Search

Simple Summary The Epstein–Barr virus (EBV) is a commonly occurring virus, infecting more than 90% of the world population, often early in life. However, only a minority of individuals develop EBV-driven diseases at some point in their lifetime. EBV is associated with several neoplasms including epithelial, mesenchymal and lymphoid tumors. EBV-driven lymphoid proliferations encompass a wide spectrum of diseases with different biological behaviors, developing frequently, although not always, in conditions of immunosuppression. The diagnosis is often complicated and requires a strict combination of clinical, pathological and molecular findings. The aim of this review, divided into three parts, is to provide an update on EBV-driven lymphoproliferative disorders arising in the gastrointestinal tract. In this review, we discuss the chronic active EBV infection of T-cell and NK-cell type, its systemic form; extranodal NK/T-cell lymphoma, nasal type and post-transplant lymphoproliferative disorders. Abstract EBV is the first known oncogenic virus involved in the development of several tumors. The majority of the global population are infected with the virus early in life and the virus persists throughout life, in a latent stage, and usually within B lymphocytes. Despite the worldwide diffusion of EBV infection, EBV-associated diseases develop in only in a small subset of individuals often when conditions of immunosuppression disrupt the balance between the infection and host immune system. EBV-driven lymphoid proliferations are either of B-cell or T/NK-cell origin, and range from disorders with an indolent behavior to aggressive lymphomas. In this review, which is divided in three parts, we provide an update of EBV-associated lymphoid disorders developing in the gastrointestinal tract, often representing a challenging diagnostic and therapeutic issue. Our aim is to provide a practical diagnostic approach to clinicians and pathologists who face this complex spectrum of disorders in their daily practice. In this part of the review, the chronic active EBV infection of T-cell and NK-cell type, its systemic form; extranodal NK/T-cell lymphoma, nasal type and post-transplant lymphoproliferative disorders are discussed.

This abstract was not presented at the conference. Citation Format: Gasparini E, Bisagni A, Di Cicilia R, Kuhn E, Falco G, Ferrari G, Foroni M, Tamagnini I, Bassano C, Ragazzi M, Gardini G, Cecchi F, Hembrough T, Bisagni G. Not presented [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-10-24.

Introduction Pulmonary Sarcomatoid Carcinoma (PSC) is a rare subset of NSCLC, associated with worse prognosis and resistant to platinum-based regimens. Recent investigations have shown high levels of PD-L1 expression in PSC, providing a rationale for the potential use of immunotherapy. In this study, we investigated whether the PD-L1 expression was related to clinico-pathologic and molecular characteristics. Materials and methods Fortythree surgically-resected PSCs were selected from 2006 to 2014 and clinical information retrieved. PD-L1 expression was analyzed by immunohistochemistry and correlated with the clinic-pathologic features and driver gene mutations analyzed by Next-Generation-Sequencing. Correlation of clinical, pathological and genetic variants with PD-L1 expression positivity were tested by Fisher’s exact test analysis. Results About 25% of PSCs showed a significant expression of PD-L1 (positive staining defined as staining in ≥10% of tumor cells). PD-L1 expression was associated with aggressive pathological features of PSCs including N2-involvement (PD-L1 positive in 83.3% of N2-PSCs vs in 16.2% of N0/N1-PSCs, p = 0.003) and presence of either local (p = 0.038) and distant metastases (p = 0.022). Furthermore, PD-L1 expression was significantly associated with the overall mutational load of the tumors (PD-L1 positivity only in PSCs with at least one mutational event) and in particular with the presence of KRAS mutation (PD-L1 positive in 44.4% of KRAS-Mut PSCs vs 12.0% in KRAS-Wild PSCs). The correlation between PD-L1 expression and KRAS-mutation were found at univariate analysis (p = 0.031), even considering PD-L1 as a continuous variable (p = 0.018), and confirmed at multivariate analysis (p = 0.035). The mutational status of the other genes explored in the NGS-panel (EGFR, APC, PTEN, PIK3CA, TP53 and STK11) did not correlate with PD-L1 expression. Conclusions PD-L1 expression significantly correlates with overall mutational load and KRAS mutational status in pulmonary sarcomatoid carcinomas.

Purpose The new ASCO/CAP guidelines published in 2013 (AC2013) significantly modified the scoring criteria for HER2-FISH, introducing the most controversial change to the HER2-equivocal category. We retrospectively evaluated the impact of AC2013 in a cohort of consecutive invasive breast cancers (IBCs) analyzed with frontline dual-color FISH. Methods 2788 consecutive IBCs were reclassified based on the AC2013 guidelines. Clinico-pathological features of equivocal IBCs were compared with HER2-negative and HER2-positive IBCs. FISH HER2-equivocal cases underwent reflex tests: HER2-IHC, RARA-FISH, and SMS-FISH. Overall and disease-free survivals were evaluated in AC2007 HER2-positive patients treated with trastuzumab and in patients that became eligible for target-therapy according to AC2013. Results Two-hundred HER2-negative cases (7.2%) were classified differently, following AC2013: 0.3% (8/2788) became HER2-positive and 6.9% (192/2788) HER2-equivocal. AC2013, compared with AC2007, significantly increased initial HER2-equivocal cases (6.9%vs1.6%, p

Diffuse large-B cell lymphomas (DLBCL) and follicular lymphomas (FL) are the most represented subtypes among mature B-cell neoplasms and originate from malignant B lymphocytes. Methylation represents one of the major epigenetic mechanisms of gene regulation. Silent information regulator 1 (SIRT1) is a class III lysine-deacetylase playing several functions and considered to be a context-dependent tumor promoter. We present the quantitative methylation, gene expression and tissue distribution of SIRT1 and some key mediators related to lymphoma pathogenesis in B lymphocytes purified from biopsies of follicular hyperplasias, FL and DLBCL. SIRT1 mRNA levels are higher in FL than follicular hyperplasias and DLBCL. B cell lymphoma 6 (BCL6) positively correlates with SIRT1. SIRT1 promoter shows a methylation decrease in the order: follicular hyperplasia - FL - DLBCL. Kruppel-like factor 4 (KLF4), Death-associated protein kinase 1 (DAPK1) and Spastic Paraplegia 20 (SPG20) methylation increase significantly in FL and DLBCL compared to follicular hyperplasias. Gene expression of DAPK1 and SPG20 inversely correlates with their degree of methylation. Our findings evidence a positive correlation between SIRT1 and BCL6 expression increase in FL. SIRT1 methylation decreases in FL and DLBCL accordingly and this parallels the increase of KLF4, DAPK1 and SPG20 methylation.

δ‑like ligand 4 (DLL4)‑Notch signaling is associated with tumor resistance to anti‑vascular endothelial growth factor (VEGF) therapy. Furthermore, Notch signaling is critical for the maintenance of colon cancer stem cells (CSCs), which are relevant in drug resistance and tumor angiogenesis. CD44 is a transmembrane glycoprotein and is considered a putative marker of CSCs. To assess the association of Notch intracellular cleaved domain (NICD), DLL4 and CD44 expression with the efficacy of anti‑angiogenic drugs, a series of samples derived from patients with advanced colon cancer enrolled in prospective clinical trials were analyzed. Histological samples from 51 primary tumors that originated from patients treated with bevacizumab‑based first‑line chemotherapy were analyzed by immunohistochemistry for NICD, DLL4 and CD44 expression, and CD31 for microvessel count. The expression levels of genes relevant for angiogenesis [angiopoietin (ANGPT)1, ANGPT2, fibroblast growth factor (FGF)1, FGF2, epidermal growth factor, placental growth factor, VEGFA and DLL4] were detected by reverse transcription‑quantitative PCR using RNA extracted from the frozen tissues of four tumors with low and four tumors with high NICD expression. Strong NICD levels were observed in 12/51 (24%) of the patients, whereas 16/51 (31%) of the colon cancer subjects exhibited high CD44 expression. Strong CD44 staining was associated with high NICD levels compared with the CD44 expression levels noted in samples with low NICD levels (67 vs. 20%, P=0.005). No association was observed with regards to the expression levels of NICD, CD44 and the other aforementioned biomarkers. High expression levels of NICD and CD44 predicted reduced progression‑free survival (P

Objective Data on the presence of varicella-zoster virus (VZV) in temporal arteries of patients with giant cell arteritis (GCA) are controversial. We analyzed VZV infection in temporal arteries from Italian patients with temporal artery biopsy (TAB)-positive GCA, TAB-negative GCA, and controls. Methods A total of 79 formalin-fixed, paraffin-embedded (FFPE) TABs performed between 2009 and 2012 at a single institution from 34 TAB-positive GCA patients, 15 TAB-negative GCA patients, and 30 controls were retrieved. Six 5-μm sections of all FFPE TABs were cut. The first section was analyzed by immunohistochemistry using mouse monoclonal anti-VZVgE IgG1 antibody. DNA was extracted from the remaining five sections and analyzed by real-time polymerase chain reaction (PCR) for the presence of VZV DNA. For 10 of the 34 TAB-positive GCA patients, an additional 2-mm piece of frozen TAB was available. DNA was extracted from the entire 2-mm length frozen specimen and analyzed by PCR for the presence of VZV DNA. Thirty additional 5-μm sections were cut from the FFPE TABs of these 10 patients and analyzed by immunohistochemistry for the presence of VZV antigen. Results Immunohistochemical analysis detected VZV antigen in 1/34 (3%) TAB-positive GCA, 0/15 TAB-negative GCA, and 0/30 controls, and in none of the 300 sections cut from the 10 FFPE TABs positive for GCA for which the frozen specimens were available. DNA obtained from all TABs was amplifiable. VZV DNA was neither found in any of the FFPE TABs nor found in frozen TABs. Conclusion Our data do not support in Italian patients a possible role for VZV infection in the etiopathogenesis of GCA.

Immunohistochemistry (IHC) is a widely-tested, low-cost and rapid ancillary technique available in all laboratories of pathology. This method is generally used for diagnostic purposes, but several studies have investigated the sensitivity and specificity of different immunohistochemical antibodies as a surrogate test in the determination of predictive biomarkers in non-small cell lung cancer (NSCLC), particularly for Epidermal Growth Factor Receptor (EGFR) gene mutations, Anaplastic Lymphoma Kinase (ALK) gene and ROS1 rearrangements. In this review, a critical examination of the works comparing the consistency of IHC expression and conventional molecular techniques to identify genetic alterations with predictive value in NSCLC is discussed. Summarizing, data on sensitivity and specificity of antibodies against ALK and ROS1 are very consistent and time has come to trust in IHC at least as a cost-effective screening tool to identify patients with rearranged tumors in clinical practice. On the other hand, mutant-specific antibodies against EGFR demonstrate a good specificity but a lowto- fair sensitivity, raising some cautions on their employment as robust predictive biomarkers. A brief comment on preliminary experiences with antibodies against BRAF, RET, HER2 and c-MET is also included.

The transdifferentiation of epithelial cells toward a mesenchymal condition (EMT) is a complex process that allows tumor cells to migrate to ectopic sites. Cadherins are not just structural proteins, but they act as sensors of the surrounding microenvironment and as signaling centers for cellular pathways. However, the molecular mechanisms underlying these signaling functions remain poorly characterized. Cadherin-6 (CDH6) is a type 2 cadherin, which drives EMT during embryonic development and it is aberrantly re-activated in cancer. We recently showed that CDH6 is a TGFβ target and an EMT marker in thyroid cancer, suggesting a role for this protein in the progression of this type of tumor. Papillary thyroid carcinomas (PTCs) are usually indolent lesions. However, metastatic spreading occurs in about 5% of the cases. The identification of molecular markers that could early predict the metastatic potential of these lesions would be strategic to design more tailored approaches and reduce patients overtreatment. In this work, we assessed the role of CDH6 in the metastatic progression of thyroid cancer. We showed that loss of CDH6 expression profoundly changes cellular architecture, alters the inter-cellular interaction modalities and attenuates EMT features in thyroid cancer cells. Using a yeast two-hybrid screening approach, based on a thyroid cancer patients library, we showed that CDH6 directly interacts with GABARAP, BNIP3 and BNIP3L, and that through these interactions CDH6 restrains autophagy and promotes re-organization of mitochondrial network through a DRP1-mediated mechanism. Analysis of the LIR domains suggests that the interaction with the autophagic machinery may be a common feature of many cadherin family members. Finally, the analysis of CDH6 expression in a unique cohort of human PTCs showed that CDH6 expression marks specifically EMT cells. and it is strongly associated with metastatic behavior and worse outcome of PTCs.

AimsIdentification of epidermal growth factor receptor (EGFR) mutations in lung adenocarcinomas is the single most important predictor of clinical response and outcome using EGFR tyrosine kinase inhibitors (TKIs). EGFR E746-A750del and L858R mutations are the most common gene alterations, also predicting the best clinical response to TKIs. We evaluated the accuracy of EGFR mutation-specific antibodies in a large cohort of lung adenocarcinomas, with different molecular settings and types of tissue samples.Methods300 lung adenocarcinomas diagnosed on cytology (48 cell blocks), biopsy (157 cases) and surgical resections (95 cases) were selected. All cases were investigated for EGFR by sequencing and two mutation-specific antibodies (clone 6B6 for E746-A750del; clone 43B2 for L858R) were tested using an automated immunostainer. Discordant results were investigated by next-generation sequencing (NGS).ResultsOverall sensitivity and specificity of mutant-specific antibodies were 58.6% and 98.0%, respectively, and they increased up to 84% and 100% if only tumours harbouring E746-A750del were considered. In 13 discordant cases, NGS confirmed immunohistochemistry results in eight samples.ConclusionsThe EGFR mutation-specific antibodies have a fair/good sensitivity and good/high specificity in identifying classic mutations, but they cannot replace molecular tests. The antibodies work equally well on biopsies and cell blocks, possibly permitting a rapid screening in cases with poor material.

Resveratrol (RSV), a plant-derived stilbene, induces cell death in Hodgkin lymphoma (HL)-derived L-428 cells in a dose-dependent manner (IC50 = 27 μM, trypan blue exclusion assay). At a lower range (25 μM), RSV treatment for 48 hr causes arrest in the S-phase of the cell cycle, while at a higher concentration range (50 μM), apoptosis can be detected, with activation of caspase-3. The histone/protein deacetylase SIRT1 has been described as a putative target of RSV action in other model systems, even though its role in cancer cells is still controversial. Here we show that RSV, at both concentration ranges, leads to a marked increase in p53, while a decrease of SIRT1 expression level, as well as enzyme activity, only occurred at the higher concentration range. Concomitantly, however, treatments at both concentration ranges resulted in a marked increase in K373-acetylated p53 and lysine-acetylated FOXO3a. Immunohistochemical stainings of human lymph nodes show a preferential distribution of SIRT1 in the germinal center of the follicles while the mantle zone shows nearly no staining to few positive cells. The classical HL-affected lymph nodes show a strong positivity of the diagnostic Hodgkin Reed-Sternberg cells. Notably, both the HL-derived cell lines and the Hodgkin Reed-Sternberg cells of the affected lymph nodes derive from germinal center-derived B cells. The study of SIRT1 distribution and expression on a larger number of biopsies might disclose a novel role for this histone/protein deacetylase as therapeutic target.

BACKGROUND AND STUDY AIMS: The study aimed to investigate whether the 25G needle is superior to the 22G needle when used in endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) of solid lesions. PATIENTS AND METHODS: The study was a single-center randomized clinical trial. The setting was a tertiary referral hospital, where EUS-FNA of solid lesions was assisted by an on-site cytopathologist, who was blinded to the needle size. The main end point was the number of passes performed to obtain adequate samples. Crossover to the other type of needle was allowed after five passes, or when the gastroenterologist experienced difficulties in puncturing the lesions. RESULTS: A total of 129 solid lesions were randomized and data regarding 127 lesions were analyzed. The mean number of passes was 3.7 (± 1.9) in the 22G needle group and 3.8 (± 2) in the 25G needle groups (difference of means: 0.1; 95 %CI: – 0.59 to 0.79). Fifty-eight of 63 (92.1 %) and 60/64 samples (93.7 %) in the 22G and 25G needle groups respectively were adequate (difference: – 1.6 %; 95 %CI: – 12.1 % to 8.9 %). Crossover to the other type of needle was performed in 11/63 (17.5 %) and in 12/64 (18.7 %) lesions in the two groups respectively (difference: – 1.2 %; 95 %CI: – 16.2 % to 13.8 %). A crossover to the 25G needle was successfully performed in four masses in the uncinate process; these lesions were difficult to puncture using the 22G needle. CONCLUSIONS: Our study failed to demonstrate that the 25G is more effective than the 22G needle in EUS-FNA of solid lesions. However, targeting of lesions in the distal duodenum may be simplified by using the 25G needle.

e12643Background: Around 40% of HER2-positive (HER2+) breast cancer patients who receive trastuzumab-based neoadjuvant therapy (TNT) achieve pCR (the FDA-recommended outcome measure in this setting...

Aim: To assess the role of Notch activation in predicting bevacizumab efficacy in colorectal cancer (CRC). Materials & methods: Notch activation was evaluated by immunohistochemistry (IHC) on 65 CRC enrolled within randomized clinical trials assessing first-line bevacizumab-based chemotherapy and on 21 CRC treated with chemotherapy alone. Results: Strong Notch (IHC 3+) activation was negatively associated with response (18 vs 62% in low Notch cases [IHC 0, 1, 2+]; p = 0.016), progression-free survival (4.9 vs 12.1 months; p = 0.002) and overall survival (19.3 vs 30.4 months; p = 0.039). No correlation was found between Notch activation and clinical outcome in CRC treated with chemotherapy alone. Conclusion: A potential role of Notch activation in the antitumor activity of bevacizumab could be hypothesized.

1028 Background: ASCO/CAP new guidelines published in 2013 (AC2013) significantly modified the scoring criteria for HER2-FISH. We retrospectively evaluated the impact of AC2013 in a five-year cohort of consecutive invasive breast cancers (IBCs) underwent frontline dual-color FISH. Furthermore, we applied three different reflex tests and investigated clinical outcomes of patients with HER2-equivocal IBC. Methods: 2788 consecutive IBCs that underwent frontline HER2/CEP17 determination in our institution from January 2009 to December 2013 were reclassified based on the AC2013 guidelines. FISH HER2-equivocal cases underwent reflex tests: HER2-IHC, RARA-FISH, and SMS-FISH. Clinico-pathological correlation was performed. Results: Two hundred HER2-negative cases (7.2%) were classified differently based on the AC2013: 0.3% (8/2788) became HER2-positive and 6.9% (192/2788) HER2-equivocal. AC2013 equivocal-IBCs represented a subgroup of grade 3, luminal-like subtype IBCs, in patients with a higher age. After reflex tests, among 190 equivocal cases 102 (53.7%) were reclassified as HER2-positive, 51 (26.8%) negative and 37 (19.5%) equivocal. IHC resulted negative in 44.7% (85), whereas SMS-FISH showed the highest percentage of positive results (45.8%). No statistically significant differences were identified in the disease-free and overall survival. Conclusions: AC2013 compared with AC2007 significantly increased initial HER2-equivocal cases (6.9%vs1.6%, p < 0.001). After reflex testing, 4.5% of patients not treated with anti-HER2 therapy (either HER2-positive or “ultimate equivocal”) resulted eligible to trastuzumab, but showed clinical outcome comparable with AC2007 HER2-positive patients, treated with trastuzumab. Our findings belittle the clinical impact of AC2013 HER2-equivocal reclassification; accordingly further studies are necessary to justify this category and the reclassification efforts by additional reflex tests.

Modifications in adhesion molecules profile may change the way tumor cells interact with the surrounding microenvironment. The Cadherin family is a large group of transmembrane proteins that dictate the specificity of the cellular interactions. The Cadherin switch that takes place during epithelial-mesenchymal transition (EMT) contributes to loosening the rigid organization of epithelial tissues and to enhancing motility and invasiveness of tumor cells. Recently, we found Cadherin-6 (CDH6, also known as K-CAD) highly expressed in thyroid tumor cells that display mesenchymal features and aggressive phenotype, following the overexpression of the transcriptional regulator Id1. In this work, we explored the possibility that CDH6 is part of the EMT program in thyroid tumors. We demonstrate that CDH6 is a new transforming growth factor-β (TGF-β) target and that its expression is modulated similarly to other EMT mesenchymal markers, both in vitro and in thyroid tumor patients. We show for the first time that CDH6 is expressed in human thyroid carcinomas and that its expression is enhanced at the invasive front of the tumor. Finally, we show that CDH6 is under the control of the transcription factor RUNX2, which we previously described as a crucial mediator of the Id1 pro-invasive function in thyroid tumor cells. Overall, these observations provide novel information on the mechanism of the EMT program in tumor progression and indicate CDH6 as a potential regulator of invasiveness in thyroid tumors.

Background. DNA methylation is one of the best studied epigenetic modifications and one major constituent of the epigenome of a cell. It contributes to normal development as well to carcinogenesis. Nowadays, many efforts are being made in order to use DNA methylation as a biomarker. The aim of our work is to characterize the expression and methylation of SIRT1, HIC1, BCL6, KLF4 and other genes relevant for Non-Hodgkin lymphomas (NHL) pathogenesis. Methods. Immunohistochemistry (IHC) on 72 formalin-fixed paraffin embedded tissue sections (FFPE). B-lymphocytes were purified from 36 biopsies of follicular hyperplasias (non-malignant B-lymphocytes), follicular lymphomas (FL) and diffuse large B-cell lymphomas (DLBCL). Gene expression were analysed by quantitative retrotranscribedPCR (qRTPCR). Quantitative CpG promoter methylation analysis was performed by pyrosequencing after bisulfite conversion or by Methyl II array qPCR on genomic DNA. Results. In a total of 72 FFPE samples of follicular hyperplasias (n = 17), FL (n = 36) and DLBCL (n = 19), SIRT1 staining is localized in the germinal center of the majority of follicular hyperplasias and FL samples. SIRT1 localizes preferentially in the centroblasts of the GC of the follicles where it correlates with Ki67. BCL6 is uniformly positive in follicular hyperplasias and FL, but heterogeneously distributed in DLBCL. Interestingly, SIRT1 and BCL6 expression correlate in FL. By quantitative pyrosequencing we analyzed 3 CpG sites for the SIRT1 promoter (corresponding to the binding sites for CREB, ARID and PPARG transcription factors). Follicular hyperplasias display higher methylation levels (52.88%) than FL (38.36%) and DLBCL (32.65%) on SIRT1 promoter suggesting a possible inverse correlation between tumor aggressiveness and SIRT1 methylation. Next, we selected a panel of genes whose expression is linked to lymphoma pathogenesis. By Methyl II array qPCR, we show that BCL6 methylation does not vary among samples. KLF4, DAPK1 and SPG20, show statistically significant methylation increases in FL and DLBCL compared to follicular hyperplasias, indicating a possible role of these proteins in lymphoma pathogenesis. On the contrary, no significant differences are observed for the other markers MZB1, MGMT, LMO2 and ASXL1. Notably, KLF4, DAPK1 and SPG20 mRNA expression levels anti-correlate with their promoter methylation in FL. Conclusions. Epigenetic changes in SIRT1 methylation inversely correlate with NHL aggressiveness (decreasing in the order: follicular hyperplasias - FL - DLBCL), while KLF4, DAPK1 and SPG20 show a methylation increase that correlates with tumor aggressiveness. These data suggest that different patterns of methylation correlate with the clinical and prognostic parameters of these NHL subtypes. Citation Format: Raffaele Frazzi, Eleonora Zanetti, Mariaelena Pistoni, Ione Tamagnini, Riccardo Valli, Francesco Merli. Different patterns of SIRT1, KLF4, DAPK1 and SPG20 methylation in B lymphocytes correlate with the clinical parameters of non-Hodgkin lymphoma subtypes. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4451.

e23007Background: Notch pathway has been suggested to play an important role in regulating cancer stem cells (CSCs) in colon cancer. CSCs are responsible for colon cancer initiation, progression an...

Context: The ability of tumor cells to invade adjacent tissues is governed by a complicated network of molecular signals, most of which have not yet been identified. In a recent work, we reported that the transcriptional regulator Id1 contributes to thyroid cancer progression by powering the invasion capacity of tumor cells. Objective: The intent of this work was to further investigate the biology of invasive thyroid tumors, through the analysis of the molecular interactions existing between Id1 and some of its target genes and through the characterization of the function of these factors in the progression of thyroid tumors. Results: We showed that Id1 controls the expression of the Runx2 isoform I and that this transcription factor plays a central role in mediating the Id1 proinvasive function in thyroid tumor cells. We demonstrated that Runx2 regulates proliferation, migration, and invasiveness by activating a panel of genes involved in matrix degradation and cellular invasion, which we previously identified as Id1 target genes in thyroid tumor cells. Finally, we show that Runx2 is strongly expressed in metastatic human thyroid tumors both at the primary site and in metastases. Conclusion: Overall, our experiments demonstrate the existence of a previously unknown molecular axis that controls thyroid tumor invasiveness by altering the ability of tumor cells to interact with the surrounding microenvironment. These factors could prove to be valuable markers that permit early diagnosis of aggressive thyroid tumors.

612 Background: Antiangiogenic therapies represent a well established additional treatment to standard chemotherapy, nevertheless no markers are available to suggest a successful outcome linked to the use of bevacizumab. To investigate potential mechanisms of resistance to angiogenesis inhibitor bevacizumab, Notch expression was correlated with response and survival in a series of bevacizumab treated advanced colorectal cancer (CRC) patients. Methods: Notch expression was evaluated by immunohistochemistry (IHC) on 65 primary CRC enrolled within 6 randomized clinical trials assessing first-line bevacizumab plus chemotherapy. Notch IHC was conducted using a polyclonal antibody to Cleaved Notch1 (Cell Signaling Technology, Danvers, MA). Notch expression was scored based on intensity of staining (0: none, 1+: weak, 2+: moderate; 3+: strong) and on percentage of immunostained cells. A control series of 21 advanced CRC treated with chemotherapy alone was also examined. Results: Notch positivity was localized to the cytoplasm or nucleus of malignant epithelial cells. In all, 11 of 61 (18%) evaluable primary tumours had a high Notch expression (IHC 3+). Six of the 11 cases (55%) with high Notch expression (IHC 3+) experienced progressive disease compared with 5 of 50 (10%) low Notch expression cases (IHC 0 1+ 2+) (p = 0.003). A high Notch expression also demonstrated an inferior median PFS (4.9 vs. 12.1 months; HR = 2.51; 95% CI, 0.96 to 6.58; p = 0.007) and OS (19.3 vs. 30.4 months; HR = 2.21; 95% CI, 0.79 to 6.15; p = 0.039) compared with low Notch expression cases. When the groups were further analyzed considering VEGF expression, the best outcome was found in low Notch (IHC 0 1 +) and high VEGF expressing tumors (IHC 2+ 3+) (response rate 9 of 11, 82 % vs. 1 of 5, 20%, in patients with high levels of Notch and VEGF expression, respectively). No correlation was found between Notch expression and clinical response in the series of patients treated with chemotherapy without bevacizumab. Conclusions: Notwithstanding the limited power of the present analysis, these data seem to suggest that low Notch expression might be a marker for successful bevacizumab treatment.

e19035 Background: Identification in lung adenocarcinomas (LACs) of epidermal growth factor receptor (EGFR) mutations is the single most important predictor of clinical response and outcome using EGFR tyrosine kinase inhibitors (TKI). We evaluated the accuracy of EGFR mutation-specific antibodies in LACs and showing different molecular settings and detected on cytology and histologic samples. Methods: 111 LACs diagnosed on cytology (21 cell blocks), biopsy (58 cases) and surgical resections (32 cases) were selected for the study. All cases were previously investigated by Sanger sequencing and/or pyrosequencing (EGFR exons 18 to 21; KRAS exon 2) and ALK status by Immunohistochemistry (IHC)/FISH. IHC using EGFR mutation-specific antibodies (clone 6B6 for delE746-A750 and clone 43B2 for L858R; Cell Signalling Technologies, Danvers, MA) were tested using an automated immunostainer (Benchmark, Ventana Inc, Tucson, AZ). Cases were quoted as positive when at least 2+ staining was present in at least 5% of tumor ...

Background: In order to investigate mechanisms of resistance to angiogenesis inhibitors, Notch and Delta-like 4 ligand (DLL4) expression was correlated with response and survival in a series of bevacizumab treated advanced colon cancer patients. DLL4-mediated Notch signalling has recently emerged as an attractive target for angiogenesis-based cancer therapies, given that DLL4 is an important component of Notch-mediated stem cell self-renewal and vascular development. DLL4-induced Notch signalling mediates tumour-resistance to anti-VEGF therapy by inducing the formation of large vessels and activating multiple pathways in preclinical models. Method: Notch and DLL4 expression was evaluated by immunohistochemistry (IHC) on 65 primary colon cancer patients enrolled within randomized clinical trials assessing first-line bevacizumab plus chemotherapy. Results: Notch positivity was localized to the cytoplasm of malignant epithelial cells. In all, 10/60 (17%) evaluable primary tumours had a high Notch expression. Five of the 10 cases (50%) with high Notch expression experienced progressive disease compared with 5/49 (10%) Notch negative cases (p=0.008). Median progression-free survival (PFS) was 2.8 months for Notch positive cases compared with 13.07 months for Notch negative cases (p=0.045). Membranous and/or cytoplasmic DLL4 immunoreactivity of tumour vessels was observed in 30/56 (54%) evaluable colon cancers. No correlation was found between DLL4 expression and clinical outcome. Conclusion: Clinical trials investigating the therapeutic efficacy of bevacizumab in colon cancer did not explore the impact of DLL4-Notch pathway on response and clinical outcome. Our results seem to suggest that high Notch expression might be involved in tumour resistance in colon cancer patients treated with bevacizumab. Citation Format: Francesca Negri, Cecilia Bozzetti, Pellegrino Crafa, Costanza Lagrasta, Stefano Cavalli, Giuseppe Pedrazzi, Giorgio Gardini, Ione Tamagnini, Rosa Porzio, Luigi Cavanna, Carlo Paties, Ida Romano, Antonino Musolino, Gianluca Tomasello, Pier Giorgio Petronini, Andrea Ardizzoni. Notch and DLL4 expression in bevacizumab-treated colon cancer patients. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4646. doi:10.1158/1538-7445.AM2013-4646 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

Introduction. SIRT1 is a histone/protein deacetylase belonging to the family of Sirtuins and is the human homologue of the yeast Sir2 enzyme1. Histone deacetylases (HDACs) play a key role in several cancer-related mechanisms and the evidences of the efficacy of HDACs inhibitors in the treatment of lymphomas is rapidly growing2. SIRT1 binds and deacetylates the master transcriptional regulator Bcl-6 with implications in the pathogenesis of diffuse large B-cell lymphoma3. Ki67 is the proliferation index and is a diagnostic and useful marker currently used in the pathological evaluation of lymphoma samples4. Our aim is the characterization of SIRT1 in the B lymphocytes derived from follicular lymphomas (FL) or follicular hyperplasias and their comparison to Ki67, Bcl-6 and HIC-1. Methods. Immunohistochemical stainings (IHC) have been performed on a total of 61 formalin fixed paraffin embedded (FFPE) tissue sections including 36 FL and 25 follicular hyperplasias. All these FFPE samples were stained also for the proliferation index Ki67/MIB1. HIC-1 was also evaluated on 36 FL and 17 follicular hyperplasias. IHCs have been evaluated independently by two pathologists. B lymphocytes were immunomagnetically sorted starting from frozen biopsies collected in a Tissue Bank. Flow cytometry was used to determine the phenotype of the purified B populations. Genomic DNA and total RNA were extracted from purified B lymphocytes. Real-time, quantitative PCR (qPCR) was performed with Evagreen. qPCR was also performed on 4 samples of peripheral blood mononuclear cells (PBMCs) used as a reference. Data analysis and statistics were performed with GraphPad Prism 5. Results. IHCs show that SIRT1 localizes preferentially in the centroblasts of the follicles. In the 36 FL analyzed, SIRT1 is expressed in 33/36 cases (91.7%) and is stronger in the centroblasts of 23/36 cases (63.9%). Interestingly, the Ki67 staining correlates positively with SIRT1 in the FL where SIRT1 localizes in the centroblasts. However, SIRT1 positivity does not correlate with FL grade in our cohort. HIC1 reactivity in the same cohorts of samples resulted only in a weak staining of the stroma but the lymphocytes were negative. In order to investigate the expression levels of the two transcriptional variants of SIRT1 (SIRT1_001 and SIRT1_002) and Bcl-6 in the tumoral lymphocytes, we sorted and purified B lymphocytes from a total of 24 biopsies of FL and 10 follicular hyperplasias. qPCR revealed that FL have a statistically significant higher SIRT1_001 expression when compared to follicular hyperplasias and PBMCs. Furthermore, the FL having a Bcl-6 fold increase higher than 10 have also SIRT1_001 significantly higher than the FL with a Bcl-6 fold increase less than 10. Conclusions. Collectively, our data show that Ki67 positivity correlates with SIRT1 localization in the nuclei of the centroblasts. Interestingly, the transcriptional isoform SIRT1_001 is higher in the B lymphocytes of FL than in follicular hyperplasias and seems also to be positively correlated to Bcl-6 overexpression in FL samples. Our investigations are now aimed at defining the significance of these data in terms of epigenetic regulation of key gene promoters in the tumoral B lymphocytes. 1 Heltweg, B. et al.Cancer research66, 4368-4377, doi:10.1158/0008-5472.CAN-05-3617 (2006). 2 Murawski, N. & Pfreundschuh, M. The lancet oncology11, 1074-1085, doi:10.1016/S1470-2045(10)70210-2 (2010). 3 Liu, T., Liu, P. Y. & Marshall, G. M. Cancer research69, 1702-1705, doi:10.1158/0008-5472.CAN-08-3365 (2009). 4 Yamamoto, E. et al.Cancer science104, 1670-1674, doi:10.1111/cas.12288 (2013). Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.