Telaprevir (Incivek) (VX-950) is an effective inhibitor of HCV NS3-4A serine protease (IC50: 0.35 μM).

In a mouse model, Telaprevir administration at doses of 10 and 25 mg/kg (p.o.) reduced hepatitis C virus protease-dependent cleavage (18.7%) and secretion of SEAP (18.4%) from the liver to the bloodstream. In mice with genotype 1b HCV-infected human hepatocytes, a one-week treatment with Telaprevir at 200 mg/kg resulted in a decrease in HCV RNA levels. Furthermore, when used in combination with MK-0608 at a dose of 50 mg/kg over four weeks, this regimen completely eliminated the virus from the mice.

Telaprevir (17.5 μM) effectively eradicates HCV RNA in replicating cells, with no recurrence observed 13 days post-treatment. When used in combination with IFN-α, Telaprevir moderately enhances the synergistic effect, reducing HCV RNA replication and inhibiting resistance mutations without significant toxicity. The compound exhibits a time-dependent increase in inhibitory efficacy against HCV RNA replication, with IC50 values of 0.574 μM, 0.488 μM, 0.210 μM, and 0.139 μM at 24, 48, 72, and 120 hours, respectively. In Con1 (genotype 1b) subgenomic HCV replicon cells, Telaprevir inhibits the HCV NS3-4A serine protease, suppressing viral polyprotein processing and consequently diminishing all HCV RNA and protein levels in a time and dose-dependent manner. Additionally, Telaprevir shows no toxicity in HCV replicating cells or parent Huh-7 and HepG2 cells after 48 hours of treatment.

Determination of anti-HCV activity: Stable Huh-7 cells containing the self-replicating, subgenomic HCV replicon, which is identical in sequence to the I377neo/NS3-3'/wt replicon are used for anti-HCV assays. Replicon cells are incubated at 37 °C for the indicated period of time with Telaprevir serially diluted in DMEM plus 2% FBS and 0.5% dimethyl sulfoxide (DMSO). Total cellular RNA is extracted using an RNeasy-96 kit, and the copy number of HCV RNA is determined using a quantitative RTPCR (QRT-PCR) assay for the assessment of 50% inhibitory concentration (IC50

Cells are incubated with various concentrations of Telaprevir for 48 hours. Cell viability is determined by using a tetrazolium (MTS)-based cell viability assay.(Only for Reference)