New developments in bone marrow transplantation.

A better understanding of the immunobiology after transplantation and of the available recombinant cytokines that enhance hematopoietic reconstitution following autologous and allogeneic bone marrow transplantation is likely to result in safer application of bone marrow transplantation. Residual tumor cells escaping chemotherapy or chemoradiotherapy given in the course of autologous and allogeneic bone marrow transplantation are still a barrier to complete eradication of malignancy. Recent experiments in animal models of human disease suggest that minimal residual disease can be controlled by an innovative therapy consisting of the administration of cytokines such as recombinant human interleukin-2 and interferon-alpha. Moreover, graft versus leukemia-like effects are induced in conjunction with autologous and allogeneic bone marrow transplantation by administration of allogeneic immunocompetent lymphocytes and recombinant interleukin-2 following bone marrow transplantation and especially by combined administration of allogeneic lymphocytes and recombinant interleukin-2. Similar approaches are currently being investigated in humans with encouraging preliminary results. Overall, our data suggest that eradication of the last tumor cell is neither feasible nor necessary for achieving operational cure. Control of minimal residual disease by activation of anticancer effector cells today seems closer than ever and we are optimistic that further advances in immunotherapy will be applicable to clinical practice in the near future.