Are viral or host factors predictive of response to interferon–ribavirin in transplant patients with hepatitis C?
Authors: Bruno Roche, Didier Samuel
Journal: Journal of Hepatology (2010)

Mutations in hepatitis C virus genotype 1b and the sensitivity of interferon-ribavirin therapy after liver transplantationJournal of HepatologyVol. 52Issue 5PreviewThe results of post-transplant antiviral therapy for recurrent hepatitis C virus (HCV) are poor, and significant pre-transplant predictors for sustained viral response (SVR) have not yet been identified. Full-Text PDF In Europe and the United States, hepatitis C virus (HCV)-related end-stage liver disease is the main indicator of the need for liver transplantation (LT). Recurrence of hepatitis C in the graft is universal after LT in HCV RNA-positive candidates, leading to lobular or chronic active hepatitis in most patients and to cholestatic hepatitis in a minority of them. Cirrhosis occurs in 20–30% of transplant recipients within 5–10 years of transplantation [[1]Berenguer M. Prieto M. Rayon J.M. Mora J. Pastor M. Ortiz V. et al.Natural history of clinically compensated hepatitis C virus-related graft cirrhosis after liver transplantation.Hepatology. 2000; 32: 852-858Crossref PubMed Scopus (489) Google Scholar] and at least 10% of patients will require re-transplantation for hepatitis C graft failure. Following transplantation, a significant increase in viral load is observed as the HCV follows a more aggressive course in immunocompromised patients when compared to competent patients. As a result, patient and graft survival are lower in HCV-positive recipients than in HCV-negative recipients [[2]Forman L.M. Lewis J.D. Berlin J.A. Feldman H.I. Lucey M.R. The association between hepatitis C infection and survival after orthotopic liver transplantation.Gastroenterology. 2002; 122: 889-896Abstract Full Text Full Text PDF PubMed Scopus (944) Google Scholar]. Antiviral therapy based on pegylated interferon (Peg-IFN) in combination with ribavirin (RBV) is primarily given when there is histological evidence of recurrent HCV disease. However, as in the non-transplant setting, its efficacy is lower in HCV genotype 1 infected patients. The reported sustained virological response (SVR) rate with Peg-IFN and RBV in genotype 1 patients ranges from 12% to 40% (mean 28.7%) and is lower than in non-transplant patients [[3]Berenguer M. Systematic review of the treatment of established recurrent hepatitis C with pegylated interferon in combination with ribavirin.J Hepatol. 2008; 49: 274-287Abstract Full Text Full Text PDF PubMed Scopus (298) Google Scholar]. Factors potentially responsible for the reduced virological response to Peg-IFN and RBV therapy in the setting of LT are: prior non-response to (Peg) IFN and RBV before transplantation, high prevalence of genotype 1, immunosuppression, intolerance, and side effects of IFN or RBV. Tolerability is a major issue, with 70–80% of patients requiring dose reduction and 10–40% requiring drug discontinuation [[3]Berenguer M. Systematic review of the treatment of established recurrent hepatitis C with pegylated interferon in combination with ribavirin.J Hepatol. 2008; 49: 274-287Abstract Full Text Full Text PDF PubMed Scopus (298) Google Scholar]. Most studies show improvements in biochemical and necroinflammatory activity in virological responders. Less consistent improvements in fibrosis scores have been reported, possibly due to the stage of fibrosis at the initiation of therapy, with more advanced stages being less reversible [4Roche B. Sebagh M. Canfora M.L. Antonini T. Roque-Afonso A.M. Delvart V. et al.Hepatitis C virus therapy in liver transplant recipients: response predictors, effect on fibrosis progression, and importance of the initial stage of fibrosis.Liver Transpl. 2008; 14: 1766-1777Crossref PubMed Scopus (131) Google Scholar, 5Carrion J.A. Navasa M. Garcia-Retortillo M. Garcia-Pagan J.C. Crespo G. Bruguera M. et al.Efficacy of antiviral therapy on hepatitis C recurrence after liver transplantation: a randomized controlled study.Gastroenterology. 2007; 132: 1746-1756Abstract Full Text Full Text PDF PubMed Scopus (309) Google Scholar]. A survival benefit was also reported in virological responders [6Veldt B.J. Poterucha J.J. Watt K.D. Wiesner R.H. Hay J.E. Kremers W.K. et al.Impact of pegylated interferon and ribavirin treatment on graft survival in liver transplant patients with recurrent hepatitis C infection.Am J Transplant. 2008; 8: 2426-2433Crossref PubMed Scopus (96) Google Scholar, 7Picciotto F.P. Tritto G. Lanza A.G. Addario L. De Luca M. Di Costanzo G.G. et al.Sustained virological response to antiviral therapy reduces mortality in HCV reinfection after liver transplantation.J Hepatol. 2007; 46: 459-465Abstract Full Text Full Text PDF PubMed Scopus (173) Google Scholar]. Predictive factors associated with SVR are: initial viral kinetics and more specifically viral response assessed at 4 and 12 weeks of therapy, non genotype−1, adherence to therapy, baseline viremia, and baseline fibrosis stage (Table 1) [[3]Berenguer M. Systematic review of the treatment of established recurrent hepatitis C with pegylated interferon in combination with ribavirin.J Hepatol. 2008; 49: 274-287Abstract Full Text Full Text PDF PubMed Scopus (298) Google Scholar].Table 1Predictive factors associated with sustained virologic response to interferon–ribavirin therapy post-transplantation.Host factorsVirologic response at week 4ConfirmedVirologic response at week 12ConfirmedTotal dose and duration of (Peg-)interferon–ribavirinConfirmedImmunosuppressive therapy (cyclosporine vs. tacrolimus)ControversialLow baseline fibrosis stageProbable (Refs. 4Roche B. Sebagh M. Canfora M.L. Antonini T. Roque-Afonso A.M. Delvart V. et al.Hepatitis C virus therapy in liver transplant recipients: response predictors, effect on fibrosis progression, and importance of the initial stage of fibrosis.Liver Transpl. 2008; 14: 1766-1777Crossref PubMed Scopus (131) Google Scholar, 5Carrion J.A. Navasa M. Garcia-Retortillo M. Garcia-Pagan J.C. Crespo G. Bruguera M. et al.Efficacy of antiviral therapy on hepatitis C recurrence after liver transplantation: a randomized controlled study.Gastroenterology. 2007; 132: 1746-1756Abstract Full Text Full Text PDF PubMed Scopus (309) Google Scholar)Low baseline activity scoreNot provenViral factorsGenotype 2 or 3ConfirmedLow baseline HCV viral loadConfirmedHCV genotype 1 mutationsOne study (Ref. [8]Fukuhara T. Taketomi A. Okano S. Ikegami T. Soejima Y. Shirabe K. et al.Mutations in hepatitis C virus genotype 1b and the sensitivity of interferon–ribavirin therapy after liver transplantation.J Hepatol. 2010; 52: 672-680Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar) Open table in a new tab In this issue of the journal, Fukuhara et al. reported for the first time in transplant patients, a role of HCV genotype 1b mutations in sensitivity to Peg-IFN and RBV therapy [[8]Fukuhara T. Taketomi A. Okano S. Ikegami T. Soejima Y. Shirabe K. et al.Mutations in hepatitis C virus genotype 1b and the sensitivity of interferon–ribavirin therapy after liver transplantation.J Hepatol. 2010; 52: 672-680Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar]. The predictive potential of the combined analysis of viral mutations that included amino acid(s) (aa) 70 and 91 in the Core region, the interferon sensitivity-determining region (ISDR, aa 2209–2248), and the interferon/ribavirin resistance determining region (IRRDR, aa 2334–2379) in the NS5A region, was retrospectively evaluated. Fifty genotype 1 patients were treated with increasing doses of Peg-IFN alpha-2b and RBV. Nineteen patients were non-responders to standard IFN therapy before transplantation. Twenty-two (44%), 8 (16%), and 20 (40%) patients demonstrated SVR, relapse, and non-response, respectively. The pre-treatment viral load and low haemoglobin level were significant risks factors for the failure to achieve SVR. Native liver tissues and serum at liver transplantation were available for genetic analysis from 16 and 22 patients, respectively. The sequences of aa 70 and 91 in the Core region, ISDR and IRRDR between liver tissues and serum were the same in the 12 patients in which both liver tissues and serum were available. Post-transplant liver tissues and serum were analyzed in 10 and 6 patients, respectively. The sequences of the Core and NS5A regions in the pre- and post-transplant samples were identical, except for aa 70 in the Core of only one patient. The patients were divided into two groups based on the mutation of aa 70 and 91 in the Core region (DW and non-DW), the number of ISDR mutations (ISDR ⩾2 and ISDR <2) and the number of IRRDR mutations (IRRDR ⩾6 and IRRDR <6). The rate of SVR was significantly lower in the non-double wild at aa 70 and 91, the ISDR <2 and IRRDR <6 groups than in the double wild (30% vs. 65%, p= 0.015), the ISDR ⩾2 (35% vs. 69%, p= 0.035), and IRRDR ⩾6 (25% vs. 78%, p<0.001) groups. A predictive scoring system based on the number of positive factors including the double wild in the Core region, ISDR ⩾2 and IRRDR ⩾6 in the NS5A region could be established before transplantation and allowed the stratification of the sensitivity of antiviral therapy after LT. The rate of SVR in this prediction score was 18%, 38%, 86%, and 100% for the presence of 0, 1, 2, or 3 positive factors, respectively (p<0.001). The results reported in this study are important since no other pre-transplant predictor, for the achievement of SVR after antiviral therapy post-transplant in genotype 1 patients has been reported. A limitation of this study is the absence of a multivariate analysis of the predictive factors of SVR in order to evaluate the importance of viral factors as compared to early viral kinetics and other pre- and on-treatment predictors of response.In the non-transplant setting, some studies from western countries and Japan reported that in patients with chronic HCV genotype 1 infection, there is a strong correlation between response to IFN and mutations in the NS5A protein, particularly in the ISDR and IRRDR regions [9Enomoto N. Sakuma I. Asahina Y. Kurosaki M. Murakami T. Yamamoto C. et al.Mutations in the nonstructural protein 5A gene and response to interferon in patients with chronic hepatitis C virus 1b infection.N Engl J Med. 1996; 334: 77-81Crossref PubMed Scopus (980) Google Scholar, 10Munoz de Rueda P. Casado J. Paton R. Quintero D. Palacios A. Gila A. et al.Mutations in E2-PePHD, NS5A-PKRBD, NS5A-ISDR, and NS5A-V3 of hepatitis C virus genotype 1 and their relationships to pegylated interferon–ribavirin treatment responses.J Virol. 2008; 82: 6644-6653Crossref PubMed Scopus (57) Google Scholar, 11El-Shamy A. Nagano-Fujii M. Sasase N. Imoto S. Kim S.R. Hotta H. Sequence variation in hepatitis C virus nonstructural protein 5A predicts clinical outcome of pegylated interferon/ribavirin combination therapy.Hepatology. 2008; 48: 38-47Crossref PubMed Scopus (120) Google Scholar, 12Shirakawa H. Matsumoto A. Joshita S. Komatsu M. Tanaka N. Umemura T. et al.Pretreatment prediction of virological response to peginterferon plus ribavirin therapy in chronic hepatitis C patients using viral and host factors.Hepatology. 2008; 48: 1753-1760Crossref PubMed Scopus (122) Google Scholar] and at aa 70 and 91 of the Core region [13Akuta N. Suzuki F. Hirakawa M. Kawamura Y. Yatsuji H. Sezaki H. et al.A matched case-controlled study of 48 and 72 weeks of peginterferon plus ribavirin combination therapy in patients infected with HCV genotype 1b in Japan: amino acid substitutions in HCV core region as predictor of sustained virological response.J Med Virol. 2009; 81: 452-458Crossref PubMed Scopus (64) Google Scholar, 14Okanoue T. Itoh Y. Hashimoto H. Yasui K. Minami M. Takehara T. et al.Predictive values of amino acid sequences of the core and NS5A regions in antiviral therapy for hepatitis C: a Japanese multi-center study.J Gastroenterol. 2009; 44: 952-963Crossref PubMed Scopus (77) Google Scholar]. In the study of Shirakawa et al., the multivariate logistic regression analysis for factors associated with SVR showed that mutant ISDR was the strongest predictor (OR = 86.0, 95% CI 6.4–1162.3) as compared to early viral kinetics (OR = 12.0, 95% CI 2.4–60) or total dose of Peg-IFN (OR = 23.1, 95% CI 2.7–194.9) [[12]Shirakawa H. Matsumoto A. Joshita S. Komatsu M. Tanaka N. Umemura T. et al.Pretreatment prediction of virological response to peginterferon plus ribavirin therapy in chronic hepatitis C patients using viral and host factors.Hepatology. 2008; 48: 1753-1760Crossref PubMed Scopus (122) Google Scholar].Few studies have analyzed the effect of virological factors (except genotype) on the outcome of HCV recurrence post-LT. Feliu et al. assessed the early virological response to antiviral therapy in a cohort of 11 patients treated immediately before and after LT and compared HCV sequences from hyper-variable region 1 and NS5A region before both treatments [[15]Feliu A. Carrion J.A. Massaguer A. Martinez-Bauer E. Garcia-Retortillo M. Gonzalez P. et al.Sensitivity to antiviral therapy may change after liver transplantation in patients with chronic hepatitis C virus infection.J Viral Hepat. 2006; 13: 544-551Crossref PubMed Scopus (15) Google Scholar]. Eight patients showed identical early viral kinetics to both courses of therapy and interestingly the type of response changed in 3 patients: 2 non-responders obtained early virological response and an early virological responder became a non-responder. The differences between the sequences of the NS5A region were very few, suggesting that the changes in sensitivity to therapy after LT are not exclusively dependent on variations in HCV strains and might be related to host factors. However, sequence analysis of the NS5A region showed that fixation of mutations in this region occurred preferentially in individuals who became sensitive to IFN after LT. Another study showed that the NS3 and the NS5B regions evolved independently after LT [[16]Massaguer A. Ramirez S. Carrion J.A. Gonzalez P. Sanchez-Tapias J.M. Forns X. Evolution of the NS3 and NS5B regions of the hepatitis C virus during disease recurrence after liver transplantation.Am J Transplant. 2007; 7: 2172-2179Crossref PubMed Scopus (12) Google Scholar]. The genetic evolution of the NS3 domain was not related to the severity of the recurrence. However, the diversification in the NS5B region was greater in patients with mild recurrences than in those with severe recurrences, suggesting that immune pressure was stronger in the former group. In a previous study we found a strong positive correlation between genetic variability in the Core sequences of 53 genotype 1 patients and differences in 5-year fibrosis scores and in viral load [[17]Gigou M. Roque-Afonso A.M. Falissard B. Penin F. Dussaix E. Feray C. Genetic clustering of hepatitis C virus strains and severity of recurrent hepatitis after liver transplantation.J Virol. 2001; 75: 11292-11297Crossref PubMed Scopus (27) Google Scholar]. Following LT, there are major changes in viral and host variables that might influence the response to therapy: (a) the variation in quasi-species composition after LT; (b) the genetic background of the liver graft is singular and the activation of IFN-dependent antiviral pathways may be different in each individual; (c) the immune pressure on HCV is modified by immunosuppression. Taking these factors into consideration, pre-transplant prediction of response to antiviral therapy after LT seems very difficult. As in the non-transplant setting, the decision to treat should take into account all parameters: age, general status, genotype, severity of the hepatitis, rapidity of fibrosis progression, risk of graft loss, and expected tolerance to the treatment. The presence of HCV mutations may represent a new tool that may help in the decision to undertake antiviral therapy post-transplantation but in no way it does it represent a factor limiting the indication of transplantation. This new technique is not fully evaluated and should be assessed in larger studies. A multifactorial approach could improve the management of HCV recurrence post-transplantation: better graft selection and particularly younger donor age, accurate follow-up of HCV re-infection by yearly liver histology and/or non-invasive markers of fibrosis, better management of immunosuppression, avoidance of rejection episodes, treatment of co-factors such as insulin resistance, and improved modalities of antiviral therapy such as use of hematopoietic growth factors [18Berenguer M. Aguilera V. Prieto M. Ortiz C. Rodriguez M. Gentili F. et al.Worse recent efficacy of antiviral therapy in liver transplant recipients with recurrent hepatitis C: impact of donor age and baseline cirrhosis.Liver Transpl. 2009; 15: 738-746Crossref PubMed Scopus (60) Google Scholar, 19Cescon M. Grazi G.L. Cucchetti A. Vetrone G. Ravaioli M. Ercolani G. et al.Predictors of sustained virological response after antiviral treatment for hepatitis C recurrence following liver transplantation.Liver Transpl. 2009; 15: 782-789Crossref PubMed Scopus (68) Google Scholar, 20Veldt B.J. Poterucha J.J. Watt K.D. Wiesner R.H. Hay J.E. Rosen C.B. et al.Insulin resistance, serum adipokines and risk of fibrosis progression in patients transplanted for hepatitis C.Am J Transplant. 2009; 9: 1406-1413Crossref PubMed Scopus (107) Google Scholar, 21Carrion J.A. Torres F. Crespo G. Miquel R. Garcia-Valdecasas J.C. Navasa M. et al.Liver stiffness identifies two different patterns of fibrosis progression in patients with hepatitis C virus recurrence after liver transplantation.Hepatology. 2010; 51: 23-34Crossref PubMed Scopus (106) Google Scholar]. However, a favourable long-term outcome for recipients of HCV-infected graft after LT is more likely to be brought about by the development of new, highly effective antiviral therapies that can prevent or treat recurrent hepatitis C. In Europe and the United States, hepatitis C virus (HCV)-related end-stage liver disease is the main indicator of the need for liver transplantation (LT). Recurrence of hepatitis C in the graft is universal after LT in HCV RNA-positive candidates, leading to lobular or chronic active hepatitis in most patients and to cholestatic hepatitis in a minority of them. Cirrhosis occurs in 20–30% of transplant recipients within 5–10 years of transplantation [[1]Berenguer M. Prieto M. Rayon J.M. Mora J. Pastor M. Ortiz V. et al.Natural history of clinically compensated hepatitis C virus-related graft cirrhosis after liver transplantation.Hepatology. 2000; 32: 852-858Crossref PubMed Scopus (489) Google Scholar] and at least 10% of patients will require re-transplantation for hepatitis C graft failure. Following transplantation, a significant increase in viral load is observed as the HCV follows a more aggressive course in immunocompromised patients when compared to competent patients. As a result, patient and graft survival are lower in HCV-positive recipients than in HCV-negative recipients [[2]Forman L.M. Lewis J.D. Berlin J.A. Feldman H.I. Lucey M.R. The association between hepatitis C infection and survival after orthotopic liver transplantation.Gastroenterology. 2002; 122: 889-896Abstract Full Text Full Text PDF PubMed Scopus (944) Google Scholar]. Antiviral therapy based on pegylated interferon (Peg-IFN) in combination with ribavirin (RBV) is primarily given when there is histological evidence of recurrent HCV disease. However, as in the non-transplant setting, its efficacy is lower in HCV genotype 1 infected patients. The reported sustained virological response (SVR) rate with Peg-IFN and RBV in genotype 1 patients ranges from 12% to 40% (mean 28.7%) and is lower than in non-transplant patients [[3]Berenguer M. Systematic review of the treatment of established recurrent hepatitis C with pegylated interferon in combination with ribavirin.J Hepatol. 2008; 49: 274-287Abstract Full Text Full Text PDF PubMed Scopus (298) Google Scholar]. Factors potentially responsible for the reduced virological response to Peg-IFN and RBV therapy in the setting of LT are: prior non-response to (Peg) IFN and RBV before transplantation, high prevalence of genotype 1, immunosuppression, intolerance, and side effects of IFN or RBV. Tolerability is a major issue, with 70–80% of patients requiring dose reduction and 10–40% requiring drug discontinuation [[3]Berenguer M. Systematic review of the treatment of established recurrent hepatitis C with pegylated interferon in combination with ribavirin.J Hepatol. 2008; 49: 274-287Abstract Full Text Full Text PDF PubMed Scopus (298) Google Scholar]. Most studies show improvements in biochemical and necroinflammatory activity in virological responders. Less consistent improvements in fibrosis scores have been reported, possibly due to the stage of fibrosis at the initiation of therapy, with more advanced stages being less reversible [4Roche B. Sebagh M. Canfora M.L. Antonini T. Roque-Afonso A.M. Delvart V. et al.Hepatitis C virus therapy in liver transplant recipients: response predictors, effect on fibrosis progression, and importance of the initial stage of fibrosis.Liver Transpl. 2008; 14: 1766-1777Crossref PubMed Scopus (131) Google Scholar, 5Carrion J.A. Navasa M. Garcia-Retortillo M. Garcia-Pagan J.C. Crespo G. Bruguera M. et al.Efficacy of antiviral therapy on hepatitis C recurrence after liver transplantation: a randomized controlled study.Gastroenterology. 2007; 132: 1746-1756Abstract Full Text Full Text PDF PubMed Scopus (309) Google Scholar]. A survival benefit was also reported in virological responders [6Veldt B.J. Poterucha J.J. Watt K.D. Wiesner R.H. Hay J.E. Kremers W.K. et al.Impact of pegylated interferon and ribavirin treatment on graft survival in liver transplant patients with recurrent hepatitis C infection.Am J Transplant. 2008; 8: 2426-2433Crossref PubMed Scopus (96) Google Scholar, 7Picciotto F.P. Tritto G. Lanza A.G. Addario L. De Luca M. Di Costanzo G.G. et al.Sustained virological response to antiviral therapy reduces mortality in HCV reinfection after liver transplantation.J Hepatol. 2007; 46: 459-465Abstract Full Text Full Text PDF PubMed Scopus (173) Google Scholar]. Predictive factors associated with SVR are: initial viral kinetics and more specifically viral response assessed at 4 and 12 weeks of therapy, non genotype−1, adherence to therapy, baseline viremia, and baseline fibrosis stage (Table 1) [[3]Berenguer M. Systematic review of the treatment of established recurrent hepatitis C with pegylated interferon in combination with ribavirin.J Hepatol. 2008; 49: 274-287Abstract Full Text Full Text PDF PubMed Scopus (298) Google Scholar]. In this issue of the journal, Fukuhara et al. reported for the first time in transplant patients, a role of HCV genotype 1b mutations in sensitivity to Peg-IFN and RBV therapy [[8]Fukuhara T. Taketomi A. Okano S. Ikegami T. Soejima Y. Shirabe K. et al.Mutations in hepatitis C virus genotype 1b and the sensitivity of interferon–ribavirin therapy after liver transplantation.J Hepatol. 2010; 52: 672-680Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar]. The predictive potential of the combined analysis of viral mutations that included amino acid(s) (aa) 70 and 91 in the Core region, the interferon sensitivity-determining region (ISDR, aa 2209–2248), and the interferon/ribavirin resistance determining region (IRRDR, aa 2334–2379) in the NS5A region, was retrospectively evaluated. Fifty genotype 1 patients were treated with increasing doses of Peg-IFN alpha-2b and RBV. Nineteen patients were non-responders to standard IFN therapy before transplantation. Twenty-two (44%), 8 (16%), and 20 (40%) patients demonstrated SVR, relapse, and non-response, respectively. The pre-treatment viral load and low haemoglobin level were significant risks factors for the failure to achieve SVR. Native liver tissues and serum at liver transplantation were available for genetic analysis from 16 and 22 patients, respectively. The sequences of aa 70 and 91 in the Core region, ISDR and IRRDR between liver tissues and serum were the same in the 12 patients in which both liver tissues and serum were available. Post-transplant liver tissues and serum were analyzed in 10 and 6 patients, respectively. The sequences of the Core and NS5A regions in the pre- and post-transplant samples were identical, except for aa 70 in the Core of only one patient. The patients were divided into two groups based on the mutation of aa 70 and 91 in the Core region (DW and non-DW), the number of ISDR mutations (ISDR ⩾2 and ISDR <2) and the number of IRRDR mutations (IRRDR ⩾6 and IRRDR <6). The rate of SVR was significantly lower in the non-double wild at aa 70 and 91, the ISDR <2 and IRRDR <6 groups than in the double wild (30% vs. 65%, p= 0.015), the ISDR ⩾2 (35% vs. 69%, p= 0.035), and IRRDR ⩾6 (25% vs. 78%, p<0.001) groups. A predictive scoring system based on the number of positive factors including the double wild in the Core region, ISDR ⩾2 and IRRDR ⩾6 in the NS5A region could be established before transplantation and allowed the stratification of the sensitivity of antiviral therapy after LT. The rate of SVR in this prediction score was 18%, 38%, 86%, and 100% for the presence of 0, 1, 2, or 3 positive factors, respectively (p<0.001). The results reported in this study are important since no other pre-transplant predictor, for the achievement of SVR after antiviral therapy post-transplant in genotype 1 patients has been reported. A limitation of this study is the absence of a multivariate analysis of the predictive factors of SVR in order to evaluate the importance of viral factors as compared to early viral kinetics and other pre- and on-treatment predictors of response. In the non-transplant setting, some studies from western countries and Japan reported that in patients with chronic HCV genotype 1 infection, there is a strong correlation between response to IFN and mutations in the NS5A protein, particularly in the ISDR and IRRDR regions [9Enomoto N. Sakuma I. Asahina Y. Kurosaki M. Murakami T. Yamamoto C. et al.Mutations in the nonstructural protein 5A gene and response to interferon in patients with chronic hepatitis C virus 1b infection.N Engl J Med. 1996; 334: 77-81Crossref PubMed Scopus (980) Google Scholar, 10Munoz de Rueda P. Casado J. Paton R. Quintero D. Palacios A. Gila A. et al.Mutations in E2-PePHD, NS5A-PKRBD, NS5A-ISDR, and NS5A-V3 of hepatitis C virus genotype 1 and their relationships to pegylated interferon–ribavirin treatment responses.J Virol. 2008; 82: 6644-6653Crossref PubMed Scopus (57) Google Scholar, 11El-Shamy A. Nagano-Fujii M. Sasase N. Imoto S. Kim S.R. Hotta H. Sequence variation in hepatitis C virus nonstructural protein 5A predicts clinical outcome of pegylated interferon/ribavirin combination therapy.Hepatology. 2008; 48: 38-47Crossref PubMed Scopus (120) Google Scholar, 12Shirakawa H. Matsumoto A. Joshita S. Komatsu M. Tanaka N. Umemura T. et al.Pretreatment prediction of virological response to peginterferon plus ribavirin therapy in chronic hepatitis C patients using viral and host factors.Hepatology. 2008; 48: 1753-1760Crossref PubMed Scopus (122) Google Scholar] and at aa 70 and 91 of the Core region [13Akuta N. Suzuki F. Hirakawa M. Kawamura Y. Yatsuji H. Sezaki H. et al.A matched case-controlled study of 48 and 72 weeks of peginterferon plus ribavirin combination therapy in patients infected with HCV genotype 1b in Japan: amino acid substitutions in HCV core region as predictor of sustained virological response.J Med Virol. 2009; 81: 452-458Crossref PubMed Scopus (64) Google Scholar, 14Okanoue T. Itoh Y. Hashimoto H. Yasui K. Minami M. Takehara T. et al.Predictive values of amino acid sequences of the core and NS5A regions in antiviral therapy for hepatitis C: a Japanese multi-center study.J Gastroenterol. 2009; 44: 952-963Crossref PubMed Scopus (77) Google Scholar]. In the study of Shirakawa et al., the multivariate logistic regression analysis for factors associated with SVR showed that mutant ISDR was the strongest predictor (OR = 86.0, 95% CI 6.4–1162.3) as compared to early viral kinetics (OR = 12.0, 95% CI 2.4–60) or total dose of Peg-IFN (OR = 23.1, 95% CI 2.7–194.9) [[12]Shirakawa H. Matsumoto A. Joshita S. Komatsu M. Tanaka N. Umemura T. et al.Pretreatment prediction of virological response to peginterferon plus ribavirin therapy in chronic hepatitis C patients using viral and host factors.Hepatology. 2008; 48: 1753-1760Crossref PubMed Scopus (122) Google Scholar]. Few studies have analyzed the effect of virological factors (except genotype) on the outcome of HCV recurrence post-LT. Feliu et al. assessed the early virological response to antiviral therapy in a cohort of 11 patients treated immediately before and after LT and compared HCV sequences from hyper-variable region 1 and NS5A region before both treatments [[15]Feliu A. Carrion J.A. Massaguer A. Martinez-Bauer E. Garcia-Retortillo M. Gonzalez P. et al.Sensitivity to antiviral therapy may change after liver transplantation in patients with chronic hepatitis C virus infection.J Viral Hepat. 2006; 13: 544-551Crossref PubMed Scopus (15) Google Scholar]. Eight patients showed identical early viral kinetics to both courses of therapy and interestingly the type of response changed in 3 patients: 2 non-responders obtained early virological response and an early virological responder became a non-responder. The differences between the sequences of the NS5A region were very few, suggesting that the changes in sensitivity to therapy after LT are not exclusively dependent on variations in HCV strains and might be related to host factors. However, sequence analysis of the NS5A region showed that fixation of mutations in this region occurred preferentially in individuals who became sensitive to IFN after LT. Another study showed that the NS3 and the NS5B regions evolved independently after LT [[16]Massaguer A. Ramirez S. Carrion J.A. Gonzalez P. Sanchez-Tapias J.M. Forns X. Evolution of the NS3 and NS5B regions of the hepatitis C virus during disease recurrence after liver transplantation.Am J Transplant. 2007; 7: 2172-2179Crossref PubMed Scopus (12) Google Scholar]. The genetic evolution of the NS3 domain was not related to the severity of the recurrence. However, the diversification in the NS5B region was greater in patients with mild recurrences than in those with severe recurrences, suggesting that immune pressure was stronger in the former group. In a previous study we found a strong positive correlation between genetic variability in the Core sequences of 53 genotype 1 patients and differences in 5-year fibrosis scores and in viral load [[17]Gigou M. Roque-Afonso A.M. Falissard B. Penin F. Dussaix E. Feray C. Genetic clustering of hepatitis C virus strains and severity of recurrent hepatitis after liver transplantation.J Virol. 2001; 75: 11292-11297Crossref PubMed Scopus (27) Google Scholar]. Following LT, there are major changes in viral and host variables that might influence the response to therapy: (a) the variation in quasi-species composition after LT; (b) the genetic background of the liver graft is singular and the activation of IFN-dependent antiviral pathways may be different in each individual; (c) the immune pressure on HCV is modified by immunosuppression. Taking these factors into consideration, pre-transplant prediction of response to antiviral therapy after LT seems very difficult. As in the non-transplant setting, the decision to treat should take into account all parameters: age, general status, genotype, severity of the hepatitis, rapidity of fibrosis progression, risk of graft loss, and expected tolerance to the treatment. The presence of HCV mutations may represent a new tool that may help in the decision to undertake antiviral therapy post-transplantation but in no way it does it represent a factor limiting the indication of transplantation. This new technique is not fully evaluated and should be assessed in larger studies. A multifactorial approach could improve the management of HCV recurrence post-transplantation: better graft selection and particularly younger donor age, accurate follow-up of HCV re-infection by yearly liver histology and/or non-invasive markers of fibrosis, better management of immunosuppression, avoidance of rejection episodes, treatment of co-factors such as insulin resistance, and improved modalities of antiviral therapy such as use of hematopoietic growth factors [18Berenguer M. Aguilera V. Prieto M. Ortiz C. Rodriguez M. Gentili F. et al.Worse recent efficacy of antiviral therapy in liver transplant recipients with recurrent hepatitis C: impact of donor age and baseline cirrhosis.Liver Transpl. 2009; 15: 738-746Crossref PubMed Scopus (60) Google Scholar, 19Cescon M. Grazi G.L. Cucchetti A. Vetrone G. Ravaioli M. 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However, a favourable long-term outcome for recipients of HCV-infected graft after LT is more likely to be brought about by the development of new, highly effective antiviral therapies that can prevent or treat recurrent hepatitis C.