Early Stem Cell Therapy Cures 'Bubble Boy' Disease
Transplant in first month of life nearly guarantees survival
THURSDAY, Jan. 24, 2002 (HealthDayNews) -- Babies born with a disorder that effectively erases their immune system are almost guaranteed survival if they have a stem cell transplant within the first month of life, a new study says.
A two-decade review by North Carolina doctors who perform the procedure shows that the grafts, which help infants with severe combined immunodeficiency (SCID) fight off infection, were successful in 20 of 21 babies who otherwise would have died. However, if the transplants are delayed more than 28 days after birth, the survival rate drops to about 75 percent, the researchers say.
"This is a disease that 20 years ago was fatal," Dr. Laurie Myers, a Duke University pediatrician and lead author of the study. "Now, the overall the success rate for transplants is about 80 percent at our center, but we've identified a way to even improve the survival rate."
Myers says the difference seems due to the few infections that can afflict newborns in the first weeks of life.
"Overall, they're in a better condition" when they're less than 28 days old, says Myers, whose findings appear in the Feb. 1 issue of the journal Blood. "They haven't had the chronic diarrhea and respiratory infections" that SCID babies can't clear.
As the results of the latest study suggest, detecting SCID early is crucial to stem cell therapy's success. What's more, a simple test to count a baby's lymphocytes -- a form of white blood cell that is radically suppressed in patients with the disease -- can pick up the condition in the first days after birth.
Testing for SCID isn't cheap, running $40 to $50, so the cost to society of catching just one case out tens of thousands of infants is staggering. Still, Myers says that's a price worth paying.
"We believe that all babies should be screened because their survival rate is 95 percent when diagnosed in the first month of life," she notes.
SCID strikes between one in 50,000 to 100,000 babies born each year in the United States. John Travolta portrayed a patient with the disorder in a 1976 TV film, "The Boy in the Plastic Bubble."
Because of its severity and poor response to drugs, SCID has drawn the attention of the most cutting-edge treatments. Children with the disease were the first to undergo gene therapy, an approach that has proved successful in a limited number of patients.
Doctors have also been able to overcome SCID with transplants of stem cells derived from bone marrow or umbilical cord blood. The grafted cells migrate to the chest and seek out the thymus gland, which is defective in SCID babies. There, they "undergo education," Myers says, and start generating T-cells that are vital to a healthy immune response.
The Duke study followed 21 patients since the early 1980s who'd undergone stem cell therapy within 28 days of delivery. Nine had been diagnosed with the disease while still in the womb, and 12 immediately after birth. All of the children had a family history of the disorder.
One of the babies died of a viral infection specific to SCID, but the rest are still alive. That's a far better return than the 71 of 96 infants, or 74 percent, who survived on transplants after a longer wait.
The Duke team, unlike other SCID centers, doesn't treat babies with potent immune-suppressing drugs before the transplant, which typically lasts an hour or so and requires only a day of hospitalization. But more than half the patients must receive monthly infusions of an immune-boosting drug, IVIG, to keep their defenses against microbes intact.
"The ones that are older are likely to need it for the rest of their lives," Myers says. "It would be nice if they didn't need to have this treatment."
Dr. Jonathan Goldsmith, vice president for medical affairs at the Immune Deficiency Foundation, says the new study is "very exciting. It suggests that early interventions can lead to better survivals, and it looks like better quality survival, because the T-cell function comes back so much quicker and stays up longer" than in babies who get the grafts later.
Goldsmith says his group "strongly favors either a pilot or a widespread program for neonatal screening" for SCID, despite the added cost. "I think you have to think about this from the perspective of finding people who have potentially curable disease."
What To Do
If you're pregnant and someone in your family had SCID or another inherited immune system disorder, be sure to tell your doctor. Your baby can be tested either in the womb or after birth.