Phase II clinical trials are in trouble, says Pharmalot's Ed Silverman. According to a new study in Nature Reviews Drug Discovery, success rates for Phase II trials fell from 28 percent in 2006 and 2007 to 18 percent in 2008 and 2009. "The implication is that the overall attrition of late-stage drug development seems to be unsustainably high," Silverman says. Specifically, the study looked at 108 reported failures from 2008 to 2010. Of these, 87 were accompanied by reasons for their failure — 44 were due to "insufficient efficacy," 25 were due to "strategic reasons," and 17 failed because of safety, Silverman says.