November 21, 2011 — Micell Technologies Inc. announced the release of preliminary data from the first-in-human clinical study of the MiStent Sirolimus Drug Eluting Coronary Stent System (MiStent DES). The device is a thin-strut drug-eluting stent distinguished by a rapid-absorbing drug/polymer coating designed for controlled drug release. Four-, six- and eight-month data from the DESSOLVE I trial were presented at the Transcatheter Cardiovascular Therapeutics Conference (TCT 2011) by John Ormiston, M.D., Mercy Angiography Unit, Auckland, New Zealand, a principal investigator in the study.
"These preliminary study results demonstrated excellent performance by the MiStent DES at up to eight months post-procedure — when patients typically experience the greatest increase in neointimal hyperplasia," said Ormiston. "MiStent DES is intended to provide enhanced patient safety and outcome by eliminating long-term exposure to DES non-erodible polymers. In addition to delivering clinical performance, MiStent DES may also enable physicians to pursue shorter duration dual antiplatelet therapy, and offer a safer choice to their non-compliant patients or patients who may be undergoing additional surgical procedures."
Thirty patients were treated with the MiStent DES with independent subgroups of 10 patients assigned to a four-month, six-month or eight-month follow-up. The primary efficacy endpoint was in-stent late lumen loss (LLL). Safety was assessed by incidence of major adverse cardiac events (MACE) and presence of tissue coverage within the treated artery at each time point.
Angiography, intravascular ultrasound (IVUS) and optical coherence tomography (OCT) imaging results were measured by independent core laboratories. Preliminary analysis of the data demonstrated a very low median in-stent LLL of 0.03 mm at four months, 0.10 mm at six months and 0.08 mm at eight months follow-up, with no binary restenosis or revascularizations.
The mean in-stent LLL values at four, six and eight months were 0.01, 0.21 and 0.09 mm, respectively. The mean and median values were comparable except at the six-month time point, in which one patient experienced a high late loss value due to treatment of a highly calcified lesion and under-expansion of the stent. When data from this patient is excluded, the six month mean LLL is 0.10 mm. The median percent of stent struts covered by tissue was 96 percent at eight months, 97 percent at six months and 90 percent at four months per OCT analysis. IVUS confirmed good inhibition of neointimal hyperplasia.
A MACE rate of 6.7 percent, including two non-Q wave myocardial infarctions (MI), one periprocedural and one non-target vessel MI, was reported through eight months follow-up.
"The MiStent DES was designed to address a need for improved patient safety while providing equivalent or better efficacy as compared to currently available drug eluting stents," observed Dennis Donohoe, M.D., chief medical advisor to Micell. "The excellent clinical outcomes of the DESSOLVE I trial demonstrate the value of the MiStent design in enabling elimination of drug and polymer from the stent in 45 to 60 days and providing patients the best of DES and BMS in one solution."
The DESSOLVE I trial was the first clinical assessment of safety and efficacy of the MiStent DES. It treated 30 patients with de novo lesions in coronary arteries ranging in diameter from 2.5 to 3.5 mm and amenable to treatment with a maximum 23 mm length stent. Subjects were enrolled across five study centers in New Zealand, Australia and Belgium. Three independent subgroups of 10 patients each were evaluated using angiography, IVUS and OCT at three time points: four, six and eight months. The primary efficacy endpoint was in-stent late lumen loss. Safety was assessed by incidence of major adverse cardiac events (MACE) and presence of strut coverage with tissue within the treated artery at each time point.
William Wijns, M.D., Cardiovascular Center, Aalst, Belgium and John Ormiston, M.D., Mercy Angiography Unit, Auckland, NZ are co-principal investigators for this trial.
The DESSOLVE II CE Mark trial is a multi-center study of patients with documented stable or unstable angina pectoris. The primary endpoint is superiority of the MiStent DES in minimizing in-stent late lumen loss at nine months, compared to Medtronic's Endeavor Sprint DES. The endpoint is measured by the angiography core laboratory in de novo coronary lesions in vessels ranging in diameter from 2.5 to 3.5 mm and amenable to treatment with a maximum 30 mm length stent. The DESSOLVE II study completed enrollment of 183 patients in July 2011.
The MiStent Sirolimus-Eluting Coronary Stent System is designed to optimize healing in patients with coronary artery disease. The rapid-absorbing drug/polymer coating is intended to precisely and consistently control drug elution and polymer exposure duration. This reduces the safety risks associated with current commercially available DES technologies.
The system includes a proprietary stent coating that contains crystalline drug (sirolimus) and an absorbable polymer. As the polymer softens and disperses from the stent into the adjacent tissue, the coating provides controlled and sustained release of therapeutic levels of drug within the surrounding tissue. Results of animal studies have determined the drug/polymer coating is cleared from the stent in 45 to 60 days leaving a bare metal stent; the polymer is completely absorbed into the surrounding tissue in 90 days to promote long-term patency and compatibility with the artery.
Using an approved drug (sirolimus) and polymer (PLGA), the patented supercritical fluid technology allows a rigorously controlled drug/polymer coating to be applied to a bare metal stent (BMS). The device leverages the benefits of Eurocor's (CE Marked) Genius Magic Cobalt Chromium Coronary Stent System. It is a state-of-the-art BMS, which has demonstrated excellent deliverability, conformability and flexibility.
The MiStent system is an investigational device currently being evaluated in international clinical studies and is not yet approved or available for sale in any market.
For more information: www.micell.com