Evaluating the role of etravirine in the second-line antiretroviral therapy after failing an initial non-nucleoside reverse transcriptase inhibitor-based regimen in a resource-limited setting

Etravirine demonstrates activity against NNRTI-resistant HIV-1 but its efficacy depends on the number of etravirine resistance-associated mutations (RAMs). This study aimed to evaluate the role of etravirine in the second regimen in a resource-limited setting. Genotype resistance assay was conducted in a cohort of HIV-infected patients who experienced virological failure from an initial NNRTI-based regimen. We focused on etravirine-RAMs previously described: V90I, A98G, L100I, K101E/P, V106I, V179D/F, Y181C/I/V, and G190A/S. Frequency and predicting factors for <or=2 etravirine-RAMs were evaluated. There were 158 patients with a median duration of ART prior to failure of 22 months. The median CD4 cell count and HIV-1 RNA at the time of virological failure were 173 cells/mm(3) and 4.1 log copies/mL, respectively. Of all, 75.3% of patients were predicted to have <or=2 etravirine-RAMs. From logistic regression, there was no clinical factor to predict etravirine susceptibility. Patients with <or=2 etravirine-RAMs had lower rates of K65R (3.4% vs 17.9%, p=0.005), Q151M (5.9% vs 20.5%, p=0.012), and multi-NRTI resistance mutations (16.8% vs 48.7%, p<0.001) when compared to patients with >2 etravirine-RAMs. Etravirine may have activity for using in the second regimen in most patients in resource-limited setting who fail an initial NNRTI-based regimen. Genotype testing is needed to identify this group. Some of these patients, indicated by genotype results, may be able to use etravirine plus 2 active NRTIs for second ART regimen. This strategy may be an option for patients who cannot afford or tolerate protease inhibitor. Prospective study to evaluate this strategy should be conducted in resource-limited setting.

Options for a Second-Line Antiretroviral Regimen for HIV Type 1-Infected Patients Whose Initial Regimen of a Fixed-Dose Combination of Stavudine, Lamivudine, and Nevirapine Fails

BACKGROUND

A fixed-dose combination of stavudine, lamivudine, and nevirapine is extensively used as an antiretroviral regimen in developing countries because of its affordability. Virological failure with this regimen has become more common, and a second-line regimen needs to be prepared in the national program.

METHODS

Genotypic resistance testing was conducted among human immunodeficiency virus type 1 (HIV-1)-infected patients who experienced treatment failure with their first antiretroviral regimen (a fixed-dose combination of stavudine, lamivudine, and nevirapine) during 2003-2005. Patterns of resistance mutations and options for a second-line regimen were studied.

RESULTS

We studied 98 patients (mean age, 35.2 years), of whom, 63% were male. The median duration of antiretroviral therapy was 20 months. The median HIV-1 RNA load at the time of virological failure detection was 4.1 log copies/mL. The prevalences of patients with > or =1 major mutation conferring drug resistance to nucleoside reverse-transcriptase inhibitors and nonnucleoside reverse-transcriptase inhibitors were 95% and 92%, respectively. M184V was the most common nucleoside reverse-transcriptase inhibitor resistance mutation (observed in 89% of patients). Thymidine analogue mutations, K65R, and Q151M were observed in 37%, 6%, and 8% of patients, respectively. Patients with an HIV-1 RNA load of >4 log copies/mL at the time of treatment failure had higher prevalence of thymidine analogue mutations (P=.041), K65R (P=.031), and Q151M (P=.008) mutations. The second-line regimen was determined in a resource-limited setting where tenofovir and enfuvirtide are not available; the options were limited for 48% of patients.

CONCLUSIONS

After experiencing treatment failure with a fixed-dose combination of stavudine, lamivudine, and nevirapine, almost all patients have lamivudine and nonnucleoside reverse-transcriptase inhibitor resistance. The options for a second-line regimen are limited for one-half of these patients. In resource-limited settings where availability of antiretroviral agents is limited, strategies for prevention of HIV-1 resistance are crucial. Early detection of virological failure may provide more options and better treatment outcomes.