(Adds Schering-Plough comment, details on trial, byline)
By Lisa Baertlein
LOS ANGELES, Dec 11 (Reuters) - Schering-Plough SGP.N and Merck & Co (MRK.N) are being investigated by U.S. lawmakers on allegations that the drugmakers are withholding data from a study that may change how doctors treat high cholesterol.
In a letter dated Dec. 11 and emailed to journalists, Rep. John Dingell, Chairman of the Committee on Energy and Commerce, and Rep. Bart Stupak, Chairman of the Oversight and Investigations Subcommittee, requested information on the delayed release of data from their ENHANCE trial concluded in April 2006.
“We are aware of the letter, but have not yet officially received it, so we cannot offer a comment at this time,” said a Schering-Plough spokesman.
No one at Merck was immediately available for comment.
The ENHANCE trial compared the effectiveness of Vytorin — a product of Schering-Plough and Merck in partnership — with Merck’s Zocor in treating patients with a genetic predisposition to dangerously high cholesterol levels.
Vytorin combines the active ingredients from Zocor and Zetia — also from Schering-Plough and Merck in partnership — into a single pill.
The patent on Zocor has expired, and economic research firm Global Insight said in November the two groups hoped to show that Vytorin is superior to Zocor, also known as simvastatin, in a bid to fend off competition from makers of generic simvastatin.
Cardiologists have been clamoring for full results from the ENHANCE trial, which involved some of the industry’s best-selling cholesterol-lowering drugs.
In recent years, drug companies have vowed to promptly deliver clinical trial findings after being chastised for failing to disclose negative trial results.
In the letter, Schering-Plough CEO Fred Hassan and Merck CEO Richard Clark were asked to make the study’s principal investigator and corporate officials available for interviews with committee staff.
Dingell and Stupak also raised concern that the companies changed the trial’s primary endpoint — its main objective.
Merck and Schering-Plough said in a Nov. 20 press release they changed the primary endpoint on the recommendation of an independent panel of clinical and biostatistical experts.
The companies also said it has taken longer than expected to examine artery scans collected during the trial, but they plan to present ENHANCE data at the American College of Cardiology conference in March.
On Tuesday, Schering-Plough posted updated ENHANCE trial information on its Web site. It said researchers now plan to present both the original endpoint and the newer endpoint at the college.
The company also said that as of Dec. 11, neither the company nor the investigators knew the results of the trial. (Editing by Gary Hill and Jan Dahinten)