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Background: The development of drug resistance to nucleoside reverse transcriptase inhibitors (NRTIs) and nonnucleoside reverse transcriptase inhibitors (NNRTIs) has been associated with baseline human immunodeficiency virus (HIV)-1 RNA level (VL), CD4 cell counts (CD4), subtype, and treatment failure duration. This study describes drug resistance and levels of susceptibility after first-line virologic failure in individuals from Thailand, South Africa, India, Malawi, Tanzania., Methods: CD4 and VL were captured at AIDs Clinical Trial Group (ACTG) A5230 study entry, a study of lopinavir/ritonavir (LPV/r) monotherapy after first-line virologic failure on an NNRTI regimen. HIV drug-resistance mutation associations with subtype, site, study entry VL, and CD4 were evaluated using Fisher exact and Kruskall-Wallis tests., Results: Of the 207 individuals who were screened for A5230, sequence data were available for 148 individuals. Subtypes observed: subtype C (n = 97, 66%) AE (n = 27, 18%), A1 (n = 12, 8%), and D (n = 10, 7%). Of the 148 individuals, 93% (n = 138) and 96% (n = 142) had at least 1 reverse transcriptase (RT) mutation associated with NRTI and NNRTI resistance, respectively. The number of NRTI mutations was significantly associated with a higher study screening VL and lower study screening CD4 (P < .001). Differences in drug-resistance patterns in both NRTI and NNRTI were observed by site., Conclusions: The degree of NNRTI and NRTI resistance after first-line virologic failure was associated with higher VL at study entry. Thirty-two percent of individuals remained fully susceptible to etravirine and rilpivirine, protease inhibitor resistance was rare. Some level of susceptibility to NRTI remained; however, VL monitoring and earlier virologic failure detection may result in lower NRTI resistance., (© The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

Objective: To evaluate virologic response rates of lopinavir/ritonavir (LPV/r) monotherapy as second-line antiretroviral treatment (ART) among adults in resource-limited settings (RLSs)., Design: An open-label pilot study of LPV/r monotherapy in participants on first-line nonnucleoside reverse transcriptase inhibitor three-drug combination ART with plasma HIV-1 RNA 1000-200 000  copies/ml., Methods: Participants were recruited from five sites in Africa and Asia within the AIDS Clinical Trials Group (ACTG) network. All participants received LPV/r 400/100  mg twice daily. The primary endpoint was remaining on LPV/r monotherapy without virologic failure at week 24. Participants with virologic failure were offered addition of emtricitabine and tenofovir (FTC/TDF) to LPV/r., Results: Mutations associated with drug resistance were encountered in nearly all individuals screened for the study. One hundred and twenty-three participants were enrolled, and 122 completed 24 weeks on study. A high proportion remained on LPV/r monotherapy without virologic failure at 24 weeks (87%). Archived samples with HIV-1 RNA levels less than 400  copies/ml at week 24 (n=102) underwent ultrasensitive assay. Of these individuals, 62 had levels less than 40  copies/ml and 30 had levels 40-200  copies/ml. Fifteen individuals experienced virologic failure, among whom 11 had resistance assessed and two had emergent protease inhibitor mutations. Thirteen individuals with virologic failure added FTC/TDF and one individual added FTC/TDF without virologic failure. At study week 48, 11 of 14 adding FTC/TDF had HIV-1 RNA levels less than 400  copies/ml., Conclusion: In this pilot study conducted in diverse RLS, LPV/r monotherapy as second-line ART demonstrated promising activity.