Risk factors for EUS-guided radiofrequency ablation adverse events in patients with pancreatic neoplasms: a large national French study (RAFPAN study).

BACKGROUND AND AIMS: EUS-guided radiofrequency ablation (EUS-RFA) has been described as a potentially curative option for solid and cystic pancreatic neoplasms. We aimed to assess the safety and efficacy of pancreatic EUS-RFA in a large study population. METHODS: A retrospective study retrieving all consecutive patients who underwent pancreatic EUS-RFA during 2019 and 2020 in France was conducted. Indication, procedural characteristics, early and late adverse events (AEs), and clinical outcomes were recorded. Risk factors for AEs and factors related to complete tumor ablation were assessed on univariate and multivariate analyses. RESULTS: One hundred patients (54% men, 64.8 ± 17.6 years old) affected by 104 neoplasms were included. Sixty-four neoplasms were neuroendocrine neoplasms (NENs), 23 were metastases, and 10 were intraductal papillary mucinous neoplasms with mural nodules. No procedure-related mortality was observed, and 22 AEs were reported. Proximity of pancreatic neoplasms (≤1 mm) to the main pancreatic duct was the only independent risk factor for AEs (odds ratio [OR), 4.10; 95% confidence interval [CI), 1.02-15.22; P = .04). Fifty-nine patients (60.2%) achieved a complete tumor response, 31 (31.6%) a partial response, and 9 (9.2%) achieved no response. On multivariate analysis, NENs (OR, 7.95; 95% CI, 1.66-51.79; P < .001) and neoplasm size <20 mm (OR, 5.26; 95% CI, 2.17-14.29; P < .001) were independently related to complete tumor ablation. CONCLUSIONS: The results of this large study confirm an overall acceptable safety profile for pancreatic EUS-RFA. Close proximity (≤1 mm) to the main pancreatic duct represents an independent risk factor for AEs. Good clinical outcomes in terms of tumor ablation were observed, especially for small NENs.

Clinical outcomes after treatment with direct antiviral agents: beyond the virological response in patients with previous HCV-related decompensated cirrhosis.

BACKGROUND: In HCV-infected patients with advanced liver disease, the direct antiviral agents-associated clinical benefits remain debated. We compared the clinical outcome of patients with a previous history of decompensated cirrhosis following treatment or not with direct antiviral agents from the French ANRS CO22 HEPATHER cohort. METHODS: We identified HCV patients who had experienced an episode of decompensated cirrhosis. Study outcomes were all-cause mortality, liver-related or non-liver-related deaths, hepatocellular carcinoma, liver transplantation. Secondary study outcomes were sustained virological response and its clinical benefits. RESULTS: 559 patients met the identification criteria, of which 483 received direct antiviral agents and 76 remained untreated after inclusion in the cohort. The median follow-up time was 39.7 (IQR: 22.7-51) months. After adjustment for multivariate analysis, exposure to direct antiviral agents was associated with a decrease in all-cause mortality (HR 0.45, 95% CI 0.24-0.84, p = 0.01) and non-liver-related death (HR 0.26, 95% CI 0.08-0.82, p = 0.02), and was not associated with liver-related death, decrease in hepatocellular carcinoma and need for liver transplantation. The sustained virological response was 88%. According to adjusted multivariable analysis, sustained virological response achievement was associated with a decrease in all-cause mortality (HR 0.29, 95% CI 0.15-0.54, p < 0.0001), liver-related mortality (HR 0.40, 95% CI 0.17-0.96, p = 0.04), non-liver-related mortality (HR 0.17, 95% CI 0.06-0.49, p = 0.001), liver transplantation (HR 0.17, 95% CI 0.05-0.54, p = 0.003), and hepatocellular carcinoma (HR 0.52, 95% CI 0.29-0.93, p = 0.03). CONCLUSION: Treatment with direct antiviral agents is associated with reduced risk for mortality. The sustained virological response was 88%. Thus, direct antiviral agents treatment should be considered for any patient with HCV-related decompensated cirrhosis. TRIAL REGISTRATION:  ClinicalTrials.gov registry number: NCT01953458.

A Placebo-Controlled Trial of Bezafibrate in Primary Biliary Cholangitis.

BACKGROUND: Patients with primary biliary cholangitis who have an inadequate response to therapy with ursodeoxycholic acid are at high risk for disease progression. Fibrates, which are agonists of peroxisome proliferator-activated receptors, in combination with ursodeoxycholic acid, have shown potential benefit in patients with this condition. METHODS: In this 24-month, double-blind, placebo-controlled, phase 3 trial, we randomly assigned 100 patients who had had an inadequate response to ursodeoxycholic acid according to the Paris 2 criteria to receive bezafibrate at a daily dose of 400 mg (50 patients), or placebo (50 patients), in addition to continued treatment with ursodeoxycholic acid. The primary outcome was a complete biochemical response, which was defined as normal levels of total bilirubin, alkaline phosphatase, aminotransferases, and albumin, as well as a normal prothrombin index (a derived measure of prothrombin time), at 24 months. RESULTS: The primary outcome occurred in 31% of the patients assigned to bezafibrate and in 0% assigned to placebo (difference, 31 percentage points; 95% confidence interval, 10 to 50; P<0.001). Normal levels of alkaline phosphatase were observed in 67% of the patients in the bezafibrate group and in 2% in the placebo group. Results regarding changes in pruritus, fatigue, and noninvasive measures of liver fibrosis, including liver stiffness and Enhanced Liver Fibrosis score, were consistent with the results of the primary outcome. Two patients in each group had complications from end-stage liver disease. The creatinine level increased 5% from baseline in the bezafibrate group and decreased 3% in the placebo group. Myalgia occurred in 20% of the patients in the bezafibrate group and in 10% in the placebo group. CONCLUSIONS: Among patients with primary biliary cholangitis who had had an inadequate response to ursodeoxycholic acid alone, treatment with bezafibrate in addition to ursodeoxycholic acid resulted in a rate of complete biochemical response that was significantly higher than the rate with placebo and ursodeoxycholic acid therapy. (Funded by Programme Hospitalier de Recherche Clinique and Arrow Génériques; BEZURSO ClinicalTrials.gov number, NCT01654731 .).

Sustained Remission After Treatment Withdrawal in Autoimmune Hepatitis: A Multicenter Retrospective Study.

BACKGROUND: In patients with autoimmune hepatitis (AIH), relapse rates between 25 and 100% after treatment withdrawal have been reported. The optimal strategy for immunosuppressive treatment withdrawal is controversial. AIM: To identify the predictive factors of histological remission and to assess the relapse rate after treatment withdrawal in AIH patients with prolonged biochemical response. METHODS: Patients with AIH and sustained biochemical remission on first-line treatment were retrospectively included. Histological response was defined as complete regression of interface hepatitis and lobular necrosis and no or minimal portal inflammation and relapse as any elevation of serum aminotransferase or gammaglobulin/IgG levels. RESULTS: Sixty-two patients were included. Forty-seven had a biopsy after a median biochemical response of 49.7 months. Twenty-five of them were histological responders. Independent predictors of histological remission were older age (OR = 1.1; CI 95%: 1.0; 1.2), mild-to-moderate fibrosis at diagnosis (OR = 8; CI: 1.4; 47.6) and aspartate aminotransferases < 0.6 × ULN (OR = 7.1; CI: 1.3; 36.7). Thirty-nine patients stopped therapy after a median biochemical response of 48.6 months. Twenty-four of them had a biopsy before treatment withdrawal: 21 were histological responders. The cumulative rate of relapse was 25% at 64 months. CONCLUSIONS: This study indicates that older age, mild-to-moderate fibrosis at diagnosis and serum aspartate aminotransferases in the lower range of normal are independent predictors of histological response in AIH with prolonged biochemical response. The relapse rate after treatment withdrawal may be limited to 25% at 64 months when patients are selected on the basis of prolonged biochemical remission and, when available, histological response.

Clinical outcomes in patients with chronic hepatitis C after direct-acting antiviral treatment: a prospective cohort study.

BACKGROUND: Although direct-acting antivirals have been used extensively to treat patients with chronic hepatitis C virus (HCV) infection, their clinical effectiveness has not been well reported. We compared the incidence of death, hepatocellular carcinoma, and decompensated cirrhosis between patients treated with direct-acting antivirals and those untreated, in the French ANRS CO22 Hepather cohort. METHODS: We did a prospective study in adult patients with chronic HCV infection enrolled from 32 expert hepatology centres in France. We excluded patients with chronic hepatitis B, those with a history of decompensated cirrhosis, hepatocellular carcinoma, or liver transplantation, and patients who were treated with interferon-ribavirin with or without first-generation protease inhibitors. Co-primary study outcomes were incidence of all-cause mortality, hepatocellular carcinoma, and decompensated cirrhosis. The association between direct-acting antivirals and these outcomes was quantified using time-dependent Cox proportional hazards models. This study is registered with ClinicalTrials.gov, number NCT01953458. FINDINGS: Between Aug 6, 2012, and Dec 31, 2015, 10 166 patients were eligible for the study. 9895 (97%) patients had available follow-up information and were included in analyses. Median follow-up was 33·4 months (IQR 24·0-40·7). Treatment with direct-acting antivirals was initiated during follow-up in 7344 patients, and 2551 patients remained untreated at the final follow-up visit. During follow-up, 218 patients died (129 treated, 89 untreated), 258 reported hepatocellular carcinoma (187 treated, 71 untreated), and 106 had decompensated cirrhosis (74 treated, 32 untreated). Exposure to direct-acting antivirals was associated with increased risk for hepatocellular carcinoma (unadjusted hazard ratio [HR] 2·77, 95% CI 2·07-3·71) and decompensated cirrhosis (3·83, 2·29-6·42). After adjustment for variables (age, sex, body-mass index, geographical origin, infection route, fibrosis score, HCV treatment-naive, HCV genotype, alcohol consumption, diabetes, arterial hypertension, biological variables, and model for end-stage liver disease score in patients with cirrhosis), exposure to direct-acting antivirals was associated with a decrease in all-cause mortality (adjusted HR 0·48, 95% CI 0·33-0·70) and hepatocellular carcinoma (0·66, 0·46-0·93), and was not associated with decompensated cirrhosis (1·14, 0·57-2·27). INTERPRETATION: Treatment with direct-acting antivirals is associated with reduced risk for mortality and hepatocellular carcinoma and should be considered in all patients with chronic HCV infection. FUNDING: INSERM-ANRS (France Recherche Nord & Sud Sida-HIV Hépatites), ANR (Agence Nationale de la Recherche), DGS (Direction Générale de la Santé), MSD, Janssen, Gilead, AbbVie, Bristol-Myers Squibb, and Roche.

HCV-Induced Epigenetic Changes Associated With Liver Cancer Risk Persist After Sustained Virologic Response.

BACKGROUND & AIMS: Chronic hepatitis C virus (HCV) infection is an important risk factor for hepatocellular carcinoma (HCC). Despite effective antiviral therapies, the risk for HCC is decreased but not eliminated after a sustained virologic response (SVR) to direct-acting antiviral (DAA) agents, and the risk is higher in patients with advanced fibrosis. We investigated HCV-induced epigenetic alterations that might affect risk for HCC after DAA treatment in patients and mice with humanized livers. METHODS: We performed genome-wide ChIPmentation-based ChIP-Seq and RNA-seq analyses of liver tissues from 6 patients without HCV infection (controls), 18 patients with chronic HCV infection, 8 patients with chronic HCV infection cured by DAA treatment, 13 patients with chronic HCV infection cured by interferon therapy, 4 patients with chronic hepatitis B virus infection, and 7 patients with nonalcoholic steatohepatitis in Europe and Japan. HCV-induced epigenetic modifications were mapped by comparative analyses with modifications associated with other liver disease etiologies. uPA/SCID mice were engrafted with human hepatocytes to create mice with humanized livers and given injections of HCV-infected serum samples from patients; mice were given DAAs to eradicate the virus. Pathways associated with HCC risk were identified by integrative pathway analyses and validated in analyses of paired HCC tissues from 8 patients with an SVR to DAA treatment of HCV infection. RESULTS: We found chronic HCV infection to induce specific genome-wide changes in H3K27ac, which correlated with changes in expression of mRNAs and proteins. These changes persisted after an SVR to DAAs or interferon-based therapies. Integrative pathway analyses of liver tissues from patients and mice with humanized livers demonstrated that HCV-induced epigenetic alterations were associated with liver cancer risk. Computational analyses associated increased expression of SPHK1 with HCC risk. We validated these findings in an independent cohort of patients with HCV-related cirrhosis (n = 216), a subset of which (n = 21) achieved viral clearance. CONCLUSIONS: In an analysis of liver tissues from patients with and without an SVR to DAA therapy, we identified epigenetic and gene expression alterations associated with risk for HCC. These alterations might be targeted to prevent liver cancer in patients treated for HCV infection.

Interferon-Induced Transmembrane Proteins Mediate Viral Evasion in Acute and Chronic Hepatitis C Virus Infection.

Although adaptive immune responses against hepatitis C virus (HCV) infection have been studied in great detail, the role of innate immunity in protection against HCV infection and immune evasion is only partially understood. Interferon-induced transmembrane proteins (IFITMs) are innate effector proteins restricting host cell entry of many enveloped viruses, including HCV. However, the clinical impact of IFITMs on HCV immune escape remains to be determined. Here, we show that IFITMs promote viral escape from the neutralizing antibody (nAb) response in clinical cohorts of HCV-infected patients. Using pseudoparticles bearing HCV envelope proteins from acutely infected patients, we show that HCV variants isolated preseroconversion are more sensitive to the antiviral activity of IFITMs than variants from patients isolated during chronic infection postseroconversion. Furthermore, HCV variants escaping nAb responses during liver transplantation exhibited a significantly higher resistance to IFITMs than variants that were eliminated posttransplantation. Gain-of-function and mechanistic studies revealed that IFITMs markedly enhance the antiviral activity of nAbs and suggest a cooperative effect of human monoclonal antibodies and IFITMs for antibody-mediated neutralization driving the selection pressure in viral evasion. Perturbation studies with the IFITM antagonist amphotericin B revealed that modulation of membrane properties by IFITM proteins is responsible for the IFITM-mediated blockade of viral entry and enhancement of antibody-mediated neutralization. Conclusion: Our results indicate IFITM proteins as drivers of viral immune escape and antibody-mediated HCV neutralization in acute and chronic HCV infection. These findings are of clinical relevance for the design of urgently needed HCV B-cell vaccines and might help to increase the efficacy of future vaccine candidates.

12 Weeks of a Ribavirin-Free Sofosbuvir and Nonstructural Protein 5A Inhibitor Regimen Is Enough to Treat Recurrence of Hepatitis C After Liver Transplantation.

Sofosbuvir (SOF) combined with nonstructural protein 5A (NS5A) inhibitors has demonstrated its efficacy in treating a recurrence of hepatitis C virus (HCV) after liver transplantation (LT). However, the duration of treatment and need for ribavirin (RBV) remain unclear in this population. Our aim was to determine whether LT recipients could be treated with an SOF + NS5A inhibitor-based regimen without RBV for 12 weeks post-LT. Between October 2013 and December 2015, 699 LT recipients experiencing an HCV recurrence were enrolled in the multicenter ANRS CO23 CUPILT cohort. We selected patients receiving SOF and NS5A inhibitor ± RBV and followed for at least 12 weeks after treatment discontinuation. The primary efficacy endpoint was a sustained virological response 12 weeks after the end of treatment (SVR12). Among these 699 patients, 512 fulfilled the inclusion criteria. Their main characteristics were: 70.1% genotype 1, 18.2% genotype 3, 21.1% cirrhosis, and 34.4% previously treated patients. We identified four groups of patients according to their treatment and duration: SOF + NS5A without RBV for 12 (156 patients) or 24 (239 patients) weeks; SOF + NS5A + RBV for 12 (47 patients) or 24 (70 patients) weeks. SVR12 values reached 94.9%, 97.9%, 95.7%, and 92.9%, respectively (P = 0.14). Only 20 patients experienced a treatment failure. Under multivariate analysis, factors such as fibrosis stage, previous treatment, HCV genotype, and baseline HCV viral load did not influence SVR12 rates in the four groups (P = 0.21). Hematological adverse events (AEs) were more common in the RBV group: anemia (P < 0.0001) and blood transfusion (P = 0.0001). CONCLUSION: SOF + NS5A inhibitors without RBV for 12 weeks constituted reliable therapy for recurrent HCV post-LT with an excellent SVR12 whatever the fibrosis stage, HCV genotype, and previous HCV treatment. (Hepatology 2018; 00:000-000).

Impact of Cytomegalovirus Infection on the Outcome of Patients With Cirrhosis: A Preliminary Study.

GOALS: The aims of this study were to evaluate whether cytomegalovirus (CMV) infection is associated with hepatocellular carcinoma (HCC) and liver-related mortality in cirrhotic patients. BACKGROUND: In cirrhotic patients, the determinants of HCC and liver-related death are imperfectly known. CMV infection, by its prooncogenic and proinflammatory properties, may favor both the development of HCC and deleterious systemic inflammation. STUDY: In the 1178 patients included between June 2008 and December 2012 in the CIrrhose et Risque de Carcinome Hépatocellulaire dans le grand-Est (CIRCE) study, a French multicenter case-control study designed to identify risk factors of HCC among cirrhotic patients, we identified 432 patients with interpretable CMV serological status at baseline. They included 159 cases with HCC and 273 controls. We measured factors associated with HCC at baseline and subsequent HCC in controls, and predictors of overall and liver-related death in the whole study population. RESULTS: During a median follow-up of 31 months, 25 cases of HCC developed in controls, and 209 deaths (163 liver-related) were recorded. There were 247 (57.2%) CMV-seropositive patients. CMV seropositivity was not associated with more frequent HCC at baseline or during follow-up, but among CMV-positive patients with HCC, the proportion of multinodular, infiltrative, or metastatic tumors at diagnosis was higher (73.8% vs. 57.3%; P=0.029), inducing higher mortality (74% vs. 52% at 3 years; P=0.004). By Cox-regression adjusted for age, gender, Model for End-stage Liver Disease (MELD) score, HCC at baseline, and diabetes, CMV seropositivity independently predicted all-cause (hazard ratio=1.45; 95% confidence interval, 1.08-1.94; P=0.013) and liver-related mortality (hazard ratio=1.56; 95% confidence interval, 1.04-2.30; P=0.031). CONCLUSIONS: In this preliminary study, CMV-seropositive cirrhotic patients were at higher risk of liver-related death caused by more aggressive HCCs or severe cirrhosis complications. These findings warrant confirmation.

Improved Bone Safety of Tenofovir Alafenamide Compared to Tenofovir Disoproxil Fumarate Over 2 Years in Patients With Chronic HBV Infection.

BACKGROUND & AIMS: Long-term use of tenofovir disoproxil fumarate (TDF) reduces bone mineral density (BMD). Tenofovir alafenamide (TAF), a new prodrug of tenofovir, has shown non-inferior efficacy to TDF in patients with chronic hepatitis B virus (HBV) infection, with improved bone effects at 48 weeks. We performed a randomized trial to evaluate the bone safety of TAF compared with TDF over 2 years, assessing baseline risk factors for bone loss, were evaluated after 2 years of treatment. METHODS: In a double-blind study, hepatitis B e antigen (HBeAg)-positive patients (n = 873) and HBeAg-negative patients (n = 425) were randomly assigned (2:1) to groups given TAF (25 mg; n = 866) or TDF (300 mg; n = 432) once daily. We assessed bone safety, including hip and spine BMD, using dual-energy X-ray absorptiometry and measured changes in serum markers of bone turnover over 96 weeks. RESULTS: At baseline, treatment groups were well matched. At week 96, patients receiving TAF had significantly smaller decreases in hip BMD (mean reduction of 0.33%) than patients receiving TDF (mean reduction of 2.51%) (P < .001) and spine BMD (reduction of 0.75% in patients receiving patients receiving TAF vs reduction of 2.57% in patients receiving TDF) (P < .001). For hip BMD, the magnitude of difference in bone loss between the TAF and TDF groups increased at week 96 compared to week 48 (P < .001). The TAF group had minimal changes in markers of bone turnover by 12 weeks of treatment, but the TDF group had significant changes, compared to baseline. Risk factors for bone loss had fewer effects in patients receiving TAF than TDF at week 96. CONCLUSIONS: In double-blind randomized trials, we found that after 2 years of treatment, patients receiving TAF had continued improvements in bone safety compared with patients receiving TDF. Clinicaltrial.gov ID NCT01940471 and NCT01940341.

Direct-acting antiviral agent-based regimen for HCV recurrence after combined liver-kidney transplantation: Results from the ANRS CO23 CUPILT study.

Hepatitis C virus (HCV) infection is associated with reduced patient survival following combined liver-kidney transplantation (LKT). The aim of this study was to assess the efficacy and safety of second-generation direct-acting antivirals (DAAs) in this difficult-to-treat population. The ANRS CO23 "Compassionate use of Protease Inhibitors in Viral C Liver Transplantation" (CUPILT) study is a prospective cohort including transplant recipients with recurrent HCV infection treated with DAAs. The present work focused on recipients with recurrent infection following LKT. The study population included 23 patients. All patients received at least one NS5B inhibitor (sofosbuvir) in their antiviral regimen an average of 90 months after LKT. Ninety-six percent of recipients achieved a sustained virological response (SVR) at week 12 (SVR12). In terms of tolerance, 39% of recipients presented with at least one serious adverse event. None of the patients experienced acute rejection during therapy and there were no deaths during follow-up. The glomerular filtration rate (GFR) decreased significantly from baseline to the end of therapy. However, this study did not show that the decline in GFR persisted over time or that it was directly related to DAAs. The DAA-based regimen is well tolerated with excellent results in terms of efficacy. It will become the gold standard for the treatment of recurrent HCV following LKT.

Safety and efficacy of daclatasvir-sofosbuvir in HCV genotype 1-mono-infected patients.

BACKGROUND & AIMS: We report the first real-life results of the sofosbuvir+daclatasvir combination in hepatitis C virus (HCV) genotype 1 infected patients. METHODS: The France REcherche Nord&Sud Sida-hiv Hépatites (ANRS) CO22 HEPATHER "Therapeutic options for hepatitis B and C: A French cohort" is a multicentre observational cohort which aims to include 15,000 HCV- and 10,000 HBV-infected patients. We selected all participants (n=768) with a HCV genotype 1 who initiated sofosbuvir (400mg/day) and daclatasvir (60mg/day) before October 1st 2014, with or without ribavirin (1-1.2g/day) for a duration of 12weeks or 24weeks. The main endpoint criterion was sustained virological response at 12weeks (SVR12), defined by the absence of detectable HCV-RNA 12weeks after the last treatment intake. Missing SVR12 measurements were imputed using SVR24 measurements (n=45), otherwise considered as virological failure (n=18). RESULTS: A SVR12 was obtained in 729/768 (95%) patients, ranging from 92% (12-week sofosbuvir+daclatasvir) to 99% (24-week sofosbuvir+daclatasvir+ribavirin). The SVR12 rates did not significantly differ between the 24-week (550/574 (96%)) and the 12-week (179/194 (92%); p=0.0688) durations or between regimens with (165/169 (98%)) or without ribavirin (564/599 (94%); p=0.0850). The SVR12 rate was greater than 97% in non-cirrhotic patients irrespective of the treatment duration or the addition of ribavirin. Among cirrhotic patients, the SVR12 rate was higher with 24 than 12-week regimen (423/444 (95%) vs. 105/119 (88%); p=0.0054). CONCLUSION: The sofosbuvir+daclatasvir combination is associated with a high rate of SVR12 in patients infected by genotype 1, with an optimal duration of 12weeks in non-cirrhotic and 24weeks in cirrhotic patients. The number of patients receiving ribavirin was too low to adequately assess its impact. LAY SUMMARY: The sofosbuvir+daclatasvir combination of antiviral drugs is associated with a high rate (95%) of viral eradication in patients infected by HCV genotype 1. The best duration of a ribavirin-free sofosbuvir+daclatasvir combination seems to be 12weeks in non-cirrhotic patients and 24weeks for those with cirrhosis. Clinical trial number: NCT01953458.

Apolipoprotein E Mediates Evasion From Hepatitis C Virus Neutralizing Antibodies.

BACKGROUND & AIMS: Efforts to develop an effective vaccine against hepatitis C virus (HCV) have been hindered by the propensity of the virus to evade host immune responses. HCV particles in serum and in cell culture associate with lipoproteins, which contribute to viral entry. Lipoprotein association has also been proposed to mediate viral evasion of the humoral immune response, though the mechanisms are poorly defined. METHODS: We used small interfering RNAs to reduce levels of apolipoprotein E (apoE) in cell culture-derived HCV-producing Huh7.5-derived hepatoma cells and confirmed its depletion by immunoblot analyses of purified viral particles. Before infection of naïve hepatoma cells, we exposed cell culture-derived HCV strains of different genotypes, subtypes, and variants to serum and polyclonal and monoclonal antibodies isolated from patients with chronic HCV infection. We analyzed the interaction of apoE with viral envelope glycoprotein E2 and HCV virions by immunoprecipitation. RESULTS: Through loss-of-function studies on patient-derived HCV variants of several genotypes and subtypes, we found that the HCV particle apoE allows the virus to avoid neutralization by patient-derived antibodies. Functional studies with human monoclonal antiviral antibodies showed that conformational epitopes of envelope glycoprotein E2 domains B and C were exposed after depletion of apoE. The level and conformation of virion-associated apoE affected the ability of the virus to escape neutralization by antibodies. CONCLUSIONS: In cell-infection studies, we found that HCV-associated apoE helps the virus avoid neutralization by antibodies against HCV isolated from chronically infected patients. This method of immune evasion poses a challenge for the development of HCV vaccines.