Tenofovir-induced renal toxicity in 324 HIV-infected, antiretroviral-naïve patients

An Efficient Humanized Mouse Model for Oral Anti-Retroviral Administration

HIV anti-retrovirals (ARVs) have vastly improved the life expectancy of people living with HIV (PLWH). However, toxic effects attributed to long-term ARV use also contribute to HIV-related co-morbidities such as heart disease, bone loss and HIV-associated neurocognitive disorders (HAND). Unfortunately, mouse models used to study the effects of ARVs on viral suppression, toxicity and HIV latency/tissue reservoirs have not been widely established. Here, we demonstrate an effective mouse model utilizing immune-compromised mice, reconstituted with infected human peripheral blood mononuclear cell (PBMCs). ARVs areincorporated into mouse chow and administered daily with combination ARV regimens includingAtripla (efavirenz, tenofovir disoproxil fumarate, and emtricitabine) and Triumeq (abacavir, dolutegravir and lamivudine). This model measures HIV-infected human cell trafficking, and ARV penetration throughout most relevant HIV organs and plasma, with a large amount of trafficking to the secondary lymphoid organs. Furthermore, the HIV viral load within each organ and the plasma was reduced in ARV treated vs. untreated control. Overall, we have demonstrated a mouse model that is relatively easy and affordable to establish and utilize to study ARVs' effect on various tissues, including the co-morbid conditions associated with PLWH, such as HAND, and other toxic effects.

Renal impairment associated with tenofovir disoproxil fumarate for antiretroviral therapy and HIV pre-exposure prophylaxis: An observational cohort study

BACKGROUND

Tenofovir disoproxil fumarate (TDF) is associated with adverse renal outcomes when prescribed for HIV infection. There are few data concerning real-world renal outcomes amongst patients prescribed TDF for pre-exposure prophylaxis (PrEP).

METHODS AND FINDINGS

Data were extracted from 52 sexual health clinics across Australia from 2009-2019. All patients prescribed TDF-containing antiretroviral therapy and PrEP were included. Rates of renal impairment (a fall in eGFR to <60 ml/min/1·73m2) were calculated for people living with HIV (PLWHIV) prescribed TDF and HIV negative PrEP-users. Risk factors were assessed using Cox-proportional hazards models. Sensitivity analysis of risk using 1:1 propensity-score matching to adjust for potential imbalance in HIV and PrEP cohorts was conducted. 5,973 patients on PrEP and 1,973 PLWHIV were included. There were 39 (0.7%) instances of renal impairment in the PrEP group and 81 (4.1%) in the PLWHIV cohort (hazard ratio [HR]:0.35 95% confidence interval [CI]: 0.22-0.56). Rates of renal impairment were 4.01/1000 person-years (95%CI:2.93-5.48) in the PrEP cohort and 16.18/1000 person-years (95%CI:13.01-20.11) in the PLWHIV cohort (p<0.001). Predictors of renal impairment were: older age (40-49 years (HR:5.09 95%CI: 2.12-12.17) and 50-82 years (HR:13.69 95%CI: 5.92-31.67) (compared with 30-39 years) and baseline eGFR<90ml/min (HR:61.19 95%CI: 19.27-194.30). After adjusting for age and baseline eGFR the rate of renal impairment remained lower in the PrEP cohort (aHR:0.62 95%CI: 0.40-0.94, p = 0.023). In propensity-matched analysis using 1,622 patients per cohort the risk of renal impairment remained higher in the PLWHIV cohort (log-rank p = 0.001).

CONCLUSION

Patients prescribed TDF-based PrEP had lower rates of renal impairment than patients prescribed TDF for HIV infection. In propensity analysis, after matching for some risk factors, rates of renal impairment remained higher amongst patients with HIV.

Effects of long-term exposure to tenofovir disoproxil fumarate-containing antiretroviral therapy on renal function in HIV-positive Chinese patients

BACKGROUND

The regimen containing tenofovir disoproxil fumarate (TDF)+lamivudine or emtricitabine + efavirenz remains the recommended first-line antiretroviral therapy (ART) by the WHO. Limited studies, however, have been conducted on the incidence of renal impairment among Chinese patients with long-term exposure to TDF-containing ART regimens.

METHODS

We retrospectively analyzed 269 eligible patients who had no comorbidities and received TDF-containing ART from July 2014 to April 2015. TDF-related renal impairment was defined as a decrease of eGFR by >25% from baseline or eGFR <90 ml/min/1.73 m². Decreased renal function was defined as a decrease of eGFR by > 10 mL/min/1.73 m² from baseline.

RESULTS

97.0% of study patients were male (median age 29, eGFR 124.0 ml/min/1.73 m²). After 168-week of ART, renal impairment occurred in 7 patients (2.7%). The incidence of decreased renal function was significantly higher at Week 168 compared with that observed at Week 12 (24.8% vs 3.7%, p < 0.001). In generalized estimating equation analysis, patients receiving ART for 144-week (aOR4.1, 95%CI 2.0-8.4) and 168-week (aOR8.4, 95%CI 4.2-16.4) were more likely to develop decreased renal function compared with those receiving ART for 12-week, so were the patients with a weight <58 kg (aOR2.3, 95%CI 1.2-4.3) and 58-66 kg (aOR2.0, 95%CI 1.0-3.8) compared to those with a weight ≥67 kg. At 168-week, 41.0% of 100 patients examined had elevated urine β2-microglobulin levels, which were negatively correlated with eGFR (r = -0.22, p = 0.02).

CONCLUSIONS

TDF-related renal impairment remained rare in HIV-positive Chinese patients with a median age of 29 years who had no comorbidities. A lower weight and duration of ART were associated with decreased renal function.

Tenofovir-associated renal toxicity in a cohort of HIV infected patients in Ghana

Objective

Tenofovir disoproxil fumarate (TDF) is a nucleotide analogue recommended in international HIV treatment guidelines. Purpose of this study was to estimate the long term effects of TDF on renal profile in a cohort of HIV patients in Ghana. Three hundred (300) consecutive HIV-positive patients who initiated TDF-based antiretroviral treatment in 2008 at the Korle-Bu Teaching Hospital were sampled. Creatinine clearance (CrCl) was calculated using the Cockcroft-Gault equation at baseline and renal impairment was defined as CrCl values of 30.0–49.9 mL/min (moderate renal impairment) and < 30 mL/min (severe renal impairment) as per institutional guidelines for renal function test.

Results

Median follow up time was 2.9 years (IQR 2.3–3.4 years). At study endpoint, 63 participants (21.0% [95% CI 6.5–26.1]) recorded CrCl rate below 50 mL/min indicating incident renal impairment, made up of 18.3% moderate renal impairment and 2.3% severe renal impairment. Factors associated with incidence of renal impairment were increasing age, decrease in creatinine clearance rate at baseline, WHO HIV stage III/IV and participants with BMI of < 18.5 kg/m². Patients with identified renal impairment risk factors at ART initiation should be targeted and monitored effectively to prevent renal injury.

Adverse outcome pathway for aminoglycoside ototoxicity in drug-resistant tuberculosis treatment

Individuals treated for multidrug-resistant tuberculosis (MDR-TB) with aminoglycosides (AGs) in resource-limited settings often experience permanent hearing loss. However, AG ototoxicity has never been conceptually integrated or causally linked to MDR-TB patients' pre-treatment health condition. We sought to develop a framework that examines the relationships between pre-treatment conditions and AG-induced hearing loss among MDR-TB-infected individuals in sub-Saharan Africa. The adverse outcome pathway (AOP) approach was used to develop a framework linking key events (KEs) within a biological pathway that results in adverse outcomes (AO), which are associated with chemical perturbation of a molecular initiating event (MIE). This AOP describes pathways initiating from AG accumulation in hair cells, sound transducers of the inner ear immediately after AG administration. After administration, the drug catalyzes cellular oxidative stress due to overproduction of reactive oxygen species. Since oxidative stress inhibits mitochondrial protein synthesis, hair cells undergo apoptotic cell death, resulting in irreversible hearing loss (AO). We identified the following pre-treatment conditions that worsen the causal linkage between MIE and AO: HIV, malnutrition, aging, noise, smoking, and alcohol use. The KEs are: (1) nephrotoxicity, pre-existing hearing loss, and hypoalbuminemia that catalyzes AG accumulation; (2) immunodeficiency and antioxidant deficiency that trigger oxidative stress pathways; and (3) co-administration of mitochondrial toxic drugs that hinder mitochondrial protein synthesis, causing apoptosis. This AOP clearly warrants the development of personalized interventions for patients undergoing MDR-TB treatment. Such interventions (i.e., choosing less ototoxic drugs, scheduling frequent monitoring, modifying nutritional status, avoiding poly-pharmacy) will be required to limit the burden of AG ototoxicity.

Clinical Pharmacology in HIV Therapy

The success of combination antiretroviral therapy in the treatment of HIV-1-positive individuals has shifted clinical attention toward combination antiretroviral drug regimens that optimize tolerability, long-term safety, and durable efficacy. Wherever patients have access to treatment, morbidity and mortality are increasingly driven by non-HIV-associated comorbidities, which may be observed earlier than in age-matched controls and despite the best available combination antiretroviral therapy. Similarly, HIV-1-positive individuals are now diagnosed and treated earlier with anticipated lifelong therapy. The contribution of specific antiretroviral agents to long-term morbidity and mortality is dependent on the pharmacologic characteristics of these agents, and it is increasingly important in this context.

Real-life study of dual therapy based on dolutegravir and ritonavir-boosted darunavir in HIV-1-infected treatment-experienced patients

BACKGROUND

Dual therapy based on dolutegravir and ritonavir-boosted darunavir (DTG/DRV/r) is a combination of well-known drugs with a high genetic barrier to HIV resistance.

METHOD

A retrospective analysis of all HIV-1 infected treatment-experienced patients who switched to DTG/DRV/r from May 2014 till March 2017 in 4 Polish centres-results of a 48-week treatment.

RESULTS

The study group consisted of 59 men and 17 women. Median baseline parameters were: age- 42.7 years, CD4 cells count- 560.5 cells/μl, CD4 cells nadir- 150 cells/μl, number of prior antiretroviral regimens- 3. The introduction of dual therapy was primarily due to virologic failure (30 patients), adverse events on previous regimens (17 patients) and therapy simplification (27 patients). At week 48 the treatment was continued in 70/76 of patients and the median CD4 cells count increased from 560.5 to 641.0 cells/μl. The therapy was discontinued in six patients (1 -virologic failure, 1 -decrease of estimated glomerular filtration rate (eGFR), 1 -myalgia, 3 -lost to follow-up). At week 48 six patients had detectable viremia, but only in one patient viremia was higher than 200 copies/ml. At week 48 the level of serum total cholesterol of the investigated subjects was statistically significantly higher than at the moment of dual therapy introduction (185.8 mg/dl vs. 174.8 mg/dl- p<0.05). However, in patients previously not treated with TDF, there were no changes in lipid parameters during therapy. Proteinuria was observed in 13.2% of patients before the switch to dual therapy and in 7.1% of patients at week 48.

CONCLUSIONS

The investigated dual therapy was effective and safe. The observed increase in lipid parameters only concerned the patients who had used a TDF-based regimen prior to analysed dual treatment.

Incidence and predictors of tenofovir disoproxil fumarate-induced renal impairment in HIV infected Nigerian patients

Introduction

The use of tenofovir disoproxil fumarate (TDF) in the treatment of HIV infection has been associated with renal dysfunction. In Nigeria, data on the incidence and risk factors of TDF nephrotoxicity is sparse. We determined the cumulative incidence of and risk factors for TDF-induced renal impairment in HIV-infected individuals accessing care at the antiretroviral therapy (ART) clinic of Jos University Teaching Hospital, Nigeria.

Methods

This retrospective cohort analysis included patients aged ≥16 years that initiated ART between January 2008 and December 2011. Renal impairment, defined as glomerular filtration rate GFR <60 mL/min/1.73 sqm using the Modification of Diet in Renal Disease (MDRD) equation was assessed at baseline and at 48 weeks on ART. Logistic regression was performed to determine factors associated with incident renal impairment.

Results

The mean age was 39±9 years, and 67.1% were female. The cumulative incidence of renal impairment among the TDF-exposed and TDF-unexposed groups was 4.6% and 2.3% respectively (p<0.001). TDF exposure was significantly associated with renal impairment [OR=2.0, 95%CI=(1.48-2.89), p<0.001] in bivariate analysis. In multivariate analysis, older age (aOR=1.06, 95%CI=(1.05-1.08), p<0.001), TDF exposure [aOR=1.85, 95%CI=(1.31-2.60), p<0.001] and co-morbidities [aOR=2.71, 95%CI=(1.72-4.25), p<0.001] were significantly associated with renal impairment.

Conclusion

TDF exposure, aging and comorbidities were predictors of renal toxicity among HIV positive patients. Regular monitoring of renal function in such high-risk individuals is recommended.

Dual therapy based on raltegravir and boosted protease inhibitors - the experience of Polish centers

INTRODUCTION

The aim of the study was to present the experience of Polish centers regarding dual therapy based on the integrase inhibitor raltegravir (RAL) and ritonavir-boosted protease inhibitors (PI/r) for treating treatment-naïve and -experienced HIV-infected patients.

MATERIAL AND METHODS

The paper concerns a retrospective multicenter study. The medical databases of six main Polish HIV centers from January 2009 to December 2014 were analyzed for the use of combined antiretroviral treatment consisting of RAL + PI/r. This study included 126 HIV-infected patients receiving RAL + PI/r therapy, of whom 17 patients were treatment-naive and 109 patients were treatment-experienced.

RESULTS

In treatment-experienced patients, the most common reasons for the introduction of a RAL + PI/r regimen were virologic failure and impaired renal function (45 of 109 patients). In the treatment-naïve group kidney disease was the cause of the RAL + PI/r regimen in 3 of 17 participants. In treatment-experienced patients, 80% of individuals still were on RAL + PI/r treatment after 12 months, 65% after 24 months and 53% of subjects after 60 months. In both groups, the simplification of the antiretroviral regimen was the most common reason for discontinuation of RAL + PI/r based therapy.

CONCLUSIONS

In antiretroviral-experienced patients the dual therapy based on RAL + PI/s is safe and effective. In antiretroviral-naïve patients the RAL + PI/r regimen is rarely used in Poland.

Renal manifestations of HIV during the antiretroviral era in South Africa: a systematic scoping review

BACKGROUND

It is estimated that 650,000 patients may develop human immunodeficiency virus (HIV)-related renal disease in South Africa. South Africa has recently adopted WHO policy, stipulating that all HIV-infected patients have access to antiretroviral treatment (ART) irrespective of CD4 cell count.

METHODS

We searched Google Scholar, PubMed, Medline, Cochrane Library, Worldcat.org and EBSCO host databases from July 2015 to December 2015. Eligibility criteria included articles pertaining to renal manifestations of HIV in South Africa from 2004 to 2015 in adult patients (≥ 18 years). We independently reviewed the articles for quality. Thematic content analysis was performed to identify patterns of renal manifestations from the included studies. The risk of bias (e.g. internal validity) in the included studies was evaluated using the mixed methods appraisal tool.

RESULTS

Eleven out 21 studies were eligible for data extraction. The prevalence of urine abnormalities on urine dipsticks was high but had poor sensitivity and specificity for detecting renal impairment. Normal renal function occurred in 28.4 to 79% of patients, mild renal impairment occurred in 19 to 57.1% and moderate renal impairment in 2 to 14.4%. Severe renal impairment occurred in 1.3% of patients. Both the Cockcroft-Gault equation (after correcting for bias) and the 4-variable Modification of Diet in Renal Disease equation (without the ethnicity factor for African Americans) have been validated for the estimation of glomerular filtration rate (eGFR) in Black South Africans. HIV-associated nephropathy was the most prevalent histology seen (57.2%). Older age, a lower CD4 count, a low haemoglobin and a detectable viral load were associated with renal impairment. Renal function improved in the first year of commencing ART as evidenced by the regression of proteinuria and the increase in eGFR.

CONCLUSION

The findings of the review have implications to the recently adopted 'test and treat' approach to HIV prevention and management.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42016039270.

Brief Report: Cumulative Tenofovir Disoproxil Fumarate Exposure is Associated With Biomarkers of Tubular Injury and Fibrosis in HIV-Infected Men

Tenofovir disoproxil fumarate (TDF) can cause kidney damage, but current clinical tests are insensitive for detecting toxicity. Among 884 HIV-infected men enrolled in the Multicenter AIDS Cohort Study, we measured urine biomarkers specific for tubular damage (interleukin-18, kidney injury molecule-1, procollagen type III N-terminal propeptide) and albuminuria. In adjusted analyses, each year of TDF exposure was independently associated with 3.3% higher interleukin-18 (95% CI: 0.8% to 5.8%), 3.4% higher kidney injury molecule-1 (1.1% to 5.7%), and 3.1% higher procollagen type III N-terminal propeptide (0.8% to 5.5%), but not with albuminuria (2.8%; -0.6% to 6.2%). Biomarkers of tubular damage may be more sensitive than albuminuria for detecting toxicity from TDF and other medications.

Changes in estimated glomerular filtration rate over time in South African HIV-1-infected patients receiving tenofovir: a retrospective cohort study

Introduction: Tenofovir has been associated with decline in kidney function, but in patients with low baseline kidney function, improvements over time have been reported. Additionally, the magnitude and trajectory of estimated glomerular filtration rate (eGFR) changes may differ according to how eGFR is calculated. We described changes in eGFR over time, and the incidence of, and risk factors for, kidney toxicity, in a South African cohort.

Methods: We included antiretroviral-naïve patients ≥16 years old who started tenofovir-containing antiretroviral therapy (ART) between 2002 and 2013. We calculated eGFR using the Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), and Cockcroft-Gault equations. We described changes in eGFR from ART initiation using linear mixed effects regression. We described the incidence of eGFR <30 mL/min on treatment, and identified associations with low eGFR using Cox regression.

Results: We included 15156 patients with median age of 35.4 years (IQR 29.9–42.0), median CD4 cell count of 168 cells/µL (IQR 83–243), and median eGFR (MDRD) of 98.6 mL/min (IQR 84.4–115.6). Median duration of follow up on tenofovir was 12.9 months (IQR 5.1–23.3).

Amongst those with a baseline and subsequent eGFR  available, mean eGFR change from baseline at 12 months was −4.4 mL/min (95% CI −4.9 to −4.0), −2.3 (−2.5 to −2.1), and 0.6 (0.04 to 1.2) in those with baseline eGFR ≥90 mL/min; and 11.9 mL/min (11.0 to 12.7), 14.6 (13.5 to 15.7), and 11.0 (10.3 to 11.7) in those with baseline eGFR <90 mL/min, according to the MDRD, CKD-EPI (n = 11 112), and Cockcroft-Gault (n = 9 283) equations, respectively.

Overall, 292 (1.9%) patients developed eGFR <30 mL/min. Significant associations with low eGFR included older age, baseline eGFR <60 mL/min, CD4 count <200 cells/µL, body weight <60 kg, and concomitant protease inhibitor use.

Conclusions: Patients on tenofovir with baseline eGFR ≥90 mL/min experienced small but significant declines in eGFR over time when eGFR was estimated using the MDRD or CKD-EPI equations. However, eGFR increased in patients with eGFR <90 mL/min, regardless of which estimating equation was used. Decreases to below 30 mL/min were uncommon. In settings with limited access to laboratory testing, monitoring guidelines should consider focusing on higher risk patients.

Evaluating the association of single-nucleotide polymorphisms with tenofovir exposure in a diverse prospective cohort of women living with HIV

Higher exposure to tenofovir (TFV) increases the risk for kidney function decline, but the impact of genetic factors on TFV exposure is largely unknown. We investigated whether single-nucleotide polymorphisms (SNPs, n=211) in 12 genes are potentially involved in TFV exposure. Participants (n=91) from the Women's Interagency HIV Study, underwent a 24 h intensive pharmacokinetic sampling of TFV after witnessed dose and TFV area under the time-concentration curves (AUCs) were calculated for each participant. SNPs were assayed using a combination of array genotyping and Sanger sequencing. Linear regression models were applied to logarithmically transformed AUC. Those SNPs that met an a priori threshold of P<0.001 were considered statistically associated with TFV AUC. ABCG2 SNP rs2231142 was associated with TFV AUC with rare allele carriers displaying 1.51-fold increase in TFV AUC (95% confidence interval: 1.26, 1.81; P=1.7 × 10^-5). We present evidence of a moderately strong effect of the rs2231142 SNP in ABCG2 on a 24 h TFV AUC.

Antiretroviral Treatment Efficacy and Safety in Older HIV-Infected Adults

Highly active antiretroviral therapy (ART) and its widespread availability have revolutionized the landscape of HIV care and patient outcomes, transforming infection with HIV into a manageable chronic condition rather than a life-limiting disease. This transformation has created an older patient demographic. The effect that older age has on the outcomes of ART is not completely understood. Limited data are available in older individuals due to underrepresentation in clinical trials. To better understand this relationship, we conducted a literature search to assess the impact of older age on the outcomes of ART in the older HIV-infected population, including immunologic and virologic outcomes, mortality, disease progression, toxicity of ART, and pharmacokinetic considerations. In addition, package inserts of antiretroviral (ARV) medications were reviewed for efficacy, safety, and pharmacokinetic information pertaining to the older population. Most studies in older adults (50 yrs or older) demonstrated slower and blunted CD4 immune recovery but better virologic suppression in response to ART. Higher rates of mortality and faster disease progression have been observed in adults 50 years and older, particularly during the first year after ART initiation. HIV-infected patients aged 50 years and older appear to be at greater risk for certain ART-associated toxicities including nephrotoxicity, decline in bone mineral density and bone fracture, symptomatic peripheral neuropathy, and cardiovascular disease including myocardial infarction. The available literature suggests that clinicians should consider avoiding agents such as tenofovir disoproxil fumarate (TDF) in older patients with risk factors for renal impairment and/or osteoporosis. If TDF is used in patients aged 50 years or older, more frequent monitoring should be considered. Older age was a significant predictor for higher atazanavir exposure and higher lopinavir trough concentration at 24 weeks. The clinical implications of these findings are unknown. It is imperative that future development of novel ARV drug therapies includes a greater proportion of older subjects in clinical trials.

Key toxicity issues with the WHO-recommended first-line antiretroviral therapy regimen

INTRODUCTION

WHO recommends tenofovir, efavirenz, and lamivudine or emtricitabine for first-line antiretroviral therapy (ART) in adults, which replaced more toxic regimens using stavudine, zidovudine or nevirapine. Areas covered: We searched Pubmed to identify observational studies and randomized controlled trials reporting toxicity of these antiretrovirals published between 2011 and 2016, and hand-searched abstracts presented at major HIV conferences in 2015 and 2016, focusing on data from sub-Saharan Africa. Tenofovir's nephrotoxicity manifests as mild renal tubular dysfunction (common and of uncertain clinical significance), acute kidney injury (rare), and chronic declining glomerular filtration rate (common). African studies, which include high proportions of patients with renal dysfunction from opportunistic diseases, report population improvement in renal function after starting tenofovir-based ART. Tenofovir modestly decreases bone mineral density, and there is emerging data that this increases fracture risk. Efavirenz commonly causes early self-limiting neuropsychiatric toxicity and hypersensitivity rashes. Recent studies have highlighted its long-term neuropsychiatric effects, notably suicidality and neurocognitive impairment, and metabolic toxicities (dyslipidemia, dysglycemia, and lipoatrophy). We point out the challenges clinicians face in the recognition and attribution of adverse drug reactions. Expert commentary: Tenofovir and efavirenz are generally well tolerated, but both are associated with potentially serious toxicities. Pharmacovigilance systems in resource-limited settings with high HIV burden should be strengthened.

Higher tenofovir exposure is associated with longitudinal declines in kidney function in women living with HIV

OBJECTIVE

Tenofovir disoproxil fumarate is a commonly used antiretroviral drug, but risk factors for tenofovir (TFV)-associated kidney disease are not fully understood. We used intensive pharmacokinetic studies in a cohort of HIV-infected women on TFV-based therapy to study the relationship between TFV exposure and subsequent kidney function.

DESIGN

This is a nested study within the Women's Interagency HIV Study, a multicenter, prospective cohort of HIV-infected women. Participants on TFV-based therapy underwent 24-h intensive pharmacokinetic sampling after witnessed dose. Kidney function was measured over the succeeding 7 years by serum creatinine [estimated glomerular filtration rate calculated by serum creatinine (eGFRcr)].

METHODS

Multivariable linear mixed models evaluated the relationship of baseline TFV area under the-time concentration curves (AUCs) with subsequent changes in kidney function. Covariates included age, diabetes, hypertension, race, BMI, ritonavir use, duration of TFV exposure, current CD4 cell count, and HIV viral load.

RESULTS

Of the 105 participants, persons within the highest baseline TFV AUC tertile had significantly lower eGFRcr compared with those in the lowest tertile (mean ± standard error: 80 ± 4.3 vs. 104 ± 2.5 ml/min per 1.73 m, P < 0.0001). By year 7, this difference widened (72 ± 4.9 vs. 105 ± 2.9, P < 0.0001). After multivariable adjustment, TFV AUC in the highest tertile remained associated with lower eGFRcr relative to values in the lowest tertile at both baseline (-15 ml/min per 1.73 m, P = 0.0047) and year 7 (-23 ml/min per 1.73 m, P = 0.0002).

CONCLUSION

Through intensive TFV pharmacokinetic sampling, we found a strong association between greater TFV exposure and subsequent decline in kidney function. Variations in TFV drug exposure may partially account for subsequent nephrotoxicity in persons infected with HIV.

The Incidence and Clinical Characteristics of Acute Serum Creatinine Elevation more than 1.5 mg/dL among the Patients Treated with Tenofovir/Emtricitabine-containing HAART Regimens

Background

The combination of tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) has been the first choice nucleoside reverse transcriptase inhibitor (NRTI) according to many reliable antiretroviral treatment (ART) guidelines because of its high efficacy. However, TDF-related renal toxicity reported in Western countries is a challenging issue regarding clinical use. We conducted this study to evaluate the incidence and characteristics of an acute increase in serum creatinine (Cr) level > 1.5 mg/dL among TDF/FTC-based highly active antiretroviral treatment (HAART)-treated patients.

Materials and Methods

We retrospectively reviewed the medical records of 205 HIV-infected patients treated with TDF/FTC-containing regimens between 1 February 2010 and 30 April 2014. Three groups of TDF/FTC + ritonavir-boosted protease inhibitor (PI/r), TDF/FTC + non-nucleoside reverse transcriptase inhibitor (NNRTI), and TDF/FTC + integrase strand transfer inhibitor (INSTI), and three PI/r subgroups of TDF/FTC + lopinavir (LPV)/r, TDF/FTC + atazanavir (ATV)/r, TDF/FTC + darunavir (DRV)/r were evaluated.

Results

A total 136 patients (91 in the TDF/FTC + PI/r group, 20 in the TDF/FTC + NNRTI group and 25 in the TDF/FTC + INSTI group) were included in the statistical analysis. Four cases (4.9%; all in the TDF/FTC + PI/r group) among 136 patients showed an acute increase in serum Cr more than 1.5 mg/dL, so the overall incidence was 2.8 cases per 100 patient-years. One case was a patient treated with TDF/FTC + LPV/r, and the others were treated with TDF/FTC + ATV/r. No case of an acute increase in serum Cr was observed in the TDF/FTC + DRV/r group. The incidence of serum Cr increase more than 1.5 mg/dL in TDF/FTC + PI/r group was 4.0 cases per 100 patient-years.

Conclusion

Although only a small number of patients were evaluated retrospectively from a single center, the TDF/FTC + PI/r regimen may have been related with relatively higher tendency of increment of serum Cr level. These findings reinforce the importance of close follow-ups of HIV-infected patients treated with the TDF/FTC + PI/r regimens.

Improvement in renal function and bone mineral density after a switch from tenofovir/emtricitabine plus ritonavir-boosted protease inhibitor to raltegravir plus nevirapine: a pilot study

BACKGROUND

The antiretroviral regimens including tenofovir and a ritonavir-boosted protease inhibitor (r/PI) have been associated with a reduced bone mineral density (BMD), increased bone turnover markers and renal tubular dysfunction.

METHODS

An observational, prospective study was performed including HIV-1-infected, virologically suppressed patients treated with tenofovir/emtricitabine plus an r/PI for at least 12 months who switched to raltegravir plus nevirapine. The primary end point was changes after 48 weeks in estimated glomerular filtration rate (eGFR), prevalence of tubular dysfunction, BMD and concentration of two serum markers of bone turnover: collagen type-1 cross-linked C-telopeptide (CTX) and bone-specific alkaline phosphatase (BAP).

RESULTS

A total of 46 patients were enrolled: 78% were male, 96% were Caucasian, the mean age was 45 years and the mean CD4(+) T-lymphocyte count was 681 cells/mm(3). A renal impairment was present in 72% of patients and was the main reason for the switch. After 48 weeks, prevalence of proximal tubular dysfunction decreased significantly (-72%; P<0.001), whereas the mean value of eGFR did not change significantly. At the same time, after 48 weeks a significant increase in both lumbar spine and total hip BMD, T-score and Z-score was reported (+11.5% in lumbar spine T-score; P<0.001), and there was a significant reduction in both CTX and BAP mean serum concentrations (-15% and -13%, respectively; P<0.001). Two (4.3%) patients had virological failure due to suboptimal adherence and one (2.2%) subject discontinued treatment due to a skin rash.

CONCLUSIONS

Switching virologically suppressed patients from tenofovir/emtricitabine plus one r/PI to raltegravir plus nevirapine after 48 weeks significantly improved proximal tubular function, increased BMD and reduced serum markers of bone turnover.

The role of drug transporters in the kidney: lessons from tenofovir

Tenofovir disoproxil fumarate, the prodrug of nucleotide reverse transcriptase inhibitor tenofovir, shows high efficacy and relatively low toxicity in HIV patients. However, long-term kidney toxicity is now acknowledged as a modest but significant risk for tenofovir-containing regimens, and continuous use of tenofovir in HIV therapy is currently under question by practitioners and researchers. Co-morbidities (hepatitis C, diabetes), low body weight, older age, concomitant administration of potentially nephrotoxic drugs, low CD4 count, and duration of therapy are all risk factors associated with tenofovir-associated tubular dysfunction. Tenofovir is predominantly eliminated via the proximal tubules of the kidney, therefore drug transporters expressed in renal proximal tubule cells are believed to influence tenofovir plasma concentration and toxicity in the kidney. We review here the current evidence that the actions, pharmacogenetics, and drug interactions of drug transporters are relevant factors for tenofovir-associated tubular dysfunction. The use of creatinine and novel biomarkers for kidney damage, and the role that drug transporters play in biomarker disposition, are discussed. The lessons learnt from investigating the role of transporters in tenofovir kidney elimination and toxicity can be utilized for future drug development and clinical management programs.

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.

Predictors of HIV-associated nephropathy

Renal disease accounts for significant morbidity and mortality in patients with HIV-1 infection. HIV-associated nephropathy (HIVAN) is an important cause of end stage renal disease in this population. Although multiple genetic, clinical, and laboratory characteristics such as Apolipoproetin-1 genetic polymorphism, high viral load, low CD-4 count, nephrotic range proteinuria, and increased renal echogenicity on ultrasound are predictive of HIVAN, kidney biopsy remains the gold standard to make the definitive diagnosis. Current treatment options for HIVAN include initiation of combined active antiretroviral therapy, blockade of the renin-angiotensin system, and steroids. In patients with progression of HIVAN, renal transplant should be pursued as long as their systemic HIV infection is controlled.

Antiretroviral therapy-induced changes in plasma lipids and the risk of kidney dysfunction in HIV-infected men

In the context of HIV, the initiation of effective antiretroviral therapy (ART) has been found to increase the risk of dyslipidemia in HIV-infected individuals, and dyslipidemia has been found to be a risk factor for kidney disease in the general population. Therefore, we examined changes in lipid profiles in HIV-infected men following ART initiation and the association with future kidney dysfunction. HIV-infected men from the Multicenter AIDS Cohort Study initiating ART between December 31, 1995 and September 30, 2011 with measured lipid and serum creatinine values pre-ART and post-ART were selected. The associations between changes in total cholesterol or high-density lipoprotein following ART initiation and the estimated change in glomerular filtration rate (eGFR) over time were assessed using piecewise linear mixed effects models. There were 365 HIV-infected men who contributed to the analysis. In the adjusted models, at 3 years post-ART, those with changes in total cholesterol >50 mg/dl had an average decrease in eGFR of 2.6 ml/min/1.73 m(2) per year (p<0.001) and at 5 years post-ART, the average decrease was 2.4 ml/min/1.73 m(2) per year (p=0.008). This decline contrasted with the estimates for those with changes in total cholesterol ≤ 50 mg/dl: 1.4 ml/min/1.73 m(2) decrease per year (p<0.001) and 0.1 ml/min/1.73 m(2) decrease per year (p=0.594) for the same time periods, respectively. Large decreases in high-density lipoprotein (a decline of greater than 5 mg/dl) were not associated with declines in eGFR. These results indicate that large ART-related increases in total cholesterol may be a risk factor for kidney function decline in HIV-infected men. Should these results be generalizable to the broader HIV population, monitoring cholesterol changes following the initiation of ART may be important in identifying HIV-infected persons at risk for kidney disease.

A review of cardiovascular and renal function monitoring: a consideration of older adults with HIV

The prevalence of human immunodeficiency virus (HIV) infection in older and elderly adults is significant worldwide. This population poses new challenges and opportunities in the management of HIV. In addition to the risks affecting HIV patients of all ages, including risk of opportunistic infection and medication resistance, age-related changes in physiology, higher comorbidity burdens, increased use of medications, and potential adverse drug reactions to HIV medications all factor into the care of older adults with HIV. The risk and progression of cardiovascular and renal comorbidities may be higher in the older adult HIV population and in patients taking specific HIV medications. Understanding these risks is essential when managing a new type of patient: the older adult with HIV.

96-Week results of abacavir/lamivudine versus tenofovir/emtricitabine, plus efavirenz, in antiretroviral-naive, HIV-1-infected adults: ASSERT study

BACKGROUND

Abacavir/lamivudine (ABC/3TC) and tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) are widely used as first-line antiretroviral therapies. However, there are limited data comparing the safety of these therapies with long-term use. The objective of this study was to assess the long-term safety of these commonly used first-line nucleoside/nucleotide combinations each administered with efavirenz (EFV).

METHODS

This open-label, 96-week, randomized study compared the safety (renal, bone and metabolic) and efficacy of ABC/3TC and TDF/FTC plus EFV in HLA-B*5701-negative antiretroviral-naive adults.

RESULTS

A total of 385 subjects were enrolled, and 249 (65%) subjects completed the study. The difference in changes from baseline in estimated glomerular filtration rate (calculated by the Modified Diet in Renal Disease equation) between treatment arms was not significant. There was a significant difference between the arms (P < 0.0001) for markers of tubular dysfunction (retinol-binding protein and ß-2 microglobulin) favouring ABC/3TC. Hip bone mineral density decreased from baseline in both arms, with a significantly greater decline with TDF/FTC (ABC/3TC -2.2% and TDF/FTC -3.5%; P < 0.001 at week 96). Subjects in the ABC/3TC arm had greater increases from baseline in median total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and triglycerides. Adverse events were similar between arms. The virological failure rate was low in both arms.

CONCLUSIONS

ABC/3TC and TDF/FTC in combination with EFV minimally affected estimated glomerular filtration rate over 96 weeks. TDF/FTC was associated with greater increases in tubular dysfunction and bone turnover marker levels, greater decreases in hip bone mineral density, and smaller increases in serum lipid levels.

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.

Evidence for risk stratification when monitoring for toxicities following initiation of combination antiretroviral therapy

OBJECTIVE

Laboratory monitoring is recommended during combination antiretroviral therapy (cART), but the pattern of detected abnormalities and optimal monitoring are unknown. We assessed laboratory abnormalities during initial cART in 2000-2010 across the United States.

DESIGN

Observational study in the Centers for AIDS Research Network of Integrated Clinical Systems Cohort.

METHODS

Among patients with normal results within a year prior to cART initiation, time to first significant abnormality was assessed by Kaplan-Meier curves stratified by event type, with censoring at first of regimen change, loss to follow-up, or 104 weeks. Incidence rates of first events were estimated using Poisson regression; multivariable analyses identified associated factors. Results were stratified by time (16 weeks) from therapy initiation.

RESULTS

A total of 3470 individuals contributed 3639 person-years. Median age, pre-cART CD4, and follow-up duration were 40 years, 206 cells/μl, and 51 weeks, respectively. Incidence rates for significant abnormalities (per 100 person-years) in the first 16 weeks post-cART initiation were as follows: lipid=49 [95% confidence interval (CI) 41-58]; hematologic=44 (40-49); hepatic=24 (20-27); and renal=9 (7-11), dropping substantially during weeks 17-104 of cART to lipid=23 (18-29); hematologic=5 (4-6); hepatic=6 (5-8); and renal=2 (1-3) (all P<0.05). Among patients receiving initial cART with no prior abnormality (N=1889), strongest associations for hepatic abnormalities after 16 weeks were hepatitis B and C [hazard ratio=2.3 (95% CI 1.2-4.5) and hazard ratio=3.0 (1.9-4.5), respectively]. The strongest association for renal abnormalities was hypertension [hazard ratio=2.8 (1.4-5.6)].

CONCLUSION

New abnormalities decreased after week 16 of cART. For abnormalities not present by week 16, subsequent monitoring should be guided by comorbidities.

Prevalence of renal disease within an urban HIV-infected cohort in northern Italy

BACKGROUND

Renal disease is an increasingly recognized noninfectious comorbidity associated with human immunodeficiency virus (HIV) infection.

METHODS

Our retrospective, cross-sectional study evaluated prevalence of nephropathy among HIV-infected patients followed up in our outpatient clinic during the year 2011. Renal dysfunction and chronic kidney disease (CKD) were defined as estimated glomerular filtration rate (eGFR) <90 ml/min per 1.73 m(2) and as renal damage or eGFR <60 ml/min per 1.73 m(2) over a 3-month or greater period, respectively.

RESULTS

We enrolled 894 HIV-infected patients with a mean age of 44.2 years and a mean current CD4 lymphocyte count of 508 cells/mm(3). The prevalence of renal dysfunction and CKD was 27.4 and 21.3 %, respectively. Older age, male gender, hypertension, diabetes, proteinuria, hypertriglyceridemia, lower nadir CD4 cell count, current use of tenofovir or tenofovir plus a ritonavir-boosted protease inhibitor were independently associated with renal dysfunction.

CONCLUSION

Renal dysfunction is a frequent comorbidity among HIV-infected persons and requires a careful clinical and laboratory monitoring of renal function.

Tenofovir-associated proteinuria

Proteinuria was observed in 27% of 153 patients taking tenofovir for more than 1 year. Concomitant protease inhibitor therapy and cumulative tenofovir exposure were independently associated with proteinuria in this cohort. Proteinuria was reversible in 11 of 12 patients who ceased tenofovir because of proteinuria without altering other medications. Clinicians should be aware that tenofovir can cause reversible proteinuria in patients with HIV.

Renal dysfunction in the setting of HIV/AIDS

Antiretroviral therapy has been immensely successful in reducing the incidence of opportunistic infections and death after HIV infection. This has resulted in heightened interest in noninfectious comorbidities including kidney disease. Although HIV-associated nephropathy, the most ominous kidney disease related to the direct effects of HIV, may be prevented and treated with antiretrovirals, kidney disease remains an important issue in this population. In addition to the common risk factors for kidney disease of diabetes mellitus and hypertension, HIV-infected individuals have a high prevalence of other risk factors, including hepatitis C and exposure to antiretrovirals and other medications. Therefore, the differential diagnosis is vast. Early identification (through efficient screening) and prompt treatment of kidney disease in HIV-infected individuals are critical to lead to better outcomes. This review focuses on clinical and epidemiological issues, treatment strategies (including dialysis and kidney transplantation), and recent advances among kidney disease in the HIV population.

Incidence of renal toxicity in HIV-infected, antiretroviral-naïve patients starting tenofovir/emtricitabine associated with efavirenz, atazanavir/ritonavir, or lopinavir/ritonavir

OBJECTIVES

We performed a retrospective cohort study of HIV-infected antiretroviral-naïve patients starting a first antiretroviral therapy with tenofovir/emtricitabine plus efavirenz (EFV), atazanavir/ritonavir (ATV/r), or lopinavir/ritonavir (LPV/r).

METHODS

The incidence of renal impairment or proximal tubular dysfunction was evaluated during a 12-month follow-up. Renal impairment was diagnosed by a reduced estimated glomerular filtration rate (eGFR) calculated using the Modification of Diet in Renal Disease (MDRD) formula, and tubular dysfunction was diagnosed when ≥ 2 among proteinuria, glucosuria, hypouricaemia, hypophosphataemia, and hypokalaemia, were identified.

RESULTS

A total of 235 patients were enrolled: 82 taking EFV, 78 ATV/r, and 75 LPV/r. The mean decline in eGFR after the 12-month follow-up was significantly greater in subjects treated with ATV/r (-10.4 ml/min/1.73 m(2)) than in those receiving EFV (- 5.1; p = 0.002) or LPV/r (-4.8; p = 0.003). Similarly, a significantly higher incidence of proximal tubulopathy was observed among ATV/r-treated patients (14.1%) compared with patients receiving EFV (4.9%) or LPV/r (5.3%).

CONCLUSIONS

In our retrospective study, naïve patients receiving tenofovir/emtricitabine and ATV/r for 12 months showed a significantly higher decline in eGFR and a significantly higher incidence of proximal tubulopathy than those receiving tenofovir/emtricitabine plus EFV or LPV/r, even though clinically evident renal toxicity associated with tenofovir-based treatment is a very uncommon event.

Macro CK2 accumulation in tenofovir-treated HIV patients is facilitated by CK oligomer stabilization but is not predictive for pathology

BACKGROUND

Ubiquitous mitochondrial creatine kinase (uMtCK) accumulates as macroenzyme creatine kinase type 2 (macro CK2) in the serum of HIV-infected patients under a tenofovir disoproxil fumarate (TDF)-containing antiretroviral regimen. The genesis and clinical significance of this finding is unclear.

METHODS

A prospective observational 5-year follow-up study was performed on those patients in which macro CK2 appearance was initially described ('TDF switch study' cohort). In addition, tenofovir (TFV), its prodrug TDF and its active, intracellular derivative TFV diphosphate (TDP) were tested in vitro for their effects on different key properties of uMtCK to clarify possible interactions of uMtCK with TFV compounds.

RESULTS

In just under 5 years of continuous TDF treatment, only 4/12 (33%) patients remained macro CK2-positive, whereas 8/12 (66%) originally positive patients were macro CK2-negative at the end of follow-up. Prospective clinical follow-up data indicate that macro CK2 appearance under TDF is not associated with significant cell damage or occurrence of malignancies. A trend towards grade 1 hypophosphataemia suggests subclinical proximal tubular dysfunction in macro-CK2-positive patients, although it was not associated with a significant decrease in estimated glomerular filtration rate. In vitro, TFV, TDF and TDP did not interfere with uMtCK enzyme activity as competitive inhibitors or pseudo-substrates, but TFV and TDF stabilized the native uMtCK octameric structure in dilute solutions.

CONCLUSIONS

Appearance of octameric uMtCK as macro CK2 in the serum of TDF-treated patients is suggested to result from a combination of low-level mitochondrial damage caused by subclinical renal tubular dysfunction together with possible compensatory uMtCK overexpression and a putative concomitant stabilization of uMtCK octamers by higher levels of TFV in proximal tubules.

Association of tenofovir exposure with kidney disease risk in HIV infection

OBJECTIVE

Despite widespread HAART use, HIV disease remains associated with increased risk of kidney disease. Whether tenofovir use is associated with higher risk of kidney disease is controversial.

DESIGN

We evaluated the association of cumulative and ever exposure to tenofovir on kidney outcomes in 10,841 HIV-infected patients from the Veterans Health Administration who initiated antiretroviral therapy from 1997 to 2007.

METHODS

Cox proportional hazards and marginal structural models evaluated associations between tenofovir and time to first occurrence of proteinuria (two consecutive urine dipstick measurements ≥30 mg/dl), rapid decline in kidney function (≥3 ml/min per 1.73 m annual decline), and chronic kidney disease (CKD; estimated glomerular filtration rate <60 ml/min per 1.73 m).

RESULTS

Median follow-up ranged from 3.9 years (proteinuria) to 5.5 years (CKD), during which 3400 proteinuria, 3078 rapid decline, and 533 CKD events occurred. After multivariable adjustment, each year of exposure to tenofovir was associated with 34% increased risk of proteinuria [95% confidence interval (CI) 25-45, P < 0.0001], 11% increased risk of rapid decline (3-18, P = 0.0033), and 33% increased risk of CKD (18-51, P < 0.0001). Preexisting renal risk factors did not appear to worsen the effects of tenofovir. Other antiretroviral drugs showed weaker or inconsistent associations with kidney disease events. Among those who discontinued tenofovir use, risk of kidney disease events did not appear to decrease during follow-up.

CONCLUSION

Tenofovir exposure was independently associated with increased risk for three types of kidney disease events, and did not appear to be reversible. Because subtle kidney function decline affects long-term morbidity and mortality, the balance between efficacy and probable adverse effects requires further study.