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A sensitive and rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous determination of tryptophan (Trp) and ten metabolites of kynurenine pathway, including kynurenine (Kyn), 3-hydroxy-kynurenine (3-HK), kynurenic acid (KA), xanthurenic acid (XA), 3-Hydroxy-anthranilic acid (3-HANA), quinolinic acid (QA), nicotinic acid mononucleotide (NaMN), picolinic acid (Pic), nicotinamide (NAM) and nicotinic acid (NA) in both plasma and urine. This LC-MS/MS method was used to predict the occurrence of acute kidney injury (AKI) in a cohort of patients with cardiac surgery under cardiopulmonary bypass (CPB). Urinary concentrations of Pic, as well as Pic to Trp and Pic to 3-HANA ratios were highly predictive of an AKI episode the week after CPB, indicating that Pic could be a predictive biomarker of AKI. Thus, monitoring the kynurenine pathway activity with this LC-MS/MS method is a clinically relevant tool to identify new biomarkers of kidney injury.

Thiopurines are drugs widely used for the treatment of autoimmune conditions, inflammatory bowel disease or acute lymphoblastic leukemia. Determination of thiopurine methyltransferase activity (TPMT), a major determinant of thiopurines toxicity, has been suggested before implementing thiopurine treatment. An ultraperformance liquid chromatography (UPLC) method was developed and validated for the quantification of TPMT enzyme activity based on the conversion of 6-mercaptopurine (6-MP) to 6-methylmercaptopurine (6-MMP) using S-adenosyl-L-methionine (SAM) as methyl donor in red blood cell lysates (RBC). This method was improved from a previous laborious high performance liquid chromatography (HPLC) method, using a lower volume of injection and with a shorter runtime. After incubation and protein precipitation 6-MMP was separated on a HSS-T3 (2.1 × 50 mm, 1.8 μm) column and monitored by UV detection (290 nm). A change on the organic solvent used to dissolve 6-MP resulted in a reduction of interference by endogenous or non-enzymatic methylated 6-MMP. A full validation of the 6-MMP assay was performed according to the FDA and EMA guidelines. The method was linear from 0.125 to 2 nmol/mL, with acceptable values of accuracy and precision. The method was applied in 106 patients treated with thiopurines whose TPMT activity was previously quantified by HPLC. Evaluation through Bland-Altman plot showed that TPMT activities were in agreement between both methods.

Each year in France, >75 000 patients receive fluoropyrimidines, including 5-fluorouracil (5-FU) and its oral prodrug capecitabine (Xeloda), to treat digestive, breast and head and neck cancers.1 Among them, ∼20% will experience severe hematological and digestive toxicities and

International audience; Any biochemical reaction underlying drug metabolism depends on individual gene-drug interactions and on groups of genes interacting together. Based on a high-throughput genetic approach, we sought to identify a set of covariant single-nucleotide polymorphisms predictive of interindividual tacrolimus (Tac) dose requirement variability. Tac blood concentrations (Tac C0 ) of 229 kidney transplant recipients were repeatedly monitored after transplantation over 3 mo. Given the high dimension of the genomic data in comparison to the low number of observations and the high multicolinearity among the variables (gene variants), we developed an original predictive approach that integrates an ensemble variable-selection strategy to reinforce the stability of the variable-selection process and multivariate modeling. Our predictive models explained up to 70% of total variability in Tac C0 per dose with a maximum of 44 gene variants (p-value

Background Neoadjuvant cisplatin-based chemotherapy (NAC) is the standard of care in non-metastatic muscle-invasive bladder cancer (MIBC). However, 60-75% patients have residual tumor after neoadjuvant cisplatin-gemcitabin or ddMVAC regimen. Pathological complete response (pCR) after NAC is correlated with overall survival (OS). Based on the overall response rate observed in the metastatic setting, ddMVAC is the most commonly used NAC regimen in Europe in urothelial carcinoma (UC) in fit patients. The emergence of immune checkpoint inhibitor (ICI) in the metastatic setting raises the question if the combination chemo plus ICI could increase the pCR rate. Trial design NEMIO is a French open-label randomized phase II trial assessing in the neoadjuvant setting the combination ddMVAC plus durvalumab (D) alone or in combination with tremelimumab (T): 4 cycles of ddMVAC every 2 weeks + 2 cycles of D (1500 mg) +/- T (75 mg) every 4 weeks. Cystectomy is performed 4-8 weeks after the last dose of ddMVAC. As no safety data are available on the ICI plus ddMVAC combination, 6 pts will be included in each arm in a safety run-in cohort to evaluate the toxicity rate of the 2 regimens. Each arm will be expanded to a maximum of 60 pts according to a Bayesian stopping rule based on grade 3/4 treatment-related adverse events (G 3/4 TRAE). The primary endpoint of the safety run-in phase will be the rate of G3/4 TRAE. The primary endpoint of the phase II will be the pCR rate and G3/4 TRAE. We hypothesized that pCR after ddMVAC + D +/- T will be > or = 45%. Exploratory endpoints will include biomarkers of response and resistance to the combo. Molecular analysis will be conducted on tumor, blood (ctDNA) and urine samples (uDNA). Immunological and metabolomics profile will also be analyzed. Seven patients have yet been enrolled since December 2018 from the 10 French participating centers and we expect the recruitment to be completed in 2021. Clinical trial identification NCT03549715. Legal entity responsible for the study Association pour la Recherche de Therapeutiques Innovantes en Cancerologie (ARTIC). Funding AstraZeneca. Disclosure C. Thibault: Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution), Travel / Accommodation / Expenses: AstraZeneca; Honoraria (self), Advisory / Consultancy: BMS; Travel / Accommodation / Expenses: Roche; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution), Travel / Accommodation / Expenses: Sanofi; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Janssen; Honoraria (self), Advisory / Consultancy: Astellas; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Pfizer. D. Borchiellini: Advisory / Consultancy, Research grant / Funding (institution): Roche; Advisory / Consultancy, Research grant / Funding (institution): MSD; Advisory / Consultancy: BMS; Advisory / Consultancy: Pfizer; Advisory / Consultancy, Research grant / Funding (institution): Janssen; Advisory / Consultancy, Research grant / Funding (institution): Astellas; Advisory / Consultancy: Sanofi; Advisory / Consultancy: Ipsen. O. Huillard: Honoraria (self): AstraZeneca; Honoraria (self): BMS; Honoraria (self): Janssen. P. Barthelemy: Advisory / Consultancy: BMS; Advisory / Consultancy: Pfizer; Advisory / Consultancy: Roche; Advisory / Consultancy: Janssen; Advisory / Consultancy: MSD; Advisory / Consultancy: Ipsen; Advisory / Consultancy: Novartis; Advisory / Consultancy: Sanofi. D. Pouessel: Advisory / Consultancy, Research grant / Funding (institution), Travel / Accommodation / Expenses: AstraZeneca; Advisory / Consultancy, Travel / Accommodation / Expenses: Pfizer; Advisory / Consultancy, Research grant / Funding (institution): Janssen; Research grant / Funding (institution): MSD; Research grant / Funding (institution): Roche; Research grant / Funding (institution): Incyte. A. Flechon: Advisory / Consultancy: BMS; Advisory / Consultancy: Pfizer; Advisory / Consultancy: AstraZeneca; Advisory / Consultancy: Roche; Advisory / Consultancy: MSD. H. Blons: Advisory / Consultancy: AstraZeneca; Advisory / Consultancy: Boehringer; Advisory / Consultancy: MSD. S. Oudard: Honoraria (self): BMS; Honoraria (self): MSD; Honoraria (self): AstraZeneca; Honoraria (self): Roche. All other authors have declared no conflicts of interest.

Adaptive responses to hypoxia, including hypoxia-inducible factor signaling, allow the cell to satisfy its basal metabolic demand and avoid death, but these responses can also be deleterious by promoting inflammation, cell dedifferentiation and fibrogenesis. Therefore, targeting hypoxia constitutes a promising therapeutic avenue. Recombinant human erythropoietin (rhEPO) appeared as a good candidate therapy because its hematopoietic properties could reverse anemia, and its tissue-protective properties could reduce cell death and limit maladaptive cellular responses to hypoxia. Despite experimental evidence on the nephroprotecive properties of rhEPO, recent clinical trials provided evidence that rhEPO was ineffective in preventing delayed graft function after ischemic acute injury but that the normalization of hemoglobin values preserved kidney function deterioration and reduced graft loss. Our aim here is to provide a survey of the rationale for evaluating the administration of rhEPO in the setting of kidney transplantation. We will discuss the intriguing findings that emerged from the clinical trials and the discrepancies between promising experimental results and negative clinical studies, as well as the differences in terms of the benefits and safety profiles of the normalization of hemoglobin values in chronic kidney disease patients and kidney transplant patients.

Transplanted organs have to cope with diverse immunologic and metabolic stressors that augment the percentage of stressed and dying cells. Cell death, whether apoptotic or necrotic, is crucial in various transplantation-associated conditions. Necrosis, a proinflammatory type of cell death classically considered as accidental, is increasingly recognized as a highly controlled death program. Apoptosis, the classical programmed cell death mode program, is tightly orchestrated and culminates in the activation of caspases. Apoptosis was classically regarded as a silent form of cell death, but mounting evidence indicates that apoptotic cells "don't go silently" and leave a heritage to the local microenvironment. This apoptotic legacy, embedded within the effector phase of apoptosis, is aimed, at least in part, at controlling leukocyte trafficking and fostering tissue remodeling at sites of apoptotic cell deletion and can promote maladaptive remodeling pathways of importance for obliterative vascular remodeling. Moreover, apoptotic cells can transfer bioactive molecules by the release of apoptotic membrane vesicles that, in turn, shapes the phenotype and functions of immune cells. In this review, we summarize recent data highlighting the importance of apoptosis-associated intercellular communication networks in the regulation of allograft remodeling and immune responses in transplantation.

Mutations of the UMOD gene, which encodes the uromodulin protein, are associated with tubulointerstitial nephritis and hyperuricemia. UMOD mutations impair uromodulin folding, resulting in its retention within the endoplasmic reticulum (ER) of renal tubular cells. The aim of this study was to investigate whether mutant uromodulin accumulation in epithelial tubular cells is associated with ER stress. We characterized tubular expression of uromodulin and the ER stress surrogate marker Grp78 by immunohistochemistry in kidney biopsy specimens from 7 patients with UMOD-related kidney disease. We compared this population with 5 patients with familial tubulointerstitial nephritis not related to UMOD mutation. All biopsy specimens from patients carrying the UMOD mutation showed strong heterogeneous cytoplasmic expression of uromodulin in cells of the thick ascending limb of the loop of Henle. In the same tubules, Grp78 was highly expressed in a perinuclear pattern. In contrast, in all kidney biopsy specimens from patients without UMOD mutations, uromodulin staining showed normal apical expression and Grp78 expression was not increased. Our observations support the hypothesis that ER accumulation of mutant uromodulin may cause ER stress, providing a potential mechanism for the progression of UMOD-related kidney disease.

The molecular mechanisms by which cyclosporine induces chronic nephrotoxicity remain poorly understood. A previous transcriptomic study suggested that cyclosporine might induce endoplasmic reticulum (ER) stress in human tubular cells. The aim of the present study was to characterize the features of tubular ER stress induced by cyclosporine and to investigate its effects on cell differentiation and viability. Using primary cultures of human tubular cells, we confirmed that cyclosporine is responsible for ER stress in vitro. This was also confirmed in vivo in the rat. In vitro, cyclosporine and other ER stress inducers were responsible for epithelial phenotypic changes leading to the generation of protomyofibroblasts, independent of transforming growth factor-beta signaling. RNA interference directed against cyclophilin A supported the role of its inhibition in triggering ER stress as well as epithelial phenotypic changes induced by cyclosporine. Salubrinal, which is known to protect cells from ER stress, significantly reduced epithelial phenotypic changes and cytotoxicity induced by cyclosporine in vitro. Salubrinal also reduced cyclosporine nephrotoxicity in rat kidneys. Thus, we describe a novel mechanism that initiates dedifferentiation and tubular cell death upon cyclosporine treatment. These results provide an interesting framework for further nephroprotective therapies by targeting ER stress.

Cyclosporine nephrotoxicity remains a major side effect in solid organ transplantation, and can be exacerbated by concomitant administration of sirolimus. Cyclosporine and sirolimus are P-glycoprotein (Pgp) substrates. We hypothesized that the Pgp activity level may affect cyclosporine cytotoxicity by interfering with the ability of Pgp to remove cyclosporine from within tubular cells, and that an interaction between cyclosporine and sirolimus on Pgp function may explain the enhancement of cyclosporine nephrotoxicity by sirolimus. Cyclosporine cytotoxicity was evaluated in primary cultures of normal human renal epithelial cells (HRECs) by cell viability and cytotoxicity assays. Verapamil, quinine, PSC833, and PGP-4008 were used as Pgp inhibitors. Rhodamine-123 (R-123), a fluorescent substrate of Pgp, was used to assess Pgp-mediated transport. Cellular cyclosporine concentration was measured by high-performance liquid chromatography coupled to tandem mass spectrometry. Pgp expression and function were confirmed in HRECs and cyclosporine and sirolimus were shown to be Pgp inhibitors in this model. Verapamil-induced inhibition of Pgp led to a significant increase in cellular concentration of cyclosporine (P

To the Editor: Proton nuclear magnetic resonance (1H-NMR) spectroscopy of urine is a noninvasive and highly reproducible method to discover biomarkers,1, 2 and to formulate hypotheses related to the pathogenesis of chronic kidney disease (CKD).3 In a cross-sectional study, Posada-Ayala et al.4 defined an 1H-NMR-based fingerprint of urine metabolites, including citrate and threonine, found differentially altered in 36 CKD patients compared with controls. We have characterized the urinary 1H-NMR-based metabolome of 111 consecutive CKD patients referred at our center for a kidney biopsy (indicated if glomerular filtration rate (GFR) 0.5 g/l and/or presence of hematuria) between 2012 and 2013. 1H-NMR measurements were performed on a Bruker 500 MHz spectrometer with a 5-mm BBI probe, and the spectra were divided into 0.04 p.p.m. buckets. An orthogonal partial least square discriminant analysis using estimated GFR (eGFR) 90 ml/min were included in the model as classifiers, the clustering was even better (Figure 1c), and the buckets with the higher contribution to the principal component were also those corresponding to citrate and threonine (Figure 1d).

To the Editor: Havasi and Borkan1 discussed recent observations that link apoptosis to cell deletion and loss of organ function after acute kidney injury. Although the major consequence of apoptosis is cell death, emerging evidence suggests that apoptosis is involved in tissue remodeling and fibrogenesis.