use a combination of standard clot-busting drugs along with its proprietary lipid “nanospheres,” small enough to penetrate inside blood clots. These nanospheres are injected intravenously, embed themselves into the clot, and are gently jostled by a low therapeutic dose of ultrasound to the brain, Zakes says. The ultrasound waves are supposed to make the clot gently expand and contract until it dissolves over about an hour. The operative word is gently, because if the clot is busted up too fast, most stroke patients have leaky vessels that can’t handle the sudden rapid blood flow. Opening up the floodgates too fast could lead to severe hemorrhaging, Zakes says.
The data so far on the ImaRx technique is mixed. A trial of 18 patients who took one vial of the ImaRx nanospheres in tandem with ultrasound had positive results, which will be presented at the meeting next month, Zakes says. But trouble showed up in a group of 18 patients who got two doses, he says. Three consecutive patients in that group ended up having severe bleeding episodes, although if the trial had been run properly, they shouldn’t have happened at all, Zakes says. All three patients had severe high blood pressure that was supposed to keep them out of the trial, one also had an overdose of a clot-busting drug, and the other had the bleeding occur on the other side of the brain that wasn’t subjected to ultrasound, he says.
It will be interesting to see if doctors buy this explanation when the full data are presented next month. For now, ImaRx is focusing on turning around with a three-part strategy. The first step is to run tests that can demonstrate its ultrasound technique is at least equivalent to existing methods, so it can get commercial approval for an ultrasound technique that’s more convenient, Zakes says. That should only take 18 months, he says. At the same time, it plans to run the NIH-funded clinical trial of its ultrasound device in combination with a clot-busting drug. The third element would involve trials that bring back its nanoparticles, which could allow doctors to treat stroke for several hours after the original three-hour window passes.
If it all sounds like a long shot, it probably should, but that is the nature of the biotech business. Seattle is home to more than 5,000 people who make a living in the ultrasound business, so there is a pool of potential partners and employees if ImaRx can make good on any part of its strategy. “Seattle is a powerhouse in ultrasound, and for that reason alone we felt it was a good place to re-establish the company,” Zakes says.
