Heterogeneity in myeloproliferative neoplasms: Causes and consequences

Exploring hematological alterations and genetics linked to SNV rs10974944 in myeloproliferative neoplasms among Amazon patients

BCR::ABL1-negative myeloproliferative neoplasms are hematopoietic disorders characterized by panmyelosis. JAK2 V617F is a frequent variant in these diseases and often occurs in the 46/1 haplotype. The G allele of rs10974944 has been shown to be associated with this variant, specifically its acquisition, correlations with familial cases, and laboratory alterations. This study evaluated the association between the 46/1 haplotype and JAK2 V617F in patients with myeloproliferative neoplasms in a population from the Brazilian Amazon. Clinical, laboratory and molecular sequencing analyses were considered. Carriers of the G allele of rs10974944 with polycythemia vera showed an increase in mean corpuscular volume and mean corpuscular hemoglobin, while in those with essential thrombocythemia, there was an elevation in red blood cells, hematocrit, and hemoglobin. Associations were observed between rs10974944 and the JAK2 V617F, in which the G allele (OR 3.4; p < 0.0001) and GG genotype (OR 4.9; p = 0.0016) were associated with JAK2 V617F + and an increase in variant allele frequency (GG: OR 15.8; p =  < 0.0001; G: OR 6.0; p = 0.0002). These results suggest an association between rs10974944 (G) and a status for JAK2 V617F, JAK2 V617F + _VAF ≥ 50%, and laboratory alterations in the erythroid lineage.

Clinical Phenotype and Outcomes of Pulmonary Hypertension Associated with Myeloproliferative Neoplasms: A Population-based Study

Rationale: Precapillary pulmonary hypertension (PH) is a rare and largely unrecognized complication of myeloproliferative neoplasms (MPNs), including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (MF). Objectives: To describe characteristics and outcomes of MPN-associated PH. Methods: We report clinical, functional, and hemodynamic characteristics, classification, and outcomes of patients with PV, ET, or primary MF in the French PH registry. Measurements and Main Results: Ninety patients with MPN (42 PV, 35 ET, 13 primary MF) presented with precapillary PH with severe hemodynamic impairment, with a median mean pulmonary arterial pressure and pulmonary vascular resistance of 42 mm Hg and 6.7 Wood units, respectively, and impaired clinical conditions, with 71% in New York Heart Association functional classes III/IV and having a median 6-minute-walk distance of 310 m. Half of the patients were diagnosed with chronic thromboembolic PH (CTEPH); the other half were considered to have group 5 PH. MF was preferentially associated with group 5 PH, whereas PV and ET were generally related to CTEPH. Proximal lesions were diagnosed in half of the patients with CTEPH. Thromboendarterectomy was performed in 18 selected patients with high risk of complications (5 early deaths). Overall survival at 1, 3, and 5 years was 67%, 50%, and 34% in group 5 PH and 81%, 66%, and 42% in CTEPH, respectively. Conclusions: PH is a life-threatening condition potentially occurring in MPN. There are multiple mechanisms, with equal diagnoses of CTEPH and group 5 PH. Physicians should be aware that PH strongly affects the burden of patients with MPN, especially in group 5 PH, with unknown pathophysiological mechanisms.

Additional Genetic Alterations and Clonal Evolution of MPNs with Double Mutations on the MPL Gene: Two Case Reports

Essential thrombocythemia (ET) and primary myelofibrosis (PMF) are two of the main BCR-ABL1-negative chronic myeloproliferative neoplasms (MPNs) characterized by abnormal megakaryocytic proliferation. Janus kinase 2 (JAK2) mutations are detected in 50-60% of ET and PMF, while myeloproliferative leukemia (MPL) virus oncogene mutations are present in 3-5% of cases. While Sanger sequencing is a valuable diagnostic tool to discriminate the most common MPN mutations, next-generation sequencing (NGS) is a more sensitive technology that also identifies concurrent genetic alterations. In this report, we describe two MPN patients with simultaneous double MPL mutations: a woman with ET presenting both MPL^V501A-W515R and JAK2^V617F mutations and a man with PMF displaying an uncommon double MPL^V501A-W515L. Using colony-forming assays and NGS analyses, we define the origin and mutational landscape of these two unusual malignancies and uncover further gene alterations that may contribute to the pathogenesis of ET and PMF.

Applications of Artificial Intelligence in Philadelphia-Negative Myeloproliferative Neoplasms

Philadelphia-negative (Ph-) myeloproliferative neoplasms (MPNs) are a group of hematopoietic malignancies identified by clonal proliferation of blood cell lineages and encompasses polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). The clinical and laboratory features of Philadelphia-negative MPNs are similar, making them difficult to diagnose, especially in the preliminary stages. Because treatment goals and progression risk differ amongst MPNs, accurate classification and prognostication are critical for optimal management. Artificial intelligence (AI) and machine learning (ML) algorithms provide a plethora of possible tools to clinicians in general, and particularly in the field of malignant hematology, to better improve diagnosis, prognosis, therapy planning, and fundamental knowledge. In this review, we summarize the literature discussing the application of AI and ML algorithms in patients with diagnosed or suspected Philadelphia-negative MPNs. A literature search was conducted on PubMed/MEDLINE, Embase, Scopus, and Web of Science databases and yielded 125 studies, out of which 17 studies were included after screening. The included studies demonstrated the potential for the practical use of ML and AI in the diagnosis, prognosis, and genomic landscaping of patients with Philadelphia-negative MPNs.

Continuous Indexing of Fibrosis (CIF): improving the assessment and classification of MPN patients

The grading of fibrosis in myeloproliferative neoplasms (MPN) is an important component of disease classification, prognostication and monitoring. However, current fibrosis grading systems are only semi-quantitative and fail to fully capture sample heterogeneity. To improve the quantitation of reticulin fibrosis, we developed a machine learning approach using bone marrow trephine (BMT) samples (n = 107) from patients diagnosed with MPN or a reactive marrow. The resulting Continuous Indexing of Fibrosis (CIF) enhances the detection and monitoring of fibrosis within BMTs, and aids MPN subtyping. When combined with megakaryocyte feature analysis, CIF discriminates between the frequently challenging differential diagnosis of essential thrombocythemia (ET) and pre-fibrotic myelofibrosis with high predictive accuracy [area under the curve = 0.94]. CIF also shows promise in the identification of MPN patients at risk of disease progression; analysis of samples from 35 patients diagnosed with ET and enrolled in the Primary Thrombocythemia-1 trial identified features predictive of post-ET myelofibrosis (area under the curve = 0.77). In addition to these clinical applications, automated analysis of fibrosis has clear potential to further refine disease classification boundaries and inform future studies of the micro-environmental factors driving disease initiation and progression in MPN and other stem cell disorders.

Single-cell methods in myeloproliferative neoplasms: old questions, new technologies

Myeloproliferative neoplasms (MPN) are a group of clonal stem cell-derived hematopoietic malignancies driven by aberrant Janus kinase-signal transducer and activator of transcription proteins (JAK/STAT) signaling. Although these are genetically simple diseases, MPNs are phenotypically heterogeneous, reflecting underlying intratumoral heterogeneity driven by the interplay of genetic and nongenetic factors. Their evolution is determined by factors that enable certain cellular subsets to outcompete others. Therefore, techniques that resolve cellular heterogeneity at the single-cell level are ideally placed to provide new insights into MPN biology. With these insights comes the potential to uncover new approaches to predict the clinical course and treat these cancers, ultimately improving outcomes for patients. MPNs present a particularly tractable model of cancer evolution, because most patients present in an early disease phase and only a small proportion progress to aggressive disease. Therefore, it is not surprising that many groundbreaking technological advances in single-cell omics have been pioneered by their application in MPNs. In this review article, we explore how single-cell approaches have provided transformative insights into MPN disease biology, which are broadly applicable across human cancers, and discuss how these studies might be swiftly translated into clinical pathways and may eventually underpin precision medicine.

Efficacy and safety of ruxolitinib in patients with myelofibrosis and low platelet count (50 × 109/L to <100 × 109/L) at baseline: the final analysis of EXPAND

Background:

Thrombocytopenia is a common feature of myelofibrosis (MF), a myeloproliferative neoplasm driven by dysregulated JAK/STAT signaling; however, pivotal trials assessing the efficacy of ruxolitinib (a JAK1/2 inhibitor) excluded MF patients with low platelet counts (<100 × 10⁹/L).

Objectives:

Determination of the maximum safe starting dose (MSSD) of ruxolitinib was the primary endpoint, with long-term safety and efficacy as secondary and exploratory endpoints, respectively.

Design:

EXPAND (NCT01317875) was a phase 1b, open-label, ruxolitinib dose-finding study in patients with MF and low platelet counts (50 to <100 × 10⁹/L).

Methods:

Patients were stratified according to baseline platelet count into stratum 1 (S1, 75 to <100 × 10⁹/L) or stratum 2 (S2, 50 to <75 × 10⁹/L). Previous analyses established the MSSD at 10 mg twice daily (bid); long-term results are reported here.

Results:

Of 69 enrolled patients, 38 received ruxolitinib at the MSSD (S1, n = 20; S2, n = 18) and are the focus of this analysis. The incidence of adverse events was consistent with the known safety profile of ruxolitinib, with thrombocytopenia (S1, 50%; S2, 78%) and anemia (S1, 55%; S2, 44%) the most frequently reported adverse events and no new or unexpected safety signals. Substantial clinical benefits were observed for patients in both strata: 50% (10/20) and 67% (12/18) of patients in S1 and S2, respectively, achieved a spleen response (defined as ⩾50% reduction in spleen length from baseline) at any time during the study.

Conclusion:

The final safety and efficacy results from EXPAND support the use of a 10 mg bid starting dose of ruxolitinib in patients with MF and platelet counts 50 to <100 × 10⁹/L.

Registration:

ClinicalTrials.gov NCT01317875.

Expression profiles analysis identifies specific interferon-stimulated signatures as potential diagnostic and predictive indicators of JAK2V617F+ myelofibrosis

Objective: This study aimed to identify specific dysregulated genes with potential diagnostic and predictive values for JAK2V617F⁺ myelofibrosis.

Methods: Two gene expression datasets of CD34⁺ hematopoietic stem and progenitor cells (HSPCs) from patients with JAK2V617F⁺ myeloproliferative neoplasm (MPN) [n = 66, including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF)] and healthy controls (HC) (n = 30) were acquired from the GEO (Gene Expression Omnibus) database. The differentially expressed genes (DEGs) were screened between each JAK2V617F⁺ MPN entity and HC. Subsequently, functional enrichment analyses, including Kyoto Encyclopedia of Genes and Genomes (KEGG), Reactome, and Gene Set Enrichment Analysis (GSEA), were conducted to decipher the important biological effects of DEGs. Protein–protein interaction (PPI) networks of the DEGs were constructed to identify hub genes and significant modules. Another two gene expression profiles of patients with JAK2V617F⁺ MPN [n = 23, including PV, ET, secondary myelofibrosis (SMF), and PMF] and HC (n = 6) from GEO were used as external validation datasets to prove the reliability of the identified signatures.

Results: KEGG analysis revealed the upregulated genes in three JAK2V617F⁺ MPN entities compared with HC were essentially enriched in inflammatory pathways and immune response signaling pathways, and the number of these pathways enriched in PMF was obviously more than that in PV and ET. Following the PPI analysis, 10 genes primarily related to inflammation and immune response were found upregulated in different JAK2V617F⁺ MPN entities. In addition, Reactome enrichment analysis indicated that interferon signaling pathways were enriched specifically in PMF but not in PV or ET. Furthermore, several interferon (IFN)-stimulated genes were identified to be uniquely upregulated in JAK2V617F⁺ PMF. The external datasets validated the upregulation of four interferon-related genes (OAS1, IFITM3, GBP1, and GBP2) in JAK2V617F⁺ myelofibrosis. The receiver operating characteristic (ROC) curves indicate that the four genes have high area under the ROC curve (AUC) values when distinguishing JAK2V617F⁺ myelofibrosis from PV or ET.

Conclusion: Four interferon-stimulated genes (OAS1, IFITM3, GBP1, and GBP2) exclusively upregulated in JAK2V617F⁺ myelofibrosis might have the potential to be the auxiliary molecular diagnostic and predictive indicators of myelofibrosis.

A retrospective real-world study of the current treatment pathways for myelofibrosis in the United Kingdom: the REALISM UK study

Background

Myelofibrosis (MF) is a blood cancer associated with splenomegaly, blood count abnormalities, reduced life expectancy and high prevalence of disease-associated symptoms. Current treatment options for MF are diverse, with limited data on management strategies in real-world practice in the United Kingdom.

Methods

The REALISM UK study was a multi-center, retrospective, non-interventional study, which documented the early management of patients with MF. The primary endpoint was the time from diagnosis to active treatment.

Discussion

Two hundred patients were included (63% [n = 126/200] with primary MF; 37% [n = 74/200] with secondary MF). Symptoms and prognostic scores at diagnosis were poorly documented, with infrequent use of patient reported outcome measures. 'Watch and wait' was the first management strategy for 53.5% (n = 107/200) of patients, while the most commonly used active treatments were hydroxycarbamide and ruxolitinib. Only 5% of patients proceeded to allogeneic transplant. The median (IQR) time to first active treatment was 46 days (0-350); patients with higher risk disease were prescribed active treatment sooner.

Conclusion

These results provide insight into real-world clinical practice for patients with MF in the United Kingdom. Despite the known high prevalence of disease-associated symptoms in MF, symptoms were poorly documented. Most patients were initially observed or received hydroxycarbamide, and ruxolitinib was used as first-line management strategy in only a minority of patients.

Plain Language Summary

Background: Myelofibrosis is a rare blood cancer associated with symptoms that can seriously affect a patient's daily life, such as enlarged spleen and decreased white and red blood cells. Although several treatments are available for patients with myelofibrosis, it is not clear which ones clinicians use most frequently.Methods: We aimed to review which treatments are usually given to patients with myelofibrosis in the UK, by collecting information from the medical records of 200 patients with myelofibrosis treated in different centres across the UK.Results: The results showed that the symptoms patients experienced were not always written down in the medical records. Similarly, clinical scores based on patient characteristics (which clinicians use to try to predict if a patient will respond to treatment well or not) were also missing from the medical records. Clinicians also rarely asked patients to complete questionnaires that try to measure the impact of myelofibrosis and its treatment on their health. The most common approach for patients with myelofibrosis in the UK was 'watch and wait', which over half of patients received. The most common drugs used for treatment were hydroxycarbamide and ruxolitinib; only a very small proportion of patients received a bone marrow transplant. On average, patients waited for 46 days before receiving a treatment, although patients considered to have a more aggressive type of disease received treatment sooner.Conclusion: The results of this study suggest that medical records can be missing key information, which is needed to decide which is the best way to treat a patient with myelofibrosis. They also suggest that clinicians in the UK prefer observation to treatment for a large number of patients with myelofibrosis. This could mean that the approach used for many patients with myelofibrosis does not help them to control symptoms that have an impact on their daily lives.

Thrombosis and hemorrhage in myeloproliferative neoplasms: The platelet perspective

Classical myeloproliferative neoplasm (MPN), also known as BCR-ABL-negative MPN, is a clonal disease characterized by abnormal expansion of hematopoietic stem cells. It has been demonstrated that MPN patients are more susceptible to thrombotic events compared to the general population. Therefore, researchers have been exploring the treatment for MPN thrombosis. However, antithrombotic therapies have brought another concern for the clinical management of MPN because they may cause bleeding events. When thrombosis and bleeding, two seemingly contradictory complications, occur in MPN patients at the same time, they will lead to more serious consequences. Therefore, it is a major challenge to achieving the best antithrombotic effect and minimizing bleeding events simultaneously. To date, there has yet been a perfect strategy to meet this challenge and therefore a new treatment method needs to be established. In this article, we describe the mechanism of thrombosis and bleeding events in MPN from the perspective of platelets for the first time. Based on the double-sided role of platelets in MPN, optimal antithrombotic treatment strategies that can simultaneously control thrombosis and bleeding at the same time may be formulated by adjusting the administration time and dosage of antiplatelet drugs. We argue that more attention should be paid to the critical role of platelets in MPN thrombosis and MPN bleeding in the future, so as to better manage adverse vascular events in MPN.

Myeloproliferative Neoplasms with Monocytosis

PURPOSE OF REVIEW

Myeloproliferative neoplasms (MPN) are a heterogeneous group of hematopoietic stem cell neoplasms comprising of polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) that share driver mutations (JAK2/CALR/MPL) resulting in constitutive activation of JAK/STAT and other signaling pathways. Patients with MPN have shortened survival and an inherent risk for leukemic evolution. Prognostically relevant clinical and genetic parameters have been incorporated into mutation-enhanced scoring systems (MIPSS70-plus version 2.0, MIPSS-ET/PV). In the current review, we describe clinical and pathological features along with prognostic significance of MPN with monocytosis.

RECENT FINDINGS

Monocytosis, defined by an absolute monocyte count (AMC) ≥ 1 × 10 ⁹/L, is a typical manifestation of chronic myelomonocytic leukemia (CMML) but is also associated with 21% and 17% of PV and PMF patients, respectively. Recent studies on the subject have reported that MPN patients with monocytosis are older and present with concomitant leukocytosis. In regard to PV, patients with monocytosis harbor unfavorable cytogenetic abnormalities including +8, 7/7q, i(17q), 5/5q-,12p-, inv(3), or 11q23 rearrangement and SRSF2 mutations, whereas PMF patients with monocytosis had significant thrombocytopenia, higher circulating blasts, higher symptom burden, and ASXL1 mutations. Moreover, presence of monocytosis predicted inferior survival in both PV and PMF. Monocytosis in MPN is associated with a distinct clinical and genetic profile and may serve as a marker of aggressive disease biology.

JAK2 p.(V617F) mutation in Tunisian myeloproliferative neoplasms and its genotype-phenotype correlation

Myeloproliferative neoplasms (MPNs) comprise polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). The relationship between JAK2 p.(V617F) mutation and MPNs was first described in 2005. The purpose of this study was to determine the prevalence of JAK2 p.(V617F) mutation in Tunisian patients assessed for MPNs and try to set a genotype-phenotype correlation. A retrospective study was conducted between January 2015 and April 2019. We collected the clinical data of all patients with MPNs suspicion or atypical splanchnic vein thrombosis (SVT). JAK2 p.(V617F) mutation was detected by allele specific real-time quantitative fluorescence PCR (AS-qPCR). We gathered 974 patients who underwent molecular analysis, 55.5% of them were male and 44.5% were female. The median age of all studied patients was 56 years. JAK2 p.(V617F) was found in 349 (35.8%) of total enrolled cases. It was reported in 44%, 37%, 29% and 25% of all patients diagnosed as having respectively ET, PV, PMF and atypical SVT. JAK2 p.(V617F) was negative in 62.2% of patients addressed for suspicion of PV. There was a significant positive correlation between the JAK2 p.(V617F) mutation status, age, gender, white blood cell counts and platelet counts. To our best knowledge, this is the first vast investigation of JAK2 p.(V617F) variant in Tunisia and North Africa with the lowest mutation rate in entire cohort and MPNs subgroups, underlying a specific presentation of this mutation. It is considered as an essential marker of MPNs’ diagnosis and prognosis and is associated with differences in the phenotype of these disorders, helpful for the follow-up of these patients.

Inflammatory Pathophysiology as a Contributor to Myeloproliferative Neoplasms

Myeloid neoplasms, including acute myeloid leukemia (AML), myeloproliferative neoplasms (MPNs), and myelodysplastic syndromes (MDS), feature clonal dominance and remodeling of the bone marrow niche in a manner that promotes malignant over non-malignant hematopoiesis. This take-over of hematopoiesis by the malignant clone is hypothesized to include hyperactivation of inflammatory signaling and overproduction of inflammatory cytokines. In the Ph-negative MPNs, inflammatory cytokines are considered to be responsible for a highly deleterious pathophysiologic process: the phenotypic transformation of polycythemia vera (PV) or essential thrombocythemia (ET) to secondary myelofibrosis (MF), and the equivalent emergence of primary myelofibrosis (PMF). Bone marrow fibrosis itself is thought to be mediated heavily by the cytokine TGF-β, and possibly other cytokines produced as a result of hyperactivated JAK2 kinase in the malignant clone. MF also features extramedullary hematopoiesis and progression to bone marrow failure, both of which may be mediated in part by responses to cytokines. In MF, elevated levels of individual cytokines in plasma are adverse prognostic indicators: elevated IL-8/CXCL8, in particular, predicts risk of transformation of MF to secondary AML (sAML). Tumor necrosis factor (TNF, also known as TNFα), may underlie malignant clonal dominance, based on results from mouse models. Human PV and ET, as well as MF, harbor overproduction of multiple cytokines, above what is observed in normal aging, which can lead to cellular signaling abnormalities separate from those directly mediated by hyperactivated JAK2 or MPL kinases. Evidence that NFκB pathway signaling is frequently hyperactivated in a pan-hematopoietic pattern in MPNs, including in cells outside the malignant clone, emphasizes that MPNs are pan-hematopoietic diseases, which remodel the bone marrow milieu to favor persistence of the malignancy. Clinical evidence that JAK2 inhibition by ruxolitinib in MF neither reliably reduces malignant clonal burden nor eliminates cytokine elevations, suggests targeting cytokine mediated signaling as a therapeutic strategy, which is being pursued in new clinical trials. Greater knowledge of inflammatory pathophysiology in MPNs can therefore contribute to the development of more effective therapy.

MAPK14 over-expression is a transcriptomic feature of polycythemia vera and correlates with adverse clinical outcomes

Background

The transcriptomic signature has not been fully elucidated in PV, as well as mRNA markers for clinical variables (thrombosis, leukemic transformation, survival, etc.). We attempted to reveal and validate crucial co-expression modules and marker mRNAs correlating with polycythemia vera (PV) by weighted gene co-expression network analysis (WGCNA).

Material and methods

The GSE57793/26014/61629 datasets were downloaded from Gene Expression Omnibus (GEO) database and integrated into one fused dataset. By R software and ‘WGCNA’ package, the PV-specific co-expression module was identified, the pathway enrichment profile of which was obtained by over-representation analysis (ORA). Protein–protein interaction (PPI) network and hub gene analysis identified MAPK14 as our target gene. Then the distribution of MAPK14 expression in different disease/mutation types, were depicted based on external independent datasets. Genome-scale correlation analysis revealed the association of MAPK14 and JAK/STAT family genes. Then gene set enrichment analysis (GSEA) was performed to detect the activated and suppressed pathways associating with MAPK14 expression. Moreover, GSE47018 dataset was utilized to compare clinical variables (thrombosis, leukemic transformation, survival, etc.) between MAPK14-high and MAPK14-low groups.

Results

An integrated dataset including 177 samples (83 PV, 35 ET, 17 PMF and 42 normal donors) were inputted into WGCNA. The ‘tan’ module was identified as the PV-specific module (R² = 0.56, p = 8e−16), the genes of which were dominantly enriched in pro-inflammatory pathways (Toll-like receptor (TLR)/TNF signaling, etc.). MAPK14 is identified as the top hub gene in PV-related PPI network with the highest betweenness. External datasets validated that the MAPK14 expression was significantly higher in PV than that of essential thrombocytosis (ET)/primary myelofibrosis (PMF) patients and normal donors. JAK2 homozygous mutation carriers have higher level of MAPK14 than that of other mutation types. The expression of JAK/STAT family genes significantly correlated with MAPK14, which also contributed to the activation of oxidated phosphorylation, interferon-alpha (IFNα) response and PI3K-Akt-mTOR signaling, etc. Moreover, MAPK14-high group have more adverse clinical outcomes (splenectomy, thrombosis, disease aggressiveness) and inferior survival than MAPK14-low group.

Conclusion

MAPK14 over-expression was identified as a transcriptomic feature of PV, which was also related to inferior clinical outcomes. The results provided novel insights for biomarkers and therapeutic targets for PV.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-02913-3.

Artificial intelligence-based morphological fingerprinting of megakaryocytes: a new tool for assessing disease in MPN patients

Accurate diagnosis and classification of myeloproliferative neoplasms (MPNs) requires integration of clinical, morphological, and genetic findings. Despite major advances in our understanding of the molecular and genetic basis of MPNs, the morphological assessment of bone marrow trephines (BMT) is critical in differentiating MPN subtypes and their reactive mimics. However, morphological assessment is heavily constrained by a reliance on subjective, qualitative, and poorly reproducible criteria. To improve the morphological assessment of MPNs, we have developed a machine learning approach for the automated identification, quantitative analysis, and abstract representation of megakaryocyte features using reactive/nonneoplastic BMT samples (n = 43) and those from patients with established diagnoses of essential thrombocythemia (n = 45), polycythemia vera (n = 18), or myelofibrosis (n = 25). We describe the application of an automated workflow for the identification and delineation of relevant histological features from routinely prepared BMTs. Subsequent analysis enabled the tissue diagnosis of MPN with a high predictive accuracy (area under the curve = 0.95) and revealed clear evidence of the potential to discriminate between important MPN subtypes. Our method of visually representing abstracted megakaryocyte features in the context of analyzed patient cohorts facilitates the interpretation and monitoring of samples in a manner that is beyond conventional approaches. The automated BMT phenotyping approach described here has significant potential as an adjunct to standard genetic and molecular testing in established or suspected MPN patients, either as part of the routine diagnostic pathway or in the assessment of disease progression/response to treatment.

The pathobiology of thrombosis, microvascular disease, and hemorrhage in the myeloproliferative neoplasms

Thrombotic, vascular, and bleeding complications are the most common causes of morbidity and mortality in the Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs). In these disorders, circulating red cells, leukocytes, and platelets, as well as some vascular endothelial cells, each have abnormalities that are cell-intrinsic to the MPN driver mutations they harbor (eg, JAK2 V617F). When these cells are activated in the MPNs, their interactions with each other create a highly proadhesive and prothrombotic milieu in the circulation that predisposes patients with MPN to venous, arterial, and microvascular thrombosis and occlusive disease. Bleeding problems in the MPNs are caused by the MPN blood cell-initiated development of acquired von Willebrand disease. The inflammatory state created by MPN stem cells in their microenvironment extends systemically to amplify the clinical thrombotic tendency and, at the same time, preferentially promote further MPN stem cell clonal expansion, thereby generating a vicious cycle that favors a prothrombotic state in these diseases.

Current Methods of Post-Translational Modification Analysis and Their Applications in Blood Cancers

Post-translational modifications (PTMs) add a layer of complexity to the proteome through the addition of biochemical moieties to specific residues of proteins, altering their structure, function and/or localization. Mass spectrometry (MS)-based techniques are at the forefront of PTM analysis due to their ability to detect large numbers of modified proteins with a high level of sensitivity and specificity. The low stoichiometry of modified peptides means fractionation and enrichment techniques are often performed prior to MS to improve detection yields. Immuno-based techniques remain popular, with improvements in the quality of commercially available modification-specific antibodies facilitating the detection of modified proteins with high affinity. PTM-focused studies on blood cancers have provided information on altered cellular processes, including cell signaling, apoptosis and transcriptional regulation, that contribute to the malignant phenotype. Furthermore, the mechanism of action of many blood cancer therapies, such as kinase inhibitors, involves inhibiting or modulating protein modifications. Continued optimization of protocols and techniques for PTM analysis in blood cancer will undoubtedly lead to novel insights into mechanisms of malignant transformation, proliferation, and survival, in addition to the identification of novel biomarkers and therapeutic targets. This review discusses techniques used for PTM analysis and their applications in blood cancer research.

Application of Single-Cell Approaches to Study Myeloproliferative Neoplasm Biology

Philadelphia-negative myeloproliferative neoplasms (MPNs) are an excellent tractable disease model of a number of aspects of human cancer biology, including genetic evolution, tissue-associated fibrosis, and cancer stem cells. In this review, we discuss recent insights into MPN biology gained from the application of a number of new single-cell technologies to study human disease, with a specific focus on single-cell genomics, single-cell transcriptomics, and digital pathology.

A Broad Overview of Signaling in Ph-Negative Classic Myeloproliferative Neoplasms

Simple Summary

There is growing evidence that Ph-negative myeloproliferative neoplasms are disorders in which multiple signaling pathways are significantly disturbed. The heterogeneous phenotypes observed among patients have highlighted the importance of having a comprehensive knowledge of the molecular mechanisms behind these diseases. This review aims to show a broad overview of the signaling involved in myeloproliferative neoplasms (MPNs) and other processes that can modify them, which could be helpful to better understand these diseases and develop more effective targeted treatments.

Abstract

Ph-negative myeloproliferative neoplasms (polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF)) are infrequent blood cancers characterized by signaling aberrations. Shortly after the discovery of the somatic mutations in JAK2, MPL, and CALR that cause these diseases, researchers extensively studied the aberrant functions of their mutant products. In all three cases, the main pathogenic mechanism appears to be the constitutive activation of JAK2/STAT signaling and JAK2-related pathways (MAPK/ERK, PI3K/AKT). However, some other non-canonical aberrant mechanisms derived from mutant JAK2 and CALR have also been described. Moreover, additional somatic mutations have been identified in other genes that affect epigenetic regulation, tumor suppression, transcription regulation, splicing and other signaling pathways, leading to the modification of some disease features and adding a layer of complexity to their molecular pathogenesis. All of these factors have highlighted the wide variety of cellular processes and pathways involved in the pathogenesis of MPNs. This review presents an overview of the complex signaling behind these diseases which could explain, at least in part, their phenotypic heterogeneity.

Single-cell sequencing in hematology

PURPOSE OF REVIEW

In this review, we highlight key recent insights into hematopoiesis and hematological malignancies through the application of novel single-cell approaches. We particularly focus on biological insights made through the study of stem/progenitors cells in myeloid malignancy at single-cell resolution.

RECENT FINDINGS

Bulk molecular profiling of hematological malignancies by next generation sequencing techniques has provided major insights into the molecular pathogenesis of blood cancers. This technology is now routinely implemented in advanced clinical diagnostics, leading to the development of novel targeted therapies. However, bulk genetic analysis can obscure key aspects of intratumoral heterogeneity which underlies critical disease events, such as treatment resistance and clonal evolution. The past few years have seen an explosion of novel techniques to analyze RNA, DNA, and protein expression at the single-cell level, providing unprecedented insight into cellular heterogeneity.

SUMMARY

Given the ease of accessibility of liquid tumor biopsies, hematology is well positioned to move novel single-cell techniques towards routine application in the clinic. The present review sets out to discuss current and potential future applications for this technology in the management of patients with hematological cancers.

Modification of the Histone Landscape with JAK Inhibition in Myeloproliferative Neoplasms

Dysregulation of epigenetic processes is increasingly understood to play a role in the pathogenesis of myeloproliferative neoplasms (MPNs). Ruxolitinib, a JAK/STAT inhibitor, has proved a useful addition to the therapeutic arsenal for these disorders, but has limited disease modifying activity. We determined the effect of JAK inhibition on the histone landscape of MPN cells in cell line models of MPNs and validated using samples from the MAJIC randomised clinical trial of ruxolitinib in polycythaemia vera and essential thrombocythaemia. We demonstrated an epigenetic modifying effect of ruxolitinib using a histone modification assay. The majority of 21 histone H3 modifications were upregulated, with H3K27me3 and H3K36me2 significant in the combined cell line results. Chromatin immunoprecipitation and sequencing (CHIP-seq) for three marks of interest, H3K4me1, H3K4me3 and H3K27ac, was consistent with the histone modification assay showing a significant increase in H3K4me3 and H3K27ac peaks at promoter regions, both marks of active transcription. In contrast, RNA sequencing demonstrates a coordinated reduction in gene expression in a number of cell pathways including PI3K-AKT signalling, transcriptional misregulation in cancer and JAK-STAT signalling in spite of these histone changes. This highlights the complex mechanisms of transcriptional control within the cells which was reflected in analysis of the histone landscape in patient samples following ruxolitinib treatment.

Physiologically based pharmacokinetic modeling to assess metabolic drug-drug interaction risks and inform the drug label for fedratinib

Purpose

Fedratinib (INREBIC^®), a Janus kinase 2 inhibitor, is approved in the United States to treat patients with myelofibrosis. Fedratinib is not only a substrate of cytochrome P450 (CYP) enzymes, but also exhibits complex auto-inhibition, time-dependent inhibition, or mixed inhibition/induction of CYP enzymes including CYP3A. Therefore, a mechanistic modeling approach was used to characterize pharmacokinetic (PK) properties and assess drug–drug interaction (DDI) potentials for fedratinib under clinical scenarios.

Methods

The physiologically based pharmacokinetic (PBPK) model of fedratinib was constructed in Simcyp^® (V17R1) by integrating available in vitro and in vivo information and was further parameterized and validated by using clinical PK data.

Results

The validated PBPK model was applied to predict DDIs between fedratinib and CYP modulators or substrates. The model simulations indicated that the fedratinib-as-victim DDI extent in terms of geometric mean area under curve (AUC) at steady state is about twofold or 1.2-fold when strong or moderate CYP3A4 inhibitors, respectively, are co-administered with repeated doses of fedratinib. In addition, the PBPK model successfully captured the perpetrator DDI effect of fedratinib on a sensitive CY3A4 substrate midazolam and predicted minor effects of fedratinib on CYP2C8/9 substrates.

Conclusions

The PBPK-DDI model of fedratinib facilitated drug development by identifying DDI potential, optimizing clinical study designs, supporting waivers for clinical studies, and informing drug label claims. Fedratinib dose should be reduced to 200 mg QD when a strong CYP3A4 inhibitor is co-administered and then re-escalated to 400 mg in a stepwise manner as tolerated after the strong CYP3A4 inhibitor is discontinued.

Electronic supplementary material

The online version of this article (10.1007/s00280-020-04131-y) contains supplementary material, which is available to authorized users.

Genomic heterogeneity in myeloproliferative neoplasms and applications to clinical practice

The myeloproliferative neoplasms (MPN) polycythaemia vera, essential thrombocythaemia and primary myelofibrosis are chronic myeloid disorders associated most often with mutations in JAK2, MPL and CALR, and in some patients with additional acquired genomic lesions. Whilst the molecular mechanisms downstream of these mutations are now clearer, it is apparent that clinical phenotype in MPN is a product of complex interactions, acting between individual mutations, between disease subclones, and between the tumour and background host factors. In this review we first discuss MPN phenotypic driver mutations and the factors that interact with them to influence phenotype. We consider the importance of ongoing studies of clonal haematopoiesis, which may inform a better understanding of why MPN develop in specific individuals. We then consider how best to deploy genomic testing in a clinical environment and the challenges as well as opportunities that may arise from more routine, comprehensive genomic analysis of patients with MPN.

Myeloproliferative Diseases as Possible Risk Factor for Development of Chronic Thromboembolic Pulmonary Hypertension-A Genetic Study

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare disease which is often caused by recurrent emboli. These are also frequently found in patients with myeloproliferative diseases. While myeloproliferative diseases can be caused by gene defects, the genetic predisposition to CTEPH is largely unexplored. Therefore, the objective of this study was to analyse these genes and further genes involved in pulmonary hypertension in CTEPH patients. A systematic screening was conducted for pathogenic variants using a gene panel based on next generation sequencing. CTEPH was diagnosed according to current guidelines. In this study, out of 40 CTEPH patients 4 (10%) carried pathogenic variants. One patient had a nonsense variant (c.2071A>T p.Lys691*) in the BMPR2 gene and three further patients carried the same pathogenic variant (missense variant, c.1849G>T p.Val617Phe) in the Janus kinase 2 (JAK2) gene. The latter led to a myeloproliferative disease in each patient. The prevalence of this JAK2 variant was significantly higher than expected (p < 0.0001). CTEPH patients may have a genetic predisposition more often than previously thought. The predisposition for myeloproliferative diseases could be an additional risk factor for CTEPH development. Thus, clinical screening for myeloproliferative diseases and genetic testing may be considered also for CTEPH patients.

Increased von Willebrand factor levels in polycythemia vera and phenotypic differences with essential thrombocythemia

BACKGROUND

Acquired von Willebrand factor (VWF) deficiency was described in Philadelphia-negative myeloproliferative neoplasms, especially in essential thrombocythemia (ET). VWF phenotype in contemporary patients with polycythemia vera (PV) remains less explored.

OBJECTIVES

To characterize the VWF phenotype in PV and to compare VWF phenotype in PV with matched healthy subjects and ET patients.

PATIENTS/METHODS

We studied 48 PV patients, treated according to current recommendations (hematocrit ≤ 45%, on low-dose aspirin prophylaxis); 48 healthy and 41 subjects with ET, all sex, age, and blood group matched. We measured VWF antigen, activity, multimeric pattern, ADAMTS-13, and factor VIII (FVIII) antigen.

RESULTS

In patients with PV, VWF antigen and activity were significantly higher than in healthy subjects (antigen: 119[96-137] vs 93[79-107] IU/dL; activity: 114[95-128] vs 90[79-107] IU/dL, respectively, medians and interquartile, P < 0.01), with normal multimeric distribution. ADAMTS-13 levels were similar between patients with PV and healthy subjects. FVIII levels were higher in PV than in healthy subjects (141[119-169] versus 98[88-123] IU/dL, respectively, P < 0.01). By multivariable analysis, JAK2-p.V617F allelic burden, erythrocyte count, and male sex significantly predicted VWF antigen and activity levels. As compared to patients with ET, patients with PV showed similar VWF antigen levels but approximately 40% higher activity (79[49-104] vs 112[93-125] IU/dL, respectively, P < 0.01).

CONCLUSIONS

Patients with PV show increased VWF and FVIII levels, predicted by JAK2-p.V617F burden and erythrocyte count. At variance with ET, acquired VWF defect was not observed in PV. High VWF/FVIII levels may sustain the thrombotic diathesis of PV and may be investigated as biomarkers for risk stratification.

Janus Kinase V617F Mutation Detection in Patients with Myelofibrosis

Myelofibrosis (MF) is characterized by a presence of an extra fibrous tissue in the bone marrow and additional hematopoiesis. The somatic mutation in the Janus kinase 2 (JAK2) gene (V617F) occurs gradually and is detected in about 50.0% of myelofibrosis or essential thrombo-cytopenia (ET) patients. Our aim was to determine the genotype status according to the carriers of the V617F mutation in patients with MF at the Hematology Ward of the University Hospital "Ivan Rilski" in Sofia, Bulgaria. DNA samples were isolated from venous blood of patients with various hematological disorders. DNA was amplified by polymerase chain reaction (PCR) and subsequent restriction analysis was performed using a BsaXI restriction enzyme. The genotype status was determined on 2.0% agarose gel. We analyzed 38 patients initially suspected of carrying MF or osteomyelofibrosis (OMF). After trepanobiopsy, 20 out of 38 patients were confirmed as myelofibrotic (52.6%), 5/38 (13.2%) were diagnosed as ET, 1/38 (2.6%) was diagnosed as myeloproliferative neoplasm (MPN), 6/38 (15.8%) had polycythemia vera (PV). In six patients, the presence of disease was rejected. Patients with MF were divided into three groups according to the JAK2 V617F genotype status: homozygous for the mutation (3/20 or 15.0%), heterozygous (9/20 or 45.0%) and homozygous for the wild type allele (8/20 or 40.0%). The triggering factor of MF is still unknown. It was considered that this factor could have a genetic nature. Mutations in three genes were mainly accepted as an actual predisposing events to this disease: point mutations leading to amino acid substitutions in JAK2 (V617F) and in MPL (W515L, W515K), as well as insertion or deletion in CALK We have proven that carriers of the V617F mutation prevailed in the group of patients with MF (altogether 12 patients or 60.0%). Previous studies also showed that JAK2 V617F is present in more than half of MF patients within their blood-forming cells. Therefore, the risk of evolution to MF could be associated with V617F-mutant allele burden in patients with MPN.

Population pharmacokinetics of fedratinib in patients with myelofibrosis, polycythemia vera, and essential thrombocythemia

PURPOSE

Fedratinib (SAR302503, TG101348) is an orally administered Janus kinase (JAK) 2-selective inhibitor that is being developed for the treatment of patients with myelofibrosis (MF). The objectives of this analysis were to develop a population pharmacokinetic (PK) model to characterize fedratinib concentration-time profiles in patients with MF, polycythemia vera (PV) and essential thrombocythemia (ET) following oral fedratinib administration; and to investigate the effects of selected covariates on fedratinib PK parameters.

METHODS

Nonlinear mixed effects modeling was employed in developing a population PK model for fedratinib. Intensive or sparse fedratinib concentration data collected in adult subjects with MF, PV or ET from six studies were pooled, and a total of 452 subjects and 3442 plasma concentration observations were included in the final model.

RESULTS

Fedratinib PK in patients with MF/PV/ET was adequately described by a two-compartment structural PK model with first-order absorption incorporating a lag time and first-order elimination. Following oral administration, fedratinib undergoes biphasic disposition and exhibits linear, time-invariant PK at doses of 200 mg and above. Compared to MF/ET patients, PV patients had higher apparent clearance (CL/F) and apparent central volume of distribution. Creatinine clearance was a statistically significant covariate on CL/F, and patients with mild and moderate renal impairment had 10% and 37% increases in fedratinib exposure as compared to patients with normal renal function. No clinically meaningful effect on fedratinib exposure was observed regarding age, body weight, sex, race and liver function.

CONCLUSIONS

These results should serve as the basis for dose adjustment of fedratinib for special populations.

Integrative Approaches to Managing Myeloproliferative Neoplasms: the Role of Nutrition, Exercise, and Psychological Interventions

PURPOSE OF REVIEW

Myeloproliferative neoplasms (MPNs) have a high symptom burden that affects functional status, emotional well-being, and quality of life for patients. Symptom control continues to be a challenging therapeutic goal despite available pharmacologic interventions. The goal of this review is to detail recent efforts that have focused on non-pharmacologic interventions, such as wholistic or integrative medicine, as an adjunctive method to alter symptom burden in this population.

RECENT FINDINGS

We discuss the ongoing physical, nutritional, and psychological interventional efforts which represent promising non-traditional interventions to date to help reduce symptom in MPN patients. In this article, we highlight the early promising data and importance of these various non-pharmacological interventions to dampen symptom burden and reduce disease-related inflammation. Nonpharmacologic interventions represent promising therapeutic strategies to alter traditional MPN treatment paradigms and improve MPN patient care.