Structured treatment interruption in patients infected with HIV: a new approach to therapy

Forgiveness of INSTI-Containing Regimens at Drug Concentrations Simulating Variable Adherence In Vitro

The integrase strand transfer inhibitor (INSTI)-based regimens bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF), dolutegravir (DTG)+FTC/TAF, DTG/lamivudine (3TC), and DTG/rilpivirine (RPV) are all approved for treatment of HIV-infected patients, with various limitations. Here, time to in vitro viral breakthrough (VB) and resistance barrier using simulated human drug exposures at either full or suboptimal treatment adherence to each regimen were compared. At drug concentrations corresponding to full adherence and 1 missed dose (C_min and C_min−1), no VB occurred with any regimen. At C_min−2, VB occurred only with DTG+3TC, with emergent resistance to both drugs. At C_min−3, VB occurred with all regimens: 100% of DTG+3TC cultures had VB by day 12, and <15% of BIC+FTC+TAF, DTG+FTC+TAF, and DTG+RPV cultures had VB. Emergent reverse transcriptase (RT) or integrase (IN) resistance was seen with DTG+RPV and DTG+3TC but not with BIC+FTC+TAF or DTG+FTC+TAF. At C_min−4, 100% VB occurred with DTG+3TC and DTG+FTC+TAF by day 12, while 94% VB occurred with DTG+RPV by day 25 and only 50% VB occurred with BIC+FTC+TAF by day 35. Emergent C_min−4 drug resistance was seen with all regimens but at differing frequencies; DTG+RPV had the most cultures with resistance. Emergent resistance was consistent with clinical observations. Overall, under high adherence conditions, no in vitro VB or resistance development occurred with these INSTI-based regimens. However, when multiple missed doses were simulated in vitro, BIC+FTC+TAF had the highest forgiveness and barrier to resistance of all tested regimens. Compared to DTG+3TC and DTG+FTC+TAF, DTG+RPV had higher forgiveness but lower resistance barrier after several simulated missed doses.

Why the HIV Reservoir Never Runs Dry: Clonal Expansion and the Characteristics of HIV-Infected Cells Challenge Strategies to Cure and Control HIV Infection

Antiretroviral therapy (ART) effectively reduces cycles of viral replication but does not target proviral populations in cells that persist for prolonged periods and that can undergo clonal expansion. Consequently, chronic human immunodeficiency virus (HIV) infection is sustained during ART by a reservoir of long-lived latently infected cells and their progeny. This proviral landscape undergoes change over time on ART. One of the forces driving change in the landscape is the clonal expansion of infected CD4 T cells, which presents a key obstacle to HIV eradication. Potential mechanisms of clonal expansion include general immune activation, antigenic stimulation, homeostatic proliferation, and provirus-driven clonal expansion, each of which likely contributes in varying, and largely unmeasured, amounts to maintaining the reservoir. The role of clinical events, such as infections or neoplasms, in driving these mechanisms remains uncertain, but characterizing these forces may shed light on approaches to effectively eradicate HIV. A limited number of individuals have been cured of HIV infection in the setting of bone marrow transplant; information from these and other studies may identify the means to eradicate or control the virus without ART. In this review, we describe the mechanisms of HIV-1 persistence and clonal expansion, along with the attempts to modify these factors as part of reservoir reduction and cure strategies.

Non-persistence to antiretroviral therapy among adults receiving HIV medical care in the United States

Not taking medicine over a specific period of time-non-persistence to antiretroviral therapy (ART)-may be associated with higher HIV-viral load. However, national estimates of non-persistence among U.S. HIV patients are lacking. We examined the association between non-persistence and various factors, including sustained HIV-viral suppression (VS) stratified by adherence, and assessed reasons for non-persistence using Medical Monitoring Project (MMP) data. MMP conducts clinical and behavioral surveillance among cross-sectional representative samples of adults receiving HIV care in the U.S. We analyzed weighted MMP interview and medical record abstraction data collected between 6/2011-5/2015 from 18,423 patients self-reporting ART use. We defined non-persistence as a self-initiated decision to not take ART for ≥2 consecutive days in the past 12-months, non-adherence as missing ≥1 ART dose during the past 3-days and sustained VS as all HIV-viral loads documented in medical record during the past 12-months as undetectable or <200 copies/mL. We used Rao-Scott chi-square tests to examine the association between non-persistence and sociodemographic, behavioral, clinical, and medication-related factors. We examined the association between non-persistence and sustained VS, stratified by adherence, and present prevalence ratios (PRs) with 95% confidence intervals (CIs). Reasons for non-persistence were assessed. Overall, 7% of patients reported non-persistence. Drug use, depression and medication side effects were associated with non-persistence (P < 0.01). Non-persistence was associated with the lack of sustained VS (PR: .66, CI:63-.70); this association did not differ by adherence level. However, VS was lower among the non-persistent/adherent compared with the persistent/non-adherent [51% (CI:47-54) versus 61% (CI:36-46), P < 0.01]. The most prevalent reason for non-persistence was treatment fatigue (38%). Though few persons in HIV care reported non-persistence, our findings suggest that non-persistence is associated with lack of sustained VS, regardless of adherence. Routine screening for non-persistence during clinical appointments and counseling for those at risk for non-persistence may help improve clinical outcomes.

Polyfunctional HIV-Specific Antibody Responses Are Associated with Spontaneous HIV Control

Elite controllers (ECs) represent a unique model of a functional cure for HIV-1 infection as these individuals develop HIV-specific immunity able to persistently suppress viremia. Because accumulating evidence suggests that HIV controllers generate antibodies with enhanced capacity to drive antibody-dependent cellular cytotoxicity (ADCC) that may contribute to viral containment, we profiled an array of extra-neutralizing antibody effector functions across HIV-infected populations with varying degrees of viral control to define the characteristics of antibodies associated with spontaneous control. While neither the overall magnitude of antibody titer nor individual effector functions were increased in ECs, a more functionally coordinated innate immune-recruiting response was observed. Specifically, ECs demonstrated polyfunctional humoral immune responses able to coordinately recruit ADCC, other NK functions, monocyte and neutrophil phagocytosis, and complement. This functionally coordinated response was associated with qualitatively superior IgG3/IgG1 responses, whereas HIV-specific IgG2/IgG4 responses, prevalent among viremic subjects, were associated with poorer overall antibody activity. Rather than linking viral control to any single activity, this study highlights the critical nature of functionally coordinated antibodies in HIV control and associates this polyfunctionality with preferential induction of potent antibody subclasses, supporting coordinated antibody activity as a goal in strategies directed at an HIV-1 functional cure.

Modeling HIV persistence, the latent reservoir, and viral blips

HIV-1 eradication from infected individuals has not been achieved with the prolonged use of highly active antiretroviral therapy (HAART). The cellular reservoir for HIV-1 in resting memory CD4(+) T cells remains a major obstacle to viral elimination. The reservoir does not decay significantly over long periods of time but is able to release replication-competent HIV-1 upon cell activation. Residual ongoing viral replication may likely occur in many patients because low levels of virus can be detected in plasma by sensitive assays and transient episodes of viremia, or HIV-1 blips, are often observed in patients even with successful viral suppression for many years. Here we review our current knowledge of the factors contributing to viral persistence, the latent reservoir, and blips, and mathematical models developed to explore them and their relationships. We show how mathematical modeling has helped improve our understanding of HIV-1 dynamics in patients on HAART and of the quantitative events underlying HIV-1 latency, reservoir stability, low-level viremic persistence, and emergence of intermittent viral blips. We also discuss treatment implications related to these studies.

The effect of controlled therapy interruption in chronic HCV infection: enhanced host immune response? A hypothesis

BACKGROUND

We have hypothesized that prolonged viral suppression partially reverses immune tolerance in chronic hepatitis C virus infection. Brief periods of treatment interruption can then simulate 'auto-vaccination' and evoke powerful secondary host immune responses.

OBJECTIVE

To determine the effect of controlled therapy interruption CTI on viral load in previous relapsers to interferon and ribavirin treatment.

STUDY DESIGN

Virus is maintained at undetectable levels for 2-8 weeks with pegylated interferon and ribavirin and then briefly interrupted, restarting as soon as viremia returns (cycle 1). It is suppressed for at least a further 4 weeks, then briefly interrupted again (cycle 2).

RESULTS

Viremia relapsed within 2-4 weeks (time to relapse TTR) after the first treatment interruption in all four patients in cycle 1. TTR increased sevenfold with the second treatment interruption in patient 1 and was followed by sustained virological response with cycle 3. In patient 2, TTR increased threefold after cycle 2 and subsequent cycles. Serum ALT and bilirubin rose significantly with treatment interruption during cycles 2 and 3, returning to baseline with treatment resumption. Serum bilirubin rose to 12.3mg/dl when two doses of pegylated interferon were missed during cycle 4. In patients 3 and 4, TTR was unchanged after three consecutive cycles. However, VL has remained more than 1 log below baseline for up to 18 months in both.

CONCLUSIONS

These observations suggest that CTI exerts significant control of chronic hepatitis C viremia.

Drug-Sparing Regimens for HIV Combination Therapy: Benefits Predicted for “Drug Coasting”

Structured Treatment Interruptions (STI) during HIV drug therapy were thought to potentially reduce side effects and toxicity, boost immune involvement, and possibly lower the viral set-point. Clinical trials of STI regimens, however, have had mixed results. We use an established mathematical model of HAART to estimate possible therapeutic outcomes for STI and for other, similar patterns in HIV combination therapy. We perform an exhaustive search of patterns of up to 60 days, for triple-drug combinations involving accurate pharmacokinetics for 12 specific antiviral drugs. The results of this analysis are consistent with recent clinical trials which have demonstrated that STI-type patterns, involving therapy interruption of weeks or months, are rarely optimal. Our analysis predicts, however, that the benefit of treatment can often be improved by including very short drug-free periods, during which the patient effectively "coasts" for a day or two on adequate drug concentrations due to the long half-life of some pharmaceuticals. Our analysis predicts many cases in which this may be achieved without increasing the risk of drug-resistance. This suggests that "drug coasting" patterns, significantly shorter than STI patterns, may merit further clinical investigation in efforts to find drug-sparing regimens for HIV.

Emergence of HIV-1 Drug Resistance During Antiretroviral Treatment

Treating HIV-infected patients with a combination of several antiretroviral drugs usually contributes to a substantial decline in viral load and an increase in CD4(+) T cells. However, continuing viral replication in the presence of drug therapy can lead to the emergence of drug-resistant virus variants, which subsequently results in incomplete viral suppression and a greater risk of disease progression. In this paper, we use a simple mathematical model to study the mechanism of the emergence of drug resistance during therapy. The model includes two viral strains: wild-type and drug-resistant. The wild-type strain can mutate and become drug-resistant during the process of reverse transcription. The reproductive ratio [Symbol: see text](0) for each strain is obtained and stability results of the steady states are given. We show that drug-resistant virus is more likely to arise when, in the presence of antiretroviral treatment, the reproductive ratios of both strains are close. The wild-type virus can be suppressed even when the reproductive ratio of this strain is greater than 1. A pharmacokinetic model including blood and cell compartments is employed to estimate the drug efficacies of both the wild-type and the drug-resistant strains. We investigate how time-varying drug efficacy (due to the drug dosing schedule and suboptimal adherence) affects the antiviral response, particularly the emergence of drug resistance. Simulation results suggest that perfect adherence to regimen protocol will well suppress the viral load of the wild-type strain while drug-resistant variants develop slowly. However, intermediate levels of adherence may result in the dominance of the drug-resistant virus several months after the initiation of therapy. When more doses of drugs are missed, the failure of suppression of the wild-type virus will be observed, accompanied by a relatively slow increase in the drug-resistant viral load.

The Bcr-Abl mutations T315I and Y253H do not confer a growth advantage in the absence of imatinib

Mutations in the Bcr-Abl kinase domain are a frequent cause of imatinib resistance in patients with advanced CML or Ph+ ALL. The impact of these mutations on the overall oncogenic potential of Bcr-Abl and on the clinical course of the disease in the absence of imatinib is presently unclear. In this study, we analyzed the effects of the Bcr-Abl P-loop mutation Y253H and the highly imatinib resistant T315I mutation on kinase activity in vitro and transforming efficiency of Bcr-Abl in vitro and in vivo. Immunoprecipitated Bcr-AblY253H and Bcr-AblT315I proteins displayed similar kinase activities and substrate phosphorylation patterns as Bcr-Abl wildtype. We directly compared the proliferative capacity of mutant to wildtype Bcr-Abl in primary BM cells in vitro and in a murine transplantation model of CML by using a competitive repopulation assay. The results implicate that in the absence of imatinib, there is no growth advantage for cells carrying Bcr-AblT315I or Bcr-AblY253H compared to Bcr-Ablwt, whereas imatinib treatment clearly selects for leukemic cells expressing mutant Bcr-Abl both in vitro and in vivo. Thus, the analysed Bcr-Abl mutants confer imatinib resistance, but do not induce a growth advantage in the absence of imatinib.

Structured treatment interruptions (STI) in chronic unsuppressed HIV infection in adults

BACKGROUND

Structured treatment interruptions (STI) of antiretroviral therapy (ART) have been investigated as part of novel treatment strategies, with different aims and objectives depending on the populations involved. These populations include: 1) patients who initiate ART during acute HIV infection; 2) patients with chronic HIV infection, on ART, with successfully suppressed viremia; and 3) patients with chronic HIV infection and treatment failure, with persistent viremia due to multi-drug resistant HIV (Hirschel 2001; Deeks 2002; Miller 2003). In an earlier Cochrane review (Pai 2005), we had summarized the evidence about the effects of STI in chronic suppressed HIV infection. In this review, we summarize the evidence on STI in patients with chronic unsuppressed HIV infection due to drug-resistant HIV. Unsuppressed HIV infection describes those patients who cannot suppress viremia, due to the presence of multi-drug-resistant virus. It is also referred to as treatment failure. Drug resistance is identified by the presence of resistant mutations at baseline.STI as a treatment strategy in HIV-infected patients with chronic unsuppressed viremia involves interrupting ART in controlled clinical settings, for a pre-specified duration of time. These interruptions have various aims, including the following: 1) to allow wild virus to re-emerge and replace the resistant mutant virus, with the hope of improving the efficacy of a subsequent ART regimen; 2) to halt development of drug resistance and to preserve subsequent treatment options; 3) to alleviate treatment fatigue and reduce drug-related adverse effects; and 4) to improve quality of life (Miller 2003; Montaner 2001; Vella 2000;).

OBJECTIVES

The objective of our systematic review was to synthesize the evidence on the effect of structured treatment interruptions in adult patients with chronic unsuppressed HIV infection.

SEARCH STRATEGY

We included all available intervention studies (randomized controlled trials and non-randomized trials) conducted in HIV-infected patients worldwide. We searched nine databases, covering the period from January 1996 to February 2006. We also scanned bibliographies of relevant studies and contacted experts in the field to identify unpublished research, abstracts and ongoing trials. In the first screen, a total of 3186 potentially eligible citations from nine databases and sources were identified, of which 2047 duplicate citations were excluded. The remaining 1139 citations were examined in detail, and we further excluded 951 citations that were modeling studies, animal studies, case reports, and opinion pieces. As shown in Figure 01, 188 citations were identified in the second screen as relevant for full-text screening. Of these, 60 basic science studies, editorials and abstracts were excluded and 128 full-text articles were retrieved. In the third screen, all full-text articles were examined for eligibility in our review. These were subclassified into three categories: 1) chronic suppressed HIV infection; 2) chronic unsuppressed HIV infection; and 3) acute HIV infection. Studies were further excluded if their abstracts did not contain enough information for inclusion in our reviews. A total of 62 studies were finally classified into chronic suppressed, acute, and chronic unsuppressed categories. Of these, 17 trials met the eligibility criteria for this review.

SELECTION CRITERIA

Inclusion criteriaAll available randomized or non-randomized controlled trials investigating planned treatment interruptions among patients with chronic unsuppressed HIV infection. Early pilot non-randomized prospective studies on treatment interruptions of fixed and variable durations were also included. Relevant abstracts on randomized controlled trials were also included if they contained sufficient information. Exclusion criteriaEditorials, reviews, modeling studies, and basic science studies were excluded. Studies on STI among patients with chronic suppressed HIV infection were summarized in a separate review. Studies on STI in primary HIV infection were beyond the scope of this review.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data, evaluated study eligibility and quality. Disagreements were resolved in consultation with a third reviewer.A total of seventeen studies on STI were included in our review. However, due to significant heterogeneity across studies (i.e. in study design, populations, baseline characteristics, and reported outcomes; and in reporting of measures of effect, hazard ratios, and risk ratios), we considered it inappropriate to perform a meta-analysis.

MAIN RESULTS

In early pilot non-randomized trials, a pattern was evident across studies. During treatment interruption, a decline in CD4 cell counts, increase in viral load, and a shift in the level of genotypic drug resistance towards more of a wild-type HIV virus was reported. This suggests that STI may be used to increase drug susceptibility to an optimized salvage regimen upon treatment re-initiation. These studies generated useful data and hypotheses that were later tested in randomized controlled trials. Randomized controlled trials rated high on quality. Of the eight randomized controlled trials reviewed, seven had been completed while one was ongoing and remains blinded. Of the seven completed randomized controlled trials, six have reported consistent virologic and immunologic patterns, and found no significant benefit in virologic response to subsequent ART in the STI arm, compared to the control arm. In addition, the largest completed randomized trial reported greater numbers of clinical disease progression events and evidence of prolonged negative impact on CD4 cell counts in the STI arm (Beatty 2005; Benson 2004; Deeks 2001; Lawrence 2003; Walmsley 2005; Ruiz 2003). The single RCT with divergent findings from the others (GigHAART), reporting a significant virologic and immunologic benefit due to STI, was different in prescribing a shorter STI duration and a salvage ART regimen of 8-9 drugs. There were also differences in the patient population characteristics with this study, targeting those with very advanced HIV disease (Katlama 2004). Although we await the unblinded results of the eighth RCT (OPTIMA), the evidence so far does not support STI in the setting of chronic unsuppressed HIV infection with antiretroviral treatment failure (Brown 2004; Holodniy 2004; Kyriakides 2002; Singer 2006).

AUTHORS' CONCLUSIONS

The current available evidence primarily supports a lack of benefit of STI before switching therapy in patients with unsuppressed HIV viremia despite ART. There is evidence of harm in attempting STI in patients with relatively advanced HIV disease, due to the associated CD4 cell decline and the increased risk of clinical disease progression. At this time, there is no evidence to recommend the use of STI in this clinical category of patients with treatment failure.

Interruption thérapeutique chez des patients infectés par le virus de l'immunodéficience humaine : évolution clinique et biologique

OBJECTIVE

The authors had for aim to evaluate the clinical and biological evolution in HIV-infected patients with viraemia lower than 30,000 copies/mL having decided to interrupt their treatment.

PATIENTS AND METHODS

Patients with highly active antiretroviral therapy (HAART) for more than 3 months followed by treatment interruption longer than 1 month were included in a retrospective analysis.

RESULTS

Forty-six patients having stopped treatment between November 1999 and July 2003 were included. The median duration of treatment interruption was 9.5 months. During the study, no clinical event occurred for 21 patients, and at least 1 clinical event occurred for the 25 others. The median CD4(+) cell counts (CD4) before and at the end of treatment interruption were 597/mm(3) and 437/mm(3), respectively (P<0.001). The median values of viral load before and at the end of treatment interruption were <50 and 23749 copies/mL, respectively (P<0.001). Among the 26 patients having started a new HAART, pre-treatment interruption and post-new HAART median CD4 (with a median delay after HAART of 9.7 months) were 548 and 432.5/mm(3) (P=0.02). Pre-treatment interruption and post-new HAART median viral load were 131.5 and 94.5 copies/mL (NS).

CONCLUSIONS

Treatment interruption must be used with caution in spite of the absence of virological impact, because CD4 cell count after new HAART is lower than CD4 preceding treatment interruption. Treatment interruption is contraindicated for patients with AIDS. Physicians must carefully follow other patients who decide on a treatment interruption.

Structured treatment interruptions (STI) in chronic suppressed HIV infection in adults

BACKGROUND

Although antiretroviral treatment (ART) has led to a decline in morbidity and mortality of HIV-infected patients in developed countries, it has also presented challenges. These challenges include increases in pill burden; adherence to treatment; development of resistance and treatment failure; development of drug toxicities; and increase in cost of HIV treatment and care. These issues stimulated interest in investigating the short-term and long-term consequences of discontinuing ART, thus providing support for research in structured treatment interruptions (STI). Structured treatment interruptions of antiretroviral treatment involve taking supervised breaks from ART. STI are defined as one or more planned, timing pre-specified, cyclical interruptions in ART. STI are attempted in monitored clinical settings in eligible participants. STI have generated hopes of reducing drug toxicities, decreasing costs and total time on treatment in HIV-positive patients. The first STI was attempted in the case of a patient in Germany, who later permanently discontinued treatment. This successful anecdotal case report led to several trials on STI worldwide.

OBJECTIVES

The objective of this systematic review was to assess the effects of structured treatment interruptions (STI) of antiretroviral therapy (ART) in the management of chronic suppressed HIV infection, using all available high-quality studies.

SEARCH STRATEGY

Nine databases covering the time period from January 1996 to March 2005 were searched. Bibliographies were scanned and experts contacted in the field to identify unpublished research and ongoing trials. Two reviewers independently extracted data, and evaluated study eligibility and quality. Disagreements were resolved in consultation with a third reviewer. Data from 33 studies were included in the review.

SELECTION CRITERIA

STI is a planned, timing pre-specified experimental intervention. In our review, we decided to include all available intervention trials in HIV-infected patients, with or without control groups. We reviewed evidence from 18 randomized and non-randomized controlled trials, and 15 single arm trials. Single arm trials were included because these pilot studies made significant contribution to the early development and refutation of hypotheses in STI.

DATA COLLECTION AND ANALYSIS

Trials included in this review varied in study participants, methodology and reported inconsistent measures of effect. Due to this heterogeneity, we did not attempt to meta-analyse them. Results were tabulated and a qualitative systematic review was done

MAIN RESULTS

For the purpose of this review, STI strategies were classified either as a timed-cycle STI strategy or a CD4-guided STI strategy. In timed-cycle STI strategy, a predetermined period of fixed duration (e.g. one week, one month) off ART was attempted followed by resumption of ART, while closely monitoring changes in CD4 levels and viral load levels. Predetermined criteria for interruption and resumption were laid out in this strategy. Timed-cycle STI fell out of favor due to reports of development of resistance in many studies. Moreover, there were no significant immunological and virological benefits, and no reduction in toxicities, reported in these studies. In CD4-guided STI strategy, ART was interrupted for variable durations guided by CD4 levels. Participants with high nadir CD4 levels qualified for this approach. A reduction in costs of ART, a reduction in mutation, and a better tolerability of this CD4-guided STI strategy was reported. However, concerns about long-term safety of this strategy on immunological, virological, and clinical outcomes were also raised.

AUTHORS' CONCLUSIONS

Timed-cycle STI have not been proven to be safe in the short term. Although CD4-guided STI strategy has reported favorable outcomes in the short term, the long-term safety, efficacy and tolerability of this strategy has not been fully investigated. Based on the studies we reviewed, the evidence to support the use of timed-cycle STI and CD4-guided STI cycles as a standard of care in the management of chronic suppressed HIV infection is inconclusive.

A model predictive control based scheduling method for HIV therapy

Recently developed models of the interaction of the human immune system and the human immunodeficiency virus (HIV) suggest the possibility of using interruptions of highly active anti-retroviral therapy (HAART) to simulate a therapeutic vaccine and induce cytotoxic lymphocyte (CTL) mediated control of HIV infection. We have developed a model predictive control (MPC) based method for determining optimal treatment interruption schedules for this purpose. This method provides a clinically implementable framework for calculating interruption schedules that are robust to errors due to measurement and patient variations. In this paper, we discuss the medical motivation for this work, introduce the MPC-based method, show simulation results, and discuss future work necessary to implement the method.

Structured intermittent therapy with seven-day cycles of HAART for chronic HIV infection: a pilot study in São Paulo, Brazil

In the last 6 years, an impressive impact of the highly active antiretroviral therapy (HAART) on survival and morbidity in HIV-1-infected individuals has been attained. However, their prolonged use may induce metabolic adverse effects such as lipodistrophy, hypertension, diabetes mellitus, osteopenia and hyperlipidemia. Recently, new strategies such as short-cycle structured intermittent therapy (SIT; 7 days without therapy followed by 7 days with HAART) have been suggested. We tested this strategy in seven (four women and three men; mean of age 39 of years) HIV-positive individuals, all of whom had CD4+ T cell counts greater than 500 cells/mm3 and undetectable plasma viral load for at least 2 years. Our results indicated no opportunistic diseases or CD4 cell count decrease over a mean follow-up of 26 months. No plasma viral replication was detected in five of seven cases. There was a decrease in triglyceride levels to normal range (not statistically significant), but no modification of cholesterol levels. Thus, we recommend a larger clinical trial to determine if SIT is cost effective in developing countries.

Interrupting highly active antiretroviral therapy in patients with HIV

Scheduled treatment interruptions are preplanned interruptions of antiretroviral treatment, which may be directed by time (e.g., cycles of 8 weeks on treatment and 8 weeks off treatment); the concentration of CD4+ lymphocytes (the CD4 count); HIV-1 RNA concentration (viral load); or other factors. This review covers the rationale of scheduled treatment interruptions and the different strategies that have been explored. It examines the issue of autovaccination, resistance and other risks and benefits. Scheduled-treatment-interruption studies in three populations are discussed: patients who initiated highly active antiretroviral therapy during acute HIV infection; patients with successfully treated chronic HIV infection; and patients with highly active antiretroviral therapy failure.

Knowledge of structured treatment interruption and adherence to antiretroviral therapy

We conducted a survey of 106 HIV-infected patients on antiretroviral therapy at a community hospital in Lancaster, Pennsylvania, to determine the extent of patient knowledge and attitudes about structured treatment interruption (STI) and whether these were factors in adherence to antiretroviral regimens. Thirty-six percent of patients possessed knowledge of STI as a treatment option and four patients reported that they had stopped taking antiretroviral therapy without specific recommendation from their physician based on information they had heard or read about STI. There was no difference in median adherence based on whether a patient was aware of STI, however, in the group who had heard of STI, attitude that STI is very beneficial was correlated with greater adherence to medication. More than one third of HIV-infected patients on antiretroviral therapy possessed knowledge of STI, and this knowledge affected adherence to antiretroviral regimens. Providers caring for HIV-infected patients should routinely inquire about patient knowledge of STI as another factor in assessing adherence to antiretroviral therapy.

Drug resistance and adherence to HIV/AIDS antiretroviral treatment: against a double standard between the north and the south

Here we review the available evidence on adherence to highly active antiretroviral therapy (HAART) and its relationship with the risk of the dissemination of HIV-resistant viral strains in both developed and developing countries. We argue that referring to these issues of resistance and adherence to withhold or delay access to HAART in developing countries implicitly imposes a double standard of thinking that is unacceptable. Scaling-up access to HAART to succeed in low-resource settings, however, requires the long-term monitoring of adherence as well as the clarification of the complex trade-offs between minimizing the costs of therapeutic regimens and minimizing the risks of non-adherence and resistance.

Brief summary of the legal proceeding

The panel, held in Rome in April 2002 with the participation of more than 100 Italian directors of infectious diseases wards, followed a systematic approach to reviewing the evidence of any specific use of the genotypic assays to detect antiretroviral resistance. The single recommendations have been developed using a rating scheme based on consideration of the evidence and, when direct evidence was lacking, on expert opinion. Another emerging issue approached during this meeting is represented by the reproducibility of HIV-1 reverse transcriptase and protease sequencing in clinical settings. The degree of concordance of genotypic assays among 12 experienced laboratories is also reported.

Discovery of 4-Benzoyl-1-[(4-methoxy-1H- pyrrolo[2,3-b]pyridin-3-yl)oxoacetyl]-2- (R)-methylpiperazine (BMS-378806): A Novel HIV-1 Attachment Inhibitor That Interferes with CD4-gp120 Interactions

Indole derivative 1 interferes with the interaction of the HIV surface protein gp120 with the host cell receptor CD4. The 4-fluoro derivative 2 exhibited markedly enhanced potency and was bioavailable in the rat, dog, and cynomolgus monkey when administered orally as a solution formulation. However, aqueous suspensions of 2 were poorly bioavailable, indicative of dissolution-limited absorption. The 7-azaindole derivative 3, BMS-378806, exhibited improved pharmaceutical properties while retaining the HIV-1 inhibitory profile of 2.

Quantitation of cytomegalovirus (CMV) DNA by real-time PCR for occurrence of CMV disease in HIV-infected patients receiving highly active antiretroviral therapy

In HIV-infected patients treated with highly active antiretroviral therapy (HAART) included in the Predivir cohort, we have evaluated the usefulness of CMV DNA quantitation by a TaqMan PCR assay from peripheral blood leukocytes (PBLs) to predict CMV disease occurrence. In parallel with the immune restoration after treatment by HAART, the percentage of positive samples decreased progressively from 7.3% at Day 0 to 3.5% at Month 12. Among the CMV markers, the smallest concordance with PBL CMV TaqMan PCR, as evaluated by kappa, was observed with pp65 antigenemia, whereas concordance with all other CMV markers was high. Among the 16 patients with CMV DNA copies at least once >100/150,000 cells, CMV disease occurred in six during follow-up, whereas among the 159 patients with CMV DNA copies always <10/150,000 cells, CMV disease occurred in three and among the seven patients with CMV DNA copies >10 and <100 occurred in only one. In univariate Cox models, all the CMV markers including PBL CMV TaqMan PCR >10/150,000 cells (RR: 27.6, IC95: 7.1-107.2), the CD4 cell count <75 cells/mm(3) and the HIV viral load >100,000 copies/ml were predictive for CMV disease. In a stepwise multivariate analysis, which should be interpreted with caution due to the small number of events (n = 10), three covariates were associated independently with CMV disease: pp65 antigenemia >100 nuclei/200,000, PBL CMV TaqMan PCR >10 copies/150,000 cells and HIV viral load remaining or increasing >100,000 copies/ml.