A former Food and Drug Administration (FDA) medical officer alleges that the agency’s Center for Biologics Evaluation and Research approved a novel medical product over the objections of four expert vascular surgeons.
The approval letter, issued in December 2024, told the product’s sponsor Humacyte Global Inc. of Durham, North Carolina that the FDA “did not refer your application to the Cellular, Tissue, and Gene Therapies Advisory Committee because our review of information submitted in your Biologics License Application—including the clinical study design and trial results—did not raise concerns or controversial issues that would have benefited from an advisory committee discussion.”
Dr. Robert E. Lee, a board-certified vascular surgeon for 40 years, with 30 years of clinical experience, told The Epoch Times that the statement “simply is not true.”
Lee spent the past 10 years with the FDA as a medical officer in the Center for Devices and Radiologic Health, which is charged with determining the safety and effectiveness of new products before they are marketed.
Lee said that “three highly experienced” in-house vascular surgeon medical officers from the FDA’s Vascular and Endovascular Devices Team—the group traditionally responsible for vascular graft approval—raised “serious concerns” about the performance of Symvess.
“As it stands, Symvess should not have been approved,” Lee said. “The FDA could ask the manufacturer for a voluntary recall pending advisory panel review.”
FDA press officer Carly Pflaum told The Epoch Times that input from Lee was considered and, as a result of some of the concerns he raised, “the review team took additional actions during the review” in response.
Concerns From Evaluators
According to an FDA document, the agency engaged three vascular surgeons—who were employed outside the drug administration but worked for the government and had security clearance—to review a summary of the clinical data, without going through a review by an advisory panel of experts reviewing all the data, a procedure that is often used for novel and controversial products.Given the product review he had submitted, one of the three outside evaluators subsequently asked Lee how Symvess could have been approved, according to Lee.
Lee said four of the six vascular surgeons—three in-house and one outside—who reviewed the product “voiced serious concerns about Symvess.”
“Yet, the FDA writes in its approval letter that the information submitted by Humacyte ‘did not raise concerns or controversial issues,’” Lee said.
A spokesperson for Humacyte told The Epoch Times: “FDA’s review of the product Symvess was very high-quality and detailed, involving review of thousands of pages of documents over a 12-month period.
“This review involved more than 30 FDA reviewers and staff members, as well as a number of outside consultants. After consideration of all available data, the FDA approved Symvess for use in vascular trauma.”
Lee said that after he raised his concerns with top management, he and his supervisors were promised that Symvess would be subject to public review by a traditional panel.
“This type of panel would have brought in experts in surgical infection and trauma surgery, as well as vascular surgeons,” he said. “No such panel review ever took place.”
In approving Symvess, Lee alleged that “the FDA ignored its policies, relied on problematic data, and failed to subject the first-of-its-kind product to a public, advisory panel review.”
Referring to the trial of Symvess conducted in Ukraine, Zhou said the quality of the data was “poor,” and the integrity of the trial “questionable.”
He called it “a retrospective observational study, which is prone to selection bias.”
Zhou said the Ukraine trial data were “skewed to shrapnel injuries and not the more typical devastating limb or polytraumatic military injuries.”
According to Zhou, no clinical evidence submitted demonstrates that Symvess is infection-resistant, and there was “uncertainty” on how Symvess compares to other treatment options.
“It is not apparent from the study data whether there are situations where the benefit of [Symvess] outweighs the risk,” Zhou said.
Lee said Zhou’s statistical review was available to FDA officials before the product was approved.
“Additionally, the labeling approved for the product provides insufficient warnings that do not adequately mitigate the risk of the serious, adverse events that some of the subjects of the trials sustained,” Lee said.
“The totality of the clinical data from the sponsor’s studies showed an alarming 10 percent risk of loss of vascular integrity and life-threatening bleeding in subjects treated with Symvess.”
Lee said after three months of carefully reviewing more than 2,300 pages of detailed clinical assessment reports covering 86 patients used in two studies, he concluded that “the product was too prone to catastrophic failure, such as breakdowns in the middle of the Symvess graft or at the point of connection with the patient’s arteries.”
“The problem was seen in 10 percent of the subjects. The patients developed serious bleeding. One died. That is too high,” he said.
“As a physician, I took the Hippocratic Oath not to harm patients. While working as an FDA medical officer, that oath was always in my mind.”
Lee stated that the observed risks of Symvess blowouts (structural failures) and associated infections are unacceptable when compared to current alternate treatment options, such as the use of another healthy vessel removed from the patient or plastic-like tubes called Dacron grafts.
“The available evidence shows the risk-benefit balance when using Symvess for vascular trauma is highly unfavorable,” he said.
A Defense Priority
Acellular Tissue Engineered Vessels, such as Symvess, received priority designation from the secretary of defense for the treatment of vascular trauma in 2024, according to a Humacyte press release.Lee noted that the Department of Defense has identified “the need for an off-the-shelf vascular graft.”
He said Symvess is not the answer.
“The data I reviewed does not support that Symvess is safe and effective in the trauma setting. The data raises major concerns that Symvess could result in worse outcomes than other available options.”
According to Lee, the Department of Defense designation may have increased the pressure for speedy approval by the FDA.
“Nonetheless, the data does not show the product is truly durable and infection-resistant as was hoped,” he said.
“If military surgeons reviewed the plethora of detailed data that I have evaluated, I doubt that they would be enthusiastic about using Symvess on distant battlefields.”
What is Symvess?
Humacyte founder and Chief Executive Officer Laura Niklason said in a press release that the development of Symvess “is a milestone for regenerative medicine overall.”According to Humacyte, Symvess is a tissue structure “designed to resemble the body’s natural vasculature and aims to restore, replace, or enhance the function of damaged or diseased vascular tissue.”
Symvess is made in the laboratory using blood vessel cells from a human donor and is comprised of organized extracellular matrix proteins.
All human DNA is removed from the material during the process.
The tubular product is grown to a length of 42 inches. Its diameter is the size of most human arm and leg arteries.
Packaged in a sterile saline solution, the tube can be cut to length for single-patient use in the operating room.
If properly refrigerated, Symvess has a shelf life of 18 months.
Humacyte said in the press release that the benefits of Symvess include reducing the amputation rate for traumatic vascular injuries from gunshot and blast wounds, as well as car and industrial accidents.
The company said Symvess also benefits patients by reducing the need to reinjure them by harvesting and then transplanting veins from other areas of the body—often a time-consuming procedure.
Lee stated that “Humacyte did what they promised and provided the clinical data that the FDA requested to support the trauma indication.”
He said his problem is with the FDA’s Center for Biologics Evaluation and Research’s process of vetting that data, calling it “less than transparent.”
“It was a backdoor way of approval that ignored input from the Center of Devices and circumvented any feedback from an advisory panel,” he alleged.
Lee’s attorney, Dr. Joe Piacentile of Whistleblowers International, told The Epoch Times that—in light of the information made public by his client—he is optimistic that Secretary of Health and Human Services Robert Kennedy Jr., FDA Commissioner Dr. Marty Makary, and Secretary of Defense Pete Hegseth will be open to revisiting the approval of Symvess.
