1 1076 136 CLONAL HEMATOPOIESIS IN MYELOPROLIFERATIVE NEOPLASMS CONFERS A PREDISPOSITION TO BOTH THROMBOSIS AND CANCER. PURPOSE OF REVIEW: THIS REVIEW FOCUSES ON VASCULAR COMPLICATIONS ASSOCIATED WITH CHRONIC MYELOPROLIFERATIVE NEOPLASMS (MPN) AND MORE SPECIFICALLY AIMS TO DISCUSS THE CLINICAL AND BIOLOGICAL EVIDENCE SUPPORTING THE EXISTENCE OF A LINK BETWEEN CLONAL HEMATOPOIESIS, CARDIOVASCULAR EVENTS (CVE), AND SOLID CANCER (SC). RECENT FINDINGS: THE MPN NATURAL HISTORY IS DRIVEN BY UNCONTROLLED CLONAL MYELOPROLIFERATION SUSTAINED BY ACQUIRED SOMATIC MUTATIONS IN DRIVER (JAK2, CALR, AND MPL) AND NON-DRIVER GENES, INVOLVING EPIGENETIC (E.G., TET2, DNMT3A) REGULATORS, CHROMATIN REGULATOR GENES (E.G., ASXL1, EZH2), AND SPLICING MACHINERY GENES (E.G., SF3B1). THE GENOMIC ALTERATIONS AND ADDITIONAL THROMBOSIS ACQUIRED RISK FACTORS ARE DETERMINANTS FOR CVE. THERE IS EVIDENCE THAT CLONAL HEMATOPOIESIS CAN ELICIT A CHRONIC AND SYSTEMIC INFLAMMATION STATUS THAT ACTS AS DRIVING FORCE FOR THE DEVELOPMENT OF THROMBOSIS, MPN EVOLUTION, AND SECOND CANCER (SC). THIS NOTION MAY EXPLAIN THE MECHANISM THAT LINKS ARTERIAL THROMBOSIS IN MPN PATIENTS AND SUBSEQUENT SOLID TUMORS. IN THE LAST DECADE, CLONAL HEMATOPOIESIS OF INDETERMINATE POTENTIAL (CHIP) HAS BEEN DETECTED IN THE GENERAL POPULATION PARTICULARLY IN THE ELDERLY AND INITIALLY FOUND IN MYOCARDIAL INFARCTION AND STROKE, RISING THE HYPOTHESIS THAT THE INFLAMMATORY STATUS CHIP-ASSOCIATED COULD CONFER PREDISPOSITION TO BOTH CARDIOVASCULAR DISEASES AND CANCER. IN SUMMARY, CLONAL HEMATOPOIESIS IN MPN AND CHIP CONFER A PREDISPOSITION TO CARDIOVASCULAR EVENTS AND CANCER THROUGH CHRONIC AND SYSTEMIC INFLAMMATION. THIS ACQUISITION COULD OPEN NEW AVENUES FOR ANTITHROMBOTIC THERAPY BOTH IN MPNS AND IN GENERAL POPULATION BY TARGETING BOTH CLONAL HEMATOPOIESIS AND INFLAMMATION. 2023 2 1077 48 CLONAL HEMATOPOIESIS OF INDETERMINATE POTENTIAL (CHIP): LINKING SOMATIC MUTATIONS, HEMATOPOIESIS, CHRONIC INFLAMMATION AND CARDIOVASCULAR DISEASE. CLONAL HEMATOPOIESIS OF INDETERMINATE POTENTIAL (CHIP) IS THE PRESENCE OF A CLONALLY EXPANDED HEMATOPOIETIC STEM CELL CAUSED BY A LEUKEMOGENIC MUTATION IN INDIVIDUALS WITHOUT EVIDENCE OF HEMATOLOGIC MALIGNANCY, DYSPLASIA, OR CYTOPENIA. CHIP IS ASSOCIATED WITH A 0.5-1.0% RISK PER YEAR OF LEUKEMIA. REMARKABLY, IT CONFERS A TWO-FOLD INCREASE IN CARDIOVASCULAR RISK INDEPENDENT OF TRADITIONAL RISK FACTORS. ROUGHLY 80% OF PATIENTS WITH CHIP HAVE MUTATIONS IN EPIGENETIC REGULATORS DNMT3A, TET2, ASXL1, DNA DAMAGE REPAIR GENES PPM1D, TP53, THE REGULATORY TYROSINE KINASE JAK2, OR MRNA SPLICEOSOME COMPONENTS SF3B1, AND SRSF2. CHIP IS ASSOCIATED WITH A PRO-INFLAMMATORY STATE THAT HAS BEEN LINKED TO CORONARY ARTERY DISEASE, MYOCARDIAL INFARCTION, AND VENOUS THROMBOEMBOLIC DISEASE, AS WELL AS PROGNOSIS AMONG THOSE WITH AORTIC STENOSIS AND HEART FAILURE. HERITABLE AND ACQUIRED RISK FACTORS ARE ASSOCIATED WITH INCREASED CHIP PREVALENCE, INCLUDING GERMLINE VARIATION, AGE, UNHEALTHY LIFESTYLE BEHAVIORS (I.E. SMOKING, OBESITY), INFLAMMATORY CONDITIONS, PREMATURE MENOPAUSE, HIV AND EXPOSURE TO CANCER THERAPIES. THIS REVIEW AIMS TO SUMMARIZE EMERGING RESEARCH ON CHIP, THE MECHANISMS UNDERLYING ITS IMPORTANT ROLE IN PROPAGATING INFLAMMATION AND ACCELERATING CARDIOVASCULAR DISEASE, AND NEW STUDIES DETAILING THE ROLE OF ASSOCIATED RISK FACTORS AND CO-MORBIDITIES THAT INCREASE CHIP PREVALENCE. 2021 3 6852 32 [MYELOPROLIFERATIVE NEOPLASMS: UPDATES ON MOLECULAR PATHOPHYSIOLOGY, DIAGNOSIS AND TREATMENT STRATEGIES]. MYELOPROLIFERATIVE NEOPLASMS (MPNS) ARE CHRONIC HEMATOPOIETIC STEM CELL DISORDERS, INCLUDING POLYCYTHEMIA VERA, ESSENTIAL THROMBOCYTOSIS, AND PRIMARY MYELOFIBROSIS. THE JAK2V617F MUTATION WAS IDENTIFIED IN 2005, FOLLOWED BY THE DISCOVERY OF THE JAK2 EXON12, MPNW515 MUTATION, AND CALR MUTATION. ABOUT 90% OF PATIENTS WITH BCR/ABL NEGATIVE MPNS HAVE BEEN SHOWN TO HAVE ONE OF THESE DRIVER MUTATIONS. IN ADDITION, MUTATIONS IN EPIGENETIC REGULATORS AND RNA SPLICING GENES WERE FOUND TO CO-EXIST WITH DRIVER MUTATIONS AND TO PLAY CRITICAL ROLES IN THE DISEASE PROGRESSION OF MPNS. CURRENTLY, EVALUATIONS OF THESE GENE MUTATIONS ARE ESSENTIAL FOR THE DIAGNOSIS OF MPNS, AND ARE ALSO NECESSARY FOR ESTIMATING THE CLINICAL COURSE AND THE RISK OF DISEASE PROGRESSION. GUIDELINES FOR THE MANAGEMENT OF MPNS WERE BASED ON THE RESULTS OF LARGE CLINICAL TRIALS. FURTHERMORE, RECENT ADVANCEMENTS IN UNDERSTANDING THE PATHOGENESIS OF MPNS ARE ANTICIPATED TO PROMOTE THE DEVELOPMENT OF MPN-TARGETED THERAPIES SUCH AS JAK2 INHIBITORS. CLINICAL TRIALS FOR PATIENTS WITH PMF AND PV HAVE CONFIRMED THE EFFICACIES OF JAK2 INHIBITORS. 2016 4 1043 41 CLINICAL CHARACTERISTICS AND WHOLE EXOME/TRANSCRIPTOME SEQUENCING OF COEXISTING CHRONIC MYELOID LEUKEMIA AND MYELOFIBROSIS. MYELOPROLIFERATIVE NEOPLASMS (MPNS) ARE CLONAL HEMATOPOIETIC STEM CELL (HSC) DISORDERS THAT CAN BE CLASSIFIED ON THE BASIS OF GENETIC, CLINICAL, PHENOTYPIC FEATURES. GENETIC LESIONS SUCH AS JAK2 MUTATIONS AND BCR-ABL TRANSLOCATION ARE OFTEN MUTUALLY EXCLUSIVE IN MPN PATIENTS AND LEAD TO ESSENTIAL THROMBOCYTHEMIA, POLYCYTHEMIA VERA, OR MYELOFIBROSIS OR CHRONIC MYELOID LEUKEMIA, RESPECTIVELY. NEVERTHELESS, COEXISTENCE OF THESE GENETIC ABERRATIONS IN THE SAME PATIENT HAS BEEN REPORTED. WHETHER THESE ABERRATIONS OCCUR IN THE SAME STEM CELL OR A DIFFERENT CELL IS UNCLEAR, BUT AN UNSTABLE GENOME IN THE HSCS SEEMS TO BE THE COMMON ANTECEDENT. IN AN EFFORT TO CHARACTERIZE THE UNDERLYING GENETIC EVENTS THAT MIGHT CONTRIBUTE TO THE APPEARANCE OF MORE THAN ONE MPN IN A PATIENT, WE STUDIED NEOPLASTIC CELLS FROM PATIENTS WITH DUAL MPNS BY NEXT-GENERATION SEQUENCING. WE OBSERVED THAT MOST PATIENTS WITH TWO MPNS HARBORED MUTATIONS IN GENES KNOWN TO CONTRIBUTE TO CLONAL HEMATOPOIESIS THROUGH ALTERED EPIGENETIC REGULATION SUCH AS TET2, ASXL1/2, SRSF2, AND IDH2 AT VARYING FREQUENCIES (1%-47%). IN ADDITION, WE FOUND THAT SOME PATIENTS ALSO HARBORED ONCOGENIC MUTATIONS IN N/KRAS, TP53, BRAF, EZH2, AND GNAS AT LOW FREQUENCIES, WHICH PROBABLY REPRESENT CLONAL EVOLUTION. THESE FINDINGS SUPPORT THE HYPOTHESIS THAT HEMATOPOIETIC CELLS FROM MPN PATIENTS HARBOR MULTIPLE GENETIC ABERRATIONS, SOME OF WHICH CAN CONTRIBUTE TO CLONAL DOMINANCE. ACQUIRING MUTATIONS IN JAK2/CALR/MPL OR THE BCR-ABL TRANSLOCATION PROBABLY DRIVE THE ONCOGENIC PHENOTYPE TOWARDS A SPECIFIC MPN. FURTHER, WE PROPOSE THAT THE ACQUISITION OF BCR-ABL IN THESE PATIENTS IS FREQUENTLY A SECONDARY EVENT RESULTING FROM AN UNSTABLE GENOME. 2017 5 2548 28 EPIGENETICS IN MYELOPROLIFERATIVE NEOPLASMS. THE MYELOPROLIFERATIVE NEOPLASMS (MPNS) ARE A GROUP OF ACQUIRED CLONAL DISORDERS WHERE MUTATIONS DRIVE PROLIFERATIVE DISEASE RESULTING IN INCREASED BLOOD COUNTS AND IN SOME CASES END-STAGE MYELOFIBROSIS. EPIGENETIC CHANGES ARE THE REVERSIBLE MODIFICATIONS TO DNA- AND RNA-ASSOCIATED PROTEINS THAT IMPACT GENE ACTIVITY WITHOUT CHANGING THE DNA SEQUENCE. THIS REVIEW SUMMARIZES MECHANISMS OF EPIGENETIC CHANGES AND THE NUCLEOSOME. THE DRIVERS AND EPIGENETIC REGULATORS IN MPNS ARE OUTLINED. IN MPNS, DISTINCT PATTERNS OF EPIGENETIC DYSREGULATION HAVE BEEN SEEN IN CHRONIC AND IN ADVANCED PHASES. METHYLATION AGE AND HISTONE MODIFICATION ARE ALTERED IN MPNS AND BY FURTHER TREATMENT. THE ALTERATIONS FOUND IN METHYLATION AGE IN MPNS AND WITH TREATMENT ARE DISCUSSED, AND THE CHANGES IN HISTONE MODIFICATION WITH JANUS KINASE (JAK) INHIBITION ARE EVALUATED. CURRENTLY AVAILABLE THERAPEUTIC AREAS WHERE THE EPIGENOME CAN BE ALTERED ARE OUTLINED. THUS, WE REVIEW THE CURRENT KNOWLEDGE AND UNDERSTANDING OF EPIGENETICS IN MPN AND CONSIDER FURTHER MANAGEMENT OPTIONS. UNDERSTANDING THE EPIGENOME AND ITS ALTERATION IN MPNS AND EPIGENETIC CHANGES ASSOCIATED WITH THE PROGRESSION OF DISEASE WILL LEAD TO ADVANCES IN THERAPEUTIC OPTIONS. 2023 6 2956 41 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 7 5782 29 SPLICING ANOMALIES IN MYELOPROLIFERATIVE NEOPLASMS: PAVING THE WAY FOR NEW THERAPEUTIC VENUES. SINCE THE DISCOVERY OF SPLICEOSOME MUTATIONS IN MYELOID MALIGNANCIES, ABNORMAL PRE-MRNA SPLICING, WHICH HAS BEEN WELL STUDIED IN VARIOUS CANCERS, HAS ATTRACTED NOVEL INTEREST IN HEMATOLOGY. HOWEVER, DESPITE THE COMMON OCCURRENCE OF SPLICEOSOME MUTATIONS IN MYELO-PROLIFERATIVE NEOPLASMS (MPN), NOT MUCH IS KNOWN REGARDING THE CHARACTERIZATION AND MECHANISMS OF SPLICING ANOMALIES IN MPN. IN THIS ARTICLE, WE REVIEW THE CURRENT SCIENTIFIC LITERATURE REGARDING "SPLICING AND MYELOPROLIFERATIVE NEOPLASMS". WE FIRST ANALYSE THE CLINICAL SERIES REPORTING SPLICEOSOME MUTATIONS IN MPN AND THEIR CLINICAL CORRELATES. WE THEN PRESENT THE CURRENT KNOWLEDGE ABOUT MOLECULAR MECHANISMS BY WHICH THESE MUTATIONS PARTICIPATE IN THE PATHOGENESIS OF MPN OR OTHER MYELOID MALIGNANCIES. BESIDE SPLICEOSOME MUTATIONS, SPLICING ANOMALIES HAVE BEEN DESCRIBED IN MYELOPROLIFERATIVE NEOPLASMS, AS WELL AS IN ACUTE MYELOID LEUKEMIAS, A DREADFUL COMPLICATION OF THESE CHRONIC DISEASES. BASED ON SPLICING ANOMALIES REPORTED IN CHRONIC MYELOGENOUS LEUKEMIA AS WELL AS IN ACUTE LEUKEMIA, AND THE MECHANISMS PRESIDING SPLICING DEREGULATION, WE PROPOSE THAT ABNORMAL SPLICING PLAYS A MAJOR ROLE IN THE EVOLUTION OF MYELOPROLIFERATIVE NEOPLASMS AND MAY BE THE TARGET OF SPECIFIC THERAPEUTIC STRATEGIES. 2020 8 4322 33 MICRORNAS IN MYELOPROLIFERATIVE NEOPLASMS. THE CHRONIC MYELOPROLIFERATIVE NEOPLASMS (MPN), INCLUDING POLYCYTHAEMIA VERA (PV), ESSENTIAL THROMBOCYTHAEMIA (ET) AND PRIMARY MYELOFIBROSIS (PMF), ARE CLONAL STEM CELL DISORDERS CHARACTERIZED BY DYSREGULATED HAEMATOPOIETIC STEM CELL EXPANSION AND PRODUCTION OF RED CELLS, WHITE CELLS AND PLATELETS ALONE OR IN COMBINATION. AN ACQUIRED MUTATION JAK2(V617F) CAN BE FOUND IN ALL THREE DISORDERS AND SHOWS MANY OF THE PHENOTYPIC ABNORMALITIES OF THE DISEASES IN MURINE MODELS. THE DISEASE PHENOTYPE IS ALSO INFLUENCED BY OTHER UNKNOWN GENETIC OR EPIGENETIC FACTORS. MICRORNAS (MIRNA) ARE 18-24 NUCLEOTIDE SINGLE-STRANDED NON-PROTEIN-CODING RNAS THAT FUNCTION PRIMARILY AS GENE REPRESSORS BY BINDING TO THEIR TARGET MESSENGER RNAS. THERE IS GROWING EVIDENCE THAT MIRNAS REGULATE HAEMATOPOIESIS IN BOTH HAEMATOPOIETIC STEM CELLS AND COMMITTED PROGENITOR CELLS. HERE, WE REVIEW THE FIELD OF MIRNA BIOLOGY AND ITS REGULATORY ROLES IN NORMAL HAEMATOPOIESIS WITH AN EMPHASIS ON MIRNA DEREGULATIONS IN MPNS. CONTINUED RESEARCH INTO HOW MIRNAS IMPACT JAK2(V617F) CLONAL EXPANSION, DIFFERENTIAL HAEMATOPOIESIS AMONG DIFFERENT MPNS, DISEASE PROGRESSION AND LEUKAEMIA TRANSFORMATION WILL LEAD TO A BETTER UNDERSTANDING OF THE DEVELOPMENT OF THESE DISORDERS, THEIR CLINICAL MANIFESTATIONS, AND THEIR TREATMENT. 2013 9 924 37 CHRONIC INFLAMMATION AS A PROMOTOR OF MUTAGENESIS IN ESSENTIAL THROMBOCYTHEMIA, POLYCYTHEMIA VERA AND MYELOFIBROSIS. A HUMAN INFLAMMATION MODEL FOR CANCER DEVELOPMENT? THE PHILADELPHIA-NEGATIVE CHRONIC MYELOPROLIFERATIVE NEOPLASMS (MPNS) ARE ACQUIRED STEM CELL NEOPLASMS, IN WHICH A STEM CELL LESION INDUCES AN AUTONOMOUS PROLIFERATIVE ADVANTAGE. IN ADDITION TO THE JAK2V617 MUTATION SEVERAL OTHER MUTATIONS HAVE BEEN DESCRIBED. RECENTLY CHRONIC INFLAMMATION HAS BEEN PROPOSED AS A TRIGGER AND DRIVER OF CLONAL EVOLUTION IN MPNS. HEREIN, IT IS HYPOTHESIZED THAT SUSTAINED INFLAMMATION MAY ELICIT THE STEM CELL INSULT BY INDUCING A STATE OF CHRONIC OXIDATIVE STRESS WITH ELEVATED LEVELS OF REACTIVE OXYGEN SPECIES (ROS) IN THE BONE MARROW, THEREBY CREATING A HIGH-RISK MICROENVIRONMENT FOR INDUCTION OF MUTATIONS DUE TO THE PERSISTENT INFLAMMATION-INDUCED OXIDATIVE DAMAGE TO DNA IN HEMATOPOIETIC CELLS. ALTERATIONS IN THE EPIGENOME INDUCED BY THE CHRONIC INFLAMMATORY DRIVE MAY LIKELY ELICIT A "EPIGENETIC SWITCH" PROMOTING PERSISTENT INFLAMMATION. THE PERSPECTIVES OF CHRONIC INFLAMMATION AS THE DRIVER OF MUTAGENESIS IN MPNS ARE DISCUSSED, INCLUDING EARLY INTERVENTION WITH INTERFERON-ALPHA2 AND POTENT ANTI-INFLAMMATORY AGENTS (E.G. JAK1-2 INHIBITORS, HISTONE DEACETYLASE INHIBITORS, DNA-HYPOMETHYLATORS AND STATINS) TO DISRUPT THE SELF-PERPETUATING CHRONIC INFLAMMATION STATE AND ACCORDINGLY ELIMINATING A POTENTIAL TRIGGER OF CLONAL EVOLUTION AND DISEASE PROGRESSION WITH MYELOFIBROTIC AND LEUKEMIC TRANSFORMATION. 2013 10 2981 27 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 11 359 34 ALWAYS STRESSED BUT NEVER EXHAUSTED: HOW STEM CELLS IN MYELOID NEOPLASMS AVOID EXTINCTION IN INFLAMMATORY CONDITIONS. CHRONIC OR RECURRENT EPISODES OF ACUTE INFLAMMATION CAUSE ATTRITION OF NORMAL HEMATOPOIETIC STEM CELLS (HSCS) THAT CAN LEAD TO HEMATOPOIETIC FAILURE BUT THEY DRIVE PROGRESSION IN MYELOID MALIGNANCIES AND THEIR PRECURSOR CLONAL HEMATOPOIESIS. MECHANISTIC PARALLELS EXIST BETWEEN HEMATOPOIESIS IN CHRONIC INFLAMMATION AND THE CONTINUOUSLY INCREASED PROLIFERATION OF MYELOID MALIGNANCIES, PARTICULARLY MYELOPROLIFERATIVE NEOPLASMS (MPNS). THE ABILITY TO ENTER DORMANCY, A STATE OF DEEP QUIESCENCE CHARACTERIZED BY LOW OXIDATIVE PHOSPHORYLATION, LOW GLYCOLYSIS, REDUCED PROTEIN SYNTHESIS, AND INCREASED AUTOPHAGY IS CENTRAL TO THE PRESERVATION OF LONG-TERM HSCS AND LIKELY MPN SCS. THE METABOLIC FEATURES OF DORMANCY RESEMBLE THOSE OF DIAPAUSE, A STATE OF ARRESTED EMBRYONIC DEVELOPMENT TRIGGERED BY ADVERSE ENVIRONMENTAL CONDITIONS. TO OUTCOMPETE THEIR NORMAL COUNTERPARTS IN THE INFLAMMATORY MPN ENVIRONMENT, MPN SCS CO-OPT MECHANISMS USED BY HSCS TO AVOID EXHAUSTION, INCLUDING SIGNAL ATTENUATION BY NEGATIVE REGULATORS, INSULATION FROM ACTIVATING CYTOKINE SIGNALS, ANTI-INFLAMMATORY SIGNALING, AND EPIGENETIC REPROGRAMMING. WE PROPOSE THAT NEW THERAPEUTIC STRATEGIES MAY BE DERIVED FROM CONCEPTUALIZING MYELOID MALIGNANCIES AS AN ECOSYSTEM OUT OF BALANCE, IN WHICH RESIDUAL NORMAL AND MALIGNANT HEMATOPOIETIC CELLS INTERACT IN MULTIPLE WAYS, ONLY FEW OF WHICH HAVE BEEN CHARACTERIZED IN DETAIL. DISRUPTING MPN SC INSULATION TO OVERCOME DORMANCY, INTERFERING WITH ABERRANT CYTOKINE CIRCUITS THAT FAVOR MPN CELLS, AND DIRECTLY BOOSTING RESIDUAL NORMAL HSCS ARE POTENTIAL STRATEGIES TO TIP THE BALANCE IN FAVOR OF NORMAL HEMATOPOIESIS. ALTHOUGH ERADICATING THE MALIGNANT CELL CLONES REMAINS THE GOAL OF THERAPY, REBALANCING THE ECOSYSTEM MAY BE A MORE ATTAINABLE OBJECTIVE IN THE SHORT TERM. 2023 12 4959 27 PATHOGENESIS OF MYELOPROLIFERATIVE DISORDERS. MYELOPROLIFERATIVE NEOPLASMS (MPNS) ARE A SET OF CHRONIC HEMATOPOIETIC NEOPLASMS WITH OVERLAPPING CLINICAL AND MOLECULAR FEATURES. RECENT YEARS HAVE WITNESSED CONSIDERABLE ADVANCES IN OUR UNDERSTANDING OF THEIR PATHOGENETIC BASIS. DUE TO THEIR PROTRACTED CLINICAL COURSE, THE EVOLUTION TO ADVANCED HEMATOLOGICAL MALIGNANCIES, AND THE ACCESSIBILITY OF NEOPLASTIC TISSUE, THE STUDY OF MPNS HAS PROVIDED A WINDOW INTO THE EARLIEST STAGES OF TUMORIGENESIS. WITH THE DISCOVERY OF MUTATIONS IN CALR, THE MAJORITY OF MPN PATIENTS NOW BEAR AN IDENTIFIABLE MARKER OF CLONAL DISEASE; HOWEVER, THE MECHANISM BY WHICH MUTATED CALR PERTURBS MEGAKARYOPOIESIS IS CURRENTLY UNRESOLVED. WE ARE BEGINNING TO UNDERSTAND BETTER THE ROLE OF JAK2(V617F) HOMOZYGOSITY, THE FUNCTION OF COMUTATIONS IN EPIGENETIC REGULATORS AND SPLICEOSOME COMPONENTS, AND HOW THESE MUTATIONS COOPERATE WITH JAK2(V617F) TO MODULATE MPN PHENOTYPE. 2016 13 3565 29 IMPACT OF GENETIC POLYMORPHISMS AND BIOMARKERS ON THE EFFECTIVENESS AND TOXICITY OF TREATMENT OF CHRONIC MYELOID LEUKEMIA AND ACUTE MYELOID LEUKEMIA. MOST MALIGNANT HEMATOLOGICAL DISEASES ARE GENERALLY A CONSEQUENCE OF ACQUIRED MUTATIONS OR REARRANGEMENTS IN CELL REPLICATION PROCESSES. ACUTE MYELOID LEUKEMIA (AML) IS A CLINICALLY AND MOLECULARLY HETEROGENEOUS DISEASE THAT RESULTS FROM ACQUIRED GENETIC AND EPIGENETIC ALTERATIONS IN HEMATOPOIETIC PROGENITOR CELLS. DESPITE THE ADVANCES MADE IN UNDERSTANDING THE PATHOGENESIS OF THIS DISEASE, THE OVERALL SURVIVAL OF PATIENTS REMAINS VERY LOW DUE TO THE HIGH RELAPSE RATE. PHARMACOGENETICS AND MASSIVE SEQUENCING STUDIES HAVE ALLOWED THE IDENTIFICATION OF NEW RECURRENT MUTATIONS WITH SIGNIFICANT PROGNOSTIC IMPACT IN AML; FURTHERMORE, IT SEEMS LIKELY THAT WHOLE GENOME SEQUENCING WILL SOON BECOME A STANDARD DIAGNOSTIC TEST, WHICH WILL ALLOW THE MOLECULAR DIAGNOSIS OF PATIENTS. THEREFORE, IT IS NECESSARY TO DEVELOP MOLECULAR TARGETS THAT OPEN NEW THERAPEUTIC PERSPECTIVES AND ALLOW INDIVIDUALIZED TREATMENT OF PATIENTS WITH THIS AGGRESSIVE DISEASE. CHRONIC MYELOID LEUKEMIA (CML) IS THE FIRST NEOPLASTIC DISEASE FOR WHICH A CHARACTERISTIC GENETIC ALTERATION WAS DESCRIBED. IT HAS, BY DEFINITION, A GENETIC MARKER, THE BCR::ABL1 REARRANGEMENT, AS A CONSEQUENCE OF THE T9;22(Q34;Q11) TRANSLOCATION. ITS STUDY IS ESSENTIAL FOR THE DIAGNOSIS OF THIS ENTITY AND ALSO FOR MONITORING THE RESPONSE TO TREATMENT. DRUGS KNOWN AS TYROSINE KINASE INHIBITORS (TKIS) THAT TARGET THE BCR::ABL1 PROTEIN (ORAL TARGETED THERAPY) ARE THE CONVENTIONAL TREATMENT OF CML, REPRESENTING A CHANGE OF PARADIGM IN THE MANAGEMENT OF ONCOHEMATOLOGICAL PATIENTS. 2022 14 4680 36 NEW MUTATIONS AND PATHOGENESIS OF MYELOPROLIFERATIVE NEOPLASMS. MYELOPROLIFERATIVE NEOPLASMS (MPNS) ARE CLONAL DISORDERS CHARACTERIZED BY EXCESSIVE PRODUCTION OF MATURE BLOOD CELLS. IN THE MAJORITY OF CLASSIC MPN--POLYCYTHEMIA VERA, ESSENTIAL THROMBOCYTHEMIA, AND PRIMITIVE MYELOFIBROSIS--DRIVER ONCOGENIC MUTATIONS AFFECTING JANUS KINASE 2 (JAK2) OR MPL LEAD TO CONSTITUTIVE ACTIVATION OF CYTOKINE-REGULATED INTRACELLULAR SIGNALING PATHWAYS. LNK, C-CBL, OR SOCSS (ALL NEGATIVE REGULATORS OF SIGNALING PATHWAYS), ALTHOUGH INFREQUENTLY TARGETED, MAY EITHER DRIVE THE DISEASE OR SYNERGIZE WITH JAK2 AND MPL MUTATIONS. IZF1 DELETIONS OR TP53 MUTATIONS ARE MAINLY FOUND AT TRANSFORMATION PHASES AND ARE PRESENT AT GREATER FREQUENCY THAN IN DE NOVO ACUTE MYELOID LEUKEMIAS. LOSS-OF-FUNCTION MUTATIONS IN 3 GENES INVOLVED IN EPIGENETIC REGULATION, TET2, ASXL1, AND EZH2, MAY BE EARLY EVENTS PRECEDING JAK2V617F BUT MAY ALSO OCCUR LATE DURING DISEASE PROGRESSION. THEY ARE MORE FREQUENTLY OBSERVED IN PMF THAN PV AND ET AND ARE ALSO PRESENT IN OTHER TYPES OF MALIGNANT MYELOID DISEASES. A LIKELY HYPOTHESIS IS THAT THEY FACILITATE CLONAL SELECTION, ALLOWING THE DOMINANCE OF THE JAK2V617F SUBCLONE DURING THE CHRONIC PHASE AND, TOGETHER WITH COOPERATING MUTATIONS, PROMOTE BLAST CRISIS. THEIR PRECISE ROLES IN HEMATOPOIESIS AND IN THE PATHOGENESIS OF MPN, AS WELL AS THEIR PROGNOSTIC IMPACT AND POTENTIAL AS A THERAPEUTIC TARGET, ARE CURRENTLY UNDER INVESTIGATION. 2011 15 5257 43 PROGRESSION OF MYELOPROLIFERATIVE NEOPLASMS (MPN): DIAGNOSTIC AND THERAPEUTIC PERSPECTIVES. CLASSICAL BCR-ABL-NEGATIVE MYELOPROLIFERATIVE NEOPLASMS (MPN) ARE A HETEROGENEOUS GROUP OF HEMATOLOGIC MALIGNANCIES, INCLUDING ESSENTIAL THROMBOCYTHEMIA (ET), POLYCYTHEMIA VERA (PV), AND PRIMARY MYELOFIBROSIS (PMF), AS WELL AS POST-PV-MF AND POST-ET-MF. PROGRESSION TO MORE SYMPTOMATIC DISEASE, SUCH AS OVERT MF OR ACUTE LEUKEMIA, REPRESENTS ONE OF THE MAJOR CAUSES OF MORBIDITY AND MORTALITY. THERE ARE CLINICALLY EVIDENT BUT ALSO SUBCLINICAL TYPES OF MPN PROGRESSION. CLINICALLY EVIDENT PROGRESSION INCLUDES EVOLUTION FROM ET TO PV, ET TO POST-ET-MF, PV TO POST-PV-MF, OR PRE-PMF TO OVERT PMF, AND TRANSFORMATION OF ANY OF THESE SUBTYPES TO MYELODYSPLASTIC NEOPLASMS OR ACUTE LEUKEMIA. THROMBOSIS, MAJOR HEMORRHAGE, SEVERE INFECTIONS, OR INCREASING SYMPTOM BURDEN (E.G., PRURITUS, NIGHT SWEATS) MAY HERALD PROGRESSION. SUBCLINICAL TYPES OF PROGRESSION MAY INCLUDE INCREASES IN THE EXTENT OF BONE MARROW FIBROSIS, INCREASES OF DRIVER GENE MUTATIONAL ALLELE BURDEN, AND CLONAL EVOLUTION. THE UNDERLYING CAUSES OF MPN PROGRESSION ARE DIVERSE AND CAN BE ATTRIBUTED TO GENETIC ALTERATIONS AND CHRONIC INFLAMMATION. PARTICULARLY, BYSTANDER MUTATIONS IN GENES ENCODING EPIGENETIC REGULATORS OR SPLICING FACTORS WERE ASSOCIATED WITH PROGRESSION. FINALLY, COMORBIDITIES SUCH AS SYSTEMIC INFLAMMATION, CARDIOVASCULAR DISEASES, AND ORGAN FIBROSIS MAY AUGMENT THE RISK OF PROGRESSION. THE AIM OF THIS REVIEW WAS TO DISCUSS TYPES AND MECHANISMS OF MPN PROGRESSION AND HOW THEIR KNOWLEDGE MIGHT IMPROVE RISK STRATIFICATION AND THERAPEUTIC INTERVENTION. IN VIEW OF THESE ASPECTS, WE DISCUSS THE POTENTIAL BENEFITS OF EARLY DIAGNOSIS USING MOLECULAR AND FUNCTIONAL IMAGING AND EXPLOITABLE THERAPEUTIC STRATEGIES THAT MAY PREVENT PROGRESSION, BUT ALSO HIGHLIGHT CURRENT CHALLENGES AND METHODOLOGICAL PITFALLS. 2021 16 3575 42 IMPACT OF MOLECULAR PROFILING ON THE MANAGEMENT OF PATIENTS WITH MYELOFIBROSIS. MYELOFIBROSIS (MF) IS A CHRONIC MYELOPROLIFERATIVE NEOPLASM (MPN) CHARACTERIZED BY A HIGHLY HETEROGENEOUS CLINICAL COURSE, WHICH CAN BE COMPLICATED BY SEVERE CONSTITUTIONAL SYMPTOMS, MASSIVE SPLENOMEGALY, PROGRESSIVE BONE MARROW FAILURE, CARDIOVASCULAR EVENTS, AND DEVELOPMENT OF ACUTE LEUKEMIA. CONSTITUTIVE SIGNALING THROUGH THE JAK-STAT PATHWAY PLAYS A FUNDAMENTAL ROLE IN ITS PATHOGENESIS, GENERALLY DUE TO ACTIVATING MUTATIONS OF JAK2, CALR AND MPL GENES (I.E., THE MPN DRIVER MUTATIONS), PRESENT IN MOST MF PATIENTS. NEXT GENERATION SEQUENCING (NGS) PANEL TESTING HAS SHOWN THAT ADDITIONAL SOMATIC MUTATIONS CAN ALREADY BE DETECTED AT THE TIME OF DIAGNOSIS IN MORE THAN HALF OF PATIENTS, AND THAT THEY ACCUMULATE ALONG THE DISEASE COURSE. THESE MUTATIONS, MOSTLY AFFECTING EPIGENETIC MODIFIERS OR SPLICEOSOME COMPONENTS, MAY COOPERATE WITH MPN DRIVERS TO FAVOR CLONAL DOMINANCE OR INFLUENCE THE CLINICAL PHENOTYPE, AND SOME, SUCH AS HIGH MOLECULAR RISK MUTATIONS, CORRELATE WITH A MORE AGGRESSIVE CLINICAL COURSE WITH POOR TREATMENT RESPONSE. THE CURRENT MAIN ROLE OF MOLECULAR PROFILING IN CLINICAL PRACTICE IS PROGNOSTICATION, PRINCIPALLY FOR SELECTING HIGH-RISK PATIENTS WHO MAY BE CANDIDATES FOR TRANSPLANTATION, THE ONLY CURATIVE TREATMENT FOR MF TO DATE. TO THIS END, CONTEMPORARY PROGNOSTIC MODELS INCORPORATING MOLECULAR DATA ARE USEFUL TOOLS TO DISCRIMINATE DIFFERENT RISK CATEGORIES. ASIDE FROM CERTAIN CLINICAL SITUATIONS, DECISIONS REGARDING MEDICAL TREATMENT ARE NOT BASED ON PATIENT MOLECULAR PROFILING, YET THIS APPROACH MAY BECOME MORE RELEVANT IN NOVEL TREATMENT STRATEGIES, SUCH AS THE USE OF VACCINES AGAINST THE MUTANT FORMS OF JAK2 OR CALR, OR DRUGS DIRECTED AGAINST ACTIONABLE MOLECULAR TARGETS. 2022 17 358 32 ALTERNATIVE SPLICING IN CHRONIC MYELOID LEUKEMIA (CML): A NOVEL THERAPEUTIC TARGET? ALTHOUGH THE IMATINIB BASED THERAPY OF CHRONIC MYELOID LEUKEMIA (CML) REPRESENTS A TRIUMPH OF MEDICINE, NOT ALL PATIENTS WITH CML BENEFIT FROM THIS DRUG DUE TO THE DEVELOPMENT OF RESISTANCE AND INTOLERANCE. THE INTERRUPTION OF IMATINIB TREATMENT IS OFTEN FOLLOWED BY CLINICAL RELAPSE, SUGGESTING A FAILURE IN THE KILLING OF RESIDUAL LEUKAEMIC STEM CELLS. THERE IS NEED TO IDENTIFY ALTERNATIVE SELECTIVE MOLECULAR TARGETS FOR THIS DISEASE AND DEVELOP MORE EFFECTIVE THERAPEUTIC APPROACHES. ALTERNATIVE PRE-MRNA SPLICING (AS) IS AN EPIGENETIC PROCESS THAT GREATLY DIVERSIFIES THE REPERTOIRE OF THE TRANSCRIPTOME. AS ORCHESTRATES INTERACTIONS BETWEEN VARIOUS TYPES OF PROTEINS AND BETWEEN PROTEINS AND NUCLEIC ACIDS. CHANGES CAUSED BY INDIVIDUAL SPLICING EVENTS IN THE CELLS ARE SMALL, HOWEVER, "SPLICING PROGRAMS" TYPICALLY REACT TO THESE INDIVIDUAL CHANGES WITH CONSIDERABLE EFFECTS IN CELL PROLIFERATION, CELL SURVIVAL, AND APOPTOSIS. CURRENT EVIDENCE SUGGESTS A PIVOTAL ROLE OF AS IN LEUKEMIAS, PARTICULARLY IN MYELODISPLASTIC SYNDROME (MDS) AND CHRONIC LYMPHOCYTE LEUKEMIA (CLL). FROM THESE STUDIES AND STUDIES IN OTHER MALIGNANCES, IT IS CLEAR THAT SPLICING ABNORMALITIES PLAY A SIGNIFICANT ROLE IN MALIGNANT TRANSFORMATION. EVALUATION OF AS EVENTS IN CML CAN BE USED TO IDENTIFY NOVEL DISEASE MARKERS AND DRUGSENSITIVE TARGETS TO OVERCOME THE LIMITS OF THE SMALL MOLECULE INHIBITORS CURRENTLY USED FOR TREATING PATIENTS WITH CML. THE USE OF ABERRANT SPLICE VARIANTS AS DISEASE MARKERS HAS BEEN REPORTED, HOWEVER, LITTLE IS KNOWN ABOUT THE USE OF SPLICING ABNORMALITIES AS DRUG TARGETS IN CML. HEREIN WE DISCUSS POTENTIAL THERAPEUTIC APPROACHES THAT CAN BE USED TO TARGET SPLICING ABNORMALITIES IN CML. 2013 18 3747 36 INSIGHTS INTO THE MOLECULAR GENETICS OF MYELOPROLIFERATIVE NEOPLASMS. THE MOLECULAR BIOLOGY OF THE BCR-ABL1-NEGATIVE CHRONIC MYELOPROLIFERATIVE NEOPLASMS (MPNS) HAS WITNESSED UNPRECEDENTED ADVANCES SINCE THE DISCOVERY OF THE ACQUIRED JAK2 V617F MUTATION IN 2005. DESPITE THE HIGH PREVALENCE OF JAK2 V617F IN POLYCYTHEMIA VERA (PV), ESSENTIAL THROMBOCYTHEMIA (ET), AND PRIMARY MYELOFIBROSIS (PMF), AND THE COMMON FINDING OF DYSREGULATED JAK-STAT SIGNALING IN THESE DISORDERS, IT IS NOW APPRECIATED THAT MPN PATHOGENESIS CAN REFLECT THE ACQUISITION OF MULTIPLE GENETIC MUTATIONS THAT ALTER SEVERAL BIOLOGIC PATHWAYS, INCLUDING EPIGENETIC CONTROL OF GENE EXPRESSION. ALTHOUGH CERTAIN GENE MUTATIONS ARE IDENTIFIED AT HIGHER FREQUENCIES WITH DISEASE EVOLUTION TO THE BLAST PHASE, MPN INITIATION AND PROGRESSION ARE NOT EXPLAINED BY A SINGLE, TEMPORAL PATTERN OF CLONAL CHANGES. A COMPLEX INTERPLAY BETWEEN ACQUIRED MOLECULAR ABNORMALITIES AND HOST GENETIC BACKGROUND, IN ADDITION TO THE TYPE AND ALLELIC BURDEN OF MUTATIONS, CONTRIBUTES TO THE PHENOTYPIC HETEROGENEITY OF MPNS. AT THE POPULATION LEVEL, AN INHERITED PREDISPOSITION TO DEVELOPING MPNS IS LINKED TO A RELATIVELY COMMON JAK2-ASSOCIATED HAPLOTYPE (REFERRED TO AS '46/1'), BUT IT EXHIBITS A RELATIVELY LOW PENETRANCE. THIS REVIEW DETAILS THE CURRENT STATE OF KNOWLEDGE OF THE MOLECULAR GENETICS OF THE CLASSIC MPNS PV, ET, AND PMF AND DISCUSSES THE CLINICAL IMPLICATIONS OF THESE FINDINGS. 2012 19 2237 36 EPIGENETIC MODIFIERS IN MYELOID MALIGNANCIES: THE ROLE OF HISTONE DEACETYLASE INHIBITORS. MYELOID HEMATOLOGICAL MALIGNANCIES ARE CLONAL BONE MARROW NEOPLASMS, COMPRISING OF ACUTE MYELOID LEUKEMIA (AML), THE MYELODYSPLASTIC SYNDROMES (MDS), CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML), THE MYELOPROLIFERATIVE NEOPLASMS (MPN) AND SYSTEMIC MASTOCYTOSIS (SM). THE FIELD OF EPIGENETIC REGULATION OF NORMAL AND MALIGNANT HEMATOPOIESIS IS RAPIDLY GROWING. IN RECENT YEARS, HETEROZYGOUS SOMATIC MUTATIONS IN GENES ENCODING EPIGENETIC REGULATORS HAVE BEEN FOUND IN ALL SUBTYPES OF MYELOID MALIGNANCIES, SUPPORTING THE RATIONALE FOR TREATMENT WITH EPIGENETIC MODIFIERS. HISTONE DEACETYLASE INHIBITORS (HDACI) ARE EPIGENETIC MODIFIERS THAT, IN VITRO, HAVE BEEN SHOWN TO INDUCE GROWTH ARREST, APOPTOTIC OR AUTOPHAGIC CELL DEATH, AND TERMINAL DIFFERENTIATION OF MYELOID TUMOR CELLS. THESE EFFECTS WERE OBSERVED BOTH AT THE BULK TUMOR LEVEL AND IN THE MOST IMMATURE CD34(+)38(-) CELL COMPARTMENTS CONTAINING THE LEUKEMIC STEM CELLS. THUS, THERE IS A STRONG RATIONALE SUPPORTING HDACI THERAPY IN MYELOID MALIGNANCIES. HOWEVER, DESPITE INITIAL PROMISING RESULTS IN PHASE I TRIALS, HDACI IN MONOTHERAPY AS WELL AS IN COMBINATION WITH OTHER DRUGS, HAVE FAILED TO IMPROVE RESPONSES OR SURVIVAL. THIS REVIEW PROVIDES AN OVERVIEW OF THE RATIONALE FOR HDACI IN MYELOID MALIGNANCIES, CLINICAL RESULTS AND SPECULATIONS ON WHY CLINICAL TRIALS HAVE THUS FAR NOT MET THE EXPECTATIONS, AND HOW THIS MAY BE IMPROVED IN THE FUTURE. 2018 20 384 34 AN EVOLUTIONARY PERSPECTIVE ON CHRONIC MYELOMONOCYTIC LEUKEMIA. CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) SHARES WITH OTHER MYELOID DISEASES A NUMBER OF SOMATIC GENE MUTATIONS. THESE MUTATIONS CAN NOW BE INTEGRATED WITHIN THE FRAMEWORK OF EVOLUTION THEORY TO ADDRESS THE MECHANISMS OF THE DISEASE. SEVERAL EVIDENCES INDICATE THAT THE DISEASE EMERGES IN ADULT HEMATOPOIETIC STEM CELLS (HSC) THROUGH THE AGE-DEPENDENT ACCUMULATION OF DNA DAMAGE, LEADING STOCHASTICALLY TO A DRIVER MUTATION THAT CONFERS A COMPETITIVE ADVANTAGE TO THE CELL. A MUTATION IN TET2 GENE COULD BE ONE OF THESE DRIVER MUTATIONS PROVOKING THE EMERGENCE OF CLONALITY. AFTER A LONG LATENCY, SECONDARY LESIONS, SUCH AS MUTATIONS IN THE SRSF2 GENE, CONTRIBUTE TO PROGRESSION TO FULL-BLOWN MALIGNANCY, WITH ABNORMAL DIFFERENTIATION. ADDITIONAL MUTATIONS ACCUMULATE AND BRANCHING ARISING MOSTLY THROUGH MITOTIC RECOMBINATION GENERATES CLONAL HETEROGENEITY. MODIFICATIONS IN THE MICROENVIRONMENT PROBABLY AFFECT THIS CLONAL DYNAMICS, WHEREAS EPIGENETIC ALTERATIONS, SUCH AS HYPERMETHYLATION OF THE TIF1GAMMA GENE PROMOTER, MAY GENERATE PHENOTYPIC DIVERSIFICATION OF OTHERWISE CLONAL POPULATIONS. THE PRESERVED ALTHOUGH DEREGULATED MYELOID DIFFERENTIATION THAT CHARACTERIZES CMML, WITH GRANULOMONOCYTE EXPANSION AND VARIOUS CYTOPENIAS, MAY DEPEND ON EARLY CLONAL DOMINANCE IN THE HEMATOPIETIC CELL HIERARCHY. PROGRESSION TO ACUTE MYELOID LEUKEMIA OBSERVED IN 25-30% OF THE PATIENTS MAY ARISE FROM THE MASSIVE EXPANSION OF A CLONE WITH NOVEL GENETIC LESIONS, PROVIDING A HIGH FITNESS TO PREVIOUSLY MINOR SUBCLONES WHEN IN CHRONIC PHASE OF THE DISEASE. THIS REVIEW DISCUSSES THE VARIOUS MODELS OF DISEASE EMERGENCE AND PROGRESSION AND HOW THIS RECENT KNOWLEDGE COULD DRIVE RATIONAL THERAPEUTIC STRATEGIES. 2013