Ribavirin revisited in the era of direct‐acting antiviral therapy for hepatitis C virus infection

Over the past two decades, ribavirin has been an integral component of treatment for hepatitis C virus (HCV) infection, where it has been shown to improve the efficacy of (pegylated) interferon. However, because of treatment‐limiting side effects and its additive toxicity with interferon, the search for interferon‐ and ribavirin‐free regimens has been underway. The recent approvals of all‐oral direct acting antivirals (DAAs) have revolutionized the HCV therapeutic landscape, and initially it was expected that the role of ribavirin with DAA regimens would be eliminated. On the contrary, what we have witnessed is that ribavirin retains an important role in the optimal treatment of some subgroups of patients, particularly those that historically have been considered the most difficult to cure. Fortunately, it has also been recognized that the safety profile of ribavirin is improved when co‐administered with all‐oral DAA combinations in the absence of interferon. Despite the antiviral mechanism of action of ribavirin being poorly understood, we now have a range of novel insights into the potential role of ribavirin in all‐oral DAA HCV treatment and greater insight into the antiviral mechanism by which it continues to provide clinical benefit for defined patient groups.     

Hepatitis C viraemia reversibly maintains subset of antigen‐specific T‐bet+ tissue‐like memory B cells

Background: Chronic antigen exposure and/or ageing increases the frequency of T‐box expressed in T cells (T‐bet)‐expressing B‐lymphocytes in mice. The frequency and significance of B‐cell T‐bet expression during chronic hepatitis C (HCV) infection in human subjects has never been described. Methods: Healthy controls, cirrhotic and noncirrhotic HCV‐infected patients, and non‐HCV patients with cirrhosis were recruited. Peripheral blood mononuclear cells were phenotyped for expression of T‐bet and related markers by flow cytometry. In a subset of patients who underwent antiviral therapy and were cured of HCV infection (sustained virological response), the dynamics of T‐bet expression in B cells was monitored. After cure, convalescent B cells were tested for T‐bet expression after re‐exposure to infected plasma or recombinant HCV proteins. Results: Forty‐nine patients including 11 healthy donors, 30 hepatitis C‐infected individuals (nine with liver cancer, 13 with cirrhosis, eight without cirrhosis) and eight patients with cirrhosis due to non‐HCV‐related cause were recruited. We found that B cells in patients with chronic HCV exhibited increased frequency of T‐bet+ B cells relative to noninfected individuals (median 11.5% v. 2.2%, P<.0001) but that there were no significant differences between noncirrhotic, cirrhotic and cancer‐bearing infected individuals. T‐Bet⁺ B cells expressed higher levels of CD95, CXCR3, CD11c, CD267 and FcRL5 compared to T‐bet^? B cells and predominantly exhibit a tissue‐like memory CD27^?CD21^? phenotype independent of HCV infection. T‐bet⁺ B cells in HCV‐infected patients were more frequently class‐switched IgD^?IgG⁺ (40.4% vs. 26.4%, P=.012). Resolution of HCV infection with direct‐acting antiviral (DAA) therapy leads to a marked reduction in the frequency of T‐bet⁺ B cells (median 14.1% pretreatment v. 6.7% end of treatment v. 6.1% SVR12, P≤.01). Re‐exposure of convalescent (cured) B cells to viremic plasma and recombinant HCV E2 protein led to re‐expression of T‐bet. Conclusion: Chronic antigenemia in chronic HCV infection induces and maintains an antigen‐specific T‐bet⁺ B cell. These B cells share markers with tissue‐like memory B cells. Antigen‐driven T‐bet expression may be a critical suppressor of B‐cell activation in chronic HCV infection.     

Augmentation of hepatitis C virus‐specific immunity and sustained virologic response

Treatment for chronic hepatitis C virus (HCV) infection has rapidly evolved into interferon‐free directly acting antiviral regimens (DAA) that result in high sustained virologic response. DAAs primarily work by suppressing HCV replication and rely less on the immune system than interferon‐based therapies. However, it is unclear whether the immune system recovers with suppression of HCV replication and contributes to HCV clearance with DAA therapy. We previously demonstrated HCV clearance is associated with increased HCV‐specific immunity in CHCV‐GT‐1‐infected patients during treatment with sofosbuvir (SOF)+ribavirin (RBV). Here, we aimed to analyse changes in HCV‐specific immunological responses associated with viral clearance with combination DAA therapy of SOF+ledipasvir (LDV) for 12 weeks in CHCV‐GT1 (N=14) patients who relapsed without augmentation of HCV‐specific immunity during treatment with SOF+RBV. Phenotypic and functional changes within the T‐cell compartment of PBMCs pre‐ and post‐treatment were analysed. Retreatment of relapsers with LDV/SOF resulted in all patients attaining SVR₁₂. Suppression of HCV was associated with a decline in T‐cell exhaustion markers (CD57; Tim3; PD1) along with augmented of HCV‐specific T‐cell IFN‐gamma responses post‐treatment. Addition of LDV to SOF was associated with augmentation of HCV‐specific immunity and SVR in patients who previously failed SOF+RBV therapy without increased immunity. These findings demonstrate a novel effect of DAA in inducing host immune responses to aid HCV clearance and achieve SVR.     

Eradication of hepatitis C virus could improve immunological status and pyoderma gangrenosum‐like lesions

Hepatitis C virus (HCV) can affect immune cells and induce various kinds of immune‐related diseases including pyoderma gangrenosum. We experienced a difficult‐to‐treat case of pyoderma gangrenosum‐like lesions in a patient with HCV infection. The patient was treated with pegylated interferon (PEG IFN)‐α‐2b and ribavirin (RBV) therapy and achieved a sustained virological response. Before the eradication of HCV, the frequency of T‐helper 17 cells was remarkably high in comparison to chronic hepatitis C patients without extrahepatic immune‐related diseases. Moreover, we could detect negative and positive strand‐specific HCV RNA in the CD19⁺ B lymphocytes and CD4⁺ T lymphocytes. However, after the eradication of HCV, the immunological status became normal and the pyoderma gangrenosum‐like lesions became stable without immunosuppressive therapy. Here, we report a sequential immunological analysis during PEG IFN/RBV therapy and the beneficial effect of HCV eradication in difficult‐to‐treat pyoderma gangrenosum‐like lesions.     

Schistosome infection aggravates HCV‐related liver disease and induces changes in the regulatory T‐cell phenotype

Schistosome infections are renowned for their ability to induce regulatory networks such as regulatory T cells (Treg) that control immune responses against homologous and heterologous antigens such as allergies. However, in the case of co‐infections with hepatitis C virus (HCV), schistosomes accentuate disease progression and we hypothesized that expanding schistosome‐induced Treg populations change their phenotype and could thereby suppress beneficial anti‐HCV responses. We therefore analysed effector T cells and n/iTreg subsets applying the markers Granzyme B (GrzB) and Helios in Egyptian cohorts of HCV mono‐infected (HCV), schistosome‐co‐infected (Sm/HCV) and infection‐free individuals. Interestingly, viral load and liver transaminases were significantly elevated in Sm/HCV individuals when compared to HCV patients. Moreover, overall Treg frequencies and Helios^posTreg were not elevated in Sm/HCV individuals, but frequencies of GrzB⁺Treg were significantly increased. Simultaneously, GrzB⁺ CD8⁺ T cells were not suppressed in co‐infected individuals. This study demonstrates that in Sm/HCV co‐infected cohorts, liver disease is aggravated with enhanced virus replication and Treg do not expand but rather change their phenotype with GrzB possibly being a more reliable marker than Helios for iTreg. Therefore, curing concurrent schistosome disease could be an important prerequisite for successful HCV treatment as co‐infected individuals respond poorly to interferon therapy.     

Response to direct‐acting antivirals for hepatitis C treatment in vertically HIV/HCV co‐infected patients

Direct‐acting antivirals (DAAs) for HCV treatment have improved tolerance and efficacy among adults, but experience in vertical transmission is scarce. In our vertically HIV/HCV co‐infected youth cohort of 58 patients, DAA achieved excellent rates of cure among naïve and pretreated individuals. Treating vertically infected seems important as 29.6% displayed advanced fibrosis at treatment initiation.     

Characteristics of regulatory T‐cell function in patients with chronic hepatitis B and C coinfection

Regulatory T cells (Tregs) affect the pathogenesis and disease progression of chronic viral hepatitis. This study evaluated the frequency and function of Tregs in patients with chronic HBV/HCV coinfection. Seventy‐four untreated HBV/HCV co‐infected patients were enrolled in this study. These subjects were divided into four subgroups: HBV‐active/HCV‐active (BACA), HBV‐inactive/HCV‐active (BICA), HBV‐active/HCV‐inactive (BACI) and HBV‐inactive/HCV‐inactive (BICI). Treg frequency was calculated as the fraction of CD4⁺Foxp3⁺T cells among CD4⁺T cells. Treg‐mediated inhibition was measured as percent of inhibition of T‐cell proliferation. The expression of interferon (IFN)‐γ, tumour necrosis factor (TNF)‐α and interleukin (IL)‐10 with/without Treg inhibition was also studied. Among the patients, there were 8 cases of BACA (10.8%), 38 of BICA (51.4%), 14 of BACI (18.9%) and 14 of BICI (18.9%). The frequency of CD4⁺Foxp3⁺T cells was comparable between the four groups. The inhibitory function of Tregs among the patients in the BACA and BICA was higher than that in the BICI (BACA vs BICI, P = .0210; BICA vs BICI, P = .0301). Patients in the BACA and BICA had higher fibrosis‐4 (FIB‐4) scores and serum ALT levels and lower serum albumin levels than those of the other groups. ALT abnormality was significantly and independently associated with a higher Treg immunosuppressive ability. The IFN‐γ expression of the effector T cells in the BACA was higher than that of the other groups. In conclusion, the inhibitory function of Tregs is higher among the HBV/HCV co‐infected patients with active HCV infection. ALT abnormality plays a dominant role in Treg function.     

Impact of oral silymarin on virus‐ and non‐virus‐specific T‐cell responses in chronic hepatitis C infection

Silymarin displays anti‐inflammatory effects on T lymphocytes in vitro. The immunomodulatory properties of oral silymarin in vivo in humans with chronic hepatitis C have not previously been characterized. We hypothesized that silymarin would suppress T‐cell proliferation and pro‐inflammatory cytokine production of virus‐ and non‐virus‐specific T cells while increasing anti‐inflammatory IL‐10 production in vivo. Patients from one site of the SyNCH‐HCV double‐masked, placebo‐controlled study of oral silymarin in prior interferon nonresponders with chronic hepatitis C provided blood samples at baseline and treatment week 20. Mononuclear cells were stimulated with recombinant HCV proteins and controls in ³H‐thymidine proliferation assays, IFNγ ELISPOT and IL‐10 ELISPOT. The frequency of CD4⁺CD25^hi and CD4⁺foxp3⁺ regulatory T cells, serum cytokine levels, serum IP‐10 and lymphocyte interferon‐stimulated gene expression were also quantified at baseline and week 20. Thirty‐two patients were recruited (10; placebo, 11; 420 mg three times a day, 11; 700 mg three times a day). Serum ALT and HCV RNA titres did not change in any group. HCV‐specific CD4⁺ T‐cell proliferation and the frequency of IFNγ‐ and IL‐10‐producing T cells were not significantly changed in silymarin‐treated subjects. However, C. albicans‐induced T‐cell IFNγ and phytohaemagglutinin‐induced T‐cell proliferation were suppressed by silymarin therapy. A trend towards augmentation of interferon‐induced ISG15 expression was present in the high‐dose silymarin group. While no effect on HCV‐specific T cells was identified, these data confirm that high‐dose oral silymarin exerts modest nonspecific immunomodulatory effects in vivo. The impact of this anti‐inflammatory effect on long‐term liver health in chronic hepatitis C merits future clinical investigation.     

Dynamic changes in innate immune responses during direct‐acting antiviral therapy for HCV infection

The role of the endogenous interferon (IFN) system has been well characterized during IFN‐based therapy for chronic hepatitis C virus (HCV) infection; less is known for direct‐acting antivirals (DAAs). In this phase 3b open‐label study, we assessed changes in IFN‐stimulated genes (ISGs) in non‐cirrhotic treatment‐naïve or pegIFN/RBV‐experienced HCV‐GT1a‐infected patients receiving paritaprevir/ritonavir/ombitasvir + dasabuvir + ribavirin (PrOD + R) for 12 weeks. ISG expression was quantified from peripheral blood mononuclear cells at baseline, treatment weeks (TW)2, TW4, TW8, end of treatment (EOT) and at post‐treatment week 12. Paired sera were used to assess IFN‐α/IFN‐related chemokines/cytokines. Twenty‐five patients were enrolled. Overall sustained virologic response (SVR)12 was 92% (no virologic failure [VF]) and 100% for those completing the study protocol. Two patients were excluded from the ISG analysis due to lack of post‐treatment samples. The majority of ISGs were downregulated at TW2‐TW4 (nadir TW4); however, a relative increase was observed at TW8‐EOT, although levels were lower than baseline. This downregulation was accompanied by increases in IFN‐α/IFN‐related chemokines, a finding not observed with T_H1/2‐related cytokines. Following SVR, ISG expression returned to TW2 levels. In conclusion, PrOD + R for 12 weeks was well‐tolerated with no VF. Our data demonstrate dynamic alterations in innate immune profiles during highly potent IFN‐free DAA therapy. The downregulation of ISG post‐therapy suggests reversal of the “exhausted” ISG phenotype following SVR, and the rise in ISGs and IFN‐α/IFN‐responsive chemokines late during therapy suggests resetting of IFN responsiveness that may be relevant in determining duration of or immunological sequelae from DAA therapy, including HBV reactivation.     

Chronic hepatitis C treatment in HIV co‐infection in Portugal: Results from a cohort OF 2133 patients presented by GEPCOI (Portuguese Coinfection Study Group)

Direct‐acting antiviral drugs (DAAs) have recently changed the paradigm of hepatitis C therapy, significantly improving treatment response rates, patient life expectancy and quality of life. In Portugal, sofosbuvir (SOF) and SOF/ledipasvir (SOF/LDV) were fully reimbursed by the National Health System since early 2015 and generalized use of interferon‐free DAA based regimens became current practice. During 2016, the remaining DAAs were sequentially added and covered by the same health access policy. The Portuguese Study Group of Hepatitis and HIV Co‐infection (GEPCOI) collected data from 15 clinical centres in Portugal, pertaining to the HCV treatment experience with DAA regimens. A cohort of 2133 patients was analysed, representing one of the largest DAA treated HCV/HIV co‐infected individuals. The global sustained virologic response (SVR) achieved was 95% in this real‐life cohort setting. Linear regression analysis showed significant differences in treatment response rates when using SOF plus ribavirin (RBV) combination in genotype 2 or 3 infected individuals (P < .002) and in those with liver cirrhosis (P < .002). These findings corroborate that early treatment is mandatory in HIV/HCV co‐infected patients, as response rates may be negatively influenced by higher fibrosis stages and suboptimal DAA regimens. The current national Portuguese health policy should continue to promote wider treatment access and individualized therapy strategies, aiming at the elimination of HCV infection in this high‐risk co‐infected population.     

Comparing the risk of hepatitis B virus reactivation between direct‐acting antiviral therapies and interferon‐based therapies for hepatitis C

Hepatitis B virus (HBV) reactivation has been reported during antihepatitis C treatment in patients with hepatitis C virus (HCV) and HBV co‐infection. We aimed to evaluate the frequency and risk factors of HBV reactivation during anti‐HCV therapy and compared those between interferon (IFN)‐free direct‐acting antiviral (DAA) therapies and IFN‐based therapies. Three hundred and twenty‐two patients with HCV infection receiving anti‐HCV therapy were retrospectively screened. The baseline HBV infection statuses of all eligible patients and the HBV‐DNA level of all patients with current or previous HBV infection were examined at the end of treatment. In patients with baseline anti‐HBs positivity, changes in anti‐HBs titre were evaluated. Of 287 patients who met the inclusion criteria, 157 had current (n=4) or previous (n=153) HBV infection; 85 were treated with IFN‐free DAA therapies and 72 were treated with IFN‐based therapies. Six patients experienced HBV reactivation (n=2) or HBV reappearance (n=4) after IFN‐free DAA therapies, while no patient developed HBV reactivation after IFN‐based therapies. The risk factors of HBV reactivation or reappearance were DAA therapies and a reduction in anti‐HBs titre to <12 mIU mL^?1 by the end of treatment. The decline changes of anti‐HBs titre were significantly higher in patients treated with DAA therapies. Although HBV reactivation hepatitis was not observed, three of four patients with HBV reactivation or reappearance after achieving HCV eradication had viremia 8 weeks after completion of therapy. A significant proportion of patients develop HBV reactivation or reappearance without hepatitis after IFN‐free DAA therapies. Low levels of anti‐HBs and their decrease to <12 mIU mL^?1 after treatment are significant risk factors for HBV reactivation or reappearance.     

Hepatic compartmentalization of exhausted and regulatory cells in HIV/HCV‐coinfected patients

Accelerated intrahepatic hepatitis C virus (HCV) pathogenesis is likely the result of dysregulation within both the innate and adaptive immune compartments, but the exact contribution of peripheral blood and liver lymphocyte subsets remains unclear. Prolonged activation and expansion of immunoregulatory cells have been thought to play a role. We determined immune cell subset frequency in contemporaneous liver and peripheral blood samples from chronic HCV‐infected and HIV/HCV‐coinfected individuals. Peripheral blood mononuclear cells (PBMC) and biopsy‐derived liver‐infiltrating lymphocytes from 26 HIV/HCV‐coinfected, 10 chronic HCV‐infected and 10 HIV‐infected individuals were assessed for various subsets of T and B lymphocytes, dendritic cell, natural killer (NK) cell and NK T‐cell frequency by flow cytometry. CD8⁺ T cells expressing the exhaustion marker PD‐1 were increased in HCV‐infected individuals compared with uninfected individuals (P = 0.02), and HIV coinfection enhanced this effect (P = 0.005). In the liver, regulatory CD4⁺CD25⁺Foxp3⁺ T cells, as well as CD4⁺CD25⁺PD1⁺ T cells, were more frequent in HIV/HCV‐coinfected than in HCV‐monoinfected samples (P < 0.001). HCV was associated with increased regulatory T cells, PD‐1⁺ T cells and decreased memory B cells, regardless of HIV infection (P ≤ 0.005 for all). Low CD8⁺ expression was observed only in PD‐1⁺CD8⁺ T cells from HCV‐infected individuals and healthy controls (P = 0.002) and was associated with enhanced expansion of exhausted CD8⁺ T cells when exposed in vitro to PHA or CMV peptides. In conclusion, in HIV/HCV coinfection, ongoing HCV replication is associated with increased regulatory and exhausted T cells in the periphery and liver that may impact control of HCV. Simultaneous characterization of liver and peripheral blood highlights the disproportionate intrahepatic compartmentalization of immunoregulatory T cells, which may contribute to establishment of chronicity and hepatic fibrogenesis in HIV coinfection.     

IFN‐free therapy is associated with restoration of type I IFN response in HIV‐1 patients with acute HCV infection who achieve SVR

Interferon (IFN)‐free direct‐acting antiviral agents (DAAs) have revolutionized chronic hepatitis C virus (HCV) treatment; early studies suggest excellent efficacy in acute HCV. However, changes in innate immune responses during DAA therapy for acute HCV are unknown. We studied interferon‐stimulated gene (ISG) expression and related cytokines/chemokines in HIV‐infected patients with acute HCV receiving sofosbuvir plus ribavirin (SOF+RBV) as part of the A5327 clinical trial. ISG expression was determined from PBMCs, and circulating cytokines/chemokines were quantified from serum from study participants. The overall sustained virologic response (SVR) was 57%; all treatment failures were due to virologic relapse. Apart from NOS2a, baseline ISG/chemokine/cytokine levels were similar irrespective of treatment outcome. Downregulation of ISGs was observed at treatment week four and end of treatment (EOT), implicating HCV in establishing elevated ISGs early during HCV infection. Levels of many of these ISGs increased at post‐treatment week 12 (PTW12) in relapsers only, coinciding with recurrent HCV RNA. Eleven ISGs were differentially expressed in responders vs relapsers. On‐treatment viral suppression was also associated with a reduction in IP‐10, CXCL11 and MIP‐1β levels. In contrast, circulating IFN‐α levels were significantly higher at EOT and PTW12 in responders vs relapsers. Upregulation of peripheral ISG expression is established early in the course of HCV infection during acute HCV infection, but did not predict subsequent treatment outcome with SOF+RBV. ISGs were downregulated during therapy and increased post‐therapy in relapsers. IFN‐α levels were higher in responders at EOT/PTW12, suggesting that impaired type I IFN production/secretion may contribute to relapse.     

Clinico‐immunological outcomes of HCV‐cured cryoglobulinemia: Lower relapse rate with interferon‐based than interferon‐free therapy

Sustained virological response (SVR) obtained with interferon (IFN) or with direct‐acting antivirals (DAAs) is commonly followed by response of hepatitis C virus (HCV)‐associated mixed cryoglobulinemia vasculitis (MCV), but relapse of MCV despite SVR has been reported in several patients after DAAs and rarely after IFN. Since relapses could have been overlooked in studies with IFN, we retrospectively compared the outcomes of MCV in SVR patients treated with DAAs (n = 70) or IFN (n = 39) followed‐up, respectively, for 30.5 (range 11‐51) or 48 months. Groups were comparable for demographics and clinics and response rates of MCV were similar (92% and 86%); however, DAA‐treated patients less efficiently reduced cryoglobulins (P = .006) and circulating B‐cell clones (P = .004), and had more frequently relapses of MCV (18% vs 3%, P = .028) and need for rituximab therapy (P = .01). Although largely inferior on an intention‐to‐treat basis, IFN may be superior to DAAs on clinico‐immunological outcomes possibly owing to its antiproliferative activity.     

Expression of programmed cell death protein 1 and T‐cell immunoglobulin‐ and mucin‐domain‐containing molecule‐3 on peripheral blood CD4+CD8+ double positive T cells in patients with chronic hepatitis C virus infection and in subjects who spontaneously cleared the virus

Chronic hepatitis C virus (HCV) infection is characterized by increased proportion of CD4+CD8+ double positive (DP) T cells, but their role in this infection is unclear. In chronic hepatitis C, immune responses to HCV become functionally exhausted, which manifests itself by increased expression of programmed cell death protein 1 (PD‐1) and T‐cell immunoglobulin‐ and mucin‐domain‐containing molecule‐3 (Tim‐3) on T cells. The aim of our study was to determine PD‐1 and Tim‐3 phenotype of DP T cells in subjects with naturally resolved and chronic HCV infection. Peripheral blood mononuclear cells from 16 patients with chronic infection and 14 subjects who cleared HCV in the past were stained with anti‐CD3, anti‐CD4, anti‐CD8, anti‐PD‐1 and anti‐Tim‐3 antibodies and, in 12 HLA‐A*02‐positive subjects, MHC class I pentamer with HCV NS3₁₄₀₆ epitope. In chronic and past HCV infection, proportions of total DP T cells and PD‐1+ DP T cells were similar but significantly higher than in healthy controls. DP T cells were more likely to be PD‐1+ than either CD4+ or CD8+ single positive (SP) T cells. HCV‐specific cells were present in higher proportions among DP T cells than among CD8+ SP T cells in both patient groups. Furthermore, while the majority of HCV‐specific DP T cells were PD‐1+, the proportion of HCV‐specific CD8+ T cells which were PD‐1+ was 4.9 and 1.9 times lower (chronic and past infection, respectively). PD‐1 and Tim‐3 were predominantly expressed on CD4^highCD8^low and CD4^lowCD8^high cells, respectively, and co‐expression of both markers was uncommon.     

Oral anti‐CD3 immunotherapy for HCV‐nonresponders is safe,promotes regulatory T cells and decreases viral load and liver enzyme levels: results of a phase‐2a placebo‐controlled trial

Orally administered anti‐CD3 antibodies are biologically active in the gut through induction of regulatory T cells, exert an immune‐modulatory effect, and alleviate insulin resistance and liver damage in patients with NASH. Aims: To determine the safety of oral anti‐CD3 monoclonal antibody (MAb) immunotherapy in chronic HCV patients with associated immune dysfunction. Methods: Four groups (n = 9) of chronic HCV patients who were nonresponders to interferon plus ribavirin therapy received oral placebo (group A) or anti‐CD3 MAb at one of three dosage levels for 30 days. Patients were followed for safety parameters and serum levels of liver enzymes, virus, cytokines and regulatory T cells. Results: Oral anti‐CD3 immunotherapy was safe and well tolerated; no treatment‐related adverse events were noted. The following improvements were noted relative to pretreatment levels: HCV viral load and AST and ALT levels decreased in the low‐ and high‐dose groups following 30 days of therapy. In two of the treated groups, an increase in regulatory T cells (CD4⁺ CD25⁺) was noted. The positive effects were somewhat more apparent in subjects with initially elevated liver enzyme levels. Conclusions: Oral anti‐CD3 MAb immunotherapy for nonresponder HCV patients was safe and well tolerated. Trends and statistically significant improvements were observed as reductions in viral load and liver enzyme levels, along with an increase in regulatory T‐cell levels. These data support a role for the immune system in the pathogenesis of HCV infection and suggest that this immunotherapy is worthy of evaluation in combination with HCV antiviral drugs.     

Baseline sensitivity of T cells to alpha‐IFN correlates with sustained virological response to IFN‐based triple therapy in HCV infection

Chronic infection with HCV is a public health problem with approximately 170 million people infected worldwide. Interferon alpha (IFNα) sensitivity in liver and IL28B genotype has been identified as important determinants of HCV clearance in the setting of pegylated interferon/ribavirin treatment. Herein, we explored IFNα sensitivity in PBMC from 21 healthy donors and 21 HCV‐infected patients treated with pegylated interferon/ribavirin and HCV nonstructural protein‐3 inhibitors (i.e. telaprevir/boceprevir). We explored phospho‐STAT1 level as read‐out for IFN signalling pathway activation in PBMC, T cells and monocytes and correlated results with virological response. We found that PBMC from healthy donors are desensitized to IFNα after priming and challenged with IFNα, with a subsequent decrease of phospho‐STAT1 and interferon‐stimulated genes. Furthermore, we show that CD3+ T cells, but not monocytes, become desensitized after 4 weeks of treatment, with a significant decrease of phospho‐STAT1 after ex vivo IFNα stimulation. Finally, we identified baseline phospho‐STAT1 level in CD3+ T cells as a potential biomarker of sustained virological response, regardless of the IL28B genotype. In the upcoming costly era of IFN‐sparing regimen, baseline IFNα sensitivity could act as biomarker to define cost‐effectiveness strategies of treatment by identifying patients who will or will not respond to IFN‐based treatments.