By Lisa Seachrist

Washington Editor

CV Therapeutics Inc. will take its atrial arrhythmia drug, CVT-510, into Phase III testing early next year. The compound will join the company's lead compound, ranolazine, in Phase III clinical testing.

Palo Alto, Calif.-based CV Therapeutics announced its decision based on the outcome of the first segment of its Phase II studies testing CVT-510 as a way to stop the rapid heartbeat associated with paroxysmal supraventricular tachycardias (PSVT), a subtype of atrial arrhythmia.

"We've finished the first part of Phase II testing and the data was pretty much exactly what we wanted," said Dan Spiegelman, senior vice president and CFO for CV Therapeutics. "We expect to start the Phase III program at the beginning of next year. We're doing some more dosing refinement work."

Spiegelman said CV Therapeutics has submitted the Phase II results to the American Heart Association for inclusion in its annual meeting to be held in November. In the meantime, the Phase II trials continue in other subtypes of atrial arrhythmias.

More than simply a rapid or irregular heartbeat, atrial arrhythmias can lead to stroke, heart attack and low blood pressure. Approximately 2.6 million people in the U.S. are hospitalized every year with an atrial arrhythmia of one form or another. The arrhythmias are caused by increased electrical conduction through the atrial ventricular (AV) node - the critical regulator of heart rate. The increased electrical conductivity can lead to atrial fibrillation, PSVT or atrial flutter.

Current therapies for atrial arrhythmias include pure adenosine or a calcium channel blocker. Unfortunately, both therapies have difficult side effects. Adenosine causes a serious drop in blood pressure, preventing the drug from being useful as a long-term therapy, while calcium channel blockers take a long time to begin to regulate the heartbeat.

CVT-510, on the other hand, is designed to avoid these problems. Because it's designed to target selectively the A1 adenosine receptor, which is responsible for slowing the AV node, CVT-510 can slow an irregular heartbeat without affecting blood pressure through the activation of the A2 adenosine receptor.

"You really see this happening quickly and from our Phase II results it looks like it works for almost everybody," Spiegelman said.

The Phase II trial is testing the drug under rather controlled conditions - patients are undergoing diagnostic tests in which physicians intentionally induce the atrial arrhythmia before giving the drug. Spiegelman said the Phase III program will test CVT-510 in the emergency room setting. The company still is working out the full details of the study, but Spiegelman said the trial would be a multicenter, randomized, placebo-controlled study of atrial arrhythmias in less than 1,000 patients.

Last year, CV Therapeutics signed a deal with Innovex Inc., a subsidiary of Research Triangle Park, N.C.-based Quintiles Transnational Corp., to outsource the marketing of its angina drug, ranolazine. Ranolazine as a monotherapy proved capable of allowing angina patients to stay on a treadmill anywhere from 22 to 49 seconds longer than placebo-treated patients. CV Therapeutics currently has the drug in a Phase III study in combination with either a beta-blocker or a calcium channel blocker. The company is on track to file a new drug application for ranolazine sometime in 2001. (See BioWorld Today, May 12, 1999, p. 1; and Oct. 8, 1999, p. 1.)

Spiegelman said the company hasn't discussed any marketing plans for CVT-510, but that another such arrangement was definitely on the table.

"It's absolutely something we would consider," Spiegelman said. "The sales force developed for ranolazine could be leveraged to market CVT-510 as well."

Spiegelman said the company believes CVT-510 will follow ranolazine to market by about a year and a half to two years.

CV Therapeutics' stock (NASDAQ:CVTX) closed Tuesday at $41.50, up $4.375, or 12 percent.