Predictors of a sustained beneficial response to interferon alfa therapy in chronic hepatitis C

Triple therapy of initial high-dose interferon with ribavirin and amantadine for patients with chronic hepatitis C

AIMS

We previously reported the potential effect of combination therapy of an initial high-dose interferon (IFN) and amantadine on the eradication of HCV-RNA in patients with chronic hepatitis C. The additive effects of amantadine on interferon and ribavirin combination therapy remain controversial. In this study we investigated the efficacy of initial high-dose IFN with ribavirin and amantadine on the virological response in patients with chronic hepatitis C with a high viral load of genotype 1b.

METHODS

Twenty-two patients with high viral loads of genotype 1b hepatitis C virus were enrolled in this pilot study. Patients were administered IFN-beta for four weeks and then IFN-alpha2b for 22 weeks with daily oral administration of ribavirin and amantadine.

RESULTS

A sustained virological response (SVR) was shown in 31.8% (seven of 22 patients). With the naïve patients, the SVR rate was 21.4% (three of 14 patients). In patients who could not eradicate HCV-RNA by previous IFN monotherapy, the SVR rate was 50% (four of eight patients).

CONCLUSION

Triple therapy with an initial high dose of IFN with ribavirin and amantadine may be effective, especially for chronic hepatitis C IFN-retreatment patients with a high viral load of genotype 1b.

Expression of transforming growth factor beta-1 in chronic hepatitis and hepatocellular carcinoma associated with hepatitis C virus infection

BACKGROUND

Transforming growth factor beta-1 (TGF beta 1) has been suggested to play a role in the development, growth or progression of hepatocellular carcinoma (HCC). Genotype and serum titer of HCV also affect the occurrence of HCC in chronic hepatitis C. In this study, we were to evaluate the effects of genotype or serum titer of HCV on the expression of TGF beta 1. We also intended to examine the correlation between the up-regulation of TGF beta 1 and the association with HCC in patients with chronic hepatitis C.

METHODS

We studied 19 patients with chronic hepatitis C and 18 with HCC associated with HCV infection. HCV genotype was determined by line probe reverse hybridization assay and the amount of HCV-RNA was quantitated by branched DNA signal amplification assay. Serum TGF beta 1 level was measured by enzyme linked immunosorbent assay.

RESULTS

HCV genotypes of patients with HCC were similar to those without it. Serum HCV-RNA titer was higher in genotype 1b than in non-1b (p < 0.05). Serum TGF beta 1 levels were higher in HCC than in chronic hepatitis (p < 0.05). However, there was no significant difference in the serum TGF beta 1 level between genotype 1b and non-1b. Also, it was not correlated with the serum HCV-RNA titer or alanine aminotransferase levels.

CONCLUSION

TGF beta 1 seems to be overexpressed in HCC compared to that of chronic hepatitis C: it was not affected by serum ALT levels, genotype or serum HCV titer. It is suggested that TGF beta 1 may be associated with the malignant transformation of hepatocyte or the progression of HCV-associated HCC.

Predictors of the efficacy of interferon therapy for patients with chronic hepatitis C before and during therapy: how does this modify the treatment course?

Antiviral therapy for hepatitis C virus (HCV) infection should be based on the natural history of HCV infection; there is a sequential, but slow, progression from chronic hepatitis to cirrhosis, leading to death from either liver failure or hepatocellular carcinoma (HCC). The risk of HCC development increases in association with the advance of fibrosis, and antiviral therapy can reduce this risk. More than 30 indices have been proposed as 'predictors' of favourable response to IFN therapy: host factors (age, gender, duration of HCV-infection, alcohol intake, hepatic iron stores, platelet count, histological staging of the liver disease), viral factors (HCV RNA levels in serum, HCV subtype, diversity of the hypervariable region, mutation of non-structure 5A gene), and IFN factors (dose, duration of treatment, type, treatment regimens i.e. every day vs three times a week, escalating dose regimen). Before starting IFN therapy, HCV subtype and pretreatment HCV RNA load, as well as the fibrotic stage of the liver, should be determined. The response to IFN therapy should be monitored by the HCV RNA status in serum during therapy, and the treatment regimen modified, or discontinued as required. A sustained virological response should be checked at more than 3 months after the completion of therapy. Even though the risk of HCC is markedly reduced in sustained responders, it is possible to develop HCC several years after completion of IFN therapy.

[Characteristics of the hepatitis C virus and viral predictors of therapeutic response]

NATURAL HISTORY OF HEPATITIS C-INFECTION AND VIRAL CHARACTERISTICS: Hepatitis C-virus (HCV) infection is a major cause of non-A, non-B-hepatitis and, additionally, is associated with liver cirrhosis and hepato-cellular carcinoma. The high degree of chronificity of HCV-infection is reasonable due to antigenic variability of neutralizing epitopes leading to incomplete immunoresponse with subsequent virus persistence. Besides genetic variants of HCV within a virus population (quasispecies nature of HCV), different genotypes are classified being genetically and phenotypically distinct, and geographically restricted in part. Genotyping of HCV is not only important for phylogenetic and epidemiological studies, but also a predictive marker for pathogenesis and therapy. VIRAL PREDICTORS OF HCV THERAPY: In a meta-analysis of 18 therapeutical studies of chronical HCV infections, genotype 1 and high levels of viremia determined markedly the response to interferon therapy. In this context, clinical trials have proven the effect of a combined therapy with interferon and ribavirin. Especially patients with HCV genotype 1 or high levels of viremia had a real benefit from combined antiviral therapy in comparison to monotherapy with interferon. CONCLUSION AND FUTURE CONCEPTS: Besides recent concepts improving the therapeutical response to HCV infection, further effort is necessary to develop more successful strategies for eradication of hepatitis C virus. In this context, variations of interferon therapy should be evaluated (e.g. higher and daily doses, longer duration of interferon therapy, "retarded" interferon (PEG-IFN). In addition, new therapeutical concepts should be performed including a combination of interferon with other known antiviral agents (amantadine), a combination with immunomodulators (GM-CSF, thymosin alpha 1), the development of new antiviral agents (inhibitors of viral proteases, helicases and polymerases) and the exploration of anti-viral, molecular strategies (specific ribozymes, antisense oligonucleotides and DNA-vaccination). Nevertheless, the development of an effective vaccination should be the most important challenge for the future.

Interferon resistance of hepatitis C virus genotype 1b: relationship to nonstructural 5A gene quasispecies mutations

A 40-amino-acid sequence located in the nonstructural 5A (NS5A) protein of hepatitis C virus genotype 1b (HCV-1b) was recently suggested to be the interferon sensitivity-determining region (ISDR), because HCV-1b strains with an ISDR amino acid sequence identical to that of the prototype strain HCV-J were found to be resistant to alpha interferon (IFN-alpha) whereas strains with amino acid substitutions were found to be sensitive (N. Enomoto, I. Sakuma, Y. Asahina, M. Kurosaki, T. Murakami, C. Yamamoto, N. Izumi, F. Marumo, and C. Sato, J. Clin. Invest. 96:224-230, 1995; N. Enomoto, I. Sakuma, Y. Asahina, M. Kurosaki, T. Murakami, C. Yamamoto, Y. Ogura, N. Izumi, F. Marumo, and C. Sato, N. Engl. J. Med. 334:77-81, 1996). We used single-strand conformation polymorphism (SSCP) analysis, combined with cloning and sequencing strategies, to characterize NS5A quasispecies in HCV-1b-infected patients and determine the relationships between pre- and posttreatment NS5A quasispecies mutations and the IFN-alpha sensitivity of HCV-1b. The serine residues involved in phosphorylation of NS5A protein were highly conserved both in the various patients and in quasispecies in a given patient, suggesting that phosphorylation is important in NS5A protein function. A hot spot for amino acid substitutions was found at positions 2217 to 2218; it could be the result of either strong selection pressure or tolerance to these amino acid replacements. The proportion of synonymous mutations was significantly higher than the proportion of nonsynonymous mutations, suggesting that genetic variability in the region studied was the result of high mutation rates and viral replication kinetics rather than of positive selection. Sustained HCV RNA clearance was associated with low viral load and low nucleotide sequence entropy, suggesting (i) that the replication kinetics when treatment is started plays a critical role in HCV-1b sensitivity to IFN-alpha and (ii) that HCV-1b resistance to IFN-alpha could be conferred by numerous and/or related mutations that could be patient specific and located at different positions throughout the viral genome and could allow escape variants to be selected by IFN-alpha-stimulated immune responses. No NS5A sequence appeared to be intrinsically resistant or sensitive to IFN-alpha, but the HCV-J sequence was significantly more frequent in nonresponder quasispecies than in sustained virological responder quasispecies, suggesting that the balance between NS5A quasispecies sequences in infected patients could have a subtle regulatory influence on HCV replication.

Variables that influence response to different interferon schedules in chronic hepatitis C and predictive models

In chronic hepatitis C (HCV), standard interferon therapy with 3 MU three times weekly for 6 months is associated with sustained response in about 10-20% of patients while another 10-15% respond only when higher dosages or/and longer periods of treatment are used. Different variables have been described that are associated with sustained response and may also identify patients requiring low- or high-dose regimens. We have analysed a large data base of 442 patients with chronic hepatitis C treated with interferon-alpha to define rates of sustained response in different patient subgroups treated with different schedules. The rate of sustained response was increased with higher dose regimens in most patient categories, defined according to age, pre-treatment liver histology and HCV genotype, while the amount of interferon per one sustained response remained the same or was reduced. The use of higher dose regimen was particularly cost-effective in patients with cirrhosis. Using the same data base, different models of prediction of sustained response in the individual patient were developed and compared. Inclusion of the HCV genotype in these models was found to increase significantly specificity and sensitivity, confirming that this parameter has a major influence on sustained response to interferon therapy in chronic HCV.