Relation of cetuximab-induced skin toxicity and early tumor shrinkage in metastatic colorectal cancer patients: results of the randomized phase 3 trial FIRE-3 (AIO KRK0306).

BACKGROUND: Cetuximab-induced skin toxicity (Cet-ST) is positively associated with outcome in metastatic colorectal cancer (mCRC). Besides its predictive relevance for targeted therapy, we investigated its prognostic impact with early tumor shrinkage (ETS) ≥20%, another on-treatment surrogate for clinical outcome in FIRE-3. PATIENTS AND METHODS: FIRE-3 evaluated first-line FOLFIRI (folinic acid, fluorouracil and irinotecan) plus cetuximab (FOLFIRI/Cet) versus FOLFIRI plus bevacizumab (FOLFIRI/Bev) in mCRC patients with RAS-WT tumors (i.e. wild-type in KRAS and NRAS exons 2-4). Retrospective data on Cet-ST that occurred during cycles 1-3 of treatment were correlated with efficacy endpoints, including ETS. To control for guarantee-time bias, only patients who had completed three or more treatment cycles were considered. RESULTS: Of 199 patients treated with FOLFIRI/Cet, 181 (91.0%) completed three or more treatment cycles. A significant survival benefit of FOLFIRI/Cet over FOLFIRI/Bev was only evident in patients developing Cet-ST grade 2-3 [41.0 versus 26.6 months; hazard ratio (HR) = 0.73; 95% confidence interval (CI): 0.61-0.87; P < 0.001] compared with Cet-ST grade 0-1 (HR = 0.90; 95% CI: 0.67-1.20; P = 0.48). Regarding prognosis, Cet-ST grade 2-3 (n = 75; 41.4%), compared with Cet-ST grade 0-1 (n = 106; 58.6%), was associated with prolonged overall survival (OS; HR = 0.62; 95% CI: 0.42-0.91; P = 0.01). In multivariate analysis, both Cet-ST (HR = 0.66; 95% CI: 0.50-0.87; P = 0.003) and ETS (HR = 0.55; 95% CI: 0.41-0.74; P < 0.0001) were independently prognostic for OS. Absence of both Cet-ST grade ≥2 and ETS identified a subgroup of patients with very poor prognosis (median OS 15.1 months). CONCLUSIONS: In FIRE-3, the addition of cetuximab to FOLFIRI was associated with superior OS compared with FOLFIRI/Bev only in patients developing Cet-ST grade ≥2. Regarding prognostic relevance, both Cet-ST and ETS were independent and early predictors of survival. The present analysis supports that a combined evaluation of on-treatment parameters such as Cet-ST and ETS may help to guide treatment of mCRC.

Consensus molecular subgroups (CMS) of colorectal cancer (CRC) and first-line efficacy of FOLFIRI plus cetuximab or bevacizumab in the FIRE3 (AIO KRK-0306) trial.

BACKGROUND: FIRE-3 compared first-line therapy with FOLFIRI plus either cetuximab or bevacizumab in 592 KRAS exon 2 wild-type metastatic colorectal cancer (mCRC) patients. The consensus molecular subgroups (CMS) are grouping CRC samples according to their gene-signature in four different subtypes. Relevance of CMS for the treatment of mCRC has yet to be defined. PATIENTS AND METHODS: In this exploratory analysis, patients were grouped according to the previously published tumor CRC-CMSs. Objective response rates (ORR) were compared using chi-square test. Overall survival (OS) and progression-free survival (PFS) times were compared using Kaplan-Meier estimation, log-rank tests. Hazard ratios (HR) were estimated according to the Cox proportional hazard method. RESULTS: CMS classification could be determined in 438 out of 514 specimens available from the intent-to-treat (ITT) population (n = 592). Frequencies for the remaining 438 samples were as follows: CMS1 (14%), CMS2 (37%), CMS3 (15%), CMS4 (34%). For the 315 RAS wild-type tumors, frequencies were as follows: CMS1 (12%), CMS2 (41%), CMS3 (11%), CMS4 (34%). CMS distribution in right- versus (vs) left-sided primary tumors was as follows: CMS1 (27% versus 11%), CMS2 (28% versus 45%), CMS3 (10% versus 12%), CMS4 (35% versus 32%). Independent of the treatment, CMS was a strong prognostic factor for ORR (P = 0.051), PFS (P < 0.001), and OS (P < 0.001). Within the RAS wild-type population, OS observed in CMS4 significantly favored FOLFIRI cetuximab over FOLFIRI bevacizumab. In CMS3, OS showed a trend in favor of the cetuximab arm, while OS was comparable in CMS1 and CMS2, independent of targeted therapy. CONCLUSIONS: CMS classification is prognostic for mCRC. Prolonged OS induced by FOLFIRI plus cetuximab versus FOLFIRI plus bevacizumab in the FIRE-3 study appears to be driven by CMS3 and CMS4. CMS classification provides deeper insights into the biology to CRC, but at present time has no direct impact on clinical decision-making.The FIRE-3 (AIO KRK-0306) study had been registered at ClinicalTrials.gov: NCT00433927.

Relevance of baseline carcinoembryonic antigen for first-line treatment against metastatic colorectal cancer with FOLFIRI plus cetuximab or bevacizumab (FIRE-3 trial).

PURPOSE: Increased baseline carcinoembryonic antigen (CEA) serum level is associated with inferior overall survival (OS) in metastatic colorectal cancer (mCRC). However, limited data exist on its predictive relevance for targeted therapies. Therefore, we analysed its relevance in FIRE-3, a randomised phase III study. EXPERIMENTAL DESIGN: FIRE-3 evaluated first-line FOLFIRI plus cetuximab (FOLFIRI/Cet) versus FOLFIRI plus bevacizumab (FOLFIRI/Bev) in mCRC patients with RAS-WT tumour (i.e. wild-type in KRAS and NRAS exons 2-4). Herein, the impact of CEA on patient outcome was investigated. RESULTS: Of 400 patients, 356 (89.0%) were evaluable for CEA. High CEA (>10 ng/ml; N = 237) compared to low CEA (≤10 ng/ml; N = 119) was associated with shorter OS in the FOLFIRI/Bev arm (hazard ratio [HR] = 1.50; P = 0.036), while no significant OS difference was observed in the FOLFIRI/Cet arm (HR = 1.07; P = 0.74). In patients with high CEA, FOLFIRI/Cet compared to FOLFIRI/Bev showed a greater OS benefit (HR = 0.56; P < 0.001) than in patients with low CEA (HR = 0.78; P = 0.30). Furthermore, FOLFIRI/Cet exhibited significantly superior objective response rate in patients with high CEA (odds ratio = 2.21; P = 0.006) in contrast to patients with low CEA (odds ratio = 0.90; P = 0.85). CONCLUSION: In patients with RAS-WT mCRC receiving first-line chemotherapy with FOLFIRI/Cet versus FOLFIRI/Bev, elevated CEA was associated with inferior survival in the bevacizumab arm, while this was not the case when cetuximab was applied. Comparison of OS and objective response rate according to treatment arms indicated that cetuximab was greatly superior to bevacizumab in patients with elevated CEA, while this effect was markedly lower and lost statistical significance in patients with low CEA.

Evaluation of survival across several treatment lines in metastatic colorectal cancer: Analysis of the FIRE-3 trial (AIO KRK0306).

BACKGROUND: We explored the impacts of sequential application of various treatment lines on survival kinetics. Therefore, differences in overall survival (OS) observed in FIRE-3 were investigated in the context of time and exposure to applied treatment. PATIENTS AND METHODS: OS analyses (stratified by treatment with FOLFIRI plus either cetuximab or bevacizumab) were performed according to time intervals as well as using a Cox model to define changes of hazard ratio (HR) over time. RESULTS: The fraction of patients with systemic treatment and time on treatment markedly decreases over treatment lines and time. OS evaluation by a Cox model indicated a trend towards a non-proportional hazard between treatment arms (P = 0.12/P = 0.09 for KRAS-intention-to-treat (ITT)/all-RAS wild-type populations, respectively). To improve the fit of the model, a change-point (point of curve separation) was estimated at 22.6 months (day 687) after randomisation. The HR between the two arms before 22.6 months was not significantly different from one. However, markedly different survival kinetics in favour of the cetuximab arm were apparent after the change-point (KRAS-ITT: P = 0.0018; HR, 0.60 [95% confidence interval [CI], 0.44-0.83] and RAS: P = 0.0006; HR, 0.51 [95% CI, 0.35-0.75]). CONCLUSION: The differences in OS favouring the cetuximab arm become apparent about 22.6 months after randomisation, indicating that only those patients who survive 22.6 months after randomisation benefit from the superiority of the cetuximab arm. When OS curves separate, only few patients receive active systemic treatment in short courses, suggesting that earlier treatment effects are responsible for later kinetics of survival curves.

Impact of BRAF and RAS mutations on first-line efficacy of FOLFIRI plus cetuximab versus FOLFIRI plus bevacizumab: analysis of the FIRE-3 (AIO KRK-0306) study.

BACKGROUND: RAS and BRAF mutations have been identified as negative prognostic factors in metastatic colorectal cancer. Efficacy of 5-fluorouracil, leucovorin, irinotecan (FOLFIRI) plus bevacizumab in patients with RAS-mutant tumours needs to be further evaluated. Whether to treat patients with BRAF-mutant tumours with either bevacizumab or anti-epidermal growth factor receptor (EGFR) antibodies remains unclear. METHODS: Patients treated within the FIRE-3 trial were retrospectively tested for BRAF and RAS mutations using formalin fixated paraffin embedded (FFPE) tumour material applying pyrosequencing for KRAS and NRAS exon 2, 3 and 4 mutations as far as for BRAF mutations. Survival analysis was done using Kaplan-Meier estimation and differences were expressed using the log-rank test. Overall response rate (ORR) was compared using Fisher's exact test. Data from a central independent radiological response evaluation were used to calculate early tumour shrinkage (ETS) and depth of response (DpR). RESULTS: Overall, 188 patients with RAS-mutant tumours and 48 with BRAF-mutant tumours were identified. In BRAF-mutant patients, ORR was numerically higher in the cetuximab versus the bevacizumab arm (52% versus 40%), while comparable results were achieved for progression-free survival (PFS; hazard ratio [HR] = 0.84, p = 0.56) and overall survival (OS; HR 0.79, p = 0.45). RAS mutation was associated with a trend towards lower ORR (37% versus 50.5%, p = 0.11) and shorter PFS (7.4 versus 9.7 months; HR 1.25; p = 0.14) in patients receiving FOLFIRI plus cetuximab versus bevacizumab, but OS was comparable (19.1 versus 20.1 months; HR 1.05; p = 0.73), respectively. ETS identified subgroups sensitive to cetuximab-based treatment in both BRAF- (9/17) and RAS-mutant (18/48) patients and was associated with significantly longer OS. DpR was comparable between both treatment arms in RAS- and BRAF-mutant patients, respectively. CONCLUSIONS: In BRAF- and RAS-mutant patients, cetuximab- and bevacizumab-based treatment had comparable survival times. ETS represents an early parameter associated with the benefit from anti-EGFR, while this was not the case with vascular endothelial growth factor A blockade.

CEA response is associated with tumor response and survival in patients with KRAS exon 2 wild-type and extended RAS wild-type metastatic colorectal cancer receiving first-line FOLFIRI plus cetuximab or bevacizumab (FIRE-3 trial).

BACKGROUND: To examine the relation of carcinoembryonic antigen (CEA) response with tumor response and survival in patients with (K)RAS wild-type metastatic colorectal cancer receiving first-line chemotherapy in the FIRE-3 trial comparing FOLFIRI plus cetuximab versus FOLFIRI plus bevacizumab. PATIENTS AND METHODS: CEA response assessed as the percentage of CEA decrease from baseline to nadir was evaluated for its association with tumor response and survival. Receiver operating characteristic analysis revealed an optimal cut-off value of 75% using the maximum of sensitivity and specificity for CEA response to discriminate CEA responders from non-responders. In addition, the time to CEA nadir was calculated. RESULTS: Of 592 patients in the intent-to-treat population, 472 were eligible for analysis of CEA (cetuximab arm: 230 and bevacizumab arm: 242). Maximal relative CEA decrease (%) significantly (P = 0.003) differed between the cetuximab arm (median 83.0%; IQR 40.9%-94.7%) and the bevacizumab arm (median 72.3%; IQR 26.3%-91.0%). In a longitudinal analysis, the CEA decrease occurred faster in the cetuximab arm and was greater than in the bevacizumab arm at all evaluated time points until 56 weeks after treatment start. CEA nadir occurred after 3.3 months (cetuximab arm) and 3.5 months (bevacizumab arm), (P = 0.49). In the cetuximab arm, CEA responders showed a significantly longer progression-free survival [11.8 versus 7.4 months; hazard ratio (HR) 1.53; 95% Cl, 1.15-2.04; P = 0.004] and longer overall survival (36.6 versus 21.3 months; HR 1.73; 95% Cl, 1.24-2.43; P = 0.001) than CEA non-responders. Analysis of extended RAS wild-type patients revealed similar results. CONCLUSION: In the FIRE-3 trial, CEA decrease was significantly faster and greater in the cetuximab arm than in the bevacizumab arm and correlated with the prolonged survival observed in patients receiving FOLFIRI plus cetuximab. CLINICAL TRIALS NUMBER: NCT00433927 (ClinicalTrials.gov); AIO KRK0306 FIRE-3.

FOLFIRI plus cetuximab versus FOLFIRI plus bevacizumab as first-line treatment for patients with metastatic colorectal cancer-subgroup analysis of patients with KRAS: mutated tumours in the randomised German AIO study KRK-0306.

BACKGROUND: The AIO KRK-0306 trial compares the efficacy of infusional 5-fluorouracil, folinic acid, irinotecan (FOLFIRI) plus cetuximab with FOLFIRI plus bevacizumab in first-line treatment of metastatic colorectal cancer (mCRC). In October 2008, an amendment terminated the inclusion of patients with KRAS-mutated tumours. This subgroup of patients is evaluated in the present analysis, while the study is ongoing for patients with KRAS wild-type tumours. METHODS: Patients were randomly assigned to FOLFIRI (Tournigand regimen) every 2 weeks plus cetuximab (400 mg/m2 day 1, followed by 250 mg/m2 weekly=arm A) or bevacizumab (5 mg/kg every 2 weeks=arm B). Among 336 randomised patients, KRAS mutation was demonstrated in 100 assessable patients. The primary study end point was objective response rate (ORR). RESULTS: ORR was 44% [95% confidence interval (CI) 29% to 59%] in arm A versus 48% (95% CI, 33% to 62%) in arm B. Progression-free survival was 7.5 versus 8.9 months (hazard ratio: 1.0) and overall survival was 22.7 versus 18.7 months (hazard ratio: 0.86) in arms A versus B, respectively. CONCLUSIONS: This is the first head to head comparison of cetuximab versus bevacizumab in first-line treatment of mCRC. In the present evaluation of patients with KRAS-mutated tumours, neither strategy demonstrated a clearly superior outcome.

[Endoscopic therapy for leaks in the gastrointestinal tract, the bile ducts and the pancreas]. / Endoskopische Therapie von Leckagen im Gastrointestinaltrakt, an den Gallenwegen und im Pankreas.

Surgery has been the mainstay of therapy in patients with gastrointestinal perforations, leakage or fistulas. New techniques for endoscopic closure of gastrointestinal perforations provide tools for an effective treatment by less invasive procedures. Temporary placement of covered self-expanding stents is an established therapy for oesophageal perforations and anastomotic leaks. Using conventional endoclips small perforations and leaks in the oesophagus and gastrointestinal tract may be closed. With the new over-the-scope-clips a more effective endoscopic full wall closure is possible in the upper gastrointestinal tract and the rectum. Endoscopically guided endoluminal vacuum therapy using polyurethane sponges is an established method for treating rectal leaks and is now increasingly used also in oesophageal leaks. Biliary leakage following endoscopic or surgical interventions is effectively treated with temporary bile stenting in most cases, but closure using metal stents or coiling may be necessary. Pancreatic leaks are a major therapeutic problem and may require multimodal therapies.

Therapy outcome in patients with chronic hepatitis C: role of therapy supervision by expert hepatologists.

Previous large multicentre trials reported sustained virological response (SVR) rates of 45-80% in chronically infected hepatitis C virus (HCV) patients. However, it is unclear whether such a treatment success is also achieved in daily routine and to what extent it depends on expert hepatological supervision. This was retrospectively analysed in patients presenting at our outpatient department during May 1997 and March 2004 and receiving at least one treatment dose. A total of 302 treatment-naive HCV patients [72% genotypes 1 or 4 (n = 215), 25% genotypes 2/3 (n = 78) and 3% undetermined genotype (n = 9)] were included in the analysis. Out of these, 196 patients consulted an expert hepatologist at least once every 3 months during treatment [regular visitors (RV)], whereas in 106 patients treatment was performed and supervised by a general practitioner (irregular visitors). Both patient groups did not differ in their baseline characteristics. However, the virological response rates at the end of treatment (ETR; 146/196, 74%vs 51/106, 48%, P < 0.001) and 6 months thereafter (SVR; 129/196, 66%vs 36/106, 34%, P < 0.001) were significantly higher in RV. In patients treated with pegylated-interferon (PEG-IFN)/ribavirin, this difference was statistically highly significant (P < 0.001) for HCV genotypes 1 and 4 (treated patients: SVR: 62/101, 61%vs 14/51, 27%, P < 0.001), but not for genotypes 2/3. SVR rates were also significantly better in RV with advanced liver damage [SVR 69% (22/32) vs 25% (5/20), P = 0.004]. In regular and irregular visitors treatment was discontinued in 7% (14/196) and 15% (16/106) respectively (P = 0.015). Patients with unfavourable genotypes 1 and 4 or with advanced liver damage benefit from HCV therapy supervision by a specialist, probably because of less frequent treatment interruptions or dose reductions.

A multimodal approach in coil embolization of a bile leak following cholecystectomy.

Bile leak is a well-known complication of cholecystectomy. Endoscopic drainage and decompression of the biliary system including temporary insertion of a biliary stent is generally considered the treatment of choice. We report the successful obliteration of a bile leak using fibered platinum coils placed under fluoroscopic guidance after stent treatment had failed.

[Current treatment of hepatitis C virus infection]. / Aktuelle Therapie der Hepatitis-C-Virus-Infektion.

New strategies have led to better results in the treatment of HCV infection during the last few years. At present the recommended treatment for patients with chronic hepatitis C is a combination of pegylated interferon and ribavirin. The sustained virological response rate of this combination therapy is 42 - 48 % for patients with genotype 1 after a course of 48 weeks and 80 % for patients with genotype 2 or 3 after a course of 24 weeks. New nucleoside analogs may lead to a better tolerance and better outcomes. A new approach is the long term monotherapy with pegylated interferon in order to reduce the progression of fibrosis and the incidence of cirrhotic complications. At present the effectivity of protease inhibitors and of a therapeutic immunisation with the E1 envelope protein of the hepatitis C virus are being examined. Because the optimal treatment strategy for patients with an acute hepatitis C infection is still unclear, these patients should be included in clinical studies.

Response to interferon alfa is hepatitis B virus genotype dependent: genotype A is more sensitive to interferon than genotype D.

BACKGROUND AND AIMS: Current interferon alfa (IFN) treatment of chronic hepatitis B has limited efficacy. The role of hepatitis B virus (HBV) genotypes for response to IFN was investigated. PATIENTS AND METHODS: HBV genotype was determined by direct sequencing of the HBV X gene in 165 consecutive patients with chronic replicative hepatitis B treated with standard IFN. HBV genotype A or D was found in 144 cases. RESULTS: Sustained response (six months after treatment) to standard IFN therapy was higher in HBV genotype A compared with HBV genotype D infected patients (49% v 26%; p<0.005). Sustained response to IFN was 46% versus 24% (p<0.03) in hepatitis B e antigen (HBeAg) positive hepatitis (n = 99) and 59% versus 29% (p<0.05) in HBeAg negative hepatitis (n = 45) for HBV genotype A compared with HBV genotype D. HBeAg status had no negative impact on IFN response. Multivariate logistic regression identified HBV genotype A and high pretreatment alanine aminotransferase levels (>2 x upper limit of normal) as independent positive predictive parameters of IFN response. CONCLUSIONS: The present study indicates that HBV genotypes A and D are important and independent predictors of IFN responsiveness in chronic hepatitis B. HBV genotype adapted treatment regimens may further improve treatment efficacy in chronic hepatitis B.

Socioepidemiological data on hepatitis delta in a German university clinic--increase in patients from Eastern Europe and the former Soviet Union.

BACKGROUND AND AIMS: The relevance of chronic hepatitis delta results from its high morbidity leading frequently to rapid cirrhosis progression. The aim of the present study was the socioepidemiological characterization of patients with hepatitis delta, in order to identify patients at risk for hepatitis delta. PATIENTS AND METHODS: Clinical parameters of 36 consecutive patients with chronic hepatitis delta, seen between 1989 and 2002 at the University Hospital in Düsseldorf, were evaluated for the present study. Socioepidemiological parameters, available in 31 of these patients who returned a questionnaire, were compared to data of the population of Nordrhein-Westfalen (NRW). RESULTS: Liver cirrhosis was found in 33.3% of patients. There was a mean delay of 3 years between the diagnosis of hepatitis B and D. Patients with delta hepatitis were characterized by lower education, were more frequently unemployed, exhibited less qualified work and had less property compared to the population of NRW. 86.1% of hepatitis delta patients were immigrants to Germany. Before 1995 hepatitis delta infections were mainly seen in patients from Southern Europe (75%), whereas after 1996 predominantly patients from Eastern Europe and the former Soviet Union (53.6%; p < 0.04) contributed to the newly diagnosed cases of hepatitis delta. CONCLUSIONS: The present data underline that hepatitis delta is a severe disease. It seems reasonable to intensify screening for hepatitis delta among patients with low socioeconomic status, especially among immigrants of Eastern Europe and the former Soviet Union.

[Hepatocellular carcinoma: rising incidence of hepatitis C virus-associated cases at a university clinic in Germany]. / Hepatozelluläres Karzinom - Steigende Inzidenz der Hepatitis-C-bedingten Fälle einer Universitätsklinik in Deutschland.

BACKGROUND AND OBJECTIVE: Hepatocellular carcinoma (HCC) ranks eighth among malignant tumors worldwide. Western countries belong to areas of low HCC prevalence, but incidence of HCC is rising. The aim of the present, retrospective study was to determine changes in the incidence rates and risk factors for HCC in Germany based on the data of a single center. PATIENTS AND METHODS: Epidemiological data of 205 consecutive patients with HCC (163 males, 42 females, mean age 64+/-1 years), admitted to the University clinic Düsseldorf between January 1988 and December 2001, were evaluated. For comparison this time period was divided into two equal intervals (1988 - 1994 and 1995 - 2001). RESULTS: The number of newly diagnosed HCC has more than doubled in the years 1995 - 2001 compared to the years 1988 - 1994. Chronic hepatitis C (HCV), hepatitis B (HBV), and chronic alcohol abuse accounted for almost 80 % of HCC. The number of HCV-associated HCC increased from 31.0 % in the years 1990 - 1995 to 44.6 % (p < 0.04) in the years 1996 - 2001, whereas the proportion of HBV-associated HCC decreased. There were no changes in the Okuda tumor stage, tumor diameter and alpha-fetoprotein levels at the time of HCC diagnosis throughout the years 1988 - 2001. More than 65 % of HCC were non-resectable at the time of HCC diagnosis due to tumor diameter or number of tumor lesions. CONCLUSION: Screening for HCC, possibly rising in its incidence, should be further improved, taking into account that chronic HCV infection is the major risk factor for HCC in Germany.

Inhibition of hepatitis C virus NS3 function by antisense oligodeoxynucleotides and protease inhibitor.

Hepatitis C Virus (HCV) NS3 protease is an attractive target for antiviral agent development because it is required for viral replication. Because a stable cell culture system or small animal model to study HCV replication is not readily available, we constructed an in vitro model allowing the investigation of NS3 transcription, translation, and protease function. Sequences encoding for full length HCV genomes were cloned and transfected into HuH-7 human hepatocellular carcinoma cells to analyze NS3 transcription/translation. A plasmid pHCV ORF I luc that expresses the complete HCV coding region upstream of a luciferase reporter gene was designed to enable quantification of translated HCV proteins. Additionally, NS3 protease function was assessed by direct coexpression of NS3 and NS5 in HuH 7 cells, and the subsequent measurement of cleavage products. We found that antisense oligodeoxynucleotides (AS-ODN) interfered with NS3 translation in a dose dependent fashion; AS-ODN 5 cotransfection directed against NS3 sequences significantly inhibited protease activity as measured by cleaved NS5A levels. Finally, cleaved NS5A levels served as anindex of protease activity and Chymostatin, a protease inhibitor, almost completely blocked NS3 enzymatic activity. This cell culture system is useful in the assessment of potential antiviral agents on HCV NS3 expression and function.