Ritonavir-Boosted Tipranavir Demonstrates Superior Efficacy to Ritonavir-Boosted Protease Inhibitors in Treatment-Experienced HIV-Infected Patients: 24-Week Results of the RESIST-2 Trial

A systematic review and meta-analysis assessing antiretroviral therapy for treatment-experienced HIV adult patients using an optimized background therapy approach: is there evidence enough for a standardized third-line strategy?

BACKGROUND

The World Health Organization (WHO) has identified the need for evidence on third-line antiretroviral therapy (ART) for adults living with HIV/AIDS, given that some controversy remains as to the best combinations of ART for experienced HIV-1-infected patients. Therefore, we conducted a systematic review and meta-analysis to (i) assess the efficacy of third-line therapy for adults with HIV/AIDS based on randomized controlled trials (RCT) that adopted the "new antiretroviral (ARV) + optimized background therapy (OBT)" approach and (ii) address the key issues identified in WHO's guidelines on the use of third-line therapy.

METHODS

MEDLINE, EMBASE, LILACS, ISI Web of Science, SCOPUS, and Cochrane Central Register of Controlled Trials were searched for RCTs assessing third-line ARV therapy that used an OBT approach between 1966 and 2015. Data was extracted using an Excel-structured datasheet based on the Consolidated Standards of Reporting Trials (CONSORT) recommendations. The primary outcome of this meta-analysis was the proportion of patients reaching undetectable HIV RNA levels (< 50 copies/mL) at 48 weeks of follow-up. Included studies were evaluated using the Cochrane's Risk of Bias assessment tool. Summarized evidence was rated according to the GRADE approach.

RESULTS

Eighteen trials assessing 9 new ARV + OBT combinations defined as third-line HIV therapy provided the efficacy data: 7 phase IIb trials and 11 phase III trials. Four of the 18 trials provided extension data, thus resulting in 14 trials providing 48-week efficacy data. In the meta-analysis, considering the outcome regarding the proportion of patients with a viral load below 50 copies/ml at 48 weeks, 9 out of 14 trials demonstrated the superiority of the new combination being studied (risk difference = 0.18, 95% CI 0.13-0.23). The same analysis stratified by the number of fully active ARVs demonstrated a risk difference of 0.29 (95% CI 0.12-0.46), 0.28 (95% CI 0.17-0.38) and 0.17 (95% CI 0.10-0.24) respectively from zero, one, and two or more active drugs strata. Nine of the 18 trials were considered to have a high risk of bias.

CONCLUSIONS

Efficacy results demonstrated that the groups of HIV-experienced patients receiving the new ARV + OBT were more likely to achieve viral suppression when compared to the control groups. However, most of these trials may be at a high risk of bias. Thus, there is still not enough evidence to stipulate which combinations are the most effective for therapeutic regimens that are to be used sequentially due to documented multi-resistance.

Evaluating fostemsavir as a therapeutic option for patients with HIV

ABSTRACIntroduction: Despite the unquestionable success of antiretroviral therapy achieved in recent years, there are still cases of heavily treated patients who do not achieve or struggle to maintain undetectable HIV-RNA due to drug resistance. New antiretroviral options are needed to address this issue.Area covered: The authors first provide an overview of fostemsavir and its role in the treatment of HTE PLWH. Data from pre-clinical and clinical studies are reviewed and the pharmacokinetic and farmacodynamic properties are highlited. Drug-drug interactions and safety data from available clinical studies are also discussed.Expert opinion: Fostemsavir is a promising antiretroviral belonging to the class of entry inhibitors; its novel mechanism of action represents a very important innovation. Its use will be limited to the heavy-treatment-experienced patient population. This use will have to be monitored to avoid abuse and waste of a molecule that for some patients may represent a life-saving drug.

Management of Virologic Failure and HIV Drug Resistance

Approximately 20% of people with HIV in the United States prescribed antiretroviral therapy are not virally suppressed. Thus, optimal management of virologic failure has a critical role in the ability to improve viral suppression rates to improve long-term health outcomes for those infected and to achieve epidemic control. This article discusses the causes of virologic failure, the use of resistance testing to guide management after failure, interpretation and relevance of HIV drug resistance patterns, considerations for selection of second-line and salvage therapies, and management of virologic failure in special populations.

An Update on Adverse Cutaneous Drug Reactions in HIV/AIDS

Background

The global mortality from HIV and the cutaneous burden of infective, inflammatory and malignant diseases in the setting of AIDS have significantly declined following the advent of highly active antiretroviral therapy. Regrettably, there has been a contemporaneous escalation in the incidence of adverse cutaneous drug reactions (ACDR), with studies attesting that HIV-positive individuals are a hundred times more susceptible to drug reactions than the general population, and advanced immunodeficiency portending an even greater risk. Several variables are accountable for this amplified risk in HIV.

Summary

Adverse reactions to trimethoprim-sulfamethoxazole are the most common, increasing from approximately 2–8% in the general population over to 43% amongst HIV-positive individuals to approximately 69% in subjects with AIDS. Antituberculosis drugs and antiretrovirals are also well-known instigators of ACDR. Cutaneous reactions range from mild morbilliform eruptions to severe, life-threatening manifestations in the form of Stevens-Johnson syndrome/toxic epidermal necrolysis. Histological features vary from vacuolar interface changes to full-thickness epidermal necrosis with subepidermal blister formation. A precipitous diagnosis of the ACDR, clinically and histologically if necessary, together with the isolation of the causative drug is critical. The identification process, however, is often complex and multifaceted due to polypharmacy and inconclusive data on which drugs are the most likely offending agents, especially against the background of tuberculosis co-infection.

Key Messages

Whilst milder cutaneous reactions are treated symptomatically, severe reactions mandate immediate treatment discontinuation without rechallenge. Further studies are required to establish safe rechallenge guidelines in resource-limited settings with a high HIV and tuberculosis prevalence.

Mapping MOS-HIV to HUI3 and EQ-5D-3L in Patients With HIV

Objectives: The Medical Outcomes Study HIV Health Survey (MOS-HIV) is frequently used in HIV clinical trials; however, scores generated from the MOS-HIV are not suited for cost-effectiveness analyses as they do not assign utility values to health states. Our objective was to estimate and externally validate several mapping algorithms to predict Health Utilities Index Mark 3 (HUI3) and EQ-5D-3L utility values from the MOS-HIV. Methods: We developed and validated mapping algorithms using data from two HIV clinical trials. Data from the first trial (n = 367) formed the estimation data set for the HUI3 (4,610 observations) and EQ-5D-3L (4,662 observations) mapping algorithms; data from the second trial (n = 168) formed the HUI3 (1,135 observations) and EQ-5D-3L (1,152 observations) external validation data set. We compared ordinary least squares (OLS) models of increasing complexity with the more flexible two-part, beta regression, and finite mixture models. We assessed model performance using mean absolute error (MAE) and mean squared error (MSE). Results: The OLS model that used MOS-HIV dimension scores along with squared terms gave the best HUI3 predictions (mean observed 0.84; mean predicted 0.80; MAE 0.0961); the finite mixture model gave the best EQ-5D-3L predictions (mean observed 0.90; mean predicted 0.88; MAE 0.0567). All models produced higher prediction errors at the lower end of the HUI3 and EQ-5D-3L score ranges (<0.40). Conclusions: The proposed mapping algorithms can be used to predict HUI3 and EQ-5D-3L utility values from the MOS-HIV, although greater error may pose a problem in samples where a substantial proportion of patients are in poor health. These algorithms may be useful for estimating utility values from the MOS-HIV for cost-effectiveness studies when HUI3 or EQ-5D-3L data are not available.

Tipranavir/Ritonavir (500/200 mg and 500/100 mg) Was Virologically Non-Inferior to Lopinavir/Ritonavir (400/100 mg) at Week 48 in Treatment-Naïve HIV-1-Infected Patients: A Randomized, Multinational, Multicenter Trial

Ritonavir-boosted tipranavir (TPV/r) was evaluated as initial therapy in treatment-naïve HIV-1-infected patients because of its potency, unique resistance profile, and high genetic barrier. Trial 1182.33, an open-label, randomized trial, compared two TPV/r dose combinations versus ritonavir-boosted lopinavir (LPV/r). Eligible adults, who had no prior antiretroviral therapy were randomized to twice daily (BID) 500/100 mg TPV/r, 500/200 mg TPV/r, or 400/100 mg LPV/r. Each treatment group also received Tenofovir 300 mg + Lamivudine 300 mg QD. The primary endpoint was a confirmed viral load (VL) <50 copies/mL at week 48 without prior antiretroviral regimen changes. Primary analyses examined CD4-adjusted response rates for non-inferiority, using a 15% non-inferiority margin. At week 48, VL<50 copies/mL was 68.4%, 69.9%, and 72.4% in TPV/r100, TPV/r200, and LPV/r groups, respectively, and TPV/r groups showed non-inferiority to LPV/r. Discontinuation due to adverse events was higher in TPV/r100 (10.3%) and TPV/r200 (15.3%) recipients versus LPV/r (3.2%) recipients. The frequency of grade ≥3 transaminase elevations was higher in the TPV/r200 group than the other groups, leading to closure of this group. However, upon continued treatment or following re-introduction after treatment interruption, transaminase elevations returned to grade ≤2 in >65% of patients receiving either TPV/r200 or TPV/r100. The trial was subsequently discontinued; primary objectives were achieved and continuing TPV/r100 was less tolerable than standard of care for initial highly active antiretroviral therapy. All treatment groups had similar 48-week treatment responses. TPV/r100 and TPV/r200 regimens resulted in sustained treatment responses, which were non-inferior to LPV/r at 48 weeks. When compared with the LPV/r regimen and examined in the light of more current regimens, these TPV/r regimens do not appear to be the best options for treatment-naïve patients based on their safety profiles.

Regimen selection in the OPTIONS trial of HIV salvage therapy: drug resistance, prior therapy, and race-ethnicity determine the degree of regimen complexity

BACKGROUND

Regimen selection for highly treatment-experienced patients is complicated.

METHODS

Using a web-based utility, study team members reviewed antiretroviral (ARV) history and resistance data and recommended individual ARV regimens and nucleoside reverse transcriptase inhibitor (NRTI) options for treatment-experienced participants consisting of 3-4 of the following agents: raltegravir (RAL), darunavir (DRV)/ritonavir, tipranavir (TPV)/ritonavir, etravirine (ETR), maraviroc (MVC), and enfuvirtide (ENF). We evaluated team recommendations and site selection of regimen and NRTIs. Associations between baseline factors and the selection of a complex regimen (defined as including four ARV agents or ENF) were explored with logistic regression.

RESULTS

A total of 413 participants entered the study. Participants initiated the first or second recommended regimen 86% of the time and 21% of participants started a complex regimen. In a multivariable model, ARV resistance to NRTI (odds ratio [OR] = 2.2), non-nucleoside reverse transcriptase inhibitor (NNRTI, OR = 6.2) or boosted protease inhibitor (PI, OR = 6.6), prior use of integrase strand transfer inhibitor (INSTI, OR = 25), and race-ethnicity (all P ≤ 0.01) were associated with selection of a complex regimen. Black non-Hispanic (OR = 0.5) and Hispanic participants from the continental US (OR = 0.2) were less likely to start a complex regimen, compared to white non-Hispanics.

CONCLUSIONS

In this multi-center trial, we developed a web-based utility that facilitated treatment recommendations for highly treatment-experienced patients. Drug resistance, prior INSTI use, and race-ethnicity were key factors in decisions to select a more complex regimen.

Use of new antiretroviral drugs and classes in Bahia, Brazil: a real life experience on salvage therapy of AIDS patients

Antiretroviral therapy has significantly evolved in the last decade, with an increasing number of new drugs and classes. Currently, even heavily experienced patients can be successfully treated with new regimens. In Brazil, the recent incorporation of some new antiretroviral drugs made it possible to suppress HIV plasma viremia in most treated patients, with significant benefits in terms of quality of life and survival. However, little has been published on outcomes of patients under new drugs-based regimens. We reviewed the safety and efficacy of antiretroviral regimens using recently introduced drugs in Bahia. Our results confirm that patients using darunavir, raltegravir, enfuvirtide, or etravirine presented with a high rate of virological suppression without significant adverse events, after one year of follow-up.

Cost-effectiveness of newer antiretroviral drugs in treatment-experienced patients with multidrug-resistant HIV disease

OBJECTIVE

Newer antiretroviral drugs provide substantial benefits but are expensive. The cost-effectiveness of using antiretroviral drugs in combination for patients with multidrug-resistant HIV disease was determined.

DESIGN

A cohort state-transition model was built representing treatment-experienced patients with low CD4 counts, high viral load levels, and multidrug-resistant virus. The effectiveness of newer drugs (those approved in 2005 or later) was estimated from published randomized trials. Other parameters were estimated from a randomized trial and from the literature. The model had a lifetime time horizon and used the perspective of an ideal insurer in the United States. The interventions were combination antiretroviral therapy, consisting of 2 newer drugs and 1 conventional drug, compared with 3 conventional drugs. Outcome measures were life-years, quality-adjusted life-years (QALYs), costs, and incremental cost-effectiveness.

RESULTS

Substituting newer antiretroviral drugs increased expected survival by 3.9 years in advanced HIV disease. The incremental cost-effectiveness ratio of newer, compared with conventional, antiretroviral drugs was $75,556/QALY gained. Sensitivity analyses showed that substituting only one newer antiretroviral drug cost $54,559 to $68,732/QALY, depending on assumptions about efficacy. Substituting 3 newer drugs cost $105,956 to $117,477/QALY. Cost-effectiveness ratios were higher if conventional drugs were not discontinued.

CONCLUSIONS

In treatment-experienced patients with advanced HIV disease, use of newer antiretroviral agents can be cost-effective, given a cost-effectiveness threshold in the range of $50,000 to $75,000 per QALY gained. Newer antiretroviral agents should be used in carefully selected patients for whom less expensive options are clearly inferior.

Virologic response to tipranavir-ritonavir or darunavir-ritonavir based regimens in antiretroviral therapy experienced HIV-1 patients: a meta-analysis and meta-regression of randomized controlled clinical trials

BACKGROUND

The development of tipranavir and darunavir, second generation non-peptidic HIV protease inhibitors, with marked improved resistance profiles, has opened a new perspective on the treatment of antiretroviral therapy (ART) experienced HIV patients with poor viral load control. The aim of this study was to determine the virologic response in ART experienced patients to tipranavir-ritonavir and darunavir-ritonavir based regimens.

METHODS AND FINDINGS

A computer based literature search was conducted in the databases of HINARI (Health InterNetwork Access to Research Initiative), Medline and Cochrane library. Meta-analysis was performed by including randomized controlled studies that were conducted in ART experienced patients with plasma viral load above 1,000 copies HIV RNA/ml. The odds ratios and 95% confidence intervals (CI) for viral loads of <50 copies and <400 copies HIV RNA/ml at the end of the intervention were determined by the random effects model. Meta-regression, sensitivity analysis and funnel plots were done. The number of HIV-1 patients who were on either a tipranavir-ritonavir or darunavir-ritonavir based regimen and achieved viral load less than 50 copies HIV RNA/ml was significantly higher (overall OR = 3.4; 95% CI, 2.61-4.52) than the number of HIV-1 patients who were on investigator selected boosted comparator HIV-1 protease inhibitors (CPIs-ritonavir). Similarly, the number of patients with viral load less than 400 copies HIV RNA/ml was significantly higher in either the tipranavir-ritonavir or darunavir-ritonavir based regimen treated group (overall OR = 3.0; 95% CI, 2.15-4.11). Meta-regression showed that the viral load reduction was independent of baseline viral load, baseline CD4 count and duration of tipranavir-ritonavir or darunavir-ritonavir based regimen.

CONCLUSIONS

Tipranavir and darunavir based regimens were more effective in patients who were ART experienced and had poor viral load control. Further studies are required to determine their consistent viral load suppression effect as the duration of treatment is more prolonged.

Closing the door to human immunodeficiency virus

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

Differences in implementation of HIV/AIDS clinical research in developed versus developing world: an evidence-based review on protease inhibitor use among women and minorities

The aim of this revision is to evaluate ethnicity and gender rate of enrolment in registrative clinical trials of the protease inhibitors (Pis) from 1996 to 2009. Company-sponsored, phase II or III registrative clinical trials of PIs were evaluated. Forty-nine clinical trials were included. Clinical trials were conducted in centres in North America ( n = 39), Central-South America ( n = 22), Europe ( n = 22), Africa ( n = 8), Asia ( n = 5), Australia ( n = 10). Overall mean age was 39.6 years; median proportion of women was 16.3%. The most represented ethnic group was Caucasian. A test for trend over time (1996-2009) shows a significant increase in the proportion of women included ( P = 0.012), and a decrease in the proportion of Caucasians included, reaching borderline significance ( P = 0.061). An inverse correlation was observed between the proportion of Caucasians and that of women enrolled in each study ( r = 0.65, P < 0.0001). Women were less likely to be included in double-blind studies (11.2% versus 17%, P = 0.019). Clinical trials for treatment-naive subjects were more likely to enrol ethnicities other than Caucasian compared with Caucasian (44.7% versus 27.1 %, respectively, P = 0.04). Rates of enrolment of minorities in registrative clinical trials for PIs show a positive trend since 1996, mirroring the growing number of people of different ethnic groups accessing ART.

Metabolism of novel anti-HIV agent 3-cyanomethyl-4-methyl-DCK by human liver microsomes and recombinant CYP enzymes

AIM

To investigate the metabolism of 3-cyanomethyl-4-methyl-DCK (CMDCK), a novel anti-HIV agent, by human liver microsomes (HLMs) and recombinant cytochrome P450 enzymes (CYPs).

METHODS

CMDCK was incubated with HLMs or a panel of recombinant cytochrome P450 enzymes including CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6, 3A4, and 3A5. LC-ion trap mass spectrometry was used to separate and identify CMDCK metabolites. In the experiments with recombinant cytochrome P450 enzymes, specific chemical inhibitors combined with CYP antibodies were used to identify the CYP isoforms involved in CMDCK metabolism.

RESULTS

CMDCK was rapidly and extensively metabolized by HLMs. Its intrinsic hepatic clearance estimated from the in vitro data was 19.4 mL·min(-1)·kg(-1), which was comparable to the mean human hepatic blood flow rate (20.7 mL·min(-1)·kg(-1)). The major metabolic pathway of CMDCK was oxidation, and a total of 14 metabolites were detected. CYP3A4 and 3A5 were found to be the principal CYP enzymes responsible for CMDCK metabolism.

CONCLUSION

CMDCK was metabolized rapidly and extensively in human hepatic microsomes to form a number of oxidative metabolites. CYP3A4 and 3A5 were the predominant enzymes responsible for the oxidation of CMDCK.

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

PURPOSE

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

DESIGN

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Effect of tipranavir/ritonavir combination on the pharmacokinetics of tadalafil in healthy volunteers

This study evaluated the effects of single-dose administration and steady-state concentrations of tipranavir 500 mg and ritonavir 200 mg (TPV/r) combination on the pharmacokinetics of tadalafil 10 mg (TAD) in an open-label study. Seventeen healthy male volunteers received sequential dosing of the studied product: TAD (day 1) alone in a single dose for 7 days followed by TAD (day 8) in a single dose with TPV/r (500/200 mg twice daily, days 8-18). Pharmacokinetic parameters were determined in a noncompartmental analysis. The geometric mean ratio and 90% confidence interval were used to evaluate drug interactions. The effect of a single dose of TAD on the pharmacokinetics of TPV/r resulted in a small decrease in exposure after either first-dose or steady-state TPV/r (geometric mean ratios [90% confidence interval]: area under the concentration-time curve, 0.85 [0.74-0.97]). In contrast, coadministration of TAD exposure was increased significantly (2.33 [2.02-2.69]) when administered with the first dose of TPV/r but not when TPV/r steady state was reached (1.01 [0.83-1.21]). Antiretroviral activity may not be reduced, but the dose of TAD should be reduced at the start of TPV/r therapy and then a full dose can be resumed after steady state is reached.

The benefit of simplification from tipranavir/ritonavir 500/200 bid to 500/100 bid guided by therapeutic drug monitoring

Despite being among the most potent protease inhibitors, the use of tipranavir (TPV) is hampered by a high pill burden and frequent side effects compared with other boosted protease inhibitors. A total of 10 patients receiving TPV/ritonavir (TPV/RTV) 500/200 for longer than 6 months were randomized to stay on the same dosing schedule or switch to TPV/RTV 500/100. Although all patients on TVP/RTV 500/200 remained stable for the next 12 weeks, 3 out of 5 patients who switched doses experienced benefits in terms of reducing aminotransferases and total cholesterol. Fasting triglycerides were also reduced in 2 of them. Plasma HIV-RNA remained undetectable in all patients, despite the observed decline in TPV trough concentrations.

Metabolism-mediated drug interactions associated with ritonavir-boosted tipranavir in mice

Tipranavir (TPV) is the first nonpeptidic protease inhibitor used for the treatment of drug-resistant HIV infection. Clinically, TPV is coadministered with ritonavir (RTV) to boost blood concentrations and increase therapeutic efficacy. The mechanism of metabolism-mediated drug interactions associated with RTV-boosted TPV is not fully understood. In the current study, TPV metabolism was investigated in mice using a metabolomic approach. TPV and its metabolites were found in the feces of mice but not in the urine. Principal component analysis of the feces metabolome uncovered eight TPV metabolites, including three monohydroxylated, three desaturated, one dealkylated, and one dihydroxylated. In vitro study using human liver microsomes recapitulated five TPV metabolites, all of which were suppressed by RTV. CYP3A4 was identified as the primary enzyme contributing to the formation of four TPV metabolites (metabolites II, IV, V, and VI), including an unusual dealkylated product arising from carbon-carbon bond cleavage. Multiple cytochromes P450 (2C19, 2D6, and 3A4) contributed to the formation of a monohydroxylated metabolite (metabolite III). In vivo, RTV cotreatment significantly inhibited eight TPV metabolic pathways. In summary, metabolomic analysis revealed two known and six novel TPV metabolites in mice, all of which were suppressed by RTV. The current study provides solid evidence that the RTV-mediated boosting of TPV is due to the modulation of P450-dependent metabolism.

Costs to achieve undetectable HIV RNA with darunavir-containing highly active antiretroviral therapy in highly pretreated patients: the POWER experience

BACKGROUND

Very few studies have evaluated the cost of highly active antiretroviral therapy (HAART) per successful treatment in HIV-infected patients.

OBJECTIVES

To evaluate the cost of achieving undetectable plasma HIV-RNA levels in highly treatment-experienced, HIV-1-infected adults receiving darunavir/ritonavir (DRV/r 600 mg/100 mg twice a day) or control protease inhibitor (PI)-based HAART.

METHODS

The mean annual per-patient cost of DRV/r and control PI-based HAART was determined from the proportional use of antiretroviral agents in the DRV/r and control PI arms of the pooled POWER 1 and 2 trials, applying drug acquisition costs for 13 healthcare settings. The mean annual cost per patient of achieving undetectable plasma HIV-RNA levels (<50 copies/mL) was calculated by dividing the cost of each treatment by the proportion of patients with undetectable plasma HIV-RNA levels after 48 weeks in the DRV/r (45%) and control PI (10%) arms of the POWER trials.

RESULTS

Whereas absolute costs of treatment were 1-19% higher with DRV/r versus control PI-based HAART depending on the healthcare setting, the mean annual per-patient cost of achieving undetectable plasma HIV-RNA levels was 73-78% lower. These cost savings were maintained in the sensitivity analyses, adjusting for control PI and enfuvirtide use, and the number of active drugs in the background regimen. The incremental annual cost per additional patient achieving undetectable plasma HIV-RNA levels with DRV/r versus control PI-based HAART in POWER 1 and 2 (£4148) compared favourably with that determined for enfuvirtide (£137, 740; TORO trials) and tipranavir/ritonavir (£32,176; RESIST) versus control therapy.

CONCLUSIONS

DRV/r-based HAART provided consistent reductions in the cost of achieving undetectable plasma HIV-RNA levels compared with control PI-based therapy in highly treatment-experienced patients across various healthcare settings. The incremental cost per additional patient achieving undetectable plasma HIV-RNA levels with DRV/r versus control PI-based HAART was also lower than that calculated for other treatment options in this population. These results suggest that DRV/r is an economically viable option for highly treatment-experienced patients.

Pharmacologic characteristics of investigational and recently approved agents for the treatment of HIV

PURPOSE OF REVIEW

Two agents from antiretroviral classes with novel mechanisms of action against HIV received regulatory approval in 2007. Maraviroc is the first in the class of chemokine coreceptor 5 antagonists and raltegravir is the first in the class of integrase inhibitors. There are other compounds in these two new classes in later stages of clinical development, as well as several protease inhibitors and nonnucleoside reverse transcriptase inhibitors that have been recently approved or are under investigation for use in treatment-experienced patients. The purpose of this article is to review the pharmacologic characteristics of these newly approved and investigational antiretroviral drugs, with particular emphasis on data presented or published within the past year.

RECENT FINDINGS

Several pivotal studies describing the efficacy, safety, and pharmacologic properties of maraviroc, vicriviroc, etravirine, rilpivirine, raltegravir, elvitegravir, darunavir/ritonavir, and tipranavir/ritonavir have begun to emerge.

SUMMARY

To date, these agents have demonstrated promising virologic activity with primarily excellent tolerability, but there is still much to learn about their pharmacology. Future studies should evaluate their potential for drug-drug interactions and elucidate their concentration-effect relationships. An appreciation for the pharmacology of these drugs is critical to their optimal use.

Hepatic profile analyses of tipranavir in Phase II and III clinical trials

Background

The risk and course of serum transaminase elevations (TEs) and clinical hepatic serious adverse event (SAE) development in ritonavir-boosted tipranavir (TPV/r) 500/200 mg BID recipients, who also received additional combination antiretroviral treatment agents in clinical trials (TPV/r-based cART), was determined.

Methods

Aggregated transaminase and hepatic SAE data through 96 weeks of TPV/r-based cART from five Phase IIb/III trials were analyzed. Patients were categorized by the presence or absence of underlying liver disease (+LD or -LD). Kaplan-Meier (K-M) probability estimates for time-to-first US National Institutes of Health, Division of AIDS (DAIDS) Grade 3/4 TE and clinical hepatic SAE were determined and clinical actions/outcomes evaluated. Risk factors for DAIDS Grade 3/4 TE were identified through multivariate Cox regression statistical modeling.

Results

Grade 3/4 TEs occurred in 144/1299 (11.1%) patients; 123/144 (85%) of these were asymptomatic; 84% of these patients only temporarily interrupted treatment or continued, with transaminase levels returning to Grade ≤ 2. At 96 weeks of study treatment, the incidence of Grade 3/4 TEs was higher among the +LD (16.8%) than among the -LD (10.1%) patients. K-M analysis revealed an incremental risk for developing DAIDS Grade 3/4 TEs; risk was greatest through 24 weeks (6.1%), and decreasing thereafter (>24-48 weeks: 3.4%, >48 weeks-72 weeks: 2.0%, >72-96 weeks: 2.2%), and higher in +LD than -LD patients at each 24-week interval. Treatment with TPV/r, co-infection with hepatitis B and/or C, DAIDS grade >1 TE and CD4⁺ > 200 cells/mm³ at baseline were found to be independent risk factors for development of DAIDS Grade 3/4 TE; the hazard ratios (HR) were 2.8, 2.0, 2.1 and 1.5, respectively. Four of the 144 (2.7%) patients with Grade 3/4 TEs developed hepatic SAEs; overall, 14/1299 (1.1%) patients had hepatic SAEs including six with hepatic failure (0.5%). The K-M risk of developing hepatic SAEs through 96 weeks was 1.4%; highest risk was observed during the first 24 weeks and decreased thereafter; the risk was similar between +LD and -LD patients for the first 24 weeks (0.6% and 0.5%, respectively) and was higher for +LD patients, thereafter.

Conclusion

Through 96 weeks of TPV/r-based cART, DAIDS Grade 3/4 TEs and hepatic SAEs occurred in approximately 11% and 1% of TPV/r patients, respectively; most (84%) had no significant clinical implications and were managed without permanent treatment discontinuation. Among the 14 patients with hepatic SAE, 6 experienced hepatic failure (0.5%); these patients had profound immunosuppression and the rate appears higher among hepatitis co-infected patients. The overall probability of experiencing a hepatic SAE in this patient cohort was 1.4% through 96 weeks of treatment. Independent risk factors for DAIDS Grade 3/4 TEs include TPV/r treatment, co-infection with hepatitis B and/or C, DAIDS grade >1 TE and CD4⁺ > 200 cells/mm³ at baseline.

Trial registration

US-NIH Trial registration number: NCT00144170

Effective treatment of patients in a deep salvage situation with "non-active HAART": experiences with the expert advice system RADATA

BACKGROUND

Clinical studies suggest expert recommendations as a possibility to optimize highly active antiretroviral therapy (HAART) in patients with multi-drug resistant virus strains. An online system (RADATA) has been developed to provide expert advice for the drug therapy of HIV-infected patients.

OBJECTIVE

To evaluate the efficacy of expert-advice-guided HAART switches in patients with triple-class failure.

METHODS

Virological and immunological outcome of patients having undergone at least three prior ART regimens, including nucleoside inhibitor (NRTI), nonnucleoside reverse transcriptase inhibitor (NNRTI), and protease inhibitor (PI) use, were analyzed. Changes in HIV-RNA and CD4-cell count were evaluated every 3 months.

RESULTS

183 patients with a median baseline viral load of 3.90 log copies/ml (1.88-6.54 log) and a CD4-cell count of 298 c/ll (5-910 c/ll) were eligible for analysis. The patients had a median of seven prior ART regimens and a treatment duration of 83 months. A median of three (range 0-8) NRTI-, two (0-7) thymidine-associated (TA), one (0-4) NNRTI-, and three (0-13) PI-associated resistance mutations were present at baseline. Despite available resistance analyses and expert recommendations, 66% (n = 119) of the patients started a new ART regimen without any active drugs according to the resistance analysis. The HIV-RNA declined by a median of 0.61 log and 0.92 log after 12 and 24 months, respectively, while the CD4-cell count rose by a median of +9 c/microl and +25 c/microl during this period. No significant differences related to number of prior regimens or number of active substances used could be found.

CONCLUSION

Despite extensive pre-treatment and multiple resistances against prescribed HAART, our patients demonstrated a decline in viral load and a stable CD4-cell count over the observation period. We conclude that the activity of antiretroviral regimens is not exclusively explained by the current algorithms used for estimating antiretroviral drug activity.

Comparison of the pharmacokinetics of apricitabine in the presence and absence of ritonavir-boosted tipranavir: a phase I, open-label, controlled, single-centre study

BACKGROUND AND OBJECTIVE

Apricitabine is a deoxycytidine analogue nucleoside reverse transcriptase inhibitor for the treatment of HIV infection. The aim of this phase I study was to investigate whether administration of apricitabine with the HIV protease inhibitor tipranavir (ritonavir-boosted) affects the pharmacokinetic profile of apricitabine.

METHODS

This phase I study was conducted in 18 healthy adult male subjects. Subjects received a single dose of apricitabine 800 mg on the morning of day 1 followed by tipranavir 500 mg plus ritonavir 200 mg every 12 hours from day 2 to day 9 to achieve steady-state concentrations of tipranavir/ritonavir. On day 10, subjects received a single morning dose of apricitabine 800 mg and a single dose of tipranavir 500 mg plus ritonavir 200 mg. Following dosing on days 1, 9 and 10, pharmacokinetic sampling was undertaken over 12 hours post-dosing to determine the plasma concentrations of apricitabine and tipranavir.

RESULTS

The administration of a single dose of apricitabine 800 mg in the presence of steady-state tipranavir/ritonavir concentrations resulted in an increase in the apricitabine area under the plasma concentration-time curve of approximately 40% and in the apricitabine maximum plasma concentration of approximately 25% relative to apricitabine 800 mg administered alone. Apricitabine was well tolerated when administered with tipranavir/ritonavir.

CONCLUSION

A moderate increase in apricitabine exposure was seen after co-administration with ritonavir-boosted tipranavir but this increase was not of clinical significance. No adjustment of apricitabine dosing is required when administered with ritonavir-boosted tipranavir.

HIV protease inhibitors: recent clinical trials and recommendations on use

BACKGROUND

HIV protease inhibitors (PIs) are potent antiretroviral drugs that represent a pivotal component of highly active antiretroviral therapy (HAART). PIs have evolved over the years to gain in potency, convenience, tolerability and genetic barrier to resistance.

OBJECTIVE

Updated summary of evidence-based information about the efficacy and safety of PIs on initial, simplification and rescue interventions in HIV patients.

METHODS

Review of available data reported in peer-reviewed journals, medical conferences and treatment guidelines.

RESULTS

Due to their characteristics, PIs are, and will remain, a cornerstone component in most lines of antiretroviral therapy. The antiviral activity, tolerability and convenience of PIs have improved significantly in recent years. Differences between compounds within this class may favour their use in specific situations, such as the friendly metabolic profile of atazanavir in patients with cardiovascular disease or the high genetic barrier of darunavir or tipranavir in heavily pretreated individuals with HIV.

Trends in the European HIV/AIDS epidemic: a perspective from Italy

The HIV/AIDS epidemic represents one of the major public-health challenges in present days. Despite the relevant improvement in the prognosis of HIV disease following the introduction of highly active antiretroviral therapy (HAART), numerous new challenges are progressively emerging as patient characteristics evolve. In this article, we give an insight into more actual topics in the HIV/AIDS epidemic in Italy and Europe, including recent epidemiological trends, emerging drug resistance and non-B-subtype circulation, the lights and shadows of HAART and the potential of HARRT to reduce sexual transmission of HIV.

Use of different inhibitory quotients to predict early virological response to tipranavir in antiretroviral-experienced human immunodeficiency virus-infected patients

Information about the relationship between pharmacological parameters and an early virological response to tipranavir (TPV) is scarce. Human immunodeficiency virus (HIV)-infected patients who had received TPV as part of a salvage regimen were analyzed retrospectively. A virological response was defined as a decline in the HIV RNA level of > or = 1 log unit or to <50 copies/ml between weeks 4 and 12 of therapy. The virtual inhibitory quotient (vIQ) was calculated as the ratio of the TPV plasma trough concentration (C(trough))/virtual change in the 50% inhibitory concentration. Three genotypic inhibitory quotients (gIQs) were calculated by using different TPV resistance mutation scores (from the International AIDS Society-USA [IAS-USA], Randomized Evaluation of Strategic Intervention in Multidrug-Resistant Patients with Tipranavir [RESIST], and Agence Nationale de Recherches sur le Sida et les Hépatites Virales [ANRS] trials). The sensitivities, specificities, positive predictive values (PPVs), negative predictive values (NPVs), and likelihood ratios for a positive result (LHR+) and a negative result (LHR-) [LHR+ = sensitivity/(1-specificity); LHR- = (1-sensitivity)/specificity] were calculated. A total of 57 HIV-infected patients were analyzed. A virological response was achieved by 77% of the patients. TPV resistance mutations, TPV C(trough), vIQs, and gIQs were all significantly associated with a virological response. The vIQ had the best PPV and NPV (97% and 78%, respectively). The values of the LHR+ were 7.8 for vIQ, 3.4 for the RESIST gIQ, 3.3 for the IAS-USA gIQ, 3.1 for the ANRS gIQ, 2.2 for TPV C(trough), and 1.3 for the IAS-USA and RESIST scores. The values of LHR- were 0 for the RESIST score, 0.07 for vIQ, 0.09 for the IAS-USA score, 0.27 for the RESIST gIQ, 0.32 for the IAS-USA gIQ, 0.37 for the ANRS gIQ, and 0.48 for TPV C(trough). HIV-infected patients who initiate a salvage regimen based on TPV may benefit from baseline drug resistance testing and TPV plasma concentration determination, as vIQ is the best predictor of a virological response.

[Interpreting methodological and statistical considerations in studies of rescue therapy]

The methodology used in studies of rescue therapy is sometimes complex. This is because of the heterogeneity of objectives and options. Firstly, the definition of failure has multiple interpretations and subtle distinctions. Secondly, the aim of treatment in these patients has varied according to the available treatment options in each case and at each moment of time. Lastly, the methodology used to develop these studies of rescue therapy has varied over time in line with changes in their aims and options. Currently, a new change can be expected to adjust to the current situation, since the number of therapeutic options for rescue therapy has substantially increased in the last year. The present review discusses changes in the design of these studies, the main methodological issues to be taken into account and the recommendations on this subject.

HIV-related liver disease: ARV drugs, coinfection, and other risk factors

Highly-active antiretroviral therapy (HAART) has proven remarkably effective for prolonging the life of patients with human immunodeficiency virus (HIV). However, while most HAART agents are safe, many have the potential to cause liver toxicity. Physicians must therefore consider the possibility of drug-induced liver injury in the management of HIV-infected patients, especially those with certain risk factors such as coinfection with hepatitis B virus (HBV) or hepatitis C virus (HCV), female gender, alcohol abuse, older age, or obesity. Understanding how, when, and why drug-related liver damage occurs is key to managing these patients safely and effectively. Knowledge of HAART-related liver effects will help ensure that patients receive the most benefit with the least toxicity from any given drug regimen. As more information about the mechanisms of drug related liver injury is known, clinicians will be better able to tailor therapies to suit individual situations, resulting in greater patient safety and outcomes.

Viral protease inhibitors

This review provides an overview of the development of viral protease inhibitors as antiviral drugs. We concentrate on HIV-1 protease inhibitors, as these have made the most significant advances in the recent past. Thus, we discuss the biochemistry of HIV-1 protease, inhibitor development, clinical use of inhibitors, and evolution of resistance. Since many different viruses encode essential proteases, it is possible to envision the development of a potent protease inhibitor for other viruses if the processing site sequence and the catalytic mechanism are known. At this time, interest in developing inhibitors is limited to viruses that cause chronic disease, viruses that have the potential to cause large-scale epidemics, or viruses that are sufficiently ubiquitous that treating an acute infection would be beneficial even if the infection was ultimately self-limiting. Protease inhibitor development is most advanced for hepatitis C virus (HCV), and we also provide a review of HCV NS3/4A serine protease inhibitor development, including combination therapy and resistance. Finally, we discuss other viral proteases as potential drug targets, including those from Dengue virus, cytomegalovirus, rhinovirus, and coronavirus.

Tipranavir: a review of its use in the management of HIV infection

Tipranavir (Aptivus) is a selective nonpeptidic HIV-1 protease inhibitor (PI) that is used in the treatment of treatment-experienced adults with HIV-1 infection. Tipranavir is administered orally twice daily and must be given in combination with low-dose ritonavir, which is used to boost its bioavailability. The durable efficacy of tipranavir, in combination with low-dose ritonavir (tipranavir/ritonavir 500 mg/200 mg twice daily), has been demonstrated in well designed trials in treatment-experienced adults infected with multidrug-resistant strains of HIV-1. In treatment-experienced adults with HIV-1 infection receiving an optimized background regimen, viral suppression was greater and immunological responses were better with regimens containing tipranavir/ritonavir than with comparator ritonavir-boosted PI-containing regimens. The efficacy benefit appeared to be more marked in patients receiving two fully active drugs in the regimen, with the combination of tipranavir/ritonavir and enfuvirtide (for the first time) appearing to be the most successful. Although tipranavir is generally well tolerated, clinical hepatitis and hepatic decompensation, and intracranial haemorrhage have been associated with the drug. Tipranavir also has a complex drug-interaction profile. Thus, tipranavir, administered with ritonavir, is an effective treatment option for use in the combination therapy of adults with HIV-1 infection who have been previously treated with other antiretroviral drugs.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Lopinavir/ritonavir in the treatment of HIV-1 infection: a review

Lopinavir/ritonavir is the first and only coformulated HIV-1 protease inhibitor (PI). Large clinical trials have demonstrated lopinavir/ritonavir's clinical efficacy in both antiretroviral-naïve and -experienced patients. The immunologic and virologic benefits of treatment with this agent have been proven in HIV-infected adults, adolescents, and children. Smaller studies support the use of lopinavir/ritonavir monotherapy as a therapeutic option in certain patients. The drug is characterized by a high genetic barrier to resistance, and appears to be more forgiving of non-adherence than earlier, unboosted PIs. The most frequent side effects observed are diarrhea, nausea, and vomiting. These gastrointestinal adverse effects are generally mild to moderate. Metabolic derangements, including hyperlipidemia and glucose intolerance, have also been observed in lopinavir/ritonavir recipients. As the menu of available antiretroviral agents continues to expand, lopinavir/ritonavir remains a proven and effective drug for the treatment of HIV infection.

Efficacy, safety and tolerability of tipranavir coadministered with ritonavir in HIV-1-infected children and adolescents

OBJECTIVE

To evaluate the efficacy, safety and tolerability of ritonavir-boosted tipranavir (TPV/r) in HIV-1-infected pediatric patients.

DESIGN

Open-label randomized pediatric trial (1182.14/PACTG1051) comparing TPV/r at two doses including an optimized background regimen.

METHODS

HIV-1-infected patients (2-18 years) with plasma viral load 1500 copies/ml or more were randomized to TPV/r 290/115 or 375/150 mg/m twice-daily oral solution and optimized background regimen. Week 48 efficacy, safety and tolerability results were evaluated.

RESULTS

Children (n = 115; 97% treatment experienced) were randomized to low or high dose therapy. Eighty-eight remained on-treatment through 48 weeks. Baseline characteristics were similar between dose groups. At study entry, half of the HIV-1 isolates were resistant to all protease inhibitors. At 48 weeks, 39.7% low-dose and 45.6% high-dose TPV/r recipients had viral load less than 400 copies/ml and 34.5 and 35.1%, respectively, achieved viral load less than 50 copies/ml. Vomiting, cough and diarrhea were the most frequent adverse events. Grade 3 alanine aminotransferase elevations were observed in 6.3% of patients. No grade 4 alanine aminotransferase or grade 3/4 aspartate aminotransferase elevations were reported.

CONCLUSIONS

TPV/r achieved a sustained virologic response, showed a good safety profile and was well tolerated at either dose. In pediatric patients with high baseline resistance profiles, high-dose TPV/r tended to demonstrate a better sustained response.

Darunavir inhibitory quotient predicts the 48-week virological response to darunavir-based salvage therapy in human immunodeficiency virus-infected protease inhibitor-experienced patients

The aim of this study was to evaluate the relationship between the virological response to darunavir-based salvage antiretroviral therapy and the darunavir genotypic and virtual inhibitory quotients (gIQ and vIQ, respectively). Thirty-seven HIV-infected patients failing protease inhibitor-based antiretroviral regimens who started salvage therapy containing darunavir-ritonavir were prospectively studied. The primary outcome of the study was a viral load (VL) of <50 copies/ml at week 48. The trough concentrations of darunavir in plasma, the number of darunavir resistance mutations, the change in the 50% inhibitory concentration (IC(50)) of darunavir in the virtual phenotype, and the darunavir gIQ and vIQ were correlated with the virological outcome in regression analyses adjusted by the number of active drugs in the background regimen. The VL was <50 copies/ml in 56.8% of patients at week 48. Changes in the VL were not significantly associated with the darunavir concentration (P = 0.304), the number of darunavir resistance mutations (P = 0.695), or the change in the IC(50) (P = 0.750). However, patients with darunavir vIQs of >or=1.5 had a 12-fold greater chance of achieving a >or=1 log(10) reduction in the VL (odds ratio [OR], 12.7; 95% confidence interval [95% CI], 1.9 to 81.6; P = 0.007), and a 5-fold greater chance of achieving a VL of <50 copies/ml (OR, 5.4; 95% CI, 1.2 to 24.5; P = 0.028), at week 48 than patients with darunavir vIQs of <1.5. The positive and negative predictive values of this darunavir vIQ cutoff for achieving a VL of <50 copies/ml at week 48 were 70% and 69%, respectively. The darunavir vIQ predicts virological response to darunavir-based salvage therapy better than the darunavir trough concentration or resistance mutations alone. We suggest targeting a darunavir vIQ of 1.5 for achieving long-term viral suppression.

Raltegravir with optimized background therapy for resistant HIV-1 infection

BACKGROUND

Raltegravir (MK-0518) is an inhibitor of human immunodeficiency virus type 1 (HIV-1) integrase active against HIV-1 susceptible or resistant to older antiretroviral drugs.

METHODS

We conducted two identical trials in different geographic regions to evaluate the safety and efficacy of raltegravir, as compared with placebo, in combination with optimized background therapy, in patients infected with HIV-1 that has triple-class drug resistance in whom antiretroviral therapy had failed. Patients were randomly assigned to raltegravir or placebo in a 2:1 ratio.

RESULTS

In the combined studies, 699 of 703 randomized patients (462 and 237 in the raltegravir and placebo groups, respectively) received the study drug. Seventeen of the 699 patients (2.4%) discontinued the study before week 16. Discontinuation was related to the study treatment in 13 of these 17 patients: 7 of the 462 raltegravir recipients (1.5%) and 6 of the 237 placebo recipients (2.5%). The results of the two studies were consistent. At week 16, counting noncompletion as treatment failure, 355 of 458 raltegravir recipients (77.5%) had HIV-1 RNA levels below 400 copies per milliliter, as compared with 99 of 236 placebo recipients (41.9%, P<0.001). Suppression of HIV-1 RNA to a level below 50 copies per milliliter was achieved at week 16 in 61.8% of the raltegravir recipients, as compared with 34.7% of placebo recipients, and at week 48 in 62.1% as compared with 32.9% (P<0.001 for both comparisons). Without adjustment for the length of follow-up, cancers were detected in 3.5% of raltegravir recipients and in 1.7% of placebo recipients. The overall frequencies of drug-related adverse events were similar in the raltegravir and placebo groups.

CONCLUSIONS

In HIV-infected patients with limited treatment options, raltegravir plus optimized background therapy provided better viral suppression than optimized background therapy alone for at least 48 weeks. (ClinicalTrials.gov numbers, NCT00293267 and NCT00293254.)

Tipranavir-ritonavir genotypic resistance score in protease inhibitor-experienced patients

To identify mutations associated with the virological response (VR) to a tipranavir-ritonavir (TPV/r)-based regimen, 143 patients previously treated with protease inhibitor (PI) were studied. VR was defined by a decrease of at least 1 log(10) in, or undetectable, human immunodeficiency virus (HIV) RNA at month 3. The effect of each mutation in the protease, considering all variants at a residue as a single variable, on the VR to TPV/r was investigated. Mutations at six residues were associated with a lower VR (E35D/G/K/N, M36I/L/V, Q58E, Q61D/E/G/H/N/R, H69I/K/N/Q/R/Y, and L89I/M/R/T/V), and one mutation was associated with a higher VR (F53L/W/Y). The genotypic score M36I/L/V-53L/W/Y + Q58E + H69I/K/N/Q/R/Y + L89I/M/R/T/V was selected as providing a strong association with VR. For the seven patients with a genotypic score of -1 (viruses with only mutation at codon 53), the percentage of responders was 100% and the percentages were 79%, 56%, 33%, 21%, and 0% for those with scores of 0, 1, 2, 3, and 4, respectively. The percentage of patients showing a response to TPV/r was lower for patients infected with non-clade B viruses (n = 16, all non-B subtypes considered together) than for those infected with clade B viruses (n = 127) (25% and 59%, respectively; P = 0.015). Most mutations associated with VR to TPV/r had not previously been associated with PI resistance. This is consistent with phenotypic analysis showing that TPV has a unique resistance profile. Mutations at five positions (35, 36, 61, 69, and 89) were observed significantly more frequently in patients infected with a non-B subtype than in those infected with the B subtype, probably explaining the lower VR observed in these patients.

Management of hepatic complications in HIV-infected persons

In the era of effective antiretroviral therapy (ART), liver disease is the second most common cause of death among persons with human immunodeficiency virus (HIV) infection. Liver disease-related deaths mostly result from chronic infection with hepatitis B virus (HBV) and/or hepatitis C virus (HCV). In addition, recent reports suggest that HCV infection may be transmitted sexually between HIV-infected men who have sex with men. Management of these conditions in HIV-infected persons requires careful consideration, balancing the potential benefits of therapy with the potential for significant treatment-related adverse effects (HCV infection) and viral resistance and/or hepatitis flares (HBV infection). Furthermore, several antiretroviral agents are active against HBV infection, including lamivudine, emtricitabine, tenofovir, and, more recently, entecavir. Despite the complexity and potential for antiretroviral-associated hepatotoxicity, ART usually is safe for patients with viral hepatitis coinfection, and, in some cases, treatment for HIV infection may be beneficial for the liver.

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

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

Tipranavir (TPV) genotypic inhibitory quotient predicts virological response at 48 weeks to TPV-based salvage regimens

The virological response (VR) to a tipranavir-ritonavir (TPV-RTV)-based regimen had been shown to be associated with a number of mutations in the protease gene, the use of enfuvirtide (T20), and the TPV phenotypic inhibitory quotient (IQ). The role of the TPV genotypic IQ (gIQ) has not yet been fully investigated. The aim of our study was to evaluate the relationship between the TPV gIQ and the VR at 48 weeks to TPV-based salvage regimens. Patients placed on regimens containing two nucleoside reverse transcriptase inhibitors plus TPV-RTV 500/200 mg twice a day with or without T20 were prospectively studied. Regular follow-up was performed over the study period. VR, considered a viral load (VL) decrease of >or=1 log unit and/or the achievement of <50 copies/ml with no VL rebound of >0.5 log unit compared to the maximal VL decrease at week 48, was assessed. Thirty-eight patients who had received multiple drugs were included. At week 48 the VL decrease was -1.48 (interquartile range [IQR], -2.88 to -0.48), 15 patients (39.5%) had VLs of <50 copies/ml, and the CD4+ cell count increase was 37 cells/mm3 (IQR, -30 to +175). Twenty subjects (52.6%) achieved VRs. The TPV gIQ and optimized background score (OBS) were independently associated with higher VL decreases. The TPV gIQ and OBS were also independent predictors of a VR at week 48. TPV gIQ and OBS cutoff values of 14,500 and 2, respectively, were associated with a higher rate of VR. The TPV gIQ was shown to be able to predict the VR at 48 weeks to TPV-containing salvage regimens better than the TPV trough concentration or TPV-associated mutations alone. A possible TPV gIQ cutoff value of 14,500 for reaching a VR at week 48 was suggested. Further studies are needed in order to evaluate the calculation of TPV gIQ as a new tool for the optimization of TPV-based salvage therapy.