Impact of body-surface area on patients' outcome in younger adults with acute myeloid leukemia.

OBJECTIVES: Anthracyclines and cytarabine are cornerstones for intensive chemotherapy in acute myeloid leukemia (AML). The goals of this study were to comprehensively assess deviations from theoretical doses and the impact of body-surface area (BSA) on patients' characteristics, physicians' strategy, dose adjustment, and clinical outcome. METHODS: The GOELAMS 2001 phase III trial included 823 AML patients below 60 years of age. In the course of treatment, anthropomorphic parameters and chemotherapy doses were prospectively registered. RESULTS: Very high BSA (≥2.15 m2 ) was the factor most significantly associated with the physician's decision to reduce chemotherapy doses during induction and postremission therapy. Despite similar AML characteristics and therapeutic strategies, the very high BSA group exhibited a significantly worse survival (5-years OS of 27%) compared to the low (BSA≤1.5 m2 ), intermediate (1.5 m2

Bone marrow sites differently imprint dormancy and chemoresistance to T-cell acute lymphoblastic leukemia.

T-cell acute lymphoblastic leukemia (T-ALL) expands in various bone marrow (BM) sites of the body. We investigated whether different BM sites could differently modulate T-ALL propagation using in vivo animal models. We observed that mouse and human T-ALL develop slowly in the BM of tail vertebrae compared with the BM from thorax vertebrae. T-ALL recovered from tail BM displays lower cell-surface marker expression and decreased metabolism and cell-cycle progression, demonstrating a dormancy phenotype. Functionally, tail-derived T-ALL exhibit a deficient short-term ex vivo growth and a delayed in vivo propagation. These features are noncell-autonomous because T-ALL from tail and thorax shares identical genomic abnormalities and functional disparities disappear in vivo and in prolonged in vitro assays. Importantly tail-derived T-ALL displays higher intrinsic resistance to cell-cycle-related drugs (ie, vincristine sulfate and cytarabine). Of note, T-ALL recovered from gonadal adipose tissues or from cocultures with adipocytes shares metabolic, cell-cycle, and phenotypic or chemoresistance features, with tail-derived T-ALL suggesting adipocytes may participate in the tail BM imprints on T-ALL. Altogether these results demonstrate that BM sites differentially orchestrate T-ALL propagation stamping specific features to leukemic cells such as quiescence and decreased response to cell-cycle-dependent chemotherapy.

Uncoupling JAK2 V617F activation from cytokine-induced signalling by modulation of JH2 αC helix.

The mechanisms by which JAK2 is activated by the prevalent pseudokinase (JH2) V617F mutation in blood cancers remain elusive. Via structure-guided mutagenesis and transcriptional and functional assays, we identify a community of residues from the JH2 helix αC, SH2-JH2 linker and JH1 kinase domain that mediate V617F-induced activation. This circuit is broken by altering the charge of residues along the solvent-exposed face of the JH2 αC, which is predicted to interact with the SH2-JH2 linker and JH1. Mutations that remove negative charges or add positive charges, such as E596A/R, do not alter the JH2 V617F fold, as shown by the crystal structure of JH2 V617F E596A. Instead, they prevent kinase domain activation via modulation of the C-terminal residues of the SH2-JH2 linker. These results suggest strategies for selective V617F JAK2 inhibition, with preservation of wild-type function.

Oncogenic Drivers in Myeloproliferative Neoplasms: From JAK2 to Calreticulin Mutations.

During the past 10 years, major progress has been accomplished with the discovery of activating mutations that are associated with the vast majority of BCR-ABL negative human myeloproliferative neoplasms (MPNs). The identification in 2005 of JAK2 V617F triggered great interest in the JAK2-STAT5/STAT3 pathway. Discovery in 2006 of mutants of thrombopoietin receptor (TPO-R/MPL) and later on of mutants in negative regulators of JAK-STAT pathway led to the notion that persistent JAK2 activation is a hallmark of MPNs. In 2013, mutations in the gene coding for the chaperone calreticulin were reported in 20-30% of essential thrombocythemia and primary myelofibrosis patients. Here, we will address the question: what do we know about calreticulin that could help us understand its role in MPNs? In addition to oncogenic driver mutations, certain MPNs also exhibit epigenetic mutations. Targeting of both oncogenic drivers and epigenetic defects could be required for effective therapy.

Peripheral Blood Plasmacytoid Dendritic Cells at Day 100 Can Predict Outcome after Allogeneic Stem Cell Transplantation.

The rapidly increasing use of allogeneic stem cell transplantation (allo-SCT) emphasizes the need for identifying variables predictive of its outcome. Plasmacytoid dendritic cells (pDCs) play a major role in establishing immune competence and in several autoimmune diseases. Thus, we investigated whether pDCs might influence the outcome of patients after allo-SCT in 79 consecutive patients who underwent this procedure. pDCs were identified in the blood of patients at day 100 after allo-SCT by staining peripheral blood mononuclear cells for surface markers and intracellular cytokines and analyzing them on a flow cytometer. We found the pDC level at day 100 was not influenced by patient or graft characteristics, and only the absence of previous grades II to IV acute graft-versus-host disease was significantly associated with higher levels of blood pDCs after allo-SCT (OR, .67; 95% CI, .54 to .83; P = .0004). Using the median value of pDCs at day 100 to divide the patients into 2 distinct groups, we observed that a low pDC level was correlated with a worse overall survival (55% versus 86%, P = .007). In a multivariate analysis, only low pDC level (OR, 3.41; 95% CI, 1.19 to 9.79; P = .02) and older patient age (OR, 5.16; 95% CI, 1.15 to 23.14; P = .03) were significantly predictive of increased risk of death. We conclude that monitoring of pDC may be useful for patient management and may have a significant impact on the probability of a favorable outcome of allo-SCT.

Initial fluconazole prophylaxis may not be required in adults with acute leukemia or myelodysplastic/myeloproliferative disorders after reduced intensity conditioning peripheral blood stem cell allogeneic transplantation.

In the myeloablative transplant setting, the early use of fluconazole prophylaxis provides a benefit in overall survival. Recent changes in transplantation practices, including the use of peripheral blood stem cells (PBSC) and/or reduced intensity conditioning (RIC) regimen may have favorably impacted the epidemiology of invasive fungal infections (IFI) after allogeneic stem cell transplantation (allo-SCT). Yet, the impact of removing fluconazole prophylaxis after RIC PBSC allotransplant is ill known. Here, a retrospective analysis was performed comparing patients who received fluconazole as antifungal prophylaxis (n = 53) or not (n = 56) after allo-SCT for acute leukemia or myelodysplastic/myeloproliferative syndrome. Sixteen IFI were documented (14 %) at a median time of 103 days after transplantation, including eight before day +100, at a similar rate, whether the patients received fluconazole prophylaxis (13 %) or not (16 %). IFI were due mainly to Aspergillus species (87 %), and only two Candida-related IFI (13 %) were documented in the non-fluconazole group before day +100. The incidences of IFI (overall, before or after day +100) as well as 3-year overall and disease-free survival, non-relapse mortality, or acute and chronic graft-versus-host disease (GVHD) were similar between both groups. In conclusion, this study suggests that fluconazole may not be required at the initial phase of RIC allo-SCT using PBSC. This result has to be confirmed prospectively while Aspergillus prophylaxis should be discussed in this particular setting.

Interleukin-18 produced by bone marrow-derived stromal cells supports T-cell acute leukaemia progression.

Development of novel therapies is critical for T-cell acute leukaemia (T-ALL). Here, we investigated the effect of inhibiting the MAPK/MEK/ERK pathway on T-ALL cell growth. Unexpectedly, MEK inhibitors (MEKi) enhanced growth of 70% of human T-ALL cell samples cultured on stromal cells independently of NOTCH activation and maintained their ability to propagate in vivo. Similar results were obtained when T-ALL cells were cultured with ERK1/2-knockdown stromal cells or with conditioned medium from MEKi-treated stromal cells. Microarray analysis identified interleukin 18 (IL-18) as transcriptionally up-regulated in MEKi-treated MS5 cells. Recombinant IL-18 promoted T-ALL growth in vitro, whereas the loss of function of IL-18 receptor in T-ALL blast cells decreased blast proliferation in vitro and in NSG mice. The NFKB pathway that is downstream to IL-18R was activated by IL-18 in blast cells. IL-18 circulating levels were increased in T-ALL-xenografted mice and also in T-ALL patients in comparison with controls. This study uncovers a novel role of the pro-inflammatory cytokine IL-18 and outlines the microenvironment involvement in human T-ALL development.

Allogeneic hematopoietic stem cell transplantation following reduced-intensity conditioning regimen in children: a single-center experience.

This single-center retrospective study reported the outcome of 19 children treated with a reduced-intensity conditioning (RIC) regimen prior to allogeneic stem cell transplantation (allo-SCT), for hematologic malignancies (n = 17), bone marrow failure (n = 1), and neuroblastoma (n = 1). Children were ineligible for standard myeloablative conditioning because of severe comorbidities (n = 9), a previous auto or allo-SCT (n = 7) or a prior history of extensive chemotherapy (n = 3). All patients underwent a fludarabine-based RIC regimen, and received grafts from matched-related donors (n = 5), match-unrelated donors (n = 6), or unrelated cord blood (UCB, n = 8). In this series, two patients treated with UCB failed to engraft and 63% achieved full donor chimerism at day 100 after allo-SCT. With a median follow-up of 537 d (range, 115-4136), treatment-related mortality was 16% and overall survival was 47%. The principal cause of death was disease relapse (n = 7). Acute graft versus host disease (GVHD) occurred in 53% of patients, while only 10% developed extensive chronic GVHD. Overall, results from this series suggest that RIC allo-SCT can be a valid alternative treatment option in unfit children with malignant hematological diseases. Prospective studies are needed to enlarge pediatric experience in this domain and better identify those children more suitable for a RIC allo-SCT approach.

Fludarabine, antithymocyte globulin, and very low-dose busulfan for reduced-intensity conditioning before allogeneic stem cell transplantation in patients with lymphoid malignancies.

This retrospective report compared the results of a reduced-intensity conditioning (RIC) regimen including fludarabine (Flu), and very low-dose oral busulfan (BU) (4 mg/kg total dose) in combination with antithymocyte globulin (ATG) (Flu/ATG/BU) to the classical Flu and low-dose total body irradiation (TBI) (2 Gy) regimen (Flu/TBI) in patients with lymphoid malignancies. With a median follow-up of 42 months, the cumulative incidence of transplant-related mortality (TRM) was 22% in the Flu/ATG/BU group versus 41% in the Flu/TBI group (P = .09). Grade 3-4 acute graft-versus-host disease (aGVHD) and extensive chronic GVHD (cGVHD) incidents were 15% versus 44% (P = .006), and 12% versus 58% (P = .0003), in the Flu/ATG/BU group versus the Flu/TBI group, respectively. The Kaplan-Meier estimate of overall survival (OS) at 2 years was comparable between both groups (71%; 95% confidence interval [CI] 58%-86%, in the Flu/ATG/BU group vs 60%; 95% CI 44%-83%, in the Flu/TBI group, P = .20). The estimate of progression-free survival (PFS) was 63% (95% CI 50%-80%) in the Flu/ATG/BU group versus 52% (95% CI, 36%-76%) in the Flu/TBI group (P = .18), suggesting that reduced-intensity conditioning (RIC) based on Flu, very low-dose BU, and ATG has the potential to induce long-term remissions in patients with lymphoid malignancies.

Infectious complications after unrelated umbilical cord blood transplantation in adult patients with hematologic malignancies.

Unrelated umbilical cord blood (UCB) is being increasingly used as an alternative stem cell source for allogeneic stem cell transplantation (allo-SCT). This retrospective study assessed infectious complications occurring in adult patients after UCB transplantation (UCBT). 31 patients received a single (n=4) or double UCBT (n=27) with a median dose of 4.7x10(7) nucleated cells/kg (range: 2.4-7.7). Patients received either a reduced-intensity conditioning (RIC; n=23) or a standard myeloablative (MA) regimen (n=8). The cumulative incidence of neutrophil recovery was 90%. Neutrophil recovery was achieved at a median time of 24 (range: 8-60) days after UCBT. The cumulative incidences of bacterial, fungal, and parasitic infections were, respectively, 16%, 10%, and 6%. Bloodstream infections were neither lethal nor required any intensive care therapy. Similarly, invasive fungal infections and parasitic infections did not cause any death in those patients with sustained engraftment. Although the cumulative incidence of cytomegalovirus (CMV) recurrence was 21%, no CMV disease was observed. With a median follow-up of 10 (range: 3-30) months, 10 patients have died (relapse, n=5; nonrelapse mortality, [NRM] n=5). Overall, the cumulative incidence of infectious-related mortality (IRM) was 8%. In conclusion, this data suggests that UCBT can be performed in adult patients with hematologic malignancies with an acceptable incidence of IRM provided a sufficient dose of nucleated cells is infused to the patient.