Amedeo De Nicolò

Association of ITPA polymorphisms rs6051702/rs1127354 instead of rs7270101/rs1127354 as predictor of ribavirin-associated anemia in chronic hepatitis C treated patients

Functional variants rs7270101 and rs1127354 of inosine triphosphatase (ITPA) were recently found to protect against ribavirin (RBV)-induced hemolytic anemia. However, no definitive data are yet available on the role of no functional rs6051702 polymorphism. Since a simultaneous evaluation of the three ITPA SNPs for hemolytic anemia has not yet been investigated, we aimed to understand the contribution of each SNPs and its potential clinical use to predict anemia in HCV treated patients. A retrospective analysis included 379 HCV treated patients. The ITPA variants rs6051702, rs7270101 and rs1127354 were genotyped and tested for association with achieving anemia at week 4. We also investigated, using multivariate logistic regression, the impact of each single and paired associated polymorphism on anemia onset. All SNPs were associated with Hb decrease. The carrier of at least one variant allele in the functional ITPA SNPs was associated with a lower decrement of Hb, as compared to patients without a variant allele. In multivariate logistic regression analyses the carrier of a variant allele in the rs6051702/rs1127354 association (OR=0.11, p=1.75×10(-5)) and Hb at baseline (OR=1.51, p=1.21×10(-4)) were independently associated with protection against clinically significant anemia at week 4. All ITPA polymorphisms considered were shown to be significantly associated with anemia onset. A multivariate regression model based on ITPA genetic polymorphisms was developed for predicting the risk of anemia. Considering the characterization of pre-therapy anemia predictors, rs6051702 SNP in association to rs1127354 is more informative in order to avoid this relevant adverse event.

Sequential therapy with entecavir and PEG-INF in patients affected by chronic hepatitis B and high levels of HBV-DNA with non-D genotypes

Complete eradication of hepatitis B virus (HBV) is rarely achieved. Treatment options include currently available nucleos(t)ide analogues and pegylated interferon. The aim of our exploratory study was to assess the effectiveness of sequential therapy for chronic hepatitis B (CHB) vs the current standard of care. We evaluated an association with entecavir and pegylated interferon alfa‐2a (PEG‐IFN) in 20 patients with hepatitis B, high HBV viremia and genotypes A, B, C and E. Patients received entecavir alone for 12 weeks, then entecavir and PEG‐IFN for 12 weeks, lastly PEG‐IFN alone for 36 weeks. The results were compared with 20 patients (control group) treated in the past with 48 weeks of PEG‐IFN monotherapy. Our results show that complete sustained virological response (SVR) and partial SVR were, respectively, 60% and 80% in the study group and 10% and 30% in the control group; anti‐HBe seroconversion rate were 76.9% vs 15%, and anti‐HBs seroconversion were 20% vs 0%, respectively. We found a correlation among different genotypes and virological and serological outcomes – genotype C has a better virological response, while genotype A had a better serological response, and E genotype had a poor response. These results show that a sequential approach is a promising strategy of treatment in patients with CHB and high viremia in comparison with PEG‐IFN monotherapy. The E genotype seems to have the worse rate of response and requires other treatment strategies.

A UPLC-MS/MS method for the simultaneous plasma quantification of all isomeric forms of the new anti-HCV protease inhibitors boceprevir and telaprevir.

HCV infection affects over 170 milions people in the world. Up to now standard-of-care therapy consisted in ribavirin plus interferon-α 2a or 2b. Recently, two new Direct Acting Antivirals (DAA), inhibitors of NS3 HCV protease, have been developed and approved for the routine use on HCV genotype 1 infected patients: boceprevir and telaprevir. Protease inhibitors show complex pharmacokinetics (strong metabolism of both drugs by CYP3A and drug interactions), they require a TID dosage and, furthermore, they are present in plasma patients in two different isomeric forms. In this work, we developed and validated an UPLC-tandem mass spectrometry assay method capable of monitoring the telaprevir and boceprevir concentrations in plasma, discriminating each isomer of both drugs. Blank plasma used for Standards and QCs preparation, was obtained from blood of healthy donors. The calibration curves for each isomer of telaprevir and boceprevir were linear in a range from 46.87 ng/mL to 6000 ng/mL and from 23.43 to 3000 ng/mL, respectively (mean r(2)>0.998 for all analytes). QCs at three different concentration were prepared: High, Medium and Low. Each Standard, QC and patient sample was treated with a protein precipitation protocol with a solution containing acidified acetonitrile and Internal Standard (6,7-Dimethyl-2,3-di(2-pyridyl)quinoxaline). An aliquot of supernatant was diluted and then directly analyzed by reverse-phase UPLC-MS/MS. Accuracy (mean 98.47%), intra-day (mean <5.21%) and inter-day (mean <7.57%) precision for telaprevir and boceprevir quality controls fitted all FDA guidelines. All compounds resulted stable in our method conditions and the extraction procedure showed a recovery near to 100%. Finally, we tested this method by monitoring plasma concentrations in 9 HCV+ patients, for each triple combined therapy, with good results. The observed median ratio between S and R isomers for boceprevir and telaprevir were 1.22 (IQR 1.10-1.33) and 1.52 (IQR 1.21-1.67), respectively. The use of this simple assay method could be an important tool for management of HCV-1 DAAs treated patients.

Development and validation of a useful HPLC-UV method for quantification of total and phosphorylated-ribavirin in blood and erythrocytes of HCV+ patients.

Ribavirin-induced hemolytic anemia is the main cause of discontinuation of the combination therapy with alpha-interferon-2b and ribavirin for the treatment of hepatitis C virus (HCV) infection. The determination of intracellular ribavirin levels in blood, including the levels of its phosphorylated metabolites, might be useful for predicting ribavirin-induced anemia, which could be caused by the accumulation of these molecules within the erythrocytes. In this work, we simplified and validated a previously developed assay method, to make it suitable for routine monitoring of cellular ribavirin. Whole blood diluted with a five-fold volume of ice-cold distilled underwent a process of acid phosphatase digestion to convert phosphorylated ribavirin metabolites to free ribavirin. The resulting mixture, spiked with an internal standard, was treated with a protein precipitation protocol in acetonitrile, followed by reverse-phase high-performance liquid chromatography analysis. The calibration curve for ribavirin levels in whole blood was linear at concentrations from 625 to 320,000 ng/mL (r(2)=0.998). Accuracy, intra-day and inter-day precision for ribavirin and phosphorylated-ribavirin quality controls were all below 9.0%. We tested this method by monitoring blood ribavirin concentrations in 13 HCV+ patients, receiving alpha interferon-plus ribavirin combination therapy.

Development and validation of a useful UPLC-MS/MS method for quantification of total and phosphorylated-ribavirin in peripheral blood mononuclear cells of HCV+ patients.

The current standard-of-care therapy in HCV consists in ribavirin (RBV) plus pegylated-interferon-α 2a or 2b and, for HCV-1 infected patients, also directly acting antivirals (DAAs). Despite the increase in the number of patients who reach sustained virological response (SVR) for HCV-1, a great inter-individual variability in the response to therapy remains. Whether new drugs are available in combination with RBV and Peg-IFN for HCV-1, the treatment of the other viral genotypes remains the same: this issue highlights the lasting importance of RBV and Peg-IFN in anti-HCV treatment. Moreover, a strong limiting factor to the usefulness of anti-HCV treatment remains the occurrence of adverse events, first of all hemolytic anemia, which have increased with the addition of DAAs, but is mainly an RBV-dependent effect. For these reasons, the monitoring of RBV exposure in the various compartments should be important. Since the routinely determination of RBV in the target cells as the hepatocytes is impracticable for of its invasiveness, the quantification in easier to obtain cells could be a good choice. In this work, we developed and validated an ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) assay method to quantify RBV concentrations in peripheral blood mononucleated cells (PBMCs). QCs were prepared with RBV and RBV-monophosphate (RMP). Each sample was divided into two aliquots, which undergone the same extraction procedure: one was treated with acid phosphatase to convert RBV phosphorylated metabolites into free RBV, the other one was not-treated. The extracts were analyzed with reverse-phase column with UPLC-MS/MS. Calibration curves fitted a least squares model (weighed 1/X) for ribavirin levels in a range from 0.1 ng to 200 ng (mean r(2)=0.9993). Accuracy, intra-day and inter-day precision of the methods were in accordance with FDA guidelines. Moreover, phosphorylated QCs were used to assess the correct determination of total RBV concentration. We tested this method by monitoring RBV concentrations in PBMCs from 20 HCV+ patients, receiving alpha interferon-plus RBV combination therapy. This method showed to be reliable, precise, accurate and suitable for evaluation of intracellular RBV concentrations.

UPLC-MS/MS method for quantification of the azathioprine metabolites 6-mercaptoguanosine and 6-methylmercaptopurine riboside in peripheral blood mononuclear cells.

In the treatment of inflammatory bowel diseases, the use of azathioprine is increasing over the time. It has been demonstrated that the effectiveness of this therapy is modulated by the metabolism of azathioprine, which is mainly exerted by both thiopurine methyl-transferase and inosine triphosphatase enzymes. Several studies reported chromatographic methods to determine the amount of its metabolites in erythrocytes, but there are not reported methods to dose them in peripheral blood mononuclear cells (PBMCs). The development of a method capable to quantify azathioprine nucleoside metabolites in this compartment could give better information on drug penetration and metabolism in the active site. In this work, we validated a new chromatographic method suitable for the monitoring of the two major biologically active ribonucleos(t)ide metabolites of azathioprine in PBMCs: 6-thioguanosine and 6-methyl-mercaptopurine riboside. After PBMCs extraction from blood through separation on density gradient, samples underwent a de-phosphorylation procedure with acid phosphatase (only one aliquot for each sample) and were then treated with a protein precipitation protocol in acetonitrile, followed by UPLC-tandem-mass spectrometry analysis. The calibration curve for each metabolite in PBMC fitted a least squares model (weighed 1/X) from 0.048 to 25ng (r(2)=0.998). Both accuracy and precision parameters fitted FDA guidelines. We tested this method by monitoring the concentrations of each metabolite in PBMC from eight inflammatory bowel diseases affected patients, receiving azathioprine maintenance therapy with optimal results.

Pharmacogenetics of ribavirin-induced anemia in HCV patients.

Dual therapy (pegylated interferon plus ribavirin) was considered the standard of care for hepatitis C virus (HCV) treatment until 2011, when the first-wave direct-acting antivirals were added to this regimen for HCV genotype-1 patients to increase the sustained virological response rate. The second-wave direct-acting antivirals entered the clinical use also in some ribavirin (RBV)- and/or interferon-free combinations. Nevertheless, since some of the new therapeutic regimens also include RBV and its use results still associated with hemolytic anemia, this requires countermeasures to be prevented. These include the identification of several host predictive factors involved in RBV absorption, distribution, metabolism, elimination and many others that might influence this toxic effect. For this reason, we provided an overview of the potential role of pharmacogenomics in predisposing RBV-treated HCV patients to anemia.

Telaprevir-S isomer enhances ribavirin exposure and the ribavirin-related haemolytic anaemia in a concentration-dependent manner

The standard-of-care for the treatment of genotype-1 chronic hepatitis C is based on the combination of direct acting antivirals, such as boceprevir and telaprevir, with ribavirin and pegylated-interferon alfa. These triple regimens give a higher response rate than dual therapy, but on the other hand show a more than 10% higher rate of anaemia. Not enough focus has been given to the interaction between telaprevir and RBV. In this work, we aimed to study and deepen this relationship by comparing ribavirin plasma and intra-erythrocytic concentrations at one month of triple and dual therapy (17 vs. 119 patients). Moreover, we determined telaprevir isomers concentrations and tested them for correlation with ribavirin concentrations and haemoglobin loss at one month of treatment. Finally, all drugs concentration data were tested for their correlation with the renal function during treatment. The comparisons of ribavirin concentration and toxicity data were repeated on a sub-group of 9 patients who had been treated 1 year before with dual therapy and then re-treated with triple therapy. The observed ribavirin plasma and intra-erythrocytic concentrations in triple therapy were significantly higher compared to dual therapy, both in whole group and sub-group comparison. Ribavirin concentrations were significantly correlated to the haemoglobin loss and telaprevir-S isomer concentrations (r(2)=0.317 P(value)=0.023 and r(2)=0.388 P(value)=0.008, respectively). Renal function had a significant decrease from the baseline value, but was not significantly correlated with drugs concentrations. These results highlight for the first time that, in the context of triple therapy with telaprevir, ribavirin exposure is related to the telaprevir-S isomer plasma concentration. We conclude that the addition of telaprevir to the dual therapy increases ribavirin exposure and haemoglobin loss: this effect could probably be managed through the therapeutic drug monitoring of ribavirin and telaprevir-S concentrations.

Intracellular accumulation of boceprevir according to plasma concentrations and pharmacogenetics.

Boceprevir (BOC) is a directly-acting antiviral agent for the treatment of hepatitis C virus genotype 1 (HCV-1) infection. It is a mixture of two stereoisomers, the inactive R and the active S isomers. No data have previously been published on BOC intracellular accumulation. In this study, BOC isomer concentrations in peripheral blood mononuclear cells (PBMCs) and plasma were determined. The influence of various single nucleotide polymorphisms (SNPs) on plasma and intracellular drug exposure at Week 4 of triple therapy were also evaluated. Plasma and intracellular BOC concentrations were determined at the end of the dosing interval (C(trough)) using a UPLC-MS/MS validated method. Allelic discrimination was performed through real-time PCR. Median plasma concentrations were 65.97 ng/mL for the S isomer and 36.31 ng/mL for the R isomer; the median S/R plasma concentration ratio was 1.66. The median PBMC concentration was 2285.88 ng/mL for the S isomer; the R isomer was undetectable within PBMCs. The median S isomer PBMC/plasma concentration ratio was 28.59. A significant positive correlation was found between plasma and PBMC S isomer concentrations. ABCB1 1236, SLC28A2 124 and IL28B rs12979860 SNPs were associated with the S isomer PBMC/plasma concentration ratio. In regression models, S isomer plasma levels and FokI polymorphism were able to predict S isomer intracellular exposure, whereas SNPs in AKR1, BCRP1 and SLC28A2 predicted the S isomer PBMC/plasma concentration ratio. No similar data regarding BOC pharmacogenetics and pharmacokinetics have been published previously. This study adds a novel and useful overview of the pharmacological properties of this drug.

ABCB11 and ABCB1 gene polymorphisms impact on telaprevir pharmacokinetic at one month of therapy

In 2011 direct-acting antivirals, including telaprevir, have been developed to achieve a better antiviral effect. It was reported that telaprevir is a substrate of P-glycoprotein (ABCB1) and cytochrome P450 3A4. The aim of this retrospective study was the evaluation of the influence of some single nucleotide polymorphisms (SNPs) of genes (ABCB1, SLC28A2/3, SLC29A1) involved in TLV and RBV transport and their correlation with plasma TLV drug exposure at 1 month of therapy. We also investigated the association of a SNP in ABCB11 gene, whose role in TLV transport was not yet shown. Twenty-nine HCV-1 patients treated with telaprevir, ribavirin and pegylated-interferon-α were retrospectively analyzed; allelic discrimination was performed by real-time PCR. Telaprevir Ctrough levels were influenced by Metavir score (P=0.023), ABCB1 2677 G>T (P=0.006), ABCB1 1236 C>T (P=0.015) and ABCB11 1131 T>C (P=0.033) SNPs. Regarding ABCB1 3435 C>T, a not statistically significant trend in telaprevir plasma concentration was observed. Metavir score (P=0.002, OR -336; 95% CI -535;-138), ABCB1 2677 (P=0.020, OR 497; 95% CI 86; 910), ABCB11 1131 (P=0.002, OR 641; 95% CI 259;1023) and CNT2 -146 (P=0.006, OR -426; 95% CI -721;-132) were able to predict telaprevir plasma levels in the regression analysis. Other SNPs showed no association. This study reveals BSEP implication in telaprevir transport and confirms the involvement and influence of P-glycoprotein on telaprevir plasma levels. To date, no similar data concerning pharmacogenetics and pharmacokinetics were published, but further studies in different and bigger cohorts are needed.