Device: Abbott's Absorb Bioresorbable Vascular Scaffold
CE mark: Yes (2011)
U.S. clinical trials: Yes, main endpoint expected in 2015
Either the FDA will reject its product after millions of dollars spent on clinical trials or Abbott's ($ABT) Absorb Bioresorbable Vascular Scaffold (BVS) will be the first stent in the class to win coveted FDA approval, though neither outcome will occur until 2015 at the earliest, when the company says it plans to submit for FDA approval.
The dissolvable stent made of a lactic acid polymer begins to break down within a year (except for two tiny platinum markers that guide placement during surgery) and elutes everolimus in a similar manner to the company's drug-eluting Xience V. Abbott told FierceMedicalDevices that the product is available in 7 sizes from 2.5 to 3.5 mm, with more anticipated before year-end.
|Abbott's Absorb bioresorbable stent--Courtesy of Abbott|
The BVS and Elixir Medical's DESolve Scaffold System are the only devices with CE marks, but GlobalData research analyst Priya Madhavan says the physicians she has talked to tell her that Elixir's stent isn't yet widely available in Europe. That's because the BVS won European approval in 2011, more than two years prior to the DESolve. BVS is also available in some emerging markets, including India, where it had been used more than 2,500 times in less than a year after the September 2012 launch.
Abbott told FierceMedicalDevices that its stent has been implanted in 50,000 patients so far, and 5,000 patients are enrolled in its clinical trials--including in the U.S., where it is the only bioresorbable stent to be tested so far. The Absorb III trial commenced in January 2013 and the company hopes to enroll about 2,250 patients. According to ClinicalTrials.gov, the main endpoint is noninferiority against Abbott's Xience drug-eluting stent as measured by the rate of target lesion failure at the patient's one-year follow-up. Secondary endpoints include the in-stent/scaffold mean lumen diameter change at three years, procedural success and death rates at various time frames up to 5 years.
The U.S. trial is still enrolling patients, and data collection on the main endpoint will conclude in August 2015, meaning approval won't come before then. The estimated study completion date is December 2019. A similar trial to gain Japanese approval commenced in June 2013, and the company said in April that it has concluded enrollment of a trial in China to gain approval there as well.
Previous worldwide trials have already provided a wealth of data on BVS. At the 2013 meeting of the American College of Cardiology, Abbott announced that the rate of major of adverse cardiovascular events was 10% at three years in a trial of 100-plus patients from Europe, Australia and New Zealand, similar to the complication rate of the leading drug-eluting stents.
A 7.2% increase in the area within the coronary artery was observed in a subset of 45 patients between years one and three postsurgery, a finding that Abbott said is unique to BVS. Elixir's DESolve has also demonstrated late lumen gain, but Biotronik's bioresorbable stent did not, explaining why it is still in the clinical testing stage.
Overall, the accumulation of evidence supporting the BVS is a big part of Abbott's first-mover advantage. But the scrutiny can also be a drawback. A recent European postmarket data registry found that although the device performed well on most measures, the risk of the BVS being blocked by a blood clot is about twice as high as that for today's gold-standard drug-eluting stents.
Abbott is counting on U.S. approval to lift its vascular division, which is growing more slowly than the rest of the company. Abbott CEO Miles White told investors during a July 14 conference call that "it's no secret there are some areas of the business we've got to pay more attention to strategically, not so much because they're weak, but because they need new shots of life, and I'd say vascular has been identified that way."
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