Variants in the ITPA gene protect against ribavirin-induced hemolytic anemia in HIV/HCV-coinfected patients with all HCV genotypes

Inosine triphosphate pyrophosphatase polymorphisms are predictors of anemia in Chinese patients with chronic hepatitis C during therapy with ribavirin and interferon

BACKGROUND AND AIM

Polymorphisms of inosine triphosphate pyrophosphatase (rs1127354 and rs6051702) and interferon lambda 4 (IFLN4) (rs12979860) are indicators of anemia and/or sustained virological response (SVR) in patients with chronic hepatitis C on ribavirin/interferon. The study aims to investigate the associations of rs1127354, rs6051702, and rs12979860 with hemoglobin levels and SVR in patients on ribavirin/interferon.

METHODS

Polymorphisms were detected by pyrosequencing. Levels of hemoglobin and hepatitis C virus (HCV) RNA were measured at weeks 2, 4, 12, 24, 36, 48, and 72 of treatment.

RESULTS

A total of 351 patients (median age, 50 years; male, 71.2%) were recruited and had HCV genotypes 1b (55.8%) or 2a (37.0%). Vedian baseline hemoglobin and HCV RNA were 155 g/dL and 6.07 log₁₀ IU/mL. Major allele homozygosity was observed in 76.3% for rs1127354 (CC), 70.9% for rs6051702 (AA), and 89.7% for rs12979860 (CC). At 4 weeks of ribavirin/interferon treatment, a more significant reduction in hemoglobin was observed with rs112754 CC than with AC/AA (P < 0.05). A decline ≥3 g/dL was more common in patients with the rs112754 CC than with the other two polymorphisms. No significant change was observed regarding rs6051702 and rs12979860 variants. In the multivariable analysis, rs1127354 AA/AC (vs CC) were independently associated with lower odds of hemoglobin decline of > 3 g/dL at 4 weeks (odds ratio, 0.21; 95% CI, 0.09-0.46; P < 0.0001). In 258 patients with 72-week outcome data available, rs1127354, rs6051702, and rs12979860 were not associated with SVR (all P > 0.05).

CONCLUSION

rs1127354 polymorphisms are associated with hemoglobin levels in Chinese patients with chronic hepatitis C treated with ribavirin/interferon.

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.

Reduced ITPase activity and favorable IL28B genetic variant protect against ribavirin-induced anemia in interferon-free regimens

BACKGROUND

Genetic variants of inosine triphosphatase (ITPA) that confer reduced ITPase activity are associated with protection against ribavirin(RBV)-induced hemolytic anemia in peginterferon(IFN)/RBV-based treatment of hepatitis C virus (HCV). Patients with reduced ITPase activity showed improved treatment efficacy when treated with IFN/RBV. In addition, a genetic polymorphism near the IL28B gene is associated with an improved response to IFN/RBV treatment. RBV has been an important component of IFN-containing regimens, and is currently recommended in combination with several IFN-free regimens for treatment of harder to cure HCV infections.

AIM

To evaluate whether genetic variations that reduce ITPase activity impact RBV-induced anemia in IFN-free/RBV regimens.

METHODS

In this study, genetic analyses were conducted in the PEARL-IV trial to investigate the effect of activity-reducing ITPA variants as well as IL28B polymorphism on anemia, platelet (PLT) counts, and virologic response in HCV genotype1a-infected patients treated with the direct-acting antiviral (DAA) regimen of ombitasvir/paritaprevir/ritonavir and dasabuvir±RBV.

RESULTS

Reduction in ITPase activity and homozygosity for the IL28Brs12979860 CC genotype protected against RBV-induced anemia. In patients receiving RBV, reduced ITPase activity was associated with reduced plasma RBV concentration and higher PLT counts. ITPase activity had no impact on response to DAA treatment, viral kinetics, or baseline IP-10 levels.

CONCLUSIONS

Our study demonstrates that genetics of ITPA and IL28B may help identify patients protected from RBV-induced anemia when treated with IFN-free regimens. Our work demonstrates for the first time that IL28B genetics may also have an impact on RBV-induced anemia. This may be of particular significance in patients with difficult-to-cure HCV infections, such as patients with decompensated cirrhosis where RBV-containing regimens likely will continue to be recommended.

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.

Effects of ribavirin/sofosbuvir treatment and ITPA phenotype on endogenous purines

Ribavirin (RBV), a purine analog, causes hemolytic anemia in some patients. In vitro, anemia appears to result from depletion of endogenous purines, but there are limited data in vivo. Single nucleotide polymorphisms in the gene encoding the inosine triphosphatase (ITPA) enzyme have been associated with protection against RBV-induced anemia and may mediate the effect of RBV treatment on endogenous purines. The purpose of this work was to determine the effect of RBV treatment on endogenous purine concentrations in individuals being treated for chronic hepatitis C virus (HCV) infection. Adenosine triphosphate (ATP), guanosine triphosphate (GTP), inosine triphosphate (ITP) and ribavirin triphosphate (RTP) were measured in whole blood obtained from 47 HCV-infected individuals at day zero (baseline), day three, day 28 and day 84 of RBV/sofosbuvir (SOF) treatment. ATP decreased -35.1% and -38.6% (p < 0.0001) at day 28 and day 84 of treatment, respectively compared to baseline. The decrease in ATP was greater in patients with ≤60% ITPA activity compared to those with 100% ITPA activity (-29.4% vs. -9.6%). GTP did not change during treatment but was 16.5% (p = 0.01) higher per 100 pmol/106 cells RTP in those with 100% ITPA activity. No significant change or effect of RTP or ITPA phenotype was noted for ITP. In summary, only ATP was reduced by RBV/SOF treatment and ITPA variants had larger reductions in ATP suggesting RBV-induced anemia is due to a different mechanism than predicted from in-vitro studies. These data emphasize the importance of characterizing the effect of nucleos(t)ide analog treatment on endogenous purines in-vivo.

Variant Inosine Triphosphatase Phenotypes Are Associated With Increased Ribavirin Triphosphate Levels

Individuals with lower inosine triphosphatase (ITPA) enzyme activity have a reduced likelihood of experiencing hemolytic anemia during hepatitis C virus (HCV) treatment containing ribavirin (RBV). Because ITPA degrades purines and RBV is a purine analogue, it is conceivable that ITPA activity may affect intracellular RBV concentrations. Here we assessed the association between ITPA activity phenotype and concentrations of RBV triphosphate (RBV-TP) in red blood cells (RBCs) during HCV treatment. RBV-TP was quantified in the RBCs of 177 HCV-infected individuals at a median (range) of 84 (19 to 336) days into HCV treatment that included RBV. Mean (SD) RBV-TP concentrations were 92.8 (51.6), 101.3 (53.5), 184.8 (84.5), and 197.7 (64.6) pmol/106 cells for 100%, 60%, 30%, and ≤10% ITPA activity groups, respectively. Overall, RBV-TP was approximately 2-fold higher in patients with ≤30% ITPA activity compared to 100% activity (P < .0001). Despite higher RBV-TP levels, individuals with variant ITPA phenotypes had less anemia. The 100% activity group had, on average, a -2.20 g/dL drop in hemoglobin vs -1.43 g/dL (P = .04) for 60% activity, -1.14 g/dL (P = .008) for 30% activity, and -0.70 g/dL (P = .06) for ≤10% activity. This finding of higher RBV-TP concentrations in RBCs in ITPA variants was unexpected given that ITPA activity-deficient individuals have a reduced likelihood of RBV-induced anemia. It also refutes the hypothesis that the mechanism by which ITPA variants are protected against anemia is due to lower RBV-TP levels in RBCs.

Impact of ITPA gene polymorphisms on the risk of ribavirin-induced haemolytic anaemia using interferon-free antivirals for chronic hepatitis C

BACKGROUND

Single nucleotide polymorphisms (SNPs) at the ITPA gene are associated with haemolytic anaemia in chronic hepatitis C patients treated with pegylated interferon-ribavirin (RBV). Information in patients treated with interferon-free, direct-acting antivirals (DAA) is scarce.

METHODS

Median haemoglobin (Hb) levels were compared at baseline and at week 4, when ribavirin concentration achieves steady state, in all consecutive chronic hepatitis C patients treated with oral DAA plus RBV at our clinic.

RESULTS

Median Hb drop in 55 patients was greater in rs1127354-CC than -CA/AA (1.8 versus 0.7 g/dl; P=0.029), and in rs6051702-AA than -AC/CC carriers (2.2 versus 1.1 g/dl; P=0.016). Eleven (20%) patients experienced severe anaemia, defined as Hb drop >3 g/dl or to <10 g/dl. All of them were rs6051702-AA.

CONCLUSIONS

Baseline testing of rs6051702 may identify the subset of patients at greatest risk for RBV-induced anaemia using interferon-free hepatitis C therapies.

ITPA deficiency and ribavirin level are still predictive of anaemia in HCV-HIV-coinfected patients receiving ribavirin combined with a first-generation DAA (ANRS HC27 study)

BACKGROUND

We aimed to determine the impact of inosine triphosphatase (ITPA) deficiency on ribavirin (RBV)-induced anaemia in HIV-HCV-coinfected patients receiving a triple therapy including the haematotoxic direct-acting antiviral agent boceprevir (BOC).

METHODS

Patients of the ANRS HC27 BocepreVIH study were genotyped for two ITPA single nucleotide polymorphisms involved in ITPA deficiency. RBV trough concentration (Ctrough) was determined at week (W)4 and W8. Impact of ITPA deficiency on anaemia, RBV Ctrough, response and haematotoxicity (grade 3/4 anaemia, erythropoietin [EPO] use, RBV dose reduction or transfusion between day [D]0 and W8) was evaluated. Impact of RBV Ctrough on anaemia was also studied.

RESULTS

Among the 63 genotyped patients, 33% had a predicted ITPA deficiency. ITPA deficiency was associated with a lower haemoglobin (Hb) decline both at W4 (-1.0 g/dl versus -2.1 g/dl; P=0.02) and W8 (-2.7 g/dl versus -4.1 g/dl; P=0.05). None of the patients with ITPA deficiency received EPO between D0-W8 versus 26% of patients without ITPA deficiency (P=0.01). RBV Ctrough was associated with Hb decrease both at W4 and W8 and an RBV Ctrough cutoff value of 2 µg/ml was significantly associated with a W4 Hb decline >2 g/dl. Haematotoxicity was significantly associated with a lower W4 Hb level (P=0.017), absence of ITPA deficiency (P=0.018) and higher RBV Ctrough (P=0.012). ITPA deficiency, W4 RBV Ctrough and gender were independent predictors of anaemia at W4. ITPA deficiency was not associated with virological response.

CONCLUSIONS

ITPA deficiency and RBV Ctrough are still predictive of RBV-induced anaemia in HIV-HCV-coinfected patients treated with RBV combined with a first-generation direct antiviral agent.

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.

HIV-1 Promoter Single Nucleotide Polymorphisms Are Associated with Clinical Disease Severity

The large majority of human immunodeficiency virus type 1 (HIV-1) markers of disease progression/severity previously identified have been associated with alterations in host genetic and immune responses, with few studies focused on viral genetic markers correlate with changes in disease severity. This study presents a cross-sectional/longitudinal study of HIV-1 single nucleotide polymorphisms (SNPs) contained within the viral promoter or long terminal repeat (LTR) in patients within the Drexel Medicine CNS AIDS Research and Eradication Study (CARES) Cohort. HIV-1 LTR SNPs were found to associate with the classical clinical disease parameters CD4⁺ T-cell count and log viral load. They were found in both defined and undefined transcription factor binding sites of the LTR. A novel SNP identified at position 108 in a known COUP (chicken ovalbumin upstream promoter)/AP1 transcription factor binding site was significantly correlated with binding phenotypes that are potentially the underlying cause of the associated clinical outcome (increase in viral load and decrease in CD4⁺ T-cell count).

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.

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.

Inosine triphosphatase allele frequency and association with ribavirin-induced anaemia in Brazilian patients receiving antiviral therapy for chronic hepatitis C

Inosine triphosphatase (ITPA) single nucleotide polymorphisms (SNPs) are strongly associated with protection against ribavirin (RBV)-induced anaemia in European, American and Asian patients; however, there is a paucity of data for Brazilian patients. The aim of this study was to evaluate the ITPA SNP (rs7270101/rs1127354) frequency in healthy and hepatitis C virus (HCV)-infected patients from Brazil and the association with the development of severe anaemia during antiviral therapy. ITPA SNPs were determined in 200 HCV infected patients and 100 healthy individuals by sequencing. Biochemical parameters and haemoglobin (Hb) levels were analysed in 97 patients who underwent antiviral therapy. A combination of AArs7270101+CCrs1127354 (100% ITPase activity) was observed in 236/300 individuals. Anaemia was observed in 87.5% and 86.2% of treated patients with AA (rs7270101) and CC genotypes (rs1127354), respectively. Men with AA (rs7270101) showed a considerable reduction in Hb at week 12 compared to those with AC/CC (p = 0.1475). In women, there was no influence of genotype (p = 0.5295). For rs1127354, men with the CC genotype also showed a sudden reduction in Hb compared to those with AC. Allelic distribution of rs7270101 and rs1127354 shows high rates of the genotypes AA and CC, respectively, suggesting that the study population had a great propensity for developing RBV-induced anaemia. A progressive Hb reduction during treatment was observed; however, this reduction was greater in men at week 12 than in women.

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.

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.

SLC29A1 polymorphism and prediction of anaemia severity in patients with chronic hepatitis C receiving triple therapy with telaprevir

OBJECTIVES

The equilibrative nucleoside transporter 1 (ENT1) is the main protein involved in ribavirin cellular uptake. Polymorphisms at the SLC29A1 gene, encoding ENT1, may influence ribavirin-associated anaemia, which is observed at a higher incidence with telaprevir in combination with pegylated-IFNα and ribavirin than with pegylated-IFNα and ribavirin alone. In this study, we investigated the role of the rs760370 SLC29A1 variant in ribavirin-induced anaemia in chronic hepatitis C patients treated with telaprevir-based triple therapy.

METHODS

Forty patients infected with hepatitis C virus (HCV) genotype 1 and starting anti-HCV therapy with telaprevir in combination with pegylated-IFN/ribavirin were prospectively evaluated for SNPs at the SLC29A1 gene and inosine triphosphatase (ITPA) genes using a real-time PCR system.

RESULTS

40% of patients developed severe anaemia with a haemoglobin (Hb) decline ≥ 5 g/dL from the pretreatment value. The SLC29A1 rs760370 GG genotype was associated with the severity of Hb decrease as expressed by the median (IQR) Hb nadir change from baseline [-5.4 (-5.6; -5.0) g/dL in GG versus -4.2 (-5.1; -3.4) in AA/AG genotype; P=0.05] and by the Hb decrease ≥ 5 g/dL by week 12 (77.8% of GG carriers versus 24% of AA/AG; P<0.01). In multivariate analysis, older age (P=0.03), lower baseline Hb concentration (P=0.02) and SLC29A1 rs760370 GG (P=0.02) were associated with the development of severe anaemia during treatment, whereas no association was found with ITPA SNPs in our population receiving telaprevir-based therapy.

CONCLUSIONS

In patients with chronic hepatitis C receiving telaprevir-based therapy, SNP rs760370A>G at the SLC29A1 gene influences the severity of ribavirin-induced anaemia, possibly mirroring the erythrocyte uptake of ribavirin.

Hepatitis C virus in the new era: Perspectives in epidemiology, prevention, diagnostics and predictors of response to therapy

Despite the great successes achieved in the fields of virology and diagnostics, several difficulties affect improvements in hepatitis C virus (HCV) infection control and eradication in the new era. New HCV infections still occur, especially in some of the poorest regions of the world, where HCV is endemic and long-term sequelae have a growing economic and health burden. An HCV vaccine is still no available, despite years of researches and discoveries about the natural history of infection and host-virus interactions: several HCV vaccine candidates have been developed in the last years, targeting different HCV antigens or using alternative delivery systems, but viral variability and adaption ability constitute major challenges for vaccine development. Many new antiviral drugs for HCV therapy are in preclinical or early clinical development, but different limitations affect treatment validity. Treatment predictors are important tools, as they provide some guidance for the management of therapy in patients with chronic HCV infection: in particular, the role of host genomics in HCV infection outcomes in the new era of direct-acting antivirals may evolve for new therapeutic targets, representing a chance for modulated and personalized treatment management, when also very potent therapies will be available. In the present review we discuss the most recent data about HCV epidemiology, the new perspectives for the prevention of HCV infection and the most recent evidence regarding HCV diagnosis, therapy and predictors of response to it.

Quantitative genetics in the study of virus-induced disease

While the role of viral variants has long been known to play a key role in causing variation in disease severity, it is also clear that host genetic variation plays a critical role in determining virus-induced disease responses. However, a variety of factors, including confounding environmental variables, rare genetic variants requiring extremely large cohorts, the temporal dynamics of infections, and ethical limitation on human studies, have made the identification and dissection of variant host genes and pathways difficult within human populations. This difficulty has led to the development of a variety of experimental approaches used to identify host genetic contributions to disease responses. In this chapter, we describe the history of genetic associations within the human population, the development of experimentally tractable systems, and the insights these specific approaches provide. We conclude with a discussion of recent advances that allow for the investigation of the role of complex genetic networks that underlie host responses to infection, with the goal of drawing connections to human infections. In particular, we highlight the need for robust animal models with which to directly control and assess the role of host genetics on viral infection outcomes.

Cytopenias during treatment of HIV-HCV-coinfection with pegylated interferon and ribavirin: safety analysis of the OPERA study

BACKGROUND

Until recently, recommendations for HCV treatment in HIV-coinfected patients have been combination therapy with pegylated interferon (PEG-IFN) and ribavirin (RBV). However, this treatment is often accompanied with cytopenias which lead to drug-dose reduction/discontinuation, therefore influencing sustained virological response (SVR). This study aimed at evaluating incidence and predictors of cytopenias and to define their impact on SVR in Italian HIV-HCV-coinfected patients undergoing PEG-IFN/RBV treatment.

METHODS

OPERA was a multicentric, observational study conducted in 98 Italian centres. Patients with HIV-HCV coinfection were administered with PEG-IFN/RBV combination treatment for 48 weeks. Incidence and time of onset of cytopenias and multiple bone marrow toxicity (mBMT) was monitored. Logistic regression analysis assessed factors associated with SVR, anaemia, neutropenia, thrombocytopenia and mBMT.

RESULTS

Between 2005 and 2011, 1,523 patients were enrolled. Anaemia (haemoglobin <10 g/dl) occurred in 197 (12.9%) patients and a haemoglobin drop ≥3 g/dl was recorded in 796 (52.3%). Anaemia did not impact on SVR, its rate being 42.1% and 38.1%, respectively, in patients with and without anaemia (P=0.31). Therapy discontinuation due to anaemia occurred in 47 patients (3.1%). Neutropenia (<1,000 neutrophils/mm(3)) occurred in 652 (42.8%) patients, and SVR was higher (P<0.001) for patients with neutropenia (44.8%) compared to without neutropenia (34%). Patients developing neutropenia did not have an increased risk of developing infections. Thrombocytopenia (<100,000 platelets/mm(3)) occurred in 595 (39.1%) patients, SVR was not influenced by it (38.2% versus 38.9% in patients with and without thrombocytopenia, respectively; P=0.79), and 16 patients (1.1%) discontinued therapy due to it. Cirrhosis was found in 148/734 evaluated patients (20.2%) and was significantly associated with thrombocytopenia (P<0.0001). mBMT was found in 417 patients (27.4%).

CONCLUSIONS

Cytopenias are frequent side effects of PEG-IFN/RBV combination therapy in HIV-HCV-coinfected patients. However, SVR is not negatively affected by their presence, nor is there an increased risk of infections in patients developing neutropenia. Several predicting factors for the onset of cytopenias have been unravelled, which will help to identify early those patients at high risk of developing cytopenia.

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.

The association of cytopenias and weight loss with hepatitis C virus virologic response in HIV/HCV-coinfected patients treated with PEG-IFN and RBV

BACKGROUND

Pegylated interferon (PEG-IFN)/ribavirin (RBV)-related cytopenias have been associated with improved virological outcomes among hepatitis C virus (HCV)-monoinfected patients. This analysis evaluated PEG-IFN/RBV-related cytopenias with virological responses among HIV/HCV-coinfected patients.

METHODS

Pooled data from PARADIGM and AIDS Pegasys Ribavirin International CO-infection Trial (APRICOT) trials of HIV/HCV-infected patients treated with PEG-IFN/RBV. Virologic response was categorized as HCV RNA detectable (end of treatment nonresponders [ET-NR]) or nondetectable (end of treatment responders [ETR]). Declines in hemoglobin (Hgb), platelets, neutrophils, lymphocytes, and weight between the groups were compared via analysis of covariance and Cochran-Mantel-Haenszel test.

RESULTS

A total of 474 patients, 291 ET-NR and 183 ETR (67 relapsers, 116 with sustained virologic response), 81% male, 52% Caucasian, 88% noncirrhotic, and 67% nondetectable HIV. The ETR experienced greater Hgb declines (≥3.0 g/dL) from baseline (73.8% versus 55.0%; P < .0001), neutrophils ≤1 and ≤ 0.5 × 10(9)/L (66.1% versus 56.4%; P = .0334 and 42.6% versus 33.3%; P = .0312, respectively), and lymphocytes ≤1.5 and ≤0.5 × 10(9)/L (99.5% versus 87.6%; P < .0001 and 24.6% versus 14.9%; P =.0079, respectively).

CONCLUSIONS

The HIV/HCV-coinfected patients with ETR experienced greater declines in Hgb, neutrophils, and lymphocytes than the ET-NR patients.

Anemia management in patients with chronic viral hepatitis C

OBJECTIVE

To review the literature regarding current strategies for the management of anemia associated with treatment for chronic viral hepatitis C (HCV) in adults.

DATA SOURCES

The MEDLINE/PubMed, EMBASE, and Cochrane databases were searched (January 1980-October 2012) for articles in English using the search terms anemia, ribavirin, dose reduction, erythropoietin stimulating agents, hepatitis C, HIV, liver transplant, telaprevir, and boceprevir.

STUDY SELECTION AND DATA EXTRACTION

All relevant original studies, meta-analyses, systematic reviews, guidelines, and review articles were assessed for inclusion. References from pertinent articles were examined for additional content not found during the initial search.

DATA SYNTHESIS

Standard of care for patients infected with HCV genotype 1 now requires a triple therapy regimen including an HCV NS3 protease inhibitor. These regimens lead to significantly higher rates of anemia compared to prior dual therapy regimens. Development of an optimal management strategy should begin with risk stratification. Ribavirin dose reductions have been recommended in the package inserts for the pegylated interferon products and studies have demonstrated the need for maintenance of 80% of the initial ribavirin dose to achieve optimal sustained virologic response (SVR) with dual therapy. The use of erythropoietin-stimulating agents has been shown to be effective for anemia caused by peginterferon and ribavirin without compromising SVR rates. Limited data have been published regarding the management of anemia with triple therapy; however, efficacy studies for boceprevir and telaprevir have used ribavirin dose reduction and erythropoietin-stimulating agents to successfully manage anemia.

CONCLUSIONS

Anemia is a common adverse event associated with the use of ribavirin, and, more recently, the new HCV protease inhibitors. Ribavirin dose reduction should continue to be used as an initial anemia management strategy, with the use of erythropoietin alfa 40,000 units once weekly reserved for patients whose hemoglobin does not adequately respond to initial management strategies.

Management of hepatitis C virus infection: the basics

Chronic hepatitis C virus (HCV) infection affects some 170 million people worldwide, including 3 to 4 million in the United States who are largely unaware of their infection status. HCV has 6 genotypes; genotype 1 is the most common in the United States and genotypes 1 and 4 are less responsive to interferon alfa-based therapy than the other genotypes. Treatment with available direct-acting antiviral (DAA) drugs has increased sustained virologic response (SVR) rates in genotype 1 infection and shortened duration of therapy in many patients, but at this time these agents must still be administered with peginterferon alfa and ribavirin to prevent rapid emergence of resistance. Baseline predictors of response to therapy continue to play a role with triple-drug combination therapy including the pharmacogenetic IL28B genotype, which differs in prevalence throughout the world. The stopping/futility rules are different for triple-drug combination therapy, allowing for earlier decision-making. Ultimately, SVR is the goal of HCV treatment because it dramatically reduces likelihood of poor long-term outcome, even among patients with histologically advanced disease. This article summarizes a basic review presented by Susanna Naggie, MD, at the IAS-USA live management of HCV continuing medical education program held in Atlanta in October 2012. This article is intended for practitioners who are new to HCV management or who are interested in reviewing the basics of HCV treatments.

Anemia management in the era of triple combination therapy for chronic HCV

Boceprevir or telaprevir plus ribavirin (RBV) and pegylated interferon-α (pegIFN-α) is the new standard-of-care therapy for patients who are chronically infected with genotype 1 hepatitis C virus (HCV). The addition of these protease inhibitors to the RBV/pegIFN-α combination regimen has significantly improved rates of sustained virologic response (SVR); however, the incidence of anemia has also increased significantly. Anemia can interfere with patients' quality of life, work productivity, and treatment adherence. Severe anemia can cause morbidity and even mortality. For the management of anemia during triple combination therapy, RBV dose reduction is recommended as an initial course of action. Retrospective analyses of carefully selected patient cohorts suggest that RBV dose reduction does not reduce SVR rates. However, this observation needs to be confirmed in prospective trials with cohorts that more accurately reflect the challenging patients treated in real-world practice. Adequate doses of RBV should be maintained during triple combination therapy, as phase II trials have demonstrated that RBV is essential for attaining optimal SVR rates and preventing viral breakthrough, relapse, and emergence of resistant variants. This roundtable addresses key points related to the management of anemia in the era of triple combination therapy, including the increasing problem of anemia, strategies for anemia management, and the importance of maintaining adequate RBV exposure as part of the HCV treatment regimen.

Association of ITPA gene polymorphisms and the risk of ribavirin-induced anemia in HIV/hepatitis C virus (HCV)-coinfected patients receiving HCV combination therapy

Polymorphisms of the ITPA gene have been associated with anemia during combination therapy in hepatitis C virus (HCV)-monoinfected patients. Our aim was to confirm this association in HIV/HCV-coinfected patients. In this prospective, observational study, 73 HIV/HCV-coinfected patients treated with pegylated interferon plus ribavirin (RBV) were enrolled. Two single nucleotide polymorphisms within or adjacent to the ITPA gene (rs1127354 and rs7270101) were genotyped. The associations between the ITPA genotype and anemia or treatment outcome were examined. Fifty-nine patients (80.8%) had CC at rs1127354, whereas 14 (19.2%) had a CA/AA ITPA genotype. Percent decreases from baseline hemoglobin level were significantly greater in patients with the CC genotype than in those with the CA/AA genotype at week 4 (P = 0.0003), week 12 (P < 0.0001), and week 36 (P = 0.0102) but not at the end of treatment. RBV dose reduction was more often needed in patients with the CC genotype than in those with the CA/AA genotype (odds ratio [OR] = 11.81; 95% confidence interval [CI] = 1.45 to 256.17; P = 0.0039), as was erythropoietin therapy (OR = 8.28; 95% CI = 1.04 to 371.12; P = 0.0057). Risk factors independently associated with percent hemoglobin nadir decrease were RBV dose reduction (OR = 11.72; 95% CI = 6.82 to 16.63; P < 0.001), baseline hemoglobin (OR = 1.69; 95% CI = 0.23 to 3.15; P = 0.024), and body mass index (OR = -0.7; 95% CI = -1.43 to 0.03; P = 0.061). ITPA polymorphism was not an independent predictor of sustained virological response. Polymorphisms at rs1127354 in the ITPA gene influence hemoglobin levels during combination HCV therapy and the need for RBV dose reduction and erythropoietin use in HIV/HCV-coinfected patients.