SilverHawk to start multi-center clinical trial

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Following the furor at last year’s Society for Vascular Surgery (SVS) meeting, there was better news for fans of FoxHollow Technologies’ SilverHawk plaque excision system with the recent announcement that the company plans to initiate two clinical studies on the use of the SilverHawk system in treating peripheral arterial disease.

The first study will be a 100-patient independent registry and will include 6- and 12-month duplex ultrasound follow-up of patients, with the results to be evaluated by an independent core lab. Enrolment is expected to be completed in the second quarter of 2006, and 6-month data will be available in the first quarter of 2007.

The second study will be a randomized trial comparing outcomes in patients treated with SilverHawk versus those undergoing medical management. Enrolment is expected to be completed by the end of 2006, with initial data available by mid-2007.

The company also announced that it has filed for an investigational device exemption (IDE) with the FDA to begin clinical trials of the SilverHawk in the treatment of coronary artery disease in bifurcated vessels. The company said it plans to introduce four enhancements to the SilverHawk device this year, designed to increase its effectiveness in cutting calcified plaque, its ease of use, and the number of areas it can treat within the legs.

Talons out

At the 2005 SVS meeting, results from the company’s TALON registry sparked fury among some vascular surgeons who criticized investigators for allegedly having financial interests in the company. Dr Takao Ohki, New York, said that there was a need to clarify the financial incentives of the investigators as – according to Ohki – 11 of the original 12 investigators have stock options in FoxHollow. In addition, Ohki criticized the data claiming that non-protocol-driven target lesion revascularization is not an objective endpoint as it is affected by physician decision. Theoretically, one can have a 0% patency rate and 0% target lesion revascularization. Ohki’s views were supported by Dr Ken Ouriel, Cleveland Clinic, who added that the TALON registry had inconclusive data on patency.

Previously, the company had said it was not necessary to conduct trials to test SilverHawk’s effectiveness against other procedures because that would be expensive and unnecessary, as there are already positive registry data. Companies and academic institutions often use registries to assess the performance of a product, although the data are much less reliable than randomized trials.

“We have always been a clinically driven company, and our TALON study has been the largest registry for PAD patients treated with an endovascular therapy. In addition, a number of single center studies have demonstrated the efficacy of SilverHawk. At the same time, given the evolution of our device and the significant clinician experience with it, we believe it is now appropriate to launch a broader program of clinical studies. We believe the findings from these and future studies, will not only assist us in the development of new devices but also help us obtain a better understanding of vascular disease and identify new indications for the use of the SilverHawk,” commented interim CEO Dr John Simpson.

Separately, a multi-center evaluation of patients with critical limb ischemia, headed by Dr David Kandzari of Duke Medical Research Institute and colleagues, has reported that 82% of patients who received plaque excision avoided an amputation or received a less extensive amputation than originally planned. The patient population was composed of those who suffer from the most severe form of PAD. Six months after the plaque excision procedure, 96% of the lesions remained free from re-treatment in patients without amputation. Results of the study were published in the February 2006 issue of The Journal of Endovascular Therapy.

In the evaluation, plaque excision was performed in 69 patients (76 limbs, 159 lesions) with procedural success in 99% of cases. In the majority of patients treated, SilverHawk was the only therapy. Stents were placed in just 6% of the cases. “We desperately need an answer for these patients, and we are very encouraged by the promise plaque excision shows in helping critical limb ischemia patients avoid amputation,” said Kandzari.

The critical limb ischemia patients treated with plaque excision were prospectively followed for six months at seven US institutions. A retrospective review of this patient subset was completed. Overall, a high prevalence of cardiovascular risk factors was identified: 78% of patients had diabetes, 57% had a history of coronary artery disease, and 47% had kidney impairment. More than 40% of patients already had a previous leg artery procedure.

“In general, the patients treated were among the sickest we see and faced a high likelihood of losing a leg. Amputation was already planned before these procedures for 48 of 76 limbs treated. The fact that 82% avoided amputation or were able to minimize the extent of the amputation is a remarkable result that validates the important role plaque excision plays in limb salvage,” Kandzari concluded.

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