Evaluation of genotoxic and mitotoxic effects of TAF-loaded chitosan nanoparticles in HepG2 cells.

Tenofovir alafenamide (TAF) is a new drug from the nucleotide reverse transcriptase inhibitor group approved for the treatment of chronic Hepatitis B in 2016. With this study, we aimed to test whether possible cellular toxicity can be reduced by controlled drug release as a result of loading with chitosan nanoparticles (CHS). We investigated the genotoxic and mitotoxic effects of 45 µM TAF-loaded CHS and TAF-only on HepG2 cells by micronucleus (MN), comet assay, determination of mtDNA quantification, mitochondrial membrane potential (ΔΨm), and ROS levels. Additionally, we compared the samples by RNAseq analyses to reveal the transcriptional responses to each regimen. In terms of genotoxic tests, although MN and comet were found higher in all experimental treatment conditions, the encapsulation of CHS reduced the genotoxicity of TAF. MtDNA level was found to be lower in the TAF treatment, whereas it was higher in CHS and CHS-TAF treatments. The TAF-loaded CHS and TAF treatments had an impaired ΔΨm value. Cellular ROS levels were higher in all treatment conditions. According to the analyses of gene expression patterns; CHS-only changed the expression of relatively few genes (187 genes), while TAF changed the expression of the 1974 genes and TAF-loaded CHS changed the expression of 734 genes. Considering the gene expression numbers, CHS encapsulation of TAF significantly reduced the number of genes that were differentially expressed by TAF-only. Overall, we observed that TAF has genotoxic and mitotoxic effects on HepG2 cells, and upon encapsulation with CHS, its genotoxic and mitotoxic effects were decreased.

Tenofovir disoproxil fumarate mediates neuronal injury by inducing neurotoxicity.

PURPOSE: Highly active antiretroviral therapy (HAART) is an accepted treatment option for patients with virus infection. Mounting evidence indicated that persistent HAART treatment is implicated with increased morbidity of HIV-associated neurocognitive disorders (HAND) in patients. Tenofovir disoproxil fumarate (TDF), a novel nucleotide reverse transcriptase inhibitor (NRTI), was used in patients with HIV co-infected with HBV. And it is still a vital first-line antiretroviral compounds in HAART. However, whether persistent treatment with TDF is involved in HAND development remains to be further elucidated. In this study, we aimed to discuss the neurotoxicity of TDF. METHODS: We used SH-SY5Y cells and primary neuronal cells to evaluate the neurotoxicity of TDF in vitro. The cytotoxicity of TDF on SH-SY5Y cells and primary neuronal cells was evaluated by the cell viability and LDH levels by MTT assay and LDH kit, respectively. Hoechst 33342 staining, TUNEL assay and flow cytometry were performed to evaluate the cells apoptosis. The intracellular reactive oxygen species (ROS) and malondialdehyde (MDA) production were measured by commercial kits. In addition, the activation level of caspase-3 was evaluated using spectrophotometry and western blotting. RESULTS: Our results showed that TDF treatment significantly induced cell viability and induced apoptosis of SH-SY5Y cells and primary neuronal cells. Furthermore, the ROS levels and MDA productions were significantly up-regulated in nerve cells treated with TDF.  CONCLUSION: Our findings indicated that TDF may induce neuronal cell apoptosis through increasing the intracellular ROS and the expression level of caspase-3, which may be related to the increasing prevalence of HAND.

Senescence and oxidative stress toxicities induced by lamivudine and tenofovir in Drosophila melanogaster.

BACKGROUND: Lamivudine and tenofovir disoproxil fumarate act against the replication of hepatitis B and human immunodeficiency viruses via inhibition of the reverse transcriptase enzyme activity, thereby preventing the synthesis of viral DNA. Chronic administration of these drugs has been associated with toxicities, including senescence, oxidative stress and premature death. A study of these toxicities in Drosophila melanogaster, which share 75% genomic similarity with humans could help to develop a pharmacologic intervention. METHODS: Susceptibility of D. melanogaster for lamivudine and tenofovir-induced toxicities were investigated. First, flies (≤3 days old) were fed with drugs-supplemented diet at varying concentrations (1mg to 300mg/10-gram diet) or distilled water for seven days to determine LD50. Secondly, five groups of 60 flies were fed with four concentrations of test drugs: 2.9mg, 5.82mg, 11.64mg and 23.28mg each per 10-gram diet for 28 days survival and lifespan assays. Then 5-day treatment plan was utilized to determine drugs toxicities on climbing ability and some biomarkers of oxidative stress. Finally, molecular docking was carried out using the Auto-dock vina mode to predict the biological interactions between the test drugs and D. melanogaster acetylcholinesterase (AChE) or glutathione-S-transferase (GST). RESULTS: The LD50 of lamivudine or tenofovir was 47.07 or 43.95mg/10g diet, respectively. Each drug significantly (P<0.05) reduced the survival rate, longevity and climbing performance of the flies dose-dependently. These drugs also altered levels of biochemical parameters: AChE, GST, superoxide dismutase (SOD), catalase (CAT), total thiol (T-SH), and malondialdehyde (MDA) of the flies significantly (P<0.05). In silico molecular analysis showed that the test drugs interacted with significantly (P<0.05) higher binding affinities at the same catalytic sites of D. melanogaster GST and AChE compared with substrates (glutathione or acetylcholine). CONCLUSION: The significant lamivudine and tenofovir-induced toxicities observed as increased mortality, climbing deficits and compromised antioxidant defence in D. melanogaster demands further research for possible pharmacological intervention.

Anti-HIV drugs promote ß-amyloid deposition and impair learning and memory in BALB/c mice.

OBJECTIVES: Growing evidence suggested that antiretroviral (ARV) drugs may promote amyloid beta (Aß) accumulation in HIV-1-infected brain and the persistence of HIV-associated neurocognitive disorders (HANDs). It has also been shown that lipid peroxidation upregulates ß-site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1) expression and subsequently promotes Aß peptide production. In the present study, we examined whether chronic exposure to the anti-HIV drugs tenofovir disoproxil fumarate (TDF) and nevirapine induces lipid peroxidation thereby promoting BACE1 and Aß generation and consequently impair cognitive function in mice. METHODS: TDF or nevirapine was orally administered to female BALB/c mice once a day for 8 weeks. On the 7th week of treatment, spatial learning and memory were assessed using the Morris water maze test. The levels of lipid peroxidation, BACE1, amyloid ß 1-42 (Aß1-42) and Aß deposits were measured in the hippocampal tissue upon completion of treatment. RESULTS: Chronic administration of nevirapine induced spatial learning and memory impairment in the Morris water maze test, whereas TDF did not have an effect. TDF and nevirapine administration increased hippocampal lipid peroxidation and Aß1-42 concentration. Nevirapine further upregulated BACE1 expression and Aß deposits. CONCLUSION: Our results suggest that chronic exposure to TDF and nevirapine contributes to hippocampal lipid peroxidation and Aß accumulation, respectively, as well as spatial learning and memory deficits in mice even in the absence of HIV infection. These findings further support a possible link between ARV drug toxicity, Aß accumulation and the persistence of HANDs.

Clinical diagnosis of sensory neuropathy in HIV patients treated with tenofovir: A 6-month follow-up study.

BACKGROUND: Sensory neuropathy (SN) is a common and often painful neurological condition associated with HIV-infection and its treatment. However, data on the incidence of SN in neuropathy-free individuals initiating combination antiretroviral therapies (cART) that do not contain the neurotoxic agent stavudine are lacking. AIMS: We investigated the 6-month incidence of SN in ART naïve individuals initiating tenofovir (TDF)-based cART, and the clinical factors associated with the development of SN. METHODS: 120 neuropathy-free and ART naïve individuals initiating cART at a single center in Johannesburg, South Africa were enrolled. Participants were screened for SN using clinical signs and symptoms at study enrolment and approximately every 2-months for a period of ~6-months. Diagnostic criteria for symptomatic SN was defined by the presence of at least one symptom (pain/burning, numbness, paraesthesias) and at least two clinical signs (reduced vibration sense, absent ankle reflexes or pin-prick hypoaesthesia). Diagnostic criteria for asymptomatic SN required at least two clinical signs only (as above). RESULTS: A total of 88% of the cohort completed three visits within the 6-month period. The 6-month cumulative incidence of neuropathy was 140 cases per 1000 patients (95% CI: 80-210) at an incidence rate of 0.37 (95% CI: 0.2-0.5) per person year. Height and active tuberculosis (TB) disease were independently associated with the risk of developing SN (P < .05). INTERPRETATION: We found that within the first 6 months of starting cART, incident SN persists in the post-stavudine era, with 11 (9%) of individuals developing asymptomatic SN, and 9 (8%) developing symptomatic SN.

Discontinuation of tenofovir due to nephrotoxicity: insight into 12 years of clinical practice

INTRODUCTION: Chronic kidney disease is a significant cause of morbidity and mortality among patients infected with human immunodeficiency virus (HIV). Tenofovir disoproxil fumarate (TDF) is widely used as the part of combination antiretroviral therapy (cART) and may cause renal function impairment. AIM: The primary objective of this analysis was to determine the rate of reversibility of kidney dysfunction and factors correlated with eGFR improvement in patients treated with TDF. MATERIALS AND METHODS: All patients who discontinued TDF between 2003 and 2015 were screened and included in the study if the reason for withdrawal was nephrotoxicity. Kidney function (eGFR, proteinuria, haematuria) was assessed on treatment and one year after discontinuation. Factors associated with not achieving eGFR recovery one year after discontinuing TDF were assessed. RESULTS: A total of 69 patients out of 1625 screened discontinued TDF due to nephrotoxicity and were included in the analysis. At the end of the study period eGFR (CKD-EPI) improved in 52 (75,4%) patients. The eGFR difference was 11,7 ml/min/1,73m2 (95% CI: 6,0 ­ 14,5). Two factors were associated with kidney function improvement: the length of TDF treatment and baseline eGFR. Better recovery was observed in patients treated with shorter (difference: 15,6 ml/min/1,73m2, 95% CI: 5,99 ­ 23,0) and in those with impaired renal function at baseline (difference: 21 ml/min/1,73m2, 95% CI: 11,0 ­ 27,99). CONCLUSIONS: In majority of patients who discontinue TDF therapy, kidney function improves during oneyear period. The drug withdrawal in case of eGFR deterioration should not be postponed.

Recellularized Native Kidney Scaffolds as a Novel Tool in Nephrotoxicity Screening.

Drug-induced kidney injury in medicinal compound development accounts for over 20% of clinical trial failures and involves damage to different nephron segments, mostly the proximal tubule. Yet, currently applied cell models fail to reliably predict nephrotoxicity; neither are such models easy to establish. Here, we developed a novel three-dimensional (3D) nephrotoxicity platform on the basis of decellularized rat kidney scaffolds (DS) recellularized with conditionally immortalized human renal proximal tubule epithelial cells overexpressing the organic anion transporter 1 (ciPTEC-OAT1). A 5-day SDS-based decellularization protocol was used to generate DS, of which 100-µm slices were cut and used for cell seeding. After 8 days of culturing, recellularized scaffolds (RS) demonstrated 3D-tubule formation along with tubular epithelial characteristics, including drug transporter function. Exposure of RS to cisplatin (CDDP), tenofovir (TFV), or cyclosporin A (CsA) as prototypical nephrotoxic drugs revealed concentration-dependent reduction in cell viability, as assessed by PrestoBlue and Live/Dead staining assays. This was most probably attributable to specific uptake of CDDP by the organic cation transporter 2 (OCT2), TFV through organic anion transporter 1 (OAT1), and CsA competing for P-glycoprotein-mediated efflux. Compared with 2D cultures, RS showed an increased sensitivity to cisplatin and tenofovir toxicity after 24-hour exposure (9 and 2.2 fold, respectively). In conclusion, we developed a physiologically relevant 3D nephrotoxicity screening platform that could be a novel tool in drug development.

Performance Assessment of New Urinary Translational Safety Biomarkers of Drug-induced Renal Tubular Injury in Tenofovir-treated Cynomolgus Monkeys and Beagle Dogs.

Newer urinary protein kidney safety biomarkers can outperform the conventional kidney functional biomarkers blood urea nitrogen (BUN) and serum creatinine (SCr) in rats. However, there is far less experience with the relative performance of these biomarkers in dogs and nonhuman primates. Here, we report urine protein biomarker performance in tenofovir-treated cynomolgus monkeys and beagle dogs. Tenofovir intravenous daily dosing in monkeys for 2 or 4 weeks at 30 mg/kg/day resulted in minimal to moderate tubular degeneration and regeneration, and tenofovir disoproxil fumarate oral dosing in dogs for 10 days at 45 mg/kg/day resulted in mild to marked tubular degeneration, necrosis, and regeneration. Among biomarkers tested, kidney injury molecule 1 (Kim-1) and clusterin (CLU) clearly outperformed BUN and SCr and were the most reliable in detecting the onset and progression of tenofovir-induced tubular injury. Cystatin C, retinol binding protein 4, ß2-microglobulin, neutrophil gelatinase-associated lipocalin, albumin, and total protein also performed better than BUN and SCr and added value when considered together with Kim-1 and CLU. These findings demonstrate the promising utility of these urinary safety biomarkers in monkeys and dogs and support their further evaluation in human to improve early detection of renal tubular injury.

A Direct Comparison of the Effects of the Antiretroviral Drugs Stavudine, Tenofovir and the Combination Lopinavir/Ritonavir on Bone Metabolism in a Rat Model.

Antiretroviral (ARV) treatment may induce metabolic complications in HIV patients on long-term therapy that can affect bone health. In this study, the effects of the ARVs Stavudine (d4T), Tenofovir (TDF) and Lopinavir/ritonavir (LPV/r) on bone metabolism and lipodystrophy were directly compared in rats to negate the consequences of HIV-associated confounding factors. Healthy 12-14-week-old male Wistar rats (n = 40) were divided into four treatment groups and received an oral animal equivalent dose of either Stavudine (6.2 mg/kg/day), TDF (26.6 mg/kg/day), LPV/r (70.8 mg/kg/day) or water (Control 1.5 mL water/day) for a period of 9 weeks. Whole-body DXA measurements, a biomechanical three-point breaking test and histomorphometric analysis were performed on the femurs and tibias at the end of the treatment period. Stavudine monotherapy was found to be associated with decreased femoral bone mineral density that translated into reduced bone strength, whereas histomorphometric analysis demonstrated that Stavudine induces an imbalance in bone metabolism at tissue level, evident in higher resorption (eroded surfaces, osteoclast surfaces and osteoclast number) and lower formation parameters (osteoblast surfaces and osteoid surfaces). This was less clear in the rats treated with either TDF or LPV/r. Furthermore, both Stavudine and TDF treatment resulted in significant bone marrow adiposity, although no significant redistribution of body fat was noted in the treated rats compared to controls. The data from this study suggest that in the absence of HIV-associated factors, LPV/r is less detrimental to bone metabolism compared to Stavudine and TDF.

Establishment of HK-2 Cells as a Relevant Model to Study Tenofovir-Induced Cytotoxicity.

Tenofovir (TFV) is an antiviral drug approved for treating Human Immunodeficiency Virus (HIV) and Hepatitis B. TFV is administered orally as the prodrug tenofovir disoproxil fumarate (TDF) which then is deesterified to the active drug TFV. TFV induces nephrotoxicity characterized by renal failure and Fanconi Syndrome. The mechanism of this toxicity remains unknown due to limited experimental models. This study investigated the cellular mechanism of cytotoxicity using a human renal proximal tubular epithelial cell line (HK-2). HK-2 cells were grown for 48 h followed by 24 to 72 h exposure to 0-28.8 µM TFV or vehicle, phosphate buffered saline (PBS). MTT (MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) and Trypan blue indicated that TFV diminished cell viability at 24-72 h. TFV decreased ATP levels at 72 h when compared to vehicle, reflecting mitochondrial dysfunction. TFV increased the oxidative stress biomarkers of protein carbonylation and 4-hydroxynonenol (4-HNE) adduct formation. Tumor necrosis factor alpha (TNFα) was released into the media following exposure to 14.5 and 28.8 µM TFV. Caspase 3 and 9 cleavage was induced by TFV compared to vehicle at 72 h. These studies show that HK-2 cells are a sensitive model for TFV cytotoxicity and suggest that mitochondrial stress and apoptosis occur in HK-2 cells treated with TFV.

Mitochondrial and Oxidative Stress Response in HepG2 Cells Following Acute and Prolonged Exposure to Antiretroviral Drugs.

Chronic HIV treatment with antiretroviral drugs has been associated with adverse health outcomes. Mitochondrial toxicity exhibited by nucleoside reverse transcriptase inhibitors (NRTIs) is pinpointed as a molecular mechanism of toxicity. This study evaluated the effect of NRTIs: Zidovudine (AZT, 7.1 µM), Stavudine (d4T, 4 µM) and Tenofovir (TFV, 1.2 µM), on mitochondrial (mt) stress response, mtDNA integrity and oxidative stress response in human hepatoma cells at 24 and 120 h. Markers for mt function, mt biogenesis, oxidative stress parameters, and antioxidant response were evaluated by spectrophotometry, luminometry, flow cytometry, qPCR and western blots. We found that AZT and d4T reduced mtDNA integrity (120 h, AZT: 76.1%; d4T:36.1%, P < 0.05) and remained unchanged with TFV. All three NRTIs, however, reduced ATP levels (AZT: 38%; d4T: 56.4%; TFV: 27.4%, P = 0.01) and mt membrane potential at 120 h (P < 0.005). Oxidative damage and reactive oxygen species (ROS) were increased by TFV and AZT at 24 h, and by d4T at 120 h (P < 0.05). Antioxidant response molecules and mt biogenesis markers were elevated by all NRTIs, with TFV causing the most significant increase (P < 0.05). Data from this study suggest that AZT, d4T and TFV alter mt function. TFV, however, achieves this independently of mtDNA depletion. Furthermore, AZT exerts toxicity soon after exposure as noted from changes at 24 h and d4T exerts greater toxicity over prolonged exposure (120 h).

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.

Toxicological evaluation of antiretroviral Tenofovir Disoproxil Fumarate on the mollusk Biomphalaria glabrata and its hemocytes.

Tenofovir disoproxil fumarate (TDF) is a drug used in HIV treatment, and several studies have detected its presence in surface water. Furthermore, more information on its environmental impact is needed in the scientific literature. Thus, due to the lack of data on the impact of this drug, and its presence in different waters of the world, this work aimed to evaluate the potential toxicological effects of TDF on the mollusk Biomphalaria glabrata in vivo and in vitro. For in vitro analysis, hemocytes were exposed to different drug concentrations for 1 h and evaluated for feasibility, and phagocytic and metabolic activity. The in vivo analysis consisted of the exposure of groups of five mollusks, in triplicate, at the same drug concentrations for 72 h and 21 days, evaluating mortality, and mollusk and hemolymph behavior. Although the exposure of the mollusk to TDF did not reduce its survival, however it was toxic to its hemocytes. Even if toxicity was identified on the mollusk and its hemocytes initially, further studies should be conducted to understand the effects of this residue on the environment and different life stages of the mollusk because, per the Globally Harmonized System of Classification and Labeling of Chemicals, for aquatic ecosystems, the results obtained were classified as toxic (EC50% 2.65 [1.98; 5.29] mg/L) and could cause unfeasibility in hemocytes at concentrations below 10 mg/l.

The molecular feature of abnormal fetal neuromuscular development after maternal use of telbivudine or tenofovir during pregnancy in rodent model.

AIMS: Maternal treatment with nucleoside analogues such as telbivudine (LdT) and tenofovir disoproxil fumarate (TDF) has been applied worldwide. However, administration of LdT or TDF during pregnancy may affect the fetal neuromuscular development. We conducted the current study to investigate the histological pathology and transcriptomic changes pertaining to the neuromuscular system of the newborn exposed to LdT or TDF during pregnancy in rodent model. MAIN METHODS: Pregnant C57/BL6 mice were randomly divided into three arms and administered either with LdT solution (0.1 ml, 78 mg/kg/d), TDF solution (0.1 ml, 39 mg/kg/d) or normal saline solution (0.1 ml). Pups in each arm were weighed and sacrificed after birth. Both sides of quadriceps femoris muscle of the newborn were obtained. The histological observation was conducted under light microscope. The transcriptional profiling was analyzed with RNA sequencing (RNA seq). KEY FINDINGS: Four types of morphological abnormalities of the newborn neuromuscular system, being clusters of rhabdomyoblasts, skeletal muscle fibrosis, rhabdomyolysis and necrosis and immature muscle fiber bundles, were noted in both LdT group and TDF group. Moreover, both groups showed significantly decreased gross cross-sectional area of muscle fiber and significantly increased percentage of muscle lesion area. RNA seq identified a total of 164 differentially expressed genes (DEGs) essential to fetal neuromuscular development. These DEGs were involved in calcium regulation, phospholipid activity, muscle cell development, the functioning of mitochondria/endoplasmic reticulum/lysosome/cytoskeleton, the regulation of arachidonic acid and the development of nervous system. SIGNIFICANCE: Our findings suggest maternal administration of LdT or TDF lead to abnormal neuromuscular development in offspring mice. Further study should be encouraged to investigate the down-stream signaling pathways.

Early switching of tenofovir disoproxil fumarate (TDF) in HIV-infected patients with TDF-induced nephrotoxicity: a prospective study.

Background: Tenofovir disoproxil fumarate (TDF) can induce proximal renal tubulopathy (PRT) and necessitate changes in treatment regimen. This prospective study aimed to compare tubular function recovery following early switching versus late switching of TDF in human immunodeficiency virus (HIV)-infected patients with TDF-induced PRT.Methods: For this prospective study, conducted during 2017-2019, we enrolled HIV-1-infected, virologically suppressed adults undergoing TDF-containing combination antiretroviral therapy. Patients were separated into a late-switching group (LSG) and an early-switching group (ESG). The LSG included patients having an estimated glomerular filtration rate (eGFR) decrease ≥25% from the pretreatment level or Fanconi syndrome. The ESG included patients having ≥2 of the following indicators of PRT: fractional excretion of phosphate (FEUP) ≥10%, low tubular maximum reabsorption of phosphate (TmP)/GFR, or uricosuria; fractional uric acid excretion ≥10%; urine protein-creatinine index (UPCI) ≥500 mg/g creatinine, normoglycemic glycosuria, or decrease in eGFR of 15%-24%. Recovery of proximal tubular function at 6 and 12 months after TDF discontinuation was assessed. Complete recovery was defined as normalization of all abnormal tubular markers.Results: Thirty-three HIV-infected patients were enrolled (70% male). Except for tubular function markers, baseline characteristics were not significantly different between the two groups. The proportion of patients having complete recovery was significantly higher in the ESG (p = 0.007, log-rank test). FEUP improved significantly in the ESG after TDF discontinuation; improvements of eGFR and UPCI were greater in the LSG. An eGFR change of 10% from baseline was the only independent predictor of failure to achieve complete recovery after switching. After median follow-up of 2.25 years post-trial, sustained recovery of eGFR within 5% of pre-TDF eGFR was achieved only in the ESG.Conclusions: Early-switching of TDF in HIV patients with PRT may allow complete recovery of proximal renal tubular function.

A 28-Day Toxicity Study of Tenofovir Alafenamide Hemifumarate by Subcutaneous Infusion in Rats and Dogs.

The toxicity of tenofovir alafenamide (TAF) hemifumarate (HF) was evaluated when administered by continuous subcutaneous (s.c.) infusion via an external infusion pump for 28 days to rats and dogs. The toxicokinetics of TAF and two metabolites, tenofovir (TFV) and tenofovir diphosphate (TFV-DP) were also evaluated. After administration of TAF HF in rats and dogs, primary systemic findings supported an inflammatory response that was considered minimal to mild. Gross pathology and histopathologic evaluation of tissue surrounding the s.c. infusion site revealed signs of inflammation, including edema, mass formation, fibrosis, and mononuclear cell inflammation in groups receiving ≥300 µg/kg/day in rats and ≥25 µg/day in dogs. Although these changes were observed in animals receiving vehicle, the severity was greater in animals receiving TAF HF. Changes in the local tissue were considered a TAF HF-mediated exacerbation of an inflammatory response to the presence of the catheter. In rats, systemic and local findings were considered not adverse due to their low severity and reversibility; therefore, the "no observed adverse effect level" (NOAEL) was set at 1,000 µg/kg/day. Because none of the systemic findings were related to systemic exposure to TAF, the systemic NOAEL was set at 250 µg/kg/day in dogs. Due to the severity of the observations noted, a NOAEL for local toxicity could not be established. Although these results might allow for exploration of tolerability and pharmacokinetics of s.c. administered TAF HF in humans, data suggest a local reaction may develop in humans at doses below a clinically relevant dose. IMPORTANCE Human immunodeficiency virus (HIV) infection continues to be a serious global human health issue, with ∼38 million people living with HIV worldwide at the end of 2019. HIV preexposure prophylaxis (PrEP) has introduced the use of antiretroviral therapies as another helpful tool for slowing the spread of HIV worldwide. One possible solution to the problem of inconsistent access and poor adherence to HIV PrEP therapies is the development of subcutaneous (s.c.) depots or s.c. implantable devices that continuously administer protective levels of an HIV PrEP therapy for weeks, months, or even years at a time. We evaluate here the toxicity of tenofovir alafenamide, a potent inhibitor or HIV replication, after continuous s.c. infusion in rats and dogs for HIV PrEP.

Bioequivalence Evaluation of Two Formulations of Tenofovir Alafenamide Tablets in Healthy Subjects Under Fasting and Fed Conditions.

PURPOSE: To evaluate the bioequivalence and safety of two formulations of 25 mg tenofovir alafenamide tablets in Chinese healthy male and female subjects under fed and fasting conditions. PATIENTS AND METHODS: This was a randomized, open-label, single-center, crossover study consisting of a fasting trial with two periods and a fed trial with four periods. In total, 42 healthy subjects were enrolled in the fasting trial and 32 healthy subjects were enrolled in the fed trial. In each period, blood samples for pharmacokinetic analysis were collected until 72 hours post-dose. The plasma concentrations of tenofovir alafenamide and tenofovir were measured and noncompartmental analysis was used to determine pharmacokinetic parameters. Throughout the entire study, subjects' safety was monitored by assessment of physical examinations, vital signs, 12-lead electrocardiography, clinical laboratory parameters, and treatment emergent adverse events (TEAEs). RESULTS: Forty subjects completed the fasting trial and 32 subjects completed the fed trial. The 90% confidence intervals (CIs) of the geometric mean ratios for AUC0-t, AUC0-∞, and Cmax for the two formulations were within 80.00% to 125.00%, which met the bioequivalence acceptance criteria. The study drugs were well tolerated by all subjects. CONCLUSION: This study demonstrated that the test formulation of 25 mg tenofovir alafenamide tablets was bioequivalent to the formulation marketed under the brand name VEMLIDY® in healthy Chinese male and female subjects under fasting and fed conditions.

Melatonin protects against tenofovir-induced nephrotoxicity in rats by targeting multiple cellular pathways.

Nephrotoxicity is a dose-limiting side effect of long-term use of tenofovir, a reverse transcriptase inhibitor that is used for the treatment of HIV infection and chronic hepatitis B infection. Identifying an agent that prevents tenofovir disoproxil fumarate (TDF)-induced renal injury can lead to its better tolerance, and a more effective treatment can be achieved. The present study is aimed at investigating whether melatonin, a potent antioxidant and anti-inflammatory agent, protects against TDF nephrotoxicity in rats and to determine its cellular targets. Rats were divided into groups and treated as follows. Group I (control): Rats in this group (n = 6) received sterile water only by gavage for 35 days. Group II: Rats (n = 6) in this group received 600 mg/kg body weight TDF in sterile water by gavage for 35 days. Group III: Rats (n = 6) in this group received once daily 20 mg/kg bodyweight melatonin i.p. 2 h before the administration of 600 mg/kg body weight TDF in sterile water by gavage for 35 days. Group IV: Rats were pretreated daily with 20 mg/kg body weight melatonin i.p. 2 h before the administration of sterile water by gavage. All the rats were sacrificed on the 36th day, after overnight fast. Melatonin pretreatment protected the rats against TDF nephrotoxicity both histologically and biochemically. Biochemically, melatonin pretreatment attenuated TDF-induced, oxidative stress, nitrosative stress, mitochondrial pathway of apoptosis, PARP overactivation and preserved proximal tubular function (p < 0.01). This suggests that melatonin may be useful in ameliorating TDF nephrotoxicity.

Identifying the role of PrimPol in TDF-induced toxicity and implications of its loss of function mutation in an HIV+ patient.

A key component of antiretroviral therapy (ART) for HIV patients is the nucleoside reverse transcriptase inhibitor (NRTI) is tenofovir. Recent reports of tenofovir toxicity in patients taking ART for HIV cannot be explained solely on the basis of off-target inhibition of mitochondrial DNA polymerase gamma (Polγ). PrimPol was discovered as a primase-polymerase localized to the mitochondria with repriming and translesion synthesis capabilities and, therefore, a potential contributor to mitochondrial toxicity. We established a possible role of PrimPol in tenofovir-induced toxicity in vitro and show that tenofovir-diphosphate incorporation by PrimPol is dependent on the n-1 nucleotide. We identified and characterized a PrimPol mutation, D114N, in an HIV+ patient on tenofovir-based ART with mitochondrial toxicity. This mutant form of PrimPol, targeting a catalytic metal ligand, was unable to synthesize primers, likely due to protein instability and weakened DNA binding. We performed cellular respiration and toxicity assays using PrimPol overexpression and shRNA knockdown strains in renal proximal tubular epithelial cells. The PrimPol-knockdown strain was hypersensitive to tenofovir treatment, indicating that PrimPol protects against tenofovir-induced mitochondrial toxicity. We show that a major cellular role of PrimPol is protecting against toxicity caused by ART and individuals with inactivating mutations may be predisposed to these effects.

In utero exposure to protease inhibitor-based antiretroviral regimens delays growth and developmental milestones in mice.

Antiretroviral therapy (ART) in pregnancy has dramatically reduced HIV vertical transmission rates. Consequently, there is a growing number of children that are HIV exposed uninfected (CHEUs). Studies suggest that CHEUs exposed in utero to ART may experience developmental delays compared to their peers. We investigated the effects of in utero ART exposure on perinatal neurodevelopment in mice, through assessment of developmental milestones. Developmental milestone tests (parallel to reflex testing in human infants) are reflective of brain maturity and useful in predicting later behavioral outcomes. We hypothesized that ART in pregnancy alters the in utero environment and thereby alters developmental milestone outcomes in pups. Throughout pregnancy, dams were treated with boosted-atazanavir combined with either abacavir/lamivudine (ATV/r/ABC/3TC), or tenofovir/emtricitabine (ATV/r/TDF/FTC), or water as control. Pups were assessed daily for general somatic growth and on a battery of tests for primitive reflexes including surface-righting, negative-geotaxis, cliff-aversion, rooting, ear-twitch, auditory-reflex, forelimb-grasp, air-righting, behaviors in the neonatal open field, and olfactory test. In utero exposure to either ART regimen delayed somatic growth in offspring and evoked significant delays in the development of negative geotaxis, cliff-aversion, and ear-twitch reflexes. Exposure to ATV/r/ABC/3TC was also associated with olfactory deficits in male and forelimb grasp deficits in female pups. To explore whether delays persisted into adulthood we assessed performance in the open field test. We observed no significant differences between treatment arm for males. In females, ATV/r/TDF/FTC exposure was associated with lower total distance travelled and less ambulatory time in the centre, while ATV/r/ABC/3TC exposure was associated with higher resting times compared to controls. In utero PI-based ART exposure delays the appearance of primitive reflexes that involve vestibular and sensory-motor pathways in a mouse model. Our findings suggest that ART could be disrupting the normal progress/maturation of the underlying neurocircuits and encourage further investigation for underlying mechanisms.