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Aggressive lymphomasLuca Mazzucchelli

Istituto cantonale di patologia, Locarno

Bellinzona IRB/IOSI, 17.5.2011

Lymphoma subtype frequencies

Histopathology 2011, 58:4-14

DLBCL

DLBCL categories

1. DLBCL specifed by site2. DLBCL with characteristic

histologic, immunophenotypic orgenotypic features

3. DLBCL associated withEBV o HHV8 infection

4. DLBCL, NOS5. Lymphoma non

classifiable

DLBCL

� Common morphologicvariants

� centroblastic� immunoblastic� anaplastic

� Molecular subgroups� Germinal centre B-cell-

like (GCB)� Activated B-cell-like

(ABC)� Unclassified

� Cytogenetic alterations� Bcl2� Bcl6� C-myc

1. DLBCL specified by site2. DLBCL with characteristic

histologic, immunophenotypic orgenotypic features

3. DLBCL associated withEBV o HHV8 infection

4. DLBCL, NOS5. Lymphoma non

classifiable

� 303 DLBCL, all treated with R-CHOP� 35 (14%) with MYC-R� Combination with other rearrangements (BCL2, BCL6)� MYC-R is a strongly adverse prognostic factor (in combination with age and IPI)

J Clin Oncol 2010; 28:3360

Univariate Kaplan-Maier analysis of overall survival in the MYC-R versus non rearranged patients

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� MYC-R occurs in 3-16% of DLBCL

� The presence of a MYC-R isa strong adverse prognosticfactor in CHOP and R-CHOP treated patients

� MYC-R in combination withIPI and patient‘s age accurately predict clinicaloutcome

� The presence of MYC-R cannot be predicted bylymphoma‘s morphology

J Clin Oncol 2010; 28:3360Blood 2009; 114:3533J Clin Pathol 2009; 62:754

MYC oncogene wasdiscovered approximately25 years ago

20’000 published articles

MYC

� Located on chromosome 8q24� Member of a family of genes that includes N-MYC, L-MYC,

and S-MYC� Three exons (exon I is noncoding)� Upon mitogenic stimulation, MYC is rapidly transcribed with

maximum mRNA levels reached within 2 hours� MYC mRNA has an extremely short half-life (10 min)� MYC protein has also a short half-life (25 min)� It is believed to regulate upward of 10% of genes within the

human genomes

MYC oncogenic activation

� Compared to other oncogenes (HRAS) activated by mutations in the coding sequence, there are three more mechanisms of oncogenicactivation: insertional mutagenesis, chromosomal translocation, and gene amplification

MYC deregulationThe control of MYC expression

� Transcriptional control and mRNA turnover� MYC promoter is a key convergence node� Rapid MYC mRNA turnover� Increased MYC mRNA expression and stability in

tumor cells

� Protein expression and regulation� Proliferative stimuli activate specific kinases to

phosphorylate and increase MYC stability

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MYC stability and degradation regulatedby phsphorylation

MYC as a regulator of gene transcription

-COOH

MYC as transcription activator MYC as transcriptional repressor

Target genes

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Target genes Oncogene cooperation

� Cooperation betweenmultiple gene isrequired for cellulartransformation

� Multiple geneticchanges are requiredfor tumors to develop

MYC regulated micro-RNAs MYC

� MYC is a transcription factor controlling the expression of a large set of target genes involved in cell cycle regulation, metabolism, DNA repair, stress response and proteinsynthesis

� MYC is involved in the regulation of miRNA expression� Genomic alterations of the MYC gene include chromosomal

translocations, mutations affecting regulatory and promoterregions, as well as copy number increase

� Most chromosomal breakpoints involving MYC are mediatedby activation induced cytidine deaminase (ACIDA) and not byRAG1/2 gene

Lymphoma Chromosomal Oncogene Mechanism ofType Alteration Involved Oncogene

Activation

Follicular t(14;18)(q32;q21) BCL2 Transcriptionalderegulation

MALT t(11;18)(q21;q21) API2/MALT1 Fusion protein

t(1;14)(p22;q32) BCL10 Transcriptionalderegulation

t(14;18)(q32;q21) MALT1 Transcriptionalderegulation

Mantle cell t(11;14)(q13;q32) BCL1 Transcriptionalderegulation

Burkitt's t(8;14)(q24;q32) c_MYC Transcriptionalderegulation

Chromosomal translocations in B-NHL

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Present in approximately 50% of cases. Translocationsinvolve IG partner genes in the majority of cases, usuallyIGH. Not associated with “double hit” lymphoma

PBL

Present in 35-50% of cases. Translocations rarely involve IGH as a partner gene. Translocations involve IGk, IGλ or non-IG partner genes. Associated with “double hit”lymphoma

BCLU

Present in 7-14% of de novo cases. Usually a secondarygenetic event. Translocations involve IG (70%) and non-IG(30%) partner genes. Associated with “double hit” lymphoma

DLBCL

Present in >90% of cases; Primary genetic event. Translocations involve Ig partner genes only: 85% t(8;14), 15% t(2;8) or t(8;22). Not associated with “double hit”lymphoma

BL

MYC RearrangementLymphoma

Adv Anat Pathol 2011, 18:219-228

Double hit B-cell lymphomas� B-cell lymphomas

characterized by a recurrentchromosomal translocationin combination with a MYC/8q24 breakpoint

� DH lymphomas are rare (0-12%)

� Most DH lymphomas have a BCL2+/MYC+ combination

� There are no unifyingmorphological features of DH-lymphomas

� Most DH lymphomas have a GC phenotype (CD10+, bcl6+, bcl2+, high ki67)

Double hit B-cell lymphomas

� Complex karyotypes� Gene expression profile

intermediate between Burkittlymphoma and DLBCL

� Frequent non IGH partner of MYC

� Median age 51-65 years� Highly aggressive clinical

behaviour� Elevated LDH, bone marrow

and CNS involvement, high IPI score

� Resistent to chemotherapy(median survival of only 0,2-1,5 years)

Aukema SM et al Blood 2010, prepublished online Nov 30

Timing and synergy of translocation in DH lymphomas

Follicular Lymphoma Mantle cell lymphoma

BCL2+/MYC+ DH Lymphoma CCND1/MYC+ DH Lymphoma

Timing and synergy of translocation in DH lymphomas

� BCL2 and CCND1 breakpoints are most likely mediated byRAG1/2 in precursor cells

� Most MYC breakpoints are likely mediated by AICDA in matureB cells (erroneous somatic hypermutation or class switch)

� 5% of FL with BCL2 breakpoints will acquire MYC breakpointduring the course of disease

� Sporadic cases of lymphomas with two clones with different breakpoints have been reported

� Secondary MYC breakpoints affect the Ig light chain whereasprimary MYC breakpoints (BL) affect the Ig haevy chain

� MYC breakpoint is most likely a secondary event in the case of BCL2 or CCND1 breakpoint

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How can the aggressive course of DH lymphomas be explained?

� MYC and BCL2 translocation may be detected in normal B cells

� Follicular lymphomas are often indolent� Adult BL have much more favorable prognosis than DH

lymphomas

BCL2 is anti-apoptoticwithout mediatingproliferative signals

MYC drives cells in active and proliferative stateMature B cells

PROLIFERATIONAPOPTOSIS

Aukema SM et al Blood 2010, prepublished online Nov 30

Cogliatti S et al. Br J Heamatol2006; 134:294 (modified)

Burkittlymphoma

MYC+DLBCL

Intermediatelymphoma

Intermediatelymphoma

Proposed algorithm for highly aggressive lymphomas Useful diagnostic markers for identifying MYCtranslocated lymphomas

� Ruzinova MB et al. Alteredsubcellular localization of c-MYCprotein identifies aggressive B-cell lymphomas harboring a c-MYC translocation. Am J SurgPathol 2010, 34:882

� Rodig SJ et al. The pre-B-cellreceptor associated proteinVpreB3 is a useful diagnosticmarker for identifying c-MYCtranslocated lymphomas. Hematologica 2010;95:2056

Outlooks

� Downstream traget genes that distinguish between physiologic and tumoroginic functions remain to be determinated

� Level of MYC protein influences the development of lymphomas?

� Possible involvement of apoptosis in response to varying degree of MYC activity remains unknown

� Maturation stage of B-cells with MYC-disregulation� Therapeutic targets