JTK-853 inhibits the drug-resistant colony formation in the genotype 1a replicon cells, and the numbers of JTK-853-resistant colonies are much lower than those of GS-9190-resistant colonies for both genotypes. When JTK-853 is incubated with the replicon cells for 48 h, it shows antiviral activity against genotype 1a H77 and 1b Con1 replicon cells (EC90: 6.5±0.5 and 0.34±0.05 μM, respectively). In 2-week culture, JTK-853(at 10 μM) causes apparent Huh-7.5 cell death[1].