Christoph Sarrazin

Telaprevir and pegylated interferon-alpha-2a inhibit wild-type and resistant genotype 1 hepatitis C virus replication in patients

Telaprevir (VX‐950) is an orally active, specifically targeted antiviral therapy for hepatitis C virus (HCV) that has been shown to profoundly reduce plasma HCV RNA in genotype 1 patients. Using a highly sensitive sequencing assay that detects minor populations of viral variants (≥5%), mutations were identified that conferred low‐level (V36M/A, T54A, or R155K/T) or high‐level (A156V/T and 36/155) resistance to telaprevir in vitro. We report a detailed kinetic analysis of these variants in 16 patients given telaprevir or telaprevir + pegylated interferon–alpha‐2a (PEG‐IFN–alpha‐2a) for 14 days. In 4 patients who had a viral rebound on telaprevir alone, the R155K/T and A156V/T variants were detected during the initial steep decline in HCV RNA. During the rebound phase, the R155K/T and A156V/T variants were replaced by V36(M/A)/R155(K/T) double mutant variants. In the remaining 12 patients given telaprevir alone or with telaprevir/PEG‐IFN–alpha‐2a, the A156V/T variant was detected in some patients, but viral levels continued to decline in all patients. Conclusion: These studies suggest that the initial antiviral response to telaprevir is due to a sharp reduction in wild‐type virus, which uncovers pre‐existing telaprevir‐resistant variants. In patients given telaprevir alone, viral rebound can result from the selection of variants with greater fitness. However, the combination of telaprevir and PEG‐IFN–alpha‐2a inhibited both wild‐type and resistant variants. In the present study, every patient who began PEG‐IFN–alpha‐2a and ribavirin after the 14‐day dosing period had undetectable HCV RNA levels at 24 weeks, indicating that telaprevir‐resistant variants are sensitive to PEG‐IFN–alpha‐2a and ribavirin. (HEPATOLOGY 2007.)

Viral Determinants of Resistance to Treatment in Patients with Hepatitis C

SUMMARY Chronic hepatitis C virus (HCV) infection affects more than 170 million persons worldwide and is responsible for the development of liver cirrhosis in many cases. Standard treatment with pegylated alpha interferon (IFN-α) in combination with the nucleoside analogue ribavirin leads to a sustained virologic response in approximately half of the patients. IFN-α is classified as an indirect treatment, as it interacts with the hosts immune response. The mechanism of action of ribavirin is still unknown. The benefit of triple therapy by adding other antiviral agents, e.g., amantadine, is controversial. Currently, new direct antiviral drugs (HCV protease/polymerase inhibitors) are being evaluated in phase 1/phase 2 trials. Phenotypic resistance to antiviral therapy has been attributed to amino acid variations within distinct regions of the HCV polyprotein. While sensitivity to IFN-α-based antiviral therapy in vivo is clearly correlated with the number of mutations within the HCV NS5A protein, the underlying functional mechanisms for this association are unknown. In turn, in vitro, several mechanisms to circumvent the host immune defense or to block treatment-induced antiviral activities have been described for different HCV proteins. By the introduction of direct antiviral drugs, hepatitis C therapy now is entering a new era in which the development of resistance may become the most important parameter for treatment success or failure.

Review article: predicting response in hepatitis C virus therapy

The introduction of combination therapy with ribavirin and of pegylated interferons has improved treatment results in patients with chronic hepatitis C. However, overall rates of sustained virologic response following antiviral therapy of chronic hepatitis C still do not exceed 54–63%. Because of several virus‐ and patient‐related factors, treatment is even less successful in some patient subpopulations.

Clinical Significance of In Vitro Replication–Enhancing Mutations of the Hepatitis C Virus (HCV) Replicon in Patients with Chronic HCV Infection

BACKGROUNDnMutations in nonstructural (NS) hepatitis C virus (HCV) proteins enhance replication in HCV-1a/b replicons. The prevalence of such mutations and their clinical significance in vivo are unknown.nnnMETHODSnParts of HCV NS3 and NS4B-NS5B genes that included 31 in vitro replication-enhancing sites were sequenced for 26 patients with chronic HCV genotype 1 infection.nnnRESULTSnFive patients showed specific mutations within NS3 at sites enhancing replication in the replicon. Those mutations were associated with a slower decrease in HCV RNA concentration during interferon (IFN)- alpha -based therapy (P = .007). Neither specific nor other mutations within NS3 and NS4B-NS5B were associated with baseline HCV RNA concentrations. Within NS5A, fewer mutations in the major HCV strain (P = .001) and increased quasi-species complexity (P = .02) and diversity (P = .02) correlated with increasing baseline HCV RNA concentrations. In silico analyses of NS3 protein structures suggested that the majority of observed mutations did not lead to major conformational changes.nnnCONCLUSIONSnSpecific mutations leading to enhanced replication in the replicon system were detected in 5 of 26 patients in vivo and were not associated with baseline HCV RNA concentrations but were associated with a slower decrease in HCV RNA concentration during IFN- alpha -based therapy. Quasi-species heterogeneity of NS5A correlated with baseline HCV RNA concentrations.

Mutations within the CD81-Binding Sites and Hypervariable Region 2 of the Envelope 2 Protein: Correlation with Treatment Response in Hepatitis C Virus–Infected Patients

The hepatitis C virus (HCV) envelope 2 (E2) protein interacts with the cellular receptor CD81 in vitro. Within E2, 2 CD81-binding sites were described. E2-CD81 interaction has been shown to modulate B and T cell function. The clinical importance of mutations within the CD81-binding sites and overlapping hypervariable region 2 (HVR2) in correlation with response to antiviral treatment is unknown. Fifty-five patients infected with HCV-1b or HCV-3a underwent interferon-alpha-based treatment. The E2 gene, comprising the CD81-binding sites and HVR2, was sequenced from pretreatment serum samples. The number of mutations within CD81-binding sites was not correlated with virologic treatment response in HCV-1b- and HCV-3a-infected patients. Within HVR2, the total number of mutations was significantly higher in HCV-1b-infected patients with a sustained response to interferon-alpha-based treatment (3.9; range, 1-6) than in those with relapse (2.9; range, 1-5) or those who did not respond (2.8; range, 1-5) (P = .041). However, when the same analyses were based only on functionally nonconserved mutations, no significant differences were observed.

Current therapy for hepatitis C

IntroductionPegylated interferon alfa in combination with ribavirin has been established as standard therapy for chronic hepatitis C virus (HCV) infection with sustained virologic response rates of 54–63%. The duration of therapy depends on the HCV genotype with currently 48 weeks for genotype 1 and 24 weeks for genotypes 2 and 3.Results and discussionThe probability of sustained virologic response is very low (<1–2%) in genotype-1-infected patients without a 2-log decline of HCV RNA concentration after 12 weeks of therapy, and treatment can therefore be discontinued early.ConclusionEfficient treatment of the multiple side-effects of interferon-based antiviral therapy is essential in order to improve compliance, prevent dose reduction or early discontinuation and therefore enhance the probability of sustained response. Future developments of interferon-based therapy aim at the individualisation of the duration of therapy according to the kinetics of viral reduction. Furthermore, direct antiviral drugs, which are currently under investigation in phase I/II clinical trials, will fundamentally expand the treatment options of HCV infection in the next few years.

The hepatitis C virus NS5A protein and response to interferon α: mutational analyses in patients with chronic HCV genotype 3a infection from India

The hepatitis C virus (HCV) non-structural (NS)5A protein is linked to interferon α resistance in vitro and higher numbers of NS5A amino acid (aa) variations in HCV 1a/b isolates are associated with virologic response to interferon α-based therapy in vivo. Here, we aimed to study NS5A aa variations in Indian patients undergoing interferon α/ribavirin treatment infected with HCV 3a. The NS5A region [aa 2194–2401, comprising interferon sensitivity determining region, protein kinase resource (PKR) binding domain, V3 region] was sequenced from pre-treatment sera of 24 patients with HCV 3a infection. Mean number and physicochemical properties of aa variations (conserved vs. non-conserved) were assessed. Additionally, published NS5A sequences [NS5A region (nxa0=xa061), PKR binding domain (nxa0=xa0111)] of characterized HCV 3a isolates were analyzed. The mean number of NS5A aa variations was not correlated with treatment response in our cohort. When all available NS5A sequences were included, a higher number of non-conserved aa variations within PKR binding domain and an extended V3 region of NS5A was associated with virologic response (Pxa0=xa00.004 and 0.05, respectively). Mutational analyses of a large number of NS5A sequences suggest, that a higher number of non-conserved aa variations within the PKR binding domain and the extended V3 region is correlated with virologic response in HCV 3a infected patients.

Akutes und chronisches Leberversagen

63.3 Intensivmedizinisches Management und Therapie der Komplikationen des ALV und ACLV – 836 63.3.1 Hepatische Enzephalopathie (HE) – 836 63.3.2 Renale Dysfunktion – 837 63.3.3 Hyponatriämie – 838 63.3.4 Alkoholische Hepatitis (ASH) – 838 63.3.5 Gastrointestinale Blutung – 838 63.3.6 Infektionen – 839 63.3.7 Aszites, spontan-bakterielle Peritonitis (SBP) – 839 63.3.8 Koagulopathie – 839 63.3.9 Beatmung und Sedierung – 840

Intensivtherapie bei akutem und chronischem Leberversagen

1.1 Epidemiologie Ein ALV stellt mit j€ahrlich sch€atzungsweise 200–500 F€allen in Deutschland eine insgesamt seltene Erkrankung dar (Canbay et al. 2011). Eine aktuelle retrospektive Analyse der Ursachen eines ALV in Deutschland zeigte, dass mittlerweile das medikamentös induzierte Leberversagen die Hauptursache (41 % der F€alle) ist (Hadem et al. 2012b). Auch wenn hierbei das Acetaminophen (Paracetamol)induzierte ALV mit 9 % der Gesamtf€alle einen bedeutenden Teil ausmacht, ist dieser Anteil im Vergleich zu US-amerikanischen Daten niedrig (dort bis zu 51 % der F€alle) (Larson et al. 2005). Im Vergleich zu historischen Daten hat der Anteil des viral bedingten ALV abgenommen (21 %). Bei fast 1/4 der F€alle bleibt die Ursache ungekl€art (Tab. 1).