Abbott's new dissolving stent may be 'next revolution'

Updated 3/1/2011 5:18 PM
  • Artist's rendering of Abbott's new polylactic acid dissolving stent.

    Artist's rendering of Abbott's new polylactic acid dissolving stent. Courtesy Abbott Labs

John Lamb, a retired auto mechanic in New Zealand, was the first patient to get one of Abbott Laboratories' experimental heart stents to treat chest pains. In a sense, he now has nothing to show for it -- as doctors intended all along.

Abbott's stent, a scaffold-like device the size of the spring in a ballpoint pen, was inserted into one of Lamb's coronary arteries in March 2006 and inflated under pressure to prop open the passage, which had been clogged by fatty plaque. Unlike metal stents, Abbott's is made of polylactic acid and designed to dissolve within two years after implant. It left a healthy, unencumbered vessel, John Ormiston, Lamb's doctor in Auckland, tells Bloomberg Businessweek in its Sept. 13 edition.

If studies confirm the device helps arteries and disappears without causing clots or other risks linked to metal models, the product may take the lead in the $4 billion-a-year market for drug-coated stents, as it would be safer for patients, said John Capek, Abbott Park-based Abbott's executive vice president of medical devices. Demand would fall for Abbott's Xience stent and rivals from Johnson & Johnson, Boston Scientific Corp. and Medtronic Inc., he said.

"It may truly become the next revolution," Capek said in a telephone interview. "The data are provocative enough at the moment to demonstrate that has a very real chance of happening."

Abbott's new product may reach commercial channels in Europe within 18 months, putting it three years ahead of dissolving stents being developed by Reva Medical Inc. in San Diego and Biotronik SE in Berlin, Capek said.

'Incredible Premium'

Abbott rose 62 cents, or 1.2 percent, to $51.07 at 10:34 a.m. in New York Stock Exchange composite trading. The shares climbed 9.9 percent in the 12 months before today.

At New Brunswick, New Jersey-based Johnson & Johnson, officials say they aren't sure how much promise there is in dissolving stents.

"For coronary stents, there is an incredible premium on stent performance," said Campbell Rogers, chief scientific officer for J&J's Cordis unit, in a telephone interview. "You need a Ferrari. The bioresorbable stent is a larger, bulkier stent. The likelihood of it being a significant advance for patients and clinicians in coronary use is not great."

The dissolving stent is designed to confer the benefits of existing devices without leaving behind the "metal spider," the image that appears during an X-ray of a patient whose coronary arteries are fully stented. Current stents don't shrink and expand with the artery's natural movement. The metal devices can trigger deadly clots, and may interfere with future tests and surgeries, Capek said.

Abbott Redesign

Abbott redesigned its dissolving stent last year after engineers found it didn't keep arteries open so well as expected during studies in Europe. Additional research will follow in the U.S., where marketing requirements are more stringent.

It may be difficult for the new material to hold open an artery as well as metal devices do, said Laura Mauri, a cardiologist and stent researcher in Boston at Brigham & Women's Hospital and Harvard Medical School.

The devices have to withstand pressure, particularly when doctors insert them into severely blocked arteries, she said.

"There is a lot of enthusiasm in Europe that this may be a new breakthrough technology," Mauri said in an interview. "They've really just passed the first hurdle."

The disappearing devices might solve one problem that has hampered sales of drug-coated stents since 2006: the formation of blood clots years after implantation. Studies show clots develop in 0.2 percent to 3.1 percent of patients.

Heart Attacks

The risk doesn't decline over time, and the result is often fatal. Heart attacks occur in as many as 65 percent of patients with the clots, a 2008 study found.

There haven't been any cases of clots in people getting Abbott's bioresorbable stent, Capek said. Data on 45 patients, who were followed for nine months after treatment, will be presented at the Transcatheter Cardiovascular Therapeutics meeting in Washington Sept. 21-25.

Abbott's approach is part of an evolution, said Patrick Serruys, chief of interventional cardiology at Erasmus Medical Center in Rotterdam, who has been a pioneer of the technology.

Doctors first cleared clogged arteries with a balloon, inflating it inside a blockage to allow blood to flow. The arteries often snapped shut or reclogged, leading researchers to craft metal tubes that were left behind to prop open the vessels.

Coated Stents

The devices attracted scar tissue, again narrowing the artery over time, and one in four patients needed retreatment. Makers finally coated the stents with drugs to prevent tissue from attaching.

The artery never fully healed with a drug-coated device inside, and years after treatment some people developed blood clots that caused heart attacks and deaths. As a result, patients take blood thinners to prevent clots, putting them at risk of internal bleeding.

With a dissolving stent, the treated arteries are able to bend, expand and contract with natural movement, Serruys said. Patients using the product won't need years of treatment with drugs such as Paris-based Sanofi-Aventis SA's Plavix, he said.

Abbott's main competitors in the stent market are in the early stages of evaluating dissolving devices. Most of their work is in places such as the leg where the larger size of an absorbable stent isn't a problem.

Stress and pressure on the legs can cause metal stents to fracture, making an absorbable device more attractive, said Sean Salmon, vice president and general manager of Minneapolis-based Medtronic's coronary and peripheral division.

Boston Scientific

While Natick, Massachusetts-based Boston Scientific is working on bioresorbable stents for leg and heart arteries, the company's emphasis in research is something else: metal devices with coatings that dissipate over time, said Keith Dawkins, chief medical officer for the cardiology, rhythm and vascular group.

"There is very little evidence that the long-term presence of a metal scaffold is detrimental," J&J's Rogers said. "There are millions and millions of patients with metal scaffolds in their arteries and are doing fine."

$1.6 Billion in Sales

The initial six-month results of the Absorb trial showed that Abbott's dissolving device is as effective as Xience, the industry leader with $1.6 billion in 2009 sales. There were few complications, and the product performed as well as existing stents.

The study may be enough to win approval in Europe, where companies must show only that medical devices are safe and similar to products that are already available, said Richard Rapoza, head of Abbott's bioresorbable technology development program, in an interview. Patients have undergone tests, including intravascular ultrasound, induced vasodilation, and optical coherence tomography.

Reva Medical, founded in 1998, is working on a stent that starts to resorb after 90 days. The company redesigned its prototype after patients who received it in a 2007 study needed repeat treatment. Reva, whose investors have included Boston Scientific and Medtronic, aims to start another trial by next year. Now closely held, the company plans a public sale of securities to be traded in Australia, according to a regulatory filing on Aug. 13.

Biotronik's bioresorbable drug-coated metal stent, made from magnesium and dubbed Dreams, was implanted in its first patient in August, in Germany, said Sandy Hathaway, a company spokeswoman, in an e-mail. Biotronik, founded in 1963 by the developers of a heart pacemaker, is closely held.

'Right Choice'

About half of all patients requiring stents have single, easy-to-treat blockages that may be perfect for the dissolving device, Abbott's Rapoza said. Lamb, the New Zealander, is one.

"I made the right choice," Lamb, now 69, said in a telephone interview. "It appealed to me that it dissolved and I wouldn't have a piece of hardware in my body."

Before the procedure, Lamb had difficulty walking the 500 meters (1,640 feet) from his house in Tauranga, a city southwest of Auckland, to the road each day, to pick up mail, without taking a breather. The pain crept up his neck and arms, strangling his chest like a tourniquet.

"It made an immediate difference, overnight," Lamb said. "It's as good as gold."