Viral kinetics analysis and virological characterization of treatment failures in patients with chronic hepatitis C treated with sofosbuvir and an NS5A inhibitor

Decompensated cirrhosis and liver transplantation negatively impact in DAA treatment response: Real-world experience from HCV-LALREAN cohort

INTRODUCTION

Although the effectiveness of direct-acting antivirals (DAAs) for the treatment of chronic hepatitis C virus (HCV) has been reported in real-world settings, predictive factors of treatment failure are lacking. Therefore, we sought to explore the baseline predictors of treatment response to DAAs.

METHODS

This was a prospective multicenter cohort study from the Latin American Liver Research Educational and Awareness Network (LALREAN) including patients who received DAA treatment from May 2016 to April 2019. A multivariate logistic regression model was conducted to identify variables associated with unachieved sustained virological response (SVR), defined as treatment failure (odds ratios [OR] and 95% confidence intervals [CIs]).

RESULTS

From 2167 patients (55.2% with cirrhosis) who initiated DAA therapy, 89.4% completed a full-course treatment (n = 1938). Median treatment duration was 12 weeks, and 50% received ribavirin. Definitive suspension due to intolerance or other causes was observed in only 1.0% cases (n = 20). Overall non-SVR12 was 4.5% (95% CI, 3.5-5.7). There were no significant differences in treatment failure according to HCV genotypes and the degree of fibrosis. Independently associated variables with DAA failure were liver function impairment according to the Child-Pugh score B OR, 2.09 (P = .06), Child-Pugh C OR, 11.7 (P < .0001); and liver transplant (LT) recipient OR, 3.75 (P = .01).

CONCLUSION

In this real-life setting, higher DAA treatment failure rates were observed in patients with decompensated cirrhosis and in LT recipients. These predictive baseline factors should be addressed to individualize the appropriate time-point of DAA treatment (NCT03775798; www.

CLINICALTRIALS

gov).

Fitness-associated substitutions following failure of direct-acting antivirals assessed by deep sequencing of full-length hepatitis C virus genomes

BACKGROUND

In hepatitis C virus (HCV) infection, treatment failure is generally associated with the selection of resistance-associated substitutions (RAS) conferring reduced susceptibility to direct-acting antiviral (DAA) drugs. Resistant variants continue to replicate after the end of treatment with potential for transmission. This may result from the selection of "fitness-associated substitutions".

AIM

To characterise potential "fitness-associated substitutions" in patients infected with genotype 3a failing DAA drugs METHODS: By means of shotgun metagenomics, we sequenced full-length HCV genomes at treatment initiation and at virological relapse in eight patients infected with genotype 3a with cirrhosis failing sofosbuvir and an NS5A inhibitor. The impact of amino acid changes occurring outside of DAA target regions selected in at least two patients were assessed on the in vitro susceptibility to an NS5A inhibitor and replication capacity.

RESULTS

At treatment failure, besides selection of known NS5A RASs, especially Y93H, a large number of amino acid changes was observed outside of DAA target regions. We identified four amino acid positions at which observed changes substantially improved in vitro replication capacity without affecting NS5A inhibitor susceptibility.

CONCLUSIONS

This is the first in vivo observation combined with in vitro confirmation of selection of phenotypically characterised "fitness-associated substitutions" together with RASs at the time of sofosbuvir-NS5A inhibitor treatment failure in patients infected with genotype 3a with cirrhosis. Our findings may explain the persistence of resistant HCV variants after treatment in patients who did not achieve sustained virological remission.

Effect of Low Positive End of Treatment Viral Load with Direct-Acting Antiviral Therapy on Sustained Virologic Response

BACKGROUND

Direct-acting antivirals (DAAs) are highly effective treatments against hepatitis C virus (HCV), with sustained virologic response (SVR) rates of 93-100% against all genotypes. In most patients, viral load (VL) becomes undetectable four weeks into treatment, but rarely a low positive VL may be observed at the end of treatment (EOT). This study was conducted to determine the effect of low positive EOT VLs with DAA therapies on SVR at 12 and 24 weeks.

METHODS

A retrospective chart review was conducted from January 2014 to December 2018 on 1256 HCV patients of all genotypes (1-6) who had received DAA therapy at two large hepatology referral centers. Baseline demographic data, along with VL at week four, EOT, and SVR12/24 time points were collected for patients that had positive EOT VL. Treatment outcome for any patient with positive EOT VL was noted.

RESULTS

Eight out of 1256 patients treated with varying DAA therapies were observed to have low positive EOT VLs ranging from <15 to 235 IU/mL. One patient had a negative EOT VL, but 23 IU/mL at week four after EOT. All eight patients who had low positive EOT VLs and one patient who had a low positive VL at four weeks after EOT achieved SVR at weeks 12 and 24. One of the eight patients had cirrhosis. The majority of patients were genotype 1a.

CONCLUSION

In the DAA treatment era, low levels of detectable HCV RNA at EOT does not predict treatment failure.

High efficacy of resistance-guided retreatment of HCV patients failing NS5A inhibitors in the real world

BACKGROUND & AIMS

Most hepatitis C virus (HCV)-infected patients failing NS5A inhibitors develop resistance-associated substitutions (RASs). Here we report the use of resistance-guided retreatment of patients who failed prior NS5A inhibitor-containing regimens in the GEHEP-004 cohort. This is the largest direct-acting antiviral (DAA)-resistance cohort study conducted in Spain. We aim to provide indications on how to use resistance information in settings where sofosbuvir/velpatasvir/voxilaprevir may not be available.

METHODS

GEHEP-004 is a prospective multicenter cohort enrolling HCV-infected patients treated with interferon (IFN)-free DAA regimens. Prior to retreatment, population-based sequencing of HCV NS3, NS5A and NS5B genes was performed. After receiving a comprehensive resistance interpretation report, the retreatment regimen was chosen and the sustained virological response (SVR) at 12 weeks after treatment completion (SVR12) was recorded.

RESULTS

A total of 342 patients experiencing virological failure after treatment with sofosbuvir/ledipasvir±ribavirin (54%), sofosbuvir/daclatasvir±ribavirin (23%), or paritaprevir-ritonavir/ombitasvir±dasabuvir±ribavirin (20%) were studied. After a resistance report, 186 patients were retreated. An SVR12 was achieved for 88.1% of the patients who failed after sofosbuvir/ledipasvir±ribavirin, 83.3% of the patients who failed after sofosbuvir/daclatasvir±ribavirin, 93.7% of the patients who failed after paritaprevir-ritonavir+ombitasvir±dasabuvir±ribavirin.

CONCLUSIONS

In our study, we show how resistance-guided retreatment in conjunction with an interpreted report allows patients to achieve SVR rates close to 90%. We hypothesize that SVR rates may even be improved if resistance data are discussed between experienced virologists and treating clinicians. We believe that our data may be relevant for countries where the access to new DAA combination regimens is limited.

LAY SUMMARY

Hepatitis C infection can be cured with currently available antiviral agents. Only a small proportion of patients experience treatment failure, however, in absolute numbers, a high number of patients may require retreatment. Highly effective combinations of antivirals are also available for retreatment. However, these antivirals might not be available in resource-limited settings. Herein, we show how, by analyzing the cause of resistance, retreatment efficacy with old drugs can get very close to the efficacy of new drug combinations.

Sofosbuvir-based direct acting antiviral therapies for patients with hepatitis C virus genotype 2 infection

BACKGROUND AND AIM

Data regarding the comparative effectiveness and safety of sofosbuvir (SOF) in combination with ribavirin (RBV), daclatasvir (DCV), or ledipasvir (LDV) for hepatitis C virus genotype 2 (HCV-2) patients were limited. We aimed to evaluate the performance of these regimens in Taiwan.

METHODS

One hundred eighty-seven HCV-2 patients with compensated liver diseases receiving SOF in combination with RBV (n = 82), DCV (n = 66), or LDV (n = 39) for 12 weeks were retrospectively enrolled. The effectiveness was determined by sustained virologic response 12 weeks off therapy (SVR₁₂ ). The patient characteristics potentially related to SVR₁₂ were compared. The safety profiles and laboratory abnormalities were assessed.

RESULTS

The SVR₁₂ rates were 93.9% (95% confidence interval [CI]: 86.5-97.4%), 98.5% (95% CI: 91.9-99.7%), and 100% (95% CI: 91.0-100%) in patients receiving SOF combined with RBV, DCV, and LDV, respectively. All patients tolerated treatment well. The stratified SVR₁₂ rates were comparable regardless of baseline characteristics or week 4 viral decline among these regimens. Six (3.2%) patients had serious adverse events which were not related to treatment. The rates of fatigue, pruritus, and anemia tended to be higher in patients receiving RBV (22.0%, 19.5%, and 8.5%) combination than those receiving DCV (10.6%, 6.1%, and 1.5%) or LDV (10.3%, 5.1%, and 0%) combination.

CONCLUSIONS

Sofosbuvir in combination with RBV, DCV, or LDV for 12 weeks is effective and well-tolerated for HCV-2 patients. Compared with DCV or LDV combination, the risks of fatigue, pruritus, and anemia are higher in patients receiving RBV combination.

Mutational pathway maps and founder effects define the within-host spectrum of hepatitis C virus mutants resistant to drugs

Knowledge of the within-host frequencies of resistance-associated amino acid variants (RAVs) is important to the identification of optimal drug combinations for the treatment of hepatitis C virus (HCV) infection. Multiple RAVs may exist in infected individuals, often below detection limits, at any resistance locus, defining the diversity of accessible resistance pathways. We developed a multiscale mathematical model to estimate the pre-treatment frequencies of the entire spectrum of mutants at chosen loci. Using a codon-level description of amino acids, we performed stochastic simulations of intracellular dynamics with every possible nucleotide variant as the infecting strain and estimated the relative infectivity of each variant and the resulting distribution of variants produced. We employed these quantities in a deterministic multi-strain model of extracellular dynamics and estimated mutant frequencies. Our predictions captured database frequencies of the RAV R155K, resistant to NS3/4A protease inhibitors, presenting a successful test of our formalism. We found that mutational pathway maps, interconnecting all viable mutants, and strong founder effects determined the mutant spectrum. The spectra were vastly different for HCV genotypes 1a and 1b, underlying their differential responses to drugs. Using a fitness landscape determined recently, we estimated that 13 amino acid variants, encoded by 44 codons, exist at the residue 93 of the NS5A protein, illustrating the massive diversity of accessible resistance pathways at specific loci. Accounting for this diversity, which our model enables, would help optimize drug combinations. Our model may be applied to describe the within-host evolution of other flaviviruses and inform vaccine design strategies.

Real-world effectiveness and safety of sofosbuvir and ledipasvir with or without ribavirin for patients with hepatitis C virus genotype 1 infection in Taiwan

Background

The real-world data for the effectiveness and safety of sofosbuvir/ledipasvir (SOF/LDV) with or without ribavirin (RBV) in patients with hepatitis C virus genotype 1 (HCV-1) infection remain limited in Taiwan.

Methods

A total of 273 chronic HCV-1 patients receiving 8, 12, or 24 weeks of SOF/LDV with or without RBV were enrolled. The sustained virologic response rate at week 12 off-therapy (SVR₁₂) by evaluable population (EP) and per-protocol population (PP) were assessed for effectiveness. The treatment discontinuation rate due to adverse events (AEs) and serious AE rate were assessed for safety. Baseline patient characteristics and on-treatment HCV viral kinetics associated with SVR₁₂ were analyzed.

Results

The SVR₁₂ rates by EP and PP analyses were 96.7% (95% confidence interval [CI]: 93.9%-98.3%) and 97.5% (95% CI: 94.8%-98.8%), respectively. The rates of treatment discontinuation due to AE and serious AE were 0.4% and 4.4%, respectively. Seven patients with true virologic failure were relapsers. In 2 patients who were lost-to follow-up, one expired at treatment week 3 due to pneumonia which was considered not related to treatment, and one declined follow-up at off-therapy week 4. The SVR₁₂ rates were comparable in terms of baseline patient characteristics and viral decline at week 4 of treatment.

Conclusions

SOF/LDV with or without RBV for 8–24 weeks is well tolerated and achieves a high SVR₁₂ rate in patients with HCV-1 infection in Taiwan.

In Vitro Antiviral Profile of Ruzasvir, a Potent and Pangenotype Inhibitor of Hepatitis C Virus NS5A

Inhibition of NS5A has emerged as an attractive strategy to intervene in hepatitis C virus (HCV) replication. Ruzasvir (formerly MK-8408) was developed as a novel NS5A inhibitor to improve upon the potency and barrier to resistance of early compounds. Ruzasvir inhibited HCV RNA replication with 50% effective concentrations (EC50s) of 1 to 4 pM in Huh7 or Huh7.5 cells bearing replicons for HCV genotype 1 (GT1) to GT7. The antiviral activity was modestly (10-fold) reduced in the presence of 40% normal human serum. The picomolar potency in replicon cells extended to sequences of clinical isolates available in public databases that were synthesized and tested as replicons. In GT1a, ruzasvir inhibited common NS5A resistance-associated substitutions (RASs), with the exception of M28G. De novo resistance selection studies identified pathways with certain amino acid substitutions at residues 28, 30, 31, and 93 across genotypes. Substitutions at position 93 were more common in GT1 to -4, while changes at position 31 emerged frequently in GT5 and -6. With the exception of GT4, the reintroduction of selected RASs conferred a ≥100-fold potency reduction in the antiviral activity of ruzasvir. Common RASs from other classes of direct-acting antiviral agents (DAAs) did not confer cross-resistance to ruzasvir. The interaction of ruzasvir with an NS3/4A protease inhibitor (grazoprevir) and an NS5B polymerase prodrug (uprifosbuvir) was additive to synergistic, with no evidence of antagonism or cytotoxicity. The antiviral profile of ruzasvir supported its further evaluation in human trials in combination with grazoprevir and uprifosbuvir.

Generic sofosbuvir-based interferon-free direct acting antiviral agents for patients with chronic hepatitis C virus infection: a real-world multicenter observational study

Real-world data regarding the effectiveness and safety of generic sofosbuvir (SOF)-based interferon-free direct acting antiviral agents (DAAs) for patients with chronic hepatitis C virus (HCV) infection remain limited. A total of 517 chronic HCV-infected patients receiving 12 or 24 weeks of SOF-based therapies were retrospectively enrolled in 4 academic centers in Taiwan. The rate of sustained virologic response at week 12 off-therapy (SVR₁₂) and that of treatment completion were assessed. The baseline characteristics and on-treatment HCV viral kinetics to predict SVR₁₂ were analyzed. By evaluable population (EP) analysis, the SVR₁₂ rate was 95.4% (95% confidence interval [CI]: 93.2–96.9%). The SVR₁₂ was achieved in 29 of 34 patients (85.3%, 95% CI: 69.6–93.6%), 130 of 139 patients (93.5%, 95% CI: 88.2–96.6%), 119 of 124 patients (96.0%, 95% CI: 90.9–98.3%) and 215 of 220 patients (97.7%, 95% CI: 94.8–99.0%) who received SOF in combination with ribavirin (RBV), ledipasvir (LDV), daclatasvir (DCV) and velpatasvir (VEL), respectively. Of 517 patients, 514 (99.4%) completed the scheduled treatment. All 15 patients with true virologic failures were relapsers. Two decompensated cirrhotic patients had on-treatment deaths which were not related to DAAs. All 7 patients who were lost to follow-up had undetectable HCV RNA level at the last visit. The SVR₁₂ rates were comparable in terms of baseline patient characteristics and viral decline at week 4 of treatment. In conclusion, generic SOF-based regimens are well tolerated and provide high SVR₁₂ rates in patients with chronic HCV infection.

Modelling how responsiveness to interferon improves interferon-free treatment of hepatitis C virus infection

Direct-acting antiviral agents (DAAs) for hepatitis C treatment tend to fare better in individuals who are also likely to respond well to interferon-alpha (IFN), a surprising correlation given that DAAs target specific viral proteins whereas IFN triggers a generic antiviral immune response. Here, we posit a causal relationship between IFN-responsiveness and DAA treatment outcome. IFN-responsiveness restricts viral replication, which would prevent the growth of viral variants resistant to DAAs and improve treatment outcome. To test this hypothesis, we developed a multiscale mathematical model integrating IFN-responsiveness at the cellular level, viral kinetics and evolution leading to drug resistance at the individual level, and treatment outcome at the population level. Model predictions quantitatively captured data from over 50 clinical trials demonstrating poorer response to DAAs in previous non-responders to IFN than treatment-naïve individuals, presenting strong evidence supporting the hypothesis. Model predictions additionally described several unexplained clinical observations, viz., the percentages of infected individuals who 1) spontaneously clear HCV, 2) get chronically infected but respond to IFN-based therapy, and 3) fail IFN-based therapy but respond to DAA-based therapy, resulting in a comprehensive understanding of HCV infection and treatment. An implication of the causal relationship is that failure of DAA-based treatments may be averted by adding IFN, a strategy of potential use in settings with limited access to DAAs. A second, wider implication is that individuals with greater IFN-responsiveness would require shorter DAA-based treatment durations, presenting a basis and a promising population for response-guided therapy.