Consumer Group Battling Approval of Brain Stent

A prominent national watchdog group and former U.S. Food and Drug Administration (FDA) scientist have joined forces to reverse the government’s 2005 approval of a brain stent.

Public Citizen and 13-year FDA veteran Larry Kessler, Sc.D., have petitioned the FDA to pull its humanitarian device exemption (HDE) approval of the Wingspan Stent System, a device used to open blocked blood vessels in the brain. Developed by Natick, Mass.-based Boston Scientific Corp., the Wingspan system consists of a balloon catheter that opens the blocked arteries and a self-expanding nitinol mesh stent tube the keeps the vessels open. The FDA granted Boston Scientific HDE approval of the product based on a 45-patient safety study it conducted at 12 sites in Europe and Asia; results show the Wingspan had a stent success rate of 100 percent, a procedural success rate of 97.7 percent, and a 4.4 percent death/stroke rate in the same hemisphere of the brain as the lesion 30 days after the procedure. The death rate from stroke in the same hemisphere of the brain after six months was 7 percent, according to the study.

A more recent clinical trial, however, revealed conflicting data, leading Public Citizen members to contend the Wingspan system is unsafe and ineffective. Results of the Stenting and Aggressive Medical Management for Preventing Recurrent stroke in Intracranial Stenosis (SAMMPRIS) trial revealed that patients who received aggressive medical therapy alone—without stents—had a significantly lower risk of second stroke and death: 12.2 percent over one year, or less than half the 25 percent rate expected with standard medical therapy. The aggressive medical management—designed specifically for the SAMMPRIS trial—consisted of early treatment with two platelet-blocking agents as well as medications to significantly lower cholesterol levels and control high blood pressure. In addition to being more effective, the treatment is considerably less expensive than stenting.

By contrast, patients receiving stents experienced a second stroke or died within one year about 20 percent of the time, comparable to the 25 percent rate expected with standard medical therapy—but clearly inferior to the 12.2 percent associated with the new medical management protocol. Results of the SAMMPRIS trial were published last fall in the New England Journal of Medicine.

“The message from the trial could not be clearer: The risks of this intervention substantially outweigh any potential benefit to patients,” said Michael Carome, M.D., deputy director of Public Citizen’s Health Research Group. “The [Wingspan] device poses an imminent threat of serious harm to patients and should be pulled from the market without further delay.”

Carome, two of his colleagues (Sarah Sorscher, a researcher with Public Citizen’s Health Research Group; and Sidney M. Wolfe, M.D., director of Public Citizen’s Health Research Group) and Kessler outlined their concerns about the Wingspan system in a 20-page letter to FDA Commissioner Margaret A. Hamburg, M.D., and Jeffrey E. Shuren, director of the FDA’s Center for Devices and Radiological Health (CDRH). The letter accuses Boston Scientific of utilizing the HDE process to gain approval of the Wingspan system based on a clinical trial that was “not designed to demonstrate whether treatment with the device was safer or more effective than medical therapy alone.” It also provides details of several studies that have been conducted since the system was cleared, though the writers acknowledge that each of the studies contain methodological weaknesses which could prevent clinicians from reaching any valid conclusions about the risks and benefits of using the Wingspan system rather than medical therapy alone to prevent strokes. Nevertheless, Carome and company claim the studies prove the Wingspan system “carries substantial risk of grave harm, especially in the short term, including the risk of death and stroke. Of particular concern is the significant number of periprocedural adverse events that can be caused by placement of the Wingspan Stent,” the letter states.

“I understand the FDA needs to use its regulatory authority in flexible and not dogmatic ways, and granting of HDEs when data about safety and effectiveness are not complete is a legitimate exercise of regulatory authority,” Kessler wrote in a letter to Wolfe. Kessler is a former director of the CDRH’s Office of Surveillance and Biometrics, and former director of the CDRH Office of Science and Engineering Laboratories who now works as a professor at the University of Washington’s School of Public Health. “However, for that flexibility, the FDA must realize it has an equally important duty to move swiftly to make regulatory changes and announcements when device problems are uncovered. These compelling post-market data about the Wingspan stent provide an opportunity for the FDA to show to industry, the clinical community and most of all to patients that the agency is serious about exercising its authority by withdrawing the HDE immediately and insisting on a recall to ensure the devices on the U.S. market are both safe and effective.”