Successful treatment with atazanavir and lopinavir/ritonavir combination therapy in protease inhibitor-susceptible and protease inhibitor-resistant HIV-infected patients

The combination of atazanavir (ATV) plus lopinavir/ritonavir (LPV/r) has been used in practice. However, clinical data supporting its use are limited. The objective of this study was to evaluate the efficacy and tolerability of regimens with ATV + LPV/r in protease inhibitor (PI)-susceptible and PI-resistant patients. A retrospective review of 2703 charts was performed to identify all patients who received ATV + LPV/r. From June 2003 to January 2005, 33 patients received ATV + LPV/r with nucleoside reverse trancriptase inhibitors (NRTIs) for 3 months or more. Virologic success (HIV-RNA < 400 copies per milliliter) was achieved in 30 patients (91%) in a median of 10 weeks (range, 2-68). Nineteen of the 23 patients (83%) who had ultrasensitive viral load (VL) assays were nondetectable. Among patients with 6 or more protease resistance (PR) mutations (PI-resistant), 11 of 14 (79%) achieved virologic success. Eleven of those received phenotypic testing (10 Virtual Phenotype, VircoLab, Baltimore, MD). Despite predicted phenotypic resistance to ATV (6 patients) and LPV/r (7 patients), virologic success was achieved in 4 of 6 (67%) and 4 of 7 (57%), respectively. The 3 PI-resistant patients who were virologic failures had extensive prior LPV/r use, 8-11 PR mutations, and predicted phenotypic resistance to LPV/r, but 2 of 3 had CD4 increases with ATV + LPV/r. Overall, 28 patients (85%) continue to tolerate ATV + LPV/r for a median of 32 weeks follow-up (range, 12-76). Combination ATV + LPV/r with NRTIs appears safe, tolerable, and efficacious in PI-resistant patients (>= 6 PR mutations) and predicted phenotypic resistance to ATV and LPV/r. Further studies of ATV + LPV/r in HIV-treatment are warranted.