News from the FDA/CDC

FDA panel: Continue using paclitaxel-eluting PAD devices, with caveats


 

REPORTING FROM AN FDA PANEL MEETING


Finally, the industry data used to create the meta-analysis were considered to be fundamentally flawed: in blinding, in the relatively small numbers of patients, and in the large percentage of patients lost to follow-up. The latter could have dramatically influenced the perceived results, especially as the studies were not powered or designed to follow mortality over such a period of time, according to the panel.

These limitations to the signal were especially important to the panel because of the obvious benefits with regard to quality of life provided to patients from these devices, which were attested to during the 2-day meeting by numerous presenters from industry, medical organizations – including societies and nonprofits – and providers.

In responding to FDA requests on a variety of concerns, the panel reiterated that there was a credible mortality signal, but that they could not be confident about the magnitude and whether it was caused by the paclitaxel treatment or some factor in the design or conduct of the studies. In addition, the panel members felt that they could neither confirm nor eliminate a class effect, given the fact that the information was based on a meta-analysis and thus none of the included devices could safely be removed from consideration.

They suggested that further safety information should be obtained, potentially by assessing and perhaps altering data collection in 29 ongoing studies over the next 5 years or so in more than 10,000 patients.

In addition, several of the panel members felt that additional animal studies might be performed including the use of older rat models; and using animal models that mimicked the kind of comorbidities present in the treated population, such as diabetes and atherosclerosis. They suggested cross-company industry cooperation with the FDA on these models, including looking at drug interactions and mimicking the dose application of stents/balloons.

Both the FDA representative and the panel were especially concerned with the benefit/risk profile.

The recommendation to still market the devices with a label warning was warranted, according to many members of the panel. They pointed to the clear benefits in quality of life and the lowered need for revascularization despite the evidence of the mortality signal, which, while statistically significant, could not be pinned town with regard to mechanisms or specific causes of death.

Overall, there was a concern that there should be a dialogue between patients and their doctors to discuss clear short-term benefits with unknown long-term risk, and that the label should support this by clearly mentioning the mortality signal that was found, although there was no attempt to develop exact wording.

Panel member Joaquin E. Cigarroa, MD, head of cardiovascular medicine at Oregon Health & Science University, Portland, suggested with regard to labeling that a statement “that ‘there may be’ – not ‘there is’ – a late mortality signal, should be included.”

Panel member John C. Somberg, MD, program director of clinical research and bioinformatics at Rush University in Lake Bluff, Ill., stated: “The label should say something like, ‘when looking at a meta-analysis that combined all studies with stents and balloons that carried paclitaxel, there may be a late mortality, which must be balanced against an early and sustained benefit in terms of pain on walking and potential loss of circulation to your extremity.’ ”

Other panel members thought that the meta-analysis should not be privileged and that somehow the totality of the evidence should somehow be distilled down into the label, including the evidence against the signal.

“We’re meeting because of a signal, of a concern – an honest, well-meaning concern – of increased mortality. And my opinion is that the patients need to be informed of it,” said Dr. Lange, president, Texas Tech University, El Paso.

Some members of the panel felt that it may not be justifiable to use these devices in patients with low intrinsic risk and low recurrence risk, and the whole spectrum of patients may need to be considered in further studies to figure out the subgroups that have more benefits and more risks, and also to consider how to mitigate risks in patients who receive the device, whether through medical therapy or lifestyle modification.

In particular, Frank W. LoGerfo, MD, the William V. McDermott Distinguished Professor of Surgery at Harvard Medical School, Boston, stated: “Interventions for claudication should be extremely rare. It rarely progresses, and the pain should be worked through by exercise with low risk of limb loss.” He added that intervention with these devices “takes away options. Trading life for something that is not limb-threatening is something we should not be considering.”

There was no firm consensus on whether new randomized trials should be done, although they were of course the ideal solution. Kevin E. Kip, PhD, Distinguished USF Health Professor at the University of South Florida, Tampa, and others argued that, whether new trials were necessary or not, to deal with the safety question in a timely fashion, existing trials have to capture as much of the missing data as possible, and carry out follow-up out further.

FDA representative Bram Zuckerman, MD, director of the Office of Cardiovascular Devices at the Center for Devices and Radiological Health, indicated that those things might not be easily be accomplished due to regulatory constraints and the financial costs, and that to do so there would be need for community effort among stakeholders, including collaborative efforts with existing prospective registries such as that run by the Vascular Quality Initiative.

One overall conclusion by both the FDA and panel members was that the quality of these and other such studies going forward must improve, by standardizing definitions and data forms to make studies more uniform across the industry. They reemphasized the need to work with the registries to get common data included, and to incorporate of insurance provider and Social Security death data as much as possible to help alleviate the lost follow-up problem.

SOURCE: Webcasts of the complete 2 days of the FDA panel meeting are available online.

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