HCV kinetic and modeling analyses indicate similar time to cure among sofosbuvir combination regimens with daclatasvir, simeprevir or ledipasvir

Glecaprevir-pibrentasvir for 4 weeks among people with recent HCV infection: The TARGET3D study

Background & Aims

Short duration treatment may aid HCV elimination among key populations. This study evaluated the efficacy of glecaprevir-pibrentasvir for 4 weeks among people with recent HCV infection.

Methods

In this single-arm multicentre international trial, adults with recent HCV (duration of infection <12 months) received glecaprevir-pibrentasvir 300 mg-120 mg daily for 4 weeks. Primary infection was defined as a first positive anti-HCV antibody and/or HCV RNA measurement within 6 months of enrolment and either acute clinical hepatitis within 12 months (symptomatic illness or alanine aminotransferase >10x the upper limit of normal) or antibody seroconversion within 18 months. Reinfection was defined as new positive HCV RNA within 6 months and prior clearance (spontaneous or treatment). The primary endpoint was sustained virological response at 12 weeks post-treatment (SVR12) in the intention-to-treat (ITT) and per-protocol (PP) populations.

Results

Twenty-three participants (96% men, 70% HIV, 57% ever injected drugs) received treatment, of whom 74% had genotype 1a infection and 35% recent reinfection. At baseline, median duration of infection was 17 weeks (IQR 11-29) and HCV RNA was 5.8 log10IU/ml (IQR 5.2-6.9). SVR12 was achieved by 78% (18/23; 95% CI 56-93%) and 82% (18/22; 95% CI 60-95%) of the ITT and PP populations, respectively, and in 100% (12/12; 95% CI 74-100%) of participants with baseline HCV RNA ≤6 log10. There were four cases of virological failure (relapse); three received retreatment with 12 weeks sofosbuvir-velpatasvir or grazoprevir-elbasvir (SVR, n = 2; loss to follow-up, n = 1). No serious adverse events were reported.

Conclusion

While most achieved SVR, the efficacy of a 4-week regimen of glecaprevir-pibrentasvir was lower than observed with longer treatment durations (≥6 weeks) among people with recent HCV.

Trial Registration

Clinicaltrials.gov Identifier: NCT02634008.

Impact and implications

Short duration treatment may aid HCV elimination among key populations. This investigator-initiated single-arm multicentre international pilot trial demonstrated that efficacy of glecaprevir-pibrentasvir for 4 weeks among people with recent HCV infection was sub-optimal (SVR12 78% ITT, 82% PP). Baseline HCV RNA appeared to impact response, with higher efficacy among participants with lower baseline HCV RNA (≤6 log10; SVR12 100% ITT, 12/12). While most achieved SVR, the efficacy of 4 weeks of glecaprevir-pibrentasvir was below that seen with longer treatment durations (≥6 weeks).

Modeling-Based Response-Guided Hepatitis C Treatment During Pregnancy and Postpartum

Treating hepatitis C virus (HCV) in pregnancy would address HCV during prenatal care and potentially reduce the risk of vertical transmission. Response-guided therapy could provide a means to individualize and the reduce duration of HCV treatment during pregnancy. Data from a 27-year-old woman indicated that, pretreatment, HCV was stable and that it dropped in a biphasic manner during sofosbuvir/velpatasvir therapy, reaching target not detected at time of delivery-16 days post-initiation of therapy. Mathematical modeling of measured HCV at days 0, 7, and 14 predicted that cure could have been achieved after 7 weeks of sofosbuvir/velpatasvir, reducing the duration of therapy by 5 weeks.

Advances in Parameter Estimation and Learning from Data for Mathematical Models of Hepatitis C Viral Kinetics

Mathematical models, some of which incorporate both intracellular and extracellular hepatitis C viral kinetics, have been advanced in recent years for studying HCV–host dynamics, antivirals mode of action, and their efficacy. The standard ordinary differential equation (ODE) hepatitis C virus (HCV) kinetic model keeps track of uninfected cells, infected cells, and free virus. In multiscale models, a fourth partial differential equation (PDE) accounts for the intracellular viral RNA (vRNA) kinetics in an infected cell. The PDE multiscale model is substantially more difficult to solve compared to the standard ODE model, with governing differential equations that are stiff. In previous contributions, we developed and implemented stable and efficient numerical methods for the multiscale model for both the solution of the model equations and parameter estimation. In this contribution, we perform sensitivity analysis on model parameters to gain insight into important properties and to ensure our numerical methods can be safely used for HCV viral dynamic simulations. Furthermore, we generate in-silico patients using the multiscale models to perform machine learning from the data, which enables us to remove HCV measurements on certain days and still be able to estimate meaningful observations with a sufficiently small error.

Modeling-Based Response-Guided DAA Therapy for Chronic Hepatitis C to Identify Individuals for Shortening Treatment Duration

Shortening duration of direct-acting antiviral therapy for chronic hepatitis C could provide cost savings, reduce medication exposure, and foster adherence and treatment completion in special populations. The current analysis indicates that measuring hepatitis C virus at baseline and on days 7 and 14 of therapy can identify patients for shortening therapy duration.

Hepatitis C virus: A critical approach to who really needs treatment

Introduction of effective drugs in the treatment of hepatitis C virus (HCV) infection has prompted the World Health Organization to declare a global eradication target by 2030. Propositions have been made to screen the general population and treat all HCV carriers irrespective of the disease status. A year ago the new severe acute respiratory syndrome coronavirus 2 virus appeared causing a worldwide pandemic of coronavirus disease 2019 disease. Huge financial resources were redirected, and the pandemic became the first priority in every country. In this review, we examined the feasibility of the World Health Organization elimination program and the actual natural course of HCV infection. We also identified and analyzed certain comorbidity factors that may aggravate the progress of HCV and some marginalized subpopulations with characteristics favoring HCV dissemination. Alcohol consumption, HIV coinfection and the presence of components of metabolic syndrome including obesity, hyperuricemia and overt diabetes were comorbidities mostly responsible for increased liver-related morbidity and mortality of HCV. We also examined the significance of special subpopulations like people who inject drugs and males having sex with males. Finally, we proposed a different micro-elimination screening and treatment program that can be implemented in all countries irrespective of income. We suggest that screening and treatment of HCV carriers should be limited only in these particular groups.

Machine learning for mathematical models of HCV kinetics during antiviral therapy

Mathematical models for hepatitis C virus (HCV) dynamics have provided a means for evaluating the antiviral effectiveness of therapy and estimating treatment outcomes such as the time to cure. Recently, a mathematical modeling approach was used in the first proof-of-concept clinical trial assessing in real-time the utility of response-guided therapy with direct-acting antivirals (DAAs) in chronic HCV-infected patients. Several retrospective studies have shown that mathematical modeling of viral kinetics predicts time to cure of less than 12 weeks in the majority of individuals treated with sofosbuvir-based as well as other DAA regimens. A database of these studies was built, and machine learning methods were evaluated for their ability to estimate the time to cure for each patient to facilitate real-time modeling studies. Data from these studies exploring mathematical modeling of HCV kinetics under DAAs in 266 chronic HCV-infected patients were gathered. Different learning methods were applied and trained on part of the dataset ('train' set), to predict time to cure on the untrained part ('test' set). Our results show that this machine learning approach provides a means for establishing an accurate time to cure prediction that will support the implementation of individualized treatment.

Advancing therapies for viral infections using mechanistic computational models of the dynamic interplay between the virus and host immune response

The COVID-19 pandemic has highlighted a need for improved frameworks for drug discovery, repurposing, clinical trial design and therapy optimization and personalization. Mechanistic computational models can play an important role in developing these frameworks. We discuss how mechanistic models, which consider viral entry, replication in target cells, viral spread in the body, immune response, and the complex factors involved in tissue and organ damage and recovery, can clarify the mechanisms of humoral and cellular immune responses to the virus, viral distribution and replication in tissues, the origins of pathogenesis and patient-to-patient heterogeneity in responses. These models are already improving our understanding of the mechanisms of action of antivirals and immune modulators. We discuss how closer collaboration between the experimentalists, clinicians and modelers could result in more predictive models which may guide therapies for viral infections, improving survival and leading to faster and more complete recovery.

Strategic treatment optimization for HCV (STOPHCV1): a randomised controlled trial of ultrashort duration therapy for chronic hepatitis C

Background: The World Health Organization (WHO) has identified the need for a better understanding of which patients with hepatitis C virus (HCV) can be cured with ultrashort course HCV therapy. Methods: A total of 202 individuals with chronic HCV were randomised to fixed-duration shortened therapy (8 weeks) vs variable-duration ultrashort strategies (VUS1/2). Participants not cured following first-line treatment were retreated with 12 weeks' sofosbuvir/ledipasvir/ribavirin. The primary outcome was sustained virological response 12 weeks (SVR12) after first-line treatment and retreatment. Participants were factorially randomised to receive ribavirin with first-line treatment. Results: All evaluable participants achieved SVR12 overall (197/197, 100% [95% CI 98-100]) demonstrating non-inferiority between fixed-duration and variable-duration strategies (difference 0% [95% CI -3.8%, +3.7%], 4% pre-specified non-inferiority margin). First-line SVR12 was 91% [86%-97%] (92/101) for fixed-duration vs 48% [39%-57%] (47/98) for variable-duration, but was significantly higher for VUS2 (72% [56%-87%] (23/32)) than VUS1 (36% [25%-48%] (24/66)). Overall, first-line SVR12 was 72% [65%-78%] (70/101) without ribavirin and 68% [61%-76%] (69/98) with ribavirin (p=0.48). At treatment failure, the emergence of viral resistance was lower with ribavirin (12% [2%-30%] (3/26)) than without (38% [21%-58%] (11/29), p=0.01). Conclusions: Unsuccessful first-line short-course therapy did not compromise retreatment with sofosbuvir/ledipasvir/ribavirin (100% SVR12). SVR12 rates were significantly increased when ultrashort treatment varied between 4-7 weeks rather than 4-6 weeks. Ribavirin significantly reduced resistance emergence in those failing first-line therapy. ISRCTN Registration: 37915093 (11/04/2016).

Strategic treatment optimization for HCV (STOPHCV1): a randomised controlled trial of ultrashort duration therapy for chronic hepatitis C

Background: The world health organization (WHO) has identified the need for a better understanding of which patients with hepatitis C virus (HCV) can be cured with ultrashort course HCV therapy. Methods: A total of 202 individuals with chronic HCV were randomised to fixed-duration shortened therapy (8 weeks) vs variable-duration ultrashort strategies (VUS1/2). Participants not cured following first-line treatment were retreated with 12 weeks' sofosbuvir/ledipasvir/ribavirin. The primary outcome was sustained virological response 12 weeks (SVR12) after first-line treatment and retreatment. Participants were factorially randomised to receive ribavirin with first-line treatment. Results: All evaluable participants achieved SVR12 overall (197/197, 100% [95% CI 98-100]) demonstrating non-inferiority between fixed-duration and variable-duration strategies (difference 0% [95% CI -3.8%, +3.7%], 4% pre-specified non-inferiority margin). First-line SVR12 was 91% [86%-97%] (92/101) for fixed-duration vs 48% [39%-57%] (47/98) for variable-duration, but was significantly higher for VUS2 (72% [56%-87%] (23/32)) than VUS1 (36% [25%-48%] (24/66)). Overall, first-line SVR12 was 72% [65%-78%] (70/101) without ribavirin and 68% [61%-76%] (69/98) with ribavirin (p=0.48). At treatment failure, the emergence of viral resistance was lower with ribavirin (12% [2%-30%] (3/26)) than without (38% [21%-58%] (11/29), p=0.01). Conclusions: Unsuccessful first-line short-course therapy did not compromise retreatment with sofosbuvir/ledipasvir/ribavirin (100% SVR12). SVR12 rates were significantly increased when ultrashort treatment varied between 4-7 weeks rather than 4-6 weeks. Ribavirin significantly reduced resistance emergence in those failing first-line therapy. ISRCTN Registration: 37915093 (11/04/2016).

Signatures of immune dysfunction in HIV and HCV infection share features with chronic inflammation in aging and persist after viral reduction or elimination

Chronic inflammation is thought to be a major cause of morbidity and mortality in aging, but whether similar mechanisms underlie dysfunction in infection-associated chronic inflammation is unclear. Here, we profiled the immune proteome, and cellular composition and signaling states in a cohort of aging individuals versus a set of HIV patients on long-term antiretroviral therapy therapy or hepatitis C virus (HCV) patients before and after sofosbuvir treatment. We found shared alterations in aging-associated and infection-associated chronic inflammation including T cell memory inflation, up-regulation of intracellular signaling pathways of inflammation, and diminished sensitivity to cytokines in lymphocytes and myeloid cells. In the HIV cohort, these dysregulations were evident despite viral suppression for over 10 y. Viral clearance in the HCV cohort partially restored cellular sensitivity to interferon-α, but many immune system alterations persisted for at least 1 y posttreatment. Our findings indicate that in the HIV and HCV cohorts, a broad remodeling and degradation of the immune system can persist for a year or more, even after the removal or drastic reduction of the pathogen load and that this shares some features of chronic inflammation in aging.

Fuzzy logic and Lyapunov-based non-linear controllers for HCV infection

Hepatitis C is the liver disease caused by the Hepatitis C virus (HCV) which can lead to serious health problems such as liver cancer. In this research work, the non‐linear model of HCV having three state variables (uninfected hepatocytes, infected hepatocytes and virions) and two control inputs has been taken into account, and four non‐linear controllers namely non‐linear PID controller, Lyapunov Redesign controller, Synergetic controller and Fuzzy Logic‐Based controller have been proposed to control HCV infection inside the human body. The controllers have been designed for the anti‐viral therapy in order to control the amount of uninfected hepatocytes to the desired safe limit and to track the amount of infected hepatocytes and virions to their reference value which is zero. One control input is the Pegylated interferon (peg‐IFN‐α) which acts in reducing the infected hepatocytes and the other input is ribavirin which blocks the production of virions. By doing so, the uninfected hepatocytes increase and achieve the required safe limit. Lyapunov stability analysis has been used to prove the stability of the whole system. The comparative analysis of the proposed nonlinear controllers using MATLAB/Simulink have been done with each other and with linear PID. These results depict that the infected hepatocytes and virions are reduced to the desired level, enhancing the rate of sustained virologic response (SVR) and reducing the treatment period as compared with previous strategies introduced in the literature.

Model-Informed Drug Development for Anti-Infectives: State of the Art and Future

Model-informed drug development (MIDD) has a long and rich history in infectious diseases. This review describes foundational principles of translational anti-infective pharmacology, including choice of appropriate measures of exposure and pharmacodynamic (PD) measures, patient subpopulations, and drug-drug interactions. Examples are presented for state-of-the-art, empiric, mechanistic, interdisciplinary, and real-world evidence MIDD applications in the development of antibacterials (review of minimum inhibitory concentration-based models, mechanism-based pharmacokinetic/PD (PK/PD) models, PK/PD models of resistance, and immune response), antifungals, antivirals, drugs for the treatment of global health infectious diseases, and medical countermeasures. The degree of adoption of MIDD practices across the infectious diseases field is also summarized. The future application of MIDD in infectious diseases will progress along two planes; "depth" and "breadth" of MIDD methods. "MIDD depth" refers to deeper incorporation of the specific pathogen biology and intrinsic and acquired-resistance mechanisms; host factors, such as immunologic response and infection site, to enable deeper interrogation of pharmacological impact on pathogen clearance; clinical outcome and emergence of resistance from a pathogen; and patient and population perspective. In particular, improved early assessment of the emergence of resistance potential will become a greater focus in MIDD, as this is poorly mitigated by current development approaches. "MIDD breadth" refers to greater adoption of model-centered approaches to anti-infective development. Specifically, this means how various MIDD approaches and translational tools can be integrated or connected in a systematic way that supports decision making by key stakeholders (sponsors, regulators, and payers) across the entire development pathway.

Modeling-Based Response-Guided Glecaprevir-Pibrentasvir Therapy for Chronic Hepatitis C to Identify Patients for Ultrashort Treatment Duration

We recently showed in a proof-of-concept study that real-time modeling-based response-guided therapy can shorten hepatitis C virus treatment duration with sofosbuvir-velpatasvir, elbasvir-grazoprevir, and sofosbuvir-ledipasvir without compromising efficacy, confirming our retrospective modeling reports in >200 patients. However, retrospective modeling of pibrentasvir-glecaprevir (P/G) treatment has yet to be evaluated. In the current study, modeling hepatitis C virus kinetics in 44 cirrhotic and noncirrhotic patients predicts that P/G treatment might have been reduced to 4, 6, and 7 weeks in 16%, 34%, and 14% of patients, respectively. These results support the further evaluation of a modeling-based response-guided therapy approach using P/G.

Intrahepatic Viral Kinetics During Direct-Acting Antivirals for Hepatitis C in Human Immunodeficiency Virus Coinfection: The AIDS Clinical Trials Group A5335S Substudy

BACKGROUND

Direct-acting antivirals (DAAs) targeting hepatitis C virus (HCV) have revolutionized outcomes in human immunodeficiency virus (HIV) coinfection.

METHODS

We examined early events in liver and plasma through A5335S, a substudy of trial A5329 (paritaprevir/ritonavir, ombitasvir, dasabuvir, with ribavirin) that enrolled chronic genotype 1a HCV-infected persons coinfected with suppressed HIV: 5 of 6 treatment-naive enrollees completed A5335S.

RESULTS

Mean baseline plasma HCV ribonucleic acid (RNA) = 6.7 log10 IU/mL and changed by -4.1 log10 IU/mL by Day 7. In liver, laser capture microdissection was used to quantify HCV. At liver biopsy 1, mean %HCV-infected cells = 25.2% (95% confidence interval [CI], 7.4%-42.9%), correlating with plasma HCV RNA (Spearman rank correlation r = 0.9); at biopsy 2 (Day 7 in 4 of 5 participants), mean %HCV-infected cells = 1.0% (95% CI, 0.2%-1.7%) (P < .05 for change), and DAAs were detectable in liver. Plasma C-X-C motif chemokine 10 (CXCL10) concentrations changed by mean = -160 pg/mL per day at 24 hours, but no further after Day 4.

CONCLUSIONS

We conclude that HCV infection is rapidly cleared from liver with DAA leaving <2% HCV-infected hepatocytes at Day 7. We extrapolate that HCV eradication could occur in these participants by 63 days, although immune activation might persist. Single-cell longitudinal estimates of HCV clearance from liver have never been reported previously and could be applied to estimating the minimum treatment duration required for HCV infection.

Response guided therapy for reducing duration of direct acting antivirals in chronic hepatitis C infected patients: a Pilot study

The advent of direct-acting antivirals (DAAs) has transformed the landscape of hepatitis C virus (HCV) management. We aimed to prospectively (real-time) evaluate the feasibility of using a response-guided therapy approach, based on mathematical modeling of early viral kinetics, to reduce the duration of DAAs therapy. Patients were treated with DAAs according to the physicians' preference. HCV was measured at baseline and at day 2 and weeks 1, 2 and 4 after treatment initiation. The primary endpoint was the proportion of patients with sustained-virological response (SVR) at 12 and/or 24 weeks post-treatment. Twenty-nine patients (mean age 54 ± 16, 44% females, 73% with HCV genotype 1), were enrolled and all completed therapy. Treatment duration was shortened in 11 of the 29 patients (38%). SVR was achieved in 28 of the 29 patients (97%). Relapse occurred post treatment in a single case of a non-cirrhotic male with genotype 3, who was treated with sofosbuvir/velpatasvir for 6 weeks. Virus sequencing did not identify baseline or treatment emergent resistance associated substitutions. Real-time mathematical modeling of early HCV kinetics can be utilized for shortening DAAs duration in approximately 40% of patients without compromising treatment efficacy.Clinical trial registration: ClinicalTrials.gov Identifier: NCT03603327.

Efficient Methods for Parameter Estimation of Ordinary and Partial Differential Equation Models of Viral Hepatitis Kinetics

Parameter estimation in mathematical models that are based on differential equations is known to be of fundamental importance. For sophisticated models such as age-structured models that simulate biological agents, parameter estimation that addresses all cases of data points available presents a formidable challenge and efficiency considerations need to be employed in order for the method to become practical. In the case of age-structured models of viral hepatitis dynamics under antiviral treatment that deal with partial differential equations, a fully numerical parameter estimation method was developed that does not require an analytical approximation of the solution to the multiscale model equations, avoiding the necessity to derive the long-term approximation for each model. However, the method is considerably slow because of precision problems in estimating derivatives with respect to the parameters near their boundary values, making it almost impractical for general use. In order to overcome this limitation, two steps have been taken that significantly reduce the running time by orders of magnitude and thereby lead to a practical method. First, constrained optimization is used, letting the user add constraints relating to the boundary values of each parameter before the method is executed. Second, optimization is performed by derivative-free methods, eliminating the need to evaluate expensive numerical derivative approximations. The newly efficient methods that were developed as a result of the above approach are described for hepatitis C virus kinetic models during antiviral therapy. Illustrations are provided using a user-friendly simulator that incorporates the efficient methods for both the ordinary and partial differential equation models.

Short-Duration Pan-Genotypic Therapy With Glecaprevir/Pibrentasvir for 6 Weeks Among People With Recent Hepatitis C Viral Infection

BACKGROUND AND AIMS

Among treatment-naive individuals with chronic hepatitis C viral (HCV) infection and without cirrhosis, glecaprevir/pibrentasvir for 8 weeks is recommended. The aim of this analysis was to evaluate the efficacy of glecaprevir/pibrentasvir for 6 weeks in people with acute and recent HCV infection.

APPROACH AND RESULTS

In this open-label, single-arm, multicenter, international pilot study, adults with recent HCV (duration of infection < 12 months) received glecaprevir/pibrentasvir 300/120 mg daily for 6 weeks. Primary infection was defined by first positive anti-HCV antibody and/or HCV RNA within 6 months of enrollment and either acute clinical hepatitis within the past 12 months (symptomatic seroconversion illness or alanine aminotransferase > 10 × upper limit of normal) or anti-HCV antibody seroconversion within 18 months. Reinfection was defined as new positive HCV RNA within 6 months of enrollment and evidence of prior spontaneous or treatment-induced clearance. The primary endpoint was sustained virologic response at 12 weeks posttreatment (SVR12). Thirty men (median age 43 years, 90% men who have sex with men) received treatment, of whom 77% (n = 23) were human immunodeficiency virus-positive, 47% (n = 14) had ever injected drugs, and 13% (n = 4) had HCV reinfection. The majority had HCV genotype 1 (83%, n = 25), followed by genotype 4 (10%, n = 3) and genotype 3 (7%, n = 2). At baseline, median estimated duration of infection was 29 weeks (range 13, 52) and median HCV RNA was 6.2 log₁₀ IU/mL (range 0.9, 7.7). SVR12 in the intention-to-treat and per-protocol populations was achieved in 90% (27/30) and 96% (27/28), respectively. There was one case of relapse, and there were two cases of nonvirological failure (death, n = 1; loss to follow-up, n = 1). No treatment-related serious adverse events were seen.

CONCLUSIONS

Glecaprevir/pibrentasvir for 6 weeks was highly effective among people with acute and recent HCV infection, supporting further evaluation of shortened-duration pan-genotypic therapy in this setting.

Modeling based response guided therapy in subjects with recent hepatitis C infection

BACKGROUND & AIMS

Mathematical modeling of viral kinetics has been shown to identify patients with chronic hepatitis C virus (HCV) infection who could be cured with a shorter duration of direct-acting antiviral (DAA) treatment. However, modeling therapy duration has yet to be evaluated in recently infected individuals. The aim of this study was to retrospectively examine whether modeling can predict outcomes of six-week sofosbuvir (SOF) and weight-based ribavirin (R) therapy in individuals with recent HCV infection.

METHODS

Modeling was used to estimate viral host parameters and to predict time to cure for 12 adults with recent HCV infection (<12 months of infection) who received six weeks of treatment with SOF + R.

RESULTS

Modeling results yielded a 100% negative predictive value for SOF + R treatment response in nine participants and suggested that a median of 13 [interquartile range: 8-16] weeks of therapy would be required for these patients to achieve cure. Modeling predicted cure after 5 weeks of therapy in the only modeled participant who achieved a sustained virological response. However, cure was also predicted for two participants who relapsed following treatment.

CONCLUSIONS

The modeling results confirm that longer than 6 weeks of SOF + R is needed to reach cure in individuals with recent HCV infection. Prospective real-time modeling under current potent DAA regimens is needed to validate the potential of response-guided therapy in the management of recent HCV infection.

Modeling Favipiravir Antiviral Efficacy Against Emerging Viruses: From Animal Studies to Clinical Trials

In 2014, our research network was involved in the evaluation of favipiravir, an anti-influenza polymerase inhibitor, against Ebola virus. In this review, we discuss how mathematical modeling was used, first to propose a relevant dosing regimen in humans, and then to optimize its antiviral efficacy in a nonhuman primate (NHP) model. The data collected in NHPs were finally used to develop a model of Ebola pathogenesis integrating the interactions among the virus, the innate and adaptive immune response, and the action of favipiravir. We conclude the review of this work by discussing how these results are of relevance for future human studies in the context of Ebola virus, but also for other emerging viral diseases for which no therapeutics are available.

The Beginning of Ending Hepatitis C Virus: A Summary of the 26th International Symposium on Hepatitis C Virus and Related Viruses

Hepatitis C virus (HCV) infects ~71 million people worldwide, and 399,000 people die annually due to HCV-related liver cirrhosis and hepatocellular carcinoma. The use of direct-acting antivirals results in a sustained virologic response in >95% of patients with chronic HCV infection. However, several issues remain to be solved to eradicate HCV. At the 26th International Symposium on Hepatitis C Virus and Related Viruses (HCV2019) held in Seoul, South Korea, October 5–8, 2019, virologists, immunologists, and clinical scientists discussed these remaining issues and how we can achieve the elimination of HCV.

Assessment of lncRNA GAS5, lncRNA HEIH, lncRNA BISPR and its mRNA BST2 as serum innovative non-invasive biomarkers: Recent insights into Egyptian patients with hepatitis C virus type 4

BACKGROUND

Hepatitis C virus (HCV) infection and its consequent complications are undeniably a public health burden worldwide, particularly in Egypt. Emerging evidence suggests that many lncRNAs have relevant roles in viral infections and antiviral responses.

AIM

To investigate the expression profiles of circulating lncRNAGAS5, lncRNAHEIH, lncRNABISPR and mRNABST2 in naïve, treated and relapsed HCV Egyptian patients, to elucidate relation to HCV infection and their efficacy as innovative biomarkers for the diagnosis and prognosis of HCV GT4.

METHODS

One hundred and thirty HCV-infected Egyptian patients and 20 healthy controls were included in this study. Serum lncRNAs and mRNABST2 were measured using quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

Our results indicated that serum lncRNAGAS5 and LncRNABISPR were upregulated, whereas mRNA BST2 and LncRNA HEIH were downregulated in naïve patients. In contrast, HCV patients treated with sofosbuvir and simeprevir; with sofosbuvir and daclatasvir; or with sofosbuvir, daclatasvir and ribavirin exhibited lower levels of lncRNAGAS5 and lncRNABISPR with higher mRNABST2 compared to naïve patients. Notably, patients relapsed from sofosbuvir and simeprevir showed higher levels of these lncRNAs with lower mRNABST2 compared to treated patients. LncRNAGAS5 and lncRNABISPR were positively correlated with viral load and ALT at P < 0.001, whereas mRNABST2 was negatively correlated with viral load at P < 0.001 and ALT at P < 0.05. Interestingly, a significant positive correlation between lncRNA HEIH and AFP was observed at P < 0.001.

CONCLUSION

Differential expression of these RNAs suggests their involvement in HCV pathogenesis or antiviral response and highlights their promising roles in diagnosis and prognosis of HCV.

Ribavirin facilitates early viral kinetics in chronic hepatitis C patients receiving daclatasvir/asunaprevir

BACKGROUND AND AIM

Ribavirin (RBV) remains crucial in difficult-to-cure chronic hepatitis C patients receiving directly acting antivirals (DAAs). The current study aimed to address whether RBV enhanced early viral kinetics in patients with DAAs.

METHODS

Hepatitis C virus (HCV) genotype-1b patients were allocated to daclatasvir/asunaprevir +weight-based RBV (1000-1200 mg/day) for 12-24 weeks. HCV RNA levels were compared at day 1, week 1, week 2, and week 4 of treatment.

RESULTS

The sustained virological response rate was 100% (67/67) and 96.7% (59/61) in the RBV and non-RBV group, respectively. The HCV RNA levels at treatment week 2 (W2) were significantly lower in the RBV group than in the non-RBV group (0.42 ± 0.81 log IU/mL vs 0.79 ± 1.03 log IU/mL, P = 0.04). Among the intermediate responders who remained to have detectable RNA after W1 of treatment, patients with RBV had a significantly higher rate of undetectable HCV RNA (71.4% vs 36.0%, P = 0.003) and lower HCV RNA level at W2 (0.55 ± 0.89 log IU/mL vs 1.32 ± 1.04 log IU/mL, P = 0.001). A more significant magnitude of HCV RNA reduction was also noted from baseline to day 1 (3.15 ± 0.38 log IU/mL vs 2.80 ± 0.70 log IU/mL, P = 0.009) and W1 to W2 (1.40 ± 0.65 log IU/mL vs 0.88 ± 0.78 log IU/mL, P = 0.007) in the RBV group compared to the non-RBV group among the intermediate responders. Logistic regression analysis revealed that adding RBV independently predicted undetectable HCV RNA at W2 (odds ratio/confidence interval: 4.74/1.54-14.57, P = 0.007) in the intermediate responders.

CONCLUSIONS

Adding RBV to DAAs improved early viral kinetic, in particular, for intermediate responders.

Viral hepatitis C treatment shortening - what is the limit?

Successful antiviral treatment for hepatitis C virus (HCV) infection is crucial to prevent progression of the disease and its most serious complications. Therapy options have changed over the years with improvement of treatment efficacy, safety and simplification. They evolved from interferon and ribavirin combination administered for 24-72 weeks through interferon (IFN)-based triple therapies with 24-48 weeks duration to the all-oral, well-tolerated direct-acting antiviral regimens lasting for 8-16 weeks and with almost 100% cure rates. The benefits of shorter treatment duration are cost reduction, access to therapy for more patients, and lower risk of adverse events and nonadherence. This review summarizes data on treatment options, focusing on the recommended durations of different regimens depending on HCV genotype, severity of liver disease and history of previous therapy. According to currently available data, shortening treatment below 8 weeks does not provide additional benefits, although the further simplification of therapy is still a subject of study.

A Parameter Estimation Method for Multiscale Models of Hepatitis C Virus Dynamics

Mathematical models that are based on differential equations require detailed knowledge about the parameters that are included in the equations. Some of the parameters can be measured experimentally while others need to be estimated. When the models become more sophisticated, such as in the case of multiscale models of hepatitis C virus dynamics that deal with partial differential equations (PDEs), several strategies can be tried. It is possible to use parameter estimation on an analytical approximation of the solution to the multiscale model equations, namely the long-term approximation, but this limits the scope of the parameter estimation method used and a long-term approximation needs to be derived for each model. It is possible to transform the PDE multiscale model to a system of ODEs, but this has an effect on the model parameters themselves and the transformation can become problematic for some models. Finally, it is possible to use numerical solutions for the multiscale model and then use canned methods for the parameter estimation, but the latter is making the user dependent on a black box without having full control over the method. The strategy developed here is to start by working directly on the multiscale model equations for preparing them toward the parameter estimation method that is fully coded and controlled by the user. It can also be adapted to multiscale models of other viruses. The new method is described, and illustrations are provided using a user-friendly simulator that incorporates the method.

A pharmacokinetic/viral kinetic model to evaluate treatment of chronic HCV infection with a non-nucleoside polymerase inhibitor

BACKGROUND

Viral kinetic models have proven useful in characterizing treatment effectiveness during HCV therapy with interferon (IFN) as well as with direct-acting antivirals (DAAs).

METHODS

Here we use a pharmacokinetic/viral kinetic (PK/VK) model to describe HCV RNA kinetics during treatment with setrobuvir, a non-nucleosidic inhibitor of the HCV NS5B polymerase enzyme. Using PK data from three studies in healthy volunteers and PK and VK data from a Phase I study, where setrobuvir was administered for 3 days, we fitted a two-compartment PK model with first-order absorption and lag-time, an Emax pharmacodynamics model and a standard biphasic VK model.

RESULTS

Setrobuvir's EC₅₀ and Hill coefficient and the viral clearance rate were significantly different (P=0.014, P<0.001 and P=0.004, respectively) between patients infected with HCV subtypes 1b and 1a, leading to an increased viral load decline in patients infected with genotype 1b virus.

CONCLUSIONS

Understanding the combined effects of PK/VK on the performance of a non-nucleoside polymerase inhibitor such as setrobuvir could provide valuable insights into their use in combination with other DAAs as well as to optimize future therapy. Further, our work suggests that patients infected with subtype 1a would need higher doses than those infected with subtype 1b to achieve the same effectiveness. Whether this is true for other non-nucleoside polymerase inhibitors needs to be examined.

Plasma Hepatitis E Virus Kinetics in Solid Organ Transplant Patients Receiving Ribavirin

Hepatitis E virus (HEV) infection causes chronic hepatitis in solid organ transplant (SOT) recipients. Antiviral therapy consists of three months of ribavirin, although response rates are not optimal. We characterized plasma HEV kinetic patterns in 41 SOT patients during ribavirin therapy. After a median pharmacological delay of three (range: 0-21) days, plasma HEV declined from a median baseline level of 6.12 (3.53-7.45) log copies/mL in four viral kinetic patterns: (i) monophasic (n = 18), (ii) biphasic (n = 13), (iii) triphasic (n = 8), and (iv) flat-partial response (n = 2). The mean plasma HEV half-life was estimated to be 2.0 ± 0.96 days. Twenty-five patients (61%) had a sustained virological response (SVR) 24 weeks after completion of therapy. Viral kinetic patterns (i)-(iii) were not associated with baseline characteristics or outcome of therapy. A flat-partial response was associated with treatment failure. All patients with a log concentration decrease of plasma HEV at day seven of >15% from baseline achieved SVR. In conclusion, viral kinetic modeling of plasma HEV under ribavirin therapy showed, for the first time, four distinct kinetic profiles, a median pharmacologic delay of three days, and an estimated HEV half-life of two days. Viral kinetic patterns were not associated with response to therapy, with the exception of a flat-partial response.

Interferon at the cellular, individual, and population level in hepatitis C virus infection: Its role in the interferon-free treatment era

The advent of powerful direct-acting antiviral agents (DAAs) has revolutionized the treatment of hepatitis C. DAAs cure nearly all patients with short duration, oral treatments. Significant efforts are now underway to optimize DAA-based treatments. We discuss the potential role of interferon in this optimization. Clinical studies present compelling evidence that DAAs perform better in treatment-naive individuals than in individuals who previously failed treatment with interferon, a surprising correlation because interferon and DAAs are thought to act independently. Recent mathematical models explore a mechanistic hypothesis underlying this correlation. The hypothesis invokes the action of interferon at the cellular, individual, and population levels. Strong interferon responses prevent the productive infection of cells, reduce viral replication, and impede the development of resistance to DAAs in infected individuals and improve cure rates elicited by DAAs in treated populations. The models develop descriptions of these processes, integrate them into a comprehensive framework, and capture clinical data quantitatively, providing a successful test of the hypothesis. Individuals with strong endogenous interferon responses thus present a promising subpopulation for reducing DAA treatment durations. This review discusses the conceptual advances made by the models, highlights the new insights they unravel, and examines their applicability to optimize DAA-based treatments.

Early HCV viral kinetics under DAAs may optimize duration of therapy in patients with compensated cirrhosis

BACKGROUND & AIMS

Detailed hepatitis C virus (HCV) kinetics modelling is scarce in patients with advanced liver disease receiving direct-acting antivirals (DAAs). Due to budget restrictions, patients and health systems would benefit from the shortest possible treatment course. We investigated whether modelling very early HCV kinetics in cirrhotic patients under DAAs therapy could be used to individualize care and reduce treatment duration to achieve cure.

METHODS

We included 74 patients with HCV-related cirrhosis who received interferon-free treatments for 12-24 weeks. HCV genotype, liver disease stage and treatment regimen were recorded. Viral load was determined prospectively at very frequent intervals until target not detected (TND, <15 IU/mL). A viral kinetic model was used to predict time to cure based on HCV clearance in extracellular body fluid (CL-EF).

RESULTS

Sixty-eight patients (92%) achieved cure. Thirteen (18%) had MELD ≥15, 35 (47%) were Child-Pugh (CTP) ≥7. Median time to reach TND was 2 weeks (IQR: 1-4 weeks). Modelling indicated an average DAAs efficacy in blocking viral production of ε = 99.1%. HCV half-life (t1/2 ) was significantly shorter in patients with CTP <7, LSM <21 kPa or MELD <15 (1.5 vs 2.5 hours; P = 0.0057). The overall median CL-EF was 5.6 weeks (4.1-7.8). A CTP >7 and a LSM ≥21 kPa were significantly (P = 0.016) associated with longer CL-EF.

CONCLUSIONS

The study provides insights into HCV dynamics during DAAs therapy in patients with compensated and decompensated cirrhosis. Viral kinetics modelling suggests that treatment duration may be optimized in patients with compensated cirrhosis.

Simultaneous quantification of simeprevir sodium: A hepatitis C protease inhibitor in binary and ternary mixtures with sofosbuvir and/or ledipasvir utilizing direct and H-point standard addition strategies

Simeprevir sodium (SMV); a novel hepatitis C inhibitor, quells hepatitis C viral replication by binding to and repressing the protease, hepatitis C infection (HCV) NS3/4A. In this way, it is known as a prompt acting antiviral agent. Calibration curves of SMV were built in various solvents; ethanol, methanol, acetonitrile, chloroform and dichloromethane. It is obeyed up to 60.0 μg/mL; in all solvents at two maximum wavelengths (280 and 327 nm). Several investigations show that, SMV might be present in a mixture of Sofosbuvir (SOF) and/or Ledipasvir (LDP). So far as that is concerned, H-point standard addition strategy (HPSAS) is made to identify it in binary or ternary mixtures. Recovery studies are in the prevalent range (93.0-107.0%) with relative standard deviation <1.5%. A correlation between the developed techniques is carried out and it demonstrates that these strategies are effectively applied for the simultaneous analysis of SMV, SOF and LDP in several synthetic samples and pharmaceutics. Statistical treatment of the acquired data is carried out against a newly published HPLC technique using F- and t-treatments.

A randomized, proof-of-concept clinical trial on repurposing chlorcyclizine for the treatment of chronic hepatitis C

BACKGROUND & AIMS

Chlorcyclizine HCl (CCZ) is a piperazine-class antihistamine with anti-hepatitis C virus (HCV) activity in vitro and in vivo. In a first-in-humans study for HCV, we evaluated the antiviral effects and safety of CCZ±ribavirin (RBV), characterized pharmacokinetic (PK) and viral kinetic (VK) patterns, and provide insights into CCZs mode of action against HCV.

METHODS

Chronic HCV patients were randomized to CCZ (75 mg twice daily) or CCZ+weight-based RBV (1000/1200 mg daily) for 28 days. Therapy started with a loading dose of CCZ 150 mg ± RBV. Serial assessments of safety, liver tests, PK and VK markers were obtained.

RESULTS

24 HCV patients were treated; 54% male, median age 56 years, median HCV RNA 6.30 log IU/ml, without baseline differences between groups. At the end of therapy, subjects treated with CCZ monotherapy did not show any significant or sustained reduction in viremia (p = 0.69), whereas 7/12 (58%) subjects treated with CCZ+RBV had a >3-fold decline in HCV RNA. Subjects who responded demonstrated monophasic (n = 2), biphasic (n = 2) and triphasic (n = 3) VK responses. Contrary to historical RBV monotherapy response, CCZ+RBV demonstrated a continued viral decline suggesting a possible synergistic effect of CCZ+RBV. Mathematical modeling predicts a median effectiveness of CCZ+RBV in blocking viral production (ε) of 59% (Interquartile range, IQR: 50%) and blocking infection (η) of 78% (IQR: 23%). Adverse events (AEs) were mild-moderate without treatment discontinuations for AEs.

CONCLUSIONS

In this human pilot study, CCZ demonstrated some anti-HCV effects, mostly in combination with RBV. More potent CCZ derivatives with optimal PK features may be more suitable for future therapeutic development. ClinicalTrials.gov number: NCT02118012.

Shortened therapy of eight weeks with paritaprevir/ritonavir/ombitasvir and dasabuvir is highly effective in people with recent HCV genotype 1 infection

Paritaprevir/ritonavir/ombitasvir and dasabuvir with or without ribavirin for 12 weeks are approved for treatment of chronic HCV genotype 1 infection. This study assessed the efficacy of shortened duration paritaprevir/ritonavir/ombitasvir and dasabuvir with or without ribavirin for 8 weeks among people with recent HCV infection. In this open-label single-arm trial conducted in Australia, England and New Zealand, adults with recent HCV (duration of infection <12 months) received paritaprevir/ritonavir/ombitasvir and dasabuvir (with weight-based ribavirin for genotypes 1a and 1, no subtype) for 8 weeks. The primary endpoint was sustained virological response at 12 weeks post-treatment (SVR12) in the intention-to-treat (ITT) population. Thirty people (median age 38 years, male 93%) commenced treatment (with ribavirin, 97%), of whom 77% (n = 23) were HIV-positive, 93% (n = 28) had genotype 1a infection and 53% (n = 16) had ever injected drugs. Median maximum ALT in the preceding 12 months was 433 IU/L (IQR 321, 1012). Acute clinical hepatitis with ALT > 10 x ULN was documented in 83% (n = 25); one participant (3%) had jaundice. At baseline, median estimated duration of infection was 30 weeks (range 11, 51), and median HCV RNA was 5.7 log₁₀ IU/mL (range 2.7, 7.3). SVR12 was achieved in 97% (29/30; early discontinuation at week 2, n = 1; per protocol 100%, 29/29). No relapse or reinfection was observed. In conclusion, paritaprevir/ritonavir/ombitasvir and dasabuvir (with ribavirin) for eight weeks were highly effective among HIV-positive and HIV-negative individuals with recent HCV infection. These data support the use of this shortened duration direct-acting antiviral regimen in this population.

Gold standard assays for the monitoring of patients with chronic hepatitis C

Chronic HCV infection continues to be an important concern of public health, with still a high mortality from HCV-related disease. The landscape of chronic HCV infection has been dramatically changed by the introduction of the new antiviral agents, able to cure the infection in the large majority of patients. The laboratory management of HCV infection relies on serological and molecular tests, which have undergone significant technological advancements, able to ameliorate the performance both in diagnosis of infection and in the treatment monitoring. This article describes the main laboratory tools in the chronic HCV infection, with particular emphasis on the recent changes coming along with the new therapeutic approaches.

Mathematical Analysis of Viral Replication Dynamics and Antiviral Treatment Strategies: From Basic Models to Age-Based Multi-Scale Modeling

Viral infectious diseases are a global health concern, as is evident by recent outbreaks of the middle east respiratory syndrome, Ebola virus disease, and re-emerging zika, dengue, and chikungunya fevers. Viral epidemics are a socio-economic burden that causes short- and long-term costs for disease diagnosis and treatment as well as a loss in productivity by absenteeism. These outbreaks and their socio-economic costs underline the necessity for a precise analysis of virus-host interactions, which would help to understand disease mechanisms and to develop therapeutic interventions. The combination of quantitative measurements and dynamic mathematical modeling has increased our understanding of the within-host infection dynamics and has led to important insights into viral pathogenesis, transmission, and disease progression. Furthermore, virus-host models helped to identify drug targets, to predict the treatment duration to achieve cure, and to reduce treatment costs. In this article, we review important achievements made by mathematical modeling of viral kinetics on the extracellular, intracellular, and multi-scale level for Human Immunodeficiency Virus, Hepatitis C Virus, Influenza A Virus, Ebola Virus, Dengue Virus, and Zika Virus. Herein, we focus on basic mathematical models on the population scale (so-called target cell-limited models), detailed models regarding the most important steps in the viral life cycle, and the combination of both. For this purpose, we review how mathematical modeling of viral dynamics helped to understand the virus-host interactions and disease progression or clearance. Additionally, we review different types and effects of therapeutic strategies and how mathematical modeling has been used to predict new treatment regimens.

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.

Management of acute HCV infection in the era of direct-acting antiviral therapy

The management of acute HCV infection has not been standardized following the availability of direct-acting antiviral agents (DAAs) for chronic HCV infection, and substantial uncertainty exists regarding the optimal treatment regimen and duration. Despite the lack of direct evidence, the 2016 American Association for the Study of Liver Diseases (AASLD)-Infectious Diseases Society of America (IDSA) guidelines supported "the same regimens for acute HCV as recommended for chronic HCV infection … owing to high efficacy and safety", whereas the 2016 European Association for the Study of the Liver (EASL) guidelines recommended sofosbuvir-ledipasvir, sofosbuvir-velpatasvir or sofosbuvir plus daclatasvir for 8 weeks in acute HCV infection, with a longer duration of 12 weeks recommended for those infected with HIV and/or baseline HCV RNA levels >1,000,000 IU/ml. This Review outlines the epidemiology, natural history and diagnosis of acute HCV infection and provides contemporary information on DAAs for acute and recent HCV infection. The Review also discusses the 2016 AASLD-IDSA and EASL recommendations for acute HCV infection management in light of available evidence and highlights key differences in study populations and design that influence interpretation. We focus on populations at high risk of HCV transmission and acquisition, including people who inject drugs and HIV-positive men who have sex with men, and highlight the potential effects of diagnosis and treatment of acute HCV infection in contributing to HCV elimination.

Modeling how reversal of immune exhaustion elicits cure of chronic hepatitis C after the end of treatment with direct-acting antiviral agents

A fraction of chronic hepatitis C patients treated with direct‐acting antivirals (DAAs) achieved sustained virological responses (SVR), or cure, despite having detectable viremia at the end of treatment (EOT). This observation, termed EOT⁺/SVR, remains puzzling and precludes rational optimization of treatment durations. One hypothesis to explain EOT⁺/SVR, the immunologic hypothesis, argues that the viral decline induced by DAAs during treatment reverses the exhaustion of cytotoxic T lymphocytes (CTLs), which then clear the infection after treatment. Whether the hypothesis is consistent with data of viral load changes in patients who experienced EOT⁺/SVR is unknown. Here, we constructed a mathematical model of viral kinetics incorporating the immunologic hypothesis and compared its predictions with patient data. We found the predictions to be in quantitative agreement with patient data. Using the model, we unraveled an underlying bistability that gives rise to EOT⁺/SVR and presents a new avenue to optimize treatment durations. Infected cells trigger both activation and exhaustion of CTLs. CTLs in turn kill infected cells. Due to these competing interactions, two stable steady states, chronic infection and viral clearance, emerge, separated by an unstable steady state with intermediate viremia. When treatment during chronic infection drives viremia sufficiently below the unstable state, spontaneous viral clearance results post‐treatment, marking EOT⁺/SVR. The duration to achieve this desired reduction in viremia defines the minimum treatment duration required for ensuring SVR, which our model can quantify. Estimating parameters defining the CTL response of individuals to HCV infection would enable the application of our model to personalize treatment durations.

Significance of day-1 viral response of hepatitis C virus in patients with chronic hepatitis C receiving direct-acting antiviral therapy

BACKGROUND AND AIM

On-treatment response of serum hepatitis C virus (HCV) is reportedly less useful to predict the outcome of anti-HCV therapy with interferon (IFN)-free regimen with direct-acting antivirals than with IFN-based regimens in clinical trials. We evaluated the significance of very early viral response after the start of therapy, which indicates direct HCV response to the drugs, on therapeutic outcome.

METHODS

Reductions in serum HCV-RNA levels were measured at 1 day after the start of therapy in 544 patients who underwent IFN-free direct-acting antiviral regimens. The association between these reductions and the achievement or failure of sustained virologic response (SVR) was evaluated.

RESULTS

Patient characteristics did not influence 1-day reduction in serum HCV-RNA except for liver fibrosis. There was no difference in 1-day HCV reduction between SVR and non-SVR patients treated with a 24-week regimen. In contrast, in patients treated with a 12-week regimen, 1-day reduction was significantly greater in SVR than in non-SVR patients (P = 0.0013) and was predictive of SVR versus non-SVR (area under the receiver-operating characteristics curve: 0.80).

CONCLUSIONS

Whereas the reduction in serum HCV-RNA levels at 1 day after the start of therapy was not associated with treatment outcomes in patients who underwent a 24-week regimen of IFN-free therapy, there was an association in patients receiving a 12-week regimen, and this reduction was predictive of SVR, thus potentially serving as a factor to identify patients at risk of treatment failure.

Predicting Early Viral Control under Direct-Acting Antiviral Therapy for Chronic Hepatitis C Virus Using Pretreatment Immunological Markers

Recent introduction of all-oral direct-acting antiviral (DAA) treatment has revolutionized care of patients with chronic hepatitis C virus (HCV) infection. Regrettably, the high cost of DAA treatment is burdensome for healthcare systems and may be prohibitive for some patients who would otherwise benefit. Understanding how patient-related factors influence individual responses to DAA treatment may lead to more efficient prescribing. In this observational study, patients with chronic HCV infection were comprehensively monitored by flow cytometry to identify pretreatment immunological variables that predicted HCV RNA negativity within 4 weeks of commencing DAA treatment. Twenty-three patients [genotype 1a (n = 10), 1b (n = 9), and 3 (n = 4)] were treated with daclatasvir plus sofosbuvir (SOF) (n = 15), ledipasvir plus SOF (n = 4), or ritonavir-boosted paritaprevir, ombitasvir, and dasabuvir (n = 4). DAA treatment most prominently altered the distribution of CD8+ memory T cell subsets. Knowing only pretreatment frequencies of CD3+ and naive CD8+ T cells allowed correct classification of 83% of patients as "fast" (HCV RNA-negative by 4 weeks) or "slow" responders. In a prospective cohort, these parameters correctly classified 90% of patients. Slow responders exhibited higher frequencies of CD3+ T cells, CD8+ TEM cells, and CD5high CD27- CD57+ CD8+ chronically activated T cells, which is attributed to bystander hyperactivation of virus-non-specific CD8+ T cells. Taken together, non-specific, systemic CD8+ T cell activation predicted a longer time to viral clearance. This discovery allows pretreatment identification of individuals who may not require a full 12-week course of DAA therapy; in turn, this could lead to individualized prescribing and more efficient resource allocation.

Efficacy, safety and patient-reported outcomes of ledipasvir/sofosbuvir in NS3/4A protease inhibitor-experienced individuals with hepatitis C virus genotype 1 and HIV coinfection with and without cirrhosis (ANRS HC31 SOFTRIH study)

OBJECTIVES

Studies evaluating the efficacy and safety of the fixed-dose combination ledipasvir (LDV)/sofosbuvir (SOF) in patients coinfected with HIV-1 and hepatitis C virus (HCV) have mainly included treatment-naïve patients without cirrhosis. We aimed to evaluate the efficacy and safety of this combination in treatment-experienced patients with and without cirrhosis.

METHODS

We conducted a multicentre, open-label, double-arm, nonrandomized study in patients coinfected with HIV-1 and HCV genotype 1 with and without cirrhosis, who had good viral suppression on their antiretroviral regimens. All patients were pretreated with a first-generation NS3/4A protease inhibitor (PI) plus pegylated interferon/ribavirin. Patients received a fixed-dose combination of LDV/SOF for 12 weeks, or for 24 weeks if cirrhosis was present. The primary endpoint was a sustained virological response (SVR) 12 weeks after the end of therapy. Secondary endpoints included safety, pharmacokinetics and patient-reported outcomes.

RESULTS

Of the 68 patients enrolled, 39.7% had cirrhosis. Sixty-five patients [95.6%; 95% confidence interval (CI): 87.6-99.1%; P < 0.0001] achieved an SVR, with similar rates of SVR in those with and without cirrhosis. Tolerance was satisfactory, with mainly grade 1 or 2 adverse events. Among patient-reported outcomes, only fatigue significantly decreased at the end of treatment compared with baseline [odds ratio (OR): 0.36; 95% CI: 0.14-0.96; P = 0.04]. Mean tenofovir area under the plasma concentration-time curve (AUC) at week 4 was high, with mean ± SD AUC variation between baseline and week 4 higher in cirrhotic than in noncirrhotic patients (3261.57 ± 1920.47 ng/mL vs. 1576.15 ± 911.97 ng/mL, respectively; P = 0.03). Mild proteinuria (54.4%), hypophosphataemia (50.0%), blood bicarbonate decrease (29.4%) and hypokalaemia (13.2%) were reported. The serum creatinine level was not modified.

CONCLUSIONS

LDV/SOF provided a high SVR rate in PI-experienced subjects coinfected with HCV genotype 1 and HIV-1, including patients with cirrhosis.

HCV kinetic and modeling analyses project shorter durations to cure under combined therapy with daclatasvir and asunaprevir in chronic HCV-infected patients

BACKGROUND & AIMS

High cure rates are achieved in HCV genotype-1b patients treated with daclatasvir and asunaprevir, DCV/ASV. Here we analyzed early HCV kinetics in genotype-1b infected Japanese subjects treated with DCV/ASV and retrospectively projected, using mathematical modeling, whether shorter treatment durations might be effective.

METHODS

HCV RNA levels were measured frequently during DCV/ASV therapy in 95 consecutively treated patients at a single center in Japan. Mathematical modeling was used to predict the time to cure, i.e, <1 virus copy in the extracellular body fluid. Patients with HCV<15 IU/ml at week 1 (n = 27) were excluded from modeling analysis due to insufficient HCV RNA data points.

RESULTS

Eighty nine of the 95 included patients (94%) achieved cure, 3 (3%) relapsed due to treatment-emergent resistance, and 3 (3%) completed therapy but were lost during follow up. Model fits from 68 patients with sufficient data points indicate that after a short pharmacological delay (15.4 min [relative standard error, rse = 26%]), DCV/ASV effectiveness in blocking HCV production was 0.999 [rse~0%], HCV half-life in blood was t1/2 = 1.7 hr [rse = 21%], and HCV-infected cell loss rate was 0.391/d [rse = 5%]. Modeling predicted that 100% and 98.5% of patients who had HCV<15 IU/ml at days 14 and 28 might have been cured with 6 and 8 weeks of therapy, respectively. There was a trend (p = 0.058) between younger age and shorter time to cure.

CONCLUSION

Modeling early HCV kinetics under DCV/ASV predicts that most patients would achieve cure with short treatment durations, suggesting that 24 weeks of DCV/ASV treatment can be significantly shortened.

Micro-costing analysis of guideline-based treatment by direct-acting agents: the real-life case of hepatitis C management in Brazil

BACKGROUND

Eradication of hepatitis C virus (HCV) using direct-acting agents (DAA) has been associated with a financial burden to health authorities worldwide. We aimed to evaluate the guideline-based treatment costs by DAAs from the perspective of the Brazilian Ministry of Health (BMoH).

METHODS

The activity based costing method was used to estimate the cost for monitoring/treatment of genotype-1 (GT1) HCV patients by the following strategies: peg-interferon (PEG-IFN)/ribavirin (RBV) for 48 weeks, PEG-IFN/RBV plus boceprevir (BOC) or telaprevir (TEL) for 48 weeks, and sofosbuvir (SOF) plus daclastavir (DCV) or simeprevir (SIM) for 12 weeks. Costs were reported in United States Dollars without (US$) and with adjustment for purchasing power parity (PPP$). Drug costs were collected at the National Database of Health Prices and an overview of the literature was performed to assess effectiveness of SOF/DCV and SOF/SIM regimens in real-world cohorts.

RESULTS

Treatment costs of GT1-HCV patients were PPP$ 43,176.28 (US$ 24,020.16) for PEG-IFN/RBV, PPP$ 71,196.03 (US$ 39,578.23) for PEG-IFN/RBV/BOC and PPP$ 86,250.33 (US$ 47,946.92) for PEG-IFN/RBV/TEL. Treatment by all-oral interferon-free regimens were the less expensive approach: PPP$ 19,761.72 (US$ 10,985.90) for SOF/DCV and PPP$ 21,590.91 (US$ 12,002.75) for SOF/SIM. The overview reported HCV eradication in up to 98% for SOF/DCV and 96% for SOF/SIM.

CONCLUSION

Strategies with all oral interferon-free might lead to lower costs for management of GT1-HCV patients compared to IFN-based regimens in Brazil. This occurred mainly because of high discounts over international DAA prices due to negotiation between BMoH and pharmaceutical industries.

No one size fits all-Shortening duration of therapy with direct-acting antivirals for hepatitis C genotype 1 infection

The advent of shorter duration, highly effective and well-tolerated interferon-free therapy now provides an opportunity for virtually all HCV-infected individuals to be cured. However, there continues to be a need to simplify and shorten treatment duration. Shortening therapy to 8 weeks with sofosbuvir and ledipasvir can be considered in treatment patients with HCV genotype 1 infection and low baseline viral load. A number of other 8-week dual and triple therapy direct-acting antiviral (DAA) regimens are in advanced clinical development. Several small studies have further demonstrated the feasibility of 6 weeks of sofosbuvir therapy in combination with an NS5A inhibitor and a protease inhibitor for HCV genotype 1. Four weeks of therapy with various combinations of the currently available DAAs appears to be suboptimal with poor response rates observed in phase 2 trials. Response-guided therapy is another promising tool that may allow for shorter therapy but require further research. Shortening therapy and retreating relapsers may be a viable cost-saving measure, but requires further cost-benefit analysis and more data on the impact of resistance on retreatment options.

A Robust and Efficient Numerical Method for RNA-Mediated Viral Dynamics

The multiscale model of hepatitis C virus (HCV) dynamics, which includes intracellular viral RNA (vRNA) replication, has been formulated in recent years in order to provide a new conceptual framework for understanding the mechanism of action of a variety of agents for the treatment of HCV. We present a robust and efficient numerical method that belongs to the family of adaptive stepsize methods and is implicit, a Rosenbrock type method that is highly suited to solve this problem. We provide a Graphical User Interface that applies this method and is useful for simulating viral dynamics during treatment with anti-HCV agents that act against HCV on the molecular level.

The paradox of highly effective sofosbuvir-based combination therapy despite slow viral decline: can we still rely on viral kinetics?

High sustained virologic response (SVR) rates have been observed after 6 weeks of anti-HCV treatment using sofosbuvir, ledipasvir and a non-nucleoside polymerase-inhibitor (GS-9669) or a protease-inhibitor (GS-9451) and after 12 weeks with sofosbuvir + ledipasvir. Here we analyze the viral kinetics observed during these treatments to decipher the origin of the rapid cure and to evaluate the possibility of further reducing treatment duration. We found that viral kinetics were surprisingly slow in all treatment groups and could not reproduce the high SVR rates observed. Based on experimental results suggesting that NS5A- or protease-inhibitors can generate non-infectious virus, we incorporated this effect into a mathematical model. We found that to predict observed SVR rates it was necessary to assume that ledipasvir, GS-9669 and GS-9451 rapidly reduce virus infectivity. We predicted with this model that 4 weeks of triple therapy could be sufficient to achieve SVR in patients with undetectable viremia at week 1, but would be suboptimal in general. In conclusion, the rapid cure rate achieved with these combinations is largely disconnected from viral loads measured during treatment. A model assuming that rapid cure is due to a drug effect of generating non-infectious virus could be a basis for future response guided therapy.

Short article: Viral dynamics among hepatitis C virus chronic infected patients during direct-acting antiviral agents therapy: impact for monitoring and optimizing treatment duration

OBJECTIVES

Direct-acting antiviral agents (DAAs) have provided an ultimate treatment duration of 12 weeks for most hepatitis C virus (HCV)-infected patients. The opportunity to reduce treatment duration to 6 or 8 weeks is being evaluated. Here, the HCV viral dynamics at short times during HCV therapies and its implications for monitoring and optimizing treatment duration have been assessed.

PATIENTS AND METHODS

HCV chronic infected patients who began HCV therapy (March 2014 to June 2015) at a reference hospital of the Northwest of Spain were selected. HCV-RNA was quantified at different short time points during HCV therapy using Abbott RealTime HCV assay. Epidemiological, clinical, and virological data were recorded.

RESULTS

Eleven HCV-infected patients were included; 90.9% had cirrhosis (>12.5 kPa) and 72.7% were treatment-experienced. HCV genotype 1b was the most prevalent (72.7%). All of the combinations were pegylated interferon-free and all included ribavirin. The median HCV-RNA (log IU/ml) at baseline was 5.8 (5.4-6.1); the decline between baseline and day 3, weeks 4, 8, and 12 was 3.2, 4.8, 5.1, and 5.6, respectively. Fewer than 50% of patients achieved undetectable viral load at weeks 4 and 8; however, all patients achieved a sustained virologic response at 12 weeks.

CONCLUSION

Rapid and high HCV-RNA decline was observed among HCV-infected patients under DAA-based regimens, especially for those without cirrhosis. Despite low rates of patients with undetectable HCV-RNA at weeks 4 and 8, all achieved a sustained virologic response at 12 weeks. These findings suggest that the time points to monitor HCV-RNA during DAA therapies and the treatment duration need to be optimized.

Modeling HCV cure after an ultra-short duration of therapy with direct acting agents

BACKGROUND

Cases of sustained-virological response (SVR or cure) after an ultra-short duration (≤27 days) of direct-acting antiviral (DAA)-based therapy, despite HCV being detected at end of treatment (EOT), have been reported. Established HCV mathematical models that predict the treatment duration required to achieve cure do not take into account the possibility that the infectivity of virus produced during treatment might be reduced. The aim of this study was to develop a new mathematical model that considers the fundamental and critical concept that HCV RNA in serum represents both infectious virus (V_i) and non-infectious virus (V_ni) in order to explain the observation of cure with ultrashort DAA therapy.

METHODS

Established HCV models were compared to the new mathematical model to retrospectively explain cure in 2 patients who achieved cure after 24 or 27 days of paritaprevir, ombitasvir, dasabuvir, ritonavir and ribavirin or sofosbuvir plus ribavirin, respectively.

RESULTS

Fitting established models with measured longitudinal HCV viral loads indicated that in both cases, cure would not have been expected without an additional 3-6 weeks of therapy after the actual EOT. In contrast, the new model fits the observed outcome by considering that in addition to blocking V_i and V_ni production (ε∼0.998), these DAA + ribavirin treatments further enhanced the ratio of V_ni to V_i, thus increasing the log (V_ni/V_i) from 1 at pretreatment to 6 by EOT, which led to <1 infectious-virus particle in the extracellular body fluid (i.e., cure) prior to EOT.

CONCLUSIONS

This new model can explain cure after short duration of DAA + ribavirin therapy by suggesting that a minimum 6-fold increase of log (V_ni/V_i) results from drug-induced enhancement of the V_ni/V_i.