Transplantation with 2-5 ؋ 10 6 mobilized CD34 ؉ cells/kg body weight lowers transplantation costs and mortality. Mobilization is most commonly performed with recombinant human G-CSF with or without chemotherapy, but a proportion of patients/donors fail to mobilize sufficient cells. BM disease, prior treatment, and age are factors influencing mobilization, but genetics also contributes. Mobilization may fail because of the changes affecting the HSC/progenitor cell/BM niche integrity and chemotaxis. Poor mobilization affects patient outcome and increases resource use. Until recently increasing G-CSF dose and adding SCF have been used in poor mobilizers with limited success. However, plerixafor through its rapid direct blockage of the CXCR4/CXCL12 chemotaxis pathway and synergy with G-CSF and chemotherapy has become a new and important agent for mobilization. Its efficacy in upfront and failed mobilizers is well established.To maximize HSC harvest in poor mobilizers the clinician needs to optimize current mobilization protocols and to integrate novel agents such as plerixafor. These include when to mobilize in relation to chemotherapy, how to schedule and perform apheresis, how to identify IntroductionHematopoietic stem cell transplantation (HSCT) has revolutionized the curative approach to a number of malignancies and BM failure syndromes by providing hematopoietic and immune rescue after high-dose cytoreductive therapy and, in allogeneic transplantations, graft-versus-tumor effect. [1][2][3][4] The term "mobilization" was first used to describe a 4-fold increase of circulating myeloid progenitors (granulocyte macrophage CFU [CFU-GM]) after the administration of endotoxin to healthy volunteers in 1977. 5 High levels of CFU-GM after recovery from myelosuppressive chemotherapy in humans was first described in 1976. 6 However, it was not until the 1980s that the use of chemotherapy-mobilized HSCs for transplantation was established. [7][8][9] Subsequently, a single high-dose cyclophosphamide was developed as a generic mobilizer. 10 Prof Metcalf led the study that showed the potential of G-CSF in mobilization. 11 Subsequently, 2 Australian centers in Melbourne and Adelaide showed for the first time the use of G-CSF-mobilized HSCs for transplantation, 12 and reports of combined G-CSF and chemotherapy mobilization soon followed. 13 Now, virtually all autologous and three-quarters of allogeneic transplantations are performed with mobilized HSCs (CIBMTR reports). 14,15 The cell dose effect of HSCT describes a threshold of HSCs that, when transplanted, is associated with rapid and sustained blood count recovery. 16 The benefits of rapid recovery are reduced hospitalization, blood product usage, and infections. 12,17 The minimum threshold for autologous transplantation is currently defined as 2 ϫ 10 6 CD34 ϩ cells/kg body weight (BW). 18 Many centers use a minimum of 3 ϫ 10 6 CD34 ϩ cells/kg BW for myeloablative and nonmyeloablative allogeneic and matched unrelated transplantations. Furthermore, Ͼ 5 ϫ 10 6 CD3...

Background:Central nervous system (CNS) relapse in diffuse large B-cell lymphoma (DLBCL) is a devastating complication; the optimal prophylactic strategy remains unclear.Methods:We performed a multicentre, retrospective analysis of patients with DLBCL with high risk for CNS relapse as defined by two or more of: multiple extranodal sites, elevated serum LDH and B symptoms or involvement of specific high-risk anatomical sites. We compared three different strategies of CNS-directed therapy: intrathecal (IT) methotrexate (MTX) with (R)-CHOP ‘group 1' R-CHOP with IT MTX and two cycles of high-dose intravenous (IV) MTX ‘group 2' dose-intensive systemic antimetabolite-containing chemotherapy (Hyper-CVAD or CODOXM/IVAC) with IT/IV MTX ‘group 3'.Results:Overall, 217 patients were identified (49, 125 and 43 in groups 1–3, respectively). With median follow-up of 3.4 (range 0.2–18.6) years, 23 CNS relapses occurred (12, 10 and 1 in groups 1–3 respectively). The 3-year actuarial rates (95% CI) of CNS relapse were 18.4% (9.5–33.1%), 6.9% (3.5–13.4%) and 2.3% (0.4–15.4%) in groups 1–3, respectively (P=0.009).Conclusions:The addition of high-dose IV MTX and/or cytarabine was associated with lower incidence of CNS relapse compared with IT chemotherapy alone. However, these data are limited by their retrospective nature and warrant confirmation in prospective randomised studies.

No abstract