Pimecrolimus and dual pimecrolimus-paclitaxel eluting stents decrease neointimal proliferation in a porcine model.

OBJECTIVES AND BACKGROUND: The purpose of this study was to determine the effectiveness and vascular response of a pimecrolimus drug eluting stent and a combination (pimecrolimus + paclitaxel) stent as compared with bare metal controls in the porcine coronary model. METHODS AND RESULTS: In the first phase of the study, cobalt chromium stents were loaded with an erodible polymer and either a slow release or a fast release formulation of pimecrolimus. Thirty stents (metal, n = 10; pimecrolimus slow, n = 10; pimecrolimus fast, n = 10) were implanted in the coronary arteries of 10 pigs. At 30 days, neointimal proliferation and inflammation were both significantly less in the pimecrolimus fast release group as compared with the bare metal controls. Endothelialization was complete and equal in all three groups of stents. In the second phase of the study, stents were loaded with an erodible polymer with alternating reservoirs of paclitaxel and pimecrolimus. Twenty stents (8 control stents and 12 dual stents) were implanted in the coronary arteries of seven pigs. At 30 days, neointimal proliferation was significantly less in the dual drug group as compared with the bare metal controls. Endothelialization was complete in both groups of stents, suggesting complete healing of the arteries. CONCLUSIONS: In a 30-day porcine stent model, pimecrolimus inhibits neointimal proliferation as compared with bare metal stents. Also, the proof of concept of a dual drug eluting stent was established showing both safety and efficacy.

Cobalt chromium stent with antiproliferative for restenosis trial in India (COSTAR I).

BACKGROUND: The CoStar stent is a novel cobalt chromium stent designed specifically for drug delivery. The COSTAR I trial represents the first-in-man study of the CoStar Paclitaxel-Eluting Coronary Stent System evaluating three dose release formulations of paclitaxel in a bioresorbable polymer matrix in the treatment of de novo coronary lesions. METHODS: The COSTAR I Trial was a prospective, multi-center registry enrolling 87 patients in four Indian centers for treatment of up to two de novo lesions = 25 mm in length in a reference vessel 2.5-3.5 mm in diameter. Three dose release formulations were studied: 30 microg eluted over 10 days bidirectionally (Group 1, n =10), 10 microg eluted over 30 days abluminally (Group 2, n=40) and 3 microg eluted over 30 days abluminally (Group 3, n = 37). RESULTS: Demographics and lesion characteristics were similar between the groups and treatment in all three groups included small caliber vessels (RVD 2.45 +/- 0.30 - 2.57 +/- 0.36 mm). The primary endpoint of in-stent late loss at four months was lowest in Group 2 (0.43 +/- 0.43 mm) compared to Group 1 and Group 3 (0.51 +/- 7 mn; 0.74 mm and 1.07 +/- 0.65 mm respectively). In-segment late loss followed similar trends, being lowest in Group 2 (0.24 +/- 0.39 mm) compared to Groups 1 and 3 (0.52 +/- 0.66 mm and 0.76 +/- 0.57 mm respectively). Group 2 demonstrated better angiographic out-comes at 12 months with in-stent late loss of 0.55 +/- 0.38 mm when compared to Groups 1 and 3 (0.90 +/- 0.76 mm and 0.74 +/- 0.55 mm respectively). Cumulative binary restenosis rates at twelve months were 1.9%, 35.7% and 39.1% in Groups 2, 1 and 3 respectively. Clinical outcomes trended similarly with cumulative MACE rates at twelve months being lowest at 7.5% in Group 2 as compared to 20% in Group 1 and 21.6% in Group 3 respectively. CONCLUSIONS: In this first-in-man feasibility trial, angiographic and clinical results seen with the extended release formulation at a higher dose (10 microg/30 days) demonstrate the feasibility of the CoStar stent platform in the treatment of native coronary lesions. It also demonstrates the importance of drug dose and release kinetics.

The effect of variable dose and release kinetics on neointimal hyperplasia using a novel paclitaxel-eluting stent platform: the Paclitaxel In-Stent Controlled Elution Study (PISCES).

OBJECTIVES: The aim of this study was to evaluate the effect of variable dose and release kinetics of paclitaxel on neointimal hyperplasia. BACKGROUND: Conventional paclitaxel-eluting stents use a durable polymer coating as a vehicle for drug delivery. The Conor stent (Conor Medsystems, Menlo Park, California) with intra-strut wells and erodable polymer is specifically designed for drug delivery with programmable pharmacokinetics. METHODS: Two hundred and forty-four patients with single vessel disease received either a bare metal Conor stent (n = 53) or one of six different release formulations that varied in dose (10 or 30 microg) and elution release kinetics (first order, zero order), direction (abluminal, luminal), and duration (5, 10, and 30 days). End points at six months (bare stent group) and at four months (eluting stent groups) were angiographic late loss and neointimal tissue volume by intravascular ultrasound and the rate of major adverse cardiac events (MACE). RESULTS: The lowest in-stent late loss (0.38 mm, p <0.01, and 0.30 mm, p <0.01) and volume obstruction (8%, p <0.01, and 5%, p <0.01) were observed with the 10-microg and 30-microg doses in the 30-day release groups respectively, whereas the highest in-stent late loss (0.88 mm), volume obstruction (26%), and restenosis rate (11.6%) were observed in the bare stent group. The overall MACE rate of the eluting stent group was 8.6%: death 0.5%, myocardial infarction 2.7%, and target lesion revascularization (TLR) 5.3%. Sub-acute thrombosis was 0.5%. The TLR rates in the two 30-day release groups were 0% and 3.4%. CONCLUSIONS: This novel eluting stent platform, using an erodable polymer with complete elution of low doses of paclitaxel, is safe. The inhibition of the in-stent neointimal hyperplasia was best in the long release groups.

One-year clinical outcome of various doses and pharmacokinetic release formulations of paclitaxel eluted from an erodable polymer - Insight in the Paclitaxel In-Stent Controlled Elution Study (PISCES).

AIMS: The one year clinical benefit of various doses and release durations of paclitaxel eluted from an erodable polymer has not been evaluated so far. METHODS AND RESULTS: Conor paclitaxel-eluting stents have intra-stent wells in which drug and polymer are deposited. Stents with six different release formulations (dose: 10 microg or 30 microg, duration: 5, 10 or 30 days, direction: mural or bidirectional) were implanted in 6 patient cohorts. Clinical follow-up was conducted at 4 and 12 months. Quantitative angiography and IVUS were performed at 4 months, and additional angiographic and IVUS follow-up were performed for groups D5 (10microg/30days/mural) and D6 (30microg/30days/mural), as they had shown the most favorable results at 4 months. At one year, the lowest major adverse cardiac event rates were observed in the slow release (30 day) group (5.1% in D5 and 6.9% in D6). One-year in-stent late loss was 0.52+/-0.34 mm in D5 and 0.36+/-0.50mm in D6 (p=0.20) while neointimal area was 0.99+/-0.54 mm2 in D5 and 0.77+/-0.92 mm2 in D6 (p=0.42). Corresponding in-stent binary restenosis at one year was 0% and 5.6% respectively (p=0.36). CONCLUSIONS: Patients who received the slow release formulation stent had better clinical outcome at one year than those who received the fast release formulation. However, the effect on neointimal suppression requires investigation in a larger population to determine whether the high dose formulation confers an additional clinical benefit.

The effect of variable release kinetics on Paclitaxel efficacy from a drug eluting stent in a porcine model.

AIMS: Paclitaxel is a potent and effective inhibitor of neointimal proliferation after coronary stenting. The Conor stent loaded with Paclitaxel can be programmed with multi-parameter matrix of dose, temporal release profiles and release pathways. The aim of this study was to determine the most efficacious dose and release pattern of Paclitaxel in a porcine model and parallels the PISCES trial. METHODS: 32 farm pigs were implanted with Conor stents loaded with 10 or 30 microg of Paclitaxel with, 10 or 30 day and mural or bidirectional release patterns. Angiographic and histomorphometric analysis was -performed at 30 and 90 days. RESULTS: All doses of Paclitaxel were angiographically superior to control (P < 0.01). At 30 days, intimal thickness was similar between Pisces D4 (30 microg/10 days, bidirectional release), D5 (10 microg/30 day mural) and D6 (30 microg/30 day, mural) with D4 having the lowest intimal thickness (167+/-59 microm). There was a significant increase in the mural injury associated with D4 in comparison to all other doses (P < 0.00001). At 90 days D4 was significantly worse in comparison to Pisces D5 and D6; (P < 0.01) and Pisces D5 and D6 were similar to controls. CONCLUSIONS: 10 day release of Paclitaxel may be too short a period to inhibit neointimal proliferation after coronary stenting, or the rapid release of Paclitaxel may induce chemical injury causing secondary insult to the artery resulting in a rebound increase in intimal thickness at 90 days. These data parallel clinical findings in the PISCES trial.

Local drug delivery via a coronary stent with programmable release pharmacokinetics.

BACKGROUND: Fixed drug release kinetics and vessel wall partitioning may limit the effectiveness of drug-eluting stents. We report preliminary experience using a new coronary stent with programmable pharmacokinetics. METHODS AND RESULTS: A newly designed metallic stent contains honeycombed strut elements with inlaid stacked layers of drug and polymer. In vitro studies evaluated recipes for loading paclitaxel to establish the parameters for controlling drug release. Manipulation of the layers of biodegradable polymer and drug allowed varying of the initial 24-hour burst release of paclitaxel from 69% to 8.6% (P<0.0001). Late release of drug could be adjusted dependently or independently of early burst release. A biphasic release profile was created by the addition of blank layers of polymer within the stack. In the 30-day porcine coronary model (n=17 pigs), there was a 70% reduction in late loss (0.3+/-0.5 versus 1.0+/-0.5 mm, P=0.04), a 28% increase in luminal volume (132+/-12 versus 103+/-21 mm(3), P=0.02), and a 50% decrease in histological neointimal area (2.0+/-0.5 versus 4.0+/-1.6 mm(2); P<0.001) compared with bare metal controls. Temporal and regional variations in vascular healing were seen histologically. CONCLUSIONS: Layered polymer/drug inlay stent technology permits flexible and controllable pharmacokinetic profiles. Programmable, complex chemotherapy using this approach may be feasible for the treatment of cardiovascular disease.