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FDA Panel Questions Intracranial Stent Approval


 

FROM A MEETING OF THE FDA'S NEUROLOGICAL DEVICES PANEL

GAITHERSBURG, MD. – The majority of a Food and Drug Administration advisory panel agreed at a meeting in March that the data on the Wingspan intracranial stent no longer supported the criteria for its approval as a humanitarian device to treat patients with intracranial arterial stenosis.

At the meeting, which was held to discuss the future of the device, all but 1 of the 15 members of the FDA’s Neurological Devices Panel agreed that the available safety and effectiveness data on the Wingspan stent – which include a randomized controlled study that was terminated early because of a higher stroke rate in the stent arm – did not support the "probable benefit to health" for humanitarian device’s approval as a treatment for intracranial stenosis. About two-thirds of the panel also agreed that there were not sufficient data to indicate that the probable benefit of the stent outweighed its risk in any subpopulation of patients, although several panelists supported keeping the stent available for the very small group of patients with no other options.

The panel was not asked to vote officially on these questions, but panelists clearly stated their opinions.

"I have seen nothing today that shows me that the benefits outweigh the risks that caused a study to be prematurely terminated," said Dr. Christopher Loftus, professor and chairman of the department of neurosurgery, Temple University Hospital, Philadelphia.

Dr. Karen Johnston, chair of neurology at the University of Virginia, Charlottesville, pointed out that making the stent available as an investigational device was an option. "Then we could actually take these patients and offer them this treatment in an organized clinical trial ... and learn something in a standardized way," she said.

In 2004, the Wingspan Stent System with Gateway PTA Balloon Catheter was designated as a humanitarian use device, and in August 2005, the FDA approved the Wingspan system under a humanitarian device exemption (HDE) for use in improving cerebral artery lumen diameter in patients with intracranial atherosclerotic disease, refractory to medical therapy, in intracranial vessels with at least 50% stenosis "that are accessible to the system." The approval was based on a prospective, single-arm study of 45 people outside the United States, with at least 50% stenosis, who had recurrent strokes and were refractory to treatment with warfarin and/or aspirin.

The agency’s criteria for HDE approval is based on safety and "probable benefit" from use of a device, which "outweighs the risk of injury or illness from its use, taking into account the probable risks and benefits of currently available devices or alternative forms of treatment." A standard device approval is based on safety and a reasonable assurance of effectiveness.

After the HDE approval, investigators independent of the stent’s manufacturer, Stryker Neurovascular (formerly Boston Scientific Neurovascular), launched the SAMMPRIS (Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis) trial. The National Institute of Neurological Disorders and Stroke sponsored the randomized trial, which compared angioplasty and stenting with the Wingspan system combined with aggressive medical therapy (with aspirin and clopidogrel) against aggressive medical therapy alone in high-risk patients with 70%-99% intracranial arterial stenosis (the median was almost 80%). Stryker provided the device for the study. Enrollment was stopped prematurely in April 2011, after it was determined that 14.7% of the patients in the stent arm died or had a stroke within 30 days of enrollment, compared with 5.8% of those in the medical management arm, a significant difference (N. Engl. J. Med. 2011;365:993-1003).

Since these interim results were published in September 2011, four Institutional Review Boards have withdrawn approval of the HDE, according to the FDA. And in December, a citizen’s petition to withdraw the HDE approval was filed by Public Citizen’s Health Research Group, stating that the device was ineffective and there was no reasonable assurance that it was safe under the conditions of use prescribed, recommended, or suggested in the labeling.

At the meeting, Stryker Neurovascular said that the Wingspan system should remain available as a humanitarian device for the small group of patients described in the approved indication. Among the points made by the company was that only about 8% of the patients in the SAMMPRIS study met the inclusion criteria for the HDE study, and that many of the patient subtypes who were treated with the stent in the HDE study were underrepresented in the SAMMPRIS study.

The company said that there was a population of patients for whom the probable benefit of treatment with the device outweighed the risk of injury or illness from its use, such as a patient who has failed treatment with aggressive medical management, or for whom this treatment is inappropriate and have failed another medical therapy regimen.

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