1 2665 143 ESTABLISHMENT OF A NOVEL MYELODYSPLASTIC SYNDROME (MDS) XENOTRANSPLANTATION MODEL. BACKGROUND: MYELODYSPLASTIC SYNDROME (MDS) IS A CLONAL DISEASE OF THE ELDERLY CHARACTERIZED BY CHRONIC CYTOPENIA, DYSPLASIA, AND A HIGH RISK OF PROGRESSION TO ACUTE MYELOID LEUKEMIA (AML). UP UNTIL NOW, FEW ANIMAL MODELS THAT FULLY RECAPITULATE CLINICAL FEATURES OF THIS DISEASE HAVE BEEN AVAILABLE. METHODS: THIS STUDY AIMED TO ESTABLISH A NEW MDS XENOGRAFT MODEL UTILIZING A HUMAN MDS-DERIVED CELL LINE WITH HETEROZYGOUS Y641C MUTATION OF EZH2 (SKM-1). 1 X 107 SKM-1 CELLS WERE INOCULATED INTO ANTI-MOUSE CD122 MONOANTIBODY CONDITIONED NONOBESE DIABETIC SEVERE COMBINED IMMUNODEFICIENCY (NOD/SCID) MICE BY INTRAVENOUS INJECTION. DECITABINE WAS INJECTED INTRAPERITONEALLY FOR EVALUATION OF EPIGENETIC DRUGS IN VIVO. RESULTS: IT IS SHOWN THAT THE HETEROZYGOUS Y641C MUTATION IN THE EZH2 GENE MUTATION, WHICH MAY DESTABILIZE THE PROTEIN (??G = 1.46 KCAL/MOL), CAN BE FOUND IN SKM-1 CELLS. MOST MICE PRESENTED ANEMIA AND LEUKOPENIA AT THREE TO FOUR WEEKS AFTER INOCULATION. THE PERIPHERAL BLOOD AND BONE MARROW SMEAR SHOWED PROMINENT DYSPLASIA ON ERYTHROCYTES AND GRANULOCYTES AS WELL AS MONOCYTES. CONCLUSIONS: THESE FINDINGS SUGGEST THAT INTRAVENOUS INOCULATION OF CELLS FROM THE HUMAN MDS-DERIVED CELL LINE PRIOR TO TARGETED DEPLETION OF CD122+ CELLS COULD PROVIDE A NOVEL MDS-LIKE XENOTRANSPLANT MOUSE MODEL. IT IS A USEFUL TOOL FOR EVALUATING POTENTIAL EXISTING AND NOVEL THERAPEUTICS FOR MDS. 2016 2 3878 40 KDM6B OVEREXPRESSION ACTIVATES INNATE IMMUNE SIGNALING AND IMPAIRS HEMATOPOIESIS IN MICE. KDM6B IS AN EPIGENETIC REGULATOR THAT MEDIATES TRANSCRIPTIONAL ACTIVATION DURING DIFFERENTIATION, INCLUDING IN BONE MARROW (BM) HEMATOPOIETIC STEM AND PROGENITOR CELLS (HSPCS). OVEREXPRESSION OF KDM6B HAS BEEN REPORTED IN BM HSPCS OF PATIENTS WITH MYELODYSPLASTIC SYNDROMES (MDS) AND CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML). WHETHER THE OVEREXPRESSION OF KDM6B CONTRIBUTES TO THE PATHOGENESIS OF THESE DISEASES REMAINS TO BE ELUCIDATED. TO STUDY THIS, WE GENERATED A VAV-KDM6B MOUSE MODEL, WHICH OVEREXPRESSES KDM6B IN THE HEMATOPOIETIC COMPARTMENT. KDM6B OVEREXPRESSION ALONE LED TO MILD HEMATOPOIETIC PHENOTYPE, AND CHRONIC INNATE IMMUNE STIMULATION OF VAV-KDM6B MICE WITH THE TOLL-LIKE RECEPTOR (TLR) LIGAND LIPOPOLYSACCHARIDE (LPS) RESULTED IN SIGNIFICANT HEMATOPOIETIC DEFECTS. THESE DEFECTS RECAPITULATED FEATURES OF MDS AND CMML, INCLUDING LEUKOPENIA, DYSPLASIA, AND COMPROMISED REPOPULATING FUNCTION OF BM HSPCS. TRANSCRIPTOME STUDIES INDICATED THAT KDM6B OVEREXPRESSION ALONE COULD LEAD TO ACTIVATION OF DISEASE-RELEVANT GENES SUCH AS S100A9 IN BM HSPCS, AND WHEN COMBINED WITH INNATE IMMUNE STIMULATION, KDM6B OVEREXPRESSION RESULTED IN MORE PROFOUND OVEREXPRESSION OF INNATE IMMUNE AND DISEASE-RELEVANT GENES, INDICATING THAT KDM6B WAS INVOLVED IN THE ACTIVATION OF INNATE IMMUNE SIGNALING IN BM HSPCS. FINALLY, PHARMACOLOGIC INHIBITION OF KDM6B WITH THE SMALL MOLECULE INHIBITOR GSK-J4 AMELIORATED THE INEFFECTIVE HEMATOPOIESIS OBSERVED IN VAV-KDM6B MICE. THIS EFFECT WAS ALSO OBSERVED WHEN GSK-J4 WAS APPLIED TO THE PRIMARY BM HSPCS OF PATIENTS WITH MDS BY IMPROVING THEIR REPOPULATING FUNCTION. THESE RESULTS INDICATE THAT OVEREXPRESSION OF KDM6B MEDIATES ACTIVATION OF INNATE IMMUNE SIGNALS AND HAS A ROLE IN MDS AND CMML PATHOGENESIS, AND THAT KDM6B TARGETING HAS THERAPEUTIC POTENTIAL IN THESE MYELOID DISORDERS. 2018 3 5911 30 TARGETED NEXT-GENERATION SEQUENCING IN MYELODYSPLASTIC SYNDROME AND CHRONIC MYELOMONOCYTIC LEUKEMIA AIDS DIAGNOSIS IN CHALLENGING CASES AND IDENTIFIES FREQUENT SPLICEOSOME MUTATIONS IN TRANSFORMED ACUTE MYELOID LEUKEMIA. OBJECTIVES: OPTIMAL INTEGRATION OF NEXT-GENERATION SEQUENCING (NGS) INTO CLINICAL PRACTICE IN HEMATOLOGIC MALIGNANCIES REMAINS UNCLEAR. WE EVALUATE THE UTILITY OF NGS IN MYELOID MALIGNANCIES. METHODS: A 42-GENE PANEL WAS USED TO SEQUENCE 109 CASES OF MYELODYSPLASTIC SYNDROME (MDS, N = 38), CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML, N = 14), MYELOPROLIFERATIVE NEOPLASM (MPN, N = 24), AND MDS AND/OR MPN TRANSFORMED TO ACUTE MYELOID LEUKEMIA (AML, N = 33). RESULTS: AT LEAST ONE PATHOGENIC MUTATION WAS IDENTIFIED IN 74% OF CASES OF MDS, 100% OF CMMLS, AND 96% OF MPNS. IN CONTRAST, ONLY 47% OF CASES OF MDS (18/38) AND 7% (1/14) OF CMMLS EXHIBITED ABNORMAL CYTOGENETICS. IN DIAGNOSTICALLY DIFFICULT CASES OF MDS OR CMML WITH NORMAL CYTOGENETICS, NGS IDENTIFIED A PATHOGENIC MUTATION AND WAS CRITICAL IN ESTABLISHING THE CORRECT DIAGNOSIS. SPLICEOSOMAL GENES AND EPIGENETIC MODIFIERS WERE FREQUENTLY MUTATED. SPLICEOSOME MUTATIONS WERE ALSO FREQUENTLY DETECTED IN AML ARISING FROM MDS, CMML, OR MPN (39%) COMPARED WITH THE REPORTED RATE IN DE NOVO AML (7%-14%). CONCLUSIONS: IN DIFFICULT CASES OF MDS OR MPN, NGS FACILITATES DIAGNOSIS BY DETECTION OF GENE MUTATIONS TO CONFIRM CLONALITY, AND AMLS EVOLVING FROM MDS OR MPN CARRY FREQUENT MUTATIONS IN SPLICEOSOMAL GENES. 2016 4 2760 41 EXPRESSION OF PD-L1, PD-L2, PD-1 AND CTLA4 IN MYELODYSPLASTIC SYNDROMES IS ENHANCED BY TREATMENT WITH HYPOMETHYLATING AGENTS. BLOCKADE OF IMMUNE CHECKPOINTS IS EMERGING AS A NEW FORM OF ANTICANCER THERAPY. WE STUDIED THE EXPRESSION OF PROGRAMMED DEATH LIGAND 1 (PD-L1), PD-L2, PROGRAMMED DEATH 1 (PD-1) AND CYTOTOXIC T LYMPHOCYTE-ASSOCIATED ANTIGEN 4 (CTLA4) MRNA IN CD34+ CELLS FROM MYELODYSPLASTIC SYNDROME (MDS), CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) AND ACUTE MYELOID LEUKEMIA (AML) PATIENTS (N=124). ABERRANT UPREGULATION (?2-FOLD) WAS OBSERVED IN 34, 14, 15 AND 8% OF THE PATIENTS. INCREASED EXPRESSION OF THESE FOUR GENES WAS ALSO OBSERVED IN PERIPHERAL BLOOD MONONUCLEAR CELLS (PBMNCS) (N=61). THE RELATIVE EXPRESSION OF PD-L1 FROM PBMNC WAS SIGNIFICANTLY HIGHER IN MDS (P=0.018) AND CMML (P=0.0128) COMPARED WITH AML. BY IMMUNOHISTOCHEMICAL ANALYSIS, PD-L1 PROTEIN EXPRESSION WAS OBSERVED IN MDS CD34+ CELLS, WHEREAS STROMA/NON-BLAST CELLULAR COMPARTMENT WAS POSITIVE FOR PD-1. IN A COHORT OF PATIENTS TREATED WITH EPIGENETIC THERAPY, PD-L1, PD-L2, PD-1 AND CTLA4 EXPRESSION WAS UPREGULATED. PATIENTS RESISTANT TO THERAPY HAD RELATIVE HIGHER INCREMENTS IN GENE EXPRESSION COMPARED WITH PATIENTS WHO ACHIEVED RESPONSE. TREATMENT OF LEUKEMIA CELLS WITH DECITABINE RESULTED IN A DOSE-DEPENDENT UPREGULATION OF ABOVE GENES. EXPOSURE TO DECITABINE RESULTED IN PARTIAL DEMETHYLATION OF PD-1 IN LEUKEMIA CELL LINES AND HUMAN SAMPLES. THIS STUDY SUGGESTS THAT PD-1 SIGNALING MAY BE INVOLVED IN MDS PATHOGENESIS AND RESISTANCE MECHANISMS TO HYPOMETHYLATING AGENTS. BLOCKADE OF THIS PATHWAY CAN BE A POTENTIAL THERAPY IN MDS AND AML. 2014 5 1901 37 ENGRAFTMENT OF CHRONIC MYELOMONOCYTIC LEUKEMIA CELLS IN IMMUNOCOMPROMISED MICE SUPPORTS DISEASE DEPENDENCY ON CYTOKINES. CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) IS A CLONAL HEMATOPOIETIC STEM CELL DISORDER THAT TYPICALLY ASSOCIATES WITH MUTATIONS IN EPIGENETIC, SPLICING, AND SIGNALING GENES. GENETICALLY MODIFIED MOUSE MODELS ONLY PARTIALLY RECAPITULATE THE DISEASE PHENOTYPE, WHEREAS XENOTRANSPLANTATION OF CMML CELLS IN IMMUNOCOMPROMISED MICE HAS BEEN RARELY SUCCESSFUL SO FAR. HERE, CMML CD34(+) CELLS SORTED FROM PATIENT BONE MARROW (BM) OR PERIPHERAL BLOOD (PB) WERE INJECTED INTRAVENOUSLY INTO NSG (NOD/LTSZ-SCID IL2RGAMMANULL) MICE AND NSG MICE ENGINEERED TO EXPRESS HUMAN GRANULO-MONOCYTE COLONY-STIMULATING FACTOR, STEM CELL FACTOR, AND INTERLEUKIN-3 (NSGS MICE). FIFTEEN OUT OF 16 PATIENT SAMPLES (94%) SUCCESSFULLY ENGRAFTED INTO NSG OR NSGS OR BOTH MOUSE STRAINS. THE EXPANSION OF HUMAN CELLS, PREDOMINANT IN THE BM, WAS ALSO OBSERVED IN THE SPLEEN AND THE PB AND WAS GREATLY ENHANCED IN MICE PRODUCING THE 3 HUMAN CYTOKINES. GENE MUTATIONS IDENTIFIED IN ENGRAFTED CELLS WERE MOSTLY SIMILAR TO THOSE IDENTIFIED IN PATIENT CELLS BEFORE INJECTION. SUCCESSFUL SECONDARY ENGRAFTMENT WAS OBTAINED IN NSGS MICE IN 3 OUT OF 10 ATTEMPTS. THUS, PRIMARY CMML LEUKEMIC CELLS EXPAND MUCH BETTER IN NSGS COMPARED WITH NSG MICE WITH LIMITED EFFICACY OF SECONDARY TRANSPLANT. 2017 6 4562 39 MYELODYSPLASTIC SYNDROME/MYELOPROLIFERATIVE NEOPLASM OVERLAP SYNDROMES: A FOCUSED REVIEW. MYELODYSPLASTIC SYNDROME (MDS)/MYELOPROLIFERATIVE NEOPLASM (MPN) OVERLAP SYNDROMES ARE UNIQUE MYELOID NEOPLASMS, WITH OVERLAPPING FEATURES OF MDS AND MPN. THEY CONSIST OF FOUR ADULT ONSET ENTITIES INCLUDING CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML), MDS/MPN-RING SIDEROBLASTS-THROMBOCYTOSIS (MDS/MPN-RS-T), BCR-ABL1 NEGATIVE ATYPICAL CHRONIC MYELOID LEUKEMIA (ACML) AND MDS/MPN-UNCLASSIFIABLE (MDS/MPN-U); WITH JUVENILE MYELOMONOCYTIC LEUKEMIA (JMML) BEING THE ONLY PEDIATRIC ONSET ENTITY. AMONG THESE OVERLAP NEOPLASMS, CMML IS THE MOST FREQUENT AND IS HALLMARKED BY THE PRESENCE OF SUSTAINED PERIPHERAL BLOOD MONOCYTOSIS WITH RECURRENT MUTATIONS INVOLVING TET2 (60%), SRSF2 (50%) AND ASXL1 (40%); WITH RAS PATHWAY MUTATIONS AND JAK2V617F BEING RELATIVELY ENRICHED IN PROLIFERATIVE CMML SUBTYPES (WBC >/=13 X 109/L). CMML USUALLY PRESENTS IN THE 7TH DECADE OF LIFE, WITH A MALE PREPONDERANCE AND IS ASSOCIATED WITH A MEDIAN OVERALL SURVIVAL OF <36 MONTHS. ADVERSE PROGNOSTICATORS IN CMML INCLUDE INCREASING AGE, HIGH WBC, PRESENCE OF CIRCULATING IMMATURE MYELOID CELLS, ANEMIA, THROMBOCYTOPENIA AND TRUNCATING ASXL1 MUTATIONS. WHILE ALLOGENEIC STEM CELL TRANSPLANTATION REMAINS THE ONLY CURATIVE OPTION, GIVEN THE LATE ONSET OF THIS NEOPLASM AND HIGH FREQUENCY OF COMORBIDITIES, MOST PATIENTS REMAIN INELIGIBLE. HYPOMETHYLATING AGENTS SUCH AS AZACITIDINE, DECITABINE AND ORAL DECITABINE/CEDAZURIDINE HAVE BEEN US FDA APPROVED FOR THE MANAGEMENT OF CMML, WITH OVERALL RESPONSE RATES OF 40-50% AND COMPLETE REMISSION RATES OF <20%. WHILE THESE AGENTS EPIGENETICALLY RESTORE HEMATOPOIESIS IN A SUBSET OF RESPONDING PATIENTS, THEY DO NOT IMPACT MUTATIONAL ALLELE BURDENS AND EVENTUAL DISEASE PROGRESSION TO AML REMAINS INEVITABLE. NEWER TREATMENT MODALITIES EXPLOITING EPIGENETIC, SIGNALING AND SPLICING ABNORMALITIES COMMONLY SEEN IN CMML ARE MUCH NEEDED. 2020 7 3871 26 JUVENILE MYELOMONOCYTIC LEUKEMIA - A BONA FIDE RASOPATHY SYNDROME. JUVENILE MYELOMONOCYTIC LEUKEMIA (JMML) IS A PEDIATRIC MYELODYSPLASTIC/MYELOPROLIFERATIVE NEOPLASM OVERLAP SYNDROME WITH SUSTAINED PERIPHERAL BLOOD MONOCYTOSIS, AGGRESSIVE FEATURES, AND POOR OUTCOMES. IN >90% OF CASES JMML IS DRIVEN BY GERMLINE OR SOMATIC MUTATIONS INVOLVING THE CANONICAL RAS PATHWAY (PTPN11, NRAS, CBL, KRAS AND NF1), WITH SOMATIC MUTATIONS/ALTERATIONS IN RAS PATHWAY GENES (SECOND HIT), SETBP1, ASXL1 AND JAK3 RESULTING IN DISEASE PROGRESSION. WHILE SPONTANEOUS REGRESSION HAS BEEN SEEN IN GERMLINE PTPN11 AND CBL MUTANT JMML, IN MOST PATIENTS, ALLOGENEIC STEM CELL TRANSPLANT IS THE ONLY CURATIVE MODALITY. JMML SHARES SEVERAL PHENOTYPIC FEATURES WITH ITS ADULT COUNTERPART PROLIFERATIVE, CHRONIC MYELOMONOCYTIC LEUKEMIA (PCMML). PCMML LARGELY OCCURS DUE TO RAS PATHWAY MUTATIONS THAT OCCUR IN THE CONTEXT OF AGE RELATED CLONAL HEMATOPOIESIS (TET2, SRSF2, ASXL1), WHILE JMML IS A BONA FIDE RASOPATHY, WITH ADDITIONAL SOMATIC MUTATIONS, INCLUDING IN EPIGENETIC REGULATORS GENES RESULTING IN DISEASE PROGRESSION. 2020 8 2277 34 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 9 1184 24 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 10 4876 37 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 11 4485 34 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 12 4838 32 ONCOGENIC N-RAS AND TET2 HAPLOINSUFFICIENCY COLLABORATE TO DYSREGULATE HEMATOPOIETIC STEM AND PROGENITOR CELLS. CONCURRENT GENETIC LESIONS EXIST IN A MAJORITY OF PATIENTS WITH HEMATOLOGIC MALIGNANCIES. AMONG THESE, SOMATIC MUTATIONS THAT ACTIVATE RAS ONCOGENES AND INACTIVATE THE EPIGENETIC MODIFIER TEN-ELEVEN TRANSLOCATION 2 (TET2) FREQUENTLY CO-OCCUR IN HUMAN CHRONIC MYELOMONOCYTIC LEUKEMIAS (CMMLS) AND ACUTE MYELOID LEUKEMIAS, SUGGESTING A COOPERATIVITY IN MALIGNANT TRANSFORMATION. TO TEST THIS, WE APPLIED A CONDITIONAL MURINE MODEL THAT ENDOGENOUSLY EXPRESSED ONCOGENIC NRAS(G12D) AND MONOALLELIC LOSS OF TET2 AND EXPLORED THE COLLABORATIVE ROLE SPECIFICALLY WITHIN HEMATOPOIETIC STEM AND PROGENITOR CELLS (HSPCS) AT DISEASE INITIATION. WE DEMONSTRATE THAT THE 2 MUTATIONS COLLABORATED TO ACCELERATE A TRANSPLANTABLE CMML-LIKE DISEASE IN VIVO, WITH AN OVERALL SHORTENED SURVIVAL AND INCREASED DISEASE PENETRANCE COMPARED WITH SINGLE MUTANTS. AT PRELEUKEMIC STAGE, N-RAS(G12D) AND TET2 HAPLOINSUFFICIENCY TOGETHER INDUCED BALANCED HEMATOPOIETIC STEM CELL (HSC) PROLIFERATION AND ENHANCED COMPETITIVENESS. NRAS(G12D/+)/TET2(+/-) HSCS DISPLAYED INCREASED SELF-RENEWAL IN PRIMARY AND SECONDARY TRANSPLANTATIONS, WITH SIGNIFICANTLY HIGHER RECONSTITUTION THAN SINGLE MUTANTS. STRIKINGLY, THE 2 MUTATIONS TOGETHER CONFERRED LONG-TERM RECONSTITUTION AND SELF-RENEWAL POTENTIAL TO MULTIPOTENT PROGENITORS, A POOL OF CELLS THAT USUALLY HAVE LIMITED SELF-RENEWAL COMPARED WITH HSCS. MOREOVER, HSPCS FROM NRAS(G12D/+)/TET2(+/-) MICE DISPLAYED INCREASED CYTOKINE SENSITIVITY IN RESPONSE TO THROMBOPOIETIN. THEREFORE, OUR STUDIES ESTABLISH A NOVEL TRACTABLE CMML MODEL AND PROVIDE INSIGHTS INTO HOW DYSREGULATED SIGNALING PATHWAYS AND EPIGENETIC MODIFIERS COLLABORATE TO MODULATE HSPC FUNCTION AND PROMOTE LEUKEMOGENESIS. 2018 13 4557 24 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 14 4553 37 MUTATIONAL LANDSCAPE OF CHRONIC MYELOMONOCYTIC LEUKEMIA IN CHINESE PATIENTS. BACKGROUND: CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) IS A RARE AND HETEROGENEOUS HEMATOLOGICAL MALIGNANCY. IT HAS BEEN SHOWN THAT THE MOLECULAR ABNORMALITIES SUCH AS ASXL1, TET2, SETBP1, AND SRSF2 MUTATIONS ARE COMMON IN CAUCASIAN POPULATION. METHODS: WE RETROSPECTIVELY ANALYZED 178 CHINESE CMML PATIENTS. THE TARGETED NEXT GENERATION SEQUENCING (NGS) WAS USED TO EVALUATE 114 GENE VARIATIONS, AND THE PROGNOSTIC FACTORS FOR OS WERE DETERMINED BY COX REGRESSION ANALYSIS. RESULTS: THE CMML PATIENTS SHOWED A UNIQUE MUTATIONAL SPECTRUM, INCLUDING TET2 (36.5%), NRAS (31.5%), ASXL1 (28.7%), SRSF2 (24.7%), AND RUNX1 (21.9%). OF THE 102 PATIENTS WITH CLONAL ANALYSIS, THE ANCESTRAL EVENTS PREFERENTIALLY OCCURRED IN TET2 (18.5%), SPLICING FACTORS (16.5%), RAS (14.0%), AND ASXL1 (7.8%), AND THE SUBCLONAL GENES WERE MAINLY ASXL1, TET2, AND RAS. IN ADDITION, THE SECONDARY ACUTE MYELOID LEUKEMIA (SAML) TRANSFORMED FROM CMML OFTEN HAD MUTATIONS IN DNMT3A, ETV6, FLT3, AND NPM1, WHILE THE PRIMARY AML (PAML) DEMONSTRATED MORE MUTATIONS IN CEBPA, DNMT3A, FLT3, IDH1/2, NPM1, AND WT1. IT WAS OF NOTE THAT A SERIES OF CLONES WERE EMERGED DURING THE PROGRESSION FROM CMML TO AML, INCLUDING DNMT3A, FLT3, AND NPM1. BY UNIVARIATE ANALYSIS, ASXL1 MUTATION, INTERMEDIATE- AND HIGH-RISK CYTOGENETIC ABNORMALITY, CMML-SPECIFIC PROGNOSTIC SCORING SYSTEM (CPSS) STRATIFICATIONS (INTERMEDIATE-2 AND HIGH GROUP), AND TREATMENT OPTIONS (BEST SUPPORTIVE CARE) PREDICTED FOR WORSE OS. MULTIVARIATE ANALYSIS REVEALED A SIMILAR OUTCOME. CONCLUSIONS: THE COMMON MUTATIONS IN CHINESE CMML PATIENTS INCLUDED EPIGENETIC MODIFIERS (TET2 AND ASXL1), SIGNALING TRANSDUCTION PATHWAY COMPONENTS (NRAS), AND SPLICING FACTOR (SRSF2). THE CMML PATIENTS WITH DNMT3A, ETV6, FLT3, AND NPM1 MUTATIONS TENDED TO PROGRESS TO SAML. ASXL1 MUTATION AND THERAPEUTIC MODALITIES WERE INDEPENDENT PROGNOSTIC FACTORS FOR CMML. 2022 15 690 28 BRD4 DEGRADATION BLOCKS EXPRESSION OF MYC AND MULTIPLE FORMS OF STEM CELL RESISTANCE IN PH(+) CHRONIC MYELOID LEUKEMIA. IN MOST PATIENTS WITH CHRONIC MYELOID LEUKEMIA (CML) CLONAL CELLS CAN BE KEPT UNDER CONTROL BY BCR::ABL1 TYROSINE KINASE INHIBITORS (TKI). HOWEVER, OVERT RESISTANCE OR INTOLERANCE AGAINST THESE TKI MAY OCCUR. WE IDENTIFIED THE EPIGENETIC READER BRD4 AND ITS DOWNSTREAM-EFFECTOR MYC AS GROWTH REGULATORS AND THERAPEUTIC TARGETS IN CML CELLS. BRD4 AND MYC WERE FOUND TO BE EXPRESSED IN PRIMARY CML CELLS, CD34(+) /CD38(-) LEUKEMIC STEM CELLS (LSC), AND IN THE CML CELL LINES KU812, K562, KCL22, AND KCL22(T315I) . THE BRD4-TARGETING DRUG JQ1 WAS FOUND TO SUPPRESS PROLIFERATION IN KU812 CELLS AND PRIMARY LEUKEMIC CELLS IN THE MAJORITY OF PATIENTS WITH CHRONIC PHASE CML. IN THE BLAST PHASE OF CML, JQ1 WAS LESS EFFECTIVE. HOWEVER, THE BRD4 DEGRADER DBET6 WAS FOUND TO BLOCK PROLIFERATION AND/OR SURVIVAL OF PRIMARY CML CELLS IN ALL PATIENTS TESTED, INCLUDING BLAST PHASE CML AND CML CELLS EXHIBITING THE T315I VARIANT OF BCR::ABL1. MOREOVER, DBET6 WAS FOUND TO BLOCK MYC EXPRESSION AND TO SYNERGIZE WITH BCR::ABL1 TKI IN INHIBITING THE PROLIFERATION IN THE JQ1-RESISTANT CELL LINE K562. FURTHERMORE, BRD4 DEGRADATION WAS FOUND TO OVERCOME OSTEOBLAST-INDUCED TKI RESISTANCE OF CML LSC IN A CO-CULTURE SYSTEM AND TO BLOCK INTERFERON-GAMMA-INDUCED UPREGULATION OF THE CHECKPOINT ANTIGEN PD-L1 IN LSC. FINALLY, DBET6 WAS FOUND TO SUPPRESS THE IN VITRO SURVIVAL OF CML LSC AND THEIR ENGRAFTMENT IN NSG MICE. TOGETHER, TARGETING OF BRD4 AND MYC THROUGH BET DEGRADATION SENSITIZES CML CELLS AGAINST BCR::ABL1 TKI AND IS A POTENT APPROACH TO OVERCOME MULTIPLE FORMS OF DRUG RESISTANCE IN CML LSC. 2022 16 5319 40 PTEN IS FUNDAMENTAL FOR ELIMINATION OF LEUKEMIA STEM CELLS MEDIATED BY GSK126 TARGETING EZH2 IN CHRONIC MYELOGENOUS LEUKEMIA. PURPOSE: LEUKEMIA STEM CELLS (LSCS) ARE AN IMPORTANT SOURCE OF TYROSINE KINASE INHIBITOR RESISTANCE AND DISEASE RELAPSE IN PATIENTS WITH CHRONIC MYELOGENOUS LEUKEMIA (CML). TARGETING LSCS MAY BE AN ATTRACTIVE STRATEGY TO OVERRIDE THIS THORNY PROBLEM. GIVEN THAT EZH2 WAS OVEREXPRESSED IN PRIMARY CML CD34(+) CELLS, OUR PURPOSE IN THIS STUDY WAS TO EVALUATE THE EFFECTS OF TARGETING EZH2 ON CML LSCS AND CLARIFY ITS UNDERLYING MECHANISM.EXPERIMENTAL DESIGN: HUMAN PRIMARY CML CD34(+) CELLS AND RETROVIRALLY BCR-ABL-DRIVEN CML MOUSE MODELS WERE EMPLOYED TO EVALUATE THE EFFECTS OF SUPPRESSION OF EZH2 BY GSK126- OR EZH2-SPECIFIC SHRNA IN VITRO AND IN VIVO RECRUITMENT OF EZH2 AND H3K27ME3 ON THE PROMOTER OF TUMOR-SUPPRESSOR GENE PTEN IN CML CELLS WAS MEASURED BY CHROMATIN IMMUNOPRECIPITATION ASSAY.RESULTS: OUR RESULTS SHOWED THAT PHARMACOLOGIC INHIBITION OF EZH2 BY GSK126 NOT ONLY ELICITED APOPTOSIS AND RESTRICTED CELL GROWTH IN CML BULK LEUKEMIA CELLS, BUT ALSO DECREASED LSCS IN CML CD34(+) CELLS WHILE SPARING THOSE FROM NORMAL BONE MARROW CD34(+) CELLS. SUPPRESSION OF EZH2 BY GSK126 OR SPECIFIC SHRNA PROLONGED SURVIVAL OF CML MICE AND REDUCED THE NUMBER OF LSCS IN MICE. EZH2 KNOCKDOWN RESULTED IN ELEVATION OF PTEN AND LED TO IMPAIRED RECRUITMENT OF EZH2 AND H3K27ME3 ON THE PROMOTER OF PTEN GENE. THE EFFECT OF EZH2 KNOCKDOWN IN THE CML MICE WAS AT LEAST PARTIALLY REVERSED BY PTEN KNOCKDOWN.CONCLUSIONS: THESE FINDINGS IMPROVE THE UNDERSTANDING OF THE EPIGENETIC REGULATION OF STEMNESS IN CML LSCS AND WARRANT CLINICAL TRIAL OF GSK126 IN REFRACTORY PATIENTS WITH CML. CLIN CANCER RES; 24(1); 145-57. (C)2017 AACR. 2018 17 3872 44 JUVENILE MYELOMONOCYTIC LEUKEMIA-A COMPREHENSIVE REVIEW AND RECENT ADVANCES IN MANAGEMENT. JUVENILE MYELOMONOCYTIC LEUKEMIA (JMML) IS A RARE PEDIATRIC MYELODYSPLASTIC/MYELOPROLIFERATIVE NEOPLASM OVERLAP DISEASE. JMML IS ASSOCIATED WITH MUTATIONS IN THE RAS PATHWAY GENES RESULTING IN THE MYELOID PROGENITORS BEING SENSITIVE TO GRANULOCYTE MONOCYTE COLONY-STIMULATING FACTOR (GM-CSF). KARYOTYPE ABNORMALITIES AND ADDITIONAL EPIGENETIC ALTERATIONS CAN ALSO BE FOUND IN JMML. NEUROFIBROMATOSIS AND NOONAN'S SYNDROME HAVE A PREDISPOSITION FOR JMML. IN A FEW PATIENTS, THE RAS GENES (NRAS, KRAS, AND PTPN11) ARE MUTATED AT THE GERMLINE AND THIS USUALLY RESULTS IN A TRANSIENT MYELOPROLIFERATIVE DISORDER WITH A GOOD PROGNOSIS. JMML WITH SOMATIC RAS MUTATION BEHAVES AGGRESSIVELY. JMML PRESENTS WITH CYTOPENIAS AND LEUKEMIC INFILTRATION INTO ORGANS. THE LABORATORY FINDINGS INCLUDE HYPERLEUKOCYTOSIS, MONOCYTOSIS, INCREASED HEMOGLOBIN-F LEVELS, AND CIRCULATING MYELOID PRECURSORS. THE BLAST CELLS IN THE PERIPHERAL BLOOD/BONE-MARROW ASPIRATE ARE LESS THAN 20% AND THE ABSENCE OF THE BCR-ABL TRANSLOCATION HELPS TO DIFFERENTIATE FROM CHRONIC MYELOID LEUKEMIA. JMML SHOULD BE DIFFERENTIATED FROM IMMUNODEFICIENCIES, VIRAL INFECTIONS, INTRAUTERINE INFECTIONS, HEMOPHAGOLYMPHOHISTIOCYTOSIS, OTHER MYELOPROLIFERATIVE DISORDERS, AND LEUKEMIAS. CHEMOTHERAPY IS EMPLOYED AS A BRIDGE TO HSCT, EXCEPT IN FEW WITH LESS AGGRESSIVE DISEASE, IN WHICH CHEMOTHERAPY ALONE CAN RESULT IN LONG TERM REMISSION. AZACITIDINE HAS SHOWN PROMISE AS A SINGLE AGENT TO STABILIZE THE DISEASE. THE PROGNOSIS OF JMML IS POOR WITH ABOUT 50% OF PATIENTS SURVIVING AFTER AN ALLOGENEIC HEMATOPOIETIC STEM CELL TRANSPLANT (HSCT). ALLOGENEIC HSCT IS THE ONLY KNOWN CURE FOR JMML TO DATE. MYELOABLATIVE CONDITIONING IS MOST COMMONLY USED WITH GRAFT VERSUS HOST DISEASE (GVHD) PROPHYLAXIS TAILORED TO THE AGGRESSIVENESS OF THE DISEASE. RELAPSES ARE COMMON EVEN AFTER HSCT AND A SECOND HSCT CAN SALVAGE A THIRD OF THESE PATIENTS. NOVEL OPTIONS IN THE TREATMENT OF JMML E.G., HYPOMETHYLATING AGENTS, MEK INHIBITORS, JAK INHIBITORS, TYROSINE KINASE INHIBITORS, ETC. ARE BEING EXPLORED. 2021 18 1311 37 DEFINITIONS, BIOLOGY, AND CURRENT THERAPEUTIC LANDSCAPE OF MYELODYSPLASTIC/MYELOPROLIFERATIVE NEOPLASMS. MYELODYSPLASTIC/MYELOPROLIFERATIVE NEOPLASMS (MDS/MPN) ARE HEMATOLOGICAL DISORDERS CHARACTERIZED BY BOTH PROLIFERATIVE AND DYSPLASTIC FEATURES. ACCORDING TO THE 2022 INTERNATIONAL CONSENSUS CLASSIFICATION (ICC), MDS/MPN CONSISTS OF CLONAL MONOCYTOSIS OF UNDETERMINED SIGNIFICANCE (CMUS), CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML), ATYPICAL CHRONIC MYELOID LEUKEMIA (ACML), MDS/MPN WITH SF3B1 MUTATION (MDS/MPN-T-SF3B1), MDS/MPN WITH RING SIDEROBLASTS AND THROMBOCYTOSIS NOT OTHERWISE SPECIFIED (MDS/MPN-RS-T-NOS), AND MDS/MPN-NOS. THESE DISORDERS EXHIBIT A DIVERSE RANGE OF GENETIC ALTERATIONS INVOLVING VARIOUS TRANSCRIPTION FACTORS (E.G., RUNX1), SIGNALING MOLECULES (E.G., NRAS, JAK2), SPLICING FACTORS (E.G., SF3B, SRSF2), AND EPIGENETIC REGULATORS (E.G., TET2, ASXL1, DNMT3A), AS WELL AS SPECIFIC CYTOGENETIC ABNORMALITIES (E.G., 8 TRISOMIES, 7 DELETIONS/MONOSOMIES). CLINICAL STUDIES EXPLORING THERAPEUTIC OPTIONS FOR HIGHER-RISK MDS/MPN OVERLAP SYNDROMES MOSTLY INVOLVE HYPOMETHYLATING AGENTS, BUT OTHER TREATMENTS SUCH AS LENALIDOMIDE AND TARGETED AGENTS SUCH AS JAK INHIBITORS AND INHIBITORS TARGETING PARP, HISTONE DEACETYLASES, AND THE RAS PATHWAY ARE UNDER INVESTIGATION. WHILE THESE TREATMENT MODALITIES CAN PROVIDE PARTIAL DISEASE CONTROL, ALLOGENEIC BONE MARROW TRANSPLANTATION (ALLO-BMT) IS THE ONLY POTENTIALLY CURATIVE OPTION FOR PATIENTS. IMPORTANT PROGNOSTIC FACTORS CORRELATING WITH OUTCOMES AFTER ALLO-BMT INCLUDE COMORBIDITIES, SPLENOMEGALY, KARYOTYPE ALTERATIONS, AND THE BONE MARROW BLASTS PERCENTAGE AT THE TIME OF TRANSPLANTATION. FUTURE RESEARCH IS IMPERATIVE TO OPTIMIZING THERAPEUTIC STRATEGIES AND ENHANCING PATIENT OUTCOMES IN MDS/MPN NEOPLASMS. IN THIS REVIEW, WE SUMMARIZE MDS/MPN DIAGNOSTIC CRITERIA, BIOLOGY, AND CURRENT AND FUTURE TREATMENT OPTIONS, INCLUDING BONE MARROW TRANSPLANTATION. 2023 19 4571 32 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 20 1070 31 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