Viro-Immunologic Response to Ritonavir-Boosted or Unboosted Atazanavir in a Large Cohort of Multiply Treated Patients: The CARe Study

Currently, comparative data able to define the potency of boosted versus unboosted atazanavir in highly pretreated HIV-infected patients are limited. Specifically, in clinical practice it is very important to establish whether atazanavir-boosting with ritonavir warrants potency and efficacy that overcome the profile of unboosted drug. For this reason, our goal was to evaluate viro-immunologic determinants of response to atazanavir, in unboosted ATV400 or boosted ATV300/r formulation, from baseline to week 48 in highly pretreated HIV-infected patients enrolled in a prospective observational Italian study. Data from 354 patients included in an atazanavir “Early Access Program” (AI424-900) with baseline viremia 500 copies per milliliter or more and with an available virologic follow-up were examined using as-treated analysis. Of these, 200 (56.5%) and 154 (43.5%), respectively, received regimens containing ATV300/r or ATV400. Virologic success (VS) was defined as reaching viremia of less than 500 copies per ...