In pursuit of the allo-immune response in multiple myeloma: where do we go from here?

AlloSCT is a potentially curative procedure for haematological malignancies and marrow failure syndromes. However, unlike leukaemia and lymphoproliferative disorders, AlloSCT has yet to find its place in the clinical management of patients with multiple myeloma. AlloSCT in multiple myeloma is associated with a high procedure related mortality (TRM up to 35%) when full-intensity conditioning is used and only up to 36% of cases show long-term disease-free survival. The introduction of reduced intensity conditioning AlloSCT, more recently following an autologous SCT, has reduced the TRM to <20%, but there is an associated increased relapse risk. The use of donor lymphocyte infusions and novel biological agents (thalidomide, bortezomib), alone or together, can be effective in relapsed and even persistent disease post-AlloSCT. Thus, in pursuit of the putative graft-versus-myeloma effect, we need to consider the whole patient management pathway both preceding (depth of response to novel agents) and post-AlloSCT, to minimize the toxicity while harnessing the adoptive immunotherapy effect. This review sets out what we have learned to date from the clinical research studies in this area, examines concepts for improving the outcomes of AlloSCT and proposes a potential direction of clinical investigation to maximize the effect of AlloSCT in multiple myeloma.