Safety of stavudine in the treatment of HIV infection with a special focus on resource-limited settings

Meta-Analysis on Nicotine's Modulation of HIV-Associated Dementia

HIV-Associated Dementia (HAD) is a significant comorbidity that many HIV-patients face. Our study utilized QIAGEN Ingenuity Pathway Analysis (IPA) to identify and analyze molecular profiles and pathways underlying nicotine's impact on HAD pathology. The Qiagen Knowledge Base (QKB) defines HAD as "Dementia associated with acquired immunodeficiency syndrome (disorder)." Although much remains unknown about HAD pathology, the curated research findings from the QKB shows 5 upregulated molecules that are associated with HAD + : CCL2 (Chemokine (C-C motif) ligand 2), L-glutamic acid, GLS (Glutaminase), POLG (DNA polymerase subunit gamma), and POLB (DNA polymerase subunit beta). The current study focused on these 5 HAD pathology molecules as the phenotype of interest. The Pathway Explorer tool of IPA was used to connect nicotine-associated molecules with the 5 HAD associated molecules (HAD pathology molecules) by connecting 29 overlapping molecules (including transcription regulators, cytokines, kinases, and other enzymes/proteins). The Molecule-Activity-Predictor (MAP) tool predicted nicotine-induced activation of the HAD pathology molecules indicating the exacerbation of HAD. However, alternative pathways with more holistic representations of molecular relationships revealed the potential of nicotine as a neuroprotective treatment. It was found that concurrent with nicotine treatment the individual inactivation of several of the intermediary molecules in the holistic pathways caused the downregulation of the HAD pathology molecules. These findings reveal that nicotine may have therapeutic properties for HAD when given alongside specific inhibitory drugs for one or more of the identified intermediary molecules.

Durability of antiretroviral therapy regimens and determinants for change in HIV-1-infected patients in the TREAT Asia HIV Observational Database (TAHOD-LITE)

BACKGROUND

The durability of first-line regimen is important to achieve long-term treatment success for the management of HIV infection. Our analysis describes the duration of sequential ART regimens and identifies the determinants leading to treatment change in HIV-positive patients initiating in Asia.

METHODS

All HIV-positive adult patients initiating first-line ART in 2003-2013, from eight clinical sites among seven countries in Asia. Patient follow-up was to May 2014. Kaplan-Meier curves were used to estimate the time to second-line ART and third-line ART regimen. Factors associated with treatment durability were assessed using Cox proportional hazards model.

RESULTS

A total of 16,962 patients initiated first-line ART. Of these, 4,336 patients initiated second-line ART over 38,798 person-years (pys), a crude rate of 11.2 (95% CI 10.8, 11.5) per 100 pys. The probability of being on first-line ART increased from 83.7% (95% CI 82.1, 85.1%) in 2003-2005 to 87.9% (95% CI 87.1, 88.6%) in 2010-2013. Third-line ART was initiated by 1,135 patients over 8,078 pys, a crude rate of 14.0 (95% CI 13.3, 14.9) per 100 pys. The probability of continuing second-line ART significantly increased from 64.9% (95% CI 58.5, 70.6%) in 2003-2005 to 86.2% (95% CI 84.7, 87.6%) in 2010-2013.

CONCLUSIONS

Rates of discontinuation of first- and second-line regimens have decreased over the last decade in Asia. Subsequent regimens were of shorter duration compared to the first-line regimen initiated in the same year period. Lower CD4⁺ T-cell count and the use of suboptimal regimens were important factors associated with higher risk of treatment switch.

HIV, antiretroviral therapy and non-communicable diseases in sub-Saharan Africa: empirical evidence from 44 countries over the period 2000 to 2016

INTRODUCTION

The HIV-infected population is growing due to the increased accessibility of antiretroviral therapy (ART) that extends the lifespan of people living with HIV (PLHIV). We aimed to assess whether national HIV prevalence and ART use are associated with an increased prevalence of cardiovascular risk factors.

METHODS

Using country-level data, we analysed the effect of HIV prevalence and use of ART on cardiovascular risk factors in 44 countries in sub-Saharan Africa between 2000 and 2016. We used fixed-effects estimation to quantify the effect of HIV and ART on the prevalence of diabetes, mean body mass index, the prevalence of overweight, obesity and hypertension, and mean systolic blood pressure. The models were adjusted for calendar time, the age structure of the population, income and education.

RESULTS

Diabetes prevalence among PLHIV was 5.8 percentage points higher (95% confidence interval (CI) 1.8 pp to 9.8 pp) compared to individuals without HIV. People receiving ART had a 4.6 percentage point higher prevalence (95% CI 2.6 pp to 6.6 pp). The prevalence of obesity was increased by 14.7 percentage points (95% CI 2.5 pp to 26.9 pp) for PLHIV. Receiving ART was associated with an increased obesity prevalence by 14.0 percentage points (95% CI 4.8 pp to 23.2 pp), whereas it had no significant association with the prevalence of overweight. The population aged 40 to 59 had a significantly higher prevalence of diabetes, overweight and obesity. HIV prevalence and ART use had no significant association with the prevalence of hypertension.

CONCLUSIONS

An ageing HIV-infected population on ART is associated with a significant increase in the prevalence of diabetes and obesity in sub-Saharan Africa. The increasing prevalence of these cardiovascular risk factors emphasizes the need for comprehensive healthcare programmes that screen and treat both HIV and non-communicable diseases to decrease the associated morbidity and mortality rates.

Community Based Antiretroviral Treatment in Rural Zimbabwe

Treatment of HIV has reduced HIV/AIDS-related mortality. Sustaining >90% virologic suppression in sub-Saharan Africa requires decentralized care and prevention services to rural communities. In Zimbabwe, the number of people receiving antiretroviral treatment (ART) has increased rapidly. However, access to treatment monitoring tools such as viral load and drug resistance testing is limited. We assessed virologic treatment outcomes among ART recipients in Nyamutora, a rural community receiving bimonthly ART and prevention services. We enrolled all ART recipients (143) at 6-monthly visits in the Nyamutora community in 2014 and 2015. Whole blood samples were collected in K-EDTA tubes, transported to Harare for CD4 counts and viral load testing, and genotype was obtained in participants with viral loads >1,000 copies/ml. Ages ranged from 2 to 75 years (median 43 years) with a median 42 months on ART at follow-up. Eight of 143 (6%) had viral loads >1,000 copies/ml at one of the 3 visits, 7 on first-line nevirapine (NVP)-based ART and 1 on second-line LPV/r-based ART. Seven participants had sequence data available, and five had drug resistance mutations, K65R, T69N, K101E, K103N, Y181C/I, M184V, and G190A. Virologic failure (p = .001) and drug resistance mutations (p = .01) on first-line NVP-based ART were associated with younger age by univariate exact logistic regression. The participants had high viral suppression (94%) despite less than optimal (NVP based) ART regimens without laboratory monitoring. Virologic failure and drug resistance were higher among children and adolescents. Effective ART delivery to the community achieved high rates of virologic suppression and minimal drug resistance.

Improved survival in HIV treatment programmes in Asia

BACKGROUND

Antiretroviral treatment (ART) for HIV-positive patients has expanded rapidly in Asia over the last 10 years. Our study aimed to describe the time trends and risk factors for overall survival in patients receiving first-line ART in Asia.

METHODS

We included HIV-positive adult patients who initiated ART between 2003-2013 (n=16,546), from seven sites across six Asia-Pacific countries. Patient follow-up was to May 2014. We compared survival for each country and overall by time period of ART initiation using Kaplan-Meier curves. Factors associated with mortality were assessed using Cox regression, stratified by site. We also summarized first-line ART regimens, CD4⁺ T-cell count at ART initiation, and CD4⁺ T-cell and HIV viral load testing frequencies.

RESULTS

There were 880 deaths observed over 54,532 person-years of follow-up, a crude rate of 1.61 (95% CI 1.51, 1.72) per 100 person-years. Survival significantly improved in more recent years of ART initiation. The survival probability at 4 years follow-up for those initiating ART in 2003-2005 was 92.1%, 2006-2009 was 94.3% and 2010-2013 was 94.5% (P<0.001). Factors associated with higher mortality risk included initiating ART in earlier time periods, older age, male sex, injecting drug use as HIV exposure and lower pre-ART CD4⁺ T-cell count. Concurrent with improved survival was increased tenofovir use, ART initiation at higher CD4⁺ T-cell counts and greater monitoring of CD4⁺ T-cells and HIV viral load.

CONCLUSIONS

Our results suggest that HIV-positive patients from Asia have improved survival in more recent years of ART initiation. This is likely a consequence of improvements in treatment, patient management and monitoring over time.

Uptake of WHO recommendations for first-line antiretroviral therapy in Kenya, Uganda, and Zambia

Introduction

Antiretroviral therapy (ART) guidelines were significantly changed by the World Health Organization in 2010. It is largely unknown to what extent these guidelines were adopted into clinical practice.

Methods

This was a retrospective observational analysis of first-line ART regimens in a sample of health facilities providing ART in Kenya, Uganda, and Zambia between 2007-2008 and 2011-2012. Data were analyzed for changes in regimen over time and assessed for key patient- and facility-level determinants of tenofovir (TDF) utilization in Kenya and Uganda using a mixed effects model.

Results

Data were obtained from 29,507 patients from 146 facilities. The overall percentage of patients initiated on TDF-based therapy increased between 2007-2008 and 2011-2012 from 3% to 37% in Kenya, 2% to 34% in Uganda, and 64% to 87% in Zambia. A simultaneous decrease in stavudine (d4T) utilization was also noted, but its use was not eliminated, and there remained significant variation in facility prescribing patterns. For patients initiating ART in 2011-2012, we found increased odds of TDF use with more advanced disease at initiation in both Kenya (odds ratio [OR]: 2.78; 95% confidence interval [CI]: 1.73-4.48) and Uganda (OR: 2.15; 95% CI: 1.46-3.17). Having a CD4 test performed at initiation was also a significant predictor in Uganda (OR: 1.43; 95% CI: 1.16-1.76). No facility-level determinants of TDF utilization were seen in Kenya, but private facilities (OR: 2.86; 95% CI: 1.45-5.66) and those employing a doctor (OR: 2.86; 95% CI: 1.48-5.51) were more likely to initiate patients on TDF in Uganda.

Discussion

d4T-based ART has largely been phased out over the study period. However, significant in-country and cross-country variation exists. Among the most recently initiated patients, those with more advanced disease at initiation were most likely to start TDF-based treatment. No facility-level determinants were consistent across countries to explain the observed facility-level variation.

Perceptions of lipodystrophy among PLHIV after 10 years of antiretroviral therapy in Senegal

Nearly one-third of people living with HIV (PLHIV) and taking HAART develop lipodystrophy in Africa. This article aims to describe how they perceive these disorders and the determinants of these perceptions. It is based on a qualitative study using interviews conducted with 20 patients with clinical lipodystrophy in Dakar, Senegal. Not all of the interviewees complained, though some had clearly visible lipodystrophy. The hypertrophic form seems better tolerated when perceived as overweight, a sign of excess wealth. Atrophic forms sometimes go unnoticed in lean people, but others experience it as stigma, avoid appearing in public, and express significant suffering, especially when symptoms jeopardize their social status. Healthcare systems should take better account of lipodystrophy and its psychosocial effects because they weaken adherence and reduce patients' quality of life.

Pharmacometrics: opportunity for reducing disease burden in the developing world: the case of Africa

Pharmacometricians are virtually nonexistent in Africa and the developing world. The unrelenting burden of infectious diseases, which are often treated using medicines with narrow effectiveness and safety dose ranges, and the growing prevalence and recognition of non-communicable diseases represent significant threats for the patients, although affording an opportunity for advancing science. This article outlines the case for pharmacometricians to redirect their expertise to focus on the disease burden affecting the developing world.

Antiretroviral Therapy (ART) Side Effect Impacted on Quality of Life, and Depressive Symptomatology: A Mixed-Method Study

Antiretroviral therapy (ART) is known for its side effects. In this paper, we describe ART side effects as experienced by Chinese HIV+ individuals. This study presents two stages of a research project, combining qualitative in-depth interviews (29 HIV+ participants) with quantitative statistical data analysis (N = 120). All data was collected between July 2005 to March 2008 at Beijing's Ditan Hospital. Consent was obtained from each participant for the qualitative interview and again for the quantitative survey. During in-depth interviews, Chinese HIV+ patients reported experiencing digestive discomfort, skin rashes, numbness, memory loss, nightmares, and dizziness, which not only brought them physical discomfort, but also interrupted different dimensions of their social lives. Furthermore, multiple regression analyses revealed that those who reported more severe side effects also experienced greater depressive mood after controlling for other clinical and psychosocial factors. ART side effects are one of the primary reasons causing HIV+ individuals to delay or stop taking life-saving medication; therefore, clinical interventions are critically needed to assist HIV+ individuals in managing ART side effects. ART side effects reinforced existing negative attitudes toward ART and lead to lower ART adherence. Future research should focus on developing culturally sensitive interventions to enhance HIV+ self-management, to alleviate physical and psychological burden from ART and HIV.

A 72-week randomized study of the safety and efficacy of a stavudine to zidovudine switch at 24 weeks compared to zidovudine or tenofovir disoproxil fumarate when given with lamivudine and nevirapine

BACKGROUND

Due to superior long-term toxicity profiles, zidovudine (AZT) and tenofovir disoproxil fumarate (TDF) are preferred over stavudine (d4T) for first-line antiretroviral regimens. However, short-term d4T use could be beneficial in avoiding AZT-induced anaemia.

METHODS

We randomized (1:1:1) 150 treatment-naive Thai HIV-infected adults with CD4(+) T-cell count <350 cells/mm(3) to arm 1 (24-week GPO-VIR S30(®) [d4T plus lamivudine (3TC) plus nevirapine (NVP)] followed by 48-week GPO-VIR Z250(®) [AZT plus 3TC plus NVP]), arm 2 (72-week GPO-VIR Z250(®)) or arm 3 (72-week TDF plus emtricitabine [FTC] plus NVP). Haemoglobin (Hb), dual energy x-ray absorptiometry, neuropathic signs, estimated glomerular filtration rate (eGFR), CD4(+) T-cell count, plasma HIV RNA and adherence were assessed.

RESULTS

In an intention-to-treat analysis, mean Hb decreased from baseline to week 24 in arm 2 compared with arm 1 (-0.19 versus 0.68 g/dl; P=0.001) and arm 3 (0.48 g/dl; P=0.010). Neuropathic signs were more common in arm 2 compared with arm 3 (20.4 versus 4.2%; P=0.028) at week 24. There were no differences in changes in peripheral fat and eGFR from baseline to weeks 24 and 72 among arms. CD4(+) T-cell count increased more in arm 1 than arms 2 and 3 from baseline to week 24 (168 versus 117 and 118 cells/mm(3); P=0.01 and 0.02, respectively) but the increase from baseline to week 72 was similar among arms.

CONCLUSIONS

A 24-week d4T lead-in therapy caused less anaemia and greater initial CD4(+) T-cell count increase than initiating treatment with AZT. This strategy could be considered in patients with baseline anaemia or low CD4(+) T-cell count. If confirmed in a larger study, this may guide global recommendations on antiretroviral initiation where AZT is more commonly used than TDF.

Adult mortality and probable cause of death in rural northern Malawi in the era of HIV treatment

Objectives

Developing countries are undergoing demographic transition with a shift from high mortality caused by communicable diseases (CD) to lower mortality rates caused by non-communicable diseases (NCD). HIV/AIDS has disrupted this trend in sub-Saharan Africa. However, in recent years, HIV-associated mortality has been reduced with the introduction of widely available antiretroviral therapy (ART). Side effects of ART may lead to increased risk of cardiovascular diseases, raising the prospects of an accelerated transition towards NCD as the primary cause of death. We report population-based data to investigate changes in cause of death owing to NCD during the first 4 years after introduction of HIV treatment.

Methods

We analysed data from a demographic surveillance system in Karonga district, Malawi, from September 2004 to August 2009. ART was introduced in mid-2005. Clinician review of verbal autopsies conducted 2–6 weeks after a death was used to establish a single principal cause of death.

Results

Over the entire period, there were 905 deaths, AIDS death rate fell from 505 to 160/100 000 person-years, and there was no evidence of an increase in NCD rates. The proportion of total deaths attributable to AIDS fell from 42% to 17% and from NCD increased from 37% to 49%.

Discussion

Our findings show that 4 years after the introduction of ART into HIV care in Karonga district, all-cause mortality has fallen dramatically, with no evidence of an increase in deaths owing to NCD.

Combination nucleoside/nucleotide reverse transcriptase inhibitors for treatment of HIV infection

INTRODUCTION

The combination of two nucleoside/nucleotide reverse transcriptase inhibitors (N(t)RTIs) and a third agent from another antiretroviral class is currently recommended for initial antiretroviral therapy. In general, N(t)RTIs remain relevant in subsequent regimens. There are currently six nucleoside reverse transcriptase inhibitors and one nucleotide reverse transcriptase inhibitor drug entities available, and several formulations that include two or more N(t)RTIs in a fixed-dose combination. These entities have heterogeneous pharmacological and clinical properties. Accordingly, toxicity, pill burden, dosing frequency, potential drug-drug interaction, preexisting antiretroviral drug resistance and comorbid conditions should be considered when constructing a regimen. This approach is critical in order to optimize virologic efficacy and clinical outcomes.

AREAS COVERED

This article reviews N(t)RTI combinations used in the treatment of HIV-infected adults. The pharmacological properties of each N(t)RTI, and the clinical trials that have influenced treatment guidelines are discussed.

EXPERT OPINION

It is likely that N(t)RTIs will continue to dominate the global landscape of HIV treatment and prevention, despite emerging interest in N(t)RTI-free combination therapy. Clinical domains where only few alternatives to N(t)RTIs exist include treatment of HIV/HBV coinfection and HIV-2. There is a need for novel N(t)RTIs with enhanced safety and resistance profiles compared with current N(t)RTIs.

HIV neuropathy risk factors and symptom characterization in stavudine-exposed South Africans

CONTEXT

HIV-associated sensory neuropathy (HIV-SN) is a frequent complication of both HIV and neurotoxic antiretroviral medications such as stavudine.

OBJECTIVES

To determine the prevalence, risk factors, and clinical characteristics of symptomatic HIV-SN in a Black South African cohort of patients exposed to stavudine.

METHODS

HIV-positive Black South Africans (n=395) who had received stavudine for at least six months were recruited at the Virology Clinic of the Charlotte Maxeke Academic Johannesburg Hospital, South Africa, and screened for neuropathy using the AIDS Clinical Trials Group neuropathy screening tool. HIV-SN was defined as present if the patient had both symptoms and signs of peripheral neuropathy. If present, the distribution and intensity of symptoms were recorded. In addition, anthropomorphic, demographic, and clinical information were recorded and analyzed as risk factors.

RESULTS

The prevalence of symptomatic HIV-SN was 57% (226 of 395). Increasing age and height were independently associated with the development of SN among patients who had used stavudine. Pain was the primary symptom reported by participants with HIV-SN (76%, 172 of 226), followed by numbness (48%, 108 of 226), and pins and needles (46%, 105 of 226). About three-quarters of participants rated their symptoms as being of moderate to severe intensity. Symptoms were always present in the feet and only 23% experienced symptoms proximal to the feet.

CONCLUSION

HIV-SN was common in this population and frequently associated with moderate to severe pain in the feet. HIV-SN was significantly associated with increasing age and height, factors that could be measured at no added cost prior to stavudine prescription, allowing higher risk patients to be offered priority access to nonneurotoxic drugs.

The genetic toxicity effects of lamivudine and stavudine antiretroviral agents

IMPORTANCE OF THE FIELD

The nucleoside reverse transcriptase inhibitors (NRTIs) are used in antiretroviral therapy worldwide for the treatment of HIV infections. These drugs act by blocking reverse transcriptase enzyme activity, causing pro-viral DNA chain termination. As a consequence, NRTIs could cause genomic instability and loss of heterozygosity.

AREAS COVERED IN THIS REVIEW

This review highlights the toxic and genotoxic effects of NRTIs, particularly lamivudine (3TC) and stavudine (d4T) analogues. In addition, a battery of short-term in vitro and in vivo systems are described to explain the potential genotoxic effects of these NRTIs as a single drug or a complexity of highly active antiretroviral therapy.

WHAT THE READER WILL GAIN

The readers will gain an understanding of a secondary effect that could be induced by 3TC and d4T treatments.

TAKE HOME MESSAGE

Considering that AIDS has become a chronic disease, more comprehensive toxic genetic studies are needed, with particular attention to the genetic alterations induced by NRTIs. These alterations play a primary role in carcinogenesis and are also involved in secondary and subsequent steps of carcinogenesis.

A randomized factorial trial comparing 4 treatment regimens in treatment-naive HIV-infected persons with AIDS and/or a CD4 cell count <200 cells/μL in South Africa

BACKGROUND

Few randomized trials comparing antiretroviral therapy (ART) regimens have been conducted in resource-limited settings.

METHODS

In the Republic of South Africa, antiretroviral-naive human immunodeficiency virus (HIV)-infected individuals >14 years old with a CD4 cell count <200 cells/μL or a prior AIDS diagnosis were randomized to receive efavirenz (EFV) or lopinavir/ritonavir (LPV/r) with either zidovudine (ZDV) plus didanosine (ddI) or stavudine (d4T) plus lamivudine (3TC) in an open-label, 2-by-2 factorial study and followed up for the primary outcome of AIDS or death and prespecified secondary outcomes, including CD4 cell count and viral load changes, treatment discontinuation, and grade 4 events.

RESULTS

In total, 1771 persons were randomized and followed up for a median of 24.7 months. AIDS or death occurred in (1) 163 participants assigned EFV and 157 assigned LPV/r (hazard ratio [HR], 1.04 [95% confidence interval {CI}, 0.84-1.30]) and in (2) 170 participants assigned ZDV+ddI and 150 assigned d4T+3TC (HR, 1.15 [95% CI, 0.93-1.44]). HIV RNA levels were lower (P < .001) and CD4 cell counts were greater (P < .01) over follow-up for d4T+3TC versus ZDV+ddI. Rates of potentially life-threatening adverse events and overall treatment discontinuation were similar for d4T+3TC and ZDV+ddI; however, more participants discontinued d4T because of toxicity (12.6%) than other treatments (<5%).

CONCLUSION

EFV and LPV/r are effective components of first-line ART. The poorer viral and immune responses with ZDV+ddI and the greater toxicity-associated discontinuation rate with d4T+3TC suggest that these treatments be used cautiously as initial therapy.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00342355.

Stavudine- and nevirapine-related drug toxicity while on generic fixed-dose antiretroviral treatment: incidence, timing and risk factors in a three-year cohort in Kigali, Rwanda

This cohort study was conducted to report on the incidence, timing and risk factors for stavudine (d4T)- and nevirapine (NVP)-related severe drug toxicity (requiring substitution) with a generic fixed-dose combination under program conditions in Kigali, Rwanda. Probability of 'time to first toxicity-related drug substitution' was estimated using the Kaplan-Meier method and Cox-proportional hazards modeling was used to identify risk factors. Out of 2190 adults (median follow-up: 1.5 years), d4T was replaced in 175 patients (8.0%) for neuropathy, 69 (3.1%) for lactic acidosis and 157 (7.2%) for lipoatrophy, which was the most frequent toxicity by 3 years of antiretroviral treatment (ART). NVP was substituted in 4.9 and 1.3% of patients for skin rash and hepatotoxicity, respectively. Use of d4T 40 mg was associated with increased risk of lipoatrophy and early (<6 months) neuropathy. Significant risk factors associated with lactic acidosis and late neuropathy included higher baseline body weight. Older age and advanced HIV disease increased the risk of neuropathy. Elevated baseline liver tests and older age were identified as risk factors for NVP-related hepatotoxicity. d4T is associated with significant long-term toxicity. d4T-dose reduction, increased access to safer ART in low-income countries and close monitoring for those at risk are all relevant strategies.

Pharmacogenetics of nucleoside reverse-transcriptase inhibitor-associated peripheral neuropathy

Peripheral neuropathy is an important complication of antiretroviral therapy. Nucleoside reverse-transcriptase inhibitor (NRTI)-associated mitochondrial dysfunction, inflammation and nutritional factors are implicated in its pathogenesis. Pharmacogenetic and genomic studies investigating NRTI neurotoxicity have only recently become possible via the linkage of HIV clinical studies to large DNA repositories. Preliminary case-control studies using these resources suggest that host mitochondrial DNA haplogroup polymorphisms in the hemochromatosis gene and proinflammatory cytokine genes may influence the risk of peripheral neuropathy during antiretroviral therapy. These putative risk factors await confirmation in other HIV-infected populations but they have strong biological plausibility. Work to identify underlying mechanisms for these associations is ongoing. Large-scale studies incorporating clearly defined and validated methods of neuropathy assessment and the use of novel laboratory models of NRTI-associated neuropathy to clarify its pathophysiology are now needed. Such investigations may facilitate the development of more effective strategies to predict, prevent and ameliorate this debilitating treatment toxicity in diverse clinical settings.