SCH , a Novel Hepatitis C Virus Protease Inhibitor, Plus Pegylated Interferon -2b for Genotype 1 Nonresponders

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1 GASTROENTEROLOGY 2007;132: , a Novel Hepatitis C Virus Protease Inhibitor, Plus Pegylated Interferon -2b for Genotype 1 Nonresponders CHRISTOPH SARRAZIN,*,# REGINE ROUZIER, FRANK WAGNER, NICOLE FORESTIER,*,# DOMINIQUE LARREY, SAMIR K. GUPTA, MUSADDEQ HUSSAIN, AMRIK SHAH, DAVID CUTLER, JENNY ZHANG, and STEFAN ZEUZEM*,# *Department of Internal Medicine II, Saarland University Hospital, Homburg, Germany; Centre Cap, Montpellier, France; Charité Research Organisation, Charité Universitätsmedizin, Berlin, Germany; Service d Hépatogastro-Entérologie et Transplantation, Montpellier School of Medicine, and INSERM Unit 632, Montpellier, France; Schering-Plough Research Institute, Kenilworth, New Jersey, and # Department of Internal Medicine I, J.W. Goethe-University Hospital, Frankfurt am Main, Germany See editorial on page Background & Aims: is a novel and potent oral hepatitis C virus (HCV) protease inhibitor. In this phase Ib study, we assessed safety parameters and virologic response of combination of plus pegylated (PEG) interferon (IFN) -2b in patients with HCV genotype 1 infections who were previously nonresponders to ribavirin therapy. Methods: This was a multicenter, open-label, 2-dose level, 3-way crossover, randomized (to crossover sequence) study carried out in 3 medical centers in Europe. Adult patients received 200 mg (n 14) or 400 mg (n 12) 3 times daily orally and 1.5 g/kg subcutaneously once each week. Patients received as monotherapy for 1 week, as monotherapy for 2 weeks, and combination therapy for 2 weeks with washout periods between each treatment period. Results: Combination therapy with and was well tolerated, with no clinically significant changes in safety parameters. Mean maximum log 10 changes in HCV RNA were and for PEG-IFN- -2b plus 200 mg and 400 mg, respectively, compared with and for SCH 200 mg and 400 mg, respectively, and and for alone in the 200 mg and 400 mg groups, respectively. Conclusions: plus was well tolerated in patients with HCV genotype 1 nonresponders to ribavirin. These preliminary results of antiviral activity of the combination suggest a potential new therapeutic option for this hard-to-treat, nonresponder patient population. The current standard of care for the serious public health problem represented by chronic hepatitis C is pegylated (PEG) interferon (IFN) plus ribavirin. Among patients with genotype-1a/1b hepatitis C virus (HCV) infection, the most common genotype in North America, Europe, and Japan, treatment with PEG-IFN- plus ribavirin results in sustained virologic response in only approximately 40% to 50%. 1 6 Furthermore, retreatment of nonresponders to IFN- /ribavirin combination therapy leaves room for improvement with overall response rates of less than 20%. 7 Therefore, this patient population has the greatest unmet medical need. Thus, new small-molecule strategies of anti-hcv therapeutics, including HCV NS3 protease and NS5B polymerase inhibitors, are under investigation The difficult-to-treat population that has not responded to current therapy may benefit most from these new developments. HCV is an enveloped, positive-strand RNA virus of approximately 9.6 kilobase. HCV infection of host hepatic cells triggers a series of intracellular signaling events through specific receptors that result in increased production of IFNs and, the central mediators of the host antiviral response. The expression of many genes is regulated by IFNs, and their products mediate viral and host functions that limit HCV replication. Furthermore, secreted IFN- interacts with the IFN- / receptor to activate the Janus kinase/signal transducers and activators of transcription signaling pathway in infected cells and in neighboring uninfected tissue. Signaling through this pathway results in amplified IFN / production and limits cell-to-cell spread of virus. 16 Upon entry into a host cell, the RNA genome is translated to assemble a 3000-amino acid polyprotein that undergoes posttranslational processing by viral and host proteases to produce 10 different polypeptides. 17 One of these viral proteins, the serine protease NS3, has an essential role in replication of HCV. 16 Recent research indicates that the HCV NS3 serine protease may also be implicated in mechanisms that promote evasion of the host response to HCV and lead to persistent chronic Abbreviations used in this paper: AUC, area under the plasma concentration-time curve; IFN, interferon; PEG, pegylated; RT-PCR, reverse-transcriptase polymerase chain reaction; TRIF, toll-interleukin-1 receptor-domain-containing adaptor inducing IFN-ß by the AGA Institute /07/$32.00 doi: /j.gastro

2 April 2007 IN COMBINATION WITH PEG-IFN- -2B 1271 infection. 18,19 These findings and the suggestion that inhibition of the NS3 serine protease may restore IFNsensitive signaling pathways as well as inhibit replication of HCV 20,21 make inhibition of the NS3 serine protease an attractive target for development of antiviral therapies. may provide dual antiviral activity through direct suppression of viral replication and restored IFN activity. The NS3 serine protease has high substrate specificity because of a unique extended substrate-binding cleft. Rational inhibitor design resulted in discovery of SCH, a novel peptidomimetic NS3 protease inhibitor. The ketoamide portion of forms a specific, stable, covalent, and reversible complex with NS3 in vitro and has potent activity in the HCV replicon system. Furthermore, results of combining and IFN- -2b in the HCV replicon system suggested at least additive potency of the combination compared with either agent alone. 22 These observations provided rationale for clinical investigation of combination therapy with and in a phase Ib trial. Two initial dose levels of were evaluated for safety and tolerability as monotherapy and in combination with in comparison with PEG-IFN- -2b alone in 26 patients with chronic HCV infection who had previously not responded to treatment with ribavirin. Virologic response and pharmacokinetic parameters of the 2 agents in short-term monotherapy and combination therapy were also evaluated. Materials and Methods The primary objective of this phase I study was to determine the safety and tolerability of in combination with for patients with HCV genotype 1 who had previously failed to respond to (Peg-Intron; Schering-Plough Corporation, Kenilworth, NJ) ribavirin. Secondary objectives were to assess pharmacodynamic characteristics of this combination therapy with HCV viral load measurements, as well as to evaluate pharmacokinetic parameters for each component alone and in combination. A number of at least 10 patients for each protease inhibitor dose level were considered to be sufficient for assessment of safety, efficacy, and proof of concept in this phase I study. Patients of either sex and any race could be included in this study if they were 18 to 60 years of age, were willing to give written informed consent, and were willing to undergo multiple inpatient periods and outpatient visits during the study. Female patients had to be surgically sterile or of non-childbearing potential, and males had to practice acceptable methods of contraception. Female partners of male enrollees also had to practice acceptable methods of contraception, and all contraception had to have been practiced for 30 days before the dosing period, during all dosing periods, and for 30 days after discontinuation of dosing. Patients had to be serum positive for HCV RNA by quantitative polymerase chain reaction (PCR) assay, with 100,000 IU/mL RNA and be genotype 1a or 1b nonresponders to with or without ribavirin. Nonresponse was defined as achieving less than a 2-log 10 decline in HCV RNA levels after at least 12 weeks of dosing with at 1.5 g/kg/wk. Patients had to have alanine aminotransferase (ALT) and aspartate aminotransferase 5 times upper limit of normal, -fetoprotein values within normal levels, negative screen for drugs with high potential for abuse, normal or clinically acceptable electrocardiogram (QTc value, 450 milliseconds (ms) for females and 430 ms for males), and evidence of compensated liver disease. Patients were required to meet the following criteria: hemoglobin 11 g/dl for females and 12 g/dl for males, white blood cells 4000/mm 3, neutrophil count 1500/mm 3, and platelets 100,000/mm 3 and the following parameters within normal limits: direct bilirubin, indirect bilirubin, albumin, prothrombin time, activated partial thromboplastin time, and serum creatinine. Patients were excluded from the study if they met any of the following criteria: hemophilia or use of anticoagulant therapy; evidence of advanced liver disease (eg, known cirrhosis, history or presence of ascites, bleeding varices, encephalopathy); presence of organ transplant; known human immunodeficiency virus (HIV) or hepatitis B virus positivity based on recent tests for anti-hiv antibodies and hepatitis B surface antigen; or liver disease with a cause other than chronic hepatitis C. The significance of antinuclear antibodies, if present, was to be evaluated by investigators for individual patients to determine whether any interference with the protocol that would warrant exclusion from the study could be expected. The study was carried out in 3 medical centers in Europe. Approval by each center s institutional review board was obtained, and the study was conducted in conformance with Good Clinical Practices. All enrolled patients provided written informed consent. All investigational drugs were supplied by Schering-Plough Research Institute (Kenilworth, NJ). This phase I clinical trial was a randomized-to-sequence, open-label, 2-dose level, crossover study. Patients (n 26) received 3 periods of dosing, consisting of administration of monotherapy for 1 week, administration of monotherapy once weekly for 2 weeks, and administration of combination plus for 2 weeks. The first 2 treatment periods were followed each by at least 2-week washout periods, and the third treatment period was followed by a 2-week follow-up period. Patients were randomized to determine the sequence of treatment periods by a computer program (Table 1). Based on the

3 1272 SARRAZIN ET AL GASTROENTEROLOGY Vol. 132, No. 4 Table 1. Design of the 3-Way Crossover Study No. per Sequence Period 1 Period 2 Period 3 4 SCH 4 5 Combo Tx 5 SCH 4 4 Combo Tx Combo Tx SCH Combo Tx SCH Combo Tx SCH Combo Tx SCH NOTE. Patients (n 26) were randomized to receive 6 possible sequences of treatment at each dose of (n 14 at 200 mg 3 times daily; n 12 at 400 mg 3 times daily). Combo Tx, combination therapy with and. results of a previous dose-finding study, 2 dose levels of, 200 mg 3 times daily and 400 mg 3 times daily, were evaluated. was administered at 1.5 g/kg once per week. Safety and tolerability of study treatments were assessed by clinical laboratory tests, vital signs, physical examination, electrocardiograms, and occurrence of adverse events. Clinical laboratory tests were recorded on days 1, 3, 6, and 10 during combination therapy and monotherapy with and on days 1, 3, and 6 during monotherapy and day 14 of the follow-up period. Urinalysis was performed on day 1 of each treatment period and the follow-up period. Electrocardiograms were performed at hours 0 and 1 on days 1, 1, 2, 3, 8, 9, and 10 during combination therapy periods and at hours 0 and 1 on days 1, 1, 2, and 3 during monotherapy with. In addition to outpatient visits, patients were confined to the hospital for the initial 8 days of the combination therapy and monotherapy treatment periods and for the initial 4 days during the monotherapy treatment period to assess carefully the safety and tolerability as well as to optimize compliance. Complete blood counts and chemistry were obtained twice per week during dosing periods. The severity of adverse events was graded according to the National Cancer Institute Common Toxicity Criteria. 23 Investigators at each site assessed each adverse event as unlikely, possibly, or probably related to use of study drug. Blood samples for HCV RNA determinations and viral sequencing were collected daily during the different therapies. HCV RNA was measured by extracting total RNA from the sample and using an in-house real-time reversetranscriptase (RT)-PCR assay with a lower limit of detection of 29 IU/mL. The amplification target was the 5=untranslated region of the HCV genome. An internal RNA control was added to each sample to assess efficiency of RNA extraction and RT-PCR. Appropriate negative and positive controls were added in each assay run. During their hospital stay, patients were fed standard low-fat meals either 90 minutes before dosing or 90 minutes after on days when pharmacokinetic sampling was not performed. On pharmacokinetic sampling days, patients underwent a 10-hour fast, except for water before sampling and during the 4-hour sampling period. During outpatient periods, patients were asked to attempt to keep the same schedule of meals and dosing and to record meal and dosing times in a diary. Blood samples for pharmacokinetic analyses of SCH were collected prior to dosing (0 hour) and at 0.5, 1, 1.5, 2, 4, 6, and 8 hours after the morning dose on day 1 of monotherapy treatment periods and on days 1 and 8 of combination therapy treatment periods. Blood samples for pharmacokinetic analyses of were collected beginning on day 1 of monotherapy and combination therapy treatment periods at hours 0, 12, 24, 48, Table 2. Demographic and Baseline Characteristics of 26 Patients Who Received at 2 Different Dose Levels in Combination With 200 mg TID (n 14) 400 mg TID (n 12) Sex, n (%) Female 6 (43) 3 (25) Male 8 (57) 9 (75) Race, n (%) White 12 (86) 12 (100) Black 2 (14) 0 Age, y Mean (SD) 44.5 (6.1) 48.9 (9.1) Median Range Weight (kg) Mean (SD) 77 (16) 79.1 (15.3) Median Range Height, cm Mean (SD) (11.1) (11.6) Median Range BMI (kg/m 2 ) Mean (SD) 25.4 (3.2) 25.9 (2.0) Median Range ALT (U/mL) Mean Range HCV RNA (Log IU/mL) Mean Range ALT, alanine aminotransferase; BMI, body mass index.

4 April 2007 IN COMBINATION WITH PEG-IFN- -2B 1273 Table 3. Summary of Treatment-Emergent Adverse Events in 10% or More of Patients in Any Cohort That Received SCH Monotherapy, Monotherapy, or Combination Therapy 200 mg TID 1 week, n 12 (%) 200 mg TID 2 weeks, n 13 (%) 2 weeks, n 24 (%) 400 mg TID 1 week, n 11 (%) 400 mg TID 2 weeks, n 10 (%) Total, n 26 (%) Adverse events Subjects reporting 5 (42) 13 (100) 22 (92) 2 (18) 10 (100) 25 (96) any adverse event Subjects 0 1 (8) 2 (8) (12) discontinuing because of an adverse event Symptoms Application site 0 2 (15) 1 (4) 0 1 (10) 3 (12) disorders Fatigue 0 1 (8) 1 (4) 0 2 (20) 3 (12) Fever 0 2 (15) 3 (13) 0 4 (40) 8 (31) Headache 3 (25) 10 (77) 14 (58) 1 (9) 8 (80) 23 (88) Influenza-like 0 1 (8) 2 (8) 0 1 (10) 3 (12) symptoms Rigors 0 6 (46) 8 (33) 1 (9) 4 (40) 14 (54) Weakness (4) 0 1 (10) 1 (4) Abdominal pain 0 2 (15) 1 (4) (12) Dyspepsia (10) 1 (4) Nausea 0 2 (15) 1 (4) (12) Vomiting 0 2 (15) 1 (4) 1 (9) 0 3 (12) Back pain (8) 0 1 (10) 3 (12) Myalgia 0 7 (54) 15 (63) 0 7 (70) 18 (69) Emotional (10) 1 (4) lability Strangury (10) 1 (4) Taste perversion (10) 1 (4) Signs Injection site 0 2 (15) 1 (4) 0 1 (10) 3 (12) inflammation Laboratory and electrocardiogram abnormalities Anemia 2 (17) 1 (8) (8) Leukopenia 0 2 (15) 4 (17) (19) Neutropenia 0 6 (46) 5 (21) (35) QTc/QT prolongation (4) 1 (9) 1 (10) 1 (4) NOTE. monotherapy (200 mg TID or 400 mg TID); monotherapy (1.5 g/kg/wk). Laboratory values outside the normal range were assessed as adverse events with the following definitions: anemia, hemoglobin values of 11 g/dl for females and 12 g/dl for males; leukopenia, white blood count 4000/mm 3 ; neutropenia, neutrophil count 1500/mm 3 ; QTc/QT prolongation 450 ms for female and 430 ms for male patients (Bazett s). Any clinically significant change from baseline was recorded as an adverse event. TID, 3 times daily. 72, and 168. Plasma samples were assayed for SCH using a validated liquid chromatographic tandem mass spectrometric method with a limit of quantitation of ng/ml. Serum concentrations were determined as previously described using a validated electrochemiluminescence assay (limit of quantification 50 pg/ml, and variability was 12% at 50 pg/ml). 24 The following pharmacokinetic variables were estimated for using model-independent methods: maximum observed plasma concentration; time of observed maximum plasma concentration; area under the plasma concentration-time curve over the dosing interval (AUC [0- ]); apparent total body clearance at steady state; and accumulation ratio. Serum concentration data were used to estimate AUC (0 168 hours) for. Results A total of 26 patients (17 males, 9 females) were randomized to 3 different treatment arms in the sequences described in Table 1. Fourteen patients received

5 1274 SARRAZIN ET AL GASTROENTEROLOGY Vol. 132, No. 4 Table 4. Mean Pharmacokinetic Parameters of on Days 1 and 8 After Dosing With 200 mg 3 Times Daily and 400 mg 3 Times Daily as Monotherapy or in Combination With Mean (CV, %) 200 mg TID monotherapy (n 12) 200 mg TID combination (n 12) 400 mg TID monotherapy (n 10) 400 mg TID combination (n 10) Day 1 Day 1 Day 8 Day 1 Day 1 Day 8 Tmax (h) a 1.50 ( ) 1.50 ( ) 1.00 ( ) 1.25 ( ) 1.50 ( ) 1.00 ( ) Cmax (ng/ml) 261 (67) 240 (48) 351 (44) 520 (40) 477 (50) 523 (36) AUC(0- ) 731 (54) 758 (37) 1200 (27) 1600 (44) 1630 (45) 1990 (31) (ng h/ml) CL/F (L/h) 177 (25) 217 (28) Ratio b 1.71 (31) 1.24 (36) AUC, area under the plasma concentration-time curve; AUC(0- ), area under the plasma concentration-time curve over the dosing interval; CL/F, apparent total clearance at steady state; Cmax, maximum observed plasma concentration; CV, coefficient of variation; TID, 3 times daily (q8h); Tmax, time of observed maximum plasma concentration. a Median (range). b Accumulation ratio of day 8 AUC(0- )/day 1 AUC(0- ). therapy at the 200 mg 3 times daily dose level and 12 at the 400 mg 3 times daily dose level. Demographic and other baseline characteristics of these patients are shown in Table 2. Safety as monotherapy and in combination with was generally well tolerated. Headache, myalgia, rigor, and fever were the most common treatment-emergent adverse events reported during combination and PEG-IFN monotherapy treatment periods. A summary of treatment-emergent adverse events experienced by 10% or more of patients in any group is shown in Table 3. Consistent with adverse event profiles associated with monotherapy, the incidence of headache, rigor, and myalgia was higher during combination therapy than monotherapy. Evaluation of blood chemistry, hematology, and urinalysis parameters revealed no clinically significant abnormalities and no pattern of abnormalities associated with treatments in this study. One instance (8% of patients) of grade 1 increase in ALT levels was observed during combination therapy with 200 mg and. No significant changes in vital signs or electrocardiogram data between baseline and treatment values were observed. One occurrence of anemia and 1 complex partial seizure were considered to be important or serious adverse events, which, however, were not considered by the investigator to be related to administration of study drugs. The patient with the partial seizure had a past history of similar events, which he did not disclose during screening for this study. In all, 3 patients discontinued treatment because of treatment-emergent adverse events (complex partial seizures during combination therapy in period 1; leukopenia and neutropenia during PEG-IFN-2b monotherapy in period 1; and neutrophil count decrease during monotherapy in period 2), and 1 patient discontinued treatment for reasons unrelated to the study. All 3 treatment arms were completed by 12 patients who received 200 mg 3 times daily and 10 patients given 400 mg 3 times daily. Pharmacokinetic Data Pharmacokinetic parameters for on day 1 of monotherapy and on days 1 and 8 of combination therapy with are shown in Table 4. The AUC (0- ) on day 1 of monotherapy and combination therapy of both dose groups are similar, which suggests that there was no interaction between SCH and PEG-IFN. Based on AUC measurements on day 1 and 8 of combination therapy, the mean accumulation ratios of were 1.71 following 200 mg 3 times daily therapy and 1.24 following 400 mg 3 times daily therapy. Estimates of relative bioavailability of SCH indicated only slightly increased (9%) AUC for during combination therapy with PEG-IFN- -2b and 200 mg compared with 200 mg monotherapy and no increase in AUC during combination therapy with and 400 mg SCH compared with 400 mg 3 times daily monotherapy. Mean AUC(last measurable time point) values for were 71,100 pg h/ml after combination therapy with 200 mg 3 times daily and 400 mg 3 times daily and 86,000 pg h/ml after PEG- IFN- -2b monotherapy. Pharmacodynamics Pharmacodynamics are calculated for all 22 patients who completed all 3 treatment arms of the

6 April 2007 IN COMBINATION WITH PEG-IFN- -2B 1275 decreases were observed approximately 2 days after the weekly injection of, followed by an increase to near baseline (Figures 1 and 2). As also shown in Figures 1 and 2, combination therapy with at either dose level and resulted in greater decreases in HCV RNA than alone. Furthermore, the degree of virologic response was related to the dose of in monotherapy and combination therapy regimens. A maximum mean change in HCV RNA of (range, 3.3 to 0.6) log 10 in week 1 and (range, 4.3 to 1.0) log 10 in week 2 was observed for plus 200 mg 3 times daily (overall mean maximum decline, ), and a maximum mean change of (range, 3.8 to 1.2) log 10 in week 1 and (range, 4.3 to 0.3) log 10 in week 2 was observed for plus 400 mg 3 times daily (overall mean maximum decline, ). The distribution of responses according to degree of HCV RNA reduction indicates that more patients had greater reductions with combination therapy with the higher dose of in combination with (Table 5). Figure 1. Individual viral responses to plus (PEG) combination therapy of 22 patients who completed all 3 treatment arms. (A) 200 mg 3 times daily plus at 1.5 g/kg/wk. Average values are shown for monotherapy (brown line, triangle) (n 22), for protease inhibitor (PI) 200 mg 3 times daily alone (yellow line, diamond), and for plus (green line, square)(n 12). (B) 400 mg 3 times daily plus at 1.5 g/kg/wk. Average values are shown for monotherapy (brown line, triangle) (n 22), for SCH 400 mg 3 times daily alone (yellow line, diamond), and for PEG- IFN- -2b plus (green line, square)(n 10). study. Treatment with alone for 1 week resulted in a mean of the maximal change in HCV RNA of (range, 1.8 to 0.2) log 10 at the 200 mg 3 times daily dose level and (range, 2.4 to 0.1) log 10 at the 400 mg 3 times daily dose level. In this nonresponding patient population, treatment with for 2 weeks was associated with a maximum mean change of log 10 in the group that received 200 mg 3 times daily SCH and log 10 in the group that received 400 mg 3 times daily. These Discussion We found that combination and was safe and well tolerated in patients with genotype 1 HCV infection who had previously not responded to with or without ribavirin. In this multiple-dose, 3-way crossover, phase I study, no differences in adverse events, laboratory parameters, or electrocardiogram data were observed when patients received monotherapy or combination therapy for 2-week periods. Furthermore, no differences in safety parameters were found in patients who received either dose level of (200 mg 3 times daily or 400 mg 3 times daily) (Table 3). The AUC and maximum observed plasma concentration increased proportionally as the dose was increased from 200 to 400 mg, whether as monotherapy or in combination with (Table 4). Addition of did not significantly increase or decrease AUC of. Nonresponders are known to be a heterogeneous group of patients. To ensure optimal comparison among treatment groups, the patients within this trial served as their own internal control and sequentially received,, and PEG-IFN plus. Washout periods of at least 2 weeks were considered to be sufficient for return of viral loads to baseline levels, and, indeed, mean differences between baseline values after each treatment were only 0.12 log 10 and 0.23 log 10 IU/mL for patients in the 200 and 400 mg groups, respectively (Figure 2). Carryover

7 1276 SARRAZIN ET AL GASTROENTEROLOGY Vol. 132, No. 4 Figure 2. HCV RNA kinetics in individual patients throughout the complete study period with washout periods of 2 weeks (2 wks) after each treatment arm. Changes of HCV RNA concentration from baseline are shown for all 4 patients who received the 3 different treatments in the following sequence: (PEG) monotherapy, protease inhibitor (PI) monotherapy, and plus combination therapy. For HCV RNA concentration before start of treatment in the first arm, the mean value from day 1 and day 1 is shown. Treatment started always after blood was drawn for HCV RNA measurement at day 1. effects because of the sequence of the 3 different treatments were not observed. Evaluation of virologic response during monotherapy and combination therapy suggests that combination plus was associated with anti-hcv activity in these patients who had previously not responded to ribavirin. at the 400 mg 3 times daily dose level in combination with was more active than the 200 mg 3 times daily dose combination (Figure 1). The oscillatory nature of HCV RNA levels during monotherapy in which there is a steep viral load drop on days 1 3 after dosing with less impact toward the end of the week appears to be related to pharmacokinetic properties of. This oscillatory characteristic can still be seen to some extent in the combination therapy curves. With each weekly treatment of, however, the HCV Table 5. Distribution of Maximal HCV RNA Reduction According to Treatment in 22 Patients Maximum HCV RNA reduction (log 10 ) Treatment N 0to 1 1 to 2 2 to 3 3 Cohort mg TID SCH mg TID Cohort mg TID SCH mg TID TID, 3 times per week. RNA drops greater so that, if only every 7-day time points were plotted, a steady and steep decline would be observed. 25 Because has a pronounced impact on reducing viral load and replication across the weekly dosing interval, the combination with SCH would be expected to suppress viral resistance development while the protease inhibitor enhances the HCV RNA decline. More patients achieved larger decreases in viral load during combination therapy with the higher dose level of, and HCV RNA became undetectable in 4 of 10 patients within the 2-week period of dosing (Table 5). Safety data support investigating higher doses of to produce even greater anti-hcv activity in future studies. Clonal sequence analysis of the HCV to evaluate potential for selection of NS3 serine protease-resistant strains during monotherapy and combination therapy is ongoing. The important role of the viral NS3 serine protease in hepatitis C virulence may be related to its dual role in HCV replication and in mechanisms that allow evasion of host defense. NS3 catalyzes separation of proteins from the approximately 3000-amino acid HCV polyprotein that form a so-named replicon on the host endoplasmic reticulum, which uses the viral genome as a template to form negative-strand RNA intermediates that are, in turn, used to synthesize new positive-strand (genomic) RNA. 26 Genomic RNA is translated to produce more polyprotein or is encapsidated to form progeny virions. In addition, NS3 blocks functioning of the cellular receptor RIG-1, which binds double-stranded HCV RNA and initiates downstream activation of interferon regulatory factor 3 and nuclear factor B. These regulatory factors promote IFN- expression and onset of the host response. NS3 cleaves the adaptor protein Cardif, a downstream component of the RIG-1 pathway, effectively reducing IFN- production. 18 An additional source of interferon regulatory factor 3 and

8 April 2007 IN COMBINATION WITH PEG-IFN- -2B 1277 nuclear factor B activation through specific receptors for double-stranded HCV RNA is Toll-interleukin-1 receptor-domain-containing adaptor inducing IFN- (TRIF). NS3 has been shown to block TRIF activation of interferon regulatory factor 3 and nuclear factor B, thus further reducing expression of IFN-. 19 Thus, inhibition of these NS3 functions may increase the ability of IFN- to promote IFN- production and the host defense response. These results are a preliminary indication of safety and anti-hcv activity in hard-to-treat patients with genotype 1 HCV infection who had previously not responded to therapy with or without ribavirin. Inhibition of the dual activities of NS3 with and addition of may meet the significant unmet need for efficacious anti-hcv therapy in this challenging patient population as well as in treatment-naive patients. Phase II clinical trials with HCV genotype 1 nonresponders are underway to determine the optimum dosing and exposure levels for this potentially important therapeutic regimen. SCH, a novel HCV NS3 protease inhibitor, will also be evaluated in naive patients as well as other hard-totreat populations including African Americans, cirrhotic patients, HIV-coinfected patients, and liver transplant recipients. References 1. Zeuzem S, Buti M, Ferenci P, Sperl J, Horsmans Y, Cianciara J, Ibraniyi E, Weiland O, Noviello S, Brass C, Albrecht J. Efficacy of 24 weeks treatment with peginterferon alfa-2b plus ribavirin in patients with chronic hepatitis C infected with genotype 1 and low pretreatment viremia. J Hepatol 2006;44: Manns MP, McHutchison JG, Gordon SC, Rustigi VK, Shiffman M, Reindollar R, Goodman ZD, Koury K, Ling M, Albrecht JK. Peginterferon alfa-2b plus ribavirin compared with interferon alfa-2b plus ribavirin for initial treatment of chronic hepatitis C: a randomised trial. Lancet 2001;358: Scotto G, Fazio V, Palumbo E, Cibelli DC, Saracino A, Angarano G. Treatment of genotype 1B HCV-related chronic hepatitis: efficacy and toxicity of three different interferon alfa-2b/ribavirin combined regimens in naive patients. New Microbiol 2005;28: Muir AJ, Bornstein JD, Killenberg PG. Peginterferon alfa-2b and ribavirin for the treatment of chronic hepatitis C in blacks and non-hispanic whites. New Engl J Med 2004;350: Hadziyannis SJ, Sette H Jr, Morgan TR, Balan V, Diago M, Marcellin P, Ramadori G, Bodenheimer H Jr, Bernstein D, Rizzetto M, Zeuzem S, Pockros PJ, Lin A, Ackrill AM, PEGASYS International Study Group. Peginterferon- 2a and ribavirin combination therapy in chronic hepatitis C: a randomized study of treatment duration and ribavirin dose. Ann Intern Med 2004;140: Fried MW, Shiffman ML, Reddy R, Smith C, Marinos G, Gonçales FL, Häussinger D, Diago M, Carosi G, Dhumeaux D, Craxi A, Lin A, Hoffman J, Yu J. Peginterferon alfa-2a plus ribavirin for chronic hepatitis C virus infection. New Engl J Med 2002;347: Poynard T, Schiff E, Terg G, Goncales F, Diago M, Reichen J, Moreno R, Bedossa P, Burrhough M, Albrecht J. Sustained virologic response (SVR) in the EPIC3 trial: week twelve virology predicts SVR in previous interferon/ribavirin treatment failures receiving PEG-Intron/Rebetrol (PR) weight-based dosing (WBD). J Hepatol 2005;42(Suppl 2):40A. 8. Lamarre D, Anderson PC, Bailey M, Beaulieu P, Bolger G, Boneau P, Bos M, Camceron DR, Cartier M, Cordingley MG, Faucher AM, Goudreau N, Kawai SH, Kukolj G, Lagace L, LaPlante SR, Narjes H, Poupart MA, Rancourt J, Sentjens RE, St. George R, Simoneau B, Steinmann G, Thibeault D, Tsantrizos YS, Weldon SM, Yong CL, Llinas-Brunet M. An NS3 protease inhibitor with antiviral effects in humans infected with hepatitis C virus. 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9 1278 SARRAZIN ET AL GASTROENTEROLOGY Vol. 132, No. 4 replicon cells. Antimicrob Agents Chemother 2004;48: Malcolm BA, Liu R, Lahser F, Agrawal S, Belanger B, Butkiewicz N, Chase R, Gheyas F, Hart A, Hesk D, Ingravallo P, Jiang C, Kong R, Lu J, Pichardo J, Prongay A, Skelton A, Tong X, Venkatraman S, Xia E, Girijavallabhan V, Njoroge GF., a mechanismbased inhibitor of hepatitis C virus NS3 protease, suppresses polyprotein maturation and enhances the antiviral activity of interferon in replicon cells. Antimicrob Agents Chemother 2006; 50: Cancer Therapy Evaluation Program. Common terminology criteria for adverse events v3.0 (CTCAE). Publish Date: December 12, Available at: Accessed May 29, Glue P, Rouzier-Panis R, Raffanel C, Sabo C, Gupta SK, Salfi M, Jacobs S, Clement RP. A dose-ranging study of pegylated interferon alfa-2b and ribavirin in chronic hepatitis C. Hepatology 2000;32: Silva M, Poo J, Wagner F, Jackson M, Cutler D, Grace M, Bordens R, Cullen C, Harvey J, Laughlin M. A randomised trial to compare the pharmacokinetic, pharmacodynamic, and antiviral effects of peginterferon alfa-2b and peginterferon alfa-2a in patients with chronic hepatitis C (COMPARE). J Hepatol 2006;45: Gosert R, Egger D, Lohmann V, Bartenschlager R, Blum HE, Bienz K, Moradpour D. Identification of the hepatitis C virus RNA replication complex in Huh-7 cells harboring subgenomic replicons. J Virol 2003;77: Received August 30, Accepted December 14, Address requests for reprints to: Stefan Zeuzem, MD, Professor of Medicine, J.W. Goethe-University Hospital, Medizinische Klinik I, Frankfurt am Main, Germany. zeuzem@em.uni-frankfurt.de; fax: (49) This study was carried out by Schering-Plough Research Institute as part of the clinical development program for. A.S. s present affiliation is Johnson & Johnson, Raritan, New Jersey. J.Z. s present affiliation is Bristol-Myers Squibb, Princeton, New Jersey. The authors thank Janelle Landau, PhD, and Elizabeth Downs for their assistance in preparation of the manuscript.