Patients who receive bone marrow transplants are significantly less likely to develop chronic graft-vs-host disease than those who receive peripheral blood stem cell transplants, according to a new, large randomized trial, the first of its kind with unrelated donors. Published recently in The New England Journal of Medicine,¹ the study found higher rates of engraftment among the peripheral blood transplant recipients but no statistically significant difference in relapse or survival between the two groups.

The results should change current practice for some patients, said Frederick R. Appelbaum, MD, of the Fred Hutchinson Cancer Research Center, in an accompanying editorial (see sidebar on page 16).

Currently, 76% of transplants in the United States use stem cells harvested from peripheral blood via apheresis. Bone marrow, which was the initial source of blood stem cells, is obtained while the donor is under anesthesia.

Evolving Practice

The use of peripheral blood stem cells began to overtake bone marrow transplants after trials with matched sibling donors showed better rates of engraftment. Some studies with sibling donors have also shown better survival and lower relapse rates. However, the higher T-cell content of peripheral blood cells increases the risk of chronic graft-vs-host disease, a serious and sometimes fatal complication.

The multicenter trial, led by Claudio Anasetti, MD, at the H. Lee Moffitt Cancer Center and Research Institute, randomized 551 patients with unrelated donors to receive either bone marrow or peripheral blood stem cell transplants. All patients had undergone chemotherapy or chemotherapy plus whole-body irradiation before transplantation, as well as regimens to help prevent graft-vs-host disease.

Overall survival at 2 years, the primary endpoint of the trial, was 51% in the peripheral blood group vs 46% in the bone marrow group, a difference that was not statistically significant.

Among secondary endpoints, the incidence of chronic graft-vs-host disease at 2 years in the bone marrow group was a statistically significant 41% vs 53% in the peripheral blood group. Relapse rates and incidence of acute graft-vs-host disease were similar in both groups. Graft failure was statistically significantly higher in the bone marrow group—9% vs 3% in the peripheral blood group.

According to the authors, the choice of peripheral blood stem cells or bone marrow may depend on specific patient characteristics. For instance, those who have never undergone cytotoxic chemotherapy, and thus are not as immunosuppressed as those who have, may be more likely to reject a bone marrow graft. Such patients might benefit from peripheral blood stem cells with their higher rates of engraftment. The indication for one or the other source according to patient or donor characteristics will need validation in prospective trials.

The same reasoning could apply to patients who receive low-dose or nonmyeloablative treatment, which is common now in patients older than 50 years. But “bone marrow may be recommended for all other patients,” said the authors, “especially those who are immunosuppressed owing to prior chemotherapy since they have a lower risk of graft rejection.” ■

Disclosure: Drs. Anasetti and Appelbaum reported no potential conflicts of interest.

Reference

1. Anasetti C, Logan BR, Lee SJ, et al: Peripheral-blood stem cells versus bone marrow from unrelated donors. N Engl J Med 367:1487-1496, 2012.