It is unusual for medical devices that fail their US pivotal trial to gain FDA approval, but it is not unheard of. Next week Claret Medical will get a sense of whether it might succeed in its attempt to get its Sentinel embolic protection device cleared for sale, when a panel will vote on its approvability despite disappointing clinical data.
Claret needs a yes. The Sentinel is its only project, and though the device is CE marked and on sale in Europe the nod from the FDA will be necessary if it is to find an acquirer, surely the goal of management and the company’s venture backers.
The Sentinel sounds like it ought to work. The sieve-like device is threaded through the veins to the brachiocephalic and the left common carotid arteries – the vessels leading from the heart to the brain – and left in place while a transcatheter aortic valve is implanted in the heart. The idea is that it filters the blood, catching cellular debris released during the valve implantation procedure that might otherwise travel to the brain and cause a stroke.
As far as debris catching goes, it works like a charm. In the pivotal trial the Sentinel’s filters caught histopathologic matter including thrombus, calcification, valve tissue, artery wall and foreign material in 99% of patients.
The trouble was, this did not make a difference to the stroke rate. Use of the filter did not reduce the median new lesion volume, the primary efficacy endpoint.
Not the end
This does not rule out a positive vote from the circulatory system devices panel on February 23, or indeed a favourable verdict from the FDA itself. Both are more concerned with safety than with efficacy, and the device did hit the primary safety endpoint in the trial, with a 30-day rate of major adverse cardiac and cerebrovascular events significantly lower than the prespecified goal.
Moreover, the Sentinel is a low-risk product, as shown by its approval application via the de novo 510(k) pathway, rather than via premarket approval.
And the agency has form for approving devices more in hope than expectation. The Amplatzer PFO Occluder made by St. Jude Medical (now part of Abbott), a catheter-mounted device for closing holes in the heart, squeaked through a panel and won approval despite a pivotal miss (Heart plug approval a minor win for St. Jude, October 31, 2016).
While the panel’s backing would be good and clearance for sale even better, they still might not be enough for Claret. A buyer for the company will only step in if it is clear that the Sentinel will find a market, and it is far from certain that doctors will use – and payers will fund – a device on the off-chance that it does some good.