I= CHARACTERIZATION OF HEPATITIS C VIRAL KINETICS IN VIVO WITH CLINICOPATHOLOGIC AND THERAPEUTIC DIMENSIONS
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Title of Thesis
CHARACTERIZATION OF HEPATITIS C VIRAL KINETICS IN VIVO WITH CLINICOPATHOLOGIC AND THERAPEUTIC DIMENSIONS

Author(s)
Jafar Khan
Institute/University/Department Details
Department of Microbiology / Faculty of Biological Sciences/ Quaid-i-Azam University Islamabad
Session
2007
Subject
Microbiology
Number of Pages
198
Keywords (Extracted from title, table of contents and abstract of thesis)
hepatitis c, non-cirrhotic chronic hepatitis c, fibrosis, moderate necro-inflammatory activity, alanine aminotransferase, serum bilirubin, hcv, fibrotic changes

Abstract
Hepatitis C viral kinetics is one of the most important precise predictive factors for the therapeutic outcome, with significant qualification to clinico-pathologic profile of chronic hepatitis C patients. The study aims to know how much the prevailing treatment regimens, baseline host and viral factors can influence the serum hepatitis C virus (HCY) RNA levels and if liver biopsy can be bypassed in the diagnosis and staging of the disease itself and in response to treatment.

The work included prospective, randomized control trials based on meta-analysis in which two hundred and twelve (212) non-cirrhotic chronic hepatitis C patients with compensated liver disease were randomly assigned to four groups. These trials as a matter of convenience and feasibility were categorized to achieve the relevant objectives on a concise, underlined clinical and pathological dimensions.

In Group-I twenty eight (n=28) chronic hepatitis C genotype-1 infected patients were randomly assigned for therapy with either 180 microgram peg.interferon α-2a once weekly for 48 weeks with ribavirin (n1=8) or without ribavirin (n2=13) and 3 million international units of the standard interferon α-2b 3 times per week plus ribavirin for 48 weeks (n3=7).Ribavirin was administered orally twice a day for a total dose of 1000mg per day (body weight‰ 75kg) or 1200mg (body weight ‰ 75kg). All patients were evaluated and monitored for virologic response. A dynamic equilibrium between viral production and clearance that characterizes untreated chronic hepatitis C infection, is altered after the initiation of antiviral therapy and analyzed on appropriate mathematical dimensions ultimately elucidating the impact of antiviral output on treatment related outcome. A typical multiphasic decay of HCV viremia was observed with antiviral therapy. The first phase of rapid initial viral decay (day -1) was followed by a second slow viral decline (day 2-21) and a third phase (day 7-28) associated with the virologic End of Treatment Response (ETR) and Sustained Virologic Response (SVR). Comparatively higher rates of Sustained Virologic Response (SVR) and End of Treatment Response (ETR) were observed more pronounced in patients treated with peginterferon α-2a plus ribavirin, than standard combination treatment. Further, the peginterferon α-2a and ribavirin proved to be more effective in treatment enhanced viral degradation than standard interferon combination therapy or mono-therapy, leading to a better ETR and SVR in chronic hepatitis C patients.

For prediction of treatment response in patients with chronic hepatitis C, the significance of baseline parameters was analyzed with viral kinetics during therapy. To this effect, in group 11, eighty seven (n=87) HCV genotype 1,2,3 and 4 infected patients, a randomized control trial was held to underscore the role of any host and viral baseline parameters that could modify their response to treatment. Among patients of this group (n=87), thirty seven (n= 37) were given a high dose of induction therapy with interferon and twenty five (n= 25) patients each, were treated with standard and peg.interferon in combination with ribavirin respectively. Early prediction of virologic response at week 4 and 12 was analyzed, using quantitative branched DNA assay (b DNA) version 3.0; and qualitative transcription mediated amplification (TMA) HCV RNA assay along with the biochemical, virologic, and histologic baseline parameters. On the basis of multivariate logistic regression analysis and receiver operating characteristic (ROC) curves of all patients, the independent predictors for sustained virologic response were genotype 2 and 3 (P< 0.0001), a low baseline gamma glutamyl transferase (GGT) level (P< 0.0001), a high baseline alanine aminotransferase (ALT) level (P= 0.002) and a low baseline viral load (P= 0.04). This data reveal that virologic non-response can be predicted early at week 12 of therapy independent of the therapeutic regimen, based on cut-off level for HCV RNA of 30,000iu/ml. Considering the number of side effects and treatment costs, virologic non-responders can thus be identified earlier than at week 24 or 48.

Also in a Group III meta-analytical trial, the data of twenty one (n=21) genotype-2 infected chronic hepatitis C patients was scrutinized and assessed for any association between viral kinetics (turnover of HCV release from hepatocytes into the bloodstream, persistence and elimination) and alanine aminotransferase (ALT) dynamics (patterns of AL T changes). All patients (n=21) of HCV genotype-2 were included 10 the trial and were daily treated with 10MID interferon α-2b with or without ribavirin for 28 days followed by standard interferon-ribavirin therapy (3MIU interferon α-2b three times per week in combination with ribavirin) for the rest of 48weeks. In association with HCV dynamics, 4 patterns of ALT changes were exhibited by these patients: (1) Exponential decay of ALT, (2) Transient small increase in AL T followed by a decrease to pre-treatment or normal levels, (3) Increase in AL T to a new high level and (4) No significant change. A small, (on average <10%) initial increase in ALT level over the first 48 hours was significantly associated with better response of viral negativity by 48 weeks and sustained virologic response (SVR) at 72 weeks (P=0.02). The week 4 ALT decline correlated with the HCV log drop (P=0.006) and the efficacy of therapy. Those patients exhibiting a new higher ALT levels during the first 48 hours had lower treatment effectiveness at inhibiting the viral production. By simultaneously modeling HCV and AL T dynamics, the changes can be fitted to incorporate ALT as a surrogate marker for treatment effect in chronic hepatitis C patients with elevated ALT. Therefore, a more frequent ALT analyses can have a positive predictive value for the treatment outcome.

Finally, in Group IV patients (n=76), the usefulness of previously validated biochemical markers [Fibrotest (FT) and Actitest (AT)] for knowing the fibrotic and activity changes in liver was estimated. The aim was to evaluate the diagnostic value of Fibrotest (FT) and Actitest (AT) in chronic hepatitis e patients at baseline and at the end of follow-up (24 weeks after treatment). Out of the 76 patients, 45 received peg. interferon α-2b (1.5 micro gram per kg once weekly and ribavirin) and the n=31 patients were administered standard interferon α-2b 3MU three times a week, with ribavirin for 48 weeks. The liver biopsies were performed before treatment and at 72 weeks (24 weeks follow-up) after randomization using the standard techniques. The MET A VIR and Knodell scoring systems were employed to generate the data for degree of fibrosis and activity to arrive at decision algorithm with end-points of histologic impact on chronically HCV infected liver. The Fibrotest (FT) comprises of five (5) markers: α-2 macroglobulin, haptoglobin, gamma glutamyl transferase (GOT), total bilirubin and apo-lipoprotein while Actitest (AT) comprises of the same five markers plus alanine aminotransferase (AL T). The biochemical markers have significant predictive values both for the diagnosis of fibrosis and activity. For the detection of bridging fibrosis or moderate necro-inflammatory activity, the area under the receiver operating characteristics (AUROC) curve of the activity index was 0.76±0.03 at baseline and 0.82±0.02 at the end of follow-up. A cut-off of the activity index at 0.30 (range, 0.00-1.00) had 90% sensitivity and 88% positive predictive value for the diagnosis of bridging fibrosis or moderate necro-inflammatory activity. A combination of 5 fibrosis and 6 activity test (FTAT) biochemical markers can be used as surrogate markers for liver biopsy in chronic hepatitis C patients with more convenience and accuracy bypassing therefore the need for liver biopsy under appropriate clinical conditions. This combination of FT-AT (Fibrotest-Actitest) can therefore have high positive or negative predictive values for diagnosis of significant liver fibrosis and activity changes in patients with chronic hepatitis e. The simplification of liver damage assessment would thus accelerate the management of chronic hepatitis e, both in terms of initial evaluation and comprehensive follow up.

Download Full Thesis
4839.97 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
469.51 KB
2 1 Introduction 1
250.97 KB
  1.1 Background And Rationale 1
  1.2 Aims And Objectives Of The Study 9
3 2 Review Of Literature 10
678.55 KB
  2.1 Structure Of Hepatitis C Virus( HCV) 10
  2.2 Factors Affecting Progression Of Chronic Hepatitis C 15
  2.3 Side Effects Of Chronic Hepatitis C Therapy 18
  2.4 Viral Levels Monitoring During Treatment Of Chronic Hepatitis C 21
4 3 Materials And Methods 36
1109.7 KB
  3.1 Study Design 36
  3.2 Inclusion Criteria 36
  3.3 The Sample Size And Randomized Control Trials 39
  3.4 Specimen Collection For Qualitative And Quantitative Detection Of Hcv 40
  3.5 Detection And Quantitation Of Hepatitis C Virus 41
  3.6 Determination Of Alanine Aminotransferase (ALT ) 51
  3.7 Determination Of Serum Bilirubin 53
  3.8 Liver Biopsy 59
  3.9 Statistical Analysis 61
  3.10 Group -I: A Randomized Control Trial To Establish Hepatitis C Viral Kinetics In Response To Treatment. 62
  3.11 Group-II: A Randomized Control Trial To Determine The Relationship Of Baseline Parameters In HCV Kinetics During Treatment 66
  3.12 Group-III: A Randomized Control Trial To Compare HCV Kinetics Versus Alanine Aminotransferase (Al T) Dynamics During Treatment 70
  3.13 Group-IV: A Randomized Control Trial For The Evaluation Of Therapeutic Responses By Assessment Of Biochemical Markers For Fibrotic Changes In Liver During Chronic Hepatitis-C 74
5 4 Results 77
1197.46 KB
  4.1 Group -I: A Randomized Control Trial To Establish Hepatitis C Viral Kinetics In Response To Treatment 81
  4.2 Group-II: A Randomized Control Trial To Determine The Relationship Of Baseline Parameters In HCV Kinetics During Treatment 88
  4.3 Group-III: A Randomized Control Trial To Compare HCV Kinetics Versus Alanine Aminotransferase (ALT) Dynamics During Treatment 107
  4.4 Group-IV: A Randomized Control Trial For The Evaluation Of Therapeutic Responses By Assessment Of Biochemical Markers For Fibrotic Changes In Liver During Chronic Hepatitis-C 115
6 5 Discussion And Conclusions 141
653.29 KB
  5.1 Group -I: A Randomized Control Trial To Establish Hepatitis C Viral Kinetics In Response To Treatment 144
  5.2 Group-II: A Randomized Control Trial To Determine The Relationship Of Baseline Parameters In HCV Kinetics During Treatment 149
  5.3 Group-III: A Randomized Control Trial To Compare HCV Kinetics Versus Alanine Aminotransferase (Alt) Dynamics During Treatment 154
  5.4 Group-IV: A Randomized Control Trial For The Evaluation Of Therapeutic Responses By Assessment Of Biochemical Markers For Fibrotic Changes In Liver During Chronic Hepatitis-C 157
  5.5 Conclusions 162-164
7 6 References 165-195
742.37 KB
  6.1 Annextures 196-197