Laetitia Canini

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

BACKGROUND & AIMS Recent clinical trials of direct-acting-antiviral agents (DAAs) against hepatitis C virus (HCV) achieved >90% sustained virological response (SVR) rates, suggesting that cure often took place before the end of treatment (EOT). We sought to evaluate retrospectively whether early response kinetics can provide the basis to individualize therapy to achieve optimal results while reducing duration and cost. METHODS 58 chronic HCV patients were treated with 12-week sofosbuvir+simeprevir (n=19), sofosbuvir+daclatasvir (n=19), or sofosbuvir+ledipasvir in three French referral centers. HCV was measured at baseline, day 2, every other week, EOT and 12weeks post EOT. Mathematical modeling was used to predict the time to cure, i.e., <1 virus copy in the entire extracellular body fluid. RESULTS All but one patient who relapsed achieved SVR. Mean age was 60±11years, 53% were male, 86% HCV genotype-1, 9% HIV coinfected, 43% advanced fibrosis (F3), and 57% had cirrhosis. At weeks 2, 4 and 6, 48%, 88% and 100% of patients had HCV<15IU/ml, with 27%, 74% and 91% of observations having target not detected, respectively. Modeling results predicted that 23 (43%), 16 (30%), 7 (13%), 5 (9%) and 3 (5%) subjects were predicted to reach cure within 6, 8, 10, 12 and 13weeks of therapy, respectively. The modeling suggested that the patient who relapsed would have benefitted from an additional week of sofosbuvir+ledipasvir. Adjusting duration of treatment according to the modeling predicts reduced medication costs of 43-45% and 17-30% in subjects who had HCV<15IU/ml at weeks 2 and 4, respectively. CONCLUSIONS The use of early viral kinetic analysis has the potential to individualize duration of DAA therapy with a projected average cost saving of 16-20% per 100-treated persons.

Severity of liver disease affects HCV kinetics in patients treated with intravenous silibinin monotherapy

BACKGROUND HCV kinetic analysis and modelling during antiviral therapy have not been performed in decompensated cirrhotic patients awaiting liver transplantation. Here, viral and host parameters were compared in three groups of patients treated with daily intravenous silibinin (SIL) monotherapy for 7 days according to the severity of their liver disease. METHODS Data were obtained from 25 patients, 12 non-cirrhotic, 8 with compensated cirrhosis and 5 with decompensated cirrhosis. The standard-biphasic model with time-varying SIL effectiveness (from 0 to final effectiveness [εmax]) was fitted to viral kinetic data. RESULTS Baseline viral load and age were significantly associated with the severity of liver disease (P<0.0001). A biphasic viral decline was observed in most patients with a higher first phase decline in patients with less severe liver disease. The εmax was significantly (P≤0.032) associated with increasing severity of liver disease (non-cirrhotic εmax [se]=0.86 [0.05], compensated cirrhotic εmax=0.69 [0.06] and decompensated cirrhotic εmax=0.59 [0.1]). The second phase decline slope was not significantly different among groups (mean 1.88 ±0.15 log10 IU/ml/week, P=0.75) as was the rate of change of SIL effectiveness (k=2.12/day [se=0.18/day]). HCV-infected cell loss rate (δ [se]=0.62/day [0.05/day]) was high and similar among groups. CONCLUSIONS The high loss rate of HCV-infected cells suggests that sufficient dose and duration of SIL might achieve viral suppression in advanced liver disease.

Distinct immune responses and virus shedding in pigs following aerosol, intra-nasal and contact infection with pandemic swine influenza A virus, A(H1N1)09

Influenza virus infection in pigs is a major farming problem, causing considerable economic loss and posing a zoonotic threat. In addition the pig is an excellent model for understanding immunity to influenza viruses as this is a natural host pathogen system. Experimentally, influenza virus is delivered to pigs intra-nasally, by intra-tracheal instillation or by aerosol, but there is little data comparing the outcome of different methods. We evaluated the shedding pattern, cytokine responses in nasal swabs and immune responses following delivery of low or high dose swine influenza pdmH1N1 virus to the respiratory tract of pigs intra-nasally or by aerosol and compared them to those induced in naturally infected contact pigs. Our data shows that natural infection by contact induces remarkably high innate and adaptive immune response, although the animals were exposed to a very low virus dose. In contacts, the kinetics of virus shedding were slow and prolonged and more similar to the low dose directly infected animals. In contrast the cytokine profile in nasal swabs, antibody and cellular immune responses of contacts more closely resemble immune responses in high dose directly inoculated animals. Consideration of these differences is important for studies of disease pathogenesis and assessment of vaccine protective efficacy.

A pharmacokinetic/viral kinetic model to evaluate the treatment effectiveness of danoprevir against chronic HCV

BACKGROUND Viral kinetic models have proven useful to characterize treatment effectiveness during HCV therapy with interferon (IFN) or with direct-acting antivirals. METHODS We use a pharmacokinetic/viral kinetic (PK/VK) model to describe HCV RNA kinetics during treatment with danoprevir, a protease inhibitor. In a Phase I study, danoprevir monotherapy was administered for 14 days in ascending doses ranging from 200 to 600 mg per day to 40 patients of whom 32 were treatment-naive and 8 were non-responders to prior pegylated IFN-α/ribavirin treatment. RESULTS In all patients, a biphasic decline of HCV RNA during therapy was observed. A two-compartment PK model and a VK model that considered treatment effectiveness to vary with the predicted danoprevir concentration inside the second compartment provided a good fit to the viral load data. A time-varying effectiveness model was also used to fit the viral load data. The antiviral effectiveness increased in a dose-dependent manner, with a 14-day time-averaged effectiveness of 0.95 at the lowest dose (100 mg twice daily) and 0.99 at the highest dose (200 mg three times daily). Prior IFN non-responders exhibited a 14-day time-averaged effectiveness of 0.98 (300 mg twice daily). The second phase decline showed two different behaviours, with 30% of patients exhibiting a rapid decline of HCV RNA, comparable to that seen with other protease inhibitors (>0.3 day(-1)), whereas the viral decline was slower in the other patients. CONCLUSIONS Our results are consistent with the modest SVR rates from the INFORM-SVR study where patients were treated with a combination of mericitabine and ritonavir-boosted danoprevir.

Hepatitis C virus dynamics and cellular gene expression in uPA-SCID chimeric mice with humanized livers during intravenous silibinin monotherapy.

Legalon SIL (SIL) is a chemically hydrophilized version of silibinin, an extract of milk thistle (Silybum marianum) seeds that has exhibited hepatoprotective and antiviral effectiveness against hepatitis C virus (HCV) in patients leading to viral clearance in combination with ribavirin. To elucidate the incompletely understood mode of action of SIL against HCV, mathematical modelling of HCV kinetics and human hepatocyte gene expression studies were performed in uPA‐SCID‐chimeric mice with humanized livers. Chronically HCV‐infected mice (n = 15) were treated for 14 days with daily intravenous SIL at 469, 265 or 61.5 mg/kg. Serum HCV and human albumin (hAlb) were measured frequently, and liver HCV RNA was analysed at days 3 and 14. Microarray analysis of human hepatocyte gene expression was performed at days 0, 3 and 14 of treatment. While hAlb remained constant, a biphasic viral decline in serum was observed consisting of a rapid 1st phase followed by a second slower phase (or plateau with the two lower SIL dosings). SIL effectiveness in blocking viral production was similar among dosing groups (median ε = 77%). However, the rate of HCV‐infected hepatocyte decline, δ, was dose‐dependent. Intracellular HCV RNA levels correlated (r = 0.66, P = 0.01) with serum HCV RNA. Pathway analysis revealed increased anti‐inflammatory and antiproliferative gene expression in human hepatocytes in SIL‐treated mice. The results suggest that SIL could lead to a continuous second‐phase viral decline, that is potentially viral clearance, in the absence of adaptive immune response along with increased anti‐inflammatory and antiproliferative gene expression in human hepatocytes.

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.

Pharmacokinetics and pharmacodynamics modeling of lonafarnib in patients with chronic hepatitis delta virus infection

The prenylation inhibitor lonafarnib (LNF) is a potent antiviral agent providing a breakthrough for the treatment of hepatitis delta virus (HDV). The current study used a maximum likelihood approach to model LNF pharmacokinetic (PK) and pharmacodynamic (PD) parameters and predict the dose needed to achieve 99% efficacy using data from 12 patients chronically infected with HDV and treated with LNF 100 mg twice daily (bid) (group 1) or 200 mg bid (group 2) for 28 days. The LNF‐PK model predicted average steady‐state LNF concentrations of 860 ng/mL and 1,734 ng/mL in groups 1 and 2, respectively, with an LNF absorption rate ka = 0.43/hour and elimination rate ke = 0.045/hour. The PK/PD model identified an average delay of 0.56 hours and an LNF concentration that decreases HDV production by 50%, EC50 = 227 ng/mL, with a Hill factor h = 1.48. The HDV half‐life in blood was 1.87 days, and the average steady‐state LNF efficacy in blocking HDV production was ɛ = 87.7% for group 1 and ɛ = 95.2% for group 2. A biphasic HDV decline with an average phase 1 decline (0.9 log10 IU/mL and 1.32 log10 IU/mL) was observed in groups 1 and 2, respectively. Phase 2 was not significantly (P = 0.94) different between the two groups, with an average slope of –0.06 log IU/mL/day. The model suggests an LNF dose of ∼610 mg bid would achieve ɛ = 99%. Conclusion: The first PK/PD modeling study in patients with chronic HDV indicates that a ∼3‐fold increase in LNF dose (∼610 mg bid) would achieve 99% antiviral efficacy. A ritonavir‐boosted LNF combination may provide a means to increase LNF efficacy with minimal side effects. The modeling findings provide an important advance in understanding HDV dynamics and the basis to optimize LNF therapy for hepatitis D. (Hepatology Communications 2017;1:288–292)

Acute hepatitis B virus infection in humanized chimeric mice has multiphasic viral kinetics

Chimeric urokinase type plasminogen activator (uPA)/severely severe combined immunodeficiency (SCID) mice reconstituted with humanized livers are useful for studying hepatitis B virus (HBV) infection in the absence of an adaptive immune response. However, the detailed characterization of HBV infection kinetics necessary to enable in‐depth mechanistic studies in this in vivo HBV infection model is lacking. To characterize HBV kinetics post‐inoculation (p.i.) to steady state, 42 mice were inoculated with HBV. Serum HBV DNA was frequently measured from 1 minute to 63 days p.i. Total intrahepatic HBV DNA, HBV covalently closed circular DNA (cccDNA), and HBV RNA was measured in a subset of mice at 2, 4, 6, 10, and 13 weeks p.i. HBV half‐life (t1/2) was estimated using a linear mixed‐effects model. During the first 6 hours p.i., serum HBV declined in repopulated uPA/SCID mice with a t1/2 = 62 minutes (95% confidence interval [CI] = 59‐67). Thereafter, viral decline slowed followed by a 2‐day lower plateau. Subsequent viral amplification was multiphasic with an initial mean doubling time of t2 = 8 ± 3 hours followed by an interim plateau before prolonged amplification (t2 = 2 ± 0.5 days) to a final HBV steady state of 9.3 ± 0.3 log copies (cps)/mL. Serum HBV and intrahepatic HBV DNA were positively correlated (R2 = 0.98). Conclusion: HBV infection in uPA/SCID chimeric mice is highly dynamic despite the absence of an adaptive immune response. Serum HBV t1/2 in humanized uPA/SCID mice was estimated to be ∼1 hour regardless of inoculum size. The HBV acute infection kinetics presented here is an important step in characterizing this experimental model system so that it can be effectively used to elucidate the dynamics of the HBV life cycle and thus possibly reveal effective antiviral drug targets. (Hepatology 2018).

Development of anti-hepatitis B surface (HBs) antibodies after HBs antigen loss in HIV-hepatitis B virus co-infected patients

BACKGROUND Hepatitis B surface antigen (HBsAg)-seroconversion, or loss of HBsAg and acquisition of anti-hepatitis B surface (HBs) antibodies, defines functional cure of chronic hepatitis B virus (HBV) infection. After HBsAg-loss, little is known regarding the development of anti-HBs antibodies and even less so in individuals co-infected with HIV. OBJECTIVES To determine anti-HBs antibody kinetics after HBsAg-loss and explore determinants of HBsAg-seroconversion in HIV-HBV co-infected patients. STUDY DESIGN Patients enrolled in the French HIV-HBV cohort were included if they had >1 study visit after HBsAg-loss. Individual patient kinetics of anti-HBs antibody levels were modeled over time using mixed-effect non-linear regression, whereby maximum specific growth rate and maximal level of antibody production were estimated from a Gompertz growth equation. RESULTS Fourteen (4.6%) of 308 co-infected patients followed in the cohort exhibited HBsAg-loss, all of whom were undergoing antiretroviral therapy. Nine (64.3%) of these patients achieved HBsAg-seroconversion during a median 3.0 years (IQR=1.1-5.1) after HBsAg-loss. Across individuals with HBsAg-seroconversion, the fastest rates of antibody growth ranged between 0.57-1.93year-1 (population maximum growth rate=1.02) and antibody production plateaued between 2.09-3.66 log10 mIU/mL at the end of follow-up (population maximal antibody levels=2.66). Patients with HBsAg-seroconversion had substantial decreases in HBV DNA viral loads (P=0.03) and proportion with elevated ALT levels (P=0.02) and HBeAg-positive serology (P=0.08). No such differences were observed in those without HBsAg-seroconversion. CONCLUSIONS Most co-infected patients with HBsAg-seroconversion produced and maintained stable antibody levels, yet kinetics of anti-HBs production were much slower compared to those observed post-vaccination or after clearance of acute HBV-infection.

Reply to: Danoprevir pharmacokinetic/viral kinetic model for treating chronic HCV - some considerations.

Recently, Canini et al. [1] have described for the first time an interesting pharmacokinetic/viral kinetic (PK/VK) model to assess the clinical effectiveness of danoprevir in treating chronic HCV patients in a short-duration treatment with different doses/regimens of danoprevir lasting for 14 days. Therefore, the conceptual thinking and development of the PK/VK model should be commended because of the immense value such a model would provide in understanding the dosing/regimen considerations for treating HCV patients as well as on the utility of such models to optimize the therapy on an individual basis. The intent of the report is not to question the assumptions of the PK/VK model but only to highlight certain key observations that may aid in better understanding of the developed PK/VK model. a) The cursory examination of the tabulated data on the average effectiveness of danoprevir during the course of the treatment suggested almost equal performance of the PK/VK model versus time varying drug efficacy (VE; viral load) model for the various parameters; it was also confirmed by the rigorous statistical analyses [1]. While this may lead to questioning the true value of a more rigorous PK/VK model relative to that of the VE model; the evaluation of predicted first-phase log decline for both PK/VK and VE models sets apart the two models. With the exception of cohort 2 (100 mg, 3 times daily), all remaining cohorts showed differential values between the two models in the first-phase log decline suggesting that the PK/VK model was more conservative as compared with the VE model. Furthermore, the examination of cohort 5 (300 mg, twice daily non-responder) suggested that the VE model predicted the first-phase log decline which was much higher than that of the PK/VK model. On a speculative note, this may imply that the VE model may be prone to false-positive observations as compared with the PK/VK model. Perhaps, the quantum of firstphase log decline may be an important consideration in managing the treatment of HCV with danoprevir and may be used as a guiding principle to differentiate the responder versus non-responder to the drug therapy. b) It may be worthwhile to ask the question of whether increasing the frequency of dosing of danoprevir changed the cohort 5 patients from non-responders to being responders. c) Because the effectiveness of danoprevir therapy is achieved rapidly with a major contribution coming from the first-phase log decline of the viral load after danoprevir dosing, it would have been important to perhaps test the PK/VK model using the first day PK data of danoprevir. Although it is not expected that the combination of the first and last day PK data of danoprevir would drastically change the model as compared with the modelling with first day PK data, such information would have been useful in designing a limited sampling strategy protocol for danoprevir which may include a few PK samples on day 1 of danoprevir dosing in HCV patients. d) As well articulated by the authors, the problematic area is to decipher the almost flat decline of the viral load in the second phase during the treatment with danoprevir in the majority of the patients regardless of the PK/VK versus VE models. Because of treatment-resistant viral strains still in the system it may be difficult to achieve very high cure rates despite the initial rapid decline of the viral load when the therapy was initiated. Hence, the initial rapid decline phase of the viral load may be a key area for differentiating between the PK/ VK versus VE models to understand the robustness of the effectiveness of danoprevir. In summary, the proposed PK/VK model has clarified the effectiveness of danoprevir in a much more robust manner as compared with VE model alone [1]. Although the VE model appears to serve the purpose as enumerated by the modelling exercise, it may be necessary to input the PK component for a rigorous assessment of the viral load data during danoprevir therapy in chronic HCV patients. It is the opinion of the author that development of a limited sampling Letter