Simon Collins, HIV i-Base

Susan Swindells and colleagues from University of Nebraska presented results from a study that switched 36 patients who had suppressed viral load <50 copies/mL for at least one year on their first PI-based triple therapy (with 2 RTIs), to atazanavir/ritonavir maintenance therapy. The primary endpoint of the study was viral suppression <200 copies/mL at 24 weeks after stopping the RTIs.

The median follow-up was 194 days (range 84 to 345). Two patients discontinued the study before switching (one withdrew consent and one had viral rebound >50 copies/mL. Of the 34 remaining patients, three experienced viral rebound at 12, 14 and 24 weeks to 1285, 4730, and 28,397 copies/mL respectively. Two of these patients had no detectable levels of atazanavir at failure, the third resuppressed to <50 copies/mL while on ATZ/r alone. PI resistance was not detected at failure in these three patients. There were no treatment discontinuations for adverse events after simplification.

The observed virologic success 24 weeks after simplification was 91% (lower 90% CI limit = 85%).

Ref: Swindells S, Wilkin T, DiRienzo G et al. A prospective, open-label, pilot trial of regimen simplification to atazanavir/ritonavir alone as maintenance antiretroviral therapy after sustained virologic suppression (ACTG 5201). Abstract 108LB.