The FDA’s neurological devices panel will review clinical data from trials of Stryker’s (NYSE:SYK) Wingspan brain stent system next month, aiming to address harsh criticisms and public petitions urging the agency to recall the device.
The panel plans to consider pre-market and post-market data about the device, including the Gateway PTA balloon catheter and stent delivery system, to address concerns that Wingspan may lead to heightened risk of stroke or death.
Former FDA medical device director Larry Kessler joined consumer watchdog group Public Citizen in December in asking the agency to pull the stent off the market, writing that he could "see no reason why this device should continue to be available."
The trouble began when researchers concluded that high-risk patients who only took medication and received lifestyle coaching had better outcomes than those who also received the implant.
The Wingspan system is approved under the FDA’s humanitarian device exemption protocol. Stryker is currently the only company with the FDA’s OK to sell a brain stent for certain high-risk patients in the U.S. who haven’t responded to drug treatment, having acquired it as part of a $1.5 billion cash buyout of Boston Scientific Corp.’s (NYSE:BSX) neurovascular business in October 2010. Thousands of patients have received the stent so far, according to a press release.
In September 2011, researchers released study results finding that stroke and death rates among patients who received the Wingspan system were 20% at 1 year, compared to 12.2% for the non-stented patients. The results came from the Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis study.
"Stroke specialists are all disappointed that stenting did not have the beneficial impact we thought it would have," Dr. Cathy Sila, principal investigator at the University Hospital Case Medical Center arm of the study, said in at the time.
Researchers suggested that the stent implantation procedure may have dislodged some arterial plaque from the original brain site and set it loose to block other, narrower arteries. Trial enrollment was cut off early when a high adverse effect proportion was found. The study was designed for up to 764 patients, but recruitment was halted when the Data Safety Monitoring Board determined there was enough evidence for a conclusive finding after 451 patients signed on.
Stryker warned that the study, funded by the National Institutes of Health and conducted at 3 U.S. sites, targeted patients earlier in the usual treatment cycle and used a more aggressive drug regimen than used in standard practice.
Researchers at Cedars-Sinai Medical Center in Los Angeles also pointed out that most patients in the study had blockages in smaller arteries, noting that those patients weren’t as sick as those considered in Wingspan’s original studies and thus didn’t fit the population considered most likely to benefit from stenting.
The original study was conducted on 45 patients and did not include a control group of non-stented patients for comparison, finding a 4.4 percent stroke rate after 30 days. Clinical trial standards for effectiveness are less stringent for HDE applications than for pre-market approval submissions.
"The SAMMPRIS trial did not follow the current HDE indication for use; it focused on studying the treatment of severe intracranial atherosclerotic disease, early in the treatment lifecycle and with an aggressive drug treatment regimen and rigorous oversight of medication compliance," Stryker spokeswoman Tamara Cutler told MassDevice at the time, adding that the system is cleared for use in no more than 4,000 patients per year.
Those arguments failed to mollify Public Citizen, who issued a release last month calling the device’s presence on the market a "reckless disregard for public safety."
"I can see no reason why this device should continue to be available," Kessler wrote in a letter in support of the petition. "I understand that 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. 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."
"Due to the FDA’s unconscionable decision to delay withdrawal of the agency’s approval of the Wingspan Stent System HDE, the continued use of this device exposes patients to an unacceptable risk of serious harm, including death," Public Citizen health research group deputy director Dr. Michael Carome said in prepared remarks. "Given the evidence of significant harm with no evidence of any benefit, there is no justification for any additional patients to be treated with this dangerous device."
"Stryker continues to support the Wingspan stent system and Gateway PTA balloon catheter as an FDA-approved Humanitarian Use Device for improving cerebral artery lumen diameter in patients with intracranial atherosclerotic disease who have failed medical therapy," the company said today in a statement sent to MassDevice.