Pharmacogenetics of ribavirin-induced anemia in HCV patients

Structure-function analysis of nucleotide housekeeping protein HAM1 from human malaria parasite Plasmodium falciparum

Non-canonical nucleotides, generated as oxidative metabolic by-products, significantly threaten the genome integrity of Plasmodium falciparum and thereby, their survival, owing to their mutagenic effects. PfHAM1, an evolutionarily conserved inosine/xanthosine triphosphate pyrophosphohydrolase, maintains nucleotide homeostasis in the malaria parasite by removing non-canonical nucleotides, although structure-function intricacies are hitherto poorly reported. Here, we report the X-ray crystal structure of PfHAM1, which revealed a homodimeric structure, additionally validated by size-exclusion chromatography-multi-angle light scattering analysis. The two monomeric units in the dimer were aligned in a parallel fashion, and critical residues associated with substrate and metal binding were identified, wherein a notable structural difference was observed in the β-sheet main frame compared to human inosine triphosphate pyrophosphatase. PfHAM1 exhibited Mg++-dependent pyrophosphohydrolase activity and the highest binding affinity to dITP compared to other non-canonical nucleotides as measured by isothermal titration calorimetry. Modifying the pfham1 genomic locus followed by live-cell imaging of expressed mNeonGreen-tagged PfHAM1 demonstrated its ubiquitous presence in the cytoplasm across erythrocytic stages with greater expression in trophozoites and schizonts. Interestingly, CRISPR-Cas9/DiCre recombinase-guided pfham1-null P. falciparum survived in culture under standard growth conditions, indicating its assistive role in non-canonical nucleotide clearance during intra-erythrocytic stages. This is the first comprehensive structural and functional report of PfHAM1, an atypical nucleotide-cleansing enzyme in P. falciparum.

Impact of ITPA gene polymorphism for predicting anemia and treatment outcome in HCV infected patients taking Sofosbuvir Ribavirin therapy

BACKGROUND

Globally, 80 million people are suffering from chronic Hepatitis C virus (HCV) infection. Sofosbuvir ribavirin-based anti-HCV therapy is associated with anemia and other adverse effects. Polymorphisms of Inosine triphosphatase (ITPA) gene may cause functional impairment in the Inosine triphosphate pyrophosphatase enzyme, resulting in enhanced sustained viral response (SVR) and protection from ribavirin-associated anemia in patients on therapy. The study objective was to investigate the effect of Inosine triphosphatase gene polymorphism on SVR achievement, hemoglobin decline and ribavirin dose reduction in patients on therapy.

METHODS

This prospective cohort study was of 170 hepatitis C infected patients received 6-month sofosbuvir ribavirin therapy. Patient viral load, reduction in ribavirin amount, liver function test, and complete blood count were noted monthly. Inosine triphosphatase variants rs1127354 and rs7270101 were assessed through the restriction fragment length polymorphism and confirmed using Sanger sequencing. The impact of polymorphism on cumulative reduction of ribavirin, and anti-HCV therapy outcome were studied.

RESULTS

A total of 74.3% of patients had ITPA rs1127354 CC genotype, 25.7% were CA and AA 0%. The frequency of ITPA genotype rs7270101-AA was 95%, AC 5%, and CC was 0%. ITPA rs1127354-CA had a notably positive impact on SVR achievement with a zero-relapse rate. ITPA rs1127354-CA genotype was significantly (P ˂0.05) protective against ≥ 2 g/dl Hb reduction from baseline to 1st, 2nd and 6th months of therapy. During treatment, Hb reduction ≥ 10 g/dl was frequently observed in rs1127354-CC genotype and rs7270101-AA genotype patients. Ribavirin dose reduction was significantly (P ˂0.05) high in rs1127354-CC genotype as compared to genotype CA whereas no significant difference was observed in ribavirin dose reduction in rs7270101 AA and non-AA genotype. Patient baseline characteristics such as age, body mass index, rs1127354-CC genotype, and baseline Hb were significantly associated with significant Hb reduction.

CONCLUSION

Pretreatment evaluation of ITPA polymorphism can be a diagnostic tool to find out patients at risk of anemia and improve treatment adherence. ITPA genotype rs1127354-CA contributes to improved compliance with ribavirin dose and protects against hemoglobin decline in HCV patients while taking ribavirin-based therapy. However, ITPA rs1127354, rs7270101 polymorphism have no significant impact on SVR achievement.

Precision Medicine: Determination of Ribavirin Urinary Metabolites in Relation to Drug Adverse Effects in HCV Patients

The most commonly used antiviral treatment against hepatitis C virus is a combination of direct-acting antivirals (DAAs) and ribavirin (RBV), which leads to a shortened duration of therapy and a sustained virologic response until 98%. Nonetheless, several dose-related side effects of RBV could limit its applications. This study aims to measure the urinary concentration of RBV and its main metabolites in order to evaluate the drug metabolism ability of HCV patients and to evaluate the adverse effects, such as anemia, with respect to RBV metabolite levels. RBV and its proactive and inactive metabolites were identified and quantified in the urine of 17 HCV males with severe liver fibrosis using proton nuclear magnetic resonance (¹H-NMR) at the fourth week (TW4) and at the twelfth week of treatment (EOT). Four prodrug urinary metabolites, including RBV, were identified and three of them were quantified. At both the TW4 and EOT stages, six HCV patients were found to maintain high concentrations of RBV, while another six patients maintained a high level of RBV proactive metabolites, likely due to nucleosidase activity. Furthermore, a negative correlation between the reduction in hemoglobin (Hb) and proactive forms was observed, according to RBV-triphosphate accumulation causing the hemolysis. These findings represent a proof of concept regarding tailoring the drug dose in relation to the specific metabolic ability of the individual, as expected by the precision medicine approach.

Real-world Safety and Effectiveness of 24-week Sofosbuvir and Ribavirin Treatment in Patients Infected with Rare Chronic Hepatitis C Virus Genotypes 3, 4, 5, or 6 in Japan

Objectives Real-world evidence on the safety and effectiveness of direct-acting antivirals in patients infected with chronic hepatitis C virus (HCV) genotypes (GTs) 3, 4, 5, or 6 in Japan is limited. This prospective observational study assesses the real-world safety profile and treatment effectiveness among patients prescribed sofosbuvir with ribavirin (SOF+RBV) for HCV GT3-6 infection in Japan. Methods Adults receiving 24-week SOF+RBV treatment for HCV GT3-6 infection were prospectively enrolled and observed through 24 weeks post-treatment for treatment-emergent adverse events (AEs) considered related to SOF and/or RBV by treating physicians and for a sustained virologic response at 12 and 24 weeks post-treatment (SVR12, SVR24). Incidence rates of related AEs and serious AEs (SAEs) were calculated. Proportions of patients experiencing related AEs/SAEs and those achieving SVR12 and SVR24 were assessed overall and by baseline characteristics, including treatment experience and cirrhosis status. Results Among the 50 patients included in the safety analysis, 92% had GT3 infection. The incidence rates of related AEs and SAEs were low overall (1.52 and 0.25 per 100 person-weeks, respectively), with 6.0% and 14.0% patients experiencing AEs related to SOF or RBV, respectively. There were no marked differences in the occurrence of related AEs/SAEs by patient baseline characteristics. SVR12 and SVR24 were achieved in 83.7% (41/49) and 82.2% (37/45) of patients, respectively. Lower effectiveness was observed among treatment-experienced patients and patients with cirrhosis at baseline. Conclusions This study demonstrated that SOF+RBV treatment for HCV GT3-6 infection was safe, effective, and an important treatment option for this difficult-to-treat patient population in Japan.

Pharmacogenetics and Precision Medicine Approaches for the Improvement of COVID-19 Therapies

Many drugs are being administered to tackle coronavirus disease 2019 (COVID-19) pandemic situations without establishing clinical effectiveness or tailoring safety. A repurposing strategy might be more effective and successful if pharmacogenetic interventions are being considered in future clinical studies/trials. Although it is very unlikely that there are almost no pharmacogenetic data for COVID-19 drugs, however, from inferring the pharmacokinetic (PK)/pharmacodynamic(PD) properties and some pharmacogenetic evidence in other diseases/clinical conditions, it is highly likely that pharmacogenetic associations are also feasible in at least some COVID-19 drugs. We strongly mandate to undertake a pharmacogenetic assessment for at least these drug-gene pairs (atazanavir-UGT1A1, ABCB1, SLCO1B1, APOA5; efavirenz-CYP2B6; nevirapine-HLA, CYP2B6, ABCB1; lopinavir-SLCO1B3, ABCC2; ribavirin-SLC28A2; tocilizumab-FCGR3A; ivermectin-ABCB1; oseltamivir-CES1, ABCB1; clopidogrel-CYP2C19, ABCB1, warfarin-CYP2C9, VKORC1; non-steroidal anti-inflammatory drugs (NSAIDs)-CYP2C9) in COVID-19 patients for advancing precision medicine. Molecular docking and computational studies are promising to achieve new therapeutics against SARS-CoV-2 infection. The current situation in the discovery of anti-SARS-CoV-2 agents at four important targets from in silico studies has been described and summarized in this review. Although natural occurring compounds from different herbs against SARS-CoV-2 infection are favorable, however, accurate experimental investigation of these compounds is warranted to provide insightful information. Moreover, clinical considerations of drug-drug interactions (DDIs) and drug-herb interactions (DHIs) of the existing repurposed drugs along with pharmacogenetic (e.g., efavirenz and CYP2B6) and herbogenetic (e.g., andrographolide and CYP2C9) interventions, collectively called multifactorial drug-gene interactions (DGIs), may further accelerate the development of precision COVID-19 therapies in the real-world clinical settings.

Molecular fingerprinting by single cell clone analysis in adverse drug reaction (ADR) assessment

Causality assessment for idiosyncratic ADRs mainly relies on epidemiology, signal detection and less often on proven or plausible mechanistic evidence of the drug at a cellular or organ level. Distinct clones of cells can exist within organs of individual patients, some conferring susceptibility to well recognised adverse drug reactions (ADRs). Recent advances in molecular biology has allowed the development of single cell clonal techniques, including single cell RNA sequencing (scRNA-seq) to molecularly fingerprint ADRs and distinguish between distinct clones of cells within organs in individuals, which may confer differing susceptibilities to ADRs. ScRNA-seq permits molecular fingerprinting of some serious ADRs, mainly in the skin, through identification of directly expressed genes (DEG) of interest within specific clones. Overexpressed DEGs provides an opportunity for targeted treatment strategies to be developed. scRNA-seq could be applied to a number of other ADRs involving tissues that can be biopsied/sampled (including skin, liver, kidney, blood, stem cells) as well as providing a molecular basis for rapid screening of potential therapeutic candidates, which may not otherwise be predictable from class of toxicity/organ involvement. . A framework for putative assessment for ADRs using scRNA-seq is proposed as well as speculating on potential regulatory implications for pharmacovigilance and drug development. Molecular fingerprinting of ADRs using scRNA-seq may allow better targeting for enhanced pharmacovigilance and risk minimisation measures for medicines with appropriate benefit risk profiles, although cost-effectiveness and other factors, such as frequency/severity of individual ADRs and population differences will still be relevant.

Pharmacogenomics of genetic polymorphism within the genes responsible for SARS-CoV-2 susceptibility and the drug-metabolising genes used in treatment

The ongoing outbreak of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) represents a significant challenge to international health. Pharmacogenomics aims to identify the different genetic variations that exist between individuals and populations in order to determine appropriate treatment protocols to enhance the efficacy of drugs and reduce their side‐effects. This literature review provides an overview of recent studies of genetic polymorphisms in genes that mediate the SARS‐CoV‐2 infection mechanism (ACE1, ACE2, TMPRSS2 and CD26). In addition, genetic variations in the drug‐metabolising enzyme genes of several selected drugs used in the treatment of COVID‐19 are summarised. This may help construct an effective health protocol based on genetic biomarkers to optimise response to treatment. Potentially, pharmacogenomics could contribute to the development of effective high‐throughput assays to improve patient evaluation, but their use will also create ethical, medical, regulatory, and legal issues, which should now be considered in the era of personalised medicine.

Pharmacogenomics of COVID-19 therapies

A new global pandemic of coronavirus disease 2019 (COVID-19) has resulted in high mortality and morbidity. Currently numerous drugs are under expedited investigations without well-established safety or efficacy data. Pharmacogenomics may allow individualization of these drugs thereby improving efficacy and safety. In this review, we summarized the pharmacogenomic literature available for COVID-19 drug therapies including hydroxychloroquine, chloroquine, azithromycin, remdesivir, favipiravir, ribavirin, lopinavir/ritonavir, darunavir/cobicistat, interferon beta-1b, tocilizumab, ruxolitinib, baricitinib, and corticosteroids. We searched PubMed, reviewed the Pharmacogenomics Knowledgebase (PharmGKB®) website, Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines, the U.S. Food and Drug Administration (FDA) pharmacogenomics information in the product labeling, and the FDA pharmacogenomics association table. We found several drug-gene variant pairs that may alter the pharmacokinetics of hydroxychloroquine/chloroquine (CYP2C8, CYP2D6, SLCO1A2, and SLCO1B1); azithromycin (ABCB1); ribavirin (SLC29A1, SLC28A2, and SLC28A3); and lopinavir/ritonavir (SLCO1B1, ABCC2, CYP3A). We also identified other variants, that are associated with adverse effects, most notable in hydroxychloroquine/chloroquine (G6PD; hemolysis), ribavirin (ITPA; hemolysis), and interferon β -1b (IRF6; liver toxicity). We also describe the complexity of the risk for QT prolongation in this setting because of additive effects of combining more than one QT-prolonging drug (i.e., hydroxychloroquine/chloroquine and azithromycin), increased concentrations of the drugs due to genetic variants, along with the risk of also combining therapy with potent inhibitors. In conclusion, although direct evidence in COVID-19 patients is lacking, we identified potential actionable genetic markers in COVID-19 therapies. Clinical studies in COVID-19 patients are deemed warranted to assess potential roles of these markers.

Risk factors associated with the severity of adverse drug reactions by Xiyanping injection: A propensity score-matched analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Xiyanping injection (XYP), extraction of Andrographis paniculate (Andrographis paniculata (Burm. f.) Nees, chuan xin lian), is a Chinese patent medicine approved to treat bronchitis in China. In 2017, safety incidents associated with treatment of XYP began to emerge throughout China. However, the risk factors of severity of adverse reactions by XYP remain uncertain.

AIM OF THE STUDY

To determine risk factors for the severity of XYP-associated adverse drug reactions (ADRs).

MATERIALS AND METHODS

We analyzed a total of 26,317 cases of ADRs linked to the use of XYP injection in the China National Adverse Drug Reaction Monitoring Information System from 2004 to 2017. Data were analyzed with respect to age, gender, ethnicity, previous ADRs, family history of ADRs, dosage specification, medication frequency specification, body weight, route of administration, herb-drug interactions (ribavirin, cefatriaxone, penicillin sodium, ambroxol hydrochloride, clindamycin, cefoxitin sodium, azithromycin, ceftazidime, amoxicillin sodium and clavulanate potassium, levofloxacin, cefazolin sodium pentahydrate, acyclovir) by univariate analysis and multivariate analysis. Propensity score matching was used to compare severity of (general or serious) ADRs.

RESULTS

We included 24,911 cases of general ADRs and 1406 cases of serious ADRs. Univariate analysis identified age (p ​< ​0.001), body weight (p ​< ​0.001), route of administration (p ​= ​0.008), co-administration of XYP with ribavirin (p ​= ​0.031) as risk factors of severity of ADRs. Multivariate analysis identified XYP ​+ ​ribavirin combination (p ​= ​0.048) and age (p ​< ​0.001) as the independent risk factors. Upon propensity score matching, the variables were relatively balanced amongst the two groups of patients with general or severe ADRs, and the level of severity in patients who received treatment of XYP ​+ ​ribavirin increased (p ​= ​0.020).

CONCLUSIONS

Age and co-administration of ribavirin may be potential risk factors for the severity of XYP-associated ADRs. This reminds us to pay more attention to the safety of elderly medication. Minimizing the herb-drug-interaction effects of XYP and ribavirin is a viable treatment target for healthcare professionals in managing serious ADRs amongst patients receiving XYP injection.

Pharmacogenetics of the anti-HCV drug sofosbuvir: a preliminary study

Background

Sofosbuvir is a potent nucleotide HCV NS5B polymerase inhibitor that is also a P-glycoprotein (encoded by the ABCB1 gene) and breast cancer resistance protein (encoded by the ABCG2 gene) substrate. Concerning previous anti-HCV therapies, pharmacogenetics had a significant impact, particularly considering the association of interleukin28B polymorphisms with dual-therapy (ribavirin + pegylated IFN) outcomes.

Objectives

In this work, we investigated the association between sofosbuvir and its prevalent metabolite (GS-331007) plasma concentrations at 1 month of therapy and genetic variants (SNPs) in genes encoding transporters and nuclear factors (ABCB1, ABCG2 and HNF4α) related to sofosbuvir transport.

Patients and methods

Allelic discrimination was performed through real-time PCR, whereas plasma concentrations were evaluated through liquid chromatography. One hundred and thirteen patients were enrolled.

Results

Sofosbuvir concentrations were below the limit of quantification since the drug was converted into its GS-331007 metabolite. ABCB1 2677 G>T (P = 0.044) and HNF4α 975 C>G (P = 0.049) SNPs were associated with GS-331007 metabolite plasma concentrations. In linear multivariate analysis, liver stiffness, insulin resistance, baseline haemoglobin and haematocrit and SNPs in the ABCB1 gene (3435 CT/TT and 1236 TT genotypes) were significant predictors of GS-331007 concentrations. Furthermore, we performed sub-analyses considering the anti-HCV concomitant drug and HCV genotype, identifying specific polymorphisms associated with GS-331007 plasma concentrations: ABCB1 3435 C>T and HNF4α975 C>G in patients treated with daclatasvir, ABCB1 2677 G>T with ledipasvir and ABCB1 3435 C>T, ABCB1 2677 G>T, ABCG2 421 C>A and ABCG2 1194 + 928 C>A with ribavirin.

Conclusions

In this study we suggested sofosbuvir GS-331007 metabolite plasma levels were affected by variants in the ABCB1 and HNFα genes.

Reversible splenial lesion syndrome in children with benign convulsions associated with mild gastroenteritis: A retrospective study of five cases

OBJECTIVE

To assess the clinical and imaging features of reversible splenial lesion syndrome (RESLES) with benign convulsions associated with mild gastroenteritis (CwG) in children.

PATIENTS AND METHODS

We retrospectively reviewed the clinical course, blood and stool examinations, cerebrospinal fluid (CSF) examination, magnetic resonance imaging (MRI), electroencephalography (EEG) findings, therapy and prognosis of five children with RESLES associated with CwG.

RESULTS

Five previously healthy patients, four girls and one boy, with mean age 26.4 ± 8.1 months, had clusters of general tonic-clonic or clonic seizures within the first two days of gastroenteritis. Rotavirus antigen was positive in the stool of one case. Interictal EEG was normal except in one case, which showed occipital slow wave. The initial MRI was performed within five days of onset, four patients had an isolated lesion in the splenium of the corpus callosum (SCC), and one patient had lesions extending outside the SCC that involved the genu of the corpus callosum. The follow-up MRI was performed 10-15 days after onset, and all lesions had completely disappeared. All patients were treated with antiviral, rehydration and anticonvulsant therapy in the acute phase. They had good prognosis and normal psychomotor development, with no neurological sequelae after 26-30 months of follow-up.

CONCLUSIONS

CwG and RESLES can coexist in young children. The patients present with clusters of general tonic-clonic or clonic seizures in the acute phase. Brain MRI shows focal lesion in the SCC with high signal intensity on T2-weighted and FLAIR sequences. It has good prognosis and excessive treatment is not necessary.

Direct-acting antiviral drugs for chronic hepatitis C and risk of major vascular events: a systematic review

Direct-acting antiviral drugs (DAAs) were recently approved for treating hepatitis C virus-related chronic hepatitis. As advanced chronic liver disease may predispose patients to thrombotic events, it is still uncertain whether DAAs may influence the actual risk of major arterial and venous thrombotic events. We performed a systematic review to assess the incidence of major vascular events in patients receiving DAAs for HCV chronic hepatitis during phase-III randomized controlled trials (RCTs). Two reviewers identified studies through Pubmed database until October 2015. Reporting and incidence of any vascular events were compared with reporting and incidence of major bleeding, anemia (a prespecified safety outcome) and headache (a common non-prespecified safety outcome). 33 RCTs, encompassing 14,764 patients, were included. Only 13 (39%) and 4 (12%) RCTs provide data on any arterial or venous events, respectively. Occurrence of anemia and headache is reported in all studies. Crude unweighted rate of major arterial events is 0.16% (95% CI 0.10-0.24) of the total included population and 0.47% in those 13 RCTs reporting data. Crude unweighted rate of major venous events is 0.03% of the total included population (95% CI 0.01-0.08) and 0.22% in those four RCTs reporting data. Crude unweighted rate of major bleeding is 0.07% (95% CI 0.03-0.1). Incidence of thrombotic events in HCV patients receiving DAAs may be low, but an incorrect estimation cannot be excluded.

Induction of inosine triphosphatase activity during ribavirin treatment for chronic hepatitis C

BACKGROUND

Ribavirin (RBV) is an antiviral agent and the primary component for chronic hepatitis C (CHC) therapy. Hemolytic anemia is limitation for RBV treatment. Inosine triphosphatase (ITPA) activity has been associated with severity of RBV-induced anemia. However, changes in ITPA activity during CHC therapy are unknown. The aim of this study was to measure the time-dependent change in ITPA activity over the RBV treatment.

METHODS

Forty-two patients with CHC were evaluated for ITPA activity over the course of RBV treatment.

RESULTS

The median value of ITPA activity at start of RBV treatment was 134.2 μmol/h/g hemoglobin (Hb; range, 26.3-251.0 μmol/h/g Hb). The ITPA activity values at 4, 8, and 12 weeks during RBV treatment were 143.2, 202.2, and 225.7 μmol/h/g Hb, respectively, and these ITPA values were significantly elevated compared with the start of treatment (p < 0.001). In patients with ITPA variants, patients with anemia (Hb < 10 g/dL) had greater elevated ITPA activities compared with patients without anemia at 12 weeks.

CONCLUSION

Our findings indicate that ITPA activities are elevated with RBV therapy, and this elevation may be a risk of anemia in late therapeutic phase in patients that began with low ITPA activity.

Influence of ABCB11 and HNF4α genes on daclatasvir plasma concentration: preliminary pharmacogenetic data from the Kineti-C study

Background

Daclatasvir is an inhibitor of HCV non-structural 5A protein and is a P-glycoprotein substrate. Pharmacogenetics has had a great impact on previous anti-HCV therapies, particularly considering the association of IL-28B polymorphisms with dual therapy outcome.

Objectives

We investigated the association between daclatasvir plasma concentrations at 2 weeks and 1 month of therapy and genetic variants (SNPs) in genes encoding transporters and nuclear factors (ABCB1, ABCB11 and HNF4α).

Patients and methods

Allelic discrimination was achieved through real-time PCR, whereas plasma concentrations were evaluated through LC-MS/MS.

Results

Fifty-two patients were analysed, all enrolled in the Kineti-C study. HNF4α 975 C > G polymorphism was found to be associated with the daclatasvir plasma concentrations at 2 weeks (P = 0.009) and 1 month of therapy (P = 0.006). Linear regression analysis suggested that, at 2 weeks of therapy, age, baseline BMI and haematocrit were significant predictors of daclatasvir concentrations, whereas at 1 month of therapy ABCB111131 CC and HNF4α CG/GG genotypes were significant predictors of daclatasvir concentrations.

Conclusions

These are the first and preliminary results from our clinical study focusing on daclatasvir pharmacogenetics, showing that this approach could have a role in the era of new anti-HCV therapies.

Vitamin D pathway gene polymorphisms affecting daclatasvir plasma concentration at 2 weeks and 1 month of therapy

AIM

Vitamin D (VD) influences genetic expression through its receptor (VDR). VD pathway gene polymorphisms seem to influence antiviral drug pharmacokinetics and therapeutic outcome/toxicity. We investigated the association between daclatasvir (DCV) plasma concentrations and genetic variants (SNPs) associated with the VD pathway.

PATIENTS & METHODS

Chronic hepatitis C patients treated with DCV from 2014 to 2016 were included. Genotypes were assessed through real-time PCR and plasma concentrations through liquid chromatography.

RESULTS

A total of 52 patients were analyzed. DCV levels were influenced by CYP24A1 rs2248359T>C polymorphism at 2 weeks and VDR Cdx2 A>G at 1 month of treatment. Linear regression analysis showed baseline BMI, alanine aminotransferase and hematocrit as significant predictors of DCV concentrations at 2 weeks, BMI and hematocrit at baseline, VDR Cdx2 AG/GG and FokI TC/CC at 1 month.

CONCLUSION

These results showed a possible role of VD pathway gene polymorphisms in influencing DCV plasma concentrations, but further studies are required.

Vitamin D pathway genetic variants are able to influence sofosbuvir and its main metabolite pharmacokinetics in HCV mono-infected patients

Vitamin D levels and genetic variants were associated with drug outcome/toxicity and concentrations. The plasma exposure of GS-331007, the main sofosbuvir metabolite, has been related to SVR. We evaluated the impact of polymorphisms in genes (CYP27B1, CYP24A1, VDBP and VDR) related to vitamin D pathway on sofosbuvir and GS-331007 plasma levels in HCV mono-infected patients at one month of treatment. Polymorphisms were investigated through real-time PCR; drug plasma quantification was performed through a UHPLC-MS/MS method. GS-331007 levels were associated with CYP24A1rs2248359 and VDRCdx2 variants in all the analyzed patients and linear regression analysis showed that sex, body mass index, HCV genotype, baseline estimated glomerular filtration rate, VDRCdx2AG/GG and CYP27B1-1260TT genotypes significantly predict concentrations. We performed sub-analyses considering the HCV genotype and the concomitant drug, identifying polymorphisms associated with GS-331007 concentrations. This is the first study focusing on vitamin D pathway gene variants and DAAs concentrations, but further studies are required.

The role of ITPA and ribavirin transporter genes polymorphisms in prediction of ribavirin-induced anaemia in chronic hepatitis C Egyptian patients

Few data are available concerning the roles of polymorphisms of inosine triphosphatase (ITPA) gene and ribavirin (RBV) transporter genes in the prediction of RBV-induced anaemia among Egyptians with chronic hepatitis C (CHC). Genotyping of three ITPA gene variants and two variants of RBV transporter genes has been performed in 123 patients under pegylated interferon-α/ribavirin treatment. The baseline haemoglobin and ITPA rs1127354 CA/AA have been found as predictors of anaemia at 4, 8 and 12 weeks of RBV therapy. In addition, ITPA rs7270101 AC/CC and age predicted anaemia after 12 weeks of therapy. In conclusion, the ITPA variant rs1127354C>A significantly predict RBV-induced anaemia during the first 3 months of treatment and it is recommended to be assessed before RBV administration.

Circannual variation of mitotane and its metabolites plasma levels in patients with adrenocortical carcinoma

OBJECTIVES

Mitotane is the reference drug for the adrenocortical carcinoma treatment; its pharmacological activity seems to depend on drug transformation in two active metabolites: o,p'-DDE (dichlorodiphenylethene) and o,p'-DDA (dichlorodiphenylacetate). Mitotane and metabolites are lipophilic agents; thus, they tend to accumulate into adipose tissues (white and brown), which change their prevalence seasonally. Aim of the work was to evaluate mitotane and metabolites plasma levels variation over the year, in adrenocortical cancer patients treated with Lysodren^® for at least 6 months.

METHODS

We enrolled a group of 86 adrenocortical carcinoma diagnosed patients, who underwent radical surgery and started mitotane as adjuvant treatment. For drug and metabolites plasma level (from samples collected ~12 h after the dose administration of mitotane, just before the subsequent administration) determination, a validated chromatographic method was used.

KEY FINDINGS

Results showed an evidence of a seasonal trend for the three substance (o,p'-DDD, o,p'-DDE and o,p'-DDA) plasma levels, in terms of acrophases and lower values. Furthermore, it came out that male patients need a higher significant mitotane drug dose than female patients to reach mitotane therapeutic window.

CONCLUSIONS

In conclusion, this is the first study assessing a mitotane plasma level variation over the year, but further studies in larger cohorts are required.

Hepatitis C virus pharmacogenomics in Latin American populations: implications in the era of direct-acting antivirals

In recent years, great progress has been made in the field of new therapeutic options for hepatitis C virus (HCV) infection. The new direct-acting antiviral agents (DAAs) represent a great hope for millions of chronically infected individuals because their use may lead to excellent cure rates with fewer side effects. In Latin America, the high prevalence of HCV genotype 1 infection and the significant association of Native American ancestry with risk predictive single-nucleotide polymorphisms (SNPs) in IFNL4 and ITPA genes highlight the need to implement new treatment regimens in these populations. However, the universal accessibility to DAAs is still not a reality in the region as their high cost is one of the major, although not the only, limiting factors for their broad implementation. Therefore, under these circumstances, could the assessment of host genetic markers be a useful tool to prioritize DAA treatment until global access to these new drugs can be achieved? This review will summarize the scientific evidences and the potential implications of HCV pharmacogenomics in this rapidly evolving era of anti-HCV drug development.

A disease spectrum for ITPA variation: advances in biochemical and clinical research

Human ITPase (encoded by the ITPA gene) is a protective enzyme which acts to exclude noncanonical (deoxy)nucleoside triphosphates ((d)NTPs) such as (deoxy)inosine 5′-triphosphate ((d)ITP), from (d)NTP pools. Until the last few years, the importance of ITPase in human health and disease has been enigmatic. In 2009, an article was published demonstrating that ITPase deficiency in mice is lethal. All homozygous null offspring died before weaning as a result of cardiomyopathy due to a defect in the maintenance of quality ATP pools. More recently, a whole exome sequencing project revealed that very rare, severe human ITPA mutation results in early infantile encephalopathy and death. It has been estimated that nearly one third of the human population has an ITPA status which is associated with decreased ITPase activity. ITPA status has been linked to altered outcomes for patients undergoing thiopurine or ribavirin therapy. Thiopurine therapy can be toxic for patients with ITPA polymorphism, however, ITPA polymorphism is associated with improved outcomes for patients undergoing ribavirin treatment. ITPA polymorphism has also been linked to early-onset tuberculosis susceptibility. These data suggest a spectrum of ITPA-related disease exists in human populations. Potentially, ITPA status may affect a large number of patient outcomes, suggesting that modulation of ITPase activity is an important emerging avenue for reducing the number of negative outcomes for ITPA-related disease. Recent biochemical studies have aimed to provide rationale for clinical observations, better understand substrate selectivity and provide a platform for modulation of ITPase activity.