Review of consensus interferon in the treatment of chronic hepatitis C

Quantitative systems pharmacology of interferon alpha administration: A multi-scale approach

The therapeutic effect of a drug is governed by its pharmacokinetics which determine the downstream pharmacodynamic response within the cellular network. A complete understanding of the drug-effect relationship therefore requires multi-scale models which integrate the properties of the different physiological scales. Computational modelling of these individual scales has been successfully established in the past. However, coupling of the scales remains challenging, although it will provide a unique possibility of mechanistic and holistic analyses of therapeutic outcomes for varied treatment scenarios. We present a methodology to combine whole-body physiologically-based pharmacokinetic (PBPK) models with mechanistic intracellular models of signal transduction in the liver for therapeutic proteins. To this end, we developed a whole-body distribution model of IFN-α in human and a detailed intracellular model of the JAK/STAT signalling cascade in hepatocytes and coupled them at the liver of the whole-body human model. This integrated model infers the time-resolved concentration of IFN-α arriving at the liver after intravenous injection while simultaneously estimates the effect of this dose on the intracellular signalling behaviour in the liver. In our multi-scale physiologically-based pharmacokinetic/pharmacodynamic (PBPK/PD) model, receptor saturation is seen at low doses, thus giving mechanistic insights into the pharmacodynamic (PD) response. This model suggests a fourfold lower intracellular response after administration of a typical IFN-α dose to an individual as compared to the experimentally observed responses in in vitro setups. In conclusion, this work highlights clear differences between the observed in vitro and in vivo drug effects and provides important suggestions for future model-based study design.

Peginterferon Alfa-2a/Ribavirin treatment efficacy in chronic hepatitis C patients is related to natural killer group 2D gene rs1049174 GC polymorphism

Natural killer group 2D (NKG2D), as an activating receptor, plays pivotal role in viral infectious diseases. Several single nucleotide polymorphisms (SNPs) in the NKG2D gene have characterized that the rs1049174G/C SNP of NKG2D is in the spotlight of notice because of its role in activating of human T cells. This study aimed to investigate rs1049174G/C genetic polymorphism in Chronic Hepatitis C (CHC) patients. The study compromised 107 CHC patients with genotype 1a and 1b. All recruited patients were under treatment with Peginterferon Alfa-2a/Ribavirin according to standard protocol. After completing treatment, 67 patients showed sustained virologic response (SVR) and the rest of patients did not respond to the treatment and considered as non-responder (NR). Genotyping of NKG2D rs1049174G/C SNP was performed using PCR-RFLP method in SVR and NR patients. The NKG2D rs1049174 genotypes frequency for GG, GC and CC were 45, 41 and 14 % respectively. Genotypes distribution were significantly different between SVR and NR groups (p = 0.005). So that the patients with the homozygous GG genotype demonstrated a higher response to Peginterferon Alfa-2a/Ribavirin therapy against HCV infection (OR = 6.0, 95 %CI 1.71-21.08, p = 0.005). In conclusion, the rs1049174 GG genotype of NKG2D receptor is an effective factor in successfully treatment of CHC patients by Peginterferon Alfa-2a/Ribavirin.

Design and evaluation of novel interferon lambda analogs with enhanced antiviral activity and improved drug attributes

Type III interferons (IFNs) (also called IFN-λ: IFN-λ1, IFN-λ2, IFN-λ3, and IFN-λ4) are critical players in the defense against viral infection of mucosal epithelial cells, where the activity of type I IFNs is weak, and unlike type I IFNs that are associated with severe and diverse side effects, type III IFNs cause minimal side effects due to the highly restricted expression of their receptors, and thus appear to be promising agents for the treatment and prevention of respiratory and gastrointestinal viral infection. However, the antiviral potency of natural type III IFNs is weak compared to type I and, although IFN-λ3 possesses the highest bioactivity among the type III IFNs, IFN-λ1, instead of IFN-λ3, is being developed as a therapeutic drug due to the difficulty to express IFN-λ3 in the prokaryotic expression system. Here, to develop optimal IFN-λ molecules with improved drug attributes, we designed a series of IFN-λ analogs by replacing critical amino acids of IFN-λ1 with the IFN-λ3 counterparts, and vice versa. Four of the designed analogs were successfully expressed in Escherichia coli with high yield and were easily purified from inclusion bodies. Interestingly, all four analogs showed potent activity in inducing the expression of the antiviral genes MxA and OAS and two of them, analog-6 and -7, displayed an unexpected high potency that is higher than that of type I IFN (IFN-α2a) in activating the IFN-stimulated response element (ISRE)-luciferase reporter. Importantly, both analog-6 and -7 effectively inhibited replication of hepatitis C virus in Huh-7.5.1 cells, with an IC50 that is comparable to that of IFN-α2a; and consistent with the roles of IFN-λ in mucosal epithelia, both analogs potently inhibited replication of H3N2 influenza A virus in A549 cells. Together, these studies identified two IFN-λ analogs as candidates to be developed as novel antiviral biologics.

Consensus interferon plus ribavirin for hepatitis C genotype 3 patients previously treated with pegylated interferon plus ribavirin

BACKGROUND

Not enough data are available about the effectiveness of consensus interferon (CIFN) among HCV genotype 3 patients who failed to respond to pegylated interferon and ribavirin.

OBJECTIVES

We aimed to assess the efficacy and safety of CIFN and ribavirin in non-responders and relapsers to pegylated interferon with ribavirin therapy.

PATIENTS AND METHODS

This open-label investigator-initiated study included 44 patients who received CIFN 15 µg /day plus ribavirin 800-1200 mg daily. In patients with an early virological response (EVR), the dose of CIFN was reduced to 15 µg thrice a week for further 36 weeks. Patients with delayed virological response continued to receive daily CIFN plus ribavirin to complete 48 weeks. The patients were considered "non-responders" if there were less than 2 log reduction in HCV RNA at 12 weeks and detectable HCV RNA at 24 weeks.

RESULTS

Twenty-four patients (55%) were non-responders and 20 patients were relapsers to the previous treatment with pegylated interferon plus ribavirin (mean age 43.6 ± 9.4 years, males 25 (57%)). Nine patients were clinically cirrhotic (Child A). End of treatment virological response was achieved in 19 (43.1%) patients and sustained virological response (SVR) occurred in 12 (27.3%). Out of these 12 patients, eight were non-responders and four were relapsers to the previous treatment. Advanced fibrosis or clinical cirrhosis was associated with low SVR. Adverse events were fever, myalgia, anorexia, depression, and weight loss. Two patients received granulocyte colony stimulating factor for transient neutropenia. Seven patients were given erythropoietin to improve hemoglobin, and six were treated for mild depression. Two patients developed portosystemic encephalopathy.

CONCLUSIONS

More than one-quarter of treatment-experienced patients with HCV genotype 3 achieved SVR after re-treatment with consensus interferon plus ribavirin.

IFN-α subtypes: distinct biological activities in anti-viral therapy

During most viral infections, the immediate host response is characterized by an induction of type I IFN. These cytokines have various biological activities, including anti-viral, anti-proliferative and immunomodulatory effects. After induction, they bind to their IFN-α/β receptor, which leads to downstream signalling resulting in the expression of numerous different IFN-stimulated genes. These genes encode anti-viral proteins that directly inhibit viral replication as well as modulate immune function. Thus, the induction of type I IFN is a very powerful tool for the host to fight virus infections. Many viruses evade this response by various strategies like the direct suppression of IFN induction or inhibition of the IFN signalling pathway. Therefore, the therapeutic application of exogenous type I IFN or molecules that induce strong IFN responses should be of great potential for future immunotherapies against viral infections. Type I IFN is currently used as a treatment in chronic hepatitis B and C virus infection, but as yet is not widely utilized for other viral infections. One reason for this restricted clinical use is that type I IFN belongs to a multigene family that includes 13 different IFN-α subtypes and IFN-β, whose individual anti-viral and immunomodulatory properties have so far not been investigated in detail to improve IFN therapy against viral infections in humans. In this review, we summarize the recent achievements in defining the distinct biological functions of type I IFN subtypes in cell culture and in animal models of viral infection as well as their clinical usage in chronic hepatitis virus infections.

Hepatitis C viremia and genotype distribution among a sample of nonmedical prescription drug users exposed to HCV in rural Appalachia

Research has demonstrated that hepatitis C (HCV) genotype distribution varies geographically and demographically. This exploratory study examines HCV viremia, viral concentration, and genotype distribution among anti-HCV positive, rural Appalachian nonmedical prescription drug users. The study population was randomly selected from a pool of 200 anti-HCV positive participants in a longitudinal study. Those randomly chosen were representative of the overall pool in terms of demographics, drug use, and other risk behaviors. Participants were tested serologically for HCV RNA, viral concentration, and genotype, and interview-administered questionnaires examined behavioral and demographic characteristics. Of the 81 participants, 69% tested RNA positive, 59% of which had viral loads exceeding 800,000 IU/ml. Approximately 66% of the RNA positive sample had genotype 1a; types 2b (16%) and 3a (13%) were less common. RNA positive participants were not significantly different than RNA negative participants demographically or behaviorally. Likewise, with the exception of education, genotype 1 participants were not significantly different than those with genotype 2 or 3. The prevalence of active HCV infection highlights a need for prevention and treatment in this population. However, the predominance of genotype 1 may present challenges due to its association with decreased responsiveness to drug treatment, although the novel class of direct-acting antivirals such as telaprevir and boceprevir offer new hope in this regard. The prevalence of genotype 1 may also foreshadow heightened burden of hepatocellular carcinoma and elevated healthcare expenditures. More research is needed to characterize HCV infection and genotype in this population.

Management of untreated and nonresponder patients with chronic hepatitis C

Hepatitis C infection has evolved in the past quarter century from a newly recognized entity without a known pathogen (non-A, non-B hepatitis) to one of the world's most prevalent causes of liver disease, an important source for hepatocellular carcinoma, and the major indication for liver transplantation. It is caused by a virus with a complex replication cycle that occurs in multiple genotypes, of which the four most prevalent (1, 2, 3, and 4) exhibit differences in clinical behavior and responses to therapy. Chronic hepatitis C virus (HCV) in particular has evolved from a disease with no known treatment to one with several primary treatment options, none of which is uniformly effective, and a growing list of secondary treatment options for those who have failed to respond to, or relapsed after initial therapy. As treatment is often associated with significant side effects, it is now a disease that presents clinicians with multiple important decisions: whom to treat, when and with what to treat them initially, and how to manage patients who have failed during initial therapy to achieve a sustained virological response, the gold standard of effective therapy. This review examines each of these important decisions, presenting evidence to help guide clinicians in their choices. The decisions are addressed sequentially as they arise during the initial evaluation and subsequent treatment of a typical, newly recognized patient with chronic HCV, and the considerations facing the clinician when the patient has failed to achieve an SVR.

Ability of orally administered IFN-α4 to inhibit naturally occurring gingival inflammation in dogs

It has been reported that type I interferons (IFN-α/β) play an important role in innate immune responses against viral and bacterial infections. In this study, we used and examined naturally occurred canine periodontal disease to show the therapeutic efficacy of low dose oral administration (LDOA) of canine IFN-α subtype 4 (CaIFN-α4). We administered purified recombinant CaIFN-α4 expressed in a baculovirus system to dogs with or without gingival inflammation. We found that LDOA of CaIFN-α4 reduce periodontopathic bacterial counts. LDOA induced improvement of naturally occurring gingival inflammation, and reduction of the stress marker responses was also observed after LDOA. These results suggest that LDOA of CaIFN-α4 has effectiveness for improvement of naturally occurring gingival inflammation in dogs.

New strategies for the treatment of hepatitis C virus infection and implications of resistance to new direct-acting antiviral agents

Persistent hepatitis C virus (HCV) infection is a leading cause of chronic hepatitis, cirrhosis, and hepatocellular carcinoma and the major indication for liver transplantation in adults. Current standard of care treatment (SOC) with pegylated-interferon-α 2 and ribavirin (RBV) has a limited efficacy and is associated with significant side effects frequently associated with poor compliance or treatment discontinuation, requiring specialized and frequent monitoring. To overcome the limited efficacy of SOC, more than 50 direct-acting antiviral agents (DAA) designed to target viral-encoded proteins essential in the HCV life cycle are currently under development. The rapid selection of resistant mutants associated with the quasispecies nature of HCV with high mutation and replication rates is one of the main challenges for the new HCV therapies. Predictive host and viral factors together with combination of DAAs with or without IFN and/or RBV need to be accurately evaluated to design the most effective individualized treatment strategy within the shortest time interval and with minimum side effects.