Novel Four‐Drug Salvage Treatment Regimens after Failure of a Human Immunodeficiency Virus Type 1 Protease Inhibitor–Containing Regimen: Antiviral Activity and Correlation of Baseline Phenotypic Drug Susceptibility with Virologic Outcome

Abstract

Twenty human immunodeficiency virus—infected patients experiencing virologic failure of an indinavir- or ritonavir-containing treatment regimen were evaluated in a prospective, open-label study. Subjects received nelfinavir, saquinavir, abacavir, and either another nucleoside analog (n = 10) or nevirapine (n = 10). Patients treated with the nevirapine-containing regimen experienced significantly greater virologic suppression at week 24 than those not treated with nevirapine (P = .04). Baseline phenotypic drug susceptibility was strongly correlated with outcome in both treatment arms. Subjects with baseline virus phenotypically sensitive to 2 or 3 drugs in the salvage regimen experienced significantly greater virus load suppression than those with baseline virus sensitive to 0 or 1 drug (median week-24 change = −2.24 log and −0.35 log, respectively; P = .01). In conclusion, non-nucleoside reverse transcriptase inhibitors may represent a potent drug in salvage therapy regimens after failure of an indinavir or ritonavir regimen. Phenotypic resistance testing may provide a useful tool for selecting more effective salvage regimens.