Boceprevir: a review of its use in the management of chronic hepatitis C genotype 1 infection

Therapeutic peptides: current applications and future directions

Peptide drug development has made great progress in the last decade thanks to new production, modification, and analytic technologies. Peptides have been produced and modified using both chemical and biological methods, together with novel design and delivery strategies, which have helped to overcome the inherent drawbacks of peptides and have allowed the continued advancement of this field. A wide variety of natural and modified peptides have been obtained and studied, covering multiple therapeutic areas. This review summarizes the efforts and achievements in peptide drug discovery, production, and modification, and their current applications. We also discuss the value and challenges associated with future developments in therapeutic peptides.

Discovery of BMS-961955, an allosteric inhibitor of the hepatitis C virus NS5B polymerase

The synthesis, structure-activity relationship (SAR) data, and further optimization of the metabolic stability and pharmacokinetic (PK) properties for a previously disclosed class of cyclopropyl-fused indolobenzazepine HCV NS5B polymerase inhibitors are described. These efforts led to the discovery of BMS-961955 as a viable contingency backup to beclabuvir which was recently approved in Japan for the treatment of HCV as part of a three drug, single pill combination marketed as Ximency^TM.

The influence of host factors and sequence variability of the p7 region on the response to pegylated interferon/ribavirin therapy for chronic hepatitis C genotype 1b in patients from Serbia

The goal of this study was to identify host and viral factors affecting the response to pegylated interferon/ribavirin (PEG-IFN/RBV) treatment in patients with chronic hepatitis C genotype 1b. Baseline characteristics of the patients and sequences within the p7 region were analyzed in pre-treatment serum samples from 53 individuals with chronic hepatitis C genotype 1b and related to the outcome of therapy. We found a significant correlation between age and response to therapy (p < 0.001). Furthermore, the pre-treatment viral load was closely associated with the stage of liver fibrosis (p < 0.001). The presence of fewer than 4 mutations and age above 40 were significantly associated with non-response (NR) (p < 0.001). Our findings may be useful for estimating the likelihood of achieving a sustained virologic response (SVR) in patients who are chronically infected with hepatitis C virus genotype 1b.

Simeprevir: a review of its use in patients with chronic hepatitis C virus infection

Simeprevir (Olysio™; Galexos™; Sovriad®) is an orally-administered NS3/4A protease inhibitor for use in combined drug regimens against chronic hepatitis C virus (HCV) infection. This article reviews studies relevant to the EU simeprevir label. In proof-of-concept studies, simeprevir had potent antiviral activity against all HCV genotypes, except genotype 3. In trials in patients with chronic HCV genotype 1 infection, week-12 sustained virological response (SVR12) rates in treatment-naïve patients and prior relapsers were significantly higher with simeprevir plus peginterferon-α/ribavirin (PR) [79-89 %] than with placebo plus PR (36-62 %). In prior partial/null responders, the SVR12 rate with simeprevir plus PR (54 %) was noninferior to that with telaprevir plus PR (55 %). Simeprevir plus PR was also efficacious in patients with HCV genotype 1/HIV-1 co-infection. In prior null responders without severe liver fibrosis (cohort 1) and treatment-naïve patients with severe liver fibrosis (cohort 2) treated with simeprevir plus sofosbuvir, the SVR12 rate for the two cohorts combined was 92 %. In patients with chronic HCV genotype 4 infection, the SVR12 rates with simeprevir plus PR were 83, 87 and 40 % in treatment-naïve patients, prior relapsers and prior null responders, respectively. Grade 3-4 adverse event, serious adverse event and treatment withdrawal rates with simeprevir plus PR were similar to those with placebo plus PR. Skin rashes with simeprevir were mostly mild or moderate; serious photosensitivity reactions occur, but are rare. Simeprevir is efficacious and generally well tolerated in patients with chronic HCV genotypes 1 and 4 infection. Studies of simeprevir in interferon-free regimens and in other subpopulations with HCV infections will be of interest.

Barriers to HCV treatment in the era of triple therapy: a prospective multi-centred study in clinical practice

BACKGROUND & AIMS

(i) To describe the demographic, clinical, virological and histological characteristics of the patients undergoing evaluation for indication of triple therapy against hepatitis C virus genotype 1, and to identify the reasons why candidate patients are excluded; and (ii) to evaluate the characteristics of the healthcare environment related to treatment.

METHODS

Observational, prospective and multi-centred study involving 16 hospitals of Spain. Data were collected on 1122 patients receiving attention in the outpatient clinics between June and December 2012.

RESULTS

Of the 1122 patients evaluated, 769 were finally included in this study; 27% (211/769) had contraindications to the therapy. Of those without contraindications, 54% (301/558) did not receive the treatment, and so, only about a third of the patients (33%-257/769) underwent therapy. The reasons for not initiating therapy were as follows: patient refusal (30%), mild disease/awaiting new treatments (34%), restrictions by the health service (30%), other reasons (6%). In univariate analyses, the probability of receiving treatment was related to: age <60 years, male gender, high education level, advanced fibrosis, having had previous treatment, being assessed in a centre of excellence. In multivariate analyses, the factors independently related to the probability of receiving treatment were as follows: high education level of the patients (P = 0.004), advanced fibrosis (P < 0.001) and centres of excellence (P = 0.009).

CONCLUSION

Despite the high efficacy of triple therapy, only a small proportion of patients receive the treatment. The causes related to non-treatment depend on patient factors, disease stage and characteristics of the health-service provision.

Sampling variability between two mid-turbinate swabs of the same patient has implications for influenza viral load monitoring

Background

With the clinical development of several antiviral intervention strategies for influenza, it becomes crucial to explore viral load shedding in the nasal cavity as a biomarker for treatment success, but also to explore sampling strategies for sensible and reliable virus collection.

Findings

In this study, 244 patients suffering from Influenza like Illness and/or acute respiratory tract infection were enrolled. Sampling was done using mid-turbinate flocked swabs and two swabs per patient were collected (one swab per nostril). The influenza A viral loads of two mid-turbinate flocked swabs (one for each nostril) per patient were compared and we have also assessed whether normalization for human cellular DNA in the swabs could be useful. The Influenza mid-turbinate nasal swab testing resulted in considerable sampling variability that could not be normalized against co-isolated human cellular DNA.

Conclusions

Influenza viral load monitoring in nasal swabs could be very valuable as virological endpoints in clinical trials to monitor treatment efficacy, in analogy to HIV, HBV & HCV viral load monitoring. However, the differences between left and right nostrils, as observed in this study, highlight the importance of proper sampling and the need for standardized sampling procedures.

Resistance patterns associated with HCV NS5A inhibitors provide limited insight into drug binding

Direct-acting antivirals (DAAs) have significantly improved the treatment of infection with the hepatitis C virus. A promising class of novel antiviral agents targets the HCV NS5A protein. The high potency and broad genotypic coverage are favorable properties. NS5A inhibitors are currently assessed in advanced clinical trials in combination with viral polymerase inhibitors and/or viral protease inhibitors. However, the clinical use of NS5A inhibitors is also associated with new challenges. HCV variants with decreased susceptibility to these drugs can emerge and compromise therapy. In this review, we discuss resistance patterns in NS5A with focus prevalence and implications for inhibitor binding.

Simeprevir: first global approval

Simeprevir (Sovriad(TM)) is a new direct-acting antiviral drug and a second-generation small-molecule NS3/4A serine protease inhibitor developed by Janssen and Medivir for the oral treatment of adults with genotype 1 and/or genotype 4 chronic hepatitis C virus (HCV) infection (chronic hepatitis C). Simeprevir antiviral activity is achieved by its non-covalent binding to HCV protease, with a fast association and slow dissociation rate. The capsule formulation is approved in Japan and Canada for use in combination with pegylated interferon (peginterferon) and ribavirin for genotype 1 chronic hepatitis C, and has been filed for approval in the US in this indication. In addition, the capsule formulation has been filed for approval in the EU for use in combination with peginterferon and ribavirin for genotype 1 and 4 chronic hepatitis C. Phase III trials of the capsule formulation of simeprevir are underway in several other regions, including China. In the pivotal phase III trials, simeprevir was administered once daily for 12 weeks in combination with peginterferon and ribavirin for 24 or 48 weeks. This article summarizes the milestones in the development of simeprevir leading to this first approval for chronic hepatitis C.

Drug interactions between antiretrovirals and new or emerging direct-acting antivirals in HIV/hepatitis C virus coinfection

PURPOSE OF REVIEW

We reviewed the pharmacokinetic interactions between direct-acting antivirals against hepatitis C virus (HCV) and antiretroviral agents.

RECENT FINDINGS

Most relevant pharmacokinetic studies involve healthy individuals and refer to the already licensed HCV protease inhibitors, boceprevir and telaprevir. Data from a phase II clinical trial question the clinical relevance of the interactions between boceprevir and HIV protease inhibitors. The use of a higher dose of telaprevir appears to offset the effect of efavirenz on telaprevir metabolism according to another phase II trial. Boceprevir and particularly telaprevir substantially increase the exposure to maraviroc, similarly to other potent CYP3A4 inhibitors. Different dosages of faldaprevir and daclatasvir have been recommended to be used in combination with a boosted HIV protease inhibitor vs. an efavirenz-based antiretroviral regimen. HIV protease inhibitors appear to substantially increase the exposure to simeprevir. The interactions between sofosbuvir and most antiretroviral agents do not appear to be of clinical relevance or to require dosage modifications.

SUMMARY

The drug-drug interaction studies for HCV direct-acting antivirals and antiretrovirals are important in determining the appropriate drug combinations and dosages. The clinical implications of these interactions need further assessment in different categories of patients, including those with cirrhosis.

Pharmacokinetics of the co-administration of boceprevir and St John's wort to male and female healthy volunteers

BACKGROUND

St John's wort (SJW; Hypericum perforatum) induces CYP3A4 that is involved in the metabolism of the hepatitis C virus (HCV) protease inhibitor boceprevir. Reduced boceprevir exposure and efficacy would contribute to therapeutic failure and increase the risk for resistance development. Boceprevir is co-administered with interferon/ribavirin, and depression has been described frequently in patients undergoing HCV treatment. Patients may purchase over-the-counter herbals to manage depression, and knowing the interaction between SJW and boceprevir is desirable.

METHODS

This Phase I, open-label, three-period, cross-over pharmacokinetic study enrolled healthy males and females who, following consent and screening procedures, were randomized to receive SJW on days 1-14, SJW plus boceprevir (SJW on days 22-35 and together on days 31-35) and boceprevir on days 52-56, separated by 7 day washout periods, or the same treatment in the opposite order. Pharmacokinetic sampling was performed at the end of each phase.

RESULTS

Seventeen (11 female) subjects completed the study and no serious adverse events were reported. Geometric mean ratios (GMRs) and 90% CIs for boceprevir (with SJW versus alone) AUC(0-8), C(max) and C8 were 0.91 (0.87-0.96), 0.94 (0.82-1.07) and 1.00 (0.79-1.27), respectively. GMRs and 90% CIs for hypericin, the active component of SJW, (with boceprevir versus alone) AUC(0-8), C(max) and C(8) were 1.23 (1.10-1.38), 1.32 (1.16-1.52) and 1.37 (1.19-1.58), respectively.

CONCLUSIONS

SJW did not have a clinically significant effect on boceprevir plasma concentrations (or those of its metabolite), suggesting that SJW and boceprevir can be safely co-administered.

Discovery and preclinical characterization of the cyclopropylindolobenzazepine BMS-791325, a potent allosteric inhibitor of the hepatitis C virus NS5B polymerase

Described herein are structure-activity relationship studies that resulted in the optimization of the activity of members of a class of cyclopropyl-fused indolobenzazepine HCV NS5B polymerase inhibitors. Subsequent iterations of analogue design and syntheses successfully addressed off-target activities, most notably human pregnane X receptor (hPXR) transactivation, and led to significant improvements in the physicochemical properties of lead compounds. Those analogues exhibiting improved solubility and membrane permeability were shown to have notably enhanced pharmacokinetic profiles. Additionally, a series of alkyl bridged piperazine carboxamides was identified as being of particular interest, and from which the compound BMS-791325 (2) was found to have distinguishing antiviral, safety, and pharmacokinetic properties that resulted in its selection for clinical evaluation.

Dynamics of resistance mutations to NS3 protease inhibitors in a cohort of Brazilian patients chronically infected with hepatitis C virus (genotype 1) treated with pegylated interferon and ribavirin: a prospective longitudinal study

Abstract

About sixty thousand new cases of Hepatitis C virus (HCV) infection are recorded in Brazil each year. These cases are currently treated with pegylated interferon (PEG-IFN) and ribavirin (RBV) with an overall success rate of 50%. New compounds for anti-HCV therapy targeted to the HCV NS3 protease are being developed and some already form the components of licensed therapies. Mapping NS3 protease resistance mutations to protease inhibitors or anti-viral drug candidates is important to direct anti-HCV drug treatment.

Methods

Sequence analysis of the HCV NS3 protease was conducted in a group of 68 chronically infected patients harboring the HCV genotype 1. The patients were sampled before, during and after a course of PEG-IFN-RBV treatment.

Results

Resistance mutations to the protease inhibitors, Boceprevir and Telaprevir were identified in HCV isolated from three patients (4.4%); the viral sequences contained at least one of the following mutations: V36L, T54S and V55A. In one sustained virological responder, the T54S mutation appeared during the course of PEG-IFN and RBV therapy. In contrast, V36L and V55A mutations were identified in virus isolated from one relapsing patient before, during, and after treatment, whereas the T54S mutation was identified in virus isolated from one non-responding patient, before and during the treatment course.

Conclusions

The incidence and persistence of protease resistance mutations occurring in HCV from chronically infected patients in Brazil should be considered when using protease inhibitors to treat HCV disease. In addition, patients treated with the current therapy (PEG-IFN and RBV) that are relapsing or are non-responders should be considered candidates for protease inhibitor therapy.