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Duke Study Shows Early Marrow Transplant Key to "Bubble Boy" Disease Cure

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Duke Health News 919-660-1306

WASHINGTON, D.C. -- They lived short lives in sterile rooms.
Children with a disorder known as "bubble boy" disease were
born without an immune system, and they inevitably died from
common infections. Their fate was dramatized by a documentary
film of a young Texas patient who lived and died in a germ-free
plastic sphere.

Now, researchers at Duke University Medical Center are
reporting that the disease, known as severe combined immune
deficiency (SCID), can be cured in many cases if diagnosed and
treated early enough.

A 15-year study by Duke physicians shows that more than 90
percent of babies born with the disorder can be given a healthy
immune system if they receive a bone marrow transplant within
three months of birth. They also have learned that these
children need not have a perfectly matched donor, but can use a
parent's "half-matched" marrow. Furthermore, the babies do not
need toxic pre-transplant chemotherapy, as is often thought and
currently practiced.

The results of the study of 79 children were prepared for
presentation May 3 at the joint American Pediatrics
Society/Society for Pediatric Research annual conference. Duke
is one of only a few hospitals in the country that specializes
in treating children with SCID.

"This once-fatal disease should be now seen as a pediatric
emergency, a condition that needs immediate diagnosis and
treatment," said Dr. Rebecca Buckley, chief of Duke's division
of pediatric allergy and immunology.

Buckley said early diagnosis of SCID is rare because doctors
do not routinely perform a test in newborns to count white
blood cells. Such a blood test could pick up children with SCID
as well as those with other serious immune deficiencies that
would not be apparent until the child developed an infection.
"A simple blood test could allow us to treat, and most likely
cure, SCID in a child for as little as $25,000," Buckley said.
"If found later, less effective treatment can run into the
millions."

Babies born with SCID suffer from a variety of genetic
defects, all leading to a lack of T or B immune cell function,
which is essential for protection against infection. The defect
is said to occur once in every 500,000 to 1 million births, but
it could be more common, researchers say, because babies who
die of a simple infection often are not given an autopsy.

"Without an immune system, a patient is completely
vulnerable to infection. A pathogen that would be harmless to a
person with normal immunity would destroy a SCID patient. Until
1982, SCID was invariably fatal unless the patient had a
brother or sister who was an exact match to donate bone
marrow," Buckley explained. "What we see now is that a sibling
match isn't necessary; haploidentical parental marrow will
work, too." A haploid match is a half match.

But the key is timing, according to Buckley. The transplant
needs to be done before the onset of opportunistic infection,
she explained, and in the first few weeks of the baby's life,
when the donor marrow takes hold quickest. Waiting until after
the first four weeks of life increases the risk of infection,
as well as slowing the development of immunity from the donor
transplant.

Buckley also found that transplants can be done without
exposing the infant to toxic chemotherapy, which can have
life-long repercussions.

Many doctors give chemotherapy to all bone marrow transplant
patients because they are following standard cancer treatment
protocol, Buckley said. But chemotherapy is not necessary in
children with SCID because they have no T-cells to attack and
destroy the foreign donor marrow, as is the case with cancer
patients.

"Patients with SCID have no immune systems to reject the
transplants. Our approach avoids toxic agents and their
possible complications," she said.

Moreover, Buckley has found a way to reduce a potentially
fatal complication of transplants called graft-versus-host
disease (GVHD). By removing the donor's T-cells before the
transplant, the donor's marrow cannot rise up and attack the
patient's vital organs -- a common complication with bone
marrow transplants.

And, by removing these cells before the transplant, the
infant avoids the toxic drugs normally given to suppress the
donor's T-cells.

Results from the study of 79 SCID patients who received bone
marrow transplants at Duke between May 1982 and January 1997
indicate that parents, as well as siblings of SCID-affected
babies, can be successful marrow donors. None of the patients
received pre-transplant chemotherapy. Overall, 78 percent of
the patients have survived -- some are now teenagers --
including all 12 recipients who received identical marrow
transplants. Seventy-four percent of the 67 haploidentical (or
parent donor) marrow recipients survive.

Within the total group of 79 patients receiving marrow
transplants, 18 babies were diagnosed with SCID in utero or at
birth because of a family history. Thirteen of those
early-diagnosed babies received marrow transplants from eight
to 24 days after birth. Twelve of 13 -- 92 percent -- survive;
one is now 15. The other six received a transplant within three
months and all survived. The Duke researchers found no
difference in eventual outcome between identical or half-match
stem-cell transplants, leading them to support early diagnosis
and neonatal transplant as key to curing SCID patients.

Newborn screenings can detect the genetic defect in SCID
babies. With the mother available as a marrow donor, the
life-saving transplant can be done in the first few days of a
baby's life. The patient can receive treatment as an outpatient
or with "observation admission" (23 hours in the hospital).

"This makes the treatment both easier on the mother and baby
and cost-effective" said Buckley. "What we're saying is that
essentially every baby with SCID could be cured if diagnosed
early enough. SCID should be considered a pediatric
emergency."

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