XTENT has announced positive six-month follow-up data from the CUSTOM II clinical trial, which assessed the safety and efficacy of the company's investigational Custom NX drug-eluting stent (DES) system for the treatment of long and multiple lesions in patients with coronary artery disease. Results were presented during the EuroPCR meeting in Barcelona.
The CUSTOM II single-arm prospective study evaluated the use of Custom NX in patients with long lesions, defined as greater than 20mm, and patients with two lesions. Of the 100 patients enrolled, 69 patients were enrolled in the long lesion arm, and 31 patients were enrolled in the two-lesion arm of the study.
Up to two customisable stent deployments of up to 60mm total length were evaluated in the study. The primary endpoint was Major Adverse Cardiac Events (MACE) at six months, with clinical follow-up at one, six and 12 months, then annually for five years. Angiographic and intravascular ultrasound (IVUS) follow-up was conducted at six months. The anticoagulation regimen was clopidogrel for a minimum of three months plus aspirin.
In the CUSTOM II patient population, the average vessel diameter was 2.57mm and the average lesion length was 28.7mm. Of the 100 patients enrolled in the trial, 26% were diabetic. The percentage of patients with ACC/AHA lesion grade B2 or C was 65.1%. This trial includes a high percentage of patients with complex lesions and one of the longest average lesion lengths studied of any DES clinical trial.
At six-month follow-up, the MACE rate was 9%. Early adverse events (in hospital) occurred in five patients, including four myocardial infarctions and one death. At six months, four additional patients (4%) underwent target lesion revascularisation. There have been only two other clinical studies with patient populations that approached the complexity of the patients enrolled in CUSTOM II, the multiple-stent cohort of the TAXUS V trial and the TAXUS VI trial. In comparison, at nine month follow up, the TAXUS V cohort the MACE rate was 20.4% and TAXUS VI had a MACE rate of 16.4%. CUSTOM II angiographic and IVUS results demonstrated in-stent late loss was 0.31mm; in-segment late loss was 0.22mm; binary restenosis rate was 7.5%; and the percentage of neointimal volume was 3.3%.
"These data are particularly encouraging considering CUSTOM II enrolled one of the most difficult-to-treat patient populations ever studied in a DES trial and also mirrored the complex disease profile physicians are most likely to see among patients presenting today with coronary artery disease," said Professor Eberhard Grube, Chief of Cardiology at the Helios Heart Center in Siegburg, Germany, and principal investigator of the CUSTOM II trial, who presented the data at EuroPCR. "Despite the complexity of patients treated, the Custom NX system allowed for very favourable results."
Custom NX Overview
The Custom NX 60 DES System is designed to enable physicians to treat one long lesion or multiple lesions by customising the length of stent placed at the treatment site. The system consists of ten, 6mm, drug-eluting stent segments, which allows the placement of up to 60mm of stent. XTENT's cobalt chromium stents are coated with Biolimus A9 and PLA, a biodegradable drug carrier.
The length of the balloon within the system is also customisable allowing for post dilatation following stent deployment. This modular system also allows for the placing of multiple stents from a single catheter. The Custom NX can be used for a wide variety of lesions, including long lesions, multiple lesions in a single vessel or multiple lesions in multiple vessels.
"XTENT technology was developed based on real world clinical demand," said Gregory D Casciaro, President and CEO of XTENT told Cardiovascular News. "Thinking ahead, it was clear that stents would be used in more complex diseases and in older patients with more co-morbidities."
CUSTOM Clinical Program
In addition to CUSTOM II, XTENT currently has several other ongoing trials:
Twelve month follow-up results from the CUSTOM I trial, XTENT's first in man study, have shown all 30 patients are alive and well and there was zero restenosis. The objective of the CUSTOM I trial is to demonstrate the safety of in situ stent-length customisation in 30 consecutive patients treated using the XTENT system to place custom-length stents coated with Biolimus A9 and a bioerodable polymer. The primary endpoint was Major Adverse Cardiac Events (MACE) at eight months, with clinical follow-up at one, four and eight months, then annually for five years. Angiographic and intravascular ultrasound (IVUS) follow-up was conducted at four months and eight months.
The CUSTOM III clinical trial is designed to evaluate in situ customisation for long lesions and multiple lesions using an expanded range of diameters of XTENT Custom NX DES Systems. Enrollment of 90 patients at 13 European centres began in September 2006 and is complete. Patients will be reassessed at 30 days, six months and 12 months.
XTENT expects to submit an IDE application to the FDA in 2007 for its planned US pivotal clinical trials, CUSTOM IV and CUSTOM V. The company anticipates that a total of up to approximately 2,500 patients will be necessary to support FDA approval.
The CUSTOM VI pivotal clinical trial in Europe will be designed to establish specific claims that would be used to seek reimbursement in selected European countries. This randomised, controlled trial with marketed drug-eluting stents used in the control arm and will include up to approximately 500 CAD patients. XTENT expects to initiate this clinical trial in 2008.
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