British HIV Association (BHIVA) guidelines for the treatment of HIV-infected adults with antiretroviral therapy (2005)

Predicting CD4 lymphocyte count <200 cells/mm(3) in an HIV type 1-infected African population

Clinical criteria are recommended to select HIV-infected patients for initiation of antiretroviral therapy when CD4 lymphocyte testing is unavailable. We evaluated the performance characteristics of WHO staging criteria, anthropometrics, and simple laboratory measurements for predicting CD4 lymphocyte count (CD4 count) <200 cells/mm(3) among HIV-infected patients in Tanzania. A total of 202 adults, diagnosed with HIV infection through community-based testing, underwent a detailed evaluation including staging history and examination, anthropometry, complete blood count, erythrocyte sedimentation rate (ESR), and CD4 count. Univariable analysis and recursive partitioning were used to identify characteristics associated with CD4 count 200 cells/mm(3). Of 202 participants 109 (54%) had a CD4 count <200 cells/mm(3). Characteristics most strongly associated with CD4 count <200 cells/mm(3) (p-value <0.0001) were the presence of mucocutaneous manifestations (72% vs. 28%), lower total lymphocyte count (TLC) (median 1,450 vs. 2,200 cells/mm(3)), lower total white blood cell count (median 4,200 vs. 5,500 cells/mm(3)), and higher ESR (median 95 vs. 53 mm/h). In a partition tree model, TLC <1,200 cells/mm(3), ESR >or=120 mm/h, or the presence of mucocutaneous manifestations yielded a sensitivity of 0.85 and specificity of 0.63 for predicting CD4 count <200 cells/mm(3). The sensitivity of the 2006 WHO Staging system improved from 0.75 to 0.93 with inclusion of these parameters, at the expense of specificity (0.36 to 0.26). The presence of mucocutaneous manifestations, TLC <1,200 cells/mm(3), or ESR >or=120 mm/h was a strong predictor of CD4 count <200 cells/mm(3) and enhanced the sensitivity of the 2006 WHO staging criteria for identifying patients likely to benefit from antiretrovirals.

Comparative evaluation of the automated Roche TaqMan real-time quantitative human immunodeficiency virus type 1 RNA PCR assay and the Roche AMPLICOR Version 1.5 conventional PCR assay

The need to evaluate antiviral treatment response and the emergence of resistance have made the human immunodeficiency virus (HIV) viral load assay a major feature of the diagnostic monitoring of HIV-infected individuals. The objective of this study was to evaluate the utility of the recently In Vitro Diagnostic Medical Devices Directive-approved Roche COBAS AmpliPrep/TaqMan96 real-time PCR assay by comparison with the existing Roche COBAS AmpliPrep/AMPLICOR MONITOR conventional PCR assay. EDTA-treated plasma samples from 191 HIV-1-infected individuals were tested for HIV-1 RNA by the AMPLICOR assay and the TaqMan assay. This was a prospective study using 191 pairs of samples from the same bleed per patient. The correlation coefficient of the assays was 98.08%. The mean difference between the assays was 0.05 log(10) copy/ml plasma, with a standard deviation (SD) of 0.27 log(10) copy/ml plasma. Thirteen samples gave results with variances greater than 0.5 log(10) copy/ml plasma, which is our clinical cutoff. Two samples were more than 3 SD different (0.81 log(10) copy/ml plasma). The TaqMan assay appeared to be slightly more sensitive at the lower end of the dynamic range. The assays correlated significantly (P > 0.95) with each other, and the regression analysis was also highly significant (R(2) > 0.95).

CD4 cell counts of 800 cells/mm3 or greater after 7 years of highly active antiretroviral therapy are feasible in most patients starting with 350 cells/mm3 or greater

OBJECTIVE

CD4 cell count changes in therapy-naive patients were investigated during 7 years of highly active antiretroviral therapy (HAART) in an observational cohort.

METHODS

Three endpoints were studied: (1) time to >or=800 CD4 cells/mm in 5299 therapy-naive patients starting HAART, (2) CD4 cell count changes during 7 years of uninterrupted HAART in a subset of 544 patients, and (3) reaching a plateau in CD4 cell restoration after 5 years of HAART in 366 virologically suppressed patients.

RESULTS

Among patients with <50, 50 to 200, 200 to 350, 350 to 500, and >or=500 CD4 cells/mm at baseline, respectively, 20%, 26%, 46%, 73%, and 87% reached >or=800 CD4 cells/mm within 7 years of starting HAART. Periods with HIV RNA levels >500 copies/mL and age >or=50 years were associated with lesser increases in CD4 cell counts between 6 months and 7 years. Having reached >or=800 CD4 cells/mm at 5 years, age >or=50 years, and >or=1 HIV RNA measurement >1000 copies/mL between 5 and 7 years were associated with a plateau in CD4 cell restoration.

CONCLUSIONS

Restoration to CD4 cell counts >or=800 cells/mm is feasible within 7 years of HAART in most HIV-infected patients starting with >or=350 cells/mm and achieving sufficient suppression of viral replication. Particularly in patients >or=50 years of age, it may be beneficial to start earlier than current guidelines recommend.

Prognostic Significance of Immune Subset Measurement in Individuals With AIDS-Associated Kaposi's Sarcoma

Purpose

A prognostic index for AIDS-associated Kaposi's sarcoma (KS) diagnosed in the era of highly active antiretroviral therapy (HAART) was based on routine clinical and laboratory characteristics. Because immune subset measurement is often performed in HIV-positive individuals, we examined whether these were predictive of mortality independently of the prognostic index, or could predict time to progression of KS.

Patients and Methods

We performed univariate and multivariate Cox regression analyses on a data set of 326 individuals with AIDS-associated KS to identify immune subset covariates predictive of overall survival and time to progression. Adaptive (CD8 T cell and CD19 B cell) and innate (CD16/56 natural-killer cell) immune parameters were studied by flow cytometry.

Results

In univariate analyses, all three immune subsets had significant effects on overall survival (P < .025). In multivariate analyses including the prognostic index, only CD8 counts remained significant (P = .026), although its effect on the overall prognostic index is small. An increase of 100 cells/mm3 in the CD8 count confers a 5% improvement in overall survival. Individuals with a higher CD8 count did not have an increased time to progression. Patients who were already on HAART at the time of KS diagnosis did not have a shorter time to progression than those who were antiretroviral naïve at KS diagnosis.

Conclusion

The CD8 count appears to provide independent prognostic information in individuals with AIDS-associated KS. Measurement of the CD8 count is clinically useful in patients with KS.

Predictors of disease progression in HIV infection: a review

During the extended clinically latent period associated with Human Immunodeficiency Virus (HIV) infection the virus itself is far from latent. This phase of infection generally comes to an end with the development of symptomatic illness. Understanding the factors affecting disease progression can aid treatment commencement and therapeutic monitoring decisions. An example of this is the clear utility of CD4+ T-cell count and HIV-RNA for disease stage and progression assessment. Elements of the immune response such as the diversity of HIV-specific cytotoxic lymphocyte responses and cell-surface CD38 expression correlate significantly with the control of viral replication. However, the relationship between soluble markers of immune activation and disease progression remains inconclusive. In patients on treatment, sustained virological rebound to >10,000 copies/mL is associated with poor clinical outcome. However, the same is not true of transient elevations of HIV RNA (blips). Another virological factor, drug resistance, is becoming a growing problem around the globe and monitoring must play a part in the surveillance and control of the epidemic worldwide. The links between chemokine receptor tropism and rate of disease progression remain uncertain and the clinical utility of monitoring viral strain is yet to be determined. The large number of confounding factors has made investigation of the roles of race and viral subtype difficult, and further research is needed to elucidate their significance. Host factors such as age, HLA and CYP polymorphisms and psychosocial factors remain important, though often unalterable, predictors of disease progression. Although gender and mode of transmission have a lesser role in disease progression, they may impact other markers such as viral load. Finally, readily measurable markers of disease such as total lymphocyte count, haemoglobin, body mass index and delayed type hypersensitivity may come into favour as ART becomes increasingly available in resource-limited parts of the world. The influence of these, and other factors, on the clinical progression of HIV infection are reviewed in detail, both preceding and following treatment initiation.

[Recommendations from the GESIDA/Spanish AIDS Plan regarding antiretroviral treatment in adults with human immunodeficiency virus infection (update January 2007)]

OBJECTIVE

This consensus document is an update of antiretroviral therapy (ART) recommendations for adult patients infected with the human immunodeficiency virus (HIV-1).

METHODS

To formulate these recommendations, a panel composed of members of the Grupo de Estudio de Sida (GESIDA; AIDS Study Group) and the Plan Nacional sobre el Sida (PNS; Spanish AIDS Plan) reviewed the advances in the current understanding of the pathophysiology of HIV, the safety and efficacy findings from clinical trials, and the results from cohort and pharmacokinetic studies published in biomedical journals or presented at scientific meetings over the last years. Three levels of evidence were defined according to the source of the data: randomized studies (level A), cohort or case-control studies (level B), and expert opinion (level C). The decision to recommend, consider or not recommend ART was established in each situation.

RESULTS

Currently, the treatment of choice for chronic HIV infection is the combination of three drugs of two different classes, including 2 nucleosides or nucleotide analogs (NRTI) plus 1 non-nucleoside (NNRTI) or 1 boosted protease inhibitor (PI/r). Initiation of ART is recommended in patients with symptomatic HIV infection. In asymptomatic patients, initiation of ART is recommended on the basis of CD4+ lymphocyte counts and plasma viral load, as follows: 1) therapy should be started in patients with CD4+ counts of < 200 cells/microl; 2) therapy should be started in most patients with CD4+ counts of 200-350 cells/microl, although it can be delayed when CD41 count persists at around 350 cells/microL and viral load is low, and 3) initiation of therapy can be delayed in patients with CD4+ counts of > 350 cells/microL. The initial objective of ART is to achieve an undetectable viral load. Adherence to therapy plays an essential role in maintaining the antiviral response. Therapeutic options are limited with the development of cross resistance and ART failure. Genotype studies are useful in these cases. More information regarding the studies analyzed and the panel recommendations for adherence, toxicity, treatment during pregnancy, patients with hepatitis B or C virus co-infection, and post-exposure prophylaxis can be accessed at www.gesida.seimc.org.

CONCLUSIONS

CD4+ lymphocyte count is the most important reference factor for initiating ART in asymptomatic patients. The large number of available drugs, the increased sensitivity of tests to monitor viral load, and the ability to determine viral resistance is leading to a more individualized approach to therapy.

Intensification of a triple-nucleoside regimen with tenofovir or efavirenz in HIV-1-infected patients with virological suppression

OBJECTIVE

To compare a quadruple-nucleoside with an efavirenz-containing regimen for treatment of HIV-1 infection.

DESIGN

A randomized, open-label study of the AIDS Clinical Trials Group (ACTG).

METHODS

Subjects receiving zidovudine/lamivudine/abacavir on ACTG 5095 with HIV-1 RNA less than 200 copies/ml were randomly assigned to intensify either with tenofovir or efavirenz. Subjects were followed for time to treatment failure, defined as either virological failure or treatment discontinuation. Analyses were intent-to-treat.

RESULTS

One hundred and seventy subjects (21% women; 56% non-white) entered the study. At baseline, 95 and 73% had HIV-1-RNA levels less than 200 and 50 copies/ml, respectively; the median CD4 cell count was 453 cells/microl. Over a median 79 weeks follow-up, 165 (97%) completed the study, three (2%) discontinued, and two (1%) died. Treatment failure occurred in 31 subjects: 18 (21%) (quadruple nucleosides) and 13 (15%) (efavirenz-containing regimen); however the failure-time curves crossed and demonstrated a non-constant treatment effect over time, characterized by more early treatment failures on the efavirenz-containing regimen and more late treatment failures on the four-nucleoside regimen. HIV-1 RNA remained suppressed in more than 88% of subjects to less than 200 copies/ml and in more than 78% to less than 50 copies/ml at weeks 24, 48, and 72, without differences by treatment arm. There were no significant differences between the regimens in CD4 cell increases, time to new grade 3/4 adverse events, or adherence.

CONCLUSION

The safety, tolerability, and efficacy of the four-nucleoside regimen were not significantly different from the efavirenz-containing regimen. These pilot data support further investigation of the quadruple-nucleoside regimen.

Effects of Active Treatment Discontinuation in Patients With a CD4+ T-Cell Nadir Greater Than 350 Cells/mm3

OBJECTIVE

To evaluate the safety and efficacy of discontinuing highly active antiretroviral therapy (HAART) in HIV-1-positive patients who initiated HAART at a CD4+ T-cell count >350 cells/mm.

METHODS

Eligible patients were identified from the Dutch AIDS Therapy Evaluation, The Netherlands (ATHENA) national observational cohort. Interruption or continuation of HAART was offered to all.

RESULTS

Of 71 patients enrolled, 46 (64%) interrupted HAART (STOP group) and 25 (36%) continued HAART (control group). The median CD4+ T-cell nadirs at the start of HAART were 469 (interquartile range [IQR]: 430-720) cells/mm3 and 510 (IQR: 440-637) cells/mm3, respectively. At week 48, the median plasma HIV RNA level in the STOP group had stabilized at approximately pre-HAART values (4.55 log10, IQR: 4.2-4.9 copies/mL), but the CD4+ T-cell count still exceeded the pre-HAART count (563 cells/mm3, IQR: 450-710 cells/mm3). Only 5 patients (11%) had reinitiated HAART after 48 weeks, all for personal reasons. No Centers for Disease Control and Prevention category events or death occurred after interruption. In 6 (13%) of 46 patients, mild symptoms of acute retroviral rebound syndrome (ARVS) were identified. No improvement was observed in mental or physical health scores. In 37% of patients, nonnucleoside reverse transcriptase inhibitor drug concentrations were still detectable 1 week after stopping.

CONCLUSIONS

Although HAART can safely be interrupted in patients with a high CD4 T-cell nadir, no improvement in quality of life was established. Patients can experience ARVS, the risk for development of resistance after treatment interruption is realistic, and there is a potential hazard of HIV transmission to sexual partners. We would not actively advise stopping treatment in patients who started treatment too early according to current guidelines.

Evolution of drug resistance in HIV-infected patients remaining on a virologically failing combination antiretroviral therapy regimen

OBJECTIVE

To estimate the extent of drug resistance accumulation in patients kept on a virologically failing regimen and its determinants in the clinical setting.

DESIGN

The study focused on 110 patients of EuroSIDA on an unchanged regimen who had two genotypic tests performed at two time points (t0 and t1) when viral load was > 400 copies/ml.

METHODS

Accumulation of resistance between t0 and t1 was measured using genotypic susceptibility scores (GSS) obtained by counting the total number of active drugs (according to the Rega system v6.4.1) among all licensed antiretrovirals as of 1 January 2006. Patients were grouped according to the number of active drugs in the failing regimen at t0 (GSS_f-t0).

RESULTS

At t0, patients had been on the failing combination antiretroviral therapy (cART) for a median of 11 months (range, 6-50 months). Even patients with extensive resistance to the failing regimen were still receiving benefit from treatment. An overall 6-monthly increase of 1.96 (SD, 2.23) International Aids Society-mutations and an average loss of 1.25 (SD, 1.81) active drugs were estimated. In comparison with patients with GSS_f-t0 = 0, the number of active drugs lost was -1.08 [95% confidence interval (CI), -2.13 to -0.03; P = 0.04] in those with GSS_f-t0 of 0.5-1.5 and -1.24 (95% CI, -2.44 to -0.04; P = 0.04) in those with GSS_f-t0 >or= 2.

CONCLUSIONS

In patients kept on the same virologically failing cART regimen for a median of 6 months, there was considerable accumulation of drug resistance mutations, particularly in patients with initial low level of resistance to the failing regimen. Randomized comparisons of maintenance treatment strategies while awaiting a new suppressive therapy to become available are warranted.

Safety and efficacy of a generic fixed-dose combination of stavudine, lamivudine and nevirapine antiretroviral therapy between HIV-infected patients with baseline CD4 <50 versus CD4 > or = 50 cells/mm3

Background

Antiretroviral therapy (ART) with a generic fixed-dose combination (FDC) of stavudine (d4T)/lamivudine (3TC)/nevirapine (NVP) is widely used in developing countries. The clinical data of this FDC among very advanced HIV-infected patients is limited.

Methods

A retrospective cohort study was conducted among ART-naïve HIV-infected patients who were initiated a generic FDC of d4T/3TC/NVP between May 2004 and October 2005. Patients were categorized into 2 groups according to the baseline CD4 (group A: <50 cell/mm³ and group B: ≥ 50 cell/mm³).

Results

There were 204 patients with a mean ± SD age of 37.1 ± 8.9 years, 120 (58.8%) in group A and 84 (41.2%) in group B. Median (IQR) CD4 cell count was 6 (16–29) cells/mm³ in group A and 139 (92–198) cells/mm³ in group B. Intention-to-treat analysis at 48 weeks, 71.7% (86/120) of group A and 75.0% (63/84) of group B achieved plasma HIV RNA <50 copies/ml (P = 0.633). On-treatment analysis, 90.5% (87/96) in group A and 96.9% (63/65) in group B achieved plasma HIV RNA <50 copies/ml (P = 0.206). At 12, 24, 36 and 48 weeks of ART, mean CD4 were 98, 142, 176 and 201 cells/mm³ in group A and 247, 301, 336 and 367 cells/mm³ in group B, respectively. There were no differences of probabilities to achieve HIV RNA <50 copies/ml (P = 0.947) and CD4 increment at 48 weeks between the two groups (P = 0.870). Seven (9.6%) patients in group A and 4 (8.5%) patients in group B developed skin reactions grade II or III (P = 1.000). ALT at 12 weeks was not different from that at baseline in both groups (P > 0.05).

Conclusion

Initiation of FDC of d4T/3TC/NVP in HIV-infected patients with CD4 <50 and ≥ 50 cells/mm³ has no different outcomes in terms of safety and efficacy. FDC of d4T/3TC/NVP can be effectively used in advance HIV-infected patients with CD4 <50 cells/mm³.

Plasma nevirapine levels, adverse events and efficacy of antiretroviral therapy among HIV-infected patients concurrently receiving nevirapine-based antiretroviral therapy and fluconazole

Background

The clinical data of plasma NVP level, safety and efficacy of antiretroviral therapy (ART) for the concurrent use of nevirapine (NVP)-based ART and fluconazole (FLU) is scanty.

Methods

A retrospective study was conducted in patients who were initiated NVP-based ART between October 2004 and November 2005. The objectives were to compare NVP levels, adverse events, and 36-week efficacy of NVP-based ART between patients who did not receive FLU (group A) and those who received FLU 200 mg/day or 400 mg/day (group B).

Results

There were 122 patients with mean ± SD age of 36 ± 9 years; 81 in group A and 41 in group B. Median (IQR) baseline CD4 cell count was 29 (8–79) cell/mm³ in group A and 19 (8–33) cell/mm³ in group B (P = 0.102). Baseline characteristics between the two groups were similar. Mean ± SD NVP levels were 6.5 ± 3.0 mg/L in group A and 11.4 ± 6.1 mg/L in group B(P < 0.001). One (2.4%) patient in group B developed clinical hepatitis (P = 0.336). Six (7.4%) patients in group A developed NVP-related skin rashes (P = 0.096). There were no differences in term of 36-week antiviral efficacy between the two groups (P > 0.05).

Conclusion

Co-administration of NVP and daily dosage of FLU (200 mg/day and 400 mg/day) results in markedly increased trough plasma NVP level when compared to the administration of NVP alone. The concurrent use of NVP and FLU in very advanced HIV-infected patients is well-tolerated. The immunological and virological responses are favorable.

Pharmacokinetic study of the interaction between itraconazole and nevirapine

OBJECTIVE

To investigate the drug interaction potential between itraconazole and nevirapine.

METHODS

Our study was conducted in 12 healthy volunteers in two phases. In phase 1 (from days 1-28), all subjects were randomly assigned to a two-way crossover study of a nevirapine regimen (nevirapine 200 mg once daily for 7 days) and an itraconazole regimen (itraconazole 200 mg once daily for 7 days) with a 14-day wash-out period between. Phase 2 (from days 43-49) was performed 14 days after phase 1 ended, and all subjects received a combination regimen (nevirapine 200 mg combined with itraconazole 200 mg once daily for 7 days). Nevirapine pharmacokinetic studies were carried out starting with the seventh dose of nevirapine in the nevirapine regimen (on days 7-10 or 28-31) and the combination regimen (on days 49-52). Itraconazole pharmacokinetic studies were carried out starting with the seventh dose of itraconazole in the itraconazole regimen (on days 7-10 or 28-31) and the combination regimen (on days 49-52).

RESULTS

There was no significant difference in nevirapine pharmacokinetic parameters between the nevirapine and combination regimens. Itraconazole plasma concentrations were lower when it was administered in the combination regimen than when it was administered in the itraconazole regimen. The mean C(max), AUC(0-96) and t (1/2) of itraconazole were significantly reduced by 38, 61 and 31%, respectively.

CONCLUSION

Nevirapine had a strong inducing effect on the metabolism of itraconazole, but there was no significant effect of itraconazole on the pharmacokinetics of nevirapine. However, a higher daily dosage of itraconazole might have an inhibitory effect.

Tuberculosis and HIV co-infection: a practical therapeutic approach

HIV and tuberculosis (TB) are leading global causes of mortality and morbidity, and yet effective treatment exists for both conditions. Rifamycin-based antituberculosis therapy can cure HIV-related TB and, where available, the introduction of highly active antiretroviral therapy (HAART) has markedly reduced the incidence of AIDS and death. Optimal treatment regimens for HIV/TB co-infection are not yet clearly defined. Combinations are limited by alterations in the activity of the hepatic cytochrome P450 (CYP) enzyme system, which in particular may produce subtherapeutic plasma concentrations of antiretroviral drugs. For example, protease inhibitors often must be avoided if the potent CYP inducer rifampicin is co-administered. However, an alternative rifamycin, rifabutin, which has similar efficacy to rifampicin, can be used with appropriate dose reduction. Available clinical data suggest that, for the majority of individuals, rifampicin-based regimens can be successfully combined with the non-nucleoside reverse transcriptase inhibitors nevirapine and efavirenz. Most available HAART regimens in areas that have a high burden of TB contain one or the other of these drugs as a backbone. However, significant questions remain as to the optimal dose of either agent required to ensure therapeutic plasma concentrations, especially in relation to particular ethnic groups. The timing of HAART initiation after starting antituberculosis therapy continues to be controversial. Debate centres upon whether early initiation of HAART increases the risk of paradoxical reactions (immune reconstitution-related events) and other adverse events, or whether delay greatly elevates the risk of disease progression. Further prospective clinical data are needed to help inform practice in this area.

Treatment outcomes amongst previously antiretroviral-naïve HIV-infected patients starting lopinavir/ritonavir-containing antiretroviral regimens at the Royal Free Hospital*

OBJECTIVE

To describe outcomes in patients starting first-line antiretroviral regimens including lopinavir/ritonavir (LPV/r) in a routine clinic setting.

METHODS

Previously naïve patients starting LPV/r-containing antiretroviral therapy were included in the study. Virological failure was defined as the first of two viral loads >500 HIV-1 RNA copies/mL more than 6 months after starting LPV/r. Cumulative percentages experiencing virological failure were calculated using Kaplan-Meier methods.

RESULTS

A total of 195 individuals had a median follow-up time of 1.7 years. At 48 weeks, 87.9, 77.4 and 71.6% of patients with pretreatment CD4 counts of <50, 50-200 and >200 cells/microL, respectively, remained on LPV/r. By 48, 72 and 96 weeks, 2.2, 3.0 and 5.0% of patients, respectively, had experienced virological failure, ignoring treatment changes but censoring follow-up at discontinuation of all antiretrovirals; these percentages became 24.0, 33.7 and 42.3% when LPV/r discontinuation was considered as virological failure. Censoring those who stopped LPV/r with a viral load <50 copies/mL and considering as virological failures those who stopped LPV/r with a viral load >50 copies/mL gave 12.1, 14.6 and 17.0% virological failure at 48, 72 and 96 weeks, respectively. Median CD4 count increases at 24, 48 and 72 weeks were 167, 230 and 253 cells/microL, respectively.

CONCLUSIONS

Few patients experienced virological failure whilst on a LPV/r-based regimen, although it was not uncommon for patients in our clinic with higher baseline CD4 counts to discontinue LPV/r.

Prevalence of primary genotypic resistance in a UK centre: Comparison of primary HIV-1 and newly diagnosed treatment-naive individuals

The worrying finding that up to 19% of newly diagnosed HIV-1 cases in the UK have genotypic evidence of transmitted drug-resistant HIV-1 (TrDR-HIV-1) does not concur with levels observed in one London centre. A study of the prevalence of resistance in primary HIV infection and newly diagnosed antiretroviral-naive individuals demonstrated significantly lower levels of TrDR-HIV-1 than previously reported. Variations in the prevalence of TrDR-HIV-1 may reflect the heterogeneity of methodologies and definitions used for resistance.

Pharmacokinetics of experimental antiretroviral agents

Many novel agents are being developed for the management of HIV-1 infection. In currently available classes, there are new protease inhibitors, non-nucleoside and nucleotide reverse transcriptase inhibitors, all in various stages of development. Novel classes include co-receptor entry antagonists (e.g., CCR5 inhibitors) as well as integrase and maturation inhibitors. Data on the pharmacodynamics and the pharmacokinetics of these new agents continue to generate interest. This article will report on the known data of the pharmacokinetics of experimental antiretrovirals, particularly concentrating on recently presented data, and describe the main drug–drug interactions studied to date.

Relationship Between Antiretroviral Prescribing Patterns and Treatment Guidelines in Treatment-Naive HIV-1-Infected US Veterans (1992-2004)

OBJECTIVE

To analyze temporal patterns of antiretroviral (ARV) prescribing practices relative to nationally defined guidelines in treatment-naive patients with HIV-1 infection.

DESIGN

Retrospective cohort study.

METHODS

We evaluated ARV prescribing patterns among ARV treatment-naive veterans who were receiving care within the US Department of Veterans Affairs (VA) from 1992 through 2004 in comparison to evolving adult HIV-1 treatment guidelines.

RESULTS

A total of 15,934 patients initiated ARV treatment. Since 1999, >94% of patients initiated at least a 3-ARV medication combination, although the percentage of patients who initiated a guideline "preferred" or "alternative" regimen never rose to greater than 72% and was significantly associated with being black and with region of care. After 1999, 20% of patients started 4 or more active ARV agents in combination, which was significantly associated with lower baseline CD4 cell count, higher viral load, and receiving care in the western United States. The proportion of patients receiving guideline "not recommended" regimens (virologically undesirable or overlapping toxicities) was <1% after 1997. VA prescribing trends generally predated guideline recommendations by 6 to 12 months.

CONCLUSIONS

VA prescribing patterns for ARV initiation adhere to treatment guidelines that maximize safety. Guidelines designed to maximize efficacy were not followed as stringently. Evaluating clinical practice patterns against contemporary treatment guidelines can inform guideline development.

Abacavir/lamivudine fixed-dose combination tablet for the treatment of HIV-1 infection

The fixed-dose combination tablet of the two nucleotide reverse transcriptase inhibitors abacavir (ABC) and lamivudine (3TC) was licensed in 2004. It is dosed once daily with no food restrictions and licensed for the treatment of HIV infection in treatment-naive individuals in combination with another class of antiretroviral. Its virological efficacy has been demonstrated in clinical studies with up to 96-week follow-up in combination with non-nucleoside reverse transcriptase inhibitors and protease inhibitors. Less lipodystrophy is seen with abacavir than stavudine or zidovudine. Resistance mutations selected by ABC/3TC leave options for future treatment. Abacavir hypersensitivity reaction occurs in 5% of those receiving ABC and genetic susceptibility testing is undergoing trial. ABC/3TC is a largely well-tolerated nucleoside reverse transcriptase inhibitor backbone with proven efficacy.

Tenofovir Disoproxil Fumarate, Emtricitabine, and Efavirenz Versus Fixed-Dose Zidovudine/Lamivudine and Efavirenz in Antiretroviral-Naive Patients

BACKGROUND

In antiretroviral-naive patients, tenofovir disoproxil fumarate (TDF), emtricitabine (FTC), and efavirenz (EFV) demonstrated superior outcomes compared with fixed-dose zidovudine (ZDV)/lamivudine (3TC) and EFV through 48 weeks. Results through a 96-week extension phase are presented.

METHODS

In this randomized, open-label, noninferiority trial, 517 antiretroviral-naive HIV-infected patients received TDF, FTC, and EFV (TDF + FTC + EFV) or ZDV/3TC and EFV (ZDV/3TC + EFV). The primary endpoint was the proportion of patients with an HIV RNA level <400 copies/mL in patients without baseline nonnucleoside resistance.

RESULTS

Through week 96, significantly more patients receiving TDF + FTC + EFV achieved and maintained an HIV RNA level <400 copies/mL (75% receiving TDF + FTC + EFV vs. 62% receiving ZDV/3TC + EFV; P = 0.004). There was a trend toward greater virologic suppression to <50 copies/mL in the TDF + FTC + EFV group (67% vs. 61%; P = 0.16). The TDF + FTC + EFV group demonstrated a significantly greater increase in CD4 count (270 vs. 237 cells/mm; P = 0.036). No patient developed the K65R mutation. Limb fat at week 96 was significantly greater in the TDF + FTC + EFV group versus the ZDV/3TC + EFV group (7.7 vs. 5.5 kg; P < 0.001).

CONCLUSION

Over 96 weeks, the combination of TDF, FTC, and EFV was superior to fixed-dose ZDV/3TC + EFV for achieving and maintaining an HIV RNA level <400 copies/mL and an increase in CD4 cells.

Lopinavir/ritonavir: a review of its use in the management of HIV infection

Coformulated lopinavir/ritonavir (Kaletra) is a boosted protease inhibitor (PI) containing lopinavir and low-dose ritonavir. It is approved for use in combination with other antiretroviral drugs for the treatment of HIV infection in adults, adolescents and children aged >or=6 months (in the US) or >or=2 years (in the EU).Lopinavir/ritonavir-based antiretroviral therapy (ART) is generally well tolerated and has shown durable virological efficacy in clinical trials in ART-naive and -experienced patients with virological failure. Lopinavir/ritonavir is one of the preferred PIs for first-line treatment of HIV infection in adults, adolescents and children, according to US and British guidelines, reflecting its comparatively better virological efficacy than nelfinavir and low incidence of de novo resistance during long-term treatment. Lopinavir/ritonavir-based treatment may produce a more effective virological response than other PI-based regimens in single PI-experienced, non-nucleoside reverse transcriptase inhibitor (NNRTI)-naive patients. In PI- and NNRTI-experienced patients, atazanavir/saquinavir was inferior to lopinavir/ritonavir; further well designed trials are required to determine the comparative efficacy of lopinavir/ritonavir versus other PIs such as ritonavir-boosted atazanavir, or fosamprenavir or tipranavir in these patients. Lopinavir/ritonavir is more likely than atazanavir (alone or boosted) or nelfinavir to cause hypertriglyceridaemia and is associated with a higher incidence of hypercholesterolaemia than atazanavir (alone or boosted). The new lopinavir/ritonavir tablet coformulation offers a reduced pill count and lack of food interaction, and ART-naive patients in the US and Canada, who are not receiving efavirenz, nelfinavir, nevirapine or amprenavir, may benefit from convenient once-daily administration of lopinavir/ritonavir. Thus, lopinavir/ritonavir is a convenient, effective option for use in the treatment of HIV infection in ART-naive and -experienced adults, adolescents and children.

HIV viral load monitoring in resource-limited regions: optional or necessary?

Although it is a standard practice in high-income countries, determination of the human immunodeficiency virus (HIV) load is not recommended in developing countries because of the costs and technical constraints. As more and more countries establish capacity to provide second-line therapy, and as costs and technological constraints associated with viral load testing decrease, the question of whether determination of the viral load is necessary deserves attention. Viral load testing could increase in importance as a guide for clinical decisions on when to switch to second-line treatment and on how to optimize the duration of the first-line treatment regimen. In addition, the viral load is a particularly useful tool for monitoring adherence to treatment, performing sentinel surveillance, and diagnosing HIV infection in children aged <18 months. Rather than considering viral load data to be an unaffordable luxury, efforts should be made to ensure that viral load testing becomes affordable, simple, and easy to use in resource-limited settings.

Issues in the design of trials comparing management strategies for heavily pretreated patients

PURPOSE OF REVIEW

Strategies for the optimal management of heavily pretreated patients with multiple drug resistance mutations in whom viral suppression is not possible are not well defined. Trials of strategic management approaches (as opposed to testing the effect of one specific drug) in this area have been mainly limited to evaluating treatment interruptions, testing the benefits of multidrug ('mega-highly active antiretroviral therapy') regimens, and evaluating the use of resistance test data for choosing new regimens.

RECENT FINDINGS

Treatment interruption before the start of a new regimen has been found to be detrimental, in terms of the risk of clinical disease, compared with no interruption. Mega-highly active antiretroviral therapy has not yet convincingly been shown to improve overall outcomes. The use of genotypic resistance testing has been shown to be useful when constructing a new regimen.

SUMMARY

Several challenges exist in designing future strategic trials in this area. These include the formulation of suitable new strategies which are generalizable across specific drugs and drug classes, the choice of suitable and feasible endpoints, and the incorporation of sufficient flexibility (so that patients are not too constrained to commit to entry) without compromising the ability to answer the question.

Considerations in the design of randomized controlled trials evaluating the optimal time to initiate antiretroviral therapy in previously untreated HIV-1-infected patients

PURPOSE OF REVIEW

This paper addresses design issues around 'when to start' trials in adults and children and in chronic and acute HIV infection. Issues for young children treated soon after birth and recently seroconverting adults differ, and are also discussed.

RECENT FINDINGS

No trials have been published addressing this question for combination antiretroviral therapy in chronic HIV infection, and the evidence base for guidelines has largely been derived from observational studies. The biases inherent in observational data and recent results from the adult SMART trial may have moved the level of equipoise from 'unstable certainty' (mitigating against randomization) to a renewed call for a very large clinical endpoint trial of when to start therapy in the era of highly active antiretroviral therapy. Older children could also be enrolled in such a trial, as the predictive value of CD4 cell count values in children over 5 years and young adults. In acute infection, ongoing trials in adults and children is similar considering strategies of early short-term combination antiretroviral therapy compared with deferred therapy. Although not strictly 'when to start trials', these approaches could reduce life-long exposure to antiretroviral therapy while maintaining clinical and immunological well being.

SUMMARY

Issues in the design of a future randomized trial of when to start antiretroviral therapy in chronic HIV infected adults and older children are discussed, while the role of early limited therapy in primary infection awaits results of ongoing trials.

The WHO public-health approach to antiretroviral treatment against HIV in resource-limited settings

WHO has proposed a public-health approach to antiretroviral therapy (ART) to enable scaling-up access to treatment for HIV-positive people in developing countries, recognising that the western model of specialist physician management and advanced laboratory monitoring is not feasible in resource-poor settings. In this approach, standardised simplified treatment protocols and decentralised service delivery enable treatment to be delivered to large numbers of HIV-positive adults and children through the public and private sector. Simplified tools and approaches to clinical decision-making, centred on the "four Ss"--when to: start drug treatment; substitute for toxicity; switch after treatment failure; and stop--enable lower level health-care workers to deliver care. Simple limited formularies have driven large-scale production of fixed-dose combinations for first-line treatment for adults and lowered prices, but to ensure access to ART in the poorest countries, the care and drugs should be given free at point of service delivery. Population-based surveillance for acquired and transmitted resistance is needed to address concerns that switching regimens on the basis of clinical criteria for failure alone could lead to widespread emergence of drug-resistant virus strains. The integrated management of adult or childhood illness (IMAI/IMCI) facilitates decentralised implementation that is integrated within existing health systems. Simplified operational guidelines, tools, and training materials enable clinical teams in primary-care and second-level facilities to deliver HIV prevention, HIV care, and ART, and to use a standardised patient-tracking system.

Design Issues in Initial HIV-Treatment Trials: Focus on Actg A5095

ACTG (AIDS Clinical Trials Group) A5095 was a double-blinded Phase III clinical trial designed to compare three simple strategies for the initial treatment of HIV-1 infection: a non-nucleoside reverse transcriptase inhibitor (NNRTI) combined with two nucleosides, a triple-nucleoside regimen, and an NNRTI combined with three nucleosides. The study was designed to provide a rigorous evaluation of the relative effectiveness of the three different treatment strategies in achieving and maintaining durable HIV-1 RNA suppression using both superiority and non-inferiority designs. At the same time, we sought to provide study participants with flexible treatment management options that closely reflected clinical care approaches available outside the setting of a clinical trial in this rapidly changing field of medicine. Fulfilling both of these goals required making decisions about the primary endpoint definition, blinding, treatment changes, and stopping guidelines for the primary efficacy hypotheses. In this paper we describe the study design decisions that were made, in the context of randomized HIV treatment trials in general. We hope that the discussion will inform the design of treatment strategy trials, both for HIV and for other diseases where clinical standards change rapidly. We also hope to inform the field regarding issues in choosing composite versus virological endpoints as well as other key considerations in trial design and monitoring.

Virological and immunological outcomes at 3 years after starting antiretroviral therapy with regimens containing non-nucleoside reverse transcriptase inhibitor, protease inhibitor, or both in INITIO: open-label randomised trial

BACKGROUND

Antiretroviral therapy has greatly reduced HIV mortality and morbidity. However, the best sequence of regimens and implications of initial regimen for long-term therapeutic success are not well defined.

METHODS

In INITIO, a large international randomised trial, we compared antiretroviral therapy with two nucleoside analogue reverse transcriptase inhibitors (didanosine+stavudine) plus either a non-nucleoside reverse transcriptase inhibitor (efavirenz, EFV) or a protease inhibitor (nelfinavir, NFV), or both (EFV/NFV), in patients with HIV-1 infection who had not previously received antiretroviral drugs. Primary outcomes were proportion with undetectable HIV RNA in plasma, and change in CD4 count from baseline at 3 years. Analyses were by intention-to-treat. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN44582462.

FINDINGS

We followed up 911 participants (297 EFV, 311 NFV, 303 EFV/NFV). At 3 years, the proportion with HIV RNA less than 50 copies per mL was highest in the EFV group (188 [74%] EFV, 162 [62%] NFV, 155 [62%] EFV/NFV; p=0.004). Mean (95% CI) increases in CD4 count were 316x10(6) cells per L (288-343) for EFV, 289x10(6) cells per L (262-316) for NFV, and 274x10(6) cells per L (231-291) for EFV/NFV (p=0.1). Fewer participants in the EFV group than in the other groups stopped adequate antiretroviral therapy for more than 30 days (p=0.005). Participants in the EFV/NFV group had shorter time to stopping the initial regimen (p<0.0001) and to a treatment modifying adverse event (p=0.04) than those in the other groups.

INTERPRETATION

Starting antiretroviral therapy with a three-drug/two-class regimen including efavirenz was better than starting with regimens including nelfinavir or efavirenz plus nelfinavir in terms of virological suppression and durability of the initial regimen. The shorter time on adequate antiretroviral therapy or to a treatment-modifying adverse event might explain the absence of additional benefit for the four-drug regimen.

Lopinavir/Ritonavir or Efavirenz plus two Nucleoside Analogues as First-Line Antiretroviral Therapy: A Non-Randomized Comparison

Background

Although efavirenz (EFV) and lopinavir/ritonavir (LPV/r) are both recommended antiretroviral agents for combination therapy in drug-naive HIV-infected patients, no randomized comparison of their efficacy and tolerability is available yet. A multi-cohort prospective observational comparative study was performed.

Methods

Efficacy was examined comparing time to virological failure, CD4 recovery and clinical progression. Tolerability was examined comparing time to treatment discontinuation for any reason and for toxicity and time to liver enzymes or lipid alterations. Survival analysis was conducted by an intent-to-treat principle using the Kaplan–Meier method, and standard and weighted Cox regression models.

Results

A total of 674 antiretroviral-naive patients starting a two nucleoside reverse transcriptase inhibitor regimen plus either EFV ( n=481) or LPV/r ( n=193) were examined. At baseline, patients starting LPV/r had higher HIV RNA and lower CD4+ T-cell counts. There was no difference in the adjusted hazards of virological failure (LPV/r versus EFV relative hazard [RH] 1.16, 95% confidence intervals [CI]: 0.58–2.32, P=0.67), CD4 recovery (RH=0.93, 95% CI: 0.66–1.30, P=0.66), clinical progression (RH=1.64, 95% CI: 0.70–3.84, P=0.25), drug discontinuation for toxicity (RH=0.92, 95% CI: 0.51–1.64, P=0.76) and for any reason, and rates of liver enzyme and total/low density lipoprotein (LDL) cholesterol elevation. In contrast, the rate of triglycerides elevations (>1 NCEP Adult Treatment Panel III category increase) was higher in the LPV/r group (RH=1.69, 95% CI: 1.14–2.50; P=0.01). Models weighted for the inverse of conditional probability of receiving either drug applied to the efficacy endpoints yielded similar results. CD4 recovery with both drugs was also similar in the lowest CD4 strata.

Conclusions

Our analysis suggests similar efficacy and tolerability for EFV- or LPV/r-based first-line antiretroviral regimens. LPV/r was associated with higher rates of hypertriglyceridaemia.

The clinical pharmacology of antiretrovirals in development

Drugs in development for the management of HIV type 1 (HIV-1) infection include agents in existing classes and agents of novel classes. Of existing classes, new protease inhibitors, nucleoside reverse transcriptase inhibitors and non-nucleoside reverse transcriptase inhibitors are in development. Novel therapeutic approaches include the development of chemokine receptor (CCR)5 antagonists, integrase inhibitors and maturation inhibitors. CCR5 antagonists are thought to inhibit HIV-1 entry into host cells by occupying a specific site on the CCR5 receptor, preventing attachment of the HIV-1 envelope protein gp120. Integrase inhibitors are small synthetically prepared molecules that block RNA/DNA interactions and modify protein or enzyme synthesis. Data on the pharmacokinetics and pharmacodynamics of these new antiretroviral agents continue to generate interest. This review reports the known data on the pharmacokinetics of experimental antiretrovirals, and describe the main drug-drug interactions studied so far.

Boosted versus Unboosted Indinavir with Zidovudine and Lamivudine in Nucleoside Pre-Treated Patients: A Randomized, Open-Label Trial with 112 Weeks of Follow-Up (HIV-Nat 005)

Introduction

The use of HIV protease inhibitors (PIs) in a ritonavir (RTV)-boosted form is now common. However, randomized data comparing boosted with unboosted PI strategies are scarce.

Methods

This randomized, open-label trial compared indinavir (IDV) 800 mg three times daily with IDV/RTV 800/100 mg twice daily, both given with zidovudine (AZT)/lamivudine (3TC) twice daily in individuals with at least 3 months previous AZT experience. The primary endpoint was the time-weighted average change in HIV RNA from baseline. Designed as a 48-week study, follow-up continued until week 112. Primary analysis is by intention to treat.

Results

One hundred and three patients commenced therapy and are included in the analysis. Patients had a median of 29 months past nucleoside reverse transcriptase inhibitor (NRTI) exposure. Baseline median (interquartile range) log10 HIV RNA was 4.0 (3.3–4.5) and CD4+T-cell count 166 (40–323) cells/μl. After 112-weeks of study there was no significant difference observed between arms in the mean (sd) change in time-weighted average HIV RNA from baseline (-1.6 [1.1] HIV RNA copies/week/ml three times daily arm; -1.4 [1.1] HIV RNA copies/week/ml twice daily arm; P=0.3). Both arms were associated with substantial toxicity expressed as serious adverse events and study drug interruptions. The twice daily arm experienced greater dyslipidaemia. Mean (sd) changes in time-weighted CD4+ T-cell count from baseline were similar [88 (84) cells/week/μl three times daily arm; 70 [109] cells/week/μl twice daily arm; P=0.3).

Conclusions

RTV-boosted IDV 800/100 mg twice daily demonstrated comparable efficacy to unboosted IDV 800mg three times daily dosing. Both regimens were associated with substantial toxicity. Use of lower doses of RTV-boosted IDV may result in better tolerability without loss of efficacy and warrant further research.