Evolution of drug resistance in HIV-infected patients remaining on a virologically failing combination antiretroviral therapy regimen

Genetic landscape for majority and minority HIV-1 drug resistance mutations in antiretroviral therapy naive patients in Accra, Ghana

Background

The successful detection of drug-resistance mutations (DRMs) in HIV-1 infected patients has improved the management of HIV infection. Next-generation sequencing (NGS) to detect low-frequency mutations is predicted to be useful for efficiently testing minority drug resistance mutations, which could contribute to virological failure. This study employed Sanger sequencing and NGS to detect and compare minority and majority drug resistance mutations in HIV-1 strains in treatment-naive patients from Ghana.

Method

From a previous study, 20 antiretroviral therapy (ART)-naive participants were selected for a cross-sectional study. Sanger sequencing and NGS techniques were used to detect the majority and minority HIV drug resistance (HIVDR) mutations, respectively, in the protease (PR) and partial reverse transcriptase (RT) genes. NGS detected mutations at 1 % and 5 % frequencies and Sanger sequencing at ≥20 % frequencies. The sequences obtained from NGS and Sanger sequencing platforms were submitted to the Stanford HIV drug resistance database for subtyping, mutation identification, and interpretations.

Results

Sequences from the twenty participants where the CRF02_AG was the predominant strain (16, 80 %) were analyzed. NGS detected 25 mutations in the RT and PR genes, compared to 21 mutations by Sanger sequencing. Minority DRMs were detected at the prevalence of 55.0 % with NGS against 35 % DRMs by Sanger sequencing. One of the patients had eight different HIVDR variants, with two minority variants. These mutations were directed against PI (K20I and D30DN), NNRTI (Y181C, M23LM and V108I) and NRTI (K65R, M184I, and D67N).

Conclusion

The study affirms the usefulness of genomic sequencing for drug resistance testing in HIV. It further shows that Sanger sequencing alone may not be adequate to detect mutations and that NGS capacity should be developed and deployed in the Ghanaian clinical settings for patients living with HIV.

Thirteen-year viral suppression and immunologic recovery of LPV/r-based regimens in pediatric HIV treatment: a multicenter cohort study in resource-constrained settings of China

Background

Antiretroviral Therapy (ART) in children remains challenging due to resource-constrained settings. We conducted a 13-year, prospective, multicenter cohort study on the effectiveness and safety of LPV/r-based regimens in ART-naive and ART-experienced children.

Methods

From January 2008 to May 2021, children living with HIV-1 were recruited with LPV/r-based regimens from 8 clinical research sites in 6 provinces in China. Effectiveness outcomes were virologic failure (defined as at least two consecutive measurements of VL > 200 copies/mL after 6 months of ART) and immune response (defined as CD4% recovered to more than 25% after 12 months of treatment). The safety outcomes were treatment-related grade 2-4 adverse events and abnormal laboratory test results.

Results

A total of 345 ART-naïve children and 113 ART-experienced children were included in this cohort study. The median follow-up time was 7.3 (IQR 5.5-10.5) years. The incidence density of virologic failure was 4.1 (95% CI 3.3-4.9) per 100 person-years in ART-naïve children and 5.0 (95% CI 3.5-6.5) per 100 person-years in ART-experienced children. Kaplan Meyer (KM) curve analysis showed children with ART experience were at a higher risk of virologic failure (p < 0.05). The risk factors of virologic failure in ART-naïve children were clinic setting in rural hospitals (aHR = 2.251, 1.108-4.575), annual missed dose times >5 days of LPV intake (aHR = 1.889, 1.004-3.554); The risk factor of virologic failure in ART-experienced children was missed dose times >5 days (aHR = 2.689, 1.299-5.604) and mother as caregivers for ART administration (aHR = 0.475, 0.238-0.948). However, during long-term treatment, viral suppression rates between ART-naïve and ART-experienced children remained similar. No significant differences were observed in the immune response, treatment-related grade 2-4 events, and abnormal laboratory test results between ART-naïve children and ART-experienced children.

Conclusion

Our research underscores that with consistent, long-term treatment of LPV/r-based regimens, ART-experienced children can achieve therapeutic outcomes comparable to ART-naïve children. It provides crucial insights on LPV/r-based regimens in pediatric HIV treatment, especially in resource-limited settings where high-cost Integrase Strand Transfer Inhibitors (INSTs) are inaccessible. This evidence-based understanding provides an essential addition to the global therapeutic strategies for pediatric HIV treatment.

HIV-1 drug resistance mutations among individuals with low-level viraemia while taking combination ART in Botswana

OBJECTIVES

To assess whether a single instance of low-level viraemia (LLV) is associated with the presence of drug resistance mutations (DRMs) and predicts subsequent virological failure (VF) in adults receiving ART in 30 communities participating in the Botswana Combination Prevention Project.

METHODS

A total of 6078 HIV-1 C pol sequences were generated and analysed using the Stanford HIV drug resistance database. LLV was defined as plasma VL = 51-999 copies/mL and VF was defined as plasma VL ≥ 1000 copies/mL.

RESULTS

Among 6078 people with HIV (PWH), 4443 (73%) were on ART for at least 6 months. Of the 332 persons on ART with VL > 50 copies/mL, 175 (4%) had VL ≥ 1000 copies/mL and 157 (4%) had LLV at baseline. The prevalence of any DRM was 57 (36%) and 78 (45%) in persons with LLV and VL ≥ 1000 copies/mL, respectively. Major DRMs were found in 31 (20%) with LLV and 53 (30%) with VL ≥ 1000 copies/mL (P = 0.04). Among the 135 PWH with at least one DRM, 17% had NRTI-, 35% NNRTI-, 6% PI- and 3% INSTI-associated mutations. Among the 3596 participants who were followed up, 1709 (48%) were on ART for ≥6 months at entry and had at least one subsequent VL measurement (median 29 months), 43 (3%) of whom had LLV. The OR of experiencing VF in persons with LLV at entry was 36-fold higher than in the virally suppressed group.

CONCLUSIONS

A single LLV measurement while on ART strongly predicted the risk of future VF, suggesting the use of VL > 50 copies/mL as an indication for more intensive adherence support with more frequent VL monitoring.

Expansion of Viral Load Testing and the Potential Impact on Human Immunodeficiency Virus Drug Resistance

Increasing the volume, strengthening the quality, and proactively using data of human immunodeficiency virus (HIV) load testing are pivotal to limiting the threat of HIV drug resistance (HIVDR) accumulation,and allow for optimal case-based HIVDR surveillance. Triangulation of viral load (VL) and HIVDR testing data could be pursued to answer key questions and translate data and results for program and public policy. Identification of virologic failure and early management mitigates the greater risk of HIVDR. Routine VL monitoring and evaluation systems are necessary, and countries should consider reviewing system requirements, structural needs, and procedural and technical factors for the entire VL cascade, with special emphasis on post-test result use.

Sensitive detection of HIV-1 resistance to Zidovudine and impact on treatment outcomes in low- to middle-income countries

Background

Thymidine analogs, namely AZT (Zidovudine or Retrovir™) and d4T (Stavudine or Zerit™) are antiretroviral drugs still employed in over 75% of first line combination antiretroviral therapy (cART) in Kampala, Uganda despite aversion to prescribing these drugs for cART in high income countries due in part to adverse events. For this study, we explored how the continued use of these thymidine analogs in cART could impact emergence of drug resistance and impact on future treatment success in Uganda, a low-income country.

Methods

We examined the drug resistance genotypes by Sanger sequencing of 262 HIV-infected patients failing a first line combined antiretroviral treatment containing either AZT or d4T, which represents approximately 5% of the patients at the Joint Clinical Research Center receiving a AZT or d4T containing treatment. Next generation sequencing (DEEPGEN™HIV) and multiplex oligonucleotide ligation assays (AfriPOLA) were then performed on a subset of patient samples to detect low frequency drug resistant mutations. CD4 cell counts, viral RNA loads, and treatment changes were analyzed in a cohort of treatment success and failures.

Results

Over 80% of patients failing first line AZT/d4T-containing cART had predicted drug resistance to 3TC (Lamivudine) and non-nucleoside RT inhibitors (NNRTIs) in the treatment regimen but only 45% had resistance AZT/d4T associated resistance mutations (TAMs). TAMs were however detected at low frequency within the patients HIV quasispecies (1–20%) in 21 of 34 individuals who were failing first-line AZT-containing cART and lacked TAMs by Sanger. Due to lack of TAMs by Sanger, AZT was typically maintained in second-line therapies and these patients had a low frequency of subsequent virologic success.

Conclusions

Our findings suggest that continued use of AZT and d4T in first-line treatment in low-to-middle income countries may lead to misdiagnosis of HIV-1 drug resistance and possibly enhance a succession of second- and third-line treatment failures.

Electronic supplementary material

The online version of this article (doi: 10.1186/s40249-017-0377-0) contains supplementary material, which is available to authorized users.

Implication of First-Line Antiretroviral Therapy Choice on Second-Line Options

BACKGROUND

Although there are a number of studies comparing the currently recommended preferred and alternative first-line (1L) antiretroviral therapy (ART) regimens on clinical outcomes, there are limited data examining the impact of 1L regimen choice and duration of virologic failure (VF) on accumulation of drug resistance mutations (DRM). The patterns of DRM from patients failing zidovudine (AZT)-containing versus tenofovir (TDF)-containing ART were assessed to evaluate the predicted susceptibility to second-line (2L) nucleoside reverse-transcriptase inhibitor (NRTI) backbone options in the context of an ongoing programmatic setting that uses viral load (VL) monitoring.

METHODS

Paired samples from Nigerian ART patients who experienced VF and switched to 2L ART were retrospectively identified. For each sample, the human immunodeficiency virus (HIV)-1 polymerase gene was sequenced at 2 time points, and DRM was analyzed using Stanford University's HIVdb program.

RESULTS

Sequences were generated for 191 patients. At time of 2L switch, 28.2% of patients on AZT-containing regimens developed resistance to TDF, whereas only 6.8% of patients on TDF-containing 1L had mutations compromising susceptibility to AZT. In a stratified evaluation, patients with 0-6 months between tested VL samples had no difference in proportion compromised to 2L, whereas those with >6 months between samples had a statistically significant difference in proportion with compromised 2L NRTI. In multivariate analyses, patients on 1L AZT had 9.90 times higher odds of having a compromised 2L NRTI option than patients on 1L TDF.

CONCLUSIONS

In the context of constrained resources, where VL monitoring is limited, we present further evidence to support use of TDF as the preferred 1L NRTI because it allows for preservation of the recommended 2L NRTI option.

Field Evaluation of Dried Blood Spots for HIV-1 Viral Load Monitoring in Adults and Children Receiving Antiretroviral Treatment in Kenya: Implications for Scale-up in Resource-Limited Settings

BACKGROUND

The World Health Organization recommends viral load (VL) as the preferred method for diagnosing antiretroviral therapy failure; however, operational challenges have hampered the implementation of VL monitoring in most resource-limited settings. This study evaluated the accuracy of dried blood spot (DBS) VL testing under field conditions as a practical alternative to plasma in determining virologic failure (VF).

METHODS

From May to December 2013, paired plasma and DBS specimens were collected from 416 adults and 377 children on antiretroviral therapy for ≥6 months at 12 clinics in Kenya. DBSs were prepared from venous blood (V-DBS) using disposable transfer pipettes and from finger-prick capillary blood using microcapillary tubes (M-DBS) and directly spotting (D-DBS). All samples were tested on the Abbott m2000 platform; V-DBS was also tested on the Roche COBAS Ampliprep/COBAS TaqMan (CAP/CTM) version 2.0 platform. VF results were compared at 3 DBS thresholds (≥1000, ≥3000, and ≥5000 copies/mL) and a constant plasma threshold of ≥1000 copies/mL.

RESULTS

On the Abbott platform, at ≥1000-copies/mL threshold, sensitivities, specificities, and kappa values for VF determination were ≥88.1%, ≥93.1%, and ≥0.82%, respectively, for all DBS methods, and it had the lowest percentage of downward misclassification compared with higher thresholds. V-DBS performance on CAP/CTM had significantly poorer specificity at all thresholds (1000%-33.0%, 3000%-60.9%, and 5000%-77.0%). No significant differences were found between adults and children.

CONCLUSIONS

VL results from V-DBS, M-DBS, and D-DBS were comparable with those from plasma for determining VF using the Abbott platform but not with CAP/CTM. A 1000-copies/mL threshold was optimal and should be considered for VF determination using DBS in adults and children.

Cross-sectional study of virological failure and multinucleoside reverse transcriptase inhibitor resistance at 12 months of antiretroviral therapy in Western India

The free antiretroviral therapy (ART) program in India has scaled up to register second largest number of people living with HIV/AIDS across the globe. To assess the effectiveness of current first-line regimen we estimated virological suppression on completion of 1 year of ART. The study describes the correlates of virological failure (VF) and multinucleoside reverse transcriptase inhibitor (NRTI) drug resistance mutations (DRMs).In this cross-sectional study conducted between June and August 2014, consecutive adults from 4 State sponsored ART clinics of western India were recruited for plasma viral load screening at 12 ± 2 months of ART initiation. Individuals with plasma viral load >1000 copies/mL were selected for HIV drug resistance (HIVDR) genotyping. Logistic regression analyses were performed to assess factors associated with VF and multi-NRTI resistance mutations. Criteria adopted for multi-NRTI resistance mutation were either presence of K65R or 3 or more thymidine analog mutations (TAMs) or presence of M184V along with 2 TAMs.Of the 844 study participants, virological suppression at 1 year was achieved in 87.7% of individuals. Factors significantly associated with VF (P < 0.005) were 12 months CD4 count of ≤100 cells/μL (adjusted OR -7.11), low reported adherence (adjusted OR -4.44), and those living without any partner (adjusted OR -1.98). In patients with VF, the prevalence of non-nucleoside reverse transcriptase inhibitor (NNRTI) DRM (78.75%) were higher as compared to NRTI (58.75%). Multi-NRTI DRMs were present in 32.5% of sequences and were significantly associated with CD4 count of ≤100 cells/μL at baseline (adjusted OR -13.00) and TDF-based failing regimen (adjusted OR -20.43). Additionally, low reported adherence was negatively associated with multi-NRTI resistance (adjusted OR -0.11, P = 0.015). K65R mutation was significantly associated with tenofovir (TDF)-based failing regimen (P < 0.001).The study supports early linkage of HIV-infected individuals to the program for ART initiation, adherence improvement, and introduction of viral load monitoring. With recent introduction of TDF-based regimen, the emergence of K65R needs to be monitored closely among HIV-1 subtype C-infected Indian population.

HIV-1 Drug Resistance and Second-Line Treatment in Children Randomized to Switch at Low Versus Higher RNA Thresholds

BACKGROUND

The PENPACT-1 trial compared virologic thresholds to determine when to switch to second-line antiretroviral therapy (ART). Using PENPACT-1 data, we aimed to describe HIV-1 drug resistance accumulation on first-line ART by virologic threshold.

METHODS

PENPACT-1 had a 2 × 2 factorial design, randomizing HIV-infected children to start protease inhibitor (PI) versus nonnucleoside reverse transcriptase inhibitor (NNRTI)-based ART, and switch at a 1000 copies/mL versus 30,000 copies/mL threshold. Switch criteria were not achieving the threshold by week 24, confirmed rebound above the threshold thereafter, or Center for Disease Control and Prevention stage C event. Resistance tests were performed on samples ≥1000 copies/mL before switch, resuppression, and at 4-years/trial end.

RESULTS

Sixty-seven children started PI-based ART and were randomized to switch at 1000 copies/mL (PI-1000), 64 PIs and 30,000 copies/mL (PI-30,000), 67 NNRTIs and 1000 copies/mL (NNRTI-1000), and 65 NNRTI and 30,000 copies/mL (NNRTI-30,000). Ninety-four (36%) children reached the 1000 copies/mL switch criteria during 5-year follow-up. In 30,000 copies/mL threshold arms, median time from 1000 to 30,000 copies/mL switch criteria was 58 (PI) versus 80 (NNRTI) weeks (P = 0.81). In NNRTI-30,000, more nucleoside reverse transcriptase inhibitor (NRTI) resistance mutations accumulated than other groups. NNRTI mutations were selected before switching at 1000 copies/mL (23% NNRTI-1000, 27% NNRTI-30,000). Sixty-two children started abacavir + lamivudine, 166 lamivudine + zidovudine or stavudine, and 35 other NRTIs. The abacavir + lamivudine group acquired fewest NRTI mutations. Of 60 switched to second-line, 79% PI-1000, 63% PI-30,000, 64% NNRTI-1000, and 100% NNRTI-30,000 were <400 copies/mL 24 weeks later.

CONCLUSIONS

Children on first-line NNRTI-based ART who were randomized to switch at a higher virologic threshold developed the most resistance, yet resuppressed on second-line. An abacavir + lamivudine NRTI combination seemed protective against development of NRTI resistance.

Outcomes of antiretroviral treatment in HIV-infected adults: a dynamic and observational cohort study in Shenzhen, China, 2003-2014

OBJECTIVES

To report 10-year outcomes of virological and immunological treatment failure rates and risk factors.

DESIGN

Prospective cohort study.

SETTING

Shenzhen, China.

PARTICIPANTS

2172 HIV-positive adults in the national treatment database of Shenzhen from December 2003 to January 2014.

INTERVENTION

Antiretroviral therapy according to the Chinese national treatment guidelines.

OUTCOME MEASURES

Virological and immunological treatment failure rates.

RESULTS

Of the 3099 patients surveyed, 2172 (70.1%) were included in the study. The median age was 33 years; 78.2% were male and 51.8% were infected through heterosexual contact. The median follow-up time was 31 months (IQR, 26-38). A total of 81 (3.7%) patients died, whereas 292 (13.4%) and 400 (18.4%) patients experienced virological and immunological failures, respectively. Adjusted Cox regression analysis indicated that baseline viral load (HR=2.19, 95% CI 1.52 to 4.48 for patients with a baseline viral load greater than or equal to 1,000,000 copies/mL compared to those with less than 10,000 copies/mL) and WHO stage (HR=4.16, 95% CI 2.01 to 10.57 for patients in WHO stage IV compared with those in stage I) were significantly associated with virological failure. The strongest risk factors for immunological treatment failure were a low CD4 cell count (HR=0.46, 95% CI 0.32 to 0.66 for patients with CD4 cell counts of 50-99 cells/mm(3) compared to those with less than 50 cells/mm(3)) and higher baseline WHO stage at treatment initiation (HR=2.15, 95% CI 1.38 to 3.34 for patients in WHO stage IV compared to those in stage I).

CONCLUSIONS

Sustained virological and immunological outcomes show that patients have responded positively to long-term antiretroviral treatment with low mortality. This 10-year data study provides important information for clinicians and policymakers in the region as they begin to evaluate and plan for the future needs of their own rapidly expanding programmes.

HIV-1 integrase genotyping is reliable and reproducible for routine clinical detection of integrase resistance mutations even in patients with low-level viraemia

OBJECTIVES

Integrase drug resistance monitoring deserves attention because of the increasing number of patients being treated with integrase strand-transfer inhibitors. Therefore, we evaluated the integrase genotyping success rate at low-level viraemia (LLV, 51-1000 copies/mL) and resistance in raltegravir-failing patients.

METHODS

An integrase genotypic resistance test (GRT) was performed on 1734 HIV-1 samples collected during 2006-13. Genotyping success rate was determined according to the following viraemia levels: 51-500, 501-1000, 1001-10 000, 10 001-100 000 and >100 000 copies/mL. The reproducibility of integrase GRT was evaluated in 41 plasma samples processed in duplicate in two reference centres. The relationship between LLV and resistance prevalence was evaluated in a subset of 120 raltegravir-failing patients.

RESULTS

Overall, the integrase genotyping success rate was 95.7%. For viraemia levels 51-500 and 501-1000 copies/mL, the rate of success was 82.1% and 94.0%, respectively. GRT was reproducible, producing sequences with a high similarity and an equal resistance profile regardless of the sequencing centre or viraemia level. Resistance was detected both at LLV and at viraemia >1000 copies/mL (51-500 copies/mL = 18.2%; 501-1000 = 37.5%; 1001-10 000 = 53.7%; 10 001-100 000 = 30.0%; and >100 000 = 30.8%). At viraemia ≤500 copies/mL, Q148H/K/R and N155H had the same prevalence (9.1%), while the Y143C/H/R was completely absent. At early genotyping (within 3 months of raltegravir treatment), Q148H/K/R and N155H mutations were detected regardless of the viraemia level, while Y143C/H/R was observed only in samples with viraemia >1000 copies/mL.

CONCLUSIONS

Our findings prove the reliability of HIV-1 integrase genotyping and reinforce the concept that this assay may be useful in the management of failures even at LLV.

Alteration of select gene expression patterns in individuals infected with HIV-1

Multiple human proteins have been shown to both support and restrict viral replication, and confirmation of virus-associated changes in the expression of these genes is relevant for future therapeutic efforts. In this study a well-characterized panel of 49 individuals either infected with HIV-1 or uninfected was compiled and analyzed for the effect of HIV infection status, viral load, and antiretroviral treatment on specific gene expression. mRNA was extracted and reverse transcribed from purified CD4+ cells, and quantitative real-time PCR was utilized to scrutinize differences in the expression of four host genes that have been demonstrated to either stimulate (HSP90 and LEDGF/p75) or restrict (p21/WAF1 and APOBEC3G) proviral integration. HIV infection status was associated with slight to moderate alterations in the expression of all four genes. After adjusting for age, mRNA expression levels of HSP90, LEDGF/p75 and APOBEC3G were found to all be decreased in infected patients compared to healthy controls by 1.43-, 1.26-, and 4.71-fold, respectively, while p21/WAF1 expression was increased 2.35-fold. Furthermore, individuals receiving raltegravir exhibited a 1.28-fold reduction in LEDGF/p75 compared to those on non-raltegravir antiretroviral treatment. Identification of these and similar HIV-induced changes in gene expression may be valuable for delineating the extent of host cell molecular mechanisms stimulating viral replication.

Cost-effectiveness of newer antiretroviral drugs in treatment-experienced patients with multidrug-resistant HIV disease

OBJECTIVE

Newer antiretroviral drugs provide substantial benefits but are expensive. The cost-effectiveness of using antiretroviral drugs in combination for patients with multidrug-resistant HIV disease was determined.

DESIGN

A cohort state-transition model was built representing treatment-experienced patients with low CD4 counts, high viral load levels, and multidrug-resistant virus. The effectiveness of newer drugs (those approved in 2005 or later) was estimated from published randomized trials. Other parameters were estimated from a randomized trial and from the literature. The model had a lifetime time horizon and used the perspective of an ideal insurer in the United States. The interventions were combination antiretroviral therapy, consisting of 2 newer drugs and 1 conventional drug, compared with 3 conventional drugs. Outcome measures were life-years, quality-adjusted life-years (QALYs), costs, and incremental cost-effectiveness.

RESULTS

Substituting newer antiretroviral drugs increased expected survival by 3.9 years in advanced HIV disease. The incremental cost-effectiveness ratio of newer, compared with conventional, antiretroviral drugs was $75,556/QALY gained. Sensitivity analyses showed that substituting only one newer antiretroviral drug cost $54,559 to $68,732/QALY, depending on assumptions about efficacy. Substituting 3 newer drugs cost $105,956 to $117,477/QALY. Cost-effectiveness ratios were higher if conventional drugs were not discontinued.

CONCLUSIONS

In treatment-experienced patients with advanced HIV disease, use of newer antiretroviral agents can be cost-effective, given a cost-effectiveness threshold in the range of $50,000 to $75,000 per QALY gained. Newer antiretroviral agents should be used in carefully selected patients for whom less expensive options are clearly inferior.

Impact of HIV drug resistance on virologic and immunologic failure and mortality in a cohort of patients on antiretroviral therapy in China

Objectives:

To study the dynamics of HIV drug resistance (HIVDR) and its association with virologic and immunologic failure as well as mortality among patients on combination antiretroviral therapy (cART) in China.

Design:

We recruited 365 patients on cART in two rural Chinese counties in 2003–2004 and followed them every 6 months until May 2010.

Methods:

Virologic failure, HIVDR, immunologic failure and death were documented. We used Kaplan–Meier and the proportional hazards models to identify the timing of the events, and risk factors for mortality.

Results:

At the end of study, patients had been followed for 1974.3 person-years, a median of 6.1 years. HIVDR mutations were found in 235 (64.4%) patients and 75 died (20.5%, 3.8/100 person-years). Median time from cART to detection of virologic failure was 17.5 months, to HIVDR 36.6 months and to immunologic failure 55.2 months (≈18-month median interval between each adverse milestone). Being male, having a baseline CD4⁺ cell count of less than 50 cells/μl and HIVDR were associated with higher mortality. Patients who developed HIVDR in the first year of treatment had higher mortality than those developing HIVDR later (adjusted hazard ratio 1.90, 95% confidence interval 1.01–3.48).

Conclusion:

HIVDR was common and was associated with higher mortality among Chinese patients on cART, particular when HIVDR was detected early in therapy. Our study reinforces the importance of improving patient adherence to cART in order to delay the emergence of HIVDR and obviate the need to switch to costly second-line drug regimens too early.

Antiretroviral treatment strategies in highly treatment experienced perinatally HIV-infected youth

BACKGROUND

There is limited information on antiretroviral (ARV) regimens and outcomes in perinatally HIV (PHIV)-infected youth. Substantial drug resistance after long-term ARV use and nonadherence hinder efforts to design suppressive regimens for PHIV-infected youth. This study compares clinical outcomes by expected activity of the prescribed ARV regimens.

METHODS

A retrospective cohort study of 13- to 24-year-old PHIV-infected youth on stable ARV regimens for ≥6 months was conducted at a pediatric HIV clinic. ARV regimens were retrospectively categorized as optimal or suboptimal based on accumulated genotypic resistance before study regimen initiation.

RESULTS

Fifty-two patients with similar baseline characteristics met inclusion criteria (21 optimal and 31 suboptimal regimens). Patients receiving optimal regimens had significantly higher increases in CD4 than those given suboptimal regimens by week 48 of treatment (+62 versus +8 cells/mm, respectively; P = 0.04) and by the end of study period (+93 versus -1 cells/mm, respectively; P = 0.03). There were no significant differences between the groups in decline of viral load, frequency of opportunistic infections or hospitalizations or accumulation of resistance mutations. Overall, 60% of the optimal and 45% of the suboptimal groups had nonadherence during the study regimen (P = 0.3).

CONCLUSIONS

PHIV-infected youth receiving optimal regimens had greater CD4 improvements but no difference in virologic outcomes compared with those receiving suboptimal regimens. In a patient population with significant nonadherence, providers must weigh the immunologic benefits of initiating an optimal regimen versus the potential risks of further resistance accumulation limiting future treatment options.

Long-lasting protection of activity of nucleoside reverse transcriptase inhibitors and protease inhibitors (PIs) by boosted PI containing regimens

BACKGROUND

The accumulation of mutations after long-lasting exposure to a failing combination antiretroviral therapy (cART) is problematic and severely reduces the options for further successful treatments.

METHODS

We studied patients from the Swiss HIV Cohort Study who failed cART with nucleoside reverse transcriptase inhibitors (NRTIs) and either a ritonavir-boosted PI (PI/r) or a non-nucleoside reverse transcriptase inhibitor (NNRTI). The loss of genotypic activity <3, 3-6, >6 months after virological failure was analyzed with Stanford algorithm. Risk factors associated with early emergence of drug resistance mutations (<6 months after failure) were identified with multivariable logistic regression.

RESULTS

Ninety-nine genotypic resistance tests from PI/r-treated and 129 from NNRTI-treated patients were analyzed. The risk of losing the activity of ≥1 NRTIs was lower among PI/r- compared to NNRTI-treated individuals <3, 3-6, and >6 months after failure: 8.8% vs. 38.2% (p = 0.009), 7.1% vs. 46.9% (p<0.001) and 18.9% vs. 60.9% (p<0.001). The percentages of patients who have lost PI/r activity were 2.9%, 3.6% and 5.4% <3, 3-6, >6 months after failure compared to 41.2%, 49.0% and 63.0% of those who have lost NNRTI activity (all p<0.001). The risk to accumulate an early NRTI mutation was strongly associated with NNRTI-containing cART (adjusted odds ratio: 13.3 (95% CI: 4.1-42.8), p<0.001).

CONCLUSIONS

The loss of activity of PIs and NRTIs was low among patients treated with PI/r, even after long-lasting exposure to a failing cART. Thus, more options remain for second-line therapy. This finding is potentially of high relevance, in particular for settings with poor or lacking virological monitoring.

Optimizing treatment switch for virologic failure during first-line antiretroviral therapy in resource-limited settings

We evaluated adult Nigerian patients with antiretroviral switch to second-line treatment with ritonavir-boosted protease inhibitor (PI/r)-based regimens due to virologic failure (confirmed HIV-1 RNA viral load [VL] >1000 copies/mL) during first-line antiretroviral therapy. Proportion of patients with VL >400 copies/mL and characteristics associated with nonsuppression during second-line treatment are described. Approximately 15% of patients (34 of 225) had VL >400 copies/mL at 1-year after treatment switch to PI/r-based regimens. In adjusted analyses, VL ≥5 log10 copies/mL at treatment switch (odds ratio [OR] 2.90 [confidence interval (CI) 1.21-6.93]); duration of first-line treatment after virologic failure >180 days (OR 2.56 [CI 1.0-6.54]); and PI/r regimen adherence <90% (OR 3.27 [CI 1.39-7.68]) were associated with VL >400 copies/mL at 1 year of second-line treatment. We therefore recommend that the maximum permissible time between suspicion of virologic failure and completion of antiretroviral treatment switch should not exceed 6 months when patients develop first-line antiretroviral failure in resource-limited settings.

Impact of low-level-viremia on HIV-1 drug-resistance evolution among antiretroviral treated-patients

BACKGROUND

Drug-resistance mutations (DRAM) are frequently selected in patients with virological failure defined as viral load (pVL) above 500 copies/ml (c/mL), but few resistance data are available at low-level viremia (LLV). Our objective was to determine the emergence and evolution of DRAM during LLV in HIV-1-infected patients while receiving antiretroviral therapy (ART).

METHODS

Retrospective analysis of patients presenting a LLV episode defined as pVL between 40 and 500 c/mL on at least 3 occasions during a 6-month period or longer while on the same ART. Resistance genotypic testing was performed at the onset and at the end of LLV period. Emerging DRAM was defined during LLV if never detected on baseline genotype or before.

RESULTS

48 patients including 4 naive and 44 pretreated (median 9 years) presented a LLV episode with a median duration of 11 months. Current ART included 2NRTI (94%), ritonavir-boosted PI (94%), NNRTI (23%), and/or raltegravir (19%). Median pVL during LLV was 134 c/mL. Successful resistance testing at both onset and end of the LLV episode were obtained for 37 patients (77%), among who 11 (30%) acquired at least 1 DRAM during the LLV period: for NRTI in 6, for NNRTI in 1, for PI in 4, and for raltegravir in 2. During the LLV period, number of drugs with genotypic resistance increased from a median of 4.5 to 6 drugs. Duration and pVL level of LLV episode, duration of previous ART, current and nadir CD4 count, number of baseline DRAM and GSS were not identified as predictive factors of resistance acquisition during LLV, probably due to limited number of patients.

CONCLUSION

Persistent LLV episodes below 500 c/ml while receiving ART is associated with emerging DRAM for all drug classes and a decreasing in further therapeutic options, suggesting to earlier consider resistance monitoring and ART optimization in this setting.

Patterns of HIV-1 drug resistance after first-line antiretroviral therapy (ART) failure in 6 sub-Saharan African countries: implications for second-line ART strategies

BACKGROUND

Human immunodeficiency virus type 1 (HIV-1) drug resistance may limit the benefits of antiretroviral therapy (ART). This cohort study examined patterns of drug-resistance mutations (DRMs) in individuals with virological failure on first-line ART at 13 clinical sites in 6 African countries and predicted their impact on second-line drug susceptibility.

METHODS

A total of 2588 antiretroviral-naive individuals initiated ART consisting of different nucleoside reverse transcriptase inhibitor (NRTI) backbones (zidovudine, stavudine, tenofovir, or abacavir, plus lamivudine or emtricitabine) with either efavirenz or nevirapine. Population sequencing after 12 months of ART was retrospectively performed if HIV RNA was >1000 copies/mL. The 2010 International Antiviral Society-USA list was used to score major DRMs. The Stanford algorithm was used to predict drug susceptibility.

RESULTS

HIV-1 sequences were generated for 142 participants who virologically failed ART, of whom 70% carried ≥1 DRM and 49% had dual-class resistance, with an average of 2.4 DRMs per sequence (range, 1-8). The most common DRMs were M184V (53.5%), K103N (28.9%), Y181C (15.5%), and G190A (14.1%). Thymidine analogue mutations were present in 8.5%. K65R was frequently selected by stavudine (15.0%) or tenofovir (27.7%). Among participants with ≥1 DRM, HIV-1 susceptibility was reduced in 93% for efavirenz/nevirapine, in 81% for lamivudine/emtricitabine, in 59% for etravirine/rilpivirine, in 27% for tenofovir, in 18% for stavudine, and in 10% for zidovudine.

CONCLUSIONS

Early failure detection limited the accumulation of resistance. After stavudine failure in African populations, zidovudine rather than tenofovir may be preferred in second-line ART. Strategies to prevent HIV-1 resistance are a global priority.

Immunologic criteria are poor predictors of virologic outcome: implications for HIV treatment monitoring in resource-limited settings

BACKGROUND

Viral load (VL) quantification is considered essential for determining antiretroviral treatment (ART) success in resource-rich countries. However, it is not widely available in resource-limited settings where the burden of human immunodeficiency virus infection is greatest. In the absence of VL monitoring, switches to second-line ART are based on World Health Organization (WHO) clinical or immunologic failure criteria.

METHODS

We assessed the performance of CD4 cell criteria to predict virologic outcomes in a large ART program in Nigeria. Laboratory monitoring consists of CD4 cell count and VL at baseline, then every 6 months. Failure was defined as 2 consecutive VLs >1000 copies/mL after at least 6 months of ART. Virologic outcomes were compared with the 3 WHO-defined immunologic failure criteria.

RESULTS

A total of 9690 patients were included in the analysis (median follow-up, 33.2 months). A total of 1225 patients experienced failure by both immunologic and virologic criteria, 872 by virologic criteria only, and 1897 by immunologic criteria only. The sensitivity of CD4 cell criteria to detect viral failure was 58%, specificity was 75%, and the positive-predictive value was 39%. For patients with both virologic and immunologic failure, VL criteria identified failure significantly earlier than CD4 cell criteria (median, 10.4 vs 15.6 months; P < .0001).

CONCLUSIONS

Because of the low sensitivity of immunologic criteria, a substantial number of failures are missed, potentially resulting in accumulation of resistance mutations. In addition, specificity and predictive values are low, which may result in large numbers of unnecessary ART switches. Monitoring solely by immunologic criteria may result in increased costs because of excess switches to more expensive ART and development of drug-resistant virus.

Low rates of nucleoside reverse transcriptase inhibitor resistance in a well-monitored cohort in South Africa on antiretroviral therapy

BACKGROUND

The emergence of complex HIV-1 drug resistance mutations has been linked to the duration of time patients are on a failing antiretroviral drug regimen. This study reports on resistance profiles in a closely monitored subtype C infected cohort.

METHODS

A total of 812 participants were enrolled into the CIPRA-SA 'safeguard the household' study, viral loads were determined at 12-weekly intervals for 96 weeks. Virological failure was defined as either a <1.5 log decrease in viral load at week 12 or two consecutive viral load measurements of >1,000 RNA copies/ml after week 24. Regimens prescribed were in line with the South African roll-out programme (stavudine, lamivudine, efavirenz or nevirapine). Viral RNA was extracted from patients with virological failure, and pol reverse-transcriptase PCR and sequence analysis were performed to determine drug-resistant mutations.

RESULTS

Virological failure was observed in 83 participants on the first-line regimen during the study period, of which 61 (73%) had HIV-1 drug-resistant mutations. The M184V mutation was the most frequent (n=46; 65%), followed by K103N (46%) and Y181C (21%). Thymidine analogue mutations were infrequent (1%) and Q151M was not observed.

CONCLUSIONS

Drug resistance profiles were less complex than has been previously reported in South Africa using the same antiretroviral drug regimens. These data suggest that frequent viral load monitoring limits the level and complexity of resistance observed in HIV-1 subtype C, preserving susceptibility to second-line options.

HIV and hepatitis virus resistance to antivirals: review of data from the XIX International HIV and Hepatitis Virus Drug Resistance Workshop and curative strategies

The XIX International HIV and Hepatitis Virus Drug Resistance Workshop offered scientists, clinical investigators, physicians and others an opportunity to present study results selected in a rigorous peer-review process and to discuss those data in an open forum. In 2010, Workshop organizers expanded the programme to include hepatitis B and C viruses, reasoning that workers in all three fields could benefit from shared experience, positive and negative. Slide sessions at the 2010 Workshop focused on hepatitis virus resistance to current and experimental antivirals; epidemiology of HIV resistance; HIV pathogenesis, fitness and resistance; resistance to new antiretrovirals; markers of response to HIV entry inhibitors; HIV persistence, reservoirs and elimination strategies; application of new viral sequencing techniques; and mechanisms of HIV drug resistance. This article summarizes all slide presentations at the Workshop.

Genotypic impact of prolonged detectable HIV type 1 RNA viral load after HAART failure in a CRF01_AE-infected cohort

HIV subtype-specific data on mutation type, rate, and accumulation following HAART treatment failure are limited. We studied patterns and accrual of drug resistance mutations in a Cambodian CRF01_AE-infected cohort continuing a virologically failing first-line, nonnucleoside reverse transcriptase inhibitor- (NNRTI-) based, HAART. Between 2005 and 2007, 837 adult HIV-infected patients had regular plasma HIV-1 RNA viral load measurements at Sihanouk Hospital Centre of Hope (SHCH), Cambodia. Drug resistance testing was performed in all patients with HIV-1 RNA >1000 copies/ml after at least 6 months of HAART. Seventy-one patients with a mean age of 34 years, of whom 68% were male, were retrospectively assessed at virological failure. The median duration of antiretroviral therapy was 12.3 (IQR 7.1-18.23) months, the median CD4 cell count was 173 (IQR 118-256) cells/mm(3), and the mean plasma HIV-1 RNA viral load was 3.9 log (SD 0.72) at failure. NNRTI mutations, M184I/V mutation, thymidine analogue mutations, and K65R were observed in 78.9%, 69%, 20%, and 12.7% of patients, respectively. For 33 patients, genotypic testing was carried out on at least two occasions before the switch to second-line HAART after a median duration of 5.8 (IQR 4.3-6.1) months of virological failure: 54.5% of patients accumulated new mutations with a rate of 1.6 mutations per person-year. Accumulation was seen both for nucleoside and nonnucleoside reverse transcriptase inhibitors, and also in patients with low-level viremia. Subtype-specific data on mutation type, rate, and accumulation after HAART failure are urgently needed to optimize treatment strategies in resource-limited settings.

The use of human immunodeficiency virus resistance tests in clinical practice

Important progress has been made in recent years in the development and clinical use of drugs for the treatment of human immunodeficiency virus type 1 (HIV-1) infection. Nevertheless, when antiretroviral therapy fails to be fully suppressive, new viral variants emerge, thus allowing HIV-1 to escape from drug pressure by accumulating mutations. Between 50% and 70% of treated patients with virological rebound harbour some form of drug-resistant virus; transmitted drug resistance in drug-naïve populations has reached 5-20% in areas of the world with access to treatment. The emergence of drug-resistant viruses remains the limiting factor in HIV-1 management, being a major cause of treatment failure, and being associated with clinical progression and death. All international guidelines focus on the importance of tailoring antiretroviral therapy to the individual patient, on the basis onf HIV-1 genetic data, integrated with clinical, laboratory and therapeutic information. The aim of this review is to provide useful information to clinicians and virologists about how and when to use genotypic resistance testing in clinical practice, especially in the management of the first stages of HIV-1 patient care and treatment decisions.

Economic evaluation of monitoring virologic responses to antiretroviral therapy in HIV-infected children in resource-limited settings

OBJECTIVE

Antiretroviral therapy (ART) management for HIV-infected children is critical in many resource-constrained countries. We investigated the cost-effectiveness and cost-utility of different frequencies of monitoring plasma viral load among HIV-positive children initiating ART in a resource-limited setting.

DESIGN/METHODS

A stochastic agent-based simulation model was built and directly informed by a cohort of 304 HIV-infected children starting ART in Thailand between 2001 and 2009. The model simulated the expected costs and clinical outcomes over time according to different viral load monitoring frequencies and initiation of second-line therapies when appropriate.

RESULTS

The optimal frequency of viral load monitoring was found to be annual, after a single screening at 6 months. Associated costs of viral load monitoring and appropriate ART would approximately triple current treatment costs. Compared with current conditions, a single screening during the first year of ART led to a 58.4% reduction in the total person-years of virological failure with annual monitoring leading to a 76.6% reduction. The incremental cost per quality adjusted life year gained from the optimal monitoring frequency was estimated as US$ 68,084 when including costs of ART and US$ 7224 without ART costs. The estimated cost attributed to preventing 1 year of virological failure was US$ 3393 with ART costs and US$ 359 without ART costs.

CONCLUSION

Even infrequent viral load monitoring is likely to provide substantial clinical benefit to HIV-infected children on ART. Viral load monitoring can be considered cost-effective in many resource-limited settings. However, the costs associated with second-line therapies could be a barrier to its economic feasibility.

Dried blood spots in HIV monitoring: applications in resource-limited settings

By the end of 2008, 4 million people were receiving antiretroviral treatment for HIV/AIDS in low- and middle-income countries. In industrialized countries, monitoring of treatment with viral load measurements and drug resistance testing is the standard of care to ensure early detection of treatment failure and a prompt switch to a fully active second-line regimen, before drug-resistant mutations accumulate. These tests, however, require highly specialized laboratories and stringent procedures for storage and shipment of plasma, and are rarely available in resource-limited settings. Therefore, treatment failure in such settings is usually not detected until patients develop severe immunodeficiency, at which stage widespread resistance is likely. Dried blood spots (DBS) are easy to collect and store, and can be a convenient alternative to plasma in settings with limited laboratory capacity. This review provides an overview of possible applications of DBS technologies in the monitoring of HIV treatment, with the main focus on viral load quantification and drug resistance testing.

Effect of Treatment Interruption and Intensification of Antiretroviral Therapy on Health-Related Quality of Life in Patients with Advanced HIV

Background. The effect of antiretroviral therapy (ART) interruption or intensification on health-related quality of life (HRQoL) in advanced HIV patients is unknown. Objective. To assess the impact of temporary treatment interruption and intensification of ART on HRQoL. Design. A 2 x 2 factorial open label randomized controlled trial. Setting. Hospitals in the United States, Canada, and the United Kingdom. Patients. Multidrug resistant (MDR) HIV patients. Intervention. Patients were randomized to receive a 12-wk interruption or not, and ART intensification or standard ART. Measurements. The Health Utilities Index (HUI3), EQ-5D, standard gamble (SG), time tradeoff (TTO), visual analog scale (VAS), and the Medical Outcomes Study HIV Health Survey (MOS-HIV). Results. There were no significant differences in HRQoL among the four groups during follow-up; however, there was a temporary significant decline in HRQoL on some measures within the interruption group during interruption (HUI3 −0.05, P = 0.03; VAS −5.9, P = 0.002; physical health summary −2.9, P = 0.001; mental health summary −1.9, P = 0.02). Scores declined slightly overall during follow-up. Multivariate analysis showed significantly lower HRQoL associated with some clinical events. Limitations. The results may not apply to HIV patients who have not experienced multiple treatment failures or who have not developed MDR HIV. Conclusions. Temporary ART interruption and ART intensification provided neither superior nor inferior HRQoL compared with no interruption and standard ART. Among surviving patients, HRQoL scores declined only slightly over years of follow-up in this advanced HIV cohort; however, approximately one-third of patients died during the trial follow up. Lower HRQoL was associated with adverse clinical events.

Drug resistance patterns and virus re-suppression among HIV-1 subtype C infected patients receiving non-nucleoside reverse transcriptase inhibitors in South Africa

BACKGROUND: Emergence of HIV-1 drug resistance is at times an inevitable and anticipated consequence of antiretroviral therapy (ART) failure. We examined drug resistance patterns and virus re-suppression among subtype C-infected South African patients receiving first-line ART. METHODS: Treatment records of 431 patients on NNRTI-containing regimens for a median of 45 months were analyzed. Patients with viral load (VL) >400 copies/mL were followed and drug resistance mutations (DRM) were re-assessed. Associations between clinical/demographic measures and drug resistance/virologic outcomes were examined using Fisher exact and ordinal and logistic regression. RESULTS: Ten percent of patients (43/431) were viremic at enrollment (98% previously suppressed); sequences were obtained from 38/43. Of those, 82% had 1-7 DRM. In bivariate analysis remote exposure to single-dose nevirapine or prior ART; higher CD4 counts; lower VL; and >6 months of virologic failure were significantly associated with number of DRM. Of 25 viremic patients followed for a median of 8 months on a continued first-line regimen, 12 (48%) re-suppressed, six with K103N and three with M184V. Thirteen (52%) had continued virologic failure which was significantly associated with detectable VL>6 months prior to enrollment and number of DRM. CONCLUSION: Among these HIV-1 subtype C-infected patients, DRM numbers and patterns were associated with prior exposure to sub-optimal ART, adherence and duration of virologic failure. Viral re-suppression in the presence of K103N and M184V challenges assumptions about drug resistance. In resource-limited settings, where genotyping and alternative drug options are unavailable, continuing first-line treatment, reinforcing adherence and regular virologic monitoring may be effective even after virologic failure.

Characterization of genotypic and phenotypic changes in HIV-1-infected patients with virologic failure on an etravirine-containing regimen in the DUET-1 and DUET-2 clinical studies

The randomized, placebo-controlled Phase III DUET studies enrolled treatment-experienced, HIV-1-infected patients. We examined the genotypic and phenotypic changes at endpoint relative to baseline, including the emergence of individual reverse transcriptase (RT) mutations, in patients who received the non-nucleoside reverse transcriptase inhibitor (NNRTI) etravirine and experienced virologic failure by rebound by the time of the Week 96 analysis. Patients received etravirine 200 mg twice-daily in combination with a background regimen containing darunavir/ritonavir, investigator-selected nucleoside reverse transcriptase inhibitors, and optional enfuvirtide. Virologic failure by rebound occurred in 93 (15.5%) etravirine-treated patients (compared with 170 [28.1%] placebo-treated patients). Patients experiencing virologic failure had more baseline antiretroviral resistance and lower activity of the background regimen relative to those not experiencing failure. Emergence of NNRTI resistance-associated mutations was observed in 55 of 93 patients. The most frequently emerging RT mutations were V179F, V179I, and Y181C, with positions K101 and E138 also showing frequent changes. Mutations usually emerged in a background of multiple other NNRTI mutations and were, in most cases, associated with a decrease in phenotypic sensitivity to etravirine at endpoint. Further analysis is needed to clarify the role of mutations at position 138 as determinants of etravirine resistance.

Measures of site resourcing predict virologic suppression, immunologic response and HIV disease progression following highly active antiretroviral therapy (HAART) in the TREAT Asia HIV Observational Database (TAHOD)

OBJECTIVES

Surrogate markers of HIV disease progression are HIV RNA in plasma viral load (VL) and CD4 cell count (immune function). Despite improved international access to antiretrovirals, surrogate marker diagnostics are not routinely available in resource-limited settings. Therefore, the objective was to assess effects of economic and diagnostic resourcing on patient treatment outcomes.

METHODS

Analyses were based on 2333 patients initiating highly active antiretroviral therapy (HAART) from 2000 onwards. Sites were categorized by World Bank country income criteria (high/low) and annual frequency of VL (> or = 3, 1-2 or <1) or CD4 (> or = 3 or <3) testing. Endpoints were time to AIDS/death and change in CD4 cell count and VL suppression (<400 HIV-1 RNA copies/mL) at 12 months. Demographics, Centers for Disease Control and Prevention (CDC) classification, baseline VL/CD4 cell counts, hepatitis B/C coinfections and HAART regimen were covariates. Time to AIDS/death was analysed by proportional hazards models. CD4 and VL endpoints were analysed using linear and logistic regression, respectively.

RESULTS

Increased disease progression was associated with site-reported VL testing less than once per year [hazard ratio (HR)=1.4; P=0.032], severely symptomatic HIV infection (HR=1.4; P=0.003) and hepatitis C virus coinfection (HR=1.8; P=0.011). A total of 1120 patients (48.2%) had change in CD4 cell count data. Smaller increases were associated with older age (P<0.001) and 'Other' HIV source exposures, including injecting drug use and blood products (P=0.043). A total of 785 patients (33.7%) contributed to the VL suppression analyses. Patients from sites with VL testing less than once per year [odds ratio (OR)=0.30; P<0.001] and reporting 'Other' HIV exposures experienced reduced suppression (OR=0.28; P<0.001).

CONCLUSION

Low measures of site resourcing were associated with less favourable patient outcomes, including a 35% increase in disease progression in patients from sites with VL testing less than once per year.

Incidence and predictors of death, retention, and switch to second-line regimens in antiretroviral- treated patients in sub-Saharan African Sites with comprehensive monitoring availability

BACKGROUND

Antiretroviral treatment programs in sub-Saharan Africa have high rates of early mortality and loss to follow-up. Switching to second-line regimens is often delayed because of limited access to laboratory monitoring.

METHODS

Retrospective analysis was performed of a cohort of adults who initiated a standard first-line antiretroviral treatment at 5 public sector sites in 3 African countries. Monitoring included routine CD4 cell counts, human immunodeficiency virus RNA measures, and records of whether appointments were kept. Incidence and predictors of death, loss to follow-up, and switch to second-line regimens were analyzed by time-to-event approaches.

RESULTS

A total of 3749 patients were analyzed; at baseline, 37.1% were classified as having World Health Organization disease stage 3 or 4, and the median CD4 cell count was 192 cells/mL. First-line regimens were nevirapine based in 96.5% of patients; 17.7% of patients attended <95% of their drug pickup appointments. During 4545 person-years of follow-up, mortality was 8.6 deaths per 100 person-years and was predicted by lower baseline CD4 cell count, lower hemoglobin level, and lower body mass index (calculated as weight in kilograms divided by the square of height in meters); more-advanced clinical stage of infection; male sex; and more missed drug pickup appointments. Dropouts (which accrued at a rate of 2.1 dropouts per 100 person-years) were predicted by a lower body mass index, more missed visits and missed drug pickup appointments, and later calendar year. Incidence of switches to second-line regimens was 4.9 per 100 person-years; increased hazards were observed with lower CD4 cell count and earlier calendar year at baseline. In patients who switched, virological failure was predicted by combined clinical and CD4 criteria with 74% sensitivity and 30% specificity.

CONCLUSIONS

In an antiretroviral treatment program employing comprehensive monitoring, the probability of switching to second-line therapy was limited. Regular pickup of medication was a predictor of survival and was also strongly predictive of patient retention.

Etravirine limits the emergence of darunavir and other protease inhibitor resistance-associated mutations in the DUET trials

Etravirine is a recently approved nonnucleoside reverse transcriptase inhibitor. The ability of etravirine to limit the emergence of resistance to protease inhibitors, and specifically to darunavir, was investigated in the subset of treatment-experienced patients with virologic rebound in the phase III DUET trials. Of those experiencing rebound, fewer etravirine-treated than placebo-treated patients developed mutations associated with resistance to protease inhibitors in general and to darunavir in particular, and more patients in the etravirine than the placebo-group maintained baseline darunavir susceptibility at endpoint.

An HIV-1 integrase genotype assay for the detection of drug resistance mutations

BACKGROUND

The integrase inhibitors (e.g. Raltegravir) are a new class of antiretroviral drugs that have recently become available for the treatment of patients with multi-drug resistant HIV-1 within Australia. The emergence of mutations that confer resistance to the integrase inhibitors has been observed in vivo; however, no commercial genotyping assay is currently available to screen for resistance to these drugs.

METHODS

The HIV-1 integrase gene was amplified from plasma-derived HIV-1 viral RNA via reverse transcription-polymerase chain reaction and genotype determined via population DNA sequencing. Drug resistance mutations and polymorphisms were detected using the Stanford University online HIV database. Assay sensitivity and reproducibility were determined using clinical and laboratory-derived samples.

RESULTS

Our in-house assay was capable of genotyping the integrase gene from all samples tested (n = 30) of HIV-1 subtypes B, C, D, F, CFR01_AE and CRF02_AG and can amplify the integrase region from plasma samples containing as few as 50 HIV RNA copies/mL. The assay is highly reproducible (average nucleotide concordance = 99.6%, n = 4) and is capable of detecting resistance-associated mutations.

CONCLUSIONS

This assay is suitable for routine drug resistance screening of plasma samples from HIV-infected patients receiving integrase inhibitor antiretroviral drugs and also serves as a useful research tool.

Cohort studies: to what extent can they inform treatment guidelines?

PURPOSE OF REVIEW

This review examines situations in which information from cohort studies has proved to be useful for the development of treatment guidelines.

RECENT FINDINGS

Although there are several reasons why randomized controlled trials (RCTs) are felt to provide the most robust evidence for treatment guidelines, they may suffer from insufficient duration of follow-up, inadequate power to consider differences in important adverse events and highly selected patient populations. Furthermore, as most RCTs are performed for licensing purposes, strategic treatment decisions often lack supportive evidence from RCTs. Although data from cohort studies may be used to complement information from RCTs, cohort studies themselves are susceptible to several biases (most notably confounding) which may limit their findings. However, in the HIV field, information from such studies has been influential in guiding decisions relating to when to start highly active antiretroviral therapy, what drugs to use in the initial highly active antiretroviral therapy regimen and when to switch highly active antiretroviral therapy should virological failure occur.

SUMMARY

Given the biases that may be present, caution should be exercised when interpreting findings from cohort studies, particularly if comparisons are made of treatment strategies that involve some element of patient or clinician choice.

Pediatric HIV clinical care resources and management practices in Asia: a regional survey of the TREAT Asia pediatric network

Characterizing intraregional differences in current pediatric HIV care and treatment in Asia can guide the development of clinical practice guidelines and improve the understanding of local resource availability. The Therapeutics Research, Education, and AIDS Training in Asia (TREAT Asia) Pediatric Program is a collaboration of clinics and referral hospitals studying pediatric HIV outcomes in the region. A Web-based survey to characterize clinical management practices and monitoring resources was developed and distributed to 20 sites in January 2008. Seventeen (85%) sites from 6 countries responded through April 2008; 14 (82%) were hospital-based and 16 (94%) were public facilities. Of 4050 HIV-infected children under care, 3606 (89%) were on antiretroviral treatment; 80% were on their first mono-, dual-, or triple-drug regimen and 74% were on nevirapine- or efavirenz-based regimens. Fifteen (88%) sites had consistent access to polymerase chain reaction (PCR) testing for infant diagnosis. All sites had access to CD4 testing, with 13 (76%) routinely monitoring patients every 3-6 months; 7 (41%) sites monitored viral load at 6- to 12-month intervals. Although there is some variation in clinical practices, high levels of treatment and monitoring resources were available at these sites. The availability of PCR for early infant diagnosis positions them to implement recent WHO recommendations to treat HIV-infected children younger than 1 year of age. This information will be used to develop future research and programs to support children with HIV in Asia.

Predictors of virologic failure in HIV-1-infected adults receiving first-line antiretroviral therapy in 8 provinces in China

BACKGROUND

Despite poor primary health care systems, free antiretroviral therapy (ART) has been available in China for >5 years. Virologic outcomes in Chinese patients receiving ART have not been described on a national level.

METHODS

A multistage cluster design was used in 8 provinces to randomly select patients who had been receiving first-line ART for at least 6 months, who were stratified into 3 treatment-duration groups. Viral load testing and patient interviews were conducted, and data were linked with national treatment database information. Collected data were analyzed for association with viral suppression by means of multivariate modeling. Adequate viral suppression was defined as a viral load of <400 copies/mL.

RESULTS

Of 5256 patients receiving ART, 3894 met the eligibility criteria, among whom 1153 were analyzed. Overall, 72% demonstrated viral suppression, and 82%, 73%, and 67% of the participants receiving ART for 6-11, 12-23, and > or = 24 months, respectively, experienced viral suppression (P < .001). In a multivariate model, treatment given at locations other than county-level hospitals was less likely to achieve viral suppression, with greater odds for inadequate virologic response found at village clinics (odds ratio [OR], 5.4; 95% confidence interval [CI], 2.9-10.1), township health centers (OR, 3.1; 95% CI, 1.7-5.6), and public health clinics (OR, 3.1; 95% CI, 1.7-5.6). Patients receiving didanosine-based regimens were more likely to experience an inadequate virologic response than were those receiving lamivudine-based regimens (OR, 3.9; 95% CI, 2.7-5.7).

CONCLUSIONS

China's national ART program is largely successful at suppressing viral load. Care received outside of hospitals and regimens containing didanosine were associated with less favorable virologic outcomes.

Clinical management of treatment-experienced, HIV/AIDS patients in the combination antiretroviral therapy era

Despite the success of combination antiretroviral therapy (ART) in improving clinical outcomes, treatment failure remains a significant challenge, particularly for highly treatment-experienced patients. This review evaluates current issues in the management of HIV-infected, treatment-experienced patients. It may provide guidance in selecting active, tolerable drug combinations that promote a reasonable quality of life, full adherence and a durable treatment response. Current treatment guidelines and clinical trial data were reviewed to identify reasons for treatment failure and to summarize therapy options for treatment-experienced and highly treatment-experienced patients. Current treatment options include nucleoside reverse transcriptase inhibitors (NRTIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs), protease inhibitors (PIs), and inhibitors of viral fusion, entry and integration. The use of NRTIs may be limited by resistance and short- and long-term toxicities. Resistance has restricted the NNRTI class with cross-resistance preventing their sequential use. Etravirine, a next-generation NNRTI, however, demonstrates effective virological suppression in patients with baseline NNRTI resistance. Boosted PIs are key components of ART for treatment-experienced patients. The newer boosted PIs tipranavir and darunavir have demonstrated impressive activity in patients with resistance to NRTIs, NNRTIs and PIs, as well as in less treatment-experienced patients for darunavir. The fusion inhibitor enfuvirtide has demonstrated efficacy in heavily treatment-experienced patients, although injection-site reactions can be problematical. The recently approved integrase inhibitor raltegravir has also shown impressive potency and tolerability in highly treatment-experienced patients. Finally, the entry inhibitor maraviroc has also been approved recently, although its use is somewhat limited by the need for HIV tropism testing. The availability of potent next-generation PIs, NNRTIs, integrase and entry-inhibitors may offer improved therapy for treatment-experienced patients, including those with multiresistant virus. These new drugs may reduce HIV immunological and clinical progression and in doing so may also reduce treatment costs.

Patient Characteristics and Treatment Outcome Associated with Protease Inhibitor (PI) use in the Asia-Pacific Region

OBJECTIVES: Regimens containing protease inhibitors (PI) are less commonly used in developing countries due to high cost and less availability. We evaluated characteristics of patients initiating PI-based therapy according to previous antiretroviral (ARV) exposure; factors associated with initiating a PI-containing regimen using newer versus older PIs, and proportion of patients with detectable viral loads (VL) after initiating a PI-based regimen. METHODS: This analysis includes all patients who have initiated a PI-based regimen. ARV exposure was categorised: naïve (no previous ARV), 1st, 2nd, >/= 3rd switches; a switch was defined as starting or stopping any drug in a regimen. Newer PIs were defined as those approved by the US FDA after 1 January 2000. Detectable VL at 12 months was defined as VL >/= 400 copies/mL. Characteristics at PI initiation were evaluated. Logistic regression was used to determine factors associated with initiating a newer PI and detectable VL at 12 months after PI initiation. RESULTS: 1106 patients initiated PI-based therapy; of these, 618 (56%) were naïve patients. Overall, 22% (176) of patients had detectable VL at 12 months following the PI initiation. Being from a high income country (vs. mid/low income, OR = 1.80, p = 0.034) were more likely to be associated with detectable VL. CONCLUSION: The use of PIs in this cohort is dictated by accessibility and affordability issues particularly for the newer PIs. Short-term virological outcomes following PI-therapy in our cohort were good, and were associated with CD4 count at time of initiation.

Effective treatment of patients in a deep salvage situation with "non-active HAART": experiences with the expert advice system RADATA

BACKGROUND

Clinical studies suggest expert recommendations as a possibility to optimize highly active antiretroviral therapy (HAART) in patients with multi-drug resistant virus strains. An online system (RADATA) has been developed to provide expert advice for the drug therapy of HIV-infected patients.

OBJECTIVE

To evaluate the efficacy of expert-advice-guided HAART switches in patients with triple-class failure.

METHODS

Virological and immunological outcome of patients having undergone at least three prior ART regimens, including nucleoside inhibitor (NRTI), nonnucleoside reverse transcriptase inhibitor (NNRTI), and protease inhibitor (PI) use, were analyzed. Changes in HIV-RNA and CD4-cell count were evaluated every 3 months.

RESULTS

183 patients with a median baseline viral load of 3.90 log copies/ml (1.88-6.54 log) and a CD4-cell count of 298 c/ll (5-910 c/ll) were eligible for analysis. The patients had a median of seven prior ART regimens and a treatment duration of 83 months. A median of three (range 0-8) NRTI-, two (0-7) thymidine-associated (TA), one (0-4) NNRTI-, and three (0-13) PI-associated resistance mutations were present at baseline. Despite available resistance analyses and expert recommendations, 66% (n = 119) of the patients started a new ART regimen without any active drugs according to the resistance analysis. The HIV-RNA declined by a median of 0.61 log and 0.92 log after 12 and 24 months, respectively, while the CD4-cell count rose by a median of +9 c/microl and +25 c/microl during this period. No significant differences related to number of prior regimens or number of active substances used could be found.

CONCLUSION

Despite extensive pre-treatment and multiple resistances against prescribed HAART, our patients demonstrated a decline in viral load and a stable CD4-cell count over the observation period. We conclude that the activity of antiretroviral regimens is not exclusively explained by the current algorithms used for estimating antiretroviral drug activity.

Clinical management of HIV-1 resistance

Antiretroviral drug resistance is a fundamental survival strategy for the virus that stems from its vast capacity to generate diversity. With the recent availability of new ARV drugs and classes, it is now possible to prescribe fully active ART to most HIV-infected subjects and achieve viral suppression even in those with multidrug-resistant HIV. It is uncertain, however, if this scenario will endure. Given that ART must be given for life, and new compounds other than second-generation integrase inhibitors may not reach the clinic soon, all efforts must be done to avoid the development of resistance to the new agents. Here, we discuss relevant aspects for the clinical management of antiretroviral drug resistance, leaving detailed explanations of mechanisms and mutation patterns to other articles in this issue. This article forms part of a special issue of Antiviral Research marking the 25th anniversary of antiretroviral drug discovery and development, vol. 85, issue 1, 2010.

An algorithm to optimize viral load testing in HIV-positive patients with suspected first-line antiretroviral therapy failure in Cambodia

OBJECTIVE

To develop an algorithm for optimal use of viral load testing in patients with suspected first-line antiretroviral treatment (ART) failure.

METHODS

Data from a cohort of patients on first-line ART in Cambodia were analyzed in a cross-sectional way to detect markers for treatment failure. Markers with an adjusted likelihood ratio <0.67 or >1.5 were retained to calculate a predictor score. The accuracy of a 2-step algorithm based on this score followed by targeted viral load testing was compared with World Health Organization criteria for suspected treatment failure.

RESULTS

One thousand eight hundred three viral load measurements of 764 patients were available for analysis. Prior ART exposure, CD4 count below baseline, 25% and 50% drop from peak CD4 count, hemoglobin drop of > or =1 g/dL, CD4 count <100 cells per microliter after 12 months of treatment, new onset of papular pruritic eruption, and visual analog scale <95% were included in the predictor score. A score >or=2 had the best combination of sensitivity and specificity and required confirmatory viral load testing for only 9% of patients. World Health Organization criteria had a similar sensitivity but a lower specificity and required viral load testing for 24.9% of patients.

CONCLUSION

An algorithm combining a predictor score with targeted viral load testing in patients with an intermediate probability of failure optimizes the use of scarce resources.

Virological efficacy and emergence of drug resistance in adults on antiretroviral treatment in rural Tanzania

BACKGROUND

Virological response to antiretroviral treatment (ART) in rural Africa is poorly described. We examined virological efficacy and emergence of drug resistance in adults receiving first-line ART for up to 4 years in rural Tanzania.

METHODS

Haydom Lutheran Hospital has provided ART to HIV-infected patients since October 2003. A combination of stavudine or zidovudine with lamivudine and either nevirapine or efavirenz is the standard first-line regimen. Nested in a longitudinal cohort study of patients consecutively starting ART, we carried out a cross-sectional virological efficacy survey between November 2007 and June 2008. HIV viral load was measured in all adults who had completed at least 6 months first-line ART, and genotypic resistance was determined in patients with viral load >1000 copies/mL.

RESULTS

Virological response was measured in 212 patients, of whom 158 (74.5%) were women, and median age was 35 years (interquartile range [IQR] 29-43). Median follow-up time was 22.3 months (IQR 14.0-29.9). Virological suppression, defined as <400 copies/mL, was observed in 187 patients (88.2%). Overall, prevalence of > or =1 clinically significant resistance mutation was 3.9, 8.4, 16.7 and 12.5% in patients receiving ART for 1, 2, 3 and 4 years, respectively. Among those successfully genotyped, the most frequent mutations were M184I/V (64%), conferring resistance to lamivudine, and K103N (27%), Y181C (27%) and G190A (27%), conferring resistance to non-nucleoside reverse transcriptase inhibitors (NNRTIs), whereas 23% had thymidine analogue mutations (TAMs), associated with cross-resistance to all nucleoside reverse transcriptase inhibitors (NRTIs). Dual-class resistance, i.e. resistance to both NRTIs and NNRTIs, was found in 64%.

CONCLUSION

Virological suppression rates were good up to 4 years after initiating ART in a rural Tanzanian hospital. However, drug resistance increased with time, and dual-class resistance was common, raising concerns about exhaustion of future antiretroviral drug options. This study might provide a useful forecast of drug resistance and demand for second-line antiretroviral drugs in rural Africa in the coming years.

Increased mutations in Env and Pol suggest greater HIV-1 replication in sputum-derived viruses compared with blood-derived viruses

OBJECTIVE

Low-level HIV-1 replication may occur during antiretroviral therapy (ART) that suppresses plasma HIV-1 RNA to less than 50 copies/ml (suppressive ART). Antiretroviral drugs appear less effective in macrophages and monocytes compared with lymphocytes, both in vitro and as implied in vivo by greater viral evolution observed during suppressive ART. Our objective was to examine sputum, which is rich in macrophages, for evidence of increased HIV-1 replication compared with that in the blood during suppressive ART.

DESIGN

A cross-sectional study during suppressive ART was performed, and HIV-1 DNA sequences derived from induced sputa and peripheral blood mononuclear cells were compared.

METHODS

Multiple sequences encoding HIV-1 reverse transcriptase, protease, and envelope were generated using single-genome sequencing. Reverse transcriptase and protease sequences were analyzed for genotypic drug resistance. The evolutionary distances of env sequences from the inferred most recent common ancestor of infection were calculated, and CXCR4 usage was predicted.

RESULTS

Nine hundred seventy bidirectional sequences from 11 individuals were analyzed. HIV-1 env and pol derived from sputa had greater frequency of drug-resistance mutations (P = 0.05), evolutionary divergence (P = 0.004), and tendency for CXCR4 usage (P = 0.1) compared with viruses derived from peripheral blood mononuclear cells.

CONCLUSION

The greater frequency of HIV-1 drug-resistance mutations and divergence of HIV-1 env in sputa-derived viruses compared with peripheral blood mononuclear cell-derived viruses suggests greater HIV-1 replication in the respiratory tract compared with the blood. Characterization of viral evolution over time and by cell-type could identify cells that provide a sanctuary for low-level viral replication in the respiratory tract during suppressive ART.