Inosine triphosphatase genetic variants are protective against anemia during antiviral therapy for HCV2/3 but do not decrease dose reductions of RBV or increase SVR

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.

Relationships Between Vitamin D Status and Cytokine: Results from Interferon-Based Therapy in Non-Cirrhotic, Treatment-Naïve Patients with Chronic Hepatitis C Infection

Background

Vitamin D contributes to bone health and extra-skeletal effects. The mechanisms underlying vitamin D metabolism have not been extensively evaluated. The relationships between vitamin D and inflammatory cytokines are debated. Our objective was to investigate whether supplemental interferons are associated with longitudinal change of vitamin D status in humans.

Methods

A total of 48 patients with 24 or 48 weeks of pegylated interferon-α plus ribavirin therapy were examined for serum 25-hydroxyvitamin D (25[OH]D) level before treatment, at the end of treatment, and 24 weeks after treatment. In addition, we analyzed publicly available RNA sequencing data from accession GSE42697 and GSE7123 in the Gene Expression Omnibus.

Findings

The overall sustained virologic response (SVR) rate was 62.5%. There was no statistically significant association between baseline 25(OH)D concentrations and liver fibrosis. In patients with SVR, serum 25(OH)D increased markedly at end-of-treatment and decreased markedly by the end of the 24-week follow-up period. In the non-SVR group, this treatment-dependent change was lost. In gene expression analysis, the vitamin D biosynthesis process was activated in subjects with SVR, but not in patients without SVR. Furthermore, vitamin D receptor (VDR) signaling in peripheral blood mononuclear cells (PBMCs) was triggered in marked responders but not in poor responders.

Conclusion

In the aggregate, these data suggest that interferons have a regulatory influence on vitamin D status that can contribute to VDR signaling in PBMCs.

Genetic Factors That Affect Spontaneous Clearance of Hepatitis C or B Virus, Response to Treatment, and Disease Progression

Hepatitis C virus (HCV) and hepatitis B virus (HBV) infections can lead to cirrhosis, end-stage liver disease, and hepatocellular carcinoma. Over the past decade, studies of individuals infected with these viruses have established genetic associations with the probability of developing a chronic infection, risk of disease progression, and likelihood of treatment response. We review genetic and genomic methods that have been used to study risk of HBV and HCV infection and patient outcomes. For example, genome-wide association studies have linked a region containing the interferon lambda genes to spontaneous and treatment-induced clearance of HCV. We review the genetic variants associated with HCV and HBV infection, and how these variants affect specific expression or activities of their products. Further studies of these variants could provide insights into risk factors for and mechanisms of chronic infection and disease progression, as well as new strategies for treatment.

Erythrocyte Inosine triphosphatase activity: A potential biomarker for adverse events during combination antiretroviral therapy for HIV

The purine analogues tenofovir and abacavir are precursors of potential substrates for the enzyme Inosine 5'-triphosphate pyrophosphohydrolase (ITPase). Here, we investigated the association of ITPase activity and ITPA genotype with the occurrence of adverse events (AEs) during combination antiretroviral therapy (cART) for human immunodeficiency virus (HIV) infection. In 393 adult HIV-seropositive patients, AEs were defined as events that led to stop of cART regimen. ITPase activity ≥4 mmol IMP/mmol Hb/hour was considered as normal. ITPA genotype was determined by testing two ITPA polymorphisms: c.94C>A (p.Pro32Thr, rs1127354) and c.124+21A>C (rs7270101). Logistic regression analysis determined odds ratios for developing AEs. In tenofovir-containing regimens decreased ITPase activity was associated with less AEs (p = 0.01) and longer regimen duration (p = 0.001). In contrast, in abacavir-containing regimens decreased ITPase activity was associated with more AEs (crude p = 0.02) and increased switching of medication due to AEs (p = 0.03). ITPA genotype wt/wt was significantly associated with an increase in the occurrence of AEs in tenofovir-containing regimens. Decreased ITPase activity seems to be protective against occurrence of AEs in tenofovir-containing cART, while it is associated with an increase in AEs in abacavir-containing regimens.

The rs1127354 Polymorphism in ITPA Is Associated with Susceptibility to Infertility

Objective

Infertility is a common human disorder which is defined as the failure to conceive for a period of 12 months without contraception. Many studies have shown that the outcome of fertility could be affected by DNA damage. We attempted to examine the association of two SNPs (rs1127354 and rs7270101) in ITPA, a gene encoding a key factor in the repair system, with susceptibility to infertility.

Materials and Methods

This was a case-control study of individuals with established infertility. Blood samples were obtained from 164 infertile patients and 180 ethnically matched fertile controls. Total genomic DNA were extracted from whole blood using the standard salting out method, and stored at -20˚C. Genotyping were based on mismatch polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method in which PCR products were digested with the XmnI restriction enzyme and run on a 12% polyacrylamide gel.

Results

All genotype frequencies in the control group were in Hardy-Weinberg equilibrium. A significant association (in allelic, recessive and dominant genotypic models) was observed between infertile patients and healthy controls based on rs1127354 (P=0.0001), however, no significant association was detected for rs7270101. Also, gender stratification and analysis of different genotype models did not lead to a significant association for this single- nucleotide polymorphis (SNP).

Conclusion

ITPA is likely to be a genetic determinant for decreased fertility. To the best of our knowledge, this is the first report demonstrating this association, however, given the small sample size and other limitations, genotyping of this SNP is recommended to be carried out in different populations with more samples.

Correlation between polymorphism in the inosine triphosphatase and the reductions in hemoglobin concentration and ribavirin dose during sofosbuvir and ribavirin therapy

BACKGROUND AND AIM

It is unclear whether polymorphism in the inosine triphosphatase (ITPA) gene correlates to the reduction in hemoglobin (Hb) concentrations during sofosbuvir (SOF) and ribavirin (RBV) therapy. This study investigated the effects of the ITPA polymorphism on Japanese patients with chronic hepatitis C virus genotype 2 infection treated with SOF/RBV therapy.

METHODS

In 106 patients treated with SOF/RBV therapy, this study assessed the effects of the ITPA polymorphism (rs1127354) on anemia, RBV dose reduction, and sustained virological response.

RESULTS

Of the 106 patients, 80 had the CC genotype, whereas 26 had a non-CC genotype in ITPA. Patients with the CC genotype had significantly larger reductions in Hb concentrations than those with a non-CC genotype throughout the treatment course. RBV dose reduction was required in 18/106 (17.0%) patients, with a significantly higher frequency in patients with the CC genotype than in those with a non-CC genotype (P = 0.010). In multivariate analysis, age ≥ 65 years (P = 0.011) and the ITPA CC genotype (P < 0.0001) were factors significantly associated with anemia throughout the treatment course. Sustained virological response was achieved in 99.0% of all patients: 98.7% of patients with the CC genotype and 100% of patients with a non-CC genotype.

CONCLUSIONS

Inosine triphosphatase polymorphism appeared to correlate with anemia incidence and RBV dose reduction during SOF/RBV therapy, but not the clinical outcome. Careful monitoring of Hb concentrations and prompt adjustment of RBV doses are required for successful treatment, particularly in patients harboring the ITPA CC genotype or age ≥ 65 years.

ITPA gene polymorphism (94C>A) effects on ribavirin-induced anemia during therapy in Egyptian patients with chronic hepatitis C

Inosine triphosphatase (ITPA) gene variants can protect against ribavirin (RBV)-induced anemia in patients treated for chronic hepatitis C. The aim of this study was to determine the relationship between genetic variants of ITPA polymorphism, anemia, RBV dose reduction, and treatment response in hepatitis C virus (HCV)-infected patients. This study was conducted on 97 Egyptian chronic HCV patients who were scheduled for pegylated-interferon (PEG-INF) /RBV therapy. ITPA genotypes rs1127354 were determined by Real Time PCR melting curve analysis. Effects of ITPA polymorphism on hemoglobin (Hb) levels, RBV dose reduction and treatment response were analyzed. The homozygous wild genotype (CC) was associated with Hb reduction at week 4 (P = 0.004). The minor allele protected against Hb reduction. No association with sustained virological response was observed (P = 0.492). Female gender; lower baseline Hb and higher baseline WBC were associated with week 4 anemia (P = 0.04; P = 0.023; 0.033, respectively). The ITPA gene polymorphism rs1127354 heterozygous genotype (CA) may influence Hb levels and protect against hemolytic anemia during RBV-containing regimens for HCV. However, such findings were not significantly related to treatment outcomes. Patients with wild ITPA genotype (CC) experienced a more Hb drop and RBV dose reductions more frequently.

Viral and host factors associated with outcomes of hepatitis C virus infection (Review)

Hepatitis C virus (HCV) infection is a major health issue globally. Owing to the progress made in host genetics and HCV molecular virology, emerging data have suggested that the natural course and treatment response in patients with HCV infection are largely determined by complex host‑viral interactions. HCV genotype is the most important viral factor predicting the response to pegylated interferon‑α plus ribavirin therapy. The subtype of HCV genotype 1 is the key viral factor that predicts the efficacy of direct‑acting antiviral therapy. HCV genome heterogeneity and baseline viral load are additionally associated with the treatment response. Multiple host genetic variants localized in genes associated with the immune response have been identified as predictors of spontaneous disease course and therapy outcome in chronic HCV. However, most findings from candidate gene association studies have not been proven universal for all investigated populations and independent studies. Previous findings in independent large genome wide association studies confirmed that interferon‑λ3 gene polymorphisms are associated with spontaneous clearance and treatment responsiveness. A polymorphism of the inosine triphosphatase gene has been identified as a protective factor against ribavirin‑induced anemia and dose reductions. Another genetic variant in the patatin‑like phospholipase domain containing 3 genes is associated with hepatic steatosis and fibrosis in patients with HCV. The present review focused on the identified viral and host factors associated with outcomes of patients with HCV, and assessed the involvement of viral and host genetics in the natural history and treatment outcomes of HCV infection. This will provide novel ideas concerning personalized prevention and individualized clinical management.

ITPase activity modulates the severity of anaemia in HCV-related cirrhosis treated with ribavirin-containing interferon-free regimens

BACKGROUND

To investigate the association between inosine triphosphatase (ITPase) activity and the degree of anaemia occurring during direct-acting antiviral (DAA)/ribavirin (RBV)-based therapy in patients with cirrhosis.

METHODS

In a multicentre, prospective study 227 patients with HCV-related cirrhosis treated with DAA and RBV were enrolled. All patients were screened for the rs1127354 and rs7270101 ITPA single nucleotide polymorphisms using direct sequencing.

RESULTS

150 (66.1%) patients had normal (100%) ITPase activity, 48 (21.1%) had moderate (60%) activity and 29 (12.8%) minimal (≤30%) activity. The ITPase activity significantly influenced the haemoglobin concentration: at day 15 it was -1.248 (sd ±0.978) in the 150 patients with an ITPase activity of 100% and -0.616 (±0.862) in the 77 patients with an ITPase activity less than 100% (P<0.000), and at day 30 it was -1.941 ±1.218 versus -1.11 ±1.218 (P<0.000). The 63 patients with a severe (at least 3/dl) haemoglobin decline, compared to those without, more frequently had an ITPase activity of 100% (82.1% versus 62.8%; P=0.021), were older (mean age ±sd: 66.7 ±8.2 versus 61.4 ±9.7 years; P=0.004) and were treated with a higher ribavirin dose (13.7 ±2.1 versus 12.8 ±2.5 mg/kg/day; P=0.008). At multivariate logistic regression analysis, the ITPase activity of 100% (OR: 2.83; 95% CI: 1.12, 7.10), male gender (OR: 3.22; 95% CI: 1.35, 7.66), body mass index (OR: 1.17; 95% CI: 1.03, 1.34) and dose of ribavirin (OR: 1.22; 95% CI: 1.06, 1.47) were independent predictors of a severe decline in haemoglobin (P<0.0001).

CONCLUSIONS

This study suggests that the polymorphisms in the ITPA gene influence the severity of anaemia during the first month of a DAA/RBV-based treatment in HCV-related cirrhosis.

Rapidity and Severity of Hemoglobin Decreasing Associated with Erythrocyte Inosine Triphosphatase Activity and ATP Concentration during Chronic Hepatitis C Treatment

The purpose of this study was to evaluate the association between therapy-induced hemoglobin (Hb) decreasing rapidity and severity with erythrocyte inosine triphosphatase (ITPase) activity and ATP concentration in chronic hepatitis C patients receiving chronic hepatitis C (HCV) treatment. Forty-three Japanese patients were included in the study. Erythrocyte ITPase activity before therapy was determined by HPLC-UV. Erythrocyte ATP concentrations before and during therapy were determined by luciferase assay. Genotyping for ITPA 94C>A (rs1127354) and IVS2+21 A>C (rs7270101) was conducted using TaqMan probes. The median ITPase activity (µmol/h/g hemoglobin) of ITPA 94 CC, CA, and AA genotypes was 136.8 (range, 80.4-289.6), 41.1 (24.3-93.1), and 11.8, respectively. ITPase activity and Hb decreasing showed a significantly inverse relationship at therapeutic weeks 2, 4, and 6 (p<0.01). Erythrocyte ATP concentration was decreased by therapy, and Hb decreasing was significantly and inversely correlated with erythrocyte ATP concentration at week 4 and after week 8 (p<0.001 and 0.05, respectively). ATP concentration for patients with ITPA 94CA was significantly lower than ITPA 94CC at week 4 (p=0.045). We concluded that ITPase activity plays an important function and that ATP concentration changes due to therapy are related to the Hb decreasing mechanism in the early period of therapy with HCV treatment.

Inosine Triphosphate Pyrophosphohydrolase Expression: Decreased in Leukocytes of HIV-Infected Patients Using Combination Antiretroviral Therapy

OBJECTIVE

In HIV-infected patients, the enzyme Inosine triphosphate pyrophosphohydrolase (ITPase), involved in purine nucleotide homeostasis, was found to be decreased in erythrocytes. Since purine analogues are pivotal in the HIV treatment, a better understanding of ITPase expression in CD4 lymphocytes may lead to better understanding of nucleotide metabolism and (adverse) effects.

DESIGN

Cross-sectional, cohort, observational study.

METHODS

HIV-infected and control patients above 18 years were included. All DNA samples were genotyped for the 2 functional ITPA SNPs; c.94C>A (rs1127354) and g.IVS+21A>C (rs7270101). ITPase expression was determined by flow cytometry in all leukocyte subsets.

RESULTS

Fifty-nine HIV-infected patients and 50 controls were included. Leukocyte subtype distribution showed no difference in monocytes and granulocytes, but lymphocytes were higher in HIV-infected patients (P < 0.001). ITPase expression was highest in activated monocytes and lowest in lymphocytes. In HIV-infected patients, the percentage of ITPase positive cells was less in all leukocyte and lymphocyte subsets compared with controls (P < 0.01). In HIV-infected patients, 97.4% of CD4 lymphocytes were ITPase positive versus 99.9% in controls (P = 0.002) and 85.9% versus 99.6% of CD8 lymphocytes (P < 0.0001), respectively. Stratification according to genotype revealed no significant differences in ITPase expression in leukocytes in HIV-infected and control patients.

CONCLUSIONS

HIV-infection seems to be interfering with the nucleotide metabolism in leukocytes, including CD4 lymphocytes, by decreasing ITPase expression, independently of ITPA genotype. Given that active metabolites of purine-analogue reverse transcriptase inhibitors are potential substrates for ITPase, these results warrant further research towards effectiveness and adverse events of purine analogues and ITPase activity.

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.

TPMT and ITPA genetic variants in Lithuanian inflammatory bowel disease patients: Prevalence and azathioprine-related side effects

PURPOSE

Inter-individual thiopurine metabolism variability can influence treatment outcomes in inflammatory bowel disease (IBD) patients. Genetic polymorphisms in thiopurine methyltransferase (TPMT) and inosine triphosphate pyrophosphatase (ITPA) were linked with toxicity of azathioprine (AZA). The aim of the study was to investigate frequencies of TPMT and ITPA polymorphisms in Lithuanian IBD patients and analyze their association with AZA-related adverse events.

MATERIALS/METHODS

Polymorphisms in TPMT (TPMT*2,*3B,*3C,*3A) and ITPA (rs1127354, rs7270101) genes were determined using PCR-RFLP and TaqMan(®) genotyping assays. 551 consecutive Lithuanian IBD patients were genotyped. The use of AZA and its side effects were assessed retrospectively according to hospital medical records.

RESULTS

Frequencies of TPMT*3A, TPMT*3B and TPMT*3C alleles were 3.1%, 0.5% and 0.1%, respectively. TPMT*2 genetic variant was not detected in the study group. The distribution of minor alleles for ITPA rs1127354 and rs7270101 polymorphisms was 9.9% and 10.5%, respectively. AZA was prescribed in 82 patients and it provoked myelotoxicity in 11%, hepatotoxicity in 6.1%, dyspepsia in 6.1%, and pancreatitis in 3.6% of cases. Among patients who had AZA-related myelotoxicity, 11.1% were TPMT compound heterozygous, 44.4% had heterozygous genotype (P<0.01). Frequencies of ITPA minor alleles were similar among the patients with and without AZA-related side effects.

CONCLUSION

Frequencies of TPMT and ITPA variant alleles in Lithuanian IBD group were similar to those observed in the Northern-Eastern Europe Caucasian populations. Polymorphisms in TPMT might be associated with myelotoxicity and leukopenia in AZA treated patients, while ITPA variant alleles appear not to be linked with treatment-related side effects.

The impact of an inosine triphosphate pyrophosphatase genotype on bilirubin increase in chronic hepatitis C patients treated with simeprevir, pegylated interferon plus ribavirin

BACKGROUND

Hyperbilirubinemia, mild or moderate, is a commonly observed laboratory abnormality in chronic hepatitis C patients treated with simeprevir with pegylated interferon (Peg-IFN) plus ribavirin. In this prospective, multicenter study, we aimed to investigate the clinical features and factors associated with bilirubin increases during the therapy.

METHODS

A total of 192 patients with chronic hepatitis C who were treated with simeprevir with Peg-IFN plus ribavirin were analyzed.

RESULTS

The mean serum bilirubin level increased significantly during the initial 12 weeks of simeprevir administration and peaked at 2 weeks after the administration. Hyperbilirubinemia of more than 2 mg/dl developed in 18% of the patients; in 85% of those patients, the bilirubin levels peaked within 6 weeks and gradually decreased thereafter. A univariable analysis revealed that an increase in serum total bilirubin of 1.0 mg/dl or more from baseline was significantly associated with the sex, red blood cell count, serum hemoglobin level, serum alanine aminotransferase level, serum creatinine level and inosine triphosphate pyrophosphatase (ITPA) genotype. In the multivariable analysis, the ITPA genotype (CC odds ratio 4.990, p = 0.011) was found to be the only independent factor. Consistent with this result, there was a significant correlation between hyperbilirubinemia and the degree of hemolytic anemia.

CONCLUSIONS

Hyperbilirubinemia develops at early time points after simeprevir administration in most cases and is dependent on the ITPA genotype. Careful attention should be paid to hyperbilirubinemia, which occurs at later time points or in patients with an ITPA non-CC genotype so that a diagnosis of liver damage with hyperbilirubinemia is not missed.

The ITPA and C20orf194 Polymorphisms and Hematological Changes During Treatment With Pegylated-Interferon Plus Ribavirin in Patients With Chronic Hepatitis C

BACKGROUND

It has been found that ITPase deficiency is caused by ITPA gene polymorphisms. It was observed that ITPA polymorphisms have impact on hematological changes, including hemoglobin (Hb)-decline during treatment of chronic hepatitis C (CHC) patients with pegylated-interferon (PEG-IFN) plus ribavirin (RBV).

OBJECTIVES

This study aimed to assess the effect of ITPA and C20orf194 polymorphisms on hematological changes at week 4 of treatment with PEG-IFN plus RBV in patients with CHC.

PATIENTS AND METHODS

In this retrospective study, 168 patients with CHC (56% HCV genotype-1 and 44% HCV genotype-3) under the treatment of PEG-IFN plus RBV were genotyped for rs1127354, rs7270101 and rs6051702 polymorphisms by the polymerase chain reaction-restriction fragment length polymorphism. Hematological changes including Hb-, platelet (Plt)- and white blood cell-decline at week 4 of the treatment were assessed.

RESULTS

In univariate analysis, rs1127354 and HCV genotypes were found to influence the Hb-decline at week 4 of the treatment. In multivariate analysis, rs1127354 CA + AA and HCV genotype-3 were found to have a great role on prevention of Hb-decline. Furthermore, rs1127354 and HCV RNA levels were found to influence the Plt-decline at week 4 of the treatment in the univariate analysis. In multivariate analysis, rs1127354 CA + AA and HCV RNA levels less than 600,000 IU/mL were found to be associated with a higher level of Plt-decline.

CONCLUSIONS

In patients with CHC, who were treated with PEG-IFN plus RBV, Hb-decline was affected by rs1127354 and HCV genotypes. However, Plt-decline may be altered by rs1127354 and baseline HCV RNA levels.

Hepatitis C virus markers in infection by hepatitis C virus: In the era of directly acting antivirals

About 130-170 million people are infected with the hepatitis C virus (HCV) worldwide and more than 350000 people die each year of HCV-related liver diseases. The combination of pegylated interferon (Peg-IFN) and ribavirin (RBV) was recommended as the treatment of choice for chronic hepatitis C for nearly a decade. In 2011 the directly acting antivirals (DAA) HCV NS3/4A protease inhibitors, telaprevir and boceprevir, were approved to treat HCV-genotype-1 infection, each in triple combination with Peg-IFN and RBV. These treatments allowed higher rates of SVR than the double Peg-IFN + RBV, but the low tolerability and high pill burden of these triple regimes were responsible for reduced adherence and early treatment discontinuation. The second and third wave DAAs introduced in 2013-2014 enhanced the efficacy and tolerability of anti-HCV treatment. Consequently, the traditional indicators for disease management and predictors of treatment response should be revised in light of these new therapeutic options. This review article will focus on the use of the markers of HCV infection and replication, of laboratory and instrumental data to define the stage of the disease and of predictors, if any, of response to therapy in the DAA era. The article is addressed particularly to physicians who have patients with hepatitis C in care in their everyday clinical practice.

ITPA Polymorphisms Are Associated with Hematological Side Effects during Antiviral Therapy for Chronic HCV Infection

Background/Objective

Genetic polymorphisms in the inosine triphosphatase (ITPA) gene have been associated with the protection from early ribavirin(RBV)-induced hemolytic anemia among patients with chronic hepatitis C virus (HCV) infection. The aim of the present study was to investigate the association between the functional ITPA variants and hematological side effects during antiviral therapy with pegylated interferon (PegIFN) and RBV.

Patients and Methods

This cohort study included all consecutive Caucasian patients treated for chronic HCV infection with PegIFN and RBV between 2000 and 2009 for whom a serum sample was available for genetic testing. The predicted inosine triphosphate pyrophosphatase (ITPase) activity was based on the genotypes of the SNPs rs1127354 and rs7270101. Decline in hemoglobin (Hb) during antiviral therapy, as well as dose reductions, blood transfusions and use of erythropoietin were assessed.

Results

In total, 213 patients were included. The predicted ITPase activity was normal among 152 (71%) patients; 61 (29%) patients had ITPase deficiency. By multivariable linear regression, RBV dose in mg per kilogram (Beta 0.09, 95%CI 0.04–0.13, p<0.001) and normal ITPase activity (Beta 0.89, 95%CI 0.64–1.14, p<0.001) were associated with more Hb decline at week 4 of treatment. Patients with normal ITPase activity underwent more dose adjustments of RBV than patients with ITPase deficiency (19(13%) vs 1(2%),p = 0.014) and received erythropoietin more frequently (12 (8%) vs 0 (0%),p = 0.024).

Conclusion

Genetic variants in the ITPA gene protected against RBV treatment-induced anemia among Caucasian patients with chronic HCV infection. Patients with normal ITPase activity underwent more dose reductions of RBV and received erythropoietin more frequently.

Relationship between ITPA polymorphisms and hemolytic anemia in HCV-infected patients after ribavirin-based therapy: a meta-analysis

BACKGROUND

There is growing evidence that variations in the gene encoding inosine triphosphate pyrophosphohydrolase (ITPase), known as inosine triphosphatase (ITPA), are related to hemolytic anemia, which is frequently observed among hepatitis C virus (HCV)-infected patients receiving ribavirin (RBV)-based therapy. We performed a meta-analysis of all eligible studies assessing ITPA gene polymorphisms related to RBV-induced hemolytic anemia in HCV-infected patients published in PubMed, Embase and the Cochrane library prior to the end of 2014.

METHODS

Three outcomes were evaluated: (1) hemoglobin decline, (2) severe anemia, and (3) RBV dose reduction or treatment discontinuation. Pooled odds ratio (OR) and 95 % confidence interval (95 % CI) were estimated by either fixed or random effects models.

RESULTS

Twenty-nine studies were selected from the literature search: 20 references involving 6533 individuals for hemoglobin decline, 13 references on 3764 patients for severe anemia, and 16 references on 3918 patients for RBV dose reduction or discontinuation. Significant associations with hemoglobin decline were found for rs1127354 CC [OR = 12.84 (95 % CI 7.44; 22.17)], rs7270101 AA [OR = 3.41 (95 % CI 2.08; 5.59)] and rs6051702 AA [OR = 4.43 (95 % CI 2.80; 7.00)] genotypes. Moreover, significant associations with hemoglobin decline were also found for absent [OR = 6.01 (95 % CI 4.84; 7.46)] and mild [OR = 4.68 (95 % CI 2.83; 7.74)] ITPase deficiency haplotypes. The ITPA rs1127354 CC genotype and absent ITPase deficiency haplotype were also associated with severe anemia {[OR = 7.77 (95 % CI 5.03; 12.00)] and [OR = 4.79 (95 % CI 1.69; 13.56)], respectively}. Additionally, the rs1127354 CC genotype showed significant association with RBV dose reduction or stopping treatment (OR = 2.24; 95 % CI 1.79; 2.81).

CONCLUSIONS

ITPA polymorphisms increase the likelihood of developing hemolytic anemia for HCV-infected patients on RBV-based therapy, particularly rs1127354 CC and rs7270101 AA genotypes, suggesting the utility of screening for ITPA polymorphisms to avoid hematological toxicity and increase adherence to RBV-based therapy.

Role of genetic polymorphisms in hepatitis C virus chronic infection

AIM: To analyze the host genetics factors influencing the clinical course and the response to antiviral treatment in patients with chronic hepatitis C (CHC).

METHODS: We conducted an electronic search on the PubMed and MEDLINE (2000-2014) databases and Cochrane library (2000-2014). A total of 73 articles were retrieved and their data were extensively evaluated and discussed by the authors and then analyzed in this review article.

RESULTS: Several studies associated polymorphisms in the interleukin 28B gene on chromosome 19 (19q13.13) with a spontaneous viral clearance in acute hepatitis C and with the response to pegylated interferon (Peg-IFN)-based treatment in chronic hepatitis C patients. Other investigations demonstrated that inosine triphosphate pyrophosphatase genetic variants protect hepatitis C virus-genotype-1 CHC patients from ribavirin-induced anemia, and other studies that a polymorphism in the patatin-like phospholipase domain-containing protein 3 was associated with hepatic steatosis in CHC patients. Although not conclusive, some investigations suggested that the vitamin D-associated polymorphisms play an important role in the achievement of sustained virologic response in CHC patients treated with Peg-IFN-based antiviral therapy. Several other polymorphisms have been investigated to ascertain their possible impact on the natural history and on the response to treatment in patients with CHC, but the data are preliminary and warrant confirmation.

CONCLUSION: Several genetic polymorphisms seem to influence the clinical course and the response to antiviral treatment in patients with CHC, suggesting individualized follow up and treatment strategies.

Impact of IL28B, ITPA and PNPLA3 genetic variants on therapeutic outcome and progression of hepatitis C virus infection

Chronic HCV infection comprises a broad spectrum of liver disease, ranging from no or minimal activity to active hepatitis that in time may progress to severe liver fibrosis, cirrhosis and hepatocellular carcinoma if left untreated. This review describes the impact of genetic variants of interleukin 28B (IL28B; also known as interferon-lambda 3), inosine triphosphate pyrophosphatase (ITPA) and patatin-like phospholipase domain-containing 3 (PNPLA3) on therapeutic outcome and liver disease severity in HCV-infected patients.

Progress in understanding the genomic basis for adverse drug reactions: a comprehensive review and focus on the role of ethnicity

A major goal of the field of pharmacogenomics is to identify the genomic causes of serious adverse drug reactions (ADRs). Increasingly, genome-wide association studies (GWAS) have been used to achieve this goal. In this article, we review recent progress in the identification of genetic variants associated with ADRs using GWAS and discuss emerging themes from these studies. We also compare aspects of GWAS for ADRs to GWAS for common diseases. In the second part of the article, we review progress in performing pharmacogenomic research in multi-ethnic populations and discuss the challenges and opportunities of investigating genetic causes of ADRs in ethnically diverse patient populations.

Prevalence of abnormal glycometabolism in treatment-naive patients with hepatitis C virus infection in a Chinese Han population

BACKGROUND AND AIM

The hepatitis C virus (HCV) may promote pancreatic β-cell apoptosis-like cell death through a caspase 3-dependent pathway, initiating the onset of type 2 diabetes mellitus (T2DM); however, the risk factors for development of T2DM and other abnormal glycometabolic factors in HCV patients of the Chinese Han ethnicity have been poorly explored.

METHODS

A total of 947 patients Chinese Han patients with confirmed HCV infection were enrolled in a multicenter study in order to examine the genetic and physiological parameters associated with the onset of abnormal glycometabolic conditions, including T2DM and prediabetes.

RESULTS

HCV genotype 1b and host interleukin-28B CC genotype were most commonly observed. A total of 145 (15.3%) patients were diagnosed with T2DM and prediabetes. Elevated age, waist circumference, smoking duration, and systolic and diastolic blood pressure were shown to increase risks for abnormal glycometabolism. Liver dysfunction was shown to have positive correlations with abnormal glycometabolism in HCV patients. Genome-wide association studies indicated that certain genetic encoding inosine triphosphatase polymorphs (rs6051702) were associated with elevated risks for abnormal glycometabolism. Coupled with previous research data, it is likely that abnormal glycometabolism may be a useful predictor of risk for poor response to antiviral therapies and treatment-induced complications, such as anemia, in treatment naïve patients.

CONCLUSIONS

Abnormal glycometabolism and other such complications of HCV and HCV treatment may share critical metabolic and genetic pathways, providing potentially novel targets for future antiviral therapies for treatment resistant HCV genotypes.

An index to predict ribavirin-induced anemia in asian patients with chronic genotype 1 hepatitis C

BACKGROUND

Single-nucleotide polymorphisms (SNP) in the inosine triphosphate pyrophosphatase (ITPA) gene correlate with ribavirin (RBV)-induced anemia in patients with chronic hepatitis C (CHC) receiving combination therapy. Managing anemia is an early priority in the treatment process.

OBJECTIVES

The aim was to develop a predictive index based on ITPA SNP status to identify CHC patients at risk of anemia.

PATIENTS AND METHODS

A total of 418 eligible East Asian patients diagnosed with CHC genotype 1 (G1) received combination therapy in this study. Participant DNA was genotyped for a functional ITPA SNP (C/C, A/A or C/A) on chromosome 20 at rs1127354. A predictive index was constructed by incorporating independent factors identified for severe anemia events (hemoglobin < 10 g/dL). Areas under the receiver-operating characteristic curves (AUCs) represented the diagnostic accuracies of the predictive index in randomly assigned development and validation cohorts.

RESULTS

Multiple logistic regressions identified age (≥ 50 y: OR = 9.7, 95% CI = 5.0 - 18.6), ITPA rs1127354 (C/C: OR = 3.3, 95% CI = 1.8 - 5.8) and baseline hemoglobin (< 14.0 g/dL: OR 6.4, 95% CI = 3.3 - 12.1; 14.0 - 14.9: OR = 2.4, 95% CI = 1.2 - 4.6) as predictors of severe anemia throughout the treatment. For severe anemia, the predictive index incorporating age, ITPA SNP status and baseline hemoglobin yielded diagnostic accuracies (AUCs) of 0.830 (95% CI = 0.783 - 0.871) in the development (n = 324) and 0.902 (0.826 - 0.925) in the validation (n = 81) cohorts.

CONCLUSIONS

In patients with CHC G1 and receiving combination therapy, ITPA SNP-based index was an accurate and practical solution for prediction of severe anemia.

Erythropoietin rs1617640 G allele associates with an attenuated rise of serum erythropoietin and a marked decline of hemoglobin in hepatitis C patients undergoing antiviral therapy

BACKGROUND

A decline in hemoglobin (Hb) concentration during antiviral therapy in chronic hepatitis C (CHC) is a serious side effect. It may compel to dose reduction or even termination of antiviral treatment. The activation of erythropoietin (EPO) synthesis as a physiological response to anemia and its relation to a genetic variation within the EPO gene has not been evaluated yet.

METHODS

Data of 348 CHC patients were reviewed retrospectively. Samples were genotyped for EPO rs1617640 and inosine triphosphatase (ITPA) rs1127354. Serum EPO concentrations were determined before and during therapy. Primary endpoints were set as Hb decline >3 g/dl at weeks 4 and 12.

RESULTS

EPO rs1617640 G homozygotes showed a significantly lower rise of serum EPO level over time than T allele carriers (p < 0.001). The cumulative frequency of a significant Hb reduction added up to 40%. Multivariate analysis revealed that besides age, ribavirin starting dose and baseline Hb also EPO rs1617640 G homozygosity associates with Hb reduction at week 4 (p = 0.025) and 12 (p = 0.029), while ITPA C homozygotes are at risk for Hb decline particularly early during treatment. Furthermore, EPO rs1617640 G homozygotes were more frequently in need for blood transfusion, epoetin-α supplementation, or ribavirin dose reduction (p < 0.001).

CONCLUSIONS

Our data suggest that EPO rs1617640 genotype, the rise of serum EPO concentration as well as ITPA rs1127354 genotype are promising parameters to evaluate the Hb decline during antiviral therapy. A rational adjustment of therapy with epoetin-α supplementation might prevent serious adverse events or the need to terminate treatment.

Variants of the inosine triphosphate pyrophosphatase gene are associated with reduced relapse risk following treatment for HCV genotype 2/3

The present study evaluated the impact of variations in the inosine triphosphate pyrophosphatase (ITPase) gene (ITPA) on treatment outcome in patients with hepatitis C virus (HCV) genotype 2/3 infection receiving peginterferon-α2a and lower, conventional 800 mg daily dose of ribavirin. Previous studies using higher, weight-based ribavirin dosing report that patients carrying polymorphisms encoding reduced predicted ITPase activity show decreased risk of ribavirin-induced anemia but increased risk of thrombocytopenia, with no impact on elimination of virus. In all, 354 treatment-naïve HCV genotype 2/3-infected patients, enrolled in a phase III trial (NORDynamIC), were genotyped for ITPA (rs1127354 and rs7270101). Homo- or heterozygosity at Ars1127354 or Crs7270101 , entailing reduced ITPase activity, was observed in 37% of patients and was associated with increased likelihood of achieving sustained virological response (SVR) (P = 0.0003 in univariate and P = 0.0002 in multivariate analyses) accompanied by a reduced risk of relapse among treatment-adherent patients. The association between ITPA variants and SVR remained significant when patients were subdivided by the 12- and 24-week treatment duration arms, HCV genotype, fibrosis stage, and IL28B genotype, and was not secondary to improved adherence to therapy or less pronounced anemia. Gene variants predicting reduced predicted ITPase activity were also associated with decreased risk of anemia (P < 0.0001), increased risk of thrombocytopenia (P = 0.007), and lower ribavirin concentrations (P = 0.02).

CONCLUSION

These findings demonstrate a novel ribavirin-like association between polymorphisms at ITPA and treatment efficacy in chronic hepatitis C mediated by reduced relapse risk. We hypothesize that patients (63%) being homozygous for both major alleles, leading to normal ITPase activity, may benefit more from the addition of ribavirin to present and future treatment regimens for HCV in spite of concomitant increased risk of anemia.

ITPA genotype protects against anemia during peginterferon and ribavirin therapy but does not influence virological response

On-treatment anemia is associated with higher sustained virological response (SVR) rates during peginterferon plus ribavirin (RBV) therapy. Inosine triphosphatase (ITPA) variants causing ITPase deficiency have been shown to protect against RBV-induced anemia. However, ITPase activity has not been associated with SVR. To study this discrepancy, we examined the relationships between ITPase activity, on-treatment anemia, SVR, and RBV levels in hepatitis C virus genotype 1 (HCV-1) patients from the CHARIOT study. ITPA genotype (rs7270101, rs1127354) was used to define ITPase activity in 546 patients. Plasma RBV levels were measured using high-performance liquid chromatography (HPLC). Relationships between ITPase activity, on-treatment hemoglobin (Hb) levels, RBV levels, and SVR were tested using regression modeling, survival analysis, and locally weighted scatterplot smoothing (LOWESS) plot analysis. Hb decline was independently associated with SVR (P<0.0001). ITPase deficiency was present in 35%. ITPase deficiency strongly protected against Hb decline (P<0.0001), but was not associated with SVR (P=0.28). The probability of SVR increased with lower nadir Hb for both wild-type and deficient ITPase activity, but the association curve shifted to describe a parallel relationship at higher Hb levels in patients with ITPase deficiency. In a subset (n=203), we tested the hypothesis that the association between Hb decline and SVR reflected RBV levels rather than actual Hb level. RBV levels were associated with on-treatment Hb decline and SVR, but not ITPase activity. In regression models, adjustment for RBV levels attenuated the association between Hb decline and SVR.

CONCLUSION

ITPase deficiency protects against RBV-induced anemia, but is not associated with SVR. Our data suggest that the relationship between Hb decline and SVR is not mechanistic, but is linked to RBV levels.

Distribution of genetic polymorphisms associated with hepatitis C virus (HCV) antiviral response in a multiethnic and admixed population

The prevalence of genetic polymorphisms identified as predictors of therapeutic-induced hepatitis C virus (HCV) clearance differs among ethnic groups. However, there is a paucity of information about their prevalence in South American populations, whose genetic background is highly admixed. Hence, single-nucleotide polymorphisms rs12979860, rs1127354 and rs7270101 were characterized in 1350 healthy individuals, and ethnicity was assessed in 259 randomly selected samples. The frequency of rs12979860CC, associated to HCV treatment response, and rs1127354nonCC, related to protection against hemolytic anemia, were significantly higher among individuals with maternal and paternal Non-native American haplogroups (64.5% and 24.2%), intermediate among admixed samples (44.1% and 20.4%) and the lowest for individuals with Native American ancestry (30.4% and 6.5%). This is the first systematic study focused on analyzing HCV predictors of antiviral response and ethnicity in South American populations. The characterization of these variants is critical to evaluate the risk-benefit of antiviral treatment according to the patient ancestry in admixed populations.

Review article: genetic factors that modify the outcome of viral hepatitis

BACKGROUND

Genetic factors can play an important role for treatment response and disease progression in chronic viral hepatitis.

AIM

To review the influence of host genetic factors on the clinical course as well as on treatment response in patients with viral hepatitis.

METHODS

Review of the literature.

RESULTS

A landmark genome-wide association study (GWAS) identified polymorphisms in the IL28B gene on chromosome 19 (19q13.13) associated with response to therapy with pegylated interferon-α (PEG-IFN) and ribavirin (RBV) and spontaneous viral clearance in acute hepatitis C. Furthermore, IL28B genotype is associated with changes of lipid metabolism and insulin resistance. A further GWAS demonstrated that ITPA genetic variants protect HCV genotype 1 patients from RBV-induced anaemia. Another polymorphism in the patatin-like phospholipase domain containing 3 (PNPLA3) is associated with hepatic steatosis. Difficult-to-treat hepatitis C patients homozygous for GG had an up to five-fold lower chance of viral clearance on PEG/RBV than non-GG patients. In chronic hepatitis B patients treated with PEG-IFN several retrospective analyses of IL28B rs12980275 and rs12979860 genotypes yielded conflicting results which can be explained by the heterogeneity between the study populations. Some variants of the HLA-DP locus (HLA-DPA1 A allele and HLA-DPB1) protect against progression of chronic hepatitis B infection.

CONCLUSIONS

The determination of IL28B polymorphisms may be useful to individualise treatment options when using PEG/RBV based therapies for chronic hepatitis C infection. In contrast, so far identified genetic factors play only a minor role in chronic hepatitis B infection.

Individualization of chronic hepatitis C treatment according to the host characteristics

Hepatitis C virus (HCV) infection is a global health problem that affects more than 170 million people worldwide. It is a major cause of cirrhosis and hepatocellular carcinoma, making the virus the most common cause of liver failure and transplantation. The standard-of-care treatment for chronic hepatitis C (CHC) has been changed during the last decade and direct acting antiviral drugs have already been used. Besides, understanding of the pathogenesis of CHC has evolved rapidly during the last years and now several host factors are known to affect the natural history and response to treatment. Recent genome-wide association studies have shown the important role of interleukin-28B and inosine triphosphatase in HCV infection. The present review article attempts to summarize the current knowledge on the role of host factors towards individualization of HCV treatment.

The role of pharmacogenetics in the treatment of chronic hepatitis C infection

Hepatitis C virus (HCV) chronically infects 170 million people worldwide. Until recently, combination therapy with peginterferon-α (pegIFN) and ribavirin (RBV) has been the standard of care. However, for many patients, especially those infected with the most common HCV genotype 1 (HCV-1), this treatment has resulted in unsatisfactory treatment response rates. Many clinical factors, including pharmacogenetics, influence the treatment response rate. Genetic variation in the interleukin 28B (IL28B) gene is the major determinant of treatment response, a finding that has been replicated in multiple independent cohorts. This review focuses on the association between pharmacogenetics and conventional pegIFN/RBV therapy in patients infected with HCV non-genotype 1; patients reinfected with HCV after liver transplantation; and patients coinfected with HCV and human immunodeficiency virus. We also review the pharmacogenetic data for boceprevir and telaprevir triple therapy in patients with HCV-1 infection, as well as viral genomic polymorphisms and genetic variants that may protect against anemia. Pharmacogenetic information offers a personalized medicine approach to help clinicians and patients make better informed decisions to maximize response and minimize toxicity for the treatment of chronic HCV infection.

Individualized therapy for hepatitis C infection: focus on the interleukin-28B polymorphism in directing therapy

Hepatitis C virus—a major global cause of chronic hepatitis, cirrhosis, and hepatocellular carcinoma—affects millions of people worldwide. Pegylated interferon (Peg-IFN) and ribavirin (RBV) had been the standard treatment for a decade until availability of the protease inhibitors in 2011. However, current antiviral therapy is still IFN-based and is associated with significant side effects and variable treatment response. Thus, various host and viral factors have been evaluated before and during treatment for the prediction of sustained virologic response to antiviral therapy. In 2009, genome-wide association studies found the single-nucleotide polymorphisms, located near the host interleukin-28B (IL28B) gene that encodes IFN-λ3, to be the best pretreatment predictor of virologic response to Peg-IFN and RBV therapy in chronic hepatitis C genotype 1 patients. Additionally, inosine triphosphatase (ITPA) gene variants were found to be associated with RBV-induced hemolytic anemia, which could affect treatment dose for selected patients. IL28B, ITPA, and other treatment predictors allowed for a potential individualized approach to treat hepatitis C. In the era of increased overall virologic response rates and good tolerability of the rapidly developing non-IFN oral direct-acting antiviral therapy regimens, the need for individualized treatment is likely to diminish. Various predictors of response, including IL28B will likely be of reduced importance in the near future.

Inosine triphosphatase deficiency helps predict anaemia, anaemia management and response in chronic hepatitis C therapy

Anaemia frequently complicates peginterferon/ribavirin therapy for chronic hepatitis C infection. Better prediction of anaemia, ribavirin dose reduction or erythropoietin (EPO) need, may enhance patient management. Inosine triphosphatase (ITPA) genetic variants are associated with ribavirin-induced anaemia and dose reduction; however, their impact in real-life clinic patient cohorts remains to be defined. We studied 193 clinic patients with chronic hepatitis C infection of mixed viral genotype (genotype 1/4 n = 123, genotype 2/3, n = 70) treated with peginterferon/ribavirin. Patients were genotyped for ITPA polymorphisms rs1127354 and rs7270101 using Taqman primers. Hardy-Weinberg equilibrium was present. Estimated ITPA deficiency was graded on severity (0-3, no deficiency/mild/moderate/severe, n = 126/40/24/3, respectively). Multivariable models tested the association with anaemia at 4 weeks of treatment [including decline in haemoglobin (g/dL); haemoglobin <10 g/dL and haemoglobin decline >3 g/dL]; ribavirin dose reduction and EPO use and explored sustained viral response (SVR) to peginterferon/ribavirin. More severe ITPA deficiency was associated with less reduction in haemoglobin level (P <0.001; R(2) = 0.34), less ribavirin dose reduction (OR 0.42; (95% CI = 0.23-0.77); P = 0.005) and less EPO use [OR 0.53; (0.30-0.94); P = 0.029]. ITPA deficiency was associated with SVR [OR: 1.70; (1.02-2.83); P = 0.041] independently of clinical covariates (adjusted R(2) = 0.31). In this clinical cohort, ITPA deficiency helped predict the risk of on-treatment anaemia, ribavirin dose reduction, need for EPO support and was associated with SVR. For patients on HCV regimens including peginterferon/ribavirin, testing for ITPA deficiency may have clinical utility.

Effect of gender and ITPA polymorphisms on ribavirin-induced anemia in chronic hepatitis C patients

BACKGROUND & AIMS

Single nucleotide polymorphisms (SNPs) in the inosine triphosphate pyrophosphatase (ITPA) gene protect patients from ribavirin induced anemia. To investigate other possible protective cofactors, gender differences were analyzed in patients with HCV genotype 1.

METHODS

Hemoglobin levels at baseline (Hb0) and the decline after 4 weeks of treatment (HbΔ4) were analyzed in 308 chronic hepatitis C patients participating in 5 Austrian trials (n=308, age 43.9 ± 11.1, male:185, female:123, BMI 25.3 ± 3.9, no cirrhosis: n=259, liver cirrhosis: n=49). All patients were treated with 180 μg peginterferon-alpha 2a and ribavirin [1000-1200 mg/d; females: mean (95% CI) 15.8 mg/kg (15.4-16.2); males 14.3 (14.1-14.5); p<0.001]. The SNPs rs6051702, rs1127354, rs7270101 and IL28B rs12979860 were analyzed by the StepOnePlus Real time PCR System.

RESULTS

188 were major alleles homozygotes; 95 (30.8%) carried the minor allele (C) of rs6051702, 47 (15.3%) of rs1127354 (A), and 69 (22.4%) of rs7270101 (C). The overall Hb0 was 14.8 g/dl (14.6-14.9) [mean (95%CI); females 13.7 (13.5-13.9); males 15.5; 15.3-15.6; p<0.001]. The overall HbΔ4 was greater in major allele homozygotes [2.8 g/dl (2.6-3.0)] than in minor allele carriers [1.6 (1.4-1.9); p<0.001]. Irrespective of the ITPA genotypes HbΔ4 was smaller in female [2.0 (1.7-2.2)] than in male patients [2.6 (2.4-2.8); p<0.001] and among females in premenopausal [1.5 (1.3-1.8)] than in postmenopausal patients [2.7 (2.3-3.1); p<0.001].

CONCLUSIONS

Irrespective of the protective effect of ITPA mutations, premenopausal females less likely develop ribavirin induced anemia.

Association of ITPA polymorphism with outcomes of peginterferon-α plus ribavirin combination therapy

AIM: To analyzed the association between inosine triphosphatase (ITPA) (rs1127354) genotypes and sustained virological response (SVR) rates in peginterferon (Peg-IFN)α + ribavirin (RBV) treatment.

METHODS: Patients who underwent Peg-IFNα + RBV combination therapy were enrolled (n = 120) and they had no history of other IFN-based treatments. Variation in hemoglobin levels during therapy, cumulative reduction of RBV dose, frequency of treatment withdrawal, and SVR rates were investigated in each ITPA genotype.

RESULTS: In patients with ITPA CC genotype, hemoglobin decline was significantly greater and the percentage of patients in whom total RBV dose was < 60% of standard and/or treatment was withdrawn was significantly higher compared with CA/AA genotype. However, SVR rates were equivalent between CC and CA/AA genotypes, and within a subset of patients with Interleukin 28B (IL28B) (rs8099917) TT genotype, SVR rates tended to be higher in patients with ITPA CC genotype, although the difference was not significant.

CONCLUSION: ITPA CC genotype was a disadvantageous factor for Peg-IFNα + RBV treatment in relation to completion rates and RBV dose. However, CC genotype was not inferior to CA/AA genotype for SVR rates. When full-length treatment is accomplished, it is plausible that more SVR is achieved in patients with ITPA CC variant, especially in a background of IL28B TT genotype.

Pre-treatment role of inosine triphosphate pyrophosphatase polymorphism for predicting anemia in Egyptian hepatitis C virus patients

AIM: To investigate and clarify, for the first time, the role of inosine triphosphate pyrophosphatase (ITPA) polymorphism in Egyptian chronic hepatitis C virus (HCV) patients.

METHODS: The human genomic DNA of all patients was extracted from peripheral blood cells in order to determine the single nucleotide polymorphism (SNP) of ITPA (rs1127354). SNP genotyping was performed by real time polymerase chain reaction (PCR, ABI TaqMan allelic discrimination kit) for 102 treatment-naive Egyptian patients with chronic HCV. All patients had no evidence of cardiovascular or renal diseases. They received a combination treatment of pegylated interferon α (PEG-IFNα) as a weekly subcutaneous dose plus an oral weight-adjusted dose of ribavirin (RBV). The majority received PEG-IFNα2a (70.6%) while 29.4% received PEG-IFNα2b. The planned duration of treatment was 24-48 wk according to the viral kinetics throughout the course of treatment. Pre-treatment liver biopsy was done for each patient for evaluation of fibrosis stage and liver disease activity. The basal viral load level was detected quantitatively by real time PCR while viral load throughout the treatment course was performed qualitatively by COBAS TaqMan assay.

RESULTS: Ninety-three patients (91.2%) had ITPA SNP CC genotype and 9 (8.8%) had non-CC genotype (CA and AA). The percentage of hemoglobin (Hb) decline was higher for CC patients than for non-CC patients, particularly at weeks 4 and 8 (P = 0.047 and 0.034, respectively). During the first 12 wk of treatment, CC patients had significantly more Hb decline > 3 g/dL than non-CC patients: 64.5% vs 22.2% at weeks 8 and 12, respectively, (P = 0.024 and 0.038). Reduction of the amount of the planned RBV dose was significantly higher for CC patients than non-CC patients during the first 12 wk (18% ± 12.1% vs 8.5% ± 10.2%, P = 0.021). The percentage of CC patients with RBV dose reduction was significantly greater than that of non-CC patients (77.4% vs 44.4%, P = 0.044). Multivariate analysis identified only the percentage of RBV dose as a predictor for Hb decline. Platelet decline was significantly higher in non-CC patients than CC patients at weeks 12, 24 and 48 (P = 0.018, 0.009 and 0.026, respectively).

CONCLUSION: Rs1127354 ITPA polymorphism plays a decisive role in protecting against treatment-induced anemia and the need for RBV dose reduction in Egyptian HCV patients.

Role of IL-28B and inosine triphosphatase polymorphisms in efficacy and safety of Peg-Interferon and ribavirin in chronic hepatitis C compensated cirrhosis with and without oesophageal varices

Genetic factors can influence the outcome of antiviral therapy in chronic hepatitis C (HCV). We evaluated the role of interleukin-28B single nucleotide polymorphisms (SNPs) and inosine triphosphatase (ITPA) gene variants in HCV cirrhosis treated with Peg-Interferon and ribavirin. A prospective cohort of 233 patients with compensated cirrhosis received 1-1.5 μg/kg/week of Peg-Interferon alpha-2b plus 1000-1200 mg/day of RBV for 48 weeks. A sustained virologic response (SVR) was achieved in 27% of patients. On multivariate logistic analysis, the absence of oesophageal varices (OR 3.64 CI 95% 1.27-10.44 P = 0.016), infection with genotype 2 or 3 (OR 4.06, CI 95% 1.08-15.26, P = 0.038), C/C alleles of rs12979860 SNP (OR 7.04, CI 95% 2.40-20.72, P < 0.001) and rapid virologic response (RVR) (OR 78.29, CI 95% 16.07-381.29, P < 0.001) were independently associated with SVR. Patients who experienced post-treatment relapse received lower total doses of Peg-Interferon (52.0 ± 15.8 μg/kg vs 65.7 ± 13.3 μg/kg, P < 0.001) and lower total dose of RBV (3829 ± 1210 mg vs 4709 ± 954 mg, P < 0.001) than patients who achieved an SVR. ITPA variants predictive of high ITPase activity were associated with reduction of haemoglobin ≥3 g/dL in the first 4 weeks (P < 0.001), and with reduction of haemoglobin <10 g/dL (P = 0.03) on treatment. In conclusion, combination therapy with Peg-Interferon and RBV in patients with HCV cirrhosis must be guided by virus genotype, severity of portal hypertension, favourable IL-28B polymorphisms and ITPA variants, and RVR on treatment.

Model incorporating the ITPA genotype identifies patients at high risk of anemia and treatment failure with pegylated-interferon plus ribavirin therapy for chronic hepatitis C

This study aimed to develop a model for predicting anemia using the inosine triphosphatase (ITPA) genotype and to evaluate its relationship with treatment outcome. Patients with genotype 1b chronic hepatitis C (n = 446) treated with peg-interferon alpha and ribavirin (RBV) for 48 weeks were genotyped for the ITPA (rs1127354) and IL28B (rs8099917) genes. Data mining analysis generated a predictive model for anemia (hemoglobin (Hb) concentration <10 g/dl); the CC genotype of ITPA, baseline Hb <14.0 g/dl, and low creatinine clearance (CLcr) were predictors of anemia. The incidence of anemia was highest in patients with Hb <14.0 g/dl and CLcr <90 ml/min (76%), followed by Hb <14.0 g/dl and ITPA CC (57%). Patients with Hb ≥ 14.0 g/dl and ITPA AA/CA had the lowest incidence of anemia (17%). Patients with two predictors (high-risk) had a higher incidence of anemia than the others (64% vs. 28%, P < 0.0001). At baseline, the IL28B genotype was a predictor of a sustained virological response [adjusted odds ratio 9.88 (95% confidence interval 5.01-19.48), P < 0.0001]. In patients who achieved an early virological response, the IL28B genotype was not associated with a sustained virological response, while a high risk of anemia was a significant negative predictor of a sustained virological response [0.47 (0.24-0.91), P = 0.026]. For high-risk patients with an early virological response, giving >80% of the planned RBV dose increased sustained virological responses by 24%. In conclusion, a predictive model incorporating the ITPA genotype could identify patients with a high risk of anemia and reduced probability of sustained virological response.

Add-on therapy of pitavastatin and eicosapentaenoic acid improves outcome of peginterferon plus ribavirin treatment for chronic hepatitis C

Despite the use of pegylated-interferon (peg-IFN) plus ribavirin combination therapy, many patients infected with hepatitis C virus (HCV)-1b remain HCV-positive. To determine whether addition of pitavastatin and eicosapentaenoic acid (EPA) is beneficial, the "add-on" therapy option (add-on group) was compared retrospectively with unmodified peg-IFN/ribavirin therapy (standard group). Association of host- or virus-related factors with sustained virological response was assessed. In HCV replicon cells, the effects of pitavastatin and/or EPA on HCV replication and expression of innate-immunity- and lipid-metabolism-associated genes were investigated. In patients infected with HCV-1b, sustained virological response rates were significantly higher in the add-on than standard group. In both groups, sustained virological response rates were significantly higher in patients with genotype TT of IL-28B (rs8099917) than in those with non-TT genotype. Among the patients with non-TT genotype, sustained virological response rates were markedly higher in the add-on than standard group. By multivariate analysis, genome variation of IL28B but not add-on therapy remained as a predictive factor of sustained virological response. In replicon cells, pitavastatin and EPA suppressed HCV replication. Activation of innate immunity was obvious in pitavastatin-treated cells and EPA suppressed the expression of sterol regulatory element binding protein-1c and low-density lipoprotein receptor. Addition of pitavastatin and EPA to peg-IFN/ribavirin treatment improved sustained virological response in patients infected with HCV-1b. Genotype variation of IL-28B is a strong predictive factor in add-on therapy.

Pharmacogenetics of efficacy and safety of HCV treatment in HCV-HIV coinfected patients: significant associations with IL28B and SOCS3 gene variants

BACKGROUND AND AIMS

This was a safety and efficacy pharmacogenetic study of a previously performed randomized trial which compared the effectiveness of treatment of hepatitis C virus infection with pegylated interferon alpha (pegIFNα) 2a vs. 2b, both with ribavirin, for 48 weeks, in HCV-HIV coinfected patients.

METHODS

The study groups were made of 99 patients (efficacy pharmacogenetic substudy) and of 114 patients (safety pharmacogenetic substudy). Polymorphisms in the following candidate genes IL28B, IL6, IL10, TNFα, IFNγ, CCL5, MxA, OAS1, SOCS3, CTLA4 and ITPA were assessed. Genotyping was carried out using Sequenom iPLEX-Gold, a single-base extension polymerase chain reaction. Efficacy end-points assessed were: rapid, early and sustained virological response (RVR, EVR and SVR, respectively). Safety end-points assessed were: anemia, neutropenia, thrombocytopenia, flu-like syndrome, gastrointestinal disturbances and depression. Chi square test, Student's T test, Mann-Whitney U test and logistic regression were used for statistic analyses.

RESULTS

As efficacy is concerned, IL28B and CTLA4 gene polymorphisms were associated with RVR (p<0.05 for both comparisons). Nevertheless, only polymorphism in the IL28B gene was associated with SVR (p = 0.004). In the multivariate analysis, the only gene independently associated with SVR was IL28B (OR 2.61, 95%CI 1.2-5.6, p = 0.01). With respect to safety, there were no significant associations between flu-like syndrome or depression and the genetic variants studied. Gastrointestinal disturbances were associated with ITPA gene polymorphism (p = 0.04). Anemia was associated with OAS1 and CTLA4 gene polymorphisms (p = 0.049 and p = 0.045, respectively), neutropenia and thromobocytopenia were associated with SOCS3 gene polymorphism (p = 0.02 and p = 0.002, respectively). In the multivariate analysis, the associations of the SOCS3 gene polymorphism with neutropenia (OR 0.26, 95%CI 0.09-0.75, p = 0.01) and thrombocytopenia (OR 0.07, 95%CI 0.008-0.57, p = 0.01) remained significant.

CONCLUSIONS

In HCV-HIV coinfected patients treated with PegIFNα and ribavirin, SVR is associated with IL28B rs8099917 polymorphism. HCV treatment-induced neutropenia and thrombocytopenia are associated with SOCS3 rs4969170 polymorphism.

The role of viral and host genetics in natural history and treatment of chronic HCV infection

Understanding of the natural history and treatment responsiveness of chronic hepatitis C virus (HCV) infection has evolved rapidly in recent years. Advances in HCV molecular virology and host genetics can now better predict spontaneous clearance and treatment outcomes. HCV genotype is the most important viral factor predicting interferon-α treatment responsiveness; HCV-1 subtype is emerging as a key determinant of the efficacy of direct acting antiviral therapy. Genome-wide association studies have recently identified several clinically important host determinants of the outcomes of peginterferon-α and ribavirin treatment outcome: IL28B polymorphism is associated with spontaneous clearance and treatment responsiveness; ITPA polymorphism protects against ribavirin-induced anaemia and dose reductions; genetic determinants of liver fibrosis progression rate have been proposed. In this review, we evaluate the role of viral and host genetics in the natural history and treatment outcomes of chronic HCV infection, and consider how this knowledge might help individualize clinical management in the era of DAA therapy.

Genetic variants at the ITPA locus protect against ribavirin-induced hemolytic anemia and dose reduction in an HCV G2/G3 cohort

OBJECTIVES

Two functional genetic variants in the inosine triphosphatase (ITPA) gene have been shown to be strongly associated with protection from ribavirin (RBV)-induced hemolysis. We aimed at evaluating this finding in a chronic hepatitis C genotype 2/3 cohort with a predominance of genotype 3 patients where available data are scarce. A second objective was to determine whether a protective association translated into the need for RBV reduction and hence a possible impact on treatment response.

METHODS

Overall, 457 patients were recruited from two trials of genotype 2/3 patients treated with pegylated interferon α-2b and weight-based RBV. rs1127354 and rs7270101 were genotyped and a composite ITPAase deficiency variable was graded according to the two single nucleotide polymorphisms. The primary endpoints were hemoglobin (Hb) decline from baseline and Hb decline of more than 3 g/dl at week 4.

RESULTS

Both single nucleotide polymorphisms and the composite ITPAase deficiency variable were strongly and independently associated with protection from a decline in Hb at week 4 in multivariate linear regression models (Prs1127354=7.0×10, Prs7270101=0.0036, PITPase deficiency variable =6.3×10). Patients with any degree of reduced ITPAase activity were less likely to have their RBV dose reduced (odds ratio 0.39, 95% confidence interval 0.16-0.96, P=0.040), although this did not translate into increased rapid viral response or sustained viral response (Prvr=0.93, Psvr=0.22).

CONCLUSION

We have confirmed a strong association between functional ITPA variants and RBV-induced hemolysis and showed protection from RBV dose reduction, although this did not translate into increased rapid viral response or sustained viral response.

A formula to estimate the optimal dosage of ribavirin for the treatment of chronic hepatitis C: influence of ITPA polymorphisms

BACKGROUND

Greater cumulative exposure to ribavirin increases response to interferon-ribavirin combination therapy for hepatitis C but also induces more severe anaemia. Polymorphisms in the ITPA gene protect against ribavirin-induced anaemia. The maximum dosage of ribavirin that can be tolerated by patients with different ITPA polymorphisms remains unknown.

METHODS

We developed a mathematical model of haemoglobin (Hb) decline in patients undergoing combination therapy. Using it to analyse published patient data, we estimated the average erythrocyte lifespan in patients with different ITPA polymorphisms. Coupled with a previous population pharmacokinetic study, we derived a formula for predicting the optimal ribavirin dosage, D(opt), above which anaemia becomes intolerable (Hb<10 g/dl).

RESULTS

Our model provided good fits to patient data of ribavirin accumulation in erythrocytes and the ensuing Hb decline during therapy. With the current treatment protocol, the average erythrocyte lifespan was approximately 36 days in patients with wild-type ITPA activity, and approximately 43 days and 55 days, respectively, in patients with mild and moderate ITPA deficiency. Our model yielded a facile formula for estimating D(opt) given a patient's weight, creatinine clearance, pretreatment Hb and ITPA polymorphism. Patients with moderate ITPA deficiency are predicted to tolerate twice the ribavirin dosage as patients with wild-type ITPA.

CONCLUSIONS

Our formula for D(opt) presents an avenue for personalizing ribavirin dosage. By keeping anaemia tolerable, the predicted optimal dosage may improve adherence, reduce the need for drug monitoring, and increase response rates. Response rates may be increased further by the higher dosages recommended for patients with ITPA deficiency.

Treating hepatitis C: current standard of care and emerging direct-acting antiviral agents

Summary.  During the late 1990s and early 2000s, major advances were made in the treatment of patients with chronic hepatitis C virus (HCV) infection. Interferon, combination interferon plus ribavirin (RBV) and pegylated interferon plus RBV increased sustained virologic response (SVR) rates from ~5% to ~40-80%, depending on the genotype of HCV infection. Advances in molecular biology have allowed investigators to begin to understand the mechanisms of HCV infection and replication. Advances in understanding of viral kinetics have provided tools to identify patients who are most likely to attain SVR. With the advances in the science of HCV infection, the first part of the 21st century has seen the development and early introduction of a number of direct-acting antiviral (DAA) drugs. These novel medications interfere with critical steps in HCV replication and have the potential to significantly increase SVR rates. This article will review the key elements of HCV replication and evaluate the various classes of new and investigational DAA that have the potential to create a revolution in the management of patients with chronic hepatitis C.

ITPA gene polymorphisms significantly affect hemoglobin decline and treatment outcomes in patients coinfected with HIV and HCV

Published studies have described a strong association with a single-nucleotide polymorphism (SNP) in the inosine triphosphate pyrophosphatase (ITPA) gene and ribavirin (RBV)-induced hemolytic anemia in HCV-infected patients receiving pegylated interferon (pegIFN) and RBV. This study sought to evaluate the effect of these polymorphisms on anemia, hemoglobin reduction, HCV kinetics, and treatment outcomes. Sixty-three patients coinfected with HIV and HCV and 58 patients infected with HCV only were treated with pegIFN/RBV were genotyped using the ABI TaqMan allelic discrimination kit for the 2 ITPA SNP variants rs1127354 and rs7270101. A composite variable of ITPA deficiency using both SNPs was created as previously reported. Statistical analysis was performed using Mann-Whitney test or Chi square/Fishers exact test for categorical data and mixed model analysis for multiple variables. Thirty-five patients (30%) were predicted to have reduced ITPA activity. ITPA deficiency was found to be protective against the development of hemoglobin reduction >3 g/dl over the course of treatment. The rates of hemoglobin reduction >3 g/dl decreased in correlation with the severity of ITPA deficiency. ITPA deficiency was associated with slower hemoglobin decline early in treatment (week 4, P = 0.020) and rapid virologic response (RVR) at week 4 (P = 0.017) in patients coinfected with HIV and HCV. ITPA polymorphisms are associated with hemoglobin decline and in patients coinfected with HIV and HCV it is also associated with early virologic outcomes. Determination of ITPA polymorphisms may allow prediction of RBV-induced anemia and earlier initiation of supportive care to ensure optimal therapeutic outcomes.