1 6780 99 [BLASTIC PLASMACYTOID DENDRITIC CELL NEOPLASM ACCOMPANIED BY CHRONIC MYELOMONOCYTIC LEUKEMIA SUCCESSFULLY TREATED WITH AZACITIDINE]. BLASTIC PLASMACYTOID DENDRITIC CELL NEOPLASM (BPDCN) IS A RARE DISEASE THAT DEVELOPS WITH A SKIN LESION AND IS OFTEN ACCOMPANIED BY LEUKEMIC TRANSFORMATION. THE NORMAL COUNTERPARTS OF BPDCN TUMOR CELLS ARE PROGENITORS OF PLASMACYTOID DENDRITIC CELLS, WHEREAS THE ORIGINS ARE THOUGHT TO BE HEMATOPOIETIC STEM CELLS. APPROXIMATELY 10%-20% OF BPDCN PATIENTS DEVELOP OTHER HEMATOLOGIC MALIGNANCIES, INCLUDING CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML). MUTATIONS IN EPIGENETIC REGULATORS ARE FREQUENTLY OBSERVED IN BOTH BPDCN AND CMML TUMORS. AZACITIDINE, A DRUG THAT TARGETS EPIGENETIC DYSREGULATION, IS KNOWN TO BE AN EFFECTIVE TREATMENT FOR CMML. HOWEVER, IT HAS BEEN USED IN FEW BPDCN PATIENTS. HERE, WE REPORT A BPDCN PATIENT WITH SKIN LESIONS, BONE MARROW INFILTRATION, AND LYMPHADENOPATHY. CMML ALSO DEVELOPED DURING THE COURSE OF BPDCN. AZACITIDINE HAD POSITIVE EFFECTS ON CMML; HOWEVER, BPDCN AGGRESSIVELY RELAPSED DURING TREATMENT. TWO TET2 MUTATIONS WERE FOUND IN BOTH BPDCN AND CMML TUMORS; ONE OF WHICH WAS COMMONLY IDENTIFIED IN BOTH TUMORS. 2018 2 2277 33 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 3 4557 22 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 4 957 26 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 5 1070 29 CLONAL ARCHITECTURE OF CHRONIC MYELOMONOCYTIC LEUKEMIAS. GENOMIC STUDIES IN CHRONIC MYELOID MALIGNANCIES, INCLUDING MYELOPROLIFERATIVE NEOPLASMS (MPN), MYELODYSPLASTIC SYNDROMES (MDS), AND MPN/MDS, HAVE IDENTIFIED COMMON MUTATIONS IN GENES ENCODING SIGNALING, EPIGENETIC, TRANSCRIPTION, AND SPLICING FACTORS. IN THE PRESENT STUDY, WE INTERROGATED THE CLONAL ARCHITECTURE BY MUTATION-SPECIFIC DISCRIMINATION ANALYSIS OF SINGLE-CELL-DERIVED COLONIES IN 28 PATIENTS WITH CHRONIC MYELOMONOCYTIC LEUKEMIAS (CMML), THE MOST FREQUENT MPN/MDS. THIS ANALYSIS REVEALS A LINEAR ACQUISITION OF THE STUDIED MUTATIONS WITH LIMITED BRANCHING THROUGH LOSS OF HETEROZYGOSITY. SERIAL ANALYSIS OF UNTREATED AND TREATED SAMPLES DEMONSTRATES A DYNAMIC ARCHITECTURE ON WHICH MOST CURRENT THERAPEUTIC APPROACHES HAVE LIMITED EFFECTS. THE MAIN DISEASE CHARACTERISTICS ARE EARLY CLONAL DOMINANCE, ARISING AT THE CD34(+)/CD38(-) STAGE OF HEMATOPOIESIS, AND GRANULOMONOCYTIC DIFFERENTIATION SKEWING OF MULTIPOTENT AND COMMON MYELOID PROGENITORS. COMPARISON OF CLONAL EXPANSIONS OF TET2 MUTATIONS IN MDS, MPN, AND CMML, TOGETHER WITH FUNCTIONAL INVALIDATION OF TET2 IN SORTED PROGENITORS, SUGGESTS A CAUSATIVE LINK BETWEEN EARLY CLONAL DOMINANCE AND SKEWED GRANULOMONOCYTIC DIFFERENTIATION. ALTOGETHER, EARLY CLONAL DOMINANCE MAY DISTINGUISH CMML FROM OTHER CHRONIC MYELOID NEOPLASMS WITH SIMILAR GENE MUTATIONS. 2013 6 4565 26 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 7 959 28 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 8 2956 30 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 9 4485 29 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 10 2237 41 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 11 6574 29 TREATMENT OF CHRONIC MYELOMONOCYTIC LEUKEMIA WITH 5-AZACYTIDINE: CASE REPORTS. EPIGENETIC THERAPY WITH HYPOMETHYLATING AGENT (5-AZACYTIDINE; AZA) IS COMMON IN THE MANAGEMENT OF SPECIFIC SUBTYPES OF MYELODYSPLASTIC SYNDROME (MDS), BUT THERE ARE ONLY FEW STUDIES IN CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) PATIENTS. IN THIS PAPER OUR EXPERIENCE WITH 3 CMML PATIENTS TREATED WITH AZA IS DESCRIBED. IN ONE PATIENT TRANSFUSION INDEPENDENCY WAS OBSERVED AFTER 4 TREATMENT CYCLES; IN ONE CASE A PARTIAL RESPONSE WAS RECORDED, BUT A PROGRESSION TO ACUTE MYELOID LEUKEMIA (AML) AFTER 13 AZA CYCLES HAS APPEARED. IN ONE PATIENT, AZA IN REDUCED DOSAGE WAS ADMINISTERED AS A BRIDGING TREATMENT BEFORE ALLOGENEIC STEM CELL TRANSPLANTATION (ASCT), BUT IN THE CONTROL BONE MARROW ASPIRATE (BEFORE ASCT) A PROGRESSION TO AML WAS RECORDED. FUTURE STUDIES ARE MANDATORY FOR EVALUATION OF NEW MOLECULAR AND CLINICAL FEATURES WHICH COULD PREDICT THE EFFICIENCY OF HYPOMETHYLATING AGENTS IN CMML THERAPY WITH RESPECT TO OVERALL SURVIVAL, EVENT-FREE SURVIVAL, QUALITY-ADJUSTED LIFE YEAR, AND PHARMACOECONOMY. 2012 12 1674 34 DRIVER MUTATIONS IN LEUKEMIA PROMOTE DISEASE PATHOGENESIS THROUGH A COMBINATION OF CELL-AUTONOMOUS AND NICHE MODULATION. STUDIES OF PATIENTS WITH ACUTE MYELOID LEUKEMIA (AML) HAVE LED TO THE IDENTIFICATION OF MUTATIONS THAT AFFECT DIFFERENT CELLULAR PATHWAYS. SOME OF THESE HAVE BEEN CLASSIFIED AS PRELEUKEMIC, AND A STEPWISE EVOLUTION PROGRAM WHEREBY CELLS ACQUIRE ADDITIONAL MUTATIONS HAS BEEN PROPOSED IN THE DEVELOPMENT OF AML. HOW THE TIMING OF ACQUISITION OF THESE MUTATIONS AND THEIR IMPACT ON TRANSFORMATION AND THE BONE MARROW (BM) MICROENVIRONMENT OCCURS HAS ONLY RECENTLY BEGUN TO BE INVESTIGATED. WE SHOW THAT CONSTITUTIVE AND EARLY LOSS OF THE EPIGENETIC REGULATOR, TET2, WHEN COMBINED WITH CONSTITUTIVE ACTIVATION OF FLT3, RESULTS IN TRANSFORMATION OF CHRONIC MYELOMONOCYTIC LEUKEMIA-LIKE OR MYELOPROLIFERATIVE NEOPLASM-LIKE PHENOTYPE TO AML, WHICH IS MORE PRONOUNCED IN DOUBLE-MUTANT MICE RELATIVE TO MICE CARRYING MUTATIONS IN SINGLE GENES. FURTHERMORE, WE SHOW THAT IN PRELEUKEMIC AND LEUKEMIC MICE THERE ARE ALTERATIONS IN THE BM NICHE AND SECRETED CYTOKINES, WHICH CREATES A PERMISSIVE ENVIRONMENT FOR THE GROWTH OF MUTATION-BEARING CELLS RELATIVE TO NORMAL CELLS. 2020 13 4555 30 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 14 1184 28 COOPERATIVE EPIGENETIC REMODELING BY TET2 LOSS AND NRAS MUTATION DRIVES MYELOID TRANSFORMATION AND MEK INHIBITOR SENSITIVITY. MUTATIONS IN EPIGENETIC MODIFIERS AND SIGNALING FACTORS OFTEN CO-OCCUR IN MYELOID MALIGNANCIES, INCLUDING TET2 AND NRAS MUTATIONS. CONCURRENT TET2 LOSS AND NRAS(G12D) EXPRESSION IN HEMATOPOIETIC CELLS INDUCED MYELOID TRANSFORMATION, WITH A FULLY PENETRANT, LETHAL CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML), WHICH WAS SERIALLY TRANSPLANTABLE. TET2 LOSS AND NRAS MUTATION COOPERATIVELY LED TO DECREASE IN NEGATIVE REGULATORS OF MITOGEN-ACTIVATED PROTEIN KINASE (MAPK) ACTIVATION, INCLUDING SPRY2, THEREBY CAUSING SYNERGISTIC ACTIVATION OF MAPK SIGNALING BY EPIGENETIC SILENCING. TET2/NRAS DOUBLE-MUTANT LEUKEMIA SHOWED PREFERENTIAL SENSITIVITY TO MAPK KINASE (MEK) INHIBITION IN BOTH MOUSE MODEL AND PATIENT SAMPLES. THESE DATA PROVIDE INSIGHTS INTO HOW EPIGENETIC AND SIGNALING MUTATIONS COOPERATE IN MYELOID TRANSFORMATION AND PROVIDE A RATIONALE FOR MECHANISM-BASED THERAPY IN CMML PATIENTS WITH THESE HIGH-RISK GENETIC LESIONS. 2018 15 4571 26 MYELOMONOCYTIC SKEWING IN CHRONIC MYELOMONOCYTIC LEUKEMIA: PHENOTYPIC, MOLECULAR AND BIOLOGIC FEATURES AND IMPACT ON SURVIVAL. BACKGROUND: MYELOMONOCYTIC SKEWING IS CONSIDERED AS A KEY PATHOPHYSIOLOGIC PHENOMENON IN CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML), BUT ITS PREVALENCE AND POTENTIAL CORRELATION WITH PHENOTYPIC, GENOTYPIC, AND CLINICAL FEATURES ARE POORLY DEFINED. METHODS: SKEWED DIFFERENTIATION TOWARD THE MYELOMONOCYTIC OVER ERYTHROID COMMITMENT AS INDICATED BY AN INVERSE RATIO OF MYELOMONOCYTIC/ERYTHROID COLONIES WAS INVESTIGATED IN 146 PATIENTS WITH CMML BY SEMISOLID IN VITRO CULTURES. RESULTS: THERE WAS A HIGH PREVALENCE OF MYELOMONOCYTIC SKEWING IN PATIENTS WITH CMML (120/146, 82%); WHEREAS, THIS PHENOMENON WAS RARE IN NORMAL INDIVIDUALS (1/98, 1%). PATIENTS WITH CMML WITH MYELOMONOCYTIC SKEWING HAD HIGHER WHITE BLOOD CELL AND PERIPHERAL BLAST CELL COUNTS, AND LOWER PLATELET VALUES. THE NUMBER OF MUTATIONS IN GENES OF THE EPIGENETIC AND/OR SPLICING CATEGORY WAS HIGHER IN CMML PATIENTS WITH AS COMPARED WITH PATIENTS WITHOUT SKEWING. PATIENTS WITH MYELOMONOCYTIC SKEWING HAD MORE FREQUENTLY MUTATIONS IN RASOPATHY GENES AND HIGHER GROWTH FACTOR INDEPENDENT MYELOID COLONY FORMATION. INTERESTINGLY, THE LACK OF MYELOMONOCYTIC SKEWING DISCRIMINATED PATIENTS WITH CMML WITH A PARTICULARLY FAVORABLE PROGNOSIS (60 VS 19 MONTHS, P = .003) AND A MINIMAL RISK OF TRANSFORMATION. CONCLUSION: MYELOMONOCYTIC SKEWING AS DETERMINED BY SEMISOLID CULTURES CAN DISCRIMINATE SUBGROUPS OF PATIENTS WITH CMML WITH A DIFFERENT PHENOTYPE, A DIFFERENT GENOTYPE, AND A DIFFERENT PROGNOSIS. 2021 16 32 39 A CASE OF TYROSINE KINASE INHIBITOR-RESISTANT CHRONIC MYELOID LEUKEMIA, CHRONIC PHASE WITH ASXL1 MUTATION. HEMATOLOGICAL MALIGNANCIES, INCLUDING CHRONIC MYELOID LEUKEMIA (CML), EXHIBIT ASXL1 MUTATIONS; HOWEVER, THE FUNCTION AND MOLECULAR MECHANISM OF THESE MUTATIONS REMAIN UNCLEAR. ASXL1 WAS ORIGINALLY IDENTIFIED AS TUMOR SUPPRESSOR GENE, IN WHICH LOSS OF FUNCTION CAUSES MYELODYSPLASTIC SYNDROME (MDS). ASXL1 MUTATIONS ARE COMMON AND ASSOCIATED WITH DISEASE PROGRESSION IN MYELOID MALIGNANCIES INCLUDING MDS, ACUTE MYELOID LEUKEMIA, AND SIMILARLY IN CML. IN MDS, ASXL1 MUTATIONS HAVE BEEN ASSOCIATED WITH POOR PROGNOSIS; HOWEVER, THE IMPACT OF ASXL1 MUTATIONS IN CML HAS NOT BEEN WELL DESCRIBED. A 31-YEAR-OLD MALE WAS DIAGNOSED AS CML-CHRONIC PHASE (CP). LABORATORY FINDINGS SHOWED A WHITE BLOOD CELL COUNT OF 187,200/MICROL, WITH ASYMPTOMATIC SPLENOMEGALY. BLAST COUNT WAS 5.0% IN PERIPHERAL BLOOD AND 7.3% IN BONE MARROW. THERE WAS NO ADDITIONAL CHROMOSOMAL ABNORMALITY EXCEPT FOR T(9;22)(Q34;Q11.2) BY CHROMOSOMAL ANALYSIS. AT ONSET, THE SOKAL SCORE WAS 1.4, INDICATING HIGH RISK. THE PATIENT RECEIVED TYROSINE KINASE INHIBITOR (TKI) THERAPY, COMPRISING NILOTINIB APPROXIMATELY 600 MG/DAY, BOSUTINIB APPROXIMATELY 600 MG/DAY, PONATINIB APPROXIMATELY 45 MG/DAY, AND DASATINIB APPROXIMATELY 100 MG/DAY. NEVERTHELESS, AFTER 1.5 YEARS OF CONTINUOUS TKI THERAPY, THE BEST OUTCOME WAS A HEMATOLOGICAL RESPONSE. ALTHOUGH ADDITIONAL CHROMOSOMAL ABERRATIONS AND ABL1 KINASE MUTATIONS WERE ANALYZED REPEATEDLY BEFORE AND DURING TKI THERAPY, KNOWN GENETIC ABNORMALITIES WERE NOT DETECTED. THEREAFTER, THE PATIENT UNDERWENT BONE MARROW TRANSPLANTATION FROM AN HLA 7/8 MATCHED UNRELATED DONOR (HLA-CW 1 LOCUS MISMATCH, GRAFT-VERSUS-HOST DIRECTION). THE PATIENT ACHIEVED NEUTROPHIL ENGRAFTMENT, 18 DAYS AFTER TRANSPLANTATION, LEADING TO COMPLETE REMISSION WITH AN UNDETECTABLE LEVEL OF BCR-ABL1 MRNA. THE PATIENT, HOWEVER, DIED FROM GRAFT-VERSUS-HOST DISEASE AND THROMBOTIC MICROANGIOPATHY AFTER 121 DAYS. GENE SEQUENCE ANALYSIS OF HIS CML CELL BEFORE STEM CELL TRANSPLANTATION REVEALED ASXL1 MUTATIONS. PHYSIOLOGICALLY, ASXL1 CONTRIBUTES TO EPIGENETIC REGULATION. IN THE CML-CP PATIENT IN THIS CASE REPORT, ASXL1 MUTATION CONFERRED RESISTANCE TO TKI THROUGH OBSCURE RESISTANCE MECHANISMS. EVEN THOUGH A MOLECULAR MECHANISM FOR TKI RESISTANCE IN ASXL1 MUTATION IN CML HAS REMAINED OBSCURE, EPIGENETIC MODULATION IS A PLAUSIBLE MODE OF CML DISEASE PROGRESSION. THE CLINICAL IMPACT INCLUDING PROGNOSIS OF ASXL1 FOR CML IS UNDERSCORED. AND THE TREATMENT STRATEGY OF CML WITH ASXL1 MUTATION HAS NOT BEEN ESTABLISHED. A DISCUSSION OF THIS CASE WAS EXPECTED TO FACILITATE TREATMENT OPTIONS. 2020 17 4876 29 OVEREXPRESSION OF ARGINASE 1 IS LINKED TO DNMT3A AND TET2 MUTATIONS IN LOWER-GRADE MYELODYSPLASTIC SYNDROMES AND CHRONIC MYELOMONOCYTIC LEUKEMIA. IMMUNE DYSREGULATION IS A COMMON FEATURE OF MYELODYSPLASTIC SYNDROMES (MDS) AND CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML), PARTICULARLY IN EARLY STAGES. HOWEVER, THE GENETIC BASIS REMAINS POORLY UNDERSTOOD. WE RECENTLY REPORTED THAT MACROPHAGES FROM MICE DEFICIENT IN TET METHYLCYTOSINE DIOXYGENASE 2 (TET2), A MODEL OF MDS/CMML, ARE HYPERINFLAMMATORY AND HAVE INCREASED EXPRESSION OF ARGINASE 1 (ARG1). IN MACROPHAGES AND MYELOID DERIVED SUPPRESSOR CELLS (MDSCS) EXPRESSION OF ARG1 CONTRIBUTES TO T-CELL SUPPRESSION AND IMMUNE EVASION BY L-ARGININE DEPLETION, IN THE SETTING OF CHRONIC INFLAMMATION AND CANCER. SINCE HUMAN MDS AND CMML ARE DRIVEN BY TET2 MUTATIONS AND ASSOCIATED WITH CHRONIC INFLAMMATION, WE HYPOTHESIZED THAT ARGINASE ENZYMATIC ACTIVITY AND ARG1 EXPRESSION WOULD BE INCREASED IN HUMAN MDS/CMML BONE MARROW. ELEVATED ARGINASE ACTIVITY WAS OBSERVED IN BONE MARROW MONONUCLEAR CELLS OF MDS AND CMML PATIENTS WITH LOWER-GRADE FEATURES. IMMUNOHISTOCHEMICAL STUDIES CONFIRMED THAT MYELOMONOCYTIC CELLS OVEREXPRESS ARG1. ADDITIONALLY, MUTATIONS IN THE EPIGENETIC REGULATORS TET2 AND DNMT3A CORRESPONDED TO HIGH ARG1 EXPRESSION AND ACTIVITY. THESE FINDINGS SUGGEST ARG1 IS A BIOMARKER OF IMMUNE DYSREGULATION IN EARLY MDS AND CMML. RECENT MURINE FINDINGS HAVE IMPLICATED TET2 AND DNMT3A IN REGULATION OF INNATE IMMUNITY. OUR STUDY SUGGESTS SIMILAR CHANGES MAY BE DRIVEN BY HUMAN TET2 AND DNMT3A MUTATIONS. 2018 18 962 35 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 19 2981 24 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 20 535 28 ASXL1 MUTATION CORRECTION BY CRISPR/CAS9 RESTORES GENE FUNCTION IN LEUKEMIA CELLS AND INCREASES SURVIVAL IN MOUSE XENOGRAFTS. RECURRENT SOMATIC MUTATIONS OF THE EPIGENETIC MODIFIER AND TUMOR SUPPRESSOR ASXL1 ARE COMMON IN MYELOID MALIGNANCIES, INCLUDING CHRONIC MYELOID LEUKEMIA (CML), AND ARE ASSOCIATED WITH POOR CLINICAL OUTCOME. CRISPR/CAS9 HAS RECENTLY EMERGED AS A POWERFUL AND VERSATILE GENOME EDITING TOOL FOR GENOME ENGINEERING IN VARIOUS SPECIES. WE HAVE USED THE CRISPR/CAS9 SYSTEM TO CORRECT THE ASXL1 HOMOZYGOUS NONSENSE MUTATION PRESENT IN THE CML CELL LINE KBM5, WHICH LACKS ASXL1 PROTEIN EXPRESSION. CRISPR/CAS9-MEDIATED ASXL1 HOMOZYGOUS CORRECTION RESULTED IN PROTEIN RE-EXPRESSION WITH RESTORED NORMAL FUNCTION, INCLUDING DOWN-REGULATION OF POLYCOMB REPRESSIVE COMPLEX 2 TARGET GENES. SIGNIFICANTLY REDUCED CELL GROWTH AND INCREASED MYELOID DIFFERENTIATION WERE OBSERVED IN ASXL1 MUTATION-CORRECTED CELLS, PROVIDING NEW INSIGHTS INTO THE ROLE OF ASXL1 IN HUMAN MYELOID CELL DIFFERENTIATION. MICE XENOGRAFTED WITH MUTATION-CORRECTED KBM5 CELLS SHOWED SIGNIFICANTLY LONGER SURVIVAL THAN UNCORRECTED XENOGRAFTS. THESE RESULTS SHOW THAT THE SOLE CORRECTION OF A DRIVER MUTATION IN LEUKEMIA CELLS INCREASES SURVIVAL IN VIVO IN MICE. THIS STUDY PROVIDES PROOF-OF-CONCEPT FOR DRIVER GENE MUTATION CORRECTION VIA CRISPR/CAS9 TECHNOLOGY IN HUMAN LEUKEMIA CELLS AND PRESENTS A STRATEGY TO ILLUMINATE THE IMPACT OF ONCOGENIC MUTATIONS ON CELLULAR FUNCTION AND SURVIVAL. 2015