Bone Marrow Transplants a Thing of the Past?
A frequent complication of allogeneic transplants is graft-vs.-host disease, where the donor cells attack the patient's organs and tissue. This occurs most often in patients who receive transplants from relatives who weren't a suitable match or from unrelated donors. In this study, the overall rate of graft-vs.-host disease was about the same between the two groups.
At the end of 2 years, 65% of the patients who had received the peripheral blood were alive and free of their disease, which could be said of only 45% of the bone marrow group. Interestingly, the patients who benefited the most from the blood stem cells were those with more advanced disease.
"These results suggest that use of blood stem cell transplants may offer advantages over bone marrow grafts in terms of overall survival and disease-free survival," says Lazarus, "But it remains to be determined whether the use of blood rather than marrow is preferred in subjects in whom the disease is not so advanced."
Also, Lazarus adds, it is uncertain whether these same benefits would be seen when the donor is not as closely matched as the ones in this study were, or if the donor is unrelated.
An advantage to this procedure is that it is safer for the donor, because blood cells can be extracted in an outpatient procedure not requiring an operating room or anesthesia. In turn, this could mean more people would be likely to volunteer as donors, says Lazarus.
The results of this study are important for two reasons, says Georgia Vogelsang, MD, an associate professor of oncology at the Johns Hopkins University School of Medicine in Baltimore.
"First, it is a large study from major transplant centers conducting a randomized study," she says. "Prior studies have suffered from small numbers and were generally from a single center."
And second, it opens the door to the next generation of studies, which may utilize better strategies in obtaining stem cells from blood, she says, thereby allowing for better control of graft-vs.-host disease, infection, and relapse. Vogelsang was not involved in the study.
But although these results are promising, it is still uncertain whether stem cells derived from blood are best for everyone.
"Whether or not it should be used over marrow is an issue that should be discussed with a patient's individual physician," says Bensinger.
The study was supported by grants from the National Cancer Institute, the National Institute of Diabetes and Digestive and Kidney Diseases, and the Jose Carreras International Leukemia Foundation.