Silk Road Medical Submits PMA Application for Enroute Systems, Supported by ROADSTER Data

November 24, 2014—Silk Road Medical, Inc. has submitted a premarket approval (PMA) application to the US Food and Drug Administration seeking 510(k) clearance for the Enroute transcarotid neuroprotection system (NPS) and stent system platform. The PMA submission is supported by data from the ROADSTER investigational device exemption (IDE) trial.

Silk Road Medical’s Enroute transcarotid NPS is designed to provide direct access to the carotid artery and reduce the risk of stroke during carotid angioplasty and stenting (CAS) by diverting debris away from the brain with a surgically inspired mechanism to temporarily reverse blood flow. The devices have been granted European CE Mark approval. In the United States, the Enroute NPS and stent systems are currently limited by law to investigational use only. 

In November, the 30-day outcomes from the ROADSTER IDE study were presented during a late-breaking clinical trials session at the VIVA 2014: Vascular InterVentional Advances meeting held November 4–7, in Las Vegas, Nevada. Additional data were presented at the VEITHsymposium held November 18–22, in New York City. Richard Cambria, MD, and Christopher Kwolek, MD, of Massachusetts General Hospital served as National Coprincipal Investigators of the ROADSTER trial. 

According to the company, the 1.4% 30-day stroke rate in ROADSTER was the lowest seen to date of any contemporary prospective trial of CAS. 

ROADSTER was a prospective, multicenter, IDE study designed to evaluate the safety and effectiveness of the Enroute transcarotid NPS in a hybrid procedure combining the best elements of carotid endarterectomy (CEA) and CAS. Patients were enrolled at 15 vascular surgery sites, one neurosurgery site, and two multispecialty sites. The primary endpoint was a composite of any stroke, death, or myocardial infarction through 30 days.

The study enrolled 208 (67 lead-in, 141 pivotal) symptomatic and asymptomatic patients who were at high risk for complications from CEA. Carotid stent systems approved by the US Food and Drug Administration were delivered through the direct carotid access point under high-rate flow reversal afforded by the Enroute transcarotid NPS. Baseline pivotal population characteristics included 26% symptomatic patients, 35% female patients, and 47% who were 75 years of age or older.

The company reported that at 30 days, the rate of stroke/death/myocardial infarction was 3.5% in the intention-to-treat population (n = 141) and 2.9% in the per-protocol population (n = 136). The rate of stroke and death was 2.8% in the intention-to-treat population versus 2.2% in the per-protocol population. The rate of all stroke was 1.4% in the intention-to-treat population versus 0.7% in the per-protocol population.

There were no strokes in patients who were 75 years or older, nor in symptomatic patients. There was one (0.7%) cranial nerve injury, which presented as hoarseness that fully resolved.

In the company’s press release, Dr. Cambria commented, “These stroke rates in a high surgical risk population are the lowest to date for CAS and comparable to the periprocedural rates in the standard surgical risk CEA arm of CREST (2.3%).”

Dr. Cambria added, “The Silk Road procedure is less of an operation for the patient than a traditional CEA and can be performed in under an hour with local anesthesia. With more experience and evidence, vascular specialists can look forward to incorporating this procedure as a true alternative to CEA for patients.”