Mechanism of active renal tubular efflux of tenofovir

Switching to tenofovir alafenamide in patients with virologically suppressed chronic hepatitis B and renal or hepatic impairment: final week 96 results from an open-label, multicentre, phase 2 study

BACKGROUND

Phase 3 studies in patients with chronic hepatitis B have shown tenofovir alafenamide to have non-inferior efficacy to tenofovir disoproxil fumarate, with improved renal and bone safety. We conducted this study to evaluate the safety and efficacy of switching to tenofovir alafenamide in participants with chronic hepatitis B and renal or hepatic impairment.

METHODS

This open-label, multicentre, phase 2 study was done in eight countries or territories at 30 sites. We recruited adults (≥18 years) with chronic hepatitis B who were virally suppressed on nucleoside or nucleotide analogues and had renal impairment (part A: moderate or severe in cohort 1 [estimated glomerular filtration rate by the Cockcroft-Gault formula (eGFRCG) 15-59 mL/min] or end-stage renal disease [eGFRCG <15 mL/min] on haemodialysis in cohort 2) or hepatic impairment including decompensation (part B: Child-Turcotte-Pugh score 7-12). Participants switched to 25 mg of tenofovir alafenamide given orally once daily for 96 weeks. The primary endpoint was the proportion of participants with viral suppression (HBV DNA <20 IU/mL) at week 24 by missing-equals-failure analysis. Efficacy (full analysis set) and safety (safety analysis set) analyses included all enrolled participants who received at least one dose of the study drug. Week 96 safety was assessed, including renal and bone parameters. This trial is registered at ClinicalTrials.gov, NCT03180619, and is completed.

FINDINGS

124 participants (93 in part A [78 in cohort 1 and 15 in cohort 2] and 31 in part B) were enrolled between Aug 11, 2017, and Oct 17, 2018, and included in the full and safety analysis sets. 106 (85%) participants completed the study. There were 69 (74%) men and 24 (26%) women in part A and 21 (68%) men and ten (32%) women in part B. At week 24, 91 (97·8%, 95% CI 92·4 to 99·7) of 93 individuals in part A (76 [97·4%, 91·0 to 99·7] of 78 in cohort 1 and 15 [100·0%, 78·2 to 100·0] of 15 in cohort 2) and 31 (100·0%, 88·8 to 100·0) in part B had HBV DNA of less than 20 IU/mL. By week 96, the most common adverse event was upper respiratory tract infection, which occurred in 14 (15%) participants in part A and in six (19%) participants in part B. Serious adverse events occurred in 20 (22%) part A participants and in ten (32%) part B participants; none were related to treatment. No treatment-related deaths occurred. At week 96, median change in estimated glomerular filtration rate (Cockcroft-Gault method) was 1·0 mL/min (IQR -2·8 to 4·5) in cohort 1 and -2·4 mL/min (-11·4 to 10·7) in part B. Mean changes in spine and hip bone mineral density were 1·02% (SD 4·44) and 0·20% (3·25) in part A and -0·25% (3·91) and 0·28% (3·25) in part B.

INTERPRETATION

Tenofovir alafenamide might offer continued antiviral efficacy and a favourable safety profile for patients with renal or hepatic impairment and chronic hepatitis B switching from tenofovir disoproxil fumarate or other antivirals.

FUNDING

Gilead Sciences.

Structural basis of prostaglandin efflux by MRP4

Multidrug resistance protein 4 (MRP4) is a broadly expressed ATP-binding cassette transporter that is unique among the MRP subfamily for transporting prostanoids, a group of signaling molecules derived from unsaturated fatty acids. To better understand the basis of the substrate selectivity of MRP4, we used cryogenic-electron microscopy to determine six structures of nanodisc-reconstituted MRP4 at various stages throughout its transport cycle. Substrate-bound structures of MRP4 in complex with PGE1, PGE2 and the sulfonated-sterol DHEA-S reveal a common binding site that accommodates a diverse set of organic anions and suggest an allosteric mechanism for substrate-induced enhancement of MRP4 ATPase activity. Our structure of a catalytically compromised MRP4 mutant bound to ATP-Mg2+ is outward-occluded, a conformation previously unobserved in the MRP subfamily and consistent with an alternating-access transport mechanism. Our study provides insights into the endogenous function of this versatile efflux transporter and establishes a basis for MRP4-targeted drug design.

Pyruvate dehydrogenase is a potential mitochondrial off-target for gentamicin based on in silico predictions and in vitro inhibition studies

During the drug development process, organ toxicity leads to an estimated failure of one-third of novel chemical entities. Drug-induced toxicity is increasingly associated with mitochondrial dysfunction, but identifying the underlying molecular mechanisms remains a challenge. Computational modeling techniques have proven to be a good tool in searching for drug off-targets. Here, we aimed to identify mitochondrial off-targets of the nephrotoxic drugs tenofovir and gentamicin using different in silico approaches (KRIPO, ProBis and PDID). Dihydroorotate dehydrogenase (DHODH) and pyruvate dehydrogenase (PDH) were predicted as potential novel off-target sites for tenofovir and gentamicin, respectively. The predicted targets were evaluated in vitro, using (colorimetric) enzymatic activity measurements. Tenofovir did not inhibit DHODH activity, while gentamicin potently reduced PDH activity. In conclusion, the use of in silico methods appeared a valuable approach in predicting PDH as a mitochondrial off-target of gentamicin. Further research is required to investigate the contribution of PDH inhibition to overall renal toxicity of gentamicin.

Renal function and lipid metabolism in Japanese HIV-1-positive individuals 288 weeks after switching from tenofovir disoproxil fumarate to tenofovir alafenamide fumarate: a single-center, retrospective cohort study

BACKGROUND

Continued use of tenofovir disoproxil fumarate (TDF), an antiretroviral drug, causes renal function decline and tubular damage in individuals with HIV. While tenofovir alafenamide fumarate (TAF) may have less damaging effects, it causes weight gain and abnormal lipid metabolism.

METHODS

This single-center, retrospective cohort study used medical records from the National Hospital Organization Sendai Medical Center to investigate renal function of Japanese HIV-1-positive individuals who switched from TDF to antiretroviral therapy including TAF by 2017. The endpoints were: estimated glomerular filtration rate (eGFR), urinary β2 microglobulin (Uβ2MG), weight, and lipid metabolism parameters at 288 weeks after switching. Possible correlation between eGFR and Uβ2MG and factors affecting eGFR decline were examined.

RESULTS

Sixty patients switched from TDF to TAF and continued therapy for 288 weeks. eGFR showed a significant decline after 144 weeks, although it was controlled from the time of change until 96 weeks. In the renal impairment group, the decline was suppressed until week 288. Uβ2MG continued to decrease significantly after 48 weeks. However, the suggested correlation between eGFR and Uβ2MG disappeared when patients switched from TDF to TAF. Weight and lipid metabolic parameters increased significantly at 48 weeks and were maintained. Factors associated with decreased eGFR were: history of acquired immune deficiency syndrome (AIDS) and Uβ2MG. However, considering the odds ratio, the switch from TDF to TAF suppressed the eGFR decline in the group with a history of AIDS, and Uβ2MG had no effect on the eGFR decline.

CONCLUSIONS

Switching from TDF to TAF for the long term slows eGFR decline, decreases Uβ2MG levels, and reduces worsening of renal function. Weight gain and abnormal lipid metabolism may occur in the short term but are controllable.

The clinical impact of rifampicin-based anti-TB therapy and tenofovir alafenamide-containing ARV regimen drug Interaction in people living with HIV: Case series report

BACKGROUND

People living with HIV (PLWH) are prone to developing tuberculosis (TB). Since tenofovir alafenamide (TAF) is the recommended tenofovir (TFV) prodrug and rifampicin is a key component of TB therapy, thus complicating HIV and TB coinfection management. However, there is little data regarding the impact of this drug-drug Interaction in PLWH, which makes health care providers reluctant to prescribe them together.

METHODS

This was an observational, retrospective case series carried out at King Faisal Specialist Hospital & Research Center (KFSH&RC), Jeddah, Saudi Arabia. PLWH (≥18 years old) who received the TAF-containing ARV regimen and rifampicin-based anti-TB therapy together for ≥ 4 weeks were included. The objective of this study was to report the clinical impact of this drug-drug interaction (rifampicin + TAF-containing antiretroviral (ARV) regimen) on HIV viral load control in PLWH.

RESULTS

A total of 7 PLWH who met the inclusion criteria, 5 (71 %) out of 7, were males. All patients received dolutegravir 50 mg twice daily (DTG) plus the combination of TAF 25 mg and emtricitabine 200 mg (FTC) once daily as their ARV regimen. Four patients had suppressed viral load levels at baseline, which was maintained throughout TB treatment. Three patients had unsuppressed viral load levels at baseline and attained viral load suppression throughout the TB treatment course CONCLUSION: Overall, the TAF-containing ARV regimen maintained it's efficacy in presence of rifampicin.

Effect of P-glycoprotein and Cotreatment with Sofosbuvir on the Intestinal Permeation of Tenofovir Disoproxil Fumarate and Tenofovir Alafenamide Fumarate

PURPOSE

We aimed to compare the effects of P-glycoprotein (ABCB1) on the intestinal uptake of tenofovir disoproxil fumarate (TDF), tenofovir alafenamide fumarate (TAF), and metabolites, tenofovir isoproxil monoester (TEM) and tenofovir (TFV), and to study the molecular mechanism of drug-drug interaction (DDI) between sofosbuvir (SOF) and TDF/TAF.

METHODS

Bidirectional transport experiments in Caco-2 cells and accumulation studies in precision-cut intestinal slices prepared from the ileal segment of rodent (rPCIS) and human (hPCIS) intestines were performed.

RESULTS

TDF and TAF were extensively metabolised but TAF exhibited greater stability. ABCB1 significantly reduced the intestinal transepithelial transfer and uptake of the TFV(TDF) and TFV(TAF)-equivalents. However, TDF and TAF were absorbed more efficiently than TFV and TEM. SOF did not inhibit intestinal efflux of TDF and TAF or affect intestinal accumulation of TFV(TDF) and TFV(TAF)-equivalents but did significantly increase the proportion of absorbed TDF.

CONCLUSIONS

TDF and TAF likely produce comparable concentrations of TFV-equivalents in the portal vein and the extent of permeation is reduced by the activity of ABCB1. DDI on ABCB1 can thus potentially affect TDF and TAF absorption. SOF does not inhibit ABCB1-mediated transport of TDF and TAF but does stabilise TDF, albeit without affecting the quantity of TFV(TDF)-equivalents crossing the intestinal barrier. Our data thus suggest that reported increases in the TFV plasma concentrations in patients treated with SOF and TDF result either from a DDI between SOF and TDF that does not involve ABCB1 or from a DDI involving another drug used in combination therapy.

Pharmacogenetics of tenofovir renal toxicity in HIV-positive Southern Africans

OBJECTIVE

Renal toxicity is more common with tenofovir disoproxil fumarate (TDF) than with tenofovir alafenamide fumarate (TAF). We investigated whether polymorphisms in genes relevant to tenofovir disposition affect renal toxicity among HIV-positive Southern Africans.

METHODS

Genetic sub-study of adults randomized to initiate TAF or TDF together with dolutegravir and emtricitabine was conducted. Outcomes were changes from week 4 to 48 in the estimated glomerular filtration rate (eGFR) and from baseline to week 48 in urine retinol-binding protein and urine β2-microglobulin adjusted for urinary creatinine (uRBP/Cr and uB2M/Cr). Primary analyses prioritized 14 polymorphisms previously reported to be associated with tenofovir disposition or renal outcomes, and all polymorphisms in 14 selected genes. We also explored genome-wide associations.

RESULTS

336 participants were enrolled. Among 14 polymorphisms of primary interest, the lowest P values for change in eGFR, uRBP/Cr, and uB2M/Cr were ABCC4 rs899494 ( P  = 0.022), ABCC10 rs2125739 ( P  = 0.07), and ABCC4 rs1059751 ( P  = 0.0088); and in genes of interest, the lowest P values were ABCC4 rs4148481 ( P  = 0.0013), rs691857 ( P  = 0.00039), and PKD2 rs72659631 ( P  = 0.0011). However, none of these polymorphisms withstood correction for multiple testing. Genome-wide, the lowest P values were COL27A1 rs1687402 ( P  = 3.4 × 10 -9 ), CDH4 rs66494466 ( P  = 5.6 × 10 -8 ), and ITGA4 rs3770126 ( P  = 6.1 × 10 -7 ).

CONCLUSION

Two ABCC4 polymorphisms, rs899494 and rs1059751, were nominally associated with change in eGFR and uB2M/Cr, respectively, albeit in the opposite direction of previous reports. COL27A1 polymorphism was genome-wide significantly associated with change in eGFR.

Population pharmacokinetics of tenofovir given as either tenofovir disoproxil fumarate or tenofovir alafenamide in an African population

Tenofovir disoproxil fumarate (TDF) and tenofovir alafenamide (TAF) are prodrugs of the nucleotide analogue tenofovir, which acts intracellularly to inhibit HIV replication. Whereas TDF converts to tenofovir in plasma and may cause kidney and bone toxicity, TAF mostly converts to tenofovir intracellularly, so it can be administered at lower doses. TAF leads to lower tenofovir plasma concentrations and lower toxicity, but there are limited data on its use in Africa. We used data from 41 South African adults living with HIV from the ADVANCE trial and described, with a joint model, the population pharmacokinetics of tenofovir given as TAF or TDF. The TDF was modeled to appear in plasma as tenofovir with a simple first-order process. Instead, two parallel pathways were used for a TAF dose: an estimated 32.4% quickly appeared as tenofovir into the systemic circulation with first-order absorption, whereas the rest was sequestered intracellularly and released into the systemic circulation as tenofovir slowly. Once in plasma (from either TAF or TDF), tenofovir disposition followed two-compartment kinetics and had a clearance of 44.7 L/h (40.2-49.5), for a typical 70-kg individual. This semimechanistic model describes the population pharmacokinetics of tenofovir when dosed as either TDF or TAF in an African population living with HIV and can be used as a tool for exposure prediction in patients, and to simulate alternative regimes to inform further clinical trials.

Expanding the toolbox of metabolically stable lipid prodrug strategies

Nucleoside- and nucleotide-based therapeutics are indispensable treatment options for patients suffering from malignant and viral diseases. These agents are most commonly administered to patients as prodrugs to maximize bioavailability and efficacy. While the literature provides a practical prodrug playbook to facilitate the delivery of nucleoside and nucleotide therapeutics, small context-dependent amendments to these popular prodrug strategies can drive dramatic improvements in pharmacokinetic (PK) profiles. Herein we offer a brief overview of current prodrug strategies, as well as a case study involving the fine-tuning of lipid prodrugs of acyclic nucleoside phosphonate tenofovir (TFV), an approved nucleotide HIV reverse transcriptase inhibitor (NtRTI) and the cornerstone of combination antiretroviral therapy (cART). Installation of novel lipid terminal motifs significantly reduced fatty acid hepatic ω-oxidation while maintaining potent antiviral activity. This work contributes important insights to the expanding repertoire of lipid prodrug strategies in general, but particularly for the delivery and distribution of acyclic nucleoside phosphonates.

Risk Factors of Renal Tubular Dysfunction in Thai People Living with HIV Receiving Tenofovir Disoproxil Fumarate

Tenofovir disoproxil fumarate (TDF) associates with renal tubular dysfunction (RTD) in some people living with HIV (PLWH). We studied clinical and genetic factors associated with RTD in Thai PLWH receiving TDF. RTD was diagnosed in 13 of 65 (20%) patients. The median (interquartile range) age and CD4 cell counts were 43.8 (40.4-50.9) years and 554 (437-716) cells/mm³, respectively. The median duration of TDF use was 46.9 (31.5-54.1) months. Univariate logistic regression demonstrated body mass index (BMI), concomitant use of protease inhibitor (PI), hyperlipidemia, and homozygous C/C SNP rs1059751 of ABCC4 gene as predisposing factors of RTD. In multivariate model, concomitant use of PI [adjusted odds ratio (aOR) 11.39; 95% confidence interval (CI), 1.59- 81.56; P = 0.015], hyperlipidemia (aOR 8.59; 95% CI, 1.46-50.40; P = 0.017), and BMI (aOR 0.76; 95% CI, 0.59-0.98; P = 0.037) remained associated with RTD in patients receiving TDF. PLWH receiving TDF with the presence of these factors should be closely monitored for RTD.

Pharmacogenomics of drug transporters for antiretroviral long-acting pre-exposure prophylaxis for HIV

The use of antiretrovirals (ARVs) as oral, topical, or long-acting pre-exposure prophylaxis (PrEP) has emerged as a promising strategy for HIV prevention. Clinical trials testing Truvada® [tenofovir disoproxil fumarate (TDF)/tenofovir (TFV) and emtricitabine (FTC)] as oral or topical PrEP in African women showed mixed results in preventing HIV infections. Since oral and topical PrEP effectiveness is dependent on adequate drug delivery and availability to sites of HIV infection such as the blood and female genital tract (FGT); host biological factors such as drug transporters have been implicated as key regulators of PrEP. Drug transporter expression levels and function have been identified as critical determinants of PrEP efficacy by regulating PrEP pharmacokinetics across various cells and tissues of the blood, renal tissues, FGT mucosal tissues and other immune cells targeted by HIV. In addition, biological factors such as genetic polymorphisms and genital inflammation also influence drug transporter expression levels and functionality. In this review, drug transporters and biological factors modulating drug transporter disposition are used to explain discrepancies observed in PrEP clinical trials. This review also provides insight at a pharmacological level of how these factors further increase the susceptibility of the FGT to HIV infections, subsequently contributing to ineffective PrEP interventions in African women.

Cumulative tenofovir diphosphate exposure in persons with HIV taking single- vs. multiple-tablet regimens

BACKGROUND

We assessed cumulative antiretroviral exposure-using tenofovir diphosphate (TFV-DP) in dried blood spots (DBS)-in persons with HIV (PWH) receiving tenofovir disoproxil fumarate (TDF)-based antiretroviral therapy (ART) as single-tablet regimens (STR) or multiple-tablet regimens (MTR).

METHODS

Blood for DBS was prospectively collected in PWH on TDF during 1144 person visits (n = 523). Linear mixed-effects models, adjusted for baseline characteristics, were used to compare TFV-DP in STR versus MTR. Models adjusted for ART regimen using either anchor drug class, pharmacokinetic booster status (unboosted [u/] or boosted [b/]), or a combined STR/MTR and booster categorical variable.

RESULTS

In the anchor class-adjusted model, STR had 19% (95% confidence interval [CI]: 3%-37%; p = 0.02) higher TFV-DP concentrations than MTR. However, in the booster-adjusted model, STR was not significantly higher than MTR (estimate 5%, 95% CI: -9% to 21%; p = 0.48), although PWH on b/ART had 35% (95% CI: 16%-58%; p = 0.0001) higher TFV-DP than u/ART. In the STR/MTR-boosted variable model, when compared to u/MTR, b/STR, b/MTR, and u/STR had 25% (95% CI: 7%-47%; p = 0.005), 37% (95% CI: 17%-59%; p < 0.0001), and 7% (95% CI: -7% to 24%; p = 0.34) higher TFV-DP, respectively. Compared with b/MTR, b/STR had 9% (95% CI: -31% to 10%; p = 0.37) lower TFV-DP. In a sensitivity analysis of PWH with HIV viral load <20 copies/ml at all visits, b/STR and b/MTR had 34% (95% CI: 16%-55%; p < 0.0001) and 12% (95% CI: -2% to 27%; p = 0.09) higher TFV-DP, respectively, compared with u/MTR, while u/STR had 4% (95% CI: -15% to 8%; p = 0.50) lower TFV-DP. Compared with b/MTR, b/STR had 17% (95% CI: 2%-30%; p = 0.03) higher TFV-DP.

CONCLUSIONS

Persons with HIV on b/TDF-based ART had higher TFV-DP than u/ART, regardless of STR or MTR use. No significant differences in TFV-DP between regimens of the same boosting status (i.e., b/STR vs. b/MTR; u/STR vs. u/MTR) were observed in the full cohort. Future research should examine the clinical utility of these findings in patient-tailored ART selection.

Important roles of transporters in the pharmacokinetics of anti-viral nucleoside/nucleotide analogs

INTRODUCTION

Nucleoside analogs are an important class of antiviral agents. Due to the high hydrophilicity and limited membrane permeability of antiviral nucleoside/nucleotide analogs (AVNAs), transporters play critical roles in AVNA pharmacokinetics. Understanding the properties of these transporters is important to accelerate translational research for AVNAs.

AREAS COVERED

The roles of key transporters in the pharmacokinetics of 25 approved AVNAs were reviewed. Clinically relevant information that can be explained by the modulation of transporter functions is also highlighted.

EXPERT OPINION

Although the roles of transporters in the intestinal absorption and renal excretion of AVNAs have been well identified, more research is warranted to understand their roles in the distribution of AVNAs, especially to immune privileged compartments where treatment of viral infection is challenging. P-gp, MRP4, BCRP, and nucleoside transporters have shown extensive impacts in the disposition of AVNAs. It is highly recommended that the role of transporters should be investigated during the development of novel AVNAs. Clinically, co-administered inhibitors and genetic polymorphism of transporters are the two most frequently reported factors altering AVNA pharmacokinetics. Physiopathology conditions also regulate transporter activities, while their effects on pharmacokinetics need further exploration. Pharmacokinetic models could be useful for elucidating these complicated factors in clinical settings.

Drug-Induced Acute Kidney Injury

Medications are a common cause of AKI especially for patients admitted to hospital wards and the intensive care unit. Although drug-related kidney injury occurs through different mechanisms, this review will focus on three specific types of tubulointerstitial injury. Direct acute tubular injury develops from several medications, which are toxic to various cellular functions. Their excretory pathways through the proximal tubules contribute further to AKI. Drug-induced AKI may also develop through induction of inflammation within the tubulointerstitium. Medications can elicit a T cell-mediated immune response that promotes the development of acute interstitial nephritis leading to AKI. Although less common, a third pathway to kidney injury results from the insolubility of drugs in the urine leading to their precipitation as crystals within distal tubular lumens, causing a crystalline-related AKI. Intratubular obstruction, direct tubular injury, and localized inflammation lead to AKI. Clinicians should be familiar with the pathogenesis and clinical-pathologic manifestations of these forms of kidney injury. Prevention and treatment of AKI relies on understanding the pathogenesis and judiciously using these agents in settings where AKI risk is high.

Comparison of Tenofovir Alafenamide and Entecavir Therapy in Patients with Chronic Hepatitis B Initially Treated with Tenofovir Disoproxil: A Retrospective Observational Survey

Background: In chronic hepatitis B patients with or exposed to the risk of osteoporosis or renal dysfunction, switching from tenofovir disoproxil fumarate (TDF) to tenofovir alafenamide fumarate (TAF) or entecavir (ETV) may be the right choice. Objectives: This study aimed to present real-life data in terms of the efficacy and safety of a TAF/ETV treatment change while receiving TDF. Methods: This retrospective study was conducted on 344 adult patients from 10 centers. The data of patients who had changed to ETV (n = 107) and TAF (n = 237) while receiving TDF were analyzed. The data collected at 0 and 6 months of treatment were analyzed. The virological response was assessed based on undetected hepatitis B virus (HBV) DNA. Serum alanine aminotransferase (ALT) values were used to evaluate the biochemical response. For renal function, serum creatinine and phosphorus, as well as estimated glomerular filtration rate (eGFR), were recorded. Moreover, lumbar spine and hip T-scores along with the serum lipid profile were evaluated. Results: The mean age of patients was 41.14 ± 13.46 years, and 224 (65.1%) of the participants were male. The treatment arms were not significantly different in terms of demographic characteristics, comorbid diseases, infection duration, family history of HBV infection, blood platelet count, serum biomarkers, such as ALT, phosphorus, creatinine, total bilirubin, albumin, lipid profile, and HBV DNA levels at the beginning. No statistically significant difference was found between the proportion of undetectable HBV DNA of the two treatment groups after 6 months (P = 0.221). The ALT normalization in the ETV and TAF groups at the sixth month compared to the baseline levels was not significantly different (P = 0.853, P = 0.330, respectively). There was no statistically significant difference between the two treatment arms regarding changes in eGFR, creatinine, phosphorus, hip, and spine T-scores from baseline to 6 months (P = 0.296, P = 0.78, P = 0.141, P = 0.832, P = 0.947, respectively). In those who switched to TAF or ETV, low-density lipoproteins cholesterol were observed to be significantly higher after 6 months compared to baseline values (P = 0.002, P = 0.049, respectively). The TC increased significantly in the TAF group (P = 0.035). Conclusions: Our study showed that switching to ETV and TAF sustained the viral suppression and biochemical response achieved by TDF therapy. The treatment switch to TAF of ETV can control renal dysfunction and reduce bone mineral density caused by TDF.

Renal function in Japanese HIV-1-positive patients who switch to tenofovir alafenamide fumarate after long-term tenofovir disoproxil fumarate: a single-center observational study

BACKGROUND

Tenofovir disoproxil fumarate (TDF) has a strong antiviral effect, but TDF is known to cause renal dysfunction. Therefore, we are investigating preventing renal dysfunction by replacing TDF with tenofovir alafenamide fumarate (TAF), which is known to be relatively safe to the kidneys. However, the changes in renal function under long-term use of TAF are not known. In this study, we evaluated renal function in Japanese HIV-1-positive patients switching to TAF after long-term treatment with TDF.

METHODS

A single-center observational study was conducted in Japanese HIV-1-positive patients. TDF was switched to TAF after at least 48 weeks of the treatment so we could evaluate the long-term use of TDF. The primary endpoint was the estimated glomerular filtration rate (eGFR) at 144 weeks of TAF administration. In addition, we predicted the factors that would lead to changes in eGFR after long-term use of TAF.

RESULTS

Of the 125 HIV-1-positive patients who were prescribed TAF at our hospital during the study period, 70 fulfilled the study criteria. The eGFR at the time of switching from TDF to TAF was 81.4 ± 21.1 mL/min/1.73 m2. eGFR improved significantly after 12 weeks of taking TAF but significantly decreased at 96 and 144 weeks. The factors significantly correlated with the decrease in eGFR at 144 weeks on TAF were eGFR and weight at the start of TAF.

CONCLUSIONS

In this study, it was confirmed that switching to TAF was effective for Japanese HIV-1-positive patients who had been taking TDF for a long period of time and had a reduced eGFR. It was also found that the transition status depended on the eGFR and weight at the time of switch. Since HIV-1-positive patients in Japan are expected to continue taking TAF for a long time, renal function and body weight should be carefully monitored.

Discovery of Modified Amidate (ProTide) Prodrugs of Tenofovir with Enhanced Antiviral Properties

This study describes the discovery of novel prodrugs bearing tyrosine derivatives instead of the phenol moiety present in FDA-approved tenofovir alafenamide fumarate (TAF). The synthesis was optimized to afford diastereomeric mixtures of novel prodrugs in one pot (yields up to 86%), and the epimers were resolved using a chiral HPLC column into fast-eluting and slow-eluting epimers. In human lymphocytes, the most efficient tyrosine-based prodrug reached a single-digit picomolar EC₅₀ value against HIV-1 and nearly 300-fold higher selectivity index (SI) compared to TAF. In human hepatocytes, the most efficient prodrugs exhibited subnanomolar EC₅₀ values for HBV and up to 26-fold higher SI compared to TAF. Metabolic studies demonstrated markedly higher cellular uptake of the prodrugs and substantially higher levels of released tenofovir inside the cells compared to TAF. These promising results provide a strong foundation for further evaluation of the reported prodrugs and their potential utility in the development of highly potent antivirals.

Pharmacokinetics of Tenofovir Alafenamide Fumarate and Tenofovir in the Chinese People: Effects of Non-Genetic Factors and Genetic Variations

Background

Tenofovir alafenamide fumarate (TAF) was approved for HBV treatment in China in 2018. Despite higher antiviral efficacy and less impact on renal function and bone mineral density, the pharmacokinetic profiles of TAF are highly variable. The objectives of this study were to investigate the pharmacokinetics of TAF in the Chinese population and explore the associations between TAF and genetic polymorphisms and non-genetic factors.

Patients and Methods

A total of 64 healthy Chinese subjects aged 18~65 years old were planned to enroll. According to the dietary intake status, the subjects were divided into two groups (n = 32 per group). The concentrations of TAF and tenofovir were measured by HPLC-MS/MS, and the single-nucleotide polymorphisms were analyzed by MALDI-TOF MS.

Results

All the enrolled participants (18–35 years) completed the clinical trial study. Similar to the results reported in other ethnic populations, the pharmacokinetic profiles of TAF and tenofovir were highly variable in the Chinese people, and the HFHC diet can significantly increase the systemic exposure of TAF. We determined both HFHC diet and rs7311358 (SLCO1B3) genotypes were independently associated with TAF AUC_0-t, while HFHC diet, age and rs3740066 (ABCC2) variants were predictive of t_1/2 of tenofovir (P < 0.05). The subjects with the AA genotype in rs7311358 had significantly higher TAF AUC_0-t values (1.15 times) than those with a G allele, and the t_1/2 of tenofovir in the rs3740066 TT genotype group was 1.23 times longer than that of CC genotype group. Furthermore, there was a trend of higher TAF AUC and shorter tenofovir t_1/2 for the rs2032582 (ABCB1) T allele and rs3742106 (ABCC4) CC variant, respectively, although not statistically significant in the multiple linear regression analysis.

Conclusion

This study provided new evidence to suggest a critical link between both genetic and non-genetic factors and TAF pharmacokinetics in the Chinese people.

ABCC4 single-nucleotide polymorphisms as markers of tenofovir disoproxil fumarate-induced kidney impairment

Recently, the use of antiretroviral drug tenofovir disoproxil fumarate (TDF) is increased, thanks to the new co-formulation with doravirine, the availability of booster-free regimens, and its advantageous lipid-lowering effect. The aim of our study was to identify genetic markers that contribute to assess the risk of TDF-related renal toxicity. We have retrospectively investigated, in 179 HIV positive patients treated with TDF, the association between the main variants in ABCC2, ABCC4, and ABCC10 genes and four safety endpoints, three clinically relevant as renal outcomes and a higher tenofovir plasma concentration. In patients with an annual eGFR decline >5 mL/min/1.73 m² a difference in genotype frequencies was observed for ABCC10 c.1875 + 526 G>A (3 subjects AA vs. 44 GG + GA, p = 0.045). In patients with an eGFR decrement >25%, plus a decline in GFR category and TDF discontinuation, a difference was observed for ABCC4 c.*38T>G (35 subjects TG + GG vs. 18 TT, p = 0.052). At univariate analysis OR was 1.39 [(95% CI 1.00-1.96) p = 0.054] and at multivariate analysis OR was 1.49 [(95% CI 1.00-2.22) p = 0.049]. The stronger associations were found between the tenofovir accumulation and ABCC4 c.*38T>G and c.3348G>A: the percentage of these patients was higher in the TG + GG (p = 0.011) and in the AA (p = 0.004) genotype, respectively. The logistic regression analysis confirmed these significant relationships. No significant association was observed in patients with eGFR < 60 mL/min/1.73m² and with the studied ABCC2 polymorphisms. Our results show a major role for a combined determination of ABCC4/ABCC10 variants as an indicator of tenofovir toxicity in the clinical practice.

ω-Functionalized Lipid Prodrugs of HIV NtRTI Tenofovir with Enhanced Pharmacokinetic Properties

Tenofovir (TFV) is the cornerstone nucleotide reverse transcriptase inhibitor (NtRTI) in many combination antiretroviral therapies prescribed to patients living with HIV/AIDS. Due to poor cell permeability and oral bioavailability, TFV is administered as one of two FDA-approved prodrugs, both of which metabolize prematurely in the liver and/or plasma. This premature prodrug processing depletes significant fractions of each oral dose and causes toxicity in kidney, bone, and liver with chronic administration. Although TFV exalidex (TXL), a phospholipid-derived prodrug of TFV, was designed to address this issue, clinical pharmacokinetic studies indicated substantial hepatic extraction, redirecting clinical development of TXL toward HBV. To circumvent this metabolic liability, we synthesized and evaluated ω-functionalized TXL analogues with dramatically improved hepatic stability. This effort led to the identification of compounds 21 and 23, which exhibited substantially longer t1/2 values than TXL in human liver microsomes, potent anti-HIV activity in vitro, and enhanced pharmacokinetic properties in vivo.

Para-aminosalicylic acid significantly reduced tenofovir exposure in human subjects: Mismatched findings from in vitro to in vivo translational research

AIMS

Tenofovir and para-aminosalicylic acid (PAS) may be coprescribed to treat patients with concomitant infections of human immunodeficiency virus and Mycobacterium tuberculosis bacteria. Both drugs are known to have remarkable renal uptake transporter-mediated clearance. Owing to the lack of clinical studies on drug-drug interaction between the 2 drugs, we conducted a translational clinical study to investigate the effect of PAS on tenofovir pharmacokinetics (PK).

METHODS

Initially, we studied in vitro renal uptake transporter-mediated drug-drug interactions using stably transfected cells with human organic anion transporters (OAT1 and OAT3). Later, we estimated clinical drug interactions using static and physiologically based PK modelling. Finally, we investigated the effects of PAS-calcium formulation (PAS-Ca) on tenofovir disoproxil fumarate PK in healthy male Korean subjects.

RESULTS

PAS inhibited OAT1- and OAT3-mediated tenofovir uptake in vitro. The physiologically based PK drug-drug interaction model suggested a 1.26-fold increase in tenofovir peak plasma concentration when coadministered with PAS. By contrast, an open-label, randomized, crossover clinical trial evaluating the effects of PAS-Ca on tenofovir PK showed significantly altered geometric mean ratio (90% confidence intervals) of maximum plasma concentration (C_max ) and area under the curve (AUC_0-inf ) by 0.33 (0.28-0.38) and 0.29 (0.26-0.33), respectively.

CONCLUSION

Our study findings suggest that the PAS-Ca formulation significantly reduced systemic exposure to tenofovir through an unexplained mechanism, which was contrary to the initial prediction. Caution should be exercised while predicting in vivo PK profiles from in vitro data, particularly when there are potential confounders such as pharmaceutical interactions.

Lopinavir and tenofovir interaction observed in non-pregnant adults altered during pregnancy

WHAT IS KNOWN AND OBJECTIVE

Tenofovir exposure is increased in non-pregnant adults when tenofovir disoproxil fumarate is coadministered with lopinavir/ritonavir. In pregnant women, tenofovir exposure is decreased. Our objective is to describe the effect of lopinavir/ritonavir on tenofovir pharmacokinetics during pregnancy.

METHODS

Data were collected through the International Maternal Pediatric and Adolescent AIDS Clinical Trials (IMPAACT) Network P1026s protocol. This was a nonrandomized, open-label, parallel-group and multicentre phase-IV prospective study in pregnant women with HIV. Intensive steady-state 24-h pharmacokinetic profiles were collected during the third trimester of pregnancy and postpartum. Tenofovir was measured in plasma using validated liquid chromatography-mass spectrometry method (quantification limit: 10 ng/ml). Statistical tests compared paired and between group pharmacokinetic data.

RESULTS AND DISCUSSION

In women not receiving lopinavir/ritonavir (n = 28), tenofovir AUC_0-24 was 27% lower (2.2 mcg·h/ml vs 2.8 mcg·h/ml, p = 0.002) and oral clearance was 27% higher (61 L/h vs 48 L/h, p = 0.001) during the third trimester compared to paired postpartum data. In women receiving lopinavir/ritonavir (n = 10), tenofovir AUC_0-24 and oral clearance were not different antepartum compared to postpartum. Women with and women without concomitant lopinavir/ritonavir displayed no significant differences in postpartum tenofovir pharmacokinetics.

WHAT IS NEW AND CONCLUSION

Tenofovir exposure during the third trimester was reduced compared to postpartum in pregnant women not receiving lopinavir/ritonavir, but not in pregnant women also receiving lopinavir/ritonavir. Our findings suggest that pregnancy confounds the expected decrease in tenofovir exposure with concomitant lopinavir/ritonavir in non-pregnant adults. These findings illustrate the need for drug-drug interaction studies in pregnant women as drug disposition differs significantly in pregnant women compared to non-pregnant adults.

Safety and Pharmacokinetics of a Tenofovir Alafenamide Fumarate-Emtricitabine based Oral Antiretroviral Regimen for Prevention of HIV Acquisition in Women: A Randomized Controlled Trial

BACKGROUND

Daily oral emtricitabine (FTC, F)/tenofovir disoproxil fumarate (TDF) combination is approved for HIV pre-exposure prophylaxis (PrEP) in men and women. Tenofovir alafenamide fumarate (TAF) is a newer, more potent prodrug of tenofovir (TFV), and in combination with FTC, has recently been approved for prevention of HIV through rectal transmission.

METHODS

This Phase I, prospective, interventional, randomized study was conducted in three clinical sites: PROFAMILIA, Santo Domingo, Dominican Republic; University of Pittsburgh and Eastern Virginia Medical School. We assessed the multi-compartmental pharmacokinetics (primary outcome) and safety (secondary outcome) among HIV uninfected women randomized to F/TDF (200mg/300mg) or F/TAF (200mg/25mg; F/TAF25) (n=24) in a single dose phase (SDP) and F/TDF, F/TAF (200mg/10mg; F/TAF10), or F/TAF25 (n=75) in a multiple dose (14 daily doses) phase (MDP). We described PK parameters in plasma, peripheral blood mononuclear cells (PBMCs), and cervicovaginal (CV) and rectal fluids and tissues. ClinicalTrials.gov #NCT02904369, completed.

FINDINGS

Recruitment for the study began on 5 October 2016. The first participant was enrolled on 6 October 2016 and the last participant completed the study 21 November 2017.

PLASMA

TFV concentrations area under curve (AUC) were ~20 fold lower following F/TAF versus F/TDF. TFV-diphosphate (TFV-DP) AUC concentrations in PBMCs were 7-fold higher with F/TAF25 versus F/TDF. Median TFV-DP concentrations in vaginal tissue (4hours post last dose) were approximately 6-fold higher with F/TAF25 versus F/TDF. TFV and TFV-DP were lower with F/TAF versus F/TDF in rectal tissue. Concentrations of FTC and FTC-triphosphate (FTC-TP) were similar across matrices and treatment arms. Gastrointestinal adverse events (AEs) occurred more frequently in F/TDF users (44.0%) than in either F/TAF group (11.5 and 12.0%).

INTERPRETATION

F/TAF was safe and well-tolerated. TFV-DP concentrations were higher in PBMCs and similar or higher (4h post dose) in female genital tract tissues for F/TAF versus F/TDF. High FTC and FTC-TP concentrations in all compartments support the potential of F/TAF as a new PrEP combination for women.

The Influence of Pharmacogenetics on the Clinical Relevance of Pharmacokinetic Drug-Drug Interactions: Drug-Gene, Drug-Gene-Gene and Drug-Drug-Gene Interactions

Drug interactions are a well-known cause of adverse drug events, and drug interaction databases can help the clinician to recognize and avoid such interactions and their adverse events. However, not every interaction leads to an adverse drug event. This is because the clinical relevance of drug-drug interactions also depends on the genetic profile of the patient. If inhibitors or inducers of drug metabolising enzymes (e.g., CYP and UGT) are added to the drug therapy, phenoconcversion can occur. This leads to a genetic phenotype that mismatches the observable phenotype. Drug-drug-gene and drug-gene-gene interactions influence the toxicity and/or ineffectivness of the drug therapy. To date, there have been limited published studies on the impact of genetic variations on drug-drug interactions. This review discusses the current evidence of drug-drug-gene interactions, as well as drug-gene-gene interactions. Phenoconversion is explained, the and methods to calculate the phenotypes are described. Clinical recommendations are given regarding the integratation of the PGx results in the assessment of the relevance of drug interactions in the future.

Roles of Multidrug Resistance Protein 4 in Microbial Infections and Inflammatory Diseases

Numerous studies have reported the emergence of antimicrobial resistance during the treatment of common infections. Multidrug resistance (MDR) leads to failure of antimicrobial treatment, prolonged illness, and increased morbidity and mortality. Overexpression of multidrug resistance proteins (MRPs) as drug efflux pumps are one of the main contributions of MDR, especially multidrug resistance protein 4 (MRP4/ABCC4) in the development of antimicrobial resistance. The molecular mechanism of antimicrobial resistance is still under investigation. Various intervention strategies have been developed for overcoming MDR, but the effect is limited. Suppression of MRP4 may be an attractive therapeutic approach for addressing drug resistance. However, there are few reports on the involvement of MRP4 in antimicrobial resistance and inflammatory diseases. In this review, we introduced the function and regulation of MRP4, and then summarized the roles of MRP4 in microbial infections and inflammatory diseases as well as polymorphisms in the gene encoding this transporter. Further studies should be conducted on drug therapy targeting MRP4 to improve the efficacy of antimicrobial therapy. This review can provide useful information on MRP4 for overcoming antimicrobial resistance and anti-inflammatory therapy.

Methotrexate Decreases Tenofovir Exposure in Antiretroviral-Suppressed Individuals Living With HIV

BACKGROUND

To mitigate increased risk of premature cardiovascular disease in antiretroviral therapy (ART) suppressed adults living with HIV (PWH), low-dose methotrexate (LDMTX) was evaluated in a multicenter randomized placebo controlled clinical trial of 176 PWH taking various ART regimens (ACTG A5314). Given shared methotrexate (MTX) and tenofovir (TFV) pharmacokinetic (PK) pathways, a substudy was conducted to investigate whether LDMTX alters TFV exposure.

METHODS

Adults virally suppressed on ART for >24 weeks were randomized to LDMTX or placebo. The first 66 participants taking a tenofovir disoproxil fumarate-containing regimen underwent intensive PK sampling over 24 hours after the second dose of LDMTX 10 mg or placebo. TFV and MTX levels were quantified using validated mass spectrometry methods. TFV PK between LDMTX and placebo groups were compared and MTX PK was characterized.

RESULTS

Forty-eight participants completed this substudy (n = 20 on LDMTX and 28 on placebo). Baseline characteristics were balanced except for protease inhibitor (PI)-use (25% in LDMTX and 43% in placebo groups). For TFV, AUC6 (primary endpoint), and AUC24,imputed, Cmax, and Cmin (secondary endpoints) were on average 22%, and 24%, 27%, and 31% less in the LDMTX versus placebo groups, with reductions in secondary endpoints reaching statistical significance. Additional analyses suggested a greater reduction in the absence of PI although not significant.

CONCLUSION

Lower TFV AUC24,imputed and Cmax indicates that LDMTX reduces TFV exposure in PWH. However, this change was modest, not warranting a change in TFV dosing at this time. Further studies of TFV PK with LDMTX, especially without PI co-administration, are warranted.

Comparative pharmacokinetics between tenofovir disoproxil phosphate and tenofovir disoproxil fumarate in healthy subjects

Tenofovir is the representative treatment for human immunodeficiency virus and hepatitis B virus infection. This study was conducted to assess the pharmacokinetics (PKs) and safety characteristics after a single administration of tenofovir disoproxil phosphate compared to tenofovir disoproxil fumarate in healthy male subjects. An open-label, randomized, single administration, two-treatment, two-sequence crossover study was conducted in 37 healthy volunteers. Serial blood samples were collected up to 72 hours. Non-compartmental analysis was used to calculate the PK parameters. The 90% confidence intervals (90% CIs) of the geometric mean ratio (GMR) were calculated for comparing tenofovir disoproxil phosphate to tenofovir disoproxil fumarate. Safety assessments were performed including clinical laboratory tests, adverse events, etc. during the study. The GMR and 90% CIs were 1.0514 (0.9527-1.1603) for C_max and 1.0375 (0.9516-1.1311) for AUC_last, respectively, and both fell within the conventional bioequivalence range of 0.8-1.25. Both tenofovir salt forms were tolerable. This study demonstrated that tenofovir disoproxil phosphate (292 mg) was bioequivalent to tenofovir disoproxil fumarate (300 mg).

Population Pharmacokinetics of Tenofovir in Pregnant and Postpartum Women Using Tenofovir Disoproxil Fumarate

Pharmacokinetics of drugs can be affected by physiologic changes during pregnancy. Our aim was to assess the influence of covariates on tenofovir (TFV) pharmacokinetics in pregnant and postpartum women receiving tenofovir disoproxil fumarate (TDF). Population pharmacokinetic parameter estimates and the influence of covariates were assessed using nonlinear mixed-effects modeling (NONMEM 7.4). Forty-six women had intensive pharmacokinetic evaluations during the second and third trimesters of pregnancy, with another evaluation postpartum. A two-compartment pharmacokinetic model with allometric scaling for body weight and first-order absorption best described the tenofovir plasma concentration data. Apparent oral clearance (CL/F) and volume of distribution at steady state (V _ss/F) were increased during pregnancy. Weight, serum creatinine (SCr), pregnancy, albumin, and age were associated with TFV CL/F during univariate assessment, but in the multivariate analysis, changes in CL/F and V _ss/F were only associated with increased body weight and enhanced renal function. Due to greater weight and lower SCr during pregnancy, CL/F was 28% higher during pregnancy than postpartum. In the final model, CL/F (liters per hour) was described as 2.07 × (SCr/0.6)^0.65 × weight^0.75, with a low between-subject variability (BSV) of 24%. The probability of target attainment (proportion exceeding area under the concentration-time curve of >1.99 μg·h/ml, the 10th percentile of average TFV exposure for nonpregnant historical controls) was 68%, 80%, 87%, and 93% above the target with 300 mg, 350 mg, 400 mg, and 450 mg of TDF, respectively, during pregnancy and 88%, 92%, 96%, and 98% above the target with same doses in postpartum women. Dose adjustment of TDF during pregnancy is not generally warranted, but any modification should be based on weight and renal function. (This study has been registered at ClinicalTrials.gov under identifier NCT00042289.).

The antiretroviral 2',3'-dideoxycytidine causes mitochondrial dysfunction in proliferating and differentiated HepaRG human cell cultures

Nucleoside reverse transcriptase inhibitors (NRTIs) were the first drugs used to treat human immunodeficiency virus infection, and their use can cause mitochondrial toxicity, including mitochondrial DNA (mtDNA) depletion in several cases. The first-generation NRTIs, including 2',3'-dideoxycytidine (ddC), were originally and are still pursued as anticancer agents. NRTI-sensitive DNA polymerases localizing to mitochondria allow for the opportunity to poison proliferating cancer cell mtDNA replication as certain cancers rely heavily on mitochondrial functions. However, mtDNA replication is independent of the cell cycle creating a significant concern that toxicants such as ddC impair mtDNA maintenance in both proliferating and nonproliferating cells. To examine this possibility, we tested the utility of the HepaRG cell line to study ddC-induced toxicity in isogenic proliferating (undifferentiated) and nonproliferating (differentiated) cells. Following ddC exposures, we measured cell viability, mtDNA copy number, and mitochondrial bioenergetics utilizing trypan blue, Southern blotting, and extracellular flux analysis, respectively. After 13 days of 1 μM ddC exposure, proliferating and differentiated HepaRG harbored mtDNA levels of 0.9% and 17.9% compared with control cells, respectively. Cells exposed to 12 μM ddC contained even less mtDNA. By day 13, differentiated cell viability was maintained but declined for proliferating cells. Proliferating HepaRG bioenergetic parameters were severely impaired by day 8, with 1 and 12 μM ddC, whereas differentiated cells displayed defects of spare and maximal respiratory capacities (day 8) and proton-leak linked respiration (day 14) with 12 μM ddC. These results indicate HepaRG is a useful model to study proliferating and differentiated cell mitochondrial toxicant exposures.

Antiretroviral drug concentrations in brain tissue of adult decedents

OBJECTIVE

Determine concentrations of antiretroviral therapy (ART) drugs in the human brain.

DESIGN

Cohort study of persons with HIV who consented to antemortem assessment and postmortem autopsy.

METHODS

Eleven persons with HIV who were taking ART at the time of death and had detectable concentrations of at least one ART drug in intracardiac aspirate at autopsy were evaluated. Autopsies were performed within 24 h of death and brain tissue was stored at -80 °C. Concentrations of 11 ART drugs were measured in three brain regions (globus pallidus, cortical gray matter, white matter) by HPLC tandem mass spectrometry with a lower limit of quantification of 25 ng/ml.

RESULTS

Participants were mostly men (82%) with a mean age of 40.4 years. Drug concentrations in brain tissue were highly variable and exceeded published concentrations in cerebrospinal fluid for several drugs, including for tenofovir, efavirenz, and lopinavir. Drug concentrations correlated most strongly between cortical gray matter and globus pallidus (rho = 0.70) but less well between globus pallidus and white matter (rho = 0.43). Combining all drugs and brain regions (n = 89), higher drug concentrations in brain were associated with longer estimated duration of HIV infection (P = 0.015), lower HIV RNA in plasma (P = 0.0001), lower nadir CD4 T-cell count (P = 0.053), and worse neurocognitive performance (P = 0.017).

CONCLUSION

This is the first analysis of ART drug concentrations in human brain tissue. Concentrations of several drugs in this analysis were similar to published concentrations in cerebrospinal fluid but others exceeded published concentrations. The association between higher drug concentrations in the brain and worse neurocognitive performance may indicate ART neurotoxicity.

HIV-1 Sanctuary Sites-the Role of Membrane-Associated Drug Transporters and Drug Metabolic Enzymes

Despite significant advances in the treatment of human immunodeficiency virus-1 (HIV) infection with highly active antiretroviral drug therapy, the persistence of the virus in cellular and anatomic reservoirs is a major obstacle preventing total HIV eradication. Viral persistence could result from a variety of contributing factors including, but not limited to, non-adherence to treatment and adverse drug reactions, latently infected cells carrying replication-competent virus, drug-drug interactions, and inadequate antiretroviral drug (ARV) concentrations reached in several anatomic sites such as the brain, testis, and gut-associated lymphoid tissues. The distribution of ARVs at specific sites of infection is primarily dependent on drug physicochemical properties and drug plasma protein binding, as well as drug efflux, influx, and metabolic processes. A thorough understanding of the functional roles of drug transporters and metabolic enzymes in the disposition of ARVs in immune cell types and tissues that are characterized as HIV reservoirs and sanctuaries is critical to overcome the challenge of suboptimal drug distribution at sites of persistent HIV infection. This review summarizes the current knowledge related to the expression and function of drug transporters and metabolic enzymes in HIV cellular and anatomic reservoirs, and their potential contribution to drug-drug interactions and insufficient drug concentration at these sites.

Brief Report: Relationship Between ABCC4 SNPs and Hepatitis B Virus Suppression During Tenofovir-Containing Antiretroviral Therapy in Patients With HIV/HBV Coinfection

BACKGROUND

Incomplete hepatitis B virus (HBV) suppression during antiretroviral therapy (ART) in HIV and HBV coinfected patients is common, but underlying factors are not fully elucidated. We hypothesize that genetic factors that influence nucleoside analog pharmacokinetics will affect HBV treatment response.

METHODS

HIV/HBV coinfected patients on tenofovir disoproxil fumarate/lamivudine (TDF/3TC)-containing ART were enrolled. Selected ABCC4 single nucleotide polymorphisms (SNPs) with known effects on nucleoside pharmacokinetics were genotyped using TaqMan assays. Relationship between ABCC4 SNPs and unsuppressed HBV DNA (HBV DNA ≥20 IU/mL) were examined.

RESULTS

Of the 50 participants on TDF/3TC-containing ART for a median (range) of 1.5 (1-7.4) years, 20 (40%) had unsuppressed HBV DNA. Participants with unsuppressed compared with those with suppressed HBV DNA were more likely to have negative HBe antibody, lower body mass index, and lower CD4 count at enrollment. Carriers of ABCC4 rs11568695 (G3724A) variant allele were more likely than noncarriers to have unsuppressed HBV (61.1% vs. 29.0%, P = 0.038). Among 36 patients with suppressed HIV RNA (presumed good ART adherence), ABCC4 rs11568695 variant carriers were more likely than noncarriers to have unsuppressed HBV (58.8% vs. 20.0% P = 0.021). Logistic regression analysis that included genetic and nongenetic factors identified ABCC4 rs11568695 variant allele, body mass index, and male sex as predictors of unsuppressed HBV DNA.

CONCLUSIONS

We identified a novel association between ABCC4 rs11568695 SNP and poor HBV treatment response. If confirmed in further studies, ABCC4 genotyping could be used to identify individuals who may need intensified HBV therapy.

Are Standard Doses of Renally-Excreted Antiretrovirals in Older Patients Appropriate: A PBPK Study Comparing Exposures in the Elderly Population With Those in Renal Impairment

BACKGROUND AND OBJECTIVES

The elderly population receives the majority of prescription drugs but are usually excluded from Phase 1 clinical trials. Alternative approaches to estimate increases in toxicity risk or decreases in efficacy are therefore needed. This study predicted the pharmacokinetics (PK) of three renally excreted antiretroviral drugs in the elderly population and compared them with known exposures in renal impairment, to evaluate the need for dosing adjustments.

METHODS

The performance of the physiologically based pharmacokinetic (PBPK) models for tenofovir, lamivudine and emtricitabine were verified using clinical data in young and older subjects. Models were then used to predict PK profiles in a virtual population aged 20 to 49 years (young) and a geriatric population aged 65 to 74 years (elderly). Predicted exposure in the elderly was then compared with exposure reported for different degrees of renal impairment, where doses have been defined.

RESULTS

An increase in exposure (AUC) with advancing age was predicted for all drugs. The mean ratio of the increase in exposure were 1.40 for emtricitabine, 1.42 for lamivudine and 1.48 for tenofovir. The majority of virtual patients had exposures that did not require dosage adjustments. About 22% of patients on tenofovir showed exposures similar to that in moderate renal impairment, where dosage reduction may be required.

CONCLUSION

Comparison of the exposure in the elderly with exposure observed in patients with different levels of renal impairment, indicated that a dosage adjustment may not be required in elderly patients on lamivudine, emtricitabine and the majority of the patients on tenofovir. Clinical trials to verify these predictions are essential.

Spatial distribution of elvitegravir and tenofovir in rat brain tissue: Application of matrix-assisted laser desorption/ionization mass spectrometry imaging and liquid chromatography/tandem mass spectrometry

RATIONALE

The complexity of central nervous system (CNS) drug delivery is the main obstacle with the blood-brain barrier (BBB) known to restrict access of most pharmaceutical drugs into the brain. Mass spectrometry imaging (MSI) offers possibilities for studying drug deposition into the CNS.

METHODS

The deposition and spatial distribution of the two antiretroviral drugs elvitegravir and tenofovir in the brain were investigated in healthy female Sprague-Dawley rats following a single intraperitoneal administration (50 mg/kg). This was achieved by the utilization of quantitative liquid chromatography/tandem mass spectrometry (LC/MS/MS) and matrix-assisted laser desorption/ionization (MALDI) MSI.

RESULTS

LC/MS/MS showed that elvitegravir has better BBB penetration, reaching maximum concentration in the brain (C_max brain) of 976.5 ng/g. In contrast, tenofovir displayed relatively lower BBB penetration, reaching C_max brain of 54.5 ng/g. MALDI-MSI showed the heterogeneous distribution of both drugs in various brain regions including the cerebral cortex.

CONCLUSIONS

LC/MS/MS and MALDI-MSI provided valuable information about the relative concentration and the spatial distribution of the two common antiretroviral drugs. This study has also shown the capability of MALDI-MSI for direct visualization of pharmaceutical drugs in situ.

Cell-type specific differences in antiretroviral penetration and the effects of HIV-1 Tat and morphine among primary human brain endothelial cells, astrocytes, pericytes, and microglia

The inability to achieve adequate intracellular antiretroviral concentrations may contribute to HIV persistence within the brain and to neurocognitive deficits in opioid abusers. To investigate, intracellular antiretroviral concentrations were measured in primary human astrocytes, microglia, pericytes, and brain microvascular endothelial cells (BMECs), and in an immortalized brain endothelial cell line (hCMEC/D3). HIV-1 Tat and morphine effects on intracellular antiretroviral concentrations also were evaluated. After pretreatment for 24 h with vehicle, HIV-1 Tat, morphine, or combined Tat and morphine, cells were incubated for 1 h with equal concentrations of a mixture of tenofovir, emtricitabine, and dolutegravir at one of two concentrations (5 μM or 10 μM). Intracellular drug accumulation was measured using LC-MS/MS. Drug penetration differed depending on the drug, the extracellular concentration used for dosing, and cell type. Significant findings included: 1) Dolutegravir (at 5 μM or 10 μM) accumulated more in HBMECs than other cell types. 2) At 5 μM, intracellular emtricitabine levels were higher in microglia than other cell types; while at 10 μM, emtricitabine accumulation was greatest in HBMECs. 3) Tenofovir (5 or 10 μM extracellular dosing) displayed greater accumulation inside HBMECs than in other cell types. 4) After Tat and/or morphine pretreatment, the relative accumulation of antiretroviral drugs was greater in morphine-exposed HBMECs compared to other treatments. The opposite effect was observed in astrocytes in which morphine exposure decreased drug accumulation. In summary, the intracellular accumulation of antiretroviral drugs differed depending on the particular drug involved, the concentration of the applied antiretroviral drug, and the cell type targeted. Moreover, morphine, and to a lesser extent Tat, exposure also had differential effects on antiretroviral accumulation. These data highlight the complexity of optimizing brain-targeted HIV therapeutics, especially in the setting of chronic opioid use or misuse.

Renal safety of tenofovir alafenamide vs. tenofovir disoproxil fumarate: a pooled analysis of 26 clinical trials

Supplemental Digital Content is available in the text

Objective:

Compared with tenofovir disoproxil fumarate (TDF), tenofovir alafenamide (TAF) has been associated with improvement in markers of renal dysfunction in individual randomized trials; however, the comparative incidence of clinically significant renal events remains unclear.

Design:

We used a pooled data approach to increase the person-years of drug exposure analysed, maximizing our ability to detect differences in clinically significant outcomes.

Methods:

We pooled clinical renal safety data across 26 treatment-naive and antiretroviral switch studies to compare the incidence of proximal renal tubulopathy and discontinuation due to renal adverse events between participants taking TAF-containing regimens vs. those taking TDF-containing regimens. We performed secondary analyses from seven large randomized studies (two treatment-naive and five switch studies) to compare incidence of renal adverse events, treatment-emergent proteinuria, changes in serum creatinine, creatinine clearance, and urinary biomarkers (albumin, beta-2-microglobulin, and retinol binding protein-to-creatinine ratios).

Results:

Our integrated analysis included 9322 adults and children with HIV (n = 6360 TAF, n = 2962 TDF) with exposure of 12 519 person-years to TAF and 5947 to TDF. There were no cases of proximal renal tubulopathy in participants receiving TAF vs. 10 cases in those receiving TDF (P < 0.001), and fewer individuals on TAF (3/6360) vs. TDF (14/2962) (P < 0.001) discontinued due to a renal adverse event. Participants initiating TAF-based vs. TDF-based regimens had more favourable changes in renal biomarkers through 96 weeks of therapy.

Conclusion:

These pooled data from 26 studies, with over 12 500 person-years of follow-up in children and adults, support the comparative renal safety of TAF over TDF.

Pharmacokinetic Interactions Between the Fixed-Dose Combinations of Elvitegravir/Cobicistat/Tenofovir Disoproxil Fumarate/Emtricitabine and Elbasvir/Grazoprevir in Healthy Adult Participants

Treatment of individuals coinfected with human immunodeficiency virus (HIV) and hepatitis C virus (HCV) requires careful consideration of potential drug-drug interactions. The pharmacokinetic interaction of the HCV fixed-dose combination treatment of elbasvir/grazoprevir (EBR/GZR) when coadministered with the fixed-dose combination HIV treatment of elvitegravir/cobicistat/tenofovir disoproxil fumarate/emtricitabine (EVG/COB/TDF/FTC) was evaluated in 22 healthy adults. In period 1, oral doses of EVG/COB/TDF/FTC (150 mg/150 mg/300 mg/200 mg) were administered once daily for 7 days. In period 2, oral doses of EBR/GZR (50 mg/100 mg) were administered once daily for 10 days. In period 3, oral doses of EVG/COB/TDF/FTC were coadministered with EBR/GZR once daily for 10 days. The pharmacokinetics of EVG/COB/TDF/FTC were not clinically meaningfully altered by concomitant EBR/GZR administration. Geometric mean ratios (90%CIs) for area under the plasma concentration-time curve from time 0 to 24 hours (AUC_0-24 ) in the presence/absence of EBR/GZR were 1.1 (1.0, 1.2) for elvitegravir; 1.1 (1.0, 1.1) for emtricitabine; 1.2 (1.1, 1.2) for tenofovir; and 1.5 (1.4, 1.6) for cobicistat. In comparison, the AUC_0-24 of elbasvir was ∼2 times higher and the AUC_0-24 of grazoprevir was ∼5 times higher following concomitant administration of EVG/COB/TDF/FTC and EBR/GZR. Geometric mean ratios (90%CI) for AUC_0-24 in the presence/absence of EVG/COB/TDF/FTC were 2.2 (2.0, 2.4) for elbasvir and 5.4 (4.5, 6.4) for grazoprevir. Coadministration of EVG/COB/TDF/FTC and EBR/GZR was generally well tolerated in healthy adults in this study. Nevertheless, because of the increased GZR exposure that occurs with coadministration of EVG/COB/TDF/FTC and EBR/GZR, coadministration of this combination is not recommended in those coinfected with HIV and HCV.

Differences in Local and Systemic TFV PK Among Premenopausal Versus Postmenopausal Women Exposed to TFV 1% Vaginal Gel

Supplemental Digital Content is Available in the Text.

Objective:

We describe and compare the local and systemic pharmacokinetics (PK) of tenofovir (TFV) and TFV-diphosphate (TFV-DP) in healthy premenopausal (PRE) and postmenopausal (POST) women using TFV 1% gel and correlate local PK with other mucosal end points.

Methods:

PRE (n = 20) and POST (n = 17) women used 2 doses of TFV 1% vaginal gel, separated by 2 hours. Blood and cervicovaginal samples were obtained 3 and 23 hours after the second dose. PRE women used gel in the follicular and luteal phases of the menstrual cycle. POST women used gel at baseline and again after approximately 2 months of treatment with 0.01% vaginal estradiol (E2) cream.

Results:

Median TFV concentrations in cervicovaginal aspirate (ng/mL) and vaginal tissue (ng/mg) were significantly higher in PRE (4.3E10⁶, 49.8) versus POST women (2.6E10⁶, 2.2). POST women had significantly higher median molecular ratios of TFV-DP to TFV (3.7%) compared with PRE (0.19%). After vaginal E2 treatment, the local and systemic PK end points in POST women were generally similar to PRE women (all P values > 0.05). Importantly, median vaginal tissue TFV-DP concentrations (fmol/mg) among PRE, POST, and POST women after E2 therapy were similar (292.5, 463.3, and 184.6, respectively). Vaginal tissue TFV concentrations were significantly positively correlated with vaginal epithelial thickness, whereas vaginal tissue TFV-DP concentrations were positively correlated with density of vaginal CD4⁺ and CD8⁺ immune cells.

Conclusions:

The state of the cervicovaginal mucosa has a significant impact on local and systemic PK of a topically applied microbicide.

Pre-exposure Prophylaxis With Tenofovir Disoproxil Fumarate/Emtricitabine and Kidney Tubular Dysfunction in HIV-Uninfected Individuals

BACKGROUND

Pre-exposure prophylaxis (PrEP) with tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) is becoming increasingly adopted for HIV prevention. Tenofovir can cause proximal tubular damage and chronic kidney disease in HIV-infected persons, but little is known regarding its nephrotoxic potential among HIV-uninfected persons. In this study, we evaluated the effects of PrEP on urine levels of the following: α1-microglobulin (α1m), a marker of impaired tubular reabsorption; albuminuria, a measure of glomerular injury; and total proteinuria.

SETTING

The Iniciativa Profilaxis Pre-Exposicion (iPrEx) study randomized HIV-seronegative men and transgender women who have sex with men to oral TDF/FTC or placebo. The iPrEx open-label extension (iPrEx-OLE) study enrolled former PrEP trial participants to receive open-label TDF/FTC.

METHODS

A cross-sectional analysis compared urine biomarker levels by study arm in iPrEx (N = 100 treatment arm, N = 100 placebo arm). Then, urine biomarker levels were compared before and after PrEP initiation in 109 participants of iPrEx-OLE.

RESULTS

In iPrEx, there were no significant differences in urine α1m, albuminuria, or proteinuria by treatment arm. In iPrEx-OLE, after 24 weeks on PrEP, urine α1m and proteinuria increased by 21% [95% confidence interval (CI): 10 to 33] and 18% (95% CI: 8 to 28), respectively. The prevalence of detectable α1m increased from 44% to 65% (P < 0.001) and estimated glomerular filtration rate declined by 4 mL/min/1.73 m (P < 0.001). There was no significant change in albuminuria (6%; 95% CI: -7% to 20%).

CONCLUSION

PrEP with TDF/FTC was associated with a statistically significant rise in urine α1m and proteinuria after 6 months, suggesting that PrEP may result in subclinical tubule dysfunction.

The Changing Face of Human Immunodeficiency Virus-Mediated Kidney Disease

In nearly 40 years since human immunodeficiency virus (HIV) first emerged, much has changed. Our understanding of the pathogenesis of HIV infection and its effect on the cells within each kidney compartment has progressed, and the natural history of the disease has been transformed. What was once an acutely fatal illness is now a chronic disease managed with oral medications. This change is largely due to the advent of antiretroviral drugs, which have dramatically altered the prognosis and progression of HIV infection. However, the success of antiretroviral therapy has brought with it new challenges for the nephrologist caring for patients with HIV/acquired immune deficiency syndrome, including antiretroviral therapy-induced nephrotoxicity, development of non-HIV chronic kidney disease, and rising incidence of immune-mediated kidney injury. In this review, we discuss the pathogenesis of HIV infection and how it causes pathologic changes in the kidney, review the nephrotoxic effects of select antiretroviral medications, and touch upon other causes of kidney injury in HIV cases, including mechanisms of acute kidney injury, HIV-related immune complex glomerular disease, and thrombotic microangiopathy.

Nucleotide Reverse Transcriptase Inhibitors: A Thorough Review, Present Status and Future Perspective as HIV Therapeutics

BACKGROUND

Human immunodeficiency virus type-1 (HIV-1) infection leads to acquired immunodeficiency syndrome (AIDS), a severe viral infection that has claimed approximately 658,507 lives in the US between the years 2010-2014. Antiretroviral (ARV) therapy has proven to inhibit HIV-1, but unlike other viral illness, not cure the infection.

OBJECTIVE

Among various Food and Drug Administration (FDA)-approved ARVs, nucleoside/ nucleotide reverse transcriptase inhibitors (NRTIs) are most effective in limiting HIV-1 infection. This review focuses on NRTIs mechanism of action and metabolism.

METHODS

A search of PubMed (1982-2016) was performed to capture relevant articles regarding NRTI pharmacology.

RESULTS

The current classical NRTIs pharmacology for HIV-1 prevention and treatment are presented. Finally, various novel strategies are proposed to improve the efficacy of NRTIs, which will increase therapeutic efficiency of present-day HIV-1 prevention/treatment regimen.

CONCLUSION

Use of NRTIs will continue to be critical for successful treatment and prevention of HIV-1.

Tenofovir Diphosphate in Dried Blood Spots Is Strongly Associated With Viral Suppression in Individuals With Human Immunodeficiency Virus Infections

BACKGROUND

Although tenofovir diphosphate (TFV-DP) in dried blood spots (DBS) is a predictor of adherence and pre-exposure prophylaxis efficacy, its utility in human immunodeficiency virus (HIV) treatment remains unknown.

METHODS

DBS for TFV-DP were collected up to 3 times over 48 weeks in persons living with HIV (PLWH) who were receiving TFV disoproxil fumarate (TDF)-based therapy. Log-transformed baseline TFV-DP was compared using t-tests or analyses of variance; generalized estimating equations were used to estimate the adjusted odds ratio (aOR) of viral suppression (<20 copies/mL) based on the TFV-DP concentration at the study visit.

RESULTS

We analyzed 1199 DBS from 532 participants (76 female; 101 Black, 101 Hispanic). Among the virologically-suppressed participants at baseline (n = 347), TFV-DP was lower in Blacks (geometric mean 1453, 95% confidence interval [CI] 1291-1635) vs Whites (1793, 95% CI 1678-1916; P = .002) and Hispanics (1760, 95% CI 1563-1982; P = .025); in non-boosted (1610, 95% CI 1505-1723) vs. boosted (1888, 95% CI 1749-2037; P = .002) regimens; and in non-nucleoside reverse transcription inhibitor-based (1563, 95% CI 1432-1707) vs. boosted protease inhibitor-based (1890, 95% CI 1704-2095; P = .006) and multiclass-based (1927, 95% CI 1650-2252; P = .022) regimens. The aOR of virologic suppression, after adjusting for age, gender, race, body mass index, estimated glomerular filtration rate, CD4+ T-cell count, antiretroviral drug class and duration of therapy, was 73.5 (95% CI 25.7-210.5; P < .0001) for a TFV-DP concentration ≥1850 fmol/punch compared to <350 fmol/punch.

CONCLUSIONS

TFV-DP in DBS is strongly associated with virologic suppression in PLWH on TDF-based therapy and is associated with certain participant characteristics. Further research is required to evaluate this drug adherence and exposure measure in clinical practice.

CLINICAL TRIALS REGISTRATION

NCT02012621.

A murine ex vivo 3D kidney proximal tubule model predicts clinical drug-induced nephrotoxicity

Drug attrition and clinical product withdrawals due to nephrotoxicity remain major challenges for pharmaceutical drug development pipelines. Currently, no reliable high-throughput in vitro screening models are available that provide reliable, predictive toxicology data for clinical nephrotoxicity. Drug screens to predict toxicity and pharmacology assessments are compromised by standard two-dimensional (2D) cell monoculture models. Here we extend a previously reported murine three-dimensional (3D) kidney-derived intact proximal tubule model to provide ex vivo drug toxicity data that reliably compare to clinical experiences and improve nephrotoxicity predictions over current 2D cell assays. Proximal tubule cytotoxicity was monitored by ATP depletion for 12 compounds (acarbose, acetylsalicylic acid, captopril, cimetidine, cidofovir, cisplatin, doxorubicin, gentamicin, polymyxin B, polymyxin B nonapeptide, probenecid and vancomycin) in 3D proximal tubule ex vivo assays. Drug concentration-response curves (1-1000 µM) and IC₅₀, lowest effective concentration (LEC) and AUC values were compared to clinical therapeutic exposure levels (C_max). The 100-fold C_max threshold demonstrated best sensitivity (96.9%) and specificity (87.5%) for this assay, with high positive (93.9%) and negative (93.3%) predictive values for nephrotoxicity. IC₅₀ values were superior to LEC. Results also support the model's capability to predict substrate-inhibitor/competitor interactions, yielding toxicity results similar to those reported in vivo. These 3D proximal tubule-based drug screens provide more reliable nephrotoxicity predictions, and more insight into complex mechanisms implicated in nephrotoxicity than current standard 2D cell assays. This new approach for rapid drug toxicity testing produces more reliable clinical comparisons than current 2D cell culture screening techniques.

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.

Genetic variation of kinases and activation of nucleotide analog reverse transcriptase inhibitor tenofovir

As antiretroviral therapy has become more accessible across the world and coformulations have improved patient compliance; the morbidity and mortality of HIV/AIDS has decreased. However, there is still a substantial gap in knowledge regarding the impact of genetic variation on the metabolism of and response to some of the most commonly prescribed antiretrovirals, including the nucleotide reverse transcriptase inhibitor tenofovir. While it has been scientifically established that tenofovir must be activated to be efficacious against HIV, the enzymes responsible for this activation have not been well characterized. The purpose of this review is to summarize and clarify the scientific knowledge regarding the enzymes that phosphorylate and activate this clinically important drug.

Roles of Renal Drug Transporter in Drug Disposition and Renal Toxicity

The kidney plays an important role in maintaining total body homeostasis and eliminating toxic xenobiotics and metabolites. Numerous drugs and their metabolites are ultimately eliminated in the urine. The reabsorption and secretion functions of the nephron are mediated by a variety of transporters located in the basolateral and luminal membranes of the tubular cells. In the past decade, many studies indicated that transporters play important roles in drug pharmacokinetics and demonstrated the impact of renal transporters on the disposition of drugs, drug-drug interactions, and nephrotoxicities. Here, we focus on several important renal transporters and their roles in drug elimination and disposition, drug-induced nephrotoxicities and potential clinical solutions.

Darunavir/Cobicistat/Emtricitabine/Tenofovir Alafenamide: A Review in HIV-1 Infection

Darunavir/cobicistat/emtricitabine/tenofovir AF (Symtuza^®) is the first protease inhibitor (PI)-based single-tablet regimen (STR) available for the treatment of adults and adolescents (aged ≥ 12 years) with HIV-1 infection. It combines the PI darunavir (which has a high genetic barrier to resistance) with the pharmacokinetic booster cobicistat and the nucleos(t)ide reverse transcriptase inhibitors emtricitabine and tenofovir alafenamide (tenofovir AF), the latter being associated with less off-target tenofovir exposure than its predecessor tenofovir disoproxil fumarate (tenofovir DF). Over 48 weeks in phase 3 trials, darunavir/cobicistat/emtricitabine/tenofovir AF was noninferior to darunavir/cobicistat plus emtricitabine/tenofovir DF in establishing virological suppression in antiretroviral therapy (ART)-naïve adults and, likewise, was noninferior to an ongoing boosted PI, emtricitabine plus tenofovir DF regimen in preventing virological rebound in virologically-suppressed, ART-experienced adults. Resistance did not emerge to the STR components, with the exception being an emtricitabine resistance-associated mutation (RAM) [M184I/V] in one of seven recipients who experienced virological failure (although M184V was a minority variant at screening in this patient). Darunavir/cobicistat/emtricitabine/tenofovir AF was generally well tolerated, with renal and bone profile improvements but less favourable effects on some lipids versus tenofovir DF-based regimens. Thus, although longer-term and cost-effectiveness data would be beneficial, darunavir/cobicistat/emtricitabine/tenofovir AF is a welcome addition to the STRs available for the treatment of adults and adolescents with HIV-1 infection, being the first to combine the high genetic resistance barrier of darunavir with the renal/bone profile of tenofovir AF, thus expanding the patient population for whom an STR may be suitable.

Acute kidney injury in HIV-infected patients: a critical review

Acute kidney injury (AKI) is characterized by a rapid decline of renal function associated with worse outcomes. The purpose of the authors is to perform a critical review of the incidence, risk factors, pathogenesis and outcome of AKI in HIV-infected patients. Human immunodeficiency virus (HIV)-infected patients have an increased risk of developing AKI, to which contribute both HIV-dependent and HIV-independent factors as well as the nephrotoxicity of drugs used. The increased risk of AKI in HIV-infected patients and its negative impact on prognosis highlights the need for identification of patients at risk, creation of prevention strategies and management. HIV-infected patients have an increased risk of developing AKI, to which both HIV-dependent and HIV-independent factors contribute, as well as the nephrotoxicity of drugs used. The increased risk of AKI in HIV-infected patients and its negative impact on prognosis highlight the need for identification of patients at risk, creation of prevention strategies and management.