Ultrasound and Clot-Busting Drug Effective for Stroke

An experimental therapy using tiny bubbles activated by transcranial Doppler (TCD) ultrasound combined with the clot-busting drug tissue plasminogen-activator (tPA) is more effective than tPA alone in treating patients suffering from ischemic stroke, according to new research.

The findings were presented at the American Stroke Association's International Stroke Conference in San Diego, CA, USA, in February 2009, by Andrei Alexandrov, M.D., director of the University of Alabama at Birmingham (UAB) Comprehensive Stroke Center (USA), and Carlos Molina, M.D., from the Vall d'Hebron Hospital (Barcelona, Spain). The study revealed that patients could be treated safely with TCD in combination with a specific dose of the bubbles, called microspheres, and tPA.

The microspheres, developed by ImaRx Therapeutics (Redmond, WA, USA), are tiny gas-filled lipid structures that cavitate (rapidly expand and collapse) when exposed to ultrasound waves, helping to reopen blocked arteries and restore blood flow. "These findings demonstrate that ultrasound combined with microspheres and tPA can be tested further in a pivotal clinical trial with the goal of providing a more effective treatment option for stroke patients by promoting faster clearing of blocked blood vessels as well as improved patient outcomes,” said Alexandrov, UAB professor of neurology. "It's very promising to see such results, which support the potential of this therapy as a more effective and expansive therapy for stroke patients.”

The phase 1/2 trial involved 35 patients and evaluated two different doses of ImaRx's MRX-801 microspheres. Cohort I and cohort II patients received 1.4 ml and 2.8 ml of microspheres, respectively. Control patients received the standard dose of tPA alone.

The researchers reported that complete recanalization was achieved in 120 minutes in 67% of cohort I patients, in 46% of cohort II patients, and 33% of control patients. Dramatic clinical recovery was achieved in 45% of cohort I, 10% of
cohort II, and 27% of controls. Moreover, clinical improvement after 90 days was reported in 75% of cohort I, 50% of cohort II, and 36% of controls.

Stroke is the third-leading cause of death, and the leading cause of disability, in the United States. The vast majority of strokes are ischemic strokes, meaning that they are caused by blood clots, while the remainder are the more deadly hemorrhagic strokes caused by bleeding in the brain.

Related Links:
University of Alabama at Birmingham
Vall d'Hebron Hospital
ImaRx Therapeutics