1 6040 153 THE CHRONIC MYELOPROLIFERATIVE DISORDERS: CLONALITY AND CLINICAL HETEROGENEITY. THE CHRONIC MYELOPROLIFERATIVE DISORDERS (MPD), POLYCYTHEMIA VERA (PV), CHRONIC IDIOPATHIC MYELOFIBROSIS (IMF), ESSENTIAL THROMBOCYTOSIS (ET), AND CHRONIC MYELOGENOUS LEUKEMIA (CML), ARE THOUGHT TO BE CLONAL DISORDERS ARISING IN A MULTIPOTENT HEMATOPOIETIC PROGENITOR CELL. HOWEVER, ESTABLISHING THE DIAGNOSIS OF AN MPD OTHER THAN CML IS PROBLEMATIC DUE TO A LACK OF CLINICALLY APPLICABLE CLONAL MARKERS. FURTHERMORE, IN SOME PATIENTS, IN WHOM A CLASSICAL MPD PHENOTYPE IS PRESENT, THE HEMATOPOIETIC STEM CELLS APPEAR TO BE POLYCLONAL, SUGGESTING THAT THE CHRONIC MPD OTHER THAN CML MAY ACTUALLY BE A GENETICALLY HETEROGENEOUS GROUP OF DISORDERS. FURTHERMORE, SINCE THE ABERRANT CLONE IS BELIEVED TO ARISE FROM A MULTIPOTENT HEMATOPOIETIC STEM CELL, THE NON-CML CHRONIC MPD-ET, PV, AND IMF-COULD BE RELATED. ADDITIONAL UNRESOLVED ISSUES REGARDING THE MPD INCLUDE: IDENTIFICATION OF THE MULTIPOTENT HEMATOPOIETIC PROGENITOR CELL INVOLVED, THE MOLECULAR BASIS FOR THE CLINICAL HETEROGENEITY AMONGST THE INDIVIDUAL MPD, THE CLINICAL SIGNIFICANCE OF CLONALITY IN NON-CML MPD, AND RECONCILIATION OF THERAPY WITH THE CLONAL AND CLINICAL HETEROGENEITY OF THESE DISORDERS. DETERMINATION OF CLONALITY HAS LARGELY BEEN CARRIED OUT USING X CHROMOSOME-LINKED POLYMORPHISMS, BUT SUCH STUDIES ARE LIMITED TO WOMEN AND WITH INCREASING PATIENT AGE ARE COMPROMISED BY SKEWING OF ALLELIC EXPRESSION IN BOTH NEUTROPHILS AND T LYMPHOCYTES, MAKING THE RESULTS DIFFICULT TO INTERPRET. X CHROMOSOME-LINKED POLYMORPHISM STUDIES HAVE INDICATED THAT IN PV THE TARGET STEM CELL IS ONE THAT GIVES RISE TO BOTH LYMPHOID AND MYELOID PROGENITORS. RECENTLY, TWO EPIGENETIC MARKERS HAVE BEEN IDENTIFIED IN THE MPD: IMPAIRED EXPRESSION OF THE THROMBOPOIETIN RECEPTOR, MPL, IN PLATELETS AND MEGAKARYOCYTES, AND OVEREXPRESSION IN NEUTROPHILS OF THE MRNA OF A GENE DESIGNATED POLYCYTHEMIA RUBRA VERA-1 (PRV-1). THE ROLE OF THESE EPIGENETIC ABNORMALITIES IN THE DIAGNOSIS OF THE MPD REMAINS TO BE ESTABLISHED. CURRENTLY, GIVEN THE UNRESOLVED ISSUES WITH RESPECT TO THE CLINICAL AND CLONAL HETEROGENEITY OF THE MPD, TREATMENT NEEDS TO BE TAILORED INDIVIDUALLY IN PATIENTS WITH AN MPD. 2004 2 964 37 CHRONIC MYELOPROLIFERATIVE DISEASES WITH AND WITHOUT THE PH CHROMOSOME: SOME UNRESOLVED ISSUES. PH-POSITIVE CHRONIC MYELOID LEUKEMIA (CML) AND PH-NEGATIVE CHRONIC MYELOPROLIFERATIVE DISEASES (MPDS), CHARACTERIZED IN MANY CASES BY THE PRESENCE OF THE JAK2(V617F) MUTATION, HAVE MANY FEATURES IN COMMON AND YET ALSO SHOW FUNDAMENTAL DIFFERENCES. IN THIS REVIEW, WE POSE FIVE DISCRETE AND RELATED QUESTIONS RELEVANT TO BOTH CATEGORIES OF HEMATOLOGICAL MALIGNANCY, NAMELY: WHAT ARE THE MECHANISMS THAT UNDERLIE DISEASE PROGRESSION FROM A RELATIVELY BENIGN OR CHRONIC PHASE? BY WHAT THERAPEUTIC METHODS MIGHT ONE TARGET RESIDUAL LEUKEMIA STEM CELLS IN CML? IS JAK2(V617F) THE ORIGINAL MOLECULAR EVENT IN MPD? WHAT EPIGENETIC EVENTS MUST HAVE A ROLE IN DICTATING DISEASE PHENOTYPE IN MPDS? AND FINALLY, WILL THE BENEFITS CONFERRED BY CURRENT OR FUTURE JAK2(V617F) INHIBITORS EQUAL OR EVEN SURPASS THE CLINICAL SUCCESS THAT HAS RESULTED FROM THE USE OF TYROSINE KINASE INHIBITORS IN CML? THESE AND OTHERS QUESTIONS MUST BE ADDRESSED AND IN SOME CASES SHOULD BE ANSWERED IN THE FORESEEABLE FUTURE. 2009 3 6856 44 [NOT AVAILABLE]. BIOLOGICAL ASPECTS OF JAK/STAT SIGNALING IN BCR-ABL-NEGATIVE MYELOPROLIFERATIVE NEOPLASMS: MYELOPROLIFERATIVE DISORDERS MORE RECENTLY NAMED MYELOPROLIFERATIVE NEOPLASMS (MPN) DISPLAY SEVERAL CLINICAL ENTITIES: CHRONIC MYELOID LEUKEMIA (CML), THE CLASSICAL MPN INCLUDING POLYCYTHEMIA VERA (PV), ESSENTIAL THROMBOCYTHEMIA (ET), PRIMARY MYELOFIBROSIS (PMF) AND ATYPICAL AND UNCLASSIFIABLE NMP. THE TERM MPN IS MOSTLY USED FOR CLASSICAL BCR-ABL-NEGATIVE (MYELOPROLIFERATIVE DISORDER) (ET, PV, PMF). THESE ARE CLONAL DISEASES RESULTING FROM THE TRANSFORMATION OF AN HEMATOPOIETIC STEM CELL AND LEADING TO AN ABNORMAL PRODUCTION OF MYELOID CELLS. THE GENETIC DEFECTS RESPONSIBLE FOR THE MYELOPROLIFERATIVE ABNORMALITIES ARE CALLED << DRIVER >> MUTATIONS AND ALL RESULT IN DEREGULATION OF THE CYTOKINE RECEPTOR / JAK2 / STAT AXIS. AMONG THEM, JAK2, THE THROMBOPOIETIN RECEPTOR (MPL) AND CALRETICULIN (CALR) MUTATIONS ARE FOUND IN AROUND 90% OF THE CASES. THESE DRIVER MPN MUTATIONS CAN BE ASSOCIATED WITH OTHER DRIVER MUTATIONS ALSO FOUND IN OTHER HEMATOLOGICAL MALIGNANCIES, ESPECIALLY IN PMFS. THESE ARE CHRONIC DISEASES WITH MAJOR RISKS BEING THROMBOSIS, HEMORRHAGE AND CYTOPENIAS FOR PMF AND THE LONG-TERM PROGRESSION TO MYELOFIBROSIS AND THE TRANSFORMATION TO LEUKEMIA. MOST RECENT THERAPEUTIC HAVE FOCUSED ON TARGETING THE JAK2 SIGNALING PATHWAY DIRECTLY BY INHIBITORS OF JAK2 OR INDIRECTLY. INTERFERON A ALLOWS IN SOME CASES HEMATOLOGIC AND MOLECULAR REMISSION PATIENTS. 2016 4 4959 32 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 5 5953 39 TARGETS IN MPNS AND POTENTIAL THERAPEUTICS. PHILADELPHIA-NEGATIVE CLASSICAL MYELOPROLIFERATIVE NEOPLASMS (MPNS), INCLUDING POLYCYTHEMIA VERA (PV), ESSENTIAL THROMBOCYTHEMIA (ET) AND PRIMARY MYELOFIBROSIS (PMF), ARE CLONAL HEMOPATHIES THAT EMERGE IN THE HEMATOPOIETIC STEM CELL (HSC) COMPARTMENT. MPN DRIVER MUTATIONS ARE RESTRICTED TO SPECIFIC EXONS (14 AND 12) OF JANUS KINASE 2 (JAK2), THROMBOPOIETIN RECEPTOR (MPL/TPOR) AND CALRETICULIN (CALR) GENES, ARE INVOLVED DIRECTLY IN CLONAL MYELOPROLIFERATION AND GENERATE THE MPN PHENOTYPE. AS A RESULT, AN INCREASED NUMBER OF FULLY FUNCTIONAL ERYTHROCYTES, PLATELETS AND LEUKOCYTES IS OBSERVED IN THE PERIPHERAL BLOOD. NEVERTHELESS, THE COMPLEXITY AND HETEROGENEITY OF MPN CLINICAL PHENOTYPES CANNOT BE SOLELY EXPLAINED BY THE TYPE OF DRIVER MUTATION. OTHER FACTORS, SUCH AS ADDITIONAL SOMATIC MUTATIONS AFFECTING EPIGENETIC REGULATORS OR SPLICEOSOMES COMPONENTS, MUTANT ALLELE BURDENS AND MODIFIERS OF SIGNALING BY DRIVER MUTANTS, CLONAL ARCHITECTURE AND THE ORDER OF MUTATION ACQUISITION, SIGNALING EVENTS THAT OCCUR DOWNSTREAM OF A DRIVER MUTATION, THE PRESENCE OF SPECIFIC GERM-LINE VARIANTS, THE INTERACTION OF THE NEOPLASTIC CLONE WITH BONE MARROW MICROENVIRONMENT AND CHRONIC INFLAMMATION, ALL CAN MODULATE THE DISEASE PHENOTYPE, INFLUENCE THE MPN CLINICAL COURSE AND THEREFORE, MIGHT BE USEFUL THERAPEUTIC TARGETS. 2022 6 3111 31 GENOTYPE-PHENOTYPE INTERACTIONS IN THE MYELOPROLIFERATIVE NEOPLASMS. THE CHRONIC MYELOPROLIFERATIVE NEOPLASMS (MPNS) ARE CLONAL DISORDERS CHARACTERIZED BY OVERPRODUCTION OF MATURE MYELOID CELLS. THEY SHARE ASSOCIATIONS WITH MOLECULAR ABNORMALITIES SUCH AS THE JAK2V617F MUTATION BUT ARE DISTINGUISHED BY IMPORTANT PHENOTYPIC DIFFERENCES. THIS REVIEW FIRST CONSIDERS THE FACTORS THAT MAY INFLUENCE PHENOTYPE IN JAK2-MUTATED MPNS, ESPECIALLY POLYCYTHEMIA VERA (PV) AND ESSENTIAL THROMBOCYTHEMIA (ET), AND THEN DISCUSSES THE MUTATIONS IMPLICATED IN JAK2-NEGATIVE MPNS SUCH AS IN MPL AND EPIGENETIC REGULATORS. CURRENT EVIDENCE SUPPORTS A MODEL WHERE ET AND PV ARE DISORDERS OF RELATIVELY LOW GENETIC COMPLEXITY, WHEREAS EVOLUTION TO MYELOFIBROSIS OR BLAST-PHASE DISEASE REFLECTS ACCUMULATION OF A HIGHER MUTATION BURDEN. 2012 7 1947 47 EPIGENETIC ABNORMALITIES IN MYELOPROLIFERATIVE NEOPLASMS: A TARGET FOR NOVEL THERAPEUTIC STRATEGIES. THE MYELOPROLIFERATIVE NEOPLASMS (MPNS) ARE A GROUP OF CLONAL HEMATOLOGICAL MALIGNANCIES CHARACTERIZED BY A HYPERCELLULAR BONE MARROW AND A TENDENCY TO DEVELOP THROMBOTIC COMPLICATIONS AND TO EVOLVE TO MYELOFIBROSIS AND ACUTE LEUKEMIA. UNLIKE CHRONIC MYELOGENOUS LEUKEMIA, WHERE A SINGLE DISEASE-INITIATING GENETIC EVENT HAS BEEN IDENTIFIED, A MORE COMPLICATED SERIES OF GENETIC MUTATIONS APPEAR TO BE RESPONSIBLE FOR THE BCR-ABL1-NEGATIVE MPNS WHICH INCLUDE POLYCYTHEMIA VERA, ESSENTIAL THROMBOCYTHEMIA, AND PRIMARY MYELOFIBROSIS. RECENT STUDIES HAVE REVEALED A NUMBER OF EPIGENETIC ALTERATIONS THAT ALSO LIKELY CONTRIBUTE TO DISEASE PATHOGENESIS AND DETERMINE CLINICAL OUTCOME. INCREASING EVIDENCE INDICATES THAT ALTERATIONS IN DNA METHYLATION, HISTONE MODIFICATION, AND MICRORNA EXPRESSION PATTERNS CAN COLLECTIVELY INFLUENCE GENE EXPRESSION AND POTENTIALLY CONTRIBUTE TO MPN PATHOGENESIS. EXAMPLES INCLUDE MUTATIONS IN GENES ENCODING PROTEINS THAT MODIFY CHROMATIN STRUCTURE (EZH2, ASXL1, IDH1/2, JAK2V617F, AND IKZF1) AS WELL AS EPIGENETIC MODIFICATION OF GENES CRITICAL FOR CELL PROLIFERATION AND SURVIVAL (SUPPRESSORS OF CYTOKINE SIGNALING, POLYCYTHEMIA RUBRA VERA-1, CXC CHEMOKINE RECEPTOR 4, AND HISTONE DEACETYLASE (HDAC)). THESE EPIGENETIC LESIONS SERVE AS NOVEL TARGETS FOR EXPERIMENTAL THERAPEUTIC INTERVENTIONS. CLINICAL TRIALS ARE CURRENTLY UNDERWAY EVALUATING HDAC INHIBITORS AND DNA METHYLTRANSFERASE INHIBITORS FOR THE TREATMENT OF PATIENTS WITH MPNS. 2011 8 162 27 ABL1 METHYLATION IN PH-POSITIVE ALL IS EXCLUSIVELY ASSOCIATED WITH THE P210 FORM OF BCR-ABL. IN HUMAN PH-POSITIVE LEUKEMIA THERE IS A CLEAR ASSOCIATION OF DIFFERENT FORMS OF THE BCR-ABL ONCOGENE WITH DISTINCT TYPES OF LEUKEMIA. THE P190 FORM OF BCR-ABL IS RARELY OBSERVED IN CHRONIC MYELOID LEUKEMIA (CML) BUT IS PRESENT IN 50% OF PH-POSITIVE ACUTE LYMPHOBLASTIC LEUKEMIA (ALL). IN CONTRAST, THE P210 FORM IS OBSERVED BOTH IN CML AND 50% OF PH-POSITIVE ALL. METHYLATION OF THE PROXIMAL PROMOTER OF THE ABL1 GENE HAS BEEN SHOWN TO BE A NEARLY UNIVERSAL EVENT ASSOCIATED WITH CLINICAL PROGRESSION OF CML. THIS RAISES THE QUESTION OF WHETHER METHYLATION OF THE ABL1 PROMOTER IS AN EPIGENETIC MODIFICATION ALSO ASSOCIATED WITH PH-POSITIVE ALL. TO STUDY THIS ISSUE, WE USED METHYLATION-SPECIFIC PCR AND BISULFITE SEQUENCING TO DETERMINE THE METHYLATION STATUS OF THE ABL1 PROMOTER IN 18 PH-POSITIVE ALL SAMPLES. WE REPORT HERE THAT GENE-SPECIFIC ABL1 PROMOTER METHYLATION IS ASSOCIATED MAINLY WITH THE P210 FORM OF BCR-ABL AND NOT THE P190 FORM. WHILE SIX OUT OF THE SEVEN P210-POSITIVE ALL SAMPLES HAD ABL1 PROMOTER METHYLATION, NONE OF THE 11 P190-POSITIVE ALL SAMPLES DEMONSTRATED ABL1 PROMOTER METHYLATION. IN ADDITION, WE ESTIMATED THE EXTENT AND RELATIVE ABUNDANCE OF ABL1 PROMOTER METHYLATION IN SEVERAL PH-POSITIVE ALL SAMPLES AND COMPARED IT TO THE METHYLATION PATTERN IN CHRONIC, ACCELERATED AND BLASTIC CRISIS PHASES OF CML. WE PUT FORTH A MODEL THAT CORRELATES THE DIFFERENT TYPES OF LEUKEMIAS WITH THE DIFFERENT LEVELS OF ABL1 PROMOTER METHYLATION. 2001 9 4322 39 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 10 3129 34 GIVINOSTAT: AN EMERGING TREATMENT FOR POLYCYTHEMIA VERA. INTRODUCTION: POLYCYTHEMIA VERA (PV), A PHILADELPHIA CHROMOSOME-NEGATIVE MYELOPROLIFERATIVE NEOPLASM, IS CHARACTERIZED BY PANMYELOSIS, PANCYTOSIS, AND A JAK2 MUTATION. PATIENTS ARE AT INCREASED RISK OF THROMBOHEMORRHAGIC EVENTS, AND PROGRESSION TO MYELOFIBROSIS OR ACUTE LEUKEMIA. CURRENT TREATMENTS INCLUDE ASPIRIN, PHLEBOTOMY, AND CYTOREDUCTIVE DRUGS (MOST COMMONLY HYDROXYUREA). GIVINOSTAT IS A POTENT, CLASS I/II HISTONE DEACETYLASE (HDAC) INHIBITOR THAT IS IN PHASE I/II CLINICAL TRIALS IN PV. GIVINOSTAT WAS WELL TOLERATED AND YIELDED PROMISING CLINICO-HEMATOLOGICAL RESPONSES. A PHASE III STUDY OF GIVINOSTAT VERSUS HYDROXYUREA IN HIGH-RISK PV PATIENTS IS PLANNED. AREAS COVERED: WE PRESENT AN OVERVIEW OF PV, CURRENT TREATMENT GUIDELINES, AND THE PUTATIVE MECHANISM(S) OF ACTION OF GIVINOSTAT. WE DISCUSS THE PRECLINICAL AND CLINICAL STUDIES OF GIVINOSTAT IN PV AND BRIEFLY REVIEW APPROVED AND INVESTIGATIONAL COMPETITOR COMPOUNDS. EXPERT OPINION: HDAC INHIBITORS HAVE LONG BEEN KNOWN TO BE ACTIVE IN PV, BUT CHRONIC TOXICITIES CAN BE CHALLENGING. GIVINOSTAT, HOWEVER, IS ACTIVE AND WELL TOLERATED, AND IS ENTERING A PIVOTAL PHASE III RANDOMIZED TRIAL. GIVINOSTAT OFFERS THE POSSIBILITY OF REPLACING HYDROXYUREA AS THE STANDARD FIRST-LINE CYTOREDUCTIVE CHOICE FOR PV PATIENTS. THIS WOULD COMPLETELY CHANGE THE CURRENT THERAPEUTIC PARADIGM AND GUIDELINES FOR PV MANAGEMENT. ALTHOUGH SURROGATE CLINICAL STUDY ENDPOINTS MAY SUFFICE FOR REGULATORY PURPOSES, THROMBOSIS REDUCTION AND PREVENTION OF DISEASE PROGRESSION REMAIN MOST IMPORTANT TO PATIENTS AND CLINICIANS. 2020 11 255 37 ADVANCES IN MYELOFIBROSIS: A CLINICAL CASE APPROACH. PRIMARY MYELOFIBROSIS IS A MEMBER OF THE MYELOPROLIFERATIVE NEOPLASMS, A DIVERSE GROUP OF BONE MARROW MALIGNANCIES. SYMPTOMS OF MYELOFIBROSIS, PARTICULARLY THOSE ASSOCIATED WITH SPLENOMEGALY (ABDOMINAL DISTENTION AND PAIN, EARLY SATIETY, DYSPNEA, AND DIARRHEA) AND CONSTITUTIONAL SYMPTOMS, REPRESENT A SUBSTANTIAL BURDEN TO PATIENTS. MOST PATIENTS EVENTUALLY DIE FROM THE DISEASE, WITH A MEDIAN SURVIVAL RANGING FROM APPROXIMATELY 5-7 YEARS. MUTATIONS IN JANUS KINASE 2 (JAK2), A KINASE THAT IS ESSENTIAL FOR THE NORMAL DEVELOPMENT OF ERYTHROCYTES, GRANULOCYTES, AND PLATELETS, NOTABLY THE V617F MUTATION, HAVE BEEN IDENTIFIED IN APPROXIMATELY 50% OF PATIENTS WITH MYELOFIBROSIS. THE APPROVAL OF A JAK2 INHIBITOR IN 2011 HAS IMPROVED THE OUTLOOK OF MANY PATIENTS WITH MYELOFIBROSIS AND HAS CHANGED THE TREATMENT LANDSCAPE. THIS ARTICLE FOCUSES ON SOME OF THE IMPORTANT ISSUES IN CURRENT MYELOFIBROSIS TREATMENT MANAGEMENT, INCLUDING DIFFERENTIATION OF MYELOFIBROSIS FROM ESSENTIAL THROMBOCYTHEMIA AND POLYCYTHEMIA VERA, UP-DATED DATA ON THE RESULTS OF JAK2 INHIBITOR THERAPY, THE ROLE OF EPIGENETIC MECHANISMS IN MYELOFIBROSIS PATHOGENESIS, INVESTIGATIONAL THERAPIES FOR MYELOFIBROSIS, AND ADVANCES IN HEMATOPOIETIC STEM CELL TRANSPLANT. THREE MYELOFIBROSIS CASES ARE INCLUDED TO UNDERSCORE THE ISSUES IN DIAGNOSING AND TREATING THIS COMPLEX DISEASE. 2013 12 4748 42 NOVEL MUTATIONS AND THEIR FUNCTIONAL AND CLINICAL RELEVANCE IN MYELOPROLIFERATIVE NEOPLASMS: JAK2, MPL, TET2, ASXL1, CBL, IDH AND IKZF1. MYELOPROLIFERATIVE NEOPLASMS (MPNS) ORIGINATE FROM GENETICALLY TRANSFORMED HEMATOPOIETIC STEM CELLS THAT RETAIN THE CAPACITY FOR MULTILINEAGE DIFFERENTIATION AND EFFECTIVE MYELOPOIESIS. BEGINNING IN EARLY 2005, A NUMBER OF NOVEL MUTATIONS INVOLVING JANUS KINASE 2 (JAK2), MYELOPROLIFERATIVE LEUKEMIA VIRUS (MPL), TET ONCOGENE FAMILY MEMBER 2 (TET2), ADDITIONAL SEX COMBS-LIKE 1 (ASXL1), CASITAS B-LINEAGE LYMPHOMA PROTO-ONCOGENE (CBL), ISOCITRATE DEHYDROGENASE (IDH) AND IKAROS FAMILY ZINC FINGER 1 (IKZF1) HAVE BEEN DESCRIBED IN BCR-ABL1-NEGATIVE MPNS. HOWEVER, NONE OF THESE MUTATIONS WERE MPN SPECIFIC, DISPLAYED MUTUAL EXCLUSIVITY OR COULD BE TRACED BACK TO A COMMON ANCESTRAL CLONE. JAK2 AND MPL MUTATIONS APPEAR TO EXERT A PHENOTYPE-MODIFYING EFFECT AND ARE DISTINCTLY ASSOCIATED WITH POLYCYTHEMIA VERA, ESSENTIAL THROMBOCYTHEMIA AND PRIMARY MYELOFIBROSIS; THE CORRESPONDING MUTATIONAL FREQUENCIES ARE APPROXIMATELY 99, 55 AND 65% FOR JAK2 AND 0, 3 AND 10% FOR MPL MUTATIONS. THE INCIDENCE OF TET2, ASXL1, CBL, IDH OR IKZF1 MUTATIONS IN THESE DISORDERS RANGES FROM 0 TO 17%; THESE LATTER MUTATIONS ARE MORE COMMON IN CHRONIC (TET2, ASXL1, CBL) OR JUVENILE (CBL) MYELOMONOCYTIC LEUKEMIAS, MASTOCYTOSIS (TET2), MYELODYSPLASTIC SYNDROMES (TET2, ASXL1) AND SECONDARY ACUTE MYELOID LEUKEMIA, INCLUDING BLAST-PHASE MPN (IDH, ASXL1, IKZF1). THE FUNCTIONAL CONSEQUENCES OF MPN-ASSOCIATED MUTATIONS INCLUDE UNREGULATED JAK-STAT (JANUS KINASE/SIGNAL TRANSDUCER AND ACTIVATOR OF TRANSCRIPTION) SIGNALING, EPIGENETIC MODULATION OF TRANSCRIPTION AND ABNORMAL ACCUMULATION OF ONCOPROTEINS. HOWEVER, IT IS NOT CLEAR AS TO WHETHER AND HOW THESE ABNORMALITIES CONTRIBUTE TO DISEASE INITIATION, CLONAL EVOLUTION OR BLASTIC TRANSFORMATION. 2010 13 5799 31 STEPPING OUT OF ANTIQUITY: AN UPDATE ON EMERGING DRUGS FOR THE TREATMENT OF POLYCYTHEMIA VERA. INTRODUCTION: POLYCYTHEMIA VERA IS A CHRONIC HEMATOLOGIC MALIGNANCY FREQUENTLY PRESENTED WITH CONSTITUTIONAL SYMPTOMS AND ASSOCIATED WITH AN INCREASED RISK OF THROMBOSIS, HEMORRHAGE, AND PROGRESSION TO MYELOFIBROSIS OR ACUTE MYELOID LEUKEMIA. CURRENT TREATMENT STRATEGIES REDUCE THROMBOHEMORRHAGIC RISK BY CONTROLLING BLOOD COUNTS AND INHIBITING PLATELETS, BUT OFTEN FAIL TO ADDRESS DISEASE-RELATED SYMPTOMS OR BIOLOGICALLY MODIFY THE DISEASE.AREAS COVERED: WE REVIEW THE CURRENT PARADIGM FOR TREATING POLYCYTHEMIA VERA, HIGHLIGHT AREAS OF UNMET NEED, REVIEW THERAPEUTIC AGENTS IN LATE STAGE CLINICAL DEVELOPMENT, AND PROVIDE AN OVERARCHING VIEW OF HOW THESE EMERGING AGENT MAY FIT INTO THE FUTURE ARMAMENTARIUM OF POLYCYTHEMIA VERA TREATMENTS.EXPERT OPINION: THE SHIFT FROM FOCUSING SOLELY ON SECONDARY PREVENTION OF THROMBOHEMORRHAGIC EVENTS TO A COMPREHENSIVE TREATMENT STRATEGY THAT ADDITIONALLY AIMS TO IMPROVE QUALITY OF LIFE AND PREVENT DISEASE PROGRESSION HAS RESULTED IN A RAPIDLY EVOLVING THERAPEUTIC LANDSCAPE THAT PROMISES TO MOVE THE TREATMENT OF POLYCYTHEMIA VERA OUT OF ANTIQUITY INTO THE MODERN AGE. 2021 14 6852 38 [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 15 3747 39 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 16 5257 38 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 17 4554 36 MUTATIONAL PROFILING IN MYELOFIBROSIS: IMPLICATIONS FOR MANAGEMENT. MUTATIONAL PROFILING, USUALLY BY TARGETED NEXT-GENERATION SEQUENCING, IS INCREASINGLY PERFORMED ON PATIENTS WITH MYELOPROLIFERATIVE NEOPLASM-ASSOCIATED MYELOFIBROSIS (MF), WHETHER PRIMARY (PMF) OR POST-POLYCYTHEMIA VERA/ESSENTIAL THROMBOCYTHEMIA (POST-PV/ET MF). "DRIVER" MUTATIONS IN JAK2, MPL AND INDELS IN CALR UNDERLIE THE VAST MAJORITY OF CASES OF PMF AND POST-ET MF; THE REMAINDER ( APPROXIMATELY 10%) LACK IDENTIFIABLE DRIVER MUTATIONS, BUT OTHER CLONAL MARKERS ARE USUALLY DETECTABLE. NEARLY ALL PATIENTS WITH POST-PV MF CARRY ACTIVATING JAK2 MUTATIONS. IN BOTH PMF AND POST-ET MF, TYPE 1/-LIKE CALR MUTATIONS CONFER A FAVORABLE PROGNOSIS. SINCE BOTH TYPE 1/-LIKE AND TYPE 2/-LIKE CALR MUTATIONS HAVE ESSENTIALLY THE SAME FUNCTIONAL CONSEQUENCE, THIS IS A SUBJECT OF INTENSE RESEARCH. ADDITIONAL, "NON-DRIVER" MUTATIONS, MOSTLY AFFECTING GENES ENCODING EPIGENETIC MODIFIERS OR SPLICEOSOME COMPONENTS, E.G., ASXL1, EZH2, TET2, DNMT3A, SRSF2 AND U2AF1, ARE FREQUENTLY FOUND; SOME OF THESE ARE ASSOCIATED WITH INFERIOR SURVIVAL AND HAVE BEEN INCORPORATED INTO PROGNOSTIC MODELS. SOME MUTATIONS, E.G., IDH1/2, ARE RELATIVELY INFREQUENT IN CHRONIC PHASE BUT ARE SUBSTANTIALLY MORE COMMON IN BLAST PHASE, AND ARE NOW THERAPEUTICALLY TARGETABLE. WHILE MUTATIONAL INFORMATION DOES NOT CURRENTLY INFLUENCE CHOICE OF DRUG THERAPY IN CHRONIC-PHASE MF, THE PRESENCE OF A "HIGH MOLECULAR RISK" GENOTYPE IS NOW ROUTINELY TAKEN INTO ACCOUNT FOR TRANSPLANT DECISION-MAKING. 2020 18 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 19 6079 40 THE EFFECT OF CXCL12 PROCESSING ON CD34+ CELL MIGRATION IN MYELOPROLIFERATIVE NEOPLASMS. PRIMARY MYELOFIBROSIS (PMF) AND POLYCYTHEMIA VERA (PV) ARE CHRONIC MYELOPROLIFERATIVE NEOPLASMS. PMF AND, TO A LESSER DEGREE, PV ARE CHARACTERIZED BY CONSTITUTIVE MOBILIZATION OF HEMATOPOIETIC STEM CELLS (HSC) AND PROGENITOR CELLS (HPC) INTO THE PERIPHERAL BLOOD (PB). THE INTERACTION BETWEEN THE CHEMOKINE CXCL12 AND ITS RECEPTOR CXCR4 PLAYS A PIVOTAL ROLE IN DETERMINING THE TRAFFICKING OF CD34(+) CELLS BETWEEN THE BONE MARROW (BM) AND THE PB. PMF, BUT NOT PV, IS ASSOCIATED WITH DOWNREGULATION OF CXCR4 BY CD34(+) CELLS DUE TO EPIGENETIC EVENTS. BOTH PV AND PMF PATIENTS HAVE ELEVATED LEVELS OF IMMUNOREACTIVE FORMS OF CXCL12 IN THE BM AND PB. USING ELECTROSPRAY MASS SPECTROMETRY, THE PB AND BM PLASMA OF PV AND PMF PATIENTS WAS SHOWN TO CONTAIN REDUCED AMOUNTS OF INTACT CXCL12 BUT SIGNIFICANT AMOUNTS OF SEVERAL TRUNCATED FORMS OF CXCL12, WHICH ARE LACKING IN NORMAL PB AND BM PLASMA. THESE TRUNCATED FORMS OF CXCL12 ARE THE PRODUCT OF THE ACTION OF SEVERAL SERINE PROTEASES, INCLUDING DIPEPTIDYL PEPTIDASE-IV, NEUTROPHIL ELASTASE, MATRIX METALLOPROTEINASE-2 (MMP-2), MMP-9, AND CATHEPSIN G. UNLIKE CXCL12, THESE TRUNCATES EITHER LACK THE ABILITY TO ACT AS A CHEMOATTRACTANT FOR CD34(+) CELLS AND/OR ACT AS AN ANTAGONIST TO THE ACTION OF CXCL12. THESE DATA SUGGEST THAT PROTEOLYTIC DEGRADATION OF CXCL12 IS CHARACTERISTIC OF BOTH PV AND PMF AND THAT THE RESULTING TRUNCATED FORMS OF CXCL12, IN ADDITION TO THE REDUCED EXPRESSION OF CXCR4 BY CD34(+) CELLS, LEAD TO A PROFOUND MOBILIZATION OF HSC/HPC IN PMF. 2010 20 4436 26 MOLECULAR EVOLUTION OF CHRONIC MYELOID LEUKAEMIA. CHRONIC MYELOID LEUKAEMIA (CML) IS A CLONAL DISORDER OF THE PLURIPOTENT HAEMATOPOIETIC STEM CELL. THE TYPICAL TRIPHASIC COURSE OF CML STARTS WITH THE PREMALIGNANT CHRONIC PHASE INITIATED BY BCR-ABL HYBRID ONCOGENE FORMATION. SECONDARY GENETIC AND EPIGENETIC ABERRATIONS ACCOMPANY THE PROGRESSION TO THE ACCELERATED PHASE AND FATAL BLASTIC CRISIS. PROPERLY TIMED BONE MARROW TRANSPLANTATION IN ELIGIBLE PATIENTS CAN RESULT IN DURABLE REMISSIONS OR CURE. BOTH OF THESE STATES ARE OFTEN ACCOMPANIED BY A LONG-TERM PERSISTENCE OF QUIESCENT LEUKAEMIC CELLS. ACCORDINGLY, A "FUNCTIONAL CURE" (I.E. TUMOUR DORMANCY INDUCTION), RATHER THAN COMPLETE ERADICATION OF THE MALIGNANT CELLS, IS AN ADEQUATE THERAPEUTICAL GOAL. THE LEVEL OF THE RESIDUAL BCR-ABL-POSITIVE CLONES SHOULD BE MONITORED AND SALVAGE TREATMENT INITIATED WHENEVER THESE QUIESCENT LEUKAEMIC CELLS EXIT THEIR DORMANT STATE. 2001