Schering says image quality hobbled Vytorin study

NEW YORK, Jan 3 (Reuters) - The chief executive of Schering-Plough Corp SGP.N on Thursday said poor quality of ultrasound images hobbled a closely watched trial of its Vytorin cholesterol fighter, and stressed that the controversial study involved a "narrow population" of patients.

U.S. lawmakers in December said they would probe allegations that Schering-Plough and its marketing partner Merck & Co Inc (MRK.N) withheld data from the so-called ENHANCE trial. They tested Vytorin among patients with a genetic predisposition to dangerously high cholesterol levels.

The lawmakers have said they wanted to know why the companies changed the study's primary endpoint, or main objective, while the study was under way -- and focused instead on a newer endpoint before the trial was completed in April 2006.

"There are some quality challenges" with the ultrasound data, Chief Executive Fred Hassan told investors at a Morgan Stanley investor conference being held in New York. He said the trial "was designed with good science in mind," but involves a "narrow population of people with high cholesterol levels."

Schering-Plough has said it now plans to present data from both the original endpoint and newer endpoint at a medical meeting in March. (Reporting by Ransdell Pierson, editing by Gerald E. McCormick)