Although combination antiretroviral therapy (ART) has been successful in suppressing plasma HIV RNA levels in infected patients, it has not resulted in eradication of virus. Prolonged, continuous ART results in significant toxicities and difficulties adhering to drug regimens. In addition, the cost of antiretroviral drugs is prohibitive for many individuals and countries. Therefore, we have studied the virologic and immunologic effects of intermittent versus continuous ART in HIV-infected individuals in an attempt to reduce the total time an individual receives therapy while maintaining therapeutic efficacy. To test the need for and feasibility of strict adherence to a short-cycle intermittent ART regimen, we are currently conducting a randomized, controlled trial of short cycle (5 days on, 2 days off) intermittent therapy versus continuous ART in Kampala, Uganda (Protocol 02-I-N288, A Randomized, Controlled Trial of Short Cycle Intermittent versus Continuous HAART for the Treatment of Chronic HIV Infection in Uganda). The study originally included a 7/7 arm (7 days on, 7 days off) but was discontinued because several patients failed specific study criteria. Patients initially enrolled in the 7/7 arm were transferred to continuous therapy and are being monitored for the original duration of the study (73 weeks). The study enrollment and follow-up are complete with 147 patients total; 32 in the 7/7 arm, 57 in the 5/2 arm and 58 in the continuous arm. Twenty patients reached an endpoint in the 7/7 arm (reached week 72 per protocol or failed prior to week 73). Of these, there were 10 failures while receiving intermittent therapy. The total number of failures per protocol is 15. Thirty-seven patients reached an endpoint in the 5/2 arm (reached week 73 or failed prior to week 73). Seven patients failed prior to week 73. The total number of failures per protocol is 11. Twenty-eight patients have reached an endpoint in the continuous arm (reached week 73 or failed prior to week 72). Nine patients failed prior to week 73. The total number of failures per protocol is fourteen. The 5/2 and continuous treatment arms in this study appear to be equivalent by virologic failure criteria. The 5 days on/2 days off regimen could potentially reduce drug costs by 28% which would be extremely advantageous in Uganda and other resource limited settings. Although the current study is not powered to demonstrate a benefit of 5/2 versus continuous therapy, secondary evaluations of adherence, toxicity and others could be of great interest. Data cleaning and preliminary analyses have begun with planned presentation and publication of findings in 2008. In summary, short cycle intermittent ART may be an important option for the treatment of HIV infection to reduce cost and, possibly, toxicity while potentially enhancing adherence. If safety and efficacy of short-cycle intermittent therapy is ultimately demonstrated in clinical settings, it might prove to be an important strategy to expand therapy in resource-limited settings.
