Early assessment of donor CD34+ positive cells chimerism after allogeneic stem cell transplantation in acute myeloid leukemia/myelodysplastic syndrome patients – pilot study

Introduction. In high-risk acute myeloid leukaemia/myelodysplastic syndrome patients, relapse remains the major cause of treatment failure after allogeneic stem cell transplantation (alloSCT). The investigation of lineage-specific chimerism has become an important tool in the management of patients during the post-transplant period. Aim. Early assessment of lineage specific chimerism in patients who underwent allogeneic hematopoietic stem cell transplantation. Material and methods. 55 patients with acute myeloid leukemia and myelodysplastic syndrome who underwent alloSCT were included in the study. Flow cytometric analysis and cell sorting was performed in bone marrow collected at day 30 after alloSCT. For the purpose of this study we analyzed sorted immature progenitor cells (CD34+CD19-) using STR method. Results. All patients who relapsed presented with lower donor chimerism in CD34+ positive cells in comparison to the group of patients in remission of the underlying disease. Median value of chimerism in CD34+ positive cells in the group of patients who relapsed was 14.5% (range 0-51%), whereas in patients who remained in remission of the underlying disease, chimerism in CD34+ never fell below 97% (median 100%, range 97-100%). All relapses occurred during the first year after alloSCT. Median time to relapse was 107 days (range 28-323). Conclusions. Early assessment of chimerism in CD34+ cells sorted out of bone marrow is a sensitive technique to detect residual or reoccurring disease after allogeneic SCT. The assessment of donor chimerism in CD34+ cells in day +30 after alloSCT seems to be relevant in post-transplant care of high risk patients.