"First-In-Man" Study Demonstrates Safety Of Polymer-Free Drug-Eluting Stents
Now MIV Therapeutics Inc. (Atlanta, Ga.) has demonstrated the safety of a revolutionary new type of drug-eluting vascular stent that uses materials found naturally in the human body, and does not employ polymers. Conducted in Brazil, a "first-in-man" study showed that MIV's VESTAsync™ stents performed as well or better than commercially available drug stent combinations, while using 60% less drug. Current concern with commercially available drug stent combinations is largely with the poor safety profile, MIV's study demonstrated potential for a better safety profile.
In the Brazilian study, conducted by Alexandré Abizaid, M.D., Ph.D. at Institute Dante Pazzanese of Cardiology in Sao Paolo, investigators implanted stents in fifteen patients and measured the extent of restenosis at four and nine months using two independent measures. The two time points are chosen to allow for healing (four months) and subsequent inflammatory or cell-proliferative responses (nine months).
The two methods used by Dr. Abizaid were intravascular ultrasound, an imaging technique for blood vessels similar to ultrasound in other parts of the body, and quantitative coronary angiography, which uses a radioactive tracer injected into the heart to detect blockages through an X-ray camera positioned outside the body.
Researchers measured "volumetric obstruction" with the ultrasound, and "late-lumen loss" with the angiography. Volumetric obstruction relates to the percentage of the stent volume that has filled, while lumen loss measures the reduction, in millimeters, of the free path through the stent area at its narrowest.
Researchers found no statistically significant narrowing of blood vessels inside the VESTASync stent at nine months compared to the results of these patients at four months. Both volumetric obstruction and late lumen loss were comparable with restenosis measures for conventional drug-eluting stents. Significantly, investigators found no evidence of "incomplete stent apposition" (a measure of incomplete attachment of the stent to the blood vessel), no stent-related thrombosis (blood clot), and no major adverse coronary events over the study period.
Dr. Costa, who presented the data at the annual meeting of the American College of Cardiology on Sunday, March 30, 2008, commented, "Our nine month data are very encouraging and reaffirm our positive findings at four months. What is remarkable is these results were obtained with 60% less drug delivered from an ultra-thin 0.6 micron coating that is entirely polymer-free."
Each year more than half a million Americans receive vascular stents mechanical devices that prop open clogged coronary arteries. For the last several years the majority of stents implanted in humans contained a drug that prevents restenosis by inhibiting inflammatory responses and the proliferation of cells near the implant site. These responses are believed to occur because the implantation procedure traumatizes the blood vessel somewhat, and the materials used in the implant are recognized by the body as "foreign." Compared with bare metal stents, drug-eluting stents reduce restenosis by 50 to 70%. Still, restenosis occurs in 5 to 10% of patients receiving them, which is acceptable; however, the safety profile of the product that produces the improved results is unacceptable. MIV aims to improve the safety profile with its drug-eluting stent.
Conventional stents are made of metals, such as stainless steel. Drug-eluting versions are coated with a polymer that contains the drug. Over time, some of the polymer dissolves and releases the drug and part of the polymer remains permanent.
MIV has taken an entirely new approach to the manufacture of vascular stents. Instead of coating the metal with polymers, the company coats the metal with hydroxyapatite and loads the hydroxyapatite with the drug. Hydroxyapatite is one of the building blocks of bones and teeth. "The human body treats hydroxyapatite as part of itself," notes MIV President and Chief Executive Officer, Dr. Mark Landy, "rather than as a foreign material." Because hydroxyapatite is porous, it can also serve as a reservoir for the drug, which in this case is the sirolimus, a drug which is also used to combat organ rejection in transplant patients. Based on these results, MIV is planning additional studies to verify these exciting nine month results found in this study.
For more information, log on to http://www.mivtherapeutics.com
MIV Therapeutics, Inc.
http://www.mivtherapeutics.com
"Primul-In-Man" Studiu demonstreazã siguranþã a polimerilor-medicament liber-Eluting Stents - "First-In-Man" Study Demonstrates Safety Of Polymer-Free Drug-Eluting Stents - articole medicale engleza - startsanatate