Boston Scientific to modify Taxus

Boston Scientific Corp. will modify the way it makes parts of its new Taxus coronary stent system, a spokesman said yesterday, to address medical complications that have cropped up for its hot-selling device.

Stents are small wire mesh tubes used to prop open arteries after angioplasty, and Boston Scientific of Natick has shipped hundreds of thousands of its new Taxus design, a drug-coated version, since it was approved by the US Food and Drug Administration in March. In at least 20 cases since then doctors have run into complications withdrawing the balloons used to place the stents in patients. In at least three other cases, patients needed surgery to remove the balloons after they failed to deflate.

The FDA is looking into the issue, which Boston Scientific calls relatively minor. It believes the withdrawal problems are probably because of doctors' unfamiliarity with the new system.

But to prevent the problem of balloons failing to deflate, Boston Scientific is making a small change in the laser-bonding process it uses to join the balloon and catheter before the stent is packaged around them, said spokesman Paul Donovan. The change will not affect the company's earnings and won't lead to a recall of any of the thousands of Taxus packages that have been shipped but not implanted, he said.

Calling the details of the change proprietary, Donovan declined to be more specific.

The change might still be enough to persuade the FDA not to send out formal notices to physicians, known informally as ''Dear Doctor" letters, of the problems with the device, or to require Boston Scientific to do so. In that case the firm will have sidestepped a problem that dogged its rival, Johnson & Johnson, shortly after it came out with its own drug-coated Cypher stent last year. In October the FDA investigated reports that linked Cypher to more than 60 patient deaths, but the next month the agency determined the death rates were within the expected range. The company later received a warning about its manufacturing practices, however.

The FDA declined to comment on Boston Scientific's efforts, but Donovan said the company had no indication the agency plans to issue a warning or notification.

In a research note to clients May 5 Merrill Lynch analyst Daniel T. Lemaitre wrote that ''While we cannot rule out the possibility that the FDA will ask BSX to send a 'Dear Doctor' letter. . . . we continue to believe that this is not a major issue."

Stents were traditionally placed as bare metal structures to prop open arteries. Taxus and Cypher are coated with minute amounts of drugs to prevent the arteries from narrowing again after the stents are implanted. Boston Scientific says Taxus is off to a fast start since its approval in March, capturing more than 70 percent of a market worth $2.5 billion annually and growing. On Tuesday it said it shipped $205 million worth of the stents worldwide in April, including $163 million in the United States. Johnson & Johnson estimates the companies have a roughly equal market share. Both sell their stents for a little under $3,000 apiece.

Last month, however, Boston Scientific disclosed it had reported to the FDA about 27 cases in which doctors ran into complications during the stenting procedure. In most of those cases the balloons used to implant Taxus seemed to stick to the coating on the stent, creating a potential blockage. In about six cases, Boston Scientific said, the balloons failed to deflate properly, and half of those patients required surgery to have the balloons removed.

Boston Scientific called the problems relatively minor given the large number of Taxus stents that have been implanted without incident, though it has continued to report a small number of both types of problems. The manufacturing change is meant to address the problem of balloons failing to deflate, Donovan said. The company has no plans for manufacturing changes to address the other problem, he said.

''At this time we believe that resistance to withdrawal issue is best addressed by proper adherence to the instructions for use," he said.

Donovan said the FDA approved the manufacturing change on Wednesday and that it has already begun to implement the change at facilities in Minnesota and Ireland where it makes Taxus and its associated Maverick balloon catheter.

Ross Kerber can be reached at kerber@globe.com.