It will still take about four to five years of work to get the drugs to market, Bernstein wrote. But “this will certainly create an overhang for Gilead’s stock given the greater credibility and resources that Merck brings to the table, as well as the broader portfolio of combination options.”

Merck is primarily interested in IDX21437, an Idenix drug known as a nucleotide, or "nuke." Merck plans to combine the drug with two of its own drugs that work by different mechanisms for a triple-drug regimen that could potentially cure most types of hepatitis C in less than two months. That triple regimen, however, is probably about three years away from reaching the market, assuming clinical trials are successful and regulators approve it, analysts say. Merck hopes to bring the double-drug regimen to market first. (from WSJ)