Screening of a focused library of TGF beta kinase inhibitors in the cellular HCV replicon model with luciferase read out yielded a number of low micromolar HCV inhibitors. Medicinal chemistry driven optimization resulted in the discovery of 4-[2-(5-bromo-2-fluoro- phenyl) pteridin-4-ylamino]-N-[3-(2-oxopyrrolidin-1-yl) propyl] nicotinamide 36 with a replicon EC50 of 64nM, associated with a selective kinase inhibitory profile for human ...