FDA Panel Urges Artificial Skin
GAITHERSBURG, Md. (AP) _ Doctors faced with some of the hardest to treat skin ulcers soon may try the first implants of living, bioengineered skin to fill the open sores.
Advisers to the Food and Drug Administration recommended Thursday that two types of this skin be approved: one treats the diabetic foot ulcers that can lead to amputations; the other treats the deep leg lesions that strike people with poor blood circulation.
The FDA is not bound by its advisers’ decisions. But the agency typically follows them. If it does, the products could mark a new era in the quest for artificial skin _ a hurdle their makers noted Thursday.
``This is a first-of-a-kind product,″ said Gail Naughton of Advanced Tissue Sciences, the La Jolla, Calif., company that pioneered DermaGraft for diabetes. ``Take into account the novelness.″
Because Apilgraf contains active bodily growth factors and other cellular substances, ``it is very similar to human skin,″ added Michael Sabolinski of Organogenesis Inc. of Canton, Mass.
The FDA advisers cautioned that the products still are not as good as real skin _ they questioned just how well DermaGraft works and said Apilgraf may be better than standard care only for the most severe leg ulcers.
But until now, victims of chronic skin ulcers or burns had two choices: traditional skin grafts if they had enough of their own skin left, or temporary skin coverings made of nonliving cells to protect the wound as their own cells grew back.
Hunting for an easier solution, tissue engineers proposed growing permanent, living replacement skin that could be stored until needed and then integrate itself into the body.
Organogenesis’ Apligraf is the most complex attempt so far. The company uses discarded foreskin from newborn circumcisions to make a ``human skin equivalent″ that contains all the layers of real skin. It can live five days before implantation.
Some 2 million Americans with vein disease suffer deep leg ulcers that can linger for months, causing severe pain and swelling. Patients must elevate their legs and wear tight elastic bandages in an attempt to heal.
In a study of 240 patients, Organogenesis compared implanting Apilgraf into the open sores with traditional care. Apilgraf was no better than standard care in the overall number of ulcers healed _ although it did appear to help legs heal a little faster, by 40 to 85 days.
But the FDA panel said the significant difference came in ulcers so severe they lingered over a year. Apilgraf helped 66 percent more of these ulcers heal, prompting the panel to vote 5-4 that Apilgraf should be sold.
Some 800,000 diabetics also suffer open sores every year, on their feet. The ulcers risk infection that lead to thousands of toe and foot amputations.
DermaGraft is a living, metabolically active copy of just the top layer of human skin. Also grown from foreskin, it is stored in a freezer until needed.
ATS compared covering diabetic ulcers with DermaGraft to standard surgical and antibiotic care.
At first, DermaGraft appeared no better. The company discovered the freezing process was killing some cells, so it changed manufacturing techniques.
Looking at a subset of patients who got the new, more potent DermaGraft, ATS argued that 41 percent of ulcers healed within 12 weeks, compared with 28 percent of diabetics who got standard therapy.
The FDA questioned whether the company’s results were statistically significant, and government advisers agreed the statistics were troubling.
``It looks like it’s very promising, but I am not 100 percent convinced it’s effective yet,″ said Dr. Susan Galandiuk of the University of Louisville.
Still, the panel found an unusual solution: Calling DermaGraft probably effective, it voted 7-2 that FDA approve the skin on the condition that ATS perform a large, strictly controlled effectiveness study once sales begin. Panels unsure of effectiveness typically require such studies prior to FDA approval.