In the great battle pitting bare-metal stents (BMS) against drug-eluting stents (DES), the latter seem to have emerged the victor--though by a smaller margin than originally expected. And yet, with the vulnerability of BMS to restenosis and the risk of thrombosis in DES, stents may not be the panacea the medical device industry was anticipating. In the quest to overcome these drawbacks, however, researchers have set their sights on the next frontier: the drug-coated balloon (DCB). But can DCBs live up to these mounting expectations, or are we inflating their potential?
"No one really thought that this would work in the 30-second span of a balloon angioplasty," Ron Sahatjian, president of Medi-Solve Coatings LLC, said in a presentation at MD&M West in February. "Researchers started to put Paclitaxel in human tissue on balloons and found some very interesting things. It had an antiproliferative effect that could last up to 14 days when put into animal tissue. They also found that a 60-second dilatation of the balloon released most of the drug; an hour later they could still find the drug in the tissue."
By supplanting a DES--thus removing the risk of thrombosis--a DCB can eliminate the need for the lengthy antiplatelet therapy required with a DES. "[Antiplatelet therapy] causes a problem because if you have an ulcer... in the body, they won't want to place a DES," Sahatjian said. "For many economic and patient-safety reasons, this is a reason to go after the DCB."
Drug-coated balloons also offer the ability to treat complex lesions and areas that aren't easily accessible using stents. Of particular interest is the potential use of DCBs to treat peripheral arterial disease. Stents placed in the superficial femoral artery in proximity to or below the knee, for instance, are prone to fracture and often require overlapping stents because of longer lesion lengths. DCBs could offer a safer, more-effective alternative. However, studies using DCBs for peripheral applications to date have produced mixed results, often requiring a bailout by a BMS, Sahatjian noted.
Because of these opportunities, DCBs have a market potential of close to $1 billion if proven successful, Sahatjian said. But there are still plenty of problems to resolve. The brevity of DCB function, for example, necessitates the use of extremely high doses of Paclitaxel. But Paclitaxel concentrations near 500 µg can induce aneurysms, Sahatijian said. Thus, the industry needs to strike a careful balance between safety and efficacy when determining DCB drug concentration.
Additional barriers to commercialization include limited data for long-term clinical effects and for large sample sizes, as well as uncertainty about what will happen in the vessel without the support of a scaffold. Regulatory requirements, Sahatjian added, would also be challenging as they would be more in line with submissions for DES than standard balloons.
As these hurdles are cleared, DCBs could make an initial splash as part of a combination therapy with a BMS. This approach could dramatically reduce the required course of antiplatelet therapy while also lowering the risk of restenosis, thanks to the DCB's impact on antiproliferation and endothelialization. But over time, DCBs will hopefully also evolve into an effective standalone treatment, reaching their expanding potential.