Long-term (96-week) follow-up of antiretroviral-naïve HIV-infected patients treated with first-line lopinavir/ritonavir monotherapy in the MONARK trial

Background: The toxicities, cost and complexity of triple combinations warrant the search for other treatment options, such as boosted protease inhibitor (PI) monotherapy. MONotherapy AntiRetroviral Kaletra (MONARK) is the first randomized trial comparing lopinavir/ritonavir monotherapy to triple combination therapy with zidovudine/lamivudine and lopinavir/ritonavir in antiretroviral-naïve patients. Methods: A total of 136 antiretroviral-naïve patients, with a CD4 cell count above 100 cells/μL and a plasma HIV RNA below 100 000 HIV-1 RNA copies/mL, were randomized and dosed with either lopinavir/ritonavir monotherapy (n=83) or lopinavir/ritonavir+zidovudine/lamivudine (n=53). We focus here on patients in the lopinavir/ritonavir monotherapy arm followed to week 96. The intent-to-treat (ITT) analysis initially involved all patients randomized to lopinavir/ritonavir monotherapy (n=83), and then focused on patients who had an HIV RNA 400 copies/mL. Focusing on the 56 patients with an HIV RNA <50 copies/mL at week 48, 38 of 56 patients (68%) had a sustained HIV RNA <50 copies/mL to week 96. To week 96, a total of 28 patients (34%) had discontinued the study treatment. In addition, the allocated treatment was changed for seven patients. PI-associated resistance mutations were evident in five of 83 patients in the monotherapy arm from baseline to week 96. Conclusion: By ITT analysis, 39 of the 83 patients initially randomized to lopinavir/ritonavir monotherapy had HIV RNA <50 copies/mL at week 96. The occurrence in some patients of low-level viraemia (50-500 copies/mL) may increase the risk of drug resistance. First-line lopinavir/ritonavir monotherapy cannot be systematically recommended. © 2009 British HIV Association

Protease inhibitor resistance analysis in the MONARK trial comparing first-line lopinavir-ritonavir monotherapy to lopinavir-ritonavir plus zidovudine and lamivudine triple therapy

The MONARK study was a pilot randomized trial comparing the safety and efficacy of lopinavir-ritonavir (LPV/r) monotherapy to those of LPV/r-zidovudine-lamivudine triple therapy for antiretroviral-naïve human immunodeficiency virus type 1 (HIV-1)-infected patients. Resistance testing was performed at the time of initial screening and at the time of virological failure (defined to include low-level viremia with >50 and <400 HIV-1 virus RNA copies/ml of plasma). Changes from the baseline sequences, including mutations noted on the 2008 International AIDS Society - USA list of resistance-associated protease mutations, were considered. Drug resistance testing was performed for 38 patients (5 of 53 on triple therapy and 33 of 83 on monotherapy). By week 96 (W96), virus samples from 18 of 33 patients in the monotherapy arm showed changes from baseline sequences, and 5 of these patients had viruses with major protease inhibitor (PI) resistance-associated mutations (M46I at W40, L76V at W48, M46I and L76V at W48, L10F and V82A at W72, and L76V at W84). Data on virus phenotypes detected at the time of initial screening and the time of virological failure were available for four patients in whom major PI resistance mutations developed, and these data revealed a mean increase of 2.2-fold (range, 0.75- to 4.6-fold) in the LPV 50% inhibitory concentration. All three patients in whom the L76V PI resistance mutation developed were infected with HIV-1 subtype CRF02-AG. In the triple-therapy group, no major PI resistance mutation was selected among the three patients with protease changes by W48. No association between the baseline CD4 cell count and the viral load, the W4 and final viral loads, or the final LPV trough concentration and the emergence of a major PI resistance mutation was found. Major PI resistance-associated mutations were detected in 5 (6%) of 83 patients treated with LPV/r monotherapy, suggesting that LPV/r monotherapy is an inappropriate first option. The mutation L76V may be considered in further studies of lopinavir resistance. Copyright © 2009, American Society for Microbiology. All Rights Reserved