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.

Understanding silibinin's modes of action against HCV using viral kinetic modeling.

BACKGROUND & AIMS: Legalon® SIL (SIL) is a chemically hydrophilized version of silibinin that has exhibited high antiviral effectiveness against hepatitis C virus (HCV). Its main mode of action (MOA) remains unclear, with contradicting in vitro studies supporting either suppression of entry and cell-to-cell spread or suppression of viral RNA synthesis as the main MOA. We sought to provide new insights into SIL's MOA in HCV genotype-1/4 patients receiving intravenous SIL monotherapy for 7 days via mathematical modeling. METHODS: Changes in HCV RNA in 25 patients receiving 10, 15, or 20mg/kg/day of SIL were analyzed and modeled using viral kinetic methods. RESULTS: In 15 patients, the virus declined in a biphasic manner, in which a sharp drop between days 0 and 2 was followed by a slower second phase of decline. In 10 patients, the initial decline was weaker and the virus declined in a single phase over the 7-day period. The blocking production effectiveness, ε, was dose-dependent with mean ε=0.49 and 0.89 in the 10 or 15 and 20mg/kg/day dosing groups, respectively (p=0.02). The effectiveness of blocking viral infection, η, was estimated as 0.60 with no significant differences across dosing groups. For all patients, the mean rate of viral load decline measured between days 2 and 7 was high (0.3 log(10)IU/ml/day), i.e., 4-fold higher than typically observed during the 2nd phase of (pegylated)-interferon-α±ribavirin treatment. CONCLUSIONS: Modeling HCV kinetics in vivo suggests that SIL may block both viral infection and viral production/release with its main dose-dependent effect being blocking viral production/release.