Myeloproliferative neoplasms and inflammation: whether to target the malignant clone or the inflammatory process or both

Red Blood Cell Distribution Width May Predict Drug-Induced Anemia and Prognosis in Patients Affected by Primary/Secondary Myelofibrosis Treated with Ruxolitinib

INTRODUCTION

Myelofibrosis (MF) is often characterized by a multifactorial anemia determined, in part, by bone marrow (BM) fibrosis, extramedullary erythropoiesis and splenomegaly. Ruxolitinib (RUX) is the first-in-class janus kinase 2 (JAK2) inhibitor approved for treatment of MF, proved to reduce spleen volume and decrease symptom burden. The red cell distribution width (RDW) is the measure of erythrocyte volume variability (anisocytosis). RDW has been recognized as a marker of clinical and subclinical systemic inflammation, and its elevation has also been associated with poor outcome in a wide spectrum of benign disorders and in different types of neoplasms.

METHODS

We retrospectively evaluated RDW in a single-center series of 200 consecutive patients with primary and secondary MF at RUX treatment initiation and examined any possible correlation with adverse MF features or drug-related anemia and any prognostic impact.

RESULTS

We suggested 20.5% as the optimal cutoff point in RDW values at start of RUX to dichotomize patients in receiver operating characteristic (ROC) analysis for spleen response and for survival. Higher RDW values at RUX start were associated with clinical and laboratory features of an aggressive MF phenotype. Lower spleen response (p < 0.001) and greater odds of drug-related anemia at 3 (p = 0.006) and 6 months (p < 0.001) were also seen in patients with higher RDW. Both increased RDW (considered as a continuous variable) and RDW ≥ 20.5% were associated with shorter overall survival (OS) from RUX initiation in univariate and multivariate analysis: HR 1.25 (95% confidence interval [CI], 1.12-1.40) (p < 0.001) and HR 3.01 (95% CI 1.81-4.99) (p < 0.001), respectively. RDW ≥ 20.5% at RUX start seems to possibly improve patients' sub-stratification along with anemia and conventional prognostic scoring systems.

CONCLUSIONS

RDW at RUX start might represent a good indirect measure of MF features and might have prognostic significance for RUX-treated patients affected by MF, aiding in the rapid detection of patients with poor prognosis.

Pacritinib prevents inflammation-driven myelofibrosis-like phenotype in a miR-146a-/- murine model

Chronic proinflammatory signaling is a characteristic trait in myeloproliferative neoplasms (MPN), particularly myelofibrosis (MF). Aberrant inflammatory signaling, particularly from NF-κB pathway, exacerbates the progression of MPN. Previously, we identified a critical role of miR-146a, a negative regulator of the TLR/NF-κB axis, in MF development. MPN patients carrying the miR-146a rs2431697-TT genotype, associated with lower miR-146a expression levels, have a higher risk of progression to overt-MF from chronic-phase disease. Using miR-146a-/- (KO) mice, a MF-like model lacking MPN driver mutations, we here investigate whether pacritinib, a dual JAK/NF-κB pathways inhibitor (via JAK2/IRAK1, respectively), prevents the age-associated myelofibrotic phenotype of these mice. Young miR-146a-/- mice were treated either with or without pacritinib, for 3 or 6 months. Notably, pacritinib prevented the splenomegaly, reticulin fibrosis and osteosclerosis observed in untreated KO mice. Pacritinib also avoided the myeloproliferation, loss of splenic architecture, and extramedullary hematopoiesis observed in age-matched untreated KO mice. Pharmacological targeting of IRAK1/JAK2 attenuated the pro-inflammatory environment, preventing the increase of inflammatory cytokines, particularly CXCL1 and TNF-α, without inducing cytopenias but rather the opposite. Compared to age-matched untreated KO mice, treated mice showed higher platelet counts irrespective of treatment duration, and higher erythrocyte counts with the longer treatment. Additionally, pacritinib preventive treatment reduced COL1A1 production in an in vitro model mimicking JAK2-driven fibrosis. These findings highlight that dual inhibition of JAK2/IRAK1 with pacritinib, by delaying or attenuating the myelofibrotic progression, could be a potential modifier of the natural course of MPN.

Neutrophil/lymphocyte ratio identifies low-risk polycythaemia vera patients for early Ropeginterferon alfa-2b therapy

We investigated the effect of Ropeginterferon alfa-2b (Ropeg) versus phlebotomy-only (Phl-O) on the neutrophil-to-lymphocyte ratio (NLR) in 126 patients randomized in the low-polycythaemia vera (PV) phase II trial. Patients with a baseline NLR ≥3.5 vs. <3.5 had a longer history of PV, were more likely to have splenomegaly, higher JAK2V617F variant allele frequency (VAF) (56% vs. 20% p = 0.001) and more proliferative disease. Ropeg was superior to Phl-O in reducing NLR (p = 0.008), and the reduction was strongly influenced by the reduction in neutrophils and less by a change in lymphocytes (-59% and -14% respectively). This effect was associated with the achievement of the low-PV primary end-point (p = 0.021), symptom reduction and reduction in JAK2 VAF. Interestingly, the reduction in JAK2 VAF from baseline was linearly associated with the reduction in NLR. Patients who failed Phl-O at 12 months had characteristics that distinguished them from responders, including very high NLR and resistance to cross-over to 100 μg Ropeg every 2 weeks suggesting higher escalated doses of Ropeg. In conclusion, the study provides evidence that NLR can serve as a valuable biomarker to assess and guide treatment with Ropeg in the early stage of low-risk PV patients.

Neutrophil-to-lymphocyte ratio (NLR) at diagnosis in essential thrombocythemia: A new promising predictor of thrombotic events

BACKGROUND

Myeloproliferative neoplasms represent a heterogeneous group of acquired hematopoietic stem cell diseases in which chronic inflammation is essential for both clonal evolution and thrombotic complications. The neutrophil-to-lymphocyte ratio (NLR), reflecting the imbalance between systemic inflammation and immunity, is emerging as a prognostic biomarker in several diseases, including hematological ones.

METHODS

A total of 473 patients with essential thrombocythemia (ET), the relationship between NLR value at diagnosis and the risk of thrombotic events in the follow-up, in addition to conventional clinical and biological variables, were retrospectively analyzed.

RESULTS

A total of 78 thrombotic events were reported for an incidence rate of 1.8 × 100 patients/year. In multivariate analysis, NLR value ≥4 at diagnosis was associated with higher cumulative thrombotic risk (hazard ratio [HR], 2.05; 95% CI, 1.29-2.28; p = .0001) as well International Prognostic Score for Thrombosis in Essential Thrombosis score intermediate-high (HR, 2.69; 95% CI, 1.27-5.72; p = .01) and diabetes (HR, 2.49; 95% CI, 1.23-3.05; p = .010). Concerning arterial thrombotic events, in multivariate analysis, NLR value at diagnosis ≥4 was predictive for thrombosis (HR, 2.13; 95% CI, 1.31-4.04; p = .001 as well diabetes (HR, 2.44; 95% CI, 1.05-5.68; p = .04) and hypertension (HR, 2.46; 95% CI, 1.05-5.68; p = .01). About venous thrombotic events, NLR value ≥5 was a marker predictive for venous thrombosis (HR, 2.99; 95% CI, 2.45-6.48; p = .01) as well age >60 years old (HR, 2.26; 95% CI, 1.0-5.10; p = .05).

CONCLUSION

NLR value is a simple, cost-effective, and easy-to-obtain inflammatory marker that can predict a diagnosis the risk of thrombosis in ET. Our results suggest that NLR value could be integrated into conventional cardiovascular risk scores, to better classify high-risk patients who are candidates for cytoreductive therapy. Further larger and prospective studies are warranted.

Combination therapy with ruxolitinib and pegylated interferon alfa-2a in newly diagnosed patients with polycythemia vera

ABSTRACT

We report the 2-year end-of-study results from the phase 2 COMBI II clinical trial investigating the combination treatment of ruxolitinib and low-dose pegylated interferon alfa-2a in patients with newly diagnosed polycythemia vera (PV). The primary outcome was safety and key secondary endpoints were efficacy, based on hematologic parameters, quality-of-life measurements, and JAK2V617F variant allele frequency (VAF). We used the 2013 European LeukemiaNet and International Working Group-Myeloproliferative Neoplasms Research remission criteria. The remission criteria included remissions in symptoms, splenomegaly, peripheral blood counts, and bone marrow. We included 25 patients with PV with a median age of 70 years; 5 of those had prior thromboembolic events and 3 had computed tomography-verified splenomegaly. Two patients stopped both study drugs; 1 of these due to progression to post-PV myelofibrosis, the only one with a grade 3 infection. No events of herpes zoster infections were observed. None of the patients discontinued treatment due to psychiatric symptoms. The peripheral blood cell count remission rate was 92% at 24 months. Using the 2013 European LeukemiaNet and International Working Group-Myeloproliferative Neoplasms Research remission criteria, 14 (56%) achieved remission at 24 months; 3 (12%) achieved complete remission and 11 (44%) achieved partial remission. The following items from the Myeloproliferative Neoplasm Symptom Total Symptom Score were significantly reduced: abdominal discomfort, night sweats, itching, and bone pain. The median JAK2V617F VAF decreased from 47% (95% confidence interval [CI], 35-59) to 7% (95% CI, 3-15), and 60% of patients achieved molecular remission. In conclusion, combination treatment improved cell counts; bone marrow cellularity, and fibrosis; and decreased JAK2V617F VAF; with acceptable toxicity in patients with PV. The trial was registered at www.clinicaltrialsregister.eu as #EudraCT2018-004150-13.

Wong Z, Karali CS, Sirinukunwattana K, Ryou H, Norfo R, Cheng Q, Carrelha J, Ren Z, Thongjuea S, Rathinam VA, Krishnan A, Royston D, Rabinovich GA, Mead AJ, Psaila B. A proinflammatory stem cell niche drives myelofibrosis through a targetable galectin-1 axis

Myeloproliferative neoplasms are stem cell-driven cancers associated with a large burden of morbidity and mortality. Most patients present with early-stage disease, but a substantial proportion progress to myelofibrosis or secondary leukemia, advanced cancers with a poor prognosis and high symptom burden. Currently, it remains difficult to predict progression, and therapies that reliably prevent or reverse fibrosis are lacking. A major bottleneck to the discovery of disease-modifying therapies has been an incomplete understanding of the interplay between perturbed cellular and molecular states. Several cell types have individually been implicated, but a comprehensive analysis of myelofibrotic bone marrow is lacking. We therefore mapped the cross-talk between bone marrow cell types in myelofibrotic bone marrow. We found that inflammation and fibrosis are orchestrated by a "quartet" of immune and stromal cell lineages, with basophils and mast cells creating a TNF signaling hub, communicating with megakaryocytes, mesenchymal stromal cells, and proinflammatory fibroblasts. We identified the β-galactoside-binding protein galectin-1 as a biomarker of progression to myelofibrosis and poor survival in multiple patient cohorts and as a promising therapeutic target, with reduced myeloproliferation and fibrosis in vitro and in vivo and improved survival after galectin-1 inhibition. In human bone marrow organoids, TNF increased galectin-1 expression, suggesting a feedback loop wherein the proinflammatory myeloproliferative neoplasm clone creates a self-reinforcing niche, fueling progression to advanced disease. This study provides a resource for studying hematopoietic cell-niche interactions, with relevance for cancer-associated inflammation and disorders of tissue fibrosis.

Proteomic screening identifies PF4/Cxcl4 as a critical driver of myelofibrosis

Despite increased understanding of the genomic landscape of Myeloproliferative Neoplasms (MPNs), the pathological mechanisms underlying abnormal megakaryocyte (Mk)-stromal crosstalk and fibrotic progression in MPNs remain unclear. We conducted mass spectrometry-based proteomics on mice with Romiplostim-dependent myelofibrosis to reveal alterations in signaling pathways and protein changes in Mks, platelets, and bone marrow (BM) cells. The chemokine Platelet Factor 4 (PF4)/Cxcl4 was up-regulated in all proteomes and increased in plasma and BM fluids of fibrotic mice. High TPO concentrations sustained in vitro PF4 synthesis and secretion in cultured Mks, while Ruxolitinib restrains the abnormal PF4 expression in vivo. We discovered that PF4 is rapidly internalized by stromal cells through surface glycosaminoglycans (GAGs) to promote myofibroblast differentiation. Cxcl4 gene silencing in Mks mitigated the profibrotic phenotype of stromal cells in TPO-saturated co-culture conditions. Consistently, extensive stromal PF4 uptake and altered GAGs deposition were detected in Romiplostim-treated, JAK2V617F mice and BM biopsies of MPN patients. BM PF4 levels and Mk/platelet CXCL4 expression were elevated in patients, exclusively in overt fibrosis. Finally, pharmacological inhibition of GAGs ameliorated in vivo fibrosis in Romiplostim-treated mice. Thus, our findings highlight the critical role of PF4 in the fibrosis progression of MPNs and substantiate the potential therapeutic strategy of neutralizing PF4-GAGs interaction.

The evolving landscape of polycythemia vera therapies

INTRODUCTION

The treatment landscape of polycythemia vera (PV) has seen major advancements within the last decade including approval of ruxolitinib in the second line setting after hydroxyurea, ropegylated interferon-α2b, and advanced clinical development of a novel class of agents called hepcidin mimetics.

AREAS COVERED

We provide a comprehensive review of the evidence discussing the risk stratification, treatment indications, role and limitations of phlebotomy only approach and pivotal trials covering nuances related to the use of interferon-α (IFN-α), ruxolitinib, hepcidin mimetics, and upcoming investigational agents including HDAC and LSD1 inhibitors.

EXPERT OPINION

The research paradigm in PV is slowly shifting from the sole focus on hematocrit control and moving toward disease modification. The discovery of hepcidin mimetics has come as a breakthrough in restoring iron homeostasis, achieving phlebotomy-independence and may lead to improved thrombosis-free survival with stricter hematocrit control. On the other hand, emerging data with IFN- α and ruxolitinib as well as combination of the two agents suggests the potential for achieving molecular remission in a subset of PV patients and long-term follow-up is awaited to validate the correlation of molecular responses with clinically relevant outcomes of progression-free and thrombosis-free survival.

miR-146a-/- mice model reveals that NF-κB inhibition reverts inflammation-driven myelofibrosis-like phenotype

Emerging evidence shows the crucial role of inflammation (particularly NF-κB pathway) in the development and progression of myelofibrosis (MF), becoming a promising therapeutic target. Furthermore, tailoring treatment with currently available JAK inhibitors (such as ruxolitinib or fedratinib) does not modify the natural history of the disease and has important limitations, including cytopenias. Since recent studies have highlighted the role of miR-146a, a negative regulator of the NF-κB pathway, in the pathogenesis of MF; here we used miR-146a-/- (KO) mice, a MF-like model lacking driver mutations, to investigate whether pharmacological inhibition of JAK/STAT and/or NF-κB pathways may reverse the myelofibrotic phenotype of these mice. Specifically, we tested the JAK1/2 inhibitor, ruxolitinib; the NF-κB inhibitor via IKKα/β, BMS-345541; both inhibitors in combination; or a dual inhibitor of both pathways (JAK2/IRAK1), pacritinib. Although all treatments decreased spleen size and partially recovered its architecture, only NF-κB inhibition, either using BMS-345541 (alone or in combination) or pacritinib, resulted in a reduction of extramedullary hematopoiesis, bone marrow (BM) fibrosis and osteosclerosis, along with an attenuation of the exacerbated inflammatory state (via IL-1β and TNFα). However, although dual inhibitor improved anemia and reversed thrombocytopenia, the combined therapy worsened anemia by inducing BM hypoplasia. Both therapeutic options reduced NF-κB and JAK/STAT signaling in a context of JAK2V617F-driven clonal hematopoiesis. Additionally, combined treatment reduced both COL1A1 and IL-6 production in an in vitro model mimicking JAK2-driven fibrosis. In conclusion, NF-κB inhibition reduces, in vitro and in vivo, disease burden and BM fibrosis, which could provide benefits in myelofibrosis patients.

Differential effects of itacitinib, fedratinib, and ruxolitinib in mouse models of hemophagocytic lymphohistiocytosis

ABSTRACT

Hemophagocytic lymphohistiocytosis (HLH) comprises a severe hyperinflammatory phenotype driven by the overproduction of cytokines, many of which signal via the JAK/STAT pathway. Indeed, the JAK1/2 inhibitor ruxolitinib has demonstrated efficacy in preclinical studies and early-phase clinical trials in HLH. Nevertheless, concerns remain for ruxolitinib-induced cytopenias, which are postulated to result from the blockade of JAK2-dependent hematopoietic growth factors. To explore the therapeutic effects of selective JAK inhibition in mouse models of HLH, we carried out studies incorporating the JAK1 inhibitor itacitinib, JAK2 inhibitor fedratinib, and JAK1/2 inhibitor ruxolitinib. All 3 drugs were well-tolerated and at the doses tested, they suppressed interferon-gamma (IFN-γ)-induced STAT1 phosphorylation in vitro and in vivo. Itacitinib, but not fedratinib, significantly improved survival and clinical scores in CpG-induced secondary HLH. Conversely, in primary HLH, in which perforin-deficient (Prf1-/-) mice are infected with lymphocytic choriomeningitis virus (LCMV), itacitinib, and fedratinib performed suboptimally. Ruxolitinib demonstrated excellent clinical efficacy in both HLH models. RNA-sequencing of splenocytes from LCMV-infected Prf1-/- mice revealed that itacitinib targeted inflammatory and metabolic pathway genes in CD8 T cells, whereas fedratinib targeted genes regulating cell proliferation and metabolism. In monocytes, neither drug conferred major transcriptional impacts. Consistent with its superior clinical effects, ruxolitinib exerted the greatest transcriptional changes in CD8 T cells and monocytes, targeting more genes across several biologic pathways, most notably JAK-dependent proinflammatory signaling. We conclude that JAK1 inhibition is sufficient to curtail CpG-induced disease, but combined inhibition of JAK1 and JAK2 is needed to best control LCMV-induced immunopathology.

JAK2V617F drives gut microbiota differences in patients with myeloproliferative neoplasms

BACKGROUND

Essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (MF) are myeloproliferative neoplasms (MPN). Inflammation is involved in the initiation, progression, and symptomology of the diseases. The gut microbiota impacts the immune system, infection control, and steady-state hematopoiesis.

METHODS

We analyzed the gut microbiota of 227 MPN patients and healthy controls (HCs) using next-generation sequencing. We expanded our previous results in PV and ET patients with additional PV, pre-MF, and MF patients which allowed us to compare MPN patients collectively, MPN sub-diagnoses, and MPN mutations (separately and combined) vs. HCs (N = 42) and compare within MPN sub-diagnoses and MPN mutation.

RESULTS

MPN patients had a higher observed richness (median, 245 [range, 49-659]) compared with HCs (191.5 [range, 111-300; p = .003]) and a lower relative abundance of taxa within the Firmicutes phylum; for example, Faecalibacterium (6% vs. 14%, p < .001). The microbiota of CALR-positive patients (N = 30) resembled that of HCs more than that of patients with JAK2V617F (N = 177). In JAK2V617F-positive patients, only minor differences in the gut microbiota were observed between MPN sub-diagnoses, illustrating the importance of this mutation.

CONCLUSION

The gut microbiota in MPN patients differs from HCs and is driven by JAK2V617F, whereas the gut microbiota in CALR patients resembles HCs more.

Neutrophil-to-lymphocyte ratio and all-cause mortality with and without myeloproliferative neoplasms-a Danish longitudinal study

The neutrophil-to-lymphocyte ratio(NLR) is increased in chronic inflammation and myeloproliferative neoplasms (MPN). We hypothesize that NLR is associated with all-cause mortality and mortality by comorbidity burden in the general population and individuals with MPN. We included 835,430 individuals from The Danish General Suburban Population Study, general practitioners, and outpatient clinics. We investigated NLR on mortality stratified by prevalent and incident MPN, essential thrombocythemia (ET), polycythemia vera (PV), myelofibrosis (MF), comorbidity burden (CCI-score), and the Triple-A risk score using hazard ratio (HR) and 95% confidence interval (95%CI). NLR 1-1.9 was the reference level. During a median follow-up of 11.2 years, 197,802 deaths were recorded. All-cause mortality increased for a stepwise increasing NLR with a HR (95%CI) for NLR ≥ 6 of 2.06(2.03-2.09) for the whole population and 2.93(2.44-3.50) in prevalent MPN. ET, PV, and MF had a HR (95%CI) for NLR ≥ 2 of 2.14(1.71-2.69), 2.19(1.89-2.54), and 2.31(1.91-2.80). Results were similar for incident MPN. Mortality was higher for stepwise increasing NLR and CCI-score(pinteraction < 2×10-16), with a HR for NLR ≥ 6 of 2.23(2.17-2.29), 4.10(4.01-4.20), and 7.69(7.50-7.89), for CCI-score 0, 1-2, or ≥3. The Triple-A risk score demonstrated alignment with NLR. Increasing NLR and comorbidity burden were associated with lower survival in individuals without MPN but were even worse in prevalent and incident MPN, ET, PV, and MF.

Inherited polygenic effects on common hematological traits influence clonal selection on JAK2V617F and the development of myeloproliferative neoplasms

Myeloproliferative neoplasms (MPNs) are chronic cancers characterized by overproduction of mature blood cells. Their causative somatic mutations, for example, JAK2V617F, are common in the population, yet only a minority of carriers develop MPN. Here we show that the inherited polygenic loci that underlie common hematological traits influence JAK2V617F clonal expansion. We identify polygenic risk scores (PGSs) for monocyte count and plateletcrit as new risk factors for JAK2V617F positivity. PGSs for several hematological traits influenced the risk of different MPN subtypes, with low PGSs for two platelet traits also showing protective effects in JAK2V617F carriers, making them two to three times less likely to have essential thrombocythemia than carriers with high PGSs. We observed that extreme hematological PGSs may contribute to an MPN diagnosis in the absence of somatic driver mutations. Our study showcases how polygenic backgrounds underlying common hematological traits influence both clonal selection on somatic mutations and the subsequent phenotype of cancer.

Micro-environment alterations through time leading to myeloid malignancies

The micro-environment plays a critical role in haematopoietic stem cell (HSC) development, self-renewal, differentiation and maintenance by providing a supportive cellular framework and essential molecular cues to sustain homeostasis. In ageing and development of age-related clonal haematopoiesis, the combined contribution of intrinsic alterations in haematopoietic stem cells and their surrounding micro-environment can promote myeloid skewing and release of pro-inflammatory cytokines. A pro-inflammatory micro-environment is a common feature in the initiation and sustenance of several myeloid malignancies. Furthermore, remodelling of the micro-environment is recognized to potentiate the survival of malignant over normal cells. This review explores micro-environmental interactions in the haematopoietic system of adults, especially how the bone marrow micro-environment is impacted by ageing, the onset of age-related clonal haematopoiesis and the development of myeloid malignancies. In addition, we also discuss the possible role age-related clonal haematopoiesis and chronic inflammatory conditions play in altering the bone marrow micro-environment dynamics. Finally, we explore the importance of in vitro models that accurately mimic different aspects of the bone marrow micro-environment in order to study normal and malignant haematopoiesis. LINKED ARTICLES: This article is part of a themed issue on Cancer Microenvironment and Pharmacological Interventions. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.2/issuetoc.

Whole blood transcriptional profiling reveals highly deregulated atherosclerosis genes in Philadelphia-chromosome negative myeloproliferative neoplasms

BACKGROUND

The Philadelphia-negative chronic myeloproliferative neoplasms (MPNs) are associated with a huge comorbidity burden, including an increased risk of cardiovascular diseases. Recently, chronic inflammation has been suggested to be the driving force for clonal evolution and disease progression in MPN but also potentially having an impact upon the development of accelerated (premature) atherosclerosis.

OBJECTIVES

Since chronic inflammation, atherosclerosis, and atherothrombosis are prevalent in MPNs and we have previously shown oxidative stress genes to be markedly upregulated in MPNs, we hypothesized that genes linked to development of atherosclerosis might be highly deregulated as well.

METHODS

Using whole blood gene expression profiling in patients with essential thrombocythemia (ET; n = 19), polycythemia vera (PV; n = 41), or primary myelofibrosis (PMF; n = 9), we herein for the first time report aberrant expression of several atherosclerosis genes.

RESULTS

Of 84 atherosclerosis genes, 45, 56, and 46 genes were deregulated in patients with ET, PV, or PMF, respectively. Furthermore, BCL2L1, MMP1, PDGFA, PTGS1, and THBS4 were progressively significantly upregulated and BCL2 progressively significantly downregulated from ET over PV to PMF (all FDR <0.05).

CONCLUSIONS

We have for the first time shown massive deregulation of atherosclerosis genes in MPNs, likely reflecting the inflammatory state in MPNs in association with in vivo activation of leukocytes, platelets, and endothelial cells being deeply involved in the atherosclerotic process.

JAK2V617F mutation is highly prevalent in patients with ischemic stroke: a case-control study

Ischemic stroke has a high recurrence rate despite treatment. This underlines the significance of investigating new possible cerebrovascular risk factors, such as the acquired gene mutation JAK2V617F found in 3.1% of the general population. We aimed to investigate the prevalence of the JAK2V617F mutation in a population with ischemic stroke compared with that in matched controls. We enrolled 538 consecutive Danish patients with ischemic stroke (mean age, 69.5 ± 10.9 years; 39.2% female) within 7 days of symptom onset. Using multiple-adjusted conditional logistic regression analysis, we compared the prevalence of JAK2V617F with that in age- and sex-matched controls free of ischemic cerebrovascular disease (ICVD) from the Danish General Suburban Population Study. DNA was analyzed for JAK2V617F mutation using sensitive droplet digital polymerase chain reaction in patients and controls. Of the 538 patients with ischemic stroke, 61 (11.3%) had JAK2V617F mutation. There were no differences in patient demographics or cerebrovascular comorbidities between the patients with and without mutations. Patients with ischemic stroke were more likely to have the JAK2V617F mutation than matched controls, in whom the JAK2V617F prevalence was 4.4% (odds ratio, 2.37; 95% confidence interval, 1.57-3.58; P < .001). A subanalysis stratified by smoking history revealed that the association was strongest in current smokers (odds ratio, 4.78; 95% confidence interval, 2.22-10.28; P < .001). Patients with ischemic stroke were 2.4 times more likely to have the JAK2V617F mutation than matched controls without ICVD when adjusting for other cerebrovascular risk factors. This finding supports JAK2V617F mutation as a novel cerebrovascular risk factor.

Elevated white blood cell counts in ischemic stroke patients are associated with increased mortality and new vascular events

Background and purpose

High levels of white blood cells (WBC) in ischemic stroke have been shown to increase the risk of new vascular events and mortality in short and intermediate follow-up studies, but long-term effects remain unknown. We studied whether elevated levels of WBC in ischemic stroke patients are associated with new vascular events and mortality in a 10-year follow-up period.

Methods

We included ischemic stroke patients hospitalized between 2011 and 2012, categorizing their WBC counts within 48 h of stroke onset as high or normal (3.5-8.8 × 109 mmol/L; >8.8 × 109 mmol/L). Using Aahlen Johansen and Cox proportional hazard models with competing risk, we analyzed the association between WBC levels and new vascular events. Kaplan-Meier and standard Cox proportional hazard models were used to assess the risk of all-cause mortality.

Results

Among 395 patients (median age 69, [IQR: 63, 78], female patients 38,0%), 38.5% had elevated WBC at admission. During the 10-year follow-up, 113 vascular events occurred, with 46% in patients with elevated WBC and 54% in patients with normal WBC. After adjusting for relevant factors, elevated WBC levels were independently associated with increased risk of new vascular events (HR: 1.61, CI: 1.09-2.39 p < 0.05) and death (HR: 1.55, CI: 1.15-2.09, p < 0.05).

Conclusion

Elevated WBC levels in ischemic stroke patients are linked to a higher risk of new vascular events and mortality. Thus, ischemic stroke patients with elevated WBC without clinical infection need special attention to investigate possible underlying conditions to prevent future vascular events and reduce mortality. The interpretation of our results is limited by the absence of adjustment to premorbid functional status, stroke severity, and stroke treatment.

Revisiting Circulating Extracellular Matrix Fragments as Disease Markers in Myelofibrosis and Related Neoplasms

Philadelphia chromosome-negative chronic myeloproliferative neoplasms (MPNs) arise due to acquired somatic driver mutations in stem cells and develop over 10-30 years from the earliest cancer stages (essential thrombocythemia, polycythemia vera) towards the advanced myelofibrosis stage with bone marrow failure. The JAK2V617F mutation is the most prevalent driver mutation. Chronic inflammation is considered to be a major pathogenetic player, both as a trigger of MPN development and as a driver of disease progression. Chronic inflammation in MPNs is characterized by persistent connective tissue remodeling, which leads to organ dysfunction and ultimately, organ failure, due to excessive accumulation of extracellular matrix (ECM). Considering that MPNs are acquired clonal stem cell diseases developing in an inflammatory microenvironment in which the hematopoietic cell populations are progressively replaced by stromal proliferation-"a wound that never heals"-we herein aim to provide a comprehensive review of previous promising research in the field of circulating ECM fragments in the diagnosis, treatment and monitoring of MPNs. We address the rationales and highlight new perspectives for the use of circulating ECM protein fragments as biologically plausible, noninvasive disease markers in the management of MPNs.

Phenotypic characterization of disease-initiating stem cells in JAK2- or CALR-mutated myeloproliferative neoplasms

Myeloproliferative neoplasms (MPN) are characterized by uncontrolled expansion of myeloid cells, disease-related mutations in certain driver-genes including JAK2, CALR, and MPL, and a substantial risk to progress to secondary acute myeloid leukemia (sAML). Although behaving as stem cell neoplasms, little is known about disease-initiating stem cells in MPN. We established the phenotype of putative CD34+ /CD38- stem cells and CD34+ /CD38+ progenitor cells in MPN. A total of 111 patients with MPN suffering from polycythemia vera, essential thrombocythemia, or primary myelofibrosis (PMF) were examined. In almost all patients tested, CD34+ /CD38- stem cells expressed CD33, CD44, CD47, CD52, CD97, CD99, CD105, CD117, CD123, CD133, CD184, CD243, and CD274 (PD-L1). In patients with PMF, MPN stem cells often expressed CD25 and sometimes also CD26 in an aberrant manner. MPN stem cells did not exhibit substantial amounts of CD90, CD273 (PD-L2), CD279 (PD-1), CD366 (TIM-3), CD371 (CLL-1), or IL-1RAP. The phenotype of CD34+ /CD38- stem cells did not change profoundly during progression to sAML. The disease-initiating capacity of putative MPN stem cells was confirmed in NSGS mice. Whereas CD34+ /CD38- MPN cells engrafted in NSGS mice, no substantial engraftment was produced by CD34+ /CD38+ or CD34- cells. The JAK2-targeting drug fedratinib and the BRD4 degrader dBET6 induced apoptosis and suppressed proliferation in MPN stem cells. Together, MPN stem cells display a unique phenotype, including cytokine receptors, immune checkpoint molecules, and other clinically relevant target antigens. Phenotypic characterization of neoplastic stem cells in MPN and sAML should facilitate their enrichment and the development of stem cell-eradicating (curative) therapies.

The Role of NLRP3, a Star of Excellence in Myeloproliferative Neoplasms

Nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3) is the most widely investigated inflammasome member whose overactivation can be a driver of several carcinomas. It is activated in response to different signals and plays an important role in metabolic disorders and inflammatory and autoimmune diseases. NLRP3 belongs to the pattern recognition receptors (PRRs) family, expressed in numerous immune cells, and it plays its primary function in myeloid cells. NLRP3 has a crucial role in myeloproliferative neoplasms (MPNs), considered to be the diseases best studied in the inflammasome context. The investigation of the NLRP3 inflammasome complex is a new horizon to explore, and inhibiting IL-1β or NLRP3 could be a helpful cancer-related therapeutic strategy to improve the existing protocols.

A Killer Disarmed: Natural Killer Cell Impairment in Myelodysplastic Syndrome

Myelodysplastic syndrome (MDS) treatment remains a big challenge due to the heterogeneous nature of the disease and its ability to progress to acute myeloid leukemia (AML). The only curative option is allogeneic hematopoietic stem cell transplantation (HSCT), but most patients are unfit for this procedure and are left with only palliative treatment options, causing a big unmet need in the context of this disease. Natural killer (NK) cells are attractive candidates for MDS immunotherapy due to their ability to target myeloid leukemic cells without prior sensitization, and in recent years we have seen an arising number of clinical trials in AML and, recently, MDS. NK cells are reported to be highly dysfunctional in MDS patients, which can be overcome by adoptive NK cell immunotherapy or activation of endogenous NK cells. Here, we review the role of NK cells in MDS, the contribution of the tumor microenvironment (TME) to NK cell impairment, and the most recent data from NK cell-based clinical trials in MDS.

DUSP6 mediates resistance to JAK2 inhibition and drives leukemic progression

Myeloproliferative neoplasms (MPNs) exhibit a propensity for transformation to secondary acute myeloid leukemia (sAML), for which the underlying mechanisms remain poorly understood, resulting in limited treatment options and dismal clinical outcomes. Here, we performed single-cell RNA sequencing on serial MPN and sAML patient stem and progenitor cells, identifying aberrantly increased expression of DUSP6 underlying disease transformation. Pharmacologic dual-specificity phosphatase (DUSP)6 targeting led to inhibition of S6 and Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling while also reducing inflammatory cytokine production. DUSP6 perturbation further inhibited ribosomal S6 kinase (RSK)1, which we identified as a second indispensable candidate associated with poor clinical outcome. Ectopic expression of DUSP6 mediated JAK2-inhibitor resistance and exacerbated disease severity in patient-derived xenograft (PDX) models. Contrastingly, DUSP6 inhibition potently suppressed disease development across Jak2V617F and MPLW515L MPN mouse models and sAML PDXs without inducing toxicity in healthy controls. These findings underscore DUSP6 in driving disease transformation and highlight the DUSP6-RSK1 axis as a vulnerable, druggable pathway in myeloid malignancies.

Arginase‐1+ bone marrow myeloid cells are reduced in myeloproliferative neoplasms and correlate with clinical phenotype, fibrosis, and molecular driver

INTRODUCTION

Philadelphia-negative myeloproliferative neoplasms (MPN) are clonal myeloid proliferative disorders characterized by sustained systemic inflammation. Despite its renowned importance, the knowledge concerning the inflammatory pathophysiology of these conditions is currently limited to studies on serum cytokines, while cellular immunity has rarely been investigated.

METHODS

In the present study, we targeted Arginase-1 immunosuppressive myeloid cells in the bone marrow of MPN patients and healthy controls and investigated their clinical and prognostic significance. We demonstrated that MPN are characterized by a significant reduction of bone marrow immunosuppressive cells and that the number of these cells significantly correlates with several clinical and histopathological features of diagnostic and prognostic importance. Moreover, we identified an unreported correlation between a reduction of Arginase-1+ bone marrow cells and the presence of CALR mutations, linking tumor-promoting immunity and molecular drivers. Finally, we postulate that the reduction of bone marrow Arginase-1+ immunosuppressive cells may be due to the migration of these cells to the spleen, where they may exert systemic immunomodulatory function.

CONCLUSION

Altogether, this study preliminary investigated the contribution of cellular immunity in the pathogenesis of myeloproliferative neoplasms and identified a possible interesting therapeutic target as well as a set of new links that may contribute to unraveling the biological mechanisms behind these interesting hematological neoplasms.

Recombinant Interferon-β in the Treatment of Polycythemia Vera and Related Neoplasms: Rationales and Perspectives

About 30 years ago, the first clinical trials of the safety and efficacy of recombinant interferon-α2 (rIFN-α2) were performed. Since then, several single-arm studies have shown rIFN-α2 to be a highly potent anticancer agent against several cancer types. Unfortunately, however, a high toxicity profile in early studies with rIFN-α2 -among other reasons likely due to the high dosages being used-disqualified rIFN-α2, which was accordingly replaced with competitive drugs that might at first glance look more attractive to clinicians. Later, pegylated IFN-α2a (Pegasys) and pegylated IFN-α2b (PegIntron) were introduced, which have since been reported to be better tolerated due to reduced toxicity. Today, treatment with rIFN-α2 is virtually outdated in non-hematological cancers, where other immunotherapies-e.g., immune-checkpoint inhibitors-are routinely used in several cancer types and are being intensively investigated in others, either as monotherapy or in combination with immunomodulatory agents, although only rarely in combination with rIFN-α2. Within the hematological malignancies, rIFN-α2 has been used off-label for decades in patients with Philadelphia-negative chronic myeloproliferative neoplasms (MPNs)-i.e., essential thrombocythemia, polycythemia vera, and myelofibrosis-and in recent years rIFN-α2 has been revived with the marketing of ropeginterferon-α2b (Besremi) for the treatment of polycythemia vera patients. Additionally, rIFN-α2 has been revived for the treatment of chronic myelogenous leukemia in combination with tyrosine kinase inhibitors. Another rIFN formulation-recombinant interferon-β (rIFN-β)-has been used for decades in the treatment of multiple sclerosis but has never been studied as a potential agent to be used in patients with MPNs, although several studies and reviews have repeatedly described rIFN-β as an effective anticancer agent as well. In this paper, we describe the rationales and perspectives for launching studies on the safety and efficacy of rIFN-β in patients with MPNs.

A macaque clonal hematopoiesis model demonstrates expansion of TET2-disrupted clones and utility for testing interventions

Individuals with age-related clonal hematopoiesis (CH) are at greater risk for hematologic malignancies and cardiovascular diseases. However, predictive preclinical animal models to recapitulate the spectrum of human CH are lacking. Through error-corrected sequencing of 56 human CH/myeloid malignancy genes, we identified natural CH driver mutations in aged rhesus macaques matching genes somatically mutated in human CH, with DNMT3A mutations being the most frequent. A CH model in young adult macaques was generated via autologous transplantation of clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9-mediated gene-edited hematopoietic stem and progenitor cells (HSPCs), targeting the top human CH genes with loss-of-function (LOF) mutations. Long-term follow-up revealed reproducible and significant expansion of multiple HSPC clones with heterozygous TET2 LOF mutations, compared with minimal expansion of clones bearing other mutations. Although the blood counts of these CH macaques were normal, their bone marrows were hypercellular and myeloid-predominant. TET2-disrupted myeloid colony-forming units isolated from these animals showed a distinct hyperinflammatory gene expression profile compared with wild type. In addition, mature macrophages purified from the CH macaques showed elevated NLRP3 inflammasome activity and increased interleukin-1β (IL-1β) and IL-6 production. The model was used to test the impact of IL-6 blockage by tocilizumab, documenting a slowing of TET2-mutated expansion, suggesting that interruption of the IL-6 axis may remove the selective advantage of mutant HSPCs. These findings provide a model for examining the pathophysiology of CH and give insights into potential therapeutic interventions.

Interleukin-1 contributes to clonal expansion and progression of bone marrow fibrosis in JAK2V617F-induced myeloproliferative neoplasm

Chronic inflammation is frequently associated with myeloproliferative neoplasms (MPN), but the role of inflammation in the pathogenesis of MPN remains unclear. Expression of the proinflammatory cytokine interleukin-1 (IL-1) is elevated in patients with MPN as well as in Jak2V617F knock-in mice. Here, we show that genetic deletion of IL-1 receptor 1 (IL-1R1) normalizes peripheral blood counts, reduces splenomegaly and ameliorates bone marrow fibrosis in homozygous Jak2V617F mouse model of myelofibrosis. Deletion of IL-1R1 also significantly reduces Jak2V617F mutant hematopoietic stem/progenitor cells. Exogenous administration of IL-1β enhances myeloid cell expansion and accelerates the development of bone marrow fibrosis in heterozygous Jak2V617F mice. Furthermore, treatment with anti-IL-1R1 antibodies significantly reduces leukocytosis and splenomegaly, and ameliorates bone marrow fibrosis in homozygous Jak2V617F mice. Collectively, these results suggest that IL-1 signaling plays a pathogenic role in MPN disease progression, and targeting of IL-1R1 could be a useful strategy for the treatment of myelofibrosis.

Cytokine pathway variants modulate platelet production: IFNA16 is a thrombocytosis susceptibility locus in humans

Inflammatory stimuli have divergent effects on peripheral platelet counts, although the mechanisms of thrombocytopenic and thrombocytotic responses remain poorly understood. A candidate gene approach targeting 326 polymorphic genes enriched in thrombopoietic and cytokine signaling pathways was applied to identify single nucleotide variants (SNVs) implicated in enhanced platelet responses in cohorts with reactive thrombocytosis (RT) or essential (myeloproliferative neoplasm [MPN]) thrombocytosis (ET). Cytokine profiles incorporating a 15-member subset, pathway topology, and functional interactive networks were distinct between ET and RT, consistent with distinct regulatory pathways of exaggerated thrombopoiesis. Genetic studies using aggregate (ET + RT) or ET-restricted cohorts identified associations with 2 IFNA16 (interferon-α16) SNVs, and the ET associations were validated in a second independent cohort (P = .0002). Odds ratio of the combined ET cohort (n = 105) was 4.92, restricted to the JAK2V617F-negative subset (odds ratio, 5.01). ET substratification analysis by variant IFNA16 exhibited a statistically significant increase in IFN-α16 levels (P = .002) among 16 quantifiable cytokines. Recombinantly expressed variant IFN-α16 encompassing 3 linked non-synonymous SNVs (E65H95P133) retained comparable antiviral and pSTAT signaling profiles as native IFN-α16 (V65D95A133) or IFN-α2, although both native and variant IFN-α16 showed stage-restricted differences (compared with IFN-α2) of IFN-regulated genes in CD34+-stimulated megakaryocytes. These data implicate IFNA16 (IFN-α16 gene product) as a putative susceptibility locus (driver) within the broader disrupted cytokine network evident in MPNs, and they provide a framework for dissecting functional interactive networks regulating stress or MPN thrombopoiesis.

Interferon-alpha2 treatment of patients with polycythemia vera and related neoplasms favorably impacts deregulation of oxidative stress genes and antioxidative defense mechanisms

Chronic inflammation is considered a major driving force for clonal expansion and evolution in the Philadelphia-negative myeloproliferative neoplasms, which include essential thrombocythemia, polycythemia vera and primary myelofibrosis (MPNs). One of the key mutation drivers is the JAK2V617F mutation, which has been shown to induce the generation of reactive oxygen species (ROS). Using whole blood gene expression profiling, deregulation of several oxidative stress and anti-oxidative defense genes has been identified in MPNs, including significant downregulation of TP53, the NFE2L2 or NRF2 genes. These genes have a major role for maintaining genomic stability, regulation of the oxidative stress response and in modulating migration or retention of hematopoietic stem cells. Therefore, their deregulation might give rise to increasing genomic instability, increased chronic inflammation and disease progression with egress of hematopoietic stem cells from the bone marrow to seed in the spleen, liver and elsewhere. Interferon-alpha2 (rIFNα) is increasingly being recognized as the drug of choice for the treatment of patients with MPNs. Herein, we report the first gene expression profiling study on the impact of rIFNα upon oxidative stress and antioxidative defense genes in patients with MPNs (n = 33), showing that rIFNα downregulates several upregulated oxidative stress genes and upregulates downregulated antioxidative defense genes. Treatment with rIFNα induced upregulation of 19 genes in ET and 29 genes in PV including CXCR4 and TP53. In conclusion, this rIFNα- mediated dampening of genotoxic damage to hematopoietic cells may ultimately diminish the risk of additional mutations and accordingly clonal evolution and disease progression towards myelofibrotic and leukemic transformation.

Megakaryocytes Are Regulators of the Tumor Microenvironment and Malignant Hematopoietic Progenitor Cells in Myelofibrosis

Megakaryocytes (MKs) are multifunctional hematopoietic cells that produce platelets, serve as components of bone marrow (BM) niches that support the development of hematopoietic stem and progenitor cell (HSPC) and provide inflammatory signals. MKs can dynamically change their activities during homeostasis and following stress, thereby regulating hematopoietic stem cell (HSC) function. Myelofibrosis (MF) is a progressive chronic myeloproliferative neoplasm (MPN) characterized by hyperactivation of JAK/STAT signaling and MK hyperplasia, which is associated with an aberrant inflammatory signature. Since JAK1/2 inhibitor alone is incapable of depleting the malignant HSC clones or reversing BM fibrosis, the identification of mechanisms that cooperate with MF JAK/STAT signaling to promote disease progression might help in developing combination therapies to modify disease outcomes. Chronic inflammation and MK hyperplasia result in an abnormal release of TGFβ1, which plays a critical role in the pathobiology of MF by contributing to the development of BM fibrosis. Dysregulated TGFβ signaling can also alter the hematopoietic microenvironment supporting the predominance of MF-HSCs and enhance the quiescence of the reservoir of wild-type HSCs. Upregulation of TGFβ1 levels is a relatively late event in MF, while during the early pre-fibrotic stage of MF the alarmin S100A8/S100A9 heterocomplex promotes pro-inflammatory responses and sustains the progression of MF-HSCs. In this review, we will discuss the recent advances in our understanding of the roles of abnormal megakaryopoiesis, and the altered microenvironment in MF progression and the development of novel combined targeted therapies to disrupt the aberrant interplay between MKs, the BM microenvironment and malignant HSCs which would potentially limit the expansion of MF-HSC clones.

Characterization of disease-propagating stem cells responsible for myeloproliferative neoplasm-blast phase

Chronic myeloproliferative neoplasms (MPN) frequently evolve to a blast phase (BP) that is almost uniformly resistant to induction chemotherapy or hypomethylating agents. We explored the functional properties, genomic architecture, and cell of origin of MPN-BP initiating cells (IC) using a serial NSG mouse xenograft transplantation model. Transplantation of peripheral blood mononuclear cells (MNC) from 7 of 18 patients resulted in a high degree of leukemic cell chimerism and recreated clinical characteristics of human MPN-BP. The function of MPN-BP ICs was not dependent on the presence of JAK2V617F, a driver mutation associated with the initial underlying MPN. By contrast, multiple MPN-BP IC subclones coexisted within MPN-BP MNCs characterized by different myeloid malignancy gene mutations and cytogenetic abnormalities. MPN-BP ICs in 4 patients exhibited extensive proliferative and self-renewal capacity, as demonstrated by their ability to recapitulate human MPN-BP in serial recipients. These MPN-BP IC subclones underwent extensive continuous clonal competition within individual xenografts and across multiple generations, and their subclonal dynamics were consistent with functional evolution of MPN-BP IC. Finally, we show that MPN-BP ICs originate from not only phenotypically identified hematopoietic stem cells, but also lymphoid-myeloid progenitor cells, which were each characterized by differences in MPN-BP initiating activity and self-renewal capacity.

Thromboinflammation in Myeloproliferative Neoplasms (MPN)-A Puzzle Still to Be Solved

Myeloproliferative neoplasms (MPNs), a group of malignant hematological disorders, occur as a consequence of somatic mutations in the hematopoietic stem cell compartment and show excessive accumulation of mature myeloid cells in the blood. A major cause of morbidity and mortality in these patients is the marked prothrombotic state leading to venous and arterial thrombosis, including myocardial infarction (MI), deep vein thrombosis (DVT), and strokes. Additionally, many MPN patients suffer from inflammation-mediated constitutional symptoms, such as fever, night sweats, fatigue, and cachexia. The chronic inflammatory syndrome in MPNs is associated with the up-regulation of various inflammatory cytokines in patients and is involved in the formation of the so-called MPN thromboinflammation. JAK2-V617F, the most prevalent mutation in MPNs, has been shown to activate a number of integrins on mature myeloid cells, including granulocytes and erythrocytes, which increase adhesion and drive venous thrombosis in murine knock-in/out models. This review aims to shed light on the current understanding of thromboinflammation, involvement of neutrophils in the prothrombotic state, plausible molecular mechanisms triggering the process of thrombosis, and potential novel therapeutic targets for developing effective strategies to reduce the MPN disease burden.

Thromboinflammation in Myeloproliferative Neoplasms (MPN)-A Puzzle Still to Be Solved

Myeloproliferative neoplasms (MPNs), a group of malignant hematological disorders, occur as a consequence of somatic mutations in the hematopoietic stem cell compartment and show excessive accumulation of mature myeloid cells in the blood. A major cause of morbidity and mortality in these patients is the marked prothrombotic state leading to venous and arterial thrombosis, including myocardial infarction (MI), deep vein thrombosis (DVT), and strokes. Additionally, many MPN patients suffer from inflammation-mediated constitutional symptoms, such as fever, night sweats, fatigue, and cachexia. The chronic inflammatory syndrome in MPNs is associated with the up-regulation of various inflammatory cytokines in patients and is involved in the formation of the so-called MPN thromboinflammation. JAK2-V617F, the most prevalent mutation in MPNs, has been shown to activate a number of integrins on mature myeloid cells, including granulocytes and erythrocytes, which increase adhesion and drive venous thrombosis in murine knock-in/out models. This review aims to shed light on the current understanding of thromboinflammation, involvement of neutrophils in the prothrombotic state, plausible molecular mechanisms triggering the process of thrombosis, and potential novel therapeutic targets for developing effective strategies to reduce the MPN disease burden.

CCL2 rs1024611Gene Polymorphism in Philadelphia-Negative Myeloproliferative Neoplasms

Introduction: The onset of the Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs) is caused by acquired somatic mutations in target myeloid genes “driver mutations”. The CCL2 gene is overexpressed by non-Hodgkin lymphomas and multiple solid tumors. Aim of the study: to evaluate the possible association of CCL2 rs1024611 SNP and its expression level and the risk of developing Philadelphia-negative MPNs. Patients and methods: A total of 128 newly diagnosed Philadelphia-negative MPN patient and 141 healthy subjects were evaluated for the genotype distribution of CCL2 rs1024611 and CCL2 expression levels. Results: The CCL2 rs1024611 G/G genotype was more frequent and significantly frequent among PMF and Post-PV/ET-MF patients and the mean CCL2 expression levels were significantly higher in PMF and Post-PV/ET-MF compared to the healthy subjects. The CCL2 rs1024611 SNP was significantly correlated to the CCL2 gene expression level and fibrosis grade. ROC analysis for the CCL2 gene expression level that discriminates MF patients from PV + ET patients revealed a sensitivity of 80.43% and a specificity of 73.17% with an AUC of 0.919 (p < 0.001). Conclusion: The CCL2 rs1024611 polymorphism could be an independent risk factor for developing MF (PMF and Post-PV/ET-MF). Moreover, CCL2 gene expression could be potential genetic biomarker of fibrotic progression.

JAK2 Variant Signaling: Genetic, Hematologic and Immune Implication in Chronic Myeloproliferative Neoplasms

The JAK2V617F variant constitutes a genetic alteration of higher frequency in BCR/ABL1 negative chronic myeloproliferative neoplasms, which is caused by a substitution of a G ˃ T at position 1849 and results in the substitution of valine with phenylalanine at codon 617 of the polypeptide chain. Clinical, morphological and molecular genetic features define the diagnosis criteria of polycythemia vera, essential thrombocythemia and primary myelofibrosis. Currently, JAK2V617F is associated with clonal hematopoiesis, genomic instability, dysregulations in hemostasis and immune response. JAK2V617F clones induce an inflammatory immune response and lead to a process of immunothrombosis. Recent research has shown great interest in trying to understand the mechanisms associated with JAK2V617F signaling and activation of cellular and molecular responses that progressively contribute to the development of inflammatory and vascular conditions in association with chronic myeloproliferative neoplasms. Thus, the aim of this review is to describe the main genetic, hematological and immunological findings that are linked to JAK2 variant signaling in chronic myeloproliferative neoplasms.

New Markers of Disease Progression in Myelofibrosis

Primary myelofibrosis (PMF) is a myeloproliferative neoplasm due to the clonal proliferation of a hematopoietic stem cell. The vast majority of patients harbor a somatic gain of function mutation either of JAK2 or MPL or CALR genes in their hematopoietic cells, resulting in the activation of the JAK/STAT pathway. Patients display variable clinical and laboratoristic features, including anemia, thrombocytopenia, splenomegaly, thrombotic complications, systemic symptoms, and curtailed survival due to infections, thrombo-hemorrhagic events, or progression to leukemic transformation. New drugs have been developed in the last decade for the treatment of PMF-associated symptoms; however, the only curative option is currently represented by allogeneic hematopoietic cell transplantation, which can only be offered to a small percentage of patients. Disease prognosis is based at diagnosis on the classical International Prognostic Scoring System (IPSS) and Dynamic-IPSS (during disease course), which comprehend clinical parameters; recently, new prognostic scoring systems, including genetic and molecular parameters, have been proposed as meaningful tools for a better patient stratification. Moreover, new biological markers predicting clinical evolution and patient survival have been associated with the disease. This review summarizes basic concepts of PMF pathogenesis, clinics, and therapy, focusing on classical prognostic scoring systems and new biological markers of the disease.

Anti-inflammatory treatment in MPN: Targeting TNFα-receptor 1 (TNFR1) and TNFR2 in JAK2-V617F induced disease

Inhibition of TNFR2 decreases WBC counts but does not ameliorate hematocrit and splenomegaly in a JAK2-V617F knock-in mouse model.

In a JAK2-V617F knock-in mouse model expressing chimeric TNFR1, anti-human TNFR1 antibody therapy reduces hematocrit and splenomegaly.

Chronic nonresolving inflammatory syndrome is a major disease feature in myeloproliferative neoplasms (MPNs). Systemic inflammation promotes the growth of the JAK2-V617F⁺ hematopoietic stem cell clone and is associated with constitutive symptoms (eg, fever, cachexia, and fatigue). Therefore, it is being discussed whether anti-inflammatory therapy, in addition to the well-established JAK inhibitor therapy, may be beneficial in the control of constitutive symptoms. Moreover, effective control of the inflammatory microenvironment may contribute to prevent transformation into secondary myelofibrosis and acute leukemia. Given the pivotal role of tumor necrosis factor α (TNF-α) in MPN and the distinct roles of TNF-α receptor 1 (TNFR1) and TNFR2 in inflammation, we investigated the therapeutic effects of αTNFR1 and αTNFR2 antibody treatment in MPN-like disease using the JAK2^+/VF knock-in mouse model. Peripheral blood counts, bone marrow/spleen histopathology, and inflammatory cytokine levels in serum were investigated. αTNFR2 antibody treatment decreased white blood cells and modulated the serum levels of several cytokines [CXCL2, CXCL5, interleukin-12(p40)], as well as of macrophage colony-stimulating factor, but they lacked efficacy to ameliorate hematocrit and splenomegaly. αTNFR1 antibody treatment resulted in the mild suppression of elevated hematocrit of −10.7% and attenuated splenomegaly (22% reduction in spleen weight). In conclusion, our studies show that TNFR1 and TNFR2 play different roles in the biology of JAK2-V617F–induced disease that may be of relevance in future therapeutic settings.

Anti-IL-6 cytokine treatment has no impact on elevated hematocrit and splenomegaly in a polycythemia vera mouse model

Somatic mutations in JAK2, MPL and Calreticulin and inflammation play a key role in pathophysiology of chronic myeloproliferative neoplasia (CMN). One of the most prominent cytokines elevated in serum of Polycythemia vera patients is interleukin-6 (IL-6). Currently, it is being discussed whether suppression of inflammation by anti-cytokine approaches as anti-IL-6 treatment may be therapeutically useful in CMN. We here sought to investigate the efficacy of anti-IL-6 treatment on inflammatory cytokines, hematocrit and splenomegaly in CMN like disease. JAK2-V617F knock-in mice (JAK2+/V617F) were treated for three weeks with anti-IL-6 antibody (Ab) or IgG-control. Upon anti-IL-6 Ab treatment, serum levels of CXCL2 and CXCL10 were significantly reduced. In addition, CXCL1, CCL11, M-CSF, G-CSF, IL-17, IL-12p40 and CCL2 were reduced by a factor of 0.3 - 0.8. Partly, this was also achieved by applying high-dose IgG. Hematocrit, erythrocyte and leukocyte counts were elevated in JAK2+/V617F mice but were not reduced by anti-IL6 Ab treatment. In addition, there was no apparent amelioration of splenomegaly and spleen histopathology. In conclusion, anti-IL-6 Ab treatment did not result in improvement of hematological disease parameters but was shown to modulate the serum cytokine signature.

Philadelphia-Negative Chronic Myeloproliferative Neoplasms during the COVID-19 Pandemic: Challenges and Future Scenarios

An outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) started in December 2019 in China and then become pandemic in February 2020. Several publications investigated the possible increased rate of COVID-19 infection in hematological malignancies. Based on the published data, strategies for the management of chronic Philadelphia-negative chronic myeloproliferative neoplasms (MPNs) are provided. The risk of severe COVID-19 seems high in MPN, particularly in patients with essential thrombocythemia, but not negligible in myelofibrosis. MPN patients are at high risk of both thrombotic and hemorrhagic complications and this must be accounted in the case of COVID-19 deciding on a case-by-case basis. There are currently no data to suggest that hydroxyurea or interferon may influence the risk or severity of COVID-19 infection. Conversely, while the immunosuppressive activity of ruxolitinib might pose increased risk of infection, its abrupt discontinuation during COVID-19 syndrome is associated with worse outcome. All MPN patients should receive vaccine against COVID-19; reassuring data are available on efficacy of mRNA vaccines in MPNs.

Targets in MPNs and potential therapeutics

Philadelphia-negative classical Myeloproliferative Neoplasms (MPNs), including Polycythemia Vera (PV), Essential Thrombocythemia (ET) and Primary Myelofibrosis (PMF), are clonal hemopathies that emerge in the hematopoietic stem cell (HSC) compartment. MPN driver mutations are restricted to specific exons (14 and 12) of Janus kinase 2 (JAK2), thrombopoietin receptor (MPL/TPOR) and calreticulin (CALR) genes, are involved directly in clonal myeloproliferation and generate the MPN phenotype. As a result, an increased number of fully functional erythrocytes, platelets and leukocytes is observed in the peripheral blood. Nevertheless, the complexity and heterogeneity of MPN clinical phenotypes cannot be solely explained by the type of driver mutation. Other factors, such as additional somatic mutations affecting epigenetic regulators or spliceosomes components, mutant allele burdens and modifiers of signaling by driver mutants, clonal architecture and the order of mutation acquisition, signaling events that occur downstream of a driver mutation, the presence of specific germ-line variants, the interaction of the neoplastic clone with bone marrow microenvironment and chronic inflammation, all can modulate the disease phenotype, influence the MPN clinical course and therefore, might be useful therapeutic targets.

The Power of Extracellular Vesicles in Myeloproliferative Neoplasms: "Crafting" a Microenvironment That Matters

Myeloproliferative Neoplasms (MPN) are acquired clonal disorders of the hematopoietic stem cells and include Essential Thrombocythemia, Polycythemia Vera and Myelofibrosis. MPN are characterized by mutations in three driver genes (JAK2, CALR and MPL) and by a state of chronic inflammation. Notably, MPN patients experience increased risk of thrombosis, disease progression, second neoplasia and evolution to acute leukemia. Extracellular vesicles (EVs) are a heterogeneous population of microparticles with a role in cell-cell communication. The EV-mediated cross-talk occurs via the trafficking of bioactive molecules such as nucleic acids, proteins, metabolites and lipids. Growing interest is focused on EVs and their potential impact on the regulation of blood cancers. Overall, EVs have been suggested to orchestrate the complex interplay between tumor cells and the microenvironment with a pivotal role in "education" and "crafting" of the microenvironment by regulating angiogenesis, coagulation, immune escape and drug resistance of tumors. This review is focused on the role of EVs in MPN. Specifically, we will provide an overview of recent findings on the involvement of EVs in MPN pathogenesis and discuss opportunities for their potential application as diagnostic and prognostic biomarkers.

The Role of Neutrophilic Granulocytes in Philadelphia Chromosome Negative Myeloproliferative Neoplasms

Philadelphia chromosome negative myeloproliferative neoplasms (MPN) are composed of polycythemia vera (PV), essential thrombocytosis (ET), and primary myelofibrosis (PMF). The clinical picture is determined by constitutional symptoms and complications, including arterial and venous thromboembolic or hemorrhagic events. MPNs are characterized by mutations in JAK2, MPL, or CALR, with additional mutations leading to an expansion of myeloid cell lineages and, in PMF, to marrow fibrosis and cytopenias. Chronic inflammation impacting the initiation and expansion of disease in a major way has been described. Neutrophilic granulocytes play a major role in the pathogenesis of thromboembolic events via the secretion of inflammatory markers, as well as via interaction with thrombocytes and the endothelium. In this review, we discuss the molecular biology underlying myeloproliferative neoplasms and point out the central role of leukocytosis and, specifically, neutrophilic granulocytes in this group of disorders.

Early and late stage MPN patients show distinct gene expression profiles in CD34+ cells

Myeloproliferative neoplasms (MPN), comprising essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF), are hematological disorders of the myeloid lineage characterized by hyperproliferation of mature blood cells. The prediction of the clinical course and progression remains difficult and new therapeutic modalities are required. We conducted a CD34⁺ gene expression study to identify signatures and potential biomarkers in the different MPN subtypes with the aim to improve treatment and prevent the transformation from the rather benign chronic state to a more malignant aggressive state. We report here on a systematic gene expression analysis (GEA) of CD34⁺ peripheral blood or bone marrow cells derived from 30 patients with MPN including all subtypes (ET (n = 6), PV (n = 11), PMF (n = 9), secondary MF (SMF; post-ET-/post-PV-MF; n = 4)) and six healthy donors. GEA revealed a variety of differentially regulated genes in the different MPN subtypes vs. controls, with a higher number in PMF/SMF (200/272 genes) than in ET/PV (132/121). PROGENγ analysis revealed significant induction of TNFα/NF-κB signaling (particularly in SMF) and reduction of estrogen signaling (PMF and SMF). Consistently, inflammatory GO terms were enriched in PMF/SMF, whereas RNA splicing–associated biological processes were downregulated in PMF. Differentially regulated genes that might be utilized as diagnostic/prognostic markers were identified, such as AREG, CYBB, DNTT, TIMD4, VCAM1, and S100 family members (S100A4/8/9/10/12). Additionally, 98 genes (including CLEC1B, CMTM5, CXCL8, DACH1, and RADX) were deregulated solely in SMF and may be used to predict progression from early to late stage MPN.

Phase II study of single-agent nivolumab in patients with myelofibrosis

Dysregulated JAK-STAT signaling in myelofibrosis induces pro-inflammatory cytokines, which suppresses T cell proliferation and differentiation, likely responsible for disease progression. The PD-1 pathway, found to be overexpressed in myeloid malignancies, has gained great interest as a therapeutic target, where a significant unmet need exists for novel therapeutic strategies. Preclinical models showed JAK2 mutant cells had higher expression of PD-L1; furthermore, JAK2 mutant xenografts treated with PD-1 inhibition had prolonged survival and reduction in JAK2 allele burden. We evaluated the efficacy and safety of single-agent nivolumab in 8 adult patients with myelofibrosis. Nivolumab was given at 3 mg/kg every 2 weeks for 8 doses, then every 12 weeks for up to 4 years, or until disease progression or toxicity. The median number of nivolumab doses received was 6 [range, 5-16 doses]. Five patients had stable disease including spleen size, total symptom score, and blood requirements for a median of 3.3 months [range, 2.3-15.2 months]. After a median follow-up of 57 months, two patients were still alive. The median overall survival was 6.1 months [range, 3.2-57.4 months]. Due to failure to meet the predetermined efficacy endpoint, the study was terminated early. Trial registration: Clinical trials.gov NCT: 02,421,354.

Evaluation of the need for cytoreduction and its potential carcinogenicity in children and young adults with myeloproliferative neoplasms

Myeloproliferative neoplasms are rare at a young age, and few reports have described the disease characteristics and outcomes in this group. This study aimed to elucidate the clinical course of essential thrombocythemia (ET) and polycythemia vera (PV) in children and young adults aged <39 years focusing on thromboembolic events (TE) and second primary malignancies (SPMs). A total of 990 patients who were diagnosed from 2008 to 2017 were included by analyzing the Health Insurance Review and Assessment Service database in Korea. The incidence was 2.53 per 1,000,000 for ET (643 patients; 276 male patients; median 31 years) and 1.37 per 1,000,000 for PV (347 patients; 309 male patients; median 32 years). Three ET patients developed secondary acute myelogenous leukemia and three developed secondary myelofibrosis. The 5-year cumulative incidence of TE was 14.2% in ET and 21.3% in PV. Thus, the incidence was higher in PV; in particular, arterial TE (ATE) was evidently higher in PV than in ET. The 5-year cumulative incidence of SPMs was 2.5% in ET and 2.6% in PV. While the use of both aspirin and hydroxyurea reduced the incidence of ATE, hydroxyurea significantly increased the incidence of SPMs. The incidence of ET and PV was very low, and ET was more common than PV in children and young adults. The high incidence of TE in young patients suggests the importance of thrombosis prevention. However, hydroxyurea appears to increase the incidence of SPMs; therefore, the risks and benefits should be considered.

Hydroxycarbamide effects on DNA methylation and gene expression in myeloproliferative neoplasms

Hydroxycarbamide (HC, hydroxyurea) is a cytoreductive drug inducing cell cycle blockade. However, emerging evidence suggests that HC plays a role in the modulation of transcription through the activity of transcription factors and DNA methylation. Examining the global mechanism of action of HC in the context of myeloproliferative neoplasms (MPNs), for which HC is the first-line treatment, will provide a better understanding of its molecular effects. To explore the effects of HC genome-wide, transcriptomic analyses were performed on two clinically relevant cell types at different stages of differentiation treated with HC in a murine MPN model. This study was replicated in MPN patients by profiling genome-wide gene expression and DNA methylation using patient blood samples collected longitudinally, before and following HC exposure. The effects of HC on the transcriptome were not only associated with cell cycle interruption but also with hematopoietic functions. Moreover, a group of genes were restored to normal expression levels in murine hematopoietic stem cells (HSCs) following drug treatment, including the master regulator of hematopoiesis, RUNX1. In humans, HC significantly modifies DNA methylation levels in HSCs at several distal regulatory regions, which we show to be associated with SPI1 binding sites and at the SPI1 locus itself. We have identified novel targets of HC that include pivotal transcription factors involved in hematopoiesis, and for the first time we report abnormal methylation patterns in MPN patients at the master regulator gene SPI1 and its distal binding sites, which HC is able to restore to normal levels.

Inflammation-related genes S100s, RNASE3, and CYBB and risk of leukemic transformation in patients with myelodysplastic syndrome with myelofibrosis

Myelodysplastic syndrome with myelofibrosis (MDS-MF) has been associated with an inferior prognosis compared with MDS without MF. However, MDS-MF is not listed independently as a subtype of MDS, and its clinical and genetic characteristics remain poorly understood. We retrospectively compared 53 patients with MDS-MF (44 MF grade 1/MF₁; 9 MF grade 2-3/MF_2 - 3) and 31 with de novo MDS without MF (MDS). The leukemic transformation risks of both MDS-MF_2 - 3 and MDS-MF₁ were increased compared with the MDS group. To identify the potential mechanisms responsible for the leukemic transformation of MDS-MF, we performed single-cell sequencing for one MDS-MF_2 - 3 patient before and after leukemic transformation to explore the variations in gene expression levels. In addition to upgraded expression levels of acute myeloid leukemia-related genes during leukemic transformation, expression levels of some inflammation-related genes (such as S100s, RNASE3, and CYBB) were also increased, and inflammation-related pathways were up-regulated. These results suggest that inflammation-related genes and pathways may play an important role in the leukemic transformation of MDS-MF.