ALBERT

Description: 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.

Description: Chromosome number alterations, aneuploidy, is a hallmark of cancer. It occurs in about 15% of acute myeloid leukemia (AML) cases, is generally preserved throughout disease progression (Bochtler et al. Leukemia 2015) and correlates with adverse prognosis (Breems et al. JCO 2008, Papaemmanuil et al. NEJM 2016). This evidence highlights the need of understanding the molecular mechanisms that promote and sustain aneuploidy in AML, in order to define novel potential therapeutic targets. In the NGS-PTL project we profiled the genomic landscape of 536 hematological samples by whole exome sequencing (WES, Illumina). Among them, we analyzed 88 and 68 samples from aneuploid (A-) FLT3-wildtype AML (isolated trisomy and monosomy, complex and monosomal karyotype) and euploid (E-) AML (normal and complex karyotype,

Description: Outcome for older patients with acute myeloid leukemia (AML) is extremely poor. Intensive induction chemotherapy is often unsuitable. In this phase II study we tested, for the first time, the efficacy of a novel combination therapy with low-dose lenalidomide plus low-dose cytarabine. Further, based on the hypothesis that genetic features might influence treatment response, we aimed at identifying a possible biomarker by studying the global gene expression profiles (GEP). We designed a prospective phase II study to assess the efficacy of the concomitant administration of low-dose lenalidomide and low-dose cytarabine in patients with acute myeloid leukemia (AML) aged more than 70 years. Forty-five patients (median age 76 years, range: 70-85) ineligible for standard therapy, were consecutively treated with low-dose lenalidomide (10 mg/day orally, days 1-21) plus low-dose cytarabine (10mg/m2 twice daily, subcutaneously, days 1-15) every six weeks, up to 6 cycles. Median white blood cell count at diagnosis was 3.2x109/l (range: 0,4-46,8x109/l), whereas median hemoglobin was 8,9 g/dl and median platelet count was 31x109/l. Twenty-three out of 45 patients had an intermediate karyotype (18/23 normal), 18/45 an unfavorable karyotype and 4/45 were not evaluable. Nineteen patients had a de novo AML, whereas 26 patients had a secondary AML (18 after MDS, 3 after a CMPD, 2 after myelofibrosis, 3 after chemo-radiotherapy for a breast cancer). To identify possible biomarkers associated to sensitivity/resistance, global gene and miRNA expression profiling (Affymetrix Transciptome 2.0) was performed on purified AML cells. Induction-period mortality was 17%, with 8 deaths occurring during cycle 1. Thirty-seven patients completed at least one cycle of therapy and are evaluable for response. Overall CR rate was 43% among evaluable patients. Nine out of 16 responding patients are still in CR after a median follow-up of 12 months (range: 2-39). Statistical analysis showed that responding patients had a longer median overall survival than non-responders (428 vs. 74 days, P = .000). Conversely, by studying the global miRNA and gene expression profile we identified a molecular signature, including 114 genes and 18 miRNA associated with the clinical response (CR vs. no CR). Of note, the involved genes belonged to relevant functional categories such as angiogenesis, cell cycle regulation and immune response. Of note, based on the expression of 5 genes, we developed an algorithm to predict treatment response that was successfully validated by showing an 87% overall accuracy. In conclusion, low-dose lenalidomide plus low-dose cytarabine has high clinical activity, predictable by GEP, in elderly AML patients with poor prognosis. The study was registered at EMA (EUDRA-CT 2008-006790-33). Acknowledgments Celgene is acknowledged for providing Lenalidomide for the patients. The study was supported in part by AIL Pesaro Onlus. Disclosures: No relevant conflicts of interest to declare.

Description: 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.