On the outcome of antiviral therapy for hepatitis C virus genotype 2 or 3 infection

On the outcome of antiviral therapy for hepatitis C virus genotype 2 or 3 infection

Åsa Alsiö

Department of Infectious Diseases/Virology Institute of Biomedicine

Sahlgrenska Academy at University of Gothenburg

Göteborg 2011

Cover illustration: Hepatitis C virus

Reprinted with permission from utopiasilver

On the outcome of antiviral therapy for hepatitis C virus genotype 2 or 3 infection

© Åsa Alsiö 2011 asa.alsio@vgregion.se

ISBN 978-91-628-8374-4 Electronic publication http://hdl.handle.net/2077/2659

Printed in Gothenburg, Sweden 2011

Ineko

Contents

Abstract 4

Populärvetenskaplig sammanfattning 5

Abbreviations 6

List of papers 8

Introduction

History 9

Virology 10

Epidemiology and routes of transmission 11

Natural history 13

Diagnostic methods 17

Treatment 20

IL28B 21

IP-10 22

Aims 23

Methods

Study populations 24

Statistical Methods 32

Results

Impact of treatment duration on outcome 34

HCV Core Antigen 39

IP-10 predicting viral response 42

Characterization of nonresponders 46

Impact of obesity on treatment outcome 49 Discussion

Treatment duration 54

Identification of patients suitable for short-time therapy 56

IP-10 60

Impact of BMI on response and drug concentration 61

Conclusions 65

Acknowledgements 66

References 68

Abstract

Approximately 80% of patients infected with HCV genotypes 2 or 3 achieve a sustained virological response, (SVR) following 24 weeks of therapy with ribavirin and pegylated interferon (peg-IFN), but in light of considerable side effects and cost, shortened treatment duration without impaired efficacy is desirable. Thus, 382 genotype 2/3 infected patients were randomized in an investigator-initiated phase III study (NORDynamIC) evaluating the efficacy of 12 (short-term) vs. 24 (standard-of- care) weeks of treatment with peg-IFN α-2a 180 µg/week and ribavirin 800 mg/day.

Overall, 12 weeks of therapy was inferior to 24 (SVR 59% vs. 78%, P<0.0001)

regardless of fibrosis stage or HCV genotype. However, in a multivariate intention-to-

treat analysis, HCV RNA <1,000 IU/mL on day 7, age <40 years, and undetectable

HCV RNA on day 29 were independent predictors of SVR following 12 weeks of

therapy. Outcome of short-term treatment was similar to standard treatment in

patients younger than 40 years, as well as in older patients provided that HCV RNA

was <1,000 IU/mL on day 7 and undetectable on day 29. Patients achieving HCV

core antigen (coreAg) levels in plasma <0.2 pg/mL on day 3 had similar sustained

viral response (SVR) rates in both study arms (86% and 84% for 12 vs. 24 week

arms respectively). Patients who never achieved undetectable HCV RNA (n=12),

had significantly higher age, pretreatment viral load, and bod mass index (BMI) as

well as lower interferon concentrations on days 7 and 29. Similarly, obesity (BMI ≥30

kg/m

²

) was significantly associated with lower peg-IFN and ribavirin concentrations

which entailed impaired outcome following 24 weeks of therapy (SVR 62% vs. 89%,

for BMI ≥30 vs. <30; P=0.006). In a multivariate analysis among per-protocol patients

in the 24 week arm, ribavirin and peg-IFN concentrations, as well as baseline HCV

RNA levels were independent predictors of SVR, suggesting that reduced

bioavailability of interferon and ribavirin in obese patients may affect treatment

outcome. Pretreatment plasma levels of Interferon-γ Inducible Protein 10 kDa (IP-10)

predicted the reduction of HCV RNA during day 1-3 (first phase) but not the decline

between days 8-29 (second phase). In addition, a significant association was

identified between expression of intrahepatic IP-10 mRNA and plasma IP-10,

indicating that the liver is likely the primary source of systemic IP-10 in chronic HCV

infection.

Populärvetenskaplig sammanfattning

Kronisk hepatit C virus (HCV)-infektion medför gradvis utveckling av leverskada och ökad risk för levercancer. Genom att behandla med interferon och ribavirin under 24 veckor kan man bota ca 80 % av patienterna infekterade med HCV genotyperna 2 och 3. Om man skulle kunna bota samma andel patienter med kortare behandling skulle biverkningar och kostnader kunna reduceras avsevärt. I en studie vi själva planerat och genomfört vid 31 nordiska kliniker randomiserades 392 patienter till 12 eller 24 veckors behandling med 180 µg pegylerat interferon-α 2a per vecka och 800mg ribavirin per dag. Huvudsyftet var att undersöka om 12 veckors behandling var lika bra som 24. Vi kunde visa att 24 veckors behandling generellt sett trots allt var bättre än 12 (utläkningsfekvens 78 % jämfört med 59 %, P<0,0001) oberoende av leverskada. Tolv veckors behandling var dock likvärdig för patienter yngre än 40 år och även för äldre patienter som svarade så snabbt på behandling att de hade en virusnivå i blod under 1000 IU/ml redan behandlings dag 7. Vi fann också att man med en alternativ metod för att bestämma mängden virus i serum under behandlingen, HCV-coreantigenkvantifiering, kunde identifiera patienter med tillfredsställande behandlingsresultat efter 12 veckors behandling. En tredjedel av patienterna (126 st.) hade HCV coreantigen <0,2 pg/ml på tredje behandlingsdagen och utläkningsfrekvensen hos dessa var 86 % jämfört med 84 %, för 12 respektive 24 veckors behandling. Tolv patienter svarade inte alls på behandling. Dessa patienter var äldre, mer överviktiga och hade mer virus i blodet samt lägre koncentrationer av interferon behandlingsdag 7 och 29. Vi fann att kraftigt överviktiga patienter (body mass index, BMI > 30) hade lägre koncentration av av såväl ribavirin som interferon i blodet och svarade sämre på behandling (Utläkningsgrad 62%

jämfört med 89 %, P=0,006). De viktigaste orsakerna till bristande behandlingssvar

var lägre koncentrationer i blod av ribavirin vecka 12 och interferon dag 29 samt hög

virusnivå i blod före behandling. Mängden av proteinet IP-10 i plasma innan

behandling var relaterat till hur snabbt virusnivån minskade under de första

dagarnas behandling. IP-10 nivåerna i plasma stämde väl överens med nivåerna i

levern vilket antyder att IP-10 bildas i levern.

Abbreviations

ALT Alanine aminotransferase

BMI Body mass index

CV Calculation variability

CXCR3 Chemotactic chemokine receptor 3

DAA Direct-acting antivirals

DNA Deoxyribonucleic acid

EIA Enzyme linked immuno assay

GGT Gammaglutamyl transferase

HAI Histology activity index

HBV Hepatitis B virus

HCV Hepatitis C virus

HCVcoreAg Hepatitis C virus core antigen

HIV Human immunodeficiency virus

HLA Human Leucocyte Antigen

HOMA-IR Homeostatic model assessment-insulin resistance

IFN Interferon

IL28B Interleukin 28 B

ISG Interferon stimulated genes

ITT Intention to treat

IP-10 Interferon-γ inducible protein 10 kDa IU/mL International units per milliliter

IVDU Intravenous drug use

NANBH Non-A, Non-B Hepatitis

NAT Nucleic acid amplification technique

NS Non-structural

OD Optical density

peg-IFN Pegylated Interferon

PP Per protocol

PPT Plasma preparation tube

PCR Polymerase chain reaction

RIBA Recombinant immunblot assay

RNA Ribonucleic acid

RT-PCR Reverse transcription polymerase chain reaction

RVR Rapid virological response

SNP Single nucleotide polymorphism

STD Sexually transmitted disease

SVR Sustained virological response

UTR Untranslated region

VLDL Very low-density Lipoprotein

List of papers

This thesis is based on the following papers, which are referred to in the text by their roman numeral

I Lagging M, Langeland N, Pedersen C, Farkkila M, Buhl MR, Morch K, Dhillon A, Alsio A, Hellstrand K, Westin J, and Norkrans G.

Randomized comparison of 12 or 24 weeks of peginterferon alpha-2a and ribavirin in chronic hepatitis C virus genotype 2/3 infection. Hepatology. 2008 Jun;47(6):1837-45.

II Alsio A, Jannesson A, Langeland N, Pedersen C, Farkkila M, Buhl MR, Morch K, Westin J, Hellstrand K, Norkrans G and LaggingM.

Early quantification of HCV core antigen may help to determine the duration of therapy for chronic genotype 2/3 HCV infection. In manuscript.

III Askarieh G, Alsio A, Pugnale P, Negro F, Ferrari C, Neumann AU, PawlotskyJ-M, SchalmS W, ZeuzemS, NorkransG, Westin J, SöderholmJ, HellstrandK and

LaggingM.

Systemic and intrahepatic interferon-gamma-inducible protein 10 kDa predicts the first-phase decline in hepatitis C virus RNA and overall viral response to therapy in chronic hepatitis C. Hepatology. 2010 May;51(5):1523-30.

IV Alsio A, Christensen PB, Farkkila M, Langeland N, Buhl MR, Pedersen C, Morch K, HaagmansB, WestinJ, HellstrandK, Norkrans G, and LaggingM .

Nonresponder patients with hepatitis C virus genotype 2/3 infection: A question of low systemic interferon concentrations? Clin Infect Dis. 2010 Feb 15;50(4):e22-5.

V

Alsio A, RembeckK, AskariehG, ChristensenPB, Farkkila M, LangelandN, BuhlMR, PedersenC, Morch K, HaagmansB, Nasic S, WestinJ, HellstrandK, NorkransG, and LaggingM.

Impact of obesity on the bioavailability of peginterferon-α2a and ribavirin and treatment outcome for chronic hepatitis C genotype 2 or 3. In manuscript.

Papers I, III and IV were reprinted with permission from the publishers.

Introduction

History

Around 400 BC, Hippocrates dispelled the belief that jaundice was a result of divine punishment and suggested that environmental factors caused an imbalance in body humours resulting in yellow skin discoloration, which he termed “icterus”. He associated this with the liver and in addition named hardening of the liver ”kirrhos”.

Since the 17

^th

century, there are multiple reports of outbreaks of jaundice in Europe, most frequently in conjunction with war. The epidemic character of these outbreaks suggested an infectious etiology and as early as 1908, McDonald made speculative assumptions that fulminant hepatitis may result from one or more unknown viral infections (1).

Two clinical types of hepatitis were distinguished in 1967, one following fecal-oral exposure and the other, following percutaneous blood exposure, had a longer incubation time (2). The identification of the hepatitis B virus (3) was followed by the discovery of the hepatitis A virus (4) and the subsequent development of diagnostic tools for both viruses. Retrospective analysis, of stored sera from earlier transfusion studies, revealed that neither of these viruses accounted for the majority of cases of transfusion-associated hepatitis. Accordingly, this condition was named non-A, non- B hepatitis (NANBH) (5). Additionally it was noted that posttransfusional NANBH could be transmitted to chimpanzees (6, 7) through inoculation of infectious human sera indicating a small transmissible agent, likely of viral origin.

Earlier suggestions of a small lipid enveloped causative agent similar to flavivirus was confirmed in 1989 by Choo et al. when the Hepatitis C Virus (HCV) was cloned and shown to belong in the flaviviridae family (8). Kuo et al. developed an assay to detect HCV antibodies (9) and it was later demonstrated that HCV accounted for 90% of the NANBH cases (10). General blood donor screening became mandatory in 1990 in the US and as on January 1, 1992 in Sweden.

In 2005, the complete replication cycle of HCV was performed in vitro using the

replicon system based on HCV genotype 1b by Lindenbach et al. (11), and shortly

thereafter Wakita et al. (12) reported production of infectious HCV particles in tissue culture, that was transmissible to chimpanzees, from a cloned HCV genotype 2 strain originally isolated from a Japanese patient with fulminant hepatitis. Both of these landmark achievements have made the development of direct-acting antivirals (DAA) feasible, and indeed the first DAAs have recently been registered for treatment of HCV genotype 1 infection (13-17).

Virology

Hepatitis C virus is a spherical, enveloped positive single stranded RNA virus belonging to the Flaviviridae family with a genome consisting of approximately 9,100- 9,400 nucleotides depending on the HCV genotype (18). It has a long open reading frame coding for a polyprotein of approximately 3000 amino acids, flanked by two untranslated (UTR) regions at the 5’- and 3’-ends, of which the 5’ UTR is the most conservative and has been used for the development of sensitive HCV RNA assays.

Ď

hypervariable region capsid envelope

protein protease/

helicase RNA-

dependent RNA polymerase c22

5’Ď

core E1 E2 NS

2 NS

3 33c

NS4 c-100

NS5

3’Ď

Hepatitis C Virus

The polyprotein is cleaved by both host and viral proteases, yielding 10 known proteins: three structural proteins, the core protein and the two envelope proteins (E1, E2) responsible for receptor binding and entry of HCV into target cells (19), p7 a short membrane peptide postulated to be involved in viral assembly (20) and the non-structural proteins (NS2, NS3, NS4a, NS4b, NS5a and NS5b), involved in viral replication and assembly. Characterizations of the three-dimensional structure of NS5b polymerase and NS3-NS4a protease have been crucial for the development of drugs directed against these enzymes. The E1 and E2 regions demonstrate the highest mutation rates, postulated to be secondary to immunoselective pressure resulting from neutralizing antibodies against these regions. This gives rise to numerous quasispecies, possibly allowing for escape from host immune defenses (21).

Isolated HCV from infectious sera typically is associated with low-density lipoprotein (22), possibly providing another mechanism of evasion from host humoral responses (23).

Epidemiology and routes of transmission

HCV is endemic in most parts of world and the WHO estimates that 2.35% of all

humans are chronically infected (24), though population-based studies are scarce

and most studies are cross-sectional in selected populations. The prevalence of

chronic infection varies in different regions of the world with the highest reported

seroprevalence in Egypt (22%)(25). In the USA, the seroprevalence of HCV

antibodies is estimated to be 1.8% (26).

Figure 2. Map displaying world-wide HCV-prevalence.

Source: www.who.int

In Sweden 48,695 cases have been reported from 1990 until the end of 2010. The estimated seroprevalence is relatively low (<0.5%) although this estimate primarily is based on studies of cohorts with expected lower seroprevalence (27) (28).

Seven genotypes have been identified, named in order of discovery, six of which have major epidemiological implications (29, 30). The relative prevalence of genotypes 1, 2 and 3 vary between geographic regions although they have a worldwide distribution. In contrast, genotype 4 is predominantly prevalent in North Africa and the Middle East (31), while genotypes 5 and 6 are found almost exclusively in South Africa and Hong Kong, respectively (32, 33).

The most frequent genotype in the Swedish population is genotype 1 (41%), followed by genotypes 3 (31%) and 2 (17%). The relative frequency of genotype 3 appears to be increasing while 1b is decreasing over time (34), possibly reflecting a shift in

Hepatitis C – Prevalence !

mode of transmission away from contaminated blood products prior to universal screening in 1992 towards an increasing proportion following intravenous drug use (IVDU). Currently, IVDU is the most common mode of transmission in industrialized countries, and it is commonly believed that HCV infection is acquired rapidly after the initiation of injection drug use with 50-80% of new injectors becoming seropositive for HCV within 6 to 12 months (35). The reported prevalence of HCV infection among drug users in Europe is 60-90 % (36, 37).

Unsafe health care procedures, including exposure to contaminated blood products, was the most frequent mode of transmission prior to implementation of universal blood donor screening in industrialized countries. This route of transmission remains responsible for the majority of transmitted cases on a global perspective, particularly in parts of the world where access to screening of blood products is limited (38).

Epidemiological studies on the risk of sexual transmission are inconclusive. High- risk sexual behavior and high prevalence of other sexually transmitted diseases (STD) have been associated with a higher prevalence of hepatitis C virus infection (26), while other studies have failed to confirm this (39). A minority of HCV cases are transmitted through household contacts (39) or perinatal transmission (40, 41), and the estimated risk of newborns to be infected at birth from an infected mother is estimated to be 5% (42).

Natural history

Results from studies of the natural course of hepatitis C vary depending on the

structure of the data collected. Retrospective studies tend to overestimate serious

outcomes as a result of preferential selection of individuals with chronic liver disease

and underrepresentation of individuals with spontaneous clearance of virus. On the

other hand, prospective studies that allow for the recognition of spontaneous

resolution require identification of all cases on the time of exposure, which is

uncommon because of the general lack of symptoms in association with acute HCV

infection. An alternative method commonly used is the identification of outbreaks of

hepatitis C from single-source exposures in the past. These studies, however, may tend to overestimate the rates of spontaneous clearance because of the demographics of the patients included, e.g. healthy young females likely exposed to low concentrations of HCV in conjunction with inadequately prepared Rh immunization.

The frequency of spontaneous recovery was reported to be 15-29% in studies of HCV infection acquired through blood transfusion (10) or intravenous drug abuse (43). On the other hand, studies of single-source outbreaks have demonstrated higher rates of spontaneous clearance in infected children and women (44, 45).

HCV RNA can often be detected within a week following exposure (46, 47), although there is commonly a window period of approximately 7-8 weeks before antibodies against HCV can be detected (47). In the majority of patients, HCV infection is established despite the induction of a humoral immune response. However, Pestka et al. demonstrated that higher titers of neutralizing antibodies with broader cross- reactivity are produced in an early phase of infection in patients later clearing their HCV infection as opposed to those who go on to develop chronic infection.(48).

Additionally clearance of HCV infection is associated with a strong multispecific CD4 T-cell response (49-51). Similarly, certain human leucocyte antigen (HLA) genotypes as well as single nucleotide polymorphisms (SNPs) in proximity to IL28B correlate with spontaneous resolution of HCV infection (52-54).

During the acute phase of infection, only a minority of infected subjects develops symptoms (such as jaundice, dark urine, pale stools, nausea and muscular tenderness), although among symptomatic individuals, spontaneous clearance is more common. (55, 56). Similarly, the majority of patients with chronic HCV infection experience no or only mild symptoms but still run the risk of developing severe liver disease as a consequence of progressive liver fibrosis.

Approximately 40-80% of patients with chronic HCV infection develop liver steatosis,

which is characterized by the accumulation fat within hepatocytes (57). Steatosis in

HCV infected patients has been associated with metabolic factors such as

(58). Among HCV genotype 3 infected patients, steatosis is more frequent, more severe, less dependent on metabolic factors, as well as associated with hypocholesterolemia and higher HCV RNA levels (59, 60). In HCV genotype 3 infected patients cholesterol levels tend to normalize and steatosis diminishes considerably following viral eradication after antiviral therapy as opposed to non- genotype 3 patients where only minor histologic amelioration occurs after successful treatment (61). Thus, two different types of steatosis seem to exist in patients with chronic HCV infection although they may overlap, one primarily related to HCV genotype 3 infection and the other resembling non-alcoholic fatty liver disease, mainly related to metabolic factors. (61). The HCV core protein has been postulated to play a crucial role in the accumulation of intracellular lipid droplets (62) and genotype 3 core protein expression in mouse models have resulted in more pronounced fat accumulation in comparison with expression of HCV genotype 1 core protein (63). Part of the steatogenic effect is thought to be mediated through reduced activity of microsomal triglyceride transfer protein (MTP), a key enzyme involved in VLDL assembly and secretion, resulting in “entrapment” of fat in the liver. Mirandola et al. demonstrated a significant inverse association between hepatic MTP gene expression and the degree of steatosis, irrespective of genotype in HCV infected patients (64). This decreased MTP gene expression was associated with insulin resistance in non-genotype 3 infected patients in contrast to HCV RNA levels in genotype 3 patients.

Steatosis has been significantly associated with accelerated progression of fibrosis,

irrespective of genotype in some studies (65, 66) whereas predominately in

genotype 3 patients in others (67, 68). Both the presence of steatosis and higher

BMI are associated with insulin resistance, which promotes fibrosis progression in

the liver (69). As BMI, insulin resistance, and steatosis grade are closely inter-

related, it has been difficult to distinguish which factors independently contribute to

the progression of fibrosis. A direct viral impact on insulin resistance, mediated by

the core protein, has been suggested in HCV genotype 1 infection (70). Hepatic

stellate cells responsible for extracellular deposition of fibrinous tissue have insulin

receptors, and connective tissue growth factor was found in increased amounts

following in vitro exposure of stellate cells to insulin (71). In addition a meta-analysis

demonstrated that chronic HCV infection is significantly associated with an increased risk of diabetes mellitus type II (72).

Fibrotic encapsulation of damaged tissue occurs in all wound-healing processes. In the liver, this is believed to be a response to prolonged injury secondary to either viral induced inflammation and steatosis, excess alcohol consumption, or metabolic disturbances. Potential associations with disease progression have been evaluated in several epidemiological studies, and the reported significant factors include male gender (44, 45, 73), age at infection (73, 74), hypogammaglobulinemia (75), coinfection with HIV, HBV or schistosomiasis (76-78), alcohol consumption (79, 80), smoking (81, 82), race (83), and coexisting hemochromatosis (84). There is no convincing evidence of disease progression correlating with HCV viral load or genotype (85), although recent data from the United States Department of Veterans Affairs suggests an increased mortality associated with HCV genotype 3 (86).

The frequency of cirrhosis development varies in different cohorts. In a reported meta-analysis (87), the estimated prevalence of cirrhosis 20 years after infection was 16-18% for pure retrospective studies, 7% for studies of single-source outbreaks, 18% for studies in clinical settings and 7% for studies conducted in non-clinical settings. Several studies indicate a more rapid disease progression among older patients (73, 87).

Strong epidemiological data support an association between hepatocellular carcinoma (HCC) and HCV (88), but the underlying mechanism behind cancer transformation remains unclear. Because HCC is more common among cirrhotic patients, with a reported annual incidence of 1-4% in a cirrhotic cohort (89), it has been postulated that signals from chronic inflammation and oxidative stress contribute to cancer development. In addition, the HCV core protein as well as the non-structural proteins NS3 and NS5a have been reported to influence host cell proliferation through several mechanisms, (reviewed in (90).

In Sweden there were 54 reported cases of HCC among HCV infected individuals in

2006 (91) constituting approximately 10% of all HCC that year. It was also noted that

the annual HCC incidence in Sweden is slowly declining as opposed to other

countries, and that the relative proportion of HCV-associated cases of HCC is increasing.

Several immune associated disorders are more frequent in the chronically HCV infected population with mixed cryoglobulinemia, characterized by the deposition of immune complexes in small vessels leading to vasculitis, being the most common (92). Various forms of immune complex-associated glomerulonephritis are associated with HCV (93). In addition, epidemiological data suggest that HCV infected patients have an increased risk of developing multiple myeloma as well as Non-Hodgkin lymphoma (94, 95)

Diagnostic methods

Antibody detection

Assays for the detection of specific antibodies against HCV are primarily used for screening of large low-risk populations, as they are relatively inexpensive and easy to use, and can be fully automated. In enzyme immune assays (EIAs), recombinant antigens based on HCV core, NS3, NS4 and NS5 proteins, are used to capture circulating antibodies (96). Anti-antibodies labeled with an enzyme are then added and subsequently, a substrate which converts to a colored compound in presence of the labeled antibodies. The amount of antibodies detected is proportional to the optical density (OD) ratio (sample OD / control OD)(97). EIAs have high sensitivity and specificity but do not discriminate persistent infection from resolved, and can be false negative in spite of the presence of viremia during the early acute phase of infection and in immunocompromised individuals.

Recombinant immunoblot assay (RIBA) may be used to confirm anti-HCV reactivity

and is based on capture of antibodies reactive to the above mentioned recombinant

HCV antigens separated as bands on a cellulose strip (98). Reactivity to 2 or more

bands is considered to confirm the presence of antibodies against HCV. Reactivity to

one antigen band is considered inconclusive and mandates further investigation with

repeat sampling and/or analysis of HCV RNA, which is rapidly replacing RIBA for the

confirmation of anti-HCV reactivity in screening EIAs as the presence of HCV RNA indicates ongoing viremia.

Viral detection and quantification

Detection of viremia can be achieved directly by nucleic acid amplification techniques (NATs) to detect and/or quantify HCV RNA (99) or indirectly by measurement of the HCV core antigen (coreAg) (100). Assessment of HCV RNA is valuable in order to diagnose HCV viremia and to monitor response to antiviral therapy, while HCV coreAg has not been fully evaluated in this context as of yet but could potentially do the same.

Previously used methods to detect HCV RNA, including branched DNA assays, are gradually being abandoned in favor of real time reverse transcriptase (RT)-PCR, as the level of detection of the latter assay is considerably lower. One commonly used commercially available (RT)-PCR (Roche COBAS TaqMan) has a lower limit of quantification of 15 IU/mL with a broad dynamic range of quantification up to 7-8 log

10

in addition to being fully automated with high specificity and sensibility (97, 101). The quantification process includes RNA capture, reversed transcription and amplification of the target sequence. Hybridization of the probe to its complementary target on the amplification sequence leads to fluorescence emission and detection.

The larger the HCV RNA level in the original sample, the earlier the fluorescence signal reaches the threshold at which it is detected.

Assays for the amplification of HCV RNA are more expensive in comparison to the

assessment of HCV coreAg (102). Additionally many smaller microbiology

laboratories lack the instrumentation needed for HCV RNA quantification, but are

able to quantify HCV coreAg. HCV coreAg assessment allows quantification of free

as well as antibody-bound core particles through the addition of an immune complex

dissociating reaction. This method is useful for confirming HCV viremia in specimens

reactive in screening EIAs and has been implemented for this purpose in many

Swedish laboratories, e.g. Växjö Skövde (personal communication).

Genotype determination

There are 7 identified genotypes of HCV, 6 of which have major epidemiological significance and may differ by as much as 33% in sequence (33). More closely related isolates within genotypes are classified as subtypes, and subtype analysis is rapidly gaining importance, as genotype 1b strains are significantly less likely to develop resistance to the recently introduced protease inhibitors than 1a strains (103, 104).

There are considerable differences in the response to current anti-HCV viral therapy according to HCV genotype, with a markedly better response to ribavirin and interferon in the genotype 2- or 3-infected population, but concerning the recently introduced protease inhibitors the efficacy in genotype 2 infected patients is modest and absent in genotype 3 infected patients (105). Hence genotype determination has a major impact on the clinical management of patients.

Sequence analysis of part of the viral genome after PCR amplification and subsequent phylogenetic analysis is the reference method for HCV genotype determination(106). When using the relatively labor-intensive and costly population sequencing method, only viral variants representing at least 20-25% of the circulating viral population can be identified. A signature sequence identified by reversed hybridization of PCR amplificates to a probe is an alternative method with higher sensitivity to detect viral variants present in lower proportion (107). PCR methods using genotype-specific primers are also available (108).

Histopathological assessment

In order to evaluate the natural course of viral hepatitis and to select suitable patients for treatment, it became necessary to standardize the histopathological evaluation.

The histopathological assessment of liver biopsies from patients with chronic HCV

infection focuses primarily on the evaluation of the necroinflammatory activity in the

various compartments of the liver lobule and the prevalence, extent, and distribution

of fibrosis. The prevalence and degree of hepatic steatosis and iron deposition as

well as the occurrence of bile duct lesions are other important histopathological

characteristics.

One of the first classifications of chronic hepatitis introduced distinguished between chronic active or chronic persistent hepatitis regardless of underlying etiology based on prevalence or absence of pronounced periportal inflammation or “piece-meal necrosis”. This classification method was subsequently replaced by more detailed pseudonumerical scoring systems. One such commonly used method was the

“histology activity index” (HAI) presented by Knodell et al. (109). This scoring system was revised in 1995 when Ishak et al. attempted to establish consensus among leading pathologists at the time (110). In this “Ishak” system, which is widely accepted and is the scoring system used throughout this thesis, the various aspects of inflammation (interface hepatitis, confluent necrosis, focal lobular inflammation, and portal inflammation) are separately graded on scale from 0 to 4, whereas fibrosis is staged from 0 to 6.

Treatment

The goal of treatment is viral eradication and hence subsequent hindrance of fibrosis progression in order to reduce the risk of end-stage liver disease and HCC. Outcome is accessed 24 weeks after the end of treatment, and undetectable HCV RNA at this time-point is defined as sustained virological response (SVR). Very high rates (exceeding 95%) of the long-term persistence of undetectable HCV RNA in patients having achieved SVR have been reported (111). In patients achieving viral clearance, histology generally improves with partial or complete regression of fibrosis and inflammation (112).

The first report on interferon treatment for non-A, non-B hepatitis came in 1986 where a minority of patients achieved persistent normalization of transaminases (113). The addition of ribavirin to interferon therapy led to improvement of eradication rates (114), and further improved efficacy and amelioration of side effects was achieved by the introduction of pegylated interferon (peg-IFN), with an improved pharmacodynamic profile (115).

Until recently, the recommended treatment regimen was a combination of peg-IFN

and weight-based ribavirin for 48 weeks for HCV genotype 1, and 24 weeks for

genotypes 2 and 3 with a lower fixed 800 mg daily dose of ribavirin (116).

Approximately 40-50% of genotype 1 infected patients and 80% of genotype 2- and 3-infected patients achieved SVR with these regimens (116). Treatment experience of chronic HCV infection with genotypes 4-6 remains limited and the current recommended treatment duration for these genotypes is 48 weeks.

Several treatment trials have evaluated the feasibility of shortened, response-guided treatment courses. Among genotype 1 infected patients, 24-week regimens are reportedly non-inferior in comparison to 48-week regimes in patients with low baseline viral load, discriminating levels between 400,000 and 800,000 IU/mL, achieving a rapid virological response (RVR), defined as undetectable HCV RNA at week 4 of therapy. Concerning patients with RVR and higher baseline viral load, the results of 24-week regimens are inconclusive (117-119).

Shorter treatment courses in chronic HCV genotype 2 and 3 infected patients achieving RVR have yielded discordant results (120-123). These inconsistencies may in part be secondary to differences in the demographics of enrolled patients, especially regarding age, BMI, and fibrosis stage.

Predictors of therapeutic response include pretreatment activation of hepatic interferon stimulated genes (ISGs) (124, 125) including IP-10, IL28B single-nucleotide polymorphisms (SNPs) (126), HCV genotype, stage of fibrosis, baseline HCV-RNA levels, BMI, age, insulin resistance, levels of ALT and GGT and co-infection with HBV or HIV reviewed in (127, 128).

IL28B single nucleotide polymorphisms (SNPs)

Recently, several genome-wide association studies have revealed that single

nucleotide polymorphisms (SNPs) in the q13 region of chromosome 19, in close

proximity to three genes (IL28A, IL28B, and IL29) encoding cytokines of the IFN-λ

(i.e. type III IFN) family, predict SVR following peg-IFN/ribavirin therapy among

patients infected with HCV genotype 1 (129-132), and explain much of the racial

differences in response (129). In the setting of therapeutic intervention for HCV

genotype 2 or 3, uncertainty prevails regarding the benefit of favorable IL28B allele carriage (133-136).

IP-10

Interferon-gamma inducible protein 10 kDa (IP-10 or CXCL10) is a chemotactic CXC

chemokine of 77 amino acids in its mature form (137, 138). IP-10 targets the CXCR3

receptor but, unlike other CXC chemokines, lacks chemotactic activity for neutrophils

and instead attracts T lymphocytes, NK cells, and monocytes to sites of infection

(138-140). IP-10 is produced by a variety of cells, including hepatocytes, and levels of

IP-10 at onset of therapy are reportedly elevated in patients infected with HCV of

genotypes 1 or 4 who do not achieve SVR (141). Two studies report that pretreatment

levels of systemic IP-10 and IL28B-related SNPs are independent predictors of

response to peginterferon/ribavirin therapy, and concomitant assessment of both

augments the prediction of the first phase decline in HCV RNA and the final

therapeutic outcome among HCV genotype 1 infected patients (142, 143)

.

The effect

of plasma levels of IP-10 in genotypes 2 and 3 remains to be elucidated.

Aims

The overall aim of this thesis was to evaluate factors that may affect the outcome of therapy with 180 µg peginterferon α-2a once weekly in combination with 800 mg ribavirin in a cohort of patients infected with Hepatitis C virus genotype 2 or 3.

In the above setting, the specific aims were:

To define the optimal duration of treatment and to identify patients potentially suitable for 12 weeks of therapy.

To evaluate the utility of plasma HCV core antigen quantification for the identification of suitable candidates for short-term therapy.

To evaluate the impact of systemic and intrahepatic IP-10 on therapeutic response.

To identify independent risk factors for non-responsiveness to therapy.

To identify potential confounding factors contributing to the poorer

response noted among obese patients, with special emphasis on the

interferon and ribavirin concentrations achieved.

Methods

Study populations

The work in this thesis is based primarily on analysis of the NORDynamIC study cohort (n=382; infected with HCV genotype 2/3). Paper III also includes patients from the DITTO study population (n=270; infected with HCV genotype 1-5).

The NORDynamIC study

This was a phase III, open-label, randomized, multicenter, investigator-initiated trial conducted by the NORDynamIC study group at 31 centers in Denmark, Finland, Norway, and Sweden. The primary endpoint was a comparison of SVR rates after 12 or 24 weeks of combination therapy. The sample size was calculated in order to be able to detect a difference of ≥12% in SVR rates between treatment arms with a power of at least 80%. Written informed consent was obtained from each participating patient. Ethics committees in each participating country approved the study. The trial was registered at the National Institutes of Health trial registry (ClinicalTrials.gov identifier: NCT00143000).

Between February 2004 and November 2005, 392 patients with chronic HCV

genotype 2/3 infection were screened for inclusion (Fig.3). Three hundred eighty-two

enrolled patients met all inclusion criteria and constituted the intention-to-treat (ITT)

population (Fig. 1). All patients were adults (age ≥ 18 years), had compensated liver

disease, were treatment naive for hepatitis C, were seronegative for hepatitis B

surface antigen and for antibodies to human immunodeficiency virus, and fulfilled the

following additional inclusion criteria: a positive test for anti-HCV antibody, infection

with HCV genotypes 2 and/or 3 but not genotypes 1, 4, 5, or 6, and HCV RNA >600

IU/mL (quantified with the Roche Amplicor HCV monitor, version 2.0) within 6

months of treatment initiation. A liver biopsy consistent with chronic hepatitis C within 24 months of entry was also required.

Figure 3. Schedule of the NORDynamIC study cohort.

At randomization, the study groups were stratified for age, genotype, and presence of cirrhosis in the liver biopsy as judged by the local pathologist. Three hundred three patients (79%) received at least 80% of the target dose of peginterferon and of ribavirin for at least 80% of the target treatment duration and were included in the per-protocol (PP) analysis.

Fifty-eight patients prematurely terminated treatment (12 in the 12-week arm vs. 46 in the 24-week arm), chiefly because of adverse events in both arms

.

In the 24-week arm, 39 of 46 premature terminations of therapy occurred between study weeks 13 and 24. However, these terminations were primarily due to adverse events, and none were due to treatment failure because no HCV RNA plasma samples were analyzed until after the 24-week post treatment follow-up period. Twenty-six patients

10 Failed to meet the inclusion criteria, met at least one exclusion criteria, or

was otherwise unable to participate

12 (6%) Terminated treatment before week 12

179 (92%) had HCV-RNA plasma sample available 24 weeks after completion of therapy

182 (94%) Completed 12 weeks of therapy once weekly + 800 mg ribavirin daily for 12 weeks

7 (4%) Terminated treatment before week 12

39 (21%) Terminated treatment between week 13 and 24

177 (94%) had HCV-RNA plasma sample available 24 weeks after completion of therapy

142 (76%) Completed 24 weeks of therapy 181 (96%) Completed 12 weeks of therapy once weekly + 800 mg ribavirin daily for 24 weeks 382 Randomly assigned to treatment

(included in intention-to-treat analysis) 392 Patients were screened

Patients lacking a 24 week post-treatment plasma sample were censored as treatment failures;

15 (8%) in the 12 week arm and 11 (6%) in the 24 week arm

(15 in the 12-week arm and 11 in the 24-week arm) failed to have a plasma sample drawn 24 weeks after completion of therapy; these latter patients were censored as treatment failures. These censored patients were classified as nonresponse or relapse on the basis of whether or not HCV RNA was detectable in the end-of- treatment plasma.

Treatment

At study entry, patients were randomized to either 12 or 24 weeks of therapy with 180 µg of peginterferon α-2a once weekly, with the first dose administered by a study nurse and subsequent dosing monitored using a patient diary (Pegasys, F.

Hoffmann-La Roche, Basel, Switzerland) and ribavirin twice daily (Copegus, F.

Hoffmann-La Roche) at a total daily dose of 800 mg daily. The result of the randomization was not disclosed to patients or treating physicians until after 12 weeks of therapy.

Classification of Treatment Outcome

Patients were classified as achieving SVR if plasma HCV RNA was undetectable (i.e., ≤15 IU/mL) 24 weeks after completion of therapy, as having relapsed if plasma HCV RNA was undetectable at the end of treatment but detectable 24 weeks after completion of therapy, and as being non- responders if plasma HCV RNA was detectable at the end of treatment. Patients were classified as having an RVR if HCV RNA was undetectable on treatment day 29.

HCV RNA Quantification

Plasma was obtained with PPT tubes, and HCV RNA was determined by reverse-

transcription polymerase chain reaction of plasma with the Cobas AmpliPrep/COBAS

TaqMan HCV test (Roche Diagnostics, Branchburg, NJ), which quantifies HCV RNA

with a limit of detection of ≤15 IU/mL. HCV RNA quantification was performed on

days 0, 3, 7, 8, and 29 and in weeks 8, 12, and 24 (for those receiving 24 weeks of

therapy) and 24 weeks after completion of therapy. All samples were frozen (-70°C)

and subsequently analyzed at the central laboratory (Department of Virology,

Gothenburg, Sweden).

Genotyping

Genotyping of HCV was initially performed at the local centers and subsequently confirmed at the central laboratory (Department of Virology, Sahlgrenska University Hospital, Gothenburg, Sweden) with a TaqMan primer-specific reverse- transcription polymerase chain reaction method and, if necessary, with INNO-LiPA HCV II (Innogenetics N.V., Ghent, Belgium). Two patients had dual infections with genotypes 2 and 3.

Liver biopsies

Liver biopsies were obtained from all patients within 24 months prior to study entry.

Only biopsies with a length exceeding 1.5 cm and containing more than 6 portal tracts were evaluated. In total, liver biopsies from 354 patients were retrieved and scored. For each biopsy, a haematoxylin-eosin stain and a Sirius Red stain were centrally staged and graded by two independent observers experienced in pseudo- numerical scoring of liver biopsies with a documented acceptable interobserver variability (144). The evaluation was performed in a blinded fashion according to the Ishak protocol(110). Equivocal issues were debated after the independent scores were noted, and a consensus score was obtained. In addition, steatosis was graded as follows: absent = 0, less than 30% of hepatocytes involved = 1, 30%-70% of hepatocytes involved = 2, and more than 70% of hepatocytes involved = 3.

Hepatitis C virus core antigen analysis

Hepatitis C virus core antigen (HCV coreAg, Architect HCVAg Abbott, Germany) was determined by a fully automated chemiluminescent microparticle immunoassay as previously reported (102). Patient samples were stored at -70°C and subsequently analyzed at a central laboratory (Department of Virology, Sahlgrenska University Hospital, Gothenburg, Sweden). Plasma samples from 340 patients were available for Hepatitis C core antigen analysis at day 0, 341 at day 3, and 342 from day 7.

Plasma samples from 22 healthy blood donors negative for antibodies against HCV

were used as controls. Anti-HCV screening preceding HCV coreAg assessment in

the same analytic instrument prior to analysis of HCV coreAg has been noted to

result in a substantial number of false positive HCV coreAg reactions (145), likely secondary to carry-over interference from microparticles coated with HCV coreAg present in previous kits utilized for the detection of antibodies against HCV.

Therefore, all analyses were performed after a thorough cleaning procedure of the analytic instrument. Samples with HCV coreAg levels <0.06 pg/mL were considered non-reactive and those with ≥0.2 pg/mL were considered reactive (102) Plasma samples with initial HCV coreAg levels between 0.06 and 0.2 pg/mL were considered grey-zone values and were retested in duplicate. If one or both of these repeat evaluations were ≥0.06 pg/mL, the sample was considered reactive and the first of the three values obtained was used in the subsequent analyses. Grey-zone levels were noted in 8 of 340 samples on day 0, 65 of 341 on day 3 and 74 of 342 on day 7, and of these samples 7 of 8 on day 0, 52 of 65 on day 3 and 63 of 74 on day 7 were considered reactive after re-analysis. The calculation variability (CV) of the assay was 21.5-23.4%.

Interferon alfa-2a drug concentration

Plasma concentration of interferon α-2a was measured at day 3, 7 (i.e. immediately before the second dose of peginterferon α-2a) and 29. All samples were collected using PPT-tubes, frozen (-70°C), and subsequently analyzed at a central laboratory.

Quantification was performed according the manufacturer’s instructions (AMS Biotechnology, Oxford, UK; lower limit of detection, 400 pg/mL). Plasma samples were available from 361 patients on day 3, 357 on day 7, and 359 on day 29.

Antibodies to IFN-alpha

Serum-antibodies to IFN-alpha were determined using quantitative sandwich enzyme-linked immunosorbent assay (Bender MedSystems Diagnostics, Aachen, Germany) according the manufacturer’s instructions.

Ribavirin concentration

Plasma ribavirin concentrations were measured at day 29 and at week 12 by use of

solid-phase extraction and high-performance liquid chromatography (Merck-Hitachi,

Tokyo, Japan) according the manufacturers instructions.

Body mass index

Body mass index (BMI) was calculated as weight in kilograms divided by the square of height in meters, and could be calculated for 300 of 303 patients included in the per protocol analysis.

Homeostatic model assessment-insulin resistance (HOMA-IR)

Baseline fasting glucose (mmol/L) was measured locally, at the time of sampling, whereas fasting serum insulin (mU/L, Architect Insulin, Abbott, Abbott Park, IL) was analyzed retrospectively on frozen samples at the central laboratory. HOMA-IR was calculated using the formula: (Glucose x Insulin) / 22.5

IP-10 Quantification in Plasma

Quantification of plasma-IP-10 was performed using Quantikine (R&D Systems, Minneapolis, MN), a solid-phase enzyme-linked immuno-sorbent (ELISA) assay, on plasma samples obtained during the week prior to the start of therapy. All samples were stored at -70°C until assayed.

The DITTO study

In total, 270 patients (180 men and 90 women) were recruited in a phase III, open- label, randomized, multicenter trial conducted by the DITTO-HCV (Dynamically Individualized Treatment of Hepatitis C Infection and Correlates of Viral/Host Dynamics) study group at nine centers in France, Germany, Greece, Israel, Italy, the Netherlands, Spain, Sweden, and Switzerland, between February 2001 and November 2003, as previously reported (146). All patients were adults, had compensated liver disease, were treatment-naive for hepatitis C, and fulfilled the following inclusion criteria: a positive test for anti-HCV antibody, an HCV RNA level

>1000 IU/ mL, and two serum alanine aminotransferase values above the upper limit

of normal within 6 months of treatment initiation. All patients in the DITTO-HCV trial

were initially treated for 6 weeks with 180 µg peginterferon α-2a administered

subcutaneously once weekly (Pegasys; F. Hoffmann-La Roche, Basel, Switzerland)

and ribavirin orally twice daily (Copegus; F. Hoffmann-La Roche) at a total daily dose

of 1000 mg for patients weighing less than 75 kg and 1200 mg daily for those patients above 75 kg. After 6 weeks of therapy. Half of the patients were randomized based on their viral kinetic classification to receive individualized therapy or to continue on standard combination therapy for a total of 48 weeks. Thus, only reductions of HCV RNA during these first 6 weeks, when all patients received the same treatment, were included in the analyses in paper III. The study was approved by ethical committees, and conformed to the guidelines of the 1975 Declaration of Helsinki. Informed consent was obtained from each patient included in this study.

A total of 264 patients had pre-treatment plasma available for IP-10 analysis, and 73 of these patients had liver biopsies from which RNA could be extracted for further evaluation.

Genotyping

The HCV genotype was determined using the Inno-LiPA HCV II assay (Innogenetics NV, Ghent, Belgium).

HCV RNA Quantification

HCV RNA was quantified by reverse transcription polymerase chain reaction (RT- PCR) using Cobas Amplicor HCV Monitor version 2.0 (Roche Diagnostics, Branchburg, NJ), and quantified on treatment days 0, 1, 4, 7, 8, 15, 22,and 29, at the end of treatment, as well as 24 weeks after the completion of treatment.

Classification of Treatment Outcome.

Patients were classified as having achieved a rapid virological response (RVR) if HCV RNA was undetectable (<50 IU/mL in the DITTO-HCV trial) in plasma on treatment day 29, and were classified as having an SVR if HCV RNA was undetectable in plasma 24 weeks after the completion of therapy.

Liver biopsies

Liver biopsies were obtained from all patients within 12 months prior to inclusion in

the study, and liver biopsy samples were processed for both histological evaluation

(≥1.5 cm) and for RNA analysis (≥1 cm). The biopsy material for RNA analysis was

immediately immersed in RNAlater (Ambion, AMS Technology, Cambridgeshire, UK)

and stored at -70°C until assayed. In total, RNA from 72 liver biopsies could be retrieved and evaluated.

Histological Evaluation of Liver Biopsies

Only biopsies with a length exceeding 1.5 cm and containing more than six portal tracts were evaluated. In total, liver biopsies from 228 infected patients were retrieved and evaluated. For each biopsy, a haematoxylin-eosin stain and a Sirius Red stain were centrally staged and graded by two independent observers experienced in pseudo-numerical scoring of liver biopsies in a blinded fashion according to the Ishak protocol (110). Equivocal issues were debated after the independent scores were noted, and a consensus score was obtained. In addition, steatosis was graded as follows: absent = 0, less than 30% of hepatocytes involved

=1, 30%-70% of hepatocytes involved = 2, and >70% of hepatocytes involved = 3.

IP-10 mRNA Quantification in Liver biopsies

Total RNA was isolated from liver biopsies using the RNeasyMini Kit (Qiagen, Hilden, Germany) and subsequently treated with deoxyribonuclease I. RNA integrity was assessed using RNA 6000 nanochips with an Agilent 2100 Bioanalyzer. First- strand complementary DNA was synthesized from 500 ng purified RNA using the SuperScript II Ribonuclease H (-) reverse transcriptase (Invitrogen, Carlsbad, CA) and random hexadeoxynucleotides. For real-time PCR, the Human SYBR Green QuantiTect Primer Assay for IP-10 (CXCL10, cat. no. QT01003065) was used (Qiagen). Primers matching the highly conserved 5´untranscribed region of the different HCV genotypes (forward: 5´- AGCGTCTAGCCATGGCGT-3´); reverse: 5´ - GGTG- TACTCACCGGTTCCG-3´) were from TIB MolBiol (Berlin, Germany).

Reactions were performed using a 7900HT Real-Time PCR System (Applied Biosystems, Foster City, CA) and all samples were assayed in triplicate. Optical data obtained were analyzed using the default and variable parameters available in the Sequence Detection Systems software (SDS, version 2.2.2; Applied Biosystems).

Expression level of target gene was normalized using as endogenous control genes

the eukaryotic translation elongation factor 1 alpha 1 (forward: 5´ -

AGCAAAAATGACCCACCAATG-3´; reverse: 5´ -GGCCTGGATGGTTCAGGATA-3´)

and the beta glucuronidase (forward: 5´ -CCACCAGGGAC- CATCCAAT-3´ reverse:

5´ -AGTCAAAATATGTGT- TCTGGACAAAGTAA-3´). The expression level of IP-10 mRNA in the first of the 72 liver biopsy evaluated was chosen as the reference, and assigned 1.0 arbitrary units (AU).

Statistical Methods

All statistical analyses were performed with either SAS for Windows (version 8.02, SAS Institute, Inc., Cary, NC). (Pharma Consulting Group, Uppsala, Sweden), with StatView for Macintosh (version 5.0, SAS Institute) by M.L. (Gothenburg, Sweden) or with IBM SPSS Statistics version 19.0 by ÅA and SN (Skövde Sweden.) All reported p values were two-sided, and p values <0.05 was considered significant.

In papers I and V the Chi-square test and Fisher’s exact test were used to evaluate differences in frequencies of SVR, relapse, and nonresponse between treatment groups. In order to evaluate factors associated with SVR in paper I, univariate analyses of covariates were performed. All covariates with a p-value of 0.10 or less in the univariate analysis were considered for inclusion in a multivariate logistic regression model. The potential explanatory variables included in the multivariate analysis were as follows: HCV RNA levels at baseline, day 3, day 7, day 8, day 29, week 8, and week 12; second slope (as measured by the decline in HCV RNA between days 3 and 7); age; gender; fibrosis stage; steatosis grade; body mass index; weight; height; baseline β-2-macroglobulin; baseline gamma glutamyl transpeptidase; baseline bilirubin; baseline procollagen type 2 N-terminal propeptide;

baseline hyaluronic acid; baseline cholesterol; alcohol intake during the year prior to enrolment; depression score at baseline; duration of infection; ribavirin trough levels at day 29 and week 12; and percentage of the target dose of pegylated interferon taken. A stepwise procedure with forward selection and backward elimination was performed for each study arm separately and for the study arms combined through a comparison of the difference in deviance between nested models.

In papers II-V, Spearman’s rank correlation coefficient r

s

test was used to evaluate

relationships between variables and individual characteristics between groups were

evaluated using the Wilcoxon-Mann- Whitney U-test. Friedman’s test was employed to assess change over time between measurements in paper II.

In paper III, viral reduction was evaluated using Kaplan-Meier cumulative survival plots displaying the proportion of patients attaining serum HCV RNA level < 50 IU/mL during the initial 6 weeks of therapy (during which time all patients received the same treatment). The log-rank test was used for comparison between the Kaplan-Meier plots with patients grouped as to whether they had intrahepatic IP-10 mRNA levels above or below the median level (i.e., 0.8 arbitrary units)

In paper V multivariate analyses were performed after univariate analyses on the per-protocol patients treated for 24 weeks with all variables associated with the endpoint (P<0.1) being entered, after exclusion of on-treatment HCV RNA levels.

The variables entered in the multivariate analyses were age, BMI, Ishak fibrosis

stage, steatosis grade, HOMA score, peg-interferon concentrations on day 3, 7 and

29, ribavirin concentrations day 29 and week 12, and baseline HCV RNA level.

Results

Paper I

Impact of treatment duration on outcome

Twelve weeks of combination therapy, in general, was inferior to 24 weeks with respect to both a lower SVR rate (ITT population: 59% vs. 78%, P<0.0001) and a higher relapse rate (33% vs. 12%, P<0.0001). This held true for genotypes 2 and 3 in both the ITT (Fig. 4), and PP analyses, irrespective if RVR was achieved or not.

Figure 4. Histogram displaying the percentage of patients in ITT analysis achieving SVR, relapse or non-response grouped according to treatment duration and genotype. P values calculated using Chi squared test.

The genotype 2–infected patients were significantly older than those infected with genotype 3 (47.2 vs. 39.8 years; P <0.0001), but they did not differ significantly in

0 10 20 30 40 50 60 70 80 90 100

Genotype 2 (n=55)

Genotype 3 (n=137)

Genotype 2 (n=49)

Genotype 3 (n=139)

12 Weeks Treatment 24 Weeks Treatment

%

p=0.0057

p=0.0015

56%

38%

58%

31%

82%

12%

78%

5% 9% 6% 12% 10%

p=0.0001 p=0.0026

SVR Relapse Non-Response

The age of the patients impacted significantly on treatment efficacy, with markedly better outcome in those younger than 40 years (Fig. 5). For patients younger than 40 years of age achieving RVR, 86% achieved SVR in the 12-week study arm as compared to 93% in the 24-week arm.

Figure 5. Histogram displaying the percentage of patients achieving SVR in ITT analysis grouped

according to treatment duration and patient age (<40 years vs. ≥40 years). . P values calculated using Chi squared test.

The majority of these younger patients (72%) achieved RVR, and not surprisingly, we observed lower SVR rates if RVR was not achieved. However, within this small group of patients (n=22 and n=19 in the 12- and 24-week arms, respectively), no significant benefit of extending the duration of therapy to 24 weeks was noted in the ITT population (SVR 73% vs. 63% for for the 12- and 24-week arms respectively), with similar results observed in the PP analysis (SVR: 73% in both arms). Patients

0 10 20 30 40 50 60 70 80 90 100

< 40 years of age (n=76)

! 40 years of age (n=118)

< 40 years of age (n=76)

! 40 years of age (n=112)

12 Weeks Treatment 24 Weeks Treatment

%

p<0.0001

80%

14%

45% 45%

83%

8%

75%

15%

5% 10% 9% 9%

p<0.0001

SVR Relapse Non-Response

younger than 40 years (who constituted 40% of the ITT population) were less likely to have cirrhosis (2% vs. 20%, P <0.0001).

Pre-treatment viral load also significantly impacted on treatment outcome. The 102 patients (27%; 51 patients in each study arm) with baseline HCV RNA below 400,000 IU/mL had an SVR rate of 80% with 12 weeks of therapy and 90% with 24 weeks as compared to 51% and 74%, respectively, for patients with baseline HCV RNA ≥400,000 IU/mL (P<0.0001). Of the patients with a low baseline viral load, 54%

were younger than 40 years, and 83% subsequently achieved RVR. Eight of the patients with baseline HCV RNA <400,000 IU/mL had cirrhosis, 6 of whom achieved SVR (4 out of 5 and 2 out of 3 in the 12-and 24 week arms respectively).

The SVR rate in the 12-week arm was inferior to that in the 24-week arm, regardless

of the stage of liver fibrosis as assessed in the liver biopsies as well as for patients

with steatosis, regardless of severity, (P=0.0002; Fig.6).

Figure 6. Histogram displaying the percentage of patients achieving; SVR, relapse and non-response in ITT analysis grouped according to treatment duration and fibrosis stage. . P values calculated using Chi squared test.

Three independent predictors of SVR in the 12- week arm were identified by multivariate analysis: HCV RNA on day 7 (<1000 vs. ≥1000 IU/mL, odds ratio 7.98;

P<0.0001), age (<40 vs. ≥40 years, odds ratio 4.84; P<0.0001), and HCV RNA on day 29 (detectable vs. undetectable, odds ratio 2.13; P=0.0454). Similarly, two independent predictors of SVR were identified in the 24-week arm: HCV RNA on day 29 (detectable vs. undetectable, odds ratio 5.44; P=0.0002) and age (<40 vs. ≥40 years, odds ratio 3.50; P<0.0001).

An HCV RNA level below 1000 IU/mL on day 7, suggestive of a very rapid clearance of virus, was predictive of successful short-term treatment also in patients with age

≥40, constituting 23% of these older patients, of whom 91% vs. 89% achieved SVR

0 10 20 30 40 50 60 70 80 90 100

No Significant Fibrosis

(n=85)

Bridging Fibrosis (n=70)

Cirrhosis (n=23)

No Significant Fibrosis

(n=83)

Bridging Fibrosis (n=70)

Cirrhosis (n=23)

12 Weeks Treatment 24 Weeks Treatment

%

69%

28%

51%

37%

30%

43%

84%

7%

76%

14%

57%

30%

2%

11%

26%

8% 10% 13%

p=0.022

p=0.0051

p=0.002 p=0.0004

SVR Relapse Non-Response