondence analysis revealed other characteristics that influence the immune response such as the presence of opportunistic infections, bloodless status and weight at the initiation of treatment.

CONCLUSION

The factors influencing the profile of meta-trajectories of CD4 cells count during efavirenz-based antiretroviral regimen should be considered at the initiation of treatment to optimize performance in the therapeutic monitoring of patients in Abidjan. The model of biomedical indicators meta-trajectories provides a therapeutic decision support provided prior to capitalize sufficient expertise for a better interpretation.

Cohort studies: to what extent can they inform treatment guidelines?

PURPOSE OF REVIEW

This review examines situations in which information from cohort studies has proved to be useful for the development of treatment guidelines.

RECENT FINDINGS

Although there are several reasons why randomized controlled trials (RCTs) are felt to provide the most robust evidence for treatment guidelines, they may suffer from insufficient duration of follow-up, inadequate power to consider differences in important adverse events and highly selected patient populations. Furthermore, as most RCTs are performed for licensing purposes, strategic treatment decisions often lack supportive evidence from RCTs. Although data from cohort studies may be used to complement information from RCTs, cohort studies themselves are susceptible to several biases (most notably confounding) which may limit their findings. However, in the HIV field, information from such studies has been influential in guiding decisions relating to when to start highly active antiretroviral therapy, what drugs to use in the initial highly active antiretroviral therapy regimen and when to switch highly active antiretroviral therapy should virological failure occur.

SUMMARY

Given the biases that may be present, caution should be exercised when interpreting findings from cohort studies, particularly if comparisons are made of treatment strategies that involve some element of patient or clinician choice.

Does short-term virologic failure translate to clinical events in antiretroviral-naïve patients initiating antiretroviral therapy in clinical practice?

OBJECTIVE

To determine whether differences in short-term virologic failure among commonly used antiretroviral therapy (ART) regimens translate to differences in clinical events in antiretroviral-naïve patients initiating ART.

DESIGN

Observational cohort study of patients initiating ART between January 2000 and December 2005.

SETTING

The Antiretroviral Therapy Cohort Collaboration (ART-CC) is a collaboration of 15 HIV cohort studies from Canada, Europe, and the United States.

STUDY PARTICIPANTS

A total of 13 546 antiretroviral-naïve HIV-positive patients initiating ART with efavirenz, nevirapine, lopinavir/ritonavir, nelfinavir, or abacavir as third drugs in combination with a zidovudine and lamivudine nucleoside reverse transcriptase inhibitor backbone.

MAIN OUTCOME MEASURES

Short-term (24-week) virologic failure (>500 copies/ml) and clinical events within 2 years of ART initiation (incident AIDS-defining event, death, and a composite measure of these two outcomes).

RESULTS

Compared with efavirenz as initial third drug, short-term virologic failure was more common with all other third drugs evaluated; nevirapine (adjusted odds ratio = 1.87, 95% confidence interval (CI) = 1.58-2.22), lopinavir/ritonavir (1.32, 95% CI = 1.12-1.57), nelfinavir (3.20, 95% CI = 2.74-3.74), and abacavir (2.13, 95% CI = 1.82-2.50). However, the rate of clinical events within 2 years of ART initiation appeared higher only with nevirapine (adjusted hazard ratio for composite outcome measure 1.27, 95% CI = 1.04-1.56) and abacavir (1.22, 95% CI = 1.00-1.48).

CONCLUSION

Among antiretroviral-naïve patients initiating therapy, between-ART regimen, differences in short-term virologic failure do not necessarily translate to differences in clinical outcomes. Our results should be interpreted with caution because of the possibility of residual confounding by indication.

Clinical impact of patient population differences and genomic variation in efavirenz therapy

Guidelines for use of antiretroviral agents presently recommend first-line treatments with nonnucleoside reverse transcriptase inhibitor-based regimens. Efavirenz is the standard-of-care comparator for nonnucleoside reverse transcriptase inhibitor-based antiretroviral therapy. As with many antiretroviral medications, efavirenz is subject to interindividual variation in metabolism, effectiveness, and tolerability. Demographic factors such as age, sex, and ethnicity have been demonstrated to influence this variability, but other underlying factors such as genetics, disease state, and concomitant drug use can also play a role. The clinical impactions of these factors are only beginning to be understood. Although significant advances have led to a greater understanding of interactions between genetic and host factors that influence the efficacy and toxicity of efavirenz, providers should not withhold treatment of HIV infection with an efavirenz-based regimen on the basis of racial or ethic categorizations.

Binding Modes of Two Novel Non-Nucleoside Reverse Transcriptase Inhibitors, YM-215389 and YM-228855, to HIV Type-1 Reverse Transcriptase

Background:

YM-215389 and YM-228855 are thiazolidenebenzenesulfonamide (TBS) derivatives and novel non-nucleoside reverse transcriptase inhibitors (NNRTIs) that inhibit not only wild-type, but also the K103N- and Y181C-substituted reverse transcriptase (RT) of HIV type-1 (HIV-1).

Methods:

To characterize the binding modes of the TBS derivatives in detail, the anti-HIV-1 activities of YM-215389 and YM-228855 against various NNRTI-resistant clones were examined. Docking studies with HIV-1 RT were also performed.

Results:

YM-215389, which effectively inhibits various NNRTI-resistant clones, interacted with L100, K103, V106 and Y318 through the benzene ring and with E138, V179, Y181, Y188 and W229 through the thiazole ring. A single amino acid substitution confers only moderate resistance to YM-215389; indeed, four amino acid substitutions (V106L, V108I, E138K and L214F) were necessary for high- level resistance. Although the activity of YM-228855, a derivative of YM-215389 that has two bulky and rigid cyano-moieties on the benzene ring, was 10x more potent against HIV-1 than YM-215389, its anti-HIV-1 activity was readily reduced with single substitutions as with Y181I and K103N.

Conclusions:

These results provide structural information for optimizing the TBS derivatives in an attempt to construct ideal NNRTIs that maintain anti-HIV-1 activity to various HIV-1 variants.

Comparison of the effectiveness of initial combined antiretroviral therapy with nelfinavir or efavirenz at a university-based outpatient service in Brazil

Since there are some concerns about the effectiveness of highly active antiretroviral therapy in developing countries, we compared the initial combination antiretroviral therapy with zidovudine and lamivudine plus either nelfinavir or efavirenz at a university-based outpatient service in Brazil. This was a retrospective comparative cohort study carried out in a tertiary level hospital. A total of 194 patients receiving either nelfinavir or efavirenz were identified through our electronic database search, but only 126 patients met the inclusion criteria. Patients were included if they were older than 18 years old, naive for antiretroviral therapy, and had at least 1 follow-up visit after starting the antiretroviral regimen. Fifty-one of the included patients were receiving a nelfinavir-based regimen and 75 an efavirenz-based regimen as outpatients. Antiretroviral therapy was prescribed to all patients according to current guidelines. By intention-to-treat (missing/switch = failure), after a 12-month period, 65% of the patients in the efavirenz group reached a viral load <400 copies/mL compared to 41% of the patients in the nelfinavir group (P = 0.01). The mean CD4 cell count increase after a 12-month period was also greater in the efavirenz group (195 x 10(6) cells/L) than in the nelfinavir group (119 x 10(6) cells/L; P = 0.002). The efavirenz-based regimen was superior compared to the nelfinavir-based regimen. The low response rate in the nelfinavir group might be partially explained by the difficulty of using a regimen requiring a higher patient compliance (12 vs 3 pills a day) in a developing country.

Initiating highly active antiretroviral therapy with newer protease inhibitors is associated with better survival compared to first-generation protease inhibitors or nevirapine

The high prevalence of comorbidity among HIV-infected patients in care such as hepatitis C virus (HCV) coinfection and mental illness may contribute to increased toxicity and decreased adherence to highly active antiretroviral therapy (HAART). Newer HAART regimens have less toxicity and better dosing characteristics than first-generation regimens, but it is not known whether they are associated with improved clinical outcomes. The purpose of this study was to examine the effect of patient factors and initial HAART regimen on survival among HIV-infected patients in routine care. We conducted an observational study of all HAART-naïve patients in the University of Washington HIV cohort who initiated HAART between January 1996 and October 2005. Cox survival analyses were used to examine the association between time to death and treatment with first-generation protease inhibitors (PIs; indinavir, ritonavir, saquinavir), newer PIs (amprenavir, atazanavir, lopinavir, nelfinavir), efavirenz, or nevirapine, controlling for baseline characteristics, and calendar period. Of 694 patients, 84 (12%) died. In adjusted analyses, patients treated with a first-generation PI (hazard ratio [HR] 1.9, p = 0.04) or nevirapine (HR 2.0, p = 0.046) had twice the risk of death compared with those receiving a newer PI. Survival for patients treated with efavirenz did not differ from those receiving a newer PI (HR 1.1, p = 0.8). Greater disease severity (HR 1.7, p = 0.03), hepatitis C virus (HCV; HR 1.6, p = 0.05), and depression (HR 2.0, p = 0.007) were independent predictors of increased mortality. This study demonstrates significant improvement in survival among patients initiating HAART with newer PIs compared to first-generation PIs or nevirapine, and highlights the complexity of patient factors affecting the clinical outcomes of treatment.

Optimal Timing and Best Antiretroviral Regimen in Treatment-naive HIV-Infected Individuals with Advanced Disease

The introduction of highly active antiretroviral therapy (HAART) in developed countries has achieved a good control of HIV infection. Despite this, a delayed HIV diagnosis makes it necessary to start antiretroviral treatment in individuals with severe impairment of their immunological function. Very often, this is accompanied by an opportunistic infection that needs to be treated, with a consequent complication of management because of overlapping toxicities and pharmacokinetic interactions with antiretroviral drugs, and a greater pill burden. All this could impair adherence and reconstitution of the immune function with a paradoxical clinical worsening in some patients, especially if the CD4 cell count is below 50 cells/microl. The best antiretroviral regimen and the best timing for starting antiretroviral therapy in treatment-naive patients with advanced infection have not yet been established. Recommendations for the clinical management of advanced HIV disease come from panels of experts in the therapy of opportunistic infections and antiretroviral treatment, and they advise starting combined antiretroviral therapy 2-4 weeks after initiating treatment of the opportunistic infection. Many patients have been successfully treated with a pharmacologically enhanced (boosted) protease inhibitor (mainly lopinavir/ritonavir)-based regimens. The efficacy of non-nucleoside reverse transcriptase inhibitor-based regimens for the treatment of very immunosuppressed patients has been tested in few clinical trials during the HAART era. Some cohort studies and randomized clinical trials support the use of efavirenz-based antiretroviral therapy for the treatment of advanced HIV-1-infected patients; however, recent randomized controlled data suggest, in a moderately advanced HIV population, a better CD4 cell recovery for lopinavir-ritonavir than for efavirenz-treated patients, but a greater virological suppression in the efavirenz arm. Further randomized clinical trials are needed in order to determine whether the efficacy, tolerability and the immunological reconstitution of efavirenz-based therapy can match that achieved with lopinavir/ritonavir or other current boosted protease inhibitor regimens in advanced patients.

Cost to achieve an undetectable viral load using recommended antiretroviral regimens

PURPOSE

The April 2005 Guidelines for the Use of Antiretroviral Agents in HIV-Infected Adults and Adolescents recommended 9 regimens to be combined with 2 nucleoside reverse transcriptase inhibitors (NRTIs). These regimens are effective in lowering viral load but are expensive. This study aimed to determine the cost for each regimen to achieve an undetectable viral load.

METHOD

52 clinical trials were reviewed. The outcome measure was cost per undetectable patient, C/PU, where C = cost of a drug, and PU = percent of patients with undetectable viral loads.

RESULTS

For 30 weeks, cost per undetectable (<400 copies/mL) ranged from 4,416 dollars (efavirenz) to 23,110 dollars (nelfinavir); for 42 weeks, the range was 5,729 dollars (efavirenz) to 24,071 dollars (indinavir/ritonavir); for 60 weeks, it ranged from 9,535 dollars (efavirenz) to 26,829 dollars (fosamprenavir); and for 84 weeks, it ranged from 12,203 dollars (efavirenz) to 22,960 dollars (nelfinavir). For <50 copies/mL, at 30 weeks the range was from 7,140 dollars (efavirenz) to 17,548 dollars (atazanavir); for 42 weeks, it ranged from 9,849 dollars (lopinavir/ritonavir) to 13,181 dollars (nelfinavir); for 60 weeks, it ranged from 8,702 dollars (nevirapine) to 36,034 dollars (atazanavir); and for 84 weeks, it ranged from 15,660 dollars (efavirenz) to 29,177 dollars (indinavir/ritonavir).

CONCLUSION

Efavirenz's low price and high effectiveness make it the least expensive means of achieving an undetectable viral load.

Predictors of antiretroviral treatment failure in an urban HIV clinic

BACKGROUND

Predictors of antiretroviral treatment (ART) failure are not well characterized for heterogeneous clinic populations.

METHODS

A retrospective analysis was conducted of HIV-infected patients followed in an urban HIV clinic with an HIV RNA measurement < or =400 copies/mL on ART between January 1, 2003, and December 31, 2004. The primary endpoint was treatment failure, defined as virologic failure (> or =1 HIV RNA measurement >400 copies/mL), unsanctioned stopping of ART, or loss to follow-up. Prior ART adherence and other baseline patient characteristics, determined at the time of the first suppressed HIV RNA load on or after January 1, 2003, were extracted from the electronic health record (EHR). Predictors of failure were assessed using proportional hazards modeling.

RESULTS

Of 829 patients in the clinic, 614 had at least 1 HIV RNA measurement < or =400 copies/mL during the study period. Of these, 167 (27.2%) experienced treatment failure. Baseline characteristics associated with treatment failure in the multivariate model were: poor adherence (hazard ratio [HR] = 3.44; 95% confidence interval [CI]: 2.34 to 5.05), absolute neutrophil count <1000/mm (HR = 2.90, 95% CI: 1.26 to 6.69), not suppressed on January 1, 2003 (HR = 2.69, 95% CI: 1.78 to 4.07) or <12 months of suppression (HR = 1.64, 95% CI: 1.10 to 2.45), CD4 count <200 cells/mm (HR = 1.90, 95% CI: 1.31 to 2.76), nucleoside-only regimen (HR = 1.75, 95% CI: 1.08 to 2.82), prior virologic failure (HR = 1.70, 95% CI: 1.22 to 2.39) and > or =1 missed visit in the prior year (HR = 1.56, 95% CI: 1.13 to 2.16).

CONCLUSIONS

More than one quarter of patients in a heterogeneous clinic population had treatment failure over a 2-year period. Prior ART adherence and other EHR data readily identify patient characteristics that could trigger specific interventions to improve ART outcomes.

Safety, Efficacy and Pharmacokinetics of Ritonavir 400mg/Saquinavir 400mg Twice Daily plus Rifampicin Combined Therapy in HIV Patients with Tuberculosis

OBJECTIVE

To assess the drug concentrations, efficacy and safety of concomitant use of rifampicin and regimens containing ritonavir/saquinavir (400mg/400mg twice daily) in tuberculosis-HIV treatment-naive patients.

DESIGN AND METHODS

This was an open-label, non-randomised, multiple-dose study. On study day (D)1, tuberculosis treatment (rifampicin 600mg/isoniazid 400mg per day fasting plus pyrazinamide 2 g/day) was introduced in 30 patients. On D31, highly active antiretroviral therapy (HAART) consisting of two nucleoside analogues plus ritonavir/saquinavir 400mg/400mg twice daily was initiated (n = 20). The pharmacokinetics were assayed with a validated reversed-phase HPLC method before the introduction of HAART on D30 (for rifampicin), after 30 days of HAART at D60 (for rifampicin plus ritonavir/saquinavir), and at the end of the study (without rifampicin) on D210 (for ritonavir/saquinavir). Clinical evaluations were performed on a monthly basis. CD4 counts and viral load were collected on D30, D60 and D180. Genotyping test for HIV was collected at baseline and at D180. Primary endpoints were drug concentration and viral load at D180 (<80 copies/mL). Secondary endpoints were presence of grade 3 and serious adverse events, clinical improvement, CD4 count and genotypic resistance to ritonavir/saquinavir.

RESULTS

Ten patients dropped out of the study during tuberculosis therapy alone. Mean (+/- SD) baseline CD4 count (on D30) was 151.89 (+/- 146.77) cells/mm(3) and viral load was 5.34 (+/- 0.4) log. During the antiretroviral therapy, 15 patients dropped out, 14 because of adverse events. One patient (of five) presented a viral load of <80 copies/mL at D180. All but one patient increased CD4 counts from baseline. No genotypic resistance was detected. Clinical improvement was evident in all five patients who tolerated the therapy. Serum concentrations of ritonavir/saquinavir and rifampicin remained within the therapeutic range.

CONCLUSIONS

Therapeutic concentrations of the studied drugs and reduction of viral load were achieved; adverse events are the main limitation of use of a ritonavir/saquinavir regimen in treatment-naive patients, but its clinical benefits were evident.

Immunologic function and virologic suppression among children with perinatally acquired HIV Infection on highly active antiretroviral therapy

BACKGROUND

The goal of highly active antiretroviral therapy (HAART) has been to stabilize and reconstitute immune function and suppress viral replication to the greatest degree possible. Suppression of HIV viral replication has been associated with improved long-term and short-term prognosis. Limited data are available on the level of virologic suppression and immune function of pediatric patients followed in clinical settings in the HAART era.

OBJECTIVE

The objective of this study was to assess the level of virologic suppression and immune function in a cohort of children with perinatally acquired HIV infection followed at dedicated HIV specialty care sites.

RESEARCH DESIGN

This study comprised a cohort study of HIV-infected children and adolescents.

SUBJECTS

Study subjects consisted of 263 HIV-positive children (<or=17 years old), on HAART, with at least one outpatient visit and CD4 test recorded in 2001 seen at 4 U.S. HIV primary pediatrics and specialty care sites (2 eastern, 1 southern, and 1 western).

MEASURES

Measures consisted of all plasma HIV-1 RNA levels <or=400 during calendar year 2001.

RESULTS

Two hundred sixty-three patients received HIV-related treatment during 2001, with a mean age of 8.5 years. Sixty-eight percent were black, 54% were females, and the majority (85%) was insured by Medicaid. A total of 28.6% had a class C AIDS diagnosis. A total of 23.5% and 34% of patients maintained viral suppression at <50 copies per milliliter (cpm), or <400 cpm, respectively, for the calendar year; 32.5% and 38.8%, respectively, fulfilled the criteria if one "blip" to <5000 cpm was allowed. Forty-eight percent maintained all viral loads <5000 cpm, and 74.9% overall had HIV-1 RNAs <or=15,000 cpm. Eighty-seven percent of patients had CD4% >25; only 4.2% had CD4 <15%. Overall, 12.5% of patients had either CD4% <15 or severely decreased absolute CD4 counts (adjusted for age). A total of 4.6% of patients had HIV-1 RNAs >100,000 cpm and severe immunosuppression. Patients who were less likely to achieve virologic suppression to <400 cpm included those with CD4 count <200 cells/mm(3) (odds ratio [OR], 0.06; 95% confidence interval [CI], 0.007-0.46), those with AIDS (OR, 0.5; 95% CI, 0.28-0.94), and those with moderate (OR, 0.42; 95% CI, 0.22-0.79), or severe immunologic suppression (OR, 0.14; 95% CI, 0.046-0.43) based on CD4%.

CONCLUSION

In this multisite, pediatric cohort, the rate of near-complete virologic suppression (<50 or <400 cpm) was low. However, the majority of patients have near-normal CD4 counts and viral loads <15,000 cpm. Follow up will be critical to assess the implications of ongoing low-level viral replication with near-normal CD4 values.

Antiretroviral therapy in advanced HIV-1 infection

Current recommendations state that antiretroviral therapy (ART) should be commenced before the onset of severe HIV-associated immune deficiency and the development of AIDS-defining infections or malignancies. However, many patients only present and are diagnosed with HIV infection when they already have advanced disease. The optimal treatment for patients with advanced HIV disease remains to be defined. Key management questions include whether the virological and immunological responses to ART are comparable to those seen in patients with less advanced disease; whether the efficacy of different antiretroviral (ARV) regimens differs in patients with advanced disease; and whether there is an increased risk of drug toxicity and the immune reconstitution inflammatory syndrome.

Rate of viral rebound according to specific drugs in the regimen in 2120 patients with HIV suppression

BACKGROUND

It is currently unclear whether the tendency for viral rebound in patients with viral load < 50 copies/ml differs according to the specific drug regimen being used.

METHODS

To follow 2120 patients in EuroSIDA who had attained < 50 copies/ml on highly active antiretroviral therapy (HAART), without previously virologically failing HAART.

RESULTS

The rate of viral rebound (two consecutive values > 400 copies/ml) was 4.9/100 person-years [95% confidence interval (CI), 4.0-5.8] for patients who were naive pre-HAART and 8.0/100 person-years (95% CI, 7.0-9.0) for those who were experienced with nucleoside analogue reverse transcriptase inhibitors (NRTI) pre-HAART. The rate of rebound was significantly higher in those taking nelfinavir than in those taking efavirenz, both in patients who were naive pre-HAART and those who were NRTI experienced [adjusted rate ratios, 2.83 (95% CI, 1.51-5.31) and 2.86 (95% CI, 1.65-5.00), respectively]. Among patients who were naive pre-HAART, those on abacavir had no evidence of a raised risk of viral rebound (adjusted rate ratio 1.17; 95% CI, 0.51-2.69), but in those with pre-HAART NRTI experience the rate was markedly raised (adjusted rate ratio, 4.48; 95% CI, 2.51-8.00). A similar picture was seen when comparing those on nevirapine with those on efavirenz, although the elevated rate ratio in pre-HAART experienced patients was of lower magnitude (adjusted rate ratio, 1.93). There was no strong evidence that rebound rates differed significantly for any NRTI pairs compared with zidovudine/lamivudine.

CONCLUSION

Viral rebound rates in patients who have attained < 50 copies/ml appear to differ according to the specific drugs being used.

Management of protease inhibitor-associated hyperlipidemia

Dyslipidemia, characterized by elevated serum levels of triglycerides and reduced levels of total cholesterol, low-density lipoprotein-cholesterol (LDL-C) and high-density lipoprotein-cholesterol, has been recognized in patients with human immunodeficiency virus (HIV) infection. It is thought that elevated levels of circulating cytokines, such as tumor necrosis factor-alpha and interferon-alpha, may alter lipid metabolism in patients with HIV infection. Protease inhibitors, such as saquinavir, indinavir and ritonavir, have been found to decrease mortality and improve quality of life in patients with HIV infection. However, these drugs have been associated with a syndrome of fat redistribution, insulin resistance, and hyperlipidemia. Elevations in serum total cholesterol and triglyceride levels, along with dyslipidemia that typically occurs in patients with HIV infection, may predispose patients to complications such as premature atherosclerosis and pancreatitis. It has been estimated that hypercholesterolemia and hypertriglyceridemia occur in greater than 50% of protease inhibitor recipients after 2 years of therapy, and that the risk of developing hyperlipidemia increases with the duration of treatment with protease inhibitors. In general, treatment of hyperlipidemia should follow National Cholesterol Education Program guidelines; efforts should be made to modify/control coronary heart disease risk factors (i.e. smoking; hypertension; diabetes mellitus) and maximize lifestyle modifications, primarily dietary intervention and exercise, in these patients. Where indicated, treatment usually consists of either pravastatin or atorvastatin for patients with elevated serum levels of LDL-C and/or total cholesterol. Atorvastatin is more potent in lowering serum total cholesterol and triglycerides compared with other hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, but it is also associated with more drug interactions compared with pravastatin. Simvastatin and lovastatin are significantly metabolized by cytochrome P450 enzymes (CYP3A4) and are therefore not recommended for coadministration with protease inhibitors. A fibric acid derivative (gemfibrozil or fenofibrate) should be used in patients with primary hypertriglyceridemia. However, it must be kept in mind that protease inhibitors, such as nelfinavir and ritonavir, induce enzymes involved in the metabolism of the fibric acid derivatives and may, therefore, reduce the lipid-lowering activity of coadministered gemfibrozil or fenofibrate. In certain patients HMG-CoA reductase inhibitors may be used in combination with fibric acid derivatives but patients should be carefully monitored for liver and skeletal muscle toxicity. Select patients may experience improvements in serum lipid levels when their offending protease inhibitor(s) is/are exchanged for efavirenz, nevirapine, or abacavir; however each patient's virologic and immunologic status must be taken closely into consideration.

Clinical, Virologic, and Immunologic Response to Efavirenz-or Protease Inhibitor???Based Highly Active Antiretroviral Therapy in a Cohort of Antiretroviral-Naive Patients With Advanced HIV Infection (EfaVIP 2 Study)

OBJECTIVE

To compare the clinical, immunologic, and virologic outcomes of efavirenz (EFV)-based versus protease inhibitor (PI)-based highly active antiretroviral therapy (HAART) in severely immunosuppressed HIV-1-infected patients.

DESIGN

Retrospective observational cohort study.

METHODS

Responses were analyzed according to the intent-to-treat principle among antiretroviral-naive patients with < 100 CD4 cells/muL who started EFV (n = 92) or a PI (n = 218) plus 2 nucleoside reverse transcriptase inhibitors. The primary end point was time to treatment failure. Secondary end points were percentage of patients with a viral load < 400 copies/mL, time to virologic failure, time to CD4 lymphocyte count > 200 cells/microL, and incidence of opportunistic events or death.

RESULTS

The median baseline CD4 cell count and viral load were 34 cells/microL and 5.54 log10 copies/mL (EFV group) and 38 cells/microL and 5.40 log10 copies/mL (PI group). Time to treatment failure was shorter with a PI-based regimen than with an EFV-based regimen (adjusted relative hazard [RH] = 2.19, 95% confidence interval [CI]: 1.23-3.89). After 12 months of therapy, a significantly higher proportion of patients receiving EFV reached a viral load < 400 copies/mL (69.4 vs. 45.1%; P < 0.05). The probability of virologic failure was higher with a PI than with EFV (adjusted HR = 2.52, 95% CI: 1.14-5.61; P = 0.024). There was no difference in time to CD4 cell count > 200 cells/microL or in incidence of opportunistic events or death.

CONCLUSION

: In severely immunosuppressed, antiretroviral-naive, HIV-1-infected patients, treatment with an EFV-based regimen compared with a nonboosted PI-based regimen resulted in a superior virologic response with no difference in immunologic or clinical effectiveness.

Do sex and race/ethnicity influence CD4 cell response in patients who achieve virologic suppression during antiretroviral therapy?

To determine whether CD4 cell count response to virus suppression during highly active antiretroviral therapy differs according to sex or race/ethnicity, we analyzed data in our observational cohort study for patients receiving their first antiretroviral regimen who experienced virus suppression by 6 months of therapy. In both univariate and multivariate analyses, women had greater CD4 cell count increases, compared with men, as did patients receiving a regimen that did not include a protease inhibitor. Race/ethnicity was not a factor.

Ritonavir plus saquinavir versus single protease inhibitor therapy in protease inhibitor-naive HIV-infected patients: the Swiss HIV Cohort Study

OBJECTIVES

To compare the response to ritonavir (RTV) plus saquinavir (SQV) with single protease inhibitor (PI) therapies among PI-naive HIV-1 infected individuals.

METHODS

Response to treatment was analysed according to the intent-to-treat principle in a prospective observational cohort study of 177 patients who between May 1995 and March 2000 started a double PI therapy with RTV and SQV (nonboosting dosages) plus at least one nucleoside reverse transcriptase inhibitor (NRTI) and 2,214 patients with a single PI therapy plus two NRTIs. We used survival analysis and Cox's proportional hazard regression methods. The primary endpoint was the time to a plasma viral load of < 400 copies/mL. Secondary endpoints were taken as a gain in the CD4 count of >100 cells/microL, and change of initial PI for any reason.

RESULTS

Baseline characteristics in both treatment groups were balanced. Median follow-up in both groups was 10.4 months. Time to an HIV-1 viral load of < 400 copies/mL and an increase in the CD4 count of >100 x 10(6) cells/L was shorter for RTV plus SQV compared with single PI regimens (log rank test for each endpoint P < 0.05). The adjusted hazard ratios of RTV plus SQV compared with single PI regimens were 1.21 (95% confidence interval 0.99-1.47) for achieving an HIV-1 viral load of < 400 copies/mL, 1.12 (0.88-1.42) for an increase in the CD4 count of > 100 cells/microL, and 0.90 (0.73-1.11) for change of first PI regimen.

CONCLUSIONS

Treatment with RTV plus SQV compared with single PI regimens appeared to give similar results for virological or immunological response.

Safety and tolerance of efavirenz in different antiretroviral regimens: results from a national multicenter prospective study in 1,033 HIV-infected patients

PURPOSE

To evaluate the incidence and severity of adverse events (AEs) and treatment interruption (TI) with efavirenz in a population with a high rate of intravenous drug use (IVDU).

METHOD

This was a national, multicenter, and observational study of HIV-infected adult patients who were starting an efavirenz-containing regimen. Evaluations of AEs were made in routine clinical practice at baseline and at least 3 months later. A total of 1,033 patients were included from 60 participating hospitals; 20% were antiretroviral naive. The risk factor for HIV infection was IVDU in 62.3%, and 6.6% of participants were on methadone.

RESULTS

AEs affected 29.3% of participants, and treatment was interrupted in 8.23%. The most frequent AEs were CNS disturbances that affected 24.1% participants; these AEs were considered related to efavirenz in 18.5% patients. AEs were not severe, and treatment had to be interrupted in 6% of patients. Other AEs were cutaneous rash (incidence of 5.9%; 2.4% of TI), gastrointestinal disturbances (1.45%; no TI), and elevation of liver function test (0.68%; no TI). Patients taking methadone had more AEs (39.7%), mainly CNS disturbances, and TI (19.1%). Cutaneous rash was more frequent among women. Psychoactive drug consumption, previous history of psychiatric disorders, antiretroviral experience, or previous nevirapine intolerance were not associated with higher incidence of AEs.

CONCLUSION

Safety and tolerance of efavirenz is good in most patients, even in a population with a high rate of IVDU. The most common AEs are CNS disturbances; they are not severe and rarely lead to TI.

[Recommendations of the Spanish AIDS Study Group (GESIDA) and the National Aids Plan (PNS) for antiretroviral treatment in adult patients with human immunodeficiency virus infection in 2002]

OBJECTIVE

To provide an update of recommendation on antiretroviral treatment (ART) in HIV-infected adults.Methods. These recommendations have been agreed by consensus by a committee of the spanish AIDS Study Group (GESIDA) and the National AIDS Plan. To do so, advances in the physiopathology of AIDS and the results on efficacy and safety in clinical trials, cohort and pharmacokinetics studies published in biomedical journals or presented at congresses in the last few years have been reviewed. Three levels of evidence have been defined according to the data source: randomized studies (level A), case-control or cohort studies (level B) and expert opinion (level C). Whether to recommend, consider, or not to recommend ART has been established for each situation.

RESULTS

Currently, ART with combinations of at least three drugs constitutes the treatment of choice in chronic HIV infection. In patients with symptomatic HIV infection, initiation of ART is recommended. In asymptomatic patients initiation of ART should be based on the CD41/mL lymphocyte count and on the plasma viral load (PVL): a) in patients with CD41 lymphocytes < 200 cells/mL, initiation of ART is recommended; b) in patients with CD41 lymphocytes between 200 and 300 cells/mL, initiation of ART should, in most cases, be recommended; however, it could be delayed when the CD41 lymphocyte count remains close to 350 cells/mL and the PVL is low, and c) in patients with CD41 lymphocytes > 350 cells/mL, initiation of ART can be delayed. The aim of ART is to achieve an undetectable PVL. Adherence to ART plays a role in the durability of the antiviral response. Because of the development of cross-resistance, the therapeutic options in treatment failure are limited. In these cases, genotypic analysis is useful. Toxicity limits ART. The criteria for ART in acute infection, pregnancy and postexposure prophylaxis and in the management of coinfection with HIV and hepatitis C and B virus are controversial.

CONCLUSIONS

The current approach to initiating ART is more conservative than in previous recommendations. In asymptomatic patients, the CD41 lymphocyte count is the most important reference factor for initiating ART. Because of the considerable number of drugs available, more sensitive monitoring methods (PVL) and the possibility of determining resistance, therapeutic strategies have become much more individualized.

Hepatotoxicity associated with nevirapine or efavirenz-containing antiretroviral therapy: role of hepatitis C and B infections

Hepatologists are frequently asked to evaluate human immunodeficiency virus (HIV)-infected patients with abnormal liver enzymes and to assess the causal role of medications, such as antiretroviral drugs. Recently, the use of HIV-1 specific non-nucleoside reverse transcriptase inhibitors (NNRTIs), including nevirapine (NVP) and efavirenz (EFV), has been associated with severe hepatic injury. We prospectively studied the incidence of severe hepatotoxicity (grade 3 or 4 change in alanine or aspartate transaminase levels) among 568 patients receiving NNRTI-containing antiretroviral therapy, including 312 and 256 patients prescribed EFV and NVP, respectively. Hepatitis C virus (HCV) and hepatitis B virus (HBV) were detected in 43% and 7.7% of patients, respectively. Severe hepatotoxicity was observed in 15.6% of patients prescribed NVP and 8.0% of those prescribed EFV, but only 32% of NVP and 50% of EFV-associated episodes were detected during the first 12-weeks of therapy. The risk was significantly greater among persons with chronic viral hepatitis (69% of cases) and those prescribed concurrent protease inhibitors (PIs) (82% of cases). Nonetheless, 84% of patients with chronic HCV or HBV did not experience severe hepatotoxicity. Severe hepatotoxicity occurs throughout the course of NNRTI therapy and is more common among patients prescribed nevirapine, those coinfected with HCV or HBV, and those coadministered protease inhibitors.