Boston Scientific pulls away from dissolvable stents

Boston Scientific Corp. is preparing to unveil study results this fall from a long-running program to create a new biodegradable plastic stent, and the findings may well be positive.

The company is going to drop the idea for bioplastic stents anyway.

Discouraging trial results from competitor Abbott Laboratories' bioplastic stents have persuaded Boston Scientific to halt its investment for the foreseeable future in its own long-running program, run from Minnesota, to design a coronary stent that completely biodegrades into the blood vessel wall, a company executive said in an interview Friday.

Biodegradable plastic stents "do show promise. We've just decided strategically that there are bigger problems to deal with, and more socially impactful problems, like stroke, like heart failure, that need our attention," said Dr. Ian Meredith, global chief medical officer for Boston Scientific. "And it is better to invest in those things that will have bigger impacts than to try and overcome the technical challenges [of bioplastic stents] in the short term."

A stent is a medical device about the size and shape of the spring inside a retractable ink pen. In coronary procedures, stents are inserted into clogged blood vessels on the heart, typically after a heart attack caused by a partial or total blockage in the artery.

Traditional stents are made of metal, but Chicago-based Abbott Laboratories, which acquired Minnesota device maker St. Jude Medical in January, is the only company that has approval to sell a completely "bioresorbable" stent in the U.S. The device is called the Absorb GT1 BVS, and it is made of a biodegradable plastic similar to dissolvable sutures.

Such stents were expected to generate billions of dollars in worldwide sales by 2021. The Absorb BVS' safety and effectiveness were initially proven in clinical trials involving more than 30,000 patients around the world. Since then, it has become clear that the device is associated with statistically significant safety problems within two years of implantation that may undermine the long-term benefits from having a device that completely dissolves over time.

"The current findings ... provide evidence beyond any reasonable doubt that Absorb BVS is inferior to new-generation [metal stents made by Abbott] on both efficacy and safety throughout two years," according to an article published Friday in the medical journal the Lancet along with an Abbott-funded meta-analysis of older data. "It cannot be anticipated that the potential long-term benefits of the current version of Absorb BVS will offset the excess in adverse events reported during the first 2 years."

Although mortality rates were similar between Absorb and metal-stent patients, the analysis found that after two years Absorb patients had statistically significant higher rates of the blood vessel becoming reclogged after the procedure and subsequent heart attacks compared to patients who got Abbott's latest drug-eluting metal Xience stent.

Last March, the Food and Drug Administration issued a safety alert for the Absorb stent highlighting an increased rate of major adverse cardiac events among Absorb patients, and cautioning doctors to avoid using the device in smaller blood vessels.

"Absorb has become a very much in niche product, that's for sure," Abbott Chief Executive Miles White said in a quarterly earnings call with stock analysts this month. "I would have wished for it to be a lot bigger than that. But Xience remains a best-in-class stent. That's still true."

Boston Scientific has watched Abbott's Absorb program closely while pursuing its own bioplastic stent, called the Renuvia, which has been implanted in 33 patients in Australia, New Zealand and Latvia as part of an early feasibility study. Boston Scientific's Meredith implanted many of those patients himself as principle investigator for the Renuvia study, before he was hired on as a company executive.

Boston Scientific is scheduled to release six-month results from its Renuvia study at the Transcatheter Cardiovascular Therapeutics annual meeting this fall. Although the results of Boston's bioplastic stent program "look really good" so far, Meredith said, all of those initial patients had relatively uncomplicated medical histories.

"You have to ask the question, do we actually put the effort into studying this in much more complex patients, many of whom are at higher risk of events anyway, against a background of literature from all over the world showing consistently that this strategy is associated with worse outcomes?" Meredith said. "We think it doesn't make sense to do this, and ... we should put our energies into treating bigger problems affecting the human race in the 21st century."

Joe Carlson • 612-673-4779