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

12 th Congress of the European Hematology Association
Novel therapeutics and targeted therapies I
0309
FUNCTIONAL CHARACTERISTICS AND GENE EXPRESSION PROFILES OF PRIMARY ACUTE
MYELOID LEUKAEMIA CELLS IDENTIFY PATIENT SUBGROUPS THAT DIFFER IN THE
SUSCEPTIBILITY TO HISTONE DEACETYLASE INHIBITORS
C. Stapnes, 1 A. Ryningen, 1 K. Hatfield, 1 A.M. Oyan, 2 G.E. Eide, 3
K.H. Kalland, 2 B.T. Gjertsen, 1 O. Bruserud1 1 Institute of Medicine, BERGEN; 2 The Gade Institute, BERGEN; 3Centre for
Clinical Research, BERGEN, Norway
Modulation of gene expression through histone deacetylase (HDAC)
inhibition is now considered a possible therapeutic strategy in several
malignancies, including acute myeloid leukaemia (AML). In the present
study we investigated the in vitro effects of various HDAC inhibitors on
primary human AML cells. The relation between the biological response
to HDAC inhibitors and basal gene expression profiles were assessed.
AML cells were derived from 59 consecutive patients. Effects of structurally
different HDAC inhibitors on cell proliferation, apoptosis induction,
colony formation and CD34 cell subsets were studied. Basal gene
expression of untreated cells was examined by microarray techniques.
The HDAC inhibitors valproic acid, PXD101, trichostatin A and sodium
butyrate were investigated. All drugs inhibited AML cell proliferation in
a dose-dependent manner when tested at high concentrations. However,
at lower concentrations, proliferation increased for a subset of
patients. HDAC inhibitors also decreased proliferation of clonogenic
and CD34 + leukaemic cells and increased apoptosis. Again the inhibition
was observed at high concentrations whereas enhanced proliferation
and decreased apoptosis were observed for a subset of patients at lower
concentrations. Based on basal expression of 100 genes it was possible
to separate patients (a group of 17 FLT3-ITD+ patients with normal
cytogenetics) with growth enhancement at intermediate HDAC
inhibitor concentrations and those without this response into two mutually
exclusive groups. Several of the genes have previously been used for
classification of AML patients. E.g. high expression of Dynein light chain
1 (DLC1) and low expression of transmembrane 4 superfamily member
2 (TM4SF2) has been associated with bad prognosis; DLC1 showed
high expression in patients with drug-induced growth enhancement,
whereas high TM4SF2 expression was observed for our group without
growth enhancement. Low expression of members of the apolipoprotein
system has been associated with adverse prognosis, and our patients
with growth enhancement also showed low levels of Apolipoprotein C1
(APOC1). The two groups could not be separated on the basis of expression
of HDACs and histone acetyl transferases. In conclusion, functional
characterisation and gene expression analyses identify AML patient
subsets that differ in their response to HDAC inhibitors in vitro. These
observations may explain why HDAC inhibitor therapy affects only a
subset of AML patients.
0310
TARGETED THERAPY OF ADULT T CELL LEUKEMIA: FROM THE BENCH TO BEDSIDE
A. Bazarbachi, 1 R. Nasr, 1 M. El-Sabban, 1 H. El Hajj, 1 Y . Kfoury, 1
L. Haddad, 1 H. Hasegawa, 2 W. Hall, 2 H. De Thé, 3 O. Hermine4 1 American University of Beirut, BEIRUT, Lebanon; 2 University College Dublin,
DUBLIN, Ireland; 3 UMR 7151 CNRS, PARIS, France; 4 Necker Hospital,
PARIS, France
Background. Adult T-cell leukemia/lymphoma (ATL) is an aggressive
malignancy of mature activated T-cell caused by human T cell lymphotropic
virus type I (HTLV-I). ATL carries a very bad prognosis because
of intrinsic chemoresistance and severe immunosuppression. The viral
transactivator protein Tax is responsible for several aspects of the malignant
transformation such as proliferation, resistance to apoptosis, genetic
instability, tumor dissemination, immnune escape and chemotherapy
resistance. Through all of these activities, Tax acts as a powerful
oncogene, and represents the most attractive viral protein for targeted
therapy. Among Tax properties, activation of the NF-κB pathway plays
a crucial role in the proliferation and transformation of the infected cells.
Indeed, most of the activated cellular genes in HTLV-I infected cells are
through this mechanism. Results. We have, using an in vitro model of
ATL derived cells, identified several potential targeted therapies for ATL:
1) Arsenic trioxide (As) synergizes with interferon-α (IFN) to induce G1
arrest and apoptosis in ATL through shut-off of the NF-κB pathway and
Tax degradation by the proteasome. This combination yielded promis-
112 | haematologica/the hematology journal | 2007; 92(s1)
ing clinical results in relapsed/refractory ATL patients. 2) Clinically
achievable concentrations of bortezomib, a selective proteasome
inhibitor, targeted multiple cellular pathways that resulted in dramatic
inhibition of cell proliferation and apoptosis of ATL-derived cells. 3) ATL
cells secrete high concentrations of functional angiogenic factors, establish
functional gap junctions with endothelial cells, and extravasate
through the endothelial barrier using mechanisms involved in angiogenesis.
Angiogenesis inhibitors, such as anti-VEGF monoclonal antibodies
(bevasizumab) or specific kinase inhibitors of the VEGF receptors
(PTK-787) inhibit ATL-induced angiogenesis and impede ATL cell invasion.
We are investigating the in vivo therapeutic potential of these targeted
therapies identified in our in vitro studies, using as a preclinical
model SCID mice injected with lymphomatous spleen cells from transgenic
mice for the Tax gene of HTLV-I. Results of these ongoing studies,
with respect to tumor regression, apoptosis induction and survival
will be presented.
0311
HE TYROSINE KINASE INHIBITOR DASATINIB SUPPRESSES IGE-DEPENDENT ACTIVATION
AND HISTAMINE RELEASE IN BASOPHILS
M. Kneidinger, 1 K. V. Gleixner, 1 A. Böhm, 1 A. Vales, 1 K. Sonneck, 1
S. Florian, 1 M. Weghofer, 1 C. Lupinek, 1 S. Vrtala, 1 R. Valenta, 1
G. Superti-Furga, 2 F.Y. Lee, 3 P. Valent1 1 Medical University of Vienna, VIENNA, Austria; 2 CeMM, Research Center
f. Mol. Med., VIENNA, Austria; 3 Oncol. Drug Disc., Bristol-Myers Squibb,
PRINCETON, NJ, USA
Background. Dasatinib (BMS354825) is a small molecule-type inhibitory
drug that blocks several tyrosine kinases including src kinases,
PDGFR, KIT, and BCR/ABL. Recently, dasatinib has been introduced as
a new effective antileukemic agent in patients with imatinib-resistant
chronic myeloid leukemia (CML) and acute lymphocytic leukemia.
Moreover, dasatinib may act on normal lymphocytes and other physiologic
cells through diverse target structures. In particular, dasatinib has
recently been examined for its immunosuppressive and anti-inflammatory
effects. Methods and Results. We here report that dasatinib at 1 µM
completely blocks the anti-IgE-induced release of histamine in human
blood basophils in healthy subjects. The effects of dasatinib on histamine
secretion in basophils were dose-dependent (IC50: 50-100 nM) and
were found to be specific for IgE-dependent activation of basophils in
that no inhibition was seen in C5a-activated or Ca-ionophore-exposed
basophils. Moreover, dasatinib was found to block recombinant allergen-induced
release of histamine from human basophils in sensitized
individuals. In addition, as assessed by flow cytometry, dasatinib (1 µM)
was found to inhibit the IgE-dependent upregulation of several activation-linked
antigens, including aminopeptidase N (CD13), LAMP-3
(CD63), endolyn (CD164), and the basophil-related ecto-enzyme E-
NPP3 (CD203c) on human basophils. The effects of dasatinib on upregulation
of basophil differentiation antigens were found to be dosedependent
and were seen in normal subjects as well as in allergic individuals.
Conclusions. Dasatinib blocks IgE-mediated activation and histamine
release in human blood basophils. These anti-allergic effects of
dasatinib may have clinical implications and may point to additional
indications for this multifunctional drug.
0312
MLN3897, A NOVEL CCR1 INHIBITOR, IMPAIRS OSTEOCLAST FORMATION AND
FUNCTION ASSOCIATED WITH DOWNREGULATION OF C-FOS
S. Vallet, 1 N. Raje,1 K. Ishitsuka, 1 T. Hideshima, 1 I. Breitktreutz, 1
T. Kiziltepe, 1 H. Yasui, 1 S. Pozzi, 1 D. Cirstea, 1 E. Ocio, 1 N. Shiraishi, 1
M. Ladetto, 2 M. Boccadoro, 2 K. Anderson1 1 2 Dana Farber Cancer Institute, BOSTON, USA; Università degli studi di Torino,
TORINO, Italy
Background. Osteolytic lesions due to enhanced osteoclast (OC) activity
are a hallmark of myeloma bone disease and other metastatic cancers.
Chemokines play a critical role in enhancing OC formation and
activity. Aims.Since CCR1 is one of the main chemokine receptors
expressed on monocytes and OC, we here characterized the effects of
MLN3897 (Millennium Pharmaceuticals), a novel specific antagonist of
CCR1, on OC formation and function. Methods. In order to analyze the
effects of MLN3897 on osteoclastogenesis, we generated OC from
peripheral blood mononuclear cells of healthy donors stimulated with
RANKL and M-CSF (50 ng/mL) for 3 weeks, in the absence or presence
of MLN3897. Mature OC were multinucleated TRAP+ cells, and their