麻豆传媒

WASHINGTON -- Researchers are applying the lessons learned from the first-generation Absorb bioresorbable vascular scaffold (BVS) in developing a new generation of disappearing stents, with some questioning whether it's even worth the effort.

"It's always good to think about history," said Patrick Serruys, MD, PhD, of Erasmus Medical Center in the Netherlands, during a panel at the Cardiovascular Research Technologies annual meeting.

He recalled that bare-metal stents came on the scene in 1986 and drug-eluting stents (DES) in 2000." In 2018, we are extremely happy with the DES, but it took 3 decades to get there. Biodegradables started in 2000."

Now stent thrombosis is the biggest weakness for BVS technology as it stands. "The safety issue is at least likely to be solved with modern-generation devices. We have to show this and go as fast as possible to randomized trials," said Michael Haude, MD, PhD, of Städtische Kliniken Neuss in Germany.

There were updates on a few BVS programs trying to do just that:

• Magmaris: the newer-generation DREAMS 2G stent from Biotronik was renamed "Magmaris" and in BIOSOLVE studies showed zero scaffold thrombosis at 24 months. A sirolimus-eluting magnesium scaffold with PLLA, the device has 150-μm struts and absorbs almost entirely in 12 months.
• DESolve: newer iterations of the novolimus-eluting BVS from Elixir get thinner struts at 120 μm thick. Ongoing clinical study shows no scaffold thrombosis at 60 months. The company will also try out a BVS with shape memory allowing it to "grow to touch the wall."
• Falcon: the second-generation Absorb from Abbott Vascular will keep the old polymer and drug but come with 99-μm struts. Quarter-mm sizing and longer lengths (33 mm and 38 mm) will give operators 40 sizes to choose from.
• Fantom: the second-generation sirolimus-eluting BVS from Reva Medical is radiopaque due to a polymer made with tyrosine amino acid-bound iodine. With struts currently at 125 μm, an even newer generation iteration named "Fantom Encore" will slash them to 95 μm.
• Renuvia: Boston Scientific built on its Synergy stent in creating this BVS with overexpansion capacity. No scaffold thrombosis has been observed at 6 months in a first-in-human study.
• Arteriosorb: an altered orientation of the biodegradable polymer allows this BVS from Arterius to have 95-μm struts with enough tensile strength and ductility, according to preclinical studies performed so far.

That there are so many industry players still striving to perfect BVS technology doesn't mean that it's quite a race, however.

"You look at things differently in industry," said Ian Meredith, MBBS, PhD, global chief medical officer and executive vice president of Boston Scientific.

"You're putting a billion dollars into [research and development] each year, over 10% of the revenue of any 1 year. What are the global priorities of an aging population? What's the cost to actually get this over the line? The value proposition [of BVS] is still a problem," Meredith continued. "You have to show superiority [to DES] to get a price premium. A stent costs $400 or less in many countries. How do you make the math work?"

In the meantime, he said there are still no solutions for opioid addiction and certain cancers, or any that are as sophisticated as the ones for coronary artery disease. Above all, "the single biggest problem of the 21st century is not stent thrombosis, it's heart failure from an aging population. In my position, do I spend $5 on heart failure or $5 on second-generation BVS? That's the question that keeps me awake at night."

Serruys countered that "a great deal of heart failure is lack of prevention" and argued that that is where "acute treatment plays a role."

Nonetheless, Richard Rapoza, PhD, of Abbott Vascular, suggested that the company will also play it safer in its BVS investments. "We will probably will not move as rapidly or aggressively as we had in the past. We'll take steps one foot in front of the other."

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