FDA OKs Bioengineered Vessel to Reduce Limb Amputations After Vascular Trauma

The FDA on Friday approved acellular tissue engineered vessel (Symvess), an off-the-shelf product for treating vascular trauma in the extremities of adults.

The one-time, single-use therapy — the first of its kind — is indicated for use as a vascular conduit for arterial injuries that require urgent revascularization to avoid the imminent loss of limb, and for when an autologous vein graft is not feasible.

“Currently available treatment options are limited for vascular trauma, which can lead to severe and potentially life-threatening complications,” Nicole Verdun, MD, director of the Office of Therapeutic Products at FDA’s Center for Biologics Evaluation and Research, said in a statement. “Today’s decision to approve a new therapeutic product based on novel medical technology represents important progress in addressing a significant unmet medical need.”

Standard of care for patients with these types of injuries involves autologous vein grafting, but harvesting a vein requires time and increases the amputation risk, and is not always feasible. Synthetic grafts are available as well, but carry a high risk of infection.

The newly approved bioengineered vessel is made up of human extracellular matrix proteins, typically found in human blood vessels, and derived from aortic tissue.

Safety and effectiveness of the product was demonstrated in a single-arm phase II/III multicenter trial involving patients who had life- or limb-threatening vascular trauma, including injuries resulting from car accidents, gunshot wounds, or industrial accidents.

Of 54 patients evaluated, two-thirds retained primary patency (blood flow) a month after the product was surgically implanted to replace a damaged arterial vessel in the extremity, and 72% retained secondary patency.

Rates of infection and amputation were low. Overall, 9% did require amputation of the treated limb over that first month while 15% required an amputation through 3 years.

“The approval of a vascular conduit that resists infection and remodels into native arteries is an extraordinary technological advancement that will have a huge impact on the quality of trauma care around the world,” said investigator Charles Fox, MD, director of vascular surgery at the University of Maryland Capital Region, in a statement from developer Humacyte.

“Symvess is perfectly sized to treat most injuries, has excellent handling properties, and reduces time necessary to save both life and limbs,” Fox added.

Investigator Rishi Kundi, MD, a vascular surgeon from the University of Maryland Medical System in Baltimore, added that the new product “will allow reconstructions that are currently impracticable because of contamination and infection.”

In trials, adverse events occurring in at least 10% of treated patients included thrombosis within the bioengineered vessel, fever, pain, and anastomotic stenosis.

Serious risks included graft rupture, anastomotic failure, and thrombosis. Labeling for the product has a boxed warning about the potential for graft failure that can result in life-threatening hemorrhage, and the treatment is contraindicated in patients who cannot take long-term antiplatelet therapy.

Transmission of infectious disease is theoretically possible with the bioengineered vessel — as it’s comprised of human cells and human/bovine reagents — though donors must meet strict eligibility requirements to reduce such risks.

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