SonoLysis^™+tPA Therapy

SonoLysis+tPA therapy involves the administration of our proprietary MRX-801 microbubbles and ultrasound in conjunction with tPA. To administer our SonoLysis+tPA therapy, MRX-801 microbubbles and tPA are injected intravenously into the bloodstream. The MRX-801 microbubbles are distributed naturally throughout the body including to the site of the blood clot. The ultrasound is then administered to the site of the blood clot, and the energy from the ultrasound causes the MRX-801 microbubbles to expand and contract vigorously, or cavitate. We believe this cavitation both mechanically breaks up the blood clot and helps the administered tPA permeate the clot to facilitate clot dissolving activity. The gas released by the MRX-801 microbubbles is then cleared from the body simply by exhaling, and the lipid shell is metabolized like other fats in the body. We believe that this therapeutic approach incorporates two complementary mechanisms of action, mechanical and enzymatic, that together can reduce the time required to dissolve a blood clot and help ensure more rapid and complete restoration of blood flow to at risk brain tissues in patients with ischemic stroke. We are conducting a Phase I/II dose-escalation clinical trial evaluating SonoLysis+tPA therapy in patients with ischemic stroke. We initiated this trial in January 2007, and intend to enroll a total of 72 patients in medical centers in the United States and Europe. Patients will be enrolled into one of four successive cohorts, or groups, that will receive escalating doses of our MRX-801 microbubbles and the standard dose of tPA. A Data and Safety Monitoring Board will review the data from each cohort before granting approval to enroll patients in the succeeding cohort utilizing the next higher dose of MRX-801 microbubbles. We estimate that if approved, over 90,000 ischemic stroke patients in the U.S. could be eligible for SonoLysis+tPA therapy annually.