An overview of emerging therapies for the treatment of chronic hepatitis C

Mono- and combinational drug therapies for global viral pandemic preparedness

Broadly effective antiviral therapies must be developed to be ready for clinical trials, which should begin soon after the emergence of new life-threatening viruses. Here, we pave the way towards this goal by reviewing conserved druggable virus-host interactions, mechanisms of action, immunomodulatory properties of available broad-spectrum antivirals (BSAs), routes of BSA delivery, and interactions of BSAs with other antivirals. Based on the review, we concluded that the range of indications of BSAs can be expanded, and new pan- and cross-viral mono- and combinational therapies can be developed. We have also developed a new scoring algorithm that can help identify the most promising few of the thousands of potential BSAs and BSA-containing drug cocktails (BCCs) to prioritize their development during the critical period between the identification of a new virus and the development of virus-specific vaccines, drugs, and therapeutic antibodies.

pH induced single step shift of hydrophobic patches followed by formation of an MG state and an amyloidogenic intermediate in Lima Bean Trypsin Inhibitor (LBTI)

Lima Bean Trypsin Inhibitor (LBTI) is 83 residues monomeric protein of 9.0 KDa, consisting of six antiparallel β-strands and can undergo concentration dependant dimerization. We have tried to characterize folding intermediates of LBTI under equilibrium denaturation conditions. We have used various spectroscopic and microscopic techniques to understand the folding and misfolding pathways. LBTI forms molten globule structure at pH 2 and amyloidiogenic intermediate state (I^a) at pH 4. pH induced Shifting of surface exposed hydrophobic patches and that followed by withdrawal of the lone tyrosine residue (Y69) towards nonpolar environment have been reported. Denaturation profile of native and molten globule (MG) states of LBTI in presence of guanidine hydrochloride show sigmoidal curves with non-coincidental and irreversible behaviour in both states. Concentration dependent amyloid fibril formation was confirmed by Thioflavin T and Congo Red binding and its morphology was studied by transmission electron microscopy (TEM). This is the first report on biophysical characterization of folding intermediates of LBTI and its aggregation behaviour to the best of our knowledge.

Type 2 Diabetes in Non-Alcoholic Fatty Liver Disease and Hepatitis C Virus Infection--Liver: The "Musketeer" in the Spotlight

The pathogenesis of type 2 diabetes (T2D) involves chronic hyperinsulinemia due to systemic and hepatic insulin resistance (IR), which if uncorrected, will lead to progressive pancreatic beta cell failure in predisposed individuals. Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of fatty (simple steatosis and steatohepatitis) and non-fatty liver changes (NASH-cirrhosis with or without hepatocellular carcinoma (HCC)) that are commonly observed among individuals with multiple metabolic derangements, notably including visceral obesity, IR and T2D. Hepatitis C virus (HCV) infection is also often associated with both hepatic steatosis and features of a specific HCV-associated dysmetabolic syndrome. In recent years, the key role of the steatotic liver in the development of IR and T2D has been increasingly recognized. Thus, in this comprehensive review we summarize the rapidly expanding body of evidence that links T2D with NAFLD and HCV infection. For each of these two liver diseases with systemic manifestations, we discuss the epidemiological burden, the pathophysiologic mechanisms and the clinical implications. To date, substantial evidence suggests that NAFLD and HCV play a key role in T2D development and that the interaction of T2D with liver disease may result in a "vicious circle", eventually leading to an increased risk of all-cause mortality and liver-related and cardiovascular complications. Preliminary evidence also suggests that improvement of NAFLD is associated with a decreased incidence of T2D. Similarly, the prevention of T2D following HCV eradication in the era of direct-acting antiviral agents is a biologically plausible result. However, additional studies are required for further clarification of mechanisms involved.

Qualitative analysis of patient-centered decision attributes associated with initiating hepatitis C treatment

BACKGROUND

In this era of a constantly changing landscape of antiviral treatment options for chronic viral hepatitis C (CHC), shared clinical decision-making addresses the need to engage patients in complex treatment decisions. However, little is known about the decision attributes that CHC patients consider when making treatment decisions. We identify key patient-centered decision attributes, and explore relationships among these attributes, to help inform the development of a future CHC shared decision-making aid.

METHODS

Semi-structured qualitative interviews with CHC patients at four Veterans Health Administration (VHA) hospitals, in three comparison groups: contemplating CHC treatment at the time of data collection (Group 1), recently declined CHC treatment (Group 2), or recently started CHC treatment (Group 3). Participant descriptions of decision attributes were analyzed for the entire sample as well as by patient group and by gender.

RESULTS

Twenty-nine Veteran patients participated (21 males, eight females): 12 were contemplating treatment, nine had recently declined treatment, and eight had recently started treatment. Patients on average described eight (range 5-13) decision attributes. The attributes most frequently reported overall were: physical side effects (83%); treatment efficacy (79%), new treatment drugs in development (55%); psychological side effects (55%); and condition of the liver (52%), with some variation based on group and gender. Personal life circumstance attributes (such as availability of family support and the burden of financial responsibilities) influencing treatment decisions were also noted by all participants. Multiple decision attributes were interrelated in highly complex ways.

CONCLUSIONS

Participants considered numerous attributes in their CHC treatment decisions. A better understanding of these attributes that influence patient decision-making is crucial in order to inform patient-centered clinical approaches to care (such as shared decision-making augmented with relevant decision-making aids) that respond to patients' needs, preferences, and circumstances.

Association of Baseline Sleep Quality With Trajectories of Depressive Symptoms in Patients Undergoing Interferon Treatment

OBJECTIVE

Some patients with hepatitis C starting interferon-α (IFN-α) therapy experience depression, although many patients do not develop depressive symptoms. We have found that poor sleep is associated with increased depressive symptoms on average. It is unknown whether this association holds generally or is driven by a specific, distinct subgroup. This investigation first determined whether patterns of change in depressive symptoms form clinically meaningful, distinct subgroups and then tested the extent to which sleep disturbances are associated with a less favorable depression trajectory.

METHOD

Group-based trajectory modeling was used on 124 patients with hepatitis C who started IFN-α therapy. The Pittsburgh Sleep Quality Index (PSQI) assessed pretreatment sleep, the Beck Depression Inventory minus the sleep question assessed depression over time, and the Structured Clinical Interview for DSM-IV provided categorical diagnoses.

RESULTS

Three distinct subgroups were found, where each subgroup shared similar patterns of depressive symptoms over time. The groups were characterized as "nondepressed," "slow increase," and "rapid increase." The nondepressed subgroup (44.4%) experienced low depressive symptoms with little change over time. In comparison, all rapid increasers (11.3%) were diagnosed as having a mood disorder by 12 weeks of treatment. The PSQI was strongly associated with group membership, where the odds of developing a rapid increase was elevated 39% for every unit-score increase in the PSQI compared with individuals who remained nondepressed (odds ratio = 1.39, 95% confidence interval = 1.07-1.80, adjusted for depression at baseline).

CONCLUSIONS

Only a distinct subpopulation of people is notably vulnerable to a developing a rapid increase in depression symptoms during IFN-α therapy. This group may be identifiable by their markedly poor sleep before IFN-α therapy.

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.

In vitro drug combination studies of Letermovir (AIC246, MK-8228) with approved anti-human cytomegalovirus (HCMV) and anti-HIV compounds in inhibition of HCMV and HIV replication

Despite modern prevention and treatment strategies, human cytomegalovirus (HCMV) remains a common opportunistic pathogen associated with serious morbidity and mortality in immunocompromised individuals, such as transplant recipients and AIDS patients. All drugs currently licensed for the treatment of HCMV infection target the viral DNA polymerase and are associated with severe toxicity issues and the emergence of drug resistance. Letermovir (AIC246, MK-8228) is a new anti-HCMV agent in clinical development that acts via a novel mode of action and has demonstrated anti-HCMV activity in vitro and in vivo. For the future, drug combination therapies, including letermovir, might be indicated under special medical conditions, such as the emergence of multidrug-resistant virus strains in transplant recipients or in HCMV-HIV-coinfected patients. Accordingly, knowledge of the compatibility of letermovir with other HCMV or HIV antivirals is of medical importance. Here, we evaluated the inhibition of HCMV replication by letermovir in combination with all currently approved HCMV antivirals using cell culture checkerboard assays. In addition, the effects of letermovir on the antiviral activities of selected HIV drugs, and vice versa, were analyzed. Using two different mathematical techniques to analyze the experimental data, (i) additive effects were observed for the combination of letermovir with anti-HCMV drugs and (ii) no interaction was found between letermovir and anti-HIV drugs. Since none of the tested drug combinations significantly antagonized letermovir efficacy (or vice versa), our findings suggest that letermovir may offer the potential for combination therapy with the tested HCMV and HIV drugs.

Cirrhosis regression in hepatitis C patients with sustained virological response after antiviral therapy: a meta-analysis

BACKGROUND & AIMS

Chronic hepatitis C may be associated with cirrhosis, liver failure and hepatocellular carcinoma. Studies have demonstrated improved clinical outcome in patients who achieved a sustained viral response (SVR).

METHODS

A systematic literature search was performed to identify studies that assessed the association between SVR and cirrhosis regression. The main outcome studied was cirrhosis regression in patients with a SVR as compared with patients without a SVR. Six studies totalling 443 patients were included. Dichotomous outcomes were reported as risk ratios (RR) with 95% confidence intervals (CI).

RESULTS

Of the 443 patients with cirrhosis, 137 achieved a SVR. Of these 137 patients who achieved an SVR, 73 (53%) patients had regression of cirrhosis. The risk ratio of cirrhosis regression was 2.69 [Confidence Interval (CI) 1.45-4.97, P < 0.01] in patients who achieved a SVR. The risk of cirrhosis regression was consistently in favour of patients who achieved a SVR regardless of the length of the biopsy or whether the biopsy was reviewed by a single or multiple pathologists. The risk ratio of cirrhosis regression was related to the duration of follow-up between biopsies. The relative risk for regression of cirrhosis in studies in which the mean or median time for the follow-up liver biopsy was greater than 36-month was 4.33 (CI 1.1-17.0, P = 0.04) as compared to a relative risk of 1.79 (CI 1.26-2.29, P < 0.01) in studies with a mean or median time between the follow-up biopsy of less than 36-month.

CONCLUSIONS

Our results suggest that the majority of patients with cirrhosis who achieve a SVR develop cirrhosis regression. Time between biopsies appears to be an important determinant of the likelihood of cirrhosis regression.

Hepatitis C virus molecular evolution: Transmission, disease progression and antiviral therapy

Hepatitis C virus (HCV) infection represents an important public health problem worldwide. Reduction of HCV morbidity and mortality is a current challenge owned to several viral and host factors. Virus molecular evolution plays an important role in HCV transmission, disease progression and therapy outcome. The high degree of genetic heterogeneity characteristic of HCV is a key element for the rapid adaptation of the intrahost viral population to different selection pressures (e.g., host immune responses and antiviral therapy). HCV molecular evolution is shaped by different mechanisms including a high mutation rate, genetic bottlenecks, genetic drift, recombination, temporal variations and compartmentalization. These evolutionary processes constantly rearrange the composition of the HCV intrahost population in a staging manner. Remarkable advances in the understanding of the molecular mechanism controlling HCV replication have facilitated the development of a plethora of direct-acting antiviral agents against HCV. As a result, superior sustained viral responses have been attained. The rapidly evolving field of anti-HCV therapy is expected to broad its landscape even further with newer, more potent antivirals, bringing us one step closer to the interferon-free era.

Pharmacogenetics of hepatitis C: transition from interferon-based therapies to direct-acting antiviral agents

Hepatitis C virus (HCV) has emerged as a major viral pandemic over the past two decades, infecting 170 million individuals, which equates to approximately 3% of the world’s population. The prevalence of HCV varies according to geographic region, being highest in developing countries such as Egypt. HCV has a high tendency to induce chronic progressive liver damage in the form of hepatic fibrosis, cirrhosis, or liver cancer. To date, there is no vaccine against HCV infection. Combination therapy comprising PEGylated interferon-alpha and ribavirin has been the standard of care for patients with chronic hepatitis C for more than a decade. However, many patients still do not respond to therapy or develop adverse events. Recently, direct antiviral agents such as protease inhibitors, polymerase inhibitors, or NS5A inhibitors have been used to augment PEGylated interferon and ribavirin, resulting in better efficacy, better tolerance, and a shorter treatment duration. However, most clinical trials have focused on assessing the efficacy and safety of direct antiviral agents in patients with genotype 1, and the response of other HCV genotypes has not been elucidated. Moreover, the prohibitive costs of such triple therapies will limit their use in patients in developing countries where most of the HCV infection exists. Understanding the host and viral factors associated with viral clearance is necessary for individualizing therapy to maximize sustained virologic response rates, prevent progression to liver disease, and increase the overall benefits of therapy with respect to its costs. Genome wide studies have shown significant associations between a set of polymorphisms in the region of the interleukin-28B (IL28B) gene and natural clearance of HCV infection or after PEGylated interferon-alpha and ribavirin treatment with and without direct antiviral agents. This paper synthesizes the recent advances in the pharmacogenetics of HCV infection in the era of triple therapies.