Long-Term Survival after Transplantation in Patients with Chronic Myeloid Leukemia from HLA-Compatible Unrelated Donors: May the Stem Cell Source Influence the Outcome?

Introduction

Allogeneic hematopoietic stem cell transplantation (alloSCT) is curative therapy for chronic myeloid leukemia (CML), but its long-term outcomes regarding graft sources are not well described.

Results

Here the outcomes of CML after alloSCT with bone marrow (BM, n=134) were compared to those of peripheral blood stem cell (PBSC, n=172) in the HLA-compatible unrelated donor setting. Patients were transplanted in 1^st CP (Bone marrow transplantation (BMT), n=100, and Peripheral blood stem cell transplantation (PBSCT), n=103), in >1^st CP (BMT, n=24, and PBSCT, n=52) and in blast crises (BMT, n=10, and PBSCT, n=17). Median follow-up were 54 months after BMT and 106 months after PBSCT. No significant differences were found in the incidence of acute and chronic graft-versus-host disease (GvHD) between both study-groups. The 5-year estimated probability of hematological relapse was 11% for patients in 1^st CP CML and 49% for patients in advanced disease after BMT (p<0.001) and 18% for patients in 1^st CP and 22% for patients in advanced disease after PBSCT (p= n.s.). The estimated probability for 10-year overall survival (OS) for patients in 1^st CP and patients in advanced stages of CML were 58% and 20% after BMT and 59% and 52% after PBSCT, respectively (not significant for 1^st CP and p<0.0001 for advanced stages). In the multivariate analysis patient age (age > 40 years), disease stage, acute GvHD, chronic GvHD and immunprophylaxis with use of ATG influenced OS significantly. For leukemia-free survival, the following risk factors were significantly in the multivariate analysis, graft source, patient age, gender constellation, disease stage, acute GvHD and chronic GvHD.

Conclusions

This large trial show significant difference between transplant recipients who received PBSC and those who received BM from unrelated donor. These finding may influence the selection of a graft source for alloSCT from unrelated donor.