June 7, 2007 -- Kids with leukemia may need a bone marrow transplant from a matched donor. But they do just as well with mismatched cord blood, doctors find.
About 30% of patients needing a transplant are lucky -- they have a brother or sister whose bone marrow is a perfect match for their own. But the other 70% of patients have to endure a desperate search for a matched stranger willing to undergo the painful donation process.
Now a new finding is revolutionizing the field of bone marrow transplant. University of Minnesota researcher John E. Wagner, MD, and colleagues show that unmatched infusions of umbilical cord blood work as well as matched bone marrow transplants.
"Seeing the lack of impact of matching was a surprise," Wagner tells WebMD. "No one would have thought this would have occurred. This is going to change the face of transplant medicine."
The change already is under way. About half of children and 30% to 40% of adults who would previously have received bone-marrow transplants -- if they could find a donor -- are now getting cord blood infusions, says Gary Kleiner, MD, PhD, co-director of pediatric stem cell transplants at the University of Miami Miller School of Medicine.
"Potentially, with cord blood, most patients who didn't have a donor before will now have someone," Kleiner, who was not involved in the Wagner study, tells WebMD. "After doing 1,000 cord blood transplants, I have never found a patient without a suitable cord-blood donor -- and it saves time, which often is of the essence."
Moreover, when cord blood is a perfect match with the patient's tissues, it appears that cord blood transplants offer even better results than matched bone marrow transplants.
"I think this is one of the most important pieces of medical information to come out of transplant medicine in a long time," Wagner says. "It has profound implications not only for individual patients but also for public policy."
Why public policy? What's holding back more widespread use of cord blood is not lack of donors. Wagner and Kleiner say that donations -- taken from the umbilical cord and placenta after a healthy baby already is delivered -- are not hard to obtain.
The problem is the expense of properly banking cord blood. Wagner says that Congress has already allocated $100 million for cord blood banking and that more public funds likely will become available as cord blood transplants become ever more common.
Cord Blood and Child Leukemia
Wagner and colleagues studied children treated for leukemia before their 16th birthday. Treatment means using chemotherapy to kill off their white blood cells. To replenish these crucial immune system cells, 282 of the kids got bone marrow transplants and 503 got cord blood transplants.
Both bone marrow and cord blood contain blood stem cells capable of replacing the cells lost to chemotherapy. But the transplants only take if the donor's tissues carry nearly all the same "self" markers -- called HLA -- as the patient's tissues.
The worse the HLA match, the greater the chance the transplanted cells will see the patient's body as "foreign" and attack it.
But earlier studies suggested that cord blood cells didn't have to be a perfect match. Of the six crucial HLA markers, cord blood seemed to work if one or even two HLA markers were mismatched.
Wagner and colleagues looked at how many kids remained leukemia-free after five years -- a milepost that usually means the patient is cured of cancer.
Sure enough, kids who got cord blood transplants mismatched for one or two HLA markers did as well as kids who got matched bone-marrow transplants. And kids who got perfectly matched cord blood transplants seemed to do even better than those who got matched bone marrow transplants.
Kids with leukemia aren't the only patients who badly need bone marrow transplants. The treatment can also save the lives of children born with dysfunctional immune systems. Many such children, Kleiner says, can't survive a long search for a matched marrow donor.
"No longer do we have to keep searching for that matched marrow donor," Wagner says. "Fifteen thousand patients -- right now -- cannot find a donor. This now gives them another option. Matching is no longer the barrier it is with marrow donors."
Wagner says that doctors are now much better at cord blood transplants than they were when the study began. Patients today can expect much better results than those seen in the study, he says.
The Wagner study appears in The Lancet. In an editorial accompanying the study, Vanderson Rocha and Eliane Gluckman of Saint Louis Hospital in Paris, advise doctors to start their search for cord blood banks and bone marrow registries at the same time -- and to use the one they find first.
Wagner says that his group is studying whether cord blood works as well for older adults as it does for children.