Peripheral-blood stem cells versus bone marrow from unrelated donors

Abstract

Background: Randomized trials have shown that the transplantation of filgrastim-mobilized peripheral-blood stem cells from HLA-identical siblings accelerates engraftment but increases the risks of acute and chronic graft-versus-host disease (GVHD), as compared with the transplantation of bone marrow. Some studies have also shown that peripheral-blood stem cells are associated with a decreased rate of relapse and improved survival among recipients with high-risk leukemia.

Methods: We conducted a phase 3, multicenter, randomized trial of transplantation of peripheral-blood stem cells versus bone marrow from unrelated donors to compare 2-year survival probabilities with the use of an intention-to-treat analysis. Between March 2004 and September 2009, we enrolled 551 patients at 48 centers. Patients were randomly assigned in a 1:1 ratio to peripheral-blood stem-cell or bone marrow transplantation, stratified according to transplantation center and disease risk. The median follow-up of surviving patients was 36 months (interquartile range, 30 to 37).

Results: The overall survival rate at 2 years in the peripheral-blood group was 51% (95% confidence interval [CI], 45 to 57), as compared with 46% (95% CI, 40 to 52) in the bone marrow group (P=0.29), with an absolute difference of 5 percentage points (95% CI, -3 to 14). The overall incidence of graft failure in the peripheral-blood group was 3% (95% CI, 1 to 5), versus 9% (95% CI, 6 to 13) in the bone marrow group (P=0.002). The incidence of chronic GVHD at 2 years in the peripheral-blood group was 53% (95% CI, 45 to 61), as compared with 41% (95% CI, 34 to 48) in the bone marrow group (P=0.01). There were no significant between-group differences in the incidence of acute GVHD or relapse.

Conclusions: We did not detect significant survival differences between peripheral-blood stem-cell and bone marrow transplantation from unrelated donors. Exploratory analyses of secondary end points indicated that peripheral-blood stem cells may reduce the risk of graft failure, whereas bone marrow may reduce the risk of chronic GVHD. (Funded by the National Heart, Lung, and Blood Institute-National Cancer Institute and others; ClinicalTrials.gov number, NCT00075816.).

Figure 1. Survival after Randomization in the Intention-to-Treat Analysis

The P value is from a stratified binomial comparison at the 2-year point. The P value from a stratified log-rank test was also not significant. A total of 75 patients in each group were still alive at 36 months.

Figure 2. Outcomes after Transplantation, According to Study Group

Panel A shows the rate of overall survival, and Panel B the rate of disease-free survival. Panel C shows the incidence of death unrelated to relapse. Panel D shows the incidence of relapse. Panel E shows the incidence of neutrophil engraftment (>500 neutrophils per cubic millimeter), and Panel F the incidence of platelet engraftment (>20,000 platelets per cubic millimeter, without platelet transfusion during the prior 7 days). Panel G shows the incidence of acute graft-versus-host disease (GVHD) of grades II to IV, and Panel H the incidence of chronic GVHD. P values for the between-group differences in overall survival (Panel A) and disease-free survival (Panel B) are from a stratified binomial comparison at the 2-year point; P values from stratified log-rank tests for survival and disease-free survival were also not significant. All other P values shown are from stratified log-rank tests.