The level of persistent HIV viremia does not increase after successful simplification of maintenance therapy to lopinavir/ritonavir alone

OBJECTIVE: To determine whether the level of persistent HIV-1 viremia is affected by simplifying standard antiretroviral therapy to lopinavir/ritonavir (LPV/r) alone. DESIGN: Measurement of HIV-1 RNA levels < 50 copies/ml in longitudinal plasma samples from 41 of 42 subjects enrolled in the 'Only Kaletra' study that compared maintenance therapy with LPV/r alone to standard of care (SOC) with two nucleoside reverse transcriptase inhibitors (NRTI) and LPV/r. METHODS: Plasma samples for each subject from study screening to week 48 were tested using a modified Roche Amplicor HIV-1 RNA assay with a quantification limit of 3 copies/ml. RESULTS: Median plasma HIV-1 RNA values at baseline and weeks 4, 8, 12, 24 and 48 were not significantly different between the LPV/r alone and the SOC arms, being 5.1 versus 3.0 (P = 0.29), 4.5 versus 2.9 (P = 0.44), 3.3 versus 2.9 (P = 0.99), 1.9 versus 1.0 (P = 0.68), 3.7 versus 3.6 (P = 0.49), and 2.8 versus 1.6 copies/ml (P = 0.78), respectively. In the 17 of 21 subjects who maintained virus suppression < 50 copies/ml on LPV/r alone, median HIV-1 RNA values did not increase significantly from baseline at any time point after discontinuing NRTI, in comparison to the three subjects with virologic failure whose median HIV-1 RNA levels began to rise at week 8. CONCLUSIONS: The level of persistent viremia did not increase after stopping NRTI therapy among subjects who maintained virus suppression < 50 copies/ml on LPV/r alone through 48 weeks. This supports further studies of induction-simplification therapy for treatment of HIV-1 infection including the identification of factors predicting success or failure of simplified therapy.