ALBERT

Beschreibung: Abstract 4631 Background Peripheral T cell lymphomas (PTCLs) are a heterogeneous group of tumors representing approximately 12% of lymphoid neoplasms, basically subdivided into specified and not specified (NOS) forms. PTCL/NOS, corresponding to about 60%–70% of PTCLs, cannot be further classified on the basis of morphology, phenotype, or conventional molecular studies. Clinically, PTCLs/NOS are highly aggressive lymphomas, with a poor response to therapy, and dismal overall survival (20-30%). Their pathobiology is poorly known, though recent gene expression profiling (GEP) studies have provided some hints for better understanding their pathogenesis. In particular, GEP and immunohistochemical studies on tissue-microarrays (TMAs) demonstrated PDGFRA to be systematically activated in almost all PTCLs/NOS, by nominating it as potential therapeutic target. Aims In this study, we aimed to identify the determinants of PDGFRA activation in PTCL/NOS. Specifically, we studied PDGFRA locus in order to identify possible mutations, translocations, or copy number variations and we explored the possible existence of an autocrine/paracrine loop sustaining an otherwise integer kinase. Methods The PDGFRA locus (4q1.1-4q1.3) was studied by FISH and wide-genome SNPs analysis (Affymetrix 500K Array). Direct sequencing of all PDGFRA exons and introns as well as of the promoter region was also performed in 90 cases. IHC and ELISA were adopted in order to study the expression of PDGF-A, PDGF-B and PDGF-C on tissue sections and in supernatants from PTCL/NOS cell cultures, respectively. Finally, the expression of PDGFRA and its activated (phosphorilated) form, p-PDGFRA, was assessed by IHC on TMAs, and by flow-citometry in PTCL/NOS cultured cells as well as in a FIP1L1-PDGFRApos chronic eosinophilic leukemia cell line (EOL-1) before and after the exposure to an anti-PDGF ligand neutralizing antibody (R&D System), given at various concentrations (20-40-60-80 ug/mL). Vitality assessments, proliferation/cell cycle assay (by In Situ Cell Proliferation kit, FLUOS – Roche) and evaluation of PDGFRA and p-PDGFRA were performed at 24, 48, 96 hours. A human PDGF peptide (R&D Sytems) was added to cultured cells for 6 hours to evaluate whether PDGFRA de-phosphorilation was really due to PDGF ligand remotion. Results First, FISH, SNPs analysis and direct sequencing showed preserved integrity of PDGRA locus. Thus we tested the hypothesis of an autocrine/paracrine stimulation. PDGF-A, PDGF-B and PDGF-C were found to be expressed by neoplastic cells at IHC in 93-95% of cases. In addition, PDGF-AA was found to be secreted by cultured neoplastic cells by ELISA. Notheworthy, PTCL cells secreted much more ligand than any other cell taken as control. We then tested whether PDGFRA phosphorylation was actually due to the presence of a PDGF ligand. Indeed, PTCL cells treated with anti-PDGF ligand neutralizing antibody at various concentrations showed PDGFRA dephosphorilation ranging from 30% up to 90% in a time dependent manner. Notably, the effect was specific as in EOL-1 PDGFRA phosphorylation was not modified at all. In addition, PTCL cells treated with a minimum of 20ug/mL of anti-PDGF ligand neutralizing antibody for 48h showed a 70% blockade of proliferation in comparison to untreated cells (BrdU assay). A further addition of 20 ug/ml of inhibitory antibody at 48 hours, increased the proliferation arrest up to 80% at 96 hours. Finally, the addition of a natural human PDGF peptide to cells previously treated with the anti-PDGF antibody, could restore PDGFRA phosphorylation confirming that PDGFRA de-phosphorilation was due to ligand remotion. Conclusions Taken together, our data demonstrate that PDGFRA activity is sustained by an autocrine loop in PTCL/NOS. In fact, though, in vivo, a possible additive paracrine effects mediated by reactive components cannot be excluded, we provide evidence that the phenomenon is largely due to neoplastic cells. Importantly, as PDGFRA signaling abrogation was associated to proliferation arrest, PDGFRA was confirmed as potential therapeutic target. Acknowledgments: this work was supported by Centro Interdipartimentale per la Ricerca sul Cancro “G. Prodi”, BolognAIL, AIRC, FIRB, RFO, Fondazione Cassa di Risparmio in Bologna, Fondazione della Banca del Monte e Ravenna, Progetto Strategico di Ateneo 2006, and Vanini-Cavagnino grant. Disclosures: No relevant conflicts of interest to declare.

Beschreibung: Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare disease of controversial origin recently recognized as a neoplasm deriving from plasmacytoid dendritic cells (pDCs). Nevertheless, it remains an orphan tumor with obscure biology and dismal prognosis. In this study, we aimed to: 1) molecularly define the cellular counterpart of BPDCN and its relationship with other leukemias; 2) identify genes and cellular programs deregulated in the tumor; and 3) delineate novel potential therapeutic targets. To address these issues we collected and studied by gene expression profile (GEP) 27 BPDCN cases as well as 8 samples of non neoplastic pDCs. Further, a panel of samples including, myeloid precursors (MPs, N=4), lymphoid precursors (LPs, N=9), acute myeloid leukemias (AMLs, N=132), and acute lymphoblastic leukemias (ALLs, N=155) was analyzed. Validation was performed by immunohistochemistry (IHC) on tissue-microarrays, while functional experiments were carried out by using the CAL-1 cell line (derived from a BPDCN case). First, we recognized the cellular derivation of BPDCN, which proved to originate from the myeloid lineage and in particular from resting pDCs. Second, by comparing the GEP of BPDCN and resting pDCs, we identified genes and cellular programs deregulated in the tumor. Following, based on an integrated bio-informatic approach, including four different tools, we uncovered the aberrant activation of the NF-kB pathway that was confirmed in independent assays. Interestingly, among other molecules, we identified BCL2 and IRF4, two well known NFkB targets, as aberrantly upregulated in neoplastic samples and confirmed this observation by IHC. We then tested whether NFkB inhibition could represent a potential therapeutic strategy in this setting. We treated BPDCN cells ex vivowith either the proteasome inhibitor bortezomib or the selective IKKB inhibitor BMS-345541 and found them to be effective in inducing cell cycle arrest and apoptosis at relatively low dosage. By contrast, BPDCN cells turned out to be virtually insensitive to cytarabine, one of the most used drug in this condition. GEP and immunocytochemistry were then successfully used to prove that cell death was accompanied by NFkB shut-off. In conclusion, we identified a molecular signature representative of the transcriptional abnormalities of BPDCN and developed a cellular model proposing the first molecular targeted therapeutic approach in the setting of this currently incurable disease. Funding This work was supported by AIRC (IG10519 and 5xMille10007, Prof. Pileri), Centro Interdipartimentale per la Ricerca sul Cancro “G. Prodi”, BolognAIL, RFO (Prof. Pileri, Prof. Piccaluga), FIRB Futura 2011 RBFR12D1CB (Prof. Piccaluga), Fondazione Cassa di Risparmio in Bologna, Fondazione della Banca del Monte e Ravenna, Progetto Strategico di Ateneo 2006 (Prof. Pileri and Dr. Piccaluga) and by MIUR (PRIN 2011, Prof. Facchetti and Prof. Pileri). The authors have no conflicting financial interests to declare. Acknowledgments The Authors obtained the CAL-1 cell line from Takahiro Maeda (tmaeda@net.nagasaki-u.ac.jp), Department of Laboratory Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan. Disclosures: No relevant conflicts of interest to declare.

Beschreibung: Abstract 3291 Primary immune thrombocytopenia (PIT) results from both increased platelet destruction and insufficient platelet production. Although the development of autoantibodies against platelet glycoproteins remains central in the pathophysiology of PIT, several abnormalities in the immune modulation system have been identified (Blood 2008 Aug 15;112(4):1147; Hematol Oncol Clin North Am. 2009 Dec;23(6):1177; Hum Immunol. 2010 Jun;71(6):586); We analysed morphology, lymphocyte phenotype and heavy immunoglobulin (IgH) and TCR gamma (TCRg) gene rearrangements in spleens from 31 PIT patients to assess possible impact on diagnosis and course, in comparison with 19 spleens surgically removed for trauma. Age ranged from 15 to 68 (mean 41.61y) with M/F of 9/22 in PIT and 18 to 89 (mean: 66y) with M/F 11/8 in controls. All PIT patients experienced at least one line therapy before surgery and 4 underwent anti-CD20 immunotherapy. Immunohistochemistry for CD3, CD20, CD4, CD8, CD56, CD57, PD1, Tia1, Granzyme B, FoxP3, CD72 was made in all cases; both IgH and TCRg gene analysis were possible in 24/31 PIT and 17/19 controls, while 4/31 PIT and 2/19 controls were examined for either one (PIT: 2 TCR and 2 IgH, controls 1 TCR and 1 IgH) and 5 PIT and 1 control were excluded for unsatisfactory material. Ay histology all cases but 2 showed expanded white pulp (that was hypoplastic in the 2/4 cases that underwent Rituximab before surgery), moderate lymphocytic and modest granulocytic infiltrates in the red pulp; haemorragic lakes were present in control spleens. Immunohistochemistry showed similar stains in the 2 groups with normal distribution (white pulp: CD20+ B follicles, CD72-+ in the marginal zone, CD3+/CD4+ T cells, PD1/CD57+ T cells in the germinal centers; red pulp: regular CD20/CD3 and CD4/CD8 ratio, PD1/Tia1/Granzyme B expressed in roughly less than 20% CD3+ T cells; scattered CD57+/CD56- T cells. For molecular results see table 1 below. Monoclonality was defined if 1 or 2 peaks of amplified polymerase chain reaction products were obtained, oligoclonality with 3 to 5 peaks and polyclonality with a Gaussian peak distribution.Table 1IGHWDCtrlIGHWDCtrlPoly2015Poly-Oligo2116Oligo10Mono32Mono32TCRWDCtrlTCRWDCtrlPoly75Poly-Oligo128Oligo53Mono129Mono129 The results showed no statistically significant differences between PIT and controls as for morphology, phenotype and clonality. Since a decrease in regulatory T cells (T regs) is reported in PIT among other immune-impairments (Eur J Haematol. 2007 Oct;79(4):310; Zhonghua Nei Ke Za Zhi. 2010 Mar;49(3):213;Blood. 2009 Mar 12;113(11):256) we immunostained all cases with T reg-related nuclear molecule Foxp3: in control cases few cells in the white and red pulp were observed, while in PIT spleens fewer Foxp3 positive cells could only be seen in the red pulp: although results are slightly different, the low amount of positive cells in both groups decreases the reliable reproducibility of such observation. Moreover, the use of glucocorticoids by all patients before splenectomy, could have further reduced (Eur J Haematol. 2007 Oct;79(4):310) T regs levels. Overlapping molecular results were also obtained in the two groups in agreement with previous reports (Hematology. 2009 Aug;14(4):237; Platelets. 2009 Mar;20(2):135; Int J Hematol. 2003 Dec;78(5):461; Blood. 2002 Aug 15;100(4):1388). The attempt to translate the molecular findings into immunomorphologic differences between monoclonal and non monoclonal cases failed since neither amount/distribution of B and T cells nor T cell subtypes showed evident differences. On the whole, our results show that neither lymphoid phenotype nor IgH or TCRg clonality can be used as specific features of refractory PIT or guide treatment choice.Figure 1Figure 1. Disclosures: No relevant conflicts of interest to declare.

Beschreibung: Abstract 1890 Poster Board I-913 Background. Primary myelofibrosis (PMF) is a clonal myeloproliferative neoplasm (MPN) characterised by a proliferation of predominantly megakaryocytes and granulocytes in bone marrow that in fully developed disease is replaced by fibrous tissue. At molecular level, no specific defect has been identified yet. Cytogenetic abnormalities occur in up to 30% of patients, the commonest including del(13)(q12-22), der(6)t(1;6)(q21-23;p21.3), del (20q), and partial trisomy 1q. In addition, approximately 50% of patients with PMF exhibit a single, recurrent, somatic mutation in the gene encoding the cytoplasmic tyrosine kinase Janus kinase 2 (JAK2). However, such mutation is not specific, also occurring in other MPN. Recently a couple of reports dealt with single-nucleotide polymorphism (SNP) array karyotyping of MPD, including some PMF. Importantly, such studies could identify previously uncovered genetic lesions, highlighting the importance of novel high resolution technologies for the detection of formerly unknown, cryptic aberrations. In this study we performed high resolution karyotyping by SNP oligonucleotide microarray by using the most updated Affymetrix array (Genome-Wide Human SNP Array 6.0) in 20 cases of myelofibrosis (MF) in order to identify novel cryptic genomic aberrations. Methods. DNA (500 ng) was extracted from peripheral blood cells (PBMNC) of 14 primary and 6 secondary MF patients. PBMNC were depleted from lymphocytes by magnetic beads. Briefly, CD3+ cells were labeled with anti-CD3 MoAb directly coupled to magnetic microbeads (Miltenyi Biotech), washed and subsequently purified using Mini-MACS technology. After selection, cell present in the positive (CD3) and negative (PBMNC) fractions were counted and submitted to flow cytometry analysis. DNA was processed and hybridized to the Affymetrix SNP arrays 6.0 as for manufacturer instruction. A whole-genome copy number variation (CNV), genotyping, loss of heterozygosity (LOH) and uniparental disomy (UPD) analyses were performed using the Partek Suite 6.0. Ten lab-specific as well as 90 HapMap samples relative to Caucasian healthy donor were used as control reference. Genomic abnormalities were defined as recurrent when occurring in at least 25% of cases. JAK2 mutational status was assessed as reported, by alle-specific PCR. Clinical information and complete follow up were retrieved for all cases. Direct sequencing, FISH, qPCR and immunohistochemistry (IHC) has been chosen for validation. Results. In all patients we could detect several CNV. The median number of CNV was 60 (range, 34-72), including 46 amplifications (A) and 14 deletions (D). All commonest previously described abnormalities were detected. In addition, several formerly uncovered recurrent lesions were identified, mainly involving 1p, 1q, 2p, 4p, 4q, 5q, 6p, 6q, 7q, 8p, 9q 10q, 11p 11q, 12p, 14q, 15q, 16p, 16q, 17q, 18q, 19q, 20p, 22q. The median size of such CNV was 424,582 Kbp (1,379 Kbp-71,277 Mbp). We then compared JAK2+ vs. JAK2− cases. Of note, we found numerous definite aberrations (A or D) distinguishing the two groups and specifically affecting 16q23.1, 1p36.13, 3q26, 14q13.2, 5q33.2, 6q14.1, 7q33, 8p23.1, and 9p11.2. Grippingly, several genes of potential interest for PMF pathogenesis were identified within the involved loci, including RET, SCAPER, WWOX and SIRPB1. Among others, the product of such genes has been selected for validation by IHC. Similarly, many miRNA were recognized, which may deserve further investigation. Conclusions. By using a newly developed highly sensitive array we identified novel cryptic lesions in patients affected by MF. Future studies on larger series, as well as functional analyses will definitely assess their role in the pathogenesis of the disease. Of note, consistent differences were recorded in JAK2+ vs. JAK2−, supporting the hypothesis of different genetic mechanisms occurring in the two sub-groups. Acknowledgments: this work was supported by AIL Pesaro Onlus, Centro Interdipartimentale per la Ricerca sul Cancro “G. Prodi”, BolognAIL, AIRC, FIRB, RFO, Fondazione Cassa di Risparmio in Bologna, Fondazione della Banca del Monte e Ravenna, Progetto Strategico di Ateneo 2006.*GV and MRS equally contributed to this work. Disclosures: No relevant conflicts of interest to declare.

Beschreibung: Abstract 3662 The differential diagnosis among the commonest peripheral T-cell lymphomas (PTCLs) (i.e. PTCL not otherwise specified, NOS; angioimmunoblastic T-cell lymphoma, AITL; and anaplastic large cell lymphoma, ALCL) is difficult, the morphologic and phenotypic features being largely overlapping. Noteworthy, recent international studies indicated significant differences in their clinical behavior as well as concerning the presence of potential therapeutic targets. We performed whole genome gene expression profiling (GEP) of PTCLs aiming to identify molecular signatures able to improve their diagnosis. We studied 95 PTCLs, including 73 PTCLs/NOS, 12 ALCLs (6 ALK+ and 6 ALK-), and 10 AITLs. All tissue samples were formalin-fixed and paraffin embedded (FFPE). GEP was performed by Illumina Whole Genome DASL Assay. First, we documented the efficiency of GEP from FFPE tissues by comparing the mRNA levels and the presence of the corresponding protein, including expressed (i.e. CD3) and not expressed (i.e. BCL10) molecules. Secondly, we tried to discriminate different PTCLs basing on their GEPs. By dividing a training (N=47) and a test set (N=48), we found 2 signatures able to differentiate PTCL/NOS vs. AITL and PTCL/NOS vs. ALCL ALK-. Specifically, in the test set the sensitivity (ST) and specificity (SP) of the assays were 100% – 80% (PTCL/NOS vs. AITL) and 100% – 100% (PTCL/NOS vs. ALK- ALCL) (Table 1). Accordingly, the positive (PPV) and negative (NPV) predicting values for the identification of PTCL/NOS were 0.92 and 1 (vs. AITL) and 1 and 1 (vs. ALK- ALCL) (Table 1).Table 1.Accuracy of GEP based signature in differentiating PTCL subtypesSTSPPPVNPVTraining setPTCL/NOS vs. AITL100%80%0.921PTCL/NOS vs. ALK-ALCL100%100%11Test setPTCL/NOS vs. AITL92.50%100%10.77PTCL/NOS vs. ALK-ALCL92.50%100%10.67Validation setPTCL/NOS vs. AITL85%86%0.920.76PTCL/NOS vs. ALK-ALCL96%73%0.960.73 Interestingly, the identified genes represented relevant functional pathways differentially regulated in the 3 tumour types, including protein kinase cascade, proliferation, and cell cycle. When applied to the test set of cases, the assay correctly classified 37/40 PTCLs/NOS (92.5%), 5/5 AITLs, and 3/3 ALK- ALCLs. Finally, we tested our signatures on 133 independent PTCL cases (including 78 PTCL/NOS, 43 AITL, and 12 ALK- ALCL) for which GEP data were available on the GEO database and were originally obtained from fresh/frozen tissues. Interestingly, we could efficiently recognize PTCL/NOS cases vs. AITLs (ST, 85%; SP 86%; PPV 0.92; NPV 0.76) and vs. ALK- ALCLs (ST 96%; SP 73%; PPV 0.96; NPV 0.73). In conclusion, we successfully generated for the first time GEP from routinary FFPE PTCL samples, identifying molecular signatures potentially useful for the clinical practice and, specifically, for the differential diagnosis of PTCL types. Disclosures: No relevant conflicts of interest to declare.