Antiviral Activity of Peg-IFN-Alpha-2A in Chronic HIV-1 Infection

The high toxicity of current Anti-Retroviral Therapy (ART) regimens has driven a number of studies investigating therapeutic approaches aimed at reducing drug exposure while maintaining the beneficial effects of immune reconstitution. Preliminary observations in HCV/HIV co-infected individuals already support an antiviral effect by Pegylated Interferon-Alpha-2A (Peg-IFN-Alpha-2A:Pegasys®) on HIV-1 replication; however, the ability of Peg-IFN-Alpha-2A (as a single agent) to maintain long-term suppression of HIV-1 replication in patients who interrupt ART after having achieved immune reconstitution remains undetermined. The rationale for addressing two doses of Peg-IFN-Alpha-2A (180 and 90 ug/week) is based on the antiviral activity reported with both doses and the lower incidence of adverse events associated with doses lower than that approved for HCV therapy (90 versus 180ug/week). The long-range goal of this proposal is to determine if Peg-IFN-Alpha-2A monotherapy can sustain HIV-1 suppression in the absence of ART in infected individuals. Our short-range goal is to determine the safety, viral suppressive potential and immune correlates of Peg-IFN-Alpha-2A administered upon the cessation of suppressive ART. Based on the current literature and our preliminary studies, we hypothesize that weekly doses of 90 or 180 ug/wk of Peg-IFN-Alpha-2A administered to pharmacologically-suppressed HIV-infected individuals in the course of antiretroviral therapy (ART) discontinuation will result in equivalent frequency of viral control, with the lower dose resulting in measurably lower rate and intensity of therapy-related adverse events (AE). We propose to compare two different doses of Peg-IFN-Alpha-2A (90 or 180 ug/wk) as a simplification step to ART, for their ability to maintain viral load suppression when initiated 5 weeks before ART interruption in HIV-infected, ART-suppressed patients (VL\<50 copies/ml). Briefly, control will be determined by the the percentages of viral load measurements \<400 copies/ml between the two arms over a period of 24 weeks, corresponding to the Pegasys monotherapy period (exclusive of dual ART/Pegasys 5-week period). A threshold of 400 is used based on the known potential for blipping on ART between 50 and 400 copies/ml with no clinical consequence to sustained suppression thereafter (JAMA 2005, 293:817-829). Primary analysis will be an "intent to treat" analysis and will address the hypothesis that two different doses of Peg-IFN-Alpha-2A (90 and 180 ug/week) will be similarly effective at inhibiting viral replication. The secondary objectives of the research are: 1. To prospectively evaluate dose-dependent, treatment-associated toxicity, safety and tolerability of 29 weekly doses of Peg-IFN-Alpha-2A at 180 ug or 90 ug/week (in association with ART for the initial 5 weeks, followed by 24 weeks of Peg-IFN-Alpha-2A in the absence of ART). 2. To determine innate immunity outcomes correlated to Peg-IFN-Alpha-2A dose and antiviral activity by monitoring Natural Killer (NK) and Dendritic cell (DC) subsets changes and the ability to maintain innate immune function (DC secretory responses, NK antiviral cytotoxic responses) 3. To determine adaptive immunity outcomes correlated to Peg-IFN-Alpha-2A dose and antiviral activity by monitoring T-cell subsets changes and the ability to maintain cell-mediated proliferative and cytokine responses against recall antigens (anti-HIV-1 gag p55).