The role of mini-allotransplants in the treatment of solid tumors

Abstract

Allogeneic stem cell transplantations (SCTs) have been inclinical use for several decades. First they were used astreatment following nuclear accidents, subsequently the mainapplication became the treatment of patients with leukemiafollowed by other hematological malignant diseases [1].Based on many clinical studies and supported by much datafrom transplant registries like the International Bone MarrowTransplant Registry (IBMTR) and the European Group forBlood and Marrow Transplantation (EBMT) it is now clearthat using allogeneic SCTs (using stem cells from a donor) cancure many patients with hematological malignancies [1–4].This is even the case in patients where other treatment modal-ities are not curative [5].Using HLA identical sibling donors, 6-year survival inpatients with acute or chronic myeloid leukemia is about 60%.In patients with acute lymphocytic leukemia it is about 50%and in myelodysplastic syndromes about 55% (refractoryanemia with or without ringsideroblasts) and about 30%for patients with RAEB (refractory anemia with excess ofblast) and RAEB-T (RAEB in transformation) subtypes (dataIBMTR).Also in patients with aplastic anemia [1, 2, 6] and low gradenon-Hodgkin’s lymphoma [7, 8] allogeneic transplantationmay be curative. In patients with multiple myeloma the poten-tial for cure is less clear [9].Although cure can be achieved using allogeneic trans-plantation, the major drawback of this procedure is itstreatment-related mortality due to the high-dose therapy andan immunological anti-host effect [10]. However, there is nowmuch evidence that this immunological anti-host effect alsoimplies an immunological anti-tumor effect [5, 10–12].