Long term probability of detection of HIV-1 drug resistance after starting antiretroviral therapy in routine clinical practice

Consistency of drug-resistant mutations in plasma and peripheral blood mononuclear cells of patients with treatment-naïve and treatment-experienced HIV-1 infection

Introduction

Genotypic drug resistance testing is cursrently recommended by the World Health Organization for all patients infected with human immunodeficiency virus type 1 (HIV-1) undergoing care or switching regimes due to failure with previous antiretroviral therapy (ART). Patients with human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) who meet the criteria for free testing for genotypic drug resistance due to poor adherence in Henan Province may resume their previous regimens before resampling. Therefore, resistance testing based on plasma RNA can fail in a proportion of patients. Resistance testing based on peripheral blood mononuclear cells (PBMCs) is an alternative option. In this study, we investigated the differences in drug-resistant mutations (DRMs) between plasma HIV RNA and proviral DNA in treatment-experienced and treatment-naïve patients.

Methods

Matched plasma RNA and proviral DNA samples of 66 HIV-1 infected treatment-naïve and 78 treatment-experienced patients were selected for DRM analysis and comparison.

Results

DRMs were detected in 27.3% (18/66) of treatment-naïve and 80.8% (63/78) of treatment-experienced samples. Resistance to at least one drug was detected based on analysis of plasma RNA and proviral DNA in 7.6% (5/66) and 9.1% (6/66) of treatment-naïve patients and in 79.5% (62/78) and 78.2% (61/78) of treatment-experienced patients, respectively. Furthermore, 61/66 (92.4%) of treatment-naïve patients showed concordant RNA and DNA drug resistance. When drug resistance was defined as intermediate and high, the concordance of drug resistance profiles of paired RNA and proviral DNA samples derived from treatment-naïve patients were up to 97.0% compared with only 80.8% (63/78) in treatment-experienced patients.

Discussion

Our data indicate that drug resistance testing based on plasma RNA or proviral DNA might be interchangeable in treatment-naïve patients, whereas plasma RNA-based testing remains the best choice for drug resistance analysis in patients with ART failure in clinical practice.

HIV-Infected Women with Low-Grade Squamous Intraepithelial Lesion on Cervical Cytology Have Higher Risk of Underlying High-Grade Cervical Intraepithelial Neoplasia

Objective: To evaluate the risk of histological high-grade cervical lesions defined as cervical intraepithelial neoplasia grade 2 or worse (CIN2+) in women with human immunodeficiency virus (HIV) infection who had low-grade squamous intraepithelial lesions (LSIL) on cervical cytological screening compared with HIV-uninfected women who had similar cytology. Methods: 127 HIV-positive women aged 18–65 years with LSIL cytology undergoing colposcopic examination between January 2008 and December 2019 at Chiang Mai University Hospital were reviewed. By matching 1:1 ratio for age (±5 years) and examination time period (±12 months), 127 HIV-negative women with LSIL cytology in the same period were recruited as controlled subjects for comparison. The patients’ characteristics, HIV status, CD4 counts, antiretroviral therapy, and histopathology on cervical biopsy were analyzed. Results: HIV-infected women significantly had early sexual debut (age < 20 years) and more sexual partners (≥2) than HIV-uninfected women. The risk of underlying CIN2+ in HIV-infected women was significantly higher than that in HIV-negative women (20.5% vs. 9.4%, p = 0.021) with an odds ratio (OR) of 2.47 and 95% confidence interval (CI) = 1.18–5.14. After adjustment, the risk of underlying CIN2+ in HIV-infected women remained significantly higher than that in HIV-uninfected women (adjusted OR = 2.55, 95% CI = 1.11–5.82, p = 0.027). Conclusion: Among women with LSIL on cervical cytology, the risk of underlying CIN2+ in HIV-infected women was approximately 2.5 times higher than those without HIV infection. Colposcopy is indicated particularly in the case of women with a long duration of HIV infection.

Understanding patterns of HIV multi-drug resistance through models of temporal and spatial drug heterogeneity

Triple-drug therapies have transformed HIV from a fatal condition to a chronic one. These therapies should prevent HIV drug resistance evolution, because one or more drugs suppress any partially resistant viruses. In practice, such therapies drastically reduced, but did not eliminate, resistance evolution. In this article, we reanalyze published data from an evolutionary perspective and demonstrate several intriguing patterns about HIV resistance evolution - resistance evolves (1) even after years on successful therapy, (2) sequentially, often via one mutation at a time and (3) in a partially predictable order. We describe how these observations might emerge under two models of HIV drugs varying in space or time. Despite decades of work in this area, much opportunity remains to create models with realistic parameters for three drugs, and to match model outcomes to resistance rates and genetic patterns from individuals on triple-drug therapy. Further, lessons from HIV may inform other systems.

Characterization of HIV-1 subtypes and drug resistance mutations in Henan Province, China (2017-2019)

Human immunodeficiency virus type 1 (HIV-1) infection remains a severe public health problem worldwide. In this study, we investigated the distribution of HIV-1 subtypes and the prevalence of drug resistance mutations (DRMs) among patients with HIV-1 infection in Henan Province, China. HIV-1 strains in blood samples taken from inpatients and outpatients visiting the Sixth People’s Hospital of Zhengzhou from August 2017 to July 2019 with a viral load (VL) greater than 1000 copies/ml were subjected to subtype and DRMs analysis. Out of a total of 769 samples, subtype and DRM data were obtained from 657 (85.43%) samples. Phylogenetic analysis based on partial pol gene sequences indicated that the most commonly found genotype was subtype B (45.51%, 299/657), followed by CRF01_AE (28.61%, 188/657), CRF07_BC (15.68%, 103/657), CRF08_BC (0.76%, 5/657), C (0.61%, 4/657), A (0.30%, 2/657), and others (8.52%, 56/657). Circulating recombinant forms (CRFs) were most commonly found in patients who were naïve to antiretroviral treatment (ART) (68.67%, 160/233). The percentage of patients with one or more major drug-resistance mutations was 50.99% (335/657), and it was 6.44% (15/233) in ART-naive patients that were primarily infected with subtype B (17.74%). Resistance mutations were most common at codons 65, 103, 106, 184, and 190 of the reverse transcriptase gene and codon 46 of the protease gene. Our study provides detailed information about the distribution of HIV-1 subtypes and the incidence of drug resistance mutations of different subtypes in ART-experienced and naïve patients. This can guide policymakers in making decisions about treatment strategies against HIV-1.

Cervical neoplastic lesions in relation to CD4 T-lymphocyte counts and antiretroviral therapy among women with clinical stage 1 HIV in Yunnan, China

China lacks data demonstrating associations of cervical neoplastic lesions with CD4 T-lymphocyte (CD4 cell) counts and antiretroviral therapy (ART) among HIV-infected women, suggesting relevant investigations are needed. A total of 545 HIV-infected women were enrolled in Yunnan, China, between 2011 and 2013. CD4 cell counts and ART were measured via medical records and cervical neoplastic lesions were measured by professional pathologists. Multivariable logistic models, which treated cervical intraepithelial neoplasia (CIN) 1+ and CIN2+ as outcomes, calculated adjusted odds ratio (aOR) of CD4 cell counts and ART. Subgroup analysis treating CIN1+ as the outcome was conducted by HIV infection duration (<4 vs ≥4 years), ethnicity (Han vs non-Han), and study site (Mangshi vs Kunming). The prevalence of CIN1+ and CIN2+ was 17.4% and 7.3%, respectively. Overall, 243 (44.6%) women had CD4 cell counts ≥500 cell/μL, 187 (34.3%) used ART for less than 2 years, and 236 (43.3%) used ART for at least 2 years. We found inverse associations of CIN1+ with CD4 cell counts (≥500 compared to <500 cells/μL: aOR = 0.46, 95% CI = 0.27-0.79) and ART use (<2 years: aOR = 0.43, 95% CI = 0.21-0.87; ≥2 years: aOR = 0.54, 95% CI = 0.27-1.10). Point estimates did not change substantially for CIN2+ but aORs of ART became nonsignificant. No significant interaction was observed for HIV infection duration. We found significant interaction between CD4 cell counts and ethnicity and study site in relation to CIN1+. Our study suggests potential protective effects of high CD4 cell counts against cervical neoplastic lesions among HIV-infected women, whereas associations of ART are less consistent.

New antiretroviral agent use affects prevalence of HIV drug resistance in clinical care populations

OBJECTIVE

To estimate the prevalence of HIV drug resistance over time and identify risk factors for multiclass resistance.

DESIGN

Prospective clinical cohort of HIV-infected patients at the University of North Carolina.

METHODS

Among antiretroviral therapy (ART)-experienced patients in care 2000-2016, we estimated annual prevalences of cumulative resistance, defined as at least one major mutation by drug class. Clinical data and multiple imputation were used when genotypic data were missing, and mutations were carried forward in time. We estimated resistance odds ratios comparing characteristics of patients in care in 2016.

RESULTS

A total of 3682 patients contributed 23 169 person-years. Prevalence of at least one major resistance mutation, irrespective of viral suppression, peaked in 2005 with 49% (95% confidence interval 46, 52) and decreased to 38% (35, 40) in 2016. Resistance to nucleoside reverse transcriptase inhibitors, protease inhibitors, and nonnucleoside reverse transcriptase inhibitors also peaked in 2005-2007 and decreased to 28 (26, 31), 14 (12, 16), and 27% (24, 29) in 2016, respectively. In 2016, prevalence of integrase strand transfer inhibitor (INSTI) resistance was 2% (1, 3) and triple-class resistance 10% (9, 12). Over the study period, cumulative resistance was frequent among patients with detectable viremia, but uncommon among patients initiating ART post-2007. Among 1553 patients in care in 2016, ART initiation at an older age, with an INSTI, and with higher CD4 cell counts were associated with resistance to fewer or no classes.

CONCLUSION

Prevalence of resistance to older ART classes has decreased in the last 10 years in this clinical cohort, whereas INSTI resistance has increased but remained very low. Patients with viremia continue to have a high burden of resistance even if they initiated ART recently.

Sex-based differences in antiretroviral therapy initiation, switching and treatment interruptions: global overview from the International Epidemiologic Databases to Evaluate AIDS (IeDEA)

INTRODUCTION

In 2015, the World Health Organization recommended that all HIV-infected individuals consider ART initiation as soon as possible after diagnosis. Sex differences in choice of initial ART regimen, indications for switching, time to switching and choice of second-line regimens have not been well described. The aims of this study were to describe first-line ART and CD4 count at ART initiation by sex, calendar year and region, and to analyse time to change or interruption in first-line ART, according to sex in each region.

METHODS

Participating cohorts included: Southern, East and West Africa (IeDEA-Africa), North America (NA-ACCORD), Caribbean, Central/South America (CCASAnet) and Asia-Pacific including Australia (IeDEA Asia-Pacific). The primary outcomes analysed for each region and according to sex were choice of initial ART, time to switching and time to discontinuation of the first-line regimen.

RESULTS AND DISCUSSION

The combined cohort data set comprised of 715,252 participants across seven regions from low- to high-income settings. The median CD4 count at treatment initiation was lower in men compared with women in nearly all regions and time periods. Women from North America and Southern Africa were more likely to switch ART compared to men (p < 0.001) with approximately 90% of women reporting a major change after 10 years in North America. Overall, after 8 years on ART, >50% of HIV- positive men and women from Southern Africa, East Africa, South and Central America remained on their original regimen. Men were more likely to have a treatment interruption compared with women in low- and middle-income countries from the Asia/Pacific region (p < 0.001) as were men from Southern Africa (p < 0.001). Greater than 75% of men and women did not report a treatment interruption after 10 years on ART from all regions except North America and Southern Africa.

CONCLUSIONS

There are regional variations in the ART regimen commenced at baseline and rates of major change and treatment interruption according to sex. Some of this is likely to reflect changes in local and international antiretroviral guideline recommendations but other sex-specific factors such as pregnancy may contribute to these differences.

Pretreatment HIV drug resistance results in virological failure and accumulation of additional resistance mutations in Ugandan children

Background

Pretreatment HIV drug resistance (PDR) can impair virological response to ART, jeopardizing effective treatment for children.

Methods

Children aged ≤12 years initiated first-line ART in Uganda during 2010-11. Baseline and 6 monthly viral load (VL) and genotypic resistance testing if VL >1000 copies/mL was done. The 2015 IAS-USA mutation list and Stanford algorithm were used to score drug resistance mutations (DRMs) and susceptibility. Virological failure (VF) was defined as two consecutive VLs >1000 copies/mL or death after 6 months of ART. Factors associated with failure and acquired drug resistance (ADR) were assessed in a logistic regression analysis.

Results

Among 317 children enrolled, median age was 4.9 years and 91.5% received NNRTI-based regimens. PDR was detected in 47/278 (16.9%) children, of whom 22 (7.9%) had resistance against their first-line regimen and were therefore on a partially active regimen. After 24 months of follow-up, 92/287 (32.1%) had experienced VF. Children with PDR had a higher risk of VF (OR 15.25, P < 0.001) and ADR (OR 3.58, P = 0.01).

Conclusions

Almost one-third of children experienced VF within 24 months of NNRTI-based first-line treatment. PDR was the strongest predictor of VF and ADR, and therefore presents a major threat in children. There is a need for ART regimens that maximize effectiveness of first-line therapy for long-term treatment success in the presence of PDR or incorporation of routine VL testing to detect VF and change treatment in time, in order to prevent clinical deterioration and accumulation of additional drug resistance. Children ≤3 years should be initiated on a PI-based regimen as per WHO guidelines.

Mechanisms and Factors That Drive Extensive Human Immunodeficiency Virus Type-1 Hypervariability: An Overview

The extensive hypervariability of human immunodeficiency virus type-1 (HIV-1) populations represents a major barrier against the success of currently available antiretroviral therapy. Moreover, it is still the most important obstacle that faces the development of an effective preventive vaccine against this infectious virus. Indeed, several factors can drive such hypervariability within and between HIV-1 patients. These factors include: first, the very low fidelity nature of HIV-1 reverse transcriptase; second, the extremely high HIV-1 replication rate; and third, the high genomic recombination rate that the virus has. All these factors together with the APOBEC3 proteins family and the immune and antiviral drugs pressures drive the extensive hypervariability of HIV-1 populations. Studying these factors and the mechanisms that drive such hypervariability will provide valuable insights that may guide the development of effective therapeutic and preventive strategies against HIV-1 infection in the near future. To this end, in this review, we summarized recent advances in this area of HIV-1 research.

Durability and Effectiveness of Maraviroc-Containing Regimens in HIV-1-Infected Individuals with Virological Failure in Routine Clinical Practice

INTRODUCTION

Limited data are available on the durability and effectiveness of maraviroc in routine clinical practice. We assessed the durability of maraviroc-containing regimens during a 30-month period, as well as their immunovirological and clinical efficacy, according to viral tropism in treatment-experienced individuals with viral load (VL) >50 copies/ml in the French Hospital Database on HIV.

METHODS

Virological success was defined as VL<50 copies/ml, immunological success as a confirmed increase of at least 100 CD4 cells/mm3 measured twice at least one month apart, and clinical failure as hospitalization for a non-AIDS event, an AIDS event, or death. Multivariable Cox regression models adjusted for potential confounders were used to assess the influence of viral tropism on durability, the immunovirological responses, and clinical outcome.

RESULTS

356 individuals started maraviroc with VL>50 copies/ml of whom 223 harbored R5 viruses, 44 non-R5 viruses and 89 viruses of unknown tropism. Individuals with non-R5 viruses were more likely than individuals with R5 viruses to discontinue maraviroc (75% vs 34%, p<0.0001). At 30 months, the estimated rates of virological and immunological success were respectively 89% and 51% in individuals with R5 viruses and 48% and 23% in individuals with non-R5 viruses. In multivariable analysis, non-R5 viruses were associated with a lower likelihood of both virological success (hazard ratio (HR): 0.42; 95% confidence interval (CI), 0.25-0.70) and immunological success (HR: 0.37; 95% CI, 0.18-0.77). No difference in clinical outcome was found between individuals with R5 and non-R5 viruses. The effectiveness of maraviroc-containing regimens in individuals with unknown viral tropism was not significantly different from that in individuals with R5 viruses. A limitation of the study is the absence of genotypic susceptibility score.

CONCLUSION

In this observational study, maraviroc-containing regimens yielded high rates of viral suppression and immunological responses in individuals with R5 viruses in whom prior regimens had failed.

Initiation of antiretroviral therapy at high CD4+ cell counts is associated with positive treatment outcomes

OBJECTIVE

There is limited research investigating the possible mechanisms of how starting combination antiretroviral therapy (cART) at a higher CD4 cell count decreases mortality. This study investigated the association between initiating cART with short-term and long-term achievement of viral suppression; emergence of any drug resistance and of an AIDS-defining illness (ADI); long-term treatment adherence; and all-cause mortality.

METHODS

This retrospective cohort study included 4120 naive patients who initiated cART between 2000 and 2012. Patients were followed until 2013, death or until the last contact date (varied by outcome). The main exposure was the interaction between period of cART initiation (2000-2006 and 2007-2012) and CD4 cell count at cART initiation (<500 versus ≥500 cells/μl). We considered both baseline and longitudinal covariates. We fitted different multivariable models using cross-sectional and longitudinal statistical methods, depending on the outcome.

RESULTS

Patients who initiated cART with a CD4 cell count at least 500 cells/μl in 2007-2012 had an increased likelihood of achieving viral suppression at 9 months and of maintaining an adherence level of at least 95% over time, and the lowest probability of developing any resistance and an ADI during follow-up. These patients were not the ones with the highest likelihood of maintaining viral suppression over time, most likely due to viral load blips experienced during the follow-up.

CONCLUSION

The outcomes in this study likely play an important role in explaining the positive impact of early cART initiation on mortality. These results should alleviate some of the concerns clinicians may have when initiating cART in patients with high CD4s as recommended by current treatment guidelines.

Efficacy of Once Daily Darunavir/Ritonavir in PI-Naïve, NNRTI-Experienced Patients in the ODIN Trial

Background. An exploratory subanalysis of the ODIN trial was performed to evaluate the efficacy of darunavir/ritonavir (DRV/r) 800/100 mg OD versus 600/100 mg BID in patients who were NNRTI-experienced but PI-naïve. Methods. ODIN was a phase III, 48-week study comparing DRV/r OD versus BID in 590 treatment-experienced patients with no DRV resistance-associated mutations (RAMs) at screening. Patients received DRV/r 800/100 mg OD or DRV/r 600/100 mg BID plus ≥2 NRTIs. Of the 590 patients randomized, 272 (46%) were NNRTI-experienced but PI-naïve. Results. Overall, 272 patients received DRV/r OD (n = 135) or BID (n = 137) plus ≥2 optimised NRTIs. The mean age was 39 years; 35% were female; 27% were Black, 24% Caucasian, 26% Oriental/Asian, and 23% other races; 17% were recruited in South Africa; and 48% had non-B HIV-1 subtypes. Mean baseline plasma HIV-1 RNA load was 4.10 log₁₀⁡ copies/mL; median CD4 cell count was 258 cells/μL. At week 48, 111/135 (82%) of DRV/r OD and 109/137 (80%) of DRV/r BID patients achieved an HIV-1 RNA load <50 copies/mL. No patient developed primary PI RAMs. Conclusion. DRV/r 800/100 mg OD in combination with ≥2 optimised NRTIs led to virological suppression <50 copies/mL in 82% of NNRTI-experienced, PI-naïve patients by week 48.

Treatment Modifications and Treatment-Limiting Toxicities or Side Effects: Risk Factors and Temporal Trends

Combined antiretroviral treatment (cART) modifications are often required due to treatment failure or side effects. We investigate cART regimens' durability, frequency of treatment-limiting adverse events, and potential risk factors and temporal trends. Data were derived from the Athens Multicenter AIDS Cohort Study (AMACS). Statistical analyses were based on survival techniques, allowing for multiple contributions per individual. Overall, 2,756 individuals, aged >15 years, initiated cART. cART regimens were grouped by their initiation date into four calendar periods (1995-1998, 1999-2002, 2003-2006, and 2007+). Median [95% confidence interval (CI)] time to first treatment modification was 2.11 (1.95-2.33) years; cumulative probabilities at 1 year were 31.6%, 29.0%, 33.1%, and 29.6% for the four periods, respectively. cART modifications were less frequent in more recent years (adjusted HR=0.96 per year; p<0.001). Longer treatment duration was associated with lower HIV-RNA, higher CD4 counts, and being previously ART naive. cART modifications due to treatment failure became less frequent in recent years (adjusted HR=0.91 per year; p<0.001). Estimated (95% CI) 1 year cumulative probabilities of treatment-limiting side effects were 16.4% (12.0-21.3%), 19.3% (15.6-23.3%), 24.9% (20.3-29.7%), and 21.1% (13.4-29.9%) for the four periods, respectively, with no significant temporal trends. Risk of side effects was lower in nonnucleoside reverse transcriptase inhibitor (NNRTI)-based regimens or triple nucleoside reverse transcriptase inhibitor (NRTI)-based cART regimens. Treatment modifications have become less frequent in more recent years. This could be partly attributed to the lower risk for side effects of NNRTI-based cART regimens and mainly to the improved efficacy of newer drugs. However, the rate of drugs substitutions due to adverse events remains substantially high.

Substituted Bis-THF Protease Inhibitors with Improved Potency against Highly Resistant Mature HIV-1 Protease PR20

An extremely drug resistant mutant of HIV-1 protease (PR) bearing 20 mutations (PR20) has been studied with two potent antiviral investigational inhibitors. GRL-5010A and GRL-4410A were designed to introduce hydrogen bond interactions with the flexible flaps of the PR by incorporating gem-difluorines and alkoxy, respectively, at the C4 position of the bis-THF of darunavir. PR20 provides an excellent model for high level resistance, since clinical inhibitors are >1000-fold less active on PR20 than on wild-type enzyme. GRL-5010A and GRL-4410A show inhibition constants of 4.3 ± 7.0 and 1.7 ± 1.8 nM, respectively, for PR20, compared to the binding affinity of 41 ± 1 nM measured for darunavir. Crystal structures of PR20 in complexes with the two inhibitors confirmed the new hydrogen bond interactions with Gly 48 in the flap of the enzyme. The two new compounds are more effective than darunavir in inhibiting mature PR20 and show promise for further development of antiviral agents targeting highly resistant PR mutants.

HIV drug resistance mutations following poor adherence in HIV-infected patient: a case report

Acquired HIV drug resistance following poor adherence is common. We report a case of HIV-infected patient with poor CD4 gain and self reported poor adherence. Investigations revealed high viral load and resistance to NRTIs and NNRTIs with sensitivity to boosted PIs. HIVDR mutations create treatment challenges in resource limited settings.

Drug resistance in non-B subtype HIV-1: impact of HIV-1 reverse transcriptase inhibitors

Human immunodeficiency virus (HIV) causes approximately 2.5 million new infections every year, and nearly 1.6 million patients succumb to HIV each year. Several factors, including cross-species transmission and error-prone replication have resulted in extraordinary genetic diversity of HIV groups. One of these groups, known as group M (main) contains nine subtypes (A-D, F-H and J-K) and causes ~95% of all HIV infections. Most reported data on susceptibility and resistance to anti-HIV therapies are from subtype B HIV infections, which are prevalent in developed countries but account for only ~12% of all global HIV infections, whereas non-B subtype HIV infections that account for ~88% of all HIV infections are prevalent primarily in low and middle-income countries. Although the treatments for subtype B infections are generally effective against non-B subtype infections, there are differences in response to therapies. Here, we review how polymorphisms, transmission efficiency of drug-resistant strains, and differences in genetic barrier for drug resistance can differentially alter the response to reverse transcriptase-targeting therapies in various subtypes.

The successful application of a national peer advisory committee for physicians who provide salvage regimens to heavily antiretroviral-experienced patients in mexican human immunodeficiency virus clinics

BACKGROUND

Designing optimal antiretroviral (ARV) salvage regimens for multiclass drug-resistant, human immunodeficiency virus (HIV)-infected patients demands specific clinical skills. Our aim was to assess the virologic and immunologic effects of the treatment recommendations drafted by a peer advisory board to physicians caring for heavily ARV-experienced patients.

METHODS

We conducted a nationwide, HIV clinic-based, cohort study in Mexico. Adults infected with HIV were assessed for a median of 33 months (interquartile range [IQR] = 22-43 months). These patients had experienced the virologic failure of at least 2 prior ARV regimens and had detectable viremia while currently being treated; their physicians had received therapeutic advice, by a panel of experts, regarding the ARV salvage regimen. The primary endpoint was the incidence of loss of virologic response (plasma HIV-RNA levels of <200 copies per mL, followed by levels above this threshold) during the follow-up assessment using an observed-failure competing risks regression analysis.

RESULTS

A total of 611 patients were observed (median ARV therapy exposure = 10.5 years; median prior regimens = 4). The probabilities of virologic failure were 11.9%, 14.4%, 16.9%, and 19.4% at the 12-, 24-, 36-, and 48-month follow-up assessments, respectively. Of the 531 patients who achieved a confirmed plasma HIV-RNA level below 200 copies per mL, the median increase in blood CD4(+) T-cell count was 162 cells per mL (IQR = 45-304 cells per mL).

CONCLUSIONS

In routine practice, a high rate of patients with extensive ARV experience, who received an optimized salvage regimen recommended by a peer advisory committee, achieved a long-term sustained virologic response and immune reconstitution.

When can HIV clinical trials detect treatment effects on drug resistance?

Methods of sampling patients for resistance testing, and statistical analyses of HIV drug resistance, have not been standardised in HIV clinical trials. We analysed methods of genotyping and rates of treatment-emergent drug resistance from 27 clinical trials identified from a MEDLINE search. Sample size calculations were conducted using NQUERY software, assuming 5% significance level, 80% power and 1:1 randomisation. The percentage of patients with treatment-emergent IAS-USA mutations after 96 weeks ranged from 1.8% to 9.1% for first-line 2NRTI/NNRTI treatments, 0.6% to 6.3% for first-line 2NRTI/PI/r treatments and 0.0% to 2.0% in switch trials of boosted PIs. The prevalence of drug resistance was higher in trials with no screening for drug resistance at baseline, where the HIV RNA cut-off for genotyping was >50 copies/mL, where patients were tested for drug resistance after discontinuation of treatment, and where follow-up times were 96 weeks or longer. HIV clinical trials could be designed to detect differences in the risk of HIV drug resistance between treatments, as an analysis supporting HIV RNA suppression as the primary endpoint. However, this would require a standardised approach, with intent-to-treat analyses, testing of all samples with HIV RNA>50 copies/mL and genotyping after drug discontinuation.

Etravirine as a Switching Option for Patients with HIV RNA Suppression: A Review of Recent Trials

Unlike other nonnucleoside reverse transcriptase inhibitors, etravirine is only approved for use in treatment-experienced patients. In the DUET 1 and 2 trials, 1203 highly treatment-experienced patients were randomized to etravirine or placebo, in combination with darunavir/ritonavir and optimized background treatment. In these trials, etravirine showed significantly higher rates of HIV RNA suppression when compared with placebo (61% versus 40% at Week 48). There was no significant rise of lipids or neuropsychiatric adverse events, but there was an increase in the risk of rash with etravirine treatment. In the SENSE trial, which evaluated etravirine and efavirenz in 157 treatment-naïve patients in combination with 2 nucleoside analogues, there was a lower risk of lipid elevations and neuropsychiatric adverse events with etravirine when compared to efavirenz. Etravirine has been evaluated in three randomized switching studies. In the SSAT029 switch trial, 38 patients who had neuropsychiatric adverse events possibly related to efavirenz showed an improvement in these after switching to etravirine. The Swiss Switch-EE recruited 58 individuals without neuropsychiatric adverse events who were receiving efavirenz, and no benefit was shown when switching to etravirine. In the Spanish ETRA-SWITCH trial (n = 46), there were improvements in lipids when individuals switched from a protease inhibitor to etravirine. These switching trials were conducted in patients with full HIV RNA suppression: <50 copies/mL and with no history of virological failure or resistance to therapy. The results from these three randomized switching studies suggest a possible new role for etravirine, in combination with two nucleoside analogues, as a switching option for those with HIV RNA suppression but who are reporting adverse events possibly related to antiretroviral therapy. However a large well-powered trial would need to be conducted to strengthen the evidence from the pilot studies conducted so far.

Virological efficacy and immunological recovery among Ethiopian HIV-1 infected adults and children

Background

Introduction of antiretroviral therapy (ART) in sub-Saharan Africa was a hot debate due to many concerns about adherence, logistics and resistance. Currently, it has been significantly scaled up. However as the WHO clinico-immunological approaches for initiation and monitoring of ART in the region lacks viral load determination and drug resistance monitoring, HIV infected adults and children may be at risk for “unrecognized” virologic failure and the subsequent development of antiretroviral drug resistance. This study evaluates the virological efficacy and immunological recovery of HIV/AIDS patients under ART.

Methods

Consecutive HIV-1 infected adults (N = 100) and children (N = 100) who have been receiving ART for up to 6 years at Gondar University Hospital, Ethiopia were enrolled following the WHO protocol for assessment of acquired drug resistance. Magnitude of viral suppression, genotypic drug resistance mutations and patterns of CD4⁺ T cell recovery were determined using standard virological and immunological methods.

Results

Virological suppression (HIV RNA < 40 copies/ml) was observed in 82 and 87% of adults and children on a median time of 24 months on ART, respectively. Mutation K103N conferring resistance to non nucleoside reverse transcriptase inhibitors and thymidine analogue mutations (M41L, L210W) were found only in one adult and child patient, respectively. Median CD4⁺ T cell count has increased from baseline 124 to 266 (IQR: 203–306) and 345 (IQR: 17–1435) to 998 (IQR: 678–2205) cells/mm³ in adults and children respectively after 12 months of ART. Nevertheless, small but significant number of clinically asymptomatic adults (16%) and children (13%) had low level viraemia (HIV-1 RNA 41–1000 copies/ml).

Conclusions

Majority of both adults (82%) and children (87%) who received ART showed high viral suppression and immunological recovery. This indicates that despite limited resources in the setting virological efficacy can be sustained for a substantial length of time and also enhance immunological recovery irrespective of age. However, the presence of drug resistance mutations and low level viraemia among clinically asymptomatic patients highlights the need for virological monitoring.

A cost-effectiveness analysis of HIV preexposure prophylaxis for men who have sex with men in Australia

BACKGROUND

Antiretroviral therapy (ART) used as preexposure prophylaxis (PrEP) by human immunodeficiency virus (HIV)-seronegative individuals reduces the risk of acquiring HIV. However, the population-level impact and cost-effectiveness of using PrEP as a public health intervention remains debated.

METHODS

We used a stochastic agent-based model of HIV transmission and progression to simulate the clinical and cost outcomes of different strategies of providing PrEP to men who have sex with men (MSM) in New South Wales (NSW), Australia. Model outcomes were reported as incremental cost-effectiveness ratios (ICERs) in 2013 Australian dollars per quality-adjusted life-year gained (QALYG).

RESULTS

The use of PrEP in 10%-30% of the entire NSW MSM population was projected to cost an additional $316-$952 million over the course of 10 years, and cost >$400 000 per QALYG compared with the status quo. Targeting MSM with sexual partners ranging between >10 to >50 partners within 6 months cost an additional $31-$331 million dollars, and cost >$110 000 per QALYG compared with the status quo. We found that preexposure prophylaxis is most cost-effective when targeted for HIV-negative MSM in a discordant regular partnership. The ICERs ranged between $8399 and $11 575, for coverage ranging between 15% and 30%, respectively.

CONCLUSIONS

Targeting HIV-negative MSM in a discordant regular partnership is a cost-effective intervention. However, this highly targeted strategy would not have large population-level impact. Other scenarios are unlikely to be cost-effective.

Preexposure prophylaxis will have a limited impact on HIV-1 drug resistance in sub-Saharan Africa: a comparison of mathematical models

BACKGROUND

Preexposure prophylaxis (PrEP) with tenofovir and emtricitabine can prevent new HIV-1 infections, but there is a concern that use of PrEP could increase HIV drug resistance resulting in loss of treatment options. We compared standardized outcomes from three independent mathematical models simulating the impact of PrEP on HIV transmission and drug resistance in sub-Saharan African countries.

METHODS

All models assume that people using PrEP receive an HIV test every 3-6 months. The models vary in structure and parameter choices for PrEP coverage, effectiveness of PrEP (at different adherence levels) and the rate with which HIV drug resistance emerges and is transmitted.

RESULTS

The models predict that the use of PrEP in conjunction with antiretroviral therapy will result in a lower prevalence of HIV than when only antiretroviral therapy is used. With or without PrEP, all models suggest that HIV drug resistance will increase over the next 20 years due to antiretroviral therapy. PrEP will increase the absolute prevalence of drug resistance in the total population by less than 0.5% and amongst infected individuals by at most 7%. Twenty years after the introduction of PrEP, the majority of drug-resistant infections is due to antiretroviral therapy (50-63% across models), whereas 40-50% will be due to transmission of drug resistance, and less than 4% to the use of PrEP.

CONCLUSION

HIV drug resistance resulting from antiretroviral therapy is predicted to far exceed that resulting from PrEP. Concern over drug resistance should not be a reason to limit the use of PrEP.

Risk of virological failure and drug resistance during first and second-line antiretroviral therapy in a 10-year cohort in Senegal: results from the ANRS 1215 cohort

BACKGROUND

In 1998, Senegal launched one of Africa's first antiretroviral therapy (ART) programs. Since then, the number of treated patients in Africa has substantially increased thanks to simplification in treatment management. Although good outcomes over the first years of ART have been observed in sub-Saharan Africa, little is known about the long-term (>5 years) risks of virological failure and drug resistance and about second-line treatment response.

METHODS

Patients from the ANRS-1215 cohort in Senegal, started with either one nonnucleoside reverse transcriptase inhibitor or indinavir, a first-generation nonboosted protease inhibitor, followed for >6 months and having >1 viral load (VL) measurement were included. Virological failure was defined as 2 consecutive VL measurements >1000 copies/mL.

RESULTS

Of the 366 patients included, 89% achieved a VL <500 copies/mL. The risk of virological failure at 12, 24, and 60 months was 5%, 16%, and 25%, being higher in younger patients (P = 0.05), those receiving a protease inhibitor-containing regimen (P = 0.05), and those with lower adherence (P = 0.03). The risk of resistance to any drug at 12, 24, and 60 months was 3%, 11%, and 18%. After virological failure, 60% of the patients were switched to second-line treatments. Although 81% of the patients achieved virological success, the risk of virological failure was 27% at 24 months, mostly in patients with multiple resistances.

CONCLUSIONS

In this cohort, virological outcomes for first-line treatments were good compared with those from high-resource settings. However, the rate of virological failure for second-line treatment was high, probably because of accumulation of resistances.

HIV-1 drug resistance in recently HIV-infected pregnant mother's naïve to antiretroviral therapy in Dodoma urban, Tanzania

Background

HIV resistance affects virological response to therapy and efficacy of prophylaxis in mother-to-child-transmission. The study aims to assess the prevalence of HIV primary resistance in pregnant women naïve to antiretrovirals.

Methods

Cross sectional baseline analysis of a cohort of HIV + pregnant women (HPW) enrolled in the study entitled Antiretroviral Management of Antenatal and Natal HIV Infection (AMANI, peace in Kiswahili language). The AMANI study began in May 2010 in Dodoma, Tanzania. In this observational cohort, antiretroviral treatment was provided to all women from the 28^th week of gestation until the end of the breastfeeding period. Baseline CD4 cell count, viral load and HIV drug-resistance genotype were collected.

Results

Drug-resistance analysis was performed on 97 naïve infected-mothers. The prevalence of all primary drug resistance and primary non-nucleoside reverse-transcriptase inhibitors resistance was 11.9% and 7.5%, respectively. K103S was found in two women with no M184V detection. HIV-1 subtype A was the most commonly identified, with a high prevalence of subtype A1, followed by C, D, C/D recombinant, A/C recombinant and A/D recombinant. HIV drug- resistance mutations were detected in A1 and C subtypes.

Conclusion

Our study reports an 11.9% prevalence rate of primary drug resistance in naïve HIV-infected pregnant women from a remote area of Tanzania. Considering that the non-nucleoside reverse-transcriptase inhibitors are part of the first-line antiretroviral regimen in Tanzania and all of Africa, resistance surveys should be prioritized in settings where antiretroviral therapy programs are scaled up.

HIV Drug Resistance: Problems and Perspectives

Access to combination antiretroviral treatment (ART) has improved greatly over recent years. At the end of 2011, more than eight million HIV-infected people were receiving ART in low-income and middle-income countries. ART generally works well in keeping the virus suppressed and the patient healthy. However, treatment only works as long as the virus is not resistant against the drugs used. In the last decades, HIV treatments have become better and better at slowing down the evolution of drug resistance, so that some patients are treated for many years without having any resistance problems. However, for some patients, especially in low-income countries, drug resistance is still a serious threat to their health. This essay will review what is known about transmitted and acquired drug resistance, multi-class drug resistance, resistance to newer drugs, resistance due to treatment for the prevention of mother-to-child transmission, the role of minority variants (low-frequency drug-resistance mutations), and resistance due to pre-exposure prophylaxis.

Virologic response to tipranavir-ritonavir or darunavir-ritonavir based regimens in antiretroviral therapy experienced HIV-1 patients: a meta-analysis and meta-regression of randomized controlled clinical trials

BACKGROUND

The development of tipranavir and darunavir, second generation non-peptidic HIV protease inhibitors, with marked improved resistance profiles, has opened a new perspective on the treatment of antiretroviral therapy (ART) experienced HIV patients with poor viral load control. The aim of this study was to determine the virologic response in ART experienced patients to tipranavir-ritonavir and darunavir-ritonavir based regimens.

METHODS AND FINDINGS

A computer based literature search was conducted in the databases of HINARI (Health InterNetwork Access to Research Initiative), Medline and Cochrane library. Meta-analysis was performed by including randomized controlled studies that were conducted in ART experienced patients with plasma viral load above 1,000 copies HIV RNA/ml. The odds ratios and 95% confidence intervals (CI) for viral loads of <50 copies and <400 copies HIV RNA/ml at the end of the intervention were determined by the random effects model. Meta-regression, sensitivity analysis and funnel plots were done. The number of HIV-1 patients who were on either a tipranavir-ritonavir or darunavir-ritonavir based regimen and achieved viral load less than 50 copies HIV RNA/ml was significantly higher (overall OR = 3.4; 95% CI, 2.61-4.52) than the number of HIV-1 patients who were on investigator selected boosted comparator HIV-1 protease inhibitors (CPIs-ritonavir). Similarly, the number of patients with viral load less than 400 copies HIV RNA/ml was significantly higher in either the tipranavir-ritonavir or darunavir-ritonavir based regimen treated group (overall OR = 3.0; 95% CI, 2.15-4.11). Meta-regression showed that the viral load reduction was independent of baseline viral load, baseline CD4 count and duration of tipranavir-ritonavir or darunavir-ritonavir based regimen.

CONCLUSIONS

Tipranavir and darunavir based regimens were more effective in patients who were ART experienced and had poor viral load control. Further studies are required to determine their consistent viral load suppression effect as the duration of treatment is more prolonged.

HIV-1 drug resistance genotyping from antiretroviral therapy (ART) naïve and first-line treatment failures in Djiboutian patients

Abstract

In this study we report the prevalence of antiretroviral drug resistant HIV-1 genotypes of virus isolated from Djiboutian patients who failed first-line antiretroviral therapy (ART) and from ART naïve patients.

Patients and methods

A total of 35 blood samples from 16 patients who showed first-line ART failure (>1000 viral genome copies/ml) and 19 ART-naïve patients were collected in Djibouti from October 2009 to December 2009. Both the protease (PR) and reverse transcriptase (RT) genes were amplified and sequenced using National Agency for AIDS Research (ANRS) protocols. The Stanford HIV database algorithm was used for interpretation of resistance data and genotyping.

Results

Among the 16 patients with first-line ART failure, nine (56.2%) showed reverse transcriptase inhibitor-resistant HIV-1 strains: two (12.5%) were resistant to nucleoside (NRTI), one (6.25%) to non-nucleoside (NNRTI) reverse transcriptase inhibitors, and six (37.5%) to both. Analysis of the DNA sequencing data indicated that the most common mutations conferring drug resistance were M184V (38%) for NRTI and K103N (25%) for NNRTI. Only NRTI primary mutations K101Q, K103N and the PI minor mutation L10V were found in ART naïve individuals. No protease inhibitor resistant strains were detected. In our study, we found no detectable resistance in ∼ 44% of all patients who experienced therapeutic failure which was explained by low compliance, co-infection with tuberculosis and malnutrition. Genotyping revealed that 65.7% of samples were infected with subtype C, 20% with CRF02_AG, 8.5% with B, 2.9% with CRF02_AG/C and 2.9% with K/C.

Conclusion

The results of this first study about drug resistance mutations in first-line ART failures show the importance of performing drug resistance mutation test which guides the choice of a second-line regimen. This will improve the management of HIV-infected Djiboutian patients.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2051206212753973

Drug resistance mutations in HIV type 1 isolates from patients failing antiretroviral therapy in Morocco

The emergence of viral-resistant strains is a major problem for the medical management of HIV-infected individuals. The aim of this study was to characterize viral subtypes and drug-resistance mutations (DRMs) in HIV-1 isolates from patients failing antiretroviral therapy (ART). A total of 45 HIV-1-infected patients failing ART were enrolled. The viral RT and Prot genes were amplified and sequenced to determine subtypes and potential DRMs. The subtype distribution was 74% subtype B, 11% subtype A, 9% CRF02-AG, 4% subtype G, and 2% subtype C. Virus samples from 34% of the patients had no DRM while 53%, 27%, and 2% of samples carried at least one DRM conferring resistance to drugs of one, two, or three classes, respectively. DRMs were observed in 50% of the patients infected with non-B strains. The prevalence of nucleoside transcriptase inhibitor (NRTI) mutations was 48%, M184V being largely predominant. The prevalence of nonnucleoside reverse transcriptase inhibitor (NNRTI) mutations was 13%, with K103N present in 57% of samples from NNRTIs-exposed patients. The prevalence of protease inhibitor (PI) mutations was 22%, with major mutations V82A and M46I seen in 16% and 11% of viruses from PI-exposed individuals, respectively. Our study shows the emergence of DRMs in HIV-1 isolates from Moroccan patients failing ART. Although not surprising, the data plead for longitudinal surveys of the dynamics of emergence of DRMs (with a focus on multidrug resistance) in treated patients and circulation of resistant HIV-1 strains in this country.

New strategies for lowering the costs of antiretroviral treatment and care for people with HIV/AIDS in the United Kingdom

In the UK, the annual cost of treatment and care for people with human immunodeficiency virus (HIV)/acquired immune deficiency virus (AIDS) rose by over 600% from £104 million in 1997 to £762 million in 2010; approximately two-thirds of the £762 million cost of treatment and care in 2010 was for the procurement of antiretrovirals and other related drugs. The number of people accessing care for HIV/AIDS rose from 22,000 in 2000 to 65,000 in 2009. Adoption of "test and treat" guidelines for treating all HIV-infected people with antiretrovirals would further increase the burden of costs. Given the current economic situation, there is now a new focus on strategies for treatment and care of people with HIV-1 infection which can maintain efficacy but at a lower cost. In this review, we propose three strategies which could potentially lower the costs of treatment and care, ie, stopping testing CD4 counts for patients with full HIV RNA suppression on antiretroviral treatment and recent CD4 counts above 350 cells/μL; more widespread use of generic antiretrovirals as replacements for patients currently taking patented versions; and use of darunavir-ritonavir monotherapy as a switch option for patients with full HIV RNA suppression on other antiretrovirals and no history of virological failure. However, it is important that high standards of clinical care are maintained despite cost-saving measures. Antiretrovirals with generic alternatives may have toxicity issues, eg, zidovudine and nevirapine. There could be ethical issues in starting patients on these drugs if they are currently tolerating other treatments. The use of darunavir-ritonavir monotherapy is not consistently recommended in international HIV treatment guidelines.

Projected life expectancy of people with HIV according to timing of diagnosis

BACKGROUND AND OBJECTIVES

Effective antiretroviral therapy (ART) has contributed greatly toward survival for people with HIV, yet many remain undiagnosed until very late. Our aims were to estimate the life expectancy of an HIV-infected MSM living in a developed country with extensive access to ART and healthcare, and to assess the effect of late diagnosis on life expectancy.

METHODS

A stochastic computer simulation model of HIV infection and the effect of ART was used to estimate life expectancy and determine the distribution of potential lifetime outcomes of an MSM, aged 30 years, who becomes HIV positive in 2010. The effect of altering the diagnosis rate was investigated.

RESULTS

Assuming a high rate of HIV diagnosis (median CD4 cell count at diagnosis, 432  cells/μl), projected median age at death (life expectancy) was 75.0 years. This implies 7.0 years of life were lost on average due to HIV. Cumulative risks of death by 5 and 10 years after infection were 2.3 and 5.2%, respectively. The 95% uncertainty bound for life expectancy was (68.0,77.3) years. When a low diagnosis rate was assumed (diagnosis only when symptomatic, median CD4 cell count 140  cells/μl), life expectancy was 71.5 years, implying an average 10.5 years of life lost due to HIV.

CONCLUSION

If low rates of virologic failure observed in treated patients continue, predicted life expectancy is relatively high in people with HIV who can access a wide range of antiretrovirals. The greatest risk of excess mortality is due to delays in HIV diagnosis.

Phase 2 double-blind, randomized trial of etravirine versus efavirenz in treatment-naive patients: 48-week results

BACKGROUND

The Study of Etravirine Neuropsychiatric Symptoms versus Efavirenz (SENSE) trial compared etravirine with efavirenz in treatment-naive patients. The primary endpoint was neuropsychiatric adverse events up to week 12; HIV RNA suppression at week 48 was a secondary endpoint.

METHODS

Patients with HIV RNA more than 5000  copies/ml were randomized to etravirine 400  mg once daily (n = 79) or efavirenz (n = 78), plus two nucleoside analogues. HIV RNA less than 50  copies/ml at week 48 was analysed using the time to loss of virological response (TLOVR) algorithm. Drug resistance at treatment failure and safety endpoints were also evaluated.

RESULTS

At baseline, the median CD4 cell count was 302  cells/μl and HIV RNA was 4.8 log10  copies/ml. In the intent to treat TLOVR analysis at week 48, 60 of 79 (76%) patients on etravirine versus 58 of 78 (74%) on efavirenz had HIV RNA less than 50  copies/ml. In the on-treatment analysis, 60 of 65 (92%) taking etravirine had HIV RNA les than 50 copies/ml versus 58 of 65 (89%) for efavirenz: etravirine showed noninferior efficacy versus efavirenz in both analyses (P < 0.05). Four patients had virological failure in the etravirine arm: none developed resistance to nucleoside analogues or nonnucleosides. Seven patients had virological failure in the efavirenz arm: three developed treatment-emergent resistance to nucleoside analogues and/or nonnucleosides. At the week 48 visit, the percentage with ongoing neuropsychiatric adverse events was 6.3% for etravirine and 21.5% for efavirenz (P = 0.011).

CONCLUSION

First-line treatment with etravirine 400 mg once daily and two nucleoside reverse transcriptase inhibitors (NRTIs) led to similar rates of HIV RNA suppression, compared with efavirenz and two NRTIs. None of the patients with virological failure in the etravirine arm developed resistance to nonnucleosides.

Analysis of drug resistance during HIV RNA viraemia in the MONET trial of darunavir/ritonavir monotherapy

BACKGROUND

When patients have HIV RNA suppressed to <50 copies/ml on current treatment, switching to darunavir (DRV)/ritonavir (DRV/r) monotherapy could prevent the development of resistance to other drug classes.

METHODS

In the MONET trial, 256 patients with HIV RNA<50 copies/ml on current highly active antiretroviral therapy (57% with protease inhibitors [PIs] and 43% with non-nucleoside reverse transcriptase inhibitors) and no history of virological failure were randomized to DRV/r 800/100 mg once daily, either as monotherapy (monotherapy arm) or with two nucleoside reverse transcriptase inhibitors (NRTIs; triple therapy arm). All samples with HIV RNA ≥ 50 copies/ml were genotyped, and a virtual phenotype was calculated (VircoType HIV-1 assays; Virco BVBA, Mechelen, Belgium).

RESULTS

A total of 63 patients had ≥ 1 HIV RNA result ≥ 50 copies/ml, of whom 38 were successfully genotyped. Most HIV RNA increases were transient and in the range of 50-200 copies/ml. Overall, 36 of the 38 (95%) successfully genotyped patients showed no International AIDS Society-USA major PI mutations, DRV mutations or NRTI mutations. Two patients showed some evidence of PI resistance during transient HIV RNA elevations: one patient in the monotherapy arm had a single DRV mutation (L33F) when HIV RNA was 63 copies/ml (the virus was phenotypically sensitive to DRV [fold change 0.8]) and one PI pretreated patient taking tenofovir disoproxil fumarate/emtricitabine/DRV/r had re-emergence of pre-existing NRTI (M184V) and PI (V82I and L90M) mutations after a short treatment interruption (this virus remained phenotypically sensitive to DRV/r). Both patients showed sustained HIV RNA suppression to week 48 remaining with the same treatment.

CONCLUSIONS

Emergence of drug resistance after changing a suppressive triple antiretroviral therapy to DRV/r with or without nucleoside analogues is uncommon.

Estimating prevalence of accumulated HIV-1 drug resistance in a cohort of patients on antiretroviral therapy

OBJECTIVES

Estimating the prevalence of accumulated HIV drug resistance in patients receiving antiretroviral therapy (ART) is difficult due to lack of resistance testing at all occasions of virological failure and in patients with undetectable viral load. A method to estimate this for 6498 EuroSIDA patients who were under follow-up on ART at 1 July 2008 was therefore developed by imputing data on patients with no prior resistance test results, based on the probability of detecting resistance in tested patients with similar profiles.

METHODS

Using all resistance test results available, predicted intermediate/high-level resistance to specific drug classes [nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (PIs)] was derived using the Stanford algorithm v5.1.2. Logistic regression models were then employed to estimate predicted probability of resistance to each drug class for given values of current viral load, history of virological failure and previous virological suppression. Based on these predicted probabilities and patients' covariate profiles, estimates of prevalence in 5355 patients with no prior test results were obtained. Overall prevalence of resistance was estimated by pooling these data with those observed in the remaining 1143 tested patients.

RESULTS

Prevalence of NRTI, NNRTI and PI resistance was estimated as 43% (95% confidence interval: 39%-46%), 15% (13%-18%) and 25% (22%-28%), respectively.

CONCLUSIONS

This method provides estimates for the proportion of treated patients in a cohort who harbour resistance on a given date, which are less likely to be affected by selection bias due to missing resistance data and will allow us to estimate prevalence of resistance to different drug classes at specific timepoints in HIV-infected populations on ART.

A suicide gene approach using the human pro-apoptotic protein tBid inhibits HIV-1 replication

Background

Regulated expression of suicide genes is a powerful tool to eliminate specific subsets of cells and will find widespread usage in both basic and applied science. A promising example is the specific elimination of human immunodeficiency virus type 1 (HIV-1) infected cells by LTR-driven suicide genes. The success of this approach, however, depends on a fast and effective suicide gene, which is expressed exclusively in HIV-1 infected cells. These preconditions have not yet been completely fulfilled and, thus, success of suicide approaches has been limited so far. We tested truncated Bid (tBid), a human pro-apoptotic protein that induces apoptosis very rapidly and efficiently, as suicide gene for gene therapy against HIV-1 infection.

Results

When tBid was introduced into the HIV-1 LTR-based, Tat- and Rev-dependent transgene expression vector pLRed(INS)₂R, very efficient induction of apoptosis was observed within 24 hours, but only in the presence of both HIV-1 regulatory proteins Tat and Rev. Induction of apoptosis was not observed in their absence. Cells containing this vector rapidly died when transfected with plasmids containing full-length viral genomic DNA, completely eliminating the chance for HIV-1 replication. Viral replication was also strongly reduced when cells were infected with HIV-1 particles.

Conclusions

This suicide vector has the potential to establish a safe and effective gene therapy approach to exclusively eliminate HIV-1 infected cells before infectious virus particles are released.

HIV-1 drug resistance testing from dried blood spots collected in rural Tanzania using the ViroSeq HIV-1 Genotyping System

Objectives

To assess whether the commercial ViroSeq HIV-1 Genotyping System (Abbott Molecular, Des Plains, IL, USA) can be used in conjunction with dried blood spots (DBS) for clinical monitoring of drug resistance in patients who fail antiretroviral treatment (ART) in rural Tanzania.

Patients and methods

Patients at Haydom Lutheran Hospital with confirmed treatment failure (viral load >1000 copies/mL) of a first-line ART regimen were selected for resistance testing. DBS were stored with desiccant at −20°C for a median of 126 days (range 0–203) and shipped at ambient temperature for 20 days. After manual extraction of nucleic acids, the ViroSeq kit was used for amplification and sequencing. DBS-derived genotypes were compared with those of a plasma-based assay.

Results

Seventeen of 36 (47%) DBS specimens were successfully genotyped. Only 2 of 16 (13%) DBS with a viral load <10 000 copies/mL could be amplified, compared with 15 of 20 (75%) DBS with a viral load >10 000 copies/mL (P = 0.001). In samples that yielded a sequence, all 23 clinically significant reverse transcriptase (RT) mutations in plasma were also detected in DBS. One RT mutation was found in DBS only. In the protease region, 77 polymorphisms were found in plasma, of which 70 (91%) were also detected in DBS. Sixteen of 17 (94%) patients had identical resistance profiles to antiretroviral drugs in plasma and DBS.

Conclusions

The ViroSeq kit performed well in patients with a high viral load, but failed to genotype most DBS with a viral load <10 000 copies/mL. In DBS that yielded a genotype, there was high concordance with a plasma-based assay.

Epidemiology of antiretroviral multiclass resistance

Given the recent evolution of therapeutic trends, the frequency and determinants of multiclass-resistant HIV infection in the modern combination highly active antiretroviral therapy (HAART) era are less well understood. In this study, the authors characterize the epidemiology of antiretroviral multiclass resistance among HAART-naïve patients enrolled in a province-wide HAART distribution program in British Columbia, Canada. HAART and resistance testing are free to eligible individuals in British Columbia. This study was based on patients who initiated naïve on HAART and were followed during January 1, 2000-June 30, 2007. Explanatory logistic and survival models were built to identify those factors most influential in the emergence of multiclass resistance. Among the 1,820 individuals in our study, 833 (46%) were tested for antiretroviral resistance at least once during their follow-up. Multiclass resistance was observed in 142 individuals (n = 833; 17%) during a median follow-up of 14 months (interquartile range, 3-34 months) (incidence rate, 0.8 cases/1,000 person-months). The authors found that initial nonnucleoside reverse transcriptase inhibitor-based HAART was the main determinant of multiclass resistance. Given that these inhibitors are still widely used, priority should be given to make resistance testing and viral load monitoring a standard part of human immunodeficiency virus care to maximize the long-term efficacy and efficiency of HAART.

Assessing subtype and drug-resistance-associated mutations among antiretroviral-treated HIV-infected patients

BACKGROUND

Several studies have reported an increasing number of therapeutic failures with antiretroviral drugs in HIV-infected patients. The emergence of viral-resistant strains is a major problem for the medical management of infected individuals. The aim of this study is to determine viral subtypes and drug-resistance mutations among antiretroviral-treated HIV-infected patients.

METHODS

A total of 42 antiretroviral-treated but still viremic HIV-infected patients were enrolled. The HIV pol regions were amplified and sequenced to determine subtypes and antiretroviral-resistant mutations.

RESULTS

The subtype distribution was 48% A/D recombinants, 43% subtype B, 5% subtype A and 5% CRF01-AE recombinants. Drug-resistant mutations were most common in subtype B (53%) and A/D recombinant strains (44%). Virus samples from 19% of participants had no drug-resistant mutations; 2, 2 and 76% of samples carried one, two and at least three drug-resistant mutations, respectively. The prevalence of nucleoside transcriptase inhibitor mutations was 76%, with M184V and L74V present in 60 and 38% of samples, respectively. The prevalence of nonnucleoside transcriptase inhibitor mutations was 74%, with P225H present in 55% of study specimens. The prevalence of protease inhibitor mutations was 45%, with major mutation L90M seen in 33% and minor mutation A71V in 36% of samples. Of note, the P225H and A71V are 'minor' drug-resistance mutations conferring only minimal drug-resistance phenotypes in the absence of major mutations.

CONCLUSION

Our study found a high prevalence of drug-resistant mutations in Iranian HIV-infected patients. Our data support the need for continued surveillance of resistance patterns to help guide therapeutic approaches and limit transmission of these variants.

Hidden drug resistant HIV to emerge in the era of universal treatment access in Southeast Asia

BACKGROUND

Universal access to first-line antiretroviral therapy (ART) for HIV infection is becoming more of a reality in most low and middle income countries in Asia. However, second-line therapies are relatively scarce.

METHODS AND FINDINGS

We developed a mathematical model of an HIV epidemic in a Southeast Asian setting and used it to forecast the impact of treatment plans, without second-line options, on the potential degree of acquisition and transmission of drug resistant HIV strains. We show that after 10 years of universal treatment access, up to 20% of treatment-naïve individuals with HIV may have drug-resistant strains but it depends on the relative fitness of viral strains.

CONCLUSIONS

If viral load testing of people on ART is carried out on a yearly basis and virological failure leads to effective second-line therapy, then transmitted drug resistance could be reduced by 80%. Greater efforts are required for minimizing first-line failure, to detect virological failure earlier, and to procure access to second-line therapies.

Short-term antiretroviral therapy to prevent mother-to-child transmission is safe and results in a sustained increase in CD4 T-cell counts in HIV-1-infected mothers

BACKGROUND

Short-term antiretroviral therapy (START) to prevent mother-to-child transmission (MTCT) is currently recommended for all HIV-1-infected pregnant women. The objective of this study was to assess the effect on CD4 cell counts and viral load dynamics the withdrawal of START after birth could generate.

METHODS

This was a 5-year cohort study involving HIV-1-infected pregnant women who presented with CD4 counts >300 cells/microL and had received START to prevent MTCT.

RESULTS

Seventy-five pregnancies were assessed. In 24 cases, there was a history of antiretroviral therapy prior to prophylaxis. The median baseline CD4 count was 573 cells/microL. In 75% of cases, prophylaxis was started after 26.6 weeks of gestation. The median CD4 cell count increase over baseline during prophylaxis was 24.5%. In only five cases did HIV-1 viral load remain detectable during prophylaxis. After START, CD4 cell counts did not drop significantly, and the HIV-1 viral load plateau was near the baseline level. The estimated mean time for CD4 count to fall below 300 cells/microL was 3.5 years and was directly associated with high baseline CD4 cell count, as well as with CD4 increase after prophylaxis, whereas it was negatively correlated with previous use of antiretroviral (ARV) drugs and persistence of detectable HIV-1 viral load during prophylaxis.

CONCLUSIONS

A potent, well-tolerated prophylactic ARV regimen can improve CD4 cell counts during and after START. In women receiving such prophylaxis, there is a remarkable time interval for CD4 cell counts to drop to levels that indicate treatment.

Life expectancy after HIV diagnosis based on national HIV surveillance data from 25 states, United States

INTRODUCTION

We estimate life expectancy and average years of life lost (AYLL) after an HIV diagnosis using population-based surveillance data from 25 states that have had name-based HIV surveillance since 1996.

METHODS

We used US national HIV surveillance data (cases > or = 13 years old) to model life expectancy after an HIV diagnosis using the life table approach. We then compared life expectancy at HIV diagnosis with that in the general population of the same age, sex, and race/ethnicity in the same calendar year using vital statistics data to estimate the AYLL due to an HIV diagnosis.

RESULTS

Average life expectancy after HIV diagnosis increased from 10.5 to 22.5 years from 1996 to 2005. Life expectancy (years) was better for females than for males but improved less for females (females: 12.6-23.6 and males: 9.9-22.0). In 2005, life expectancy for black males was shortest, followed by Hispanic males and then white males. AYLL for cases diagnosed in 2005 was 21.1 years (males: 19.1 and females: 22.7) compared with 32.9 years in 1996.

CONCLUSIONS

Disparity in life expectancy for females and both black and Hispanic males, compared with males and white males, respectively, persists and should be addressed.

Antiretroviral tissue kinetics: in vivo imaging using positron emission tomography

Our current knowledge on the antiviral efficacy, dosing, and toxicity of available highly active antiretroviral therapy regimens is mostly derived from plasma or blood kinetics of anti-human immunodeficiency virus (anti-HIV) drugs. However, the blood comprises only 2% of the total target cells in the body. Tissue drug levels may differ substantially from corresponding plasma levels, and drug distribution processes may be characterized by high intertissue variability, leading to suboptimal target site concentrations and the potential risk for therapeutic failures. Positron emission tomography has greatly expanded the scope of the pharmacokinetic measurements that can be performed noninvasively in animal models or humans. We have prepared [18F]FPMPA, a fluorine-18-radiolabeled analogue of tenofovir, to study antiretroviral tissue kinetics in vivo noninvasively and tested the imaging probe in rats. The biodistribution of the fluorine-18 analogue closely follows that of nonfluorinated tenofovir. Compared to that in the blood, the levels of penetration of the antiretroviral drug were found to be significantly reduced in the spleen and submandibular lymph nodes (approximately 2-fold), in the mesenteric lymph nodes and the testes (approximately 4-fold), and in the brain compartment (approximately 25-fold). Intersubject variability of the trough drug concentration (measured at 120 min) in certain tissues, like the colon (coefficient of variation, >100%), is not reflected by the intersubject variability in the blood compartment (coefficient of variation, 24%). Positron emission tomography imaging of the fluorine-18 analogue revealed the accumulation of the antiretroviral drug in the cortex of the kidneys, a potential correlate of tenofovir-induced nephrotoxicity observed in HIV-1-infected treated patients. Thus, [18F]FPMPA is a promising radiotracer for evaluation of tenofovir biodistribution under carefully controlled drug administration protocols.

The effect of intrinsic stochasticity on transmitted HIV drug resistance patterns

Estimates of transmitted HIV drug-resistance prevalence vary widely among and within epidemiological surveys. Interpretation of trends from available survey data is therefore difficult. Because the emergence of drug-resistance involves small populations of infected drug-resistant individuals, the role of stochasticity (chance events) is likely to be important. The question addressed here is: how much variability in transmitted HIV drug-resistance prevalence patterns arises due to intrinsic stochasticity alone, i.e., if all starting conditions in the different epidemics surveyed were identical? This 'thought experiment' gives insight into the minimum expected variabilities within and among epidemics. A simple stochastic mathematical model was implemented. Our results show that stochasticity alone can generate a significant degree of variability and that this depends on the size and variation of the pool of new infections when drug treatment is first introduced. The variability in transmitted drug-resistance prevalence within an epidemic (i.e., the temporal variability) is large when the annual pool of all new infections is small (fewer than 200, typical of the HIV epidemics in Central European and Scandinavian countries) but diminishes rapidly as that pool grows. Epidemiological surveys involving hundreds of new infections annually are therefore needed to allow meaningful interpretation of temporal trends in transmitted drug-resistance prevalence within individual epidemics. The stochastic variability among epidemics shows a similar dependence on the pool of new infections if treatment is introduced after endemic equilibrium is established, but can persist even when there are more than 10,000 new infections annually if drug therapy is introduced earlier. Stochastic models may therefore have an important role to play in interpreting differences in transmitted drug-resistance prevalence trends among epidemiological surveys.

Misclassification of first-line antiretroviral treatment failure based on immunological monitoring of HIV infection in resource-limited settings

BACKGROUND

The monitoring of patients with human immunodeficiency virus (HIV) infection who are treated with antiretroviral medications in resource-limited settings is typically performed by use of clinical and immunological criteria. The early identification of first-line antiretroviral treatment failure is critical to prevent morbidity, mortality, and drug resistance. Misclassification of failure may result in premature switching to second-line therapy.

METHODS

Adult patients in western Kenya had their viral loads (VLs) determined if they had adhered to first-line therapy for >6 months and were suspected of experiencing immunological failure (ie, their CD4 cell count decreased by 25% in 6 months). Misclassification of treatment failure was defined as a 25% decrease in CD4 cell count with a VL of <400 copies/mL. Logistic and tree regressions examined relationships between VL and 4 variables: CD4 T cell count (hereafter CD4 cell count), percentage of T cells expressing CD4 (hereafter CD4 cell percentage), percentage decrease in the CD4 T cell count (hereafter CD4 cell count percent decrease), and percentage decrease in the percentage of T cells expressing CD4 (hereafter CD4% percent decrease).

RESULTS

There were 149 patients who were treated for 23 months; they were identified as having a 25% decrease in CD4 cell count (from 375 to 216 cells/microL) and a CD4% percent decrease (from 19% to 15%); of these 149 patients, 86 (58%) were misclassified as having experienced treatment failure. Of 42 patients who had a 50% decrease in CD4 cell count, 18 (43%) were misclassified. In multivariate logistic regression, misclassification odds were associated with a higher CD4 cell count, a shorter duration of therapy, and a smaller CD4% percent decrease. By combining these variables, we may be able to improve our ability to predict treatment failure.

CONCLUSIONS

Immunological monitoring as a sole indicator of virological failure would lead to a premature switch to valuable second-line regimens for 58% of patients who experience a 25% decrease in CD4 cell count and for 43% patients who experience a 50% decrease in CD4 cell count, and therefore this type of monitoring should be reevaluated. Selective virological monitoring and the addition of indicators like trends CD4% percent decrease and duration of therapy may systematically improve the identification of treatment failure. VL testing is now mandatory for patients suspected of experiencing first-line treatment failure within the Academic Model Providing Access to Healthcare (AMPATH) in western Kenya, and should be considered in all resource-limited settings.

Virological monitoring and resistance to first-line highly active antiretroviral therapy in adults infected with HIV-1 treated under WHO guidelines: a systematic review and meta-analysis

Antiretroviral-therapy rollout in resource-poor countries is often associated with limited, if any, HIV-RNA monitoring. The effect of variable monitoring on the emergence of resistance after therapy with commonly used drug combinations was assessed by systematic review of studies reporting resistance in patients infected with HIV with a CD4 count of fewer than 200 cells per muL treated with two nucleoside analogues (including a thymidine analogue) and a non-nucleoside reverse transcriptase inhibitor. 8376 patients from eight cohorts and two prospective studies were analysed. Resistance at virological failure to non-nucleoside reverse transcriptase inhibitors at 48 weeks was 88.3% (95% CI 82.2-92.9) in infrequently monitored patients, compared with 61.0% (48.9-72.2) in frequently monitored patients (p<0.001). Lamivudine resistance was 80.5% (72.9-86.8) and 40.3% (29.1-52.2) in infrequently and frequently monitored patients, respectively (p<0.001); the prevalence of at least one thymidine analogue mutation was 27.8% (21.2-35.2) and 12.1% (5.9-21.4), respectively (p<0.001). Genotypic resistance at 48 weeks to lamivudine, nucleoside reverse transcriptase inhibitors (thymidine analogue mutations), and non-nucleoside reverse transcriptase inhibitors appears substantially higher in less frequently monitored patients. This Review highlights the need for cheap point-of-care viral-load tests to identify early viral failures and limit the emergence of resistance.