Non-nucleoside Reverse Transcriptase Inhibitor-based Regimens Research Articles

Etravirine and Rilpivirine Drug Resistance Among HIV-1 Subtype C Infected Children Failing Non-Nucleoside Reverse Transcriptase Inhibitor-Based Regimens in South India.

We have analyzed reverse transcriptase (RT) region of HIV-1 pol gene from 97 HIV-infected children who were identified as failing first-line therapy that included first-generation non-nucleoside RT inhibitors (Nevirapine and Efavirenz) for at least 6 months. We found that 54% and 65% of the children had genotypically predicted resistance to second-generation non-nucleoside RT inhibitors drugs Etravirine (ETR) and Rilpivirine, respectively. These cross-resistance mutations may compromise future NNRTI-based regimens, especially in resource-limited settings. To complement these investigations, we also analyzed the sequences in Stanford database, Monogram weighted score, and DUET weighted score algorithms for ETR susceptibility and found almost perfect agreement between the three algorithms in predicting ETR susceptibility from genotypic data.

Analysis of contemporary HIV/AIDS health care costs in Germany: Driving factors and distribution across antiretroviral therapy lines.

To analyze contemporary costs of HIV health care and the cost distribution across lines of combination antiretroviral therapy (cART). To identify variations in expenditures with patient characteristics and to identify main cost determinants. To compute cost ratios between patients with varying characteristics.Empirical data on costs are collected in Germany within a 2-year prospective observational noninterventional multicenter study. The database contains information for 1154 HIV-infected patients from 8 medical centers.Means and standard deviations of the total costs are estimated for each cost fraction and across cART lines and regimens. The costs are regressed against various patient characteristics using a generalized linear model. Relative costs are calculated using the resultant coefficients.The average annual total costs (SD) per patient are &OV0556;22,231.03 (8786.13) with a maximum of &OV0556;83,970. cART medication is the major cost fraction (83.8%) with a mean of &OV0556;18,688.62 (5289.48). The major cost-driving factors are cART regimen, CD4-T cell count, cART drug resistance, and concomitant diseases. Viral load, pathology tests, and demographics have no significant impact. Standard non-nucleoside reverse transcriptase inhibitor-based regimens induce 28% lower total costs compared with standard PI/r regimens. Resistance to 3 or more antiretroviral classes induces a significant increase in costs.HIV treatment in Germany continues to be expensive. Majority of costs are attributable to cART. Main cost determinants are CD4-T cells count, comorbidity, genotypic antiviral resistance, and therapy regimen. Combinations of characteristics associated with higher expenditures enhance the increasing effect on the costs and induce high cost cases.

Efficacy, safety and pharmacokinetics of tenofovir disoproxil fumarate in virologic-suppressed HIV-infected children using weight-band dosing.

Tenofovir disoproxil fumarate (TDF) is approved for children but concerns remain about long-term renal and bone toxicity. We evaluated the efficacy, safety and pharmacokinetics of TDF in treatment-experienced children during 96 weeks. This was a prospective, open-label study in HIV-infected children 3-18 years of age (≥15 kg), with viral suppression on their first-line regimen without tenofovir. Children were given TDF/lamivudine/efavirenz once daily at entry; TDF was prescribed according to weight bands. Age-, gender- and CD4-matched controls receiving TDF-sparing regimens were concomitantly enrolled. Tenofovir pharmacokinetic assessment was performed at week 4. CD4 counts, HIV-1 RNA viral load and safety assessments were determined at baseline, 24, 48 and 96 weeks. Eighty children were enrolled (40 per group); 35 (44%) were male. Median age was 12.2 (range 3.1-17.7) years. The median administered dose was 214 mg/m. Tenofovir geometric mean AUC0-24 hours, Cmax and C24 hours were 2.66 [90% confidence interval (CI) 2.49-2.84] μg hours/mL, 0.26 (0.24-0.29) μg/mL and 0.057 (0.052-0.062) μg/mL, respectively. Estimated glomerular filtration rate did not significantly change overtime. The fractional excretion of calcium slightly increased but fractional excretion of phosphate was unchanged among children in TDF group. The bone mineral density Z score decreased in the first 24 weeks of TDF treatment and was stable afterward. The TDF group had lower cholesterol levels (P = 0.001). Thirty-nine of 40 children remained virologically suppressed. No serious adverse event related to tenofovir. TDF substitution in children and adolescents who were otherwise stable while receiving a first-line nonnucleoside reverse transcriptase inhibitor-based regimen achieved adequate exposure without clinically significant renal or bone adverse events over 96 weeks. While reassuring, these preliminary safety findings may not exclude delayed effects on renal function and bone density.

Transmitted drug resistance to rilpivirine in newly diagnosed antiretroviral naive adults

We characterized transmitted drug resistance to rilpivirine and the predicted efficacy of first-line rilpivirine-containing regimens in antiretroviral-naive Spanish patients. International Antiviral Society-USA mutations were detected in 138 of 2781 patients (4.9%), E138A (3.4%) being the most prevalent. Using the Stanford Algorithm, 121 patients (4.4%) showed low-level or intermediate resistance. No differences in the predicted efficacy of first-line non-nucleoside reverse transcriptase inhibitor-based regimens were observed. As rilpivirine becomes more widely used in clinical practice, the evolution of its transmitted drug resistance will need to be monitored. In addition, the exact role of E138A singletons on rilpivirine activity as part of first-line regimens merits further evaluation.

Drug resistance is rarely the cause or consequence of long-term persistent low-level viraemia in HIV-1-infected patients on ART.

The introduction of highly sensitive HIV-1 viral load assays with a lower quantification limit of 20 copies/ml uncovered that in a number of patients on ART, the viral load systematically fluctuates around or slightly above the detection limit of the assays. This study aimed to analyse the presence or occurrence of drug resistance mutations in HIV-1-infected patients during long-term persistent low-level viraemia (PLLV) under ART. A retrospective study was carried out in which baseline and on-therapy presence of drug resistance mutations in the HIV-1 protease and reverse transcriptase genes were analysed in patients with PLLV between 20 and 250 copies/ml. For all available plasma samples collected during PLLV, resistance analysis was attempted with an ultrasensitive amplification and sequencing protocol. Resistance analysis was successful for 154 samples collected longitudinally from 23 patients over a median period of 4.7 years (IQR 3.3-5.7). Twenty of these patients were on a boosted protease inhibitor (PI)-based regimen (87%). Single drug resistance mutations were detected in isolated samples of 4 patients, 2 of the 3 patients who initiated a non-nucleoside reverse transcriptase inhibitor-based regimen and 2 of the 20 on a PI-based regimen. Only one of the detected mutations decreased susceptibility to the therapy regimen taken at the time of sample collection. Drug resistance mutations were not found in the three patients who developed virological failure (viral load >250 copies/ml) during the study. Long episodes of PLLV in patients on boosted PI-based regimens rarely result in the selection of new drug-resistant variants.

HIV in people reincarcerated in Connecticut prisons and jails: an observational cohort study

Reincarceration in prison or jail correlates with non-sustained HIV viral suppression, but HIV treatment outcomes in released prisoners who are reincarcerated have not recently been systematically assessed despite advances in antiretroviral treatment (ART) potency, simplicity, and tolerability. In a retrospective cohort of reincarcerated inmates with HIV in Connecticut (2005-12), we used longitudinally linked demographic, pharmacy, and laboratory databases to examine correlates of viral suppression. The primary outcome was viral suppression on reincarceration, defined as viral load lower than 400 RNA copies per mL. Of 497 prisoners and jail detainees with HIV, with 934 reincarcerations, individuals were mostly unmarried, uninsured, and black men prescribed a protease-inhibitor-based ART regimen. During the median 329 days (IQR 179-621) between prison release and reincarceration, the proportion of incarceration periods with viral suppression decreased significantly from 52% to 31% (mean HIV-RNA increased by 0·4 log10; p<0·0001), lower than Connecticut's HIV-infected prison population and those prescribed ART nationally. 158 (51%) of 307 individuals with viral suppression on release had viral suppression on reincarceration. Viral suppression on reincarceration was associated with increasing age (adjusted odds ratio [aOR] 1·04, 95% CI 1·01-1·07), being prescribed non-nucleoside reverse transcriptase inhibitor-based regimens (1·63, 1·14-2·34), and having higher levels of medical or psychiatric comorbidity (1·16, 1·03-1·30). Identification of individuals most at risk for recidivism and loss of viral suppression might mitigate the risk that repeated reincarceration poses to systems of public health and safety. Bristol-Myers Squibb Virology, Patterson Trust, and National Institute on Drug Abuse.

Risk of clinically significant depression in HIV‐infected patients: effect of antiretroviral drugs

We aimed to characterize depression in newly diagnosed HIV-infected patients, to determine the effect of antiretroviral therapy (ART) on its incidence, and to investigate whether efavirenz use was associated with a higher risk, compared with non-efavirenz-containing regimens, in the Spanish CoRIS cohort. CoRIS is a contemporary, multicentre cohort of HIV-infected patients, antiretroviral-naïve at entry, launched in 2004. Poisson regression models were used to investigate demographic, clinical and treatment-related factors associated with a higher incidence of clinically significant depression to October 2010. In total, 5185 patients (13 089 person-years) participated in the study, of whom 3379 (65.2%) started ART during follow-up. The incidence rates of depression before and after starting ART were 11.68 [95% confidence interval (CI) 9.01-15.15] and 7.06 (95% CI 5.45-9.13) cases per 1000 person-years, respectively. After adjustment, there was an inverse association between the occurrence of depression and the initiation of ART [incidence rate ratio (IRR) 0.53; 95% CI 0.28-0.99], while the likelihood of depression increased in patients of age > 50 years (IRR 1.94; 95% CI 1.21-3.12). Longer exposure to ART was associated with a decreased IRR of depression in unadjusted and adjusted analyses. The IRR for patients receiving < 2, 2-4 and > 4 years of ART was 0.72 (95% CI 0.36-1.44), 0.10 (95% CI 0.04-0.25) and 0.05 (95% CI 0.01-0.17), respectively, compared with ART-naïve patients. This protective effect was also observed when durations of exposure to nonnucleoside reverse transcriptase inhibitor-based regimens and efavirenz-containing regimens were analysed separately. The incidence of clinically significant depression was lower among HIV-infected patients on ART. The protective effect of ART was also observed with efavirenz-containing regimens.

Targets for intervention to improve virological outcomes for patients receiving free antiretroviral therapy in Tamil Nadu, India

Operational research to identify factors predicting poor clinical outcomes is critical to maximize patient care and prolong first-line regimens for those receiving free antiretroviral therapy (ART) in India. We sought to identify social or clinical factors amenable to intervention that predict virological outcomes after 12 months of ART. We examined a retrospective cohort of consecutive adults initiating free nonnucleoside reverse transcriptase inhibitor-based regimens. Individuals remaining in care 12 months post-ART initiation were tested for HIV viral load and surveyed to identify barriers and facilitators to adherence, and to determine clinic travel times and associated costs. Uni- and multivariate logistic regression identified factors predicting HIV viral load >200 copies/mL after 12 months of ART. Of 230 adults initiating ART, 10% of patients died, 8% transferred out, 5% were lost to follow-up, and 174/230 (76%) completed 12 months of ART, the questionnaire, and viral load testing. HIV viral load was <200 copies/mL in 140/174 (80%) patients. In multivariate models, being busy with work or caring for others (OR 2.9, p < 0.01), having clinic transport times ≥ 3 hours (OR 3.0, p = 0.02), and alcohol use (OR 4.8, p = 0.03) predicted viral load >200 copies/mL after 12 months of ART. Clinical outcomes following ART are related to programmatic factors such as prolonged travel time and individual factors such as being busy with family or using alcohol. Simple interventions that alter these factors should be evaluated to improve clinical outcomes for populations receiving free ART in similar settings.

Second-Line Protease Inhibitor-Based Haart after Failing Non-Nucleoside Reverse Transcriptase Inhibitor-Based Regimens in Asian HIV-Infected Children

The World Health Organization (WHO) recommends boosted protease inhibitor (bPI)-based HAART after failing non-nucleoside reverse transcriptase inhibitor (NNRTI) treatment. We examined outcomes of this regimen in Asian HIV-infected children. Children from five Asian countries in the TREAT Asia Pediatric HIV Observational Database (TApHOD) with ≥ 24 weeks of NNRTI-based HAART followed by ≥ 24 weeks of bPI-based HAART were eligible. Primary outcomes were the proportions with virological suppression (HIV RNA < 400 copies/ml) and immune recovery (CD4+ T-cell percentage [CD4%]≥ 25% if age < 5 years and CD4+ T-cell count ≥ 500 cells/mm3 if age ≥ 5 years) at 48 and 96 weeks. Of 3,422 children, 153 were eligible; 52% were female. At switch, median age was 10 years, 26% were in WHO stage 4. Median weight-for-age z-score (WAZ) was -1.9 (n = 121), CD4% was 12.5% (n = 106), CD4+ T-cell count was 237 cells/mm3 (n = 112), and HIV RNA was 4.6 log10 copies/ml (n = 61). The most common bPI was lopinavir/ritonavir (83%). At 48 weeks, 61% (79/129) had immune recovery, 60% (26/43) had undetectable HIV RNA and 73% (58/79) had fasting triglycerides ≥ 130 mg/dl. By 96 weeks, 70% (57/82) achieved immune recovery, 65% (17/26) had virological suppression, and hypertriglyceridaemia occurred in 66% (33/50). Predictors for virological suppression at week 48 were longer duration of NNRTI-based HAART (P = 0.006), younger age (P = 0.007), higher WAZ (P = 0.020) and HIV RNA at switch < 10,000 copies/ml (P = 0.049). In this regional cohort of Asian children on bPI-based second-line HAART, 60% of children tested had immune recovery by 1 year, and two-thirds had hyperlipidaemia, highlighting difficulties in optimizing second-line HAART with limited drug options.

Predictors of CD4+ T-Cell Counts of HIV Type 1–Infected Persons After Virologic Failure of All 3 Original Antiretroviral Drug Classes

Low CD4(+) T-cell counts are the main factor leading to clinical progression in human immunodeficiency virus type 1 (HIV-1) infection. We aimed to investigate factors affecting CD4(+) T-cell counts after triple-class virological failure. We included individuals from the COHERE database who started antiretroviral therapy from 1998 onward and who experienced triple-class virological failure. CD4(+) T-cell counts obtained after triple-class virologic failure were analyzed using generalized estimating equations. The analyses included 2424 individuals with a total of 23 922 CD4(+) T-cell count measurements. In adjusted models (excluding current viral load and year), CD4(+) T-cell counts were higher with regimens that included boosted protease inhibitors (increase, 22 cells/µL [95% confidence interval {CI}, 3.9-41]; P = .017) or drugs from the new classes (increase, 39 cells/µL [95% CI, 15-62]; P = .001), compared with nonnucleoside reverse-transcriptase inhibitor-based regimens. These associations disappeared when current viral load and/or calendar year were included. Compared with viral levels of <2.5 log(10) copies/mL, levels of 2.5-3.5, 3.5-4.5, 4.5-5.5, and >5.5 log(10) copies/mL were associated with CD4(+) T-cell count decreases of 51, 84, 137, and 186 cells/µL, respectively (P < .001). The approximately linear inverse relationship between log(10) viral load and CD4(+) T-cell count indicates that there are likely immunologic benefits from lowering viral load even by modest amounts that do not lead to undetectable viral loads. This is important for patients with low CD4(+) T-cell counts and few drug options.

Adherence and persistence with non-nucleoside reverse transcriptase inhibitor-based antiretroviral regimens

Objective: The objective of this study was to examine adherence and persistency in HIV patients initiating first-line combination antiretroviral therapy (cART) with a non-nucleoside reverse transcriptase inhibitor (NNRTI)-based regimen.Methods: Using US health insurance records, the authors identified all persons aged ≥ 18 years with HIV, who began NNRTI-based cART between 1 January 2003 and 30 September 2009. They examined adherence using proportion of days covered (PDC), and non-persistency based on evidence of discontinuation, switching or augmentation. Differences in non-adherence (1 - PC) and non-persistency were compared over 12 months, between three treatment groups: i) efavirenz, emtricitabine and tenofovir as a fixed-dose combination (‘EFV/FTC/TDF'); ii) EFV-based regimens other than EFV/TDF/FTC, with ≥ 2 NRTIs (‘EFV + ≥ 2 NRTIs'); and iii) nevirapine-based regimens with ≥ 2 NRTIs (NVP + ≥ 2 NRTIs).Results: There were 1874 patients receiving EFV/FTC/TDF, 893 receiving EFV + ≥ 2 NRTIs and 207 receiving NVP + ≥ 2 NRTIs. Adherence was lower for both EFV + ≥ 2 NRTIs and NVP + ≥ 2 NRTIs than for EFV/FTC/TDF (rate ratio (RR) = 1.57 and 2.01, respectively; both p < 0.01), while non-persistency was higher (hazard ratio (HR) = 1.56, p < 0.01 and 1.70, p < 0.01, respectively).Conclusion: Adherence and persistency may differ between NNRTI-based regimens; additional analyses are needed to understand the reasons for these differences.

Gastrointestinal-associated lymphoid tissue immune reconstitution in a randomized clinical trial of raltegravir versus non-nucleoside reverse transcriptase inhibitor-based regimens

To examine immune restoration in duodenal tissue and correlates of reduction of immune activation in chronic HIV-infected patients randomized to different treatment regimens. Randomized clinical trial (RCT) comparing raltegravir to a non-nucleoside reverse transcriptase inhibitor-based regimen, both with fixed-dose tenofovir difumerate/emtricitabine. Antiretroviral therapy (ART)-naive volunteers underwent upper endoscopy for duodenal biopsies before and after 9 months of therapy. Tissue was paraffin-embedded for immunohistochemistry or digested into single-cell suspensions for flow cytometry of lymphocyte subsets and activation phenotype. Plasma-soluble CD14 levels were measured as a surrogate for bacterial translocation. Sixteen HIV-positive and seven control individuals completed study procedures. Small increases in duodenal lamina propria CD4 T-cell numbers were observed, especially when viewed relative to populations in control volunteers, with no differences between treatment arms. The increase in CD4 T-cell percentage was due largely to declines in CD8 T-cell numbers, which were disproportionately increased compared to peripheral blood and controls. Patients randomized to the raltegravir arm had consistent declines in both sCD14 levels and CD8 T-cell numbers in the duodenal tissue lamina propria. This first RCT of lymphocyte population restoration in duodenal tissue demonstrates more modest increases in CD4 T-cell numbers during the first 9 months of therapy than when considering CD3/CD4 percentages only. Although reduced after 9 months of ART, disproportional increased CD8 populations persist in duodenal gastrointestinal-associated lymphoid tissue (GALT). Local rather than systemic antigenic stimulation appears to be driving expanded CD8 T lymphocytes in GALT. Factors other than viral-induced CD8 expansion may be contributing to this local immunologic response.

Maternal Nutritional Status Predicts Adverse Birth Outcomes among HIV-Infected Rural Ugandan Women Receiving Combination Antiretroviral Therapy

ObjectiveMaternal nutritional status is an important predictor of birth outcomes, yet little is known about the nutritional status of HIV-infected pregnant women treated with combination antiretroviral therapy (cART). We therefore examined the relationship between maternal BMI at study enrollment, gestational weight gain (GWG), and hemoglobin concentration (Hb) among 166 women initiating cART in rural Uganda.DesignProspective cohort.MethodsHIV-infected, ART-naïve pregnant women were enrolled between 12 and 28 weeks gestation and treated with a protease inhibitor or non-nucleoside reverse transcriptase inhibitor-based combination regimen. Nutritional status was assessed monthly. Neonatal anthropometry was examined at birth. Outcomes were evaluated using multivariate analysis.ResultsMean GWG was 0.17 kg/week, 14.6% of women experienced weight loss during pregnancy, and 44.9% were anemic. Adverse fetal outcomes included low birth weight (LBW) (19.6%), preterm delivery (17.7%), fetal death (3.9%), stunting (21.1%), small-for-gestational age (15.1%), and head-sparing growth restriction (26%). No infants were HIV-infected. Gaining <0.1 kg/week was associated with LBW, preterm delivery, and a composite adverse obstetric/fetal outcome. Maternal weight at 7 months gestation predicted LBW. For each g/dL higher mean Hb, the odds of small-for-gestational age decreased by 52%.ConclusionsIn our cohort of HIV-infected women initiating cART during pregnancy, grossly inadequate GWG was common. Infants whose mothers gained <0.1 kg/week were at increased risk for LBW, preterm delivery, and composite adverse birth outcomes. cART by itself may not be sufficient for decreasing the burden of adverse birth outcomes among HIV-infected women.Trial RegistrationClinicaltrials.gov NCT00993031

8.0 Antiretroviral therapy in specific populations

8.0 Antiretroviral therapy in specific populations

New option for management of HIV-1 infection in treatment-naive patients: once-daily, fixed-dose combination of rilpivirine-emtricitabine-tenofovir

Fixed-dose combination tablets have become an important therapy option for patients infected with the human immunodeficiency virus. Fixed-dose combination rilpivirine-tenofovir-emtricitabine is a recently approved therapy option that has been extensively studied within the treatment-naïve population. When compared with efavirenz-based therapy, improved tolerability with rilpivirine-based therapy was balanced by higher rates of virologic failure to provide similar overall efficacy rates within the intention-to-treat analysis. As a result, providers will need to balance the potential for improved tolerability with fixed-dose combination rilpivirine-tenofovir-emtricitabine against a higher potential for virologic failure, particularly among patients with baseline viral loads above 100,000 copies/mL. Current treatment guidelines have recommended that fixed-dose combination rilpivirine-tenofovir-emtricitabine be an alternative therapy option for treatment-naïve patients and advise caution in those patients with high viral loads at baseline. Similar to other non-nucleoside reverse transcriptase inhibitor-based regimens, there are a number of drug interaction concerns with fixed-dose combination rilpivirine-tenofovir-emtricitabine that will necessitate monitoring and, in some cases, appropriate management. Additionally, the emergence of drug resistance to fixed-dose combination rilpivirine-tenofovir-emtricitabine has been well documented in clinical studies and close attention will be necessary in order to protect current and future therapy options. Overall, fixed-dose combination rilpivirine-tenofovir-emtricitabine is poised to provide an important therapy option for patients when appropriately applied.

Duration and reasons for changing the first antiretroviral therapy: an 8-year follow-up

BackgroundFailure of first highly active antiretroviral therapy (HAART) reduces both the duration and the chances of viral control in subsequent regimens, due to cross-resistance and common toxicity between and within...

Deep Sequencing Reveals Minor Protease Resistance Mutations in Patients Failing a Protease Inhibitor Regimen

Standard genotypic antiretroviral resistance testing, performed by bulk sequencing, does not readily detect variants that comprise <20% of the circulating HIV-1 RNA population. Nevertheless, it is valuable in selecting an antiretroviral regimen after antiretroviral failure. In patients with poor adherence, resistant variants may not reach this threshold. Therefore, deep sequencing would be potentially valuable for detecting minority resistant variants. We compared bulk sequencing and deep sequencing to detect HIV-1 drug resistance at the time of a second-line protease inhibitor (PI)-based antiretroviral regimen failure. Eligibility criteria were virologic failure (HIV-1 RNA load of >500 copies/ml) of a first-line nonnucleoside reverse transcriptase inhibitor-based regimen, with at least the M184V mutation (lamivudine resistance), and second-line failure of a lopinavir/ritonavir (LPV/r)-based regimen. An amplicon-sequencing approach on the Roche 454 system was used. Six patients with viral loads of >90,000 copies/ml and one patient with a viral load of 520 copies/ml were included. Mutations not detectable by bulk sequencing during first- and second-line failure were detected by deep sequencing during second-line failure. Low-frequency variants (>0.5% of the sequence population) harboring major protease inhibitor resistance mutations were found in 5 of 7 patients despite poor adherence to the LPV/r-based regimen. In patients with intermittent adherence to a boosted PI regimen, deep sequencing may detect minority PI-resistant variants, which likely represent early events in resistance selection. In patients with poor or intermittent adherence, there may be low evolutionary impetus for such variants to reach fixation, explaining the low prevalence of PI resistance.

Trends of transmitted drug resistance of HIV-1 and its impact on treatment response to first-line antiretroviral therapy in Taiwan

To determine the impact of transmitted drug resistance (TDR) of HIV-1 on treatment outcome in areas where routine testing for drug resistance mutations may not be available before combination antiretroviral therapy (cART) is initiated. Genotypic resistance assays were performed on HIV isolates from archived blood samples obtained from 1349 antiretroviral-naive HIV-1-infected patients in Taiwan from 2000 to 2010. Resistance mutations were interpreted with the use of the HIVdb program of the Stanford University HIV Drug Resistance Database. The genotypic sensitivity score (GSS) of the regimens prescribed was calculated. A matched case-control study was conducted to assess the impact of TDR on treatment outcomes. The overall prevalence of TDR to any antiretroviral agent was 8.0%, declining from 12.3% in 2003-06 to 5.1% in 2007-10. In the matched case-control study, 31 patients with high- or intermediate-level resistance, 16 with low-level resistance and 89 controls were enrolled. Compared with regimens with GSS >2.5, initiation of regimens with GSS ≤2.5 was associated with a higher treatment failure rate (39.3% versus 15.7%, P = 0.02) and shorter time to treatment failure (log-rank P < 0.001). In patients receiving regimens with GSS ≤2.5, protease inhibitor-based regimens were less likely to result in treatment failure, compared with non-nucleoside reverse-transcriptase inhibitor-based regimens (hazard ratio 0.26, 95% CI 0.06-1.12, P = 0.07). In Taiwan the prevalence of TDR of HIV-1 strains declined and stabilized between 2007 and 2010. Receipt of antiretroviral regimens with GSS ≤2.5 was associated with poorer treatment responses than regimens with GSS >2.5.

Etravirine and Rilpivirine Resistance in HIV-1 Subtype Crf01_Ae-Infected Adults Failing Non-Nucleoside Reverse Transcriptase Inhibitor-Based Regimens

We studied prevalence of etravirine (ETR) and rilpivirine (RPV) resistance in HIV-1 subtype CRF01_AE infection with first-line non-nucleoside reverse transcriptase inhibitor (NNRTI) failure. A total of 225 adults failing two nucleoside reverse transcriptase inhibitors (NRTIs) plus 1 NNRTI in Thailand with HIV RNA>1,000 copies/ml were included. Genotypic resistance results and HIV-1 subtype were interpreted by Stanford DR database. ETR resistance was calculated by the new Monogram weighted score (Monogram WS; ≥ 4 indicating high-level ETR resistance) and by DUET weighted score (DUET WS; 2.5-3.5 and ≥ 4 resulted in intermediate and reduce ETR response, respectively). RPV resistance interpretation was based on previous reports. Median (IQR) age was 38 (34-42) years, 41% were female and CDC A:B:C were 22%:21%:57%. HIV subtypes were 96% CRF01_AE and 4% B. Antiretrovirals at failure were lamivudine (100%), stavudine (93%), nevirapine (90%) and efavirenz (10%) with a median (IQR) duration of 3.4 (1.8-4.5) years. Median (IQR) CD4(+) T-cell count and HIV RNA were 194 (121-280) cells/mm³ and 4.1 (3.6-4.6) log₁₀ copies/ml, respectively. The common NNRTI mutations were Y181C (41%), G190A (22%) and K103N (19%). The proportion of patients with Monogram WS score ≥ 4 was 61.3%. By DUET WS, 49.8% and 7.5% of patients were scored 2.5-3.5 and ≥4, respectively. Only HIV RNA ≥ 4 log₁₀ copies/ml at failure was associated with both Monogram WS ≥ 4 (OR 2.3, 95% CI 1.3-3.9; P=0.003) and DUET WS ≥ 2.5 (OR 1.9, 95% CI 1.1-3.3; P=0.02). The RVP resistance-associated mutations (RAMs) detected were K101P (1.8%), Y181I (2.7%) and Y181V (3.6%). All patients with RPV mutation had ETR resistance. No E138R/E138K mutations were detected. Approximately 60% of patients had high-level ETR resistance. The role of ETR in second-line therapy is limited in late NNRTI failure settings. RVP RAMs were uncommon, but cross-resistance between ETR and RVP was high.

Slower Clearance of Nevirapine Resistant Virus in Infants Failing Extended Nevirapine Prophylaxis for Prevention of Mother-to-Child HIV Transmission

Nevirapine resistance mutations arise commonly following single or extended-dose nevirapine (ED-NVP) prophylaxis to prevent mother-to-child transmission (PMTCT) of human immunodeficiency virus (HIV), but decay within 6-12 months of single-dose exposure. Use of ED-NVP prophylaxis in infants is expected to rise, but data on decay of nevirapine resistance mutations in infants in whom ED-NVP failed remain limited. We assessed, in Ethiopian infants participating in the Six-Week Extended Nevirapine (SWEN) Trial, the prevalence and persistence of nevirapine resistance mutations at 6 and 12 months following single-dose or up to 6 weeks of ED-NVP, and correlated their presence with the timing of infection and the type of resistance mutations. Standard population genotyping followed by high-throughput cloning were done on dried blood spot samples collected during the trial. More infants who received ED-NVP had nevirapine resistance detected by standard population genotyping (high frequencies) at age 6 months compared with those who received single-dose nevirapine (SD-NVP) (58% of 24 vs. 26% of 19, respectively; p = 0.06). Moreover, 56% of ED-NVP-exposed infants with nevirapine resistance at age 6 months still had nevirapine resistance mutations present at high frequencies at age 1 year. Infants infected before 6 weeks of age who received either SD- or ED-NVP were more likely to have Y181C or K103N; these mutations were also more likely to persist at high frequencies through 1 year of age. HIV-infected infants in whom ED-NVP prophylaxis fails are likely to experience delayed clearance of nevirapine-resistant virus in the first year of life, which in turn places them at risk for early selection of multidrug-resistant HIV after initial therapy with nonnucleoside reverse transcriptase inhibitor-based regimens.