Revised cytogenetic risk stratification in primary myelofibrosis: analysis based on 1002 informative patients

Trisomy 8 Defines a Distinct Subtype of Myeloproliferative Neoplasms Driven by the MYC-Alarmin Axis

Despite advances in understanding the genetic abnormalities in myeloproliferative neoplasms (MPN) and the development of JAK2 inhibitors, there is an urgent need to devise new treatment strategies, particularly for patients with triple-negative (TN) myelofibrosis (MF) who lack mutations in the JAK2 kinase pathway and have very poor clinical outcomes. Here we report that MYC copy number gain and increased MYC expression frequently occur in TN-MF and that MYC-directed activation of S100A9, an alarmin protein that plays pivotal roles in inflammation and innate immunity, is necessary and sufficient to drive development and progression of MF. Notably, the MYC-S100A9 circuit provokes a complex network of inflammatory signaling that involves numerous hematopoietic cell types in the bone marrow microenvironment. Accordingly, genetic ablation of S100A9 or treatment with small molecules targeting the MYC-S100A9 pathway effectively ameliorates MF phenotypes, highlighting the MYC-alarmin axis as a novel therapeutic vulnerability for this subgroup of MPNs. Significance: This study establishes that MYC expression is increased in TN-MPNs via trisomy 8, that a MYC-S100A9 circuit manifest in these cases is sufficient to provoke myelofibrosis and inflammation in diverse hematopoietic cell types in the BM niche, and that the MYC-S100A9 circuit is targetable in TN-MPNs.

Myelofibrosis and allogeneic transplantation: critical points and challenges

New available drugs allow better control of systemic symptoms associated with myelofibrosis (MF) and splenomegaly but they do not modify the natural history of progressive and poor prognosis disease. Thus, hematopoietic stem cell transplantation (HSCT) is still considered the only available curative treatment for patients with MF. Despite the increasing number of procedures worldwide in recent years, HSCT for MF patients remains challenging. An increasingly complex network of the patient, disease, and transplant-related factors should be considered to understand the need for and the benefits of the procedure. Unfortunately, prospective trials are often lacking in this setting, making an evidence-based decision process particularly arduous. In the present review, we will analyze the main controversial points of allogeneic transplantation in MF, that is, the development of more sophisticated models for the identification of eligible patients; the need for tools offering a more precise definition of expected outcomes combining comorbidity assessment and factors related to the procedure; the decision-making process about the best transplantation time; the evaluation of the most appropriate platform for curative treatment; the impact of splenomegaly; and splenectomy on outcomes.

Genetic alterations in myeloproliferative and myelodysplastic/myeloproliferative neoplasms - a practical guide to WHO-HAEM5

Within the World Health Organization (WHO) classification of haematopoietic neoplasms, particularly its fifth version from 2022 (WHO-HAEM5), myeloid neoplasms are not only grouped into myeloproliferative (MPN) and myelodysplastic neoplasms (MDS). There is also a group of haematological disorders that share features of both categories termed myelodysplastic /myeloproliferative neoplasms (MDS/MPN). In this article, we aim to provide a comprehensive and practical guide to WHO-HAEM5 highlighting the genetic alterations that underlie MPN and MDS/MPN. This guide provides an overview of the overlapping commonalities among these entities, as well as their unique characteristics.

Calreticulin and JAK2V617F driver mutations induce distinct mitotic defects in myeloproliferative neoplasms

Myeloproliferative neoplasms (MPNs) encompass a diverse group of hematologic disorders driven by mutations in JAK2, CALR, or MPL. The prevailing working model explaining how these driver mutations induce different disease phenotypes is based on the decisive influence of the cellular microenvironment and the acquisition of additional mutations. Here, we report increased levels of chromatin segregation errors in hematopoietic cells stably expressing CALRdel52 or JAK2V617F mutations. Our investigations employing murine 32DMPL and human erythroleukemic TF-1MPL cells demonstrate a link between CALRdel52 or JAK2V617F expression and a compromised spindle assembly checkpoint (SAC), a phenomenon contributing to error-prone mitosis. This defective SAC is associated with imbalances in the recruitment of SAC factors to mitotic kinetochores upon CALRdel52 or JAK2V617F expression. We show that JAK2 mutant CD34 + MPN patient-derived cells exhibit reduced expression of the master mitotic regulators PLK1, aurora kinase B, and PP2A catalytic subunit. Furthermore, the expression profile of mitotic regulators in CD34 + patient-derived cells allows to faithfully distinguish patients from healthy controls, as well as to differentiate primary and secondary myelofibrosis from essential thrombocythemia and polycythemia vera. Altogether, our data suggest alterations in mitotic regulation as a potential driver in the pathogenesis in MPN.

Indication and management of allogeneic haematopoietic stem-cell transplantation in myelofibrosis: updated recommendations by the EBMT/ELN International Working Group

New options for medical therapy and risk scoring systems containing molecular data are leading to increased complexity in the management of patients with myelofibrosis. To inform patients' optimal care, we updated the 2015 guidelines on indications for and management of allogeneic haematopoietic stem-cell transplantation (HSCT) with the support of the European Society for Blood and Marrow Transplantation (EBMT) and European LeukemiaNet (ELN). New recommendations were produced using a consensus-building methodology after a comprehensive review of articles released from January, 2015 to December, 2022. Seven domains and 18 key questions were selected through a series of questionnaires using a Delphi process. Key recommendations in this update include: patients with primary myelofibrosis and an intermediate-2 or high-risk Dynamic International Prognostic Scoring System score, or a high-risk Mutation-Enhanced International Prognostic Score Systems (MIPSS70 or MIPSS70-plus) score, or a low-risk or intermediate-risk Myelofibrosis Transplant Scoring System score should be considered candidates for allogeneic HSCT. All patients who are candidates for allogeneic HSCT with splenomegaly greater than 5 cm below the left costal margin or splenomegaly-related symptoms should receive a spleen-directed treatment, ideally with a JAK-inhibitor; HLA-matched sibling donors remain the preferred donor source to date. Reduced intensity conditioning and myeloablative conditioning are both valid options for patients with myelofibrosis. Regular post-transplantation driver mutation monitoring is recommended to detect and treat early relapse with donor lymphocyte infusion. In a disease where evidence-based guidance is scarce, these recommendations might help clinicians and patients in shared decision making.

Leukemic conversion involving RAS mutations of type 1 CALR-mutated primary myelofibrosis in a patient treated for HCV cirrhosis: a case report

Somatic frameshift mutations in exon 9 of calreticulin (CALR) gene are recognized as disease drivers in primary myelofibrosis (PMF), one of the three classical Philadelphia-negative myeloproliferative neoplasms (MPNs). Type 1/type 1-like CALR mutations particularly confer a favorable prognostic and survival advantage in PMF patients. We report an unusual case of PMF incidentally diagnosed in a 68-year-old woman known with hepatitis C virus (HCV) cirrhosis who developed a progressive painful splenomegaly, without anomalies in blood cell counts. While harboring a type 1 CALR mutation, the patient underwent a leukemic transformation in less than 1 year from diagnosis, with a lethal outcome. Analysis of paired DNA samples from chronic and leukemic phases by a targeted next-generation sequencing (NGS) panel and single-nucleotide polymorphism (SNP) microarray revealed that the leukemic clone developed from the CALR-mutated clone through the acquisition of genetic events in the RAS signaling pathway: an increased variant allele frequency of the germline NRAS Y64D mutation present in the chronic phase (via an acquired uniparental disomy of chromosome 1) and gaining NRAS G12D in the blast phase. SNP microarray analysis showed five clinically significant copy number losses at regions 7q22.1, 8q11.1-q11.21, 10p12.1-p11.22, 11p14.1-p11.2, and Xp11.4, revealing a complex karyotype already in the chronic phase. We discuss how additional mutations, detected by NGS, as well as HCV infection and antiviral therapy, might have negatively impacted this type 1 CALR-mutated PMF. We suggest that larger studies are required to determine if more careful monitoring would be needed in MPN patients also carrying HCV and receiving anti-HCV treatment.

Machine Learning for the Prediction of Survival Post-Allogeneic Hematopoietic Cell Transplantation: A Single-Center Experience

INTRODUCTION

Prediction of outcomes following allogeneic hematopoietic cell transplantation (HCT) remains a major challenge. Machine learning (ML) is a computational procedure that may facilitate the generation of HCT prediction models. We sought to investigate the prognostic potential of multiple ML algorithms when applied to a large single-center allogeneic HCT database.

METHODS

Our registry included 2,697 patients that underwent allogeneic HCT from January 1976 to December 2017. 45 pretransplant baseline variables were included in the predictive assessment of each ML algorithm on overall survival (OS) as determined by area under the curve (AUC). Pretransplant variables used in the EBMT ML study (Shouval et al., 2015) were used as a benchmark for comparison.

RESULTS

On the entire dataset, the random forest (RF) algorithm performed best (AUC 0.71 ± 0.04) compared to the second-best model, logistic regression (LR) (AUC = 0.69 ± 0.04) (p < 0.001). Both algorithms demonstrated improved AUC scores using all 45 variables compared to the limited variables examined by the EBMT study. Survival at 100 days post-HCT using RF on the full dataset discriminated patients into different prognostic groups with different 2-year OS (p < 0.0001). We then examined the ML methods that allow for significant individual variable identification, including LR and RF, and identified matched related donors (HR = 0.49, p < 0.0001), increasing TBI dose (HR = 1.60, p = 0.006), increasing recipient age (HR = 1.92, p < 0.0001), higher baseline Hb (HR = 0.59, p = 0.0002), and increased baseline FEV1 (HR = 0.73, p = 0.02), among others.

CONCLUSION

The application of multiple ML techniques on single-center allogeneic HCT databases warrants further investigation and may provide a useful tool to identify variables with prognostic potential.

Prognostic Significance of the Myelodysplastic Syndrome-Specific Comorbidity Index (MDS-CI) in Patients with Myelofibrosis: A Retrospective Study

In myelofibrosis, comorbidities (CMs) add prognostic information independently from the Dynamic International Prognostic Scoring System (DIPSS). The Myelodysplastic Syndrome-Specific Comorbidity Index (MDS-CI) offers a simple tool for CM assessment as it is calculable after having performed a careful history and physical examination, a small routine chemistry panel (including creatinine and liver enzymes) and a limited set of functional diagnostics. To assess the prognostic impact of the MDS-CI in addition to the DIPSS and the Mutation-Enhanced International Prognostic Scoring System (MIPSS)-70, we performed a retrospective chart review of 70 MF patients who had not received allogeneic stem cell transplantation (primary MF, n = 51; secondary MF, n = 19; median follow-up, 40 months) diagnosed at our institution between 2000 and 2020. Cardiac diseases (23/70) and solid tumors (12/70) were the most common CMs observed at MF diagnosis. Overall survival (OS) was significantly influenced by the MDS-CI (median OS MDS-CI low (n = 38): 101 months; MDS-CI intermediate (n = 25): 50 months; and high (n = 7): 8 months; p < 0.001). The MDS-CI added prognostic information after inclusion as a categorical variable in a multivariate model together with the dichotomized DIPSS or the dichotomized MIPSS70: MDS-CI high HR 14.64 (95% CI 4.42; 48.48), p = 0.0002, and MDS-CI intermediate HR 1.97 (95% CI 0.96; 4.03), p = 0.065, and MDS-CI high HR 19.65 (95% CI 4.71; 81.95), p < 0.001, and MDS-CI intermediate HR 1.063 (95% CI 0.65; 4.06), p = 0.2961, respectively. The analysis of our small and retrospective MF cohort suggests that the MDS-CI represents a useful tool to identify MF patients with an increased vulnerability due to comorbidities. However, analyses of larger cohorts are necessary to define the value of the MDS-CI as a prognostic tool in comparison with other comorbidity indices.

Allogeneic haematopoietic stem cell transplantation for myelofibrosis: prognostic indicators and the role of JAK2V617F measurable-residual disease monitoring by droplet-digital polymerase chain reaction

Relapse after allogeneic haematopoietic stem cell transplantation (HSCT) is one of the key determinants of outcome in myelofibrosis (MF) and remains an important unmet need. In this retrospective single-centre study, we evaluated 35 consecutive patients with MF receiving allogeneic HSCT. At 30 days post-HSCT, full donor chimerism was achieved in 31 patients (88.6%). The median time to neutrophil engraftment was 16.8 (10-42) days and the median time to platelet engraftment was 26 (12-245) days. Four patients (11.4%) experienced primary graft failure. With a median duration of follow-up of 33 (1-223) months, with the 5-year overall survival (OS) and progression-free survival (PFS) were 51.6% and 46.3%, respectively. Relapse after HSCT (P < 0.001), leucocyte count ≥ 18 × 109/L at HSCT (P = 0.003) and accelerated/blast phase disease at HSCT (P < 0.001) were significantly associated with worse OS. Age at HSCT ≥ 54 years (P = 0.01), mutated ETV6 (P = 0.03), leucocyte count ≥ 18 × 109/L (P = 0.02), accelerated/blast phase MF (P = 0.001), and grade 2-3 bone marrow reticulin fibrosis at 12 months post-HSCT (P = 0.002) were significantly associated with worse PFS. JAK2V617F MRD ≥ 0.047 [sensitivity 85.7%; positive predictive value (PPV) 100%; AUC 0.984; P = 0.001] at 6 months and JAK2V617F MRD ≥ 0.009 (sensitivity 100%; PPV 100%; AUC 1.0; P = 0.001) at 12 months were highly predictive of post-HSCT relapse. Inferior OS and PFS were significantly associated with detectable JAK2V617F MRD at 12 months (P = 0.003 and P = 0.0001, respectively).

Blast phase myeloproliferative neoplasm: contemporary review and 2024 treatment algorithm

Leukemic transformation in myeloproliferative neoplasms (MPN), also referred to as "blast-phase MPN", is the most feared disease complication, with incidence estimates of 1-4% for essential thrombocythemia, 3-7% for polycythemia vera, and 9-13% for primary myelofibrosis. Diagnosis of MPN-BP requires the presence of ≥20% circulating or bone marrow blasts; a lower level of excess blasts (10-19%) constitutes "accelerated phase" disease (MPN-AP). Neither "intensive" nor "less intensive" chemotherapy, by itself, secures long-term survival in MPN-BP. Large-scale retrospective series have consistently shown a dismal prognosis in MPN-BP, with 1- and 3-year survival estimates of <20% and <5%, respectively. Allogeneic hematopoietic stem cell transplant (AHSCT) offers the possibility of a >30% 3-year survival rate and should be pursued, ideally, while the patient is still in chronic phase disease. The value of pre-transplant bridging chemotherapy is uncertain in MPN-AP while it is advised in MPN-BP; in this regard, we currently favor combination chemotherapy with venetoclax (Ven) and hypomethylating agent (HMA); response is more likely in the absence of complex/monosomal karyotype and presence of TET2 mutation. Furthermore, in the presence of an IDH mutation, the use of IDH inhibitors, either alone or in combination with Ven-HMA, can be considered. Pre-transplant clearance of excess blasts is desired but not mandated; in this regard, additional salvage chemotherapy is more likely to compromise transplant eligibility rather than improve post-transplant survival. Controlled studies are needed to determine the optimal pre- and post-transplant measures that target transplant-associated morbidity and post-transplant relapse.

Cytogenetic Assessment and Risk Stratification in Myelofibrosis with Optical Genome Mapping

Cytogenetic assessment in myelofibrosis is essential for risk stratification and patient management. However, an informative karyotype is unavailable in a significant proportion of patients. Optical genome mapping (OGM) is a promising technique that allows for a high-resolution assessment of chromosomal aberrations (structural variants, copy number variants, and loss of heterozygosity) in a single workflow. In this study, peripheral blood samples from a series of 21 myelofibrosis patients were analyzed via OGM. We assessed the clinical impact of the application of OGM for disease risk stratification using the DIPSS-plus, GIPSS, and MIPSS70+v2 prognostic scores compared with the standard-of-care approach. OGM, in combination with NGS, allowed for risk classification in all cases, compared to only 52% when conventional techniques were used. Cases with unsuccessful karyotypes (n = 10) using conventional techniques were fully characterized using OGM. In total, 19 additional cryptic aberrations were identified in 9 out of 21 patients (43%). No alterations were found via OGM in 4/21 patients with previously normal karyotypes. OGM upgraded the risk category for three patients with available karyotypes. This is the first study using OGM in myelofibrosis. Our data support that OGM is a valuable tool that can greatly contribute to improve disease risk stratification in myelofibrosis patients.

Genetic basis and molecular profiling in myeloproliferative neoplasms

BCR::ABL1-negative myeloproliferative neoplasms (MPNs) are clonal diseases originating from a single hematopoietic stem cell that cause excessive production of mature blood cells. The 3 subtypes, that is, polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), are diagnosed according to the World Health Organization (WHO) and international consensus classification (ICC) criteria. Acquired gain-of-function mutations in 1 of 3 disease driver genes (JAK2, CALR, and MPL) are the causative events that can alone initiate and promote MPN disease without requiring additional cooperating mutations. JAK2-p.V617F is present in >95% of PV patients, and also in about half of the patients with ET or PMF. ET and PMF are also caused by mutations in CALR or MPL. In ∼10% of MPN patients, those referred to as being "triple negative," none of the known driver gene mutations can be detected. The common theme between the 3 driver gene mutations and triple-negative MPN is that the Janus kinase-signal transducer and activator of transcription (JAK/STAT) signaling pathway is constitutively activated. We review the recent advances in our understanding of the early events after the acquisition of a driver gene mutation. The limiting factor that determines the frequency at which MPN disease develops with a long latency is not the acquisition of driver gene mutations, but rather the expansion of the clone. Factors that control the conversion from clonal hematopoiesis to MPN disease include inherited predisposition, presence of additional mutations, and inflammation. The full extent of knowledge of the mutational landscape in individual MPN patients is now increasingly being used to predict outcome and chose the optimal therapy.

Myelofibrosis progression grading based on type I and type III collagen and fibrillin 1 expression boosted by whole slide image analysis

AIMS

The progression of primary myelofibrosis is characterised by ongoing extracellular matrix deposition graded based on 'reticulin' and 'collagen' fibrosis, as revealed by Gomori's silver impregnation. Here we studied the expression of the major extracellular matrix proteins of fibrosis in relation to diagnostic silver grading supported by image analysis.

METHODS AND RESULTS

By using automated immunohistochemistry, in this study we demonstrate that the expression of both types I and III collagens and fibrillin 1 by bone marrow stromal cells can reveal the extracellular matrix scaffolding in line with myelofibrosis progression as classified by silver grading. 'Reticulin' fibrosis indicated by type III collagen expression and 'collagen' fibrosis featured by type I collagen expression were parallel, rather than sequential, events. This is line with the proposed role of type III collagen in regulating type I collagen fibrillogenesis. The uniformly strong fibrillin 1 immune signals offered the best inter-rater agreements and the highest statistical correlations with silver grading of the three markers, which was robustly confirmed by automated whole slide digital image analysis using a machine learning-based algorithm. The progressive up-regulation of fibrillin 1 during myelofibrosis may result from a negative feedback loop as fibrillin microfibrils sequester TGF-β, the major promoter of fibrosis. This can also reduce TGF-β-induced RANKL levels, which would stimulate osteoclastogenesis and thus can support osteosclerosis in advanced myelofibrosis.

CONCLUSIONS

Through the in-situ detection of these extracellular matrix proteins, our results verify the molecular pathobiology of fibrosis during myelofibrosis progression. In particular, fibrillin 1 immunohistochemistry, with or without image analysis, can complement diagnostic silver grading at decent cell morphology.

International Consensus Classification of myeloid and lymphoid neoplasms: myeloproliferative neoplasms

The recently published International Consensus Classification (ICC) of myeloid neoplasms summarized the results of an in-depth effort by pathologists, oncologists, and geneticists aimed to update the 2017 World Health Organization classification system for hematopoietic tumors. Along these lines, several important modifications were implemented in the classification of myeloproliferative neoplasms (MPNs). For chronic myeloid leukemia, BCR::ABL1-positive, the definition of accelerated and blast phase was simplified, and in the BCR::ABL1-negative MPNs, the classification was slightly updated to improve diagnostic specificity with a more detailed and better validated morphologic approach and the recommendation of more sensitive molecular techniques to capture in particular early stage diseases. In this regard, high sensitive single target (RT-qPCR, ddPCR) or multi-target next-generation sequencing assays with a minimal sensitivity of VAF 1% are now important for a proper diagnostic identification of MPN cases with low allelic frequencies at initial presentation. This review discusses the updated diagnostic criteria of MPN according to the ICC, particularly by highlighting the new concepts and how they can be applied in clinical settings to obtain an appropriate prognostic relevant diagnosis.

The international consensus classification of myeloid neoplasms and acute Leukemias: myeloproliferative neoplasms

A group of international experts, including hematopathologists, oncologists, and geneticists were recently summoned (September 2021, Chicago, IL, USA) to update the 2016/17 World Health Organization classification system for hematopoietic tumors. After careful deliberation, the group introduced the new International Consensus Classification (ICC) for Myeloid Neoplasms and Acute Leukemias. This current in-depth review focuses on the ICC-2022 category of JAK2 mutation-prevalent myeloproliferative neoplasms (MPNs): essential thrombocythemia, polycythemia vera, primary myelofibrosis, and MPN, unclassifiable. The ICC MPN subcommittee chose to preserve the primary role of bone marrow morphology in disease classification and diagnostics, while also acknowledging the complementary role of genetic markers for establishing clonality, facilitating MPN subtype designation, and disease prognostication.

Molecular prognostication in Ph-negative MPNs in 2022

The application of genomic techniques, including cytogenetics and DNA sequencing, to decipher the molecular landscape of patients with myeloproliferative neoplasms (MPNs) has radically modified diagnostic approach and management through improved risk stratification. Three driver mutated genes (JAK2, MPL, CALR) are variably harbored by >80% of patients and associated with clinical characteristics, as well as major disease-related complications and different survival outcomes. Therefore, JAK2 V617F mutation is included in the revised International Prognosis Score of Thrombosis for Essential Thrombocythemia score for prediction of thrombosis in patients with essential thrombocythemia and prefibrotic primary myelofibrosis, while a CALR type 1 mutated genotype constitutes a favorable variable for survival in patients with myelofibrosis (MF). Novel, integrated clinical and cytogenetic/mutation scores (Mutation-Enhanced International Prognostic Score System for Transplantation-Age Patients with Primary Myelofibrosis [MIPSS70/v2], genetically inspired prognostic scoring system [GIPSS], Myelofibrosis Secondary to PV and ET- Prognostic Model [MYSEC-PM]) have been devised that guide selection of stem cell transplantation candidates with MF or help predict the risk associated with the transplant procedure (Myelofibrosis Transplant Scoring System), with greater performance compared with conventional scores based on hematologic and clinical variables only. On the other hand, several clinical needs remain unmet despite the great amount of molecular information available nowadays. These include the prediction of evolution to acute leukemia in a clinically actionable time frame, the identification of patients most likely to derive durable benefits from target agents, in primis JAK inhibitors, and, conversely, the significance of molecular responses that develop in patients receiving interferon or some novel agents. Here, we discuss briefly the significance and the role of genomic analysis for prognostication in patients with MPNs from a clinician's point of view, with the intent to provide how-to-use hints.

Molecular Pathogenesis of Myeloproliferative Neoplasms

PURPOSE OF REVIEW

Myeloproliferative neoplasms (MPNs) are chronic hematological malignancies characterized by increased proliferation of MPN stem and myeloid progenitor cells with or without bone marrow fibrosis that typically lead to increased peripheral blood cell counts. The genetic and cytogenetic alterations that initiate and drive the development of MPNs have largely been defined, and we summarize these here.

RECENT FINDINGS

In recent years, advances in understanding the pathogenesis of MPNs have defined a long-preclinical phase in JAK2-mutant MPN, identified genetic loci associated with MPN predisposition and uncovered mechanistic insights in CALR-mutant MPN. The integration of molecular genetics into prognostic risk models is well-established in myelofibrosis and ongoing studies are interrogating the prognostic implications of concomitant mutations in ET and PV. Despite all these advances, the field is deficient in clonally selective therapies to effectively target the MPN clone at any stage of disease, from pre-clinical to advanced. Although the biological understanding of the pathogenesis of MPNs has progressed quickly, substantial knowledge gaps remain, including in the molecular mechanisms underlying MPN progression and myelofibrotic transformation. An ongoing goal for the MPN field is to translate advances in biological understanding to improved treatments for patients.

Acute Myeloid Leukemia Following Myeloproliferative Neoplasms: A Review of What We Know, What We Do Not Know, and Emerging Treatment Strategies

Acute myeloid leukemia (AML) arising from myeloproliferative neoplasms (MPNs) represents a small subtype of secondary AML (sAML). This entity is well known to be associated with poor responses to available treatment options and dismal outcomes. To date, there are no standardized treatment options and there has been very little therapeutic advancement in recent years. This is a stark contrast to other subsets of AML for which there have been significant advances in therapeutic approaches, especially for patients with targetable mutations. We aim to focus our review on the incidence, risk factors for leukemogenesis, pathogenesis, molecular landscape, and emerging therapeutic options in post-myeloproliferative neoplasm acute myeloid leukemia (post-MPN AML).

Phase III MANIFEST-2: pelabresib + ruxolitinib vs placebo + ruxolitinib in JAK inhibitor treatment-naive myelofibrosis

Myelofibrosis (MF) is a clonal myeloproliferative neoplasm, typically associated with disease-related symptoms, splenomegaly, cytopenias and bone marrow fibrosis. Patients experience a significant symptom burden and a reduced life expectancy. Patients with MF receive ruxolitinib as the current standard of care, but the depth and durability of responses and the percentage of patients achieving clinical outcome measures are limited; thus, a significant unmet medical need exists. Pelabresib is an investigational small-molecule bromodomain and extraterminal domain inhibitor currently in clinical development for MF. The aim of this article is to describe the design of the ongoing, global, phase III, double-blind, placebo-controlled MANIFEST-2 study evaluating the efficacy and safety of pelabresib and ruxolitinib versus placebo and ruxolitinib in patients with JAKi treatment-naive MF. Clinical Trial Registration: NCT04603495 (ClinicalTrials.gov).

Disease-related thrombocytopenia in myelofibrosis is defined by distinct genetic etiologies and is associated with unique prognostic correlates

BACKGROUND

Thrombocytopenia in patients with myelofibrosis (MF) is prognostically detrimental and poses a therapeutic challenge. MF patients with thrombocytopenia are considered high-risk by most prognostic models and their distinct phenotype has given rise to the emerging concept of cytopenic MF. Yet, the mechanisms underlying thrombocytopenia in MF are poorly understood.

METHODS

This study aimed to highlight the genetic mechanisms driving low platelet counts in treatment-naive MF patients, establish their phenotypic correlates, and assess prognostic factors specific to this group of patients.

RESULTS

The authors found that most patients presenting with low platelets had a clear thrombocytopenia-specific genetic abnormality involving a U2AF1 Q157 mutation, deletion 20q, molecular complexity (three or more mutations), or high-risk karyotype. Etiologic clustering did not correlate with prognosis; however, thrombocytopenic patients were found to have unique prognostic variables including low serum albumin and mutations of SRSF2 and TP53. This led to the proposal of a prognostic model (SRSF2, albumin, TP53 score) that stratifies thrombocytopenic patients as low, intermediate, or high-risk with corresponding median survivals of 93.5, 29.5, and 7.2 months, respectively.

CONCLUSIONS

This study demonstrates that thrombocytopenia in MF is driven by different genetic mechanisms and is not uniformly high-risk. As novel agents with improved hematologic safety profiles enter the treatment landscape, thoughtful, risk-adapted therapeutic decisions will be required for MF patients with thrombocytopenia.

LAY SUMMARY

A significant minority of patients with myelofibrosis (MF) present with low platelets. Historically, these patients have been viewed as having "high-risk" disease, but this may not be uniformly true. Our study shows that there are various different causes for low platelets in MF, some of which represent high-risk disease whereas others do not. Additionally, our study shows that genetic mutations affecting the genes SRSF2 and TP53 are uniquely problematic in this group, as is a low serum albumin level. This study helps to risk-stratify MF patients with thrombocytopenia, thereby providing more information to guide informed and individualized treatment decisions.

How I Diagnose Primary Myelofibrosis

OBJECTIVES

Primary myelofibrosis (PMF) is a BCR/ABL1-negative myeloproliferative neoplasm (MPN) with a shorter overall survival and a higher leukemic transformation than other BCR/ABL1-negative MPNs. Diagnosis of PMF can be challenging given its clinical, morphologic, molecular overlap with other myeloid neoplasms also associated with myelofibrosis, and reactive conditions.

METHODS

We summarize and discuss the clinical, morphologic, and molecular features useful for diagnosing PMF as well as salient features helpful in distinguishing PMF from myelodysplastic syndrome with associated fibrosis and autoimmune myelofibrosis using a case-based approach.

RESULTS

PMF in both its prefibrotic and fibrotic stages, the latter characterized by reticulin/collagen marrow fibrosis, is characterized by a proliferation of predominantly abnormal megakaryocytes and granulocytes in the bone marrow. Driver mutations in   JAK2, CALR, or MPLare seen in approximately 90% of PMF cases. In triple-negative cases, the presence of cytogenetic abnormalities and other somatic mutations identified by next-generation sequencing can help establish a diagnosis of PMF in the appropriate clinical and morphologic context.

CONCLUSIONS

Given the significant difference in prognosis and treatment, integration of clinical, morphological, and molecular/genetic findings is essential in distinguishing PMF from other etiologies that can demonstrate myelofibrosis.

Cytogenetic abnormalities in essential thrombocythemia: Clinical and molecular correlates and prognostic relevance in 809 informative cases

Cytogenetic studies among 809 consecutive patients with essential thrombocythemia (ET; median age 59 years; 65% females) revealed normal karyotype in 754 (93%), loss of chromosome Y only (-Y) in 16 (2%), and abnormalities other than -Y in 39 (4.8%), the most frequent being sole 20q- (n = 8). At presentation, abnormal karyotype, excluding -Y, was associated with older age (p = 0.04), higher leukocyte count (p = 0.03) and arterial thrombosis history (p = 0.02); no associations were apparent for JAK2/CALR/MPL mutations whereas ASXL1 mutations clustered with normal karyotype/-Y and TP53 with abnormal karyotype. Survival was significantly shorter in patients with abnormal karyotype or -Y, compared to those with normal karyotype (median 12, 10, and 21 years, respectively; p < 0.0001). During multivariable analysis that included IPSET (international prognostic score for ET) variables, abnormal karyotype (p < 0.01, HR 2.0), age >60 years (p < 0.01, HR 4.5), leukocytosis >11 × 10⁹/L (p < 0.01, HR 1.5), and male gender (p < 0.01, HR 1.4) were independently associated with inferior survival; abnormal karyotype and age >60 years remained significant, along with SF3B1/SRSF2/U2AF1/TP53 mutations (p = 0.04; HR 2.9), when the latter was included in the multivariable model. The current study suggests prognostic relevance for karyotype in ET.

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

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

A Prognostic Model to Predict Survival After 6 Months of Ruxolitinib in Patients with Myelofibrosis

RUX dose, spleen response, and transfusion requirement in the first 6 months of RUX treatment predict overall survival in MF.

The RR6 model overcomes conventional risk stratification in RUX-treated MF.

Ruxolitinib (RUX) is extensively used in myelofibrosis (MF). Despite its early efficacy, most patients lose response over time and, after discontinuation, have a worse overall survival (OS). Currently, response criteria able to predict OS in RUX-treated patients are lacking, leading to uncertainty regarding the switch to second-line treatments. In this study, we investigated predictors of survival collected after 6 months of RUX in 209 MF patients participating in the real-world ambispective observational RUXOREL-MF study (NCT03959371). Multivariable analysis identified the following risk factors: (1) RUX dose <20 mg twice daily at baseline, months 3 and 6 (hazard ratio [HR], 1.79; 95% confidence interval [CI], 1.07-3.00; P = .03), (2) palpable spleen length reduction from baseline ≤30% at months 3 and 6 (HR, 2.26; 95% CI, 1.40-3.65; P = .0009), (3) red blood cell (RBC) transfusion need at months 3 and/or 6 (HR, 1.66; 95% CI, 0.95-2.88; P = .07), and (4) RBC transfusion need at all time points (ie, baseline and months 3 and 6; HR, 2.32; 95% CI, 1.19-4.54; P = .02). Hence, we developed a prognostic model, named Response to Ruxolitinib After 6 Months (RR6), dissecting 3 risk categories: low (median OS, not reached), intermediate (median OS, 61 months; 95% CI, 43-80), and high (median OS, 33 months; 95% CI, 21-50). The RR6 model was validated and confirmed in an external cohort comprised of 40 MF patients. In conclusion, the RR6 prognostic model allows for the early identification of RUX-treated MF patients with impaired survival who might benefit from a prompt treatment shift.

Mutational spectrum and prognosis in Chinese patients with prefibrotic primary myelofibrosis

Prefibrotic primary myelofibrosis (Pre‐PMF) has been classified as a separate entity of myeloproliferative neoplasms (MPNs). Pre‐PMF is clinically heterogeneous but a specific prognostic model is lacking. Gene mutations have emerged as useful tools for stratification of myelofibrosis patients. However, there have been limited studies comprehensively investigating the mutational spectrum and its clinicopathological significance in pre‐PMF subjects. In this study, we addressed these issues by profiling the mutation status of 141 genes in 172 Chinese MPN patients including 72 pre‐PMF cases. Our findings corroborated the clinical/molecular distinctiveness of pre‐PMF and suggested a refined risk classification strategy for this entity.

Reduced intensity hematopoietic stem cell transplantation for myelofibrosis in accelerated-phase

Results of this first report in accelerated-phase myelofibrosis may encourage clinicians to refer these patients for curative treatment.

Accelerated-phase myelofibrosis without prior cytoreduction showed excellent 5-year survival (65%) but higher relapse vs chronic phase.

Accelerated-phase myelofibrosis, currently defined by circulating blasts 10% to 19%, usually confers very high risk for progression and poor outcome. The outcome of hematopoietic stem cell transplantation for accelerated-phase myelofibrosis has not been evaluated yet. We analyzed the outcome of 349 clinically and genetically annotated patients with primary or secondary myelofibrosis undergoing reduced intensity transplantation, of whom 35 had accelerated-phase myelofibrosis. In comparison with chronic-phase (<10% blasts) myelofibrosis, median leukocyte counts were higher, more patients had constitutional symptoms, and RAS mutations were detected more frequently in the accelerated-phase group. After a median follow-up of 5.9 years, estimated 5-year overall survival was 65% (95% confidence interval [CI], 49% to 81%) vs 64% (95% CI, 59% to 69%) for the chronic-phase group (P = .91), and median overall survival was not reached. In terms of relapse-free survival, estimated 5-year outcome for the accelerated-phase group was 49% (95% CI, 32% to 67%) vs 55% (95% CI, 50% to 61%) for the chronic-phase group (P = .65). Estimated 5-year nonrelapse mortality was 20% (95% CI, 8% to 33%) for the accelerated-phase group vs 30% (95% CI, 24% to 35%; P = .25) for the chronic-phase group. In terms of relapse, 5-year incidence was 30% (95% CI, 14% to 46%) for the accelerated-phase group vs 15% (95% CI, 11% to 19%) for the chronic-phase group (P = .02). Results were confirmed in multivariable analysis and propensity score matching. In conclusion, reduced intensity transplantation showed excellent survival but higher relapse for accelerated-phase myelofibrosis.

Polycythemia vera: historical oversights, diagnostic details, and therapeutic views

Polycythemia vera (PV) is a relatively indolent myeloid neoplasm with median survival that exceeds 35 years in young patients, but its natural history might be interrupted by thrombotic, fibrotic, or leukemic events, with respective 20-year rates of 26%, 16%, and 4%. Current treatment strategies in PV have not been shown to prolong survival or lessen the risk of leukemic or fibrotic progression and instead are directed at preventing thrombotic complications. In the latter regard, two risk categories are considered: high (age >60 years or thrombosis history) and low (absence of both risk factors). All patients require phlebotomy to keep hematocrit below 45% and once-daily low-dose aspirin, in the absence of contraindications. Cytoreductive therapy is recommended for high-risk or symptomatic low-risk disease; our first-line drug of choice in this regard is hydroxyurea but we consider pegylated interferon as an alternative in certain situations, including in young women of reproductive age, in patients manifesting intolerance or resistance to hydroxyurea therapy, and in situations where treatment is indicated for curbing phlebotomy requirement rather than preventing thrombosis. Additional treatment options include busulfan and ruxolitinib; the former is preferred in older patients and the latter in the presence of symptoms reminiscent of post-PV myelofibrosis or protracted pruritus. Our drug choices reflect our appreciation for long-term track record of safety, evidence for reduction of thrombosis risk, and broader suppression of myeloproliferation. Controlled studies are needed to clarify the added value of twice- vs once-daily aspirin dosing and direct oral anticoagulants. In this invited review, we discuss our current approach to diagnosis, prognostication, and treatment of PV in general, as well as during specific situations, including pregnancy and splanchnic vein thrombosis.

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.

New Markers of Disease Progression in Myelofibrosis

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

Clinical Efficacy of Ruxolitinib in Patients with Myelofibrosis: A Nationwide Population-Based Study in Korea

Previous studies have reported the survival benefit after ruxolitinib treatment in patients with myelofibrosis (MF). However, population-based data of its efficacy are limited. We analyzed the effects of ruxolitinib in MF patients with data from the Korean National Health Insurance Database. In total, 1199 patients diagnosed with MF from January 2011 to December 2017 were identified, of which 731 were included in this study. Patients who received ruxolitinib (n = 224) were matched with those who did not receive the drug (n = 507) using the 1:1 greedy algorithm. Propensity scores were formulated using five variables: age, sex, previous history of arterial/venous thrombosis, and red blood cell (RBC) or platelet (PLT) transfusion dependence at the time of diagnosis. Cox regression analysis for overall survival (OS) revealed that ruxolitinib treatment (hazard ratio (HR), 0.67; p = 0.017) was significantly related to superior survival. In the multivariable analysis for OS, older age (HR, 1.07; p < 0.001), male sex (HR, 1.94; p = 0.021), and RBC (HR, 3.72; p < 0.001) or PLT (HR, 9.58; p = 0.001) transfusion dependence were significantly associated with poor survival, although type of MF did not significantly affect survival. Considering evidence supporting these results remains weak, further studies on the efficacy of ruxolitinib in other populations are needed.

Outcomes of Allogeneic Hematopoietic Cell Transplantation in Patients With Myelofibrosis-A Systematic Review and Meta-Analysis

Allogeneic hematopoietic cell transplant (allo-HCT) remains the only potentially curative therapeutic modality for patients with primary or secondary myelofibrosis (MF). However, many patients are considered ineligible for allo-HCT, and transplant-related mortality can be substantial. Data on the efficacy and safety of allo-HCT are mixed and largely derived from retrospective studies. We aimed to synthesize the available evidence on the safety and efficacy of allo-HCT in MF and to identify patient, disease, and transplant characteristics with prognostic impact on outcomes of patients with MF undergoing allo-HCT. For this systematic review and meta-analysis, Cochrane Library, Google Scholar, Ovid Medline, Ovid Embase, PubMed, Scopus, and Web of Science Core Collection were searched from inception to October 11, 2020, for studies on allo-HCT in MF. Random-effects models were used to pool response rates for the co-primary outcomes of 1-year, 2-year, and 5-year overall survival (OS). Rates of non-relapse mortality and acute and chronic graft-versus-host-disease (GVHD) were studied as secondary endpoints. Subgroup analyses on the effect of conditioning regimen intensity, baseline dynamic international prognostic scoring system (DIPSS) score, and patient age were performed. The study protocol has been registered on PROSPERO (CRD42020188706). Forty-three studies with 8739 patients were identified and included in this meta-analysis. Rates of 1-year, 2-year, and 5-year OS were 66.7% (95% confidence interval [CI], 63.5%-69.8%), 64.4% (95% CI, 57.6%-70.6%), and 55.0% (95% CI, 51.8%-58.3%), respectively. Rates of 1-year, 2-year, and 5-year nonrelapse mortality were 25.9% (95% CI, 23.3%-28.7%), 29.7% (95% CI, 24.5%-35.4%), and 30.5% (95% CI, 25.9%-35.5%), respectively. The combined rate of graft failure was 10.6% (95% CI, 8.9%-12.5%) with primary and secondary graft failure occurring in 7.3% (95% CI, 5.7%-9.4%) and 5.9% (95% CI, 4.3%-8.0%) of patients, respectively. Rates of acute and chronic graft-versus-host disease were 44.0% (95% CI, 39.6%-48.4%; grade III/IV: 15.2%) and 46.5% (95% CI, 42.2%-50.8%; extensive or moderate/severe: 26.1%), respectively. Subgroup analyses did not show any significant difference between conditioning regimen intensity (myeloablative versus reduced-intensity), median patient age, and proportion of DIPSS-intermediate-2/high patients. The quality of the evidence is limited by the absence of randomized clinical trials in the field and the heterogeneity of patient and transplant characteristics across included studies. Given the poor prognosis of patients not receiving transplants and in the absence of curative nontransplantation therapies, our results support consideration of allo-HCT for eligible patients with MF.

Classical Philadelphia-negative myeloproliferative neoplasms (MPNs): A continuum of different disease entities

Classical Philadelphia-negative myeloproliferative neoplasms (MPNs) are clonal hematopoietic stem cell-derived disorders characterized by uncontrolled proliferation of differentiated myeloid cells and close pathobiologic and clinical features. According to the 2016 World Health Organization (WHO) classification, MPNs include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). The 2016 revision aimed in particular at strengthening the distinction between masked PV and JAK2-mutated ET, and between prefibrotic/early (pre-PMF) and overt PMF. Clinical manifestations in MPNs include constitutional symptoms, microvascular disorders, thrombosis and bleeding, splenomegaly secondary to extramedullary hematopoiesis, cytopenia-related symptoms, and progression to overt MF and acute leukemia. A dysregulation of the JAK/STAT pathway is the unifying mechanistic hallmark of MPNs, and is guided by somatic mutations in driver genes including JAK2, CALR and MPL. Additional mutations in myeloid neoplasm-associated genes have been also identified, with established prognostic relevance, particularly in PMF. Prognostication of MPN patients relies on disease-specific clinical models. The increasing knowledge of MPN biology led to the development of integrated clinical and molecular prognostic scores that allow a more refined stratification. Recently, the therapeutic landscape of MPNs has been revolutionized by the introduction of potent, selective JAK inhibitors (ruxolitinib, fedratinib), that proved effective in controlling disease-related symptoms and splenomegaly, yet leaving unmet critical needs, owing the lack of disease-modifying activity. In this review, we will deal with molecular, clinical, and therapeutic aspects of the three classical MPNs aiming at highlighting either shared characteristics, that overall define a continuum within a single disease family, and uniqueness, at the same time.

Cell-autonomous megakaryopoiesis associated with polyclonal hematopoiesis in triple-negative essential thrombocythemia

A subset of essential thrombocythemia (ET) cases are negative for disease-defining mutations on JAK2, MPL, and CALR and defined as triple negative (TN). The lack of recurrent mutations in TN-ET patients makes its pathogenesis ambiguous. Here, we screened 483 patients with suspected ET in a single institution, centrally reviewed bone marrow specimens, and identified 23 TN-ET patients. Analysis of clinical records revealed that TN-ET patients were mostly young female, without a history of thrombosis or progression to secondary myelofibrosis and leukemia. Sequencing analysis and human androgen receptor assays revealed that the majority of TN-ET patients exhibited polyclonal hematopoiesis, suggesting a possibility of reactive thrombocytosis in TN-ET. However, the serum levels of thrombopoietin (TPO) and interleukin-6 in TN-ET patients were not significantly different from those in ET patients with canonical mutations and healthy individuals. Rather, CD34-positive cells from TN-ET patients showed a capacity to form megakaryocytic colonies, even in the absence of TPO. No signs of thrombocytosis were observed before TN-ET development, denying the possibility of hereditary thrombocytosis in TN-ET. Overall, these findings indicate that TN-ET is a distinctive disease entity associated with polyclonal hematopoiesis and is paradoxically caused by hematopoietic stem cells harboring a capacity for cell-autonomous megakaryopoiesis.

Allogeneic haematopoietic cell transplantation for myelofibrosis: proposed definitions and management strategies for graft failure, poor graft function and relapse: best practice recommendations of the EBMT Chronic Malignancies Working Party

Allogeneic haematopoietic cell transplantation (allo-HCT) remains the only curative approach in myelofibrosis (MF). Despite advances over recent decades, relapse and non-relapse mortality rates remain significant. Relapse rates vary between 15 and 25% across retrospective studies and management strategies vary widely, ranging from palliation to adoptive immunotherapy and, in some cases, a second allo-HCT. Moreover, in allo-HCT, there is a higher incidence of poor graft function and graft failure due to splenomegaly and a hostile "pro-inflammatory" marrow niche. The Practice Harmonisation and Guidelines subcommittee of the Chronic Malignancies Working Party (CMWP) of EBMT convened an international panel consisting of transplant haematologists, histopathologists and molecular biologists to propose practical, clinically relevant definitions of graft failure, poor graft function and relapse as well as management strategies following allo-HCT. A systematic approach to molecular monitoring, histopathological assessment and chimerism testing is proposed. These proposed recommendations aim to increase the accuracy and uniformity of reporting and to thereby facilitate the development of more consistent approaches to these challenging issues. In addition, we propose management strategies for these complications.

The Prognostic Role of Cytogenetics Analysis in Philadelphia Negative Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPNs) are clonal stem cell disorders characterized collectively by clonal proliferation of myeloid cells with variable morphologic maturity and hematopoietic efficiency. Although the natural history of these neoplasms can be measured sometimes in decades more than years, the cytogenetics analysis can offer useful information regarding the prognosis. Cytogenetics has a well-established prognostic role in acute leukemias and in myelodysplastic syndromes, where it drives the clinical decisions. NGS techniques can find adverse mutations with clear prognostic value and are currently included in the prognostic evaluation of MPNs in scores such as MIPSS, GIPSS, MIPSS-PV, and MIPSS-ET. We suggest that cytogenetics (considering its availability and relative cost) has a role regarding prognostic and therapeutic decisions.

A case of a primary myelofibrosis with progression and related literature review of progression phase genetics

Philadelphia (BCR-ABL)-negative myeloproliferative neoplasms (MPNs) include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). MPN can transform into an accelerated or a blast phase, which is associated with poor response to standard therapy and low overall median survival. We present an interesting case of a patient with a history of PMF and progression and summarize the current studies on genetic features of myeloproliferative neoplasms in blast phase (MPN-BP) with an emphasis on PMF. Although MPN-BP show ≥20% blasts in peripheral blood or bone marrow, it is not considered as acute myeloid leukemia (AML) according to the WHO classification. While MPNs-BP typically lack genetic mutations seen in de novo AML, they commonly harbor IDH1/2, SRSF2, ASXL1, and TP53 mutations, similar to the genetic profiles of acute myeloid leukemia with myelodysplasia-related changes (AML-MRC).

Integration of Molecular Information in Risk Assessment of Patients with Myeloproliferative Neoplasms

Philadelphia chromosome-negative myeloproliferative neoplasms (MPN) are clonal disorders of a hematopoietic stem cell, characterized by an abnormal proliferation of largely mature cells driven by mutations in JAK2, CALR, and MPL. All these mutations lead to a constitutive activation of the JAK-STAT signaling, which represents a target for therapy. Beyond driver ones, most patients, especially with myelofibrosis, harbor mutations in an array of "myeloid neoplasm-associated" genes that encode for proteins involved in chromatin modification and DNA methylation, RNA splicing, transcription regulation, and oncogenes. These additional mutations often arise in the context of clonal hematopoiesis of indeterminate potential (CHIP). The extensive characterization of the pathologic genome associated with MPN highlighted selected driver and non-driver mutations for their clinical informativeness. First, driver mutations are enlisted in the WHO classification as major diagnostic criteria and may be used for monitoring of residual disease after transplantation and response to treatment. Second, mutation profile can be used, eventually in combination with cytogenetic, histopathologic, hematologic, and clinical variables, to risk stratify patients regarding thrombosis, overall survival, and rate of transformation to secondary leukemia. This review outlines the molecular landscape of MPN and critically interprets current information for their potential impact on patient management.

Next Generation Cytogenetics in Myeloid Hematological Neoplasms: Detection of CNVs and Translocations

Simple Summary

Conventional cytogenetic approaches are the gold standard for the identification of chromosomal alterations in myeloid neoplasms. Next-generation sequencing panels are a new approach for the detection of copy number variations (CNV) or translocations. Here we report on a commercial panel utility including frequent mutations, CNVs and translocations in myeloid neoplasms. A total of 135 patients with myeloid neoplasms and three with acute lymphoblastic leukemia were analyzed by NGS. When comparing with gold standard techniques, 48 frequent alterations were detected by both methodologies, ten of them observed only by conventional methods and another eight only by NGS. Additionally, 38 secondary CNVs were detected in any of the genes included in the panel for mutational analysis. With those results we determine that NGS represents a reliable complementary source of information for the analysis of CNVs and translocations.

Abstract

Conventional cytogenetics are the gold standard for the identification of chromosomal alterations recurrent in myeloid neoplasms. Some next-generation sequencing (NGS) panels are designed for the detection of copy number variations (CNV) or translocations; however, their use is far from being widespread. Here we report on the results of a commercial panel including frequent mutations, CNVs and translocations in myeloid neoplasms. Frequent chromosomal alterations were analyzed by NGS in 135 patients with myeloid neoplasms and three with acute lymphoblastic leukemia. NGS analysis was performed using the enrichment-capture Myeloid Neoplasm-GeneSGKit (Sistemas Genómicos, Spain) gene panel including 35 genes for mutational analysis and frequent CNVs and translocations. NGS results were validated with cytogenetics and/or MLPA when possible. A total of 66 frequent alterations included in NGS panel were detected, 48 of them detected by NGS and cytogenetics. Ten of them were observed only by cytogenetics (mainly trisomy 8), and another eight only by NGS (mainly deletion of 12p). Aside from this, 38 secondary CNVs were detected in any of the genes included mainly for mutational analysis. NGS represents a reliable complementary source of information for the analysis of CNVs and translocations. Moreover, NGS could be a useful tool for the detection of alterations not observed by conventional cytogenetics.

RAS/CBL mutations predict resistance to JAK inhibitors in myelofibrosis and are associated with poor prognostic features

The dysregulation of the JAK/STAT pathway drives the pathogenesis of myelofibrosis (MF). Recently, several JAK inhibitors (JAKis) have been developed for treating MF. Select mutations (MTs) have been associated with impaired outcomes and are currently incorporated in molecularly annotated prognostic models. Mutations of RAS/MAPK pathway genes are frequently reported in cancer and at low frequencies in MF. In this study, we investigated the phenotypic, prognostic, and therapeutic implications of NRASMTs, KRASMTs, and CBLMTs (RAS/CBLMTs) in 464 consecutive MF patients. A total of 59 (12.7%) patients had RAS/CBLMTs: NRASMTs, n = 25 (5.4%); KRASMTs, n = 13 (2.8%); and CBLMTs, n = 26 (5.6%). Patients with RAS/CBLMTs were more likely to present with high-risk clinical and molecular features. RAS/CBLMTs were associated with inferior overall survival compared with patients without MTs and retained significance in a multivariate model, including the Mutation-Enhanced International Prognostic Score System (MIPSS70) risk factors and cytogenetics; however, inclusion of RAS/CBLMTs in molecularly annotated prognostic models did not improve the predictive power of the latter. The 5-year cumulative incidence of leukemic transformation was notably higher in the RAS/CBLMT cohort. Among 61 patients treated with JAKis and observed for a median time of 30 months, the rate of symptoms and spleen response at 6 months was significantly lower in the RAS/CBLMT cohort. Logistic regression analysis disclosed a significant inverse correlation between RAS/CBLMTs and the probability of achieving a symptom or spleen response that was retained in multivariate analysis. In summary, our study showed that RAS/CBLMTs are associated with adverse phenotypic features and survival outcomes and, more important, may predict reduced response to JAKis.

Outcome of patients with IDH1/2-mutated post-myeloproliferative neoplasm AML in the era of IDH inhibitors

IDH1/2-inhibitor–based combinations conferred significant clinical responses in patients with IDH1/2-mutated post–MPN AML. Complete remission was achieved in 3/7 patients (1 attaining MRD–) with new IDH1/2-mutated post–MPN AML treated with IDH1/2-i combinations.

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.

Outcomes following second allogeneic haematopoietic cell transplantation in patients with myelofibrosis: a retrospective study of the Chronic Malignancies Working Party of EBMT

Therapeutic management of patients with primary or secondary myelofibrosis (MF) who experience relapse or graft failure following allogeneic haematopoietic cell transplantation (allo-HCT) remains heterogeneous. We retrospectively analyzed 216 patients undergoing a second allo-HCT for either relapse (56%) or graft failure (31%) between 2010 and 2017. Median age was 57.3 years (range 51-63). The same donor as for the first allo-HCT was chosen in 66 patients (31%) of whom 19 received an HLA-identical sibling donor, whereas a different donor was chosen for 116 patients (54%). Median follow-up was 40 months. Three-year overall survival (OS) and relapse-free survival (RFS) were 42% and 39%, respectively. Three-year non-relapse mortality (NRM) and relapse rates were 36% and 25%, respectively. Grade II-IV and III-IV acute GVHD occurred in 25% and 11% of patients, respectively, and the 3-year incidence of chronic GVHD was 33% including 14% for extensive grade. Graft-failure incidence at 1 year was 14%. In conclusion, our data suggest that a second allo-HCT is a potential option for patients failing first allo-HCT for MF albeit careful patient assessment is fundamental to identify individual patients who could benefit from this approach.

[Evaluation of the prognostic value of MIPSS70-plus in Chinese patients with primary myelofibrosis]

目的

评价MIPSS70-plus预后积分系统对中国原发性骨髓纤维化（PMF）患者的预后评估价值。

方法

回顾性分析113例PMF患者的临床资料，应用Log-rank和COX回归模型进行预后相关因素分析；应用似然比检验比较MIPSS70-plus和动态国际预后积分系统（DIPSS）的预后评估效能。

结果

113例PMF患者中男71例，女42例，中位年龄55（20～70）岁。依据MIPSS70-plus染色体核型分组标准，染色体核型预后良好组90例（79.6%），预后不良组23例（20.4%）。二代测序基因突变检测结果示，JAK2V617F突变63例（55.8%），CALR外显子9突变20例（17.7%）（其中1型CALR突变15例，2型CALR突变5例），MPLW515突变5例（4.4%），25例（22.1%）未检测到JAK2、MPL和CALR基因突变（三阴性）。高分子风险（HMR）突变检出率依次为ASXL1突变44例（38.9%）、SRSF2突变8例（7.1%）、IDH1/2突变5例（4.4%）、EZH2突变4例（3.5%）；51例患者（45.1%）有1种以上高危基因突变。MIPSS70-plus预后积分低危组、中危组、高危组、极高危组分别为28例（26.7%）、20例（19.0%）、41例（39.0%）、16例（15.3%），2年预期总生存率分别为100%、89.7%（95%CI 76.2%～100.0%）、64.8%（95%CI 47.0%～82.6%）、35.0%（95%CI 10.3%～59.7%）（P<0.001）。MIPSS70-plus的-2log似然比显著低于DIPSS（86.355对95.990，P＝0.001），表明MIPSS70-plus较DIPSS有更准确的预后分组预测效能。

结论

MIPSS-70plus较DIPSS预后积分系统对中国PMF患者有更好的预后评估效能。

Myeloid somatic mutation panel testing in myeloproliferative neoplasms

Myeloproliferative neoplasms are characterised by somatic mutations in pathways that regulate cell proliferation, epigenetic modifications, RNA splicing or DNA repair. Assessment of the mutational profile assists diagnosis and classification, but also aids assessment of prognosis, and may guide the use of emerging targeted therapies. The most practical way to provide information on numerous genetic variants is by using massively parallel sequencing, commonly in the form of disease specific next generation sequencing (NGS) panels. This review summarises the diagnostic and prognostic value of somatic mutation testing in Philadelphia-negative myeloproliferative neoplasms: polycythaemia vera, essential thrombocythaemia, primary myelofibrosis, chronic neutrophilic leukaemia, systemic mastocytosis, and chronic eosinophilic leukaemia. NGS panel testing is increasing in routine practice and promises to improve the accuracy and efficiency of pathological diagnosis and prognosis.

Impact of Integrated Genetic Information on Diagnosis and Prognostication for Myeloproliferative Neoplasms in the Next-Generation Sequencing Era

Since next-generation sequencing has been widely used in clinical laboratories, the diagnosis and risk stratification of hematologic malignancies are greatly dependent on genetic aberrations. In this study, we analyzed the genomic landscapes of 200 patients with myeloproliferative neoplasms (MPNs) and evaluated the impact of the genomic landscape on diagnosis and risk stratification. Mutations in JAK2, CALR and MPL were detected in 76.4% of MPNs. The proportion of patients with clonal genetic markers increased up to 86.4% when all detectable genetic aberrations were included. Significant co-occurring genetic aberrations potentially associated with phenotype and/or disease progression, including those in JAK2/SF3B1 and TP53/del(13q), del(5q), −7/del(7q) and complex karyotypes, were detected. We also identified genetic aberrations associated with patient outcomes: TP53 and −7/del(7q) were associated with an inferior chance of survival, RUNX1, TP53 and IDH1/2 were associated with leukemic transformation and SF3B1, IDH1/2, ASXL1 and del(20q) were associated with fibrotic progression. We compared risk stratification systems and found that mutation-enhanced prognostic scoring systems could identify lower risk polycythemia vera, essential thrombocythemia and higher risk primary myelofibrosis. Furthermore, the new risk stratification systems showed a better predictive capacity for patient outcome. These results collectively indicate that integrated genetic information can enhance diagnosis and prognostication in patients with myeloproliferative neoplasms.