Progenitor cells purging: negative selection

Disease relapse after autologous bone marrow transplantation (ABMT) may arise from residual tumor in the recipient and/or from cancer cells that are reinfused. The aim of purging by negative selection is to remove tumor cells from the marrow without adversely affecting the engraftment potential of the normal cell. We report the results of a study on fifty-six patients (pts) with non Hodgkin's lymphoma or acute leukemia submitted to ABMT after immunomagnetobead (IMB) purging (11 pts), Maphosphamide purging (31 pts) and no purging (14 pts). The IBM procedure involved one incubation of 3 monoclonal antibodies (CD10, CD19 and CD22) and two incubations with magnetic beads (Dynabeads M-450). The median recovery of mononuclear cells and CFU-GM was 40% and 45% after IMB purging and 84% and 5% after Maphosphamide purging respectively. The rate of leukocyte, neutrophils and platelets recovery following ABMT was similar in the three groups of pts, although platelet recovery was slow in patients received graft purged with Maphosphamide. Our study confirms the clinical feasibility of the IMB procedure, but only randomized studies will be able to definitely address the question of the clinical utility of purging.