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Clinicians and patients remain highly interested in the concept of structured treatment interruption (STI). Although STI strategies based on CD4-cell counts failed miserably in several large randomized trials in 2006 (ACC Dec 29 2006), investigators are still exploring other options. One such approach involves patients cycling on and off antiretroviral therapy (ART) for defined periods of time.
In the industry-supported FOTO study, 30 patients with durable virologic suppression (viral loads <50 copies/mL for ≥3 months) stopped taking their ART for 2 consecutive days each week (generally weekends). Ten patients were on efavirenz-based regimens, 10 were on nevirapine-based regimens, and 10 were on PI-based regimens; no regimen changes were made during the study. Most patients (70%) were not on their first ART regimen. At week 48, an as-treated analysis demonstrated maintenance of virologic suppression in 90% of patients.
Cohen CJ et al. Pilot study of a novel short-cycle antiretroviral treatment interruption strategy: 48-week results of the five-days on, two-days-off (FOTO) study. HIV Clin Trials 2007 Jan/Feb; 8:19-23.
Comment
The STI strategy evaluated in this pilot study (5 days on ART, 2 days off) produced enticing results. However, if we recalculate its efficacy using a more-standard intent-to-treat analysis, the 48-week rate of virologic suppression drops to an underwhelming 77%. No metabolic or resistance data are presented. Given that current regimens are often dosed once daily, and the breakthrough failure rate for suppressed patients on these regimens is generally low (<5%–10% per year), there is no urgent need to simplify current regimens solely to improve adherence or clinical outcomes. The FOTO strategy could result in a theoretical 29% savings in ART costs, but widespread use cannot be considered until results are available from much larger studies that have been conducted among diverse patient populations and that have been powered to evaluate clinical outcomes.