Abacavir does not influence the rate of virological response in HIV-HCV-coinfected patients treated with pegylated interferon and weight-adjusted ribavirin

BACKGROUND

The combination of pegylated interferon (PEG-IFN) plus ribavirin (RBV) is the standard of care for hepatitis C virus (HCV) treatment in HIV-coinfected individuals. In 2007, abacavir (ABC)-based antiretroviral therapy was, for the first time, reported to be associated with early virological failure during HCV treatment. The aim of our study was to evaluate the effect of ABC on the response rate to HCV therapy.

METHODS

A retrospective analysis of HIV-HCV-coinfected patients treated with PEG-IFN and weight-adjusted RBV in four hospitals in Spain was performed. An analysis of baseline descriptive variables was conducted. Logistic regression models were used to test possible associations between non-response and pretreatment characteristics, including antiretroviral drugs.

RESULTS

A total of 244 HIV-HCV-coinfected patients treated with PEG-IFN and RBV were included. Overall, 85% of patients were on highly active antiretroviral therapy; of these patients, 24% received ABC-based regimens. The most frequent genotypes were 1 and 3. RBV dosing was 213.2 mg/kg/day in 97% of the patients. In the global intent-to-treat analyses, 46.3% of patients reached a sustained virological response (SVR; 46.2% in ABC group versus 46.7% in non-ABC group, P=1). The only two factors in the multivariate analysis that were statistically associated with an increased risk of failure to achieve SVR were HCV genotypes 1 or 4 and older age. The use of ABC was not associated with failure to achieve SVR at any of the other time points evaluated.

CONCLUSIONS

Our data suggest that the use of ABC-based regimens in the context of HCV therapy does not negatively affect the outcome of this treatment.

Antiviral activity of low-dose alovudine in antiretroviral-experienced patients: results from a 4-week randomized, double-blind, placebo-controlled dose-ranging trial

BACKGROUND

Alovudine inhibits replication of highly nucleoside reverse transcriptase inhibitor (NRTI)-resistant HIV strains in vitro. However, dose-dependent safety concerns resulted in its initial development being halted. Recently, a 4-week course of alovudine 7.5 mg/day added to a stavudine-free failing regimen yielded a significant decrease in viral load by -1.88 log(10) HIV-1 RNA copies/mL. The magnitude of the reduction in viral load suggested that lower doses might still be effective while offering adequate safety during long-term use.

OBJECTIVE

To determine whether lower dosages of alovudine still provide significant antiviral activity in patients with broad NRTI resistance.

METHODS

A randomized, double-blind, placebo-controlled trial investigating three doses of alovudine (0.5, 1 and 2 mg) or placebo added for 4 weeks to a failing regimen in patients with evidence of NRTI-resistant HIV strains [>or=2 thymidine-associated mutations (TAMs)]. The primary endpoint was the mean viral load reduction between baseline and week 4.

RESULTS

Seventy-two patients were enrolled in the study: 21, 13, 18 and 20 in the placebo and 0.5, 1 and 2 mg arms, respectively. Baseline median CD4 count and viral load were 298 cells/microL (range 44-692 cells/microL) and 3.9 log(10) copies/mL (range 2.5-5.2 log(10) copies/mL), respectively. Baseline viral isolates harboured a median of four TAMs. Alovudine was added to a median four-drug failing regimen. At week 4, compared with placebo, mean viral load changes were -0.42 log(10) [95% confidence interval (CI) -0.67 to -0.18] and -0.30 log(10) (-0.55 to -0.06) in the 2 and 1 mg arms, respectively. There was no significant change in CD4 cell count. Alovudine was well tolerated.

CONCLUSION

A 4-week course of alovudine 2 mg/day provided a modest but significant viral load reduction in patients harbouring viruses with a median of four TAMs.

Pharmacokinetics of coadministered ritonavir-boosted elvitegravir and zidovudine, didanosine, stavudine, or abacavir

OBJECTIVE

To evaluate the potential for clinically relevant drug interactions between ritonavir-boosted elvitegravir (EVG/r) and the nucleoside reverse transcriptase inhibitors (NRTIs) zidovudine (ZDV), didanosine (ddI), stavudine (d4T), or abacavir (ABC) upon coadministration.

METHODS

In 3 studies, healthy subjects were administered a single dose of ddI, d4T, or ABC, or multiple doses of ZDV, followed by multiple doses of EVG/r alone and together with an NRTI; pharmacokinetics (PK) of EVG and NRTIs were evaluated after individual administration and coadministration. Lack of PK alteration bounds (90% confidence intervals [CI]) for the NRTIs were based on the lack of PK-based dose adjustments per prescribing information.

RESULTS

Twenty-four of 28, 32/32, and 24/26 subjects completed the ZDV-EVG/r, ddI/d4T-EVG/r, and ABC-EVG/r studies, respectively. All study drugs were well tolerated and no serious adverse events were noted. The PK of ZDV, its glucuronide (G-ZDV), d4T, ABC, and EVG were within the lack of PK alteration 90% CI bounds upon coadministration. Exposures of ddI were modestly (approximately 15%) lower, but these changes are unlikely to be clinically meaningful.

CONCLUSIONS

There are no clinically relevant drug interactions between EVG/r and the NRTIs zidovudine, didanosine, stavudine, or abacavir. These agents can be coadministered without dose adjustment.

Low-level K65R mutation in HIV-1 reverse transcriptase of treatment-experienced patients exposed to abacavir or didanosine

BACKGROUND

Prior abacavir (ABC) or didanosine (ddI) therapy can result in the L74V/I or K65R mutation in HIV-1 reverse transcriptase. Preexisting K65R may have an impact on the treatment response to tenofovir disoproxil fumarate (TDF).

METHODS

An allele-specific polymerase chain reaction (AS-PCR) assay was developed to detect K65R with a lower limit of quantitation of 0.5%.

RESULTS

Among baseline plasma samples from 63 treatment-naive patients, no K65R was detected by AS-PCR. Among baseline samples from 154 treatment-experienced patients, 8 had K65R and 44 had L74V/I by population sequencing. Low-level K65R was detected in an additional 11 patients by AS-PCR, 3 of whom subsequently developed full K65R. Baseline K65R correlated with absence of thymidine analog mutations (TAMs; P = 0.003) and use of ABC or ddI (P = 0.004). Patients with full or low-level K65R at baseline or with L74V/I showed a diminished TDF response. Multivariate analyses confirmed that multiple TAMs, K65R, and L74V/I were independent predictors of diminished TDF response.

CONCLUSIONS

Prior therapy with ABC or ddI can result in a population genotype that shows K65R or L74V/I but does not reveal low-level K65R present in some patients. Subsequent treatment intensification with TDF resulted in a poor virologic response and may result in expansion of the preexisting K65R mutant.

HPV oral infection. Case report of an HIV-positive Nigerian sex worker

HPV infections have become a major problem in immunocompromised patients, particularly in HIV-positive subjects. HPV lesions are observed more frequently in the ano-genital area and rarely in different body areas, such as the skin and oral cavity. However, in HIV-positive subjects there is an increased risk of oral condylomas. We describe the case of an HIV-positive Nigerian young woman, who came to our notice due to the appearance of small labial and mouth mucous membrane lesions, related to HPV infection, as shown by a biopsy. These lesions were not evident in the genital area. After two years in which the patient no longer received therapy, there was a progressive reduction in CD4 count, associated with the development of the oral condylomas. Hence the patient began a new HAART combination, but after seven months, although a slight improvement emerged in the CD4 count with the disappearance of HIV-RNA, there has been no regression of oral condylomas.

Metabolic effects of protease inhibitor-sparing antiretroviral regimens given as initial treatment of HIV-1 Infection (AIDS Clinical Trials Group Study A5095)

OBJECTIVE

To assess metabolic changes after initiation of protease inhibitor (PI)-sparing regimens in antiretroviral-naive patients.

METHODS

Metabolic changes were analyzed within the triple-nucleoside (zidovudine [ZDV]/lamivudine [3TC]/abacavir [ABC])-containing, 3-drug efavirenz (EFV) [ZDV/3TC + EFV]-containing, and 4-drug EFV [ZDV/3TC/ABC + EFV]-containing arms of the AIDS Clinical Trials Group multicenter trial A5095. Metabolic values were compared with published US general population norms.

RESULTS

From week 0 to week 24, all arms exhibited similar mild median increases in glucose and decreases in insulin sensitivity, whereas changes in lipids were greater in the ZDV/3TC + EFV and ZDV/3TC/ABC + EFV arms than in the ZDV/3TC/ABC arm: triglyceride (TG; 7, 18, and -1 mg/dL, respectively), total cholesterol (TC; 23, 28, and 5 mg/dL, respectively), low-density lipoprotein cholesterol (LDL-C; 9, 14, and 1 mg/dL, respectively), and high-density lipoprotein cholesterol (HDL-C; 10, 10, and 5 mg/dL, respectively). Adjusted mean study lipid values of all study participants at week 0 and week 96 compared with those of the National Health and Nutrition Examination Survey (NHANES) 1999 through 2002 values were: TG (148, 187, and 123 mg/dL, respectively), TC (164, 195, and 203 mg/dL, respectively), HDL-C (35, 47, and 51 mg/dL, respectively), and LDL-C (101, 117, and 123 mg/dL, respectively) (P < or = 0.005 for each value vs. NHANES values).

CONCLUSIONS

Similar mild increases in glucose and decreases in insulin sensitivity were observed in all regimens, whereas lipids were modestly higher in the EFV-containing arms. Compared with general population norms, the metabolic dysfunctions of concern after these PI-sparing therapies were increasingly abnormal TC and lower (but improved relative to baseline) HDL-C levels.

Tenofovir and abacavir combination therapy: lessons learned from an urban clinic population

Regimens containing abacavir (ABC), tenofovir (TDF), and lamivudine (3TC) have recently been demonstrated to have high failure rates. This poses a clinical dilemma of how to manage patients currently being treated with other regimens containing tenofovir/abacavir. We evaluated the outcomes of tenofovir/abacavir regimens in our clinical practice through a retrospective review of 2655 charts. Two hundred patients (7%) were on a tenofovir/abacavir-containing regimen. Fifty-nine patients met the criteria for analysis and were grouped into three groups: (1) antiretroviral naïve, (2) virally suppressed patients switched to TDF/ABC, and (3) patients with failure of their first antiretroviral regimen. Rates of viral suppression in the naïve, switch, and first-failure groups were 95%, 86%, and 46%, respectively. In the first-failure group, viral suppression was 66% without and 18% with a preexisting M184V. A composite analysis of the groups revealed a success rate of 86% when the regimen contained zidovudine (ZDV) and 62% when it did not. No K65R mutations were noted. These findings support continued caution in the use of TDF/ABC in combination. However, these data suggest that this combination may be successfully used in selected situations such as in combination with ZDV. In patients already virally suppressed on a TDF/ABC-containing regimen, considerations include continuing the regimen or adding zidovudine, in the attempt to protect against the development of a K65R mutation and/or virologic failure, versus changing a stable regimen.

Plasma HIV-1 RNA dynamics in antiretroviral-naive subjects receiving either triple-nucleoside or efavirenz-containing regimens: ACTG A5166s

OBJECTIVE

We sought to compare clearance rates of plasma human immunodeficiency virus type 1 (HIV-1) RNA in men and women starting triple-nucleoside-based versus efavirenz (EFV)-based regimens.

METHODS

First- and second-phase decay rates of plasma HIV-1 were compared in men and women initiating a triple nucleoside reverse-transcriptase inhibitor (NRTI) regimen versus regimens that included EFV plus an NRTI. Subjects (n=64) were randomized to receive zidovudine/lamivudine/abacavir (triple-nucleoside regimen), zidovudine/lamivudine plus EFV (3-drug EFV regimen) or zidovudine/lamivudine/abacavir plus EFV (4-drug EFV regimen). Plasma HIV-1 RNA levels were fitted to a biexponential viral-dynamics model using a nonlinear mixed-effects model. Nonparametric Wilcoxon tests compared empirical Bayes estimates of first- and second-phase viral decay rates between treatment arms and sex.

RESULTS

Median first-phase viral decay rates were significantly faster in subjects receiving the 3-drug EFV regimen (0.67/day), compared with those receiving the triple-nucleoside regimen (0.56/day; P=.02). The second-phase viral decay rate was also faster in the 3-drug EFV group than in the triple-nucleoside group (P=.09). Decay rates in the 4-drug EFV group were intermediate. Viral decay rates were not significantly different in men and women. CONCLUSIONS Faster initial viral decay in subjects randomized to a 3-drug EFV-based regimen corresponded to the overall superior efficacy of that regimen. Viral decay rates did not differ by sex.

Once-daily highly active antiretroviral therapy for HIV-infected children: safety and efficacy of an efavirenz-containing regimen

OBJECTIVE

To improve adherence and virologic suppression, we assessed the feasibility and effectiveness of a once-daily regimen of efavirenz with 3 nucleoside reverse transcriptase inhibitors as first-line or second-line highly active antiretroviral therapy in a cohort of HIV-1-infected children.

METHODS

HIV-1-infected children naive to efavirenz were treated with a combination of efavirenz, abacavir, didanosine, and lamivudine in an observational, prospective, single-center study. Virologic failure-free survival was assessed with Kaplan-Meier analysis. The CD4+ T-cell increase was estimated by using a generalized linear model incorporating repeated measurements.

RESULTS

Thirty-six children received the study medication for a median of 69 weeks. Virologic failure-free survival rates were 76% and 67% after 48 weeks and 96 weeks, respectively. No significant difference was found in efficacy between first-line and second-line highly active antiretroviral therapy. All children receiving highly active antiretroviral therapy showed a sustained CD4+ T-cell increase, irrespective of virologic suppression. Growth rates improved with highly active antiretroviral therapy. Study medication administration was stopped for 14 children, mostly because of nonadherence (4 cases) or virologic rebound (5 cases) and because of adverse events (unrelated death and grade 2 liver toxicity) in 2 cases. Lipid abnormalities and abacavir-related hypersensitivity were not observed.

CONCLUSIONS

For the first time, once-daily highly active antiretroviral therapy is demonstrated to be a safe, convenient, and potent antiretroviral regimen for HIV-1-infected children.

Pilot study of once-daily simplification therapy with abacavir/lamivudine/zidovudine and efavirenz for treatment of HIV-1 infection

OBJECTIVE

The purpose of this pilot study was to explore the efficacy and safety of the abacavir/lamivudine/zidovudine fixed-dose combination tablet administered as two tablets once daily (qd) versus one tablet twice daily (bid) in combination with efavirenz (EFV).

METHOD

This was a prospective, randomized, open-label, multicenter study with a 24-week treatment period in 7 outpatient HIV clinics in the United States. Patients currently receiving an initial regimen of abacavir/lamivudine/zidovudine bid plus EFV qd for at least 6 months with HIV-1 RNA <50 copies/mL for at least 3 months and a screening CD4+ cell count > or = 200 cells/mm3 were eligible. Thirty-six patients enrolled, and 35 (97%) completed the study. Participants were randomized to switch to 2 tablets of abacavir/lamivudine/zidovudine qd plus EFV qd (QD arm) or continue current treatment (BID arm) for 24 weeks.

RESULTS

Efficacy, safety, and adherence were evaluated. Median baseline CD4+ cell count was 521 cells/mm3. At week 24, HIV-1 RNA <50 copies/mL was achieved for 94% of participants in the QD arm and 89% in the BID arm by intent-to-treat, missing = failure analysis (95% confidence interval for difference: > or = 0.29 to +0.18, p = 1.000). At week 24, median CD4+ cell count change from baseline was +26 cells/mm3 for the QD arm and -39 cells/mm3 for BID arm. One patient randomized to the QD arm met virologic failure criteria (confirmed HIV-1 RNA >120 copies/mL) at week 20 and viral genotype showed M184V. After failure, this patient revealed he never took EFV throughout the entire study after randomization, effectively receiving only abacavir/lamivudine/zidovudine qd alone. Median adherence was slightly higher in the QD arm, although both arms had broad variability and overlapping interquartile ranges. Adverse events were infrequent and occurred with similar frequency between arms; treatment-related adverse events were abdominal pain, flatulence, nausea, headache, and abnormal dreams (1 patient [3%] for each adverse event). No patients withdrew due to adverse events, and no abacavir hypersensitivity reactions were reported.

CONCLUSION

In this pilot study of patients suppressed on abacavir/lamivudine/zidovudine bid plus EFV, 94% of participants switching to abacavir/lamivudine/zidovudine qd plus EFV maintained virologic suppression, compared to 89% of participants continuing abacavir/lamivudine/zidovudine bid plus EFV.

Abacavir plasma pharmacokinetics in the absence and presence of atazanavir/ritonavir or lopinavir/ritonavir and vice versa in HIV-infected patients

BACKGROUND

Significant interactions between abacavir and other antiretrovirals have not been reported. This study investigated the steady-state plasma pharmacokinetics of abacavir when co-administered with atazanavir/ritonavir or lopinavir/ritonavir in HIV-infected individuals.

METHODS

HIV-infected subjects on abacavir (600 mg once daily) plus two nucleoside reverse transcriptase inhibitors (NRTIs) (excluding tenofovir) underwent a 24 h pharmacokinetic assessment for plasma abacavir concentrations. Atazanavir/ritonavir (300/100 mg once daily; arm (1) or lopinavir/ritonavir (400/100 mg twice daily; arm (2) were then added and the 24 h pharmacokinetic assessment repeated. Arm 3 included subjects stable on atazanavir/ritonavir or lopinavir/ritonavir and two NRTIs (excluding tenofovir or abacavir). These patients underwent a pharmacokinetic assessment for atazanavir/ritonavir or lopinavir/ritonavir concentrations on day 1, abacavir (600 mg once daily) was then added to the regimen and the pharmacokinetic assessment repeated. Within-subject changes in drug exposure were evaluated by geometric mean (GM) ratios and 95% confidence intervals (CI).

RESULTS

Twenty-four patients completed the study. GM (95% CI) abacavir area under the curve (AUC) was 18,621 (15,900-21,807) and 15,136 (13,339-17,174) ng.h/ml without and with atazanavir/ritonavir and 15,136 (12,298-18,628) and 10,471 (9,270-11,828) ng.h/ml without and with lopinavir/ritonavir. GM (95% CI) atazanavir AUC without and with abacavir was 26,915 (13,252-54,666) and 28,840 (19,213-43,291) ng.h/ml; lopinavir AUC without and with abacavir was 60,253 (48,084-75,509) and 63,096 (48,128-82,718) ng.h/ml.

CONCLUSIONS

No changes in atazanavir or lopinavir exposures were observed following the addition of abacavir; however, decreases in abacavir plasma exposure of 17% and 32% were observed following the addition of atazanavir/ritonavir or lopinavir/ritonavir, respectively.

Abacavir hypersensitivity reaction after switching from the twice-daily to the once-daily formulation

A 36-year-old man with HIV infection developed a reaction compatible with an abacavir hypersensitivity reaction after switching from the twice-daily to the once-daily formulation. The switch was determined by a more convenient intake. The patient was treated with abacavir twice-daily plus lamivudine and efavirenz for more than 5 years with no side effects. At the time of this change, his CD4 count was 1069 cell/mm(3) and HIV-RNA undetectable. Our case suggests that patients should be carefully monitored after switching, and warned about the potential effects.

Abacavir/lamividune combination in the treatment of HIV-1 infection: a review

Consensus guidelines for the management of HIV infection recommend the use of two nucleoside analogues in combination with either a non-nucleoside reverse transcriptase inhibitor or a ritonavir-boosted protease inhibitor in therapy-naive patients. As adherence is crucial for treatment success, regimens with fewer pills, simpler dosing schedules and fewer adverse events have become the first choice for antiretroviral therapy. Fixed-dose combinations further improve the convenience of therapy. There are three dual-nucleoside fixed-dose combinations licensed for treating HIV-infected individuals, which include a combination of abacavir and lamivudine. This article reviews the pharmacology, efficacy, resistance profiles, safety and tolerability of abacavir focussing on its use in combination with lamivudine and discusses the role of this nucleoside backbone in antiretroviral therapy.

Switch to abacavir-based triple nucleoside regimens in HIV-1 infected patients never treated with suboptimal antiretroviral therapy: a review

The major trials conducted on treatment simplification included large portions of patients who had previously received monotherapy or dual therapy and were likely to have relevant mutations of resistance at baseline. These studies concluded that simplification was safe (especially when this population was excluded), with some additional risk of viral failure for subjects simplified to abacavir-based regimens. On the other hand, induction-maintenance studies and other studies which involved only patients who had started HAART as the first-line showed that simplification to abacavir was as safe as continuation of the original regimen and better accepted by the patients. The largest randomized studies of simplification that allowed extrapolation of data on the population of subjects who had never received suboptimal therapy were reviewed. Four studies failed to show significant differences in efficacy between treatment arms, while two detected significant differences in favor of the continuation arms. Simplification to abacavir led to significant decreases in cholesterol and triglyceride levels and to slight improvements in quality of life. No variations in body shape were detected, although the duration was probably insufficient and most studies did not involve adequate technology (i.e. DEXA, CT). Other, smaller studies are also presented in the review, selected for their particular design or analysis, which may contribute to a better understanding of the setting in which simplification may be a feasible option. Choosing the adequate timing and the correct patient characteristics, simplification to abacavir-based regimens is safe and prevents metabolic consequences of therapy.

Salvage therapy with abacavir and other reverse transcriptase inhibitors for human immunodeficiency-associated encephalopathy

BACKGROUND

HIV-associated encephalopathy (HIV-AE) is a severe neurologic condition that affects HIV-infected children. The potential benefit of antiretroviral (ARV) agents with good cerebrospinal fluid (CSF) penetration remains to be defined. Abacavir (ABC) achieves good CSF concentrations and studies of high-dose ABC showed benefit in adults with HIV dementia. The present study evaluated the safety and virologic, immunologic and neuropsychological responses of an ARV regimen including high-dose ABC in children with HIV-AE.

METHODS

Children between 3 months and 18 years old and abacavir-naive with HIV-AE and virologic failure were eligible.

RESULTS

: Seventeen children (16 ARV-experienced) were enrolled and 14 children completed 48 weeks of therapy. The overall tolerability was good; 2 children had a possible hypersensitivity reaction. At week 48, 53% and 59% of the children achieved HIV RNA levels below the limit of quantitation in plasma and CSF, respectively. The median (25%-75% range) change of HIV RNA from baseline to week 48 was -2.29 (-0.81 to -2.47) log10 copies/mL in plasma and -0.94 (0 to -1.13) log10 copies/mL in CSF. The mean increases in CD4 (+/-standard error of mean) cell count and CD4% were 427 (+/-169) cells/mm and 8% (+/-2), respectively. Concentrations of soluble tumor necrosis factor receptor II were reduced in plasma and CSF. Children less than 6 years of age demonstrated significant neuropsychological improvement at week 48.

CONCLUSIONS

In the present study with a limited number of children, highly active ARV therapy including high-dose ABC showed a safety profile similar to standard dose ABC and provided clinical, immunologic and virologic response in children with HIV-AE at week 48. Children less than 6 years of age also demonstrated significant neuropsychological improvement.

Comparative biological and clinical outcomes after a switch from a virologically unsuccessful first protease inhibitor-containing antiretroviral combination to a 3-drug regimen containing efavirenz, nevirapine, or abacavir

BACKGROUND

Incomplete adherence is the main cause of antiretroviral therapy failure during initial combination antiretroviral therapy (cART). A switch to a protease inhibitor-sparing cART may be useful when a patient does not tolerate a first protease inhibitor-containing cART regimen.

METHODS

To compare the biological and clinical outcomes of patients in whom a first protease inhibitor-containing cART regimen failed to control viral replication and whose treatment was switched to cART containing efavirenz, nevirapine, or abacavir, we studied 1440 patients from the French Hospital Database on HIV whose treatment was changed from a first protease inhibitor-containing cART to a 3-drug regimen with either efavirenz, nevirapine, or abacavir while their plasma viral load was detectable.

RESULTS

Kaplan-Meier 12-month probabilities of virological suppression were 73.6%, 53.9%, and 66.1% among patients whose treatment was switched to efavirenz-cART, nevirapine-cART, and abacavir-cART, respectively. Factors associated with a lower likelihood of virological suppression were antiretroviral exposure before the first cART, higher plasma viral load values at the treatment switch, a stavudine-lamivudine backbone after the switch (instead of a zidovudine-lamivudine backbone), and a switch to nevirapine (adjusted hazard ratio, 0.63 [95% CI, 0.54-0.74], compared with efavirenz) or abacavir (adjusted hazard ratio, 0.84 [95% CI, 0.68-1.04] compared with efavirenz). There was no difference among the 3 groups with regard to immunological gain (>50 CD4+ T cells/mm3) or clinical outcome.

CONCLUSION

When virological rebound occurs from receipt of protease inhibitor-containing cART, virological suppression can be obtained after a switch to a protease inhibitor-free cART--efavirenz-cART yielding the highest rate of virological suppression.

Three- vs four-drug antiretroviral regimens for the initial treatment of HIV-1 infection: a randomized controlled trial

CONTEXT

Three-drug antiretroviral regimens are standard of care for initial treatment of human immunodeficiency virus 1 (HIV-1) infection, but a 4-drug regimen could improve antiretroviral activity and be more effective than a 3-drug regimen.

OBJECTIVE

To compare the safety/efficacy of 3-drug vs 4-drug regimens for initial treatment of HIV-1 infection.

DESIGN

The AIDS Clinical Trials Group (ACTG) A5095 study, a randomized, double-blind, placebo-controlled study with enrollment and follow-up conducted from March 22, 2001, to March 1, 2005, and enrolling treatment-naive, HIV-1-infected patients with HIV-1 RNA levels of 400 copies/mL or greater from US clinical trials units of the ACTG.

INTERVENTIONS

Zidovudine/lamivudine plus efavirenz (3-drug regimen) vs zidovudine/lamivudine/abacavir plus efavirenz (4-drug regimen).

MAIN OUTCOME MEASURES

Time to virologic failure (defined as time to first of 2 successive HIV-1 RNA levels > or =200 copies/mL at or after week 16), CD4 cell count changes, and grade 3 or 4 adverse events. HIV-1 RNA data were intent-to-treat, regardless of treatment changes.

RESULTS

Seven hundred sixty-five patients with a baseline mean HIV-1 RNA level of 4.86 log10 (72,444) copies/mL and CD4 cell count of 240 cells/mm3 were randomized. After a median 3-year follow-up, 99 (26%) of 382 and 94 (25%) of 383 patients receiving the 3-drug and 4-drug regimens, respectively, reached protocol-defined virologic failure; time to virologic failure was not significantly different (hazard ratio, 0.95; 97.5% confidence interval, 0.69-1.33; P = .73). In planned subgroup analyses, increased risk for virologic failure was seen in non-Hispanic black patients (adjusted hazard ratio, 1.66; 95% confidence interval, 1.18-2.34; P = .003). At 3 years, the HIV-1 RNA level was less than 200 copies/mL in 152 (90%) of 169 and 143 (92%) of 156 patients receiving the 3-drug and 4-drug regimens, respectively (P = .59), and less than 50 copies/mL in 144 (85%) of 169 and 137 (88%) of 156 patients (P = .39). CD4 cell count increases and grade 3 or 4 adverse events were not significantly different.

CONCLUSIONS

In treatment-naive patients, there were no significant differences between the 3-drug and 4-drug antiretroviral regimens; overall, at least approximately 80% of patients had HIV-1 RNA levels less than 50 copies/mL through 3 years. These results support current guidelines recommending 2 nucleosides plus efavirenz for initial treatment of HIV-1 infection; adding abacavir as a fourth drug provided no additional benefit.

CLINICAL TRIALS REGISTRATION

clinicaltrials.gov Identifier: NCT00013520.

The KLEAN study of fosamprenavir-ritonavir versus lopinavir-ritonavir, each in combination with abacavir-lamivudine, for initial treatment of HIV infection over 48 weeks: a randomised non-inferiority trial

BACKGROUND

Lopinavir-ritonavir is a preferred protease inhibitor co-formulation for initial HIV-1 treatment. Fosamprenavir-ritonavir has shown similar efficacy and safety to lopinavir-ritonavir when each is combined with two nucleoside reverse transcriptase inhibitors. We compared the two treatments directly in antiretroviral-naive patients.

METHODS

This open-label, non-inferiority study included 878 antiretroviral-naive, HIV-1-infected patients randomised to receive either fosamprenavir-ritonavir 700 mg/100 mg twice daily or lopinavir-ritonavir 400 mg/100 mg twice daily, each with the co-formulation of abacavir-lamivudine 600 mg/300 mg once daily. Primary endpoints were proportion of patients achieving HIV-1 RNA less than 400 copies per mL at week 48 and treatment discontinuations because of an adverse event. The intent-to-treat analysis included all patients exposed to at least one dose of randomised study medication. This study is registered with ClinicalTrials.gov, number NCT00085943.

FINDINGS

At week 48, non-inferiority of fosamprenavir-ritonavir to lopinavir-ritonavir (95% CI around the treatment difference -4.84 to 7.05) was shown, with 315 of 434 (73%) patients in the fosamprenavir-ritonavir group and 317 of 444 (71%) in the lopinavir-ritonavir group achieving HIV-1 RNA less than 400 copies per mL. Treatment discontinuations due to an adverse event were few and occurred with similar frequency in the two treatment groups (fosamprenavir-ritonavir 53, 12%; lopinavir-ritonavir 43, 10%). Diarrhoea, nausea, and abacavir hypersensitivity were the most frequent drug-related grade 2-4 adverse events. Treatment-emergent drug resistance was rare; no patient had virus that developed reduced susceptibility to fosamprenavir-ritonavir or lopinavir-ritonavir.

INTERPRETATION

Fosamprenavir-ritonavir twice daily in treatment-naive patients provides similar antiviral efficacy, safety, tolerability, and emergence of resistance as lopinavir-ritonavir, each in combination with abacavir-lamivudine.

Adherence and acceptability of once daily Lamivudine and abacavir in human immunodeficiency virus type-1 infected children

BACKGROUND

Data on adherence to and acceptability of once daily lamivudine and abacavir are few.

METHODS

Twenty-four U.K. human immunodeficiency virus type-1 infected children 2-13 years of age participated in the Pediatric European Network for the Treatment of AIDS (PENTA) 13 single arm, open label pharmacokinetic study of twice (every 12 hours) versus once (every 24 hours) daily lamivudine and abacavir. Caregivers were asked to complete an adherence questionnaire at screening, week 0 (switch once daily to twice daily) and weeks 4, 12 and 24. Acceptability was also assessed at screening and week 24.

RESULTS

Fifteen children were taking lamivudine and abacavir as part of their regimens, 8 lamivudine only and 1 abacavir only. After switching to lamivudine/abacavir every 24 hours, 7 (29%) received once daily regimens for all drugs. Twenty-three (96%) caregivers thought that switching to once daily lamivudine/abacavir would make things a lot/a little easier for their child: 17 (71%) thought it was actually easier after switching. Six mothers with children taking a mixture of twice/once daily drugs changed their mind, whereas all mothers of children on once daily regimens agreed that it was a lot easier. Nonadherence (missing doses in the last 3 days) was reported for 8 of 118 (7%) completed questionnaires; missed doses were reported for every drug in the regimen with reasons such as "not at home," "forgot" or "routine different from normal." However, viral loads in all these children remained <100 copies/mL.

CONCLUSION

Adherence to once daily abacavir/lamivudine was good with no evidence of an association between nonadherence and virologic rebound. Acceptability of once daily drugs was best when the whole regimen was dosed once daily.

Efficacy and safety of a once-daily fixed-dose combination of abacavir/lamivudine compared with abacavir twice daily and lamivudine once daily as separate entities in antiretroviral-experienced HIV-1-infected patients (CAL30001 Study)

BACKGROUND

A one-tablet, once-daily abacavir/lamivudine fixed-dose combination (FDC) has been recently approved to treat HIV-1 infection.

METHODS

A randomized, open-label, parallel-group, multicenter study to compare the efficacy and safety of the FDC group to the separate entities (SE) group, in combination with tenofovir and a new protease inhibitor or nonnucleoside reverse transcription inhibitor in antiretroviral-experienced adults experiencing virologic failure (VF). Eligible subjects had viral loads >1000 copies/mL with < or =3 nucleoside reverse transcription inhibitor-associated mutations. The primary efficacy end point was time-average changed from baseline (average area under the curve minus baseline) in plasma HIV-1 RNA over 48 weeks.

RESULTS

A total of 186 subjects were enrolled. The average area under the curve minus baseline was -1.65 and -1.83 log10 copies/mL in the FDC and SE groups, respectively (intention to treat; 95% confidence interval: -0.13, 0.38). Patients in the FDC (50%) and SE groups (47%) achieved viral loads <50 copies/mL based on the time to loss of virologic response algorithm. VF was low and similar in both groups (FDC, 16%; SE, 18%). Tolerability was similar between the 2 groups.

CONCLUSIONS

The FDC group had noninferior efficacy over 48 weeks to the SE group in treatment-experienced subjects with VF.