Treatment of chronic hepatitis D with peginterferon lambda-the phase 2 LIMT-1 clinical trial.

BACKGROUND AND AIMS: HDV infection leads to the most aggressive form of human viral hepatitis for which there is no FDA-approved therapy. PEG IFN-lambda-1a (Lambda) has previously demonstrated a good tolerability profile in HBV and HCV patients compared to PEG IFN-alfa. The goal of Phase 2 LIMT-1 trial was to evaluate the safety and efficacy of Lambda monotherapy in patients with HDV. APPROACH AND RESULTS: An open-label study of Lambda 120 or 180 mcg, administered once weekly by subcutaneous injections for 48 weeks, followed by 24 weeks of posttreatment follow-up. Thirty-three patients were allocated to Lambda 180 mcg (n=14) or 120 mcg (n=19). Baseline mean values: HDV RNA 4.1 log10 IU/mL (SD±1.4); ALT 106 IU/L (35-364); and bilirubin 0.5 mg/dL (0.2-1.2). Intention-to-treat rates of virologic response to Lambda 180 mcg and 120 mcg, 24 weeks following treatment cessation were 5 of 14(36%) and 3 of 19 (16%), respectively. The posttreatment response rate of 50% was seen in low BL viral load (≤4 log10) on 180 mcg. Common on-treatment adverse events included flu-like symptoms and elevated transaminase levels. Eight (24%) cases of hyperbilirubinemia with or without liver enzyme elevation, leading to drug discontinuation, were mainly observed in the Pakistani cohort. The clinical course was uneventful, and all responded favorably to dose reduction or discontinuation. CONCLUSIONS: Treatment with Lambda in patients with chronic HDV may result in virologic response during and following treatment cessation. Clinical phase 3 development of Lambda for this rare and serious disease is ongoing.

Treating chronic hepatitis delta: The need for surrogate markers of treatment efficacy.

Chronic hepatitis delta represents the most severe form of chronic viral hepatitis. The current treatment of hepatitis delta virus (HDV) infection consists of the use of interferons and is largely unsatisfactory. Several new compounds are currently in development for the treatment of HDV infection. However, surrogate markers that can be used to develop clinical endpoints in HDV infection are not well defined. In the current manuscript, we aimed to evaluate the existing data on treatment of HDV infection and to suggest treatment goals (possible "trial endpoints") that could be used across different clinical trials.

Sofosbuvir/velpatasvir for 12 weeks in hepatitis C virus-infected patients with end-stage renal disease undergoing dialysis.

BACKGROUND & AIMS: Although off-label use of sofosbuvir-containing regimens occurs regularly in patients with hepatitis C virus (HCV) infection undergoing dialysis for severe renal impairment or end-stage renal disease (ESRD), these regimens are not licensed for this indication, and there is an absence of dosing recommendations in this population. This study evaluated the safety and efficacy of sofosbuvir/velpatasvir in patients with HCV infection with ESRD undergoing dialysis. METHODS: In this phase II, single-arm study, 59 patients with genotype 1-6 HCV infection with ESRD undergoing hemodialysis or peritoneal dialysis received open-label sofosbuvir/velpatasvir (400 mg/100 mg) once daily for 12 weeks. Patients were HCV treatment naive or treatment experienced without cirrhosis or with compensated cirrhosis. Patients previously treated with any HCV NS5A inhibitor were not eligible. The primary efficacy endpoint was the proportion of patients achieving sustained virologic response (SVR) 12 weeks after discontinuation of treatment (SVR12). The primary safety endpoint was the proportion of patients who discontinued study drug due to adverse events. RESULTS: Overall, 56 of 59 patients achieved SVR12 (95%; 95% CI 86-99%). Of the 3 patients who did not achieve SVR12, 2 patients had virologic relapse determined at post-treatment Week 4 (including 1 who prematurely discontinued study treatment), and 1 patient died from suicide after achieving SVR through post-treatment Week 4. The most common adverse events were headache (17%), fatigue (14%), nausea (14%), and vomiting (14%). Serious adverse events were reported for 11 patients (19%), and all were deemed to be unrelated to sofosbuvir/velpatasvir. CONCLUSIONS: Treatment with sofosbuvir/velpatasvir for 12 weeks was safe and effective in patients with ESRD undergoing dialysis. LAY SUMMARY: Sofosbuvir/velpatasvir is a combination direct-acting antiviral that is approved for treatment of patients with hepatitis C virus (HCV) infection. Despite the lack of dosing recommendations, sofosbuvir-containing regimens (including sofosbuvir/velpatasvir) are frequently used for HCV-infected patients undergoing dialysis. This study evaluated the safety and efficacy of sofosbuvir/velpatasvir for 12 weeks in patients with HCV infection who were undergoing dialysis. Treatment with sofosbuvir/velpatasvir was safe and well tolerated, resulting in a cure rate of 95% in patients with HCV infection and end-stage renal disease. Clinical Trial Number: NCT03036852.

Characterization of hepatitis B and delta coinfection in Israel.

BACKGROUND: Characteristics of hepatitis B (HBV) and delta (HDV) coinfection in various geographical regions, including Israel, remain unclear. Here we studied HDV seroprevalence in Israel, assessed HDV/HBV viral loads, circulating genotypes and hepatitis delta antigen (HDAg) conservation. METHODS: Serological anti HDV IgG results from 8969 HBsAg positive individuals tested in 2010-2015 were retrospectively analyzed to determine HDV seroprevalence. In a cohort of HBV/HDV coinfected (n=58) and HBV monoinfected (n=27) patients, quantitative real-time PCR (qRT-PCR) and sequencing were performed to determine viral loads, genotypes and hepatitis delta antigen (HDAg) protein sequence. RESULTS: 6.5% (587/8969) of the HBsAg positive patients were positive for anti HDV antibodies. HDV viral load was >2 log copies/ml higher than HBV viral load in most of the coinfected patients with detectable HDV RNA (86%, 50/58). HDV genotype 1 was identified in all patients, most of whom did not express HBV. While 66.6% (4/6) of the HBV/HDV co-expressing patients carried HBV-D2 only 18.5% (5/27) of the HBV monoinfections had HBV-D2 (p=0.03). Higher genetic variability in the HDAg protein sequence was associated with higher HDV viral load. CONCLUSIONS: The overall significant prevalence of HDV (6.5%) mandates HDV RNA testing for all coinfected patients. Patients positive for HDV RNA (characterized by low HBV DNA blood levels) carried HDV genotype 1. Taken together, the significant HDV seroprevalence and the lack of effective anti-HDV therapy, necessitates strict clinical surveillance especially in patients with higher HDV viral loads and increased viral evolution.

Sustained virological response with intravenous silibinin: individualized IFN-free therapy via real-time modelling of HCV kinetics.

BACKGROUND & AIMS: Intravenous silibinin (SIL) is a potent antiviral agent against hepatitis C virus (HCV) genotype-1. In this proof of concept case-study we tested: (i) whether interferon-alfa (IFN)-free treatment with SIL plus ribavirin (RBV) can achieve sustained virological response (SVR); (ii) whether SIL is safe and feasible for prolonged duration of treatment and (iii) whether mathematical modelling of early on-treatment HCV kinetics can guide duration of therapy to achieve SVR. METHODS: A 44 year-old female HCV-(genotype-1)-infected patient who developed severe psychiatric adverse events to a previous course of pegIFN+RBV, initiated combination treatment with 1200 mg/day of SIL, 1200 mg/day of RBV and 6000 u/day vitamin D. Blood samples were collected frequently till week 4, thereafter every 1-12 weeks until the end of therapy. The standard biphasic mathematical model with time-varying SIL effectiveness was used to predict the duration of therapy to achieve SVR. RESULTS: Based on modelling the observed viral kinetics during the first 3 weeks of treatment, SVR was predicted to be achieved within 34 weeks of therapy. Provided with this information, the patient agreed to complete 34 weeks of treatment. IFN-free treatment with SIL+RBV was feasible, safe and achieved SVR (week-33). CONCLUSIONS: We report, for the first time, the use of real-time mathematical modelling of HCV kinetics to individualize duration of IFN-free therapy and to empower a patient to participate in shared decision making regarding length of treatment. SIL-based individualized therapy provides a treatment option for patients who do not respond to or cannot receive other HCV agents and should be further validated.

Long-term effects of treatment and response in patients with chronic hepatitis C on quality of life. An international, multicenter, randomized, controlled study.

BACKGROUND: Hepatitis C decreases health related quality of life (HRQL) which is further diminished by antiviral therapy. HRQL improves after successful treatment. This trial explores the course of and factors associated with HRQL in patients given individualized or standard treatment based on early treatment response (Ditto-study). METHODS: The Short Form (SF)-36 Health Survey was administered at baseline (n = 192) and 24 weeks after the end of therapy (n = 128). RESULTS: At baseline HRQL was influenced by age, participating center, severity of liver disease and income. Exploring the course of HRQL (scores at follow up minus baseline), only the dimension general health increased. In this dimension patients with a relapse or sustained response differed from non-responders. Men and women differed in the dimension bodily pain. Treatment schedule did not influence the course of HRQL. CONCLUSIONS: Main determinants of HRQL were severity of liver disease, age, gender, participating center and response to treatment. Our results do not exclude a more profound negative impact of individualized treatment compared to standard, possibly caused by higher doses and extended treatment duration in the individualized group. Antiviral therapy might have a more intense and more prolonged negative impact on females.

Waning effectiveness of the third dose of the BNT162b2 mRNA COVID-19 vaccine.

The duration of protection of the third (booster) dose of the BioNTech/Pfizer BNT162b2 mRNA Coronavirus Disease 2019 vaccine has been the subject of recent investigations, as global discussions around the necessity and effectiveness of a fourth dose are already underway. By conducting a retrospective study implementing a test-negative case-control design, analyzing 546,924 PCR tests performed throughout January 2022 by 389,265 persons who received at least two doses, we find that the effectiveness in each month-since-vaccination decreases significantly. Compared to those vaccinated five months prior to the outcome period, on August 2021, relative protection against infection waned from 53.4% a month after vaccination to 16.5% three months after vaccination. These results suggest that there is a significant waning of vaccine effectiveness against the Omicron variant of the third dose of the BNT162b2 vaccine within a few months after administration. Additional information could assist to comprehensively estimate the effectiveness of the three-dose-strategy.

Reduced dose and duration of peginterferon alfa-2b and weight-based ribavirin in patients with genotype 2 and 3 chronic hepatitis C.

BACKGROUND & AIMS: There is increasing interest in identifying patients with chronic hepatitis C genotype 2 or 3 infection in whom it is possible to lower the burden of therapy while retaining high levels of efficacy. METHODS: Treatment-naive patients with chronic hepatitis C genotype 2/3 infection were randomized to receive peginterferon alfa-2b (1.5µg/kg/wk) for 24weeks (group A); peginterferon alfa-2b (1.0µg/kg/wk) for 24weeks (group B); or peginterferon alfa-2b (1.5µg/kg/wk) for 16weeks (group C), each in combination with weight-based ribavirin (800-1200mg/d). The study population comprised two cohorts: the Hep-Net cohort enrolled in Germany and an International cohort enrolled at study sites throughout Europe and Asia. The primary end point was sustained virological response (SVR). RESULTS: The study included 682 patients; 80.2% had genotype 3 infection. In the intent-to-treat population, SVR rates were 66.5%, 64.3%, and 56.6% in groups A, B, and C, and were similar in Asian and white patients. Treatment differences (A vs. B and A vs. C) failed to reach the predefined margin for noninferiority of -10%; and thus groups B and C failed to show noninferiority relative to group A. Among patients with undetectable HCV RNA at week 4, SVR rates were 75.3%, 75.9%, and 72.4%, respectively. Relapse rates were 17.8%, 16.3%, and 29.3%, respectively. Treatment-emergent serious adverse events were highest in group A and lowest in group C, and adverse events leading to discontinuation were similar across treatment arms. CONCLUSIONS: For patients with chronic hepatitis C genotype 2/3 infection, 24weeks of peginterferon alfa-2b (1.5µg/kg/wk) plus weight-based ribavirin remains a standard-of-care therapy; however, treatment for 16weeks may be considered for patients with undetectable HCV RNA at week 4 of the treatment.

Long-term treatment with entecavir induces reversal of advanced fibrosis or cirrhosis in patients with chronic hepatitis B.

BACKGROUND & AIMS: Long-term treatment with entecavir resulted in durable virologic suppression and continued histologic improvement in nucleoside-naive chronic hepatitis B patients. Patients with advanced fibrosis or cirrhosis, who received long-term entecavir treatment, were evaluated for improvement in liver histology. METHODS: The study included a subset of patients from phase III and long-term rollover studies, who received entecavir for at least 3 years, had advanced fibrosis or cirrhosis, and evaluable biopsies at baseline and after long-term treatment. RESULTS: Ten patients had advanced fibrosis or cirrhosis at baseline (Ishak fibrosis score, ≥ 4). After approximately 6 years of cumulative entecavir therapy (range, 267-297 wk), all 10 patients showed improvement in liver histology and Ishak fibrosis score. The mean change from baseline in Ishak fibrosis and Knodell necroinflammatory scores were -2.2 and -7.6, respectively. A reduction in Ishak fibrosis score to 4 or less was observed for all 4 patients who had cirrhosis at baseline. CONCLUSIONS: Chronic hepatitis B patients with advanced fibrosis or cirrhosis demonstrated histologic improvement and reversal of fibrosis and cirrhosis after long-term treatment with entecavir.

Budesonide induces remission more effectively than prednisone in a controlled trial of patients with autoimmune hepatitis.

BACKGROUND & AIMS: Autoimmune hepatitis (AIH) is a chronic liver disease associated with cirrhosis and liver failure. Corticosteroid therapy induces long-term remission but has many side effects. We compared the effects of budesonide (a steroid that is rapidly metabolized, with low systemic exposure) and prednisone, both in combination with azathioprine. METHODS: We performed a 6-month, prospective, double-blind, randomized, active-controlled, multicenter, phase IIb trial of patients with AIH without evidence of cirrhosis who were given budesonide (3 mg, three times daily or twice daily) or prednisone (40 mg/d, tapered to 10 mg/d); patients also received azathioprine (1-2 mg/kg/d). Treatment was followed by a 6-month, open-label phase during which all patients received budesonide in addition to azathioprine. The primary end point was complete biochemical remission, defined as normal serum levels of aspartate aminotransferase and alanine aminotransferase, without predefined steroid-specific side effects, at 6 months. RESULTS: The primary end point was achieved in 47/100 patients given budesonide (47.0%) and in 19/103 patients given prednisone (18.4%) (P < .001; 97.5% 1-side confidence interval [CI] = 16.2). At 6 months, complete biochemical remission occurred in 60% of the patients given budesonide versus 38.8% of those given prednisone (P = .001; CI: 7.7); 72.0% of those in the budesonide group did not develop steroid-specific side effects versus 46.6% in the prednisone group (P < .001; CI = 12.3). Among 87 patients who were initially given prednisone and then received budesonide after 6 months, steroid-specific side effects decreased from 44.8% to 26.4% at month 12 (P < .002). CONCLUSIONS: Oral budesonide, in combination with azathioprine, induces and maintains remission in patients with noncirrhotic AIH, with a low rate of steroid-specific side effects.

Albinterferon Alfa-2b was not inferior to pegylated interferon-α in a randomized trial of patients with chronic hepatitis C virus genotype 1.

BACKGROUND & AIMS: The current standard of care for patients with chronic hepatitis C virus (HCV) genotype 1 is once-weekly pegylated interferon-α (Peg-IFNα) plus daily ribavirin for 48 weeks. We evaluated the efficacy/safety of albinterferon alfa-2b (albIFN), a novel, long-acting, genetic fusion polypeptide of albumin and IFNα-2b. METHODS: In the phase 3 ACHIEVE-1 trial, 1331 patients were assigned equally to 3 open-label, 48-week treatment groups: Peg-IFNα-2a 180 µg every week, or albIFN 900 or 1200 µg every 2 weeks administered subcutaneously, with weight-based oral ribavirin 1000-1200 mg/day. During the study, the data monitoring committee recommended dose modification for all patients receiving albIFN 1200 µg to 900 µg because of increased pulmonary adverse events (AEs) in the 1200-µg arms of both ACHIEVE studies. Main outcome measure was sustained virologic response (SVR; undetectable serum HCV RNA at week 72). RESULTS: Intention-to-treat SVR rates were 51.0% (225/441), 48.2% (213/442), and 47.3% (208/440) with Peg-IFNα-2a, and albIFN 900 and 1200 µg, respectively. The primary objective of showing noninferiority of albIFN 900 µg (P < .001) and 1200 µg (P = .003) vs Peg-IFNα-2a for SVR was achieved. Multivariate modeling indicated consistency of treatment effect across subgroups. Serious/severe AE rates were 23.1%, 24.0%, 28.2%; treatment discontinuation rates because of AEs were 4.1%, 10.4%, 10.0%; discontinuation rates because of respiratory AEs were 0%, 0.9%, 1.6%; with Peg-IFNα-2a, and albIFN 900 and 1200 µg, respectively. Hematologic abnormality rates were comparable across the Peg-IFNα-2a and albIFN 900-µg groups. CONCLUSIONS: albIFN 900 µg every 2 weeks showed comparable efficacy, with similar serious/severe AE rates, although with a higher discontinuation rate, vs Peg-IFNα-2a in patients with chronic HCV genotype 1.

Randomized trial of peginterferon alfa-2b and ribavirin for 48 or 72 weeks in patients with hepatitis C virus genotype 1 and slow virologic response.

UNLABELLED: The benefit of extending treatment duration with peginterferon (PEG-IFN) and ribavirin (RBV) from 48 weeks to 72 weeks for patients with chronic hepatitis C genotype 1 infection has not been well established. In this prospective, international, open-label, randomized, multicenter study, 1,428 treatment-naïve patients from 133 centers were treated with PEG-IFN alfa-2b (1.5 µg/kg/week) plus RBV (800-1,400 mg/day). Patients with detectable hepatitis C virus (HCV) RNA and a ≥2-log(10) drop in HCV RNA levels at week 12 (slow responders) were randomized 1:1 to receive 48 weeks (n = 86) or 72 weeks (n = 73) of treatment. Sustained virologic response (SVR) rates were 43% in slow responders treated for 48 weeks and 48% in slow responders treated for 72 weeks (P = 0.644). Relapse rates were similar in slow responders treated for 48 or 72 weeks (47% versus 33%, P = 0.169). The safety profile was similar in both treatment arms; serious adverse events leading to discontinuation of treatment were observed in 3.5% of slow responders treated for 48 weeks and 8.2% of those treated for 72 weeks. Among slow responders with a <2-log drop in HCV RNA at week 8, SVR was 39% in the 72-week arm and 19% in the 48-week arm. CONCLUSION: These data suggest that 48 weeks of therapy with PEG-IFN alfa-2b plus RBV (800-1,400 mg/day) should remain a standard-of-care treatment for treatment-naïve G1 slow responders.

Modeling Challenges of Ebola Virus-Host Dynamics during Infection and Treatment.

Mathematical modeling of Ebola virus (EBOV)-host dynamics during infection and treatment in vivo is in its infancy due to few studies with frequent viral kinetic data, lack of approved antiviral therapies, and limited insight into the timing of EBOV infection of cells and tissues throughout the body. Current in-host mathematical models simplify EBOV infection by assuming a single homogeneous compartment of infection. In particular, a recent modeling study assumed the liver as the largest solid organ targeted by EBOV infection and predicted that nearly all cells become refractory to infection within seven days of initial infection without antiviral treatment. We compared our observations of EBOV kinetics in multiple anatomic compartments and hepatocellular injury in a critically ill patient with Ebola virus disease (EVD) with this model's predictions. We also explored the model's predictions, with and without antiviral therapy, by recapitulating the model using published inputs and assumptions. Our findings highlight the challenges of modeling EBOV-host dynamics and therapeutic efficacy and emphasize the need for iterative interdisciplinary efforts to refine mathematical models that might advance understanding of EVD pathogenesis and treatment.

[Autoimmune hepatitis].

Autoimmune hepatitis (AIH) is a chronic and progressive disease. The etiology and epidemiologic characterizations of AIH are not fully understood. It has a prolonged course and can affect all age groups. Symptoms and signs may appear years before diagnosis, and may be manifested for extended periods only as minor liver enzymes abnormalities. Clinical manifestations vary from lethargy and jaundice, to extremely severe deterioration in quality of life, hepatic failure and liver transplantation or death. In most cases there is a good response to therapy, making it important to diagnose the disease early in its course. The objectives of this review are to increase the awareness to AIH, to the diagnostic methods and to the treatment modalities and to discuss updates regarding AIH.

High frequency of multiclass HCV resistance-associated mutations in patients failing direct-acting antivirals: real-life data.

BACKGROUND: Direct-acting antiviral (DAA) therapy has dramatically increased sustained virological response rates in HCV-infected patients. However, resistance-associated substitutions (RAS) interfering with NS3- and NS5A-targeted therapy, still emerge. This real-life study analysed the type and frequency of RAS in rare cases of patients failing DAA regimens in 12 clinical centres in Israel. METHODS: Blood samples and clinical data from 49 patients who failed various DAAs were collected. RAS identified in the NS3 and NS5A regions by population (Sanger) and next-generation sequencing (NGS) were compared by treatment regimen and HCV subtypes. RESULTS: The majority (71.4%, 35/49) of patients were infected with the genotype (GT)1b strain, while 12.2% (6/49) carried GT1a and 14.3% GT3a/b (7), GT4a (1) and GT1b/GT3a. RAS were identified in 85.7% (42/49) of failures, of which 90.5% (38/42) were clinically relevant RAS (known to be associated with a specific GT and DAA in patients failing therapy or those with more than twofold change in in vitro replicon assays). The most abundant RAS were 168A/E/Q/G/N/V (32.6%, 16/49) identified in NS3, and 93H/N (61.2%, 30/49), 31I/M/V (34.7%, 17/49) and 30R/H/K (12.2%, 6/49), identified in NS5A. Significantly more clinically relevant RAS were identified in NS5A (82.2%, 37/45) than in NS3 (35.7%, 10/28; P<0.01). While RAS were identified in all GT1a, GT3b and GT4a failures (100%, 10/10), only 71.8% (28/39) of GT1b or GT3a failures had RAS (P=0.09). In four cases, NGS identified additional clinically relevant RAS and in one patient, NGS deciphered coexistence of GT3a and GT1b infections. CONCLUSIONS: Our findings, together with additional real-life data, will contribute to the optimization of retreatment in DAA failure, when cost-related and suboptimal regimens must be employed.

Correction: Modeling suggests that microliter volumes of contaminated blood caused an outbreak of hepatitis C during computerized tomography.

[This corrects the article DOI: 10.1371/journal.pone.0210173.].

Modeling suggests that microliter volumes of contaminated blood caused an outbreak of hepatitis C during computerized tomography.

BACKGROUND & AIMS: Acute hepatitis C (AHC) is not frequently identified because patients are usually asymptomatic, although may be recognized after iatrogenic exposures such as needle stick injuries, medical injection, and acupuncture. We describe an outbreak of AHC among 12 patients who received IV saline flush from a single multi-dose vial after intravenous contrast administration for a computerized tomography (CT) scan. The last patient to receive IV contrast with saline flush from a multi-dose vial at the clinic on the previous day was known to have chronic HCV genotype 1b (termed potential source, PS). Here we sought to confirm (via genetic analysis) the source of infection and to predict the minimal contaminating level of IV saline flush needed to transmit infectious virus to all patients. METHODS: In order to confirm the source of infection, we sequenced the HCV E1E2 region in 7 CT patients, in PS, and in 2 control samples from unrelated patients also infected with HCV genotype 1b. A transmission probabilistic model was developed to predict the contamination volume of blood that would have been sufficient to transmit infectious virus to all patients. RESULTS: Viral sequencing showed close clustering of the cases with the PS. The transmission probabilistic model predicted that contamination of the multi-dose saline vial with 0.6-8.7 microliters of blood would have been sufficient to transmit infectious virus to all patients. CONCLUSION: Analysis of this unique cohort provides a new understanding of HCV transmission with respect to contaminating volumes and viral titers.

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 (Vi) and non-infectious virus (Vni) 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 Vi and Vni production (ε∼0.998), these DAA + ribavirin treatments further enhanced the ratio of Vni to Vi, thus increasing the log (Vni/Vi) 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 (Vni/Vi) results from drug-induced enhancement of the Vni/Vi.

HCV genotype-1 subtypes and resistance-associated substitutions in drug-naive and in direct-acting antiviral treatment failure patients.

BACKGROUND: Direct-acting antiviral (DAA) treatment regimens and response rates of patients with HCV genotype-1 (GT1) are currently considered subtype-dependent. Identification of clinically relevant resistance-associated substitutions (RASs) in the NS3 and NS5A proteins at baseline and in DAA failures, may also impact clinical decisions. METHODS: In a multicentre cohort study (n=308), NS3 or NS5B sequencing (n=248) was used to discriminate between GT1 subtypes. The correlation between baseline NS3 and NS5A RASs on the 12-week sustained virological response (SVR12) rates of 160 of the patients treated with second-generation DAAs was also assessed. Post-treatment resistance analysis was performed on samples from 58 patients exhibiting DAA virological failure. RESULTS: GT1a, GT1b and GT1d subtypes were identified in 23.0%, 75.4% and 1.2% of tested samples. GT1b was most prevalent (97.7%, 128/131) among patients born in the former Soviet Union. The Q80K NS3 RAS was identified in 17.5% (10/57) of the GT1a carriers, most of whom were Israeli-born. NS3 and NS5A baseline RASs showed a negligible correlation with SVR12 rates. Treatment-emergent RASs were observed among 8.9% (4/45) and 76.9% (10/13) of first- and second-generation DAA failures, respectively, with D168V/E (NS3), Y93H and L31M (NS5A) being the most prevalent mutations. CONCLUSIONS: NS3 sequencing analysis can successfully discriminate between GT1 subtypes and identify NS3 amino acid substitutions. While pre-treatment NS3 and NS5A RASs marginally affect second-generation DAA SVR12 rates, post-treatment resistance analysis should be considered prior to re-therapy.