| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | COVER ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
||||||||
|
||||||||||
NEWS & VIEWS |
The findings, reported by US and European research groups in the New England Journal of Medicine (2004;351:2265–2275 and 2276–2285), offer a promising alternative to thousands of leukemia patients in need of treatment.
"As many as 16,000 leukemia patients diagnosed each year require a bone marrow transplant but have no matched relative or can’t find a match in the national bone marrow registry," Mary J. Laughlin, MD, Associate Professor of Medicine at Case Western Reserve University School of Medicine and lead researcher of one of the studies, said in a statement. "Umbilical cords that are normally discarded after birth could provide real hope for these patients."
Laughlin and colleagues compared outcomes in 600 patients aged 16 to 60 with acute lymphoblastic leukemia, acute myeloid leukemia, chronic myeloid leukemia, or myelodysplastic syndrome. Thirty-four patients received transplants of cord blood mismatched for 1 human leukocyte antigen (HLA); 116 patients received cord blood mismatched for 2 HLA antigens; 83 patients received bone marrow with 1 HLA mismatch; and 367 patients received HLA-matched bone marrow.
Disease-free survival was highest—33% at 3 years—among patients who received a matched bone marrow transplant. But the rates were similar for patients who received mismatched marrow or cord blood (19% vs. 23% at 3 years; P = .69). Rates of treatment-related mortality were also similar for the mismatched marrow group and the cord blood group (P = 0.96), as was overall mortality (P = 0.92). These similarities were all the more remarkable, the researchers noted, because 77% of the cord blood transplants were mismatched for 2 HLA antigens, while the mismatched bone marrow grafts were only mismatched in 1 HLA antigen.
The European study, led by Vanderson Rocha, MD, PhD, of the Hôpital Saint-Louis in Paris, compared 682 adults with acute myeloid or lymphoblastic leukemia who received either a matched bone marrow transplant or a mismatched cord blood transplant (43% with more than 1 HLA mismatch). The researchers found no significant differences in transplant-related mortality, relapse, or disease-free survival between the two groups.
Cord blood transplants have been used successfully in children with leukemia, but the technique has some limitations when used in adults. One of the greatest obstacles, said Ralph Vogler, MD, Scientific Program Director at the American Cancer Society (ACS), is retrieving sufficient numbers of stem cells from the cord blood to populate the bone marrow of an adult. Typically, cord blood produces about one-tenth the number of useable cells compared with bone marrow.
One consequence of these numbers is the time it takes for neutrophil and platelet counts to return to normal after grafting. In Laughlin’s study, median neutrophil recovery occurred after 18 days in patients who received matched bone marrow, compared with 20 days in those receiving mismatched bone marrow and 27 days in those receiving cord blood. Infection-related deaths in the first 100 days following transplant were significantly higher in the cord blood group (45%) than in either of the bone marrow groups (21% for matched marrow, 24% for mismatched marrow). Neutrophil recovery in cord blood recipients was also significantly delayed in Rocha’s study.
But progress has been made in that arena, Vogler said. "Now what’s being done is after the transplant they’re giving growth factors to stimulate white cell production, and there is a growth factor that can stimulate platelet production," he said. Platelets can also be transfused, he added.
There are also some advantages to cord blood transplants. There is no danger to the donor, because the blood is collected after birth before the placenta and umbilical cord are discarded. Once a suitable donor is identified, the cord blood can be made available more rapidly than bone marrow.
In addition, stem cells from cord blood are less immunogenic than those from adult blood, so grafts tend to be better accepted with less graft-versus-host disease (GVHD), Vogler said.
In Laughlin’s study, rates of acute GVHD were similar in patients who received cord blood and matched bone marrow, while patients who received mismatched bone marrow had higher rates of this complication. The European researchers, however, found lower risk of acute GVHD among cord blood recipients compared with recipients of matched bone marrow.
Risk of chronic GVHD was not significantly different between the two groups in the European study. In the US study, however, the rate of chronic GVHD was higher among cord blood recipients than among matched marrow recipients and similar to the rate among mismatched marrow recipients. Nevertheless, the US study found significant differences in the proportion of cases of extensive GVHD among all their patients with chronic GVHD: 33% of cord blood recipients, 52% of HLA-matched marrow recipients, and 71% of mismatched marrow recipients (P = 0.03).
Overall transplant results are still best when a matched bone marrow donor is available, and neither group of researchers recommends cord blood as a substitute for a matched marrow donor.
Although use of cord blood for transplantation is increasing, the optimal organization and regulation of cord blood banks remain topics of debate, according to Robert Steinbrook, MD, a correspondent with the New England Journal of Medicine. In a perspective article in the same issue of the Journal, Steinbrook noted the differences between public and private cord blood banks.
According to Steinbrook, public banks around the world currently store between 175,000 and 200,000 units of cord blood. The banks do not charge the donor for collection or storage, but do charge $15,000 to $25,000 when a unit is provided for transplantation. The fee is usually covered by health insurance, Steinbrook wrote. However, expansion of these public banks has been limited by a shortage of stored cord blood and a lack of funding for storage and collection, he added
In contrast, private cord blood banks offer parents the opportunity to store their own child’s cord blood for subsequent use by the child or a sibling. Fees generally are about $1,000 to $1,500 for collection and $100 a year for storage. Blood from private banks has been used in only a handful of transplants, Steinbrook notes. One issue: "As medicine is currently practiced, a child’s own cord blood cannot be used if the child is born with a genetic disease or develops leukemia."
Steinbrook concludes, "A person’s own cord blood is very unlikely to be needed for personal or family use, so patients and society are better served when matches from unrelated persons can be found in a public bank."
|
| ||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | COVER ARCHIVE | SEARCH | TABLE OF CONTENTS |
