Optimizing background therapy in treatment-experienced HIV-1 patients by rules-based algorithms and bioinformatics

Short Communication: Nucleoside Reverse Transcriptase Inhibitors with Reduced Predicted Activity Do Not Impair Second-Line Therapy with Lopinavir/Ritonavir or Darunavir/Ritonavir

Second-line therapy randomized trials with lopinavir/ritonavir question the value of resistance testing to guide nucleoside reverse transcriptase inhibitor (NRTI) selection. In this study, we investigated the association between baseline drug resistance and treatment outcome after 104 weeks of second-line therapy with NRTIs and either darunavir/ritonavir or lopinavir/ritonavir in West-central Africa. We did an observational analysis of data from 387 individuals in a randomized, open-label 2LADY trial in Burkina Faso, Cameroon, and Senegal. We modeled the association between RTI drug resistance mutations (DRMs) and virological failure (VF) (viral load [VL] <50 copies/mL) at week 104 using logistic regressions. Covariates included baseline VL and CD4⁺ count, demographic, and adherence data. Overall, 193 (49.9%), 150 (38.8%), and 44 (11.4%) individuals had, respectively, low/none (genotypic susceptibility score [GSS] <1), intermediate (GSS = 1), and high predicted NRTI activity (GSS >1) in their prescribed second-line regimen. The average number of DRMs by drug class, the proportion of individuals by GSS category, and the duration of first-line therapy were not associated with VF (p > .05). High VL at switch was the only consistent prognostic factor for VF after multivariate adjustment (p < .01). Suboptimal adherence, high predicted RTI activity, or low NRTI mutations were associated with VF (p < .05) when using higher end points for VF or in the intention-to-treat analysis. In conclusion, the use of RTIs with predicted reduced activity does not impair second-line protease inhibitor-based therapy. Therefore, HIV care in resource-limited settings should prioritize strategies to improve adherence and targeted VL testing over drug resistance testing for selecting NRTIs during a protease-based second-line switch.

Effect of dolutegravir in combination with Nucleoside Reverse Transcriptase Inhibitors (NRTIs) on people living with HIV who have pre-existing NRTI mutations

Until the introduction of dolutegravir (DTG), people living with HIV (PLWH) who have developed nucleoside reverse transcriptase inhibitor (NRTI) mutations have had few other treatment options outside of regimens based on ritonavir-boosted protease inhibitors (PI/r). Here we report treatment results among PLWH in Sweden with pre-existing NRTI mutations on antiretroviral treatment (ART) with DTG and one to two NRTIs. All PLWH on ART with DTG and one to two NRTIs with pre-existing NRTI mutations were retrospectively identified from the National InfCare HIV database. As controls, PLWH on PI/r and one to two NRTIs, matched according to Genotypic Susceptibility Score and observation time, were included. Data were collected as long as the study population was on treatment with DTG; controls were monitored for the same interval. Outcome was classified as either treatment success or failure. In total, 244 participants (122 individuals treated with DTG and 122 individuals treated with PI/r) were included. Median observation time was 78 weeks (interquartile range 50-98 weeks) for participants on DTG and 75 weeks (50-101 weeks) for individuals on PI/r. Viral failure was detected in four individuals treated with DTG and three individuals treated with PI/r, resulting in similar success rates of 96.7% and 97.5%, respectively. No new mutations were found among participants with treatment failure. DTG in combination with one to two NRTIs was as efficient as PI/r in individuals with pre-existing NRTI mutations in this setting. It may be considered an alternative to PI/r-based ART even in the presence of NRTI resistance.