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Thrombectomy devices making a major impact on the acute ischemic stroke market


By Larry Haimovitch

Medical Device Daily Contributing Writer

March 3, 2016

LOS ANGELES —This year marks the 20th anniversary of the FDA’s approval of the clot buster tPA. This approval ushered in an era of hope for acute ischemic stroke (AIS) patients, with the first proven therapy to lyse a clot in the brain, restore blood flow and mitigate or avoid the potentially devastating impact of an AIS.

While tPA has positively impacted the lives of many people in the past two decades, its benefit has been severely curtailed by its limited “therapeutic time window of opportunity”. It is widely estimated that tPA is used in only about 5% of the roughly 700,000 domestic annual domestic acute ischemic strokes.  

At this year’s International Stroke Conference, held here last week, the soaring cost of tPA was cited in a paper delivered by Dawn Kleindorfer, MD, University of Cincinnati. Dr. Kleindorfer noted that while tPA’s cost has jumped 111% in the past decade, the hospital reimbursement has been raised only 8% in that same time period, causing financial pain to hospitals and possibly impacting the care of AIS patients.

“This should be a call to action for healthcare professionals to lobby CMS to better adjust for these higher cost medications . . .” she said. Responding to a question during a press conference, Dr. Kleindorfer noted that it was not possible to gauge what impact this price increase was having on AIS therapy choices but voiced concern at the financial impact on hospital budgets.

Catheter-based mechanical thrombectomy devices, which were initially introduced about a decade ago, experienced a rocky start with three trials reported in 2013 showing disappointing outcomes. However, the tide has dramatically turned in the past year plus, as several key trials have clearly established an overwhelming benefit of combining tPA with a thrombectomy device.

These trials and their main country affiliations include MR CLEAN (Netherlands), ESCAPE (Canada), SWIFT PRIME (U.S. & Europe), EXTEND-IA (Australia) and REVASCAT (Spain). Data from these trials was published during 2014 in the prestigious New England Journal of Medicine (NEJM). The studies were so positive that they were cut short for ethical reasons, meaning the investigators could no longer justify randomizing patients into the control group.

These trials all used a variety of imaging modalities and combinations of treatment approaches with all but one mandating the use of intravenous tPA before the initiation of endovascular therapy. All five trials provided strong evidence to support the use of thrombectomy that is initiated within six hours of stroke onset.  Importantly, the time window to successfully use tPA, typically 4.5 hours or less, is significantly extended with thrombectomy.

A pooled meta-analysis of four of these trials, which included 787 patients was presented here and also published online in the American Heart Association (Dallas) journal Stroke. These data were derived from the  NEJM articles and used the Medtronic Inc. (Minneapolis) Solitaire stent retriever. It showed very convincing evidence that mechanical thrombectomy, in combination with tPA, significantly improves functional outcomes and reduced mortality, even amongst patients 80 years or older.

Another less prominent AIS thrombectomy trial, which was reported here, has also shown favorable results, This UK-based trial, dubbed PISTE, was stopped early after just 65 patients had been enrolled because of the outstanding results reported from the other endovascular studies.

At an evening symposium held here, Anne Alexandrov, a professor at the University of Tennessee Health Science Center (Nashville) noted that there are several factors that have caused the more recent mechanical thrombectomy trials to provide superior results. These include: (1) better trial design; (2) faster time to treatment; (3) careful patient selection derived from better imaging information; (4) new and superior thrombectomy devices.

With regard to faster time to intervention, Alexandrov noted that there is a strong correlation between time to treatment and a favorable outcome. Specifically, in the MR CLEAN trial, on average patients were treated in 280 minutes and 33% of the patients had a good outcome. Conversely, in the ESCAPE trial, patients were treated in 210 minutes and 71% experienced sginficant benefit.

The upshot of these improvements, she said, is that “patients are two to four times more likely” to enjoy reduced or no disability post an acute ischemic stroke. In addition, there was a statistically significant reduction in mortality seen in patients in all these trials.

Although celebrating the tremendous progress in AIS clinical outcomes, Alexandrov said that there is till plenty of room for improvement. “Forty percent of our AIS patients do not achieve a good outcome . . . we need to do better than that.”

As a result of the tremendous results seen in these trials, in mid-2015 the American Stroke Association (Dallas) published updated guidelines, recommending the use of a stent retriever in conjunction with tPA medication as a first-line treatment for ischemic stroke patients deemed eligible following a CT scan.

These guidelines note that the optimal initial treatment for an ischemic stroke remains intravenous delivery of tPA but acknowledge that “some people will benefit from additional treatment with a stent retrieval device if a clot continues to obstruct one of the big vessels after tPA is given.”

At a Medtronic hosted analysts’ meeting in San Francisco last October, the global market for mechanical thrombectomy devices was estimated at approximately $250 million. It is expected to grow 23% per year, reaching $700 million by 2020. The U.S. market, currently estimated at $100 million, is forecasted to surge 32% per year, reaching $400 million by 2020.

MDD believes that there are about 15,000 to 20,000 mechanical thrombectomy procedures performed annually in the U.S. The total available market opportunity is thought to be somewhere between 150,000 and 200,000 procedures per year. Thus, the AIS opportunity is only about 10% penetrated, which supports the thesis that this market can and will grow at a feverish pace in the next several years.

Three public companies are prominent players in the overall neurovascular market. This market includes the larger revenue hemorrhagic stroke and the smaller acute ischemic. According Larry Biegelsen of Wells Fargo Securities (New York), Medtronic and Stryker Corp. (Kalamazoo, Michigan) are the worldwide co-market leaders, with each company generating approximately $550 to $600 million in annual neurovascular revenue. Both companies have grown impressively in recent years, fueled by a combination of internal growth and active acquisition programs.

Another major contender is newly-minted public company Penumbra Inc. (Alameda, California), which has registered stellar growth since its founding in 2004. Led by its highly successful line of Penumbra system clot aspiration catheters, approximately $135 to $140 million or about 80% of its global revenue is derived from its neurovascular activities

As a footnote, Penumbra has conducted its own clinical trial, dubbed THERAPY, which randomized patients to the Penumbra system and tPA versus tPA alone. The trial was halted in late-2014 after the positive results from MR CLEAN made it unethical to continue. The trial was quite successful, in particular showing excellent mortality benefits. The data, which was presented in April 2015 at the European Stroke Organization Conference, is expected to be published soon in a peer-reviewed article.

2016 International Stroke Conference

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