Dietary iron restriction protects against vaso-occlusion and organ damage in murine sickle cell disease.

Sickle cell disease (SCD) is an inherited disorder resulting from a ß-globin gene mutation, and SCD patients experience erythrocyte sickling, vaso-occlusive episodes (VOE), and progressive organ damage. Chronic hemolysis, inflammation, and repeated red blood cell transfusions in SCD can disrupt iron homeostasis. Patients who receive multiple blood transfusions develop iron overload, and another subpopulation of SCD patients manifest iron deficiency. To elucidate connections between dietary iron, the microbiome, and SCD pathogenesis, we treated SCD mice with an iron-restricted diet (IRD). IRD treatment reduced iron availability and hemolysis, decreased acute VOE, and ameliorated chronic organ damage in SCD mice. Our results extend previous studies indicating that the gut microbiota regulate disease in SCD mice. IRD alters microbiota load and improves gut integrity, together preventing crosstalk between the gut microbiome and inflammatory factors such as aged neutrophils, dampening VOE, and organ damage. These findings provide strong evidence for the therapeutic potential of manipulating iron homeostasis and the gut microbiome to ameliorate SCD pathophysiology. Many treatments, which are under development, focus on lowering the systemic iron concentration to relieve disease complications, and our data suggest that iron-induced changes in microbiota load and gut integrity are related- and novel-therapeutic targets.

Vitamin K antagonism impairs the bone marrow microenvironment and hematopoiesis.

Vitamin K antagonists (VKAs) have been used in 1% of the world's population for prophylaxis or treatment of thromboembolic events for 64 years. Impairment of osteoblast function and osteoporosis has been described in patients receiving VKAs. Given the involvement of cells of the bone marrow microenvironment (BMM), such as mesenchymal stem cells (MSCs) and macrophages, as well as other factors such as the extracellular matrix for the maintenance of normal hematopoietic stem cells (HSCs), we investigated a possible effect of VKAs on hematopoiesis via the BMM. Using various transplantation and in vitro assays, we show here that VKAs alter parameters of bone physiology and reduce functional HSCs 8-fold. We implicate impairment of the functional, secreted, vitamin K-dependent, γ-carboxylated form of periostin by macrophages and, to a lesser extent, MSCs of the BMM and integrin ß3-AKT signaling in HSCs as at least partly causative of this effect, with VKAs not being directly toxic to HSCs. In patients, VKA use associates with modestly reduced leukocyte and monocyte counts, albeit within the normal reference range. VKAs decrease human HSC engraftment in immunosuppressed mice. Following published examples that alteration of the BMM can lead to hematological malignancies in mice, we describe, without providing a causal link, that the odds of VKA use are higher in patients with vs without a diagnosis of myelodysplastic syndrome (MDS). These results demonstrate that VKA treatment impairs HSC function via impairment of the BMM and the periostin/integrin ß3 axis, possibly associating with increased MDS risk.

Testosterone therapy as a novel approach to the management of cytopenias in myelodysplastic neoplasms: a review of literature and case report.

PURPOSE: To explore the potential of testosterone therapy in managing cytopenias in myelodysplastic neoplasm and investigate the link between hypogonadism and hematologic malignancies. METHODS: A case of a patient with intermediate-risk myelodysplastic neoplasm and hypogonadism treated with testosterone replacement therapy is presented. Testosterone, prostate specific antigen, and erythropoietin levels were checked prior to therapy initiation and 3 months after. Blood counts were monitored over time. This is followed by a literature review of testosterone use in myelodysplastic neoplasm and the prevalence of hypogonadism in hematologic malignancies. RESULTS: The patient showed sustained improvement in anemia with testosterone therapy and reported subjective improvement in his weakness and fatigue. This improvement occurred even in the setting of an undetectable follow up erythropoietin level. His repeat prostate specific antigen levels remained low, while testosterone levels showed marked improvement. The literature review demonstrated positive response rates for testosterone in treating myelodysplastic neoplasm-related cytopenias, and showed a higher incidence of hypogonadism in hematologic malignancies. CONCLUSION: Our review suggests that the use of testosterone in low and intermediate-risk myelodysplastic neoplasm is underexplored and poses to have significant potential as a future therapeutic agent, after careful consideration of risks and benefits. In addition, the incidence of hypogonadism in myelodysplastic neoplasm and its potential impact on exacerbating cytopenias in myelodysplastic neoplasm warrants further investigation.

A STAT3 Degrader Demonstrates Pre-clinical Efficacy in Venetoclax resistant Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) is an aggressive hematologic malignancy that continues to have poor prognosis despite recent therapeutic advances. Venetoclax (Ven), a BCL2-inhibitor has shown a high response rate in AML; however, relapse is invariable due to mitochondrial dysregulation that includes upregulation of the antiapoptotic protein MCL1, a central mechanism of Ven resistance (Ven-res). We have previously demonstrated that the transcription factor STAT3 is upregulated in AML hematopoietic stem and progenitor cells (HSPCs) and can be effectively targeted to induce apoptosis of these aberrant cells. We now show that overexpression of STAT3 alone is sufficient to initiate a strong AML phenotype in a transgenic murine model. Phospho-proteomic data from Ven treated AML patients show a strong correlation of high total STAT3 and phospho-STAT3 [both p-STAT3(Y705) and p-STAT3(S727)] expression with worse survival and reduced remission duration. Additionally, significant upregulation of STAT3 was observed in Ven-res cell lines, in vivo models and primary patient samples. A novel and specific degrader of STAT3 demonstrated targeted reduction of total STAT3 and resulting inhibition of its active p-STAT3(Y705) and p-STAT3(S727) forms. Treatment with the STAT3 degrader induced apoptosis in parental and Ven-res AML cell lines and decreased mitochondrial depolarisation, and thereby dependency on MCL1 in Ven-res AML cell line, as observed by BH3 profiling assay. STAT3 degrader treatment also enhanced differentiation of myeloid and erythroid colonies in Ven-res peripheral blood mononuclear cells (PBMNCs). Upregulation of p-STAT3(S727) was also associated with pronounced mitochondrial structural and functional dysfunction in Ven-res cell lines, that were restored by STAT3 degradation. Treatment with a clinical-stage STAT3 degrader, KT-333 resulted in a significant reduction in STAT3 and MCL1 protein levels within two weeks of treatment in a cell derived xenograft model of Ven-res AML. Additionally, this treatment significant improvement in the survival of a Ven-res patient-derived xenograft in-vivo study. Degradation of STAT3 resulting in downregulation of MCL1 and improvements in global mitochondrial dysfunction suggests a novel mechanism of overcoming Ven-res in AML. Statement of Purpose: Five-year survival from AML is dismal at 30%. Our prior research demonstrated STAT3 over-expression in AML HSPC's to be associated with inferior survival. We now explore STAT3 over-expression in Ven-res AML, explain STAT3 mediated mitochondrial perturbations and describe a novel therapeutic strategy, STAT3 degradation to overcome Ven-res.

Glutaminase inhibition in combination with azacytidine in myelodysplastic syndromes: a phase 1b/2 clinical trial and correlative analyses.

Malignancies are reliant on glutamine as an energy source and a facilitator of aberrant DNA methylation. We demonstrate preclinical synergy of telaglenastat (CB-839), a selective glutaminase inhibitor, combined with azacytidine (AZA), followed by a single-arm, open-label, phase 1b/2 study in persons with advanced myelodysplastic syndrome (MDS). The dual primary endpoints evaluated clinical activity, safety and tolerability; secondary endpoints evaluated pharmacokinetics, pharmacodynamics, overall survival, event-free survival and duration of response. The dose-escalation study included six participants and the dose-expansion study included 24 participants. Therapy was well tolerated and led to an objective response rate of 70% with (marrow) complete remission in 53% of participants and a median overall survival of 11.6 months, with evidence of myeloid differentiation in responders determined by single-cell RNA sequencing. Glutamine transporter solute carrier family 38 member 1 in MDS stem cells was associated with clinical responses and predictive of worse prognosis in a large MDS cohort. These data demonstrate the safety and efficacy of CB-839 and AZA as a combined metabolic and epigenetic approach in MDS. ClinicalTrials.gov identifier: NCT03047993 .

Future directions in preclinical and translational cancer neuroscience research.

Recent advances in cancer neuroscience necessitate the systematic analysis of neural influences in cancer as potential therapeutic targets in oncology. Here, we outline recommendations for future preclinical and translational research in this field.

Bone marrow niche-derived extracellular matrix-degrading enzymes influence the progression of B-cell acute lymphoblastic leukemia.

Specific and reciprocal interactions with the bone marrow microenvironment (BMM) govern the course of hematological malignancies. Matrix metalloproteinase-9 (MMP-9), secreted by leukemia cells, facilitates tumor progression via remodeling of the extracellular matrix (ECM) of the BMM. Hypothesizing that leukemias may instruct the BMM to degrade the ECM, we show, that MMP-9-deficiency in the BMM prolongs survival of mice with BCR-ABL1-induced B-cell acute lymphoblastic leukemia (B-ALL) compared with controls and reduces leukemia-initiating cells. MMP-9-deficiency in the BMM leads to reduced degradation of proteins of the ECM and reduced invasion of B-ALL. Using various in vivo and in vitro assays, as well as recipient mice deficient for the receptor for tumor necrosis factor (TNF) α (TNFR1) we demonstrate that B-ALL cells induce MMP-9-expression in mesenchymal stem cells (MSC) and possibly other cells of the BMM via a release of TNFα. MMP-9-expression in MSC is mediated by activation of nuclear factor kappa B (NF-κB) downstream of TNFR1. Consistently, knockdown of TNF-α in B-ALL-initiating cells or pharmacological inhibition of MMP-9 led to significant prolongation of survival in mice with B-ALL. In summary, leukemia cell-derived Tnfα induced MMP-9-expression by the BMM promoting B-ALL progression. Inhibition of MMP-9 may act as an adjunct to existing therapies.

Clinically Actionable Strategies for Studying Neural Influences in Cancer.

Neuro-glial activation is a recently identified hallmark of growing cancers. Targeting tumor hyperinnervation in preclinical and small clinical trials has yielded promising antitumor effects, highlighting the need of systematic analysis of neural influences in cancer (NIC). Here, we outline the strategies translating these findings from bench to the clinic.

The transcriptional regulator FUBP1 influences disease outcome in murine and human myeloid leukemia.

The transcriptional regulator far upstream element binding protein 1 (FUBP1) acts as an oncoprotein in solid tumor entities and plays a role in the maintenance of hematopoietic stem cells. However, its potential function in leukemia is unknown. In murine models of chronic (CML) and acute myeloid leukemia (AML) induced by BCR-ABL1 and MLL-AF9, respectively, knockdown of Fubp1 resulted in prolonged survival, decreased numbers of CML progenitor cells, decreased cell cycle activity and increased apoptosis. Knockdown of FUBP1 in CML and AML cell lines recapitulated these findings and revealed enhanced DNA damage compared to leukemia cells expressing wild type FUBP1 levels. FUBP1 was more highly expressed in human CML compared to normal bone marrow cells and its expression correlated with disease progression. In AML, higher FUBP1 expression in patient leukemia cells was observed with a trend toward correlation with shorter overall survival. Treatment of mice with AML with irinotecan, known to inhibit topoisomerase I and FUBP1, significantly prolonged survival alone or in combination with cytarabine. In summary, our data suggest that FUBP1 acts as cell cycle regulator and apoptosis inhibitor in leukemia. We demonstrated that FUBP1 might play a role in DNA repair, and its inhibition may improve outcome in leukemia patients.