For years, scientists and analysts have predicted an explosion of expensive new agents that are tailor-made to counter the underlying causes of disease, genetic and otherwise. And now such drugs—for example, Sovaldi, for treating hepatitis C—are starting to hit the market. In a new blog post, The Commonwealth Fund’s David Blumenthal, M.D., and David Squires discuss the challenge these drugs present to the nation's efforts to curb health care costs, and outline policies that may help, including the use of comparative effectiveness research, methods for controlling prices, and faster approval for less-expensive alternatives.