Monocytosis is an adverse prognostic factor for survival in younger patients with primary myelofibrosis

Progression in Myeloid Neoplasms: Beyond the Myeloblast

Disease progression in myelodysplastic syndromes (MDS), myelodysplastic-myeloproliferative neoplasms (MDS/MPN), and myeloproliferative neoplasms (MPN), altogether referred to as myeloid neoplasms (MN), is a major source of mortality. Apart from transformation to acute myeloid leukemia, the clinical progression of MN is mostly due to the overgrowth of pre-existing hematopoiesis by the MN without an additional transforming event. Still, MN may evolve along other recurrent yet less well-known scenarios: (1) acquisition of MPN features in MDS or (2) MDS features in MPN, (3) progressive myelofibrosis (MF), (4) acquisition of chronic myelomonocytic leukemia (CMML)-like characteristics in MPN or MDS, (5) development of myeloid sarcoma (MS), (6) lymphoblastic (LB) transformation, (7) histiocytic/dendritic outgrowths. These MN-transformation types exhibit a propensity for extramedullary sites (e.g., skin, lymph nodes, liver), highlighting the importance of lesional biopsies in diagnosis. Gain of distinct mutations/mutational patterns seems to be causative or at least accompanying several of the above-mentioned scenarios. MDS developing MPN features often acquire MPN driver mutations (usually JAK2), and MF. Conversely, MPN gaining MDS features develop, e.g., ASXL1, IDH1/2, SF3B1, and/or SRSF2 mutations. Mutations of RAS-genes are often detected in CMML-like MPN progression. MS ex MN is characterized by complex karyotypes, FLT3 and/or NPM1 mutations, and often monoblastic phenotype. MN with LB transformation is associated with secondary genetic events linked to lineage reprogramming leading to the deregulation of ETV6, IKZF1, PAX5, PU.1, and RUNX1. Finally, the acquisition of MAPK-pathway gene mutations may shape MN toward histiocytic differentiation. Awareness of all these less well-known MN-progression types is important to guide optimal individual patient management.

Myelofibrosis and Survival Prognostic Models: A Journey between Past and Future

Among the myeloproliferative diseases, myelofibrosis is a widely heterogeneous entity characterized by a highly variable prognosis. In this context, several prognostic models have been proposed to categorize these patients appropriately. Identifying who deserves more invasive treatments, such as bone marrow transplantation, is a critical clinical need. Age, complete blood count (above all, hemoglobin value), constitutional symptoms, driver mutations, and blast cells have always represented the milestones of the leading models still used worldwide (IPSS, DIPSS, MYSEC-PM). Recently, the advent of new diagnostic techniques (among all, next-generation sequencing) and the extensive use of JAK inhibitor drugs have allowed the development and validation of new models (MIPSS-70 and version 2.0, GIPSS, RR6), which are continuously updated. Finally, the new frontier of artificial intelligence promises to build models capable of drawing an overall survival perspective for each patient. This review aims to collect and summarize the existing standard prognostic models in myelofibrosis and examine the setting where each of these finds its best application.

Advances in myelodysplastic/myeloproliferative neoplasms

The myelodysplastic syndrome/myeloproliferative neoplasms (MDS/MPN) category includes a heterogeneous group of diseases characterized by the co-occurrence of clinical and pathologic features of both myelodysplastic and myeloproliferative neoplasms. The recently published International Consensus Classification of myeloid neoplasms revised the entities included in the MDS/MPN category as well as criteria for their diagnosis. In addition to the presence of one or more increased peripheral blood cell counts as evidence of myeloproliferative features, concomitant cytopenia as evidence of ineffective hematopoiesis is now an explicit requirement to diagnose the diseases included in this category. The increasing availability of modern gene sequencing has allowed better understanding of the biologic characteristics of these myeloid neoplasms. The presence of specific mutations in the appropriate clinicopathologic context is now included in the diagnostic criteria for some of MDS/MPN entities. In this review, we highlight what has changed in the diagnostic criteria of MDS/MPN from the WHO 2016 classification while providing practical guidance in diagnosing these diseases.

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.

Progression in Ph-Chromosome-Negative Myeloproliferative Neoplasms: An Overview on Pathologic Issues and Molecular Determinants

Progression in Ph-chromosome-negative myeloproliferative neoplasms (MPN) develops with variable incidence and time sequence in essential thrombocythemia, polycythemia vera, and primary myelofibrosis. These diseases show different clinic-pathologic features and outcomes despite sharing deregulated JAK/STAT signaling due to mutations in either the Janus kinase 2 or myeloproliferative leukemia or CALReticulin genes, which are the primary drivers of the diseases, as well as defined diagnostic criteria and biomarkers in most cases. Progression is defined by the development or worsening of marrow fibrosis or the progressive increase in the marrow blast percentage. Progression is often related to additional genetic aberrations, although some can already be detected during the chronic phase. Detailed scoring systems for clinical usage that are mostly applied in patients with primary myelofibrosis have been defined, and the most recent ones include cytogenetic and molecular parameters with prognostic significance. Additional different clinic-pathologic changes have been reported that may occur during the course of the disease and that are, at present, classified as WHO-defined types of progression, although they likely represent such an event. The present review is meant to provide an updated overview on progression in Ph-chromosome-negative MPN, with a major focus on the pathologic side.

Progression in Ph-Chromosome-Negative Myeloproliferative Neoplasms: An Overview on Pathologic Issues and Molecular Determinants

Progression in Ph-chromosome-negative myeloproliferative neoplasms (MPN) develops with variable incidence and time sequence in essential thrombocythemia, polycythemia vera, and primary myelofibrosis. These diseases show different clinic-pathologic features and outcomes despite sharing deregulated JAK/STAT signaling due to mutations in either the Janus kinase 2 or myeloproliferative leukemia or CALReticulin genes, which are the primary drivers of the diseases, as well as defined diagnostic criteria and biomarkers in most cases. Progression is defined by the development or worsening of marrow fibrosis or the progressive increase in the marrow blast percentage. Progression is often related to additional genetic aberrations, although some can already be detected during the chronic phase. Detailed scoring systems for clinical usage that are mostly applied in patients with primary myelofibrosis have been defined, and the most recent ones include cytogenetic and molecular parameters with prognostic significance. Additional different clinic-pathologic changes have been reported that may occur during the course of the disease and that are, at present, classified as WHO-defined types of progression, although they likely represent such an event. The present review is meant to provide an updated overview on progression in Ph-chromosome-negative MPN, with a major focus on the pathologic side.

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.

Laboratory Evaluation and Pathological Workup of Neoplastic Monocytosis - Chronic Myelomonocytic Leukemia and Beyond

PURPOSE OF REVIEW

Monocytosis is a distinct but non-specific manifestation of various physiologic and pathologic conditions. Among hematopoietic stem cell neoplasms, depending on the criteria used for disease classification, monocytosis may be a consistent and integral component of diseases such as chronic myelomonocytic leukemia or acute myeloid leukemia with monocytic differentiation, or it may represent an inconsistent finding that often provides a clue to the underlying genetic changes driving the neoplasm. The purpose of this review is to provide the readers with a laboratory-based approach to neoplastic monocytosis.

RECENT FINDINGS

In-depth elucidation of the genomic landscape of myeloid neoplasms within the past few years has broadened our understanding of monocytosis and its implications for diagnosis and prognosis. Genetic findings also shed light on potential disease response - or lack thereof - to various therapeutic agents used in the setting of myeloid neoplasms. In this review, we provide our approach to diagnose neoplastic monocytosis in the context of case-based studies while incorporating the most recent literature on this topic.

Clinical and Molecular Approach to Adult-Onset, Neoplastic Monocytosis

PURPOSE OF REVIEW

In this review, we provide a comprehensive and contemporary understanding of malignant monocytosis and provide a framework by which the appropriate diagnosis with malignant monocytosis can be rendered.

RECENT FINDINGS

Increasing data support the use of molecular data to refine the diagnostic approach to persistent monocytosis. The absence of a TET2, SRSF2, or ASXL1 mutation has ≥ 90% negative predictive value for a diagnosis of CMML. These data may also reliably differentiate chronic myelomonocytic leukemia, the malignancy that is most associated with mature monocytosis, from several other diseases that can be associated with typically a lesser degree of monocytosis. These include acute myelomonocytic leukemia, acute myeloid leukemia with monocytic differentiation, myelodysplastic syndromes, and myeloproliferative neoplasms driven by BCR-ABL1, PDGFRA, PDGFRB, or FGFR1 rearrangements or PCM1-JAK2 fusions among other rarer aberrations. The combination of monocyte partitioning with molecular data in patients with persistent monocytosis may increase the predictive power for the ultimate development of CMM but has not been prospectively validated. Many conditions, both benign and malignant, can be associated with an increase in mature circulating monocytes. After reasonably excluding a secondary or reactive monocytosis, there should be a concern for and investigation of malignant monocytosis, which includes hematopathologic review of blood and marrow tissues, flow cytometric analysis, and cytogenetic and molecular studies to arrive at an appropriate diagnosis.

Accelerated Phase of Myeloproliferative Neoplasms

BACKGROUND

Myeloproliferative neoplasms (MPNs) can transform into blast phase MPN (leukemic transformation; MPN-BP), typically via accelerated phase MPN (MPN-AP), in ∼20-25% of the cases. MPN-AP and MPN-BP are characterized by 10-19% and ≥20% blasts, respectively. MPN-AP/BP portend a dismal prognosis with no established conventional treatment. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the sole modality associated with long-term survival.

SUMMARY

MPN-AP/BP has a markedly different mutational profile from de novo acute myeloid leukemia (AML). In MPN-AP/BP, TP53 and IDH1/2 are more frequent, whereas FLT3 and DNMT3A are rare. Higher incidence of leukemic transformation has been associated with the most aggressive MPN subtype, myelofibrosis (MF); other risk factors for leukemic transformation include rising blast counts above 3-5%, advanced age, severe anemia, thrombocytopenia, leukocytosis, increasing bone marrow fibrosis, type 1 CALR-unmutated status, lack of driver mutations (negative for JAK2, CALR, or MPL genes), adverse cytogenetics, and acquisition of ≥2 high-molecular risk mutations (ASXL1, EZH2, IDH1/2, SRSF2, and U2AF1Q157). The aforementioned factors have been incorporated in several novel prognostic scoring systems for MF. Currently, elderly/unfit patients with MPN-AP/BP are treated with hypomethylating agents with/without ruxolitinib; these regimens appear to confer comparable benefit to intensive chemotherapy but with lower toxicity. Retrospective studies in patients who acquired actionable mutations during MPN-AP/BP showed positive outcomes with targeted AML treatments, such as IDH1/2 inhibitors, and require further evaluation in clinical trials. Key Messages: Therapy for MPN-AP patients represents an unmet medical need. MF patients, in particular, should be appropriately stratified regarding their prognosis and the risk for transformation. Higher-risk patients should be monitored regularly and treated prior to progression to MPN-BP. MPN-AP patients may be treated with hypomethylating agents alone or in combination with ruxolitinib; also, patients can be provided with the option to enroll in rationally designed clinical trials exploring combination regimens, including novel targeted drugs, with an ultimate goal to transition to transplant.

Inflammatory Microenvironment and Specific T Cells in Myeloproliferative Neoplasms: Immunopathogenesis and Novel Immunotherapies

The Philadelphia-negative myeloproliferative neoplasms (MPNs) are malignancies of the hematopoietic stem cell (HSC) arising as a consequence of clonal proliferation driven by somatically acquired driver mutations in discrete genes (JAK2, CALR, MPL). In recent years, along with the advances in molecular characterization, the role of immune dysregulation has been achieving increasing relevance in the pathogenesis and evolution of MPNs. In particular, a growing number of studies have shown that MPNs are often associated with detrimental cytokine milieu, expansion of the monocyte/macrophage compartment and myeloid-derived suppressor cells, as well as altered functions of T cells, dendritic cells and NK cells. Moreover, akin to solid tumors and other hematological malignancies, MPNs are able to evade T cell immune surveillance by engaging the PD-1/PD-L1 axis, whose pharmacological blockade with checkpoint inhibitors can successfully restore effective antitumor responses. A further interesting cue is provided by the recent discovery of the high immunogenic potential of JAK2V617F and CALR exon 9 mutations, that could be harnessed as intriguing targets for innovative adoptive immunotherapies. This review focuses on the recent insights in the immunological dysfunctions contributing to the pathogenesis of MPNs and outlines the potential impact of related immunotherapeutic approaches.

Inflammatory Microenvironment and Specific T Cells in Myeloproliferative Neoplasms: Immunopathogenesis and Novel Immunotherapies

The Philadelphia-negative myeloproliferative neoplasms (MPNs) are malignancies of the hematopoietic stem cell (HSC) arising as a consequence of clonal proliferation driven by somatically acquired driver mutations in discrete genes (JAK2, CALR, MPL). In recent years, along with the advances in molecular characterization, the role of immune dysregulation has been achieving increasing relevance in the pathogenesis and evolution of MPNs. In particular, a growing number of studies have shown that MPNs are often associated with detrimental cytokine milieu, expansion of the monocyte/macrophage compartment and myeloid-derived suppressor cells, as well as altered functions of T cells, dendritic cells and NK cells. Moreover, akin to solid tumors and other hematological malignancies, MPNs are able to evade T cell immune surveillance by engaging the PD-1/PD-L1 axis, whose pharmacological blockade with checkpoint inhibitors can successfully restore effective antitumor responses. A further interesting cue is provided by the recent discovery of the high immunogenic potential of JAK2V617F and CALR exon 9 mutations, that could be harnessed as intriguing targets for innovative adoptive immunotherapies. This review focuses on the recent insights in the immunological dysfunctions contributing to the pathogenesis of MPNs and outlines the potential impact of related immunotherapeutic approaches.

Macrophage frequency in the bone marrow correlates with morphologic subtype of myeloproliferative neoplasm

Bone marrow (BM) fibrosis in myeloproliferative neoplasms (MPNs) is associated with a poor prognosis. The development of myelofibrosis and differentiation of mesenchymal stromal cells to profibrotic myofibroblasts depends on macrophages. Here, we compared macrophage frequencies in BM biopsies of MPN patients and controls (patients with non-neoplastic processes), including primary myelofibrosis (PMF, n = 18), essential thrombocythemia (ET, n = 14), polycythemia vera (PV, n = 12), and Philadelphia chromosome-positive chronic myeloid leukemia (CML, n = 9). In PMF, CD68-positive macrophages were greatly increased compared to CML (p = 0.017) and control BM (p < 0.001). Similar findings were observed by CD163 staining (PMF vs. CML: p = 0.017; PMF vs. control: p < 0.001). Moreover, CD68-positive macrophages were increased in PV compared with ET (p = 0.009) and reactive cases (p < 0.001). PMF had higher frequencies of macrophages than PV (CD68: p < 0.001; CD163: p < 0.001) and ET (CD68: p < 0.001; CD163: p < 0.001). CD163 and CD68 were often co-expressed in macrophages with stellate morphology in Philadelphia chromosome-negative MPN, resulting in a sponge-like reticular network that may be a key regulator of unbalanced hematopoiesis in the BM space and may explain differences in cellularity and clinical course.

Myelomonocytic Skewing In Vitro Discriminates Subgroups of Patients with Myelofibrosis with A Different Phenotype, A Different Mutational Profile and Different Prognosis

Normal hematopoietic function is maintained by a well-controlled balance of myelomonocytic, megaerythroid and lymphoid progenitor cell populations which may be skewed during pathologic conditions. Using semisolid in vitro cultures supporting the growth of myelomonocytic (CFU-GM) and erythroid (BFU-E) colonies, we investigated skewed differentiation towards the myelomonocytic over erythroid commitment in 81 patients with myelofibrosis (MF). MF patients had significantly increased numbers of circulating CFU-GM and BFU-E. Myelomonocytic skewing as indicated by a CFU-GM/BFU-E ratio ≥ 1 was found in 26/81 (32%) MF patients as compared to 1/98 (1%) in normal individuals. Patients with myelomonocytic skewing as compared to patients without skewing had higher white blood cell and blast cell counts, more frequent leukoerythroblastic features, but lower hemoglobin levels and platelet counts. The presence of myelomonocytic skewing was associated with a higher frequency of additional mutations, particularly in genes of the epigenetic and/or splicing machinery, and a significantly shorter survival (46 vs. 138 mo, p < 0.001). The results of this study show that the in vitro detection of myelomonocytic skewing can discriminate subgroups of patients with MF with a different phenotype, a different mutational profile and a different prognosis. Our findings may be important for the understanding and management of MF.

Clinical, Hematologic, Biologic and Molecular Characteristics of Patients with Myeloproliferative Neoplasms and a Chronic Myelomonocytic Leukemia-Like Phenotype

Patients with a myeloproliferative neoplasm (MPN) sometimes show a chronic myelomonocytic leukemia (CMML)-like phenotype but, according to the 2016 WHO classification, a documented history of an MPN excludes the diagnosis of CMML. Forty-one patients with an MPN (35 polycythemia vera (PV), 5 primary myelofibrosis, 1 essential thrombocythemia) and a CMML-like phenotype (MPN/CMML) were comprehensively characterized regarding clinical, hematologic, biologic and molecular features. The white blood cell counts in MPN/CMML patients were not different from CMML patients and PV patients. The hemoglobin values and platelet counts of these patients were higher than in CMML but lower than in PV, respectively. MPN/CMML patients showed myelomonocytic skewing, a typical in vitro feature of CMML but not of PV. The mutational landscape of MPN/CMML was not different from JAK2-mutated CMML. In two MPN/CMML patients, development of a CMML-like phenotype was associated with a decrease in the JAK2 V617F allelic burden. Finally, the prognosis of MPN/CMML (median overall survival (OS) 27 months) was more similar to CMML (JAK2-mutated, 28 months; JAK2-nonmutated 29 months) than to PV (186 months). In conclusion, we show that patients with MPN and a CMML-like phenotype share more characteristics with CMML than with PV, which may be relevant for their classification and clinical management.

Cancer Immune Therapy for Philadelphia Chromosome-Negative Chronic Myeloproliferative Neoplasms

Philadelphia chromosome-negative chronic myeloproliferative neoplasms (MPN) are neoplastic diseases of the hematopoietic stem cells in the bone marrow. MPN are characterized by chronic inflammation and immune dysregulation. Of interest, the potent immunostimulatory cytokine interferon-α has been used to treat MPN for decades. A deeper understanding of the anti-cancer immune response and of the different immune regulatory mechanisms in patients with MPN has paved the way for an increased perception of the potential of cancer immunotherapy in MPN. Therapeutic vaccination targeting the driver mutations in MPN is one recently described potential new treatment modality. Furthermore, T cells can directly react against regulatory immune cells because they recognize proteins like arginase and programmed death ligand 1 (PD-L1). Therapeutic vaccination with arginase or PD-L1 therefore offers a novel way to directly affect immune inhibitory pathways, potentially altering tolerance to tumor antigens like mutant CALR and mutant JAK2. Other therapeutic options that could be used in concert with therapeutic cancer vaccines are immune checkpoint-blocking antibodies and interferon-α. For more advanced MPN, adoptive cellular therapy is a potential option that needs more preclinical investigation. In this review, we summarize current knowledge about the immune system in MPN and discuss the many opportunities for anti-cancer immunotherapy in patients with MPN.

The role of circulating monocytes and JAK inhibition in the infectious-driven inflammatory response of myelofibrosis

Myelofibrosis (MF) is characterized by chronic inflammation and hyper-activation of the JAK-STAT pathway. Infections are one of the main causes of morbidity/mortality. Therapy with Ruxolitinib (RUX), a JAK1/2 inhibitor, may further increase the infectious risk. Monocytes are critical players in inflammation/immunity through cytokine production and release of bioactive extracellular vesicles. However, the functional behavior of MF monocytes, particularly during RUX therapy, is still unclear. In this study, we found that monocytes from JAK2V617F-mutated MF patients show an altered expression of chemokine (CCR2, CXCR3, CCR5) and cytokine (TNF-α-R, IL10-R, IL1β-R, IL6-R) receptors. Furthermore, their ability to produce and secrete free and extracellular vesicles-linked cytokines (IL1β, TNF-α, IL6, IL10) under lipopolysaccharides (LPS) stimulation is severely impaired. Interestingly, monocytes from RUX-treated patients show normal level of chemokine, IL10, IL1β, and IL6 receptors together with a restored ability to produce intracellular and to secrete extracellular vesicles-linked cytokines after LPS stimulation. Conversely, RUX therapy does not normalize TNF-R1/2 receptors expression and the LPS-driven secretion of free pro/anti-inflammatory cytokines. Accordingly, upon LPS stimulation, in vitro RUX treatment of monocytes from MF patients increases their secretion of extracellular vesicles-linked cytokines but inhibits the secretion of free pro/anti-inflammatory cytokines. In conclusion, we demonstrated that in MF the infection-driven response of circulating monocytes is defective. Importantly, RUX promotes their infection-driven cytokine production suggesting that infections following RUX therapy may not be due to monocyte failure. These findings contribute to better interpreting the immune vulnerability of MF and to envisaging strategies to improve the infection-driven immune response.

Treatment of MDS/MPN and the MDS/MPN IWG International Trial: ABNL MARRO

PURPOSE OF REVIEW

MDS/MPNs comprise a group of rare hematologic malignancies that balance features of myeloproliferation and bone marrow failure. Given overlapping clinical features and rarity of incidence, MDS/MPNs have long posed a diagnostic and therapeutic challenge. Herein, we sought to review recent advances in diagnosis and emerging therapeutic strategies and highlight the upcoming ABNL MARRO study which aims to individualize therapy for patients with MDS/MPN.

RECENT FINDINGS

Focused study of molecular mutations in MDS/MPNs has provided improved diagnostic clarity. Specific gene mutation or patterns of mutation have been increasingly described and have helped to distinguish between clinically similar diseases. While the current treatment landscape consists largely of therapies that have been co-opted from related disease, the emergence of prospective clinical trials specifically focused on MDS/MPN and the increased use of targeted agents represent progress for patients with MDS/MPN. An improved understanding of the molecular drivers of myeloid diseases has provided diagnostic clarity and renewed hope of targeted therapies for MDS/MPN patients. The upcoming ABNL MARRO study hopes to leverage this knowledge to match patients with targeted therapeutic options specific to molecular drivers of their disease.

Update on the pathologic diagnosis of chronic myelomonocytic leukemia

The diagnostic criteria for chronic myelomonocytic leukemia were recently revised in the 2016 World Health Organization classification update and include new and revised subtypes. In addition, molecular genetic studies have provided new insights into the prognosis and diagnosis of this myeloid neoplasm. This review summarizes the 2016 changes to the diagnostic criteria, discusses potential future changes that may impact diagnosis and provides an overview of recent advances in the diagnosis and prognosis determination of chronic myelomonocytic leukemia.

Myelofibrosis osteoclasts are clonal and functionally impaired

Bone marrow (BM) sclerosis is commonly found in patients with late-stage myelofibrosis (MF). Because osteoclasts (OCs) and osteoblasts play a key role in bone remodeling, and MF monocytes, the OC precursors, are derived from the neoplastic clone, we wondered whether decreased OC numbers or impairment in their osteolytic function affects the development of osteosclerosis. Analysis of BM biopsies from 50 MF patients showed increased numbers of multinucleated tartrate-resistant acid phosphatase (TRAP)/cathepsin K⁺ OCs expressing phosphorylated Janus kinase 2 (JAK2). Randomly microdissected TRAP⁺ OCs from 16 MF patients harbored JAK2 or calreticulin (CALR) mutations, confirming MF OCs are clonal. To study OC function, CD14⁺ monocytes from MF patients and healthy individuals were cultured and differentiated into OCs. Unlike normal OCs, MF OCs appeared small and round, with few protrusions, and carried the mutations and chromosomal abnormalities of neoplastic clones. In addition, MF OCs lacked F-actin-rich ring-like structures and had fewer nuclei and reduced colocalization signals, compatible with decreased fusion events, and their mineral resorption capacity was significantly reduced, indicating impaired osteolytic function. Taken together, our data suggest that, although the numbers of MF OCs are increased, their impaired osteolytic activity distorts bone remodeling and contributes to the induction of osteosclerosis.

Diagnosis and Treatment of Chronic Myelomonocytic Leukemias in Adults: Recommendations From the European Hematology Association and the European LeukemiaNet

Chronic myelomonocytic leukemia (CMML) is a disease of the elderly, and by far the most frequent overlap myelodysplastic/myeloproliferative neoplasm in adults. Aside from the chronic monocytosis that remains the cornerstone of its diagnosis, the clinical presentation of CMML includes dysplastic features, cytopenias, excess of blasts, or myeloproliferative features including high white blood cell count or splenomegaly. Prognosis is variable, with several prognostic scoring systems reported in recent years, and treatment is poorly defined, with options ranging from watchful waiting to allogeneic stem cell transplantation, which remains the only curative therapy for CMML. Here, we present on behalf of the European Hematology Association and the European LeukemiaNet, evidence- and consensus-based guidelines, established by an international group of experts, from Europe and the United States, for standardized diagnostic and prognostic procedures and for an appropriate choice of therapeutic interventions in adult patients with CMML.

Expression of CD markers in JAK2V617F positive myeloproliferative neoplasms: Prognostic significance

Myeloproliferative neoplasms (MPNs) are clonal stem cell disorders characterized by the presence of JAK2^V617F mutation. Thrombohemorrhagic as well as autoimmune or inflammatory phenomena are common clinical outcomes of these disorders. Recent studies have shown that abnormality in frequency and function of blood cells manifested by an alteration in CD markers' expression patterns play a key role in these complications. So, there may be a relationship between CD markers' expressions and prognosis of JAK2^V617F positive MPNs. Therefore, in this review, we have focused on these abnormalities from the perspective of changing expressions of CD markers and assessment of the relationship between these changes with prognosis of JAK2^V617F positive MPNs. It can be stated that the abnormal expression of a large number of CD markers can be used as a prognostic biomarker for clinical outcomes including thrombohememorrhagic events, as well as autoimmune and leukemic transformation in JAK2^V617F positive MPNs. Considering the possible role of CD markers' expressions in JAK2^V617F MPNs prognosis, further studies are needed to confirm the relationship between the expression of CD markers with prognosis to be able to find an appropriate therapeutic approach via targeting CD markers.

How I treat myelofibrosis after failure of JAK inhibitors

The introduction of JAK inhibitors, leading to regulatory approval of ruxolitinib, represents a major therapeutic advance in myelofibrosis (MF). Most patients experience reduction in splenomegaly and improved quality of life from symptom improvement. It is a paradox, however, that, despite inhibition of signaling downstream of disease-related driver mutations, JAK inhibitor treatment is not associated with consistent molecular or pathologic responses in MF. Furthermore, there are important limitations to JAK inhibitor therapy including development of dose-limiting cytopenias and/or nonhematological toxicities such as neuropathy or opportunistic infections. Over half of the patients discontinue treatment within 3 years of starting treatment. Although data are sparse, clinical outcome after JAK inhibitor "failure" is likely poor; consequently, it is important to understand patterns of failure to select appropriate salvage treatment(s). An algorithmic approach, particularly one that incorporates cytogenetics/molecular data, is most helpful in selecting stem cell transplant candidates. Treatment of transplant-ineligible patients relies on a problem-based approach that includes use of investigational drugs, or consideration of splenectomy or radiotherapy. Data from early phase ruxolitinib combination studies, despite promising preclinical data, have not shown clear benefit over monotherapy thus far. Development of effective treatment strategies for MF patients failing JAK inhibitors remains a major unmet need.

Myeloid neoplasms with features intermediate between primary myelofibrosis and chronic myelomonocytic leukemia

Monocytosis can develop during disease course in primary myelofibrosis simulating that seen in chronic myelomonocytic leukemia, and should not lead to disease reclassification. In contrast, at presentation, rare cases have clinical, morphologic, and molecular genetic features truly intermediate between primary myelofibrosis and chronic myelomonocytic leukemia. The taxonomy and natural history of these diseases are unclear. We identified cases which either: (1) fulfilled the 2008 World Health Organization criteria for primary myelofibrosis but had absolute monocytosis and, when available, chronic myelomonocytic leukemia-related mutations (ASXL1, SRSF2, TET2) or (2) fulfilled criteria of chronic myelomonocytic leukemia but had megakaryocytic proliferation and atypia, marrow fibrosis, and myeloproliferative-type driver mutations (JAK2, MPL, CALR). Patients with established primary myelofibrosis who developed monocytosis and those with chronic myelomonocytic leukemia with marrow fibrosis were excluded. By combining the pathology databases of two large institutions, six eligible cases were identified. Patients were predominantly male and elderly with monocytosis at diagnosis (average 17.5%/2.3 × 10³/μl), organomegaly, primary myelofibrosis-like atypical megakaryocytes admixed with a variable number of chronic myelomonocytic leukemia-like hypolobated forms, variable myelodysplasia, marrow fibrosis and osteosclerosis. All had a normal karyotype and no myelodysplasia-associated cytogenetic abnormalities. Five of the patients in whom a more extensive molecular characterization was performed showed co-mutations involving JAK2 or MPL and ASXL1, SRSF2, TET2, NRAS, and/or KRAS. Disease progression has occurred in all and two have died. Rare patients present with features that overlap between primary myelofibrosis and chronic myelomonocytic leukemia and are thus difficult to classify based on current World Health Organization criteria. Biologically, these cases likely represent primary myelofibrosis with monocytosis, dysplasia, and secondary (non-driver) mutations at presentation. Alternatively, they may represent a true gray zone of neoplasms. Their clinical behavior appears aggressive and innovative therapeutic approaches may be beneficial in this particular subset.

Monocytosis in polycythemia vera: Clinical and molecular correlates

Monocytosis (absolute monocyte count, AMC ≥ 1 × 10⁹ /L) might accompany a spectrum of myeloid neoplasms, other than chronic myelomonocytic leukemia (CMML). In the current study, we examined the prevalence, laboratory and molecular correlates, and prognostic relevance of monocytosis in polycythemia vera (PV). Among 267 consecutive patients with World Health Organization (WHO)-defined PV, 55 (21%) patients displayed an AMC of ≥1 × 10⁹ /L and 18 (7%) an AMC of ≥1.5 × 10⁹ /L. In general, PV patients with monocytosis were significantly older and displayed higher frequencies of leukocytosis (81% vs. 50% at AMC ≥1 × 10⁹ /L) and TET2/SRSF2 mutations (57%/29% vs. 19%/1% at AMC ≥ 1.5 × 10⁹ /L). In univariate analysis, AMC ≥1.5 × 10⁹ /L adversely affected overall (OS; P = .004; HR 2.6, 95% CI 1.4-4.8) and myelofibrosis-free (MFFS; P = .02; HR 4.4, 95% CI 1.3-15.1) survival; during multivariable analysis, significance was borderline sustained for OS (P = .05) and MFFS (P = .06). Other independent risk factors for OS included unfavorable karyotype (P = .02, HR 3.39, 95% CI 1.17-9.79), older age (P < .0001, HR 3.34 95% CI 1.97-5.65), and leukocytosis ≥15 × 10⁹ /L (P = .004, HR 2.04, 95% CI 1.26-3.29). In conclusion, in the current study, we encountered a higher than expected prevalence of monocytosis in patients with PV and the mutation profile and age distribution of PV patients with monocytosis is akin to those of patients with CMML and might partly contribute to their worse prognosis.

CMML: Clinical and molecular aspects

Chronic Myelomonocytic Leukemia is a chronic myeloid neoplasm occurring mostly in the elderly with overlapping features of myelodysplastic syndromes (MDS) and myeloproliferative neoplasms (MPN) characterized by chronic monocytosis. Recent progresses in the molecular and cellular pathogenesis of CMML have stirred a renewed interest in this clinically heterogeneous disorder. Here, we review the recent progresses in the biology of CMML and how it affects its current and future clinical management.

Risk factors for infections in myelofibrosis: role of disease status and treatment. A multicenter study of 507 patients

Although infectious complications represent a relevant cause of morbidity and mortality in patients with myelofibrosis (MF), little is known about their incidence, outcome and risk factors. We retrospectively evaluated a cohort of 507 MF patients, diagnosed between 1980 and 2014 in five Italian hematology centers, to define the epidemiology of infections and describe the impact of ruxolitinib (RUX) treatment. Overall, 112 patients (22%) experienced 160 infectious events (grade 3-4, 45%) for an incidence rate of 3.9% per patient-year. Infections were mainly bacterial (78%) and involving the respiratory tract (52% of cases). Also, viral (11%) and fungal infections (2%) were recorded. Overall, infections were fatal in 9% of the cases. Among baseline features, high/intermediate-2 IPSS category (HR 1.8, 95%CI:1.2-2.7; P = 0.02) and spleen length ≥10 cm below left costal margin (HR 1.6, 95%CI:1.1-2.5; P = 0.04) were associated with higher infectious risk in multivariate analysis. Overall, the rate of infections was higher in the cohort of 128 RUX-treated patients (44% vs. 20%, P < 0.001). In conclusion, IPSS-category and splenomegaly, emerged as the main risk factors for infections in MF. RUX-treated patients experienced significantly more infection episodes; however, future prospective studies are needed to isolate the confounding contribution of other risk factors such as disease stage. Am. J. Hematol. 92:37-41, 2017. © 2016 Wiley Periodicals, Inc.

An accurate, simple prognostic model consisting of age, JAK2, CALR, and MPL mutation status for patients with primary myelofibrosis

In most patients with primary myelofibrosis, one of three mutually exclusive somatic mutations is detected. In approximately 60% of patients, the Janus kinase 2 gene is mutated, in 20%, the calreticulin gene is mutated, and in 5%, the myeloproliferative leukemia virus gene is mutated. Although patients with mutated calreticulin or myeloproliferative leukemia genes have a favorable outcome, and those with none of these mutations have an unfavorable outcome, prognostication based on mutation status is challenging due to the heterogeneous survival of patients with mutated Janus kinase 2. To develop a prognostic model based on mutation status, we screened primary myelofibrosis patients seen at the MD Anderson Cancer Center, Houston, USA, between 2000 and 2013 for the presence of Janus kinase 2, calreticulin, and myeloproliferative leukemia mutations. Of 344 primary myelofibrosis patients, Janus kinase 2^V617F was detected in 226 (66%), calreticulin mutation in 43 (12%), and myeloproliferative leukemia mutation in 16 (5%); 59 patients (17%) were triple-negatives. A 50% cut-off dichotomized Janus kinase 2-mutated patients into those with high Janus kinase 2^V617F allele burden and favorable survival and those with low Janus kinase 2^V617F allele burden and unfavorable survival. Patients with a favorable mutation status (high Janus kinase 2^V617F allele burden/myeloproliferative leukemia/calreticulin mutation) and aged 65 years or under had a median survival of 126 months. Patients with one risk factor (low Janus kinase 2^V617F allele burden/triple-negative or age >65 years) had an intermediate survival duration, and patients aged over 65 years with an adverse mutation status (low Janus kinase 2^V617F allele burden or triple-negative) had a median survival of only 35 months. Our simple and easily applied age- and mutation status-based scoring system accurately predicted the survival of patients with primary myelofibrosis.

Chronic myelomonocytic leukemia: 2016 update on diagnosis, risk stratification, and management

Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic stem cell disorder characterized by overlapping features of myelodysplastic syndromes and myeloproliferative neoplasms. Diagnosis is based on the presence of persistent (>3 months) peripheral blood monocytosis (>1 × 10(9) /L), along with bone marrow dysplasia. Clonal cytogenetic abnormalities occur in ∼20-30% of patients, while >90% have gene mutations. Mutations involving TET2 (∼60%), SRSF2 (∼50%), ASXL1 (∼40%), and RAS (∼30%) are frequent; with only ASXL1 mutations negatively impacting overall survival. Two molecularly integrated, CMML-specific prognostic models include; the Groupe Français des Myélodysplasies (GFM) and the Molecular Mayo Model (MMM). The GFM model segregates patients into 3 groups based on: age >65 years, WBC >15 × 10(9) /L, anemia, platelets <100 × 10(9) /L, and ASXL1 mutation status, with respective median survivals of 56 (low), 27.4 (intermediate), and 9.2 (high) months. The MMM is based on ASXL1 mutational status, absolute monocyte count >10 × 10(9) /L, hemoglobin <10 g/dL, platelets <100 × 109/L and circulating immature myeloid cells. This model stratifies patients into four groups; high (≥3 risk factors), intermediate-2 (2 risk factors), intermediate-1 (1 risk factor) and low (no risk factors), with median survivals of 16, 31, 59, and 97 months, respectively. Hypomethylating agents such as 5-azacitidine and decitabine are commonly used, with overall response rates of ∼30-40% and complete remission rates of ∼7-17%. Allogeneic stem cell transplant is the only potentially curative option, but is associated with significant morbidity and mortality. Individualized therapy, including epigenetic modifiers and small molecule inhibitors, are exciting prospects. Am. J. Hematol. 91:632-642, 2016. © 2016 Wiley Periodicals, Inc.

Chronic Myelomonocytic Leukemia: Focus on Clinical Practice

Chronic myelomonocytic leukemia (CMML) is a clonal stem cell disorder with features that overlap those of myelodysplastic syndromes (MDSs) and myeloproliferative neoplasms (MPNs). Chronic myelomonocytic leukemia often results in peripheral blood monocytosis and has an inherent tendency to transform to acute myeloid leukemia. Clonal cytogenetic changes are seen in approximately 30% of patients, and molecular abnormalities are seen in more than 90%. Gene mutations involving TET2 (∼60%), SRSF2 (∼50%), ASXL1 (∼40%), and RAS (∼30%) are frequent, with nonsense and frameshift ASXL1 mutations being the only mutations identified thus far to have an independent negative prognostic effect on overall survival. Contemporary molecularly integrated prognostic models (inclusive of ASXL1 mutations) include the Molecular Mayo Model and the Groupe Français des Myélodysplasies model. Given the lack of formal treatment and response criteria, management of CMML is often extrapolated from MDS and MPN, with allogeneic stem cell transplant being the only curative option. Hydroxyurea and other cytoreductive agents have been used to control MPN-like features, while epigenetic modifiers such as hypomethylating agents have been used for MDS-like features. Given the relatively poor response to these agents and the inherent risks associated with hematopoietic stem cell transplant, newer drugs exploiting molecular and epigenetic abnormalities in CMML are being developed. The creation of CMML-specific response criteria is a much needed step in order to improve clinical outcomes.

Prognostic value of lymphocyte/monocyte ratio in advanced Hodgkin lymphoma: correlation with International Prognostic Score and tumor associated macrophages

We studied the prognostic significance of the absolute lymphocyte/monocyte count ratio (ALC/AMC), its contribution to the prognostic value of the International Prognostic Score (IPS), and evaluated if ALC/AMC could serve as a proxy for the frequency of CD68 + tumor-associated macrophages (TAMs) in 101 patients with advanced Hodgkin lymphoma (HL). The receiver operating characteristic (ROC) curve identified best cut-off values of 2.0 for ALC/AMC and 25% for CD68 + TAM. Patients with ALC/AMC < 2, IPS > 2 and > 25% CD68 + TAM had an inferior overall survival (OS) and event-free survival (EFS). Spearman's test also uncovered a significant correlation between the ALC/AMC and TAM. Multivariate analysis identified ALC/AMC < 2, IPS > 2 and > 25% CD68 + TAM as poor prognostic factors of OS and EFS. After evaluating ALC/AMC and IPS, we stratified patients into three progressively-worse-outcome groups (low-risk: 0 risk factors; intermediate: 1 risk factor; high: 2 risk factors). Our study encourages the combination of ALC/AMC with IPS, for refining risk prediction in advanced HL patients.

Surveying the landscape of MDS/MPN research: overlap among the overlap syndromes?

The myelodysplastic/myeloproliferative neoplasms (MDS/MPNs) lie at the interphase of phenotypically opposing bone marrow malignancies. They are characterized by concomitant features of bone marrow failure and myeloproliferation and are generally associated with a poor prognosis. Although much is unknown with respect to the clinical course and molecular biology of MDS/MPNs, emerging research is beginning to uncover the key defining characteristics of this designation. In this review, we will discuss the features of MDS/MPN diseases that unify there clinical and molecular course and those that define distinct disease entities. We will discuss advances in genetics and MDS/MPN modeling, as well as translational discoveries that are anticipated to inform the diagnosis, prognostication, and treatment of MDS/MPNs in the near future.

An international consortium proposal of uniform response criteria for myelodysplastic/myeloproliferative neoplasms (MDS/MPN) in adults

Myelodysplastic syndromes (MDS) and myeloproliferative neoplasms (MPN) are hematologically diverse stem cell malignancies sharing phenotypic features of both myelodysplastic syndromes and myeloproliferative neoplasms. There are currently no standard treatment recommendations for most adult patients with MDS/MPN. To optimize efforts to improve the management and disease outcomes, it is essential to identify meaningful clinical and biologic end points and standardized response criteria for clinical trials. The dual dysplastic and proliferative features in these stem cell malignancies define their uniqueness and challenges. We propose response assessment guidelines to harmonize future clinical trials with the principal objective of establishing suitable treatment algorithms. An international panel comprising laboratory and clinical experts in MDS/MPN was established involving 3 independent academic MDS/MPN workshops (March 2013, December 2013, and June 2014). These recommendations are the result of this collaborative project sponsored by the MDS Foundation.

Chronic myelomonocytic leukemia prognostic classification and management: evidence base and current practice

Chronic myelomonocytic leukemia is a clonal malignancy of the ageing hematopoietic stem cell characterized by a biased differentiation leading to persistent monocytosis and inconstant hypersensitivity of myeloid progenitors to granulo-monocyte colony-stimulating factor (GM-CSF). Cytogenetic abnormalities identified in 30-40 % of patients and gene mutations detected in every patient can be used to stratify patients into risk groups that guide the therapeutic choices. TET2, SRSF2, ASXL1, and genes of the Ras pathway are the most frequently mutated genes, with ASXL1 mutations negatively affecting the disease outcome. Allogeneic stem cell transplantation is the first option to consider, especially in younger patients with poor prognostic factors. There is no firm clinical guideline in transplant-ineligible patients, but hypomethylating agents might be an interesting option. A consensus prognostic scoring system and specific response criteria are now required to facilitate the evaluation of new therapeutic strategies in clinical trials specifically dedicated to this disease.

Chronic kidney disease in patients with the Philadelphia-negative chronic myeloproliferative neoplasms

BACKGROUND

The progression of kidney function and frequency of chronic kidney disease (CKD) in patients with the Philadelphia-negative myeloproliferative neoplasms (MPN) is unknown, although CKD is linked to increased mortality.

METHODS

This longitudinal retrospective study evaluates the estimated glomerular filtration rate (eGFR) in 143 MPN patients over a period of 9 years.

RESULTS

29% of patients had CKD stage 3 or 4 at time of diagnosis. 20% of patients had a rapid annual loss of eGFR (>3mL/min/1.73m(2)) and eGFR was negatively correlated to monocyte and neutrophil counts.

CONCLUSION

Kidney impairment might contribute to the increased mortality observed in MPN patients.

[Myeloproliferative neoplasms: histopathological and molecular pathological diagnosis]

Myeloproliferative neoplasms (chronic myeloproliferative disorders according to former nomenclature) comprise chronic myeloid leukemia, polycythemia vera, essential thrombocythemia, primary myelofibrosis, chronic eosinophilic leukemia, chronic neutrophilic leukemia and systemic mastocytosis. All disorders have excessive proliferation of one or more hematopoietic lineages in common and progress with different probability to blast crisis or fibrosis. A further common feature is provided by the activating mutation of tyrosin kinases and associated pathways of signal transduction (BCR-ABL, JAK2(V617F), MPL(W515L/K), KIT(D816V) and FIP1L1-PDGFRA) causative for the abnormal proliferation. With regard to diagnosis and therapy these mutations are of utmost importance because they enable the exclusion of reactive processes, contribute with varying specificity to subtyping of MPN and are at least partly sensitive to targeted therapy. The molecular mechanisms of blastic and fibrotic progression are not yet understood.