Allogeneic hematopoietic stem cell transplantation for multiple myeloma: curative but not the standard of care.

PURPOSE OF REVIEW: Despite the curative potential of allogeneic hematopoietic stem cell transplantation (allo HSCT) for patients with multiple myeloma, and reduction of transplant-related mortality with nonmyeloablative transplant approaches, rates of acute and chronic graft-versus-host disease and disease progression remain high. It is unclear if nonmyeloablative transplants are more effective than autologous (auto). Novel promising drugs and maintenance treatment strategies following auto SCT may also delay allo transplantation. In this review, we summarize the emerging data on allo HSCT and provide suggestions for its optimal role in the treatment of myeloma.

RECENT FINDINGS: Large cooperative group studies comparing allo HSCT with auto SCT as frontline therapy have been performed with reduced intensity conditioning regimens using unmanipulated peripheral blood stem cells from human leukocyte antigen (HLA)-compatible donors and standard calcineurin inhibitor graft-versus-host disease prophylaxis. Two recent reports show conflicting data. Although the Blood and Marrow Transplant Clinical Trials Network 0102 study demonstrated no progression-free or overall survival advantage at 3 years, a European study demonstrated superior 5-year outcome after auto/HLA-matched sibling allo HSCT compared with tandem auto SCT in previously untreated multiple myeloma patients. The advent of maintenance therapy could potentially improve outcomes of both transplant types.

SUMMARY: High rates of acute and chronic graft-versus-host disease currently limit the implementation of nonmyeloablative allo HSCT. Novel approaches are required so that patients with myeloma can undergo allo HSCT before resistance develops to standard drug combinations.