Mayo Clinic Participating in International Stroke Trial

Thursday, May 24, 2007

SCOTTSDALE, Ariz. - Mayo Clinic is conducting a clinical trial on an investigational drug derived from snake venom that may reduce the extent of stroke-related disability.

The drug is being investigated for treatment of acute ischemic stroke, or a stroke in which a blood vessel to the brain is blocked, leading to loss of neurological function.

Called ancrod, the fibrinogen depleting drug is an enzyme derived from the venom of the Malayan pit viper, which has been found to be a potent natural anticoagulant. It is crucial that the drug, which also acts to break up the clot and reduce blood viscosity, be administered within six hours of the onset of stroke.

Ancrod differs from previous drugs used in trials for ischemic stroke in that current therapies must be administered within three hours, potentially limiting the number of patients who can be treated. The six-hour window allowed by ancrod has demonstrated, in previous U.S. clinical trials, to have a beneficial effect on functional outcome.

Analysis of data from the prior clinical trials of ancrod and other fibrinogen depleting agents in stroke was announced at the 2007 International Stroke Conference in San Francisco, and supported the role of ancrod in breaking up the blood clot caused by a stroke. Sessions at the conference were presented by Mayo Clinic physician-investigators Drs. Bart M. Demaerschalk, Neurology, and Bentley J. Bobrow, Emergency Medicine.

"We conducted a systematic review and meta-analysis of six clinical stroke trials with ancrod and similar agents, involving more than 4,000 patients, to determine the safety and efficacy of these agents for the treatment of acute ischemic stroke," said Demaerschalk. "It appears that ancrod may be promising for treatment, but we need new data."

The new international phases of the clinical trials — in which Mayo Clinic is participating — will examine whether the infusion of ancrod within the six-hour time frame will minimize neurological damage. The primary measurement will be the level of disability experienced by the patient at 90 days following the stroke.

The current trials, under the umbrella called the Ancrod Stroke Program, will use a different dosing regiment than in the previous trials. Those eligible for the trial are adult patients suffering from an acute, ischemic stroke who experience the first symptoms within six hours of beginning treatment.

Mayo Clinic's stroke trial is scheduled to continue through 2008, and it will be vital for patients to get to a stroke center conducting the trial. Mayo Clinic Hospital is the only stroke center in Arizona participating in the Ancrod Stroke Program trials.

According to the American Stroke Association, someone in the U.S. suffers a stroke every 45 seconds, and a stroke-related death occurs every three minutes. May is Stroke Awareness Month.

Mayo Clinic is the first and largest integrated, not-for-profit group practice in the world. As a leading academic medical center in the Southwest, Mayo Clinic focuses on providing specialty and surgical care in more than 65 disciplines at its outpatient facility in north Scottsdale and at Mayo Clinic Hospital. The 208-licensed bed hospital is located at 56th Street and Mayo Boulevard (north of Bell Road) in northeast Phoenix, and provides inpatient care to support the medical and surgical specialties of the clinic, which is located at 134th Street and Shea Boulevard in Scottsdale.

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