Surrogate uncertainty

Partners Merck & Co. Inc. and Schering-Plough Corp. took a beating in January after releasing data from the ENHANCE trial showing that their cholesterol drug Vytorin ezetimibe/simvastatin missed the primary endpoint of reduced progression in carotid intima-media thickness vs. simvastatin alone. Since then, two more trials have raised doubts about the trial designs and endpoints without doing anything to allay concerns about Vytorin’s efficacy.

In one of the trials, similar results from Pfizer Inc.’s Lipitor atorvastatin suggested that intima-media thickness (IMT) may not be a good endpoint...