Medical Device Daily Washington Editor
GAITHERSBURG, Maryland — By a vote of 8-2, with one abstention, the FDA's Circulatory System Devices panel last week recommended approval, with a small number of conditions, for the Gore TAG Thoracic Endoprosthesis, developed by W. L. Gore & Associates (Flagstaff, Arizona).
If given approval by the FDA, the Gore TAG would be the first endovascular device approved in U.S. for patients suffering from a thoracic aortic aneurysm (TAA).
Of particular note was that the company's premarket approval application went through the FDA's expedited approval process.
According to the American Medical Association (Chicago), 15,000 people die annually as a result of TAA. In addition, 5% to 10% of those who die of sudden death (roughly 200,000 annually) are estimated to have died as a result of TAA, which brings the number of deaths up to an estimated 30,000 each year. That is about the same number of people who die every year of breast or prostate cancer.
Aneurysms occur when a section of the aorta, the body's main circulatory vessel, weakens and bulges outward like a balloon. If the aneurysm ruptures, the patient is at high risk for death due to internal bleeding.
TAA is generally believed to be significantly under-diagnosed, because three out of four individuals with aneurysms are asymptomatic, Gore said.
TAA traditionally has been treated with highly invasive open surgery. The procedure requires the surgeon to make a large incision in the patient's chest in order to sew a synthetic graft in place, which prevents the aneurysm from rupturing.
An open surgical procedure is particularly risky for older patients who may suffer from additional medical conditions such as diabetes or hypertension.
Gore says its TAG device is a significantly less-invasive endovascular strategy. The device is inserted through a small incision in the patient's groin, and a catheter delivery system is guided into position through the patient's arteries under fluoroscopy.
Once in position, a reinforced ePTFE- (expanded polytetrafluoroethylene) covered, self-expanding nitinol stent is secured inside the weakened section of the thoracic aorta. This creates a new path for blood flow and relines the aorta. The stent-graft excludes the diseased segment from the pressure of blood circulation, thereby reducing the risk of a rupture.
Data from the pivotal trial showed that Gore TAG patients after 30 days had less than one-fourth the rate of resultant paraplegia (3% vs. 14%) and one-third fewer strokes (11% vs. 33%) than the patients in the control group treated with the traditional surgical option.
The company also reported no aneurysm ruptures in the Gore TAG patients followed through two years. Two years following treatment, the TAG group had 24% mortality, the control group 26%, statistically insignificant.
Procedural blood loss was 80% less in endovascular surgery vs. traditional open surgery, and the stays in intensive care were shortened from three days to one day, Gore said. The company also provided data showing that hospital stays went from 10 to three days.
According to Gore, patients treated with its device experienced less trauma than those who undergo open surgery and shorter recovery time, with a return to normal activity in less than half the time of those undergoing standard open surgery.
The company received a good deal of public support for its product and its trial during the meeting.
Richard Cambria, MD, professor of surgery at Harvard Medical School and chief of the division of vascular and endovascular surgery at Massachusetts General Hospital (both Boston) testified during the panel meeting's open forum.
Cambria called Gore's technology and similar devices “the single significant advance in the treatment of thoracic aortic pathology in our lifetimes.“
Michael Tuchek, DO, a thoracic surgeon with the Loyola University Health System (Chicago), who has performed similar procedures for the same indication using the AneuRx Stent Graft System developed by Medtronic (Minneapolis), also supported Gore and its TAG product.
“I am not here to torpedo their efforts; I am here to applaud them and think they have done a great job with this trial,“ Tuchek said, calling the technology “nothing short of astounding.“ He told the panelists: “This is critically needed technology and far and away better than the open operation. We need an endovascular alternative to treat these patients and I implore you to let this device be approved.“
The panel members did not seem as convinced as the company and other supporters of the device technology. The design of the trial raised questions — in particular the design of the control group — and the amount of data reported by the company was a sticking point for some panelists.
The end decision seemed to come down to individual panel members' belief that having the Gore device on the market would ultimately benefit patients and was not a safety risk.
“We cannot dismiss science,“ said panel member Clyde Yancy, MD, of the University of Texas Southwestern Medical Center (Dallas). “There was significant ambiguity in a study with too few patients. This is technology that needs to be pursued, but we cannot proceed with such thin data.“
Judah Weinberger, MD, a surgeon with Columbia University (New York), pointed to the study design limitations, but said, “What is obvious was that this is a far less morbid procedure than what is currently available surgically.“
He added: “Under the circumstances and having lived through taking care of patients with this disease, I do not think I am in a position to try and withhold a therapy that will very clearly decrease the morbidity of the procedure to such an obvious extent.“
Norman Kato, MD, a surgeon with the Cardiac Care Medical Group (Encino, California), called the control group results of the trial “nothing short of atrocious“ but voted for approval with three conditions because it was “clear“ that the device would be beneficial.
The conditions included a post-approval study, appropriate physician training and some changes in device labeling.
The FDA is not bound by the recommendations of its advisory panels, but follows them in most cases.