Sofosbuvir, velpatasvir and voxilaprevir combination for the treatment of hepatitis C

Peptide therapeutics: current status and future opportunity with focus on nose-to-brain delivery☆

Peptide drugs are a highly diverse group of therapeutic agents. Over the last decade, more than 40 peptides have been approved for clinical use. They target different structures, ranging from G protein-coupled receptors (GPCRs) to pathogens and are used to treat a variety of indications, including metabolic disorders, genetic diseases, acute illnesses and more. Structurally, peptide therapeutics are a heterogeneous class. This diversity allows them to bridge the gap between small molecules and biologics. However, limited metabolic stability and bioavailability must be addressed. Strategies to improve the half-life include backbone and sequence modification, cyclization and the addition of stabilizing moieties. Great strides have been made in recent years towards achieving sufficient drug uptake for oral application have been achieved within recent years. However, these methods require specialized peptide design or involve permeabilization of the gastrointestinal tract. Consequently, other routes of administration are being explored. One promising approach is the nasal application of peptides. This method can be used for systemic uptake, but also allows for direct nose-to-brain delivery of compounds. While successful nose-to-brain delivery is already used in the clinic, the underlining mechanisms are poorly understood. Strategies for rational optimization are needed to make this method more applicable to a wider range of compounds. Overall, approved peptide therapeutics cover a wide range of applications and have demonstrated a growing and novel potential in recent drug discovery.

Daclatasvir as a hepatitis C infection treatment option: an up-to-date evaluation

INTRODUCTION

Globally, it is estimated that 290,000 patients infected with hepatitis C virus (HCV) died from hepatitis C consequences, including cirrhosis and hepatocellular carcinoma in 2019. Although daclatasvir (DCV), combined with sofosbuvir (SOF), is effective in HCV patients, the new pan-genotypic combinations are considered by many as more cost-effective and successful in eradicating HCV infection.

AREAS COVERED

This review discusses the safety, efficacy, and cost-effectiveness of DCV as an HCV treatment option based on real-world studies and pharmacoeconomic evaluations.

EXPERT OPINION

Real-life studies suggest that SOF/DCV has acceptable sustained virological response and can be used successfully to manage HCV. Nonetheless, the use of SOF/DCV is limited by the longer treatment duration in genotype (GT)-3 patients and the need for ribavirin (RBV) in treatment-experienced patients which increases the likelihood of adverse effects. DCV is likely to remain as a therapeutic option for the management of GT-1, GT-2, and GT-4 patients in resource limited settings, while GT-3 patients are more likely to benefit from RBV-free direct-acting antiviral combinations such as SOF/velpatasvir for 12 weeks or glecaprevir/pibrentasvir for 8 weeks. The introduction of generics for these new pan-genotypic drugs would likely eliminate the need for SOF/DCV in the near future.

Sofosbuvir/Velpatasvir/Voxilaprevir for Previous Treatment Failures With Glecaprevir/Pibrentasvir in Chronic Hepatitis C Infection

OBJECTIVES

Chronic hepatitis C-infected patients who do not respond to nonstructural 5A inhibitor-containing regimens have few treatment options. It is unclear if patients who fail glecaprevir/pibrentasvir (G/P) (Mavyret) can be re-treated with sofosbuvir/velpatasvir/voxilaprevir (SOF/VEL/VOX) (Vosevi) because the latter's registration trials antedated the availability of the former.

METHODS

Adherent virologic failures to G/P were re-treated with 12 weeks of SOF/VEL/VOX, and all subjects underwent resistance testing at baseline and again with subsequent relapse.

RESULTS

Ninety-four percent of subjects achieved sustained virologic response with re-treatment, despite 90% of 31 subjects harboring nonstructural 5A inhibitor resistance-associated mutations at baseline.

DISCUSSION

SOF/VEL/VOX is an effective regimen for virologic failures to G/P.

A pan-genotypic Hepatitis C Virus NS5A amplification method for reliable genotyping and resistance testing

BACKGROUND

Chronic infection with the Hepatitis C Virus (HCV) is associated with the risk of progressive liver disease. Although, HCV treatment options and viral cure rates have tremendously increased over the last decade, all currently licensed combination therapies contain inhibitors of the replication complex NS5A. Resistance-associated substitutions (RAS) in NS5A can limit the efficacy of therapy; however, resistance testing is routinely not recommended for all patients. Notably, pan-genotypic combinations have been approved, however the correct identification of the HCV genotype is still required for treatment decisions and is a good predictor for treatment success.

OBJECTIVE

The aim of this study was the establishment of a pan-genotypic NS5A amplification method for reliable genotyping and simultaneous resistance testing in a fast and cheap routine diagnostic setup.

STUDY DESIGN

Pan-genotypic degenerated nested PCR primer were designed and tested in 262 HCV-patients. The collection included samples from genotypes 1-7 and the median viral load was 1.07 × 10⁶ IU/ml (range 248-21 × 10⁶ IU/ml).

RESULTS

Amplification of the expected 747bp fragment was successful in 257 of 262 (98.1%) samples including samples <1000 IU/ml. The direct comparison of the genotype information obtained with core sequencing to those obtained by NS5A prediction showed high concordance (97.3%) and discrepancies occurred only for relatively rare subtypes. Resistance analysis using Geno2Pheno_[HCV] showed NS5A-RAS in 23 of 257 (8.9%) of samples.

CONCLUSIONS

We successfully developed a routine diagnostic method for pan-genotypic amplification of NS5A. This amplicon can be used for simultaneous genotyping and resistance testing for enhancing and improving routine HCV diagnostic.

Real-World Efficacy and Safety of Pangenotypic Direct-Acting Antivirals Against Hepatitis C Virus Infection

BACKGROUND

Advances in the development of Direct-Acting Antivirals (DAAs), particularly pangenotypic drugs, have led to a high rate of hepatitis C virus (HCV) eradication. Notably, real- world studies have confirmed the efficacy and safety of pangenotypic DAA combinations reported in registration trials. The aim of this study was to review the treatment recommendations, and the efficacy and safety data of anti-HCV pangenotypic drugs reported in registration clinical trials and in recent real-life cohort studies.

METHODS

We reviewed the efficacy and safety data of pangenotypic anti-HCV drug combinations reported in original articles and in online conference abstracts.

RESULTS

Current pangenotypic drug combinations resulted in very high rates of sustained virologic response and few adverse reactions in real-life settings. SVR12 rates in real-life studies ranged from 90-100% depending on the pangenotypic combination, the HCV genotype and the stage of liver disease. Most adverse reactions reported in real-life settings were mild in intensity and rarely led to treatment discontinuation. These results are in accordance with those of clinical trials.

CONCLUSION

Pangenotypic DAAs result in very high rates of sustained virologic responses and are well tolerated. However, they are contraindicated in patients with decompensated cirrhosis or advanced chronic kidney disease who failed previous DDA-based treatment. Further research is required to customize treatment to "unpackage" current DAA combinations and to develop generic drugs against HCV.

Development of an Infectious Cell Culture System for Hepatitis C Virus Genotype 6a Clinical Isolate Using a Novel Strategy and Its Sensitivity to Direct-Acting Antivirals

Hepatitis C virus (HCV) is classified into seven major genotypes, and genotype 6 is commonly prevalent in Asia, thus reverse genetic system representing genotype 6 isolates in prevalence is required. Here, we developed an infectious clone for a Chinese HCV 6a isolate (CH6a) using a novel strategy. We determined CH6a consensus sequence from patient serum and assembled a CH6a full-length (CH6aFL) cDNA using overlapped PCR product-derived clones that shared the highest homology with the consensus. CH6aFL was non-infectious in hepatoma Huh7.5 cells. Next, we constructed recombinants containing Core-NS5A or 5′UTR-NS5A from CH6a and the remaining sequences from JFH1 (genotype 2a), and both were engineered with 7 mutations identified previously. However, they replicated inefficiently without virus spread in Huh7.5 cells. Addition of adaptive mutations from CH6a Core-NS2 recombinant, with JFH1 5′UTR and NS3-3′UTR, enhanced the viability of Core-NS5A recombinant and acquired replication-enhancing mutations. Combination of 22 mutations in CH6a recombinant with JFH1 5′UTR and 3′UTR (CH6aORF) enabled virus replication and recovered additional four mutations. Adding these four mutations, we generated two efficient recombinants containing 26 mutations (26m), CH6aORF_26m and CH6aFL_26m (designated “CH6acc”), releasing HCV of 10^4.3–10^4.5 focus-forming units (FFU)/ml in Huh7.5.1-VISI-mCherry and Huh7.5 cells. Seven newly identified mutations were important for HCV replication, assembly, and release. The CH6aORF_26m virus was inhibited in a dose- and genotype-dependent manner by direct-acting-antivirals targeting NS3/4A, NS5A, and NS5B. The CH6acc enriches the toolbox of HCV culture systems, and the strategy and mutations applied here will facilitate the culture development of other HCV isolates and related viruses.

Review article: novel antivirals for hepatitis C-sofosbuvir/velpatasvir/voxilaprevir, glecaprevir/pibrentasvir

BACKGROUND

In 2017, the hepatitis C treatment regimens sofosbuvir/velpatasvir/voxilaprevir (SOF/VEL/VOX) and glecaprevir/pibrentasvir (G/P) received approval from the U.S. Food and Drug Administration. Although both SOF/VEL/VOX (NS5B polymerase inhibitor/NS5A inhibitor/NS3/4A protease inhibitor) and G/P (NS3/4A protease inhibitor/NS5A inhibitor) are pangenotypic regimens, they are indicated for distinct subsets of patients with hepatitis C.

AIM

To compare and contrast available safety and efficacy data for SOF/VEL/VOX and G/P and outline their clinical utility.

METHODS

For each of the regimens, this review outlines the indications, safety information, and the major clinical studies in which SOF/VEL/VOX and G/P were evaluated.

RESULTS

SOF/VEL/VOX is positioned as a salvage regimen for patients previously treated with NS5A inhibitors and for genotype 1a- and 3-infected patients who had failed other sofosbuvir-containing regimens. G/P is the first pangenotypic regimen with an 8-week duration for treatment-naïve, non-cirrhotic patients, and it is indicated for patients with any genotype who have advanced kidney disease, including those on dialysis.

CONCLUSION

The addition of SOF/VEL/VOX and G/P to existing hepatitis C treatment options will expand the number of patients who are eligible for and responsive to treatment, thus increasing the possibility of eliminating hepatitis C as a public health issue.

Patients with chronic hepatitis C receiving sofosbuvir and ribavirin-based treatment, with or without interferon in Zhejiang, China: An observational study

Hepatitis C virus (HCV) is one of the most important virus as the cause of liver disease in China. The aim of the present study was to explore whether sofosbuvir and ribavirin-based treatment can cure patients with chronic hepatitis C in eastern China. We examined a cohort of HCV-monoinfected patients and 9 patients agreed to participate in our treatment and research. The patients were diagnosed with chronic hepatitis C with or without cirrhosis. Nine patients including 4 female and 5 male met the requirements for selection and were willing to participate in this experiment. Sofosbuvir and ribavirin-based treatment with or without interferon was given to the patients. Viral loads, cytokines, and chemokines were recorded during treatment and after treatment. After 2 weeks of sofosbuvir and ribavirin-based treatment, the viral load of patients decreased to limits of detection. Eight patients were cured. Patients had rapid virological response (RVR) with undetectable viral load at week 4 and sustained virological response (SVR). The interferon-inducible protein-10 (IP-10) decreased after the treatment. However, the patient with cirrhosis failed, as the virus reappeared during SVR4. At the same time, the IP-10 dramatically increased as the relapse of the HCV virus. In summary, the IP-10 has the potential to be the biomarker for the prognostic of HCV.

From Oxiranes to Oligomers: Architectures of U.S. FDA Approved Pharmaceuticals Containing Oxygen Heterocycles

Oxygen heterocycles are the second most common type of heterocycles that appear as structural components of U.S. Food and Drug Administration (FDA) approved pharmaceuticals. Analysis of our database of drugs approved through 2017 reveals 311 distinct pharmaceuticals containing at least one oxygen heterocycle. Most prevalent among these are pyranoses, with furanoses, macrolactones, morpholines, and dioxolanes rounding off the top five. The main body of this Perspective is organized according to ring size, commencing with three- and four-membered rings and ending with macrocycles, polymers, and unusual oxygen-containing heterocycles. For each section, all oxygen heterocycle-containing drugs are presented along with a brief discussion about structural and drug application patterns.

Retreatment Efficacy of Sofosbuvir/Ombitasvir/Paritaprevir/Ritonavir + Ribavirin for Hepatitis C Virus Genotype 4 Patients

BACKGROUND

The current standard of care for patients with chronic hepatitis C virus (HCV) infection is a combination of direct-acting antiviral agents (DAAs). However, rare clinical trials have been reported on the combination regimen of sofosbuvir (SOF) with ombitasvir, paritaprevir, and ritonavir (OBV/PTV/r) plus ribavirin (RBV) for treated patients with HCV genotype 4 (GT4) infection.

AIMS

To clarify the retreatment efficacy and safety of the recent regimen, SOF with OBV/PTV/r + RBV, for chronic HCV GT4-experienced patients who failed treatment with DAA-based regimens.

METHODS

A total of 113 treatment-experienced patients were allocated for the completion of their treatment period. The enrolled patients were treated orally with SOF plus a fixed dose combination of OBV/PTV/r + RBV, which was administered orally based on the patients' tolerability. The primary end point was a sustained virological response (HCV RNA < 15 IU/mL), observed 12 weeks after the end of the treatment (SVR12).

RESULTS

Among all patients, the treatment-experienced patients with SOF plus OBV/PTV/r + RBV had a higher SVR12 rate (97%; 109/113). Further, SVR12 was achieved by 98% (81/83) of non-cirrhotic patients and 93% (28/30) of cirrhotic patients. Additionally, the most common adverse events reported included fatigue, headache, insomnia, nausea, and dyspnea.

CONCLUSIONS

The recent multi-targeted regimen of SOF plus OBV/PTV/r + RBV was well tolerated and achieved excellent SVR rates among retreatment-experienced Egyptian patients with prior DAA treatments failure, thus providing an alternative regimen for the retreatment of difficult-to-cure HCV GT4 patients.

Efficacy of NS5A Inhibitors Against Hepatitis C Virus Genotypes 1-7 and Escape Variants

BACKGROUND & AIMS

Inhibitors of the hepatitis C virus (HCV) NS5A protein are a key component of effective treatment regimens, but the genetic heterogeneity of HCV has limited the efficacy of these agents and mutations lead to resistance. We directly compared the efficacy of all clinically relevant NS5A inhibitors against HCV genotype 1-7 prototype isolates and resistant escape variants, and investigated the effects of pre-existing resistance-associated substitutions (RAS) on HCV escape from treatment.

METHODS

We measured the efficacy of different concentrations of daclatasvir, ledipasvir, ombitasvir, elbasvir, ruzasvir, velpatasvir, and pibrentasvir in cultured cells infected with HCV recombinants expressing genotype 1-7 NS5A proteins with or without RAS. We engineered HCV variants that included RAS identified in escape experiments, using recombinants with or without T/Y93H and daclatasvir, or that contained RAS previously reported from patients.

RESULTS

NS5A inhibitors had varying levels of efficacy against original and resistant viruses. Only velpatasvir and pibrentasvir had uniform high activity against all HCV genotypes tested. RAS hotspots in NS5A were found at amino acids 28, 30, 31, and 93. Engineered escape variants had high levels of fitness. Pibrentasvir had the highest level of efficacy against variants; viruses with RAS at amino acids 28, 30, or 31 had no apparent resistance to pibrentasvir, and HCV with RAS at amino acid 93 had a low level of resistance to this drug. However, specific combinations of RAS and deletion of amino acid 32 led to significant resistance to pibrentasvir. For the remaining NS5A inhibitors tested, RAS at amino acids 28 and 93 led to high levels of resistance. Among these inhibitors, velpatasvir was more effective against variants with RAS at amino acid 30 and some variants with RAS at amino acid 31 than the other agents. Variants with the pre-existing RAS T/Y93H acquired additional NS5A changes during escape experiments, resulting in HCV variants with specific combinations of RAS, showing high fitness and high resistance.

CONCLUSIONS

We performed a comprehensive comparison of the efficacy of the 7 clinically relevant inhibitors of HCV NS5A and identified variants associated with resistance to each agent. These findings could improve treatment of patients with HCV infection.

Potent Inhibitors of Hepatitis C Virus NS3 Protease: Employment of a Difluoromethyl Group as a Hydrogen-Bond Donor

The design and synthesis of potent, tripeptidic acylsulfonamide inhibitors of HCV NS3 protease that contain a difluoromethyl cyclopropyl amino acid at P1 are described. A cocrystal structure of 18 with a NS3/4A protease complex suggests the presence of a H-bond between the polarized C-H of the CHF₂ moiety and the backbone carbonyl of Leu135 of the enzyme. Structure-activity relationship studies indicate that this H-bond enhances enzyme inhibitory potency by 13- and 17-fold compared to the CH₃ and CF₃ analogues, respectively, providing insight into the deployment of this unique amino acid.

Sofosbuvir and velpatasvir with or without voxilaprevir in direct-acting antiviral-naïve chronic hepatitis C: patient-reported outcomes from POLARIS 2 and 3

BACKGROUND

Chronic hepatitis C infection leads to impairment of patient-reported outcomes (PROs). Treatment with direct-acting antiviral regimens results in short- and long-term improvement of these outcomes.

AIM

To assess PROs in patients treated with a newly developed direct-acting antiviral, a fixed-dose combination of sofosbuvir/velpatasvir (SOF/VEL) with/without voxilaprevir (VOX).

METHODS

The PRO data were collected from participants of POLARIS-2 and POLARIS-3 clinical trials (DAA-naïve, all HCV genotypes). Participants self-administered SF-36v2, FACIT-F, CLDQ-HCV and WPAI:SHP instruments at baseline, during treatment, and in follow-up.

RESULTS

Of 1160 patients, 611 received SOF/VEL/VOX and 549 received SOF/VEL (52.8 ± 11.0 years, 55.9% male, 75.4% treatment-naïve, 33.9% cirrhotic). The sustained viral response at 12 weeks (SVR12) rates were 95%-98%. During treatment, improvements in most PRO scores were significant (all but one P < .01) and ranged from, on average, +2.3 to +15.0 points (on a 0-100 scale) by the end of treatment. These improvements were similar between SOF/VEL/VOX and SOF/VEL arms (all P > .05). After treatment discontinuation, patients treated with both regimens achieved significant and clinically meaningful PRO gains (+2.7 to +16.7 by post-treatment week 12, +3.9 to +20.1 by post-treatment week 24; all but one P < .001). Multivariate analysis showed that depression, anxiety and cirrhosis were the most consistent independent predictors of PRO impairment while no association of PROs with the treatment regimen choice was found (all P > .05).

CONCLUSIONS

The pan-genotypic regimens with SOF/VEL with or without VOX not only have excellent efficacy and safety, but also significantly positively impact patients' experience both during treatment and after achieving sustained virologic response in DAA-naïve patients with HCV.

Effectiveness of current and future regimens for treating genotype 3 hepatitis C virus infection: a large-scale systematic review

BACKGROUND

Six distinct genetic variants (genotypes 1 - 6) of hepatitis C virus (HCV) exist globally. Certain genotypes are more prevalent in particular countries or regions than in others but, globally, genotype 3 (GT3) is the second most common. Patients infected with HCV GT1, 2, 4, 5 or 6 recover to a greater extent, as measured by sustained virological response (SVR), following treatment with regimens based on direct-acting antivirals (DAAs) than after treatment with older regimens based on pegylated interferon (Peg-IFN). GT3, however, is regarded as being more difficult to treat as it is a relatively aggressive genotype, associated with greater liver damage and cancer risk; some subgroups of patients with GT3 infection are less responsive to current licensed DAA treatments. Newer DAAs have become available or are in development.

METHODS

According to PRISMA guidance, we conducted a systematic review (and descriptive statistical analysis) of data in the public domain from relevant clinical trial or observational (real-world) study publications within a 5-year period (February 2011 to May 2016) identified by PubMed, Medline In-Process, and Embase searches. This was supplemented with a search of five non-indexed literature sources, comprising annual conferences of the AASLD, APASL, CROI, EASL, and WHO, restricted to a 1-year period (April 2015 to May 2016).

RESULTS

Of the all-oral regimens, the efficacy (SVR12 ≥ 90%) of sofosbuvir plus daclatasvir- and velpatasvir-based regimens in clinical trials supports and reinforces their recommendation by guidelines. Other promising regimens comprise grazoprevir + elbasvir + sofosbuvir, and ombitasvir + paritaprevir/ribavirin + sofosbuvir. Newer regimens incorporating pibrentasvir + glecaprevir or grazoprevir + ruzasvir + MK-3682 (uprifosbuvir), offer all-oral, ribavirin-free SVR12 rates consistently greater than 95%. Observational studies report slightly lower overall SVR rates but reflect corresponding clinical trial data in terms of treatments most likely to achieve good responses.

CONCLUSIONS

On the basis of SVR12, we established that for treating GT3 infections (i) regimens incorporating newer DAAs are more effective than those comprising older DAAs, and (ii) ribavirin may be of less benefit in newer DAA regimens than in older DAA regimens. The analysis provides evidence that DAA regimens can replace Peg-IFN-based regimens for GT3 infection.