III. Role of allotransplantation for non-Hodgkin lymphoma and chronic lymphocytic leukemia

With an incidence rate of 15 per 100 000, non-Hodgkin’s lymphoma (NHL) accounts for the majority of lymphoid neoplasms in Europe [1]. Although in most of these entities the results of first-line therapy are becoming more and more effective, allogeneic stem cell transplantation (alloSCT) is increasingly used in NHL. Numbers of NHL allotransplants registered with the European Society for Blood and Marrow Transplantation (EBMT) grew from 2000 to 2009 as follows: chronic lymphocytic leukemia (CLL) 160%, follicular lymphoma (FL) 62%, mantle cell lymphoma (MCL) 89%, diffuse large cell lymphoma (DLCL) 54%, T-cell lymphoma (TCL) 339%. With 354 transplants performed, CLL was the leading alloSCT indication among these five entities registered with the EBMT in 2009, followed by TCL (211), FL (199), DLCL (171) and MCL (136) (EBMT, data on file). In contrast to autografting, where stem cells are re-infused to compensate for the hematopoietic toxicity of single-hit high-dose therapy, alloSCT represents a fundamentally different biological principle, namely the ignition of a permanent immunotherapeutic process within the recipient: the graft-versus-lymphoma (GVL) effect. Thus, three crucial questions need to be addressed for each NHL subtype in order to assess the potential benefit of alloSCT: (i) is GVL effective? (ii) can it be translated into therapeutic benefit with acceptable toxicity? (iii) which indications result from the individual efficacy/toxicity ratio? The present overview attempts to briefly address these three key questions for the main NHL subsets CLL, FL, MCL, DLCL and TCL. Since some general issues, such as GVL/graftversus-host disease (GVHD) principles and toxicity patterns in the reduced intensity conditioning (RIC) era, are best investigated in CLL, this entity will be described in more depth.