1 959 128 CHRONIC MYELOMONOCYTIC LEUKEMIA AND ATYPICAL CHRONIC MYELOID LEUKEMIA: NOVEL PATHOGENETIC LESIONS. CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) AND ATYPICAL CHRONIC MYELOID LEUKEMIA (ACML) ARE DISTINCT, YET RELATED, ENTITIES OF MYELODYSPLASTIC/MYELOPROLIFERATIVE NEOPLASMS (MDS/MPN) CHARACTERIZED BY MORPHOLOGIC DYSPLASIA WITH ACCUMULATION OF MONOCYTES OR NEUTROPHILS, RESPECTIVELY. OUR UNDERSTANDING OF THE MOLECULAR PATHOGENESIS OF CMML AND ACML HAS ADVANCED, MAINLY DUE TO THE APPLICATION OF NOVEL TECHNOLOGIES SUCH AS ARRAY-BASED KARYOTYPING AND NEXT-GENERATION SEQUENCING. IN ADDITION TO PREVIOUSLY KNOWN RECURRENT ABERRATIONS, SOMATIC UNIPARENTAL DISOMY AFFECTING CHROMOSOMES 3, 4, 7, AND 11 FREQUENTLY OCCURS IN CMML. NOVEL SOMATIC MUTATIONS OF GENES, INCLUDING THOSE ASSOCIATED WITH PROLIFERATION SIGNALING (CBL, RAS, RUNX1, JAK2 (V617F)) AND WITH MODIFICATION OF EPIGENETIC STATUS (TET2, ASXL1, UTX, EZH2) HAVE BEEN FOUND. VARIOUS COMBINATIONS OF MUTATIONS SUGGEST A MULTISTEP PATHOGENESIS AND MAY ACCOUNT FOR CLINICAL HETEROGENEITY. MOST RECENTLY, SEVERAL SPLICEOSOME-ASSOCIATED-GENE MUTATIONS WERE REPORTED AND SRSF2 MUTATIONS ARE FREQUENTLY DETECTED IN CMML. THE PROGNOSTIC AND DIAGNOSTIC SIGNIFICANCE OF THESE MOLECULAR LESIONS, IN PARTICULAR THEIR VALUE AS BIOMARKERS OF RESPONSE OR RESISTANCE TO SPECIFIC THERAPIES, WHILE UNCERTAIN NOW IS LIKELY TO BE CLARIFIED AS LARGE SYSTEMATIC STUDIES COME TO COMPLETION. 2012 2 4557 28 MUTATIONS IN ASXL1 ARE ASSOCIATED WITH POOR PROGNOSIS ACROSS THE SPECTRUM OF MALIGNANT MYELOID DISEASES. THE ASXL1 GENE IS ONE OF THE MOST FREQUENTLY MUTATED GENES IN MALIGNANT MYELOID DISEASES. THE ASXL1 PROTEIN BELONGS TO PROTEIN COMPLEXES INVOLVED IN THE EPIGENETIC REGULATION OF GENE EXPRESSION. ASXL1 MUTATIONS ARE FOUND IN MYELOPROLIFERATIVE NEOPLASMS (MPN), MYELODYSPLASTIC SYNDROMES (MDS), CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) AND ACUTE MYELOID LEUKEMIA (AML). THEY ARE GENERALLY ASSOCIATED WITH SIGNS OF AGGRESSIVENESS AND POOR CLINICAL OUTCOME. BECAUSE OF THIS, A SYSTEMATIC DETERMINATION OF ASXL1 MUTATIONAL STATUS IN MYELOID MALIGNANCIES SHOULD HELP IN PROGNOSIS ASSESSMENT. 2012 3 4565 39 MYELOID MALIGNANCIES: MUTATIONS, MODELS AND MANAGEMENT. MYELOID MALIGNANT DISEASES COMPRISE CHRONIC (INCLUDING MYELODYSPLASTIC SYNDROMES, MYELOPROLIFERATIVE NEOPLASMS AND CHRONIC MYELOMONOCYTIC LEUKEMIA) AND ACUTE (ACUTE MYELOID LEUKEMIA) STAGES. THEY ARE CLONAL DISEASES ARISING IN HEMATOPOIETIC STEM OR PROGENITOR CELLS. MUTATIONS RESPONSIBLE FOR THESE DISEASES OCCUR IN SEVERAL GENES WHOSE ENCODED PROTEINS BELONG PRINCIPALLY TO FIVE CLASSES: SIGNALING PATHWAYS PROTEINS (E.G. CBL, FLT3, JAK2, RAS), TRANSCRIPTION FACTORS (E.G. CEBPA, ETV6, RUNX1), EPIGENETIC REGULATORS (E.G. ASXL1, DNMT3A, EZH2, IDH1, IDH2, SUZ12, TET2, UTX), TUMOR SUPPRESSORS (E.G. TP53), AND COMPONENTS OF THE SPLICEOSOME (E.G. SF3B1, SRSF2). LARGE-SCALE SEQUENCING EFFORTS WILL SOON LEAD TO THE ESTABLISHMENT OF A COMPREHENSIVE REPERTOIRE OF THESE MUTATIONS, ALLOWING FOR A BETTER DEFINITION AND CLASSIFICATION OF MYELOID MALIGNANCIES, THE IDENTIFICATION OF NEW PROGNOSTIC MARKERS AND THERAPEUTIC TARGETS, AND THE DEVELOPMENT OF NOVEL THERAPIES. GIVEN THE IMPORTANCE OF EPIGENETIC DEREGULATION IN MYELOID DISEASES, THE USE OF DRUGS TARGETING EPIGENETIC REGULATORS APPEARS AS A MOST PROMISING THERAPEUTIC APPROACH. 2012 4 2277 39 EPIGENETIC REGULATION BY ASXL1 IN MYELOID MALIGNANCIES. MYELOID MALIGNANCIES ARE CLONAL HEMATOPOIETIC DISORDERS THAT ARE COMPRISED OF A SPECTRUM OF GENETICALLY HETEROGENEOUS DISORDERS, INCLUDING MYELODYSPLASTIC SYNDROMES (MDS), MYELOPROLIFERATIVE NEOPLASMS (MPN), CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML), AND ACUTE MYELOID LEUKEMIA (AML). MYELOID MALIGNANCIES ARE CHARACTERIZED BY EXCESSIVE PROLIFERATION, ABNORMAL SELF-RENEWAL, AND/OR DIFFERENTIATION DEFECTS OF HEMATOPOIETIC STEM CELLS (HSCS) AND MYELOID PROGENITOR CELLS HEMATOPOIETIC STEM/PROGENITOR CELLS (HSPCS). MYELOID MALIGNANCIES CAN BE CAUSED BY GENETIC AND EPIGENETIC ALTERATIONS THAT PROVOKE KEY CELLULAR FUNCTIONS, SUCH AS SELF-RENEWAL, PROLIFERATION, BIASED LINEAGE COMMITMENT, AND DIFFERENTIATION. ADVANCES IN NEXT-GENERATION SEQUENCING LED TO THE IDENTIFICATION OF MULTIPLE MUTATIONS IN MYELOID NEOPLASMS, AND MANY NEW GENE MUTATIONS WERE IDENTIFIED AS KEY FACTORS IN DRIVING THE PATHOGENESIS OF MYELOID MALIGNANCIES. THE POLYCOMB PROTEIN ASXL1 WAS IDENTIFIED TO BE FREQUENTLY MUTATED IN ALL FORMS OF MYELOID MALIGNANCIES, WITH MUTATIONAL FREQUENCIES OF 20%, 43%, 10%, AND 20% IN MDS, CMML, MPN, AND AML, RESPECTIVELY. SIGNIFICANTLY, ASXL1 MUTATIONS ARE ASSOCIATED WITH A POOR PROGNOSIS IN ALL FORMS OF MYELOID MALIGNANCIES. THE FACT THAT ASXL1 MUTATIONS ARE ASSOCIATED WITH POOR PROGNOSIS IN PATIENTS WITH CMML, MDS, AND AML, POINTS TO THE POSSIBILITY THAT ASXL1 MUTATION IS A KEY FACTOR IN THE DEVELOPMENT OF MYELOID MALIGNANCIES. THIS REVIEW SUMMARIZES THE RECENT ADVANCES IN UNDERSTANDING MYELOID MALIGNANCIES WITH A SPECIFIC FOCUS ON ASXL1 MUTATIONS. 2023 5 957 31 CHRONIC MYELOMONOCYTIC LEUKAEMIA: A CONCISE CLINICAL AND PATHOPHYSIOLOGICAL REVIEW. CHRONIC MYELOMONOCYTIC LEUKAEMIA (CMML) IS A CLONAL HAEMATOPOIETIC STEM CELL DISORDER WITH MYELODYSPLASTIC AND MYELOPROLIFERATIVE OVERLAP FEATURES, AND AN INHERENT TENDENCY TO TRANSFORM TO ACUTE MYELOID LEUKAEMIA. APPROXIMATELY 30% OF PATIENTS PRESENT WITH CLONAL CYTOGENETIC ABNORMALITIES, WHILE ALMOST 90% HAVE MOLECULAR ABERRATIONS INVOLVING EPIGENETIC REGULATION, THE SPLICEOSOME COMPONENT MACHINERY, TUMOUR SUPPRESSOR GENES AND TRANSCRIPTION FACTORS/REGULATORS. NUMEROUS PROGNOSTIC MODELS EXIST FOR CMML, WITH MORE RECENT MODELS INCORPORATING PROGNOSTIC MUTATIONS, SUCH AS THOSE INVOLVING ASXL1. OTHER VARIABLES THAT SEEM TO CONSISTENTLY AFFECT OUTCOMES INCLUDE THE DEGREE OF LEUCOCYTOSIS/MONOCYTOSIS, ANAEMIA AND THROMBOCYTOPENIA. ALLOGENEIC STEM CELL TRANSPLANT REMAINS THE ONLY CURATIVE OPTION FOR CMML, WHILE HYPOMETHYLATING AGENTS CAN BE USED FOR TRANSPLANT-INELIGIBLE PATIENTS OR THOSE WITHOUT SUITABLE STEM CELL SOURCES. TARGETING BIOLOGICAL PATHWAYS ACTIVATED IN CMML OFFERS POTENTIAL HOPE FOR MORE EFFECTIVE AND LESS TOXIC THERAPIES. 2014 6 4442 39 MOLECULAR GENETICS OF MDS/MPN OVERLAP SYNDROMES. THE MYELODYSPLASTIC/MYELOPROLIFERATIVE NEOPLASMS (MDS/MPN) ARE A HETEROGENOUS GROUP OF MYELOID MALIGNANCIES HALLMARKED BY CLINICOPATHOLOGIC FEATURES THAT OVERLAP WITH MYELODYSPLASTIC SYNDROMES AND MYELOPROLIFERATIVE NEOPLASMS. FORMALLY RECOGNIZED BY THE WORLD HEALTH ORGANIZATION, THIS GROUP INCLUDES THE ENTITIES CHRONIC MYELOMONOCYTIC LEUKEMIA, JUVENILE MYELOMONOCYTIC LEUKEMIA, ATYPICAL CHRONIC MYELOID LEUKEMIA, MDS/MPN WITH RING SIDEROBLASTS AND THROMBOCYTOSIS AND MDS/MPN, UNCLASSIFIABLE. ADVANCEMENTS IN NEXT GENERATION SEQUENCING HAVE BEGUN TO UNRAVEL THE MOLECULAR UNDERPINNINGS OF THESE DISEASES, IDENTIFYING AN ARRAY OF RECURRENTLY MUTATED GENES INVOLVED IN EPIGENETIC REGULATION, RNA SPLICING, TRANSCRIPTION, AND CELL SIGNALING. DESPITE MOLECULAR OVERLAP WITH OTHER MYELOID MALIGNANCIES, EACH ENTITY DISPLAYS A UNIQUE SPECTRUM OF SOMATIC MUTATIONS SUPPORTING THEIR UNIQUE PATHOBIOLOGY AND CLINICAL FEATURES. IMPORTANTLY, MOLECULAR PROFILING IS BECOMING AN INTEGRAL TOOL UTILIZED IN ROUTINE CLINICAL PRACTICE. THIS REVIEW SUMMARIZES OUR CURRENT UNDERSTANDING OF THE MOLECULAR PATHOGENESIS OF OVERLAP SYNDROMES AND DETAILS THE IMPACT OF SOMATIC MUTATIONS IN DIAGNOSTIC, PROGNOSTIC, AND THERAPEUTIC DECISION-MAKING. 2020 7 2956 34 GENETIC AND EPIGENETIC FACTORS INTERACTING WITH CLONAL HEMATOPOIESIS RESULTING IN CHRONIC MYELOMONOCYTIC LEUKEMIA. PURPOSE OF REVIEW: SINCE 2016, THE WHO HAS RECOGNIZED THE SIGNIFICANT PHENOTYPIC HETEROGENEITY OF CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) AS A MYELODYSPLASTIC SYNDROME/MYELOPROLIFERATIVE NEOPLASM (MDS/MPN) OVERLAP DISEASE. ALTHOUGH SHARING MANY SOMATIC MUTATIONS WITH MDS AND MPN, THE PURPOSE OF THIS REVIEW IS TO PUT RECENT BIOLOGICAL FINDINGS OF CMML IN THE CONTEXT OF EVOLUTIONARY THEORY, HIGHLIGHTING IT AS A DISTINCT EVOLUTIONARY TRAJECTORY OCCURRING IN THE CONTEXT OF CLONAL HEMATOPOIESIS. RECENT FINDINGS: CLONAL HEMATOPOIESIS OF INDETERMINATE POTENTIAL (CHIP), WITH A MUTATIONAL SPECTRUM AND PREVALENCE CORRELATED WITH AGE, HAS BEEN DEFINED. ENRICHED IN DNMT3A, TET2, AND ASXL1 MUTATIONS, CLONAL EVOLUTION CAN PROGRESS INTO VARIOUS EVOLUTIONARY TRAJECTORIES INCLUDING CMML. IMPACT OF FOUNDER MUTATIONS (PRIMARILY TET2) ON INCREASED HEMATOPOIETIC STEM CELL FITNESS HAS BEEN WELL CHARACTERIZED. EPISTATIC INTERACTIONS BETWEEN MUTATIONS AND EPIGENETIC EVENTS HAVE BEEN EXPLORED, BOTH IN CMML AND ITS PEDIATRIC COUNTERPART JUVENILE MYELOMONOCYTIC LEUKEMIA, INCLUDING CMML TRANSFORMATION TO ACUTE MYELOID LEUKEMIA. TOGETHER, THESE FINDINGS HAVE CONTRIBUTED SIGNIFICANTLY TOWARD CMML EVOLUTIONARY DYNAMICS. SUMMARY: DESPITE RELATIVELY FEW 'DRIVER' MUTATIONS IN CMML, EVOLUTIONARY DEVELOPMENT OF CHRONIC LEUKEMIA REMAINS INCOMPLETELY UNDERSTOOD. RECENT STUDIES HAVE SHED LIGHT ON THE IMPORTANCE OF STUDYING EPIGENETIC CONSEQUENCES OF MUTATIONS AND EPISTASIS BETWEEN KEY MUTATIONS TO BETTER UNDERSTAND CLONAL ARCHITECTURE AND EVOLUTIONARY DYNAMICS. 2020 8 2981 34 GENETIC COMPLEXITY OF CHRONIC MYELOMONOCYTIC LEUKEMIA. IN RECENT YEARS CMML HAS RECEIVED INCREASED ATTENTION AS THE MOST COMMONLY OBSERVED MDS/MPN OVERLAP SYNDROME. RENEWED INTEREST HAS OCCURRED IN PART DUE TO WIDESPREAD ADOPTION OF NEXT-GENERATION SEQUENCING PANELS THAT HELP RENDER THE DIAGNOSIS IN THE ABSENCE OF MORPHOLOGIC DYSPLASIA. ALTHOUGH MOST CMML PATIENTS EXHIBIT SOMATIC MUTATIONS IN EPIGENETIC MODIFIERS, SPLICEOSOME COMPONENTS, TRANSCRIPTION FACTORS AND SIGNAL TRANSDUCTION GENES, IT IS INCREASINGLY CLEAR THAT A SMALL SUBSET HARBORS AN INHERITED PREDISPOSITION TO CMML AND OTHER MYELOID NEOPLASMS. MORE INTRIGUING IS THE FACT THAT THE MUTATIONAL SPECTRUM OBSERVED IN CMML IS FOUND IN OTHER TYPES OF MYELOID LEUKEMIAS, BEGGING THE QUESTION OF HOW SIMILAR GENETIC BACKGROUNDS CAN LEAD TO SUCH DIVERGENT CLINICAL PHENOTYPES. IN THIS REVIEW WE PRESENT A CONTEMPORARY SNAPSHOT OF THE GENETIC COMPLEXITY INHERENT TO CMML, EXPLORE THE RELATIONSHIP BETWEEN GENOTYPE-PHENOTYPE AND PRESENT A STEPWISE MODEL OF CMML PATHOGENESIS AND PROGRESSION. 2021 9 4555 55 MUTATIONAL SPECTRUM ANALYSIS OF CHRONIC MYELOMONOCYTIC LEUKEMIA INCLUDES GENES ASSOCIATED WITH EPIGENETIC REGULATION: UTX, EZH2, AND DNMT3A. CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML), A MYELODYSPLASTIC/MYELOPROLIFERATIVE NEOPLASM, IS CHARACTERIZED BY MONOCYTIC PROLIFERATION, DYSPLASIA, AND PROGRESSION TO ACUTE MYELOID LEUKEMIA. CMML HAS BEEN ASSOCIATED WITH SOMATIC MUTATIONS IN DIVERSE RECENTLY IDENTIFIED GENES. WE ANALYZED 72 WELL-CHARACTERIZED PATIENTS WITH CMML (N = 52) AND CMML-DERIVED ACUTE MYELOID LEUKEMIA (N = 20) FOR RECURRENT CHROMOSOMAL ABNORMALITIES WITH THE USE OF ROUTINE CYTOGENETICS AND SINGLE NUCLEOTIDE POLYMORPHISM ARRAYS ALONG WITH COMPREHENSIVE MUTATIONAL SCREENING. CYTOGENETIC ABERRATIONS WERE PRESENT IN 46% OF CASES, WHEREAS SINGLE NUCLEOTIDE POLYMORPHISM ARRAY INCREASED THE DIAGNOSTIC YIELD TO 60%. AT LEAST 1 MUTATION WAS FOUND IN 86% OF ALL CASES; NOVEL UTX, DNMT3A, AND EZH2 MUTATIONS WERE FOUND IN 8%, 10%, AND 5.5% OF PATIENTS, RESPECTIVELY. TET2 MUTATIONS WERE PRESENT IN 49%, ASXL1 IN 43%, CBL IN 14%, IDH1/2 IN 4%, KRAS IN 7%, NRAS IN 4%, AND JAK2 V617F IN 1% OF PATIENTS. VARIOUS MUTANT GENOTYPE COMBINATIONS WERE OBSERVED, INDICATING MOLECULAR HETEROGENEITY IN CMML. OUR RESULTS SUGGEST THAT MOLECULAR DEFECTS AFFECTING DISTINCT PATHWAYS CAN LEAD TO SIMILAR CLINICAL PHENOTYPES. 2011 10 1039 41 CLINICAL AND BIOLOGICAL IMPLICATIONS OF DRIVER MUTATIONS IN MYELODYSPLASTIC SYNDROMES. MYELODYSPLASTIC SYNDROMES (MDS) ARE A HETEROGENEOUS GROUP OF CHRONIC HEMATOLOGICAL MALIGNANCIES CHARACTERIZED BY DYSPLASIA, INEFFECTIVE HEMATOPOIESIS AND A VARIABLE RISK OF PROGRESSION TO ACUTE MYELOID LEUKEMIA. SEQUENCING OF MDS GENOMES HAS IDENTIFIED MUTATIONS IN GENES IMPLICATED IN RNA SPLICING, DNA MODIFICATION, CHROMATIN REGULATION, AND CELL SIGNALING. WE SEQUENCED 111 GENES ACROSS 738 PATIENTS WITH MDS OR CLOSELY RELATED NEOPLASMS (INCLUDING CHRONIC MYELOMONOCYTIC LEUKEMIA AND MDS-MYELOPROLIFERATIVE NEOPLASMS) TO EXPLORE THE ROLE OF ACQUIRED MUTATIONS IN MDS BIOLOGY AND CLINICAL PHENOTYPE. SEVENTY-EIGHT PERCENT OF PATIENTS HAD 1 OR MORE ONCOGENIC MUTATIONS. WE IDENTIFY COMPLEX PATTERNS OF PAIRWISE ASSOCIATION BETWEEN GENES, INDICATIVE OF EPISTATIC INTERACTIONS INVOLVING COMPONENTS OF THE SPLICEOSOME MACHINERY AND EPIGENETIC MODIFIERS. COUPLED WITH INFERENCES ON SUBCLONAL MUTATIONS, THESE DATA SUGGEST A HYPOTHESIS OF GENETIC "PREDESTINATION," IN WHICH EARLY DRIVER MUTATIONS, TYPICALLY AFFECTING GENES INVOLVED IN RNA SPLICING, DICTATE FUTURE TRAJECTORIES OF DISEASE EVOLUTION WITH DISTINCT CLINICAL PHENOTYPES. DRIVER MUTATIONS HAD EQUIVALENT PROGNOSTIC SIGNIFICANCE, WHETHER CLONAL OR SUBCLONAL, AND LEUKEMIA-FREE SURVIVAL DETERIORATED STEADILY AS NUMBERS OF DRIVER MUTATIONS INCREASED. THUS, ANALYSIS OF ONCOGENIC MUTATIONS IN LARGE, WELL-CHARACTERIZED COHORTS OF PATIENTS ILLUSTRATES THE INTERCONNECTIONS BETWEEN THE CANCER GENOME AND DISEASE BIOLOGY, WITH CONSIDERABLE POTENTIAL FOR CLINICAL APPLICATION. 2013 11 4471 42 MOLECULAR PATHOGENESIS OF ATYPICAL CML, CMML AND MDS/MPN-UNCLASSIFIABLE. ACCORDING TO THE 2008 WHO CLASSIFICATION, THE CATEGORY OF MYELODYSPLASTIC/MYELOPROLIFERATIVE NEOPLASMS (MDS/MPN) INCLUDES ATYPICAL CHRONIC MYELOID LEUKAEMIA (ACML), CHRONIC MYELOMONOCYTIC LEUKAEMIA (CMML), MDS/MPN-UNCLASSIFIABLE (MDS/MPN-U), JUVENILE MYELOMONOCYTIC LEUKAEMIA (JMML) AND A "PROVISIONAL" ENTITY, REFRACTORY ANAEMIA WITH RING SIDEROBLASTS AND THROMBOCYTOSIS (RARS-T). THE REMARKABLE PROGRESS IN OUR UNDERSTANDING OF THE SOMATIC PATHOGENESIS OF MDS/MPN HAS MADE IT CLEAR THAT THERE IS CONSIDERABLE OVERLAP AMONG THESE DISEASES AT THE MOLECULAR LEVEL, AS WELL AS LAYERS OF UNEXPECTED COMPLEXITY. DEREGULATION OF SIGNALLING PLAYS AN IMPORTANT ROLE IN MANY CASES, AND IS CLEARLY LINKED TO MORE HIGHLY PROLIFERATIVE DISEASE. OTHER MUTATIONS AFFECT A RANGE OF OTHER ESSENTIAL, INTERRELATED CELLULAR MECHANISMS, INCLUDING EPIGENETIC REGULATION, RNA SPLICING, TRANSCRIPTION, AND DNA DAMAGE RESPONSE. THE VARIOUS COMBINATIONS OF MUTATIONS INDICATE A MULTI-STEP PATHOGENESIS, WHICH LIKELY CONTRIBUTES TO THE MARKED CLINICAL HETEROGENEITY OF THESE DISORDERS. THE DELINEATION OF COMPLEX CLONAL ARCHITECTURES MAY SERVE AS THE CORNERSTONE FOR THE IDENTIFICATION OF NOVEL THERAPEUTIC TARGETS AND LEAD TO BETTER PATIENT OUTCOMES. THIS REVIEW SUMMARIZES SOME OF THE CURRENT KNOWLEDGE OF MOLECULAR PATHOGENETIC LESIONS IN THE MDS/MPN SUBTYPES THAT ARE SEEN IN ADULTS: ATYPICAL CML, CMML AND MDS/MPN-U. 2015 12 4485 38 MOLECULAR SIMILARITY BETWEEN MYELODYSPLASTIC FORM OF CHRONIC MYELOMONOCYTIC LEUKEMIA AND REFRACTORY ANEMIA WITH RING SIDEROBLASTS. CHRONIC MYELOMONOCYTIC LEUKEMIA IS SIMILAR TO BUT A SEPARATE ENTITY FROM BOTH MYELOPROLIFERATIVE NEOPLASMS AND MYELODYSPLASTIC SYNDROMES, AND SHOWS EITHER MYELOPROLIFERATIVE OR MYELODYSPLASTIC FEATURES. WE ASK WHETHER THIS DISTINCTION MAY HAVE A MOLECULAR BASIS. WE ESTABLISHED THE GENE EXPRESSION PROFILES OF 39 SAMPLES OF CHRONIC MYELOMONOCYTIC LEUKEMIA (INCLUDING 12 CD34-POSITIVE) AND 32 CD34-POSITIVE SAMPLES OF MYELODYSPLASTIC SYNDROMES BY USING AFFYMETRIX MICROARRAYS, AND STUDIED THE STATUS OF 18 GENES BY SANGER SEQUENCING AND ARRAY-COMPARATIVE GENOMIC HYBRIDIZATION IN 53 SAMPLES. ANALYSIS OF 12 MRNAS FROM CHRONIC MYELOMONOCYTIC LEUKEMIA ESTABLISHED A GENE EXPRESSION SIGNATURE OF 122 PROBE SETS DIFFERENTIALLY EXPRESSED BETWEEN PROLIFERATIVE AND DYSPLASTIC CASES OF CHRONIC MYELOMONOCYTIC LEUKEMIA. AS COMPARED TO PROLIFERATIVE CASES, DYSPLASTIC CASES OVER-EXPRESSED GENES INVOLVED IN RED BLOOD CELL BIOLOGY. WHEN APPLIED TO 32 MYELODYSPLASTIC SYNDROMES, THIS GENE EXPRESSION SIGNATURE WAS ABLE TO DISCRIMINATE REFRACTORY ANEMIAS WITH RING SIDEROBLASTS FROM REFRACTORY ANEMIAS WITH EXCESS OF BLASTS. BY COMPARING MRNAS FROM THESE TWO FORMS OF MYELODYSPLASTIC SYNDROMES WE DERIVED A SECOND GENE EXPRESSION SIGNATURE. THIS SIGNATURE SEPARATED THE MYELODYSPLASTIC AND MYELOPROLIFERATIVE FORMS OF CHRONIC MYELOMONOCYTIC LEUKEMIAS. THESE RESULTS WERE VALIDATED USING TWO INDEPENDENT GENE EXPRESSION DATA SETS. WE FOUND THAT MYELODYSPLASTIC CHRONIC MYELOMONOCYTIC LEUKEMIAS ARE CHARACTERIZED BY MUTATIONS IN TRANSCRIPTION/EPIGENETIC REGULATORS (ASXL1, RUNX1, TET2) AND SPLICING GENES (SRSF2) AND THE ABSENCE OF MUTATIONS IN SIGNALING GENES. MYELODYSPLASTIC CHRONIC MYELOMONOCYTIC LEUKEMIAS AND REFRACTORY ANEMIAS WITH RING SIDEROBLASTS SHARE A COMMON EXPRESSION PROGRAM SUGGESTING THEY ARE PART OF A CONTINUUM, WHICH IS NOT TOTALLY EXPLAINED BY THEIR SIMILAR BUT NOT, HOWEVER, IDENTICAL MUTATION SPECTRUM. 2013 13 1266 38 CYTOGENETIC AND MOLECULAR ABNORMALITIES IN CHRONIC MYELOMONOCYTIC LEUKEMIA. CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) IS A CLONAL STEM CELL DISORDER ASSOCIATED WITH PERIPHERAL BLOOD MONOCYTOSIS AND AN INHERENT TENDENCY TO TRANSFORM TO ACUTE MYELOID LEUKEMIA. CMML HAS OVERLAPPING FEATURES OF MYELODYSPLASTIC SYNDROMES AND MYELOPROLIFERATIVE NEOPLASMS. CLONAL CYTOGENETIC CHANGES ARE SEEN IN ~30%, WHEREAS GENE MUTATIONS ARE SEEN IN >90% OF PATIENTS. COMMON CYTOGENETIC ABNORMALITIES INCLUDE; TRISOMY 8, -Y, -7/DEL(7Q), TRISOMY 21 AND DEL(20Q), WITH THE MAYO-FRENCH RISK STRATIFICATION EFFECTIVELY RISK STRATIFYING PATIENTS BASED ON CYTOGENETIC ABNORMALITIES. GENE MUTATIONS FREQUENTLY INVOLVE EPIGENETIC REGULATORS (TET2 ~60%), MODULATORS OF CHROMATIN (ASXL1 ~40%), SPLICEOSOME COMPONENTS (SRSF2 ~50%), TRANSCRIPTION FACTORS (RUNX1 ~15%) AND SIGNAL PATHWAYS (RAS ~30%, CBL ~15%). OF THESE, THUS FAR, ONLY NONSENSE AND FRAMESHIFT ASXL1 MUTATIONS HAVE BEEN SHOWN TO NEGATIVELY IMPACT OVERALL SURVIVAL. THIS HAS RESULTED IN THE DEVELOPMENT OF CONTEMPORARY, MOLECULARLY INTEGRATED (INCLUSIVE OF ASXL1 MUTATIONS) CMML PROGNOSTIC MODELS, INCLUDING MOLECULAR MAYO MODEL AND THE GROUPE FRANCAIS DES MYELODYSPLASIES MODEL. BETTER UNDERSTANDING OF THE PREVALENT GENETIC AND EPIGENETIC DYSREGULATION HAS RESULTED IN EMERGING TARGETED TREATMENT OPTIONS FOR SOME PATIENTS. THE DEVELOPMENT OF AN INTEGRATED (CYTOGENETIC AND MOLECULAR) PROGNOSTIC MODEL ALONG WITH CMML-SPECIFIC RESPONSE ASSESSMENT CRITERIA ARE MUCH NEEDED FUTURE GOALS. 2016 14 4566 27 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. 2021 15 962 38 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 ( APPROXIMATELY 60%), SRSF2 ( APPROXIMATELY 50%), ASXL1 ( APPROXIMATELY 40%), AND RAS ( APPROXIMATELY 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 FRANCAIS DES MYELODYSPLASIES 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. 2016 16 5284 29 PROPOSALS FOR CLINICAL TRIALS IN CHRONIC MYELOMONOCYTIC LEUKEMIA. CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) IS A CLONAL HEMATOLOGIC MALIGNANCY OF MOSTLY OLDER INDIVIDUALS THAT EXHIBITS BOTH MYELODYSPLASTIC AND MYELOPROLIFERATIVE FEATURES. CMML PRESENTATION AND OUTCOME ARE VARIABLE, REFLECTING GENETIC AND CLINICAL HETEROGENEITY. HYPOMETHYLATING AGENTS ARE THE MAINSTAY OF THERAPY BUT INDUCE COMPLETE REMISSIONS IN LESS THAN 20% OF PATIENTS AND DO NOT PROLONG SURVIVAL COMPARED TO HYDROXYUREA. ALLOGENEIC STEM CELL TRANSPLANT (ASCT) IS POTENTIALLY CURATIVE, BUT FEW PATIENTS QUALIFY DUE TO ADVANCED AGE AND/OR COMORBIDITIES. WORK OF THE PAST SEVERAL YEARS HAS IDENTIFIED KEY MOLECULAR PATHWAYS THAT DRIVE DISEASE PROLIFERATION AND TRANSFORMATION TO ACUTE LEUKEMIA, INCLUDING JAK/STAT AND MAPK SIGNALING AND EPIGENETIC DYSREGULATION. THERE IS INCREASINGLY COMPELLING EVIDENCE THAT INFLAMMATION IS A MAJOR DRIVER OF CMML PROGRESSION. THUS FAR HOWEVER, THIS MECHANISTIC KNOWLEDGE HAS NOT YET BEEN TRANSLATED INTO IMPROVED OUTCOMES, SUGGESTING THAT FUNDAMENTALLY NEW APPROACHES ARE REQUIRED. IN THIS REVIEW, WE DISCUSS THE DISEASE COURSE, NEW CLASSIFICATIONS, AND CURRENT TREATMENT LANDSCAPE OF CMML. WE REVIEW ONGOING CLINICAL STUDIES AND DISCUSS OPTIONS FOR RATIONALLY BASED FUTURE CLINICAL TRIALS. 2023 17 536 35 ASXL1 MUTATIONS PREDICT INFERIOR MOLECULAR RESPONSE TO NILOTINIB TREATMENT IN CHRONIC MYELOID LEUKEMIA. GENE MUTATIONS INDEPENDENT OF BCR::ABL1 HAVE BEEN IDENTIFIED IN NEWLY DIAGNOSED PATIENTS WITH CHRONIC MYELOID LEUKEMIA (CML) IN CHRONIC PHASE, WHEREBY MUTATIONS IN EPIGENETIC MODIFIER GENES WERE MOST COMMON. THESE FINDINGS PROMPTED THE SYSTEMATIC ANALYSIS OF PREVALENCE, DYNAMICS, AND PROGNOSTIC SIGNIFICANCE OF SUCH MUTATIONS, IN A CLINICALLY WELL-CHARACTERIZED PATIENT POPULATION OF 222 CML PATIENTS FROM THE TIGER STUDY (CML-V) BY TARGETED NEXT-GENERATION SEQUENCING COVERING 54 MYELOID LEUKEMIA-ASSOCIATED GENES. IN TOTAL, 53/222 CML PATIENTS (24%) CARRIED 60 MUTATIONS AT DIAGNOSIS WITH ASXL1 BEING MOST COMMONLY AFFECTED (N = 20). TO STUDY MUTATION DYNAMICS, LONGITUDINAL DEEP SEQUENCING ANALYSIS OF SERIAL SAMPLES WAS PERFORMED IN 100 PATIENTS AFTER 12, 24, AND 36 MONTHS OF THERAPY. TYPICAL PATTERNS OF CLONAL EVOLUTION INCLUDED ERADICATION, PERSISTENCE, AND EMERGENCE OF MUTATED CLONES. PATIENTS CARRYING AN ASXL1 MUTATION AT DIAGNOSIS SHOWED A LESS FAVORABLE MOLECULAR RESPONSE TO NILOTINIB TREATMENT, AS A MAJOR MOLECULAR RESPONSE (MMR) WAS ACHIEVED LESS FREQUENTLY AT MONTH 12, 18, AND 24 COMPARED TO ALL OTHER PATIENTS. PATIENTS WITH ASXL1 MUTATIONS WERE ALSO YOUNGER AND MORE FREQUENTLY FOUND IN THE HIGH RISK CATEGORY, SUGGESTING A CENTRAL ROLE OF CLONAL EVOLUTION ASSOCIATED WITH ASXL1 MUTATIONS IN CML PATHOGENESIS. 2022 18 1043 42 CLINICAL CHARACTERISTICS AND WHOLE EXOME/TRANSCRIPTOME SEQUENCING OF COEXISTING CHRONIC MYELOID LEUKEMIA AND MYELOFIBROSIS. MYELOPROLIFERATIVE NEOPLASMS (MPNS) ARE CLONAL HEMATOPOIETIC STEM CELL (HSC) DISORDERS THAT CAN BE CLASSIFIED ON THE BASIS OF GENETIC, CLINICAL, PHENOTYPIC FEATURES. GENETIC LESIONS SUCH AS JAK2 MUTATIONS AND BCR-ABL TRANSLOCATION ARE OFTEN MUTUALLY EXCLUSIVE IN MPN PATIENTS AND LEAD TO ESSENTIAL THROMBOCYTHEMIA, POLYCYTHEMIA VERA, OR MYELOFIBROSIS OR CHRONIC MYELOID LEUKEMIA, RESPECTIVELY. NEVERTHELESS, COEXISTENCE OF THESE GENETIC ABERRATIONS IN THE SAME PATIENT HAS BEEN REPORTED. WHETHER THESE ABERRATIONS OCCUR IN THE SAME STEM CELL OR A DIFFERENT CELL IS UNCLEAR, BUT AN UNSTABLE GENOME IN THE HSCS SEEMS TO BE THE COMMON ANTECEDENT. IN AN EFFORT TO CHARACTERIZE THE UNDERLYING GENETIC EVENTS THAT MIGHT CONTRIBUTE TO THE APPEARANCE OF MORE THAN ONE MPN IN A PATIENT, WE STUDIED NEOPLASTIC CELLS FROM PATIENTS WITH DUAL MPNS BY NEXT-GENERATION SEQUENCING. WE OBSERVED THAT MOST PATIENTS WITH TWO MPNS HARBORED MUTATIONS IN GENES KNOWN TO CONTRIBUTE TO CLONAL HEMATOPOIESIS THROUGH ALTERED EPIGENETIC REGULATION SUCH AS TET2, ASXL1/2, SRSF2, AND IDH2 AT VARYING FREQUENCIES (1%-47%). IN ADDITION, WE FOUND THAT SOME PATIENTS ALSO HARBORED ONCOGENIC MUTATIONS IN N/KRAS, TP53, BRAF, EZH2, AND GNAS AT LOW FREQUENCIES, WHICH PROBABLY REPRESENT CLONAL EVOLUTION. THESE FINDINGS SUPPORT THE HYPOTHESIS THAT HEMATOPOIETIC CELLS FROM MPN PATIENTS HARBOR MULTIPLE GENETIC ABERRATIONS, SOME OF WHICH CAN CONTRIBUTE TO CLONAL DOMINANCE. ACQUIRING MUTATIONS IN JAK2/CALR/MPL OR THE BCR-ABL TRANSLOCATION PROBABLY DRIVE THE ONCOGENIC PHENOTYPE TOWARDS A SPECIFIC MPN. FURTHER, WE PROPOSE THAT THE ACQUISITION OF BCR-ABL IN THESE PATIENTS IS FREQUENTLY A SECONDARY EVENT RESULTING FROM AN UNSTABLE GENOME. 2017 19 5782 34 SPLICING ANOMALIES IN MYELOPROLIFERATIVE NEOPLASMS: PAVING THE WAY FOR NEW THERAPEUTIC VENUES. SINCE THE DISCOVERY OF SPLICEOSOME MUTATIONS IN MYELOID MALIGNANCIES, ABNORMAL PRE-MRNA SPLICING, WHICH HAS BEEN WELL STUDIED IN VARIOUS CANCERS, HAS ATTRACTED NOVEL INTEREST IN HEMATOLOGY. HOWEVER, DESPITE THE COMMON OCCURRENCE OF SPLICEOSOME MUTATIONS IN MYELO-PROLIFERATIVE NEOPLASMS (MPN), NOT MUCH IS KNOWN REGARDING THE CHARACTERIZATION AND MECHANISMS OF SPLICING ANOMALIES IN MPN. IN THIS ARTICLE, WE REVIEW THE CURRENT SCIENTIFIC LITERATURE REGARDING "SPLICING AND MYELOPROLIFERATIVE NEOPLASMS". WE FIRST ANALYSE THE CLINICAL SERIES REPORTING SPLICEOSOME MUTATIONS IN MPN AND THEIR CLINICAL CORRELATES. WE THEN PRESENT THE CURRENT KNOWLEDGE ABOUT MOLECULAR MECHANISMS BY WHICH THESE MUTATIONS PARTICIPATE IN THE PATHOGENESIS OF MPN OR OTHER MYELOID MALIGNANCIES. BESIDE SPLICEOSOME MUTATIONS, SPLICING ANOMALIES HAVE BEEN DESCRIBED IN MYELOPROLIFERATIVE NEOPLASMS, AS WELL AS IN ACUTE MYELOID LEUKEMIAS, A DREADFUL COMPLICATION OF THESE CHRONIC DISEASES. BASED ON SPLICING ANOMALIES REPORTED IN CHRONIC MYELOGENOUS LEUKEMIA AS WELL AS IN ACUTE LEUKEMIA, AND THE MECHANISMS PRESIDING SPLICING DEREGULATION, WE PROPOSE THAT ABNORMAL SPLICING PLAYS A MAJOR ROLE IN THE EVOLUTION OF MYELOPROLIFERATIVE NEOPLASMS AND MAY BE THE TARGET OF SPECIFIC THERAPEUTIC STRATEGIES. 2020 20 2237 36 EPIGENETIC MODIFIERS IN MYELOID MALIGNANCIES: THE ROLE OF HISTONE DEACETYLASE INHIBITORS. MYELOID HEMATOLOGICAL MALIGNANCIES ARE CLONAL BONE MARROW NEOPLASMS, COMPRISING OF ACUTE MYELOID LEUKEMIA (AML), THE MYELODYSPLASTIC SYNDROMES (MDS), CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML), THE MYELOPROLIFERATIVE NEOPLASMS (MPN) AND SYSTEMIC MASTOCYTOSIS (SM). THE FIELD OF EPIGENETIC REGULATION OF NORMAL AND MALIGNANT HEMATOPOIESIS IS RAPIDLY GROWING. IN RECENT YEARS, HETEROZYGOUS SOMATIC MUTATIONS IN GENES ENCODING EPIGENETIC REGULATORS HAVE BEEN FOUND IN ALL SUBTYPES OF MYELOID MALIGNANCIES, SUPPORTING THE RATIONALE FOR TREATMENT WITH EPIGENETIC MODIFIERS. HISTONE DEACETYLASE INHIBITORS (HDACI) ARE EPIGENETIC MODIFIERS THAT, IN VITRO, HAVE BEEN SHOWN TO INDUCE GROWTH ARREST, APOPTOTIC OR AUTOPHAGIC CELL DEATH, AND TERMINAL DIFFERENTIATION OF MYELOID TUMOR CELLS. THESE EFFECTS WERE OBSERVED BOTH AT THE BULK TUMOR LEVEL AND IN THE MOST IMMATURE CD34(+)38(-) CELL COMPARTMENTS CONTAINING THE LEUKEMIC STEM CELLS. THUS, THERE IS A STRONG RATIONALE SUPPORTING HDACI THERAPY IN MYELOID MALIGNANCIES. HOWEVER, DESPITE INITIAL PROMISING RESULTS IN PHASE I TRIALS, HDACI IN MONOTHERAPY AS WELL AS IN COMBINATION WITH OTHER DRUGS, HAVE FAILED TO IMPROVE RESPONSES OR SURVIVAL. THIS REVIEW PROVIDES AN OVERVIEW OF THE RATIONALE FOR HDACI IN MYELOID MALIGNANCIES, CLINICAL RESULTS AND SPECULATIONS ON WHY CLINICAL TRIALS HAVE THUS FAR NOT MET THE EXPECTATIONS, AND HOW THIS MAY BE IMPROVED IN THE FUTURE. 2018