1 4442 100 MOLECULAR GENETICS OF MDS/MPN OVERLAP SYNDROMES. THE MYELODYSPLASTIC/MYELOPROLIFERATIVE NEOPLASMS (MDS/MPN) ARE A HETEROGENOUS GROUP OF MYELOID MALIGNANCIES HALLMARKED BY CLINICOPATHOLOGIC FEATURES THAT OVERLAP WITH MYELODYSPLASTIC SYNDROMES AND MYELOPROLIFERATIVE NEOPLASMS. FORMALLY RECOGNIZED BY THE WORLD HEALTH ORGANIZATION, THIS GROUP INCLUDES THE ENTITIES CHRONIC MYELOMONOCYTIC LEUKEMIA, JUVENILE MYELOMONOCYTIC LEUKEMIA, ATYPICAL CHRONIC MYELOID LEUKEMIA, MDS/MPN WITH RING SIDEROBLASTS AND THROMBOCYTOSIS AND MDS/MPN, UNCLASSIFIABLE. ADVANCEMENTS IN NEXT GENERATION SEQUENCING HAVE BEGUN TO UNRAVEL THE MOLECULAR UNDERPINNINGS OF THESE DISEASES, IDENTIFYING AN ARRAY OF RECURRENTLY MUTATED GENES INVOLVED IN EPIGENETIC REGULATION, RNA SPLICING, TRANSCRIPTION, AND CELL SIGNALING. DESPITE MOLECULAR OVERLAP WITH OTHER MYELOID MALIGNANCIES, EACH ENTITY DISPLAYS A UNIQUE SPECTRUM OF SOMATIC MUTATIONS SUPPORTING THEIR UNIQUE PATHOBIOLOGY AND CLINICAL FEATURES. IMPORTANTLY, MOLECULAR PROFILING IS BECOMING AN INTEGRAL TOOL UTILIZED IN ROUTINE CLINICAL PRACTICE. THIS REVIEW SUMMARIZES OUR CURRENT UNDERSTANDING OF THE MOLECULAR PATHOGENESIS OF OVERLAP SYNDROMES AND DETAILS THE IMPACT OF SOMATIC MUTATIONS IN DIAGNOSTIC, PROGNOSTIC, AND THERAPEUTIC DECISION-MAKING. 2020 2 6588 25 TUMOR HETEROGENEITY IN LYMPHOMAS: A DIFFERENT BREED. THE FACTS THAT CANCER REPRESENTS TISSUES CONSISTING OF HETEROGENEOUS NEOPLASTIC, AS WELL AS REACTIVE, CELL POPULATIONS AND THAT CANCERS OF THE SAME HISTOTYPE MAY SHOW PROFOUND DIFFERENCES IN CLINICAL BEHAVIOR HAVE LONG BEEN RECOGNIZED. WITH THE ADVENT OF NEW TECHNOLOGIES AND THE DEMANDS OF PRECISION MEDICINE, THE INVESTIGATION OF TUMOR HETEROGENEITY HAS GAINED MUCH INTEREST. AN UNDERSTANDING OF INTERTUMORAL HETEROGENEITY IN PATIENTS WITH THE SAME DISEASE ENTITY IS NECESSARY TO OPTIMALLY GUIDE PERSONALIZED TREATMENT. IN ADDITION, INCREASING EVIDENCE INDICATES THAT DIFFERENT TUMOR AREAS OR PRIMARY TUMORS AND METASTASES IN AN INDIVIDUAL PATIENT CAN SHOW SIGNIFICANT INTRATUMORAL HETEROGENEITY ON DIFFERENT LEVELS. THIS PHENOMENON CAN BE DRIVEN BY GENOMIC INSTABILITY, EPIGENETIC EVENTS, THE TUMOR MICROENVIRONMENT, AND STOCHASTIC VARIATIONS IN CELLULAR FUNCTION AND ANTITUMORAL THERAPIES. THESE MECHANISMS MAY LEAD TO BRANCHED SUBCLONAL EVOLUTION FROM A COMMON PROGENITOR CLONE, RESULTING IN SPATIAL VARIATION BETWEEN DIFFERENT TUMOR SITES, DISEASE PROGRESSION, AND TREATMENT RESISTANCE. THIS REVIEW ADDRESSES TUMOR HETEROGENEITY IN LYMPHOMAS FROM A PATHOLOGIST'S VIEWPOINT. THE RELATIONSHIP BETWEEN MORPHOLOGIC, IMMUNOPHENOTYPIC, AND GENETIC HETEROGENEITY IS EXEMPLIFIED IN DIFFERENT LYMPHOMA ENTITIES AND REVIEWED IN THE CONTEXT OF HIGH-GRADE TRANSFORMATION AND TRANSDIFFERENTIATION. IN ADDITION, FACTORS DRIVING HETEROGENEITY, AS WELL AS CLINICAL AND THERAPEUTIC IMPLICATIONS OF LYMPHOMA HETEROGENEITY, WILL BE DISCUSSED. 2018 3 963 27 CHRONIC MYELOMONOCYTIC LEUKEMIA: INSIGHTS INTO BIOLOGY, PROGNOSTIC FACTORS, AND TREATMENT. PURPOSE OF REVIEW: CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) IS A CLONAL HEMATOLOGICAL MALIGNANCY CHARACTERIZED BY BOTH DYSPLASTIC AND PROLIFERATIVE FEATURES, WITH AN INHERENT RISK FOR LEUKEMIC TRANSFORMATION. WITH THE HELP OF THIS REVIEW, WE AIM TO SUMMARIZE KEY CONCEPTS WITH REGARDS TO CMML BIOLOGY, DIAGNOSIS, RISK STRATIFICATION, AND THERAPEUTICS. RECENT FINDINGS: BASED ON RECENT STUDIES, CMML IS HALLMARKED BY A RELATIVELY LOW GENETIC COMPLEXITY, WHICH CONTRASTS WITH A COMPELLING PHENOTYPICAL HETEROGENEITY, LARGELY DRIVEN BY EPIGENETIC MECHANISMS. RECENT ADVANCES IN THE CHARACTERIZATION OF CMML BIOLOGY HAS LED TO AN IMPROVEMENT IN RISK-STRATIFICATION, BY MEANS OF INCORPORATING PROGNOSTICALLY RELEVANT GENE MUTATIONS. THIS, HOWEVER, HAS NOT SIGNIFICANTLY IMPACTED AVAILABLE THERAPIES AND OUTCOMES CONTINUE TO REMAIN POOR. ADVANCES IN CMML BIOLOGY HAVE BETTER EXPLAINED THE PHENOTYPIC HETEROGENEITY, WHILE CONTINUING TO DEFINE THE GENETIC AND EPIGENETIC LANDSCAPE. IN SPITE OF RECENT ADVANCES, LIMITED EFFECTIVE THERAPIES EXIST AND DEVELOPING RATIONALLY DERIVED THERAPEUTIC APPROACHES IS MUCH NEEDED. 2019 4 4566 32 MYELOID SOMATIC MUTATION PANEL TESTING IN MYELOPROLIFERATIVE NEOPLASMS. MYELOPROLIFERATIVE NEOPLASMS ARE CHARACTERISED BY SOMATIC MUTATIONS IN PATHWAYS THAT REGULATE CELL PROLIFERATION, EPIGENETIC MODIFICATIONS, RNA SPLICING OR DNA REPAIR. ASSESSMENT OF THE MUTATIONAL PROFILE ASSISTS DIAGNOSIS AND CLASSIFICATION, BUT ALSO AIDS ASSESSMENT OF PROGNOSIS, AND MAY GUIDE THE USE OF EMERGING TARGETED THERAPIES. THE MOST PRACTICAL WAY TO PROVIDE INFORMATION ON NUMEROUS GENETIC VARIANTS IS BY USING MASSIVELY PARALLEL SEQUENCING, COMMONLY IN THE FORM OF DISEASE SPECIFIC NEXT GENERATION SEQUENCING (NGS) PANELS. THIS REVIEW SUMMARISES THE DIAGNOSTIC AND PROGNOSTIC VALUE OF SOMATIC MUTATION TESTING IN PHILADELPHIA-NEGATIVE MYELOPROLIFERATIVE NEOPLASMS: POLYCYTHAEMIA VERA, ESSENTIAL THROMBOCYTHAEMIA, PRIMARY MYELOFIBROSIS, CHRONIC NEUTROPHILIC LEUKAEMIA, SYSTEMIC MASTOCYTOSIS, AND CHRONIC EOSINOPHILIC LEUKAEMIA. NGS PANEL TESTING IS INCREASING IN ROUTINE PRACTICE AND PROMISES TO IMPROVE THE ACCURACY AND EFFICIENCY OF PATHOLOGICAL DIAGNOSIS AND PROGNOSIS. 2021 5 3575 36 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 6 937 19 CHRONIC LYMPHOCYTIC LEUKAEMIA GENOMICS AND THE PRECISION MEDICINE ERA. MASSIVE GENOMIC ANALYSES HAVE UNDERSCORED THE DIVERSITY OF CHRONIC LYMPHOCYTIC LEUKAEMIA (CLL) BETWEEN PATIENTS. GENETIC HETEROGENEITY OF TUMOUR CLONES WITHIN A PATIENT MAY FUEL TUMOUR EVOLUTION. SEVERAL RECURRENTLY DEREGULATED INTRA-CELLULAR PATHWAYS ARE CANDIDATES FOR TARGETED THERAPIES THAT ARE VERY PROMISING AND ARE DRAMATICALLY CHANGING CLINICAL PATIENTS' PERSPECTIVES. IN THIS REVIEW WE PRESENT AN OVERVIEW OF THE GENETIC AND EPIGENETIC FEATURES OF CLL AND THEIR CLINICAL AND BIOLOGICAL IMPLICATIONS. 2017 7 5284 26 PROPOSALS FOR CLINICAL TRIALS IN CHRONIC MYELOMONOCYTIC LEUKEMIA. CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) IS A CLONAL HEMATOLOGIC MALIGNANCY OF MOSTLY OLDER INDIVIDUALS THAT EXHIBITS BOTH MYELODYSPLASTIC AND MYELOPROLIFERATIVE FEATURES. CMML PRESENTATION AND OUTCOME ARE VARIABLE, REFLECTING GENETIC AND CLINICAL HETEROGENEITY. HYPOMETHYLATING AGENTS ARE THE MAINSTAY OF THERAPY BUT INDUCE COMPLETE REMISSIONS IN LESS THAN 20% OF PATIENTS AND DO NOT PROLONG SURVIVAL COMPARED TO HYDROXYUREA. ALLOGENEIC STEM CELL TRANSPLANT (ASCT) IS POTENTIALLY CURATIVE, BUT FEW PATIENTS QUALIFY DUE TO ADVANCED AGE AND/OR COMORBIDITIES. WORK OF THE PAST SEVERAL YEARS HAS IDENTIFIED KEY MOLECULAR PATHWAYS THAT DRIVE DISEASE PROLIFERATION AND TRANSFORMATION TO ACUTE LEUKEMIA, INCLUDING JAK/STAT AND MAPK SIGNALING AND EPIGENETIC DYSREGULATION. THERE IS INCREASINGLY COMPELLING EVIDENCE THAT INFLAMMATION IS A MAJOR DRIVER OF CMML PROGRESSION. THUS FAR HOWEVER, THIS MECHANISTIC KNOWLEDGE HAS NOT YET BEEN TRANSLATED INTO IMPROVED OUTCOMES, SUGGESTING THAT FUNDAMENTALLY NEW APPROACHES ARE REQUIRED. IN THIS REVIEW, WE DISCUSS THE DISEASE COURSE, NEW CLASSIFICATIONS, AND CURRENT TREATMENT LANDSCAPE OF CMML. WE REVIEW ONGOING CLINICAL STUDIES AND DISCUSS OPTIONS FOR RATIONALLY BASED FUTURE CLINICAL TRIALS. 2023 8 945 31 CHRONIC LYMPHOCYTIC LEUKEMIA: MOLECULAR HETEROGENEITY REVEALED BY HIGH-THROUGHPUT GENOMICS. CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) HAS BEEN CONSISTENTLY AT THE FOREFRONT OF GENETIC RESEARCH OWING TO ITS PREVALENCE AND THE ACCESSIBILITY OF SAMPLE MATERIAL. RECENTLY, GENOME-WIDE TECHNOLOGIES HAVE BEEN INTENSIVELY APPLIED TO CLL GENETICS, WITH REMARKABLE PROGRESS. SINGLE NUCLEOTIDE POLYMORPHISM ARRAYS HAVE IDENTIFIED RECURRING CHROMOSOMAL ABERRATIONS, THEREBY FOCUSING FUNCTIONAL STUDIES ON DISCRETE GENOMIC LESIONS AND LEADING TO THE FIRST IMPLICATION OF SOMATIC MICRORNA DISRUPTION IN CANCER. NEXT-GENERATION SEQUENCING (NGS) HAS FURTHER TRANSFORMED OUR UNDERSTANDING OF CLL BY IDENTIFYING NOVEL RECURRENTLY MUTATED PUTATIVE DRIVERS, INCLUDING THE UNEXPECTED DISCOVERY OF SOMATIC MUTATIONS AFFECTING SPLICEOSOME FUNCTION. NGS HAS FURTHER ENABLED IN-DEPTH EXAMINATION OF THE TRANSCRIPTIONAL AND EPIGENETIC CHANGES IN CLL THAT ACCOMPANY GENETIC LESIONS, AND HAS SHED LIGHT ON HOW DIFFERENT DRIVER EVENTS APPEAR AT DIFFERENT STAGES OF DISEASE PROGRESSION AND CLONALLY EVOLVE WITH RELAPSED DISEASE. IN ADDITION TO PROVIDING IMPORTANT INSIGHTS INTO DISEASE BIOLOGY, THESE DISCOVERIES HAVE SIGNIFICANT TRANSLATIONAL POTENTIAL. THEY ENHANCE PROGNOSIS BY HIGHLIGHTING SPECIFIC LESIONS ASSOCIATED WITH POOR CLINICAL OUTCOMES (FOR EXAMPLE, DRIVER EVENTS SUCH AS MUTATIONS IN THE SPLICING FACTOR SUBUNIT GENE SF3B1) OR WITH INCREASED CLONAL HETEROGENEITY (FOR EXAMPLE, THE PRESENCE OF SUBCLONAL DRIVER MUTATIONS). HERE, WE REVIEW NEW GENOMIC DISCOVERIES IN CLL AND DISCUSS THEIR POSSIBLE IMPLICATIONS IN THE ERA OF PRECISION MEDICINE. 2013 9 1078 35 CLONAL NON-MALIGNANT HEMATOLOGICAL DISORDERS: UNRAVELING MOLECULAR PATHOGENIC MECHANISMS TO DEVELOP NOVEL TARGETED THERAPEUTICS. CLONAL NON-MALIGNANT HEMATOLOGICAL DISORDERS ARE A HETEROGENEOUS GROUP OF DISEASES THAT ARE PARTICULARLY CHALLENGING FOR HEMATOLOGISTS. INDEED, MOST OBVIOUS AND FREQUENT HEMATOLOGICAL DISEASES INCLUDE A BROAD SPECTRUM OF MALIGNANCIES, SUCH AS LEUKEMIAS, LYMPHOMAS, MYELOMA, AND OTHER MYELOPROLIFERATIVE OR LYMPHOPROLIFERATIVE DISORDERS. IN RECENT YEARS, ALL THESE DISEASES HAVE BEEN CATEGORIZED BY THE WHO ACCORDING TO A NOVEL CLASSIFICATION OF MYELOID AND LYMPHOID MALIGNANCIES, WHICH TAKES IN ACCOUNT THE OUTSTANDING PROGRESS IN OUR UNDERSTANDING OF MOLECULAR DEFECTS UNDERLYING HEMATOLOGICAL MALIGNANCIES. REGARDLESS OF A NUMBER OF NOVEL TECHNOLOGIES, HEMATOLOGISTS CONTINUE TO DEAL DAILY WITH CONDITIONS WHERE A CLEAR DIAGNOSIS OF A MALIGNANCY IS MISSING: THIS IS THE CASE OF SEVERAL CLONAL HEMATOLOGICAL DISORDERS, WHICH ARE CONSIDERED BONA FIDE NON-MALIGNANT. SOME MYELODYSPLASTIC SYNDROMES, CHRONIC T AND NK DISORDERS OF GRANULAR LYMPHOCYTES, MYELOFIBROSIS, MONOCLONAL GAMMOPATHIES, MONOCLONAL B-CEL LYMPHOCYTOSIS, MASTOCYTOSIS AND PAROXYSMAL NOCTURNAL HEMOGLOBINURIA ARE PARADIGMATIC EXAMPLES OF HOW CLONAL DISORDERS ARE CLEARLY DIFFERENT FROM CANCERS, EVEN IF THEY MAY SHARE WITH HEMATOLOGICAL MALIGNANCIES SIMILAR MOLECULAR, GENETIC, EPIGENETIC AND IMMUNOLOGICAL PROCESSES. INDEED, IT IS NOT ENTIRELY CLEAR WHETHER IN INDIVIDUAL CONDITIONS SUCH PATHOGENIC MECHANISMS MAY REPRESENT INITIAL STEP(S) OF MALIGNANT TRANSFORMATION, MAKING A BRIDGE BETWEEN THESE CLONAL NON-MALIGNANT DISORDERS AND TYPICAL HEMATOLOGICAL CANCERS. SOME OF THESE NON-MALIGNANT DISORDERS IMPLY SPECIFIC PATHOGENIC MECHANISMS AND/OR CLINICAL COURSE, AND SO THEY HAVE BEEN DEFINITELY ESTABLISHED WITH THEIR OWN BIOLOGICAL AND CLINICAL IDENTITY. HOWEVER, THE OBVIOUS QUESTION WHETHER SOME OF THESE CLONAL NON-MALIGNANT HEMATOLOGICAL DISEASES FORM SOME A KIND OF DISEASE-CONTINUUM WITH THEIR CORRESPONDING MALIGNANT COUNTERPART IS STILL TO BE ANSWERED. 2014 10 958 37 CHRONIC MYELOMONOCYTIC LEUKEMIA - A REVIEW. INTRODUCTION: CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) IS A CLONAL MYELOID NEOPLASM, DENOTED BY OVERLAPPING MYELODYSPLASTIC AND MYELOPROLIFERATIVE FEATURES, WITH POOR OVERALL SURVIVAL AND HIGH TRANSFORMATION RATE TO ACUTE MYELOID LEUKEMIA. AREAS COVERED: THIS REVIEW, FOLLOWING A THOROUGH MEDLINE SEARCH OF PERTINENT PUBLISHED LITERATURE, DISCUSSES THE DIAGNOSTIC CRITERIA, THE PATHOGENESIS, AND THE COMPLEX GENETIC LANDSCAPE OF THE DISEASE. PROGNOSTICATION, RESPONSE CRITERIA, THERAPEUTIC MANAGEMENT OF PATIENTS, EFFICACY OF ESTABLISHED AND NOVEL TREATMENT MODALITIES ARE THOROUGHLY REVIEWED. EXPERT OPINION: CYTOGENETIC ABNORMALITIES AND MUTATIONS IN GENES INVOLVED IN EPIGENETIC AND TRANSCRIPTIONAL REGULATION, AND CELL-SIGNALING ARE ABUNDANT IN CMML AND IMPLICATED IN ITS COMPLEX PATHOGENESIS. AS PRESENCE OF THESE MUTATIONS CARRY A PROGNOSTIC IMPACT, THEY ARE INCREASINGLY INCORPORATED IN RISK-STRATIFICATION SCHEMES. NOVEL RESPONSE CRITERIA HAVE BEEN PROPOSED, CONSIDERING THE UNIQUE FEATURES OF THE DISEASE. ALTHOUGH ALLOGENEIC HEMATOPOIETIC STEM CELL TRANSPLANTATION REMAINS THE ONLY TREATMENT WITH CURATIVE INTENT, IT IS RESERVED FOR A MINORITY OF PATIENTS; THEREFORE, THERE IS AN UNMET NEED FOR OPTIMIZING TREATMENT MODALITIES, SUCH AS HYPOMETHYLATING AGENTS, AND INTRODUCING NOVEL AGENTS, WHICH COULD SUBSTANTIALLY IMPROVE SURVIVAL AND QUALITY OF LIFE OF CMML PATIENTS. CLINICAL TRIALS DEDICATED SPECIFICALLY TO CMML ARE NEEDED TO EXPLORE THE EFFICACY AND SAFETY OF NOVEL TREATMENT MODALITIES. 2021 11 2956 33 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 12 957 31 CHRONIC MYELOMONOCYTIC LEUKAEMIA: A CONCISE CLINICAL AND PATHOPHYSIOLOGICAL REVIEW. CHRONIC MYELOMONOCYTIC LEUKAEMIA (CMML) IS A CLONAL HAEMATOPOIETIC STEM CELL DISORDER WITH MYELODYSPLASTIC AND MYELOPROLIFERATIVE OVERLAP FEATURES, AND AN INHERENT TENDENCY TO TRANSFORM TO ACUTE MYELOID LEUKAEMIA. APPROXIMATELY 30% OF PATIENTS PRESENT WITH CLONAL CYTOGENETIC ABNORMALITIES, WHILE ALMOST 90% HAVE MOLECULAR ABERRATIONS INVOLVING EPIGENETIC REGULATION, THE SPLICEOSOME COMPONENT MACHINERY, TUMOUR SUPPRESSOR GENES AND TRANSCRIPTION FACTORS/REGULATORS. NUMEROUS PROGNOSTIC MODELS EXIST FOR CMML, WITH MORE RECENT MODELS INCORPORATING PROGNOSTIC MUTATIONS, SUCH AS THOSE INVOLVING ASXL1. OTHER VARIABLES THAT SEEM TO CONSISTENTLY AFFECT OUTCOMES INCLUDE THE DEGREE OF LEUCOCYTOSIS/MONOCYTOSIS, ANAEMIA AND THROMBOCYTOPENIA. ALLOGENEIC STEM CELL TRANSPLANT REMAINS THE ONLY CURATIVE OPTION FOR CMML, WHILE HYPOMETHYLATING AGENTS CAN BE USED FOR TRANSPLANT-INELIGIBLE PATIENTS OR THOSE WITHOUT SUITABLE STEM CELL SOURCES. TARGETING BIOLOGICAL PATHWAYS ACTIVATED IN CMML OFFERS POTENTIAL HOPE FOR MORE EFFECTIVE AND LESS TOXIC THERAPIES. 2014 13 959 39 CHRONIC MYELOMONOCYTIC LEUKEMIA AND ATYPICAL CHRONIC MYELOID LEUKEMIA: NOVEL PATHOGENETIC LESIONS. CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML) AND ATYPICAL CHRONIC MYELOID LEUKEMIA (ACML) ARE DISTINCT, YET RELATED, ENTITIES OF MYELODYSPLASTIC/MYELOPROLIFERATIVE NEOPLASMS (MDS/MPN) CHARACTERIZED BY MORPHOLOGIC DYSPLASIA WITH ACCUMULATION OF MONOCYTES OR NEUTROPHILS, RESPECTIVELY. OUR UNDERSTANDING OF THE MOLECULAR PATHOGENESIS OF CMML AND ACML HAS ADVANCED, MAINLY DUE TO THE APPLICATION OF NOVEL TECHNOLOGIES SUCH AS ARRAY-BASED KARYOTYPING AND NEXT-GENERATION SEQUENCING. IN ADDITION TO PREVIOUSLY KNOWN RECURRENT ABERRATIONS, SOMATIC UNIPARENTAL DISOMY AFFECTING CHROMOSOMES 3, 4, 7, AND 11 FREQUENTLY OCCURS IN CMML. NOVEL SOMATIC MUTATIONS OF GENES, INCLUDING THOSE ASSOCIATED WITH PROLIFERATION SIGNALING (CBL, RAS, RUNX1, JAK2 (V617F)) AND WITH MODIFICATION OF EPIGENETIC STATUS (TET2, ASXL1, UTX, EZH2) HAVE BEEN FOUND. VARIOUS COMBINATIONS OF MUTATIONS SUGGEST A MULTISTEP PATHOGENESIS AND MAY ACCOUNT FOR CLINICAL HETEROGENEITY. MOST RECENTLY, SEVERAL SPLICEOSOME-ASSOCIATED-GENE MUTATIONS WERE REPORTED AND SRSF2 MUTATIONS ARE FREQUENTLY DETECTED IN CMML. THE PROGNOSTIC AND DIAGNOSTIC SIGNIFICANCE OF THESE MOLECULAR LESIONS, IN PARTICULAR THEIR VALUE AS BIOMARKERS OF RESPONSE OR RESISTANCE TO SPECIFIC THERAPIES, WHILE UNCERTAIN NOW IS LIKELY TO BE CLARIFIED AS LARGE SYSTEMATIC STUDIES COME TO COMPLETION. 2012 14 1071 27 CLONAL DYNAMICS IN CHRONIC LYMPHOCYTIC LEUKEMIA. CHRONIC LYMPHOCYTIC LEUKEMIA HAS A HIGHLY VARIABLE DISEASE COURSE ACROSS PATIENTS, THOUGHT TO BE DRIVEN BY THE VAST INTER- AND INTRAPATIENT MOLECULAR HETEROGENEITY DESCRIBED IN SEVERAL LARGE-SCALE DNA-SEQUENCING STUDIES CONDUCTED OVER THE PAST DECADE. ALTHOUGH THE LAST 5 YEARS HAVE SEEN A DRAMATIC SHIFT IN THE THERAPEUTIC LANDSCAPE FOR CHRONIC LYMPHOCYTIC LEUKEMIA, INCLUDING THE REGULATORY APPROVAL OF SEVERAL POTENT TARGETED AGENTS (IE, IDELALISIB, IBRUTINIB, VENETOCLAX), THE VAST MAJORITY OF PATIENTS STILL INEVITABLY EXPERIENCE DISEASE RECURRENCE OR PERSISTENCE. RECENT GENOME-WIDE SEQUENCING APPROACHES HAVE HELPED TO IDENTIFY SUBCLONAL POPULATIONS WITHIN TUMORS THAT DEMONSTRATE A BROAD SPECTRUM OF SOMATIC MUTATIONS, DIVERSE LEVELS OF RESPONSE TO THERAPY, PATTERNS OF REPOPULATION, AND GROWTH KINETICS. UNDERSTANDING THE IMPACT OF GENETIC, EPIGENETIC, AND TRANSCRIPTOMIC FEATURES ON CLONAL GROWTH DYNAMICS AND DRUG RESPONSE WILL BE AN IMPORTANT STEP TOWARD THE SELECTION AND TIMING OF THERAPY. 2019 15 944 26 CHRONIC LYMPHOCYTIC LEUKEMIA: FROM MOLECULAR PATHOGENESIS TO NOVEL THERAPEUTIC STRATEGIES. CHRONIC LYMPHOCYTIC LEUKEMIA IS A WELL-DEFINED LYMPHOID NEOPLASM WITH VERY HETEROGENEOUS BIOLOGICAL AND CLINICAL BEHAVIOR. THE LAST DECADE HAS BEEN REMARKABLY FRUITFUL IN NOVEL FINDINGS ELUCIDATING MULTIPLE ASPECTS OF THE PATHOGENESIS OF THE DISEASE INCLUDING MECHANISMS OF GENETIC SUSCEPTIBILITY, INSIGHTS INTO THE RELEVANCE OF IMMUNOGENETIC FACTORS DRIVING THE DISEASE, PROFILING OF GENOMIC ALTERATIONS, EPIGENETIC SUBTYPES, GLOBAL EPIGENOMIC TUMOR CELL REPROGRAMMING, MODULATION OF TUMOR CELL AND MICROENVIRONMENT INTERACTIONS, AND DYNAMICS OF CLONAL EVOLUTION FROM EARLY STEPS IN MONOCLONAL B CELL LYMPHOCYTOSIS TO PROGRESSION AND TRANSFORMATION INTO DIFFUSE LARGE B-CELL LYMPHOMA. ALL THIS KNOWLEDGE HAS OFFERED NEW PERSPECTIVES THAT ARE BEING EXPLOITED THERAPEUTICALLY WITH NOVEL TARGET AGENTS AND MANAGEMENT STRATEGIES. IN THIS REVIEW WE PROVIDE AN OVERVIEW OF THESE NOVEL ADVANCES AND HIGHLIGHT QUESTIONS AND PERSPECTIVES THAT NEED FURTHER PROGRESS TO TRANSLATE INTO THE CLINICS THE BIOLOGICAL KNOWLEDGE AND IMPROVE THE OUTCOME OF THE PATIENTS. 2020 16 467 30 ARE WE FINALLY GETTING PERSONAL? MOVING TOWARDS A PERSONALIZED APPROACH IN CHRONIC LYMPHOCYTIC LEUKEMIA. WITH ITS HETEROGENEOUS BIOLOGICAL FEATURES AND CLINICAL COURSE, CHRONIC LYMPHOCYTIC LEUKEMIA (CLL), THE MOST FREQUENT ADULT LEUKEMIA IN THE WESTERN WORLD, IS A PARADIGMATIC CONDITION REQUIRING A TAILORED APPROACH AND A PRECISE KNOWLEDGE OF THE BIOLOGY BEHIND EACH INDIVIDUAL PATIENT. THIS PERSONALIZED MANAGEMENT IS BECOMING EVEN MORE CRUCIAL, SINCE, AFTER DECADES OF PRECLINICAL WORK UNRAVELLING THE KEY ROLE OF THE B-CELL RECEPTOR (BCR) SIGNALLING PATHWAYS AND THE ANTI-APOPTOTIC MECHANISMS IN CLL CELL SURVIVAL AND PROLIFERATION, WE HAVE NOW BCR AND BCL2 INHIBITORS AVAILABLE IN CLINICAL PRACTICE. THANKS TO THIS, WE ARE NOW ABLE TO EXPLOIT SPECIFIC BIOMARKERS TO TAILOR OUR TREATMENT STRATEGIES AND IMPROVE LONG-TERM DISEASE CONTROL, PATIENT OUTCOME AND QUALITY OF LIFE. THAT NOTWITHSTANDING, AS THE DISEASE ITSELF REMAINS INCURABLE, NOVEL CHALLENGES AND UNMET CLINICAL NEEDS HAVE RISEN FROM THE INTRODUCTION OF NOVEL TARGETED AGENTS, INCLUDING MECHANISMS OF RESISTANCE AT BOTH GENETIC AND EPIGENETIC LEVELS. IN THIS REVIEW, WE SUMMARIZE THE CURRENTLY ESTABLISHED PREDICTIVE BIOMARKERS (I.E. IGHV MUTATION STATUS AND TP53 GENE DISRUPTION) THAT SHOULD BE APPLIED IN CLINICAL PRACTICE TO INFORM TREATMENT DECISION IN 2021 BUT ALSO DISCUSS THE MOST PROMISING PROGNOSTIC BIOMARKERS (B-CELL RECEPTOR STEREOTYPY, COMPLEX KARYOTYPE, SOMATIC GENE MUTATIONS, MEASURABLE RESIDUAL DISEASE - MRD) THAT MIGHT BECOME KEY TO DEFINE THE MANAGEMENT OF OUR PATIENTS IN A NEAR FUTURE. 2022 17 1164 20 CONTRIBUTION OF CHRONIC MYELOID LEUKAEMIA (CML) AS A DISEASE MODEL TO DEFINE AND STUDY CLONAL HETEROGENEITY. ALTHOUGH TUMOUR CELL INTRA-CLONAL HETEROGENEITY HAS BEEN KNOWN FOR MANY YEARS, ITS APPLICATION IN THE ONCOLOGY CLINICAL PRACTICE (PATIENT MANAGEMENT, PROGNOSIS, ETC.) REMAINS LIMITED. FOR THIS, CHRONIC MYELOID LEUKAEMIA (CML) IS A REMARKABLE MODEL. BASIC RESEARCH STUDIES REVEALED THE HETEROGENEITY OF THE INITIAL CLONE, AND LED TO THE HYPOTHESIS OF THE EXISTENCE OF LEUKEMIC STEM CELLS. NEVERTHELESS, THE INDISPUTABLE EVIDENCE OF THE INTRA-CLONAL HETEROGENEITY ROLE IN THE THERAPEUTIC RESPONSE CAME FROM THE OUTCOMES OF THE TREATMENT WITH TYROSINE KINASE INHIBITORS (THE FIRST TARGETED THERAPY IN MEDICINE) COMBINED WITH THE EARLY AND RIGOROUS CLINICAL AND MOLECULAR MONITORING OF THESE PATIENTS. CML MANAGEMENT ALREADY TAKES THIS HETEROGENEITY INTO ACCOUNT FOR PERSONALIZED PATIENT FOLLOW-UP. THE ADVENTURE CONTINUES WITH THE OBJECTIVES OF BETTER TAILORING THE TREATMENT AND OF CURING THE DISEASE IN MOST OF THE PATIENTS. 2019 18 1242 33 CURRENT AND NOVEL THERAPEUTIC APPROACHES IN MYELODYSPLASTIC SYNDROMES. MYELODYSPLASTIC SYNDROMES (MDS) ARE A HETEROGENEOUS GROUP OF HEMATOLOGIC NEOPLASMS WITH AN ANNUAL INCIDENCE OF 4.1 CASES PER 100,000 AMERICANS. PATIENTS WITH MDS SUFFER FROM CHRONIC CYTOPENIAS THAT MAY LEAD TO RECURRENT TRANSFUSIONS, INFECTIONS, AND INCREASED RISK FOR BLEEDING. THEY ARE ALSO AT RISK FOR PROGRESSION TO ACUTE MYELOID LEUKEMIA. ALLOGENEIC HEMATOPOIETIC CELL TRANSPLANTATION IS THE ONLY POTENTIALLY CURATIVE TREATMENT FOR MDS, ALTHOUGH 3 DRUGS HAVE BEEN APPROVED BY THE US FOOD AND DRUG ADMINISTRATION FOR ITS TREATMENT: LENALIDOMIDE, 5-AZACITIDINE, AND DECITABINE. THESE THERAPIES CAN BE EFFECTIVE IN THE RELIEF OF CYTOPENIAS, ACHIEVEMENT OF CYTOGENETIC REMISSIONS, AND REDUCTION IN BONE MARROW BLASTS. 5-AZACITIDINE HAS ALSO BEEN SHOWN TO IMPROVE OVERALL SURVIVAL. HOWEVER, THERE REMAIN MANY UNMET NEEDS IN THE TREATMENT OF MDS. BREAKTHROUGHS IN OUR UNDERSTANDING OF THE COMPLEX PATHOGENESIS OF MDS THROUGH EPIGENETIC, GENETIC, IMMUNOLOGIC, AND OTHER BIOLOGICAL MECHANISMS HAVE ALLOWED US TO DEVELOP NEW THERAPEUTIC STRATEGIES THAT CAN LEAD TO IMPROVEMENTS IN OUTCOMES IN MDS. IN THIS REVIEW, WE AIM TO PROVIDE AN OVERVIEW OF THE EVOLUTION IN CLASSIFCATION AND RISK STRATIFCATION IN MDS AND TO ILLUSTRATE HOW WE CAN USE THIS TO GUIDE US IN TAILORING THERAPEUTIC CHOICES IN THIS DISEASE. RESPONSES AND OUTCOMES RELATED TO COM MONLY USED MDS THERAPIES WILL BE DISCUSSED TOGETHER WITH NOVEL THERAPIES THAT HAVE EVOLVED WITH THE IMPROVED UNDERSTANDING OF MDS PATHOPHYSIOLOGY. 2014 19 4471 47 MOLECULAR PATHOGENESIS OF ATYPICAL CML, CMML AND MDS/MPN-UNCLASSIFIABLE. ACCORDING TO THE 2008 WHO CLASSIFICATION, THE CATEGORY OF MYELODYSPLASTIC/MYELOPROLIFERATIVE NEOPLASMS (MDS/MPN) INCLUDES ATYPICAL CHRONIC MYELOID LEUKAEMIA (ACML), CHRONIC MYELOMONOCYTIC LEUKAEMIA (CMML), MDS/MPN-UNCLASSIFIABLE (MDS/MPN-U), JUVENILE MYELOMONOCYTIC LEUKAEMIA (JMML) AND A "PROVISIONAL" ENTITY, REFRACTORY ANAEMIA WITH RING SIDEROBLASTS AND THROMBOCYTOSIS (RARS-T). THE REMARKABLE PROGRESS IN OUR UNDERSTANDING OF THE SOMATIC PATHOGENESIS OF MDS/MPN HAS MADE IT CLEAR THAT THERE IS CONSIDERABLE OVERLAP AMONG THESE DISEASES AT THE MOLECULAR LEVEL, AS WELL AS LAYERS OF UNEXPECTED COMPLEXITY. DEREGULATION OF SIGNALLING PLAYS AN IMPORTANT ROLE IN MANY CASES, AND IS CLEARLY LINKED TO MORE HIGHLY PROLIFERATIVE DISEASE. OTHER MUTATIONS AFFECT A RANGE OF OTHER ESSENTIAL, INTERRELATED CELLULAR MECHANISMS, INCLUDING EPIGENETIC REGULATION, RNA SPLICING, TRANSCRIPTION, AND DNA DAMAGE RESPONSE. THE VARIOUS COMBINATIONS OF MUTATIONS INDICATE A MULTI-STEP PATHOGENESIS, WHICH LIKELY CONTRIBUTES TO THE MARKED CLINICAL HETEROGENEITY OF THESE DISORDERS. THE DELINEATION OF COMPLEX CLONAL ARCHITECTURES MAY SERVE AS THE CORNERSTONE FOR THE IDENTIFICATION OF NOVEL THERAPEUTIC TARGETS AND LEAD TO BETTER PATIENT OUTCOMES. THIS REVIEW SUMMARIZES SOME OF THE CURRENT KNOWLEDGE OF MOLECULAR PATHOGENETIC LESIONS IN THE MDS/MPN SUBTYPES THAT ARE SEEN IN ADULTS: ATYPICAL CML, CMML AND MDS/MPN-U. 2015 20 3747 31 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