Citations

Abstract Targeting membrane PD-1 molecules expressed by tumor-reactive T cells is gaining acceptance as a potentially effective anti-tumor immunotherapy. PD-1 blockade mediated by monoclonal antibodies has yielded promising therapeutic effects in treatment of melanoma, lung cancer and kidney cancers. Although detecting PD-1 expression by T cells is relatively straightforward, a simple and reliable method for determining whether PD-1 on T cells has engaged its ligand B7-H1 (PD-L1) is wanting. Our previous studies have revealed that engagement of PD-1 or B7-1 by B7-H1 results in alternations of apoptosis signaling pathway by up-regulating pro-apoptotic molecules among activated T cells and are correlated with B7-H1-mediated T cell death. Those observations suggest that intracellular levels of apoptosis-related Bcl2 family molecules among PD-1 positive CD8 T cells may be barometers of the extent to which PD-1 has been triggered by B7-H1. Using PD-1 and B7-H1 deficient animal models, we found that lower levels of intracellular pro-apoptosis molecules identify those activated T cells whose PD-1 molecules have not yet been extensively engaged, thus T cell function might be restored to their normal function once PD-1 signals from B7-H1 are blocked. Similarly, human PD-1 positive CD8 T cells engaged by B7-H1 also expressed higher levels of pro-apoptosis molecules during antigen stimulation. Our clinical data demonstrated that pro-apoptosis molecule expression by tumor-reactive T cell levels are higher among advanced melanoma and prostate cancers than healthy controls, reflecting chronic engagement with B7-H1. Thus, using pro-apoptosis status as signaling biomarkers for T cell PD-1 engagement, it may be possible to select patients who are most likely to have strong benefit from PD-1 or B7-H1 (PD-L1) blockade therapy. Citation Format: Wei Zhao, Haidong Dong. T cell apoptosis signaling biomarker of PD-1 engagement in cancer patients. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2552. doi:10.1158/1538-7445.AM2014-2552

Abstract The mechanisms by which ovarian cancer cells are released from the primary tumor, seed throughout the peritoneal cavity, attach to local organs, and then invade these organs, are not understood. In this study, the cell adhesion molecule, Nectin-4, was investigated as a potential mediator of several steps involved in ovarian cancer progression. In particular, due to the ability of Nectin-4 to promote cell-cell adhesions, we were interested in determining its role in mediating the formation of cell-cell aggregates (spheroids) which are commonly seen in the peritoneal fluid of ovarian cancer patients. Furthermore, since spheroids are known to have a decreased rate of cell proliferation and are chemoresistant, we were also interested in the role of Nectin-4 in ovarian cancer cell proliferation and invasion. In our previous studies, we performed gene microarray analysis and identified Nectin-4 overexpression in ovarian cancer tissues compared to normal ovaries and other normal tissues. By ELISA, we found soluble Nectin-4 in the sera of 50% of women with ovarian cancer. In this study, we performed a series of experiments in which two human ovarian cancer cells lines were transfected with Nectin-4 or shRNA targeting Nectin-4, and then the resultant cells were tested in functional assays. In the first case, MA148 cells, which do not express Nectin-4, were transfected with full-length Nectin-4. The resultant MA148 cells which expressed high levels of Nectin-4 showed an increased rate of proliferation compared to control cells which did not express Nectin-4. They also formed the initial cell-cell adhesions involved in spheroid formation faster than control cells. Furthermore, the spheroids which expressed Nectin-4 were slower to disaggregate and invade through monolayers of mesothelial cells. In the second case, NIH:OVCAR5 cells, which express moderate levels of Nectin-4, were transfected with shRNA targeting Nectin-4, resulting in the partial knockdown of Nectin-4 expression. We found that the NIH:OVCAR5 cells that express lower levels of Nectin-4 on their surface required a substantially longer time to form spheroids and migrated more slowly in a wound healing assay. In both cases, we verified the expression of Nectin-4 in the transfected cells by Western immunoblotting and flow cytometry. These results suggest that Nectin-4: (a) is important in the early events of cell-cell adhesion, (b) plays a role in multicellular aggregation within the ascites of ovarian cancer patients, and (c) causes tight spheroid formations that may impede disaggregation. Additional functional studies leading to a better understanding of the role of Nectin-4 overexpression and shedding in ovarian cancer are currently underway. Understanding the role of Nectin-4 in ovarian cancer progression is critical in order to facilitate its development as a novel therapeutic target for ovarian cancer. Citation Format: Kristin L. Boylan, Adam Meyer, Petra C. Buchanan, Melissa S. DeRycke, Amy P. Skubitz. Role of nectin-4 in the progression of ovarian cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1984. doi:10.1158/1538-7445.AM2014-1984

Abstract Background: Extranodal follicular dendritic cell sarcoma (FDCS) is an exceedingly rare tumor type that is limited to few cases in the literature. Given the rarity of this tumor, there is a lack of genetic understanding of this disease resulting in a non-individualized plan of care for patients with this disease. Herein, we are the first to describe extensively molecularly the DNA and RNA of this tumor. Methods: Under an IRB approved protocol, the patient's tumor and whole blood was freshly frozen for molecular analysis. We performed Next Generation Sequencing (NGS) genomic profiling including exome capture, mate pair and mRNA sequencing on this tumor. Exome and mRNA data were processed through Mayo's Bioinformatics Core standard pipelines, GENOME GPS 1.2.1 and MAPRSeq v1.2.1. Mutations and indels were prioritized depending on whether or not they belonged to known cancer associated genes. Copy number variations (CNVs) in Exome and Mate Pair data was found through PatternCNV v 1.0.1 and fusion transcripts were found using SNOWSHOES-FTD and Tophat-Fusion 2.0.6. Results: At the genomic level large scale genomic rearrangements were detected, including chr19 and chr20 trisomy, chr15q and chr17q segmental duplications result in two intra-chromosomal fusion genes, and translocations leading to four inter-chromosomal fusion genes between chr15 and chr17. Of particular interest is a stop codon gain in the CLTC1 (chr22) gene, which is involved in the mitotic spindle organization which has been associated with meningiomas and breast tumorigenesis. The new stop codon is before the site required for the recruitment of the proteins to the spindle. The large scale genomic rearrangement described above is consistent with this defective spindle assembly hypothesis. Another intriguing mutation detected in the VEGFR1 (chr13) gene leads to a 45% mis-spliced transcript. VEGFR1 is thought to modulate VEGFR2 which plays an essential role in angiogenesis, by acting as a decoy receptor. Therefore the loss of function of VEGFR1 might lead to hyper-activity of VEGFR2 pathway and a potential therapeutic strategy is to directly inhibit the VEGFR2 pathway. Furthermore missense mutations in the ATM (chr11) and TP53 (chr17) genes were found. PARP inhibitors have been used with success for cancer with defects in the ATM gene. Finally a novel fusion transcript of HDGRFP3 (chr15) and SHC4 (chr15) was identified. Such fusion results in an overexpressed SHC4 gene which has been associated with metastatic melanomas. Conclusions: In summary, genomic profiling of a rare thyroid FDCS identified drug targetable genes as well as changes related to tumor etiology. Future work is necessary to determine the functional significance of these molecular findings and whether they will predict benefit to targeted therapies. Citation Format: Jaime I. Davila, Jason Starr, Steven Attia, Chen Wang, Xue Wang, Brian Necela, Casler John, David Menke, Vivek Sarangi, Gavin Oliver, Richard Joseph, John Copland, Alexander Parker, E. Aubrey Thompson, Robert Smallridge, Yan W. Asmann. Extensive genomic profiling of a rare extranodal-follicular dendritic cell sarcoma: Implications for future individualized therapy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1894. doi:10.1158/1538-7445.AM2014-1894

Abstract Background: Ovarian cancer (OC) is the most common cause of death among gynecologic cancers. A key reason for the high lethality of OC is that early detection of OC is uncommon, and the majority of OC patients have advanced stage disease at diagnosis. Current non-invasive tests do not adequately distinguish benign from malignant adnexal masses. Diagnostic tests that reliably distinguish early stage OC from benign conditions may lead to earlier diagnosis of OC and improved survival. Methods: We designed a cohort study of plasma biomarkers in ovarian cancer patients. Specimens were analyzed from 100 patients with advanced OC (AJCC Stage III and IV), 50 patients with early stage OC (Stage I and II), and 50 patients with benign surgical conditions from the Mayo Ovarian SPORE Biospecimens Core. Presurgical plasma samples were assayed for multiple toll-like receptor agonists, cytokines, and vascular growth factors by ELISA and electrochemiluminescence. Biomarkers that were reliably detected in plasma were analyzed for association with OC. Differences in plasma biomarker levels between benign, early, and advanced OC patient groups were assessed using plate-adjusted logistic regression models. Results: Out of 23 biomarkers tested, 7 were excluded due to unreliable plasma detection. Of the remaining 16 biomarkers, 6_including interferon gamma (IFNγ), interleukin 6 (IL-6), IL-8, IL-10, tumor necrosis factor alpha (TNFα), and placental growth factor (PlGF)_were univariately associated with OC (all p<0.005), and one_IL-6_was associated with early stage OC (p < 0.0001). Heat shock protein 90kDa beta member 1 (HSP90B1, gp96) was associated with OC and early stage OC with borderline statistical significance (p = 0.039 and p = 0.026, respectively). However, when adjusted for cancer antigen 125 (CA-125), only HSP90B1 independently predicted OC (p = 0.008), as well as early stage OC (p = 0.014). Conclusions: The plasma cytokines IFNγ, IL-6, IL-8, IL-10, TNFα, and PlGF are associated with OC. However, after adjusting for CA-125, only HSP90B1 independently predicts OC, including early stage OC. These data warrant further investigation to determine whether measuring plasma HSP90B1 can aid in patient evaluation. Citation Format: Matthew S. Block, Matthew J. Maurer, Krista Goergen, Kimberly R. Kalli, Courtney L. Erskine, Marshall D. Behrens, Keith L. Knutson. Plasma heat shock protein 90kDa beta member 1 levels predict both early stage and advanced stage ovarian cancer independently from cancer antigen 125 in patients with an indeterminate adnexal mass. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1873. doi:10.1158/1538-7445.AM2014-1873

Abstract Disruption of the MDM2/p53 pathway is an oncogenic driver alteration observed in the vast majority of GBM. This study evaluated the efficacy of the small molecule, human-specific, MDM2 inhibitor SAR405838 across a panel of GBM xenografts with distinct alterations within the MDM2/p53 pathway. Through screening a panel of 56 GBM xenografts with a combination of array CGH and MDM2-specific PCR amplification, five xenograft models were identified with high-level MDM2 amplification (GBM 5, 102, 108, 122, and 143). MDM2 transcript expression was elevated in all of these lines except GBM102, which had expression levels similar to non-amplified lines. The effects of SAR405838 were studied in 2 of the MDM2 amplified lines (GBM102, GBM108), and non-amplified lines with wild-type p53 (GBM10) or mutant p53 (GBM12). Using a combination of neurosphere and Cyquant assays to assess in vitro sensitivity, 100 nM SAR405838 completely inhibited growth of GBM108 (6% +/- 1% absorbance relative to control), partially inhibited GBM102 neurosphere formation (34 +/- 17% relative to control), and had nominal impact on relative neurosphere formation in GBM10 (51% +/- 4% relative to control) or GBM12 (96% +/- 4% relative to control). Twenty-four hours after treatment with 100 nM SAR405838, transcript expression of p53 target genes p21 and PUMA were elevated by 14 and 12 fold relative to control in GBM108, while more limited changes in expression were observed in GBM102 (4 and 2.5 fold increase, respectively). Similarly, analysis of apoptosis after 72h by Annexin-V staining demonstrated a 5-fold increase in apoptotic fraction from control in GBM108 compared to no increase in GBM102. A more striking difference in efficacy was observed in flank tumor xenograft studies where the time to reach a median tumor volume of 1000 mm3 was marginally extended in GBM102 (36 days for placebo vs. 44 days for SAR405838). In contrast, GBM108 placebo-treated mice grew to a median volume of 1000 mm3 in 53 days while treatment with SAR405838 resulted in complete tumor regression at 70 days. SAR405838 is a known substrate for the P-glycoprotein efflux pump that functions in the blood brain barrier to exclude xenobiotics from the central nervous system. Consistent with limited penetration of SAR405838 into the brain, a parallel study in an intracranial xenograft model for GBM108 demonstrated no significant survival benefit with SAR405838 treatment compared to placebo. Thus, although SAR405838 provides marked efficacy in vitro and in a flank tumor model of an MDM2 amplified tumor line, the lack of efficacy in an orthotopic model of this study suggests that more prudent investigation is needed before advancing the development of this specific drug in human tumors growing in the brain. Citation Format: Ann C. Mladek, Isabelle Meaux, Katrina Bakken, Pascal Pannier, Cedric Barriere, James W. Watters, Laurent R.J. Debussche, Jann N. Sarkaria. Targeted murine double minute 2 (MDM2) inhibition results in dramatic tumor regression in an MDM2-amplified glioblastoma multiforme (GBM) xenograft model. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1799. doi:10.1158/1538-7445.AM2014-1799

Abstract Introduction: QSOX1 is a flavin-dependent sulfhydryl oxidase and the only known human enzyme with both disulfide generating and transferring activities. Using tissue microarrays, we previously demonstrated that QSOX1 is over-expressed in multiple tumor types including breast, pancreas, prostate and myeloma. Loss of QSOX1 leads to a significant decrease in tumor cell proliferation and invasion. The over-expression of QSOX1 in tumor cells compared to non-malignant cells combined with its role in tumor cell proliferation and invasion make it an attractive target for potential anti-neoplastic agents. Methods: Using a high throughput screening assay to detect sulfhydryl oxidase activity, we screened a library of compounds for inhibition of the QSOX1 enzyme. We used ROS-GloTM, a luciferase-based assay that detects H2O2, to determine if any compounds in the library inhibited QSOX1-mediated disulfide bond formation using reduced RNAse A as a substrate. QSOX1 generates H2O2 as a by-product of disulfide bond formation. To determine if compounds that showed activity in the enzymatic assay were also active against tumor cells, we treated pancreatic, breast, and myeloma cells with the compounds in a dose-dependent fashion, using non-malignant cells as controls. We assayed growth/viability by MTT and CellTiter-Glo assays. Invasive activity of tumor cells was assessed using matrigel-coated inserts in a modified Boyden chamber assay. Results: High throughput library screening identified 4 compounds that specifically inhibited QSOX1 activity (designated A-D) compared to a glucose oxidase counter-screen. Growth/viability assays showed that compound D suppressed the growth of tumor cells with IC50s between 300nM-750nM, depending on tumor cell line. In non-malignant cells the IC50s for compound D were more than 10-fold higher than in tumor cells. Compounds A and D also inhibited invasion of breast and pancreatic tumor cells through Matrigel. Conclusion: This is the first report of chemical compounds that inhibit QSOX1 enzymatic activity. The discovery of QSOX1 inhibitors with cellular efficacy establishes the chemical tractability of the target. Our data demonstrate that these First-In-Class compounds have potential as anti-neoplastic therapeutics via inhibition of QSOX1. Citation Format: Paul D. Hanavan, Douglas O. Faigel, Chen-Ting Ma, Eduard Sergienko, Nathalie Meurice, Joachim L. Petit, Yvette W. Ruiz, Benjamin A. Katchman, Douglas F. Lake. Small molecule inhibitors of QSOX1 suppress tumor cell growth and invasion. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1790. doi:10.1158/1538-7445.AM2014-1790

Abstract Deregulation of the TWEAK-Fn14 signaling pathway is observed in many diseases including inflammation, autoimmune diseases, and cancer, notably glioblastoma. Activation of Fn14 signaling by TWEAK binding triggers glioma cell invasion and survival and therefore represents an attractive pathway for therapeutic intervention. Based on structural studies of the TWEAK-binding cysteine rich domain of Fn14, several homology models of TWEAK were built to investigate plausible modes of TWEAK-Fn14 interaction. Two promising models, centered on different anchoring residues of TWEAK [Tyrosine 176 (Y176) and Tryptophan 231 (W231)], were prioritized using a data-driven strategy. Site-directed mutagenesis of TWEAK at Y176, but not W231, resulted in the loss of TWEAK binding to Fn14 substantiating Y176 as the anchoring residue. Importantly, mutation of TWEAK at Y176 did not disrupt TWEAK trimerization, but failed to induce Fn14 mediated nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling. The validated structural models were utilized in a virtual screen to design a targeted library of small molecules predicted to disrupt the TWEAK-Fn14 interaction. 129 small molecules were screened iteratively, with identification of molecules producing up to 37% inhibition of TWEAK-Fn14 binding. One specific compound, L524-0366 binds specifically to the Fn14 receptor and disrupt TWEAK-Fn14 interaction. Treatment of L524-0366 suppresses TWEAK-induced cell migration and survival in glioblastoma cells. In summary, we present a data-driven in silico study revealing key structural elements of the TWEAK-Fn14 interaction, followed by experimental validation, serving as a guide for the design of small molecule inhibitors of the TWEAK-Fn14 ligand-receptor interaction. Our results provide the foundation for further exploration utilizing L524-0366 as a small molecule inhibitor to the TWEAK-Fn14 signaling axis. Citation Format: Harshil D. Dhruv, Joseph C. Loftus, Pooja Narang, Joachim L. Petit, Donald Chow, Holly Yin, Michael Berens, Nathalie Meurice, Nhan L. Tran. Identification and characterization of L524-0366 as a small molecule inhibitor that disrupt TWEAK-Fn14 signaling in glioblastoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1780. doi:10.1158/1538-7445.AM2014-1780

Abstract Introduction: Histologic characteristics of nonmalignant breast tissues (epithelial proliferation and involution) are associated with future breast cancer (BC) risk. We evaluated immune infiltration (lobulitis) in benign breast lobules and its association with features of BC risk. Methods: We analyzed archived nonmalignant breast tissue samples from 81 women in age-matched groups of varying cancer risk: 27 with benign breast disease (BBD) who later developed BC (cases), 27 with BBD without subsequent BC (controls), and 27 normal women without clinical breast disease from the Komen Tissue Bank at Indiana University (KTB). Up to 10 lobules in each sample were characterized by H&E for lobulitis, involution (none, partial, complete), and fibrocystic (FC) status (normal, nonproliferative, proliferative). Lobulitis was defined by H&E staining as lymphocyte nuclei in the intralobular stroma at low magnification and between adjacent acini at high magnification. Data was analyzed by mixed effects logistic regression. Results: Median age was 57 years (range 37-70). Among 81 breast tissue samples, 750 lobules were evaluated: 249 in BBD Cases, 265 in BBD Controls, and 236 in KTB donors. 56% of lobules were normal and 44% were FC, with 87% of FC lobules occurring in BBD samples. Lobulitis was present in 44% of lobules and varied according to subject age and individual lobule features. Younger women were more likely to have lobulitis (p=0.002); among women <50 the median proportion of lobules with lobulitis was 50%, versus 30% among women 50+. Lobulitis was less frequent in lobules with complete involution (37%) compared to partial (74%) or no involution (84%), p<0.0001. Lobulitis was common in normal lobules (52%) and decreased with increasing epithelial abnormality-39% of nonproliferative lobules and 27% of proliferative lobules (p<0.0001). In multivariate analysis including all 3 variables, all 3 remained significantly associated with lobulitis: age (p=0.03), proliferation (p<0.0001), and involution (p=0.0001). Lobules with lobulitis were less frequent in groups of women with increased breast cancer risk-55% of lobules in normal KTB samples, 43% in BBD controls, and 35% in BBD cases (p = 0.02). Conclusion: Lobulitis is common in normal and benign breast tissue lobules but varies with age, involution status, and epithelial abnormality. Further work is needed to understand the role of immune infiltrates in breast cancer risk. Citation Format: Rushin D. Brahmbhatt, Daniel W. Visscher, Tanya L. Hoskin, Derek C. Radisky, Linda M. Murphy, Melody L. Stallings Mann, Erin Miller, Vernon S. Pankratz, Lynn C. Hartmann, Marlene H. Frost, Amy C. Degnim. Immune infiltration of normal and benign breast lobules varies in breast tissues based on cancer risk. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1652. doi:10.1158/1538-7445.AM2014-1652

Abstract Intro: Male BC is a rare disease (<1% male tumors); knowledge is limited and management extrapolated from female BC. An international consortium, coordinated by EORTC and TBCRC, was created to better characterize and manage this disease, with 3 parts: 1) retrospective joint analysis 2) prospective registry 3) clinical trial(s). We report 1st results of part 1. Methods: Joint analysis of male BC pts with available FU & FFPE samples, treated in 1990-2010, in 23 centers from 9 countries. Clinical data, long term outcomes, local pathology were centrally analyzed at EORTC. FFPE samples were analyzed at 3 central labs (UK, NL, US) for histology, grade, ER, PR, AR, HER-2, Ki67. Cut-off for positivity: Allred score ≥ 3 for ER/ AR/PR; 20% for Ki67; ASCO-CAP for HER2. Outcome data (OS & RFS) analyzed per Kaplan Meier, p-values correspond to logrank test, CI’s by Brookmeyer & Crowley. Reported % use number of non-missing values as denominator. Results: 1822 pts enrolled; 349 (19%) ineligible (no valid central lab assessment); of 1473 eligible pts (1384 from EU, 89 from US) 63% diagnosed in 2001-2010. Median age at diagnosis (Dx) was 68.5 ys. Of pts with known M status at Dx, 56 (5.1%) were M1; of 1046 M0 cases, 60% were N0 and 51% had T1 tumors at Dx; 4% of pts had BCS and 18% had SLNB; half received adjuvant RT. (Neo)adjuvant CT was used in 30% of M0 pts, most (44%) anthracycline-only; 77% of M0 pts received adjuvant ET, most tamoxifen (88.4%). Central pathology: 697 cases with central histology & grade (full series ongoing): 87% ductal, 53% grade 2. In 1473 pts, at least 1 biomarker centrally assessed; 92% ER highly+ (Allred 7-8), PR had wider variation (35% highly+); 87% AR highly+; 25% Ki67 high; 5% HER2pos. Using IHC surrogates: 58% Luminal A-like, 35% LuminalB-like/HER2neg, 6% LuminalB-like/HER2pos; 0.1% HER2pos/non-Luminal; 1% TNBC (16% not classified). Outcome: For 1046 M0 pts, median FU was 5.7 yrs (0-19.2); 63% alive at analysis; in 88% cause of death was reported, mainly 33% non-cancer and 28% progression(PD)/toxicity. Significant OS improvement over time is seen. 75% (42/56) M1 pts died, mainly due PD. In M0 pts, median OS (yrs) was significantly correlated with ER+ p=0.001 [Allred 0-2: 3.9 (0.1, 6.0); 3-6: 7.1 (4.7, 11.7); 7-8: 8.8 (8.3, 10.0)] & with PR+ p=0.022 [Allred 0-2: 7.3 (6.1, 10.3), 3-6: 8.0 (7.0, 9.3), 7-8: 9.5 (8.4, 12.8)]; less correlation for AR; no major differences for HER2 or Ki67. Median OS & grade (394 cases; full series ongoing): Grade1: 12.8 yrs (6.1-15.6); Grade2: 7.9 (6.5-10.7); Grade3: 9.3 (4.9-21.1). Median OS for IHC surrogates: 8.7 (7.8-9.7) for Luminal A; 8.3 (6.9-9.4) for Luminal B/HER-2neg; 9.3 years (5.9-21.1) for Luminal B/HER-2+. Similar results were seen for RFS. ER/PR/AR using histoscores will be presented. Conclusions: a) 56% pts had T1 tumors at Dx but only 4% had BCS; b) ER was highly + in >90% but adjuvant ET given in only 77% pts; c) Male BC is usually ER+, PR+ & AR+ and of Luminal A-like subtype (5% HER2pos & 1% TNBC); d) Significant improvement in OS over time; e) ER and PR (Allred) are prognostic (high expression/better prognosis), less for AR, not for Ki67 nor IHC surrogates; f) In-depth characterization of samples is ongoing. Funding: BCRF, EBCC Council, Pink Ribbon NL, BRO. Citation Format: Fatima Cardoso, John Bartlett, Leen Slaets, Carolien van Deurzen, Elise van Leewen-Stok, Peggy Porter, Barbro Linderholm, Ingrid Hedenfalk, Carolien Schroder, John Martens, Jane Bayani, Christi van Asperen, Melissa Murray, Clifford Hudis, Lavinia Middleton, Joanna Vermeij, Stephanie Peeters, Judith Fraser, Monica Nowaczyk, Isabel Rubio, Stefan Aebi, Catherine Kelly, Kathryn Ruddy, Eric Winer, Cecilia Nilsson, Lissandra Dal Lago, Larissa Korde, Kim Benstead, Danielle Van Den Weyngaert, Oliver Bogler, Theodora Goulioti, Nicolas Dif, Carlo Messina, Konstantinos Tryfonidis, Jan Bogaerts, Sharon Giordano. Characterization of male breast cancer: First results of the EORTC10085/TBCRC/BIG/NABCG International Male BC Program [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr S6-05.

Abstract Background: We have previously shown in animal models that combination anti-HER2 therapy leads to complete tumor regression of HER2+ breast cancer (BC). We translated these findings in a neoadjuvant trial of 12 weeks (wks) of L+T (TBCRC006) that demonstrated a meaningful pathologic complete response (pCR) and near pCR (in ER+ tumors) in patients with locally advanced HER2+ BC. In the present trial, we sought to determine whether longer treatment would lead to a higher rate of pCR without the use of chemotherapy by converting near pCR to pCR especially in the ER+ subset. Methods: TBCRC023 (NCT00999804) is a randomized phase II trial combining a Simon Phase 2 design in the experimental arm with a pick-the-winner design, not powered for direct comparison. Women with HER2+ BC measuring 2 cm or larger were eligible and were randomized in a 1:2 ratio to 12 vs. 24 wks of L+T. Letrozole (along with ovarian suppression if premenopausal) was also administered in patients whose tumors were also ER+. Serial tumor biopsies were obtained at baseline, wk 1, wk 12, and at the time of surgery. All evaluable patients were assessed for pCR, defined as no residual invasive carcinoma in the breast. Patients did not undergo surgery, withdrew consent, or received additional neoadjuvant therapy were counted as non-responders. Results: Ninety-seven patients were enrolled (33 in 12-wk arm and 64 in 24-wk arm), of whom 95 were evaluable. Seventy seven percent of patients were white and 18% were black. Twenty percent were of Hispanic ethnicity. Median age was 51 and 55% were postmenopausal. Median tumor size was 5 cm and 65% were ER+. Study treatment was well tolerated with grade 1-2 diarrhea (24% in 12-wk arm, 31% in 24-wk arm) and grade 1-2 acneform rash (12% in 12-wk arm, 19% in 24-wk arm) being the most common toxicities. Grade 3 toxicities were uncommon and were mostly in the 24-wk arm (elevated liver function test: 9%, diarrhea 2%, mucositis 2%), while the 12-wk arm had one grade 3 anemia and the study’s only serious adverse event (acute kidney injury). There were no grade 4 toxicities. The experimental arm completed stage 2 accrual and pCR rate was numerically superior to control, entirely due to better results in ER+ (Table 1), but lower than the expected pCR rate of 36% needed in the planned analysis to conclude in favor of enhanced efficacy with extended therapy. pCR rates were also lower in the control arm than in the previous study. Table 1. pCR rates 12-week arm % (n)24-week arm % (n)ER-positive8.7% (2/23)33.2% (13/39)ER-negative20% (2/10)8.7% (2/23)Overall pCR12.2% (4/33)24.2% (15/62) Conclusions: Treatment with L+T (with endocrine therapy in ER+ tumors) for 24 weeks leads to doubling of the pCR rate in women with HER2+ breast cancer without using cytotoxic chemotherapy. This approach is effective and well tolerated and warrants study as part of a de-escalation strategy that may spare some patients the cost and toxicity of chemotherapy. Tissue obtained on this trial will provide a valuable resource to validate correlative findings from our prior studies and discover new biomarkers to help guide proper patient selection for treatment. Citation Format: Mothaffar F Rimawi, Polly A Niravath, Tao Wang, Brent Rexer, Andres Forero, Antonio C Wolff, Rita Nanda, Anna M Storniolo, Ian Krop, Matthew P Goetz, Julie R Nangia, Sao Jiralerspong, Anne C Pavlick, Carolina Gutierrez, Rachel Schiff, Susan G Hilsenbeck, C Kent Osborne. TBCRC023: A randomized multicenter phase II neoadjuvant trial of lapatinib plus trastuzumab, with endcorine therapy and without chemotherapy, for 12 vs. 24 weeks in patients with HER2 overexpressing breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr S6-02.