Post on 02-Jan-2016
Diagnostically and Prognostically Significant Genetic Alterations in Diffuse Large B-Cell Lymphoma
Friederike Kreisel, MD
Department of Pathology and Immunology
Washington University in St. Louis
Frequency of B-and T-Cell Lymphomas
Diffuse Large B-cellLymphoma
Follicular Lymphoma
Marginal Zone B-cellLymphoma
CLL/SLL
Mantle CellLymphoma
Burkitt Lymphoma
T-cell Lymphomas
Other Types
33%
22.1%9.4%
6.7%
11.7%
6.0%
2.5%
8.6%
Incidence of non-Hodgkin lymphoma (NHL) has increased more than 73% between 1973 and 1991Estimated rate for DLBCL is ~4.68 cases per 100,000 persons/year
Normal B-Cell Differentiation
NEJM 2000, 343;108-117
The Germinal Center
Germinal Center
NEJM 2000, 343;108-117
Lymph node
CD10+/BCL-6+/BCL-2-
Diffuse Large B-Cell Lymphoma
• Usually de novo (primary)
• Transformation from:– CLL/SLL– Follicular lymphoma
• Immunodeficiency is strongest known risk factor
WHO 2008, Tumors of Hematopoietic and Lymphoid Tissues
Diffuse Large B-Cell Lymphoma
• Clinically, morphologically, and genetically heterogenous group with only a subset falling into the WHO subcategories
• 20-30% of DLBCL continue to be defined by their nuclear size only
DLBCL Subcategories (WHO 2008) • Diffuse large B-cell lymphoma, NOS• T-cell/histiocyte rich DLBCL• Primary DLBCL of CNS• Primary cutaneous DLBCL, leg type• EBV positive DLBCL of the elderly• Primary mediastinal (thymic) LBCL• Intravascular LBCL• DLBCL associated with chronic inflammation• Lymphomatoid granulomatosis• ALK-positive LBCL• Plasmablastic lymphoma• LBCL arising in HHV8+ multicentric Castleman’s disease• Primary effusion lymphoma• B-cell lymphoma, unclassifiable
International Prognostic Index (IPI) most
commonly used to predict outcome in DLBCL • Unfavorable variables
– Age >60 years– Poor performance status (ECOG2)– Advanced Ann Arbor stage (III-IV)– Extranodal involvement 2 sites– High serum LDH (>normal)
Risk group Unfavorable variables
All patients Patients60
Low 0 or 1 0
Low/intermediate 2 1
High/intermediate 3 2
High 4 or 5 3
Major Recurring Genetic Events in DLBCL
Genetic Defect Frequency Location
BCL6 35-40% 3q27
BCL2 t(14;18) 13%, amplification 24%
18q21
cMYC 15% 8q24
FAS(CD95) 20% 10q24
Aberrant SHM 45% Genes aberrantly targeted: BCL6,
cMYC, PAX5
TP53 16% 17p
BCL6• Zinc-finger transcription
repressor normally expressed within germinal center (GC) B-cells BCL6 null animals fail to generate GCs in response to antigen
• Constitutive expression of BCL6 might the p53-mediated apoptosis, promoting persistence of malignant clones
Wikipedia
BCL2• Proto-oncogene located at
18q21 that promotes B-cell survival via inhibition of apoptosis and confers chemotherapy resistance
• BCL-2 expression is normally down-regulated in the GC where apoptosis plays a critical role in negative B-cell selection
• t(14;18) fusion gene leading to transcription of levels of BCL2
Wikipedia
Gene Expression Profiling
• Measurement of the activity (expression) of thousands of genes at once relative amount of mRNA expressed provides a global picture of cellular function
Gene Expression Profiling
• Highlight similarities between subsets of DLBCL and normal B cells
• Define robust and highly reproducible DLBCL subtypes with comprehensive transcriptional signatures
• Identify features associated with unfavorable responses to empiric combination chemotherapy
DNA Microarray - Methodology
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+
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DLBCL2
DLBCL1
LYMPHOCHIP
Slides are coated with poly-Lysine, which is positively charged.DNA is negatively charged, so it “sticks” to the slide through ionic inter-action
cDNA is made from different DLBCLtumors
LYMPHOCHIP
DNA Microarray - Methodology
DLBCL2
DLBCL1
LYMPHOCHIP
Both sets of DLBCL cDNA are labelled with different fluorescent tags, in this case red and green
LYMPHOCHIP
DLBCL1
DLBCL2
Gene array lymphochip is incubatedwith the tagged DLBCL cDNAs, whichbind to the matching genes printed on the array
DNA Microarray - Methodology
LYMPHOCHIP
DLBCL1DLBCL2
Since positions of the genes on the DNA array are known, levels of gene expression can be figured out based on color signal.If the gene is only expressed in DLBCL1, the square is red; if the geneis only expressed in DLBCL2, the square is green; if the gene isequally expressed in both DLBCL, the square is yellow.
Gene Expression Profiling in DLBCL (Alizadeh et al., Nature 2000)
Ratio of hybridization of fluorescent experimental mRNA to fluorescent pooledreference mRNA
Gene Expression Profiling in DLBCL (Alizadeh et al., Nature 2000)
a. Hierarchical clustering of DLBCL (orange and blue) and germinal center B cells (black) based on the genes of the germinal center B-cell gene expression signature
b. Discovery of genes that are selectively expressed in GC B-like DLBCL and activated B-like DLBCL based on genes of pan B-cells, germinal center B-cells, and activated B-cells
c. Hierarchical clustering of the genes selectively expressed in GC B-like DLBCL and activated B-like DLBCL, which was determined from Fig 3b
Differences Between GC-like and Activated B-like DLBCL
GC B-like DLBCL Activated B-like DLBCL
Cell of origin Germinal center B-cell Postgerminal center B-cell
Chromosomal alterations
t(14;18); gains of 12q Gains of 3q and 18q21-22; deletion of
6q21-q22, BCL6 translocations
Oncogenic mechanisms
BCL2 translocation; amplification of cREL locus
Constitutive NFkB activation
Ongoing Ig mutation
Yes No
IHC Expression of CD10, BCL-6 Expression of MUM1
Clinical outcome Favorable (60% 5-year survival)
Poor (35% 5-year survival)
Overall survival of DLBCL patients grouped on the basis of gene profiling shows worse outcome for patients with “activated B-like”
subtype
A.A. Alizadeh et al. Nature 2000; 403:503-511
Immunohistochemistry (IHC) can be used to determine the GC B-like and Activated B-like
subtypes of DLBCL
NormalLymph Node
GC B-like DLBCL
Activated B-like/non-GC B-like DLBCL
C.P. Hans et al. Blood 2004, 103:275-282
CD10 BCL-6
Overall survival curves comparing immunohistochemical and genetic classification of GC B-like and activated B-like
DLBCL are worse for the activated B-like subtype
C.P. Hans et al. Blood 2004, 103:275-282
Decision Tree for IHC Classification of DLBCL
• Sensitivity of IHC 71% for the GC B-like group and 88% for the activated B-like / non GC B-like group
• PPV of IHC was 87% for the GC B-like group and 73% for the activated B-like / non GC B-like group
• 30/142 (21%) of cases had discordant IHC and cDNA microarray results
C.P. Hans et al. Blood 2004, 103:275-282
Does the type of therapy for DLBCL affect prognosis in patients?
• Drugs in CHOP:– C = Cyclophosphamide– H = Doxorubicin (Hydroxydaunomycin)– O = Vincristine Sulfate (Oncovin)– P = Predisone
• Drugs in R-CHOP (since 2000):– R = Rituximab – C = Cyclophosphamide– H = Doxorubicin (Hydroxydaunomycin)– O = Vincristine Sulfate (Oncovin)– P = Predisone
Rituximab
• CD20 antigen– Expressed only on B-cells– Present in >90% of B-cell
lymphomas– Does not shed off cell
surface– Important for cell cycle
initiation and differentiation
B-cell
Murine antigen binding domain
Human IgG1 constant region
Human k constant region
CD20
Effects of Rituximab
• Mediates antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity
• Elicits shedding of CD23
• Down-regulates the B-cell receptor
• Induces apoptosis of CD20+ cells
• Half-life of 30-400 hours (varies by dose and length of treatment)
OS Curves of Patients with GC B-Like and Activated B-like DLBCL by IHC After CHOP or R-CHOP Treatment
R. Seki et al. Cancer Sci 2009, 100:1842-47
The overall survival rates for control and immunochemotherapy-treated DLBCL patients according to immunohistochemical and clinical
factors
H. Nyman et al. Blood 2007;109:4930-4935
CHOP R-CHOP R-CHOP
The Hans Classifier – Controversies in the CHOP and R-CHOP Era
Hans et al. Blood 2004Berglund et al. Mod Path 2005Haarer et al. Arch Pathol 2006Muris et al. J Pathol 2006Sjo et al. Eur J Hematol 2007Van Imhoff et al. J Clin Oncol 2007Nyman et al. Blood 2007Amara et al. Mod Pathol 2008Fu et al. JCO 2008 (R-CHOP)Colomo et al. Blood 2003Nyman et al. Blood 2007 (R-CHOP)De Paepe et al. JCO 2005Dupuis et al. Haematologica 2007Natkunam et al. JCO 2008Veelken et al. Ann Oncol 2007Amen et al. Histopathology 2007Wilson et al. JCO 2008 (DE-EPOCH-R)Ott et al. Leukemia Research 2012 (R-CHOP)
Survival association present
Survival association absent
Transcriptional Profile of DLBCL Subsequently Treated with R-CHOP
J.P. Jais et al. Leukemia 2008;22:1917-24
The recognition of GCB and ABC DLBCL is highly reproducible by gene expression profiling between
different centers
GCB Unclass ABC
GCB 53 3 0
Unclass 3 16 2
ABC 0 3 48
Center A
Center B
Concordant results in 117/128 (91%)
Unpublished data from Elias Campo, MD
Prognostic Impact of Gene Alterations in DLBCL in the Era of Rituximab
• MYC gene rearrangements
• CDKN2A (p16INK4/p14ARF) and CDKN2B (p15INK4) deletions
• p53 aberrations
cMYC • Located on 8q24• Regulates gene expression
through binding on Enhancer Box sequences and recruiting histone acetyl-transferases
• Burkitt lymphoma t(8;14) - cMYC gene next to the immunoglobulin heavy chain locus fusion gene causing overexpression of MYC proto-oncogene in lymphoma cells
Wikipedia
Outcomes of Patients with MYC+ or MYC- DLBCL
• 135 cases of DLBCL analyzed
• 12/134 cases (8.8%) were positive for MYC rearrangement
• All patients were treated with R-CHOP
K.J. Savage et al. Blood 2009; 114:3533-37
CDKN2A/B (p16,p14,p15)
• Located on 9p21.3• Tumor suppressor gene that
regulates cell cycle via the retinoblastoma and p53 apoptosis pathways
• Defective p53/CDKN2A/B signaling can lead to apoptosis resistance in DLBCL
Kreisel et al. Cancer Genetics 2010;204:129-37
TP53
• Located on 17p13.1• Tumor suppressor gene• “The guardian of the
genome”• p53 is in reference to its
molecular weight (53-kDa protein)
• 50% of human tumors contain a mutation or deletion of the TP53 gene
Wikipedia
OS according to the TP53 and CDKN2A allelic status in DLBCL. (A) Overall survival (OS) probability in the entire lymphoma population (n = 114). (B) OS probability in the R-CHOP
treated subgroup (n=78)
Jardin F et al. Blood 2010;116:1092-1104
Schematic representation of the 9p21 locus and its genomic alterations detected by a dedicated quantitative multiplex PCR of short fragments (QMPSF) assay in DLBCL.
Jardin F et al. Blood 2010;116:1092-1104
p16 p14 p15
Gray: heterozygous deletionBlack: homozygous deletion
CDKN2A/B
Summary• DLBCL represents a morphologically,
biologically, and clinically heterogenous group of tumors
• ~20-30% of DLBCL cannot be subcategorized into a current WHO subclassification
• Despite DLBCL subcategories clinical outcome within a specific category is heterogenous
• Genetic alterations of BCL-6, BCL-2, and c-MYC are among the most common recurrent genetic abnormalities
Summary
• Gene expression profiling of DLBCL offered– Comparison of gene signatures between
subsets of DLBCL and normal B cells– Delineation of robust and highly reproducible
DLBCL subtypes with comprehensive transcriptional signatures (GC-like vs. activated-like DLBCL)
– Identification of gene expression signatures associated with unfavorable response to empiric combination chemotherapy
Summary
• Immunohistochemical sub-categorization into GC-like vs. non GC B-type in Rituximab era remains controversial, although robust with cDNA microarray
• Additionally, c-MYC, TP53, and CDKN2A/B aberrations appear to have prognostic significance in Rituximab era
Journal Club
4/10/12
Aim of study• Show that the variability in natural history of
DLBCL reflects unrecognized molecular heterogeneity in the tumors
• Measure the activity (expression) of thousands of genes at once (DNA microarrays)
• Identify molecularly distinct subgroups of DLBCL
• Correlate different subgroups with clinical outcome
Construction of DNA microarray• “Lymphochip”: selection of genes that are
preferentially expressed in lymphoid cells and genes with known or suspected roles in immunology or cancer– 12,069 out of 17,856 cDNA from a germinal center B-
cell library– 2,338 cDNA from libraries derived from DLBCL,
follicular lymphoma, mantle cell lymphoma, chronic lymphocytic leukemia
– cDNA from genes that are induced or repressed during B- and T-cell-lymphocyte activation by mitogens or cytokines
– 3,186 genes of importance to lymphocyte and/or cancer biology
cDNA Microarray - Methodology
17,856-GENE ARRAYLYMPHOCHIP
17,856-GENE ARRAYLYMPHOCHIP
Experimental sample
Reference poolof 9 differentlymphoma celllines
The fluorescence ratio was quantified for each gene and reflected the relativeabundance of the gene in eachexperimental mRNA sample compared to the reference pool
Experimental sample
Reference poolof 9 differentlymphoma celllines
Figure 1dendrogram
Each row: separate cDNAclone on the microarray
Each column: separate experimental mRNAsample
Results: ratio of hybridization of fluorescent experimental mRNA to fluorescent pooledreference mRNA
Figure 2
“Lymph node survivalsignature” host response to lymphoma, is associated with survival times
“Proliferation signature”, a quantitative measurement of tumor cell proliferation, confers an inferior survival
“Germinal center B-cell signature”with BCL-6 and CD10 expression
Figure 3
Figure 4
Figure 5