Acute myelogenous leukemia (AML) is the most common adult leukemia, characterized by the clonal expansion of immature myeloblasts initiating from rare leukemic stem (LS) cells. To understand the functional properties of human LS cells, we developed a primary human AML xenotransplantation model using newborn nonobese diabetic/severe combined immunodeficient/interleukin (NOD/SCID/IL)2r gamma(null) mice carrying a complete null mutation of the cytokine gamma c upon the SCID background. Using this model, we demonstrated that LS cells exclusively recapitulate AML and retain self-renewal capacity in vivo. They home to and engraft within the osteoblast-rich area of the bone marrow, where AML cells are protected from chemotherapy-induced apoptosis. Quiescence of human LS cells may be a mechanism underlying resistance to cell cycle-dependent cytotoxic therapy. Global transcriptional profiling identified LS cell-specific transcripts that are stable through serial transplantation. These results indicate the potential utility of this AML xenograft model in the development of novel therapeutic strategies targeted at LS cells.

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Cytomegalovirus (CMV) infection is a major infectious complication after allogeneic hematopoietic cell transplantation (allo-HSCT). Recently, it was reported that CMV reactivation is associated with a decreased risk of relapse in patients with acute myeloid leukemia (AML). The aim of this study was to evaluate the impact of early CMV reactivation on the incidence of disease relapse after allo-HSCT in a large cohort of patients. The Japan Society for Hematopoietic Cell Transplantation's Transplantation-Related Complication Working Group retrospectively surveyed the database of the Transplant Registry Unified Management Program at the Japan Society for Hematopoietic Cell Transplantation. Patients with AML (n = 1836), acute lymphoblastic leukemia (ALL, n = 911), chronic myeloid leukemia (CML, n = 223), and myelodysplastic syndrome (MDS, n = 569) who underwent their first allo-HSCT from HLA-matched related or unrelated donors between 2000 and 2009 and who survived without disease relapse until day 100 after transplantation were analyzed. Patients who received umbilical cord blood transplantation were not included. Patients underwent surveillance by pp65 antigenemia from the time of engraftment, and the beginning of preemptive therapy was defined as CMV reactivation. Cox proportional hazards models were used to evaluate the risk factors of relapse, nonrelapse, and overall mortality. CMV reactivation and acute/chronic graft-versus-host disease (GVHD) were evaluated as time-dependent covariates. CMV reactivation was associated with a decreased incidence of relapse in patients with AML (20.3% versus 26.4%, P = .027), but not in patients with ALL, CML, or MDS. Among 1836 patients with AML, CMV reactivation occurred in 795 patients (43.3%) at a median of 42 days, and 436 patients (23.7%) relapsed at a median of 221 days after allo-HSCT. Acute GVHD grades II to IV developed in 630 patients (34.3%). By multivariate analysis considering competing risk factors, 3 factors were significantly associated with a decreased risk of AML relapse and 1 factor with an increased risk of AML relapse: CMV reactivation (hazard ratio [HR], .77; 95% confidence interval [CI], .59 to .99), unrelated donor compared with related donor (HR, .59; 95% CI, .42 to .84), development of chronic GVHD (HR, .77; 95% CI, .60 to .99), and pretransplantation advanced disease status compared with standard disease status (HR, 1.99; 95% CI, 1.56 to 2.52). However, CMV reactivation was associated with increased nonrelapse mortality (HR, 1.60; 95% CI, 1.18 to 2.17) and overall mortality (HR, 1.37; 95% CI, 1.11 to 1.69). A beneficial effect of CMV reactivation on subsequent risk of relapse was observed in patients with AML but not in those with other hematological malignancies. However, this benefit was nullified by the increased nonrelapse mortality. The underlying mechanism is unclear; however, immunological activation against CMV reactivation plays an essential role in this association. Thus, immune augmentation treatment options, including vaccination and adopti...

Umbilical cord blood transplantation (CBT) is an alternative allogeneic haematopoietic stem cell transplantation (HSCT) strategy for patients with haematological diseases who do not have a matched related or unrelated donor and who need urgent transplantation. The value of CBT using myeloablative preparative regimens has already been confirmed among paediatric and adult patients (Laughlin et al, 2004;Rocha et al, 2004;Takahashi et al, 2004). However, conventional myeloablative preparative regimens are associated with significant morbidity and mortality, particularly in older patients or in those who have experienced extensive prior therapy or organ dysfunction associated with transplantation-related mortality. Various reduced-intensity preparative regimens that have been applied to such patients by several groups, including the authors of the present study, have proven feasible (Barker et al, 2003(Barker et al, , 2005Chao et al, 2004;Jacobsohn et al, 2004;Miyakoshi et al, 2004Miyakoshi et al, , 2007Yuji et al, 2005;Misawa et al, 2006;Ballen et al, 2007;Brunstein et al, 2007;Komatsu et al, 2007;Uchida et al, 2008).

The online version of this article has a Supplementary Appendix. BackgroundPatients with acute myeloid leukemia who are treated with conventional chemotherapy still have a substantial risk of relapse; the prognostic factors and optimal treatments after relapse have not been fully established. We, therefore, retrospectively analyzed data from patients with acute myeloid leukemia who had achieved first complete remission to assess their prognosis after first relapse. Design and MethodsClinical data were collected from 70 institutions across the country on adult patients who were diagnosed with acute myeloid leukemia and who had achieved a first complete remission after one or two courses of induction chemotherapy. ResultsAmong the 1,535 patients who were treated with chemotherapy alone, 1,015 relapsed. Half of them subsequently achieved a second complete remission. The overall survival was 30% at 3 years after relapse. Multivariate analysis showed that achievement of second complete remission, salvage allogeneic hematopoietic cell transplantation, and a relapse-free interval of 1 year or longer were independent prognostic factors. The outcome after allogeneic transplantation in second complete remission was comparable to that after transplantation in first complete remission. Patients with acute myeloid leukemia and cytogenetic risk factors other than inv(16) or t(8;21) had a significantly worse outcome when they did not undergo salvage transplantation even when they achieved second complete remission. ConclusionsWe found that both the achievement of second complete remission and the application of salvage transplantation were crucial for improving the prognosis of patients with acute myeloid leukemia in first relapse. Our results indicate that the optimal treatment strategy after first relapse may differ according to the cytogenetic risk.Key words: acute myeloid leukemia, allogeneic hematopoietic cell transplantation, first relapse, second remission, cytogenetic risk. 2010;95(11):1857-1864. doi:10.3324/haematol.2010 This is an open-access paper. Citation: Kurosawa S, Yamaguchi T, Miyawaki S, Uchida N, Sakura T, Kanamori H, Usuki K, Yamashita T, Okoshi Y, Shibayama H, Nakamae H, Mawatari M, Hatanaka K, Sunami K, Shimoyama M, Fujishima N, Maeda Y, Miura I, Takaue Y, and Fukuda T. Prognostic factors and outcomes of adult patients with acute myeloid leukemia after first relapse. Haematologica Prognostic factors and outcomes of adult patients with acute myeloid leukemia after first relapse