Renal safety of tenofovir in HIV-infected children: a prospective, 96-week longitudinal study

Health-Related Physical Fitness Evaluation in HIV-Diagnosed Children and Adolescents: A Scoping Review

BACKGROUND

Health-related physical fitness has been widely used to investigate the adverse effects of HIV infection/ART in children and adolescents. However, methods/protocols and cut-points applied for investigating health-related physical fitness are not clear. The aim of this scoping review was to map the literature to identify gaps in knowledge regarding the methods/protocols and cut-points.

METHODS

A scoping review, following the Joana Briggs Institute (JBI) guidelines, was conducted through ten major databases. Search followed the PCC strategy to construct block of terms related to population (children and adolescents), concept (health-related physical fitness components) and context (HIV infection).

RESULTS

The search resulted in 7545 studies. After duplicate removal, titles and abstracts reading and full text assessment, 246 studies were included in the scoping review. Body composition was the most investigated component (n = 244), followed by muscular strength/endurance (n = 23), cardiorespiratory fitness (n = 15) and flexibility (n = 4). The World Health Organization growth curves, and nationals' surveys were the most reference values applied to classify body composition (n = 149), followed by internal cut-points (n = 30) and cut-points developed through small populations (n = 16). Cardiorespiratory fitness was classified through cut-points from three different assessment batteries, as well as cut-points developed through studies with small populations, muscular strength/endurance and flexibility were classified through the same cut-points from five different assessment batteries.

CONCLUSIONS

The research on muscular strength/endurance, cardiorespiratory fitness and flexibility has been scarcely explored. The lack of studies that investigated method usability as well as reference values was evidenced.

Microalbuminuria in Perinatally HIV-Infected Children and Adolescents in the United States

Background

The kidney is a common target for human immunodeficiency virus (HIV), making renal disease a common noninfectious complication of HIV. Microalbuminuria is an important marker that can detect early renal damage. Timely detection of microalbuminuria is important to initiate renal management and stop the progression of renal dysfunction in people with HIV. Limited data are available about renal abnormalities in people with perinatal HIV infection. The objective of this study was to determine the prevalence of microalbuminuria in a cohort of perinatally HIV-infected children and young adults receiving combination antiretroviral therapy and investigate correlations between microalbuminuria and clinical and laboratory findings.

Methods

This was a retrospective study of 71 patients with HIV followed in an urban pediatric HIV clinic in Houston, Texas, between October 2007 and August 2016. Demographic, clinical, and laboratory data were compared between subjects with persistent microalbuminuria (PM) and those without. PM is defined as a microalbumin-to-creatinine ratio ≥30 mg/g on at least 2 occasions separated by at least 1 month.

Results

Sixteen of 71 patients (23%) met the definition of PM. In univariate analysis, patients with PM had significantly higher CD8⁺ T-cell activation and lower CD4⁺ T-cell nadir. Multivariate analysis demonstrated increased microalbuminuria to be independently associated with older age and CD8⁺ T-cell activation measured as CD8⁺HLA-DR⁺ T-cell percentage.

Conclusions

Older age and increased activation of CD8⁺HLA-DR⁺ on T cells correlate with presence of microalbuminuria in this cohort of HIV-infected patients.

Pharmacotherapeutic options for kidney disease in HIV positive patients

INTRODUCTION

Since the developmentof combined antiretroviral therapy (cART), HIV-associated mortality and the incidence of HIV-associated end-stage kidney disease (ESKD) has decreased. However, in the United States, an increase in non-HIV-associated kidney diseases within the HIV-positive population is expected.

AREAS COVERED

In this review, the authors highlight the risk factors for kidney disease within an HIV-positive population and provide the current recommendations for risk stratification and for the monitoring of its progression to chronic kidney disease (CKD), as well as, treatment. The article is based on literature searches using PubMed, Medline and SCOPUS.

EXPERT OPINION

The authors recommend clinicians (1) be aware of early cART initiation to prevent and treat HIV-associated kidney diseases, (2) be aware of cART side effects and discriminate those that may become more nephrotoxic than others and require dose-adjustment in the setting of eGFR ≤ 30ml/min/1.73m², (3) follow KDIGO guidelines regarding screening and monitoring for CKD with a multidisciplinary team of health professionals, (4) manage other co-infections and comorbidities, (5) consider changing cART if drug induced toxicity is established with apparent eGFR decline of ≥ 10ml/min/1.73m² or rising creatinine (≥0.5mg/dl) during drug-drug interactions, and (6) strongly consider kidney transplant in appropriately selected individuals with end stage kidney failure.

Proximal renal tubular function in HIV-infected children on tenofovir disoproxil fumarate for treatment of HIV infection at two tertiary hospitals in Harare, Zimbabwe

BACKGROUND

Renal abnormalities in HIV infected children may be due to the HIV infection or treatment among other factors. Tenofovir disoproxil fumarate (TDF) is associated with proximal renal tubular dysfunction, proteinuria and decrease in glomerular function. Studies in developed countries have shown variable prevalence of proximal renal tubular dysfunction in children on TDF. There are no known studies in developing countries, including Zimbabwe, documenting the proximal tubular function in HIV infected children on TDF. The aim of this study was to assess renal and proximal renal tubular function in HIV infected children receiving TDF and determine factors associated with proximal tubular dysfunction.

METHODS

A descriptive cross-sectional study was conducted in HIV infected patients below 18 years of age attending outpatient clinics at two tertiary hospitals in Harare, who received a TDF-containing antiretroviral regimen for at least six months. Dipstick protein and glucose, serum and urine phosphate and creatinine levels were measured. Fractional excretion of phosphate was calculated. Estimated glomerular filtration rate (eGFR) was calculated using the Schwartz formula. Tubular dysfunction was defined by at least two of the following characteristics: normoglycaemic glycosuria, hypophosphatemia and fractional excretion of phosphate > 18%.

FINDINGS

One hundred and ninety-eight children below 18 years of age were recruited over a period of six months. The prevalence of tubular dysfunction was 0.5%. Normoglycaemic glycosuria occurred in 1 (0.5%), fractional excretion of phosphate >18% in 4 (2%), and hypophosphatemia in 22 [11.1%] patients. Severe stunting was associated with increased risk of hypophosphatemia (OR 9.31 CI (1.18, 80.68) p = 0.03). Reduction in estimated glomerular filtration rate (eGFR) < 90ml/min/1.73m2 and proteinuria was evident in 35.9% and 32.8% of children, respectively. Concurrent TDF and HIV-1 protease inhibitor-based regimen was the only independent factor associated with reduction in GFR (OR 4.43 CI (1.32; 4.89) p = 0.016).

CONCLUSION

Tubular dysfunction was uncommon in Zimbabwean children on a TDF-based ART regimen. Hypophosphatemia, proteinuria and reduction in eGFR were common. Reassessing renal function using more sensitive biomarkers is needed to examine the long-term tolerance of TDF.

[Tenofovir-associated Fanconi`s syndrome and rickets in a HIV infected girl]

Tenofovir (TDF) is an inhibitor of reverse transcriptase nucleotide analogue, although it has good tolerability and high anti-retroviral activity, its effect on the kidney has been a concern.

OBJECTIVE

To describe a girl infected with HIV who presented Fanconi syndrome during antiretroviral therapy with TDF.

CLINICAL CASE

We describe a HIV-1-infected girl, who after 18 months treatment with TDF presented loss of strength and pain of the lower extremities with functional impairment. Laboratory findings were consistent with Fanconi syndrome. Radiographs showed bilateral hip fracture and wrists. Full recovery of Fanconi syndrome was achieved four months after changing antiretroviral therapy.

CONCLUSIONS

TDF-prescribing physicians must be prepared to detect signs and symptoms of renal dysfunction and immediately consider switching to another antiviral drug.

A review of renal disease in children with HIV infection

Human immunodeficiency virus (HIV) infection continues to be a leading cause of morbidity and mortality. HIV-infected individuals are now surviving for a relatively longer period and this is because of easy accessibility to antiretroviral therapy these days. As a result, chronic disease-related complications are now being recognized more often. Kidney disease in HIV-infected children can vary from glomerular to tubular-interstitial involvement. We searched the database to identify various kidney diseases seen in HIV-infected children. We describe the epidemiology, pathogenesis, pathology, clinical and laboratory manifestations, management and outcome of commonly seen kidney disease in HIV-infected children. We also provide a brief overview of toxicity of antiretroviral drugs seen in HIV-infected children. Kidney involvement in HIV-infected children may arise because of HIV infection per se, opportunistic infections, immune mediated injury and drug toxicity. HIV-associated nephropathy is perhaps the most common and most severe form of kidney disease. Proteinuria may be a cost-effective screening test in the long-term management of HIV-infected children, however, there are no definite recommendations for the same. Other important renal diseases are HIV immune complex kidney disease, thrombotic microangiopathy, interstitial nephritis and vasculitis.

Predictive factors and prevalence of microalbuminuria in HIV-infected patients: a cross-sectional analysis

Background

Renal dysfunction is a common problem in the HIV+ population, due to the effect of both the HIV virus and the several classes of ARV drugs such as tenofovir (TDF). It is also known that the presence of renal damage correlates with cardiovascular risk and therefore with the risk of mortality of the patients accordingly. The detection of early renal damage is very important. Albuminuria and microalbuminuria are markers of early kidney disease and cardiovascular risk. The aim of the study is to evaluate the prevalence of microalbuminuria in a large polycentric sample, of unselected and consecutive HIV-patients followed as outpatients, and to assess its association with different therapeutic regimens.

Methods

We studied 326 patients with a mean age of 48.4 ± 1.6 years, treated at the Infectious Diseases Clinics of Chieti and Perugia for 48 weeks. The main metabolic parameters and the microalbuminuria levels in a single sample of urine were evaluated.

Results

Microalbuminuria was detected in 61.0% of patients at T0 and in 49.7% after 48 weeks of observation with a median values of 1.1 mg/L (IQR: 0-2.7) vs. 0 mg/L (IQR: 0-2.0). 70% of the enrolled population did not show changes in microalbuminuria levels over time, 19% showed improvement, and 11% of the population had a worsening of microalbuminuria levels without any alteration of creatinine, uric acid and GFR-MDRD. We also found a statistically significant association between the development of microalbuminuria and gender (p < 0.035), Arterial Hypertension (AH) (p < 0.028) and therapy with TDF (p < 0.050).

Conclusion

We showed a very high prevalence of microalbuminuria, much higher than the literature data; the use of TDF affects the renal function in a statistically significant way and should therefore be considered a risk factor for kidney damage, which can be early assessed with the measurement of microalbuminuria.

Renal and Bone Adverse Effects of a Tenofovir-Based Regimen in the Treatment of HIV-Infected Children: A Systematic Review

INTRODUCTION

Tenofovir disoproxil fumarate (TDF)-containing regimens in the treatment of HIV-infected children have safety concerns with respect to renal and bone toxicity.

OBJECTIVE

The aim of this study was to systematically review and critically appraise the literature relating to the reported renal and bone adverse effects of TDF-based regimens in the treatment of HIV-infected children from 2 to 19 years old.

METHODS

Searches were performed using the Cochrane Central Register of Controlled Trials (CENTRAL), Cumulative Index to Nursing and Allied Health Literature (CINAHL), MEDLINE, OvidSP, ScienceDirect and Web of Science databases and platforms. All primary studies involving tenofovir use in HIV-infected children were sought. Studies that involved the use of TDF for pre- and post-exposure prophylaxis, and treatment of chronic hepatitis B virus infection were excluded. Data on study characteristics, participant's characteristics, therapeutic intervention and adverse effects were extracted using a piloted tool. In addition, pharmacovigilance data from the WHO Adverse Reaction database were included.

RESULTS

We identified 19 studies that reported the presence of renal and bone adverse effects of TDF and these included a total of 1100 study participants. The reports were in distinctly heterogeneous participant groups. A total of 287 renal and bone adverse effects were reported (250 renal and 37 bone adverse effects). Approximately 238 (21.6 %) participants were affected by these adverse effects. Of these, 15 participants stopped their TDF-containing regimen due to these adverse effects. In addition, the pharmacovigilance data from the WHO Adverse Reaction database reported 101 renal and bone adverse effects for patients whose indication was HIV/AIDS.

CONCLUSION

This systematic review summarises the reports of renal and bone adverse effects of a TDF-containing regimen in the treatment of HIV-infected children. Our findings suggest that the benefits of using TDF in children need to be balanced against the potential risk of toxicity.

Long-term renal effects of tenofovir-disoproxil-fumarate in vertically HIV-infected children, adolescents, and young adults: a 132-month follow-up study

BACKGROUND AND OBJECTIVES

The introduction of highly active anti-retroviral therapy has led to a significant decline in morbidity and mortality. Although several studies in adult populations have shown that tenofovir-disoproxil-fumarate (TDF) use is associated with a significant loss of renal function, there is still uncertainty on the long-term TDF safety profile in pediatric HIV populations, mostly in vertically HIV-infected patients. The aim of this study was to evaluate the long-term TDF renal safety profile, during a ten-year follow up.

METHODS

Twenty-six vertically HIV-infected patients were evaluated for a total of 132 months of follow up, monitoring anthropometric parameters, renal function, viral load and CD4+ count. Generalized estimating equations were used to evaluate the changes in anthropometric and laboratory variables. Multivariable fractional polynomials were used to test for the existence of non-linear relationships of outcomes with time and other continuous covariates. In all patients, weight, height and body mass index increased linearly with time. CD4+ count and glomerular filtration rate decreased linearly with time (p < 0.01).

RESULTS

No significant increase of serum creatinine was registered. An inverse linear relationship between time and plasma phosphate was found. Hypophosphatemia was detected in 17 patients, mostly mild. In 14 out of 17 we also genotyped single nucleotide polymorphisms rs717620 mapping in ABCC2, a gene encoding for a renal transporter.

CONCLUSIONS

Our study demonstrates the relative safety of prolonged use of TDF in vertically HIV-infected children and young adults. The most relevant alteration that emerged was hypophosphatemia, appearing after 72 months of TDF therapy, mostly mild and without clinical significance.

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

BACKGROUND

Tenofovir disoproxil fumarate (TDF) is approved for children but concerns remain about long-term renal and bone toxicity. We evaluated the efficacy, safety and pharmacokinetics of TDF in treatment-experienced children during 96 weeks.

METHODS

This was a prospective, open-label study in HIV-infected children 3-18 years of age (≥15 kg), with viral suppression on their first-line regimen without tenofovir. Children were given TDF/lamivudine/efavirenz once daily at entry; TDF was prescribed according to weight bands. Age-, gender- and CD4-matched controls receiving TDF-sparing regimens were concomitantly enrolled. Tenofovir pharmacokinetic assessment was performed at week 4. CD4 counts, HIV-1 RNA viral load and safety assessments were determined at baseline, 24, 48 and 96 weeks.

RESULTS

Eighty children were enrolled (40 per group); 35 (44%) were male. Median age was 12.2 (range 3.1-17.7) years. The median administered dose was 214 mg/m. Tenofovir geometric mean AUC0-24 hours, Cmax and C24 hours were 2.66 [90% confidence interval (CI) 2.49-2.84] μg hours/mL, 0.26 (0.24-0.29) μg/mL and 0.057 (0.052-0.062) μg/mL, respectively. Estimated glomerular filtration rate did not significantly change overtime. The fractional excretion of calcium slightly increased but fractional excretion of phosphate was unchanged among children in TDF group. The bone mineral density Z score decreased in the first 24 weeks of TDF treatment and was stable afterward. The TDF group had lower cholesterol levels (P = 0.001). Thirty-nine of 40 children remained virologically suppressed. No serious adverse event related to tenofovir.

CONCLUSION

TDF substitution in children and adolescents who were otherwise stable while receiving a first-line nonnucleoside reverse transcriptase inhibitor-based regimen achieved adequate exposure without clinically significant renal or bone adverse events over 96 weeks. While reassuring, these preliminary safety findings may not exclude delayed effects on renal function and bone density.

Review of tenofovir use in HIV-infected children

Tenofovir disoproxil fumarate (TDF) is approved by the Food and Drug Administration for use in children ages 2 years and older and is recommended by the World Health Organization for use as a preferred first-line nucleotide reverse transcriptase inhibitor in adults and adolescents ages 10 years and older. The simplicity of once daily dosing, few metabolic side effects and efficacy against hepatitis B virus make TDF suitable for use in a large scale program. Unlike thymidine analoge nucleoside reverse transcriptase inhibitors (NRTIs); tenofovir does not induce multi-NRTI resistance mutations, so more NRTI options are available for future second-line-regimens. Fixed-dose combinations of TDF with other ARVs as a single tablet regimen are now widely available for adults and adolescents, but none are available for young children. Current information on TDF including the pharmacokinetics, safety and tolerability in children and adolescents was reviewed. A dosing regimen according to body-weight-band has been established for pediatric use. Safety concerns of TDF mainly relate to its effects on renal function and bone mineral density. Regular monitoring of renal function in high-risk patients, including those on other nephrotoxic drugs, may be warranted to detect adverse renal effects. Long-term-data on renal and bone outcomes among HIV-infected children is needed. Lessons learned from clinical studies will help clinicians balance the risks and benefits of TDF and design appropriate antiretroviral regimens for children in different circumstances.

Clinical practice guideline for the management of chronic kidney disease in patients infected with HIV: 2014 update by the HIV Medicine Association of the Infectious Diseases Society of America

It is important to realize that guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. IDSA considers adherence to these guidelines to be voluntary, with the ultimate determination regarding their application to be made by the physician in the light of each patient's individual circumstances.

Update on tenofovir toxicity in the kidney

Tenofovir (TFV) is a widely used and effective treatment for HIV infection. Numerous studies have shown that TFV exposure is associated with small but significant declines in estimated glomerular filtration rate (eGFR). However, TFV toxicity is targeted mainly at the proximal tubule (PT), and in severe cases can cause the renal Fanconi syndrome or acute kidney injury. Severe toxicity occurs in a minority of patients, but milder PT dysfunction is more common; the long-term significance of this on kidney and bone health is uncertain. Recent work suggests that changes in eGFR on TFV therapy might be explained by inhibition of PT creatinine secretion rather than actual alterations in glomerular function. Risk factors for nephrotoxicity include pre-existing kidney disease, increased age, and low body mass. Mitochondria in the PT are the targets of TFV toxicity, but the exact mechanisms remain unclear. Substantial improvement of renal function occurs in many patients with TFV toxicity upon stopping therapy, but function does not always return to baseline. In recent years, TFV usage has been extended to new clinical spheres, including pediatrics, resource-poor settings and treatment of hepatitis B infection; theoretical reasons exist as to why some of these patients might be at higher or lower risk of TFV toxicity. Finally, strategies have been proposed to prevent TFV toxicity or enhance recovery.

Kidney disease in children and adolescents with perinatal HIV-1 infection

Introduction

Involvement of the kidney in children and adolescents with perinatal (HIV-1) infection can occur at any stage during the child's life with diverse diagnoses, ranging from acute kidney injury, childhood urinary tract infections (UTIs), electrolyte imbalances and drug-induced nephrotoxicity, to diseases of the glomerulus. The latter include various immune-mediated chronic kidney diseases (CKD) and HIV-associated nephropathy (HIVAN).

Discussion

The introduction of highly active anti-retroviral therapy (HAART) has dramatically reduced the incidence of HIVAN, once the commonest form of CKD in children of African descent living with HIV, and also altered its prognosis from eventual progression to end-stage kidney disease to one that is compatible with long-term survival. The impact of HAART on the outcome of other forms of kidney diseases seen in this population has not been as impressive. Increasingly important is nephrotoxicity secondary to the prolonged use of anti-retroviral agents, and the occurrence of co-morbid kidney disease unrelated to HIV infection or its treatment. Improved understanding of the molecular pathogenesis and genetics of kidney diseases associated with HIV will result in better screening, prevention and treatment efforts, as HIV specialists and nephrologists coordinate clinical care of these patients. Both haemodialysis (HD) and peritoneal dialysis (PD) are effective as renal replacement therapy in HIV-infected patients with end-stage kidney disease, with PD being preferred in resource-limited settings. Kidney transplantation, once contraindicated in this population, has now become the most effective renal replacement therapy, provided rigorous criteria are met. Given the attendant morbidity and mortality in HIV-infected children and adolescents with kidney disease, routine screening for kidney disease is recommended where resources permit.

Conclusions

This review focuses on the pathogenesis and genetics, clinical presentation and management of kidney disease in children and adolescents with perinatal HIV-1 infection.

Tenofovir treatment duration predicts proteinuria in a multiethnic United States Cohort of children and adolescents with perinatal HIV-1 infection

BACKGROUND

Tenofovir is associated with renal proximal tubule injury. Such toxicity has not been extensively studied in HIV-1-infected children, in whom tenofovir is increasingly used.

METHODS

History, urine and blood were collected at regular intervals from 448 children and adolescents with perinatal HIV-1 infection followed in the Pediatric HIV/AIDS Cohort study. Relationships between tenofovir use and proteinuria and chronic kidney disease (CKD) outcomes were examined using multivariable logistic regression models. Proteinuria was defined as at least one urine protein/creatinine ratio (uPCR) ≥ 0.2, and CKD as ≥ 2 sequential uPCR ≥ 0.2 or estimated glomerular filtration rates <60 mL/min/1.73 m with no subsequent resolution, or a clinical diagnosis not contradicted by a normal uPCR. Subjects with ≥ 2 uPCR <0.2, and no abnormal uPCR and eGFR comprised the comparison group.

RESULTS

Subjects were 47% male, 72% black, 24% Hispanic, with entry mean age (± standard deviation) of 11.5 ± 2.5 years. Proteinuria prevalence at entry, and annually during 3 years, ranged from 10.3% to 13.7%. The cumulative prevalence of proteinuria was 22% (94/434, 95% confidence interval: 18%-26%) and CKD 4.5% (20/448, 95% confidence interval: 2.7%-6.8%). Duration of tenofovir use was an independent predictor of proteinuria, with >3 years of exposure having the highest risk compared with no exposure (odds ratio: 2.53, 95% confidence interval: 1.23-5.22, overall P = 0.01). Overall, duration of tenofovir use did not significantly predict the presence of CKD.

CONCLUSIONS

Rates of proteinuria and CKD were lower than those seen in the pre-highly active antiretroviral therapy era. However, prolonged exposure to tenofovir increases risk of renal injury.

Proteinuria in paediatric patients with human immunodeficiency virus infection

In human immunodeficiency virus (HIV)-infected people kidney disease is as an important cause of morbidity and mortality. Clinical features of kidney damage in HIV-infected patients range from asymptomatic microalbuminuria to nephrotic syndrome. The lack of specific clinical features despite the presence of heavy proteinuria may mask the renal involvement. Indeed, it is important in HIV patients to monitor renal function to early discover a possible kidney injury. After the introduction of antiretroviral therapy, mortality and morbidity associated to HIV-infection have shown a substantial reduction, although a variety of side effects for long-term use of highly active antiretroviral therapy, including renal toxicity, has emerged. Among more than 20 currently available antiretroviral agents, many of them can occasionally cause reversible or irreversible nephrotoxicity. At now, three antiretroviral agents, i.e., indinavir, atazanavir and tenofovir disoproxil fumarate have a well established association with direct nephrotoxicity. This review focuses on major causes of proteinuria and other pathological findings related to kidney disease in HIV-infected children and adolescents.

Stampidine as a promising antiretroviral drug candidate for pre-exposure prophylaxis against sexually transmitted HIV/AIDS

INTRODUCTION

Pre-exposure prophylaxis (PrEP) is an evolving new approach to prevention of sexually transmitted HIV-1 that employs antiretroviral (ARV) agents prior to potential HIV-1 exposure in an attempt to reduce the likelihood of HIV-1 infection postexposure. The identification of new ARV agents with potent activity against multidrug-resistant HIV remains an unmet and urgent challenge in the field of PrEP.

AREAS COVERED

This article reviews the preclinical and early clinical activity and safety profile of stampidine, a novel antiretroviral (ARV) drug candidate that exhibits remarkable subnanomolar to low nanomolar in vitro antiretroviral potency against genotypically and phenotypically nucleoside reverse transcriptase inhibitor (NRTI)-resistant primary clinical HIV isolates, non-nucleoside RT-resistant HIV-1 isolates. Stampidine has a favorable pharmacokinetic profile in mice, rats, dogs and cats with 25 or 50 mg/kg tolerable dose levels yielding micromolar plasma concentrations that are 1000-fold higher than its in vitro IC(50) value against HIV. Stampidine has a favorable, safety profile in mice, rats, dogs and cats and it showed significant in vivo ARV activity in HIV-infected Hu-PBL-SCID mice as well as FIV-infected domestic cats. Furthermore, it did not cause any maternal toxicity, developmental toxicity or teratogenicity in rabbits treated at 10 - 40 mg/kg/day dose levels. In a recently completed first-in-human Phase I clinical trial, stampidine did not cause dose-limiting toxicity at single dose levels ranging from 5 to 25 mg/kg.

EXPERT OPINION

The favorable safety and activity profile of stampidine warrants its further development as a promising next-generation PrEP candidate to prevent the sexual transmission of HIV-1. The discovery of stampidine as a potent antiretroviral agent represents a significant step forward in the development of effective therapeutic as well as preventive strategies against HIV/AIDS.

Long-term renal safety of tenofovir disoproxil fumarate in vertically HIV-infected children, adolescents and young adults: a 60-month follow-up study

BACKGROUND AND OBJECTIVE

Sporadic cases of renal toxicity have been reported in HIV-infected children treated with tenofovir disoproxil fumarate (TDF). We assessed the long-term renal safety of TDF in a cohort of vertically HIV-infected children, adolescents and young adults.

METHODS

We evaluated 26 HIV-infected children, adolescents and young adults, aged 4.9-17.4 years at baseline, every 6 months for 60 consecutive months. At the baseline visit, they had an undetectable viral load and a good immune reconstitution and were being treated with lamivudine, stavudine and a protease inhibitor (PI). At the same visit, stavudine was replaced with TDF and the PI with efavirenz. Serum creatinine, estimated glomerular filtration rate (GFR), urine protein to creatinine ratio, serum phosphate, ratio of the maximum rate of tubular phosphate reabsorption to the GFR (TmPO(4)/GFR), urine glucose, and urine α(1)-microglobulin to creatinine ratio were used as markers of renal function. The outcome-time relationships were studied using generalized estimating equations (GEEs). In addition to time (continuous, ten equally spaced intervals), sex, age at baseline and CD4+ T-cell count were used as covariates.

RESULTS

A moderate reduction in GFR was observed only once in an underweight female patient. There was no occurrence of proteinuria, hypophosphataemia or glycosuria. Moreover, TmPO(4)/GFR was stable and the urine α(1)-microglobulin to creatinine ratio was always within normal limits.

CONCLUSION

TDF had an excellent renal safety profile in HIV-infected children, adolescents and young adults regularly followed up for 60 months.

Prospective study of renal function in HIV-infected pediatric patients receiving tenofovir-containing HAART regimens

AIM

to describe the impact of tenofovir disoproxil fumarate (TDF) use on renal function in HIV-infected pediatric patients.

DESIGN

it is a prospective, multicenter study. The setting consisted of five third-level pediatric hospitals in Spain. The study was conducted on patients aged 18 years and younger who had received TDF for at least 6 months. The intervention was based on the study of renal function parameters by urine and serum analyses. The main outcome measures were renal function results following at least 6 months of TDF therapy.

RESULTS

forty patients were included (32 were white and 26 were diagnosed with AIDS). Median (range) duration of TDF treatment was 77 months (16-143). There were no significant changes in the estimated creatinine clearance. Urine osmolality was abnormal in eight of 37 patients, a decrease in tubular phosphate absorption was documented in 28 of 38 patients, and 33 of 37 patients had proteinuria. A statistically significant decrease in serum phosphate and potassium concentrations was observed during treatment (P = 0.005 and P = 0.003, respectively), as well as a significant relationship between final phosphate concentration and tubular phosphate absorption (P = 0.010). A negative correlation was found between phosphate concentration and time on TDF.

CONCLUSIONS

TDF use showed a significant association with renal tubular dysfunction in HIV-infected pediatric patients. Periodic assessment of tubular function may be advisable in the follow-up of this population.

Youth-specific considerations in the development of preexposure prophylaxis, microbicide, and vaccine research trials

Preventing HIV infection in adolescents and young adults will require a multimodal targeted approach, including individual-directed behavioral risk reduction, community-level structural change, and biomedical interventions to prevent sexual transmission. Trials testing biomedical interventions to prevent HIV transmission will require special attention in this population due to the unique psychosocial and physiologic characteristics that differentiate them from older populations. For example, microbicide research will need to consider acceptability, dosing requirements, and coinfection rates that are unique to this population. Preexposure prophylaxis studies also will need to consider potential unique psychosocial issues such as sexual disinhibition and acceptability as well as unique pharmacokinetic parameters of antiretroviral agents. Vaccine trials also face unique issues with this population, including attitudes toward vaccines, risks related to false-positive HIV tests related to vaccine, and different immune responses based on more robust immunity. In this article, we will discuss issues around implementing each of these biomedical prevention modalities in trials among adolescents and young adults to help to guide future successful research targeting this population.

Growing up with HIV: children, adolescents, and young adults with perinatally acquired HIV infection

Tremendous success in the prevention and treatment of pediatric HIV in high-resource countries has changed the face of the epidemic. A perinatally HIV-infected child now faces a chronic disease rather than a progressive, fatal one. However, these successes pose new challenges as perinatally HIV-infected youth survive into adulthood. These include maintaining adherence to long-term, likely life-long therapy; selecting successive antiretroviral drug regimens, given the limited availability of pediatric formulations and the lack of pharmacokinetic and safety data in children; and overcoming extensive drug resistance in multi-drug-experienced children. Pediatric HIV care now focuses on morbidity related to long-term HIV infection and its treatment. Survival into adulthood of perinatally HIV-infected youth in high-resource countries encourages expansion of pediatric treatment programs in low-resource countries, where most HIV-infected children live, and provides important lessons about how the epidemic changes with increasing access to antiretroviral therapy for children.

Effect of tenofovir disoproxil fumarate on risk of renal abnormality in HIV-1-infected children on antiretroviral therapy: a nested case-control study

OBJECTIVE

To investigate the association between tenofovir disoproxil fumarate (TDF) use and renal abnormality in a large cohort of HIV-1-infected children on antiretroviral therapy (ART).

DESIGN

Nested case-control study.

METHODS

Patients were from the Collaborative HIV Paediatric Study, a cohort of approximately 95% of HIV-1-infected children in the UK/Ireland. Serum (but not urine) biochemistry results for 2002-2008 were obtained for 456 ART-exposed children (2-18 years) seen at seven hospitals. Cases had either confirmed hypophosphataemia DAIDS grade at least 2 or estimated glomerular filtration rate (eGFR) less than 60 ml/min per 1.73 m; three controls per case were matched by hospital. Conditional logistic regression identified risk factors for renal abnormality.

RESULTS

Twenty of 456 (4.4%) had hypophosphataemia, and one had eGFR less than 60 ml/min per 1.73 m. Ten of 20 (50%) cases versus 11 of 60 (18%) controls had taken TDF-containing ART for a median [interquartile range (IQR)] of 18 [17-20] months, as part of second-line or salvage therapy. The hypophosphataemia incidence rate was 4.3/100 person-years in the TDF group versus 0.9/100 person-years in those not exposed to TDF. In multivariable analysis, only TDF exposure in the previous 6 months was associated with hypophosphataemia [odds ratio (OR) = 4.81, 95% confidence interval (CI) 1.45-16.0, P = 0.01]. In six of 10 children with hypophosphataemia and at least four subsequent phosphate measurements, phosphate values returned to normal when TDF was stopped; in four with three measures or less, values rose but remained subnormal.

CONCLUSIONS

Hypophosphataemia was uncommon (4%), but was associated with prolonged TDF use, and was generally reversible following TDF withdrawal. Findings highlight the importance of continuing to monitor longer-term renal function, in particular tubular function, especially in those taking TDF. Further studies assessing urine biochemistry measures which more accurately indicate renal tubular damage are required.

Progressive renal tubular dysfunction associated with long-term use of tenofovir DF

It became evident that tenofovir DF (TDF) causes a modest and gradual decline in GFR, however, the impact of long-term use of TDF on tubular function has not been fully evaluated. In 40 patients treated with TDF and 23 patients treated with other NRTIs, urine beta(2)-microglobulin (U-BMG), percentage tubular reabsorption of phosphate (%TRP), alkaline phosphatase (ALP), serum creatinine, and calculated GFR were prospectively measured for 96 weeks. In patients receiving TDF, median U-BMG rose from 188 microg/liter at baseline to 555 microg/liter at week 96 (p = 0.02), median %TRP declined from 94% at baseline to 90% at week 96 (p = 0.002), median ALP ratio compared with baseline persistently increased from 1 to 1.278 at week 96 (p = 0.001), and serum creatinine showed significant but minimal change from 0.64 mg/dl to 0.74 mg/dl at week 96 (p = 0.02). The GFR level declined minimally but significantly in TDF-receiving patients (-17 ml/min/1.73 m(2)), whereas it did not change in other NRTI-receiving patients [+ 3 ml/min/1.73 m(2); mixed models analysis of variance (MMANOVA) p = 0.03 for overall change from baseline to week 96]. U-BMG, %TRP, ALP, or serum creatinine did not change significantly in other NRTI-receiving patients during the observation period. In five patients with marked changes in U-BMG (>10,000 microg/liter) and %TRP (<80%), both U-BMG and %TRP immediately recovered in all patients after discontinuing TDF, whereas GFR levels did not fully recover for 6 months in three patients. Prolonged treatment with TDF caused progressive renal tubular dysfunction as well as a modest decline in GFR. If U-BMG levels >10,000 microg/liter and %TRP values <80% are observed, discontinuing TDF may be beneficial.

Tenofovir use in human immunodeficiency virus-1-infected children in the United kingdom and Ireland

BACKGROUND

Tenofovir disoproxil fumarate (TDF) is neither licensed for use nor extensively studied in HIV-infected children. The only available formulation is an adult tablet, introducing the possibility of dosing errors in children. TDF interacts with other antiretrovirals and has been associated with decline in renal function and CD4 count. We describe the use of TDF in a cohort of HIV-1-infected children in the United Kingdom and Ireland.

METHODS

Children ever prescribed TDF and followed in the Collaborative HIV Pediatric Study cohort since 2001 were included in analyses of dosing, adverse events, and virologic and immunologic response. Suspected adverse drug reactions to TDF reported to the Medicines and Healthcare products Regulatory Agency during the same time were also reviewed.

RESULTS

One hundred fifty-nine of 1253 children had taken TDF. They were older and had clinically more advanced disease than the rest of the cohort. Eighteen percent received >120% and 37% received <80% of the suggested pediatric dose (8 mg/kg). Thirty-seven percent of new TDF regimens contained didanosine (ddI), though few since 2005. Twelve of 159 (7.5%) children experienced serious adverse events and stopped TDF permanently, 11 taking concurrent lopinavir-ritonavir, and 10 ddI; 5 had renal toxicity. Viral load suppressed to < or =50 copies/mL at 12 months in 38% of those starting TDF. Median increase in CD4 count at 12 months was +110 cells/mL (interquartile range, 9-270), but only 3 cells/mL in those taking concurrent ddI.

CONCLUSIONS

TDF seems to be an effective antiretroviral drug in this pediatric cohort, although considerable underdosing and overdosing occurs. A small number of children experienced serious adverse events while taking TDF; half were renal toxicity, most associated with concurrent ddI and lopinavir-ritonavir use.

[Management of renal toxicity in HIV-positive patients. What to measure, how to measure it and how frequently]

Chronic kidney disease in patients with HIV is being recognized as one of the most frequent comorbidities of this disease and consequently much research is currently being performed in this area. The possible manifestations are highly varied and consequently a high index of suspicion is required. Appropriate investigations should be performed from the moment patients first seek care to rule out renal disease and to prevent worsening, with the diagnostic or therapeutic measures that may subsequently be required. One of the most common problems is nephrotoxicity caused by some drugs and cases associated with tenofovir are becoming more frequently described. However, there is wide clinical experience with this drug and renal toxicity associated with its use is uncommon both in clinical trials and in clinical practice. Familiarity with what may happen, the associated factors and appropriate patient management are essential.

Pharmacologic and nonpharmacologic options for the management of HIV infection during pregnancy

Over the past decade, significant advances have been made in the treatment of HIV-1 infection using both pharmacologic and nonpharmacologic strategies to prevent mother-to-child transmission (MTCT). Optimal prevention of the MTCT of HIV requires antiretroviral drugs (ARV) during pregnancy, during labor, and to the infant. ARVs reduce viral replication, lowering maternal plasma viral load and thus the likelihood of MTCT. Postexposure prophylaxis of ARV agents in newborns protect against infection following potential exposure to maternal HIV during birth. In general, the choice of an ARV for treatment of HIV-infected women during pregnancy is complicated by the need to consider the effectiveness of the therapy for the maternal disease as well as the teratogenic or teratotoxic potential of these drugs. Clinicians managing HIV in pregnancy need to discuss the potential risks and benefits of available therapy options so that mothers can make informed decisions in choosing the best treatment regimen for themselves and for their children.

Chronic administration of tenofovir to rhesus macaques from infancy through adulthood and pregnancy: summary of pharmacokinetics and biological and virological effects

The reverse transcriptase (RT) inhibitor tenofovir (TFV) is highly effective in the simian immunodeficiency virus (SIV) macaque model of human immunodeficiency virus infection. The current report describes extended safety and efficacy data on 32 animals that received prolonged (>or=1- to 13-year) daily subcutaneous TFV regimens. The likelihood of renal toxicity (proximal renal tubular dysfunction [PRTD]) correlated with plasma drug concentrations, which depended on the dosage regimen and age-related changes in drug clearance. Below a threshold area under the concentration-time curve for TFV in plasma of approximately 10 microg x h/ml, an exposure severalfold higher than that observed in humans treated orally with 300 mg TFV disoproxil fumarate (TDF), prolonged TFV administration was not associated with PRTD based on urinalysis, serum chemistry analyses, bone mineral density, and clinical observations. At low-dose maintenance regimens, plasma TFV concentrations and intracellular TFV diphosphate concentrations were similar to or slightly higher than those observed in TDF-treated humans. No new toxicities were identified. The available evidence does not suggest teratogenic effects of prolonged low-dose TFV treatment; by the age of 10 years, one macaque, on TFV treatment since birth, had produced three offspring that were healthy by all criteria up to the age of 5 years. Despite the presence of viral variants with a lysine-to-arginine substitution at codon 65 (K65R) of RT in all 28 SIV-infected animals, 6 animals suppressed viremia to undetectable levels for as long as 12 years of TFV monotherapy. In conclusion, these findings illustrate the safety and sustained benefits of prolonged TFV-containing regimens throughout development from infancy to adulthood, including pregnancy.