Medtronic ($MDT) announced promising results from the first-in-human implants of its investigational drug-filled stent at the TCT conference in San Francisco.
Optical coherence tomography imaging found that the stent achieved 90% strut coverage (new cell growth over stent struts) on average at one month and had a malapposed strut rate of 2% across 6 patients. Within one month of the procedure the rate of malposition fell by 50%, Medtronic said in a release.
As suggested by its the name, the device's drug delivery mechanism is distinct from previous drug-eluting stents. Sirolimus is coated on the inside of the stent and released through laser-drilled holes on the outer surface of the stent so that the drug comes into contact with the vessel's inner wall. Medtronic says the controlled and sustained releases helps the patient avoid undesirable responses to foreign agent, such as chronic inflammation.
Bioresorbable drug-eluting stents attempt to limit the vessel's exposure to polymer by being absorbed by the body in the months following implantation. While the drug-filled stent is not bioresorbable, it goes a step further by eliminating polymer use altogether. Another advantage of the approach is that because the drug is coated on the inside of the stent, it is protected from the stent's surrounding environment, which reduces concerns about its durability during tracking, according to a release.
"The novel DFS truly represents an innovative stent platform with advanced stent manufacturing to optimize clinical performance without the need of a polymer," said co-principal investigator Stephen Worthley, who implanted the drug-filled stent at the Royal Adelaide Hospital in Australia, in a statement. "These patients implanted with the DFS have shown very promising early outcomes of strut coverage and healing that indicate the new platform may provide many clinical benefits, including shorter DAPT (dual antiplatelet drug therapy) duration, and we look forward to evaluating how well the stent continues to perform throughout the trial."
Medtronic is recruiting additional trial patients at 9 centers in Australia, according to ClinicalTrials.Gov. The 100-person trial commenced in June, and is scheduled to conclude in February 2021. Medtronic said in the release that the trial is also underway in Brazil. The trial's primary outcome is late lumen loss at 9 months.
Bioresorbable stents like Abbott's Absorb BVS have demonstrated late lumen gain, meaning the size of the coronary artery increased in the months following surgery. The drug-filled stent is not bioresorbable, meaning its metallic body remains in the coronary artery following drug elution.
In addition, Boston Scientific ($BSX) recently boasted that its partially bioresorbable stent reduces exposure to polymers thanks to the bioresorbable coating of its just-approved Synergy stent, which became the first device in that category to earn the FDA's blessing.
Medtronic's approach is an alternative means to achieving the goal of less bodily exposure to polymer. While its device forgoes some of the advantages of bioresorbable stents (like the return of the vessel to its original, prediseased state (normal vasomotion) and the ability to conduct reinterventions uninhibited by the presence of permanent stent), the drug-filled stent avoids doubts about the durability of bioresorbable stents. Instead the investigational stent borrows much of its platform and technology from Medtronic's Resolute drug-eluting stent franchise.
Meanwhile, Abbott ($ABT) just gave an update on trials of its fully absorbable bioresorbable Absorb BVS stent at TCT. The device has a CE mark and FDA approval is expected next year. GlobalData projects the BVS is to hit sales of $96.3 million by 2017 in the U.S. once commercialization commences. India is its largest market right now, accounting for slightly more than a third of its $132 million in 2014 global revenues.
In a sign of fierce competition ahead in the next-gen stent market, a Medtronic spokeswoman emailed FierceMedicalDevices an advance copy of an editorial in the New England Journal of Medicine, which concludes that "although the concept of self-degrading stents is intuitively attractive, promise alone is not enough to make us unconditionally embrace this technology. For the moment, the trends toward higher event rates with the Absorb scaffold and the additional challenges associated with implantation must be considered."
|Sahajanand Medical Technology's Supraflex stent--Courtesy of Sahajanand|
Regardless, Medtronic needs to keep innovating in the stent arena to compete with competitors on the high and low end. In fact, the use of lasers in stent manufacturing was pioneered by companies in India's diamond cutting district in Surat, Gujurat. Companies like Sahajanand Medical Technologies have begun exporting their stents to Europe.
Though the Indian companies' stents aren't as novel as the drug-filled stent, or as proven as, say, Medtronic's Resolute franchise, they are considerably cheaper, making it all the more important for the device bigwig to constantly differentiate itself through innovation.
- read the release