Improved Survival with Transplants of Peripheral Blood Stem Cells

SEATTLE—A phase III study of 168 patients with hematologic malignancies found that those receiving peripheral blood stem cells (PBSC) had fewer relapses, fewer deaths, and faster engraftment than those receiving bone marrow, without a greater risk of acute graft-vs-host disease (GVHD). Both the PBSC and bone marrow transplants were from HLA identical sibling donors. William Bensinger, MD, a researcher in the Clinical Research Division at the Fred Hutchinson Cancer Research Center reported the study at the ASH meeting.

Dr. Bensinger and his collaborators at the City of Hope Medical Center and Stanford University started the prospective multicenter trial in 1996 to compare two features of PBSC and bone marrow transplants—engraftment time and acute GVHD. If it could be shown that PBSC transplants worked as well for recipients as bone marrow transplants do, then donors could be spared the pain as well as the anesthesia required with bone marrow transplantation.

The study included 168 patients with hematologic cancers who had human leukocyte antigen–identical relatives able to donate either PBSC or bone marrow. Dr. Bensinger reported on the 138 patients who received their transplants by February 1999. These patients had a median follow-up of 21 months.

No Major GVHD Variance

The course of the patients’ recovery varied significantly between treatment groups. Neutrophil engraftment took place 6 days earlier among PBSC recipients than among bone marrow recipients (15 days vs 21 days). Platelet engraftment also occurred earlier, in this case, by 8 days (13 days for PBSC vs 21 days for bone marrow).

Relapse rates were higher among bone marrow recipients. Two-year survival among patients receiving PBSC was 71%, significantly higher than the 51% survival rate among marrow recipients. The gap in survival rates between PBSC and marrow recipients was wider in patients with advanced disease than in patients with less-advanced cancers.

One factor that did not differ significantly between treatment groups was GVHD. Grade 3 or 4 acute GVHD occurred in 16% of PBSC recipients and 13% of marrow recipients. Chronic GVHD had a cumulative incidence of 38% in PBSC recipients and 28% in bone marrow recipients, which was not considered statistically significant.

Dr. Bensinger concluded: “the use of peripheral blood stem cells was associated with significantly higher survival and disease-free survival, more-rapid engraftment, and equivalent acute graft-vs-host disease.”