The Impact of Choice of NNRTI on Short-Term Treatment Outcomes among HIV-Infected Patients Prescribed Tenofovir and Lamivudine in Johannesburg,South Africa

Introduction

Recent WHO guidelines for resource-limited settings recommend tenofovir in first-line antiretroviral therapy (ART) yet there are suggestions that patients receiving nevirapine with tenofovir have worse outcomes than those receiving efavirenz. We sought to compare outcomes among those taking nevirapine vs. efavirenz with tenofovir and lamivudine.

Methods

We analyzed data on ART naïve, non-pregnant patients, ≥18 years old without tuberculosis co-infection, initiating tenofovir with lamivudine and either nevirapine or efavirenz between April 1, 2010 and July 31, 2011 (when South Africa’s public-sector use of tenofovir began) at Themba Lethu Clinic in South Africa. We measured virologic suppression (viral load <400 copies/ml), virologic failure (2 consecutive viral loads >1000 copies/ml), and attrition (death/loss to follow-up) all at 12 months after ART initiation. Modified Poisson regression with robust error estimation was used to estimate risk ratios (RR) and 95% confidence intervals (CI) for predictors of each outcome.

Results

2,254 patients were prescribed efavirenz, 131 nevirapine. Patients were followed a median (range) of 12.0 (0.1–12.0) person-months. 62.2% were female and median (IQR) age was 37.7 years (31.5–44.1). Patients prescribed efavirenz had similar initiating CD4 counts (median 132 for both regimens) but were somewhat more likely to be WHO Stage III or IV (39.6% vs. 33.6%) than those prescribed nevirapine. No difference in attrition was found (aRR: 0.83; 95% CI: 0.49–1.41). Among patients with ≥1 viral load within 1 year on ART, those prescribed nevirapine were as likely to reach virologic suppression (aRR: 0.97; 95% CI: 0.88–1.07) but more likely to experience virologic failure (aRR: 1.84; 95% CI: 1.02–3.31) than those prescribed efavirenz.

Conclusions

Our results support the notion that, among patients prescribed tenofovir and lamivudine, virologic failure is more common among those taking nevirapine than among those taking efavirenz. Longer-term follow up and larger studies will be needed to confirm this finding.     

Prevalence and impact of minority variant drug resistance mutations in primary HIV-1 infection

Objective

To evaluate minority variant drug resistance mutations detected by the oligonucleotide ligation assay (OLA) but not consensus sequencing among subjects with primary HIV-1 infection.

Design/Methods

Observational, longitudinal cohort study. Consensus sequencing and OLA were performed on the first available specimens from 99 subjects enrolled after 1996. Survival analyses, adjusted for HIV-1 RNA levels at the start of antiretroviral (ARV) therapy, evaluated the time to virologic suppression (HIV-1 RNA<50 copies/mL) among subjects with minority variants conferring intermediate or high-level resistance.

Results

Consensus sequencing and OLA detected resistance mutations in 5% and 27% of subjects, respectively, in specimens obtained a median of 30 days after infection. Median time to virologic suppression was 110 (IQR 62–147) days for 63 treated subjects without detectable mutations, 84 (IQR 56–109) days for ten subjects with minority variant mutations treated with ≥3 active ARVs, and 104 (IQR 60–162) days for nine subjects with minority variant mutations treated with <3 active ARVs (p = .9). Compared to subjects without mutations, time to virologic suppression was similar for subjects with minority variant mutations treated with ≥3 active ARVs (aHR 1.2, 95% CI 0.6–2.4, p = .6) and subjects with minority variant mutations treated with <3 active ARVs (aHR 1.0, 95% CI 0.4–2.4, p = .9). Two subjects with drug resistance and two subjects without detectable resistance experienced virologic failure.

Conclusions

Consensus sequencing significantly underestimated the prevalence of drug resistance mutations in ARV-naïve subjects with primary HIV-1 infection. Minority variants were not associated with impaired ARV response, possibly due to the small sample size. It is also possible that, with highly-potent ARVs, minority variant mutations may be relevant only at certain critical codons.     

Effectiveness of a Treatment Switch to Nevirapine plus Tenofovir and Emtricitabine (or Lamivudine) in Adults with HIV-1 Suppressed Viremia

Background

Switching subjects with persistently undetectable HIV-1 viremia under antiretroviral treatment (ART) to once-daily tenofovir/emtricitabine (or lamivudine) + nevirapine is a cost-effective and well-tolerated strategy. However, the effectiveness of this approach has not been established.

Methods

We performed a retrospective study evaluating the rates of treatment failure, virological failure (VF), and variables associated, in all subjects initiating this switch combination in our clinic since 2001. Analyses were performed by a modified intention to treat, where switch due to toxicity equalled failure. The main endpoint was plasma HIV-RNA < 50 copies/mL.

Results

341 patients were treated for a median of 176 (57; 308) weeks. At week 48, 306 (89.7%) subjects had HIV-1 RNA <50 copies/mL, 10 (2.9%) experienced VF, and 25 (7.4%) discontinued the treatment due to toxicity. During the whole follow-up 23 (6.7%) individuals (17 on lamivudine, 6 on emtricitabine; p = 0.034) developed VF and treatment modification due to toxicity occurred in 36 (10.7%). Factors independently associated with VF in a multivariate analysis were: intravenous drug use (HR 1.51; 95%CI 1.12, 2.04), time with undetectable viral load before the switch (HR 0.98; 0.97, 0.99), number of prior NRTIs (HR 1.49; 1.15, 1.93) or NNRTIs (HR 3.22; 1.64, 6.25), and previous NVP (HR 1.54; 1.10, 2.17) or efavirenz (HR 5.76; 1.11, 29.87) unscheduled interruptions. VF was associated with emergence of usual nevirapine mutations (Y181C/I/D, K103N and V106A/I), M184V (n = 16; 12 with lamivudine vs. 4 with emtricitabine, p = 0.04), and K65R (n = 7).

Conclusions

The rates of treatment failure at 48 weeks, or long-term toxicity or VF with this switch regimen are low and no unexpected mutations or patterns of mutations were selected in subjects with treatment failure.     

Impact of multi-targeted antiretroviral treatment on gut T cell depletion and HIV reservoir seeding during acute HIV infection

Background

Limited knowledge exists on early HIV events that may inform preventive and therapeutic strategies. This study aims to characterize the earliest immunologic and virologic HIV events following infection and investigates the usage of a novel therapeutic strategy.

Methods and Findings

We prospectively screened 24,430 subjects in Bangkok and identified 40 AHI individuals. Thirty Thais were enrolled (8 Fiebig I, 5 Fiebig II, 15 Fiebig III, 2 Fiebig IV) of whom 15 completed 24 weeks of megaHAART (tenofovir/emtricitabine/efavirenz/raltegravir/maraviroc). Sigmoid biopsies were completed in 24/30 at baseline and 13/15 at week 24.At baseline, the median age was 29 years and 83% were MSM. Most were symptomatic (87%), and were infected with R5-tropic (77%) CRF01_AE (70%). Median CD4 was 406 cells/mm³. HIV RNA was 5.5 log₁₀ copies/ml. Median total blood HIV DNA was higher in Fiebig III (550 copy/10⁶ PBMC) vs. Fiebig I (8 copy/10⁶ PBMC) (p = 0.01) while the median %CD4+CCR5+ gut T cells was lower in Fiebig III (19%) vs. Fiebig I (59%) (p = 0.0008).After 24 weeks of megaHAART, HIV RNA levels of <50 copies were achieved in 14/15 in blood and 13/13 in gut. Total blood HIV DNA at week 0 predicted reservoir size at week 24 (p<0.001). Total HIV DNA declined significantly and was undetectable in 3 of 15 in blood and 3 of 7 in gut. Frequency of CD4+CCR5+ gut T cells increased from 41% at baseline to 64% at week 24 (p>0.050); subjects with less than 40% at baseline had a significant increase in CD4+CCR5+ T cells from baseline to week 24 (14% vs. 71%, p = 0.02).

Conclusions

Gut T cell depletion and HIV reservoir seeding increases with progression of AHI. MegaHAART was associated with immune restoration and reduced reservoir size. Our findings could inform research on strategies to achieve HIV drug-free remission.     

Comparison of bone and renal effects in HIV-infected adults switching to abacavir or tenofovir based therapy in a randomized trial

Introduction

Our objective was to compare the bone and renal effects among HIV-infected patients randomized to abacavir or tenofovir-based combination anti-retroviral therapy.

Methods

In an open-label randomized trial, HIV-infected patients were randomized to switch from zidovudine/lamivudine (AZT/3TC) to abacavir/lamivudine (ABC/3TC) or tenofovir/emtricitabine (TDF/FTC). We measured bone mass density (BMD) and bone turnover biomarkers (osteocalcin, osteocalcin, procollagen type 1 N-terminal propeptide (P1NP), alkaline phosphatase, type I collagen cross-linked C-telopeptide (CTx), and osteoprotegerin). We assessed renal function by estimated creatinine clearance, plasma cystatin C, and urinary levels of creatinine, albumin, cystatin C, and neutrophil gelatinase-associated lipocalin (NGAL). The changes from baseline in BMD and renal and bone biomarkers were compared across study arms.

Results

Of 40 included patients, 35 completed 48 weeks of randomized therapy and follow up. BMD was measured in 33, 26, and 27 patients at baseline, week 24, and week 48, respectively. In TDF/FTC-treated patients we observed significant reductions from baseline in hip and lumbar spine BMD at week 24 (−1.8% and −2.5%) and week 48 (−2.1% and −2.1%), whereas BMD was stable in patients in the ABC/3TC arm. The changes from baseline in BMD were significantly different between study arms. All bone turnover biomarkers except osteoprotegerin increased in the TDF/FTC arm compared with the ABC/3TC arm, but early changes did not predict subsequent loss of BMD. Renal function parameters were similar between study arms although a small increase in NGAL was detected among TDF-treated patients.

Conclusion

Switching to TDF/FTC-based therapy led to decreases in BMD and increases in bone turnover markers compared with ABC/3TC-based treatment. No major difference in renal function was observed.

Trial registration

Clinicaltrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00647244","term_id":"NCT00647244"}}NCT00647244     

Prevalence and Clinical Significance of HIV Drug Resistance Mutations by Ultra-Deep Sequencing in Antiretroviral-Na?ve Subjects in the CASTLE Study

Background

CASTLE compared the efficacy of atazanavir/ritonavir with lopinavir/ritonavir, each in combination with tenofovir-emtricitabine in ARV-naïve subjects from 5 continents.

Objectives

Determine the baseline rate and clinical significance of TDR mutations using ultra-deep sequencing (UDS) in ARV-naïve subjects in CASTLE.

Methods

A case control study was performed on baseline samples for all 53 subjects with virologic failures (VF) at Week 48 and 95 subjects with virologic successes (VS) randomly selected and matched by CD4 count and viral load. UDS was performed using 454 Life Sciences/Roche technology.

Results

Of 148 samples, 141 had successful UDS (86 subtype B, 55 non-B subtypes). Overall, 30.5% of subjects had a TDR mutation at baseline; 15.6% only had TDR(s) at <20% of the viral population. There was no difference in the rate of TDRs by B (30.2%) or non-B subtypes (30.9%). VF (51) and VS (90) had similar rates of any TDRs (25.5% vs. 33.3%), NNRTI TDRs (11.1% vs.11.8%) and NRTI TDRs (24.4% vs. 25.5%). Of 9 (6.4%) subjects with M184V/I (7 at <20% levels), 6 experienced VF. 16 (11.3%) subjects had multiple TAMs, and 7 experienced VF. 3 (2.1%) subjects had both multiple TAMs+M184V, and all experienced VF. Of 14 (9.9%) subjects with PI TDRs (11 at <20% levels): only 1 experienced virologic failure. The majority of PI TDRs were found in isolation (e.g. 46I) at <20% levels, and had low resistance algorithm scores.

Conclusion

Among a representative sample of ARV-naïve subjects in CASTLE, TDR mutations were common (30.5%); B and non-B subtypes had similar rates of TDRs. Subjects with multiple PI TDRs were infrequent. Overall, TDRs did not affect virologic response for subjects on a boosted PI by week 48; however, a small subset of subjects with extensive NRTI backbone TDR patterns experienced virologic failure.     

Worsening Endothelial Function with Efavirenz Compared to Protease Inhibitors: A 12-Month Prospective Study

Objective

Changes in endothelial function, measured as flow-mediated dilation (FMD) of the brachial artery, has not been systematically assessed beyond 6 months of initiation of antiretroviral therapy (ART) when drug-related effects might offset initial improvements with virologic control.

Design

We assessed 6 and 12 month changes in FMD [presented as median (quartile 1, quartile 3)] and circulating HIV and cardiovascular biomarkers in 23 subjects initiating ART.

Results

There were no significant changes in FMD at 6 or 12 months overall despite significant increases in CD4 cell count and HDL-C and reductions in HIV RNA level, MCP-1, IP-10, sVCAM-1, sTNFR2, and sCD14. However, there were significant differences (P = 0.04) in the changes in FMD between those receiving efavirenz [N = 12; −3.50% (−4.90%, 0.68%)] vs. protease inhibitors at 12 months [N = 11; 1.50% (−0.86%, 4.56%)]. The differences in changes in FMD between those receiving and not receiving emtricitabine/tenofovir/efavirenz were more pronounced and were significantly different at both 6 and 12 months (P<0.02 for both). Additional studies showed no significant differences in changes in 25-(OH)-vitamin D, PTH, FGF-23, of F2-isoprostane levels between efavirenz and PI use or between those receiving and not receiving emtricitabine/tenofovir/efavirenz.

Conclusion

Efavirenz use was associated with reduced FMD at 12 months compared to PI-based regimens while emtricitabine/tenofovir/efavirenz was associated with reduced FMD at both 6 and 12 months compared to those not receiving this combination. Long-term effects of antiretrovirals on endothelial function may play an important role in the risk of cardiovascular disease in HIV-infected patients.     

HIV-1 drug resistance emergence among breastfeeding infants born to HIV-infected mothers during a single-arm trial of triple-antiretroviral prophylaxis for prevention of mother-to-child transmission: a secondary analysis

Background

Nevirapine and lamivudine given to mothers are transmitted to infants via breastfeeding in quantities sufficient to have biologic effects on the virus; this may lead to an increased risk of a breastfed infant''s development of resistance to maternal antiretrovirals. The Kisumu Breastfeeding Study (KiBS), a single-arm open-label prevention of mother-to-child HIV transmission (PMTCT) trial, assessed the safety and efficacy of zidovudine, lamivudine, and either nevirapine or nelfinavir given to HIV-infected women from 34 wk gestation through 6 mo of breastfeeding. Here, we present findings from a KiBS trial secondary analysis that evaluated the emergence of maternal ARV-associated resistance among 32 HIV-infected breastfed infants.

Methods and Findings

All infants in the cohort were tested for HIV infection using DNA PCR at multiple study visits during the 24 mo of the study, and plasma RNA viral load for all HIV-PCR–positive infants was evaluated retrospectively. Specimens from mothers and infants with viral load >1,000 copies/ml were tested for HIV drug resistance mutations. Overall, 32 infants were HIV infected by 24 mo of age, and of this group, 24 (75%) infants were HIV infected by 6 mo of age. Of the 24 infants infected by 6 mo, nine were born to mothers on a nelfinavir-based regimen, whereas the remaining 15 were born to mothers on a nevirapine-based regimen. All infants were also given single-dose nevirapine within 48 hours of birth. We detected genotypic resistance mutations in none of eight infants who were HIV-PCR positive by 2 wk of age (specimens from six infants were not amplifiable), for 30% (6/20) at 6 wk, 63% (14/22) positive at 14 wk, and 67% (16/24) at 6 mo post partum. Among the 16 infants with resistance mutations by 6 mo post partum, the common mutations were M184V and K103N, conferring resistance to lamivudine and nevirapine, respectively. Genotypic resistance was detected among 9/9 (100%) and 7/15 (47%) infected infants whose mothers were on nelfinavir and nevirapine, respectively. No mutations were detected among the eight infants infected after the breastfeeding period (age 6 mo).

Conclusions

Emergence of HIV drug resistance mutations in HIV-infected infants occurred between 2 wk and 6 mo post partum, most likely because of exposure to maternal ARV drugs through breast milk. Our findings may impact the choice of regimen for ARV treatment of HIV-infected breastfeeding mothers and their infected infants.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00146380","term_id":"NCT00146380"}}NCT00146380 Please see later in the article for the Editors'' Summary     

HIV-infected children in rural Zambia achieve good immunologic and virologic outcomes two years after initiating antiretroviral therapy

Background

Many HIV-infected children in sub-Saharan Africa reside in rural areas, yet most research on treatment outcomes has been conducted in urban centers. Rural clinics and residents may face unique barriers to care and treatment.

Methods

A prospective cohort study of HIV-infected children was conducted between September 2007 and September 2010 at the rural HIV clinic in Macha, Zambia. HIV-infected children younger than 16 years of age at study enrollment who received antiretroviral therapy (ART) during the study were eligible. Treatment outcomes during the first two years of ART, including mortality, immunologic status, and virologic suppression, were assessed and risk factors for mortality and virologic suppression were evaluated.

Results

A total of 69 children entered the study receiving ART and 198 initiated ART after study enrollment. The cumulative probabilities of death among children starting ART after study enrollment were 9.0% and 14.4% at 6 and 24 months after ART initiation. Younger age, higher viral load, lower CD4+ T-cell percentage and lower weight-for-age z-scores at ART initiation were associated with higher risk of mortality. The mean CD4⁺ T-cell percentage increased from 16.3% at treatment initiation to 29.3% and 35.0% at 6 and 24 months. The proportion of children with undetectable viral load increased to 88.5% and 77.8% at 6 and 24 months. Children with longer travel times (≥5 hours) and those taking nevirapine at ART initiation, as well as children who were non-adherent, were less likely to achieve virologic suppression after 6 months of ART.

Conclusions

HIV-infected children receiving treatment in a rural clinic experienced sustained immunologic and virologic improvements. Children with longer travel times were less likely to achieve virologic suppression, supporting the need for decentralized models of ART delivery.     

Impact of drug stock-outs on death and retention to care among HIV-infected patients on combination antiretroviral therapy in Abidjan, Côte d'Ivoire

Background

To evaluate the type and frequency of antiretroviral drug stock-outs, and their impact on death and interruption in care among HIV-infected patients in Abidjan, Côte d''Ivoire.

Methods and Findings

We conducted a cohort study of patients who initiated combination antiretroviral therapy (cART) in three adult HIV clinics between February 1, 2006 and June 1, 2007. Follow-up ended on February 1, 2008. The primary outcome was cART regimen modification, defined as at least one drug substitution, or discontinuation for at least one month due to drug stock-outs at the clinic pharmacy. The secondary outcome for patients who were on cART for at least six months was interruption in care, or death. A Cox regression model with time-dependent variables was used to assess the impact of antiretroviral drug stock-outs on interruption in care or death. Overall, 1,554 adults initiated cART and were followed for a mean of 13.2 months. During this time, 72 patients discontinued treatment and 98 modified their regimen because of drug stock-outs. Stock-outs involved nevirapine and fixed-dose combination zidovudine/lamivudine in 27% and 51% of cases. Of 1,554 patients, 839 (54%) initiated cART with fixed-dose stavudine/lamivudine/nevirapine and did not face stock-outs during the study period. Among the 975 patients who were on cART for at least six months, stock-out-related cART discontinuations increased the risk of interruption in care or death (adjusted hazard ratio [HR], 2.83; 95%CI, 1.25–6.44) but cART modifications did not (adjusted HR, 1.21; 95%CI, 0.46–3.16).

Conclusions

cART stock-outs affected at least 11% of population on treatment. Treatment discontinuations due to stock-outs were frequent and doubled the risk of interruption in care or death. These stock-outs did not involve the most common first-line regimen. As access to cART continues to increase in sub-Saharan Africa, first-line regimens should be standardized to decrease the probability of drug stock-outs.     

Prevalence of transmitted drug resistance and impact of transmitted resistance on treatment success in the German HIV-1 Seroconverter Cohort

Background

The aim of this study is to analyse the prevalence of transmitted drug resistance, TDR, and the impact of TDR on treatment success in the German HIV-1 Seroconverter Cohort.

Methods

Genotypic resistance analysis was performed in treatment-naïve study patients whose sample was available 1,312/1,564 (83.9% October 2008). A genotypic resistance result was obtained for 1,276/1,312 (97.3%). The resistance associated mutations were identified according to the surveillance drug resistance mutations list recommended for drug-naïve patients. Treatment success was determined as viral suppression below 500 copies/ml.

Results

Prevalence of TDR was stable at a high level between 1996 and 2007 in the German HIV-1 Seroconverter Cohort (N = 158/1,276; 12.4%; CI_wilson 10.7–14.3; p _{for trend} = 0.25). NRTI resistance was predominant (7.5%) but decreased significantly over time (CI_Wilson: 6.2–9.1, p _{for trend} = 0.02). NNRTI resistance tended to increase over time (NNRTI: 3.5%; CI_Wilson: 2.6–4.6; p _{for trend}  = 0.07), whereas PI resistance remained stable (PI: 3.0%; CI_Wilson: 2.1–4.0; p _{for trend}  = 0.24). Resistance to all drug classes was frequently caused by singleton resistance mutations (NRTI 55.6%, PI 68.4%, NNRTI 99.1%). The majority of NRTI-resistant strains (79.8%) carried resistance-associated mutations selected by the thymidine analogues zidovudine and stavudine. Preferably 2NRTI/1PIr combinations were prescribed as first line regimen in patients with resistant HIV as well as in patients with susceptible strains (susceptible 45.3%; 173/382 vs. resistant 65.5%; 40/61). The majority of patients in both groups were treated successfully within the first year after ART-initiation (susceptible: 89.9%; 62/69; resistant: 7/9; 77.8%).

Conclusion

Overall prevalence of TDR remained stable at a high level but trends of resistance against drug classes differed over time. The significant decrease of NRTI-resistance in patients newly infected with HIV might be related to the introduction of novel antiretroviral drugs and a wider use of genotypic resistance analysis prior to treatment initiation.     

National prevalence and trends of HIV transmitted drug resistance in Mexico

Background

Transmitted drug resistance (TDR) remains an important concern for the management of HIV infection, especially in countries that have recently scaled-up antiretroviral treatment (ART) access.

Methodology/Principal Findings

We designed a study to assess HIV diversity and transmitted drug resistance (TDR) prevalence and trends in Mexico. 1655 ART-naïve patients from 12 Mexican states were enrolled from 2005 to 2010. TDR was assessed from plasma HIV pol sequences using Stanford scores and the WHO TDR surveillance mutation list. TDR prevalence fluctuations over back-projected dates of infection were tested. HIV subtype B was highly prevalent in Mexico (99.9%). TDR prevalence (Stanford score>15) in the country for the study period was 7.4% (95% CI, 6.2∶8.8) and 6.8% (95% CI, 5.7∶8.2) based on the WHO TDR surveillance mutation list. NRTI TDR was the highest (4.2%), followed by NNRTI (2.5%) and PI (1.7%) TDR. Increasing trends for NNRTI (p = 0.0456) and PI (p = 0.0061) major TDR mutations were observed at the national level. Clustering of viruses containing minor TDR mutations was observed with some apparent transmission pairs and geographical effects.

Conclusions

TDR prevalence in Mexico remains at the intermediate level and is slightly lower than that observed in industrialized countries. Whether regional variations in TDR trends are associated with differences in antiretroviral drug usage/ART efficacy or with local features of viral evolution remains to be further addressed.     

Virologic failures on initial boosted-PI regimen infrequently possess low-level variants with major PI resistance mutations by ultra-deep sequencing

Background

It is unknown whether HIV-positive patients experiencing virologic failure (VF) on boosted-PI (PI/r) regimens without drug resistant mutations (DRM) by standard genotyping harbor low-level PI resistant variants. CASTLE compared the efficacy of atazanavir/ritonavir (ATV/r) with lopinavir/ritonavir (LPV/r), each in combination with TVD in ARV-naïve subjects.

Objective

To determine if VF on an initial PI/r-based regimen possess low-level resistant variants that may affect a subsequent PI-containing regimen.

Methods/Results

Patients experiencing VF on a Tenofovir/Emtricitabine+PI/r regimen were evaluated by ultra deep sequencing (UDS) for mutations classified/weighted by Stanford HIVdb. Samples were evaluated for variants to 0.4% levels. 36 VF subjects were evaluated by UDS; 24 had UDS for PI and RT DRMs. Of these 24, 19 (79.2%) had any DRM by UDS. The most common UDS-detected DRM were NRTI in 18 subjects: M184V/I (11), TAMs(7) & K65R(4); PI DRMs were detected in 9 subjects: M46I/V(5), F53L(2), I50V(1), D30N(1), and N88S(1). The remaining 12 subjects, all with VLs<10,000, had protease gene UDS, and 4 had low-level PI DRMs: F53L(2), L76V(1), I54S(1), G73S(1). Overall, 3/36(8.3%) subjects had DRMs identified with Stanford-HIVdb weights >12 for ATV or LPV: N88S (at 0.43% level-mutational load 1,828) in 1 subject on ATV; I50V (0.44%-mutational load 110) and L76V (0.52%-mutational load 20) in 1 subject each, both on LPV. All VF samples remained phenotypically susceptible to the treatment PI/r.

Conclusion

Among persons experiencing VF without PI DRMs with standard genotyping on an initial PI/r regimen, low-level variants possessing major PI DRMs were present in a minority of cases, occurred in isolation, and did not result in phenotypic resistance. NRTI DRMs were detected in a high proportion of subjects. These data suggest that PIs may remain effective in subjects experiencing VF on a PI/r-based regimen when PI DRMs are not detected by standard or UDS genotyping.     

Randomized trial of time-limited interruptions of protease inhibitor-based antiretroviral therapy (ART) vs. continuous therapy for HIV-1 infection

Background

The clinical outcomes of short interruptions of PI-based ART regimens remains undefined.

Methods

A 2-arm non-inferiority trial was conducted on 53 HIV-1 infected South African participants with viral load <50 copies/ml and CD4 T cell count >450 cells/µl on stavudine (or zidovudine), lamivudine and lopinavir/ritonavir. Subjects were randomized to a) sequential 2, 4 and 8-week ART interruptions or b) continuous ART (cART). Primary analysis was based on the proportion of CD4 count >350 cells(c)/ml over 72 weeks. Adherence, HIV-1 drug resistance, and CD4 count rise over time were analyzed as secondary endpoints.

Results

The proportions of CD4 counts >350 cells/µl were 82.12% for the intermittent arm and 93.73 for the cART arm; the difference of 11.95% was above the defined 10% threshold for non-inferiority (upper limit of 97.5% CI, 24.1%; 2-sided CI: −0.16, 23.1). No clinically significant differences in opportunistic infections, adverse events, adherence or viral resistance were noted; after randomization, long-term CD4 rise was observed only in the cART arm.

Conclusion

We are unable to conclude that short PI-based ART interruptions are non-inferior to cART in retention of immune reconstitution; however, short interruptions did not lead to a greater rate of resistance mutations or adverse events than cART suggesting that this regimen may be more forgiving than NNRTIs if interruptions in therapy occur.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00100646","term_id":"NCT00100646"}}NCT00100646     

Comparative Efficacy of Lamivudine and Emtricitabine: A Systematic Review and Meta-Analysis of Randomized Trials

Introduction

Lamivudine and emtricitabine are considered equivalent by several guidelines, but evidence of comparable efficacy is conflicting.

Methods

We searched two databases up to June 30 2013 to identify randomized and quasi-randomized trials in which lamivudine and emtricitabine were used as part of combination antiretroviral therapy for treatment-naïve or experienced HIV-positive adult patients. We only included trials where partner drugs in the regimen were identical or could be considered to be comparable. We allowed for comparisons between tenofovir and abacavir provided the study population did not begin treatment with a viral load >100,000 copies/ml.

Results

12 trials contributed 15 different randomized comparisons providing data on 2251 patients receiving lamivudine and 2662 patients receiving emtricitabine. Treatment success was not significantly different in any of the 12 trials. In the three trials that directly compared lamivudine and emtricitabine, the relative risk for achieving treatment success was non-significant (RR 1.03 95%CI 0.96-1.10). For all trials combined, the pooled relative risk for treatment success was not significantly different (RR 1.00, 95%CI 0.97–1.02). No heterogeneity was observed (I ² = 0). Similarly, there was no difference in the pooled relative risk for treatment failure (RR 1.08, 95%CI 0.94–1.22, I ² = 3.4%).

Conclusions

The findings of this systematic review suggest that lamivudine and emtricitabine are clinically equivalent.     

Nucleic Acid Template and the Risk of a PCR-Induced HIV-1 Drug Resistance Mutation

Background

The HIV-1 nucleoside RT inhibitor (NRTI)-resistance mutation, K65R confers intermediate to high-level resistance to the NRTIs abacavir, didanosine, emtricitabine, lamivudine, and tenofovir; and low-level resistance to stavudine. Several lines of evidence suggest that K65R is more common in HIV-1 subtype C than subtype B viruses.

Methods and Findings

We performed ultra-deep pyrosequencing (UDPS) and clonal dideoxynucleotide sequencing of plasma virus samples to assess the prevalence of minority K65R variants in subtype B and C viruses from untreated individuals. Although UDPS of plasma samples from 18 subtype C and 27 subtype B viruses showed that a higher proportion of subtype C viruses contain K65R (1.04% vs. 0.25%; p<0.001), limiting dilution clonal sequencing failed to corroborate its presence in two of the samples in which K65R was present in >1.5% of UDPS reads. We therefore performed UDPS on clones and site-directed mutants containing subtype B- and C-specific patterns of silent mutations in the conserved KKK motif encompassing RT codons 64 to 66 and found that subtype-specific nucleotide differences were responsible for increased PCR-induced K65R mutation in subtype C viruses.

Conclusions

This study shows that the RT KKK nucleotide template in subtype C viruses can lead to the spurious detection of K65R by highly sensitive PCR-dependent sequencing techniques. However, the study is also consistent with the subtype C nucleotide template being inherently responsible for increased polymerization-induced K65R mutations in vivo.