When it comes to treating the narrowing arteries in the legs and thighs, Boston Sci has its Eluvia drug-eluting stent, which received a CE Mark in early 2016, and its Ranger drug-coated balloon, which received a CE Mark in 2014. (Until Boston Sci is able to market the Ranger in the U.S., the company is distributing C.R. Bard’s Lutonix drug-coated balloon.)
It goes without saying, though, that peripheral arteries are not the same as coronary arteries. Jeff Mirviss, the head of Boston Sci’s peripheral interventions business, recently explained the story behind the Eluvia and Ranger’s development to MDO:
MDO: What were some of the technological challenges that Boston Scientific had to overcome to create drug-eluting device technologies such as the Eluvia and the Ranger for use in peripheral vasculature?
Mirviss: Boston Scientific has been doing work in the drug-device combination in the vasculature for 2 decades. We’ve had a lot of success in coronary applications. A lot of our technology leverages the science and expertise and capabilities that we built over the years in this area. And while the coronary vessels are very different than the peripheral vessels in many ways, a lot of the base technology and the base science that we have was informative of our ability to make the devices work safely and effectively in the peripheral application.
To answer your question specifically with regard to challenges overcome, first is finding the right combination of drug and polymer or excipient [substance stabilizing the active ingredient], depending on which one you’re talking about – between drug-eluting stents and drug-coated balloons – that is safe but also effective. With some drugs, not enough drug, and you don’t get the efficacy. But too much drug might be problematic in terms of manufacturing or clinical safety. Finding the right therapeutic window has been definitely an area where that we’ve spent a lot of resources scientifically looking at the optimal combination of drug dose and polymer or excipient.
The second is with regard to having the drug stay on the device effectively within the coating but also coming off at the right timeframe. With our Eluvia drug-eluting stent what is unique about it is the drug is released over a 1 year period of time. That was by design because in the [superficial femoral artery] the restenosis [blood vessel narrowing] occurs over a bit of a longer period of time than the coronary arteries. Most restenosis in the coronary happens in about 6 months, but in the peripheral arteries it happens later, 9 or 12 months. Our hypothesis was that our drugs should be working when restenosis is most likely to occur. Getting the drug to release over the timeframe we wanted at the right rate was another technological challenge that took a lot of work to overcome.
MDO: How do you achieve that? How do you make that possible?
Mirviss: That’s where the polymer does its job. Unlike many other devices in which the drug is quite plainly put on top of the device, whereby the drug can come off during delivery of the device or putting the device through the introducer, the polymer and drug are put on top of the stent together in the manufacturing process. It’s a process to have the combination applied to the stent at the same time. And then when the stent is delivered, the drug can release over a given period of time. We can tune the release of the drug based on the rate the drug comes off as well as the length of time the drug comes off. You can make it come off very quickly in high amounts, or you can make it come off slower over longer periods of time. It’s a tunable technology we have. That’s what we believe is our secret sauce.