SEATTLE--Early donor matching and transplant appear to be particularly important in improving survival rates in chronic myeloid leukemia (CML) patients receiving unrelated donor marrow, John A. Hansen, MD, said at the plenary session of the American Society of Hematology annual meeting. In fact, he said, in selected patients, survival rates approach those of patients receiving marrow from HLA-identical siblings.
The anticipated 3-year survival rate for CML patients in chronic phase who receive marrow from an HLA-identical sibling has been about 80%, while 2-year disease-free survival in patients receiving unrelated donor transplants has ranged from 36% to 45%.
The new study, conducted at the Fred Hutchinson Cancer Research Center and the University of Washington, Seattle, showed 74% 3-year survival in selected patients with HLA-matched unrelated donors and early transplantation.
Dr. Hansen, professor of medicine at the University and head of the Human Immunogenetics Program at Fred Hutchinson, said that the study included 333 CML patients receiving non-T-cell-depleted bone marrow cells following cyclophosphamide(Drug information on cyclophosphamide) and total body irradiation. Methotrexate(Drug information on methotrexate) and cyclosporine were administered after the transplant for prevention of graft-versus-host disease (GVHD).
Although a majority of the patients in the study were HLA-A, B, DRB1 identical with their donor (75%), the remaining 25% involved at least one minor donor mismatch for HLA-A, B, or DR antigens, Dr. Hansen said. Patient ages ranged from 5 to 55 years, with a median of 36 years.
The study found that, for patients under age 50, the probability of surviving 3 years post-treatment was 74% if transplantation from an HLA-matched donor occurred less than 1 year after diagnosis of CML.
In comparison, the 3-year survival rate dropped to 57% if transplantation was done more than 3 years following diagnosis. Survival dropped even further, to 40%, if the marrow was from a mismatched donor and transplantation was done more than 3 years after diagnosis.