Reviving protease inhibitors: new data and more options.
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Biomedical subjects
Publications and source records attributed to Robert L Murphy.
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OBJECTIVE: To compare one protease inhibitor (PI)-based and two PI-sparing antiretroviral therapy regimens. METHODS: International, open label, randomized study of antiretroviral drug-naive patients, with CD4 lymphocyte counts >/= 200 x 106 cells/l and plasma HIV-1 RNA levels > 500 copies/ml. Treatment assignment to stavudine and didanosine plus indinavir or nevirapine or lamivudine. Primary study endpoint was the percentage of patients with plasma HIV-1 RNA levels < 500 copies/ml after 48 weeks in the intention-to-treat analysis (ITT). RESULTS: In total, 298 patients were enrolled. After 48 weeks, the percentage of patients in the indinavir, nevirapine and lamivudine arms with HIV-1 RNA < 500 copies/ml was 57.0%, 58.4% and 58.7%, respectively, in an ITT analysis. After 96 weeks of follow-up, these percentages were 50.0%, 59.6% and 45.0%, respectively. The percentage of patients with HIV-1 RNA < 50 copies/ml was significantly less for those allocated to lamivudine in an on-treatment analysis after 48 and 96 weeks of follow-up. Patients in the nevirapine arm experienced a smaller increase in the absolute number of CD4 T lymphocytes. There were no significant differences in the incidence of serious adverse events. CONCLUSIONS: A comparable virological response can be achieved with first-line PI-base and PI-sparing regimens. The triple nucleoside regimen utilized may be less likely to result in viral suppression to < 50 copies/ml, while the nevirapine-based regimen is associated with a lower increase in CD4 T lymphocytes.
OBJECTIVES: The primary objective was to determine the long-term safety of the subcutaneous self-administration of enfuvirtide. Secondary objectives included the determination of enfuvirtide pharmacokinetics and antiviral activity and the immunological response to the enfuvirtide-containing regimen. METHODS: A multicenter 48-week uncontrolled open-label rollover study was conducted on 71 HIV-infected adults recruited from previous enfuvirtide clinical trials. Patients with extensive previous use of protease and reverse transcriptase inhibitors received a twice-daily dose of 50 mg enfuvirtide subcutaneously (45 mg deliverable) combined with two or more antiretroviral drugs selected for each individual, guided by resistance testing and previous treatment history. RESULTS: The mean baseline plasma HIV-RNA level was 4.81 log(10) copies/ml and the mean CD4 cell count was 134.8 cells/microl. The majority (86.9%) of treatment-emergent adverse events were grade 2 or less in severity. Injection site reactions were common, but no patients discontinued treatment. A mean HIV-RNA change of -1.33 log(10) was achieved within 14 days of treatment initiation. At week 48, approximately one-third of all patients in the intent-to-treat population maintained significant suppression of plasma HIV RNA, with either less than 400 copies/ml or more than a 1.0 log(10) decline from baseline. The mean gain in absolute CD4 cell counts at 48 weeks was 84.9 cells/microl. Trough plasma concentrations of enfuvirtide were consistently higher than target concentrations. CONCLUSION: Self-administration of enfuvirtide is not associated with unexpected toxicities for up to one year, and combined with oral antiretroviral drugs was associated with a significant decrease in HIV RNA and an increase in CD4 cell counts.
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Effective highly active antiretroviral therapy (HAART) for human immunodeficiency virus type 1 is associated with virus suppression and immune reconstitution. However, in some patients, this reconstitution is partial or incomplete because CD4(+) cell counts do not increase significantly. This may be due to damage in the microenvironment of lymphoid tissues (LTs), where CD4(+) T cells reside. To test this hypothesis, LT samples were obtained from 23 patients enrolled in a prospective trial that compared 3 different HAART regimens. Analysis of LT architecture and CD4(+) T cells populations revealed abnormalities in 100% of the LT samples, especially in the follicles, with 43% showing absence, 14% showing regression, and 43% showing hyperplasia. CD4(+) T cell populations were abnormal in 16 (89%) of 18 tissue samples, with 7 (39%) of 18 decreased by >50% of normal levels. These data are consistent with the hypothesis that persistent abnormalities in the microenvironment can influence immune reconstitution and document persistent LT abnormalities with HAART not detected by measures of peripheral CD4(+) T cell count.
Filgrastim, or granulocyte colony-stimulating factor, reverses neutropenia associated with human immunodeficiency virus type 1 (HIV-1) and cytomegalovirus (CMV) infections. During a trial of anti-CMV retinitis therapies coadministered with antiretroviral therapy, 2-4 plasma specimens of HIV-1 RNA were collected from 36 HIV-1-infected patients receiving filgrastim to prevent neutropenia and from 36 patients not receiving filgrastim. For both groups, the crude mean and mean rate of change of HIV-1 log(10) RNA levels were similar. Adjustment for covariates (CD4(+) T cell lymphocytes, virus load at enrollment, level of neutropenia and antiretroviral therapy [mainly non-highly active antiretroviral therapy], and anti-CMV therapy during follow-up) resulted in a mean log(10) HIV-1 RNA level for individuals receiving filgrastim versus those not receiving the drug of 5.11 versus 4.87 (P=.12) and respective log mean rates of change per month of -0.08 versus -0.21 (P=.08). This latter difference has borderline statistical significance, which suggests that filgrastim may reduce the decline of HIV-1 RNA loads.
Enfuvirtide (T-20) is a novel antiretroviral agent that blocks HIV-1 cell fusion. A 28-day randomized dose-comparison study was conducted to determine the safety, pharmacokinetics, and antiviral activity of enfuvirtide in 78 HIV-infected adults, most with extensive treatment experience. Patients received enfuvirtide, added to a failing regimen, either by continuous subcutaneous infusion (CSI: 12.5, 25, 50 or 100 mg/day) or by subcutaneous (SC) injection (50 or 100 mg twice daily). Dose-related decreases in viral load were observed, with a maximum mean reduction from baseline of 1.6 log(10) copies/ml (p< 0.001) seen in the 100 mg bid SC group. Most responses diminished by 28 days. Plasma pharmacokinetics and antiviral responses were more consistent for SC injection than for CSI because of technical difficulties experienced with CSI. Injection site reactions were common but generally mild. These results indicate that enfuvirtide is a promising new therapeutic agent for HIV-infected patients, including those with prior antiretroviral treatment.
The AIDS Clinical Trials Group Study 850 (ACTG 850) evaluated the penetration of zidovudine (ZDV), lamivudine (3TC), and amprenavir (APV), given alone and in combination with the 2 nucleoside analogues, into the male genital tract, because these factors may affect human immunodeficiency virus (HIV) type 1 suppression and transmission. Nineteen men receiving APV monotherapy and 12 men receiving triple therapy donated blood plasma (BP) and seminal plasma (SP) during therapy. Paired SP and BP were used to calculate compartmental concentration ratios. APV SP concentrations were consistently lower than BP concentrations, ZDV SP concentrations approximated BP concentrations early but became greater later in the dosing interval, and 3TC SP concentrations were substantially greater than BP concentrations throughout. Observed SP concentrations plotted with population BP concentration-time curves confirmed these findings, suggesting that passive diffusion (APV), slowed elimination (ZDV), and either active accumulation and/or inhibition of elimination (3TC) are responsible for SP concentrations of these agents. The antiretroviral effect of APV monotherapy was related to APV concentrations.
The safety and antiviral activity of lopinavir (Lpv), a protease inhibitor (PI) coformulated with ritonavir (Rtv) to enhance its pharmacokinetic properties, were evaluated in 70 patients with plasma human immunodeficiency virus type 1 (HIV-1) RNA levels of 1000-100,000 copies/mL on a first PI-containing regimen. Patients were randomized to substitute only the PI with Lpv/Rtv, 400/100 mg or 400/200 mg twice daily. On day 15, nevirapine (200 mg 2x/day) was added, and nucleoside reverse-transcriptase inhibitors were changed. Despite a >4-fold reduction in phenotypic susceptibility to the preentry PI in 63% of patients, mean plasma HIV-1 RNA levels declined by 1.14 log(10) copies/mL after 2 weeks of Lpv/Rtv. At week 48, 86% of subjects receiving treatment had plasma HIV-1 RNA levels of <400 copies/mL; 76% had levels <50 HIV-1 RNA copies/mL (intent-to-treat: 70% and 60%, respectively). Mean CD4 cell counts increased by 125 cells/muL. Three patients discontinued therapy for drug-related adverse events.
PURPOSE: To describe the characteristics of patients with AIDS and cytomegalovirus retinitis in the era of highly active antiretroviral therapy (HAART). METHODS: Prospective cohort study. Baseline (enrollment) data were compared between patients with newly diagnosed cytomegalovirus retinitis (incident cases) and those with previously diagnosed cytomegalovirus retinitis (prevalent cases). RESULTS: As of December 31, 2000, 45 incident and 200 prevalent cases had been enrolled. Among prevalent cases, the median time from cytomegalovirus retinitis diagnosis was 2.9 years. Incident cases were more likely than prevalent cases to be women (35.4% vs 15.3%, P =.001), African American (45.4% vs 20.4%, P =.002), and uninsured (29.6% vs 7.6%, P <.001). Incident cases were less likely than prevalent cases to be on HAART (51.2% vs 77.6%, P =.001) and to have had an immunologic response to HAART (increase in CD4(+) T-cell count to > 100 cells/microl) (12.2% vs 57.5%, P <.001). The median CD4(+) T-cell count at enrollment among incident cases was 17 cells/microl and among prevalent cases was 159 cells/microl (P <.001). Immune recovery uveitis had been diagnosed in 15.5% of the prevalent cases. Sixty-three percent of prevalent cases were not on anticytomegalovirus therapy. CONCLUSIONS: There is a population of patients with previously diagnosed and longstanding cytomegalovirus retinitis who have experienced immune recovery as a consequence of HAART and are no longer receiving anticytomegalovirus therapy. There are demographic differences between incident and prevalent cases that may reflect the evolution of the AIDS epidemic and differences in utilization of health care services.
Pathologic findings attributed to human immunodeficiency virus (HIV) infection and acquired immune deficiency syndrome (AIDS) are described in the spleen in studies that encompassed the years preceding highly active anti-retroviral therapy (HAART). Major findings included white-pulp depletion, hemosiderin deposition, spindle cell proliferations, and perivascular hyalinization. Infectious and malignant infiltrates were commonly noted and characterized. The histopathology of AIDS autopsy spleens since the introduction of protease inhibitors has not been studied. Histologic sections from 168 cases of AIDS spleens examined at autopsy over a 19-year period (1982-2000) were evaluated for significant pathologic findings. Multiple morphologic parameters were recorded, including a graded estimation of white-pulp depletion. Significantly less white-pulp depletion was observed in the 39 HAART-era spleens (1995-2000) compared with the 129 spleens from the 1982-1994 patient group (P =.001). The rates of splenic involvement by atypical mycobacteria and cytomegalovirus were similar to those in the past, although the overall clinical rates of these opportunistic infections were found to be decreased. The annual numbers of AIDS autopsies have decreased, reflecting a nationwide trend of lower autopsy rates. Increased survival with HIV infection and AIDS is now apparent. Protease inhibitors, in conjunction with other contemporary therapies, may have contributed to the preservation of white pulp observed in the HAART patient group.