Haematologica 2003 - Supplements

Plenary Sessions
1. Development of normal and malignant
plasma cell
P1.1
PRIMARY IGH TRANSLOCATIONS AND D-TYPE
CYCLIN EXPRESSION PROVIDE A NOVEL
MOLECULAR CLASSIFICATION OF MULTIPLE
MYELOMA
Bergsagel PL 1 , Chesi M 1 , Trudel S 1 , Affer M 1 , Robbiani
DF 1 , Ely S 1 , Hurt EM 2 , Staudt LM 2 , Fonseca R 3 , Barlogie
B 4 , Shaughnessy J 4 , Kuehl WM 5
1. Weill Medical College, 2. Metabolism Branch, NCI, 3. Mayo
Clinic, 4. University of Arkansas for Medical Sciences, 5. Genetics
Department, NCI. Contact: plbergsa@med.cornell.edu
During the secondary immune response activated B cells undergo
IgH somatic mutation and isotype switch recombination then
home to the bone marrow and differentiate into long-lived plasma
cells. Multiple myeloma is the malignant counterpart of these
cells. We hypothesized that errors in these B cell specific DNA
modification processes may be responsible for IgH translocations
in MM, and developed a Southern blot assay to identify them.
Identification and cloning of translocation breakpoints in MM has
identified two types of IgH translocations. Primary translocations
have breakpoints that cluster within the switch and JH regions
(11q13, 6p21, 4p16, and 16q23), while secondary translocations
have breakpoints outside of these regions (8q24, 6p25, 20q11,
other non-recurrent partners). We postulate that these primary
translocations, which occur in 40% of MM patients at diagnosis,
are early, disease-defining events. Other unidentified IgH
translocations (not 11q13, 6p21, 4p16, or 16q23) are identified in
20% of patients at diagnosis, although the frequency of primary
and secondary translocations within this group is unknown.
Finally, 40% of patients do not have IgH translocations at
diagnosis, and the molecular pathogenesis of this subset remains
enigmatic 1 .
The primary translocations identify homogeneous groups of
patients with similar phenotypic features and response to
treatments. Seventy-five percent of patients with t(4;14)
ectopically express FGFR3 and proliferate abnormally in
response to FGF. Inhibition of FGFR3 signaling in these MM
inhibits FGF induced growth, and in cell lines with activating
mutations can induce growth arrest followed by differentiation,
then apoptosis. Ectopic expression of c-maf, most pronounced in
t(14;16) MM, results in expression of integrin beta 7, increased
adhesion to E-cadherin and stroma and increased expression of
cyclin D2, a direct transcriptional target of cyclin D2. Inhibition
of c-maf inhibits growth and tumorigenicity in nude mice of c-
maf-expressing MM cell lines. These results demonstrate the
importance of these translocations to MM biology and validate
the genes dysregulated by these translocations as attractive targets
for drug development.
In addition these results highlight the importance of cyclin D
dysregulation, either directly (Cyclin D1 - 11q13, Cyclin D3 -
6p21) or indirectly (Cyclin D2 – 16q23, 4p16), as a common
pathway dysregulated by IgH translocation in MM. If we
examine the expression of cyclin D in a large group of MM
patients (200) it is evident that almost all patients (not only those
with translocations) ectopically express a single cyclin D, a result
incongruous with such a low proliferative tumor. Therefore
dysregulation of the cyclin D pathway provides a unifying
hypothesis for myelomagenesis. In this analysis, 60% (119/200)
of patients do not have a primary translocations, with 35%
(70/200) that express cyclin D1 (at a level below that seen with
t(11;14)), 20% (40/200) that express cyclin D2, and 5% (9/200)
without a predominant cyclin D. This large group of patients with
a low level of cyclin D1 expression and lacking a t(11;14) (that
we call D1 lo) have a distinct gene expression profile suggesting
that they represent a homogeneous population of patients. We do
not observe MM cell lines with this phenotype, and postulate that
they may be particularly dependent on the bone marrow
microenvironment for their growth and survival. We postulate
that this group of patients represents an important new molecular
subtype of MM that may include most of the patients lacking IgH
translocations. In a recent cytogenetic analysis the prognostic
importance of ploidy has been noted, with hypodiploid MM
associated with a worse prognosis (median OS 12.6 mo) and
more frequent IgH translocation (56%), while hyperdiploid MM
had a better prognosis (median OS 33.8 mo), and less frequent
IgH translocations (11%) 2 . This suggests that the D1 lo group,
lacking primary IgH translocations, overlaps significantly with
this hyperdiploid group.
Based on this analysis of the data generated by Avet-Loiseau and
the IFM 3 , Fonseca and the Mayo group 4 , and Shaughnessy and
the Arkansas group 5 , and Smadja, Bastard and the Groupe
Francais de Cytogenetique Hematologique 2 , we propose the
following simple molecular classification of MM:
Translocation and Cyclin D (TC) Molecular Classification of
MM v1.0
Class 1 ry IgH Cyclin Diploid Incidence Survival*
tx
TC1 6p21 D3 Non-hyper 3% 88%
11q13 D1 Non-hyper 15%
TC2 None D1 lo ?Hyper 35% ?51%
TC3 None None ?Hyper 3% ?49%
None D2 ?Hyper 20%
TC4 4p16 D2 Non-hyper 18% 23%
16q23 D2 Non-hyper 6%
*Overall Survival at 80 months from Moreau et al, 2002 3 .
This model has important implications for identifying genetically
homogeneous groups of patients for treatment protocols, and
defines two distinct groups (TC2 and TC3) in need of greater
molecular dissection.
1. Kuehl WM, Bergsagel PL. Multiple myeloma: evolving
genetic events and host interactions. Nat Rev Cancer.
2002;2:175-187
2. Smadja NV, Bastard C, Brigaudeau C, Leroux D, Fruchart C.
Hypodiploidy is a major prognostic factor in multiple myeloma.
Blood. 2001;98:2229-2238.
3. Moreau P, Facon T, Leleu X, Morineau N, Huyghe P,
Harousseau JL, Bataille R, Avet-Loiseau H. Recurrent 14q32
translocations determine the prognosis of multiple myeloma,
especially in patients receiving intensive chemotherapy. Blood.
2002;100:1579-1583
4. Fonseca R, Blood E, Rue M, Harrington D, Oken MM, Kyle
RA, Dewald GW, Van Ness B, Van Wier SA, Henderson KJ,
Bailey RJ, Greipp PR. Clinical and Biologic Implications of
Recurrent Genomic Aberrations in Myeloma. Blood. 2003
5. Zhan F, Hardin J, Kordsmeier B, Bumm K, Zheng M, Tian E,
Sanderson R, Yang Y, Wilson C, Zangari M, Anaissie E, Morris
C, Muwalla F, van Rhee F, Fassas A, Crowley J, Tricot G,
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