Einfluss von Ribavirin auf die Dynamik der Hepatitis-C-Virämie bei Interferon-α-behandelten Patienten mit Response oder Nonresponse

Zusammenfassung

Die IFNα-Ribavirin-Kombinationstherapie hat sich bei Patienten mit chronischer Hepatitis C gegenüber einer alleinigen IFNα-Therapie als überlegen erwiesen. In dieser Studie wurde deshalb untersucht, ob Ribavirin, dessen Wirkungsmechanismus unklar ist, einen zusätzlichen Effekt auf die Hepatitis-C-Virämie hat. Verglichen wurde die Dynamik der Hepatitis-C-Virämie zwischen Patienten, die entweder auf eine IFNα-Mono- oder Kombinationstherapie angesprochen, oder Patienten, die auf beide Therapieformen keine Response gezeigt hatten.

64 unvorbehandelte Patienten mit chronischer Hepatitis C hatten entweder 3 × 6 Mio. Einheiten IFNα-2a (Hoffmann-La Roche)/Woche (n = 34) oder IFNα plus Ribavirin (Meduna) (14 mg/kg/Tag) (n = 30) für 12 Wochen erhalten. 37 der 64 behandelten Patienten (58 %) wurden nach 3-monatiger Therapie HCV-RNA-negativ (= Responder; 17 [46 %] mit IFNα-Monotherapie und 20 [54 %] mit Kombinations­therapie). Die restlichen 27 Patienten blieben HCV-RNA-positiv (= Nonresponder; 13 [48 %] mit IFNα-Monotherapie und 14 [52 %] mit Kombinationstherapie). Die HCV-RNA-Konzentrationen (bDNA assay, Chiron) wurden vor und 1, 2, 4 und 12 Wochen nach Therapiebeginn bestimmt. Mittels nicht­radioaktiver Einzelstrang-Konformations-(SSCP)Analyse der hypervariablen Region des HCV wurde untersucht, inwieweit der initiale Abfall der Hepatitis-C-Virämie bei Nonresponder-Patienten mit Änderungen der Virus­population (Quasispeziesverteilung) einhergeht.

Bei den Respondern hatte die Ribavirintherapie keinen Einfluss auf den Abfall der Hepatitis-C-Virämie. Auch bei den Nonrespondern kam es unabhängig von der Therapieform in der ersten Therapiewoche (Phase 1) zu einem Rückgang der Virämie (im Mittel 10,0 ± 2,3 auf 5,5 ± 1,1 MEq/ml). Im ­weiteren Verlauf (Phase 2) kam es jedoch unter IFNα-Monotherapie zu einem Anstieg der Virämie, während unter ­Kombinationstherapie ein weiterer Rückgang der HCV-RNA Konzentrationen zu verzeichnen war (Woche 12: 7,5 ± 2,9 MEq/ml [IFNα-mono, n = 12] vs. 3,0 ± 0,5 MEq/ml ­[Kombination, n = 15]). Der initiale Abfall der Virämie zeigte jedoch bei allen Nonrespondern individuell deutliche Unterschiede (Spannweite der Abnahme von 0-98 %, verglichen mit der Ausgangsvirämie) und bei 5 der 27 Nonresponder kam es zu einer Abnahme ≥ 1 log (≥ 90 %). Mittels SSCP­Analyse konnte keine signifikante Korrelation zwischen ­Virämieverlauf und Änderungen der Viruspopulation (SSCP-Bandenmuster) hergestellt werden.

Unsere Beobachtungen zeigen, dass Ribavirin in Kombination mit IFNα einen zusätzlichen, jedoch erst verzögert (2-4 Wochen nach Therapiebeginn) einsetzenden antiviralen/immunmodulatorischen Effekt hat. Der auch bei den Nonrespondern zu beobachtende 2-phasige Virämieverlauf kann nicht allein durch die Selektion primär IFNα-resistenter HCV-Varianten erklärt werden. Die individuellen Unterschiede bezüglich der Dynamik der Hepatitis-C-Virämie bei IFNα-Nonrespondern legen eine Neubewertung der Definition von Nonresponse nahe.

Influence of ribavirin on the dynamics of hepatitis C ­viremia in interferon-α-treated patients with response or nonresponse

Combination therapy with interferon-α (IFNα) plus Ribavirin has been shown to improve the response rate in patients with chronic hepatitis C as compared to IFNα alone. However, the mode of anti-viral action of Ribavirin is still unknown. To prove, whether Ribavirin has any additional effect on the decline of hepatitis C viremia during the first weeks of treatment patients with and without combination therapy were compared. Kinetic studies were performed in patients who either responded to IFNα alone or IFNα plus ­Ribavirin combination as well as in nonresponders to both forms of therapeutic approaches.

64 IFNα naive patients with histologically proven chronic hepatitis C were included in the study. Patients were random­ized to receive either IFNα-2a (Hoffmann-La Roche) 6 MU thrice weekly or IFNα 6 MU tiw plus Ribavirin (Meduna) 14 mg/kg/day for 12 weeks. 37 patients (58 %) became HCV RNA-negative (= responders; 17 [46 %] with IFNα alone, and 20 [54 %] with combination therapy). 27 patients remained HCV RNA-positive (= non-responders; 13 [48 %] with ­IFNα alone, and 14 [52 %] with combination therapy). HCV RNA concentrations were measured in all patients at baseline as well as 1, 2, 4, and 12 weeks after the start of treatment (bDNA assay, Chiron). Using nonradioactive single-stranded conformation (SSCP)-analysis of the HCV hypervariable ­region 1 we investigated further whether initial viral decline is correlated with changes in viral quasispecies distribution.

In primary responders, ribavirin did not influence hepatitis C viremia decline which was of biphasic nature. Also in nonresponders HCV RNA levels decreased after one week of treatment irrespectively of the mode of therapy (mean 10.0 ± 2.3 to 5.5 ± 1.1) (phase 1). In the following weeks, how­ever, 2 types of HCV dynamics could be observed ­(phase 2). In patients with combination therapy, a further reduction of viremia level could be observed, whereas viremia levels in patients with IFNα alone slightly increased (week 12: 3.0 ± 0.5 MEq/mL [combination, n = 15] vs. 7.5 ± 2.9 MEq/mL [IFNα-mono, n = 12]). The individual response of these nonresponder patients showed, however, marked differ­ences (range percentage decline after 4 weeks, 0-98 %). Changes in the viral population (quasispecies distribution) as cause of these differences could be excluded by SSCP-analysis of PCR products of the HCV hypervariable region 1.

Ribavirin in combination with IFNα exerts an additional anti-viral/immunmodulatory effect which manifests itself in phase 2 of hepatitis C viremia decline. The biphasic decline of hepatitis C viremia also observed in IFNα-nonresponders can not be explained by the selection of primary IFNα-resistant viral variants. The individual differences in the dynamic of hepatitis C viremia observed in the so called „nonresponders” imply that the term „nonresponder” should be redefined, considering our observation that a marked viral decline can occur in these patients.

Schlüsselwörter

HCV - Viruskinetik - antivirale Therapie - Quasispeziesverteilung

Key words

HCV - Virus Kinetics - Antiviral Therapy - ­Quasispecies Distribution

Literatur

• 1 Poynard T, Marcellin P, Lee S S. et al . Randomized trial of interferon (2b plus ribavirin for 48 weeks or 24 weeks versus interferon (2b plus placebo for 48 weeks for treatment of chronic infection with hepatitis C virus.  Lancet. 1998;  352 1426-1432
• 2 McHutchison J G, Gordon S C, Schiff E R. et al . Interferon alfa-2b alone or in combination with ribavirin as initial treatment for chronic hepatitis C.  N Engl J Med. 1998;  339 1485-1492
• 3 Patterson J L, Fernandez-Larsson R. Molecular mechanisms of action of ribavirin.  Rev Infect Dis. 1990;  12 1139-1146
• 4 Sidwell R W, Huffman J H, Kharp L. Broad spectrum activity of virazole: 1-beta-D-ribofuranosyl-1,2,3-triazole-3-carboxamide.  Science. 1972;  117 705-706
• 5 Reichard O, Andersson J, Schvarcz R, Weiland O. Ribavirin treatment for chronic hepatitis C.  Lancet. 1991;  337 1058-1061
• 6 Zeuzem S, Schmidt S M, Lee J H. Hepatitis C virus dynamics in vivo: Effect of ribavirin and interferon alfa.  Hepatology. 1998;  28 245-252
• 7 Ning Q, Brown D, Parodo J. et al . Ribavirin inhibits viral induced macrophage production of TNF, IL-1, the procoagulant fgl2 prothombinase and preserves Th1 cytokine production but inhibits Th2 cytokine response.  J Immunol. 1998;  160 3487-3493
• 8 Forns X, Purcell R H, Bukh J. Quasispecies in viral persistence and pathogenesis of hepatitis C virus.  Trends Microbiol. 1999;  7 402-410
• 9 Berg T, Hoffmann R M, Teuber G. et al . Efficacy of short-term Ribavirin plus interferon alfa combination therapy followed by interferon alone in previously untreated patients with chronic hepatitis C.  A randomized trial Liver. 2000;  20 (im Druck)
• 10 Orita M, Iwahana H, Kanazawa H, Hayashi K, Sekiya T. Detection of polymorphisms of human DNA by gel electrophoresis as single-strand conformation polymorphisms.  Proc Natl Acad Sci. 1989;  86 2766-2770
• 11 Kato N, Hijikata M, Ootsuyama Y. et al . Molecular cloning of the human hepatitis C virus genome from Japanese patients with non-A non-B hepatitis.  Proc Natl Acad Sci. 1990;  87 9524-9528
• 12 Binder T, Berg T, Hopf U, Siegert W, Schmidt C A. PCR-SSCP: Nonradioactive detection with biotinprimers and streptavidine-alkaline phosphatase conjugates.  BioTechniques. 1995;  18 780-781
• 13 Lee J H, Stripf T, Roth W K, Zeuzem S. Non-isotopic detection of hepatitis C virus quasispecies by single strand conformation polymorphism.  J Med Virol. 1997;  53 245-251
• 14 Neumann A U, Lam N P, Dahari H. et al . Hepatitis C viral dynamics and the antiviral efficacy of interferon-α therapy.  Science. 1998;  282 103-107
• 15 Zeuzem S, Schmidt J M, Lee J H, Rüster B, Roth W K. Effect of interferon alfa on the dynamics of hepatitis C virus turnover in vivo.  Hepatology. 1996;  23 366-371
• 16 Lam N, Neumann A, Gretch D. Dose-dependent acute clearance of hepatitis genotype 1 virus with interferon alfa.  Hepatology. 1997;  26 226-231
• 17 Ilyin G P, Langouet S, Rissel M. Ribavirin inhibits protein synthesis and cell proliferation induced by mitogeic factors in primary human and rat hepatocytes.  Hepatology. 1998;  27 1687-1694
• 18 Montero C, Duley J A, Fairbanks L D. Demonstration of induction of erythrocyte inosine monophosphate dehydrogenase activity in ribavirin-treated patients using a high performance liquid chromatography linked method.  Clin Chim Acta. 1995;  238 169-178
• 19 Hultgren C, Milich D R, Weiland O, Sallberg M. The antiviral compound ribavirin modulates the T helper (Th) 1/Th2 subset balance in hepatitis B and C virus-specific immune responses.  J Gen Virol. 1998;  79 2381-2391
• 20 Brillanti S, Migliolo M, Barbara L. Combination antiviral therapy with ribavirin and interferon alfa in interferon alfa relapsers and nonresponders: Italian experience.  J Hepatol. 1995;  23 (Suppl. 2) 13-16
• 21 Schalm S W, Brouwer J T, Chemello L. et al . Interferon-ribavirin combination therapy for chronic hepatitis C.  Dig Dis Sci 1996. 41 (Suppl.) 131-134
• 22 Schvarcz R, Ando Y, Sönnerborg A, Weiland O. Combination treatment with interferon alfa-2b and ribavirin for chronic hepatitis C in patients who failed to respond to achieve a sustained response to interferon alone: Swedish experience.  J Hepatol. 1995;  23 (Suppl. 2) 17-21
• 23 Teuber G, Berg T, Hoffmann R M. et al . Retreatment wit interferon-alpha and ribavirin in primary interferon-alpha nonresponders with chronic hepatitis C.  Digestion. 2000;  61 90-97
• 24 Kakumu S, Yoshioka K, Wakita T. et al . A pilot study of ribavirin and interferon beta for the retreatment of chronic hepatitis C.  Gastroenterology. 1993;  105 507-512
• 25 Bellobuono A, Mondazzi L, Tempini S. et al . Ribavirin and interferon-alpha combination therapy vs. interferon-alpha alone in the treatment of chronic hepatitis C: A randomized clinical trial.  J Viral Hepat. 1997;  4 185-191
• 26 Salmeron J, Ruiz-Extremera A, Torres C. et al . Interferon versus ribavirin plus interferon in chronic hepatitis C previously resistant to interferon: A randomized trial.  Liver. 1999;  19 275-280
• 27 Andreone P, Gramenzi A, Cursaro C. et al . Interferon-alpha plus ribavirin in chronic hepatitis C resistant to previous interferon-alpha course: Results of a randomized multicenter trial.  J Hepatol. 1999;  30 788-793
• 28 Tromm  A, Greving I, Griga T, Mankel K, Huppe D. Inter- feron-alpha-2b + ribavirin for the treatment of chronic hepatitis C in non-responders to interferon-alpha-monotherapy.  Z Gastroenterol. 2000;  38 159-164
• 29 Wedemeyer H, Jäckel E, Wedemeyer J. et al . Is combination therapy of chronic hepatitis C with interferon alpha and ribavirin in primary interferon nonresponders indicated? An analysis of personal experiences and review of the literature.  Z Gastroenterol. 1998;  36 819-827
• 30 Martell M, Esteban J I, Quer J. et al . Hepatitis C virus (HCV) circulates as a population of different but closely related genomes: Quasispecies nature of HCV genome distribution.  J Virol. 1992;  66 3225-3229
• 31 Kao J H, Chen P J, Lai M Y, Wang T H, Chen D S. Quasispecies of hepatitis C virus and genetic drift of the hypervariable region in chronic type C hepatitis.  J Infect Dis. 1995;  172 261-264
• 32 Shindo M, Hamada K, Koya S. et al . The clinical significance of changes in genetic heterogeneity of the hypervariable region 1 in chronic hepatitis C with interferon therapy.  Hepatology. 1996;  24 1018-1023
• 33 Pawlotsky J M, Germanidis G, Frainais P O. et al . Evolution of hepatitis C virus second envelope protein hypervariable region in chronically infected patients receiving alpha interferon therapy.  J Virol. 1999;  73 6490-6499
• 34 Gerotto M, Sullivan D G, Polyak S J. et al . Effect of retreatment with interferon alone or interferon plus ribavirin on hepatitis C virus quasispecies diversification in nonresponder patients with chronic hepatitis C.  J Virol. 1999;  73 7241-7247
• 35 Lee J H, von Wagner M, Roth W K. et al . Effect of ribavirin on virus load and quasispecies distribution in patients infected with hepatitis C virus.  J Hepatol. 1998;  29 29-35
• 36 González-Peralta R P, Liu W Z, Davis G R, Qian K P, Lau J YN. Modulation of hepatitis C virus quasispecies heterogeneity by interferon-α and ribavirin therapy.  J Viral Hepat. 1997;  4 99-106

Anschrift für die Verfasser: