[Stem cell transplantation in multiple myeloma]

High-dose chemotherapy combined with autologous hematopoietic stem cell transplantation (ASCT) has brought about high complete remission rates (about 40%), reduction of transplant-related toxicity in the patients with multiple myeloma, and it has spread rapidly. Moreover, it has demonstrated that overall survival times of high-dose chemotherapy with ASCT are significantly more extended than conventional chemotherapy. The indications of transplantation should be determined on the basis of various prognostic factors and sensitivity of the induction chemotherapy, and it is important that a therapeutic strategy should take the timing of ASCT into consideration before induction therapy. However, some problems of tumor cell contamination in the peripheral stem progenitor graft and its contribution to relapse have arisen. Some new trials including positive selection of CD34+ cells within its grafts and double auto-transplantation are ongoing to solve these problems. If the patient is under 50 years of age and an HLA identical donor is available, an allogeneic bone marrow transplantation (allo-BMT) may be considered. However, the indication of allo-BMT should be carefully selected because the transplant-related mortality is high (about 40%), and allo-BMT is not superior to ASCT in overall survival. New trials with nonablative hematopoietic stem cell transplantation with donor lymphocyte infusions (DLI) to induce a graft-versus-myeloma (GVM) effect are awaited.