Autologous transplantation with tumor-free graft: a model for multiple myeloma patients

The importance of obtaining a tumor-free graft for autologous transplantation in cancer patients has been debated extensively in the last decade and is still unresolved largely because it is believed that relapse is more likely to originate from the host and not from the graft. This is in spite of recent indications that the main source of relapse is the graft. In this review article we bring forward evidence that the currently used grafts, whether from peripheral blood or bone marrow, harbour significant number of tumor cells before and even after purging with currently available purging protocols. We believe that the use of a tumor-free graft is the only way to obtain a valid assessment of the efficacy of high dose radio-chemotherapy, and is the only methodology to increase the probability to achieve long term survival following AT. Accordingly, we describe in detail a procedure to obtain a tumor-free graft, designed for the treatment of multiple myeloma patients based on flow-sorting of CD34+ stem cells.