A new technique in the fight against leukemia may give children who are most likely to fail standard therapy a better shot at beating their disease.
A new form of blood stem cell transplantation (also known as a bone marrow transplant) allows closely related relatives to donate their healthy cells without being a perfect match to the recipient's cells.
Our goal is to formulate a way to do the transplant more safely," said Dr. Gregory Hale, interim chief of the St. Jude Bone Marrow Transplantation Division.
In standard stem cell transplantation a patient first undergoes a treatment called myeloablative conditioning regimen (MCR) to destroy all of the blood cells in the body, including the cancerous blood cells. Then, the patient receives a blood stem cell transplant from a genetic match, in the hopes that these cells will settle into the patient and begin to produce normal, mature blood cells.
If these transplanted cells do not come from a perfect match, however, they will not be accepted by the patient's body. In fact, since some of the donated cells work to rebuild the patient's immune system, these poorly matched cells can begin to attack the body, causing a serious, life-threatening condition known as graft-versus-host disease. Treatment of graft-versus-host-disease involves suppressing the immune response, but doing so without damaging the new bone marrow.
It is difficult to find a perfect match. Hale estimates that 70 percent of Caucasians and 50 percent of minority patients find matches in the national registry. Additionally, it can take up to four months before an unrelated match is confirmed and available for the donation. And on top of this, the MCR that is a required part of standard stem cell transplantation can be dangerous and make the patient more sick before he gets any better.
Researchers from St. Jude Children's Hospital, however, have developed a new technique that allows them to use donor stem cells from a parent or sibling who is not a genetic match.
Health
The technique takes stem cells from the related donor and treats them to remove a set amount of the immune system cells that cause graft-versus-host disease. This should lower the risk of graft-versus-host disease, but leave enough healthy immune cells to fight off any remaining leukemia cells. This technique not only allows cells to be taken from a less-than-perfect match who is readily-available for the donation, but eliminates MCR and replaces it with a less harsh treatment to prepare the patient's body for the transplant.
"The overall success of this procedure suggests it holds promise for children who are likely to fail standard treatment for leukemia because they have treatment-resistant disease and no matched donor," said Hale.
In a preliminary study, researchers compared results of the new stem cell transplant technique with the standard stem cell transplant technique. After being followed for a year after the initial treatment, 91 percent of those children who received the new technique completely accepted the new cells. A similar percent of patients who had standard stem cell transplant also had a successful treatment.
There were several patients that still suffered from graft-versus-host disease with the new treatment, but those who did not suffer from graft-versus-host-disease had a faster recovery than those who had the standard transplant. Moreover, the patients' immune system had recovered within four months of the initial treatment. . It is a promising development, but Hale cautions that the new technique needs to be studied further to determine its long-term success and its' ability to control the most aggressive forms of leukemia.
