Immunologic and Virologic Studies of Intermittent Versus Continuous HAART in the Treatment of HIV Disease

Although highly active antiretroviral therapy (HAART) has been successful in suppressing plasma HIV RNA levels in infected patients, it has not resulted in eradication of virus. It is now clear that virus replication persists despite undetectable plasma viremia in individuals receiving HAART. In this regard, withdrawing HAART, even after prolonged periods of virus suppression, leads to an almost universal rapid rebound of plasma viremia. It is also now clear that prolonged, continuous HAART carries a risk of significant toxicity and side effects. These recent observations may argue for a different approach to HAART with the goals of: 1) durable suppression of virus replication, without an attempt at eradication, and; 2) minimization of toxicity and side effects and improvement in patient life-style. Therefore, we propose to study the virologic and immunologic effects of intermittent versus continuous HAART in HIV-infected individuals as a possible means to achieve these goals. The primary protocol, Cohort 1, will be a randomized controlled study of 45 individuals receiving continuous HAART and 45 individuals receiving intermittent HAART with intervals of one month off therapy followed by two months on therapy. A second cohort of 10 individuals will serve as a pilot study of 2 arms of 5 patients each to evaluate the potential of shorter on-off cycles to maintain suppression of plasma virus and boost HIV-specific immune responses. An extension of Cohort 2 will add 5 patients to the 7 days on/ 7 days off HAART arm with modified exclusion criteria and procedure schedule. Cohort 3 will be a pilot study of 5 individuals who will received 4 days off HAART followed by 3 days on HAART. Cohort 4 will be a pilot study of 8 individuals who will receive a once-daily HAART regimen administered as short cycle intermittent therapy of 7 days off drugs followed by 7 days on drugs. Cohort 5 will be a pilot study of 5 individuals who will receive 3 days off HAART followed by 4 days on HAART. We will analyze CD4+ T-cell counts, viral load, incidence of toxicity and side effects, HIV-specific immune responses and viral resistance to therapy and characterize the virus during rebound plasma viremia.