ImaRx Therapeutics, a biopharmaceutical company developing and marketing therapies for vascular disorders, has provided an update of its Transcranial Ultrasound in Clinical SONolysis (TUCSON) clinical trial in patients with acute ischemic stroke.
The TUCSON trial, a Phase I/II randomized, placebo controlled clinical trial, is designed to evaluate the safety, tolerability and activity of four escalating doses of MRX-801 microbubbles and ultrasound as an adjunctive therapy to tissue plasminogen activator (tPA) treatment in subjects with acute ischemic stroke, according to the Tucson, Ariz.-based ImaRx.
The company said the trial design includes four dose cohorts of 18 subjects each randomized to receive either treatment (MRX-801, ultrasound and tPA) or control (tPA alone). Safety is assessed by the incidence of symptomatic intracranial hemorrhage (sICH) within 36 hours following the initiation of treatment, while activity is assessed by recanalization, defined as increased blood flow in the occluded artery. To date, ImaRx said it has completed the enrollment of all 18 subjects in Cohort 1 (12 treated and 6 control) and 17 subjects in Cohort 2 (11 treated and 6 control).
Cohort 1 evaluated one vial of MRX-801, and the company said that there were no unexpected safety events and there were signs of improved recanalization in treated patients compared to controls. In clinical recovery endpoints, the number and proportion of patients who experienced dramatic or early clinical recovery were higher in the treatment group compared to controls. Clinical recovery at 24 to 36 hours was roughly equivalent in both groups as was neurological improvement at 24 to 36 hours.
Cohort 2 evaluated two vials of MRX-801, ImaRx said the activity data from subjects in this cohort is currently being collected and will be available in the second quarter of 2008.
Garen Manvelian, MD, chief medical officer for ImaRx, said it “is well known that tPA has an associated risk of bleeding. We believe that the intracranial hemorrhage events, such as those observed in Cohort 2, may be reduced by eliminating tPA in our future SonoLysis clinical studies in stroke.”
ImaRx said it expects to begin its next SonoLysis clinical study in the second half of 2008. To avoid the inherent bleeding risk associated with tPA, the company intends to conduct its future clinical trials under its SEDONA program, MRX-801 microbubbles and ultrasound, without tPA.