VEXAS syndrome: complete molecular remission after hypomethylating therapy.

The VEXAS syndrome, a genetically defined autoimmune disease, associated with various hematological neoplasms has been attracting growing attention since its initial description in 2020. While various therapeutic strategies have been explored in case studies, the optimal treatment strategy is still under investigation and allogeneic cell transplantation is considered the only curative treatment. Here, we describe 2 patients who achieved complete molecular remission of the underlying UBA1 mutant clone outside the context of allogeneic HCT. Both patients received treatment with the hypomethylating agent azacitidine, and deep molecular remission triggered treatment de-escalation and even cessation with sustained molecular remission in one of them. Prospective studies are necessary to clarify which VEXAS patients will benefit most from hypomethylating therapy and to understand the variability in the response to different treatment strategies.

Machine learning assisted real-time deformability cytometry of CD34+ cells allows to identify patients with myelodysplastic syndromes.

Diagnosis of myelodysplastic syndrome (MDS) mainly relies on a manual assessment of the peripheral blood and bone marrow cell morphology. The WHO guidelines suggest a visual screening of 200 to 500 cells which inevitably turns the assessor blind to rare cell populations and leads to low reproducibility. Moreover, the human eye is not suited to detect shifts of cellular properties of entire populations. Hence, quantitative image analysis could improve the accuracy and reproducibility of MDS diagnosis. We used real-time deformability cytometry (RT-DC) to measure bone marrow biopsy samples of MDS patients and age-matched healthy individuals. RT-DC is a high-throughput (1000 cells/s) imaging flow cytometer capable of recording morphological and mechanical properties of single cells. Properties of single cells were quantified using automated image analysis, and machine learning was employed to discover morpho-mechanical patterns in thousands of individual cells that allow to distinguish healthy vs. MDS samples. We found that distribution properties of cell sizes differ between healthy and MDS, with MDS showing a narrower distribution of cell sizes. Furthermore, we found a strong correlation between the mechanical properties of cells and the number of disease-determining mutations, inaccessible with current diagnostic approaches. Hence, machine-learning assisted RT-DC could be a promising tool to automate sample analysis to assist experts during diagnosis or provide a scalable solution for MDS diagnosis to regions lacking sufficient medical experts.

Half-dose glucarpidase as efficient rescue for toxic methotrexate levels in patients with acute kidney injury.

PURPOSE: High-dose methotrexate (HDMTX)-associated acute kidney injury with delayed MTX clearance has been linked to an excess in MTX-induced toxicities. Glucarpidase is a recombinant enzyme that rapidly hydrolyzes MTX into non-toxic metabolites. The recommended dose of glucarpidase is 50 U/kg, which has never been formally established in a dose finding study in humans. Few case reports, mostly in children, suggest that lower doses of glucarpidase might be equally effective in lowering MTX levels. METHODS: Seven patients with toxic MTX plasma concentrations following HDMTX therapy were treated with half-dose glucarpidase (mean 25 U/kg, range 17-32 U/kg). MTX levels were measured immunologically as well as by liquid chromatography-mass spectrometry (LC-MS). Toxicities were assessed according to National Cancer Institute-Common Terminology Criteria for Adverse Events (CTCAE) v5.0. RESULTS: All patients experienced HDMTX-associated kidney injury (median increase in creatinine levels within 48 h after HDMTX initiation compared to baseline of 251%, range 80-455%) and showed toxic MTX plasma concentrations (range 3.1-182.4 µmol/L) before glucarpidase injection. The drug was administered 42-70 h after HDMTX initiation. Within one day after glucarpidase injection, MTX plasma concentrations decreased by ≥ 97.7% translating into levels of 0.02-2.03 µmol/L. MTX rebound was detected in plasma 42-73 h after glucarpidase initiation, but concentrations remained consistent at < 10 µmol/L. CONCLUSION: Half-dose glucarpidase seems to be effective in lowering MTX levels to concentrations manageable with continued intensified folinic acid rescue.

Myelodysplastic Syndromes and Metabolism.

Myelodysplastic syndromes (MDS) are acquired clonal stem cell disorders exhibiting ineffective hematopoiesis, dysplastic cell morphology in the bone marrow, and peripheral cytopenia at early stages; while advanced stages carry a high risk for transformation into acute myeloid leukemia (AML). Genetic alterations are integral to the pathogenesis of MDS. However, it remains unclear how these genetic changes in hematopoietic stem and progenitor cells (HSPCs) occur, and how they confer an expansion advantage to the clones carrying them. Recently, inflammatory processes and changes in cellular metabolism of HSPCs and the surrounding bone marrow microenvironment have been associated with an age-related dysfunction of HSPCs and the emergence of genetic aberrations related to clonal hematopoiesis of indeterminate potential (CHIP). The present review highlights the involvement of metabolic and inflammatory pathways in the regulation of HSPC and niche cell function in MDS in comparison to healthy state and discusses how such pathways may be amenable to therapeutic interventions.

Increased FGF-23 levels are linked to ineffective erythropoiesis and impaired bone mineralization in myelodysplastic syndromes.

Myelodysplastic syndromes (MDS) are clonal malignant hematopoietic disorders in the elderly characterized by ineffective hematopoiesis. This is accompanied by an altered bone microenvironment, which contributes to MDS progression and higher bone fragility. The underlying mechanisms remain largely unexplored. Here, we show that myelodysplastic NUP98­HOXD13 (NHD13) transgenic mice display an abnormally high number of osteoblasts, yet a higher fraction of nonmineralized bone, indicating delayed bone mineralization. This was accompanied by high fibroblast growth factor-23 (FGF-23) serum levels, a phosphaturic hormone that inhibits bone mineralization and erythropoiesis. While Fgf23 mRNA expression was low in bone, brain, and kidney of NHD13 mice, its expression was increased in erythroid precursors. Coculturing these precursors with WT osteoblasts induced osteoblast marker gene expression, which was inhibited by blocking FGF-23. Finally, antibody-based neutralization of FGF-23 in myelodysplastic NHD13 mice improved bone mineralization and bone microarchitecture, and it ameliorated anemia. Importantly, higher serum levels of FGF­23 and an elevated amount of nonmineralized bone in patients with MDS validated the findings. C­terminal FGF­23 correlated negatively with hemoglobin levels and positively with the amount of nonmineralized bone. Thus, our study identifies FGF-23 as a link between altered bone structure and ineffective erythropoiesis in MDS with the prospects of a targeted therapeutic intervention.

Effects of rigosertib on the osteo-hematopoietic niche in myelodysplastic syndromes.

Rigosertib is a novel multi-kinase inhibitor, which has clinical activity towards leukemic progenitor cells of patients with high-risk myelodysplastic syndromes (MDS) after failure or progression on hypomethylating agents. Since the bone marrow microenvironment plays an important role in MDS pathogenesis, we investigated the impact of rigosertib on cellular compartments within the osteo-hematopoietic niche. Healthy C57BL/6J mice treated with rigosertib for 3 weeks showed a mild suppression of hematopoiesis (hemoglobin and red blood cells, both - 16%, p < 0.01; white blood cells, - 34%, p < 0.05; platelets, - 38%, p < 0.05), whereas there was no difference in the number of hematopoietic stem cells in the bone marrow. Trabecular bone mass of the spine was reduced by rigosertib (- 16%, p = 0.05). This was accompanied by a lower trabecular number and thickness (- 6% and - 10%, respectively, p < 0.05), partly explained by the increase in osteoclast number and surface (p < 0.01). Milder effects of rigosertib on bone mass were detected in an MDS mouse model system (NHD13). However, rigosertib did not further aggravate MDS-associated cytopenia in NHD13 mice. Finally, we tested the effects of rigosertib on human mesenchymal stromal cells (MSC) in vitro and demonstrated reduced cell viability at nanomolar concentrations. Deterioration of the hematopoietic supportive capacity of MDS-MSC after rigosertib pretreatment demonstrated by decreased number of colony-forming units, especially in the monocytic lineage, further supports the idea of disturbed crosstalk within the osteo-hematopoietic niche mediated by rigosertib. Thus, rigosertib exerts inhibitory effects on the stromal components of the osteo-hematopoietic niche which may explain the dissociation between anti-leukemic activity and the absence of hematological improvement.

Treatment of Pegylated Asparaginase-Induced Hypertriglyceridemia with Continuous Intravenous Infusion of Insulin and Heparin: A Case Report.

BACKGROUND: Pegylated asparaginase may induce prolonged hypertriglyceridemia. To date, there is no standard management of this complication. Here, we present a case report of pegylated asparaginase-induced hypertriglyceridemia and hepatotoxicity successfully treated with continuous intravenous infusion of insulin and heparin. CASE PRESENTATION: A 51-year-old male patient with lymphoid blast crisis of chronic myelogenous leukemia was treated with pegylated asparaginase. The patient developed severe hypertriglyceridemia. Supportive therapy with low-fat diet, fibric acids, and omega-3 fatty acids was not successful, and later, the patient developed high-grade hepatotoxicity. Like hypertriglyceridemia-induced pancreatitis, continuous intravenous infusion of insulin and heparin was initiated. The level of triglyceride and cholesterol decreased rapidly within 4 days. CONCLUSION: In case of severe pegylated asparaginase-induced hypertriglyceridemia, continuous intravenous infusion of insulin and heparin can reduce rapidly and safely the triglyceride level. Controlled trials are needed to address this important issue.

Erythropoietin inhibits osteoblast function in myelodysplastic syndromes via the canonical Wnt pathway.

The effects of erythropoietin on osteoblasts and bone formation are controversial. Since patients with myelodysplastic syndromes often display excessively high erythropoietin levels, we aimed to analyze the effect of erythropoietin on osteoblast function in myelodysplastic syndromes and define the role of Wnt signaling in this process. Expression of osteoblast-specific genes and subsequent osteoblast mineralization was increased in mesenchymal stromal cells from healthy young donors by in vitro erythropoietin treatment. However, erythropoietin failed to increase osteoblast mineralization in old healthy donors and in patients with myelodysplasia, whereas the basal differentiation potential of the latter was already significantly reduced compared to that of age-matched controls (P<0.01). This was accompanied by a significantly reduced expression of genes of the canonical Wnt pathway. Treatment of these cells with erythropoietin further inhibited the canonical Wnt pathway. Exposure of murine cells (C2C12) to erythropoietin also produced a dose-dependent inhibition of TCF/LEF promoter activity (maximum at 500 IU/mL, -2.8-fold; P<0.01). The decreased differentiation capacity of erythropoietin-pretreated mesenchymal stromal cells from patients with myelodysplasia could be restored by activating the Wnt pathway using lithium chloride or parathyroid hormone. Its hematopoiesis-supporting capacity was reduced, while reactivation of the canonical Wnt pathway in mesenchymal stromal cells could reverse this effect. Thus, these data demonstrate that erythropoietin modulates components of the osteo-hematopoietic niche in a context-dependent manner being anabolic in young, but catabolic in mature bone cells. Targeting the Wnt pathway in patients with myelodysplastic syndromes may be an appealing strategy to promote the functional capacity of the osteo-hematopoietic niche.

Wnt5a is a key target for the pro-osteogenic effects of iron chelation on osteoblast progenitors.

Iron overload due to hemochromatosis or chronic blood transfusions has been associated with the development of osteoporosis. However, the impact of changes in iron homeostasis on osteoblast functions and the underlying mechanisms are poorly defined. Since Wnt signaling is a critical regulator of bone remodeling, we aimed to analyze the effects of iron overload and iron deficiency on osteoblast function, and further define the role of Wnt signaling in these processes. Therefore, bone marrow stromal cells were isolated from wild-type mice and differentiated towards osteoblasts. Exposure of the cells to iron dose-dependently attenuated osteoblast differentiation in terms of mineralization and osteogenic gene expression, whereas iron chelation with deferoxamine promoted osteogenic differentiation in a time- and dose-dependent manner up to 3-fold. Similar results were obtained for human bone marrow stromal cells. To elucidate whether the pro-osteogenic effect of deferoxamine is mediated via Wnt signaling, we performed a Wnt profiler array of deferoxamine-treated osteoblasts. Wnt5a was amongst the most highly induced genes. Further analysis revealed a time- and dose-dependent induction of Wnt5a being up-regulated 2-fold after 48 h at 50 µM deferoxamine. Pathway analysis using specific inhibitors revealed that deferoxamine utilized the phosphatidylinositol-3-kinase and nuclear factor of activated T cell pathways to induce Wnt5a expression. Finally, we confirmed the requirement of Wnt5a in the deferoxamine-mediated osteoblast-promoting effects by analyzing the matrix mineralization of Wnt5a-deficient cells. The promoting effect of deferoxamine on matrix mineralization in wild-type cells was completely abolished in Wnt5a-/- cells. Thus, these data demonstrate that Wnt5a is critical for the pro-osteogenic effects of iron chelation using deferoxamine.

Selective expansion of regulatory T cells during lenalidomide treatment of myelodysplastic syndrome with isolated deletion 5q.

Lenalidomide (LEN) leads to erythroid improvement in the majority of patients with myelodysplastic syndrome and isolated deletion of the long arm of chromosome 5 (MDS-del(5q)). This effect is believed to be exerted via its immunomodulatory properties, although the precise nature is still incompletely understood. We prospectively performed immune profiling in the bone marrow and blood of MDS-del(5q) patients undergoing LEN therapy for a median of 6 cycles. Therapy with LEN led to a significant increase in the median absolute lymphocyte count (1.3-fold, p = 0.013) without changes in the distribution of the T helper cells within the entire compartment. In parallel, the frequency of Treg increased significantly during treatment both in the peripheral blood (5.0 vs. 9.6 %, p = 0.001) and bone marrow (3.4 vs. 8.1 %, p = 0.001). Surprisingly, LEN treatment led to a decrease in TGFbeta levels, both in the peripheral blood (4.9 vs. 2.3 ng/ml, p = 0.039) and bone marrow (4.5 vs. 0.8 ng/ml, p = 0.023). These changes were not associated with an increase in pro-inflammatory Th17 cells. Taken together, our results demonstrate that LEN induces a shift in lymphocytic populations towards immunosuppression in MDS-del(5q) patients.

Mutational hierarchies in myelodysplastic syndromes dynamically adapt and evolve upon therapy response and failure.

Clonal evolution is believed to be a main driver for progression of various types of cancer and implicated in facilitating resistance to drugs. However, the hierarchical organization of malignant clones in the hematopoiesis of myelodysplastic syndromes (MDS) and its impact on response to drug therapy remain poorly understood. Using high-throughput sequencing of patient and xenografted cells, we evaluated the intratumoral heterogeneity (n= 54) and reconstructed mutational trajectories (n = 39) in patients suffering from MDS (n = 52) and chronic myelomonocytic leukemia-1 (n = 2). We identified linear and also branching evolution paths and confirmed on a patient-specific level that somatic mutations in epigenetic regulators and RNA splicing genes frequently constitute isolated disease-initiating events. Using high-throughput exome- and/or deep-sequencing, we analyzed 103 chronologically acquired samples from 22 patients covering a cumulative observation time of 75 years MDS disease progression. Our data revealed highly dynamic shaping of complex oligoclonal architectures, specifically upon treatment with lenalidomide and other drugs. Despite initial clinical response to treatment, patients' marrow persistently remained clonal with rapid outgrowth of founder-, sub-, or even fully independent clones, indicating an increased dynamic rate of clonal turnover. The emergence and disappearance of specific clones frequently correlated with changes of clinical parameters, highlighting their distinct and far-reaching functional properties. Intriguingly, increasingly complex mutational trajectories are frequently accompanied by clinical progression during the course of disease. These data substantiate a need for regular broad molecular monitoring to guide clinical treatment decisions in MDS.

Effects of a home-based exercise program on physical capacity and fatigue in patients with low to intermediate risk myelodysplastic syndrome-a pilot study.

INTRODUCTION: Fatigue is a frequent and disabling symptom in myelodysplastic syndromes (MDS). There is evidence for the benefit of exercise on fatigue in haematological malignancies, but clinical trials targeting patients with MDS do not exist. METHODS: A prospective, non-randomized feasibility trial was conducted to assess the safety and efficacy of a home-based exercise intervention in patients with MDS. Exercise schedule contained endurance or strength training in daily turns over 12 weeks. Outcome measures included 6-min walking distance (6-MWD), an ergometer check, strength measurement of lower limb, abdomen and back, quality of life and fatigue. RESULTS: Twenty-one patients (13 male, 8 female) were included. Median age was 66 years (range 29-87). Fifteen patients (71%) continued the program till week 12 (T1), of whom eleven patients met criteria for program completion. There were no adverse events reported due to the intervention. 6-MWD significantly improved from 580m at T0 to 645m at T1 (p<0.05). Fatigue scores did not significantly change over time (MFI: 12.8 vs. 12.3 vs. 11.9; QLQ-C30 fatigue scale: 48.2 vs. 46.7 vs. 47.4). CONCLUSION: These data provide evidence that an unsupervised outpatient exercise program is feasible and can improve physical capacity. Randomized, controlled studies implementing these interventions are warranted.