Ultrasound plus tPA more efficacious for treating stroke victims

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An experimental therapy using gas-filled microspheres activated by transcranial Doppler ultrasound, in combination with the clot busting drug tissue plasminogen activator (tPA), is more effective than tPA alone for ischemic stroke treatment, according to new research presented this week at the American Stroke Association's International Stroke Conference in San Diego.

The microspheres, developed by ImaRx Therapeutics in Redmond, Wash., are gas-filled lipid structures that cavitate when exposed to ultrasound waves, helping to reopen blocked arteries and restore blood flow.

The findings, presented by Andrei Alexandrov, MD, director of the University of Alabama at Birmingham's (UAB) Comprehensive Stroke Center, and Carlos Molina, MD, of the Vall d'Hebron Hospital in Barcelona, Spain, showed that patients can be treated safely with transcranial Doppler ultrasound in combination with a specific dose of the microspheres along with tPA.

"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, professor of neurology at UAB. "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 researchers reported that their 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, and control patients received the standard dose of tPA alone.

Aleaxandrov and Molina reported that complete recanalization was achieved in 120 minutes in 67 percent of cohort I patients, in 46 percent of cohort II patients and 33 percent of control patients. Dramatic clinical recovery has achieved in 45 percent of cohort I, 10 percent of cohort II and 27 percent of controls.

In addition, clinical improvement after 90 days was reported in 75 percent of cohort I, 50 percent of cohort II and 36 percent of controls.