On April 1, The FDA approved a new treatment for large brain aneurysms, which are otherwise difficult to treat with surgical clipping or coiling.
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The cPAX Aneurysm Treatment System, created by the company NeuroVasx, of Maple Grove, MN, is intended for surgery on brain aneurysms that are larger than 10 millimeters in size, which can rupture and lead to intracranial bleeding and potentially death.
Similar to coiling, the cPAX system works by filling the space within the aneurysm with a special polymer material to stop the blood flow through the aneurysm. The material can either be placed with a permanent stent or with the help of a temporary balloon catheter.
The system is unique, according to Neurovasx, because the polymer material is detachable at any point along the length of the device and it allows for non-invasive CT and MRI scans.
The FDA recommended that the cPAX system only be used in individuals aged 22 and older, and that it should not be used in those with an active infection or those who cannot undergo anticoagulation and antiplatelet therapy. Already approved for use in Canada and the European Union, the system received US approval under a Humanitarian Device Exemption (HDE), which considers conditions that affect fewer than 4000 people in the US per year.
Two separate open-label studies were conducted in Brazil at one site to evaluate the safety of the cPAX treatment system. Thirty-six subjects were treated; 14 met the criteria for HDE. The primary performance endpoint was aneurysms, which were 90 percent or greater occluded at the 90-day-follow-up. In the HDE population, 66.7 percent of the aneurysms met that endpoint.
“The primary safety endpoint was freedom from device-related neurological deterioration,” said Karyl Haskell, vice president of regulatory affairs and quality assurance at NeuroVasx, Inc. “We evaluated that based on the modified Rankin Scale and found that 92.9 percent of the subjects had no serious neurological deterioration.”
The rate of aneurysms that were retreated in the HDE population was 42.9 percent. “We felt that this was pretty reasonable given that retreatment is at the discretion of the investigator,” Haskell said.
Device-related adverse events were found in 36 percent of patients. Haskell said that these were all anticipated events, including ischemic stroke, monoparesis and somnolence, parent artery occlusion, and also mild headache and confusion. There was one death, but investigators and an independent adjudicator believe it to be caused by the rupture of an aneurysm not treated by the cPAX system.
Commenting by e-mail about the approval to Neurology Today, S. Claiborne Johnston, MD, PhD, professor of neurology and epidemiology and director of the Stroke Service at the University of California-San Francisco, said: “Because large aneurysms can be extremely devastating — beyond just the risk of rupture, they can cause disability and death due to mass effect on neighboring structures — traditional surgical approaches are extremely high risk. Given this, there's definitely a role for new devices such as this one.”
Stephan Mayer, MD, professor of clinical neurology and neurological surgery and head of the Critical Care Neurology Division at Columbia University, was optimistic about the device. “I think that this is just one example of many types of advances in endovascular intervention. I think that it's a good thing and I think that there's going to be a lot more of this to come.”
Dr. Mayer added, “If you have a cerebral hemorrhage, your risk of dying is related to the severity of the initial bleeding, your clinical grade, how old you are, and how big your aneurysm is — and that's simply a function of the fact that surgical morbidity is higher the larger the aneurysm is. So, anything that gives another tool in the armamentarium to try to get these aneurysms treated in a more safe way is going to be good for patients.”
But, he warned that because cPAX was approved under an HDE and has limited study data, there are extra safety considerations to keep in mind. Since it was only tested on 36 patients, “as practitioners begin to get more experience with it, there's always that possibility that after 100 patients, we start to say, ‘oh, wait a minute, here's a low-frequency complication or side effect that we simply didn't have the sample-size to appreciate based on the initial experience.’” However, he added that there has also likely been experience in large animal models before the product moved to human systems.
Despite the risk, people will look to alternate treatments like the cPAX system because the other options of surgery or “leaving these [aneurysms] alone are not appealing to patients with giant aneurysms” said Dr. Johnston. The reason the FDA approves something like this, Dr. Mayer added, is “because it's giving an option when there are no other options.”