Atomic Force Microscopy Application for the Measurement of Infliximab Concentration in Healthy Donors and Pediatric Patients with Inflammatory Bowel Disease

The use of infliximab has completely changed the therapeutic landscape in inflammatory bowel disease. However, despite its proven efficacy to induce and maintain clinical remission, increasing evidence suggests that treatment failure may be associated with inadequate drug blood concentrations. The introduction of biosensors based on different nanostructured materials for the rapid quantification of drugs has been proposed for therapeutic drug monitoring. This study aimed to apply atomic force microscopy (AFM)-based nanoassay for the measurement of infliximab concentration in serum samples of healthy donors and pediatric IBD patients. This assay measured the height signal variation of a nanostructured gold surface covered with a self-assembled monolayer of alkanethiols. Inside this monolayer, we embedded the DNA conjugated with a tumor necrosis factor able to recognize the drug. The system was initially fine-tuned by testing known infliximab concentrations (0, 20, 30, 40, and 50 nM) in buffer and then spiking the same concentrations of influximab into the sera of healthy donors, followed by testing pediatric IBD patients. A good correlation between height variation and drug concentration was found in the buffer in both healthy donors and pediatric IBD patients (p-value < 0.05), demonstrating the promising use of AFM nanoassay in TDM

A new proof of evidence of cysteamine quantification for therapeutic drug monitoring in patients with cystinosis

Background To date, measurement of intracellular cystine is used for the therapeutic monitoring of patients affected by cystinosis in treatment with cysteamine. Since this method is time and sample consuming, development of a faster method to quantify cysteamine would be extremely useful in order to help clinicians to adjust dosages of cysteamine and to define better the pharmacokinetic profile of this drug. The aim of the study was to develop a liquid chromatography tandem mass spectrometry method for the quantification of cysteamine in plasma samples and to test its applicability on plasma samples derived from patients with nephropathic infantile cystinosis in treatment with cysteamine. Results The percentage of accuracy of the developed method varied between 97.80 and 106.00% and CV% between 0.90 and 6.93%. There was no carry over. The calibration curves were built from 2.5 to 50 mu M. The limit of detection and the lower limit of quantification occurred at 0.25 and 1.25 mu M respectively. Cysteamine was stable up to 2 months at -20 degrees C. Concentrations of cysteamine and intracellular cystine of 4 patients were in line with data previously reported. Conclusion The proposed method showed an appropriate selectivity, specificity, linearity, sensibility, accuracy, precision and good applicability to samples

Role of Oxidative Stress Mediated by Glutathione-S-transferase in Thiopurines' Toxic Effects

Azathioprine (AZA), 6-mercaptopurine (6-MP), and 6-thioguanine (6-TG) are antimetabolite drugs, widely used as immunosuppressants and anticancer agents. Despite their proven efficacy, a high incidence of toxic effects in patients during standard-dose therapy is recorded. The aim of this study is to explain, from a mechanistic point of view, the clinical evidence showing a significant role of glutathione-S-transferase (GST)-M1 genotype on AZA toxicity in inflammatory bowel disease patients. To this aim, the human nontumor IHH and HCEC cell lines were chosen as predictive models of the hepatic and intestinal tissues, respectively. AZA, but not 6-MP and 6-TG, induced a concentration-dependent superoxide anion production that seemed dependent on GSH depletion. N-Acetylcysteine reduced the AZA antiproliferative effect in both cell lines, and GST-M1 overexpression increased both superoxide anion production and cytotoxicity, especially in transfected HCEC cells. In this study, an in vitro model to study thiopurines' metabolism has been set up and helped us to demonstrate, for the first time, a clear role of GST-M1 in modulating AZA cytotoxicity, with a close dependency on superoxide anion production. These results provide the molecular basis to shed light on the clinical evidence suggesting a role of GST-M1 genotype in influencing the toxic effects of AZA treatment

PACSIN2 as a modulator of autophagy and mercaptopurine cytotoxicity: mechanisms in lymphoid and intestinal cells

PACSIN2 variants are associated with gastrointestinal effects of thiopurines and thiopurine methyltransferase activity through an uncharacterized mechanism that is postulated to involve auto-phagy. This study aims to clarify the role of PACSIN2 in autophagy and in thiopurine cytotoxicity in leukemic and intestinal models. Higher autophagy and lower PACSIN2 levels were observed in inflamed compared with non-inflamed colon biopsies of in-flammatory bowel disease pediatric patients at diagnosis. PAC-SIN2 was identified as an inhibitor of autophagy, putatively through inhibition of autophagosome formation by a protein- protein interaction with LC3-II, mediated by a LIR motif. Moreover, PACSIN2 resulted a modulator of mercaptopurine-induced cyto-toxicity in intestinal cells, suggesting that PACSIN2-regulated autophagy levels might influence thiopurine sensitivity. However, PACSIN2 modulates cellular thiopurine methyltransferase activity via mechanisms distinct from its modulation of autophagy

PACSIN2 modifies miRNAs in extracellular vesicles, modulating thiopurine response

Thiopurines, such as mercaptopurine, are antimetabolites, used in the treatment of acute lymphoblastic leukemia (ALL) and inflammatory bowel disease (IBD). PACSIN2 rs2413739 is associated with gastrointestinal toxicity in children with ALL and with drug-efficacy in IBD pediatric patients. PACSIN2 is involved in vesicular trafficking and may affect the release and content of extracellular vesicles (EVs), which mediate cell communication and whose cargo modifies phenotypes of target cells. This study evaluates mechanisms associating PACSIN2 polymorphism with interindividual variability in efficacy of thiopurines, by considering the role of PACSIN2 in sorting specific miRNA in EVs. Effects of stable PACSIN2 knock-down (KD) were evaluated in intestinal LS180 cells. MTT cytotoxicity assay was used to verify mercaptopurine-sensitivity. EVs, released by LS180 KD and MOCK control cells were isolated by ultracentrifuge and characterized by nanoparticle tracking analysis (NTA). EVs miRNA-sequencing was performed by Illumina Hi-seq 2000. EVs may alter drug cytotoxicity, therefore LS180 MOCK and KD cells were co-treated with mercaptopurine and EVs. Statistical analysis was performed using t-test and ANOVA. Mercaptopurine was more cytotoxicity in LS180 KD cells (IC50 MOCK 3.23; IC50 KD 2.18 μM). No differences were observed by NTA in release of EVs between MOCK and KD cells (t-test, p = 0.13). PACSIN2 KD altered intracellular and EVs expression of 6 and 24 miRNAs respectively. EVs released by reduced mercaptopurine cytotoxicity (about 10%) and Rac1 protein expression in KD cells (ANOVA, p < 0.001), probably because they transport different miRNAs. In conclusion, PACSIN2 KD increase mercaptopurine cytotoxicity, probably, by deregulation of miRNA expression in cells and EVs. These results will be further investigated to better explain the link between PACSIN2 and EVs, whose miRNAs could provide a new scenario in personalizing thiopurine treatment.Book of abstract: 4th Belgrade Bioinformatics Conference, June 19-23, 202

Carbamazepine-induced thrombocytopenic purpura in a child: Insights from a genomic analysis

To the Editor, Carbamazepine is an effective anticonvulsant and has a relatively low incidence of adverse effects, although it occasionally causes hema- tologic disorders. We herein describe a patient with carbamazepine- induced thrombocytopenic purpura that was investigated by pharma- cological, immunological and genomic assays

Expression pattern of long non-coding RNA growth arrest-specific 5 in the remission induction therapy in childhood acute lymphoblastic leukemia

Uvod: Ekspresija duge nekodirajuće RNK G AS5 je izme - njena u mnogim kancerima zbog njene uloge u apoptozi i inhibiciji rasta ćelije. G AS5 interaguje sa glukokortikoidnim receptorom, što je čini potencijalnim farmakotranskripcionim markerom značajnim za glukokortikoidnu terapiju. Naš cilj u ovoj studiji je bio da analiziramo ekspresiju GAS5 tokom indukcione terapije kod dečje akutne limfoblastne leukemije (ALL), u kojoj se koriste glukokortikoidni lekovi, i da te rezultate povežemo sa odgovorom na terapiju. Metode: Nivo ekspresije G AS5 u mononuklearnim ćelijama periferne krvi izolovanih od 29 dece obolelih od ALL, određen je metodologijom RT-qPCR, i to u momentu dijagnoze, 15. i 33. dana indukcione terapije. Rezultati: Naši rezultati su pokazali da postoje interindivi - dualne razlike u ekspresiji GAS5 kod pacijenata, i to u svim analiziranim tačkama. Kod svakog ALL pacijenta GAS5 ekspresija je 15. dana bila visa u odnosu na ekspresiju u momentu dijagnoze (p lt 0,0005). Nivo ekspresije GAS5 je 33. dana bio niži u poređenju sa 15. danom (p lt 0,0005), ali je i dalje bio značajno visi u odnosu na momenat dijagnoze kod većine pacijenata (p = 0,001). Pacijenti čiji je broj blasta u perifernoj krvi 8. dana bio ispod 100 po mikrolitru periferne krvi, imali su viši nivo ekspresije GAS5 (p = 0,016) i niži odnos ekspresija merenih 15. dana i u momentu dijagnoze (p = 0,009). Zaključak: Nasi rezultati ukazuju da bi nivo ekspresije GAS5 mogao da bude marker terapijskog odgovora u indukcionoj terapiji kod dece obolele od ALL.Background: Long non-coding RNA growth arrest-specific 5 (GAS5) is deregulated in many cancers because of its role in cell growth arrest and apoptosis. Additionally, GAS5 interacts with glucocorticoid receptor, making it a potential pharmacotranscription marker of glucocorticoid (GC) therapy. In this study, we aimed at analysing G AS5 expression in the remission induction therapy phase of childhood acute lymphoblastic leukemia (ALL), in which GCs are mandatorily used, and to correlate it with therapy response. Methods: G AS5 expression was measured in peripheral blood mononuclear cells taken from 29 childhood ALL patients at diagnosis, on day 15 and day 33 of remission induction therapy using RT-qPCR methodology. Results: Our results have shown interindividual differences in G AS5 expression at all time points. For each ALL patient, G A S5 expression was higher on day 15 in comparison to its level at diagnosis (p lt 0.0005). On day 33, the level of G A S5 expression decreased in comparison with day 15 (p lt 0.0005), but it was still significantly higher than at diagnosis for the majority of patients (p=0.001). Patients whose number of blasts on day 8 was below 100 per mL of peripheral blood had a higher GAS5 expression at diagnosis (p=0.016), and lower ratio day 15/diagnosis (p=0.009). Conclusions: Our results suggest that the expression level of GAS5 could be a potential marker of therapy response in remission induction therapy of childhood ALL

Pharmacokinetics and pharmacodynamics of thiopurines in an in\ua0vitro model of human hepatocytes: Insights from an innovative mass spectrometry assay

AIM: To apply an innovative LC-MS/MS method to quantify thiopurine metabolites in human hepatocytes and to associate them to cytotoxicity. METHODS: Immortalized human hepatocytes (IHH cells) were treated for 48 and 96 h, with 1.4 7 10-4 M azathioprine and 1.1 7 10-3 M mercaptopurine, concentrations corresponding to the IC50 values calculated after 96 h exposure in previous cytotoxicity analysis. After treatments, cells were collected for LC-MS/MS analysis to quantify 11 thiopurine metabolites with different level of phosphorylation and viable cells were counted by trypan blue exclusion assay to determine thiopurines in vitro effect on cell growth and survival. Statistical significance was determined by analysis of variance (ANOVA). RESULTS: Azathioprine and mercaptopurine had a significant time-dependent cytotoxic effect (p-value ANOVA = 0.012), with a viable cell count compared to controls of 55.5% and 67.5% respectively after 48 h and 23.7% and 36.1% after 96 h; no significant difference could be observed between the two drugs. Quantification of thiopurine metabolites evidenced that the most abundant metabolite was TIMP, representing 57.1% and 40.3% of total metabolites after 48 and 96 h. Total thiopurine metabolites absolute concentrations decreased over time: total mean content decreased from 469.9 pmol/million cells to 83.6 pmol/million cells (p-value ANOVA = 0.0070). However, considering the relative amount of thiopurine metabolites, TGMP content significantly increased from 11.4% cells to 26.4% (p-value ANOVA = 0.017). A significant association between thiopurine effects and viable cell counts could be detected only for MeTIMP: lower MeTIMP concentrations were associated with lower cell survival (p-value ANOVA = 0.011). Moreover, the ratio between MeTIMP and TGMP metabolites directly correlated with cell survival (p-value ANOVA = 0.037). CONCLUSION: Detailed quantification of thiopurine metabolites in a human hepatocytes model provided useful insights on the association between thioguanine and methyl-thioinosine nucleotides with cell viability

Multicentric Case-Control Study on Azathioprine Dose and Pharmacokinetics in Early-onset Pediatric Inflammatory Bowel Disease

BACKGROUND: Early-onset inflammatory bowel disease (IBD) is generally aggressive, with a high probability of complications and need of surgery. Despite the introduction of highly effective biological drugs, treatment with azathioprine continues to be important even for early-onset IBD; however, in these patients azathioprine response seems to be reduced. This study evaluated azathioprine doses, metabolite concentrations, and their associations with patients' age in children with IBD treated at 6 tertiary pediatric referral centers. METHODS: Azathioprine doses, metabolites, and clinical effects were assessed after at least 3 months of therapy in 17 early-onset (age 12 and <18 yrs, controls) patients with IBD. Azathioprine dose was titrated on therapeutic efficacy (response and adverse effects). Azathioprine metabolites and thiopurine methyltransferase activity were determined by high-performance liquid chromatography with ultra violet-vis detection (HPLC-UV) methods. RESULTS: Frequency of patients in remission was similar among early-onset and control groups, respectively (82% and 84%, P value = 0.72). Early-onset patients required higher doses of azathioprine (median 2.7 versus 2.0 mg\ub7kg\ub7d, P value = 1.1 7 10). Different doses resulted in comparable azathioprine active thioguanine nucleotide metabolite concentrations (median 263 versus 366 pmol/8 7 10 erythrocytes, P value = 0.41) and methylmercaptopurine nucleotide concentrations (median 1455 versus 1532 pmol/8 7 10 erythrocytes, P value = 0.60). Lower ratios between thioguanine nucleotide metabolites and azathioprine doses were found in early-onset patients (median 98 versus 184 pmol/8 7 10 erythrocytes\ub7mg\ub7kg\ub7d, P value = 0.017). Interestingly, early-onset patients presented also higher thiopurine methyltransferase activity (median 476 versus 350 nmol methylmercaptopurine/mg hemoglobin/h, P-value = 0.046). CONCLUSIONS: This study demonstrated that patients with early-onset IBD present increased inactivating azathioprine metabolism, likely because of elevated activity of the enzyme thiopurine methyltransferase

In Vivo Response to Methotrexate Forecasts Outcome of Acute Lymphoblastic Leukemia and Has a Distinct Gene Expression Profile

William Evans and colleagues investigate the genomic determinants of methotrexate resistance and interpatient differences in methotrexate response in patients newly diagnosed with childhood acute lymphoblastic leukemia