1 1102 106 COMBINED CHEMOSENSITIVITY AND CHROMATIN PROFILING PRIORITIZES DRUG COMBINATIONS IN CLL. THE BRUTON TYROSINE KINASE (BTK) INHIBITOR IBRUTINIB HAS SUBSTANTIALLY IMPROVED THERAPEUTIC OPTIONS FOR CHRONIC LYMPHOCYTIC LEUKEMIA (CLL). ALTHOUGH IBRUTINIB IS NOT CURATIVE, IT HAS A PROFOUND EFFECT ON CLL CELLS AND MAY CREATE NEW PHARMACOLOGICALLY EXPLOITABLE VULNERABILITIES. TO IDENTIFY SUCH VULNERABILITIES, WE DEVELOPED A SYSTEMATIC APPROACH THAT COMBINES EPIGENOME PROFILING (CHARTING THE GENE-REGULATORY BASIS OF CELL STATE) WITH SINGLE-CELL CHEMOSENSITIVITY PROFILING (QUANTIFYING CELL-TYPE-SPECIFIC DRUG RESPONSE) AND BIOINFORMATIC DATA INTEGRATION. BY APPLYING OUR METHOD TO A COHORT OF MATCHED PATIENT SAMPLES COLLECTED BEFORE AND DURING IBRUTINIB THERAPY, WE IDENTIFIED CHARACTERISTIC IBRUTINIB-INDUCED CHANGES THAT PROVIDE A STARTING POINT FOR THE RATIONAL DESIGN OF IBRUTINIB COMBINATION THERAPIES. SPECIFICALLY, WE OBSERVED AND VALIDATED PREFERENTIAL SENSITIVITY TO PROTEASOME, PLK1, AND MTOR INHIBITORS DURING IBRUTINIB TREATMENT. MORE GENERALLY, OUR STUDY ESTABLISHES A BROADLY APPLICABLE METHOD FOR INVESTIGATING TREATMENT-SPECIFIC VULNERABILITIES BY INTEGRATING THE COMPLEMENTARY PERSPECTIVES OF EPIGENETIC CELL STATES AND PHENOTYPIC DRUG RESPONSES IN PRIMARY PATIENT SAMPLES. 2019 2 5606 30 RPPA-BASED PROTEOMICS RECOGNIZES DISTINCT EPIGENETIC SIGNATURES IN CHRONIC LYMPHOCYTIC LEUKEMIA WITH CLINICAL CONSEQUENCES. THE CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) ARMAMENTARIUM HAS EVOLVED SIGNIFICANTLY, WITH NOVEL THERAPIES THAT INHIBIT BRUTON TYROSINE KINASE, PI3K DELTA AND/OR THE BCL2 PROTEIN IMPROVING OUTCOMES. STILL, THE CLINICAL COURSE OF CLL PATIENTS IS HIGHLY VARIABLE AND MOST PREVIOUSLY RECOGNIZED PROGNOSTIC FEATURES LACK THE CAPACITY TO PREDICT RESPONSE TO MODERN TREATMENTS INDICATING THE NEED FOR NEW PROGNOSTIC MARKERS. IN THIS STUDY, WE IDENTIFIED FOUR EPIGENETICALLY DISTINCT PROTEOMIC SIGNATURES OF A LARGE COHORT OF CLL AND RELATED DISEASES DERIVED SAMPLES (N = 871) USING REVERSE PHASE PROTEIN ARRAY TECHNOLOGY. THESE SIGNATURES ARE ASSOCIATED WITH CLINICAL FEATURES INCLUDING AGE, CYTOGENETIC ABNORMALITIES [TRISOMY 12, DEL(13Q) AND DEL(17P)], IMMUNOGLOBULIN HEAVY-CHAIN LOCUS (IGHV) MUTATIONAL LOAD, ZAP-70 STATUS, BINET AND RAI STAGING AS WELL AS WITH THE OUTCOME MEASURES OF TIME TO TREATMENT AND OVERALL SURVIVAL. PROTEIN SIGNATURE MEMBERSHIP WAS IDENTIFIED AS PREDICTIVE MARKER FOR OVERALL SURVIVAL REGARDLESS OF OTHER CLINICAL FEATURES. AMONG THE ANALYZED EPIGENETIC PROTEINS, EZH2, HDAC6, AND LOSS OF H3K27ME3 LEVELS WERE THE MOST INDEPENDENTLY ASSOCIATED WITH POOR SURVIVAL. THESE FINDINGS DEMONSTRATE THAT PROTEOMIC BASED EPIGENETIC BIOMARKERS CAN BE USED TO BETTER CLASSIFY CLL PATIENTS AND PROVIDE THERAPEUTIC GUIDANCE. 2022 3 4874 36 OVERCOMING ACQUIRED EPIGENETIC RESISTANCE TO BTK INHIBITORS. THE USE OF BRUTON TYROSINE KINASE (BTK) INHIBITORS TO BLOCK B-CELL RECEPTOR (BCR)-DEPENDENT NF-KAPPAB ACTIVATION IN LYMPHOID MALIGNANCIES HAS BEEN A MAJOR CLINICAL ADVANCE, YET ACQUIRED THERAPEUTIC RESISTANCE IS A RECURRING PROBLEM. WE MODELED THE DEVELOPMENT OF RESISTANCE TO THE BTK INHIBITOR IBRUTINIB IN THE ACTIVATED B-CELL (ABC) SUBTYPE OF DIFFUSE LARGE B-CELL LYMPHOMA, WHICH RELIES ON CHRONIC ACTIVE BCR SIGNALING FOR SURVIVAL. THE PRIMARY MODE OF RESISTANCE WAS EPIGENETIC, DRIVEN IN PART BY THE TRANSCRIPTION FACTOR TCF4. THE RESULTANT PHENOTYPIC SHIFT ALTERED BCR SIGNALING SUCH THAT THE GTPASE RAC2 SUBSTITUTED FOR BTK IN THE ACTIVATION OF PHOSPHOLIPASE CGAMMA2, THEREBY SUSTAINING NF-KAPPAB ACTIVITY. THE INTERACTION OF RAC2 WITH PHOSPHOLIPASE CGAMMA2 WAS ALSO INCREASED IN CHRONIC LYMPHOCYTIC LEUKEMIA CELLS FROM PATIENTS WITH PERSISTENT OR PROGRESSIVE DISEASE ON BTK INHIBITOR TREATMENT. WE IDENTIFIED CLINICALLY AVAILABLE DRUGS THAT CAN TREAT EPIGENETIC IBRUTINIB RESISTANCE, SUGGESTING COMBINATION THERAPEUTIC STRATEGIES. SIGNIFICANCE: IN DIFFUSE LARGE B-CELL LYMPHOMA, WE SHOW THAT PRIMARY RESISTANCE TO BTK INHIBITORS IS DUE TO EPIGENETIC RATHER THAN GENETIC CHANGES THAT CIRCUMVENT THE BTK BLOCKADE. WE ALSO OBSERVED THIS RESISTANCE MECHANISM IN CHRONIC LYMPHOCYTIC LEUKEMIA, SUGGESTING THAT EPIGENETIC ALTERATIONS MAY CONTRIBUTE MORE TO BTK INHIBITOR RESISTANCE THAN CURRENTLY THOUGHT.SEE RELATED COMMENTARY BY PASQUALUCCI, P. 555. THIS ARTICLE IS HIGHLIGHTED IN THE IN THIS ISSUE FEATURE, P. 549. 2021 4 1380 33 DEVELOPMENTAL SUBTYPES ASSESSED BY DNA METHYLATION-IPLEX FORECAST THE NATURAL HISTORY OF CHRONIC LYMPHOCYTIC LEUKEMIA. ALTERATIONS IN GLOBAL DNA METHYLATION PATTERNS ARE A MAJOR HALLMARK OF CANCER AND REPRESENT ATTRACTIVE BIOMARKERS FOR PERSONALIZED RISK STRATIFICATION. CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) RISK STRATIFICATION STUDIES TYPICALLY FOCUS ON TIME TO FIRST TREATMENT (TTFT), TIME TO PROGRESSION (TTP) AFTER TREATMENT, AND OVERALL SURVIVAL (OS). WHEREAS TTFT RISK STRATIFICATION REMAINS SIMILAR OVER TIME, TTP AND OS HAVE CHANGED DRAMATICALLY WITH THE INTRODUCTION OF TARGETED THERAPIES, SUCH AS THE BRUTON TYROSINE KINASE INHIBITOR IBRUTINIB. WE HAVE SHOWN THAT GENOME-WIDE DNA METHYLATION PATTERNS IN CLL ARE STRONGLY ASSOCIATED WITH PHENOTYPIC DIFFERENTIATION AND PATIENT OUTCOMES. HERE, WE DEVELOPED A NOVEL ASSAY, TERMED METHYLATION-IPLEX (ME-IPLEX), FOR HIGH-THROUGHPUT QUANTIFICATION OF TARGETED PANELS OF SINGLE CYTOSINE GUANINE DINUCLEOTIDES FROM MULTIPLE INDEPENDENT LOCI. ME-IPLEX WAS USED TO CLASSIFY CLL SAMPLES INTO 1 OF 3 KNOWN EPIGENETIC SUBTYPES (EPITYPES). WE EXAMINED THE IMPACT OF EPITYPE IN 1286 CLL PATIENTS FROM 4 INDEPENDENT COHORTS REPRESENTING A COMPREHENSIVE VIEW OF CLL DISEASE COURSE AND THERAPIES. WE FOUND THAT EPITYPE SIGNIFICANTLY PREDICTED TTFT AND OS AMONG NEWLY DIAGNOSED CLL PATIENTS. ADDITIONALLY, EPITYPE PREDICTED TTP AND OS WITH 2 COMMON CLL THERAPIES: CHEMOIMMUNOTHERAPY AND IBRUTINIB. EPITYPE RETAINED SIGNIFICANCE AFTER STRATIFYING BY BIOLOGICALLY RELATED BIOMARKERS, IMMUNOGLOBULIN HEAVY CHAIN MUTATIONAL STATUS, AND ZAP70 EXPRESSION, AS WELL AS OTHER COMMON PROGNOSTIC MARKERS. FURTHERMORE, AMONG SEVERAL BIOLOGICAL TRAITS ENRICHED BETWEEN EPITYPES, WE FOUND HIGHLY BIASED IMMUNOGENETIC FEATURES, INCLUDING IGLV3-21 USAGE IN THE POORLY CHARACTERIZED INTERMEDIATE-PROGRAMMED CLL EPITYPE. IN SUMMARY, ME-IPLEX IS AN ELEGANT METHOD TO ASSESS EPIGENETIC SIGNATURES, INCLUDING ROBUST CLASSIFICATION OF CLL EPITYPES THAT INDEPENDENTLY STRATIFY PATIENT RISK AT DIAGNOSIS AND TIME OF TREATMENT. 2019 5 557 29 B-CELL ANTIGEN RECEPTOR SIGNALING IN CHRONIC LYMPHOCYTIC LEUKEMIA: THERAPEUTIC TARGETS AND TRANSLATIONAL OPPORTUNITIES. B-CELL CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) IS CHARACTERIZED BY CLONALLY EXPANDED AND MOLECULARLY HETEROGENEOUS POPULATIONS OF B LYMPHOCYTES WITH IMPAIRED APOPTOTIC MECHANISMS. THIS OCCURS AS A RESULT OF MULTIPLE GENETIC AND EPIGENETIC ABNORMALITIES, INCLUDING CHROMOSOMAL ABERRATIONS AND ENHANCER REGION HYPOMETHYLATION, OFTEN IMPINGING ON INTRACELLULAR SIGNALING PATHWAYS THAT ARE ESSENTIAL TO NORMAL B-CELL ACTIVATION, PROLIFERATION, AND SURVIVAL. THE B-CELL ANTIGEN RECEPTOR (BCR) SIGNALING IS ONE SUCH PATHWAY USURPED BY MALIGNANT B CELLS, AS EXEMPLIFIED BY THE EARLY PHASE CLINICAL SUCCESS ACHIEVED BY SMALL-MOLECULE AGENTS TARGETING KEY PLAYERS INVOLVED IN THE PATHWAY. SUCH NEW TARGETED AGENTS, INCLUDING THOSE THAT INHIBIT THE FUNCTION OF SPLEEN TYROSINE KINASE (SYK), BRUTON'S TYROSINE KINASE (BTK), PHOSPHATIDYLINOSITOL 3-KINASES (PI3K), AND B-CELL LYMPHOMA 2 (BCL-2), ALONG WITH THE CURRENT STANDARD THERAPY COMPRISING CHEMO-IMMUNOTHERAPIES WITH OR WITHOUT B-CELL DEPLETING BIOLOGIC AGENT RITUXIMAB (ANTI-CD20 MONOCLONAL ANTIBODY), SHOULD EXPAND THE ARMAMENTARIUM FOR CLL THERAPY. WE REVIEW THE THERAPEUTIC AGENTS CURRENTLY IN CLINICAL DEVELOPMENT WHICH TARGET DIFFERENT EFFECTORS OF THE MALIGNANT BCR SIGNALING, AND DISCUSS THEIR OVERLAPPING AND DISCRIMINATING TRANSLATIONAL OPPORTUNITIES IN THE CONTEXT OF CLL TREATMENT. 2013 6 5691 34 SILENCING OF HDAC6 AS A THERAPEUTIC TARGET IN CHRONIC LYMPHOCYTIC LEUKEMIA. ALTHOUGH THE TREATMENT PARADIGM FOR CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) IS RAPIDLY CHANGING, THE DISEASE REMAINS INCURABLE, EXCEPT WITH ALLOGENEIC BONE MARROW TRANSPLANTATION, AND RESISTANCE, RELAPSED DISEASE, AND PARTIAL RESPONSES PERSIST AS SIGNIFICANT CHALLENGES. RECENT STUDIES HAVE UNCOVERED ROLES FOR EPIGENETIC MODIFICATION IN THE REGULATION OF MECHANISMS CONTRIBUTING TO MALIGNANT PROGRESSION OF CLL B CELLS. HOWEVER, THE EXTENT TO WHICH EPIGENETIC MODIFIERS CAN BE TARGETED FOR THERAPEUTIC BENEFIT IN CLL PATIENTS REMAINS POORLY EXPLORED. WE REPORT FOR THE FIRST TIME THAT EXPRESSION OF EPIGENETIC MODIFIER HISTONE DEACETYLASE 6 (HDAC6) IS UPREGULATED IN CLL PATIENT SAMPLES, CELL LINES, AND EUTCL1 TRANSGENIC MOUSE MODELS COMPARED WITH HDAC6 IN NORMAL CONTROLS. GENETIC SILENCING OF HDAC6 CONFERRED SURVIVAL BENEFIT IN EUTCL1 MICE. ADMINISTRATION OF ISOFORM-SPECIFIC HDAC6 INHIBITOR ACY738 IN THE EUTCL1 AGING AND ADOPTIVE TRANSFER MODELS DETERRED PROLIFERATION OF CLL B CELLS, DELAYED DISEASE ONSET VIA DISRUPTION OF B-CELL RECEPTOR SIGNALING, AND SENSITIZED CLL B CELLS TO APOPTOSIS. FURTHERMORE, COADMINISTRATION OF ACY738 AND IBRUTINIB DISPLAYED SYNERGISTIC CELL KILL AGAINST CLL CELL LINES AND IMPROVED OVERALL SURVIVAL COMPARED WITH EITHER SINGLE AGENT IN VIVO. THESE RESULTS DEMONSTRATE FOR THE FIRST TIME THE THERAPEUTIC EFFICACY OF SELECTIVE HDAC6 INHIBITION IN PRECLINICAL CLL MODELS AND SUGGEST A RATIONALE FOR THE CLINICAL DEVELOPMENT OF HDAC6 INHIBITORS FOR CLL TREATMENT, EITHER ALONE OR IN COMBINATION WITH BRUTON TYROSINE KINASE INHIBITION. 2018 7 5243 22 PROGNOSTIC IMPACT OF EPIGENETIC CLASSIFICATION IN CHRONIC LYMPHOCYTIC LEUKEMIA: THE CASE OF SUBSET #2. BASED ON THE METHYLATION STATUS OF 5 SINGLE CPG SITES, A NOVEL EPIGENETIC CLASSIFICATION OF CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) WAS RECENTLY PROPOSED, CLASSIFYING CLL PATIENTS INTO 3 CLINICO-BIOLOGICAL SUBGROUPS WITH DIFFERENT OUTCOME, TERMED MEMORY LIKE CLL (M-CLL), NAIVE LIKE CLL (N-CLL), AND A THIRD INTERMEDIATE CLL SUBGROUP (I-CLL). WHILE M-CLL AND N-CLL PATIENTS AT LARGE CORRESPONDED TO PATIENTS CARRYING MUTATED AND UNMUTATED IGHV GENES, RESPECTIVELY, LIMITED INFORMATION EXISTS REGARDING THE LESS DEFINED I-CLL GROUP. USING PYROSEQUENCING, WE INVESTIGATED THE PROGNOSTIC IMPACT OF THE PROPOSED 5 CPG SIGNATURE IN A WELL-CHARACTERIZED CLL COHORT (135 CASES), INCLUDING IGHV-MUTATED AND UNMUTATED PATIENTS AS WELL AS CLINICALLY AGGRESSIVE STEREOTYPED SUBSET #2 PATIENTS. OVERALL, WE CONFIRMED THE SIGNATURE'S ASSOCIATION WITH ESTABLISHED PROGNOSTIC MARKERS. MOREOVER, IN THE PRESENCE OF THE IGHV MUTATIONAL STATUS, THE EPIGENETIC SIGNATURE REMAINED INDEPENDENTLY ASSOCIATED WITH BOTH TIME-TO-FIRST-TREATMENT AND OVERALL SURVIVAL IN MULTIVARIATE ANALYSES. AS A PRIME FINDING, WE OBSERVED THAT SUBSET #2 PATIENTS WERE PREDOMINANTLY CLASSIFIED AS I-CLL, PROBABLY REFLECTING THEIR BORDERLINE IGHV MUTATIONAL STATUS (97-99% GERMLINE IDENTITY), THOUGH HAVING A SIMILARLY POOR PROGNOSIS AS N-CLL PATIENTS. IN SUMMARY, WE VALIDATED THE EPIGENETIC CLASSIFIER AS AN INDEPENDENT FACTOR IN CLL PROGNOSTICATION AND PROVIDE FURTHER EVIDENCE THAT SUBSET #2 IS A MEMBER OF THE I-CLL GROUP, HENCE SUPPORTING THE EXISTENCE OF A THIRD, INTERMEDIATE EPIGENETIC SUBGROUP. 2016 8 1333 30 DEREGULATION AND EPIGENETIC MODIFICATION OF BCL2-FAMILY GENES CAUSE RESISTANCE TO VENETOCLAX IN HEMATOLOGIC MALIGNANCIES. THE BCL2 INHIBITOR VENETOCLAX HAS BEEN APPROVED TO TREAT DIFFERENT HEMATOLOGICAL MALIGNANCIES. BECAUSE THERE IS NO COMMON GENETIC ALTERATION CAUSING RESISTANCE TO VENETOCLAX IN CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) AND B-CELL LYMPHOMA, WE ASKED IF EPIGENETIC EVENTS MIGHT BE INVOLVED IN VENETOCLAX RESISTANCE. THEREFORE, WE EMPLOYED WHOLE-EXOME SEQUENCING, METHYLATED DNA IMMUNOPRECIPITATION SEQUENCING, AND GENOME-WIDE CLUSTERED REGULARLY INTERSPACED SHORT PALINDROMIC REPEATS (CRISPR)/CRISPR-ASSOCIATED PROTEIN 9 SCREENING TO INVESTIGATE VENETOCLAX RESISTANCE IN AGGRESSIVE LYMPHOMA AND HIGH-RISK CLL PATIENTS. WE IDENTIFIED A REGULATORY CPG ISLAND WITHIN THE PUMA PROMOTER THAT IS METHYLATED UPON VENETOCLAX TREATMENT, MEDIATING PUMA DOWNREGULATION ON TRANSCRIPT AND PROTEIN LEVEL. PUMA EXPRESSION AND SENSITIVITY TOWARD VENETOCLAX CAN BE RESTORED BY INHIBITION OF METHYLTRANSFERASES. WE CAN DEMONSTRATE THAT LOSS OF PUMA RESULTS IN METABOLIC REPROGRAMMING WITH HIGHER OXIDATIVE PHOSPHORYLATION AND ADENOSINE TRIPHOSPHATE PRODUCTION, RESEMBLING THE METABOLIC PHENOTYPE THAT IS SEEN UPON VENETOCLAX RESISTANCE. ALTHOUGH PUMA LOSS IS SPECIFIC FOR ACQUIRED VENETOCLAX RESISTANCE BUT NOT FOR ACQUIRED MCL1 RESISTANCE AND IS NOT SEEN IN CLL PATIENTS AFTER CHEMOTHERAPY-RESISTANCE, BAX IS ESSENTIAL FOR SENSITIVITY TOWARD BOTH VENETOCLAX AND MCL1 INHIBITION. AS WE FOUND LOSS OF BAX IN RICHTER'S SYNDROME PATIENTS AFTER VENETOCLAX FAILURE, WE DEFINED BAX-MEDIATED APOPTOSIS TO BE CRITICAL FOR DRUG RESISTANCE BUT NOT FOR DISEASE PROGRESSION OF CLL INTO AGGRESSIVE DIFFUSE LARGE B-CELL LYMPHOMA IN VIVO. A COMPOUND SCREEN REVEALED TRAIL-MEDIATED APOPTOSIS AS A TARGET TO OVERCOME BAX DEFICIENCY. FURTHERMORE, ANTIBODY OR CAR T CELLS ELIMINATED VENETOCLAX RESISTANT LYMPHOMA CELLS, PAVING A CLINICALLY APPLICABLE WAY TO OVERCOME VENETOCLAX RESISTANCE. 2022 9 6390 21 THE ROLE OF THE GENETIC ABNORMALITIES, EPIGENETIC AND MICRORNA IN THE PROGNOSIS OF CHRONIC LYMPHOCYTIC LEUKEMIA. CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) IS INCREASED PROLIFERATION OF B-CELLS WITH PERIPHERAL BLOOD AND BONE MARROW INVOLVEMENT, WHICH IS USUALLY OBSERVED IN OLDER PEOPLE. GENETIC MUTATIONS, EPIGENETIC CHANGES AND MIRS PLAY A ROLE IN CLL PATHOGENESIS. DEL 11Q, DEL L17Q, DEL 6Q, TRISOMY 12, P53 AND IGVH MUTATIONS ARE THE MOST IMPORTANT GENETIC CHANGES IN CLL. DELETION OF MIR-15A AND MIR-16A CAN INCREASE BCL2 GENE EXPRESSION, MIR-29 AND MIR-181 DELETIONS DECREASE THE EXPRESSION OF TCL1, AND MIR-146A DELETION PREVENTS TUMOR METASTASIS. EPIGENETIC CHANGES SUCH AS HYPO- AND HYPERMETHYLATION, UBIQUITINATION, HYPO- AND HYPERACETYLATION OF GENE PROMOTERS INVOLVED IN CLL PATHOGENESIS CAN ALSO PLAY A ROLE IN CLL. EXPRESSION OF CD38 AND ZAP70, PRESENCE OR ABSENCE OF MUTATION IN IGVH AND P53 MUTATION ARE AMONG THE FACTORS INVOLVED IN CLL PROGNOSIS. USE OF MONOCLONAL ANTIBODIES AGAINST SURFACE MARKERS OF B-CELLS LIKE ANTI-CD20 AS WELL AS TYROSINE KINASE INHIBITORS ARE THE MOST IMPORTANT THERAPEUTIC APPROACHES FOR CLL. 2018 10 5462 24 RESEARCH PROGRESS ON EPIGENETICS OF SMALL B-CELL LYMPHOMA. SMALL B-CELL LYMPHOMA IS THE CLASSIFICATION OF B-CELL CHRONIC LYMPHOPROLIFERATIVE DISORDERS THAT INCLUDE CHRONIC LYMPHOCYTIC LEUKAEMIA/SMALL LYMPHOCYTIC LYMPHOMA, FOLLICULAR LYMPHOMA, MANTLE CELL LYMPHOMA, MARGINAL ZONE LYMPHOMA, LYMPHOPLASMACYTIC LYMPHOMA/WALDENSTROM MACROGLOBULINEMIA. THE CLINICAL PRESENTATION IS SOMEWHAT HETEROGENEOUS, AND ITS OCCURRENCE AND DEVELOPMENT MECHANISMS ARE NOT YET PRECISE AND MAY INVOLVE EPIGENETIC CHANGES. EPIGENETIC ALTERATIONS MAINLY INCLUDE DNA METHYLATION, HISTONE MODIFICATION, AND NON-CODING RNA, WHICH ARE ESSENTIAL FOR GENETIC DETECTION, EARLY DIAGNOSIS, AND ASSESSMENT OF TREATMENT RESISTANCE IN SMALL B-CELL LYMPHOMA. AS CHRONIC LYMPHOCYTIC LEUKEMIA/SMALL LYMPHOCYTIC LYMPHOMA HAS ALREADY BEEN REPORTED IN THE LITERATURE, THIS ARTICLE FOCUSES ON SMALL B-CELL LYMPHOMAS SUCH AS FOLLICULAR LYMPHOMA, MANTLE CELL LYMPHOMA, MARGINAL ZONE LYMPHOMA, AND WALDENSTROM MACROGLOBULINEMIA. IT DISCUSSES RECENT DEVELOPMENTS IN EPIGENETIC RESEARCH TO DIAGNOSE AND TREAT THIS GROUP OF LYMPHOMAS. THIS REVIEW PROVIDES NEW IDEAS FOR THE TREATMENT AND PROGNOSIS ASSESSMENT OF SMALL B-CELL LYMPHOMA BY EXPLORING THE CONNECTION BETWEEN SMALL B-CELL LYMPHOMA AND EPIGENETICS. 2022 11 1581 21 DNA METHYLATION PROFILES IN CHRONIC LYMPHOCYTIC LEUKEMIA PATIENTS TREATED WITH CHEMOIMMUNOTHERAPY. BACKGROUND: IN ORDER TO GAIN INSIGHT INTO THE CONTRIBUTION OF DNA METHYLATION TO DISEASE PROGRESSION OF CHRONIC LYMPHOCYTIC LEUKEMIA (CLL), USING 450K ILLUMINA ARRAYS, WE DETERMINED THE DNA METHYLATION PROFILES IN PAIRED PRE-TREATMENT/RELAPSE SAMPLES FROM 34 CLL PATIENTS TREATED WITH CHEMOIMMUNOTHERAPY, MOSTLY (N = 31) WITH THE FLUDARABINE-CYCLOPHOSPHAMIDE-RITUXIMAB (FCR) REGIMEN. RESULTS: THE EXTENT OF IDENTIFIED CHANGES IN CLL CELLS VERSUS MEMORY B CELLS FROM HEALTHY DONORS WAS TERMED "EPIGENETIC BURDEN" (EB) WHEREAS THE NUMBER OF CHANGES BETWEEN THE PRE-TREATMENT VERSUS THE RELAPSE SAMPLE WAS TERMED "RELAPSE CHANGES" (RC). SIGNIFICANT (P < 0.05) ASSOCIATIONS WERE IDENTIFIED BETWEEN (I) HIGH EB AND SHORT TIME-TO-FIRST-TREATMENT (TTFT); AND, (II) FEW RCS AND SHORT TIME-TO-RELAPSE. BOTH THE EB AND THE RC CLUSTERED IN SPECIFIC GENOMIC REGIONS AND CHROMATIN STATES, INCLUDING REGULATORY REGIONS CONTAINING BINDING SITES OF TRANSCRIPTION FACTORS IMPLICATED IN B CELL AND CLL BIOLOGY. CONCLUSIONS: OVERALL, WE SHOW THAT DNA METHYLATION IN CLL FOLLOWS DIFFERENT DYNAMICS IN RESPONSE TO CHEMOIMMUNOTHERAPY. THESE EPIGENETIC ALTERATIONS WERE LINKED WITH SPECIFIC CLINICAL AND BIOLOGICAL FEATURES. 2019 12 955 27 CHRONIC MYELOID LEUKEMIA: MECHANISMS OF BLASTIC TRANSFORMATION. THE BCR-ABL1 ONCOPROTEIN TRANSFORMS PLURIPOTENT HSCS AND INITIATES CHRONIC MYELOID LEUKEMIA (CML). PATIENTS WITH EARLY PHASE (ALSO KNOWN AS CHRONIC PHASE [CP]) DISEASE USUALLY RESPOND TO TREATMENT WITH ABL TYROSINE KINASE INHIBITORS (TKIS), ALTHOUGH SOME PATIENTS WHO RESPOND INITIALLY LATER BECOME RESISTANT. IN MOST PATIENTS, TKIS REDUCE THE LEUKEMIA CELL LOAD SUBSTANTIALLY, BUT THE CELLS FROM WHICH THE LEUKEMIA CELLS ARE DERIVED DURING CP (SO-CALLED LEUKEMIA STEM CELLS [LSCS]) ARE INTRINSICALLY INSENSITIVE TO TKIS AND SURVIVE LONG TERM. LSCS OR THEIR PROGENY CAN ACQUIRE ADDITIONAL GENETIC AND/OR EPIGENETIC CHANGES THAT CAUSE THE LEUKEMIA TO TRANSFORM FROM CP TO A MORE ADVANCED PHASE, WHICH HAS BEEN SUBCLASSIFIED AS EITHER ACCELERATED PHASE OR BLASTIC PHASE DISEASE. THE LATTER RESPONDS POORLY TO TREATMENT AND IS USUALLY FATAL. HERE, WE DISCUSS WHAT IS KNOWN ABOUT THE MOLECULAR MECHANISMS LEADING TO BLASTIC TRANSFORMATION OF CML AND PROPOSE SOME NOVEL THERAPEUTIC APPROACHES. 2010 13 4446 27 MOLECULAR MAP OF CHRONIC LYMPHOCYTIC LEUKEMIA AND ITS IMPACT ON OUTCOME. RECENT ADVANCES IN CANCER CHARACTERIZATION HAVE CONSISTENTLY REVEALED MARKED HETEROGENEITY, IMPEDING THE COMPLETION OF INTEGRATED MOLECULAR AND CLINICAL MAPS FOR EACH MALIGNANCY. HERE, WE FOCUS ON CHRONIC LYMPHOCYTIC LEUKEMIA (CLL), A B CELL NEOPLASM WITH VARIABLE NATURAL HISTORY THAT IS CONVENTIONALLY CATEGORIZED INTO TWO SUBTYPES DISTINGUISHED BY EXTENT OF SOMATIC MUTATIONS IN THE HEAVY-CHAIN VARIABLE REGION OF IMMUNOGLOBULIN GENES (IGHV). TO BUILD THE 'CLL MAP,' WE INTEGRATED GENOMIC, TRANSCRIPTOMIC AND EPIGENOMIC DATA FROM 1,148 PATIENTS. WE IDENTIFIED 202 CANDIDATE GENETIC DRIVERS OF CLL (109 NEW) AND REFINED THE CHARACTERIZATION OF IGHV SUBTYPES, WHICH REVEALED DISTINCT GENOMIC LANDSCAPES AND LEUKEMOGENIC TRAJECTORIES. DISCOVERY OF NEW GENE EXPRESSION SUBTYPES FURTHER SUBCATEGORIZED THIS NEOPLASM AND PROVED TO BE INDEPENDENT PROGNOSTIC FACTORS. CLINICAL OUTCOMES WERE ASSOCIATED WITH A COMBINATION OF GENETIC, EPIGENETIC AND GENE EXPRESSION FEATURES, FURTHER ADVANCING OUR PROGNOSTIC PARADIGM. OVERALL, THIS WORK REVEALS FRESH INSIGHTS INTO CLL ONCOGENESIS AND PROGNOSTICATION. 2022 14 2402 30 EPIGENETIC REPROGRAMMING SENSITIZES CML STEM CELLS TO COMBINED EZH2 AND TYROSINE KINASE INHIBITION. A MAJOR OBSTACLE TO CURING CHRONIC MYELOID LEUKEMIA (CML) IS RESIDUAL DISEASE MAINTAINED BY TYROSINE KINASE INHIBITOR (TKI)-PERSISTENT LEUKEMIC STEM CELLS (LSC). THESE ARE BCR-ABL1 KINASE INDEPENDENT, REFRACTORY TO APOPTOSIS, AND SERVE AS A RESERVOIR TO DRIVE RELAPSE OR TKI RESISTANCE. WE DEMONSTRATE THAT POLYCOMB REPRESSIVE COMPLEX 2 IS MISREGULATED IN CHRONIC PHASE CML LSCS. THIS IS ASSOCIATED WITH EXTENSIVE REPROGRAMMING OF H3K27ME3 TARGETS IN LSCS, THUS SENSITIZING THEM TO APOPTOSIS UPON TREATMENT WITH AN EZH2-SPECIFIC INHIBITOR (EZH2I). EZH2I DOES NOT IMPAIR NORMAL HEMATOPOIETIC STEM CELL SURVIVAL. STRIKINGLY, TREATMENT OF PRIMARY CML CELLS WITH EITHER EZH2I OR TKI ALONE CAUSED SIGNIFICANT UPREGULATION OF H3K27ME3 TARGETS, AND COMBINED TREATMENT FURTHER POTENTIATED THESE EFFECTS AND RESULTED IN SIGNIFICANT LOSS OF LSCS COMPARED TO TKI ALONE, IN VITRO, AND IN LONG-TERM BONE MARROW MURINE XENOGRAFTS. OUR FINDINGS POINT TO A PROMISING EPIGENETIC-BASED THERAPEUTIC STRATEGY TO MORE EFFECTIVELY TARGET LSCS IN PATIENTS WITH CML RECEIVING TKIS. SIGNIFICANCE: IN CML, TKI-PERSISTENT LSCS REMAIN AN OBSTACLE TO CURE, AND APPROACHES TO ERADICATE THEM REMAIN A SIGNIFICANT UNMET CLINICAL NEED. WE DEMONSTRATE THAT EZH2 AND H3K27ME3 REPROGRAMMING IS IMPORTANT FOR LSC SURVIVAL, BUT RENDERS LSCS SENSITIVE TO THE COMBINED EFFECTS OF EZH2I AND TKI. THIS REPRESENTS A NOVEL APPROACH TO MORE EFFECTIVELY TARGET LSCS IN PATIENTS RECEIVING TKI TREATMENT. CANCER DISCOV; 6(11); 1248-57. (C)2016 AACR.SEE RELATED ARTICLE BY XIE ET AL., P. 1237THIS ARTICLE IS HIGHLIGHTED IN THE IN THIS ISSUE FEATURE, P. 1197. 2016 15 6762 21 ZAP70 IN CHRONIC LYMPHOCYTIC LEUKAEMIA. THE PROTEIN TYROSINE KINASE ZETA-CHAIN ASSOCIATED PROTEIN KINASE (ZAP70), NORMALLY EXPRESSED IN T CELLS AND A SUBSET OF B CELLS, IS SOLELY EXPRESSED IN POOR PROGNOSIS CHRONIC LYMPHOCYTIC LEUKAEMIA AND IMPLICATED IN ENHANCED B CELL RECEPTOR SIGNALLING. AS A RESULT, THE EXPRESSION OF THIS PROTEIN PROVIDES AN IDEAL PROGNOSTIC MARKER FOR THE DISEASE. A PREVIOUS STUDY HAS SHOWN DIFFERENTIAL CPG METHYLATION OF A 5' REGION OF ZAP70 IN LEUKAEMIC LYMPHOID CELLS, ALTHOUGH NO FURTHER EPIGENETIC STUDIES HAVE BEEN REPORTED. FURTHER INVESTIGATION INTO THE EXPRESSION OF ZAP70 MAY THEREFORE PROVIDE TARGETS FOR THERAPIES. 2008 16 5703 32 SINGLE-CELL MULTIOMICS REVEAL THE SCALE OF MULTILAYERED ADAPTATIONS ENABLING CLL RELAPSE DURING VENETOCLAX THERAPY. VENETOCLAX (VEN) INHIBITS THE PROSURVIVAL PROTEIN BCL2 TO INDUCE APOPTOSIS AND IS A STANDARD THERAPY FOR CHRONIC LYMPHOCYTIC LEUKEMIA (CLL), DELIVERING HIGH COMPLETE REMISSION RATES AND PROLONGED PROGRESSION-FREE SURVIVAL IN RELAPSED CLL BUT WITH EVENTUAL LOSS OF EFFICACY. A SPECTRUM OF SUBCLONAL GENETIC CHANGES ASSOCIATED WITH VEN RESISTANCE HAS NOW BEEN DESCRIBED. TO FULLY UNDERSTAND CLINICAL RESISTANCE TO VEN, WE COMBINED SINGLE-CELL SHORT- AND LONG-READ RNA-SEQUENCING TO REVEAL THE PREVIOUSLY UNAPPRECIATED SCALE OF GENETIC AND EPIGENETIC CHANGES UNDERPINNING ACQUIRED VEN RESISTANCE. THESE APPEAR TO BE MULTILAYERED. ONE LAYER COMPRISES CHANGES IN THE BCL2 FAMILY OF APOPTOSIS REGULATORS, ESPECIALLY THE PROSURVIVAL FAMILY MEMBERS. THIS INCLUDES PREVIOUSLY DESCRIBED MUTATIONS IN BCL2 AND AMPLIFICATION OF THE MCL1 GENE BUT IS HETEROGENEOUS ACROSS AND WITHIN INDIVIDUAL PATIENT LEUKEMIAS. CHANGES IN THE PROAPOPTOTIC GENES ARE NOTABLY UNCOMMON, EXCEPT FOR SINGLE CASES WITH SUBCLONAL LOSSES OF BAX OR NOXA. MUCH MORE PROMINENT WAS UNIVERSAL MCL1 GENE UPREGULATION. THIS WAS DRIVEN BY AN OVERLYING LAYER OF EMERGENT NF-KAPPAB (NUCLEAR FACTOR KAPPA B) ACTIVATION, WHICH PERSISTED IN CIRCULATING CELLS DURING VEN THERAPY. WE DISCOVERED THAT MCL1 COULD BE A DIRECT TRANSCRIPTIONAL TARGET OF NF-KAPPAB. BOTH THE SWITCH TO ALTERNATIVE PROSURVIVAL FACTORS AND NF-KAPPAB ACTIVATION LARGELY DISSIPATE FOLLOWING VEN DISCONTINUATION. OUR STUDIES REVEAL THE EXTENT OF PLASTICITY OF CLL CELLS IN THEIR ABILITY TO EVADE VEN-INDUCED APOPTOSIS. IMPORTANTLY, THESE FINDINGS PINPOINT NEW APPROACHES TO CIRCUMVENT VEN RESISTANCE AND PROVIDE A SPECIFIC BIOLOGICAL JUSTIFICATION FOR THE STRATEGY OF VEN DISCONTINUATION ONCE A MAXIMAL RESPONSE IS ACHIEVED RATHER THAN MAINTAINING LONG-TERM SELECTIVE PRESSURE WITH THE DRUG. 2022 17 941 31 CHRONIC LYMPHOCYTIC LEUKEMIA B-CELL NORMAL CELLULAR COUNTERPART: CLUES FROM A FUNCTIONAL PERSPECTIVE. CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) IS CHARACTERIZED BY THE CLONAL EXPANSION OF SMALL MATURE-LOOKING CD19+ CD23+ CD5+ B-CELLS THAT ACCUMULATE IN THE BLOOD, BONE MARROW, AND LYMPHOID ORGANS. TO DATE, NO CONSENSUS HAS BEEN REACHED CONCERNING THE NORMAL CELLULAR COUNTERPART OF CLL B-CELLS AND SEVERAL B-CELL TYPES HAVE BEEN PROPOSED. CLL B-CELLS HAVE REMARKABLE PHENOTYPIC AND GENE EXPRESSION PROFILE HOMOGENEITY. IN RECENT YEARS, THE MOLECULAR AND CELLULAR BIOLOGY OF CLL HAS BEEN ENRICHED BY SEMINAL INSIGHTS THAT ARE LEADING TO A BETTER UNDERSTANDING OF THE NATURAL HISTORY OF THE DISEASE. IMMUNOPHENOTYPIC AND MOLECULAR APPROACHES (INCLUDING IMMUNOGLOBULIN HEAVY-CHAIN VARIABLE GENE MUTATIONAL STATUS, TRANSCRIPTIONAL AND EPIGENETIC PROFILING) COMPARING THE NORMAL B-CELL SUBSET AND CLL B-CELLS PROVIDE SOME NEW INSIGHTS INTO THE NORMAL CELLULAR COUNTERPART. FUNCTIONAL CHARACTERISTICS (INCLUDING ACTIVATION REQUIREMENTS AND PROPENSITY FOR PLASMA CELL DIFFERENTIATION) OF CLL B-CELLS HAVE NOW BEEN INVESTIGATED FOR 50 YEARS. B-CELL SUBSETS DIFFER SUBSTANTIALLY IN TERMS OF THEIR FUNCTIONAL FEATURES. ANALYSIS OF SHARED FUNCTIONAL CHARACTERISTICS MAY REVEAL SIMILARITIES BETWEEN NORMAL B-CELL SUBSETS AND CLL B-CELLS, ALLOWING SPECULATIVE ASSIGNMENT OF A NORMAL CELLULAR COUNTERPART FOR CLL B-CELLS. IN THIS REVIEW, WE SUMMARIZE CURRENT DATA REGARDING PERIPHERAL B-CELL DIFFERENTIATION AND HUMAN B-CELL SUBSETS AND SUGGEST POSSIBILITIES FOR A NORMAL CELLULAR COUNTERPART BASED ON THE FUNCTIONAL CHARACTERISTICS OF CLL B-CELLS. HOWEVER, A DEFINITIVE NORMAL CELLULAR COUNTERPART CANNOT BE ATTRIBUTED ON THE BASIS OF THE AVAILABLE DATA. WE DISCUSS THE FUNCTIONAL CHARACTERISTICS REQUIRED FOR A CELL TO BE LOGICALLY CONSIDERED TO BE THE NORMAL COUNTERPART OF CLL B-CELLS. 2018 18 5666 25 SF3B1-MUTATED CHRONIC LYMPHOCYTIC LEUKEMIA SHOWS EVIDENCE OF NOTCH1 PATHWAY ACTIVATION INCLUDING CD20 DOWNREGULATION. CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) IS CHARACTERIZED BY A LOW CD20 EXPRESSION, IN PART EXPLAINED BY AN EPIGENETIC-DRIVEN DOWNREGULATION TRIGGERED BY MUTATIONS OF THE NOTCH1 GENE. IN THE PRESENT STUDY, BY TAKING ADVANTAGE OF A WIDE AND WELL-CHARACTERIZED CLL COHORT (N=537), WE DEMONSTRATE THAT CD20 EXPRESSION IS DOWNREGULATED IN SF3B1-MUTATED CLL IN AN EXTENT SIMILAR TO NOTCH1-MUTATED CLL. IN FACT, SF3B1-MUTATED CLL CELLS SHOW COMMON FEATURES WITH NOTCH1-MUTATED CLL CELLS, INCLUDING A GENE EXPRESSION PROFILE ENRICHED OF NOTCH1-RELATED GENE SETS AND ELEVATED EXPRESSION OF THE ACTIVE INTRACYTOPLASMIC NOTCH1. ACTIVATION OF THE NOTCH1 SIGNALING AND DOWN-REGULATION OF SURFACE CD20 IN SF3B1-MUTATED CLL CELLS CORRELATE WITH OVER-EXPRESSION OF AN ALTERNATIVELY SPLICED FORM OF DVL2, A COMPONENT OF THE WNT PATHWAY AND NEGATIVE REGULATOR OF THE NOTCH1 PATHWAY. THESE FINDINGS ARE CONFIRMED BY SEPARATELY ANALYZING THE CD20-DIM AND CD20-BRIGHT CELL FRACTIONS FROM SF3B1-MUTATED CASES AS WELL AS BY DVL2 KNOCK-OUT EXPERIMENTS IN CLL-LIKE CELL MODELS. ALTOGETHER, THE CLINICAL AND BIOLOGICAL FEATURES THAT CHARACTERIZE NOTCH1-MUTATED CLL MAY ALSO BE RECAPITULATED IN SF3B1-MUTATED CLL, CONTRIBUTING TO EXPLAIN THE POOR PROGNOSIS OF THIS CLL SUBSET AND PROVIDING THE RATIONALE FOR EXPANDING NOVEL AGENTS-BASED THERAPIES TO SF3B1-MUTATED CLL. 2021 19 5512 25 RICHTER SYNDROME IN CHRONIC LYMPHOCYTIC LEUKEMIA: UPDATES ON BIOLOGY, CLINICAL FEATURES AND THERAPY. RICHTER SYNDROME (RS) OR RICHTER TRANSFORMATION IS THE DEVELOPMENT OF SECONDARY AGGRESSIVE LYMPHOMA IN THE SETTING OF UNDERLYING CHRONIC LYMPHOCYTIC LEUKEMIA/SMALL LYMPHOCYTIC LYMPHOMA (CLL/SLL). MOST FREQUENTLY CLL TRANSFORMS INTO DIFFUSE LARGE B-CELL LYMPHOMA (DLBCL) (90%) AND RARELY (10%) INTO HODGKIN LYMPHOMA, TERMED HODGKIN VARIANT OF RICHTER SYNDROME (HVRS). RS IS GENERALLY CHARACTERIZED BY AN AGGRESSIVE CLINICAL COURSE AND POOR PROGNOSIS. IN RECENT YEARS, MAJOR ADVANCES HAVE BEEN MADE IN UNDERSTANDING GENETIC EVENTS WHICH RELATE TO THE PROGRESSION OF CLL OR TRANSFORMATION INTO RS. BETTER UNDERSTANDING OF THE MOLECULAR PATHWAYS HAS REVEALED THAT RS IS NOT A SINGLE HOMOGENEOUS ENTITY. THE MAJORITY OF CASES ARE CLONALLY RELATED TO THE ORIGINAL CLL CLONE, WHILE A MINORITY DEVELOP FROM AN UNRELATED CLONE. THIS REVIEW SUMMARIZES NEW DATA RELATING TO THE MOLECULAR BIOLOGY AND THE GENETIC/EPIGENETIC CHANGES OCCURRING DURING RICHTER TRANSFORMATION, AND ALSO CONSIDERS THE CLINICAL FEATURES AND THERAPY FOR BOTH DLBCL-RS AND HODGKIN VARIANT-RS. 2015 20 5030 28 PERSPECTIVES ON PRECISION MEDICINE IN CHRONIC LYMPHOCYTIC LEUKEMIA: TARGETING RECURRENT MUTATIONS-NOTCH1, SF3B1, MYD88, BIRC3. CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) IS HIGHLY HETEROGENEOUS, WITH EXTREMELY VARIABLE CLINICAL COURSE. THE CLINICAL HETEROGENEITY OF CLL REFLECTS DIFFERENCES IN THE BIOLOGY OF THE DISEASE, INCLUDING CHROMOSOMAL ALTERATIONS, SPECIFIC IMMUNOPHENOTYPIC PATTERNS AND SERUM MARKERS. THE APPLICATION OF NEXT-GENERATION SEQUENCING TECHNIQUES HAS DEMONSTRATED THE HIGH GENETIC AND EPIGENETIC HETEROGENEITY IN CLL. THE NOVEL MUTATIONS COULD BE PHARMACOLOGICALLY TARGETED FOR INDIVIDUALIZED APPROACH IN SOME OF THE CLL PATIENTS. POTENTIAL NEUROGENIC LOCUS NOTCH HOMOLOG PROTEIN 1 (NOTCH1) SIGNALLING TARGETING MECHANISMS IN CLL INCLUDE SECRETASE INHIBITORS AND SPECIFIC ANTIBODIES TO BLOCK NOTCH LIGAND/RECEPTOR INTERACTIONS. IN VITRO STUDIES CHARACTERIZING THE EFFECT OF THE SPLICING INHIBITORS RESULTED IN INCREASED APOPTOSIS OF CLL CELLS REGARDLESS OF SPLICING FACTOR 3B SUBUNIT 1 (SF3B1) STATUS. SEVERAL THERAPEUTIC STRATEGIES HAVE BEEN ALSO PROPOSED TO DIRECTLY OR INDIRECTLY INHIBIT THE TOLL-LIKE RECEPTOR/MYELOID DIFFERENTIATION PRIMARY RESPONSE GENE 88 (TLR/MYD88) PATHWAY. ANOTHER POTENTIAL APPROACH IS TARGETING NUCLEAR FACTOR KAPPA-LIGHT-CHAIN-ENHANCER OF ACTIVATED B CELLS (NF-KAPPAB) AND INHIBITION OF THIS PROSURVIVAL PATHWAY. NEWLY DISCOVERED MUTATIONS AND THEIR SIGNALLING PATHWAYS PLAY KEY ROLES IN THE COURSE OF THE DISEASE. THIS OPENS NEW OPPORTUNITIES IN THE MANAGEMENT AND TREATMENT OF CLL. 2021