麻豆传媒

An FDA advisory committee was nearly unanimous in support of approval of Abbott's Absorb bioresorbable vascular scaffold (BVS) at a panel meeting Tuesday.

Given the findings of the ABSORB series of trials, "the porridge is just the right temperature" for the "disappearing" stent, said panel member , of Rush University Medical Center in Lake Bluff, Ill.

The panel voted 9-0 (with 1 abstention) that the benefits outweigh the risks for what would be the first bioabsorbable scaffold stent if approved. The FDA is not obligated to follow the recommendations of its advisory committees but usually does.

The committee spent the day debating the merits of the BVS, which has shown non-inferiority -- but not superiority -- against the Xience everolimus-eluting drug-eluting stent (DES) from the same manufacturer. In fact, the theoretical long-term benefits of a dissolving scaffold are yet to be seen, while ABSORB III revealed last year that the rate of target lesion failure favored the metallic DES without reaching statistical significance (7.8% for BVS versus 6.1% for DES).

"There is a large patient population whose focus would be on safety more than anything else. The question marks here that we might not have with other stents out there would be the difficult challenge of explaining to patients why they should go with BVS, given those unknown factors," consumer representative and panelist Naftali Z. Frankel, MBA, noted, suggesting that not all patients would mind having a permanent metal device in their bodies if it was shown to be safe.

Among the other issues on the table was the pattern of poor outcomes associated with BVS use in small vessels, particularly under 2.5 mm. Representing the sponsor, , of Columbia University Medical Center/New York-Presbyterian Hospital, recommended that operators quantitatively measure lesions 2.75 mm or below to make sure they are placing BVS in appropriate-sized vessels. That cutoff relieves the burden of intravascular imaging done in the cath lab, he said. "Otherwise, we are going to be imaging a lot of patients."

After Stone and the advisory committee discussed the inaccuracies of clinicians eyeballing their lesions, several panelists said they felt more comfortable recommending imaging even for lesions up to 3.0 mm, just to be sure operators weren't using BVS in higher-risk patients.

Even so, "intravascular ultrasound [IVUS] use was never robust even in its heyday. It's used less than 10% of the time in some surveys. While we might recommend the use of IVUS to optimize these procedures, it's just not going to happen," warned panelist , of University of New Mexico School of Medicine in Albuquerque.

One thing the panelists did agree on was the need for an attitude change among operators with regard to imaging.

"Admonish interventionalists: Don't be cavalier about sizing vessels," said Somberg. He feared, however, that "there will still be outliers that will never use quantitative measurements even if you send them to the attorney general."

The vote came out 9-1 that the Absorb BVS has "reasonable safety" and 10-0 that it is effective.

Laskey was the only panelist to vote no for the safety of the device, reasoning that while the composite endpoint of the ABSORB III trial produced no significant differences between BVS and DES, point estimates for individual components all went "in the wrong direction," against BVS.

"Perhaps things aren't as safe as they seem to be. I can't blame everything on the small vessels," he said. These reservations "still rattle around, though they may go away with the test of time."

The chair of the committee, , of the University of Wisconsin School of Medicine & Public Health in Madison, said he would have voted yes if he was required to be tie-breaker. He said that "people have been talking about this for at least 2 decades" -- and went insofar as to call the BVS "transformative" and "the holy grail."

Pending the FDA's final approval decision, what happens next for Absorb -- and whether it achieves wider adoption -- will also depend on its performance in ABSORB IV and other studies. Somberg suggested that investigators follow-up on patients continuing dual antiplatelet therapy beyond 1 year and those who terminate prematurely.

To that list of data that are needed, committee member Richard A. Lange, MD, MBA, of University of Texas in San Antonio, added expanded populations in acute myocardial infarction, ostial lesions, left main, and chronic total occlusions.

Lange ultimately told 麻豆传媒 after the vote that he was not surprised by the near unanimous decision.

"I thought the results were pretty compelling -- and as is the case with most technologies, they'll improve," he concluded.

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