Bone Marrow Microenvironment Of Patients Research Articles

Clinical significance of IL-18 and IL-18-binding protein in bone marrow of patients with myelodysplastic syndrome

Objective: To analyze the level and clinical significance of IL-18 and IL-18-binding protein (BP) in the bone marrow of patients with myelodysplastic syndrome (MDS) . Methods: A total of 43 newly diagnosed patients with MDS who were admitted to the Department of Hematology, Tianjin Medical University General Hospital, from July 2020 to February 2021 were randomly selected. The control group consisted of 14 patients with acute myeloid leukemia (AML) and 25 patients with iron-deficiency anemia (IDA). The levels of IL-18 and IL-18 BP in the bone marrow supernatant were measured, and their correlations with MDS severity, as well as the functionality of CD8(+) T cells and natural killer cells, was analyzed. Results: The levels of IL-18, IL-18 BP, and free IL-18 (fIL-18) in the bone marrow supernatant of patients with MDS were higher than in the IDA group. The level of fIL-18 was linearly and negatively correlated with the MDS-International Prognostic Scoring System (IPSS) score. IL-18 receptor (IL-18Rα) expression on CD8(+) T cells in the MDS group was lower than in the IDA group, and the levels of fIL-18 and IL-18Rα were positively correlated with CD8(+) T-cell function in the MDS group. Conclusion: IL-18 BP antagonizes IL-18, leading to a decrease in fIL-18 in the bone marrow microenvironment of patients with MDS, affecting CD8(+) T-cell function, which is closely related to MDS severity; therefore, it may become a new target for MDS treatment.

Uncovering the cellular and omics characteristics of natural killer cells in the bone marrow microenvironment of patients with acute myeloid leukemia

BackgroundAcute myeloid leukemia (AML) is a highly heterogeneous hematologic malignancy and the most frequently acute leukemia of stem cell precursors and the myeloid derivatives in adult. Longitudinal studies have indicated the therapeutic landscape and drug resistance for patients with AML are still intractable, which largely attribute to the deficiency of detailed information upon the pathogenesis.MethodsIn this study, we compared the cellular phenotype of resident NK cells (rAML-NKs, rHD-NKs) and expanded NK cells (eAML-NKs, eHD-NKs) from bone marrow of AML patients (AML) and healthy donors (HD). Then, we took advantage of the co-culture strategy for the evaluation of the in vitro cytotoxicity of NK cells upon diverse tumor cell lines (e.g., K562, Nalm6, U937). With the aid of RNA-sequencing (RNA-SEQ) and bioinformatics analyses (e.g., GOBP analysis, KEGG analysis, GSEA, volcano plot), we verified the similarities and differences of the omics features between eAML-NKs and eHD-NKs.ResultsHerein, we verified the sharp decline in the content of total resident NK cells (CD3−CD56+) in rAML-NKs compared to rHD-NKs. Differ from the expanded eHD-NKs, eAML-NKs revealed decline in diverse NK cell subsets (NKG2D+, CD25+, NKp44+, NKp46+) and alterations in cellular vitality but conservations in cytotoxicity. According to transcriptomic analysis, AML-NKs and HD-NKs showed multifaceted distinctions in gene expression profiling and genetic variations.ConclusionsCollectively, our data revealed the variations in the cytobiological and transcriptomic features between AML-NKs and HD-NKs in bone marrow environment. Our findings would benefit the further development of novel biomarkers for AML diagnosis and NK cell-based cytotherapy in future.

Bone Marrow Microenvironment-Responsive Nanomedicine Promotes Anti-Leukemia Activity In Vivo

Background: Leukemia escape and relapse is the leading cause of death after allogeneic hematopoietic stem cell transplantation (allo-HSCT) for acute myeloid leukemia (AML). Work over the past decades has demonstrated that the CD47- signal-regulatory protein α (SIRPa) interaction mediated cancer cell immune escape. Although CD47-SIRPα interaction blockade contributes to cancer cell clearance by macrophages, how to deliver the anti-CD47 to bone marrow niche through an efficient drug delivery strategy and improve the cytotoxic activity of macrophages is an important issue that needs to be addressed. Methods: Here, we performed immunohistochemical (IHC) analysis and flow cytometry analysis of TIM-3 expression using samples of bone marrow from patients with or without relapse. In addition, according to the natural “myeloid niche homing” characteristic of AML cells and the low-oxygen microenvironment in bone marrow, we constructed β-cyclodextrin azobenzene linker (AZO-β-CD)-modified fusion protein and amantadine-modified HSA protein (HSA-ADA), followed by the addition of anti-CD47. Furthermore, the nanogel TIM3-targeting antibodies were modified on the surface of the nanogel to finally construct the supramolecular nanogel delivery system. Moreover, we detected the effect of target nanomedicine in a leukemia xenograft mouse model. Results: We demonstrated that in the bone marrow microenvironment of patients with relapse, the expression of TIM-3 significantly increased, especially in the CD34 +CD38 + leukemic progenitors, but not in the HSCs. Furthermore, we verified using nanomedicine could significantly increase the number of macrophages in the bone marrow. Importantly, the blockade of CD47-SIRPα signaling using nanomedicine markedly improved the anti-tumor activity in a leukemia xenograft mouse model. Conclusion: Thus, our findings reveal that nanomedicine could inhibit CD47-SIRPα signaling and contribute to anti-leukemia function effectively, which may be a new strategy for preventing and treating the recurrence of AML after transplantation.

Levels of Individual Mid and Long Chain Polyunsaturated Triacylglycerols (TAGs) Are Different between the Bone Marrow Microenvironment of Patients with Multiple Myeloma (MM) and Monoclonal Gammopathy of Unknown Significance (MGUS)

Background: It has been recently demonstrated that altered lipid metabolism involving increased free fatty acids (FFAs) uptake supports the growth and proliferation of MM cells (Panaroni et al. Blood 2022; Farell et al. Elife 2023). Whether the availability of FFAs in the bone marrow (BM) microenvironment is associated with the pathogenesis of MM from MGUS has not been previously evaluated. Thus, we evaluated if individual species of FAs or FA-containing lipids such as triacylglycerols (TAGs), diacylglycerols (DAGs), and monoacylglycerols (MAGs) are differentially present between the BM microenvironment of MGUS and MM patients. Methods: Lipid profiles of BM plasma samples (reflective of the BM microenvironment) from patients with a spectrum of plasma cell disorders (22 MGUS and 24 MM (15 newly diagnosed and 9 relapsed/refractory)) were acquired by liquid chromatography (LC)/tandem mass spectrometry (MS), and individual lipid species were quantified based on single-point quantification using 55 isotopically labeled internal standards. Concentration-based lipid species data was analyzed by the web-based tool MetaboAnalyst 5.0. Data was normalized by quantile normalization, log transformed and scaled by Pareto scaling. p values <0.05 were considered significant. Results: A total of 993 distinct lipid species were quantified by the MS-based targeted lipidomics assessment. Of these lipid species, the levels of individual mid-chain (≤50 carbon chain length) and long-chain (≥52 carbon chain length) polyunsaturated TAGs were the most differentially present in the BM plasma of MM compared to MGUS patients (Figure 1A). Even though a principal component analysis (PCA) involving all lipid species showed moderate separation of MM from MGUS patients, five MGUS patients (categorized as MGUS-other (MGO)) who clustered more towards MM patients compared to the remaining MGUS patients had a distinct pattern of individual mid and long-chain polyunsaturated TAG levels that were comparable to MM patients (Figure 1B). Furthermore, the proliferation rate of clonal plasma cells in the BM of these MM and MGUS as measured by the S-phase% was found to be directly correlated with the level of long-chain polyunsaturated TAGs. Conclusions: Mid and long-chain polyunsaturated TAGs are present in lower and higher levels, respectively, in the BM microenvironment of MM compared to MGUS patients. These findings continue to support the importance of FA-containing TAGs and other lipids in the pathogenesis of MM. Future confirmatory studies evaluating the biological significance of these differences are required to determine if they can be exploited for diagnostic and therapeutic purposes.

P-399 Isatuximab promotes immune activation in the bone marrow microenvironment of patients with high risk smoldering multiple myeloma

P-399 Isatuximab promotes immune activation in the bone marrow microenvironment of patients with high risk smoldering multiple myeloma

The non-cell-autonomous function of ID1 promotes AML progression via ANGPTL7 from the microenvironment

AbstractThe bone marrow microenvironment (BMM) can regulate leukemia stem cells (LSCs) via secreted factors. Increasing evidence suggests that dissecting the mechanisms by which the BMM maintains LSCs may lead to the development of effective therapies for the eradication of leukemia. Inhibitor of DNA binding 1 (ID1), a key transcriptional regulator in LSCs, previously identified by us, controls cytokine production in the BMM, but the role of ID1 in acute myeloid leukemia (AML) BMM remains obscure. Here, we report that ID1 is highly expressed in the BMM of patients with AML, especially in BM mesenchymal stem cells, and that the high expression of ID1 in the AML BMM is induced by BMP6, secreted from AML cells. Knocking out ID1 in mesenchymal cells significantly suppresses the proliferation of cocultured AML cells. Loss of Id1 in the BMM results in impaired AML progression in AML mouse models. Mechanistically, we found that Id1 deficiency significantly reduces SP1 protein levels in mesenchymal cells cocultured with AML cells. Using ID1-interactome analysis, we found that ID1 interacts with RNF4, an E3 ubiquitin ligase, and causes a decrease in SP1 ubiquitination. Disrupting the ID1-RNF4 interaction via truncation in mesenchymal cells significantly reduces SP1 protein levels and delays AML cell proliferation. We identify that the target of Sp1, Angptl7, is the primary differentially expression protein factor in Id1-deficient BM supernatant fluid to regulate AML progression in mice. Our study highlights the critical role of ID1 in the AML BMM and aids the development of therapeutic strategies for AML.

Oral azacitidine modulates the bone marrow microenvironment in patients with acute myeloid leukaemia in remission: A subanalysis from the QUAZAR AML-001 trial.

Oral azacitidine (Oral-AZA) maintenance therapy improved relapse-free (RFS) and overall survival (OS) significantly versus placebo for AML patients in remission after intensive chemotherapy (IC) in the phase 3 QUAZAR AML-001 study. Immune profiling was performed on the bone marrow (BM) at remission and on-treatment in a subset of patients with the aim of identifying prognostic immune features and evaluating associations of on-treatment immune effects by Oral-AZA with clinical outcomes. Post-IC, increased levels of lymphocytes, monocytes, T cells and CD34 + CD117+ BM cells were prognostically favourable for RFS. CD3+ T-cell counts were significantly prognostic for RFS in both treatment arms. At baseline, high expression of the PD-L1 checkpoint marker was identified on a subset of CD34 + CD117+ BM cells; many of which were PD-L2+. High co-expression of T-cell exhaustion markers PD-1 and TIM-3 was associated with inferior outcomes. Oral-AZA augmented T-cell numbers during early treatment, increased CD4+:CD8+ ratios and reversed T-cell exhaustion. Unsupervised clustering analysis identified two patient subsets defined by T-cell content and expression of T-cell exhaustion markers that were enriched for MRD negativity. These results indicate that Oral-AZA modulates T-cell activity in the maintenance setting of AML, and these immune-mediated responses are associated with clinical outcomes.

Bone Marrow Adipocytes Promote the Survival of Multiple Myeloma Cells and Up-Regulate Their Chemoresistance

To investigate the effect of adipocytes in the bone marrow microenvironment of patients with multiple myeloma (MM) on the pathogenesis of MM. Bone marrow adipocytes (BMA) in bone marrow smears of health donors (HD) and newly diagnosed MM (ND-MM) patients were evaluated with oil red O staining. The mesenchymal stem cells (MSC) from HD and ND-MM patients were isolated, and in vitro co-culture assay was used to explore the effects of MM cells on the adipogenic differentiation of MSC and the role of BMA in the survival and drug resistance of MM cells. The expression of adipogenic/osteogenic differentiation-related genes PPAR-γ, DLK1, DGAT1, FABP4, FASN and ALP both in MSC and MSC-derived adipocytes was determined with real-time quantitative PCR. The Western blot was employed to detect the expression levels of IL-6, IL-10, SDF-1α, TNF-α and IGF-1 in the supernatant with or without PPAR-γ inhibitor. The results of oil red O staining of bone marrow smears showed that BMA increased significantly in patients of ND-MM compared with the normal control group, and the BMA content was related to the disease status. The content of BMA decreased in the patients with effective chemotherapy. MM cells up-regulated the expression of MSC adipogenic differentiation-related genes PPAR-γ, DLK1, DGAT1, FABP4 and FASN, but the expression of osteogenic differentiation-related gene ALP was significantly down-regulated. This means that the direct consequence of the interaction between MM cells and MSC in the bone marrow microenvironment is to promote the differentiation of MSC into adipocytes at the expense of osteoblasts, and the cytokines detected in supernatant changed. PPAR-γ inhibitor G3335 could partially reverse the release of cytokines by BMA. Those results confirmed that BMA regulated the release of cytokines via PPAR-γ signal, and PPAR-γ inhibitor G3335 could distort PPAR-γ mediated BMA maturation and cytokines release. The increased BMA and related cytokines effectively promoted the proliferation, migration and drug resistance of MM cells. The BMA and its associated cytokines are the promoting factors in the survival, proliferation and migration of MM cells. BMA can protect MM cells from drug-induced apoptosis and plays an important role in MM treatment failure and disease progression.

An Unbalanced Monocyte Macrophage Polarization in the Bone Marrow Microenvironment of Patients with Poor Graft Function after Allogeneic Hematopoietic Stem Cell Transplantation

BackgroundPoor graft function (PGF) remains a life-threatening complication following allogeneic hematopoietic stem cell transplantation (allo-HSCT), and the underlying mechanisms have not yet been elucidated. Considerable evidence from murine studies has demonstrated that effective hematopoiesis depends on the specific bone marrow (BM) microenvironment, where hematopoietic stem cells (HSCs) reside. In this regard, we previously reported that PGF patients had impaired BM endosteal cells and endothelial progenitor cells, as well as dysregulated T cell responses in the BM microenvironment, which may be involved in the occurrence of PGF (BBMT 2013; BMT2016; Oncotarget 2016; BBMT 2016; Blood 2016; J Transl Med2017). Macrophage is one of the important components of BM immune microenvironment. Meanwhile, Murine studies suggest that macrophages regulate the retention of HSCs by regulating osteoblastic cell activity and nestin-expressing cells. Increasing evidence shows that BM resident macrophages are indispensable for HSCs function and BM erythroid output. However, little is known about the quantity and function of BM macrophages and whether the unbalanced BM macrophages directly interact with HSCs in PGF patients post allo-HSCT.AimsTo compare the number and function of BM macrophages between patients with PGF and GGF after allo-HSCT. Moreover, to investigate whether the unbalanced BM macrophages directly interact with HSCs in PGF patients.MethodsThis prospective nested case-control study enrolled 30 patients with PGF, 60 matched patients with good graft function (GGF), defined as persistent successful engraftment after allotransplant, and 30 healthy donors (HD). Standard monocyte subsets, defined by cluster of differentiation CD14 and CD16, were quantified by flow cytometry. In addition, based on the phenotype of polarized macrophages in vitro, classically activated inflammatory macrophage (M1:CD68+CCR2+) and alternatively activated anti-inflammatory macrophage (M2:CX3CR1+CD163+/CD206+) from BM samples were analyzed by flow cytometry. BM CD14+ monocytes were isolated from BM mononuclear cell (BMMNCs) and were cultured with 100 ng/ml recombinant human M-CSF for 10 days to obtain macrophages. The functions of BM derived macrophages were evaluated by migration assay and phagocytosis assay. CD34+ cells from healthy donors were co-cultured with BM derived macrophages from PGF patients, and the levels of reactive oxygen species (ROS) and apoptosis in CD34+ cells were analyzed by flow cytometry after 5 days co-culture.ResultsAlterations in standard monocyte subsets (classical, intermediate and non-classical) were found when comparing subjects among PGF, GGF and normal controls. In particular, elevated intermediate and non-classical monocyte subsets were observed in PGF patients when compared with those in GGF patients. Moreover, PGF patients displayed an imbalanced M1/M2 ratio compared with the GGF and normal controls, attributable to a reduction in M2 and an increase in M1. Dysfunctional BM derived macrophages, which were characterized by impaired proliferation, migration, phagocytosis and higher level of apoptosis, were revealed in patients with PGF. BM CD34+ cells from healthy donors were co-cultured respectively with BM derived macrophages from patients with PGF and normal controls. Apoptosis and intracellular levels of ROS were markedly increased in CD34+ bone marrow cells which were co-cultured with PGF patients' BM derived macrophages compared with normal controls.Summary/ConclusionIn summary, the current study demonstrated the abnormal number and impaired function of BM macrophages and unbalanced BM macrophages directly interact with HSCs in PGF patients. We speculate that reduction of anti-inflammatory M2 monocytes while increase of pro-inflammatory M1 monocytes in PGF patient BM have a negative impact on HSCs in BM microenvironment. Thus, our results indicate that unbalanced BM M1/M2 and dysfunctional BM macrophages may play an important role in the pathogenesis of PGF following allo-HSCT. Therefore, it would be of value to investigate the appropriate approach to balance the M1/M2 and enhance function of BM macrophages, which may be a promising therapeutic approach for PGF patients. DisclosuresNo relevant conflicts of interest to declare.

Neuropathy in the Altered Bone Marrow Microenvironment of Patients with Essential Thrombocythemia and the Effects of Interferonα-2b on Them

Background: ET is one of the classical Philadelphia chromosome-negative MPNs . BM-MSCs may involve in the pathogenesis of MPN. Bone marrow neural tissue, closely related to hematological diseases , is composed of sympathetic nervous system (SNS) fibres , ensheathing Schwann cells, supporting nestin+ MSCs . There has been a longstanding interest in using interferon (IFN) to control myeloproliferation in patients with ET. Until now, little is known about whether IFN had effects on the BM-MSCs from patients with ET.Objective: This study aims to systematically and thoroughly assess the biological and functional characteristics of BM-MSCs and SNS in patients with ET and explored the effects of IFNα-2b exerted on them.Methods: (1) The morphology of BM-MSCs was observed under an inverted microscope. (2) The immunophenotype markers of BM-MSCs were examined by flow cytometry. (3) BM-MSCs were induced to differentiate into adipocytes and osteoblasts, which were identified with corresponding staining. (4) The proliferation rate, senescence and apoptosis of BM-MSCs was detected.(5)Nestin+cell number ,sympathetic nerve fibres , schwann cells and nestin mRNA expression were detected by IHC and RT-PCR respectively.(6)CXCL12 and norepinephrine was detected by ELISA . (7) Umbilical cord derived CD34+ cells were purified and co-cultured with BM-MSCs to assess the function of BM-MSCs to support hematopoiesis . Hematopoietic growth factors such as SCF, IL-6 and VEGF were detected by ELISA . (8) Peripheral blood mononuclear cells (PBMCs) were isolated from normal controls and co-cultured with BM-MSCs to assess the suppression capacity of BM-MSCs in the proliferation of PBMCs. PBMCs were also co-cultured with BM-MSCs to assess the contribution of BM-MSCs in promoting the proliferation of Tregs. (9) Compared with ET derived BM-MSCs in the absence of IFNα-2b, the ET derived BM-MSCs were examined the changes in above biological and functional characteristics with the presence of IFNα-2b.Results: (1) No significant differences were found in morphology between BM-MSCs from patients with ET and normal controls. Both BM-MSCs exhibited bipolar spindle-like cells with a whirlpool-like array. (2) BM-MSCs from patients with ET and normal controls also had no discrepancies in immunophenotype characteristics. (3) BM-MSCs from ET showed increased proliferation, lower apoptosis capacity and decreased senescence. (4)In MPN patients, nestin+cell number and nestin messenger RNA expression were markedly increased. (5)Nevertheless , BM-MSCs from ET patients expressed lower levels CXCL12 than healthy controls. (6)Sympathetic nerve fibres and ensheathing Schwann cells were markedly reduced in BM of ET patients , with lower levels of norepinephrine secreted. (7) BM-MSCs from ET patients were more difficult to induce to osteoblasts than healthy controls. (8) Both BM-MSCs from ET patients and healthy controls had the potential to support hematopoiesis. However, BM-MSCs from ET patients had reduced capacity to amplify CD34+ cells and maintain long-term hematopoiesis. BM-MSCs from ET patients expressed lower levels SCF, IL-6 and VEGF than healthy controls. (9) BM-MSCs from ET were defective to suppress the proliferation of PBMCs and could promote PBMCs to differentiate into regulatory T cells. (10) IFNα-2b had no effect on the morphology, immunophenotype and JAK2 mutant allele of BM-MSCs derived from ET patients. IFNα-2b was capable of suppressing the proliferation of BM-MSCs, but increasing its apoptosis and its function of supporting hematopoiesis. IFNα-2b also ameliorated its defective in inhibiting the proliferation of PBMCs and promotes PBMCs to differentiate into regulatory T cells.Conclusion: (1) BM-MSCs from ET patients were multiply defective both in biological properties and functions. (2) BM-MSCs from ET were abnormal in proliferation,senescence, apoptosis and differentiation. (3) BM-MSCs from ET had reduced capacity to maintain hematopoiesis. (4) BM-MSCs from ET were defective in maintaining immune homeostasis. (5) Neuropathy is obvious in ET patients. (6) IFNα-2b affects BM-MSCs from ET patients in multiple differentiation capacities, proliferation, apoptosis and the capacity to support long-term hematopoiesis and immune regulation. DisclosuresNo relevant conflicts of interest to declare.

Tumor Microenvironment Proteomics: Lessons From Multiple Myeloma.

Although the “seed and soil” hypothesis was proposed by Stephen Paget at the end of the 19th century, where he postulated that tumor cells (seeds) need a propitious medium (soil) to be able to establish metastases, only recently the tumor microenvironment started to be more studied in the field of Oncology. Multiple myeloma (MM), a malignancy of plasma cells, can be considered one of the types of cancers where there is more evidence in the literature of the central role that the bone marrow (BM) microenvironment plays, contributing to proliferation, survival, migration, and drug resistance of tumor cells. Despite all advances in the therapeutic arsenal for MM treatment in the last years, the disease remains incurable. Thus, studies aiming a better understanding of the pathophysiology of the disease, as well as searching for new therapeutic targets are necessary and welcome. Therefore, the present study aimed to evaluate the protein expression profiling of mononuclear cells derived from BM of MM patients in comparison with these same cell types derived from healthy individuals, in order to fill this gap in MM treatment. Proteomic analysis was performed using the mass spectrometry technique and further analyses were done using bioinformatics tools, to identify dysregulated biological pathways and/or processes in the BM microenvironment of patients with MM as a result of the disease. Among the pathways identified in this study, we can highlight an upregulation of proteins related to protein biosynthesis, especially chaperone proteins, in patients with MM. Additionally, we also found an upregulation of several proteins involved in energy metabolism, which is one of the cancer hallmarks. Finally, with regard to the downregulated proteins, we can highlight mainly those involved in different pathways of the immune response, corroborating the data that has demonstrated that the immune system of MM is impaired and, therefore, the immunotherapies that have been studied recently for the treatment of the disease are extremely necessary in the search for a control and a cure for these patients who live with the disease.

Immune profiling of the bone marrow microenvironment in patients with high-risk localized prostate cancer.

Bone marrow (BM) is a primary metastatic site in prostate cancer (PC) and bone invasion is considered incurable. T cell-mediated immune surveillance is essential in controlling both tumorigenesis and initiation of metastases. Beside tropism, dissemination of PC cells to the BM may be facilitated by defects in BM immune homeostasis predisposing this niche to colonization.To evaluate the BM immune microenvironment in locally advanced, non-metastatic PC, we performed flow cytometry analysis of myeloid and lymphoid subsets in BM aspirates and peripheral blood collected during prostatectomy. Healthy BM aspirates served to establish a reference range for comparison.We found alterations in BM immune composition of PC patients, including an increased CD4/CD8 ratio, enrichment of CD4+ T cells, increased CD56+CD3+ NKT and CD56+CD3- NK yields compared to healthy controls. The lymphoid phenotype remained comparable regarding T cell activation and chemokine receptor-based polarization patterns. Additionally, we found increased B7H3 expression in the myeloid monocyte/macrophage subset and decreased DC infiltration in BM of PC patients.These findings suggest that alterations in the immune milieu may limit immune surveillance that compromise the ability of the BM microenvironment to prevent tumor dissemination, and predispose development of bone metastases in a subset of patients with localized PC.

Characterization of Plasma and Immune Cells Molecular Landscape That Play a Role in Rapid Progression of Multiple Myeloma Using Cross Center Scrna-Seq Study

Characterization of Plasma and Immune Cells Molecular Landscape That Play a Role in Rapid Progression of Multiple Myeloma Using Cross Center Scrna-Seq Study

Highly multiplexed proteomic assessment of human bone marrow in acute myeloid leukemia

AbstractAcute myeloid leukemia (AML) is a genetically heterogeneous disease that is characterized by abnormal clonal proliferation of myeloid progenitor cells found predominantly within the bone marrow (BM) and blood. Recent studies suggest that genetic and phenotypic alterations in the BM microenvironment support leukemogenesis and allow leukemic cells to survive and evade chemotherapy-induced death. However, despite substantial evidence indicating the role of tumor–host interactions in AML pathogenesis, little is known about the complex microenvironment of the BM. To address this, we performed novel proteomic profiling of the noncellular compartment of the BM microenvironment in patients with AML (n = 10) and age- and sex-matched healthy control subjects (n = 10) using an aptamer-based, highly multiplexed, affinity proteomics platform (SOMAscan). We show that proteomic assessment of blood or RNA-sequencing of BM are suboptimal alternate screening strategies to determine the true proteomic composition of the extracellular soluble compartment of AML patient BM. Proteomic analysis revealed that 168 proteins significantly differed in abundance, with 91 upregulated and 77 downregulated in leukemic BM. A highly connected signaling network of cytokines and chemokines, including IL-8, was found to be the most prominent proteomic signature associated with AML in the BM microenvironment. We report the first description of significantly elevated levels of the myelosuppressive chemokine CCL23 (myeloid progenitor inhibitory factor-1) in both AML and myelodysplastic syndrome patients and perform functional experiments supportive of a role in the suppression of normal hematopoiesis. This unique paired RNA-sequencing and proteomics data set provides innovative mechanistic insights into AML and healthy aging and should serve as a useful public resource.

Ruxolitinib (RUX) Induced Meaningful and Directional Changes in the Bone Marrow Microenvironment of Patients with Myelofibrosis Enrolled in the COMFORT-I Study

Background The oral Janus kinase (JAK) 1/JAK2 inhibitor RUX has been shown to induce a reduction in bone marrow (BM) fibrosis in patients (pts) with myelofibrosis (MF) compared with placebo. MF is characterized by clonal proliferation of hematopoietic progenitor cells (HPCs) and amplification of cytokine-producing megakaryocytes (MEGs) and macrophages (MACs). Evidence suggests that the pro-inflammatory microenvironment, fostered by the hematopoietic clone, results in BM stromal alterations (including BM fibrosis and osteosclerosis), which can, in turn, influence the hematopoietic niche. The objective of this analysis was to evaluate BM changes in order to characterize the long-term effects of RUX on BM stromal alterations, cytokine-producing cells (ie, MEGs and MACs), and plasma cells (surrogates of inflammation) in a cohort of pts with intermediate-2 or high-risk primary MF, post-polycythemia vera MF, or post-essential thrombocythemia MF who were enrolled in the phase 3 COMFORT-I study. Methods This analysis included 57 pts (36 originally randomized to RUX, 21 crossover [CO] from placebo). All pts were required to have a baseline (BL) BM biopsy and ≥1 subsequent BM observation. CO pts were re-baselined; if CO occurred at <36 wks or ≥36 wks, the Week 0 BM or Week 48 BM, respectively, was used as the BL observation. For fibrosis and osteosclerosis, sections were stained with standard procedures. Specific immunohistochemical (IHC) stains were used to assess MEGs (CD61); plasma cells (MUM1); and activated MACs, including CD68 to identify M1 and anti-inflammatory M2 subtypes, and CD163, a very specific marker for the M2 subtype. Evaluations included IHC and morphometric assessment of CD34+ HPCs. European consensus guidelines were used to grade BM fibrosis and cellularity (Haematologica. 2005;90:1128-1132). Each parameter was graded, by consensus, based on independent review by 3 expert pathologists. A 0-3 grading system was used for fibrosis, osteosclerosis, plasma cells, MEG clustering/atypia, and CD68/163 MACs. Changes from BL to last BM observation are reported. These changes were categorized as improved, stable, or worsened. Improvement/worsening was defined as ≥1 grade reduction/increase from BL or a change in abnormal/normal status. Improvement was assessed in pts with BL values 1-3 or abnormal, stability in pts with BL values 0-2 or normal, and worsening in pts with BL values 0-2 or normal. Results Pt characteristics are summarized in the Table. With respect to age-adjusted cellularity at BL, most marrows were hypercellular, with a notable increase in the proportion of normocellular and hypocellular marrows by the last observation (Figure). In most pts, BM fibrosis was either stable or improved; 21.6% of pts had worsening fibrosis. Similarly, the majority of pts had stable (62.7%) or improved (20.6%) osteosclerosis at the last observation compared with BL. Assessments of megakaryopoiesis revealed stabilization or improvement in MEG clustering in all pts; MEG atypia was improved or stable in the majority of pts. Similarly, RUX resulted in normalization of CD68+ and CD163+ MACs in 21.4% and 25.0% of pts, respectively. The proportion of pts with normal CD34+ clustering/frequency increased from 72.5% at BL to 86.3% at the last visit. With respect to evidence of decreased inflammation in the BM microenvironment, the majority of pts (71.4%) with abnormal plasma cells at BL had a normal level of plasma cells by the last observation, and only 9.7% had evidence of worsening. Conclusions These results extend previous observations on the effect of RUX on the BM in pts with MF. RUX treatment resulted in improvements in the HPCs, atypical MEGs, and activated MACs that are classically thought to produce the inflammatory cytokines that drive BM stromal alterations. These improvements in myeloproliferation were associated with improvement/stabilization of BM fibrosis and sclerosis in the majority of pts. There were also directional improvements in BM plasma cells, a surrogate of inflammation in the BM microenvironment. The MF phenotype is derived from clonal myeloproliferation and a secondary inflammatory state, which results in BM stromal alterations and a constellation of symptoms. The disease-modifying properties of RUX are likely attributable to its ability to address not only myeloproliferation through inhibition of JAK2, but also the secondary inflammatory state through inhibition of JAK1. Disclosures Kvasnicka: Novartis: Honoraria, Research Funding; Takeda: Honoraria; Incyte: Honoraria, Research Funding. Thiele:Sanofi: Consultancy, Honoraria, Other: Remuneration; Incyte: Consultancy, Honoraria, Other: Remuneration, Research Funding; AOP Orphan Pharmaceuticals: Consultancy, Research Funding; Novartis: Consultancy, Honoraria, Other: Remuneration, Research Funding; Shire: Research Funding. Bueso-Ramos:Incyte: Consultancy. Colucci:Incyte: Employment, Equity Ownership. Paranagama:Incyte: Employment, Equity Ownership. Verstovsek:Genetech: Research Funding; Blueprint Medicines Corp: Research Funding; Gilead: Research Funding; Promedior: Research Funding; CTI BioPharma Corp: Research Funding; Novartis: Consultancy, Research Funding; Sierra Oncology: Research Funding; Pharma Essentia: Research Funding; Astrazeneca: Research Funding; Ital Pharma: Research Funding; Protaganist Therapeutics: Research Funding; Constellation: Consultancy; Pragmatist: Consultancy; Incyte: Research Funding; Roche: Research Funding; NS Pharma: Research Funding; Celgene: Consultancy, Research Funding.

Research Advances on Role of Extracellular Vesicles in the Bone Marrow Microenvironment of Patients with Hematological Malignancies--Review

Bone marrow (BM) microenvironment appears to play an important role in the pathogenesis of hematological malignancies. Apart from soluble factors and direct cell-cell contact, the extracellular vesicles (EVs) were identified as a third mediator for cell communication within BM microenvironment. Recently, more and more evidences have demonstrated that EVs are also involved in the dysregulation of the BM microenvironment in patients with hematological malignancies. Therefore this review focuses on the biological characteristics of EVs, the clinical value of EVs as biomarkers, the BM microenvironment reprogramming in hematological malignancies by EVs, and the potential role of EVs in drug resistance and therapy of hematological malignancies.

Increased Monocytic Myeloid-Derived Suppressor Cells in the Marrow of Relapsed/Refractory Acute Myeloid Leukemia Patients Following Induction Chemotherapy

Background: Acute myeloid leukemia (AML) is an aggressive malignancy associated with poor long-term outcomes. This malignancy arises in the context of an immunosuppressive milieu, which fosters immune escape and tumor growth. Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous group of immature myeloid cells with immunosuppressive activity, the most potent of which are the monocytic MDSCs (mMDSCs). The presence of mMDSCs within the bone marrow microenvironment of patients with AML, along with their impact on disease relapse and overall survival has yet to be fully characterized. Therefore, we sought to address this unanswered question through a retrospective analysis of a cohort of AML patients (pts) at Roswell Park Comprehensive Cancer Center.Methods: Medical records were retrospectively reviewed under an IRB approved protocol in order to identify pts aged 18-70 years old with normal karyotype (NK) AML treated with standard cytarabine and anthracycline based chemotherapy with refractory or subsequent relapsed disease. Demographics, disease-specific variables, baseline clinical characteristics, treatment response, and adverse events were analyzed using descriptive statistics. Overall survival and relapse-free survival were estimated utilizing Kaplan-Meier (KM) analysis. Detailed analysis of previously collected clinical multiparameter flow cytometric data was performed utilizing WinList software to identify mMDSCs at serial clinical time points (diagnosis, after induction chemotherapy, and relapse). A mononuclear gate was created utilizing CD45 vs. SSC (blasts excluded), followed by FSC vs. SSC to eliminate dead cells and aggregates. Based on the scientific literature, mMDSCs were defined as the subset of marrow cells co-expressing CD14+ and HLA-DR dim, and was reported as the percentage of total monocytes in the marrow aspirate sample.Results: Six pts with NK-AML who received induction chemotherapy with cytarabine, daunorubicin, and etoposide (ADE) were identified. Mean age was 56 years (range 35 - 67), with 3/6 male pts (50%) (Table 1). NPM1 was mutated in 2/6 pts at diagnosis, with no FLT3-ITD mutations identified. In addition, 2 pts had an elevated WBC at presentation. Following induction therapy, 2 pts had primary refractory disease with four achieving complete remission (CR). Furthermore, each of the 6 pts relapsed. All 6 pts had marrow aspirate samples containing detectable mMDSCs by flow cytometry at multiple time points. Of note, 5 of 6 pts had elevated mMDSCs (average 76.2%; range 72.8% - 82.6% of total marrow monocytes) detected at time of response assessment following induction. Median relapse-free survival was 48 months (Figure 1). Overall survival not yet been reached. Mean duration of follow up was 85 months (range 61 - 119 months).Conclusions: This retrospective analysis suggests that high numbers of marrow mMDSCs (>72%) are associated with relapsed/refractory AML in a small patient cohort. Of note, other risk factors for refractory/relapsed disease (i.e. elevated WBC at presentation and FLT3 mutation) were not consistently present in our cohort, thus supporting a potential role of mMDSCs in promoting disease recurrence. Additional studies to further quantify and delineate the biological role of mMDSCs in a larger pt cohort are needed to corroborate these findings and determine the potential role of these immune cells in therapy resistant AML. DisclosuresWang:Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Speakers Bureau; Jazz: Speakers Bureau; Amgen: Consultancy; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy; Novartis: Speakers Bureau; Jazz: Speakers Bureau; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Partial Reconstitution of Humoral and Cellular Immunity in Patients with Chronic Lymphocytic Leukemia Treated with Acalabrutinib

IntroductionImmune dysregulation in chronic lymphocytic leukemia (CLL) contributes to a high rate of infections and morbidity. We previously reported that treatment of CLL with ibrutinib, a Bruton tyrosine kinase (BTK) inhibitor, leads to partial reconstitution of humoral immunity and fewer infections, especially in patients who achieved a ≥50% increase in serum IgA levels. Acalabrutinib is also an irreversible BTK inhibitor that is more selective than ibrutinib and has demonstrated safety and efficacy in the treatment of relapsed or refractory CLL. It is currently unclear how the increased specificity of acalabrutinib affects immune reconstitution and infection rates. We assessed the immunological impact of acalabrutinib in patients with CLL treated with single-agent acalabrutinib.MethodsSamples originated from a phase 2, single-center trial studying acalabrutinib 100 mg twice daily (BID) or acalabrutinib 200 mg once daily (QD) in patients with relapsed/refractory (RR) CLL or high-risk, treatment naïve (TN) CLL (chromosome 17p deletion or mutation in TP53 or NOTCH1) (NCT02337829). Patients who received at least 6 months of acalabrutinib and had paired longitudinal data available were included in the analyses. Patients receiving IV immunoglobulin replacement were excluded from analysis of IgG levels. Additionally, patients with detectable monoclonal IgG, IgA and/or IgM proteins on serum immunofixation were excluded from analysis of the corresponding immunoglobulin isotype. The analysis of free light chains was stratified based on k or λ restriction of CLL cells determined by flow cytometry. Immunohistochemical staining of bone marrow biopsies was performed: T cell numbers were estimated by CD3 staining and the degree of CD68-positive macrophage extensions in contact with CLL cells were semi-quantitatively assessed on a scale from 0 (no extensions) to 4 (maximum number of extensions). The Wilcoxon signed-rank test and the Mann-Whitney U test were used to compare paired and unpaired data, respectively. Differences in the rate of infection between groups were examined using the Cox regression model for recurrent events.ResultsSerum IgA levels increased as early as 3 months after the initiation of acalabrutinib (median increase 35.7%, P = .0001), with levels sustained up to 24 months (Figure 1), whereas serum IgG and IgM levels were not affected by acalabrutinib. There was no difference (P > .05) in IgA, IgG, IgM trend between TN or RR CLL. Furthermore, there was no difference (P > .05) in IgA, IgG and IgM trends between patients treated with QD compared to BID dosing of acalabrutinib. Among 20 k-restricted and 18 λ-restricted CLL cases, the involved (tumor-derived) free light chain was elevated at baseline and trended toward the normal range after 3 months of acalabrutinib therapy consistent with an anti-tumor effect (k: median decrease 55.4%; P < .0001 and λ: median decrease 49.1%; P = .0003). The uninvolved free light chain did not change (P > .05). Peripheral blood CD3+, CD4+ and CD8+ T cell counts were elevated above the laboratory reference range at baseline and normalized after 6 months (CD4+ median decrease 49.2%; P = .0074 and CD8+ median decrease 54.8%; P = .003). T cell numbers in the bone marrow did not appreciably change. However, treatment-induced changes of the immune microenvironment were apparent in tumor-macrophage interactions. At baseline, macrophages tightly interacted with CLL cells, often with multiple podocytes making contact with CLL cells. On acalabrutinib, we observed a decrease in these macrophage podocyte interactions (P = .0007). At a median follow-up of 20 months, 31 (68.9%) patients developed a total of 68 infections, including 7 (10.3%) grade 3 and 1 (1.5%) grade 4 infections. Patients with superior immune reconstitution, as defined by an increase in serum IgA of ≥ a median of 36% from baseline to 3 months, had a significantly lower rate of infections (risk ratio = 0.52, P = 0.029).ConclusionsThese data indicate that acalabrutinib allows for partial reconstitution of humoral and cell-mediated immunity and disrupts macrophage-CLL cell interaction in the bone marrow microenvironment in patients with CLL. Furthermore, acalabrutinib did not interfere with uninvolved free light chains, suggesting that acalabrutinib selectively inhibits CLL B-cells and does not impair normal B-cell function. [Display omitted] DisclosuresIzumi:Acerta Pharma: Employment, Equity Ownership, Patents & Royalties: Acerta Pharma, various patents for ACP-196. Hamdy:Acerta Pharma: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties: Acerta Pharma, various patents for ACP-196. Wiestner:Pharmacyclics LLC, an AbbVie Company: Research Funding.

TGF-Beta Signaling in Mesenchymal Stromal Cells Contributes to Myelofibrosis but Not Hematopoietic Phenotypes in Myeloproliferative Neoplasms

The development of myelofibrosis in patients with myeloproliferative neoplasms (MPNs) is associated with a dismal prognosis. The mechanisms responsible for the progression to myelofibrosis are unclear, limiting the development of therapies to treat or prevent it. The cell of origin responsible for the increased collagen deposition is controversial, with recent studies implicating Gli1+ or leptin receptor+ mesenchymal stromal cells, monocytes, or even endothelial cells. Moreover, the signals generated by malignant hematopoietic cells in MPN that induce increased collagen expression are uncertain. There is some evidence that elevated expression of cytokines/chemokines in the bone marrow microenvironment of patients with MPN may contribute. In particular, recent studies have implicated transforming growth factor-β (TGF-β), platelet-derived growth factor and CXCL4 in the development of myelofibrosis. Here, we test the specific hypothesis that TGF-β signaling in mesenchymal stromal cells is required for the development of myelofibrosis. Moreover, we hypothesize that TGF-β signaling, by altering the expression of key niche factors by mesenchymal stromal cells, contributes to the myeloid expansion in MPN.To test this hypothesis, we abrogated TGF-β signaling in mesenchymal stem/progenitor cells (MSPCs) by deleting Tgfbr2 using a doxycycline-repressible Sp7 (osterix)-Cre transgene (Osx-Cre), which targets all mesenchymal stromal cells in the bone marrow, including CXCL12-abundant reticular (CAR) cells, osteoblasts, adipocytes, or arteriolar pericytes. We previously showed that TGF-β signaling plays a key role in the lineage specification of MSPCs during development (2017 ASH abstract #2438). In contrast, we show that post-natal deletion of Tgfbr2, by removing doxycycline at birth, is not associated with significant changes in mesenchymal stromal cells in the bone marrow. Moreover, expression of key niche factors, including Cxcl12 and stem cell factor, and basal hematopoiesis were normal in these mice. Thus, we used the post-natal Osx-Cre; Tgfbr2-deleted mice as recipients to assess the role of TGF-β signaling in mesenchymal stromal cells on the hematopoietic and myelofibrosis phenotype in Jak2V617F or MPLW515L models of MPN. Specifically, we transplanted hematopoietic cells from Mx1-Cre; Jak2V617F mice (4 weeks after pIpC treatment) or hematopoietic cells transduced with MPLW515L retrovirus into irradiated wildtype or post-natal Osx-Cre; Tgfbr2-deleted mice. Both MPN models have elevated Tgfb1 expression in the bone marrow. As reported previously, transplantation of MPLW515L transduced hematopoietic cells into wildtype recipients produced a rapidly fatal MPN characterized by neutrophilia, erythrocytosis, thrombocytosis, splenomegaly, and reticulin fibrosis in the bone marrow. A similar hematopoietic phenotype was observed in Osx-Cre; Tgfbr2fl/fl recipients. However, a trend to decreased reticulin fibrosis was observed in Osx-Cre; Tgfbr2fl/fl compared to wildtype recipients (reticulin histology score: 0.5 versus 1.1, respectively, n=5, p=0.23). Likewise, the degree of neutrophilia, erythrocytosis, thrombocytosis, and splenomegaly in wildtype and Osx-Cre; Tgfbr2fl/fl recipients of Jak2V617F cells was similar. As reported previously, we did not observe overt myelofibrosis in this model (as measured by reticulin staining). However, we were able to detect increased collagen III deposition using immunofluorescence staining in 4 of 5 wildtype recipients compared to 1 of 4 Osx-Cre Tgfbr2fl/flrecipients of Jak2V617F cells (p=0.21).In conclusion, our data suggest that TGF-β signaling in mesenchymal stromal cells contributes, but is not absolutely required, for the development of myelofibrosis. Alterations in mesenchymal stromal cells induced by increased TGF-β signaling do not appear to be a major driver of the myeloid expansion in MPN. The contribution of increased TGF-β signaling in hematopoietic cells or other bone marrow stromal cell populations to the MPN phenotype is under investigation. DisclosuresNo relevant conflicts of interest to declare.

A Study of Tbo-Filgrastim (Granix) to Disrupt the Bone Marrow Microenvironment in Patients with Multiple Myeloma Undergoing Autologous Stem Cell Transplantation

Multiple myeloma is the second most common hematologic malignancy in the US. The current standard of care for transplant eligible patients is therapy with high-dose melphalan (HDM) followed by autologous stem cell transplant (ASCT). Although ASCT improves progression-free (PFS) and overall survival (OS), it is not curative and virtually all patients will relapse. Attempts to improve upon HDM by adding other agents to transplant protocols have largely resulted in unacceptable increases in toxicity.Preclinical studies performed by our group suggest that granulocyte-stimulating factor (G-CSF) disrupts the bone marrow microenvironment, resulting in a striking loss of plasmablasts, plasma cells, and decreased expression of chemokine/cytokines contributing to plasma cell maintenance. Tbo-filgrastim (Granix, Teva Pharmaceuticals) is a recombinant methionyl human granulocyte colony-stimulating factor. We hypothesized that tbo-filgrastim treatment may provide a potent and well-tolerated method to disrupt the ‘myeloma cell niche’, rendering patients more sensitive to HDM.Methods: Here, we report results from an open label, single center, phase II randomized study to test the efficacy and safety of tbo-filgrastim plus HDM (tbo-filgrastim arm) versus HDM alone (SOC arm) prior to ASCT (NCT02112045). Patients were randomized 1:1 to tbo-filgrastim on Day -7 through Day -2 (480 or 960 mcg/day, based on weight) and melphalan on Day -2 prior to ASCT (140 or 200 mg/m2, based on age) or melphalan alone. The primary objective was to compare CR rate at day 100. Secondary objectives included comparison of the toxicity, overall response rate, PFS, OS, and rate of neutrophil and platelet engraftment between the two arms. Eligible patients were ≥18 years with symptomatic multiple myeloma enrolled within 12 months of receiving at least 2 cycles of any systemic therapy, were undergoing their first ASCT, and had an adequate ASCT collection product (at least 2 million CD34+ cells/kg). Target enrollment was 176 patients, with an interim analysis of efficacy and futility planned after 88 patients reached Day 100 post-ASCT. Early stopping rules for unacceptable toxicity were in place. Responses were evaluated by IMWG criteria.Results: Ninety patients were enrolled (median age 59.5, range 33 to 77) and 89 were evaluable for response. The early stopping rules for toxicity were not met. The planned interim analysis showed that the proportion of patients in CR at Day 100 was similar between the arms and the study was halted for futility (39.5% on the tbo-filgrastim arm vs. 37.8% on SOC arm). The overall response rate (CR + VGPR + PR) between the tbo-filgrastim and the SOC arm was 95% vs 93%, respectively. At the interim analysis, with median follow-up time for the study of 21.7 months, (range 8.8 to 25.8), the median PFS and OS had not been reached for either arm. There was no difference in PFS between the tbo-filgrastim and the SOC arm (84% vs 80%, respectively, p=0.60). There was no difference in OS between the tbo-filgrastim and the SOC arm (90.9% vs 95.6%, respectively, p=0.43). All patients in the study achieved neutrophil (ANC > 0.5 K/cumm) and platelet (> 20 K/cumm) engraftment. The median time to neutrophil engraftment for the tbo-filgrastim arm was 5 days (range, 3-9) vs 4 days (range, 3-7) in the SOC arm, p<0.001. There was no difference in the median time to platelet engraftment between the arms (11 days in the tbo-filgrastim arm, range 2-23, and 10 days in the SOC arm, range 1-24, p=0.67). Adverse events for both arms were typical of those observed in the ASCT population.Conclusions: The administration of tbo-filgrastim in the setting of HDM prior to ASCT is feasible, without excess toxicity or loss of engraftment. There was no difference in Day +100 CR or ORR rates, PFS, or OS in patients treated with tbo-filgrastim plus HDM versus HDM alone with a median follow-up of 21.7 months. The lack of efficacy may be secondary to the high pre-ASCT response rates seen with modern agents. DisclosuresJacoby:Celgene: Speakers Bureau; NovoNordisk: Consultancy. Schroeder:Amgen Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees. Vij:Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Jazz Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees; Jansson: Honoraria, Membership on an entity's Board of Directors or advisory committees; Karyopharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.