Aggregates of nonmuscular myosin IIA in erythrocytes associate with GATA1- and GFI1B-related thrombocytopenia

BACKGROUND

The transcription factor GATA1 is an essential regulator of erythroid cell gene expression and maturation and is also relevant for platelet biogenesis. GATA1-related thrombocytopenia (GATA1-RT) is a rare X-linked inherited platelet disorder (IPD) characterized by macrothrombocytopenia and dyserythropoiesis. Enlarged platelet size, reduced platelet granularity, and noticeable red blood cell anisopoikilocytosis are characteristic but unspecific morphological findings in GATA1-RT.

OBJECTIVES

To expand the investigation of platelet phenotype of patients with GATA1-RT by light- and immunofluorescence microscopy on a blood smear.

METHODS

We assessed blood smears by light- and immunofluorescence microscopy after May-Grünwald Giemsa staining using a set of 13 primary antibodies against markers belonging to different platelet structures. Antibody binding was visualized by fluorescently labeled secondary antibodies.

RESULTS

We investigated 12 individuals with genetically confirmed GATA1-RT from 8 unrelated families. While confirming the already known characteristic of platelet morphology (platelet macrocytosis and reduced expression of markers for α-granules), we also found aggregates of nonmuscular myosin heavy chain II A (NMMIIA) in the erythrocytes in all individuals (1-3 aggregates/cell, 1-3 μm diameter). By systematically reanalyzing blood smears from a cohort of patients with 19 different forms of IPD, we found similar NMMIIA aggregates in the red blood cells only in subjects with GFI1B-related thrombocytopenia (GFI1B-RT), the other major IPD featured by dyserythropoiesis.

CONCLUSION

Aggregates of NMMIIA in the erythrocytes associate with GATA1-RT and GFI1B-RT and can facilitate their diagnosis on blood smears. This previously unreported finding might represent a novel marker of dyserythropoiesis assessable in peripheral blood.

ROP-ET: a prospective phase III trial investigating the efficacy and safety of ropeginterferon alfa-2b in essential thrombocythemia patients with limited treatment options

Interferon-based therapies, such as ropeginterferon alfa-2b have emerged as promising disease-modifying agents for myeloproliferative neoplasms (MPNs), including essential thrombocythemia (ET). Current ET treatments aim to normalize hematological parameters and reduce the thrombotic risk, but they do not modify the natural history of the disease and hence, have no impact on disease progression. Ropeginterferon alfa-2b (trade name BESREMi®), a novel, monopegylated interferon alfa-2b with an extended administration interval, has demonstrated a robust and sustained efficacy in polycythemia vera (PV) patients. Given the similarities in disease pathophysiology and treatment goals, ropeginterferon alfa-2b holds promise as a treatment option for ET. The ROP-ET trial is a prospective, multicenter, single-arm phase III study that includes patients with ET who are intolerant or resistant to, and/or are ineligible for current therapies, such as hydroxyurea (HU), anagrelide (ANA), busulfan (BUS) and pipobroman, leaving these patients with limited treatment options. The primary endpoint is a composite response of hematologic parameters and disease-related symptoms, according to modified European LeukemiaNet (ELN) criteria. Secondary endpoints include improvements in symptoms and quality of life, molecular response and the safety profile of ropeginterferon alfa-2b. Over a 3-year period the trial assesses longer term outcomes, particularly the effects on allele burden and clinical outcomes, such as disease-related symptoms, vascular events and disease progression. No prospective clinical trial data exist for ropeginterferon alfa-2b in the planned ET study population and this study will provide new findings that may contribute to advancing the treatment landscape for ET patients with limited alternatives. TRIAL REGISTRATION: EU Clinical Trials Register; EudraCT, 2023-505160-12-00; Registered on October 30, 2023.

Imetelstat-mediated alterations in fatty acid metabolism to induce ferroptosis as a therapeutic strategy for acute myeloid leukemia

Telomerase enables replicative immortality in most cancers including acute myeloid leukemia (AML). Imetelstat is a first-in-class telomerase inhibitor with clinical efficacy in myelofibrosis and myelodysplastic syndromes. Here, we develop an AML patient-derived xenograft resource and perform integrated genomics, transcriptomics and lipidomics analyses combined with functional genetics to identify key mediators of imetelstat efficacy. In a randomized phase II-like preclinical trial in patient-derived xenografts, imetelstat effectively diminishes AML burden and preferentially targets subgroups containing mutant NRAS and oxidative stress-associated gene expression signatures. Unbiased, genome-wide CRISPR/Cas9 editing identifies ferroptosis regulators as key mediators of imetelstat efficacy. Imetelstat promotes the formation of polyunsaturated fatty acid-containing phospholipids, causing excessive levels of lipid peroxidation and oxidative stress. Pharmacological inhibition of ferroptosis diminishes imetelstat efficacy. We leverage these mechanistic insights to develop an optimized therapeutic strategy using oxidative stress-inducing chemotherapy to sensitize patient samples to imetelstat causing substantial disease control in AML.

Immunoproteasome function maintains oncogenic gene expression in KMT2A-complex driven leukemia

Pharmacologic targeting of chromatin-associated protein complexes has shown significant responses in KMT2A-rearranged (KMT2A-r) acute myeloid leukemia (AML) but resistance frequently develops to single agents. This points to a need for therapeutic combinations that target multiple mechanisms. To enhance our understanding of functional dependencies in KMT2A-r AML, we have used a proteomic approach to identify the catalytic immunoproteasome subunit PSMB8 as a specific vulnerability. Genetic and pharmacologic inactivation of PSMB8 results in impaired proliferation of murine and human leukemic cells while normal hematopoietic cells remain unaffected. Disruption of immunoproteasome function drives an increase in transcription factor BASP1 which in turn represses KMT2A-fusion protein target genes. Pharmacologic targeting of PSMB8 improves efficacy of Menin-inhibitors, synergistically reduces leukemia in human xenografts and shows preserved activity against Menin-inhibitor resistance mutations. This identifies and validates a cell-intrinsic mechanism whereby selective disruption of proteostasis results in altered transcription factor abundance and repression of oncogene-specific transcriptional networks. These data demonstrate that the immunoproteasome is a relevant therapeutic target in AML and that targeting the immunoproteasome in combination with Menin-inhibition could be a novel approach for treatment of KMT2A-r AML.

Cell fate determinant Llgl1 is required for propagation of acute myeloid leukemia

Scribble complex proteins can influence cell fate decisions and self-renewal capacity of hematopoietic cells. While specific cellular functions of Scribble complex members are conserved in mammalian hematopoiesis, they appear to be highly context dependent. Using CRISPR/Cas9-based genetic screening, we have identified Scribble complex-related liabilities in AML including LLGL1. Despite its reported suppressive function in HSC self-renewal, inactivation of LLGL1 in AML confirms its relevant role for proliferative capacity and development of AML. Its function was conserved in human and murine models of AML and across various genetic backgrounds. Inactivation of LLGL1 results in loss of stemness-associated gene-expression including HoxA-genes and induces a GMP-like phenotype in the leukemia stem cell compartment. Re-expression of HoxA9 facilitates functional and phenotypic rescue. Collectively, these data establish LLGL1 as a specific dependency and putative target in AML and emphasizes its cell-type specific functions.

Associations of spleen volume with markers of blood count and lipid profile in a large population-based study

Background

The aim of our study was to investigate associations of spleen volume with blood count markers and lipid profile in the general population.

Materials & methods

Cross-sectional data from 1,106 individuals aged 30-90 years from the population-based Study of Health in Pomerania (SHIP-START-2) were analyzed. Blood count markers included red blood cell (RBC) counts, hemoglobin, platelet count, and white blood cell (WBC) counts. Lipid profile included total-cholesterol, high-density lipoprotein-cholesterol (HDL-C), and low-density lipoprotein-cholesterol (LDL-C) as well as triglycerides. Linear regression models adjusted for age, sex, body height, and weight were used to associate standardized spleen volume with blood counts and lipid profile markers.

Results

Spleen volume was positively associated with RBC (β = 0.05; 95% confidence interval [CI] = 0.03 to 0.08) and hemoglobin (β = 0.05; 95% CI = 0.01 to 0.09) but inversely with platelet count (β = -16.3; 95% CI = -20.5 to -12.1) and WBC (β = -0.25; 95% CI = -0.37 to -0.14). Furthermore, spleen volume showed inverse associations with total cholesterol (β = -0.17; 95% CI = -0.24 to -0.09), HDL-C (β = -0.08; 95% CI = -0.10 to -0.05), and LDL-C (β = -0.12; 95% CI = -0.17 to -0.06). There was no significant association of spleen volume with triglycerides.

Conclusion

Our study showed that the spleen volume is associated with markers of the blood count and lipid profile in the general population.

Pomalidomide combinations are a safe and effective option after daratumumab failure

PURPOSE

Outcomes of multiple myeloma (MM) patients who are refractory to daratumumab are dismal and no standard of treatment exists for this patients' population. Here, we investigate the role of pomalidomide combinations in daratumumab-refractory MM patients.

METHODS

We performed a retrospective analysis of myeloma patients treated at four referral centers (three in Germany and one in Italy). Review chart identified 30 patients with relapsed and refractory myeloma, who progressed during treatment with daratumumab and were treated with pomalidomide-based combinations in the subsequent lines of therapy.

RESULTS

Responses improved from 37% with daratumumab to 53% with pomalidomide. Of seven patients with extramedullary MM (EMM), four achieved a clinical stabilization with pomalidomide, including one patient with a long-lasting complete response. Median progression-free survival and overall survival were 6 and 12 months, respectively. Pomalidomide combinations were well tolerated, no patient discontinued treatment due to adverse events.

CONCLUSION

These data show that pomalidomide-based combinations can be an effective and safe salvage regimen for daratumumab-refractory patients, including those with EMM.

Diagnosis and treatment of MPN in real life: exploratory and retrospective chart review including 960 MPN patients diagnosed with ET or MF in Germany

PURPOSE

The WHO 2016 re-classification of myeloproliferative neoplasms resulted in a separation of essential thrombocythemia (ET) from the pre-fibrotic and fibrotic (overt) phases of primary myelofibrosis (MF). This study reports on a chart review conducted to evaluate the real life approach regarding clinical characteristics, diagnostic assessment, risk stratification and treatment decisions for MPN patients classified as ET or MF after implementation of the WHO 2016 classification.

METHODS

In this retrospective chart review, 31 office-based hematologists/oncologists and primary care centers in Germany participated between April 2021 and May 2022. Physicians reported available data obtained from patient charts via paper-pencil based survey (secondary use of data). Patient features were evaluated using descriptive analysis, also including diagnostic assessment, therapeutic strategies and risk stratification.

RESULTS

Data of 960 MPN patients diagnosed with essential thrombocythemia (ET) (n = 495) or myelofibrosis (MF) (n = 465) after implementation of the revised 2016 WHO classification of myeloid neoplasms was collected from the patient charts. While they met at least one minor WHO-criteria for primary myelofibrosis, 39.8% of those diagnosed with ET did not have histological BM testing at diagnosis. 63.4% of patients who were classified as having MF, however, did not obtain an early prognostic risk assessment. More than 50% of MF patients showed characteristics consistent with the pre-fibrotic phase, which was emphasized by the frequent use of cytoreductive therapy. Hydroxyurea was the most frequently used cytoreductive medication in 84.7% of ET and 53.1% of MF patients. While both ET and MF cohorts showed cardiovascular risk factors in more than 2/3 of the cases, the use of platelet inhibitors or anticoagulants varied between 56.8% in ET and 38.1% in MF patients.

CONCLUSIONS

Improved histopathologic diagnostics, dynamic risk stratification including genetic risk factors for cases of suspected ET and MF are recommended for precise risk assessment and therapeutic stratification according to WHO criteria.

Predictors of Response to Hydroxyurea and Switch to Ruxolitinib in HU-Resistant Polycythaemia VERA Patients: A Real-World PV-NET Study

In polycythemia vera (PV), the prognostic relevance of an ELN-defined complete response (CR) to hydroxyurea (HU), the predictors of response, and patients' triggers for switching to ruxolitinib are uncertain. In a real-world analysis, we evaluated the predictors of response, their impact on the clinical outcomes of CR to HU, and the correlations between partial or no response (PR/NR) and a patient switching to ruxolitinib. Among 563 PV patients receiving HU for ≥12 months, 166 (29.5%) achieved CR, 264 achieved PR, and 133 achieved NR. In a multivariate analysis, the absence of splenomegaly (p = 0.03), pruritus (p = 0.002), and a median HU dose of ≥1 g/day (p < 0.001) remained associated with CR. Adverse events were more frequent with a median HU dose of ≥1 g/day. Overall, 283 PR/NR patients (71.3%) continued HU, and 114 switched to ruxolitinib. In the 449 patients receiving only HU, rates of thrombosis, hemorrhages, progression, and overall survival were comparable among the CR, PR, and NR groups. Many PV patients received underdosed HU, leading to lower CR and toxicity rates. In addition, many patients continued HU despite a PR/NR; however, splenomegaly and other symptoms were the main drivers of an early switch. Better HU management, standardization of the criteria for and timing of responses to HU, and adequate intervention in poor responders should be advised.

Identifying Patients with Polycythemia Vera at Risk of Thrombosis after Hydroxyurea Initiation: The Polycythemia Vera-Advanced Integrated Models (PV-AIM) Project

Patients with polycythemia vera (PV) are at significant risk of thromboembolic events (TE). The PV-AIM study used the Optum® de-identified Electronic Health Record dataset and machine learning to identify markers of TE in a real-world population. Data for 82,960 patients with PV were extracted: 3852 patients were treated with hydroxyurea (HU) only, while 130 patients were treated with HU and then changed to ruxolitinib (HU-ruxolitinib). For HU-alone patients, the annualized incidence rates (IR; per 100 patients) decreased from 8.7 (before HU) to 5.6 (during HU) but increased markedly to 10.5 (continuing HU). Whereas for HU-ruxolitinib patients, the IR decreased from 10.8 (before HU) to 8.4 (during HU) and was maintained at 8.3 (after switching to ruxolitinib). To better understand markers associated with TE risk, we built a machine-learning model for HU-alone patients and validated it using an independent dataset. The model identified lymphocyte percentage (LYP), neutrophil percentage (NEP), and red cell distribution width (RDW) as key markers of TE risk, and optimal thresholds for these markers were established, from which a decision tree was derived. Using these widely used laboratory markers, the decision tree could be used to identify patients at high risk for TE, facilitate treatment decisions, and optimize patient management.

Molecular-defined clonal evolution in patients with classical myeloproliferative neoplasms

Classical myeloproliferative neoplasms (MPNs) are characterized by distinct clinical phenotypes. The discovery of driver mutations in JAK2, CALR and MPL genes provided new insights into their pathogenesis. Next-generation sequencing (NGS) identified additional somatic mutations, most frequently in epigenetic modulator genes. In this study, a cohort of 95 MPN patients was genetically characterized using targeted NGS. Clonal hierarchies of detected mutations were subsequently analysed using colony forming progenitor assays derived from single cells to study mutation acquisition. Further, the hierarchy of mutations within distinct cell lineages was evaluated. NGS revealed mutations in three epigenetic modulator genes (TET2, DNMT3A, ASXL1) as most common co-mutations to the classical driver mutations. JAK2^V617F as well as DNMT3A and TET2 mutations were detected as primary events in disease formation and most cases presented with a linear mutation pattern. Mutations appear mostly in the myeloid lineages but can also appear in lymphoid subpopulations. In one case with a double mutant MPL gene, mutations exclusively appeared in the monocyte lineage. Overall, this study confirms the mutational heterogeneity of classical MPNs and highlights the role of JAK2^V617F and epigenetic modifier genes as early events in hematologic disease formation.

Antiseptic efficacy of two mouth rinses in the oral cavity to identify a suitable rinsing solution in radiation- or chemotherapy induced mucositis

OBJECTIVES

Oral mucositis caused by intensive cancer chemotherapy or radiotherapy frequently results in pronounced damage of the oral mucosa leading to painful oral hygiene. To support oral care, antimicrobial effective mouth rinses may be used. Thus, the efficacy of a hypochlorite-based mouth rinse (Granudacyn®), assumed to be highly biocompatible because of the compounds being part of the natural pathogen defense, as possible antiseptic agent in case of oral mucositis was compared to that of an octenidine based antiseptic mouth rinse (Octenidol® md).

MATERIALS AND METHODS

The study was conducted as monocentric, controlled, randomized, blind cross over comparative study on 20 volunteers. As a proof of principle, we performed the study on orally healthy subjects and not cancer patients. The efficacy was determined as reduction of colony forming units (cfu) on buccal mucosa as well as in saliva. After mouth rinsing for 30 s, samples were taken after 1 min, 15 min, 30 and 60 min. The lg-reduction was calculated as difference between lg-values of cfu pre- and post-treatment.

RESULTS

Both antiseptic mouth rinses induced a significant reduction of cfu on buccal mucosa and in saliva 1 min after mouth rinsing. The effect persisted up to 60 min. The octenidine based rinse was significantly superior to the hypochlorite-based rinse up to the last sample 60 min after rinsing. However, the known cytotoxicity of octenidine argues against its application.

CONCLUSION

Within the limits of this study, due to its antiseptic efficacy, the hypochlorite-based rinse Granudacyn® can be regarded appropriate to support the oral hygiene in patients with a sensitive oral mucosa during an aggressive cancer chemotherapy and radiation treatment in case of oral mucositis.

Ruxolitinib in cytopenic myelofibrosis: Response, toxicity, drug discontinuation, and outcome

BACKGROUND

Patients with cytopenic myelofibrosis (MF) have more limited therapeutic options and poorer prognoses compared with patients with the myeloproliferative phenotype.

AIMS AND METHODS

Prognostic correlates of cytopenic phenotype were explored in 886 ruxolitinib-treated patients with primary/secondary MF (PMF/SMF) included in the RUX-MF retrospective study. Cytopenia was defined as: leukocyte count <4 × 10⁹ /L and/or hemoglobin <11/<10 g/dL (males/females) and/or platelets <100 × 10⁹ /L.

RESULTS

Overall, 407 (45.9%) patients had a cytopenic MF, including 249 (52.4%) with PMF. In multivariable analysis, high molecular risk mutations (p = .04), intermediate 2/high Dynamic International Prognostic Score System (p < .001) and intermediate 2/high Myelofibrosis Secondary to Polycythemia Vera and Essential Thrombocythemia Prognostic Model (p < .001) remained associated with cytopenic MF in the overall cohort, PMF, and SMF, respectively. Patients with cytopenia received lower average ruxolitinib at the starting (25.2 mg/day vs. 30.2 mg/day, p < .001) and overall doses (23.6 mg/day vs. 26.8 mg/day, p < .001) and achieved lower rates of spleen (26.5% vs. 34.1%, p = .04) and symptom (59.8% vs. 68.8%, p = .008) responses at 6 months compared with patients with the proliferative phenotype. Patients with cytopenia also had higher rates of thrombocytopenia at 3 months (31.1% vs. 18.8%, p < .001) but lower rates of anemia (65.6% vs. 57.7%, p = .02 at 3 months and 56.6% vs. 23.9% at 6 months, p < .001). After competing risk analysis, the cumulative incidence of ruxolitinib discontinuation at 5 years was 57% and 38% in patients with cytopenia and the proliferative phenotype (p < .001), whereas cumulative incidence of leukemic transformation was similar (p = .06). In Cox regression analysis adjusted for Dynamic International Prognostic Score System score, survival was significantly shorter in patients with cytopenia (p < .001).

CONCLUSIONS

Cytopenic MF has a lower probability of therapeutic success with ruxolitinib as monotherapy and worse outcome. These patients should be considered for alternative therapeutic strategies.

Dynamic DNA methylation reveals novel cis-regulatory elements in mouse hematopoiesis

Differentiation of hematopoietic stem and progenitor cells to terminally differentiated immune cells is accompanied by large-scale remodeling of the DNA methylation landscape. Although significant insights into the molecular mechanisms of hematopoietic tissue regeneration were derived from mouse models, profiling of DNA methylation has been hampered by high cost or low resolution using available methods. The recent development of the Infinium Mouse Methylation BeadChip (MMBC) array facilitates methylation profiling of the mouse genome at a single CpG resolution at affordable cost. We extended the RnBeads package to provide a computational framework for the analysis of MMBC data. This framework was applied to a newly generated reference map of mouse hematopoiesis encompassing nine different cell types. Analysis of dynamically regulated CpG sites showed progressive and unidirectional DNA methylation changes from hematopoietic stem and progenitor cells to differentiated hematopoietic cells and allowed the identification of lineage- and cell type-specific DNA methylation programs. Comparison with previously published catalogs of cis-regulatory elements (CREs) revealed 12,856 novel putative CREs that were dynamically regulated by DNA methylation (mdCREs). These mdCREs were predominantly associated with patterns of cell type-specific DNA hypomethylation and could be identified as epigenetic control regions regulating the expression of key hematopoietic genes during differentiation. In summary, we established an analysis pipeline for MMBC data sets and provide a DNA methylation atlas of mouse hematopoiesis. This resource allowed us to identify novel putative CREs involved in hematopoiesis and will serve as a platform to study epigenetic regulation of normal and malignant hematopoiesis.

Comparison of inpatient and outpatient palliative sedation practice - A prospective observational study

INTRODUCTION

Palliative sedation (PS) is an intrusive measure to relieve patients at the end of their life from otherwise untreatable symptoms. Intensive discussion of the advantages and limitations of palliative care with the patients and their relatives should precede the initiation of PS since PS is terminated by the patient's death in most cases. Drugs for PS are usually administered intravenously. Midazolam is widely used, either alone or in combination with other substances. PS can be conducted in both inpatient and outpatient settings; however, a quality analysis comparing both modalities was missing so far.

PATIENTS AND METHODS

This prospective observational study collected data from patients undergoing PS inpatient at the palliative care unit (PCU, n = 26) or outpatient at a hospice (n = 2) or at home (specialized outpatient palliative care [SAPV], n = 31) between July 2017 and June 2018. Demographical data, indications for PS, and drug protocols were analyzed. The depth of sedation according to the Richmond Agitation Sedation Scale (RASS) and the degree of satisfaction of staff members and patient's relatives were included as parameters for quality assessment.

RESULTS

Patients undergoing PS at the PCU were slightly younger compared to outpatients (hospice and SAPV combined). Most patients suffered from malignant diseases, and midazolam was the backbone of sedation for inpatients and outpatients. The median depth of sedation was between +1 and -3 according to the RASS with a trend to deeper sedation prior to death. The median degree of satisfaction was "good," scored by staff members and by patient's relatives. Significant differences between inpatients and outpatients were not seen in protocols, depth of sedation, and degree of satisfaction.

CONCLUSION

The data support the thesis that PS is possible for inpatients and outpatients with comparable results. For choosing the best place for PS, other aspects such as patient's and relative's wishes, stress, and medical reasons should be considered.

Taz protects hematopoietic stem cells from an aging-dependent decrease in PU.1 activity

Specific functions of the immune system are essential to protect us from infections caused by pathogens such as viruses and bacteria. However, as we age, the immune system shows a functional decline that can be attributed in large part to age-associated defects in hematopoietic stem cells (HSCs)—the cells at the apex of the immune cell hierarchy. Here, we find that the Hippo pathway coactivator TAZ is potently induced in old HSCs and protects these cells from functional decline. We identify Clca3a1 as a TAZ-induced gene that allows us to trace TAZ activity in vivo. Using CLCA3A1 as a marker, we can isolate “young-like” HSCs from old mice. Mechanistically, Taz acts as coactivator of PU.1 and to some extent counteracts the gradual loss of PU.1 expression during HSC aging. Our work thus uncovers an essential role for Taz in a previously undescribed fail-safe mechanism in aging HSCs.

Immune system function declines with age, a consequence of defects in hematopoietic stem cells (HSCs). Here the authors show that TAZ buffers age-related loss of PU.1 activity to maintain HSC functionality and identify the surface protein Clca3a1 as a marker of “young-like” HSCs, even in old mice.

Real-world clinical outcomes of patients with myelofibrosis treated with ruxolitinib: a medical record review

Aim: To assess real-world ruxolitinib treatment patterns and outcomes in patients diagnosed with primary or secondary myelofibrosis. Materials & methods: Patient medical records were reviewed in six countries. Results: Eligible patients (n = 469) had a mean age of 63.5 years, and most were male (66.5%) with primary myelofibrosis (78.5%). Median duration of ruxolitinib treatment was 13.1 months; 40% of patients initiated treatment at the recommended dose. The Kaplan-Meier estimate of median survival from ruxolitinib initiation was 44.4 months (95% CI, 38.8-50.2 months). Approximately one quarter (23%) of patients continued ruxolitinib after progression. Conclusion: These results suggest an unmet need for more effective treatments for patients with myelofibrosis who failed ruxolitinib.

Peripheral blasts are associated with responses to ruxolitinib and outcomes in patients with chronic-phase myelofibrosis

Background

The presence of peripheral blasts (PB) is a negative prognostic factor in patients with primary and secondary myelofibrosis (MF) and PB ≥4% was associated with a particularly unfavorable prognosis. Ruxolitinib (RUX) is the JAK1/2 inhibitor most used for treatment of MF‐related splenomegaly and symptoms. Its role has not been assessed in correlation with PB.

Methods

In 794 chronic‐phase MF patients treated with RUX, we evaluated the impact of baseline percentage of PB on response (spleen and symptoms responses) and outcome (RUX discontinuation‐free, leukemia‐free, and overall survival). Three subgroups were compared: PB‐0 (no PB, 61.3%), PB‐4 (PB 1%‐4%, 33.5%), and PB‐9 (PB 5%‐9%, 5.2%).

Results

At 3 and 6 months, spleen responses were less frequently achieved by PB‐4 (P = .001) and PB‐9 (P = .004) compared to PB‐0 patients. RUX discontinuation‐free, leukemia‐free, and overall survival were also worse for PB‐4 and PB‐9 patients (P = .001, P = .002, and P < .001, respectively).

Conclusions

Personalized approaches beyond RUX monotherapy may be useful in PB‐4 and particularly in PB‐9 patients.

In 794 chronic‐phase myelofibrosis patients treated with ruxolitinib, the impact of the baseline percentage of peripheral blasts (PB) on response and outcome was evaluated. Three subgroups were compared: PB‐0 (no PB, 61.3%), PB‐4 (PB 1%‐4%, 33.5%), and PB‐9 (PB 5%‐9%, 5.2%). At 3 and 6 months, spleen responses were less frequently achieved by PB‐4 (P = .001) and PB‐9 (P = .004) compared to PB‐0 patients; ruxolitinib discontinuation‐free, leukemia‐free, and overall survival were also worse for PB‐4 and PB‐9 patients (P = .001, P = .002, and P < .001, respectively).

Context-specific effects of NOX4 inactivation in acute myeloid leukemia (AML)

PURPOSE

Oxidative stress has been linked to initiation and progression of cancer and recent studies have indicated a potential translational role regarding modulation of ROS in various cancers, including acute myeloid leukemia (AML). Detailed understanding of the complex machinery regulating ROS including its producer elements in cancer is required to define potential translational therapeutic use. Based on previous studies in acute myeloid leukemia (AML) models, we considered NADPH oxidase (NOX) family members, specifically NOX4 as a potential target in AML.

METHODS

Pharmacologic inhibition and genetic inactivation of NOX4 in murine and human models of AML were used to understand its functional role. For genetic inactivation, CRISPR-Cas9 technology was used in human AML cell lines in vitro and genetically engineered knockout mice for Nox4 were used for deletion of Nox4 in hematopoietic cells via Mx1-Cre recombinase activation.

RESULTS

Pharmacologic NOX inhibitors and CRISPR-Cas9-mediated inactivation of NOX4 and p22-phox (an essential NOX component) decreased proliferative capacity and cell competition in FLT3-ITD-positive human AML cells. In contrast, conditional deletion of Nox4 enhanced the myeloproliferative phenotype of an FLT3-ITD induced knock-in mouse model. Finally, Nox4 inactivation in normal hematopoietic stem and progenitor cells (HSPCs) caused a minor reduction in HSC numbers and reconstitution capacity.

CONCLUSION

The role of NOX4 in myeloid malignancies appears highly context-dependent and its inactivation results in either enhancing or inhibitory effects. Therefore, targeting NOX4 in FLT3-ITD positive myeloid malignancies requires additional pre-clinical assessment.

Combined Activity of the Redox-Modulating Compound Setanaxib (GKT137831) with Cytotoxic Agents in the Killing of Acute Myeloid Leukemia Cells

Acute myeloid leukemia (AML) cells harbor elevated levels of reactive oxygen species (ROS), which promote cell proliferation and cause oxidative stress. Therefore, the inhibition of ROS formation or elevation beyond a toxic level have been considered as therapeutic strategies. ROS elevation has recently been linked to enhanced NADPH oxidase 4 (NOX4) activity. Therefore, the compound Setanaxib (GKT137831), a clinically advanced ROS-modulating substance, which has initially been identified as a NOX1/4 inhibitor, was tested for its inhibitory activity on AML cells. Setanaxib showed antiproliferative activity as single compound, and strongly enhanced the cytotoxic action of anthracyclines such as daunorubicin in vitro. Setanaxib attenuated disease in a mouse model of FLT3-ITD driven myeloproliferation in vivo. Setanaxib did not significantly inhibit FLT3-ITD signaling, including FLT3 autophosphorylation, activation of STAT5, AKT, or extracellular signal regulated kinase 1 and 2 (ERK1/2). Surprisingly, the effects of Setanaxib on cell proliferation appeared to be independent of the presence of NOX4 and were not associated with ROS quenching. Instead, Setanaxib caused elevation of ROS levels in the AML cells and importantly, enhanced anthracycline-induced ROS formation, which may contribute to the combined effects. Further assessment of Setanaxib as potential enhancer of cytotoxic AML therapy appears warranted.

PLCG1 is required for AML1-ETO leukemia stem cell self-renewal

In an effort to identify novel drugs targeting fusion-oncogene-induced acute myeloid leukemia (AML), we performed high-resolution proteomic analysis. In AML1-ETO (AE)-driven AML, we uncovered a deregulation of phospholipase C (PLC) signaling. We identified PLCgamma 1 (PLCG1) as a specific target of the AE fusion protein that is induced after AE binding to intergenic regulatory DNA elements. Genetic inactivation of PLCG1 in murine and human AML inhibited AML1-ETO dependent self-renewal programs, leukemic proliferation, and leukemia maintenance in vivo. In contrast, PLCG1 was dispensable for normal hematopoietic stem and progenitor cell function. These findings are extended to and confirmed by pharmacologic perturbation of Ca++-signaling in AML1-ETO AML cells, indicating that the PLCG1 pathway poses an important therapeutic target for AML1-ETO+ leukemic stem cells.

Cytoreductive treatment in real life: a chart review analysis on 1440 patients with polycythemia vera

Purpose

Patients with polycythemia vera (PV) show an elevated incidence of thromboembolic complications and decreased survival when compared to age-matched healthy individuals. Hypercellularity as indicated by elevated hematocrit, pathophysiological changes induced by the JAK2 driver mutation and cardiovascular risk factors contribute to the increased incidence of thromboembolic events. Higher age and a history of thromboembolic events define a high-risk population of PV patients. Depending on the individual risk profile, phlebotomy or pharmacologic cytoreduction is recommended in combination with low-dose acetylsalicylic acid. Stringent cytoreduction is required for effective risk reduction. However, in recent reports, the rate of thromboembolic complications in PV patients under cytoreductive therapy appears still elevated compared to healthy individuals. This study reports on a chart review to assess for cytoreductive therapy of 1440 PV patients in real life.

Methods

Forty-two eligible hematologists/oncologists in private practice treating patients with MPN were recruited to participate in a paper–pencil-based survey conducted between January 2019 and March 2020 in Germany. Physicians were asked to report primary documented data obtained from patient charts. Descriptive analyses were conducted to assess for patient characteristics, treatment modalities, risk factors and thromboembolic complications.

Results

Data were collected from the patient charts of 1440 individuals diagnosed with PV. The patient population was older than those reported in multicenter trials with a median age of 72.2 years at the time of reporting and 63.5 years at diagnosis. Age was the main factor accounting for high-risk status with 84.7% of patients being above the age of 60 followed by thromboembolic complications reported in 21.3% of patients. The use of pharmacologic cytoreduction was highly variable between participating centers with an average of 60.7% and a range of 10.1–100%. Hydroxyurea was the most frequently used drug followed by ruxolitinib, while interferons were reported for a minority of patients. For 35.4% of patients a persistent need for phlebotomy in addition to cytoreductive treatment was reported. Although presence of high-risk criteria and insufficient disease control were reported as main triggers to initiate pharmacologic cytoreduction, 28.1% had elevated hematocrit values (> 45%) and 38.6% showed persistence of elevated leukocyte count (> 10^9/l) while on cytoreductive treatment. In contrast, physician-reported symptom burden was lower than published in clinical trials and patient-reported outcomes. The rate of patients experiencing thromboembolic complications was 32.2% at any time and 14.3% after diagnosis with most patients receiving acetylsalicylic acid and 10.8% remaining on oral anticoagulants or heparin.

Conclusions

Cytoreductive treatment of high-risk PV in real life is highly variable regarding indication for cytoreduction and definition of therapy resistance. This study highlights the need for (i) improved risk stratification for thromboembolic events, (ii) consequent indication of pharmacologic cytoreduction in high-risk PV and (iii) attention to signs of therapy resistance that can trigger an earlier and stringent switch to second line agents.

Kidney Dysfunction Is Associated with Thrombosis and Disease Severity in Myeloproliferative Neoplasms: Implications from the German Study Group for MPN Bioregistry

Simple Summary

In patients with myeloproliferative neoplasms (MPN) and in patients with kidney dysfunction, a higher rate of thrombosis has been reported compared with the general population. Furthermore, MPN patients are more prone to develop kidney dysfunction. In our study, we assessed the importance of specific risk factors for kidney dysfunction and thrombosis in MPN patients. We found that the rate of thrombosis is correlated with the degree of kidney dysfunction, especially in myelofibrosis. Significant associations for kidney dysfunction included arterial hypertension, MPN treatment, and increased inflammation, and those for thrombosis comprised arterial hypertension, non-excessive platelet counts, and antithrombotic therapy. The identified risk factor associations varied between MPN subtypes. Our data suggest that kidney dysfunction in MPN patients is associated with an increased risk of thrombosis, mandating closer monitoring, and, possibly, early thromboprophylaxis.

Abstract

Inflammation-induced thrombosis represents a severe complication in patients with myeloproliferative neoplasms (MPN) and in those with kidney dysfunction. Overlapping disease-specific attributes suggest common mechanisms involved in MPN pathogenesis, kidney dysfunction, and thrombosis. Data from 1420 patients with essential thrombocythemia (ET, 33.7%), polycythemia vera (PV, 38.5%), and myelofibrosis (MF, 27.9%) were extracted from the bioregistry of the German Study Group for MPN. The total cohort was subdivided according to the calculated estimated glomerular filtration rate (eGFR, (mL/min/1.73 m²)) into eGFR1 (≥90, 21%), eGFR2 (60–89, 56%), and eGFR3 (<60, 22%). A total of 29% of the patients had a history of thrombosis. A higher rate of thrombosis and longer MPN duration was observed in eGFR3 than in eGFR2 and eGFR1. Kidney dysfunction occurred earlier in ET than in PV or MF. Multiple logistic regression analysis identified arterial hypertension, MPN treatment, increased uric acid, and lactate dehydrogenase levels as risk factors for kidney dysfunction in MPN patients. Risk factors for thrombosis included arterial hypertension, non-excessive platelet counts, and antithrombotic therapy. The risk factors for kidney dysfunction and thrombosis varied between MPN subtypes. Physicians should be aware of the increased risk for kidney disease in MPN patients, which warrants closer monitoring and, possibly, early thromboprophylaxis.

Recurrent Upper Gastrointestinal Bleeding from Isolated Gastric Varices as Primary Symptom of Myelofibrosis: A Case Report on Combining Interventional and Pharmacologic Treatment Options

Portal hypertension leads to pronounced venous collateralization and development of varices. Besides manifest liver cirrhosis, primarily left-sided portal hypertension is causal for the development of gastric varices. We present a case of a 36-year-old female patient with splenomegaly, underlying primary myelofibrosis, and detection of somatic Janus-kinase-2 driver-mutation JAK2V617F. Following first upper gastrointestinal bleeding, isolated gastric varices could be detected as a result of underlying left-sided portal hypertension. Within a few months, repeated life-threatening bleedings with transfusion requirements and frequent hospitalizations occurred. Despite multiple injections of cyanoacrylates, the proven therapy of choice, varices could not be stabilized. Combination of targeted JAK-inhibitor therapy in conjunction with the use of EUS-guided application of coils with subsequent cyanoacrylate injection resulted in acute and long-term bleeding control.

The Role of MacroH2A Histone Variants in Cancer

Simple Summary

The structural unit of chromatin is the nucleosome that is composed of DNA wrapped around a core of eight histone proteins. Histone variants can replace ‘standard’ histones at specific sites of the genome. Thus, histone variants modulate all functions in the context of chromatin, such as gene expression. Here, we provide a concise review on a group of histone variants termed macroH2A. They contain two additional domains that contribute to their increased size. We discuss how these domains mediate molecular functions in normal cells and the role of macroH2As in gene expression and cancer.

Abstract

The epigenome regulates gene expression and provides a molecular memory of cellular events. A growing body of evidence has highlighted the importance of epigenetic regulation in physiological tissue homeostasis and malignant transformation. Among epigenetic mechanisms, the replacement of replication-coupled histones with histone variants is the least understood. Due to differences in protein sequence and genomic distribution, histone variants contribute to the plasticity of the epigenome. Here, we focus on the family of macroH2A histone variants that are particular in having a tripartite structure consisting of a histone fold, an intrinsically disordered linker and a globular macrodomain. We discuss how these domains mediate different molecular functions related to chromatin architecture, transcription and DNA repair. Dysregulated expression of macroH2A histone variants has been observed in different subtypes of cancer and has variable prognostic impact, depending on cellular context and molecular background. We aim to provide a concise review regarding the context- and isoform-dependent contributions of macroH2A histone variants to cancer development and progression.

Ruxolitinib rechallenge in resistant or intolerant patients with myelofibrosis: Frequency, therapeutic effects, and impact on outcome

BACKGROUND

After ruxolitinib discontinuation, the outcome of patients with myelofibrosis (MF) is poor with scarce therapeutic possibilities.

METHODS

The authors performed a subanalysis of an observational, retrospective study (RUX-MF) that included 703 MF patients treated with ruxolitinib to investigate 1) the frequency and reasons for ruxolitinib rechallenge, 2) its therapeutic effects, and 3) its impact on overall survival.

RESULTS

A total of 219 patients (31.2%) discontinued ruxolitinib for ≥14 days and survived for ≥30 days. In 60 patients (27.4%), ruxolitinib was rechallenged for ≥14 days (RUX-again patients), whereas 159 patients (72.6%) discontinued it permanently (RUX-stop patients). The baseline characteristics of the 2 cohorts were comparable, but discontinuation due to a lack/loss of spleen response was lower in RUX-again patients (P = .004). In comparison with the disease status at the first ruxolitinib stop, at its restart, there was a significant increase in patients with large splenomegaly (P < .001) and a high Total Symptom Score (TSS; P < .001). During the rechallenge, 44.6% and 48.3% of the patients had spleen and symptom improvements, respectively, with a significant increase in the number of patients with a TSS reduction (P = .01). Although the use of a ruxolitinib dose > 10 mg twice daily predicted better spleen (P = .05) and symptom improvements (P = .02), the reasons for/duration of ruxolitinib discontinuation and the use of other therapies before rechallenge were not associated with rechallenge efficacy. At 1 and 2 years, 33.3% and 48.3% of RUX-again patients, respectively, had permanently discontinued ruxolitinib. The median overall survival was 27.9 months, and it was significantly longer for RUX-again patients (P = .004).

CONCLUSIONS

Ruxolitinib rechallenge was mainly used in intolerant patients; there were clinical improvements and a possible survival advantage in many cases, but there was a substantial rate of permanent discontinuation. Ruxolitinib rechallenge should be balanced against newer therapeutic possibilities.

Impact of comorbidities and body mass index on the outcome of polycythemia vera patients

In 816 patients with 2016 World Health Organization-defined polycythemia vera (PV) enrolled in a multicenter retrospective study, we investigated the predictive value of Charlson comorbidity index (CCI) and body mass index (BMI) on thrombosis, progression to post-PV myelofibrosis (PPV-MF) and survival. Patients were subgrouped according to CCI = 0 (58.1%, no comorbidities) or CCI ≥ 1 (41.9%) and according to normal/underweight (BMI < 25, 54.5%) or overweight/obesity (BMI ≥ 25, 45.5%) at PV diagnosis. BMI was available for 529 patients. Patients with CCI ≥ 1 were older and more frequently presented cardiovascular risk factors compared to patients with CCI = 0 (p < 0.001), while overweight/obese patients were more frequently males (p < 0.001). Cumulative incidence of thromboses with death as competing risk was 13.3% at 10 years. Multivariable analysis with death as competing risk showed that previous thromboses (subdistribution hazard ratio [SHR]: 2.1, p = 0.01) and hypertension (SHR: 1.77, p = 0.04) were significantly associated with a higher thrombotic risk, while BMI ≥ 25 lost statistical significance (SHR: 1.69, p = 0.05) and CCI ≥ 1 was excluded after evaluation of goodness of fit. After a median follow-up of 6.1 years, progression to PPV-MF occurred in 44 patients, and 75 patients died. BMI ≥ 25 was associated with a lower probability of progression to PPV-MF (SHR: 0.38, CI95%: 0.15-0.94, p = 0.04) and better survival (hazard ratio [HR]: 0.42, CI95%: 0.18-0.97, p = 0.04). CCI ≥ 1 did not affect progression to PPV-MF (p = 0.44) or survival (p = 0.71).  The evaluation of CCI and BMI may improve the prognostic definition of PV. In patients with hypertension an accurate evaluation of thrombotic risk is warranted.

A JAK of all trades: how global phosphoproteomics reveal the Achilles heel of MPNs

While Janus-kinase (JAK)-inhibitors effectively reduce the inflammatory phenotype of myeloproliferative neoplasms (MPN), they do not affect disease burden or presence of the mutated clone to a major extent. Here, we show how Janus-kinase 2 (JAK2)-mutated cells persist through maintenance of the mitogen-activated protein kinase Interacting Serine/Threonine Kinase 1 (MKNK1) – Extracellular Signal-regulated Kinase (ERK)-axis by hijacking the splicing machinery through post-translational modifications.

Splicing factor YBX1 mediates persistence of JAK2-mutated neoplasms

Janus kinases (JAKs) mediate responses to cytokines, hormones and growth factors in haematopoietic cells^1,2. The JAK gene JAK2 is frequently mutated in the ageing haematopoietic system^3,4 and in haematopoietic cancers⁵. JAK2 mutations constitutively activate downstream signalling and are drivers of myeloproliferative neoplasm (MPN). In clinical use, JAK inhibitors have mixed effects on the overall disease burden of JAK2-mutated clones^6,7, prompting us to investigate the mechanism underlying disease persistence. Here, by in-depth phosphoproteome profiling, we identify proteins involved in mRNA processing as targets of mutant JAK2. We found that inactivation of YBX1, a post-translationally modified target of JAK2, sensitizes cells that persist despite treatment with JAK inhibitors to apoptosis and results in RNA mis-splicing, enrichment for retained introns and disruption of the transcriptional control of extracellular signal-regulated kinase (ERK) signalling. In combination with pharmacological JAK inhibition, YBX1 inactivation induces apoptosis in JAK2-dependent mouse and primary human cells, causing regression of the malignant clones in vivo, and inducing molecular remission. This identifies and validates a cell-intrinsic mechanism whereby differential protein phosphorylation causes splicing-dependent alterations of JAK2-ERK signalling and the maintenance of JAK2^V617F malignant clones. Therapeutic targeting of YBX1-dependent ERK signalling in combination with JAK2 inhibition could thus eradicate cells harbouring mutations in JAK2.

Second primary malignancy in myelofibrosis patients treated with ruxolitinib

Ruxolitinib (RUX), the first JAK1/JAK2 inhibitor approved for myelofibrosis (MF) therapy, has recently been associated with the occurrence of second primary malignancies (SPMs), mainly lymphomas and non-melanoma skin cancers (NMSCs). We analyzed the incidence, risk factors and outcome of SPMs in 700 MF patients treated with RUX in a real-world context. Median follow-up from starting RUX was 2·9 years. Overall, 80 (11·4%) patients developed 87 SPMs after RUX start. NMSCs were the most common SPMs (50·6% of the cases). Multivariate analysis demonstrated that male sex [hazard ratio (HR): 2·37, 95% confidence interval (95%CI): 1·22-4·60, P = 0·01] and thrombocytosis> 400 × 10⁹ /l at RUX start (HR:1·98, 95%CI: 1·10-4·60, P = 0·02) were associated with increased risk for SPMs. Risk factors for NMSC alone were male sex (HR: 3·14, 95%CI: 1·24-7·92, P = 0·02) and duration of hydroxycarbamide and RUX therapy > 5 years (HR: 3·20, 95%CI: 1·17-8·75, P = 0·02 and HR: 2·93, 95%CI: 1·39-6·17, P = 0·005 respectively). In SPMs excluding NMSCs, male sex (HR: 2·41, 95%CI: 1·11-5·25, P = 0·03), platelet > 400 × 10⁹ /l (HR: 3·30, 95%CI: 1·67-6·50, P = 0·001) and previous arterial thromboses (HR: 3·47, 95%CI: 1·48-8·14, P = 0·004) were shown to be associated with higher risk of SPMs. While it is reassuring that no aggressive lymphoma was documented, active skin surveillance is recommended in all patients and particularly after prolonged hydroxycaramide therapy; oncological screening should be triggered by thrombocytosis and arterial thrombosis, particularly in males.

Activating JAK-mutations confer resistance to FLT3 kinase inhibitors in FLT3-ITD positive AML in vitro and in vivo

An important limitation of FLT3 tyrosine kinase inhibitors (TKIs) in FLT3-ITD positive AML is the development of resistance. To better understand resistance to FLT3 inhibition, we examined FLT3-ITD positive cell lines which had acquired resistance to midostaurin or sorafenib. In 6 out of 23 TKI resistant cell lines we were able to detect a JAK1 V658F mutation, a mutation that led to reactivation of the CSF2RB-STAT5 pathway. Knockdown of JAK1, or treatment with a JAK inhibitor, resensitized cells to FLT3 inhibition. Out of 136 patients with FLT3-ITD mutated AML and exposed to FLT3 inhibitor, we found seven different JAK family mutations in six of the cases (4.4%), including five bona fide, activating mutations. Except for one patient, the JAK mutations occurred de novo (n = 4) or displayed increasing variant allele frequency after exposure to FLT3 TKI (n = 1). In vitro each of the five activating variants were found to induce resistance to FLT3-ITD inhibition, which was then overcome by dual FLT3/JAK inhibition. In conclusion, our data characterize a novel mechanism of resistance to FLT3-ITD inhibition and may offer a potential therapy, using dual JAK and FLT3 inhibition.

Interferon alpha for essential thrombocythemia during 34 high-risk pregnancies: outcome and safety

PURPOSE

Pregnancies in women with essential thrombocythemia (ET) are at a higher risk for obstetrical complications. Acetylsalicylic acid (ASA) and low-molecular weight heparin (LMWH) are common options to prevent miscarriages and maternal complications, whereas interferon alpha (IFN) seems to be the cytoreductive therapy of choice. This retrospective study analyzes the largest number of IFN pregnancies to date in terms of outcome and safety.

METHODS

Data of 34 high-risk pregnancies in 23 women presenting at the University hospitals of Minden and Jena from 01-Jun-2007 to 01-Jun-2020 were collected. Reasons defining high-risk ET pregnancy in all 23 patients were: Thrombosis (n = 9) or severe hemorrhage (n = 2) in history, platelet count ≥ 1500 × 10³/µl (n = 8) or severe microcirculatory disturbances not completely responding to ASA (n = 4).

RESULTS

Without the use of IFN, live birth rate was 60% (6/10), however, after the use of IFN live birth rate increased to 73.5% (25/34 pregnancies). Nine pregnancies ended in miscarriages (9/34; 26.5%); all of them spontaneous abortions. Live birth rate significantly improved with ASA (90% versus 50%, p = 0.0168), however, if ASA and LMWH was added (n = 14), live birth rate was 100%. IFN compound (PEGylated versus standard IFN) and JAK2-driver mutation had no impact on pregnancy outcome. One major maternal complication occurred as a major peripartal bleeding after abortion curettage.

CONCLUSION

IFN was associated with an encouraging live birth rate of 73.5% with no fatal maternal events and manageable side effects.

PLCγ1 suppression promotes the adaptation of KRAS-mutant lung adenocarcinomas to hypoxia

Mutant KRAS modulates the metabolic plasticity of cancer cells conferring growth advantage during hypoxia, but the molecular underpinnings are largely unknown. Using a lipidomic screen, we found that PLCγ1 is suppressed during hypoxia in KRAS-mutant human lung adenocarcinoma cancer cell lines. Suppression of PLCγ1 in hypoxia promotes a less oxidative cancer cell metabolism, reduces the formation of mitochondrial reactive oxygen species and switches tumor bioenergetics towards glycolysis by impairing Ca²⁺ entry into the mitochondria. This event prevents lipid peroxidation, antagonizes apoptosis and increases cancer cell proliferation. Accordingly, loss-of-function of Plcγ1 in a mouse model of Kras^G12D-driven lung adenocarcinoma increased the expression of glycolytic genes, boosted tumor growth and reduced survival. In patients with mutant KRAS lung adenocarcinomas, low PLCγ1 expression correlates with increased expression of hypoxia markers and predicts poor patient survival. Thus, our work reveals a mechanism of cancer cell adaptation to hypoxia with potential therapeutic value.

Fibrosis and Immune Cell Infiltration Are Separate Events Regulated by Cell-Specific Receptor Notch3 Expression

BACKGROUND

Kidney injuries that result in chronic inflammation initiate crosstalk between stressed resident cells and infiltrating immune cells. In animal models, whole-body receptor Notch3 deficiency protects from leukocyte infiltration and organ fibrosis. However, the relative contribution of Notch3 expression in tissue versus infiltrating immune cells is unknown.

METHODS

Chimeric mice deficient for Notch3 in hematopoietic cells and/or resident tissue cells were generated, and kidney fibrosis and inflammation after unilateral ureteral obstruction (UUO) were analyzed. Adoptive transfer of labeled bone marrow-derived cells validated the results in a murine Leishmania ear infection model. In vitro adhesion assays, integrin activation, and extracellular matrix production were analyzed.

RESULTS

Fibrosis follows UUO, but inflammatory cell infiltration mostly depends upon Notch3 expression in hematopoietic cells, which coincides with an enhanced proinflammatory milieu (e.g., CCL2 and CCL5 upregulation). Notch3 expression on CD45⁺ leukocytes plays a prominent role in efficient cell transmigration. Functionally, leukocyte adhesion and integrin activation are abrogated in the absence of receptor Notch3. Chimeric animal models also reveal that tubulointerstitial fibrosis develops, even in the absence of prominent leukocyte infiltrates after ureteral obstruction. Deleting Notch3 receptors on resident cells blunts kidney fibrosis, ablates NF-κB signaling, and lessens matrix deposition.

CONCLUSIONS

Cell-specific receptor Notch3 signaling independently orchestrates leukocyte infiltration and organ fibrosis. Interference with Notch3 signaling may present a novel therapeutic approach in inflammatory as well as fibrotic diseases.

SIRT7: an influence factor in healthy aging and the development of age-dependent myeloid stem-cell disorders

Molecular alterations within the hematopoietic system influence cellular longevity and development of age-related myeloid stem-cell disorders like acute myeloid leukemia (AML) and chronic myeloid leukemia (CML). A reduced SIRT7-expression in aged murine hematopoietic stem cells (HSC) resulted in reduced longevity and increased proliferation. In this study we investigated age-related changes of SIRT7-expression in healthy humans and relevant pathomechanisms in AML and CML. SIRT7-expression in leukocytes of healthy people decreased in an age-dependent manner. Low SIRT7 mRNA levels were also detected in AML and CML patients. With positive treatment response, SIRT7-expression increased, but showed reduction when patients progressed or relapsed. Pharmacologic inhibition of driver mutations in AML (FLT3-ITD) or CML (BCR-ABL) also restored SIRT7 levels in cell lines and patient samples. Furthermore, SIRT7-expression increased with time during PMA-mediated monocyte differentiation of THP-1 cells. SIRT7-overexpression in THP-1 cells resulted in increased expression of differentiation markers. BCR-ABL, FLT3-ITD, and differentiation-associated SIRT7-expression in general were positively regulated by C/EBPα, -β, and -ε binding to two different C/EBP-binding sites within the SIRT7 promoter. SIRT7 is important in human hematopoietic cell aging and longevity. It might act as tumor suppressor and could potentially serve as general biomarker for monitoring treatment response in myeloid stem-cell disorders.

Prevalence and dynamics of clonal hematopoiesis caused by leukemia-associated mutations in elderly individuals without hematologic disorders

Clonal hematopoiesis is frequently observed in elderly people. To investigate the prevalence and dynamics of genetic alterations among healthy elderly individuals, a cohort of 50 people >80 years was genotyped for commonly mutated leukemia-associated genes by targeted deep next-generation sequencing. A total of 16 somatic mutations were identified in 13/50 (26%) individuals. Mutations occurred at low variant allele frequencies (median 11.7%) and remained virtually stable over 3 years without development of hematologic malignancies in affected individuals. With DNMT3A mutations most frequently detected, another cohort of 160 healthy people spanning all age groups was sequenced specifically for DNMT3A revealing an overall mutation rate of 6.2% (13/210) and an age-dependent increase of mutation prevalence. A significant difference (p = 0.017) in the DNMT3A expression pattern was detected between younger and healthy elderly people as determined by qRT-PCR. To evaluate the selection of clonal hematopoietic stem cells (HSCs), bone marrow of two healthy individuals with mutant DNMT3A was transplanted in a humanized mouse model. Xenografts displayed stable kinetics of DNMT3A mutations over 8 months. These findings indicate that the appearance of low-level clones with leukemia-associated mutations is a common age-associated phenomenon, but insufficient to initiate clonal selection and expansion without the additional influence of other factors.

Risk factors for progression to blast phase and outcome in 589 patients with myelofibrosis treated with ruxolitinib: Real-world data

The impact of ruxolitinib therapy on evolution to blast phase (BP) in patients with myelofibrosis (MF) is still uncertain. In 589 MF patients treated with ruxolitinib, we investigated incidence and risk factors for BP and we described outcome according to disease characteristics and treatment strategy. After a median follow-up from ruxolitinib start of 3 years (range 0.1-7.6), 65 (11%) patients transformed to BP during (93.8%) or after treatment. BP incidence rate was 3.7 per 100 patient-years, comparably in primary and secondary MF (PMF/SMF) but significantly lower in intermediate-1 risk patients (2.3 vs 5.6 per 100 patient-years in intermediate-2/high-risk patients, P < .001). In PMF and SMF cohorts, previous interferon therapy seemed to correlate with a lower probability of BP (HR 0.13, P = .001 and HR 0.22, P = .02, respectively). In SMF, also platelet count <150 × 10⁹ /l (HR 2.4, P = .03) and peripheral blasts ≥3% (HR 3.3, P = .004) were significantly associated with higher risk of BP. High-risk category according to dynamic International Prognostic Score System (DIPSS) and myelofibrosis secondary to PV and ET Collaboration Prognostic Model (MYSEC-PM predicted BP in patients with PMF and SMF, respectively. Median survival after BP was 0.2 (95% CI: 0.1-0.3) years. Therapy for BP included hypomethylating agents (12.3%), induction chemotherapy (9.2%), allogeneic transplant (6.2%) or supportive care (72.3%). Patients treated with supportive therapy had a median survival of 6 weeks, while 73% of the few transplanted patients were alive at a median follow-up of 2 years. Progression to BP occurs in a significant fraction of ruxolitinib-treated patients and is associated with DIPSS and MYSEC-PM risk in PMF and SMF, respectively.

Life after ruxolitinib: Reasons for discontinuation, impact of disease phase, and outcomes in 218 patients with myelofibrosis

BACKGROUND

After discontinuing ruxolitinib, the outcome of patients with myelofibrosis reportedly has been poor. The authors investigated whether disease characteristics before the receipt of ruxolitinib may predict drug discontinuation in patients with myelofibrosis and whether reasons for drug discontinuation, disease phase at discontinuation, and salvage therapies may influence the outcome.

METHODS

A centralized electronic clinical database was created in 20 European hematology centers, including clinical and laboratory data for 524 patients who received ruxolitinib for myelofibrosis.

RESULTS

At 3 years, 40.8% of patients had stopped ruxolitinib. Baseline predictors of drug discontinuation were: intermediate-2-risk/high-risk category (Dynamic International Prognostic Score System), a platelet count <100 ×10⁹ per liter, transfusion dependency, and unfavorable karyotype. At last contact, 268 patients (51.1%) had discontinued therapy, and the median drug exposure was 17.5 months. Fifty patients (18.7%) died while taking ruxolitinib. The reasons for discontinuation in the remaining 218 patients were the lack (22.9%) or loss (11.9%) of a spleen response, ruxolitinib-related adverse events (27.5%), progression to blast phase (23.4%), ruxolitinib-unrelated adverse events (9.2%), and allogeneic transplantation during response (5.1%). The median survival after ruxolitinib was 13.2 months and was significantly better in the 167 patients who discontinued ruxolitinib in chronic phase (27.5 vs 3.9 months for those who discontinued in blast phase; P < .001). No survival differences were observed among patients who discontinued ruxolitinib in chronic phase because of lack of response, loss of response, or ruxolitinib-related adverse events. The use of investigational agents and/or ruxolitinib rechallenge were associated with improved outcome.

CONCLUSIONS

The survival of patients with myelofibrosis after discontinuation of ruxolitinib is poor, particularly for those who discontinue in blast phase. Salvage therapies can improve outcome, emphasizing the need for novel therapies.

Oncogenic JAK2V617F causes PD-L1 expression, mediating immune escape in myeloproliferative neoplasms

Recent evidence has revealed that oncogenic mutations may confer immune escape. A better understanding of how an oncogenic mutation affects immunosuppressive programmed death ligand 1 (PD-L1) expression may help in developing new therapeutic strategies. We show that oncogenic JAK2 (Janus kinase 2) activity caused STAT3 (signal transducer and activator of transcription 3) and STAT5 phosphorylation, which enhanced PD-L1 promoter activity and PD-L1 protein expression in JAK2^V617F-mutant cells, whereas blockade of JAK2 reduced PD-L1 expression in myeloid JAK2^V617F-mutant cells. PD-L1 expression was higher on primary cells isolated from patients with JAK2^V617F-myeloproliferative neoplasms (MPNs) compared to healthy individuals and declined upon JAK2 inhibition. JAK2^V617F mutational burden, pSTAT3, and PD-L1 expression were highest in primary MPN patient-derived monocytes, megakaryocytes, and platelets. PD-1 (programmed death receptor 1) inhibition prolonged survival in human MPN xenograft and primary murine MPN models. This effect was dependent on T cells. Mechanistically, PD-L1 surface expression in JAK2^V617F-mutant cells affected metabolism and cell cycle progression of T cells. In summary, we report that in MPN, constitutive JAK2/STAT3/STAT5 activation, mainly in monocytes, megakaryocytes, and platelets, caused PD-L1-mediated immune escape by reducing T cell activation, metabolic activity, and cell cycle progression. The susceptibility of JAK2^V617F-mutant MPN to PD-1 targeting paves the way for immunomodulatory approaches relying on PD-1 inhibition.

Roles of JAK2 in Aging, Inflammation, Hematopoiesis and Malignant Transformation

Clonal alterations in hematopoietic cells occur during aging and are often associated with the establishment of a subclinical inflammatory environment. Several age-related conditions and diseases may be initiated or promoted by these alterations. JAK2 mutations are among the most frequently mutated genes in blood cells during aging. The most common mutation within the JAK2 gene is JAK2-V617F that leads to constitutive activation of the kinase and thereby aberrant engagement of downstream signaling pathways. JAK2 mutations can act as central drivers of myeloproliferative neoplasia, a pre-leukemic and age-related malignancy. Likewise, hyperactive JAK-signaling is a hallmark of immune diseases and critically influences inflammation, coagulation and thrombosis. In this review we aim to summarize the current knowledge on JAK2 in clonal hematopoiesis during aging, the role of JAK-signaling in inflammation and lymphocyte biology and JAK2 function in age-related diseases and malignant transformation.

Plasma VCAM1 levels correlate with disease severity in Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by motor and non-motor symptoms. There is increasing evidence that PD pathology is accompanied by an inflammatory response. This is highly relevant for understanding disease progression and the development of novel neuroprotective therapies.

OBJECTIVE

Assessing potential dysregulation of a panel of inflammatory mediators in the peripheral blood mononuclear cells (PBMCs) and plasma of PD patients and in the context of clinical outcome metrics.

METHODS

We performed a screening of selected cell-surface chemokine receptors and adhesion molecules in PBMCs from PD patients and age-matched healthy controls in a flow cytometry-based assay. ELISA was used to quantify VCAM1 levels in the plasma of PD patients. Lymphocytic chemotactic ability was assessed using a modified Boyden chamber assay.

RESULTS

VLA4 expression was significantly downregulated on CD3+ T cells, CD56+ NK cells, and CD3+/CD56+ NK-T cells from PD patients; further, an increase of the soluble VLA4 ligand VCAM1 in patient plasma was noted. sVCAM1 in PD patients was even higher than reported for patients with multiple sclerosis, neuromyelitis optica, and rheumatoid arthritis. sVCAM1 levels correlated with the disease stage (Hoehn and Yahr scale) and motor impairment. Chemoattraction with SDF-1α revealed impaired motility of lymphocytes from PD patients relative to controls.

CONCLUSION

Our data provides evidence for a functional dysregulation of the sVCAM1-VLA4 axis in PD. Further studies evaluating the therapeutic potential of this axis are warranted.

Clonal evolution patterns in acute myeloid leukemia with NPM1 mutation

Mutations in the nucleophosmin 1 (NPM1) gene are considered founder mutations in the pathogenesis of acute myeloid leukemia (AML). To characterize the genetic composition of NPM1 mutated (NPM1^mut) AML, we assess mutation status of five recurrently mutated oncogenes in 129 paired NPM1^mut samples obtained at diagnosis and relapse. We find a substantial shift in the genetic pattern from diagnosis to relapse including NPM1^mut loss (n = 11). To better understand these NPM1^mut loss cases, we perform whole exome sequencing (WES) and RNA-Seq. At the time of relapse, NPM1^mut loss patients (pts) feature distinct mutational patterns that share almost no somatic mutation with the corresponding diagnosis sample and impact different signaling pathways. In contrast, profiles of pts with persistent NPM1^mut are reflected by a high overlap of mutations between diagnosis and relapse. Our findings confirm that relapse often originates from persistent leukemic clones, though NPM1^mut loss cases suggest a second "de novo" or treatment-associated AML (tAML) as alternative cause of relapse.

Memantine potentiates cytarabine-induced cell death of acute leukemia correlating with inhibition of Kv1.3 potassium channels, AKT and ERK1/2 signaling

Background

Treatment of acute leukemia is challenging and long-lasting remissions are difficult to induce. Innovative therapy approaches aim to complement standard chemotherapy to improve drug efficacy and decrease toxicity. Promising new therapeutic targets in cancer therapy include voltage-gated K_v1.3 potassium channels, but their role in acute leukemia is unclear. We reported that K_v1.3 channels of lymphocytes are blocked by memantine, which is known as an antagonist of neuronal N-methyl-D-aspartate type glutamate receptors and clinically applied in therapy of advanced Alzheimer disease. Here we evaluated whether pharmacological targeting of K_v1.3 channels by memantine promotes cell death of acute leukemia cells induced by chemotherapeutic cytarabine.

Methods

We analyzed acute lymphoid (Jurkat, CEM) and myeloid (HL-60, Molm-13, OCI-AML-3) leukemia cell lines and patients’ acute leukemic blasts after treatment with either drug alone or the combination of cytarabine and memantine. Patch-clamp analysis was performed to evaluate inhibition of K_v1.3 channels and membrane depolarization by memantine. Cell death was determined with propidium iodide, Annexin V and SYTOX staining and cytochrome C release assay. Molecular effects of memantine co-treatment on activation of Caspases, AKT, ERK1/2, and JNK signaling were analysed by Western blot. K_v1.3 channel expression in Jurkat cells was downregulated by shRNA.

Results

Our study demonstrates that memantine inhibits K_v1.3 channels of acute leukemia cells and in combination with cytarabine potentiates cell death of acute lymphoid and myeloid leukemia cell lines as well as primary leukemic blasts from acute leukemia patients. At molecular level, memantine co-application fosters concurrent inhibition of AKT, S6 and ERK1/2 and reinforces nuclear down-regulation of MYC, a common target of AKT and ERK1/2 signaling. In addition, it augments mitochondrial dysfunction resulting in enhanced cytochrome C release and activation of Caspase-9 and Caspase-3 leading to amplified apoptosis.

Conclusions

Our study underlines inhibition of K_v1.3 channels as a therapeutic strategy in acute leukemia and proposes co-treatment with memantine, a licensed and safe drug, as a potential approach to promote cytarabine-based cell death of various subtypes of acute leukemia.

Electronic supplementary material

The online version of this article (10.1186/s12964-018-0317-z) contains supplementary material, which is available to authorized users.

Randomized comparison of low dose cytarabine with or without glasdegib in patients with newly diagnosed acute myeloid leukemia or high-risk myelodysplastic syndrome

Glasdegib is a Hedgehog pathway inhibitor. This phase II, randomized, open-label, multicenter study (ClinicalTrials.gov, NCT01546038) evaluated the efficacy of glasdegib plus low-dose cytarabine (LDAC) in patients with acute myeloid leukemia (AML) or high-risk myelodysplastic syndrome unsuitable for intensive chemotherapy. Glasdegib 100 mg (oral, QD) was administered continuously in 28-day cycles; LDAC 20 mg (subcutaneous, BID) was administered for 10 per 28 days. Patients (stratified by cytogenetic risk) were randomized (2:1) to receive glasdegib/LDAC or LDAC. The primary endpoint was overall survival. Eighty-eight and 44 patients were randomized to glasdegib/LDAC and LDAC, respectively. Median (80% confidence interval [CI]) overall survival was 8.8 (6.9–9.9) months with glasdegib/LDAC and 4.9 (3.5–6.0) months with LDAC (hazard ratio, 0.51; 80% CI, 0.39–0.67, P = 0.0004). Fifteen (17.0%) and 1 (2.3%) patients in the glasdegib/LDAC and LDAC arms, respectively, achieved complete remission (P < 0.05). Nonhematologic grade 3/4 all-causality adverse events included pneumonia (16.7%) and fatigue (14.3%) with glasdegib/LDAC and pneumonia (14.6%) with LDAC. Clinical efficacy was evident across patients with diverse mutational profiles. Glasdegib plus LDAC has a favorable benefit–risk profile and may be a promising option for AML patients unsuitable for intensive chemotherapy.