1 569 117 BCOR AND BCORL1 MUTATIONS IN MYELODYSPLASTIC SYNDROMES AND RELATED DISORDERS. PATIENTS WITH LOW-RISK MYELODYSPLASTIC SYNDROMES (MDS) THAT RAPIDLY PROGRESS TO ACUTE MYELOID LEUKEMIA (AML) REMAIN A CHALLENGE IN DISEASE MANAGEMENT. USING WHOLE-EXOME SEQUENCING OF AN MDS PATIENT, WE IDENTIFIED A SOMATIC MUTATION IN THE BCOR GENE ALSO MUTATED IN AML. SEQUENCING OF BCOR AND RELATED BCORL1 GENES IN A COHORT OF 354 MDS PATIENTS IDENTIFIED 4.2% AND 0.8% OF MUTATIONS RESPECTIVELY. BCOR MUTATIONS WERE ASSOCIATED WITH RUNX1 (P = .002) AND DNMT3A MUTATIONS (P = .015). BCOR IS ALSO MUTATED IN CHRONIC MYELOMONOCYTIC LEUKEMIA PATIENTS (7.4%) AND BCORL1 IN AML PATIENTS WITH MYELODYSPLASIA-RELATED CHANGES (9.1%). USING DEEP SEQUENCING, WE SHOW THAT BCOR MUTATIONS ARISE AFTER MUTATIONS AFFECTING GENES INVOLVED IN SPLICING MACHINERY OR EPIGENETIC REGULATION. IN UNIVARIATE ANALYSIS, BCOR MUTATIONS WERE ASSOCIATED WITH POOR PROGNOSIS IN MDS (OVERALL SURVIVAL [OS]: P = .013; CUMULATIVE INCIDENCE OF AML TRANSFORMATION: P = .005). MULTIVARIATE ANALYSIS INCLUDING AGE, INTERNATIONAL PROGNOSTIC SCORING SYSTEM, TRANSFUSION DEPENDENCY, AND MUTATIONAL STATUS CONFIRMED A SIGNIFICANT INFERIOR OS TO PATIENTS WITH A BCOR MUTATION (HAZARD RATIO, 3.3; 95% CONFIDENCE INTERVAL, 1.4-8.1; P = .008). THESE DATA SUGGEST THAT BCOR MUTATIONS DEFINE THE CLINICAL COURSE RATHER THAN DISEASE INITIATION. DESPITE INFREQUENT MUTATIONS, BCOR ANALYSES SHOULD BE CONSIDERED IN RISK STRATIFICATION. 2013 2 5665 46 SF3B1, RUNX1 AND TP53 MUTATIONS SIGNIFICANTLY IMPACT THE OUTCOME OF PATIENTS WITH LOWER-RISK MYELODYSPLASTIC SYNDROME. INTRODUCTION: PROGNOSIS OF PATIENTS WITH MYELODYSPLASTIC SYNDROME (MDS), PARTICULARLY THE GROUP WITH LOWER-RISK DISEASE (LR-MDS) IS VERY HETEROGENEOUS. SEVERAL STUDIES HAVE DESCRIBED THE PROGNOSTIC VALUE OF RECURRENT SOMATIC MUTATIONS IN MDS INCLUDING ALL RISK CATEGORIES. RECENTLY, THE INCORPORATION OF GENOMIC DATA TO CLINICAL PARAMETERS DEFINED THE NEW MOLECULAR INTERNATIONAL PROGNOSTIC SCORING SYSTEM (IPSS-M). MATERIALS AND METHODS: IN THIS STUDY, WE EVALUATED THE IMPACT OF MOLECULAR PROFILE IN A SERIES OF 181 PATIENTS WITH LR-MDS AND NON-PROLIFERATIVE CHRONIC MYELOMONOCYTIC LEUKEMIA. RESULTS: EPIGENETIC REGULATORS (TET2, ASXL1) AND SPLICING (SF3B1) WERE THE MOST RECURRENT MUTATED PATHWAYS. IN UNIVARIATE ANALYSIS, RUNX1 OR TP53 MUTATIONS CORRELATED WITH LOWER MEDIAN OVERALL SURVIVAL (OS). IN CONTRAST, SF3B1 MUTATION WAS ASSOCIATED WITH PROLONGED MEDIAN OS [95 MONTHS (95% IC, 32-157) VS. 33 MONTHS (95% CI, 19-46) IN UNMUTATED PATIENTS (P < 0.01)]. IN A MULTIVARIATE COX REGRESSION MODEL, RUNX1 MUTATIONS INDEPENDENTLY ASSOCIATED WITH SHORTER OS, WHILE SF3B1 MUTATION RETAINED ITS FAVORABLE IMPACT ON OUTCOME (HR: 0.24, 95% CI, 0.1-0.5; P = 0.001). IN ADDITION, TP53 OR RUNX1 MUTATIONS WERE IDENTIFIED AS PREDICTIVE COVARIATES FOR THE PROBABILITY OF LEUKEMIC PROGRESSION (P < 0.001). CONCLUSION: INCORPORATION OF MOLECULAR TESTING IN LR-MDS IDENTIFIED A SUBSET OF PATIENTS WITH EXPECTED POORER OUTCOME, EITHER DUE TO LOWER SURVIVAL OR PROBABILITY OF LEUKEMIC PROGRESSION. 2022 3 4571 25 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 4 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 5 3560 41 IMPACT OF CLINICAL, CYTOGENETIC, AND MOLECULAR PROFILES ON LONG-TERM SURVIVAL AFTER TRANSPLANTATION IN PATIENTS WITH CHRONIC MYELOMONOCYTIC LEUKEMIA. CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) IS A HETEROGENEOUS GROUP OF CLONAL HEMATOPOIETIC MALIGNANCIES WITH VARIABLE CLINICAL AND MOLECULAR FEATURES. WE ANALYZED LONG-TERM RESULTS OF ALLOGENEIC HEMATOPOIETIC CELL TRANSPLANTATION IN PATIENTS WITH CMML AND DETERMINED CLINICAL AND MOLECULAR RISK FACTORS ASSOCIATED WITH OUTCOMES. DATA FROM 129 PATIENTS, AGED 7-74 (MEDIAN 55) YEARS, AT VARIOUS STAGES OF THE DISEASE AND TRANSPLANTED FROM RELATED OR UNRELATED DONORS WERE ANALYZED. USING A PANEL OF 75 GENES SOMATIC MUTATIONS PRESENT BEFORE HEMATOPOIETIC CELL TRANSPLANTATION WERE IDENTIFIED IN 52 PATIENTS. THE PROGRESSION-FREE SURVIVAL RATE AT 10 YEARS WAS 29%. THE MAJOR CAUSE OF DEATH WAS RELAPSE (32%), WHICH WAS SIGNIFICANTLY ASSOCIATED WITH ADVERSE CYTOGENETICS (HAZARD RATIO, 3.77; P=0.0002), CMML PROGNOSTIC SCORING SYSTEM (HAZARD RATIO, 14.3, P=0.01), AND MD ANDERSON PROGNOSTIC SCORES (HAZARD RATIO, 9.4; P=0.005). MORTALITY WAS ASSOCIATED WITH HIGH-RISK CYTOGENETICS (HAZARD RATIO, 1.88; P=0.01) AND HIGH HEMATOPOIETIC CELL TRANSPLANTATION COMORBIDITY INDEX (SCORE >/=4: HAZARD RATIO, 1.99; P=0.01). HIGH OVERALL MUTATION BURDEN (>/=10 MUTATIONS: HAZARD RATIO, 3.4; P=0.02), AND >/=4 MUTATED EPIGENETIC REGULATORY GENES (HAZARD RATIO 5.4; P=0.003) WERE LINKED TO RELAPSE. UNSUPERVISED CLUSTERING OF THE CORRELATION MATRIX REVEALED DISTINCT HIGH-RISK GROUPS WITH UNIQUE ASSOCIATIONS OF MUTATIONS AND CLINICAL FEATURES. CMML WITH A HIGH MUTATION BURDEN APPEARED TO BE DISTINCT FROM HIGH-RISK GROUPS DEFINED BY COMPLEX CYTOGENETICS. NEW TRANSPLANT STRATEGIES MUST BE DEVELOPED TO TARGET SPECIFIC DISEASE SUBGROUPS, STRATIFIED BY MOLECULAR PROFILING AND CLINICAL RISK FACTORS. 2020 6 4555 32 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 7 5984 29 TET2, DNMT3A, IDH1, AND JAK2 MUTATION IN MYELOPROLIFERATIVE NEOPLASMS IN SOUTHERN IRAN. BACKGROUND: FIVE EPIGENETIC REGULATOR MUTATIONS ARE CONSIDERED IN MYELOPROLIFERATIVE NEOPLASMS (MPN) THAT HAVE PROGNOSTIC AND THERAPEUTIC VALUES. OBJECTIVE: WE AIMED TO EVALUATE THESE MUTATIONS IN MPNS AMONG THE IRANIAN POPULATION. METHODS: WE SELECTED 5 MUTATIONS IN 4 EPIGENETIC REGULATORY GENES [TET2, DNMT3A, IDH1 (RS147001633&RS121913499), AND JAK2)] AND EVALUATED 130 PATIENTS WITH MPNS INCLUDING 78 PHILADELPHIA CHROMOSOME NEGATIVE (49 ETS, 20 PVS, AND 9 PMFS) AND 52 PHILADELPHIA CHROMOSOME-POSITIVE PATIENTS AS WELL AS 51 HEALTHY CONTROLS. RESULTS: EIGHT PATIENTS (6.5%) CARRIED THE DNMT3A MUTATION, 35 (27%) WERE POSITIVE FOR TET2 MUTATION AND 64 (49.3%) HAD THE JAK2V617F MUTATION. IN THE HEALTHY CONTROLS, 16 (31.4%) CASES HAD THE TET2 MUTATION (15 HETEROZYGOTE + 1 HOMOZYGOTE) AND ONE HAD HETEROZYGOTE JAK2 MUTATION. THERE WAS NO STATISTICALLY SIGNIFICANT DIFFERENCE BETWEEN PATIENT GROUPS FOR ANY OF THESE MUTATIONS, EXCEPT FOR JAK2. THE JAK2 MUTATION RATE WAS 18 (90%), 25 (51%), 7 (77.8%), 14 (26.9%) IN POLYCYTHEMIA VERA, ESSENTIAL THROMBOCYTHEMIA, PRIMARY MYELOFIBROSIS, AND CHRONIC MYELOCYTIC LEUKEMIA, RESPECTIVELY. PATIENTS AGED 60 AND OLDER WERE MORE LIKELY TO CARRY THE TET2 MUTATION (23% VS. 39% IN YOUNGER AND OLDER THAN 60 YEARS OLD INDIVIDUALS, P=0.025). IDH1 WAS NOT DETECTED AT ALL AND PV HAD THE HIGHEST TET2 MUTATION 7(35%). TWO PMF PATIENTS HAD A HISTORY OF BONE MARROW TRANSPLANTATION THAT WERE NEGATIVE FOR IDH1AND DNMT3A AND ONE WAS POSITIVE FOR TET2 MUTATION. CONCLUSION: IN THE NORMAL IRANIAN POPULATION, THE HETEROZYGOTE FORM OF TET2 MUTATION IS SIGNIFICANT, ESPECIALLY IN THE ELDERLY. NO ASSOCIATION WAS FOUND BETWEEN JAK2 AND TET2 MUTATIONS. BOTH OF THEM ARE MORE PREVALENT IN THE AGE GROUP OF 60 YEARS AND OLDER. DNMT3A MUTATION HAS A LOW PREVALENCE AND OCCURS IN BOTH POSITIVE AND NEGATIVE MPNS. 2021 8 1083 42 CNL AND ACML SHOULD BE CONSIDERED AS A SINGLE ENTITY BASED ON MOLECULAR PROFILES AND OUTCOMES. CHRONIC NEUTROPHILIC LEUKEMIA (CNL) AND ATYPICAL CHRONIC MYELOID LEUKEMIA (ACML) ARE RARE MYELOID DISORDERS THAT ARE CHALLENGING WITH REGARD TO DIAGNOSIS AND CLINICAL MANAGEMENT. TO STUDY THE SIMILARITIES AND DIFFERENCES BETWEEN THESE DISORDERS, WE UNDERTOOK A MULTICENTER INTERNATIONAL STUDY OF ONE OF THE LARGEST CASE SERIES (CNL, N = 24; ACML, N = 37 CASES, RESPECTIVELY), FOCUSING ON THE CLINICAL AND MUTATIONAL PROFILES (N = 53 WITH MOLECULAR DATA) OF THESE DISEASES. WE FOUND NO DIFFERENCES IN CLINICAL PRESENTATIONS OR OUTCOMES OF BOTH ENTITIES. AS PREVIOUSLY DESCRIBED, BOTH CNL AND ACML SHARE A COMPLEX MUTATIONAL PROFILE WITH MUTATIONS IN GENES INVOLVED IN EPIGENETIC REGULATION, SPLICING, AND SIGNALING PATHWAYS. APART FROM CSF3R, ONLY EZH2 AND TET2 WERE DIFFERENTIALLY MUTATED BETWEEN THEM. THE MOLECULAR PROFILES SUPPORT THE NOTION OF CNL AND ACML BEING A CONTINUUM OF THE SAME DISEASE THAT MAY FIT BEST WITHIN THE MYELODYSPLASTIC/MYELOPROLIFERATIVE NEOPLASMS. WE IDENTIFIED 4 HIGH-RISK MUTATED GENES, SPECIFICALLY CEBPA (BETA = 2.26, HAZARD RATIO [HR] = 9.54, P = .003), EZH2 (BETA = 1.12, HR = 3.062, P = .009), NRAS (BETA = 1.29, HR = 3.63, P = .048), AND U2AF1 (BETA = 1.75, HR = 5.74, P = .013) USING MULTIVARIATE ANALYSIS. OUR FINDINGS UNDERSCORE THE RELEVANCE OF MOLECULAR-RISK CLASSIFICATION IN CNL/ACML AS WELL AS THE IMPORTANCE OF CSF3R MUTATIONS IN THESE DISEASES. 2023 9 5246 44 PROGNOSTIC SCORE INCLUDING GENE MUTATIONS IN CHRONIC MYELOMONOCYTIC LEUKEMIA. PURPOSE: SEVERAL PROGNOSTIC SCORING SYSTEMS HAVE BEEN PROPOSED FOR CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML), A DISEASE IN WHICH SOME GENE MUTATIONS-INCLUDING ASXL1-HAVE BEEN ASSOCIATED WITH POOR PROGNOSIS IN UNIVARIABLE ANALYSES. WE DEVELOPED AND VALIDATED A PROGNOSTIC SCORE FOR OVERALL SURVIVAL (OS) BASED ON MUTATIONAL STATUS AND STANDARD CLINICAL VARIABLES. PATIENTS AND METHODS: WE GENOTYPED ASXL1 AND UP TO 18 OTHER GENES INCLUDING EPIGENETIC (TET2, EZH2, IDH1, IDH2, DNMT3A), SPLICING (SF3B1, SRSF2, ZRSF2, U2AF1), TRANSCRIPTION (RUNX1, NPM1, TP53), AND SIGNALING (NRAS, KRAS, CBL, JAK2, FLT3) REGULATORS IN 312 PATIENTS WITH CMML. GENOTYPES AND CLINICAL VARIABLES WERE INCLUDED IN A MULTIVARIABLE COX MODEL OF OS VALIDATED BY BOOTSTRAPPING. A SCORING SYSTEM WAS DEVELOPED USING REGRESSION COEFFICIENTS FROM THIS MODEL. RESULTS: ASXL1 MUTATIONS (P < .0001) AND, TO A LESSER EXTENT, SRSF2 (P = .03), CBL (P = .003), AND IDH2 (P = .03) MUTATIONS PREDICTED INFERIOR OS IN UNIVARIABLE ANALYSIS. THE RETAINED INDEPENDENT PROGNOSTIC FACTORS INCLUDED ASXL1 MUTATIONS, AGE OLDER THAN 65 YEARS, WBC COUNT GREATER THAN 15 X10(9)/L, PLATELET COUNT LESS THAN 100 X10(9)/L, AND ANEMIA (HEMOGLOBIN < 10 G/DL IN FEMALE PATIENTS, < 11G/DL IN MALE PATIENTS). THE RESULTING FIVE-PARAMETER PROGNOSTIC SCORE DELINEATED THREE GROUPS OF PATIENTS WITH MEDIAN OS NOT REACHED, 38.5 MONTHS, AND 14.4 MONTHS, RESPECTIVELY (P < .0001), AND WAS VALIDATED IN AN INDEPENDENT COHORT OF 165 PATIENTS (P < .0001). CONCLUSION: A NEW PROGNOSTIC SCORE INCLUDING ASXL1 STATUS, AGE, HEMOGLOBIN, WBC, AND PLATELET COUNTS DEFINES THREE GROUPS OF CMML PATIENTS WITH DISTINCT OUTCOMES. BASED ON CONCORDANCE ANALYSIS, THIS SCORE APPEARS MORE DISCRIMINATIVE THAN THOSE BASED SOLELY ON CLINICAL PARAMETERS. 2013 10 5980 34 TET2 MUTATIONS WERE PREDICTIVE OF INFERIOR PROGNOSIS IN THE PRESENCE OF ASXL1 MUTATIONS IN PATIENTS WITH CHRONIC MYELOMONOCYTIC LEUKEMIA. BACKGROUND: SOMATIC MUTATIONS INVOLVING EPIGENETIC REGULATORS, HISTONE MODIFICATION AND CHROMATIN REGULATION, SPLICING COMPONENTS, TRANSCRIPTION FACTORS AND SIGNALING REGULATOR GENES ARE COMMON IN CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) PATIENTS. IT HAS BEEN CONSENSUS THAT ASXL1 MUTATIONS HAVE ADVERSELY IMPACT ON OVERALL SURVIVAL (OS), WHILE THE EFFECT OF TET2 MUTATIONS REMAINS CONTROVERSIAL AND UNDEFINED. METHODS: ASXL1 AND TET2 MUTATIONS WERE ANALYZED IN 141 PATIENTS WITH CMML USING SANGER SEQUENCING, WITH THE AIM TO IDENTIFY THE INTERPLAY OF ASXL1 AND TET2 MUTATIONS IN THE PROGNOSIS OF CMML. RESULTS: SIXTY-FIVE (46.1%) OF THE CMML PATIENTS HARBORED ASXL1 MUTATIONS (FRAMESHIFT AND NONSENSE), AND 46 (32.6%) HAD TET2 MUTATIONS (FRAME SHIFT, NONSENSE AND MISSENSE). IN A SEPARATE MULTIVARIABLE ANALYSIS THAT INCLUDED THE MAYO PROGNOSTIC MODEL AS A SINGLE VARIABLE ALONG WITH ASXL1WT/TET2WT, THE RESPECTIVE HAZARD RATIOS OF ASXL1MUT/TET2MUT, ASXL1MUT/TET2WT AND ASXL1WT/TET2MUT WERE 4.7 (95% CI, 2.2-10.3; P<0.001), 2.2 (95% CI, 1.1-4.2; P=0.025) AND 1.3 (95% CI, 0.6-2.5; P=0.521). CONCLUSIONS: OUR STUDY SHOWED THAT ASXL1 MUTATIONS PREDICT INFERIOR OS, AND ADDITIONAL TET2 MUTATIONS WERE ASSOCIATED WITH POOR SURVIVAL IN THE PRESENCE OF ASXL1 MUTATIONS OF CMML PATIENTS. 2016 11 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 12 2678 39 EVALUATION OF A PROGNOSTIC EPIGENETIC CLASSIFICATION SYSTEM IN CHRONIC LYMPHOCYTIC LEUKEMIA PATIENTS. BACKGROUND: METHYLATION AT 5 CPG SITES WAS PREVIOUSLY SHOWN TO CLASSIFY CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) INTO 3 PROGNOSTIC SUBGROUPS. HERE, WE AIMED TO VALIDATE THE MARKER SET IN AN ADDITIONAL COHORT AND TO EVALUATE ITS CLINICAL UTILITY FOR CLL PATIENT STRATIFICATION. METHODS: WE EVALUATED THIS EPIGENETIC MARKER SET IN 79 GERMAN PATIENTS USING BISULFITE TREATMENT FOLLOWED BY PYROSEQUENCING AND CLASSIFICATION USING A SUPPORT VECTOR MACHINE-LEARNING TOOL. RESULTS: THE N-CLL, I-CLL, AND M-CLL CLASSIFICATION WAS DETECTED IN 28 (35%), 10 (13%), AND 41 (51%) PATIENTS, RESPECTIVELY. EPIGENETIC GROUPING WAS ASSOCIATED WITH IGHV MUTATIONAL STATUS (P = 2 X 10(-12)), ISOLATED DEL13Q (P = 9 X 10(-6)), DEL17P (P = .015), COMPLEX KARYOTYPE (P = .005), VH-USAGE, AND CLINICAL OUTCOME AS TIME TO FIRST TREATMENT (P = 1.4 X 10(-12)) AND OVERALL SURVIVAL (P = .003). MULTIVARIATE COX REGRESSION ANALYSIS IDENTIFIED N-CLL AS A FACTOR FOR EARLIER TREATMENT HAZARD RATIO (HR), 6.3 (95% CONFIDENCE INTERVAL [CI] 2.4-16.4; P = .0002) COMPARED TO IGHV MUTATIONAL STATUS (HR 4.6, 95% CI 1.9-11.3, P = .0008). IN ADDITION, WHEN COMPARING THE PROGNOSTIC VALUE OF THE EPIGENETIC CLASSIFICATION SYSTEM WITH THE IGHV CLASSIFICATION, EPIGENETIC GROUPING PERFORMED BETTER COMPARED TO IGHV MUTATIONAL STATUS USING KAPLAN-MEIER ESTIMATION AND ALLOWED THE IDENTIFICATION OF A THIRD, INTERMEDIATE (I-CLL) GROUP. THUS, OUR STUDY CONFIRMED THE PROGNOSTIC VALUE OF THE EPIGENETIC MARKER SET FOR PATIENT STRATIFICATION IN ROUTINE CLINICAL DIAGNOSTICS. 2022 13 536 32 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 14 4549 31 MUTATION ANALYSIS OF THERAPY-RELATED MYELOID NEOPLASMS. WE ANALYZED THE GENETIC MUTATION STATUS OF 13 PATIENTS WITH THERAPY-RELATED MYELOID NEOPLASMS (T-MN). CONSISTENT WITH PREVIOUS REPORTS, T-MN CELLS PREFERENTIALLY ACQUIRED MUTATIONS IN TP53 AND EPIGENETIC MODIFYING GENES, INSTEAD OF MUTATIONS IN TYROSINE KINASE AND SPLICEOSOME GENES. FURTHERMORE, WE COMPARED THE MUTATION STATUS OF THREE T-MN CELLS WITH EACH OF THE INITIAL LYMPHOID MALIGNANT CELLS, AND IDENTIFIED COMMON MUTATIONS AMONG T-MN AND THE INITIAL MALIGNANT CELLS IN TWO PATIENTS. IN A PATIENT WHO DEVELOPED CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) AFTER FOLLICULAR LYMPHOMA (FL), TET2 MUTATION WAS IDENTIFIED IN BOTH CMML AND FL CELLS. NOTABLY, THE TET2 MUTATION WAS ALSO IDENTIFIED IN PERIPHERAL BLOOD CELLS IN THE DISEASE-FREE PERIOD WITH THE SAME ALLELIC FREQUENCY AS CMML AND FL CELLS, BUT NOT IN A GERM-LINE CONTROL, INDICATING THAT THE TET2 MUTATION OCCURRED SOMATICALLY IN THE INITIATING CLONE FOR BOTH MALIGNANT CELLS. ON THE OTHER HAND, A GERM-LINE MYB MUTATION WAS IDENTIFIED IN A PATIENT WHO DEVELOPED MYELODYSPLASTIC SYNDROMES (MDS) AFTER FL. THESE RESULTS SUGGEST THAT GERM-LINE DEPOSITION AND CLONAL HEMATOPOIESIS ARE CLOSELY ASSOCIATED WITH T-MN SUSCEPTIBILITY; HOWEVER, FURTHER ANALYSIS IS NECESSARY TO CLARIFY THE MECHANISM REQUIRED TO PROVIDE THE INITIATING CLONE WITH LINEAGE COMMITMENT AND CLONAL EXPANSION. 2018 15 4540 29 MULTISTEP PATHOGENESIS OF CHRONIC MYELOMONOCYTIC LEUKEMIA IN PATIENTS. BACKGROUND: A MULTISTEP PATHOGENESIS OF MYELOID LEUKEMIA INCLUDING MUTATIONS IN EPIGENETIC, SPLICEOSOME, AND SIGNALING GENES HAS BEEN RECENTLY DEMONSTRATED IN A PRECLINICAL MODEL BUT IS POORLY VALIDATED IN PATIENTS. METHODS: CLINICAL, PHENOTYPIC, AND BIOLOGIC FEATURES WERE COMPARED BETWEEN THREE DISTINCT MOLECULARLY DEFINED CMML COHORTS INCLUDING TET2 MONOMUTATED PATIENTS (T, N = 10), TET2/SRSF2 BIMUTATED PATIENTS (TS, N = 19), AND PATIENTS WHO HAD NRAS MUTATIONS IN ADDITION TO TET2/SRSF2 COMUTATIONS (TSN, N = 14). RESULTS: MEDIAN SURVIVAL WAS 90, 45, AND 9 MONTHS, RESPECTIVELY (P = .001). WHEREAS NO PATIENT IN THE T AND TS GROUP TRANSFORMED INTO ACUTE MYELOID LEUKEMIA (AML), 6/14 PATIENTS IN THE TSN GROUP HAD AML AT STUDY ENTRY OR TRANSFORMED DURING FOLLOW-UP. LEUKOCYTE COUNTS, BLAST CELL COUNTS, AND LDH LEVELS WERE SIGNIFICANTLY HIGHER IN TSN VS. TS AND T, RESPECTIVELY, WHEREAS HEMOGLOBIN AND PLATELET VALUES WERE NOT SIGNIFICANTLY DIFFERENT. INCREASED GROWTH FACTOR-INDEPENDENT MYELOID COLONY FORMATION WAS RESTRICTED TO TSN BUT NOT FOUND IN T AND TS, RESPECTIVELY. THE PROPORTION OF PATIENTS SHOWING IN VITRO MYELOMONOCYTIC SKEWING IN T, TS, AND TSN WAS 0%, 56%, AND 100%, RESPECTIVELY (P = .010). CONCLUSION: OUR RESULTS DEMONSTRATE THAT THE MODEL OF MULTISTEP PATHOGENESIS IN CMML CAN BE RECAPITULATED IN PATIENTS REGARDING CLINICAL, PHENOTYPIC, AND BIOLOGIC FEATURES. 2022 16 1070 24 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 17 4485 32 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 18 1100 26 COMBINATION OF MYELOPROLIFERATIVE NEOPLASM DRIVER GENE ACTIVATION WITH MUTATIONS OF SPLICE FACTOR OR EPIGENETIC MODIFIER GENES INCREASES RISK OF RAPID BLASTIC PROGRESSION. OBJECTIVES: MYELOPROLIFERATIVE NEOPLASMS (MPN) COMPRISING POLYCYTHEMIA VERA (PV), ESSENTIAL THROMBOCYTHEMIA (ET) AND PRIMARY MYELOFIBROSIS (PMF) FOLLOW A BI-PHASIC COURSE OF DISEASE WITH FIBROTIC AND/OR BLASTIC PROGRESSION. AT PRESENTATION IN THE CHRONIC PHASE, CURRENTLY THERE ARE ONLY INSUFFICIENT TOOLS TO PREDICT THE RISK OF PROGRESSION IN INDIVIDUAL CASES. METHODS: IN THIS STUDY, CHRONIC PHASE MPN (16 PMF, 11 PV, AND 11 MPN UNCLASSIFIED) WITH BLASTIC TRANSFORMATION DURING COURSE OF DISEASE (N = 38, MEDIAN FOLLOW-UP 5.3 YEARS) WERE ANALYZED BY HIGH-THROUGHPUT SEQUENCING. MPN CASES WITH A COMPARABLE FOLLOW-UP PERIOD AND WITHOUT EVIDENCE OF BLAST INCREASE SERVED AS CONTROL (N = 63, MEDIAN FOLLOW-UP 5.8 YEARS). RESULTS: FREQUENT ARCH/CHIP-ASSOCIATED MUTATIONS (TET2, ASXL1, DNMT3A) FOUND AT PRESENTATION WERE NOT SIGNIFICANTLY ASSOCIATED WITH BLASTIC TRANSFORMATION. BY CONTRAST, MUTATIONS OF SRSF2, U2AF1, AND IDH1/2 AT FIRST PRESENTATION WERE FREQUENTLY OBSERVED IN THE PROGRESSION COHORT (13/38, 34.2%) AND WERE COMPLETELY MISSING IN THE CONTROL GROUP WITHOUT BLAST TRANSFORMATION DURING FOLLOW-UP (P = .0007 FOR SRSF2; P = .0063 FOR U2AF1 AND IDH1/2). CONCLUSION: UNLIKE FREQUENT ARCH/CHIP ALTERATIONS (TET2, ASXL1, DNMT3A), MUTATIONS IN SRSF2, IDH1/2, AND U2AF1 WHEN MANIFEST ALREADY AT FIRST PRESENTATION PROVIDE AN INDEPENDENT RISK FACTOR FOR RAPID BLAST TRANSFORMATION OF MPN. 2021 19 2848 32 FREQUENT SOMATIC MUTATIONS IN EPIGENETIC REGULATORS IN NEWLY DIAGNOSED CHRONIC MYELOID LEUKEMIA. ALTHOUGH TYROSINE KINASE INHIBITORS (TKIS) HAVE SIGNIFICANTLY IMPROVED THE PROGNOSIS OF CHRONIC MYELOID LEUKEMIA (CML), THE ABILITY OF TKIS TO ERADICATE CML REMAINS UNCERTAIN AND PATIENTS MUST CONTINUE TKI THERAPY FOR INDEFINITE PERIODS. IN THIS STUDY, WE PERFORMED WHOLE-EXOME SEQUENCING TO IDENTIFY SOMATIC MUTATIONS IN 24 PATIENTS WITH NEWLY DIAGNOSED CHRONIC PHASE CML WHO WERE REGISTERED IN THE JALSG CML212 STUDY. WE IDENTIFIED 191 SOMATIC MUTATIONS OTHER THAN THE BCR-ABL1 FUSION GENE (MEDIAN 8, RANGE 1-17). AGE, HEMOGLOBIN CONCENTRATION AND WHITE BLOOD CELL COUNTS WERE CORRELATED WITH THE NUMBER OF MUTATIONS. PATIENTS WITH MUTATIONS ?6 SHOWED HIGHER RATE OF ACHIEVING MAJOR MOLECULAR RESPONSE THAN THOSE<6 (P=0.0381). MUTATIONS IN EPIGENETIC REGULATOR, ASXL1, TET2, TET3, KDM1A AND MSH6 WERE FOUND IN 25% OF PATIENTS. TET2 OR TET3, AKT1 AND RUNX1 WERE MUTATED IN ONE PATIENT EACH. ASXL1 WAS MUTATED WITHIN EXON 12 IN THREE CASES. MUTATED GENES WERE SIGNIFICANTLY ENRICHED WITH CELL SIGNALING AND CELL DIVISION PATHWAYS. FURTHERMORE, DNA COPY NUMBER ANALYSIS SHOWED THAT 2 OF 24 PATIENTS HAD UNIPARENTAL DISOMY OF CHROMOSOME 1P OR 3Q, WHICH DISAPPEARED MAJOR MOLECULAR RESPONSE WAS ACHIEVED. THESE MUTATIONS MAY PLAY SIGNIFICANT ROLES IN CML PATHOGENESIS IN ADDITION TO THE STRONG DRIVER MUTATION BCR-ABL1. 2017 20 27 27 A B-CELL EPIGENETIC SIGNATURE DEFINES THREE BIOLOGIC SUBGROUPS OF CHRONIC LYMPHOCYTIC LEUKEMIA WITH CLINICAL IMPACT. PROSPECTIVE IDENTIFICATION OF PATIENTS WITH CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) DESTINED TO PROGRESS WOULD GREATLY FACILITATE THEIR CLINICAL MANAGEMENT. RECENTLY, WHOLE-GENOME DNA METHYLATION ANALYSES IDENTIFIED THREE CLINICOBIOLOGIC CLL SUBGROUPS WITH AN EPIGENETIC SIGNATURE RELATED TO DIFFERENT NORMAL B-CELL COUNTERPARTS. HERE, WE DEVELOPED A CLINICALLY APPLICABLE METHOD TO IDENTIFY THESE SUBGROUPS AND TO STUDY THEIR CLINICAL RELEVANCE. USING A SUPPORT VECTOR MACHINE APPROACH, WE BUILT A PREDICTION MODEL USING FIVE EPIGENETIC BIOMARKERS THAT WAS ABLE TO CLASSIFY CLL PATIENTS ACCURATELY INTO THE THREE SUBGROUPS, NAMELY NAIVE B-CELL-LIKE, INTERMEDIATE AND MEMORY B-CELL-LIKE CLL. DNA METHYLATION WAS QUANTIFIED BY HIGHLY REPRODUCIBLE BISULFITE PYROSEQUENCING ASSAYS IN TWO INDEPENDENT CLL SERIES. IN THE INITIAL SERIES (N=211), THE THREE SUBGROUPS SHOWED DIFFERENTIAL LEVELS OF IGHV (IMMUNOGLOBULIN HEAVY-CHAIN LOCUS) MUTATION (P<0.001) AND VH USAGE (P<0.03), AS WELL AS DIFFERENT CLINICAL FEATURES AND OUTCOME IN TERMS OF TIME TO FIRST TREATMENT (TTT) AND OVERALL SURVIVAL (P<0.001). A MULTIVARIATE COX MODEL SHOWED THAT EPIGENETIC CLASSIFICATION WAS THE STRONGEST PREDICTOR OF TTT (P<0.001) ALONG WITH BINET STAGE (P<0.001). THESE FINDINGS WERE CORROBORATED IN A VALIDATION SERIES (N=97). IN THIS STUDY, WE DEVELOPED A SIMPLE AND ROBUST METHOD USING EPIGENETIC BIOMARKERS TO CATEGORIZE CLLS INTO THREE SUBGROUPS WITH DIFFERENT CLINICOBIOLOGIC FEATURES AND OUTCOME. 2015