12th Congress of the European Hematology ... - Haematologica

sclerosis[NS] and 12 Mixed cellularity[MC]) and in 10 reactive lymph
nodes (RLN). Patients median age was 32 years (range, 15-80), clinical
stage was I-II (n=26); III-IV (n=23) and 25 were EBV+. RNA was obtained
from formalin fixed paraffin embedded tissues. Data were analyzed by
using BRB Array Tools and TIGR Multiexperiment Viewer. Results. Hierarchical
clustering analysis categorized three well defined groups corresponding
to NS, MC and RLN. We detect a distinctive miRNAs signature
of cHL samples that was compound by a set of 25 miRNAs including
miR-21, mir-134 and mir-138, which permits to differentiate between
cHL samples and RLN. We applied PAM algorithm to an independent set
of 24 samples and using the microRNAs signature of 25 miRNAs the
samples were classificated in cHL or RLN correctly in all cases. We also
found a specific set of 36 miRNAs differentially expressed between nodular
sclerosis and mixed cellularity subtype. With respect to EBV presence,
we found that miR-96, 128a, 128b, 129 and 205 were underexpressed
in EBV + cases, whereas miR-28, 130b, 132, 140 and 330 were
overexpressed. We also found that miR-138 was overexpressed in clinical
stages I-II vs. III-IV (p=0.004), and that miR-328 was overexpressed
in stages III-IV (p=0.003). We analyze mir-21 and mir-138 by in situ
hybridization and found that it were expressed by the tumoral cells.
Summary/Conclusions. Classical HL have a specific miRNAs signature that
can play a role in its pathogenesis and there are differences between NS
or MC subtypes. The presence of EBV affect the miRNAs pattern.
0922
FREQUENT CRYPTIC ALTERATIONS DETECTED BY SNP-CHIPS IN BURKITT LYMPHOMAS
V. Havelange, 1 E. Callet-Bauchu, 2 I. Theate, 3 F. Mugneret, 4
L. Michaux, 5 C. Barin, 6 N. Dastugue, 7 E. Lippert, 8 P. Saussoy, 9
D. Penther10 , M. Vikkula11 , H. Poirel12 1 Cliniques Universitaires Saint-Luc, BRUSSELS, Belgium; 2 CHU-Lyon Sud,
LYON, France; 3 Laboratoire d’anatomopathologie,St Luc, BRUSSELS, Belgium;
4 Hôpital Bocage, DIJON, France; 5 KUL, LEUVEN, Belgium; 6 CHU Tours,
TOURS, France; 7 CHU Purpan, TOULOUSE, France; 8 CHU-Bordeaux, BOR-
DEAUX, France; 9 Laboratoire d'hématologie, BRUSSELS, Belgium; 10 Centre
Henri Becquerel, ROUEN, France; 11 Human molecular genetic, ICP, BRUSSELS,
Belgium; 12 Centre de Génétique Hématologie,St. Luc, BRUSSELS, Belgium
Background. Burkitt lymphomas/leukemias (BL), highly aggressive Bcell
lymphomas, are characterized by MYC locus rearrangement. Additional
chromosomal abnormalities have been described; the most frequent
are partial gain of 1q (+1q), 7q (+7q) and partial 13q deletion. We
recently demonstrated in a conventional cytogenetic study of childhood
mature B-cell lymphomas the independent negative prognostic impact of
del(13q) and +7q. Aims. To characterize these prognostic additional chromosomal
abnormalities and to look for cryptic genomic alterations in
order to reveal candidate genes and/or cellular pathways involved in
Burkitt lymphomagenesis. Methods. DNA from 36 BL (20 adults/16 children)
was analyzed by 50K Xba SNP arrays (Affymetrix), a genome-wide
study of single nucleotide polymorphisms (SNPs). This technique allows
the detection of allelic imbalances and losses of heterozygosity (LOH).
Results. The most frequent additional chromosomal abnormalities were
refined: partial or total gain of 1q and 7q. Recurrent 13q amplification
(minimal amplified region of 3.1Mb) was detected in 7 patients followed
by a terminal deletion in 4 patients. Different candidate genes are under
study. Many cryptic imbalances have been detected by this technique like
2p16.1 amplification containing 2 oncogenes (REL and BCL11a) in 7
patients or 9p21.3 deletion including the tumor suppressor gene (TSG)
CDKN2A in 4 patients. 144 acquired partial uniparental disomies (pUPD)
(defined as region of at least 50 SNPs) were found by SNP-arrays
(4/patient). pUPD are characterized by loss of heterozygosity without
chromosomal deletion and probably result from mitotic
recombination(s). The physiopathogenic role of pUPD remains unclear.
Firstly, it can be polymorphisms. Secondly, random pUPD can reflect
genomic instability especially in complex karyotypes. We show a similar
incidence of pUPD in BL with or without complex karyotype. Thirdly,
non random pUPD may have a pathogenic effect, rendering the cell
homozygous for a preexisting mutation leading to activation of an oncogene
or inactivation of a TSG. Some regions seem to be non-random in
the most probable pUPD of our series: 17p and 17q (n=4), 1p, 9p and 10q
(n=3). We are now sequencing candidate genes (CDKN2A, TP53…) in
these non random pUPD to unveil mutations of oncogenes or TSG. Conclusions.
The SNP arrays allowed us to characterize additional prognostic
chromosomal abnormalities in BL and to detect many cryptic non
random alterations. Acquired pUPD seem to be localized in non random
regions and can be involved in BL pathogenesis in cooperation with MYC
deregulation.
12 th Congress of the European Hematology Association
Cytogenetics, molecular diagnostics and targeted
therapies
0923
HIGH RESPONSE RATE AFTER SEQUENTIAL ADMINISTRATION OF AZACITIDINE,
VALPROIC ACID, AND ATRA IN PREVIOUSLY UNTREATED OLDER PATIENTS WITH ACUTE
MYELOID LEUKEMIA OR HIGH-RISK MYELODYSPLASTIC SYNDROME
E. Raffoux, 1 C. Recher, 2 N. Boissel, 1 R. Oumedaly, 3 I. Lobe, 1
F. Huguet, 2 D. Rea, 1 P. Chaibi, 4 A. De Labarthe, 1 P. Fenaux, 5
L. Degos, 6 C. Gardin, 5 H. Dombret1 1 1Hopital Saint Louis, PARIS, France; 2 CHU Purpan, TOULOUSE, France;
3 CHU Caen, CAEN, France; 4 Hop Ch. Foix, IVRY/SEINE, France; 5 CHU Avicenne,
BOBIGNY, France; 6 HAS, ST DENIS, France
Background. Intensive chemotherapy is associated with very poor
results in older patients with AML or high-risk MDS. Epigenetic modulation
combining demethylating agent and HDAC inhibitor seems to
be a promising alternative (Garcia-Manero Blood 2006, Soriano ASH
2006). We report here preliminary results of a pilot study using azacitine
and valproic acid (VPA) followed by ATRA in this patient population.
Patients and Methods. Patients with AML or high-risk MDS aged 60
years or more and considered as unfit for conventional chemotherapy
were enrolled. Each treatment cycle comprised azacitidine (75 mg/m 2 /d)
and VPA (50 mg/kg/d) for seven days (D1-D7), followed by ATRA (45
mg/m 2 /d) from D8 to D28, every 28 days. A total of 6 cycles was
planned. Peripheral blood and marrow evaluation was performed after
cycle 1, 3, and 6. AML responses were classified as CR, CRi, PR, NEL
(no evidence of leukemia), stable disease with or without haematological
improvement (HI), or progressive disease while MDS responses
were classified as CR, PR, HI, or progressive disease, according to AML
and MDS IWG criteria. Disease progression was assessed only after at
least 3 cycles. Results. Between March 2006 and January 2007, 20
patients were treated (median age, 74 years; 12 AML and 8 MDS). AML
patients had either severe comorbidities (n=6) or -7/complex karyotype
(n=6). All MDS patients had high-risk IPSS Score including 3 patients
with -7/3q abn/complex karyotype At the time of analysis, 17 patients
were evaluable with a median cycle number of 5. Overall haematological
response including HI was 65%. In AML patients, response rate
was 66% (8/12) with 6 CR, 1 PR and 1 NEL. In MDS patients, response
rate was 60% (3/5) including 1 CR, 1 PR, and 1 HI (HI-E + HI-P). Overall
CR + PR rate was thus 53%. Only one death was observed during
therapy (1 sepsis after the first cycle). Neurological Grade 3/4 toxicities
were observed in 2 patients (transient encephalopathy attributed to
VPA by both investigators and independent safety committee). Others
side effects were pain at injection site and mild GI events, as described
with azacitidine alone. Despite these toxicities, most patients could be
treated as out-patients. Conclusions. Combined therapy with azacitidine
and VPA followed by ATRA seems to be a relatively safe and very promising
approach in older patients with high-risk myeloid disorders.
Response rate (53% CR + PR) compares favorably enough with intensive
chemotherapy to envision future prospective up-front comparison.
0924
TARGETING ICMT AMELIORATES K-RAS-INDUCED MYELOPROLIFERATIVE DISEASE
AND LUNG CANCER
M. Bergo, A.M. Wahlstrom, M. Liu, C. Karlsson, B. Swolin, B.A. Cutts
Sahlgrenska University Hospital, GOTEBORG, Sweden
Background. Hyperactive signaling through the RAS proteins is
involved in the pathogenesis of many forms of cancer. The RAS proteins
and many other intracellular signaling proteins are methylated at a farnesylated
or geranylgeranylated cysteine residue at the carboxyl terminus
by isoprenylcysteine carboxyl methyltransferase (ICMT). We previously
showed that inactivation of Icmt results in mislocalization of the
RAS proteins and blocks oncogenic RAS transformation of mouse fibroblasts
suggesting that ICMT may be an attractive therapeutic target. However,
nothing is yet known about the impact of inhibiting ICMT on the
development of malignancies in vivo. Aim. To test the hypothesis that
inactivation of Icmt would inhibit the development or progression of a
K-RAS-induced myeloproliferative disease in mice. Methods. We used
Cre-loxP techniques to simultaneously activate the expression of
endogenous oncogenic K-RAS and inactivate the expression of Icmt in
bone marrow cells. In this way, we could determine if the absence of
Icmt would have an impact on the development of K-RAS-induced
haematologica/the hematology journal | 2007; 92(s1) | 345