Pregnancy in women with sickle cell disease is associated with adverse maternal and neonatal outcomes. Studies assessing the effects of prophylactic red blood cell transfusions on these outcomes have drawn inconsistent conclusions. The objective of this systematic review was to assess the effect of prophylactic compared with on-demand red blood cell transfusions on maternal and neonatal outcomes in women with sickle cell disease. A systematic search of several medical literature databases was conducted. Twelve studies involving 1291 participants met inclusion criteria. The studies had moderate to high risk of bias. Meta-analysis demonstrated that prophylactic transfusion was associated with a reduction in maternal mortality (7 studies, 955 participants; odds ratio [OR], 0.23; 95% confidence interval [CI], 0.06-0.91), vaso-occlusive pain episodes (11 studies, 1219 participants; OR, 0.26; 95% CI, 0.09-0.76), pulmonary complications (9 studies, 1019 participants; OR, 0.25; 95% CI, 0.09-0.72), pulmonary embolism (3 studies, 237 participants; OR, 0.07; 95% CI, 0.01-0.41), pyelonephritis (6 studies, 455 participants; OR, 0.19; 95% CI, 0.07-0.51), perinatal mortality (8 studies, 1140 participants; OR, 0.43; 95% CI, 0.19-0.99), neonatal death (5 studies, 374 participants; OR, 0.26; 95% CI, 0.07-0.93), and preterm birth (9 studies, 1123 participants; OR, 0.59; 95% CI, 0.37-0.96). Event rates for most of the results were low. Prophylactic transfusions may positively impact several adverse maternal and neonatal outcomes in women with sickle cell disease; however, the evidence stems from a relatively small number of studies with methodologic limitations. A prospective, multicenter, randomized trial is needed to determine whether the potential benefits balance the risks of prophylactic transfusions.

Monoclonal B-cell lymphocytosis (MBL) is a precursor of chronic lymphocytic leukemia (CLL). Observations of MBL in blood donors raise concern that transmitted MBL may cause recipient CLL. Using a database with health information on 1.5 million donors and 2.1 million recipients, we compared CLL occurrence among 7413 recipients of blood from 796 donors diagnosed with CLL after donation cessation, and among 80, 431 recipients of blood from 7477 matched CLL-free donors. During follow-up, 12 and 107 cases of CLL occurred among the exposed and unexposed recipients, respectively, yielding a relative risk of 0.94 (95% confidence interval, 0.52-1.71). Analyses using the entire database showed no evidence of CLL clustering among recipients of blood from individual donors. In conclusion, when donor MBL was approximated by subsequent donor CLL diagnosis, data from 2 countries' entire computerized transfusion experience over more than 30 years indicate that MBL/CLL transmission does not contribute importantly to recipient CLL risk.

Site-specific genome editing provides a promising approach for achieving long-term, stable therapeutic gene expression. Genome editing has been successfully applied in a variety of preclinical models, generally focused on targeting the diseased locus itself; however, limited targeting efficiency or insufficient expression from the endogenous promoter may impede the translation of these approaches, particularly if the desired editing event does not confer a selective growth advantage. Here we report a general strategy for liver-directed protein replacement therapies that addresses these issues: zinc finger nuclease (ZFN) -mediated site-specific integration of therapeutic transgenes within the albumin gene. By using adeno-associated viral (AAV) vector delivery in vivo, we achieved long-term expression of human factors VIII and IX (hFVIII and hFIX) in mouse models of hemophilia A and B at therapeutic levels. By using the same targeting reagents in wild-type mice, lysosomal enzymes were expressed that are deficient in Fabry and Gaucher diseases and in Hurler and Hunter syndromes. The establishment of a universal nuclease-based platform for secreted protein production would represent a critical advance in the development of safe, permanent, and functional cures for diverse genetic and nongenetic diseases.

Acute lymphoblastic leukemia (ALL) cells reside in the bone marrow microenvironment which nurtures and protects cells from chemotherapeutic drugs. The disruption of cell-cell communication within the leukemic niche may offer an important new therapeutic strategy. Tunneling nanotubes (TNTs) have been described as a novel mode of intercellular communication, but their presence and importance in the leukemic niche are currently unknown. Here, we show for the first time that primary B-cell precursor ALL (BCP-ALL) cells use TNTs to signal to primary mesenchymal stromal cells (MSCs). This signaling results in secretion of prosurvival cytokines, such as interferon-γ-inducible protein 10/CXC chemokine ligand 10, interleukin 8, and monocyte chemotactic protein-1/CC chemokine ligand 2. A combination of TNT-disrupting conditions allows us to analyze the functional importance of TNTs in an ex vivo model. Our results indicate that TNT signaling is important for the viability of patient-derived B-cell precursor ALL cells and induces stroma-mediated prednisolone resistance. Disruption of TNTs significantly inhibits these leukemogenic processes and resensitizes B-cell precursor ALL cells to prednisolone. Our findings establish TNTs as a novel communication mechanism by which ALL cells modulate their bone marrow microenvironment. The identification of TNT signaling in ALL-MSC communication gives insight into the pathobiology of ALL and opens new avenues to develop more effective therapies that interfere with the leukemic niche.

In this issue of Blood, Gros et al report that glycoprotein VI (GPVI) promotes the proinflammatory role of platelets by increasing neutrophil secretion and toxicity while at the same time repairing the vascular damage inflicted by neutrophil activation, thereby maintaining vascular integrity. Significantly, this effect is independent of hemostasis.

In this issue of Blood, Barete et al report the safety and efficacy of cladribine in 68 adult patients with mastocytosis.

In this issue of Blood, Dietrich et al make the first observation of the presence of deleterious CDKN1B mutation in 16% of patients with hairy cell leukemia (HCL). Furthermore, in the majority of patients, the CDKN1B mutation was clonal, suggesting that this mutation plays a role in the pathogenesis of HCL.

In this issue of Blood, Junker et al delineate a novel signaling axis involving miR-21 and the tumor suppressor Pdcd4 that is essential for Notch-mediated induction of T-cell acute lymphoblastic leukemia (T-ALL).

In this issue of Blood, Mamonkin and colleagues report genetically engineered T cells with specificity for the lineage marker CD5 selectively kill T-lymphoma but not normal T cells, although both express the CD5 target antigen.

In this issue of Blood, Kirstine Søgaard and colleagues report on the relevance of splanchnic vein thrombosis (SVT) as a marker of occult malignant disease.

In this issue of Blood, Ceriani et al introduce, in primary mediastinal B-cell lymphoma (PMBCL), a new prognostic factor measured on pretreatment 18F-fluorodeoxyglucose (18FDG)-positron emission tomography (PET)/computed tomography (CT): the total lesion glycolysis (TLG), which is an index of the glucose uptake by the total tumor burden. This paper is part of the International Extranodal Lymphoma Study Group (IELSG) 26 prospective study designed to evaluate the role of PET in the treatment of PMBCL.

In this issue of Blood, back-to-back (dos-à-dos) papers by Chiu et al and Yee et al present complementary findings of structural investigations into the interaction between factor VIII (FVIII) and von Willebrand factor (VWF). The binding of FVIII to VWF contributes in a major way to the regulation of hemostasis.

Expression of the forkhead transcription factor FOXP1 is essential for early B-cell development, whereas downregulation of FOXP1 at the germinal center (GC) stage is required for GC B-cell function. Aberrantly high FOXP1 expression is frequently observed in diffuse large B-cell lymphoma and mucosa-associated lymphoid tissue lymphoma, being associated with poor prognosis. Here, by gene expression analysis upon ectopic overexpression of FOXP1 in primary human memory B cells (MBCs) and B-cell lines, combined with chromatin immunoprecipitation and sequencing, we established that FOXP1 directly represses expression of PRDM1, IRF4, and XBP1, transcriptional master regulators of plasma cell (PC) differentiation. In accordance, FOXP1 is prominently expressed in primary human naive and MBCs, but expression strongly decreases during PC differentiation. Moreover, as compared with immunoglobulin (Ig) M(+) MBCs, IgG(+) MBCs combine lower expression of FOXP1 with an enhanced intrinsic PC differentiation propensity, and constitutive (over)expression of FOXP1 in B-cell lines and primary human MBCs represses their ability to differentiate into PCs. Taken together, our data indicate that proper control of FOXP1 expression plays a critical role in PC differentiation, whereas aberrant expression of FOXP1 might contribute to lymphomagenesis by blocking this terminal B-cell differentiation.

Hemophagocytic lymphohistiocytosis (HLH) is a refractory immune disorder with a significant risk of death. Although standard therapy has dramatically improved survival in HLH patients, approximately 30%, especially adults, show no response to current treatment strategies. This prospective study aimed to investigate the efficacy of liposomal doxorubicin treatment combined with etoposide and methylprednisolone (doxorubicin-etoposide-methylprednisolone; DEP) as a salvage therapy for adult refractory HLH. Adult patients who did not achieve at least partial response 2 weeks after initial standard HLH therapy were enrolled in this study between June 2013 and June 2014. Response to salvage therapy was assessed at 2 and 4 weeks after initiation of DEP therapy and patients were followed until death or until November 2014. Sixty-three refractory HLH patients were enrolled, including 29 cases of lymphoma-associated HLH, 22 cases of Epstein-Barr virus-associated HLH, and 4 cases of familial HLH. There were 8 cases with unknown underlying diseases. Seventeen cases (27.0%) achieved complete response and 31 cases (49.2%) achieved partial response. The overall response was 76.2% (48/63). Patients who showed no response to DEP died within 4 weeks after salvage therapy. Twenty-nine of the 48 patients who achieved partial or complete response survived to subsequent chemotherapy, allogenic hematopoietic stem cell transplantation, or splenectomy. Our study suggests that DEP regimen is an effective salvage regimen for adult refractory HLH, which can prolong patient survival as we continue to understand the responsible mechanisms and bridge the gap between HLH and its underlying diseases. This study was registered in the Chinese Clinical Trials Registry Platform (http://www.chictr.org.cn/) as ChiCTR-IPC-14005514.

Omenn syndrome (OS) is a severe immunodeficiency associated with erythroderma, lymphoproliferation, elevated IgE, and hyperactive oligoclonal T cells. A restricted T-cell repertoire caused by defective thymic T-cell development and selection, lymphopenia with homeostatic proliferation, and lack of regulatory T cells are considered key factors in OS pathogenesis. We report 2 siblings presenting with cytomegalovirus (CMV) and Pneumocystis jirovecii infections and recurrent sepsis; one developed all clinical features of OS. Both carried homozygous germline mutations in CARD11 (p.Cys150*), impairing NF-κB signaling and IL-2 production. A somatic second-site mutation reverting the stop codon to a missense mutation (p.Cys150Leu) was detected in tissue-infiltrating T cells of the OS patient. Expression of p.Cys150Leu in CARD11-deficient T cells largely reconstituted NF-κB signaling. The reversion likely occurred in a prethymic T-cell precursor, leading to a chimeric T-cell repertoire. We speculate that in our patient the functional advantage of the revertant T cells in the context of persistent CMV infection, combined with lack of regulatory T cells, may have been sufficient to favor OS. This first observation of OS in a patient with a T-cell activation defect suggests that severely defective T-cell development or homeostatic proliferation in a lymphopenic environment are not required for this severe immunopathology.

Iron supplements acutely increase hepcidin, but the duration and magnitude of the increase, its dose dependence, and its effects on subsequent iron absorption have not been characterized in humans. Better understanding of these phenomena might improve oral iron dosing schedules. We investigated whether the acute iron-induced increase in hepcidin influences iron absorption of successive daily iron doses and twice-daily iron doses. We recruited 54 nonanemic young women with plasma ferritin ≤20 µg/L and conducted: (1) a dose-finding investigation with 40-, 60-, 80-, 160-, and 240-mg labeled Fe as [(57)Fe]-, [(58)Fe]-, or [(54)Fe]-FeSO4 given at 8:00 am fasting on 1 or on 2 consecutive days (study 1, n = 25; study 2, n = 16); and (2) a study giving three 60-mg Fe doses (twice-daily dosing) within 24 hours (study 3, n = 13). In studies 1 and 2, 24 hours after doses ≥60 mg, serum hepcidin was increased (P < .01) and fractional iron absorption was decreased by 35% to 45% (P < .01). With increasing dose, fractional absorption decreased (P < .001), whereas absolute absorption increased (P < .001). A sixfold increase in iron dose (40-240 mg) resulted in only a threefold increase in iron absorbed (6.7-18.1 mg). In study 3, total iron absorbed from 3 doses (2 mornings and an afternoon) was not significantly greater than that from 2 morning doses. Providing lower dosages (40-80 mg Fe) and avoiding twice-daily dosing maximize fractional absorption. The duration of the hepcidin response supports alternate day supplementation, but longer-term effects of these schedules require further investigation. These clinical trials were registered at www.ClinicalTrials.gov as #NCT01785407 and #NCT02050932.

Internal tandem duplication of the Fms-like tyrosine kinase-3 receptor (FLT3) internal tandem duplication (ITD) is found in 30% of acute myeloid leukemia (AML) and is associated with a poor outcome. In addition to tyrosine kinase inhibitors, therapeutic strategies that modulate the expression of FLT3-ITD are also promising. We show that AML samples bearing FLT3-ITD mutations are more sensitive to proteasome inhibitors than wild-type samples and this sensitivity is strongly correlated with a higher FLT3-ITD allelic burden. Using pharmacologic inhibitors of autophagy, specific downregulation of key autophagy proteins including Vps34, autophagy gene (Atg)5, Atg12, Atg13, biochemical, and microscopy studies, we demonstrated that proteasome inhibitors induced cytotoxic autophagy in AML cells. FLT3-ITD molecules were detectable within autophagosomes after bortezomib treatment indicating that autophagy induction was responsible for the early degradation of FLT3-ITD, which preceded the inhibition of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK), PI3K/AKT, and STAT5 pathways, and subsequent activation of cell death. Moreover, proteasome inhibitors overcome resistance to quizartinib induced by mutations in the kinase domain of FLT3, suggesting that these compounds may prevent the emergence of mutant clones arising from tyrosine kinase inhibitor treatments. In xenograft mice models, bortezomib stimulated the conversion of LC3-I to LC3-II, indicating induction of autophagy in vivo, downregulated FLT3-ITD protein expression and improved overall survival. Therefore, selecting patients according to FLT3-ITD mutations could be a new way to detect a significant clinical activity of proteasome inhibitors in AML patients.