Mumbai: Abbott today said that two-year data from 30 patients in its ABSORB clinical trial showed hat its bioabsorbable drug-eluting stent successfully treated coronary artery disease and was absorbed into the walls of treated arteries within two years, leaving behind blood vessels that appeared to move and function similar to unstented arteries.

According to Abbott, patients who received its bioabsorbable drug-eluting coronary stent and were followed out to two years experienced no stent thrombosis out to two years and no new major adverse cardiac events (MACE) between six months and two years. The company said these results confirmed its earlier positive one-year clinical results with its bioabsorbable drug-eluting stent. The results were presented today at the Cardiovascular Research Foundation's 20th annual Transcatheter Cardiovascular Therapeutics (TCT) scientific symposium.

"Now you see it, now you don't – for the first time, we have data in patients showing that Abbott's bioabsorbable drug eluting stent does its job treating diseased coronary arteries and that it is absorbed by two years," said John Ormiston, M.D., principal investigator in the ABSORB trial and medical director at Mercy Angiography in Auckland, New Zealand."Clinical safety and effectiveness were sustained at two years, and the previously stented portion of arteries demonstrated the ability to expand and contract in a manner similar to a vessel that has never been stented. These are very exciting results that represent a potential major breakthrough in the future treatment of patients with coronary artery disease."

Trends were observed in data from tests of artery movement and function, demonstrating a potential restoration of unstented artery movement to coronary blood vessels after the stent was absorbed – something that is not possible with permanent metal-based stent implants.

Abbott also will present groundbreaking intravascular ultrasound (IVUS) and optical computed tomography (OCT) imaging data on its bioabsorbable drug-eluting coronary stent platform this week at TCT in the "Best of Coronary Interventions Abstracts" session on Wednesday, 15 October 2008.

Abbott says the IVUS data will reveal a decrease in plaque area in treated arteries corresponding to a similar increase in blood flow area between six months and two years: 12.7 per cent decrease in plaque area (p=<0.001, n=17); 10.8 per cent increase in luminal area (p=0.03, n=17). OCT imaging data will show absorption of the stent into artery walls and that the blood vessel lining of arteries treated with Abbott's bioabsorbable stent looks more uniform after two years than it did immediately post-treatment.

"The imaging technology data from the ABSORB trial indicate that Abbott's bioabsorbable stent has the potential to restore vascular integrity and endothelial function to treated vessels after two years," said professor Patrick W. Serruys, M.D., Ph.D., professor of interventional cardiology at the Thoraxcentre, Erasmus University Hospital, Rotterdam, and co-principal investigator in the ABSORB trial. "With these ABSORB data, we have come full circle in interventional time, linking the past, when balloon angioplasty was used without stents, to the future, when disappearing stents may become the new standard of care for patients with coronary artery disease."

Abbott said it is the only company with long-term clinical data evaluating the safety and performance of a fully bioabsorbable drug-eluting coronary stent out to two years.
Its bioabsorbable everolimus-eluting coronary stent is made of polylactic acid, said to be used in medical implants such as dissolvable sutures. As with a metallic stent, Abbott's bioabsorbable stent is designed to restore blood flow by propping a clogged vessel open, and to provide support until the blood vessel heals. Unlike a metallic stent, however, a bioabsorbable stent is designed to be slowly metabolised by the body and completely absorbed over time.

"The early success of our bioabsorbable stent marks the dawn of the beginning of a new era in the history of interventional medical device treatment," said John M. Capek, Ph.D., executive vice president, Medical Devices, Abbott. "Today's data show that bioabsorbable stents have become more than just a wish for patients – they are now on their way to becoming a clinical reality."

Abbott will begin enrolling the next cohort of 80 patients into its international ABSORB clinical trial in the first half of 2009.

ABSORB Clinical Trial Results
Abbott's said two-year data from the first 30 patients enrolled in ABSORB clinical trial demonstrated a low (3.6 percent, n=28) MACE rate, which was consistent with results at one year (3.4 per cent, n=29) and before six-months (3.3 per cent, n=30). One patient had a minor heart attack due to lack of blood supply at six-months, another was electively lost to follow up at one year, and one patient died from a non-cardiac cause at two years. A zero percent stent thrombosis rate persisted for all patients across all time points in the ABSORB trial. Potential restoration of unstented artery movement to coronary blood vessels after the bioabsorbable stent was absorbed was revealed at two years with the drugs acetylcholine and nitroglycerin used in nine patients, showing vasodilation in the previously stented area, and methergine used in seven patients, showing vasoconstriction in the previously stented area.

About the ABSORB Clinical Trial
The ABSORB trial is a prospective, non-randomized (open label) study designed to enroll up to 110 patients in Belgium, Denmark, France, New Zealand, Poland and the Netherlands. Key endpoints of the study include assessments of safety – MACE (defined as any event that resulted in re-treatment of the treated artery, heart attack or cardiac death) and stent thrombosis (blood clot formation) rates – at 30, 180 and 270 days, with additional annual follow-up for up to five years, as well as an assessment of the acute performance of the bioabsorbable drug eluting stent. Other key endpoints of the study include successful deployment of the bioabsorbable drug eluting stent, follow-up measurements assessed by angiography, intravascular ultrasound (IVUS), and state-of-the-art imaging modalities at 180 days and two years.

Everolimus, developed by Novartis Pharma AG, is a proliferation signal inhibitor, or mTOR inhibitor, licensed to Abbott by Novartis for use on its drug eluting stents. Everolimus has been shown to inhibit in-stent neointimal growth in the coronary vessels following stent implantation, due to its anti-proliferative properties.