Michael D. Hughes

A CONTROLLED TRIAL OF TWO NUCLEOSIDE ANALOGUES PLUS INDINAVIR IN PERSONS WITH HUMAN IMMUNODEFICIENCY VIRUS INFECTION AND CD4 CELL COUNTS OF 200 PER CUBIC MILLIMETER OR LESS

BACKGROUND The efficacy and safety of adding a protease inhibitor to two nucleoside analogues to treat human immunodeficiency virus type 1 (HIV-1) infection are not clear. We compared treatment with the protease inhibitor indinavir in addition to zidovudine and lamivudine with treatment with the two nucleosides alone in HIV-infected adults previously treated with zidovudine. METHODS A total of 1156 patients not previously treated with lamivudine or protease inhibitors were stratified according to CD4 cell count (50 or fewer vs. 51 to 200 cells per cubic millimeter) and randomly assigned to one of two daily regimens: 600 mg of zidovudine (or stavudine) and 300 mg of lamivudine, or that regimen with 2400 mg of indinavir. The primary end point was the time to the development of the acquired immunodeficiency syndrome (AIDS) or death. RESULTS The proportion of patients whose disease progressed to AIDS or death was lower with indinavir, zidovudine, and lamivudine (6 percent) than with zidovudine and lamivudine alone (11 percent; estimated hazard ratio, 0.50; 95 percent confidence interval, 0.33 to 0.76; P=0.001). Mortality in the two groups was 1.4 percent and 3.1 percent, respectively (estimated hazard ratio, 0.43; 95 percent confidence interval, 0.19 to 0.99; P=0.04). The effects of treatment were similar in both CD4 cell strata. The responses of CD4 cells and plasma HIV-1 RNA paralleled the clinical results. CONCLUSIONS Treatment with indinavir, zidovudine, and lamivudine as compared with zidovudine and lamivudine alone significantly slows the progression of HIV-1 disease in patients with 200 CD4 cells or fewer per cubic millimeter and prior exposure to zidovudine.

A Trial Comparing Nucleoside Monotherapy with Combination Therapy in HIV-Infected Adults with CD4 Cell Counts from 200 to 500 per Cubic Millimeter

BACKGROUND This double-blind study evaluated treatment with either a single nucleoside or two nucleosides in adults infected with human immunodeficiency virus type 1 (HIV-1) whose CD4 cell counts were from 200 to 500 per cubic millimeter. METHODS We randomly assigned 2467 HIV-1--infected patients (43 percent without prior antiretroviral treatment) to one of four daily regimens: 600 mg of zidovudine; 600 mg of zidovudine plus 400 mg of didanosine; 600 mg of zidovudine plus 2.25 mg of zalcitabine; or 400 mg of didanosine. The primary end point was a > or = 50 percent decline in the CD4 cell count, development of the acquired immunodeficiency syndrome (AIDS), or death. RESULTS Progression to the primary end point was more frequent with zidovudine alone (32 percent) than with zidovudine plus didanosine (18 percent; relative hazard ratio, 0.50; P<0.001), zidovudine plus zalcitabine (20 percent; relative hazard ratio, 0.54; P<0.001), or didanosine alone (22 percent; relative hazard ratio, 0.61; P<0.001). The relative hazard ratios for progression to an AIDS-defining event or death were 0.64 (P=0.005) for zidovudine plus didanosine, as compared with zidovudine alone, 0.77 (P=0.085) for zidovudine plus zalcitabine, and 0.69 (P=0.019) for didanosine alone. The relative hazard ratios for death were 0.55 (P=0.008), 0.71 (P=0.10), and 0.51 (P=0.003), respectively. For zidovudine plus zalcitabine, the benefits were limited to those without previous treatment. CONCLUSIONS Treatment with zidovudine plus didanosine, zidovudine plus zalcitabine, or didanosine alone slows the progression of HIV disease and is superior to treatment with zidovudine alone. Antiretroviral therapy can improve survival in patients with 200 to 500 CD4 cells per cubic millimeter.

Antithrombotic Therapy for Atrial Fibrillation Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND The risk of stroke varies considerably across different groups of patients with atrial fibrillation (AF). Antithrombotic prophylaxis for stroke is associated with an increased risk of bleeding. We provide recommendations for antithrombotic treatment based on net clinical benefit for patients with AF at varying levels of stroke risk and in a number of common clinical scenarios. METHODS We used the methods described in the Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines article of this supplement. RESULTS For patients with nonrheumatic AF, including those with paroxysmal AF, who are (1) at low risk of stroke (eg, CHADS(2) [congestive heart failure, hypertension, age ≥ 75 years, diabetes mellitus, prior stroke or transient ischemic attack] score of 0), we suggest no therapy rather than antithrombotic therapy, and for patients choosing antithrombotic therapy, we suggest aspirin rather than oral anticoagulation or combination therapy with aspirin and clopidogrel; (2) at intermediate risk of stroke (eg, CHADS(2) score of 1), we recommend oral anticoagulation rather than no therapy, and we suggest oral anticoagulation rather than aspirin or combination therapy with aspirin and clopidogrel; and (3) at high risk of stroke (eg, CHADS(2) score of ≥ 2), we recommend oral anticoagulation rather than no therapy, aspirin, or combination therapy with aspirin and clopidogrel. Where we recommend or suggest in favor of oral anticoagulation, we suggest dabigatran 150 mg bid rather than adjusted-dose vitamin K antagonist therapy. CONCLUSIONS Oral anticoagulation is the optimal choice of antithrombotic therapy for patients with AF at high risk of stroke (CHADS(2) score of ≥ 2). At lower levels of stroke risk, antithrombotic treatment decisions will require a more individualized approach.

Statistical problems in the reporting of clinical trials. A survey of three medical journals.

Reports of clinical trials often contain a wealth of data comparing treatments. This can lead to problems in interpretation, particularly when significance testing is used extensively. We examined 45 reports of comparative trials published in the British Medical Journal, the Lancet, or the New England Journal of Medicine to illustrate these statistical problems. The issues we considered included the analysis of multiple end points, the analysis of repeated measurements over time, subgroup analyses, trials of multiple treatments, and the overall number of significance tests in a trial report. Interpretation of large amounts of data is complicated by the common failure to specify in advance the intended size of a trial or statistical stopping rules for interim analyses. In addition, summaries or abstracts of trials tend to emphasize the more statistically significant end points. Overall, the reporting of clinical trials appears to be biased toward an exaggeration of treatment differences. Trials should have a clearer predefined policy for data analysis and reporting. In particular, a limited number of primary treatment comparisons should be specified in advance. The overuse of arbitrary significance levels (for example, P less than 0.05) is detrimental to good scientific reporting, and more emphasis should be given to the magnitude of treatment differences and to estimation methods such as confidence intervals.

The Relation of Virologic and Immunologic Markers to Clinical Outcomes after Nucleoside Therapy in HIV-Infected Adults with 200 to 500 CD4 Cells per Cubic Millimeter

BACKGROUND We studied measures of human immunodeficiency virus (HIV) replication, the viral phenotype, and immune function (CD4 cell counts) and the relation of changes in these indicators to clinical outcomes in a subgroup of patients in a controlled trial of early antiretroviral treatment for HIV, the AIDS Clinical Trials Group Study 175. METHODS The 391 subjects, each of whom entered the study with a single screening CD4 cell count of 200 to 500 per cubic millimeter, were randomly assigned to receive zidovudine alone, didanosine alone, zidovudine plus didanosine, or zidovudine plus zalcitabine. Plasma concentrations of HIV RNA were assessed in 366 subjects, and viral isolates from 332 subjects were assayed for the presence of the syncytium-inducing phenotype. RESULTS After eight weeks, the mean (+/-SE) decrease from base line in the concentration of HIV RNA, expressed as the change in the base 10 log of the number of copies per milliliter, was 0.26+/-0.06 for patients treated with zidovudine alone, 0.65+/-0.07 for didanosine alone, 0.93+/-0.10 for zidovudine plus didanosine, and 0.89+/-0.06 for zidovudine plus zalcitabine (P<0.001 for each of the pairwise comparisons with zidovudine alone). Multivariate proportional-hazards models showed that higher base-line concentrations of plasma HIV RNA, less suppression of plasma HIV RNA by treatment, and the presence of the syncytium-inducing phenotype were significantly associated with an increased risk of progression to the acquired immunodeficiency syndrome and death. After adjustment for these measures of viral replication and for the viral phenotype, CD4 cell counts were not significant predictors of clinical outcome. CONCLUSIONS Both the risk of the progression of HIV disease and the efficacy of antiretroviral therapy are strongly associated with the plasma level of HIV RNA and with the viral phenotype. The changes in the plasma concentration of HIV RNA predict the changes in CD4 cell counts and survival after treatment with reverse-transcriptase inhibitors.

Stroke and thromboembolism in atrial fibrillation: A systematic review of stroke risk factors, risk stratification schema and cost effectiveness data

The risk of stroke in atrial fibrillation (AF) needs to be assessed in each patient to determine the clinical and cost-effectiveness of thromboprophylaxis, with the aim of appropriate use of antithrombotic therapy. To achieve this, stroke risk factors in AF populations need to be identified and stroke risk stratification models have been devised on the basis of these risk factors. In this article, we firstly provide a systematic review of studies examining the attributable stroke risk of various clinical, demographic and echocardiographic patient characteristics in AF populations. Secondly, we performed a systematic review of published stroke risk stratification models, in terms of the results of the review of stroke risk factors and their ability to accurately discriminate between different levels of stroke risk. Thirdly, we review the health economic evidence relating to the cost-effectiveness of anticoagulation and antiplatelet therapy as thromboprophylaxis in AF patients. The studies included in the systematic review of stroke risk factors identified history of stroke or TIA, increasing age, hypertension and structural heart disease (left-ventricular dysfunction or hypertrophy) to be good predictors of stroke risk in AF patients. The evidence regarding diabetes mellitus, gender and other patient characteristics was less consistent. Three stroke risk stratification models were identified that were able to discriminate between different categories of stroke risk to at least 95% accuracy. Few models had addressed the cumulative nature of risk factors where a combination of risk factors would confer a greater risk than either factor alone. In patients at high risk of stroke, anticoagulation is cost effective, but not for those with a low risk of stroke. With the evidence available for stroke risk factors and the various alternative stroke risk stratification models, a review of these models in terms of the evidence on which they are devised and their performance in representative AF populations is important. The appropriate administration of thromboprophylaxis in AF patients would need to balance the risks and benefits of antithrombotic therapy with its cost-effectiveness.

Meta-analysis for the evaluation of potential surrogate markers

We describe a meta-analysis approach for the evaluation of a potential surrogate marker. Surrogate markers are useful in helping to identify therapeutic mechanisms of action and disease pathogenesis, and for selecting therapies to take forward from phase II to phase III clinical trials. They have also become increasingly important for regulatory purposes by providing a basis for preliminary approval of drugs pending clinical outcome studies. Methodology for evaluating surrogate markers has focused on determining the difference in the effects of two treatments on clinical outcome in an individual clinical trial, and then estimating the proportion of this difference explained by the treatments effects on the potential marker. Studies are, however, frequently underpowered or cease before they accumulate sufficient evidence to draw strong conclusions about the value of a potential surrogate marker using this approach, and there are also some technical difficulties with the approach. Consideration of the association between the difference in treatment effects on the clinical outcome and the difference in treatment effects on the potential marker over a range of trials provides an alternative means to evaluate a potential marker. We describe a meta-analysis approach using Bayesian methods to model this association. Importantly, this approach enables one to obtain prediction intervals for the true difference in clinical outcome for a given estimated treatment difference in the effect on the potential marker. We illustrate the methodology by applying it to results from studies of the AIDS Clinical Trials Group to assess the value of CD4 T-lymphocyte cell count as a potential surrogate marker for the treatment effects on the development of AIDS or death.

Nevirapine, Zidovudine, and Didanosine Compared with Zidovudine and Didanosine in Patients with HIV-1 Infection: A Randomized, Double-Blind, Placebo-Controlled Trial

Strategies to improve the clinical benefit of therapy for human immunodeficiency virus type 1 (HIV-1) infection have included combining antiretroviral drugs to increase antiviral activity. Some combinations of two HIV-1 reverse transcriptase inhibitors synergistically inhibit HIV-1 replication in vitro; these combinations include that of the nucleoside analogues zidovudine and didanosine [1, 2] and that of zidovudine and the non-nucleoside reverse transcriptase inhibitor nevirapine [3-5]. The combination of zidovudine and didanosine also enhances antiviral activity in vivo [6-8] and delays disease progression [9-11] more effectively than zidovudine monotherapy. One way to further suppress HIV-1 replication may be to add a third antiretroviral agent to a combination regimen. Certain three-drug regimens, including the combination of zidovudine, didanosine, and a non-nucleoside reverse transcriptase inhibitor such as nevirapine, inhibit wild-type HIV-1 in vitro more effectively than one or two of these drugs [12-15]. Nevirapine (400 mg/d), as monotherapy or in combination with zidovudine or zidovudine and didanosine, has resulted in sustained antiviral effect in vivo, although nevirapine-resistant virus was isolated from patients in open-label trials [16-18] and from in vitro selection experiments [19, 20]. No adverse drugdrug interactions were noted in patients receiving the triple combination of nevirapine, zidovudine, and didanosine over a short period [18]. Therefore, we tested whether this triple combination would improve immunologic and virologic effects in vivo by comparing it with a combination of zidovudine and didanosine in a 48-week phase II, randomized clinical trial in adults with HIV-1 disease who had previously received prolonged nucleoside therapy. Methods Study Design and Treatment Regimens This multicenter, randomized trial was AIDS (acquired immunodeficiency syndrome) Clinical Trials Group Protocol 241. Patients received either nevirapine with open-label zidovudine and didanosine (the triple combination) or placebo with open-label zidovudine and didanosine (the double combination). The placebo tablets were identical in appearance to the active nevirapine tablets. Patients and investigators were blinded to treatment assignments; a permuted-blocks design within each institution was used for randomization. Patients were stratified according to their screening CD4 cell counts: 50 or fewer cells/mm3, 51 to 200 cells/mm3, and 201 to 350 cells/mm3. Zidovudine (Retrovir, provided by Glaxo Wellcome, Research Triangle Park, North Carolina) was given orally as two 100-mg tablets three times a day. Didanosine (Videx, provided by Bristol-Myers Squibb, Wallingford, Connecticut) was given orally as two 100-mg chewable and dispersable tablets twice daily for patients weighing at least 60 kg and as one 100-mg tablet and one 25-mg tablet twice daily for patients weighing less than 60 kg. Nevirapine (Viramune, provided by Boehringer-Ingelheim Pharmaceuticals, Ridgefield, Connecticut) was given orally as a 200-mg tablet once daily for the first 2 weeks and thereafter as one 200-mg tablet twice daily. This schedule was used because a lead-in period with a lower daily dose of nevirapine had decreased the frequency of nevirapine-related rashes in earlier studies [17]. Data were gathered, analyzed, and interpreted independently of the pharmaceutical companies that provided the drugs, according to the standard operating procedures of the AIDS Clinical Trials Group. Study Sample Adults who had documented HIV-1 infection and CD4 cell counts of 350 cells/mm3 or less within 30 days of randomization and who had had previous nucleoside therapy with zidovudine, didanosine, or zalcitabine for at least 6 months were eligible. Eligibility criteria also included a Karnofsky performance status score of at least 70% within 30 days of randomization, a hemoglobin concentration of at least 91 g/L or more for men and 88 g/L for women, a neutrophil count of 1000 cells/mm3 or more, a platelet count of 75 000 109/L or more, a serum creatinine concentration no more than 1.5 times the upper limit of normal, serum concentrations of alanine aminotransferase and aspartate aminotransferase no more than 3 times the upper limit of normal, and a serum amylase concentration no more than 1.5 times the upper limit of normal (unless the serum lipase concentration was 1.5 times the upper limit of normal or less). Patients were excluded if they were intolerant of zidovudine (at 500 or 600 mg/d) or didanosine (at 400 mg/d for tablets and 500 mg/d for sachets), had moderate peripheral neuropathy ( grade 2 according to the National Institute of Allergy and Infectious Diseases [NIAID] Division of AIDS Table for Grading Adult Adverse Experiences), had pancreatitis, or had previously used non-nucleoside reverse transcriptase inhibitors. The study was approved by the institutional review board at each institution, and all participants gave written informed consent. Concomitant therapy with other antiretroviral agents, foscarnet, biological response modifiers, erythromycin, clavulanate-containing antibacterial agents, warfarin, phenytoin, or phenobarbital was not permitted. Prophylaxis for Pneumocystis carinii pneumonia was required for all patients with a CD4 cell count of 200 cells/mm3 or less or a history of P. carinii pneumonia. Maintenance therapies for other opportunistic infections were permitted. Patients could continue their prestudy antiretroviral nucleoside therapy until the day on which therapy with the study medications was started. Management of Toxicities Toxicity was graded according to the NIAID Division of AIDS Table for Grading Adult Adverse Experiences. Modification, interruption, or discontinuation of therapy with the study medications was done for many adverse effects one drug at a time, starting with the drug most likely to have caused the toxicity. Zidovudine was the first drug to be modified for severe anemia, myositis, neutropenia, fatigue, and headache; didanosine was the first to be modified for severe nausea, vomiting, diarrhea, constipation, hyperamylasemia, fasting hypertriglyceridemia, hyperuricemia, and peripheral neuropathy; and nevirapine or placebo was the first to be modified for rash, severe thrombocytopenia, and adverse neuropsychological effects. Therapy with all study medications was interrupted for other severe adverse experiences, including hepatotoxicity. Therapy with a medication or medications was interrupted until the toxicity resolved and was then resumed at half the original dose, except that didanosine therapy was permanently discontinued for pancreatitis and nevirapine or placebo use was permanently discontinued for severe rash. Recurrent or persistent adverse effects led to the permanent discontinuation of either zidovudine or didanosine therapy. All study treatment was stopped if therapy with nevirapine or placebo or any two study medications was permanently discontinued. Patient Evaluation The schedule of patient evaluations is shown in Table 1. Standardized assays were used for CD4 cell counts [21, 22] and serum p24 antigen levels (AIDS Clinical Trials Group Virus Quality Assurance Laboratory reference standards were used with enzyme-linked immunosorbent assay kits from either Coulter [Hialeah, Florida], Abbott Laboratories [North Chicago, Illinois], or DuPont [Wilmington, Delaware]). Plasma nevirapine concentrations were measured at Boehringer-Ingelheim Pharmaceuticals by a validated high-performance liquid chromatography assay [23]. Additional virologic and pharmacologic assessments were done on specimens from all patients enrolled at 8 of the 16 study sites (n = 198). The HIV-1 infectivity titers in peripheral blood mononuclear cells were calculated by using maximum likelihood estimation from a standardized HIV-1 quantitative microculture assay in quality-assured AIDS Clinical Trials Group virology laboratories [24]. Plasma HIV-1 RNA levels were measured by quantitative reverse transcriptase polymerase chain reaction (Roche Molecular Systems, Alameda, California, and Branchburg, New Jersey) done in batch at Roche Biomedical Laboratories (Research Triangle Park, North Carolina) [25]. Plasma zidovudine and didanosine concentrations were measured at the University of Alabama at Birmingham by validated radioimmunoassays [26, 27]. Viruses isolated at entry were classified as either syncytium-inducing or non-syncytium-inducing according to the results of an MT-2 cell assay [28]. Table 1. Schedule of Patient Evaluations Primary outcome measures were differences between treatment groups at the end of the study in mean absolute CD4 cell count, HIV-1 infectivity titer in peripheral blood mononuclear cells, serum p24 antigen level, and time to HIV-1 disease progression or death. Secondary outcome measures were differences between treatment groups at the end of the study in the mean percentage of T lymphocytes that were CD4 cells and in plasma HIV-1 RNA levels. These measurements at the end of the study were the geometric means of measurements obtained between weeks 40 and 48, expressed as the change from the geometric mean of the two measurements made before treatment. Standardized area-under-the-curve analyses of immunologic and virologic measures over time were additional secondary outcome measures used to assess differences between treatments that included short-term effects. Progression of HIV-1 disease was defined as the development of a new AIDS-defining clinical event according to the Centers for Disease Control and Prevention case definition (except that we excluded CD4 cell count as a disease progression criterion) [29], a newly diagnosed deep-seated bacterial infection or bacteremia unrelated to the use of injection drugs or an intravascular catheter, 1 month or more of symptomatic microsporidiosis, or the recurrence of either P. carinii pneumonia or central nervous system toxoplasmosis. All disease prog

Monitoring plasma HIV-1 RNA levels in addition to CD4+ lymphocyte count improves assessment of antiretroviral therapeutic response

The duration of disease-free survival after infection with human immunodeficiency virus type 1 (HIV-1) varies considerably during antiretroviral therapy. Patients with similar CD4+ lymphocyte counts progress at different rates when they are given the same antiretroviral therapy. Better prediction of risk for progression and its association with viral suppression may help improve antiretroviral management for individual patients and speed the development of new drugs. Higher plasma HIV-1 RNA levels are associated with poorer clinical status and lower CD4+ lymphocyte counts [1-3] and predict subsequent outcome [4-11]. The biological variability of plasma HIV-1 RNA levels in patients receiving stable therapeutic regimens must be quantified to define the magnitude of an antiviral effect that can be reliably detected after antiretroviral treatment is initiated. Determination of infectious HIV-1 titers in mononuclear cells of peripheral blood by quantitative microculture [12, 13] or syncytium-inducing phenotype of an HIV-1 isolate may provide information that is different from or complementary to the information gleaned from measuring plasma HIV-1 RNA levels [14-16]. However, studies have not yet conclusively determined whether measurements of CD4+ lymphocytes in conjunction with any or all of these virological variables should be recommended to optimize prediction or guide antiretroviral treatment more effectively. In this report, we quantify the relative roles of CD4+ lymphocyte counts, plasma HIV-1 RNA levels, infectious HIV-1 titers in mononuclear cells of peripheral blood, and the syncytium-inducing viral phenotype as predictors of disease progression during a clinical trial of combination therapy [17]. Our approach was to assess the value of plasma HIV-1 RNA levels and CD4+ lymphocyte count, both of which are readily available to clinicians, and then to assess the additional value of the infectious HIV-1 titer in mononuclear cells of peripheral blood and the syncytium-inducing viral phenotype. We also quantify the variability of plasma HIV-1 RNA levels. Our results suggest guidelines for using these measures in clinical practice for predicting the effectiveness of antiretroviral therapy over 1 year. Methods Study Design We prospectively evaluated virological, immunologic, and clinical data from patients who participated in the intensive virology substudy of ACTG (AIDS Clinical Trials Group) Protocol 241; ACTG Protocol 241 was a multicenter, randomized, double-blind, placebo-controlled trial of 398 patients receiving nevirapine, zidovudine, and didanosine compared with zidovudine and didanosine [17]. All patients at 8 of the 16 AIDS Clinical Trials Units who participated in the main study were enrolled in the substudy (n = 198). For 48 weeks, all 198 patients received open-label zidovudine (600 mg/d) and didanosine (400 mg/d for patients weighing 60 kg and 250 mg/d for patients weighing <60 kg). One hundred of the substudy patients were randomly assigned to receive nevirapine (200 mg/d for the first 2 weeks and 400 mg/d thereafter), and 98 were assigned to receive matching placebo. Participants gave written informed consent, and the protocol was approved by the institutional review board at each participating AIDS Clinical Trials Unit. The study was funded by the ACTG of the National Institute of Allergy and Infectious Diseases; supplemental funding for virology was provided by Boehringer Ingelheim Pharmaceuticals (Ridgefield, Connecticut). Study drugs were provided by Glaxo Wellcome (Research Triangle Park, North Carolina), Bristol-Myers Squibb (Princeton, New Jersey), and Boehringer Ingelheim Pharmaceuticals. However, all data were gathered by members of the ACTG and were analyzed and interpreted by the authors, who had sole responsibility for the decision to submit the manuscript for publication. Evaluation of Patients Stable therapy at baseline was defined as the absence of reported change in antiretroviral therapy from 30 days before the preentry visit until the entry visit. All patients were followed prospectively for progression of HIV-related disease. Progression was defined as the development of a new acquired immunodeficiency syndrome (AIDS)-defining event [18]; a newly diagnosed, deep-seated bacterial infection or bacteremia that was not related to injection drug use or an intravascular catheter; pulmonary or extrapulmonary tuberculosis; recurrent Pneumocystis carinii pneumonia; recurrent toxoplasmosis of the central nervous system; or death. Reports of disease progression were reviewed by the study chair; only events that could be confirmed were used in the analysis. We measured CD4+ lymphocyte counts, plasma HIV-1 RNA levels, and infectious HIV-1 titers in mononuclear cells of peripheral blood at the preentry visit (within 14 days of starting study treatment), at the entry visit (before starting study treatment and at least 72 hours after the preentry visit), and at the visits 8 and 48 weeks after the start of study treatment. Specimens could be obtained at any time of day. We used the geometric mean of preentry and entry measurements as the baseline value for each variable. The presence of the syncytium-inducing viral phenotype was determined at the entry visit. Standardized assays were used to determine CD4+ lymphocyte counts [19, 20], infectious HIV-1 titer in mononuclear cells of peripheral blood (in infectious units per million cells) using real-time testing [13, 21], and syncytium-inducing viral phenotype of a virus isolated from mononuclear cells of peripheral blood using MT-2 cells [22]. Plasma samples were frozen at 70C; HIV-1 RNA levels were measured by quantitative reverse transcription polymerase chain reaction assay (Roche Molecular Systems, Alameda, California, and Branchburg, New Jersey) [23]. The lower limit of detection for this assay was 200 HIV-1 RNA copies/mL. Levels of HIV-1 RNA in plasma samples collected from the same patient at the preentry, entry, week 8, and week 48 visits were determined in a single laboratory assay. Statistical Analysis Analysis of plasma HIV-1 RNA levels and infectious HIV-1 titers in mononuclear cells of peripheral blood was done after log10 transformation. Plasma levels of HIV-1 RNA that were below the detectable limit were assigned the value of 200 copies/mL. Infectious HIV-1 titers in mononuclear cells of peripheral blood outside the measurable range (0.22 to 7493 infectious units per million cells) were assigned the value of 0.22 infectious units per million cells if they were below the range and 7493 infectious units per million cells if they were above the range. Linear regression analysis [24] was used to compare the mean plasma HIV-1 RNA levels, infectious HIV-1 titers in mononuclear cells of peripheral blood, and CD4+ lymphocyte counts according to patient characteristics at baseline and to assess factors associated with the long-term change (from baseline to week 48) in CD4+ lymphocyte counts. Logistic regression analysis [25] was used to assess the association at baseline of the percentage of patients who had AIDS with virological measures and CD4+ lymphocyte counts. The intrapatient SD of plasma HIV-1 RNA levels was estimated using the method of moments for variance components [26]. Spearman correlation coefficients were used to assess the association between preentry and entry measurements. Proportional hazards models [27] were used to assess the association between the risk for disease progression or death and baseline levels and early changes (from baseline to week 8) in plasma HIV-1 RNA levels, infectious HIV-1 titers in mononuclear cells of peripheral blood, and log-transformed CD4+ lymphocyte counts as well as baseline syncytium-inducing viral phenotype. These models were stratified by study treatment to control for any differential effects of the two study regimens. Results Patient Characteristics at Study Entry The mean CD4+ lymphocyte count of the 198 patients before treatment was 145 cells/mm3 (range, 1 to 443 cells/mm3). Patients were a median of 39 years of age, predominantly male (81%), predominantly white (76%), and predominantly free of a previous AIDS-defining diagnosis (86%). All but 3 patients had taken zidovudine before study entry, 44% had taken didanosine, and 35% had taken zalcitabine. The median duration of cumulative previous nucleoside therapy was 25 months, and 34% of patients had received therapy for longer than 36 months. Virological Measures at Baseline by Patient Characteristics Table 1 shows the mean plasma HIV-1 RNA levels, infectious HIV-1 titers in mononuclear cells of peripheral blood, and CD4+ lymphocyte counts at baseline for patients stratified by characteristics that were significantly associated with viral load. We also assessed the associations with age, sex, racial or ethnic group, self-reported homosexuality, and duration of previous nucleoside therapy, but these associations were not significant. Table 1. Plasma HIV-1 RNA Level, Infectious HIV-1 Titer in Mononuclear Cells of Peripheral Blood, and CD4+ Lymphocyte Count at Baseline* Patients with a history of AIDS had a significantly higher mean baseline level of HIV-1 RNA in plasma and a significantly lower mean CD4+ lymphocyte count than did those without such a history (Table 1). More patients with a history of AIDS than those without had baseline HIV-1 isolates with the syncytium-inducing viral phenotype (58% compared with 36%; P = 0.015). However, in a multivariate analysis, only the CD4+ lymphocyte count at baseline was significantly associated with a history of AIDS. Thus, disease status at baseline was explained by CD4+ lymphocyte counts and not by any of the virological measures that were considered. Variability of Virological Measures in Patients Receiving Stable Treatment Variation in plasma HIV-1 RNA levels was evaluated by comparing the preentry and entry measures from the 167 patients who reported no changes in treatment from 30 days

Phase 2 Study of the Safety and Efficacy of Vicriviroc, a CCR5 Inhibitor, in HIV-1-Infected, Treatment-Experienced Patients: AIDS Clinical Trials Group 5211

BACKGROUND Vicriviroc, an investigational CCR5 inhibitor, demonstrated short-term antiretroviral activity in a phase 1 study. METHODS The present study was a double-blind, randomized phase 2 study of vicriviroc in treatment-experienced, human immunodeficiency virus (HIV)-infected subjects experiencing virologic failure while receiving a ritonavir-containing regimen with an HIV-1 RNA level >or=5000 copies/mL and CCR5-using virus. Vicriviroc at 5, 10, or 15 mg or placebo was added to the failing regimen for 14 days, after which the antiretroviral regimen was optimized. The primary end point was the change in plasma HIV-1 RNA levels at day 14; secondary end points included safety/tolerability and HIV-1 RNA changes at week 24. RESULTS One hundred eighteen subjects were randomized with a median HIV-1 RNA level of 36,380 (4.56 log(10)) copies/mL and a median CD4 cell count of 146 cells/mm(3). At 14 days and 24 weeks, mean changes in HIV-1 RNA level (log(10) copies/mL) were greater in the vicriviroc groups (-0.87 and -1.51 [5 mg], -1.15 and -1.86 [10 mg], and -0.92 and -1.68 [15 mg]) than in the placebo group (+0.06 and -0.29) (P<.01). Grade 3/4 adverse events were similar across groups. Malignancies occurred in 6 subjects randomized to vicriviroc and in 2 to placebo. CONCLUSIONS In HIV-1-infected, treatment-experienced patients, vicriviroc demonstrated potent virologic suppression through 24 weeks. The relationship of vicriviroc to malignancy is uncertain. Further development of vicriviroc in treatment-experienced patients is warranted.