The age of the bone marrow microenvironment influences B-cell acute lymphoblastic leukemia progression via CXCR5-CXCL13.

B-cell acute lymphoblastic leukemia (B-ALL) occurs most commonly in children, whereas chronic myeloid leukemia is more frequent in adults. The myeloid bias of hematopoiesis in elderly individuals has been considered causative, but the age of the bone marrow microenvironment (BMM) may be contributory. Using various murine models of B-ALL in young vs old mice, we recapitulated B-ALL preponderance in children vs adults. We showed differential effects of young vs old BM macrophages on B-ALL cell function. Molecular profiling using RNA- and ATAC-sequencing revealed pronounced differences in young vs old BMM-derived macrophages and enrichment for gene sets associated with inflammation. In concordance with the role of C-X-C motif chemokine (CXCL) 13 for disease-associated B-cell chemoattraction, we found CXCL13 to be highly expressed in young macrophages on a translational compared with a transcriptional level. Inhibition of CXCL13 in BM macrophages impaired leukemia cell migration and decreased the proliferation of cocultured B-ALL cells, whereas recombinant CXCL13 increased pAKT and B-ALL cell expansion. Pretreatment of B-ALL-initiating cells with CXCL13 accelerated B-ALL progression. Deficiency of Cxcr5, the receptor for CXCL13, on B-ALL-initiating cells prolonged murine survival, whereas high expression of CXCR5 in pediatric B-ALL may predict central nervous system relapse. CXCL13 staining was increased in bone sections from pediatric compared with adult patients with B-ALL. Taken together, our study shows that the age of the BMM and, in particular, BM macrophages influence the leukemia phenotype. The CXCR5-CXCL13 axis may act as prognostic marker and an attractive novel target for the treatment of B-ALL.

CD79a promotes CNS-infiltration and leukemia engraftment in pediatric B-cell precursor acute lymphoblastic leukemia.

Central nervous system (CNS) involvement remains a challenge in the diagnosis and treatment of acute lymphoblastic leukemia (ALL). In this study, we identify CD79a (also known as Igα), a signaling component of the preB cell receptor (preBCR), to be associated with CNS-infiltration and -relapse in B-cell precursor (BCP)-ALL patients. Furthermore, we show that downregulation of CD79a hampers the engraftment of leukemia cells in different murine xenograft models, particularly in the CNS.

Metabolic adaptation of acute lymphoblastic leukemia to the central nervous system microenvironment is dependent on Stearoyl CoA desaturase.

Metabolic reprogramming is a key hallmark of cancer, but less is known about metabolic plasticity of the same tumor at different sites. Here, we investigated the metabolic adaptation of leukemia in two different microenvironments, the bone marrow and the central nervous system (CNS). We identified a metabolic signature of fatty-acid synthesis in CNS leukemia, highlighting Stearoyl-CoA desaturase (SCD1) as a key player. In vivo SCD1 overexpression increases CNS disease, whilst genetic or pharmacological inhibition of SCD1 decreases CNS load. Overall, we demonstrated that leukemic cells dynamically rewire metabolic pathways to suit local conditions and that targeting these adaptations can be exploited therapeutically.

The arginine metabolome in acute lymphoblastic leukemia can be targeted by the pegylated-recombinant arginase I BCT-100.

Arginine is a semi-essential amino acid that plays a key role in cell survival and proliferation in normal and malignant cells. BCT-100, a pegylated (PEG) recombinant human arginase, can deplete arginine and starve malignant cells of the amino acid. Acute lymphoblastic leukemia (ALL) is the most common cancer of childhood, yet for patients with high risk or relapsed disease prognosis remains poor. We show that BCT-100 is cytotoxic to ALL blasts from patients in vitro by necrosis, and is synergistic in combination with dexamethasone. Against ALL xenografts, BCT-100 leads to a reduction in ALL engraftment and a prolongation of survival. ALL blasts express the arginine transporter CAT-1, yet the majority of blasts are arginine auxotrophic due to deficiency in either argininosuccinate synthase (ASS) or ornithine transcarbamylase (OTC). Although endogenous upregulation or retroviral transduced increases in ASS or OTC may promote ALL survival under moderately low arginine conditions, expression of these enzymes cannot prevent BCT-100 cytotoxicity at arginine depleting doses. RNA-sequencing of ALL blasts and supporting stromal cells treated with BCT-100 identifies a number of candidate pathways which are altered in the presence of arginine depletion. Therefore, BCT-100 provides a new clinically relevant therapeutic approach to target arginine metabolism in ALL.

HPC-A dose prediction on the optia® cell separator based on a benchmark CE2 collection efficiency: Promoting clinical efficiency, minimizing toxicity, and allowing quality control.

It has been shown that it is possible to predict the CD 34+ hematopoietic progenitor cell dose from collection procedures on TerumoBCT COBE Spectra® cell separator platform using simple variables available at the start of the procedure. In this article, we demonstrate that this can be done simply and reliably using TerumoBCT Spectra Optia® ("Optia") cell separator platform with a very close correlation between predicted and actual results (correlation coefficient 0.956). This knowledge can be used to optimize apheresis sessions and to minimize harmful effects and costs. In addition, we have shown differences in collection efficiency between healthy donors and cancer patients undergoing autologous donation. Finally, we have shown a small but significant improvement in collection efficiency for the Optia platform compared with the COBE Spectra platform.