Duke Study Shows Umbilical Cord Blood Transplant is Viable Treatment for Genetic Disorders
MIAMI, FL -- Children whose genetic disorders have previously been a death sentence have a reasonable chance for life with umbilical cord blood transplants, according to Duke University Medical Center researchers.
The physicians found that of the patients treated, those younger than 2 years old did the best, with 80 percent surviving.
Results of a study prepared for presentation Sunday at the American Society of Hematology annual conference show an overall long-term survival rate of 68 percent for children with a variety of genetic diseases.
"What we've seen is that diseases which in the past have been thought incurable can now be cured if recognized early and referred to appropriate resources -- centers that can treat pediatric patients with umbilical cord blood transplant," said Dr. Rick Howrey, who led the study.
Doctors think the success rate of transplants at early ages may be related to the period of the infants' developing immune systems, which make it less likely that they will suffer serious graft vs. host disease. That occurs when the transplanted cells (the graft) begin growing and later attacking the rest of the body, as if the host's other cells are foreign to the newly developing immune system. Replacing the patient's defective marrow before the genetic disease has caused serious damage may also contribute to the higher success in younger patients, Howrey said. In addition, the patients' smaller size increases the ratio of stem cells per kilo of body weight, which is probably the most important factor, he said.
"A lot of parents of children with these genetic disorders have been told by their doctors, 'There's nothing we can do,' which in the past has been true. But with this new form of treatment, there is now hope for children with many genetic diseases which in the past had been uniformly fatal. There are a lot of physicians who have not heard about this treatment yet and are now learning that there are other possibilities for children with genetic disease," said Howrey. "Early diagnosis of the genetic problem is the key."
In the study, 50 patients with genetic disorders were treated at Duke with umbilical cord blood transplants from unrelated donors. The disorders, all fatal without replacement of the children's bone marrow, included immune deficiencies, marrow failures and metabolic disorders. Forty-five patients grew new marrow and 34 of the children treated are still alive.
Umbilical cord blood can substitute for marrow in a transplant because the blood is rich in immature cells, called stem cells, that generate developing and mature blood cells. The tissue-type match between the donor and recipient doesn't need to be as close as in bone marrow transplants, probably due to that same immaturity of cells in the cord blood that would normally trigger rejection of tissue, researchers said.
Replacing the bone marrow, in essence, replaces a primary component of the patient's genetic make-up, doctors said, and thus can cure the genetic disorder.
Early diagnosis has given the daughters of Kim and David Gosey a second lease on life. Their first daughter, Hannah, was 6 months old when she received an unrelated cord blood transplant in February 1997 to treat Hurler's Syndrome, a genetic disease that affects the metabolism. Without transplant, doctors said Hannah would have lived only seven to 10 years, and spent much of that time suffering.
Hannah was about 18 months past her transplant when Kim Gosey discovered she was pregnant again, and shortly afterward that her second child would also be born with Hurler's Syndrome.
The Portsmouth, Va., couple didn't hesitate. They immediately contacted the Duke team to begin the process of searching for a transplant match for their unborn daughter. "We had everything ready before she arrived," the girls' mother said. "All we had to do was wait for Cassidy."
The baby, Cassidy, received her transplant when she was 3 months old. Now two months past transplant, she is out of the hospital and being treated on an outpatient basis.