Is a graft-versus-leukemia effect required?
The existence of a GVL effect is now widely accepted. The contribution of this effect to the cure of malignancy is less well defined and may be quite variable in different systems. In the mouse a spontaneous B cell lymphoma can be cured following cell therapy alone, that is to say without the need to reduce the tumor with chemotherapy or radiotherapy, provided the lymphocytes include CD8+ cells. In patients who relapse with acute leukemia after an allogeneic transplant donor lymphocyte infusions may be totally ineffective. It is possible that the GVL or graft-versus-tumor effect, must be combined in most instances with tumor cell reduction, and therefore with chemoradiotherapy. Indeed, the original bone marrow transplant program is a combination of cytoreduction followed by stem cell engraftment and immune intervention, all in one. As conditioning programs become less intense, the need for early infusion of donor lymphocytes increases: this may carry the risk of acute GVHD and studies
