Accelerated Allogeneic Haemopoietic Engraftment after Preceding Rituximab-Therapy

The chimeric monoclonal anti-CD20 antibody rituximab and the graft- versus-leukaemia/lymphoma effect after allogeneic stem cell transplantation have improved therapy of lymphatic malignancies during the last decade. In addition, successful therapy of chronic graft-versus-host disease after stem cell transplantation with rituximab has been published. Other investigators correlated prolonged neutropenia after autologous stem cell transplantation with prior rituximabtherapy. To address the question, if rituximab pre- treatment prior to transplantation diminishes the graft versus lymphoma effect afterwards and can prolong engraftment of allogeneic haemopoiesis, we retrospectively analysed data from 34 patients allografted for lymphoid malignancies. 19 patients had received at least one course of rituximab prior to allogeneic stem cell transplantation and 15 did not. Both groups matched very good. Patients with rituximab pre-treatment engrafted with 1 leukocyte/nl significantly faster than patients without prior rituximab therapy (12 days [median, range 1-32] vs. 18 days [median, range 12-31], p < 0,005). Engraftment of platelets (PLT) occurred as well faster after rituximab pre-treatment. The differences were significant for all three steps [20PLT/nl: 11,5 days (median, range 1-28) vs. 27 days (median, range 11-54) p < 0,001; 50PLT/nl: 16,5 days (median, range 11-37) vs. 42 days (median, range 22-70) p < 0,001; 100PLT/nl: 22,5 days (median, range 13-52) vs. 60 days (median, range 25-117) p < 0,005]. The mechanism leading to faster engraftment remains unclear so far. Preceding therapy with rituximab had no influence on event-free survival, overall survival, or manifestation freedom from graft-versus-host disease (GVHD) after allogeneic stem cell transplantation. Patients with GVHD had a significantly better overall survival (p=0,0001) comparing to patients without. In conclusion, this investigation gives no hint for a suppression of GvH and GvL effects by rituximab administration prior to allogeneic stem cell transplantation. In addition, in contrast to results published for autologous stem cell transplantation, no detrimental effects on establishment of graft haemopoiesis after allogeneic stem cell transplantation by preceding rituximab therapy were found.