Reduced intensity allogeneic stem cell transplantation in multiple myeloma.

Allogeneic stem cell transplantation (SCT) is an attractive form of immunotherapy for multiple myeloma (MM) due to well documented graft versus myeloma activity. High transplant related mortality with allogeneic SCT is currently the major limitation to wider use of this potentially curative modality. Mortality can be significantly reduced through the use of lower intensity conditioning regimens which allow engraftment of allogeneic stem cells. This comes at a cost, however, of higher rates of disease progression and relapse. Because allografting is currently the only modality with potential for cure, further studies designed to improve the therapeutic index of allografts are warranted. These include the use of intermediate intensity, yet still non-myeloablative conditioning regimens, autologous transplant performed just prior to allografting, peripheral blood cells, graft engineering to improve the graft versus myeloma activity while reducing GVHD, post transplant maintenance and targeted conditioning therapies such as bone seeking radioisotopes.