Although recent advances in the treatment and monitoring of HIV-1 infection have substantially diminished HIV-associated illness and mortality, the management of HIV-infected patients has become increasingly complex. Both the acute and long-term toxicities of the common antiretroviral medications are becoming better understood and continue to complicate the successful management of this condition. Alternative treatment strategies are clearly needed, both for patients with access to HAART and, on a worldwide basis, particularly for the much greater number of patients with little or no access to these expensive therapies. Our clinical research continues to address several important aspects of the following questions: how to dose anti-retroviral drugs; how to design alternative therapies for those patients who fail to respond to anti-retroviral therapy with sustained maximal viral load suppression; what is the mechanism for and clinical importance of the HIV-associated lipodystrophy syndrome; what happens to viral load and other measures after the discontinuation of successful anti-retroviral therapy, and whether HAART-sparing strategies are both effective and worthwhile. We continue our efforts to improve access to clinical trials by local minority populations through an outreach that includes a close relationship with local clinics for the medically under-served.In patients who had undetectable levels of plasma viremia during combination antiretroviral therapy for more than 1 year, we have demonstrated that discontinuation of antiviral therapy promptly results in substantial viral relapse. The kinetics of this relapse appear unrelated either to the pre-cessation level of infection within the resting, latently-infected CD4 cell pool or to prior therapy with interleukin-2 when given in an effort to help lower viral levels within this pool. The source of rebounding virus in this setting remains elusive, although these data suggest that the resting, latently-infected pool may not be a major contributor in this regard. Within two months of treatment cessation lymph node histology begins to revert to a state similar to primary infection in some cases. Further, the rate of peripheral lymphocyte turnover appears to accelerate markedly upon withdrawal of antiretroviral therapy and to return to baseline levels shortly after re-introduction of HAART, strongly suggesting that viral activity directly influences the rate of CD4 proliferation. CD8 cytotoxic activity and intracellular cytokine expression also increase following treatment cessation and viral relapse, although this heightened activity is unable to effect strong control over viral replication. Following resumption of drug therapy, however, restoration of control over plasma viremia is rapidly restored with no evidence to date of viral resistance to combination drug therapy.Patients with antiretroviral therapy-associated lipodystrophy were also studied before and after treatment interruption. A relatively brief interruption of HAART resulted in significant improvements in total cholesterol, LDL cholesterol, and triglyceride levels. No changes were observed in insulin resistance profiles or anthropometric measurements, perhaps due to the brief duration of HAART interruption. These results suggest that hyperlipidemia and alterations in corticosteroid metabolism in the setting of HAART are a direct drug effect that reverses with drug withdrawal. However, glucose metabolism and fat redistribution do not change over the short term.Another major focus of this project has been to characterize the immunologic abnormalities associated with HIV infection, develop immunologic approaches to the therapy of patients with HIV infection, and utilize these immune based therapies as tools for obtaining additional insights into the pathophysiologic mechanisms present in patients with HIV infection. Specifically, this project is aimed at reversing the CD4 cell decline associated with progressive HIV-1 infection through the use of subcutaneous administration of interleukin-2. A series of randomized phase I-II studies have been carried out that have established this as a feasible method for increasing the CD4 count in patients with HIV infection; these studies have been extended to optimize the dosing regimens for maximal immunologic and virologic benefit while minimizing side effects. Cohorts of patients are being followed who have received this treatment for periods that now extend beyond 8 years. Four separate Vanguard trials of subcutaneous IL-2 have now been completed in Argentina, Thailand, Houston, and the United Kingdom in a successful effort to extend these observations to other populations. The laboratory continues to be engaged in an extensive series of collaborations with a large number of extramural colleagues, both in the US and abroad, to further this project in the context of two major randomized phase III international clinical endpoint trials. The goal of these studies is to determine whether the favorable effects of IL-2 therapy on CD4 cell number translate into a significant delay in the onset of AID-defining conditions and/or death in recipients of IL-2 plus antiretrovirals versus patients on antiretoviral therapy alone. Already the results of one multicenter trial of IL-2 suggest that this agent may induce a small but statistically significant decrease in levels of plasma virus compared to recipients of antiretrovirals alone.Interleukin-2 (IL-2) is also being studied for its potential role in supplementing HAART therapy and for its varied effects on cytokine expression. Specifically we are examining the effect of HAART therapy with IL-2 treatment on the reservoir of latent virus and on certain components of the immune system, compared to HAART alone. Analyses will include quantification of competent virus, characterization of lymphocyte subsets, intracellular cytokine staining, and assays for protective immune responses.
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