Telaprevir: An NS3/4A Protease Inhibitor for the Treatment of Chronic Hepatitis C

Therapeutic Intervention of Serine Protease Inhibitors against Hepatitis C Virus

Hepatitis C virus (HCV) is a globally prevalent and hazardous disorder that is responsible for inducing several persistent and potentially fatal liver diseases. Current treatment strategies offer limited efficacy, often accompanied by severe and debilitating adverse effects. Consequently, there is an urgent and compelling need to develop novel therapeutic interventions that can provide maximum efficacy in combating HCV while minimizing the burden of adverse effects on patients. One promising target against HCV is the NS3-4A serine protease, a complex composed of two HCV-encoded proteins. This non-covalent heterodimer is crucial in the viral life cycle and has become a primary focus for therapeutic interventions. Although peginterferon, combined with ribavirin, is commonly employed for HCV treatment, its efficacy is hampered by significant adverse effects that can profoundly impact patients' quality of life. In recent years, the development of direct-acting antiviral agents (DAAs) has emerged as a breakthrough in HCV therapy. These agents exhibit remarkable potency against the virus and have demonstrated fewer adverse effects when combined with other DAAs. However, it is important to note that there is a potential for developing resistance to DAAs due to alterations in the amino acid position of the NS3-4A protease. This emphasizes the need for ongoing research to identify strategies that can minimize the emergence of resistance and ensure long-term effectiveness. While the combination of DAAs holds promise for HCV treatment, it is crucial to consider the possibility of drug-drug interactions. These interactions may occur when different DAAs are used concurrently, potentially compromising their therapeutic efficacy. Therefore, carefully evaluating and monitoring potential drug interactions are vital to optimize treatment outcomes. In the pursuit of novel therapeutic interventions for HCV, the field of computational biology and bioinformatics has emerged as a valuable tool. These advanced technologies and methodologies enable the development and design of new drugs and therapeutic agents that exhibit maximum efficacy, reduced risk of resistance, and minimal adverse effects. By leveraging computational approaches, researchers can efficiently screen and optimize potential candidates, accelerating the discovery and development of highly effective treatments for HCV, treatments.

Characterization of Healthy Donor-Derived T-Cell Responses Specific to Telaprevir Diastereomers

Telaprevir, a protease inhibitor, was used alongside PEGylated interferon-α and ribavirin to treat hepatitis C viral infections. The triple regimen proved successful; however, the appearance of severe skin reactions alongside competition from newer drugs restricted its use. Skin reactions presented with a delayed onset indicative of a T-cell mediated reaction. Thus, the aim of this study was to investigate whether telaprevir and/or its diastereomer, which is generated in humans, activates T-cells. Telaprevir in its S-configured therapeutic form and the R-diastereomer were cultured directly with peripheral blood mononuclear cells from healthy donors prior to the generation of T-cell clones by serial dilution. Drug-specific CD4+ and CD8+ T-cell clones responsive to telaprevir and the R-diastereomer were generated and characterized in terms of phenotype and function. The clones proliferated with telaprevir and diastereomer concentrations of 5-20 µM and secreted IFN-γ, IL-13, and granzyme B. In contrast, the telaprevir M11 metabolite did not stimulate T-cells. The CD8+ T-cell response was MHC I-restricted and dependent on the presence of soluble drug. Flow cytometric analysis showed that clones expressed chemokine receptors CCR4 (skin homing) and CXCR3 (migration to peripheral tissue) and 1 of 3 distinct TCR Vβs; TCR Vβ 2, 5.1, or 22. These data show the propensity of both R- and S-forms of telaprevir to generate skin-homing cytotoxic T-cells that may induce the adverse reactions observed in human patients.

Epidemiology, patient profile, and health care resource use for hepatitis C in Italy

Objective

The objectives of this study were to estimate the prevalence of Hepatitis C among six Italian Local Health Units (LHUs), to describe patient and antiviral drug characteristics, and to estimate the health care consumption rates and related costs for the management of patients affected by hepatitis C virus (HCV) infection by using data from routine clinical practice.

Methods

We conducted a retrospective study using administrative databases of six Italian LHUs. All patients who had a record related to HCV during the enrollment period (July 1, 2009, to December 31, 2014) and who had at least 6 months of data available prior to the first HCV record were included. The date of the first record related to HCV during the enrollment period was considered as a proxy of diagnosis and used as the index date. Patients were followed from the index date up to 1 year, death, or exiting the database. Using the overall cohort of HCV adult patients as the numerator, we estimated the prevalence of HCV among six LHUs. The denominators were obtained from the National Institute of Statistics (N=1,665,682). We also evaluated descriptive patient’s characteristics and treatment patterns, and estimated health care consumption rates and related costs for the management of the HCV patients.

Results

A total of 7,550 patients were analyzed, of whom 57% were male with a mean age of 57.6±16.4 years. The prevalence of HCV was estimated to be 0.45% (95% confidence interval 0.44–0.46). During the follow-up period, 78.6% of HCV patients had received no antiviral treatment. The annual health care cost associated with HCV infection was €6,022.7 (±7,922.6) while the cost specific to HCV care was €3,154.6 (±4,972.0)

Conclusion

Our findings showed that, in the Italian real-world setting, only a small proportion of HCV-infected patients received an antiviral treatment. Despite the current low prevalence of HCV, the economic impact of such disease remains high.

Sofosbuvir: A Nucleotide NS5B Inhibitor for the Treatment of Chronic Hepatitis C Infection

OBJECTIVE

To review the use of sofosbuvir for the treatment of chronic hepatitis C virus (HCV).

DATA SOURCES

Review and nonreview articles were identified through MEDLINE (1996-April 2014), citations of articles, and meeting abstracts using keywords, including NS5B polymerase inhibitor, GS-7977, sofosbuvir, direct-acting antiviral (DAA), and others.

STUDY SELECTION AND DATA EXTRACTION

Phase 1, 2, and 3 studies describing dose-ranging potential, pharmacokinetics, efficacy, safety, and tolerability of sofosbuvir were identified.

DATA SYNTHESIS

Sofosbuvir is an NS5B polymerase inhibitor that was approved for use by the Food and Drug Administration in December 2013 for the treatment of chronic HCV in combination with pegylated interferon (peg-IFN) and ribavirin (RBV) for genotype 1. Additionally, it has been evaluated with other oral DAAs, such as simeprevir and others in the pipeline. It is not recommended as monotherapy because of lower sustained virological response (SVR) rates in clinical studies. Most of the treatment regimens are 12 weeks in duration; however, certain populations require a longer duration. Sofosbuvir has activity against all 6 genotypes, although most clinical trials evaluated genotypes 1 to 3. Sofosbuvir has a favorable safety and tolerability profile, making it a recommended first-line agent for chronic HCV infection.

CONCLUSION

In clinical trials, 12 weeks of sofosbuvir with concomitant peg-IFN and RBV therapy in treatment-naïve and experienced HCV genotype 1 patients resulted in SVR rates of >90%. An all-oral regimen of sofosbuvir and RBV is highly effective for genotype 2 and 3 patients. Sofosbuvir was found to be tolerable with minimal adverse effects (AEs), and no treatment discontinuations occurred secondary to drug related AEs..

Role of interleukin-28B polymorphism as a predictor of sustained virological response in patients with chronic hepatitis C treated with triple therapy: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Chronic hepatitis C represents an important health problem. The aim of our meta-analysis was to establish the role of reference single nucleotide (rs) 12979860 allele of interleukin-28B (IL28B) CC versus CT+TT genotype (the most researched allele of IL28B) as a predictor of sustained virological response (SVR) in patients with chronic hepatitis C treated with triple therapy.

METHODS

The PubMed, MEDLINE, Lilacs, Scopus, Ovid, EMBASE, Cochrane and Medscape databases as well as abstract books from important gastroenterology and hepatology meetings were searched for all studies published until 15 July 2012 that analysed the relationship between the polymorphism of IL28B and SVR in patients with chronic hepatitis C, genotype 1, treated with pegylated interferon + ribavirin + direct antiviral agents (telaprevir or boceprevir). The following keywords were used: IL28B polymorphism, chronic hepatitis C, sustained virological response, SVR, triple therapy, telaprevir, boceprevir.

RESULTS

Odds ratios (ORs) with 95 % confidence intervals were pooled from five study populations (1,641 cases) using a random-effects model. The SVR rate was significantly higher in patients with the CC genotype of IL28B than in those with non-CC genotypes (CT and TT): OR = 3.91 (95 % CI 2.11-7.28), p < 0.0001. Higher SVR rates were obtained in chronic hepatitis C patients with the CC genotype of IL28B, regardless of their therapeutic status (naïve patients: OR = 3.99 [95 % CI 1.67-9.51], p < 0.0001; and previously treated ones: OR = 2.15 [95 % CI 1.35-3.43], p = 0.001).

CONCLUSION

IL28B polymorphism seems to influence the SVR rate in patients with chronic hepatitis C treated with triple therapy, but further studies are needed to clarify the mechanism and the influence of other factors on the SVR rates.

Animal models of chronic liver diseases

Chronic liver diseases are frequent and potentially life threatening for humans. The underlying etiologies are diverse, ranging from viral infections, autoimmune disorders, and intoxications (including alcohol abuse) to imbalanced diets. Although at early stages of disease the liver regenerates in the absence of the insult, advanced stages cannot be healed and may require organ transplantation. A better understanding of underlying mechanisms is mandatory for the design of new drugs to be used in clinic. Therefore, rodent models are being developed to mimic human liver disease. However, no model to date can completely recapitulate the "corresponding" human disorder. Limiting factors are the time frame required in humans to establish a certain liver disease and the fact that rodents possess a distinct immune system compared with humans and have different metabolic rates affecting liver homeostasis. These features account for the difficulties in developing adequate rodent models for studying disease progression and for testing new pharmaceuticals to be translated into the clinic. Nevertheless, traditional and new promising animal models that mimic certain attributes of chronic liver diseases are established and being used to deepen our understanding in the underlying mechanisms of distinct liver diseases. This review aims at providing a comprehensive overview of recent advances in animal models recapitulating different features and etiologies of human liver diseases.

Molecular pathways: hepatitis C virus, CXCL10, and the inflammatory road to liver cancer

An estimated 170 million people worldwide are chronically infected with the hepatitis C virus (HCV), which is characterized histologically by a persistent immune and inflammatory response that fails to clear HCV from hepatocytes. This response is recruited to the liver, in part, by the chemokine CXCL10, the serum and intrahepatic levels of which have been inversely linked to the outcome of interferon-based therapies for hepatitis C. Bystander tissue damage from this ineffective response is thought to lead to increased hepatocyte turnover and the development of fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). However, CXCL10 is traditionally viewed as an orchestrator of the angiostatic and antitumor immune response. In this review, we will explore this duality and the pathways by which CXCL10 is produced by hepatocytes during HCV infection, its effects on resident and infiltrating immune cells, and how deregulation of these cell populations within the liver may lead to chronic liver inflammation. We will also discuss potential host-directed therapies to slow or reverse HCV-induced inflammation that leads to fibrosis, cirrhosis, and HCCs.

Safety of telaprevir for chronic hepatitis C virus infection: a meta-analysis of randomized controlled trials

BACKGROUND

Previous studies have reported telaprevir is effective for chronic hepatitis C virus infection, but the safety of a telaprevir-based regimen remains uncertain.

OBJECTIVE

A meta-analysis was performed to assess the safety of the addition of telaprevir to a standard regimen of pegylated interferon (peginterferon) plus ribavirin (combination telaprevir with peginterferon plus ribavirin, the TPR group) compared with the standard regimen group (peginterferon plus ribavirin, the PR group).

METHODS AND RESULTS

Seven randomized controlled trials involving a total of 2808 patients were included in the meta-analysis. The addition of telaprevir to the standard regimen was associated with a significantly increased risk of serious adverse events compared with the standard PR group (relative risk [RR] = 1.56; 95% confidence interval [CI] 1.21, 2.03; p = 0.0007; I2 = 0%). Telaprevir was also associated with increased risk of treatment discontinuation (RR = 2.10; 95% CI 1.56, 2.83; p < 0.0001; I2 = 42%). In addition, telaprevir was more likely to cause nausea (RR = 1.39; p < 0.0001), diarrhoea (RR = 1.32; p = 0.004), pruritus (RR = 1.56; p = 0.0006), rash (RR = 1.60; p < 0.0001) and anaemia (RR = 1.55; p = 0.007). There was no difference in the other kinds of adverse events between the two groups. Sensitivity analysis further validated the credibility of the above outcomes.

CONCLUSION

Our meta-analysis raises safety concerns about the potential for an increased risk of serious adverse events associated with the use of telaprevir among patients with chronic hepatitis C virus infection, and cautious use of telaprevir is warranted.

Expected and actual case ascertainment and treatment rates for children infected with hepatitis C in Florida and the United States: epidemiologic evidence from statewide and nationwide surveys

OBJECTIVE

To evaluate the rate of pediatric hepatitis C virus (HCV) case ascertainment relative to the estimated number of actual cases.

STUDY DESIGN

Data from Florida and United States health departments were used to assess pediatric HCV case ascertainment rates in Florida and nationwide. The percentage of children infected with HCV from Miami-Dade County receiving medical care by a pediatric gastroenterologist was estimated based on data obtained from physician questionnaires.

RESULTS

From 2000 through 2009, 2007 children were identified as having positive HCV antibody tests in Florida, only 12% of the expected number (n = 12 155). An estimated 1.6% of the expected children with HCV who tested Ab-positive (37 of 1935) were actively followed by a pediatric gastroenterologist in Miami-Dade County, Florida. Across the United States, only 4.9% of the expected cases have been identified.

CONCLUSIONS

The identification of children infected with HCV in the nation as a whole is grossly inadequate. Only a small fraction of cases are identified. In Florida, less than 2% of children identified receive treatment. Lack of identification and lack of treatment of children infected with HCV constitute critical public health problems. Strategies to increase awareness of HCV infection and to screen at-risk individuals could substantially improve morbidity and mortality while reducing health care costs.

A theoretical framework for early human studies: uncertainty, intervention ensembles, and boundaries

Clinical development of novel therapeutics begins with a coordinated sequence of early phase clinical trials. Such early human studies confront a series of methodological and ethical challenges. In what follows, I propose a theoretical framework for early human studies aimed at informing the negotiation of these challenges. At the outset of clinical development, researchers confront a virtually undifferentiated landscape of uncertainty with respect to three variables: outcomes, their probability of occurrence, and operation dimensions needed to effectuate favorable outcomes. Early human trials transform this uncertain landscape into one where there are grounds for belief about risk and benefit for various combined operation dimensions. To accomplish this, studies set out with two aims. First, they identify a set of operation dimensions that, when combined as a package (intervention ensemble), elicits a reasonable probability of a target outcome. Second, they define the boundaries of dimension values within an intervention ensemble. This latter aim entails exposing at least some volunteers in early studies to treatments that are inactive or excessive. I provide examples that illustrate the way early human studies discover and delimit intervention ensembles, and close by offering some implications of this framework for ethics, methodology, and efficiency in clinical development of new interventions.