Tenofovir disoproxil fumarate (TDF) may induce renal proximal tubulopathy (rPT). There are no data on pharmacogenomic predictors of rPT in the genes encoding the multidrug-resistance protein (MRP) 2 and MRP4 transporters.
Mutational screening of the genes for MRP2 (ABCC2) and MRP4 (ABCC4) was performed using genomic DNA from 13 human immunodeficiency virus type 1 (HIV-1)-infected patients (group 1) presenting with TDF-induced rPT. Concomitantly, 17 unrelated HIV-1-infected patients who had received TDF therapy and who did not have rPT (group 2) were included in a case-control analysis, to assess the influence of single-nucleotide polymorphisms (SNPs) identified in ABCC2 and ABCC4.
Six SNPs were identified in ABCC2. A significant allelic association between the 1249 G-->A SNP and TDF-induced rPT was observed (odds ratio, 6.11 [95% confidence interval, 1.19-31.15]; P<.02). ABCC2 haplotypes were significantly associated with the onset of TDF-induced rPT--CATC appeared to be a predisposing haplotype, as it was found in 40.9% of the group 1 case patients and in 13.7% of the group 2 control subjects (P<.01), whereas CGAC appeared to be a protective haplotype, as it was not observed in the group 1 case patients but was present in 20.2% of the group 2 control subjects (P<.01). No association was observed between ABCC4 polymorphism and TDF-induced rPT in the present study.
ABCC2 haplotypes are associated with rPT induced by TDF in HIV-1-infected patients.
"This contrast with the higher frequency of Fanconi syndrome in HIV patients exposed to TDF where the risk of kidney injury associated to TDF is most likely multifactorial , and exaggerated by older age, lower body weight, pre-existing renal impairment, concomitant use of nephrotoxic medications and such co-morbidities as diabetes or arterial hypertension . However, the association of Fanconi syndrome with HIV may also depend on an interaction with the multidrug-resistance proteins 2 (MRP2) implicated in drug efflux at the apical surface of the proximal tubule whose altered function may lead to drug accumulation within tubular epithelial cells resulting in kidney tubular dysfunction   . Indeed, genetic polymorphisms of this protein encoded by the adenosine triphosphate-binding cassette (ABC) gene ABCC2, is strongly associated with development of kidney tubular dysfunction in TDF exposed individuals  . "
[Show abstract][Hide abstract] ABSTRACT: Tenofovir disoproxil fumarate (TDF) is a nucleotide reverse transcriptase inhibitor widely used to treat patients with human immunodeficiency virus (HIV) and hepatitis B virus (HBV) infection. Despite the excellent safety records of this regimen, a few cases of acute renal failure and Fanconi syndrome have been reported among HIV patients exposed to TDF. In the HBV monoinfection scenario, only two cases of TDF-associated Fanconi syndrome have been reported thus far. Here, we describe two additional patients with chronic hepatitis B (CHB) who developed a TDF-induced Fanconi syndrome that reverted after TDF withdrawal and had viral replication fully suppressed upon switching to entecavir (ETV). Though the overall risk of TDF associated severe renal toxicity in HBV patients appears to be negligible, both glomerular and tubular function should be monitored in patients exposed to TDF, especially when other renal risk factors or a history of previous exposure to adefovir dipivoxil (ADV) are present.
"Carrier-mediated cellular drug accumulation is a resultant of the activity of uptake and efflux transporters. The pharmacological significance of efflux transport proteins is evident considering their role in the development of resistance of tumor cells to chemotherapeutic agents (as, e.g., in the case of P-glycoprotein ) or in the induction of drug cellular toxicity because of their malfunction (as, e.g., in the case of multidrug resistance-associated protein 2 polymorphism ). The pharmacological and more specifically the toxicological role of uptake transporters in the development of specific drug adverse effects has been only in the recent years under critical investigation. "
[Show abstract][Hide abstract] ABSTRACT: Transporters are important mediators of specific cellular uptake and thus, not only for effects, but also for side effects, metabolism, and excretion of many drugs such as cisplatin. Cisplatin is a potent cytostatic drug, whose use is limited by its severe acute and chronic nephro-, oto-, and peripheral neurotoxicity. For this reason, other platinum derivatives, such as carboplatin and oxaliplatin, with less toxicity but still with antitumoral action have been developed. Several transporters, which are expressed on the cell membranes, have been associated with cisplatin transport across the plasma membrane and across the cell: the copper transporter 1 (Ctr1), the copper transporter 2 (Ctr2), the P-type copper-transporting ATPases ATP7A and ATP7B, the organic cation transporter 2 (OCT2), and the multidrug extrusion transporter 1 (MATE1). Some of these transporters are also able to accept other platinum derivatives as substrate. Since membrane transporters display a specific tissue distribution, they can be important molecules that mediate the entry of platinum derivatives in target and also nontarget cells possibly mediating specific effects and side effects of the chemotherapeutic drug. This paper summarizes the literature on toxicities of cisplatin compared to that of carboplatin and oxaliplatin and the interaction of these platinum derivatives with membrane transporters.
"Our results suggest that RBPCR results may need to be interpreted in the context of eGFR and ethnicity. The observed association between ethnicity and tubular biomarkers is of interest and suggests that tubular handling of LMWP may be different in patients of different ethnic backgrounds, or that the prevalence of genetic polymorphisms of the organic anion transporters and/or multi-drug resistant proteins, which have been implicated in the pathogenesis of cART-associated tubular dysfunction [27,40], may vary by ethnicity. Alternatively, a higher muscle mass in black patients may have resulted in higher urinary creatinine concentrations, and thus somewhat lower RBPCR, NGALCR and CCR values. "
[Show abstract][Hide abstract] ABSTRACT: Chronic kidney disease is common in HIV positive patients and renal tubular dysfunction has been reported in those receiving combination antiretroviral therapy (cART). Tenofovir (TFV) in particular has been linked to severe renal tubular disease as well as proximal tubular dysfunction. Markedly elevated urinary concentrations of retinal-binding protein (RBP) have been reported in patients with severe renal tubular disease, and low-molecular-weight proteins (LMWP) such as RBP may be useful in clinical practice to assess renal tubular function in patients receiving TFV. We analysed 3 LMWP as well as protein and albumin in the urine of a sample of HIV positive patients.
In a cross-sectional fashion, total protein, albumin, RBP, cystatin C, and neutrophil gelatinase-associated lipocalin (NGAL) were quantified in random urine samples of 317 HIV positive outpatients and expressed as the ratio-to-creatinine (RBPCR, CCR and NGALCR). Exposure to cART was categorised as none, cART without TFV, and cART containing TFV and a non-nucleoside reverse-transcriptase-inhibitor (TFV/NNRTI) or TFV and a protease-inhibitor (TFV/PI).
Proteinuria was present in 10.4 % and microalbuminuria in 16.7 % of patients. Albumin accounted for approximately 10 % of total urinary protein. RBPCR was within the reference range in 95 % of patients while NGALCR was elevated in 67 % of patients. No overall differences in urine protein, albumin, and LMWP levels were observed among patients stratified by cART exposure, although a greater proportion of patients exposed to TFV/PI had RBPCR >38.8 μg/mmol (343 μg/g) (p = 0.003). In multivariate analyses, black ethnicity (OR 0.43, 95 % CI 0.24, 0.77) and eGFR <75 mL/min/1.73 m2 (OR 3.54, 95 % CI 1.61, 7.80) were independently associated with upper quartile (UQ) RBPCR. RBPCR correlated well to CCR (r2 = 0.71), but not to NGALCR, PCR or ACR.
In HIV positive patients, proteinuria was predominantly of tubular origin and microalbuminuria was common. RBPCR in patients without overt renal tubular disease was generally within the reference range, including those receiving TFV. RBP therefore appears a promising biomarker for monitoring renal tubular function in patients receiving TFV and for distinguishing patients with normal tubular function or mild tubular dysfunction from those with severe renal tubular disease or Fanconi syndrome.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.