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Summary

  1. Top of page
  2. Summary
  3. Introduction
  4. Patients and methods
  5. Results
  6. Discussion
  7. Authorship
  8. Acknowledgments
  9. References
  10. Supporting Information

Background

A novel dinucleotide variant TT/∆G (ss469415590) has been associated with hepatitis C virus clearance.

Aim

To assess the role of the ss469415590 variant, compared with the known IL28B polymorphisms (rs8099917, rs12979860 and rs12980275) for predicting virological response to therapy in chronic hepatitis C, and its association with the CXCL10 chemokine serum levels – a surrogate marker of interferon-stimulated genes activation.

Methods

Multivariate analysis of factors predicting rapid and sustained virological response in 280 consecutive, treatment-naïve, nondiabetic, Caucasian patients with chronic hepatitis C treated with peginterferon alpha and ribavirin.

Results

In hepatitis C virus genotype 1, the OR (95% CI) for rapid and sustained virological response for the wild-type ss469415590 TT was 9.88 (1.99–48.99) and 7.25 (1.91–27.51), respectively, similar to those found for rs12979860 CC [9.55 (1.93–47.37) and 6.30 (1.71–23.13)] and for rs12980275 AA [9.62 (1.94–47.77] and 7.83 (2.02–30.34)], but higher than for rs8099917 TT [4.8 (1.73–13.33) and 4.75 (2.05–10.98)]. In hepatitis C virus genotype 1, mean (SD) CXCL10 levels in patients with the TT/TT, TT/∆G and ∆G/∆G variants were, respectively, 355.1 (240.6), 434.4 (247.4) and 569.9 (333.3) (P = 0.04). In patients with genotypes 2 and 3 no significant association was found for TT/∆G with viral response. The predictive value of ss469415590 was stronger in patients with advanced fibrosis.

Conclusions

The novel IL28B variants at marker ss469415590 predict response to IFN alpha in chronic hepatitis C patients, especially in those with advanced fibrosis. Their determination may be superior to that of known IL28B variants for patient management using IFN-based regimens.


Introduction

  1. Top of page
  2. Summary
  3. Introduction
  4. Patients and methods
  5. Results
  6. Discussion
  7. Authorship
  8. Acknowledgments
  9. References
  10. Supporting Information

The hepatitis C virus (HCV) is an RNA virus belonging to the Flaviviridae family, and a major human pathogen, accounting for about one-third of all cases of chronic viral hepatitis globally.[1] Currently licensed therapy consists of pegylated interferon alpha (pegIFNα) and ribavirin, plus one of the two currently licensed protease inhibitors (telaprevir and boceprevir) in patients infected with HCV genotype 1.[2] Overall, cure – defined as undetectable HCV RNA in serum 24 weeks after the end of treatment, or sustained virological response (SVR) – is achieved in approximately 70% of cases.

Despite steadily enhancing therapeutic efficacy over the years, due to novel drug formulations and improved scheduling, optimal effectiveness remains to be defined, owing to drug toxicity, contraindications, costs, etc. Thus, patients’ profiling has emerged as an important tool enabling clinicians to optimise treatment allocation or deferral, until more effective and better-tolerated drugs become available. A wealth of baseline variables (e.g. stage of liver disease, HCV RNA load and genotype, sex and age) and on-treatment responses (such as HCV RNA decline during the first weeks of therapy) are used to optimise drug dosing and duration. A few years ago, four groups independently reported the identification of host single-nucleotide polymorphisms (SNPs) near IL28B, the gene encoding for interleukin-28B (now referred to as IFNL3), capable of increasing the accuracy in predicting SVR, especially in patients infected with HCV genotype 1.[3] Unexpectedly, data suggest that IL28B variants may still influence the rate of response to some IFN-α-free regimens comprising only direct-acting anti-virals (DAA), especially protease inhibitors and in patients infected with genotype 1a.[4-6]

Although the IL28B variant associated with good virological response is strongly associated with lower level of intrahepatic interferon-stimulated gene (ISG) expression,[7] this evidence remains correlative at best, and the mechanistic link between host genetic variation near IL28B and virological response to IFN-α-based therapy is elusive. Recently, we[8] and others[9] have identified a novel dinucleotide variant TT/∆G (ss469415590) near IL28B associated with HCV clearance. Although in strong linkage disequilibrium with IL28B variants at marker rs12979860, at least in patients of Caucasian ancestry, this variant seems to possess functional significance by modulating IL28B expression at least in poly(I:C)-stimulated peripheral blood mononuclear cells.[8] In fact, the rs469415590[∆G] frameshift variant leads to the transient mRNA expression of a putative novel gene named IFNL4, associated with poor clearance of HCV,[9] although solid evidence on its expression in human tissue is currently lacking. On the contrary, the TT variant does not produce IFNL4 mRNA. Thus, the TT/ΔG is the only functional variant in the IL28B locus identified so far, and may be of the utmost interest to identify the mechanisms underlying the response of HCV to anti-virals.

We aimed to assess the role of the novel ss469415590 variant, compared with the rs8099917, rs12979860 and rs12980275 genotypes, for predicting the rapid and sustained response to IFN-α-based treatment in a cohort of treatment-naïve, nondiabetic, Caucasian patients with chronic hepatitis C from Italy. In addition, we evaluated the association between the different ss469415590 variants and the serum levels of the CXC chemokine IFN-gamma inducible protein 10 kDa (IP-10, or CXCL10), a surrogate marker of ISG activation and predictor of SVR in IFN-α-based regimens.[10]

Patients and methods

  1. Top of page
  2. Summary
  3. Introduction
  4. Patients and methods
  5. Results
  6. Discussion
  7. Authorship
  8. Acknowledgments
  9. References
  10. Supporting Information

Patient population

The study population included 280 treatment-naïve hepatitis C patients who were part of a multicenter observational prospective cohort study, the Italian Hepatitis C Cohort Study (ITAHECS), which aimed to evaluate the factors that influence response to anti-viral therapy. The study methods and results concerning the influence of some IL28B variants to patients’ response to anti-HCV therapy have been already published.[11] Briefly, eligibility criteria for therapy included Caucasian ancestry, age between 18 and 65 years, detectable HCV RNA in serum by polymerase chain reaction (PCR) and alanine aminotransferase (ALT) above the upper limit of normal within 6 months of treatment initiation. In addition, 177 patients had a liver biopsy performed within 6 months preceding the start of anti-viral therapy. Liver necroinflammation and fibrosis were scored according to the METAVIR score.[12] Exclusion criteria were decompensated cirrhosis, the presence of concomitant liver disease of aetiology other than HCV, including anti-HIV or hepatitis B surface antigen positivity and high alcohol intake (>40 g/day), and of any contraindication to therapy with the combination of pegylated interferon (IFN)-α and ribavirin. The average daily alcohol intake in the last 6 months was assessed by interviews extended to family members and general practitioners. All patients were asked to abstain from alcohol during anti-viral treatment.

The study was conducted according to the principles of the Helsinki declaration, approved by all local ethical committees and all patients gave informed consent at enrolment.

Assays

HCV genotyping was performed by INNO-LiPA HCV II assay (Innogenetics, Zwijndrecht, Belgium). A quantitative PCR assay (Cobas Amplicor HCV Monitor Test, v 2.0; Roche, Basel, Switzerland) was performed to detect serum HCV RNA at baseline and at Week 12 of therapy. Qualitative HCV RNA assessment was performed at Weeks 4, 12, 24, 48 during treatment and 24 weeks after stopping therapy using Cobas Amplicor HCV, v2.0 (Roche; limit of detection: 50 IU/mL). High baseline viral load was defined as HCV RNA levels >400 000 IU/mL. Quantification of CXCL10 was performed using Quantikine (R&D Systems, Minneapolis, MN, USA), a solid-phase ELISA, on pre-treatment samples stored at −20°C until assayed.

Anti-viral therapy and outcome

Therapy was based on the combination of pegylated IFN-α2a (180 μg/week) or pegylated IFN-a2b (1.5 μg/kg/week) plus ribavirin (800–1200 mg/day) for 48 weeks in HCV genotype 1 or 4 patients, and for 24 weeks in HCV genotype 2 or 3 patients.

The definition of rapid virological response (RVR), sustained virological response (SVR), relapsers and nonresponders were made according to the American Association for the Study of Liver Disease guidelines.[13] Thus, patients who had a <2 log10 drop in viral load at Week 12 as compared with baseline, those who had detectable HCV RNA at Week 24 of therapy and those who had undetectable serum HCV RNA at the end of therapy, but detectable HCV RNA at 24 weeks after cessation of therapy were considered nonresponders.

IL28B genotyping

Genotyping of IL28B variants was conducted in a blinded fashion relative to baseline characteristics and treatment outcome of patients. DNA samples from patients were genotyped for the IL28B rs8099917, rs12979860 rs12980275 and ss469415590 polymorphisms with TaqMan SNP genotyping assays (Applied Biosystems Inc., Foster City, CA, USA), using the ABI 7500 Fast real-time thermocycler, according to manufacturers’ recommended protocols. TaqMan probes and primers were designed and synthesised using Applied Biosystems Inc. software. Automated allele calling was performed using SDS software from Applied Biosystems Inc. Positive and negative controls were used in each genotyping assay. Primers and probes were reported previously.[8, 14]

The IL28B rs8099917 allele T, rs12979860 allele C, rs12980275 allele A and ss469415590 alleles TT were defined as wild-type alleles, whereas the G, T, G and ΔG as mutant alleles respectively.

Statistical analysis

Subjects with HCV genotypes 2 and 3 were considered together as they had similar response rates to the anti-viral treatment. The associations of the new IL28B ss469415590 genotypes, and of the rs8099917, rs12979860 and rs12980275 genotypes, with both RVR and SVR were assessed by the commonly used statistical methods for the analysis of proportions for both HCV genotype 1 and HCV genotypes 2/3 separately. Subsequently, multivariate logistic regression was performed to evaluate the association of the new IL28B variant and the other genotypes with RVR and SVR, adjusting for demographical and clinical variables. A stepwise backward procedure was used for selecting the final logistic regression model. The associations of IL28B polymorphisms with RVR and SVR were evaluated comparing separately patients with homozygous wild-type and those with heterozygous genotypes with patients with homozygous mutant genotypes. Heterozygous and homozygous mutant genotypes were analysed together in the case of rs8099917 polymorphism because there were no patients who were homozygote for the allele G and had RVR. The predictive accuracy of RVR and SVR by the logistic regression models including the different IL28B genotypes was assessed by comparing the areas under the corresponding receiver operating characteristic (ROC) curves, using the methods commonly suggested.[15] Discrimination abilities between the new polymorphism ss469415590 and the other IL28B variants were compared using the integrated discrimination improvement (IDI) test.[16] Two-sided P values <0.05 were considered statistically significant. All the analyses were performed using the Stata package version 12.0 (Stata Corporation, College Station, TX, USA).

Results

  1. Top of page
  2. Summary
  3. Introduction
  4. Patients and methods
  5. Results
  6. Discussion
  7. Authorship
  8. Acknowledgments
  9. References
  10. Supporting Information

Baseline feature of the study populations

A total of 280 consecutive treatment-naïve patients with HCV chronic hepatitis were included. Their mean (SD) age was 46 (11) years and 59% of them were males. HCV genotypes 1, 2 and 3 were found in 121, 104 and 55 patients respectively. The baseline demographic and clinical characteristics of the patients are shown in Table S1.

The frequency of rs8099917, rs12979860, rs12980275 and ss469415590 genotypes in the study population according to HCV genotypes is shown in Table 1. No significant differences in the distribution of IL28B genotypes by HCV genotype were found. A strong linkage disequilibrium was observed of ss469415590 with rs12979860 (r2 = 0.98) and with rs12980275 (r2 = 0.95). A lower association was found between ss469415590 and rs8099917 (r2 = 0.70). In the 121 subjects with HCV genotype 1, only one and two patients showed discordant genotype distributions between ss469415590 and rs12979860 and between ss469415590 and rs12980275 respectively. In the remaining patients with HCV genotype 2 or 3 infection, those with discordant genotypes between ss469415590 and rs12979860 and between ss469415590 and rs12980275, were four and nine, respectively.

Table 1. Frequency of IL28B genotypes in patients with chronic hepatitis C virus (HCV) infection according to HCV type
IL28B genotypesHCV type 1 (n = 121) N (%)HCV types 2/3 (n = 159) N (%)P value
rs8099917
GG6 (5)9 (6) 
TG50 (41)57 (36) 
TT65 (54)93 (58)0.64
rs12979860
TT19 (15)16 (10) 
CT60 (50)76 (48) 
CC42 (35)67 (42)0.25
rs12980275
GG18 (15)17 (11) 
AG61 (50)75 (47) 
AA42 (35)67 (42)0.35
ss469415590
ΔG/ΔG19 (16)15 (10) 
TT/ΔG60 (50)80 (50) 
TT41 (34)64 (40)0.23

ss469415590 variants and baseline HCV RNA

No significant association was observed between basal HCV RNA and ss469415590 variants. Indeed, the mean (SD) of the log-transformed baseline serum HCV RNA levels according to this IL28B genetic variant was as follows: 5.80 (0.71), 5.70 (0.86) and 5.87 (0.93) log10 IU/mL for ΔG/ΔG, TT/ΔG and TT/TT variants respectively (P = 0.5). Concerning HCV genotypes 2/3, the HCV RNA levels were 5.89 (0.91), 5.67 (0.86) and 5.86 (0.95) log10 IU/mL for the three IL28B variants respectively (P = 0.4) (data not shown).

ss469415590 variants and baseline CXCL10 serum levels

The level of circulating CXCL10 according to HCV genotype and the ss469415590 variants was measured in 226 of 280 patients, namely, in 92 (76%) of 121 genotype 1, 87 (83%) of 104 genotype 2 and 47 (85%) of 55 genotype 3 patients. In patients with HCV genotype 1, mean serum CXCL10 levels (SD) in patients with the TT/TT, TT/∆G and ∆G/∆G variants were, respectively, 355.1 (240.6), 434.4 (247.4) and 569.9 (333.3) (P = 0.04). In patients with HCV genotypes 2 and 3, pooled together, mean serum CXCL10 levels (SD) in patients with the TT/TT, TT/∆G and ∆G/∆G variants were, respectively, 351.9 (387.7), 302.6 (239.3) and 342.7 (332.8) (P = 0.7).

IL28B variants and virological response

RVR was achieved in 172/280 (61%) patients, including 33 (27%) with HCV genotype 1 and 139 (87%) with genotypes 2/3. SVR was achieved in 209/280 (75%) patients, that is 65 (53%) and 144 (91%) of patients infected with HCV genotypes 1 or 2/3 respectively. The RVR and SVR rates for IL28B genotypes in patients with HCV genotype 1 are shown in Table 2.

Table 2. Association of IL28B genotypes with rapid virological response (RVR) and sustained virological response (SVR) in patients with chronic hepatitis C type 1 using multiple logistic regression including age and HCV RNA viral load as covariates
IL28B polymorphismsRVR (n = 33)P valueSVR (n = 65)P value
Response rate (%)OR (95% CI)Response rate (%)OR (95% CI)
  1. The logistic regression models included age and HCV RNA serum level, dichotomised as less than vs. equal to or greater than 400 000 IU/mL. OR, odds ratio.

rs8099917
GG+TG16Reference 69Reference 
TT384.8 (1.73–13.33)0.003694.75 (2.05–10.98)<0.001
rs12980275
GG17Reference 44Reference 
AG110.78 (0.16–3.86)0.78340.63 (0.19–2.03)0.44
AA559.62 (1.94–47.77)0.006867.83 (2.02–30.34)0.003
rs12979860
TT16Reference 47Reference 
CT130.92 (0.19–4.45)0.91350.58 (0.18–1.83)0.36
CC529.55 (1.93–47.37)0.006836.30 (1.71–23.13)0.006
ss469415590
ΔG/ΔG16Reference 47Reference 
TT/ΔG130.92 (0.19–4.44)0.92350.58 (0.19–1.83)0.36
TT/TT549.88 (1.99–48.99)0.005857.25 (1.91–27.51)0.004

In patients with HCV genotype 1, statistically significant higher response rates were found for subjects with IL28B homozygous wild-type genotypes (TT for rs8099917, CC for rs12979860, AA for rs12980275 and TT/TT for ss469415590 genotypes) with respect to those with homozygous mutant or heterozygous genotypes, for both RVR and SVR (Table 2). There were three subjects with discordant IL28B genotype combinations: one with ss469415590 TT/ΔG and rs12979860 CC failed to reach RVR and SVR; a second patient with ss469415590 TT/ΔG and rs12980275 AA achieved both RVR and SVR and the third patient with ss469415590 ΔG/ΔG and rs12980275 AG failed to reach RVR but achieved SVR.

Then, we assessed the SVR rates in patients with HCV genotype 1 divided according to IL28B alleles and fibrosis stage (Table S2). Patients were stratified into four groups, according to the stage of fibrosis [absent/moderate fibrosis (Metavir F0–F2) vs. advanced fibrosis (F3–F4)] and the IL28B risk alleles rs8099917 G, rs12979860 T, rs12980275 G and ss469415590 ΔG (carriers vs noncarriers). The risk of treatment failure increased in patients with advanced fibrosis and presence of the risk allele: rs8099917 G allele (OR = 31; 95% CI: 4–241), rs12979860 T allele (OR = 42.1; 95% CI: 6.4–277.1), rs12980275 G allele (OR = 49.9; 95% CI: 7.3–340.7) and ss469415590 ΔG allele (OR = 51.5; 95% CI: 7.4–356.3).

Subsequently, each IL28B polymorphism was included in a multivariate analysis, together with demographic and clinical variables in patients with HCV genotype 1. Using a stepwise backward procedure, we selected a final logistic regression model including only the baseline HCV RNA serum level dichotomised at 400 000 IU/mL, age dichotomised at 40 years and the IL28B variants as independent predictors of SVR and RVR. The OR for each IL28B variant is shown in Table 2. For the new ss469415590 TT variant we found an OR of 9.88 for RVR and 7.25 for SVR, which were similar to those found for rs12979860 and rs12980275, whereas lower associations were found for rs8099917.

No statistically significant association of IL28B genotypes with either RVR or SVR was found in patients with HCV genotypes 2/3 (Table S3). There was no association between the fibrosis stage and host polymorphism with the response to therapy among patients with HCV genotype 2/3 (Table S4).

When the IL28B polymorphisms were tested using a stepwise backward procedure all together, the rs12980275 polymorphism demonstrated the strongest association with both RVR and SVR, whereas all the others were excluded due to high collinearity among them. When only ss469415590 and rs12979860 were included in the model, the coefficient estimates were extremely imprecise due to high collinearity between them. The ROC analysis for RVR showed a lower area under the curve for rs8099917 (AUC = 0.65) with respect to the other genotypes (AUC = 0.73 for ss469415590, AUC = 0.73 for rs12979860 and AUC = 0.75 for rs12980275), though no significant difference was found among them; similarly, the analysis for SVR provided the following results: AUC = 0.67 for rs8099917, AUC = 0.72 for rs12979860, AUC = 0.73 for ss469415590 and AUC = 0.74 for rs12980275.

When IDI test was performed, ss469415590, rs12979860 and rs12980275 polymorphisms showed a better ability than rs8099917 to discriminate both RVR and SVR rates (P < 0.05).

No statistically significant improvement in the prediction of RVR and SVR was found when compared ss469415590 with rs12979860 and rs12980275 polymorphisms.

Discussion

  1. Top of page
  2. Summary
  3. Introduction
  4. Patients and methods
  5. Results
  6. Discussion
  7. Authorship
  8. Acknowledgments
  9. References
  10. Supporting Information

In this study we aimed to evaluate the role of the novel ss469415590 polymorphism in proximity to IL28B in patients infected with HCV in a Southern Europe population. The main finding of this study is that the new polymorphism has a similar performance as the previously investigated rs12979860 and rs12980275, and better than rs8099917, for predicting RVR and SVR in patients with HCV genotype 1. This finding is not unexpected due to the strong linkage disequilibrium among the former two SNPs in Caucasian populations, confirming some recent findings.[8, 9] Moreover, it was reported recently that ss469415590 variant is a better predictor than rs12979860 of response to IFN-based therapy in HCV genotype 1[17] and HCV/HIV-1 coinfected[18] patients. No association between the new variant and the virological response was observed in our patients with HCV genotypes 2 and 3. In addition, we observed an interesting, significant association between ss469415590 variants and the level of circulating CXCL10, a surrogate marker of ISG activation consistent with the previous report by Lagging et al.,[19] where CCrs12979860 was significantly associated with lower baseline CXCL10 levels among a predominantly HCV genotype 1 infected population. Why this association was not seen among HCV genotype 2 or 3 infected patients remains unclear, but it has previously been noted that the impact of IL28B genotypes on other clinical features (e.g. liver histology) differs across HCV genotypes.[20, 21]

The novel polymorphism ss469415590 has been proposed [9] as a candidate to provide a causal link between IL28B and viral eradication in hepatitis C, possibly solving a puzzle that had befuddled investigators since the identification of the original IL28B SNPs. This was due to the correlative nature of the evidence gathered until recently, and to the perplexing data on IL28B expression vs. genetic polymorphisms. For example, the level of expression of IL28B had been reported to be lower in peripheral blood mononuclear cells from patients with the unfavourable IL28B variants, compared with those carrying the wild-type gene,[22, 23] but this had not been confirmed in liver tissue,[7, 24, 25] where the viral infection takes place. In addition, it has been correctly pointed out how it was difficult to justify a causal role for IL28B in affecting viral clearance, when IL28A has a high level of homology with IL28B and yet no recognised association with the same phenotype,[26] although other explanations are possible. Irrespectively of this incertitude, the region surrounding IL28B is certainly involved in the eradication of HCV, both spontaneous and INF-α induced. It remains unclear whether highlighting the existence and the function of IFNL4 – or loss thereof – will provide the causal mechanism of increased viral clearance, but it is arguably an alluring candidate. First, IFNL4 gene transfection induces ISG upon transient expression in a hepatoma cell line,[9] and indeed a higher ISG expression in hepatocytes, as evaluated by immunohistochemistry, is known to be associated with poor response.[27] On the other hand, by using poly(I:C)-stimulated peripheral blood mononuclear cells from individuals carrying different allelic combinations of TT/ΔG and the previously reported variant rs12979860, it was shown that induction of IL28B and CXCL10 was dependent on ss469415590 but not on rs12979860, and was indeed significantly weaker in patients with the ∆G/∆G variant.[8] Again, this observation is in agreement with the reported association between the cell type–specific ISG expression and therapy outcome.[27] Our present data are compatible with the widely reported data that circulating levels of CXCL10 are higher in patients with poorer response to therapy.[28, 29]

In spite of this, however, a note of caution is mandatory. First, as said above, IFNL4 construct induces ISG only upon transient expression in hepatoma cells,[9] and it remains unclear whether the protein is secreted and/or has a specific and functional receptor. More importantly, the three haplotypes containing ∆G and found in European patients do not carry the same level of risk of therapy failure, as it would be expected if the mutation would tag the causal haplotype.[9, 26] Thus, further validation of these findings from different ethnic groups is necessary before the expression of IFNL4 is accepted as a causal mechanistic link between ss469415590 variants and HCV clearance. It has to be added that ss469415590 may still act by modifying the methylation profile of DNA-specific sites involved in IL28B regulation. Indeed, the TT/∆G polymorphism is located in a CpG island, and the ∆G variant is associated with a cytosine methylation absent in wild-type genomic sequence.[8] This may result in differential binding affinity of hitherto unidentified transcription factors.[8]

The findings for the already investigated IL28B SNPs rs12979860 and rs12980275 are substantially in agreement with two recent meta-analyses, showing an OR for SVR for HCV types 1–4 in Caucasians of 2.52–2.63 for the rs8099917 and of 4.08–7.31 for rs12979860.[30, 31] In addition, as reported before, no association was found between IL28B variants (including at the ss469415590 marker) and viral response in patients infected with HCV genotypes 2 and 3.

An aspect of importance in clinical therapeutic management is the stage of fibrosis. Despite the small size of the sample, it appeared that the IL28B risk alleles are associated with treatment failure especially in patients with HCV genotype 1 and advanced fibrosis (Table S2).

Triple therapy including a DAA (telaprevir or boceprevir) represents a significant advance for the treatment of HCV type 1 patients, but at the expenses of increased adverse effects and high cost. Recent data indicate that in approximately 20% of naïve HCV-1 patients, identified by their interferon responsiveness and some baseline predictors including the CC for rs12979860, dual therapy with pegylated IFN-α and ribavirin is more cost-effective first-line therapy.[32] Current data indicate that determination of IL28B genotype will remain useful in the IFN-free era for several reasons.[33] Although baseline, pre-treatment patient profiling may be less critical to determine how to treat – although the treatment length may be still be dependent on some parameters, such as prior treatment history, HCV genotype and fibrosis staging – nonetheless it will remain important to determine whom to treat. In fact, the baseline workup will include the assessment of features identifying patients at risk of progression if left untreated, and host genetics (including IL28B genotyping) will still contribute. Concerning the predictive value of SVR, genetics will only play a role in interferon (IFN)-based regimens (and possibly a minor role in some protease inhibitor-based regimens). If, on the one hand, IFN-free regimens will be widely used in developed countries, this will not be the case in resource-poor countries, where IFN-α, due to its low cost, will still be widely used as alternative to expensive IFN-free regimens. Thus, determining IL28B variants will remain relevant to dictate the conduct of IFN-based regimens in these resource-poor setting. Finally, the preference accorded to the ss469415590 variant may be justified in patient populations where the linkage disequilibrium is not as strong as in Caucasians and Asians, such as among patients from Africa (and possibly other – and hitherto poorly characterised – ethnical groups).[9]

In conclusion, the novel ss469415590 variant is strongly associated with IFN-α-induced HCV clearance in treatment-naïve, nondiabetic, Caucasian, chronic hepatitis C patients from Italy, especially those with advanced fibrosis. Its predictive value is moderately better with respect to the rs8099917 and similar to rs12979860 and rs12980275 genotypes. Minor variants at the novel marker are also significantly associated with higher circulating levels of CXCL10, in agreement with previous data on the other IL28B variants.[19] Despite the advent of IFN-free regimens, the determination of the novel IL28B variants at marker ss469415590 may be superior to that of known IL28B variants for patient profiling and management, especially in settings where IFN-based regimens will continue being used.

Authorship

  1. Top of page
  2. Summary
  3. Introduction
  4. Patients and methods
  5. Results
  6. Discussion
  7. Authorship
  8. Acknowledgments
  9. References
  10. Supporting Information

Guarantor of the article: Giovanna Fattovich.

Author contributions: Loredana Covolo contributed to study design, collection and interpretation of data, statistical analysis and to the draft of the manuscript. Stephanie Bibert contributed to IL28B genotyping and interpretation of data. Francesco Donato contributed to study design, interpretation of the results, statistical analysis and to the draft of the manuscript. Pierre-Yves Bochud contributed to statistical analysis and interpretation of the results. Marting Lagging contributed to laboratory analysis and interpretation of data. Francesco Negro contributed to study design, interpretation of the results and to the draft of the manuscript. Giovanna Fattovich contributed to the conception, study design, data, interpretation of data and drafted the manuscript. All authors approved the final version of the manuscript.

Acknowledgments

  1. Top of page
  2. Summary
  3. Introduction
  4. Patients and methods
  5. Results
  6. Discussion
  7. Authorship
  8. Acknowledgments
  9. References
  10. Supporting Information

This study could not have been completed without the data and analysis of the Italian Hepatitis C Cohort Study (ITAHECS) group including the following members: Massimo Puoti, Department of infectious Diseases, AO Ospedale Niguarda Ca’ Grande, Milano, Italy; Giovanni Battista Gaeta, Viral Hepatitis Unit, Second University of Naples, Naples, Italy; Teresa Santantonio, Clinic of Infectious Diseases, University of Foggia, Foggia, Italy; Giovanni Raimondo, Department of Internal Medicine, University of Messina, Messina, Italy; Raffaele Bruno, Institute of Infectious and Tropical Diseases, University of Pavia, Pavia, Italy. The authors are grateful to Galia Askarieh, Department of Infectious Diseases, University of Goteborg, Goteborg, Sweden, for the analysis of CXCL10. LC and SB contributed equally to this study, as did GF and FN.

Declaration of personal and funding interests: None.

References

  1. Top of page
  2. Summary
  3. Introduction
  4. Patients and methods
  5. Results
  6. Discussion
  7. Authorship
  8. Acknowledgments
  9. References
  10. Supporting Information

Supporting Information

  1. Top of page
  2. Summary
  3. Introduction
  4. Patients and methods
  5. Results
  6. Discussion
  7. Authorship
  8. Acknowledgments
  9. References
  10. Supporting Information
FilenameFormatSizeDescription
apt12568-sup-0001-TableS1.docWord document45KTable S1. Baseline demographic and clinical characteristics of patients with chronic hepatitis C.
apt12568-sup-0002-TableS2.docWord document51KTable S2. Joint analysis of fibrosis stage and host genetic polymorphisms on-treatment response in HCV genotype 1 patients.
apt12568-sup-0003-TableS3.docWord document51KTable S3. Association of IL28B genotypes with rapid virological response (RVR) and sustained virological response (SVR) in patients with chronic hepatitis C types 2/3 using multiple logistic regression.
apt12568-sup-0004-TableS4.docWord document50KTable S4. Joint analysis of fibrosis stage and host genetic polymorphisms on-treatment response in HCV genotype 2/3 patients.

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