bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract PD6-6: A pooled analysis of the prognostic relevance of circulating tumor cells in early breast cancer
Authors: Janni WJ , Rack BK , Terstappen LMWW , Pierga J-Y , Fehm T , Hall C , Groot M , Bidard F-C , Meier-Stiegen F , Friedl TWP , Fasching P , Lucci A
Published: August 2014

Background: While there is unequivocal evidence regarding the prognostic relevance of circulating tumor cells (CTCs) in peripheral blood of patients (pts.) with metastatic breast cancer (BC), less data is available for the prognostic relevance at time of primary diagnosis.

Methods: We conducted a pooled analysis with individual data of 3172 pts with non-metastatic (Stage I-III) BC from five academic institutions. Prevalence and number of CTCs in the peripheral blood were assessed at time of primary diagnosis using the FDA-approved CellSearch System (Veridex, USA). Patient outcomes were analyzed using univariate log-rank tests and multivariate Cox regressions. The median follow-up time was 61 months.

Results: At least one CTC was detected in 20.2% of the pts. The presence of CTCs was associated with larger tumors, more axillary lymph node metastases, and higher histological tumor grade (all p < 0.005). The presence of CTCs was significantly related to poor progression-free (PFS, log-rank test, p < 0.001, hazard ratio [HR] 2.0) and overall survival (OS, p < 0.001, HR 2.6). Multivariate Cox regressions, including tumor size, nodal status, histological tumor grade, hormone receptor status and HER2 status, and CTC prevalence confirmed that the presence of CTCs was an independent prognostic factor for both poor PFS (HR 1.8) and OS (HR 2.1, both p < 0.001). In the univariate subgroup analysis concerning OS, the HR for pts. with positive HRS was 3.1 (p< 0.0001), and 2.0 (p = 0.001) for pts. with a negative HRS. The prognostic relevance of CTC status was similar for patients with HER2 negative and HER2 positive tumors (HR 2.6 and 2.5, respectively). The HR in CTC-positive pts. with HRS positive/HER2 positive tumors was 3.4 (p = 0.003). For patients with more than 3 CTCs, the hazard ratio for death was increased to 5.2 (1.5 - 2.8) in univariate and to 4.0 (2.6 - 6.2) in multivariate analysis.

Cox Regression Analysis for Overall SurvivalVariableHazard ratio95% CIP-valueCTCs   pos vs. neg2.1081.594 - 2.788<0.001Tumor grade  0.001G2 vs. G11.0730.489 - 2.3540.861G3 vs. G12.2391.028 - 4.8740.042Histological type  0.389lobular vs. ductal1.3200.865 - 2.0150.198other vs. ductal0.8980.498 - 1.6200.722Tumor stage  <0.001T2 vs. T11.8531.301 - 2.6380.001T3 vs. T13.7062.310 - 5.947<0.001T4 vs. T13.5382.014 - 6.218<0.001Nodal stage  <0.001N1 vs. N01.5471.081 - 2.2130.017N2 vs. N02.5381.660 - 3.879<0.001N3 vs. N03.8242.471 - 5.918<0.001Hormone receptor status   pos vs. neg0.4020.294 - 0.550<0.001Her2 status   pos vs. neg0.5790.407 - 0.8230.002Menopausal status   post vs. pre1.3701.023 - 1.8340.035

Conclusions: In patients with early breast cancer, the presence of CTCs in peripheral blood is an independent predictor of poor progression-free and overall survival.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD6-6.
Abstract PL02: Adjuvant bisphosphonate therapy in breast cancer
Authors: Gnant M
Published: August 2014

Breast cancer patients face challenges to skeletal integrity, both by caused by the disease but also as a side effect of standard endocrine therapy. Bisphosphonates inhibit osteoclast-mediated bone resorption, are approved as standard therapy for treating malignant bone disease from advanced cancers, and have shown efficacy for preventing cancer treatment-induced bone loss.

Bisphosphonates also have demonstrated anti-cancer activity preclinically and in clinical trials during adjuvant breast cancer therapy. The metastasis-preventing effect of bisphosphonates has been explained by their putative effects on the bone marrow microenvironment, which provides a site for cancer cells to evade immune surveillance and adjuvant systemic anti-cancer therapy. Dormant tumor micrometastases are believed to be the ultimate source of disease persistence and relapse, and it has been suggested that adjuvant bisphosphonate treatment renders the bone marrow microenvironment less conducive to cancer (stem) cell survival. This plenary lecture will provide a brief overview of the numerous preclinical and early clinical studies of bisphosphonates demonstrating a variety of direct and indirect anticancer activities, including the „seed-and-soil” hypothesis, and the proven effects of bisphosphonates on disseminated tumor cells.

However, key questions remain surrounding the role of adjuvant bisphosphonates in breast cancer, including selecting patient populations actually deriving benefit and optimal timing/scheduling of therapy. Despite thousands of patients have been included in randomized clinical trials of adjuvant bisphosphonates, significant controversy persists about the usefulness of this therapeutic approach: current clinical data show clear-cut improvements in disease outcomes with bisphosphonates in many studies, although not in all patient subsets: Strongest support for the potential adjuvant anticancer benefits from bisphosphonates has been demonstrated in women with established menopause (i.e., very low circulating estrogen levels). Also, initiating bisphosphonates early and concomitantly with adjuvant therapy generally provided the greatest benefits.

In addition to earlier trials using oral bisphosphonates such as clodronate, recent clinical data from large phase 3 trials (e.g. ABCSG-12, ZO-FAST, and AZURE) demonstrate significantly improved disease-free survival with zoledronic acid in some patient populations with early breast cancer. Other bone-targeted treatment approaches such as denosumab are currently evaluated for adjuvant therapy in large clinical trials.

This plenary lecture will review the available data and concepts with the ultimate aim of aiding physicians in providing bone-targeted therapy as part of their optimal breast cancer patient counseling and management.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PL02.
Abstract S3-05: Patient-derived xenograft study reveals endocrine therapy resistance of ER+ breast cancer caused by distinct ESR1 gene aberrations
Authors: Shao J , Li S , Crowder RJ , Kitchens RT , Johnson SN , Goncalves R , Phommaly C , Griffith OL , Maher C , Perou CM , Mardis ER , Ellis MJ
Published: August 2014

Endocrine therapy resistance occurs in 50% of estrogen receptor positive (ER+) luminal breast cancers but the underlying mechanisms are poorly understood. To gain insight, we have taken advantage of whole-genome and RNA sequencing data of five late-stage hormone-resistant luminal breast tumors all of which have been successfully established as patient-derived mouse xenograft (PDX) models. Here we describe genetic alterations in ESR1-the gene coding for ERa-in three of these five tumors. They include an ESR1 point mutation (Y537S), a gene translocation causing an in-frame fusion between N-terminal ER and C-terminal Yes-associated protein 1 (YAP1), and ESR1 gene amplification. Functional characterization of the ESR1(Y537S) mutant and ESR1-YAP1 fusion in ER+ cell lines indicated that they both possess constitutive transcriptional activity and drive hormone-independent cell proliferation, mirroring the endocrine resistance of the originating tumors and the estradiol-independent growth of the PDX tumors. ESR1 (Y537S), a known gain-of-function experimental mutation in the ligand-binding domain of ER is not seen in primary breast cancer (TCGA data), suggesting it is a mutation associated with acquired resistance. Regarding the ESR1-YAP1 fusion gene, the truncated N-terminal ER fragment lacks the hormone-dependent transactivation domain (AF2) and the ligand binding domain but retains the hormone-independent transactivation domain (AF1) and therefore drives resistance to all endocrine approaches. As for ESR1 gene amplification, the tumor of origin, though resistant to aromatase inhibition, paradoxically responded to estradiol treatment, and this was recapitulated in the PDX model. Interestingly, acquired ESR1 gene amplification also occurred in long-term estrogen-deprived breast cancer MCF-7 cells which similarly regress upon estradiol exposure. Thus, ESR1 amplification may be a biomarker for paradoxical therapy with estradiol. Together, our focused study of advanced endocrine resistant luminal breast tumors revealed three distinct mutational mechanisms affecting the ESR1 gene that drive endocrine therapy resistance. Prevalence studies using RNAseq are underway to determine the frequency of somatic changes in the ESR1 gene in advanced breast cancer samples and additional ER+ PDX models. These additional data will be presented at the meeting.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr S3-05.
Abstract S4-03: Exome sequencing reveals clinically actionable mutations in the pathogenesis and metastasis of triple negative breast cancer
Authors: Blackwell KL , Hamilton EP , Marcom PK , Peppercorn J , Spector N , Kimmick G , Hopkins J , Favaro J , Rocha G , Parks M , Love C , Scotland P , Dave SS
Published: August 2014

Triple negative breast cancer (TNBC) represents a particularly aggressive and difficult to treat form of breast cancer. No specific genetic alterations have been described as characteristic of the disease, with the exception of association with BRCA1/2, EGFR, and KRAS mutations. In this study, we sought to define clinically actionable mutations in untreated metastatic tumors as well as compare the mutational status of metastatic samples with germ-line and primary tumors using whole exome sequencing.

We prospectively enrolled 38 patients with newly diagnosed metastatic TNBC and collected matched specimens of germ-line DNA, primary tumor and metastatic tumor. Median DFI from time of initial primary diagnosis to recurrence was 18 months (IQR = 1-24 months) and 9 patients presented with de novo metastatic disease. 34/38 patients went on to receive first-line treatment with nab-paclitaxel, carboplatin, and bevacizumab and ORR/PFS/OS are available.

Sites of TNBC metastatic tissue (n = 31) included: liver (10), chest wall (13), non-regional lymph nodes (4), and lung (4). 7 patients had inadequate metastatic tumor for sequencing. We performed whole-exome sequencing for all samples using the Agilent solution-based system of exon capture, which uses RNA baits to target all protein coding genes (CCDS database), as well as ∼700 human miRNAs from miRBase (v13). In all, we generated over 10 GB of sequencing data using high throughput sequencing on the Illumina platform.

We observed striking genetic heterogeneity among the metastatic and primary tumors. There was no single driver mutation that was common to the metastatic tumors indicating the diverse genetic pathways that contribute to metastasis. Early analysis suggests that mutations in APC and MTOR occur more frequently in metastatic tumors than in primary tumors. Nonsense mutations of ER were detected in both primary and metastatic tumors but not in germ-line DNA. EGFR and HER2 mutations were not found in any of the primary or metastatic TNBC samples.

This data provides the most comprehensive genetic portrait of metastatic and primary TNBC to date, and represents a significant first step in identifying the genetic causes of the disease, drivers of recurrence, and potential therapeutic targets. Full results, including the primary versus metastatic tumor mutational analysis will be presented.

This study was funded by a Susan G. Komen Grant SAC 100001.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr S4-03.
Abstract S4-07: Effects of bisphosphonate treatment on recurrence and cause-specific mortality in women with early breast cancer: A meta-analysis of individual patient data from randomised trials
Authors: Coleman R , Gnant M , Paterson A , Powles T , von Minckwitz G , Pritchard K , Bergh J , Bliss J , Gralow J , Anderson S , Evans V , Pan H , Bradley R , Davies C , Gray R
Published: August 2014

Background: Disseminated tumour cells can remain dormant in the bone marrow for years prior to subsequent activation and the development of overt metastases. Bisphosphonates (BP) have profound effects on bone physiology and could potentially modify the metastatic disease process. Variable outcomes in terms of disease recurrence have been reported, with efficacy apparently influenced by menopausal status.

Methods: We sought individual patient data for meta-analysis from 41 randomised trials that compared BP to no BP (placebo or open control). Primary outcomes were time to recurrence, time to first distant recurrence and breast cancer mortality. Predefined subgroup comparisons were of type of BP (amino-/non-amino), duration and schedule of BP treatment, menopausal status, age, ER status, concomitant chemotherapy and site of distant recurrence (bone/other).

Results: Data on 17,751 women (75% of 23,573 randomised in relevant trials) have so far been received, with around 3,300 breast cancer recurrences and 2,500 deaths. Effects on breast cancer mortality, recurrence and bone metastases for 17,016 women in the locked database and for 10,540 who were postmenopausal are shown below.

No. eventsRate Ratio (SE)10 year gain2p valueAll women (n = 17,016)Breast cancer mortality2,0490.91 (0.04)1.7%0.04Breast cancer recurrence3,2840.94 (0.04)1.0%0.13Distant recurrence2,7510.92 (0.04)1.3%0.05Bone recurrence8250.79 (0.07)1.4%0.002Other distant recurrence1,9260.99 (0.05)0.1%0.8Postmenopausal women (n = 10,540)Breast cancer mortality1,1070.83 (0.06)3.1%0.004Breast cancer recurrence1,8090.86 (0.05)3.0%0.002Distant recurrence1,5030.83 (0.05)3.3%0.0007Bone recurrence4450.65 (0.08)2.9%0.00001Other distant recurrence1,0580.93 (0.06)0.7%0.26

Reductions in bone recurrence for postmenopausal women were similar irrespective of bisphosphonate type, treatment schedule, ER status, nodal involvement or use of concomitant chemotherapy. There were no improvements in bone (RR = 1.00, 2p = 0.97) or other recurrence for premenopausal women. Adjuvant bisphosphonates also reduced bone fractures (RR = 0.83, 2p = 0.009).

Conclusion: Adjuvant bisphosphonates reduce bone recurrences and improve breast cancer survival in postmenopausal but not premenopausal women.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr S4-07.
Abstract A01: No Maryland county left behind: Statewide intervention may reduce geographic disparities.
Authors: Bischoff Christina M. , Kanarek Norma F.
Published: August 2014

Introduction: Recent Maryland cancer planning, funding and consensus building efforts and prior screening for breast and cervical cancer have successfully reduced mortality rates and racial disparities over time. Nevertheless geographical disparities among Maryland counties have not been examined.

To date assessment of racial disparities has been accomplished using the Index of Disparity. To evaluate geographic disparities and whether every county is improving regardless of its size we suggest utilization of coefficient of variation (CV), skewness and kurtosis. We investigated geographic disparities in county cancer mortality over three time periods and between Maryland and the five adjacent states.

Methods: Using data from CDC WONDER, we assessed county breast (female), colon/rectal, lung, and prostate (male) cancer mortality coefficient of variation, skewness, and kurtosis relative to a priori critical values.

Results: Maryland counties showed a coefficient of variation consistent with adjacent state counties. In both geographic areas, breast and colon/rectum coefficients of variation were statistically below 0.25. Skewness among Maryland counties was not significant in any time period or any site except prostate cancer, significantly positive (1.36, 95% confidence intervals: 0.43-2.29) only during 1994-98. Only the adjacent state counties exhibited statistically significant skewness and kurtosis for each cancer site at some time. Coefficient of variation is most often slightly smaller than the Index of Disparity due to the larger average of county rates relative to the overall rate (weighted by county).

Conclusion: With statewide funding since 1990, Maryland has eliminated geographic disparities in breast and colon/rectum cancer but continues to exhibit borderline lung/bronchus and significant prostate disparities exhibited by “large” coefficient of variation but not – skewness and kurtosis in 2004-2008. We suggest that absence of skewness and kurtosis may be a further indication of county disparities reduction.

Tracking of disparities across counties indicated whether statewide or county-specific interventions was needed and whether progress toward elimination of disparities was made. The ideal progression of geographic disparities is indicated by a resultant very small coefficient of variation; left, if any skewness; and no kurtosis. Maryland is on track to accomplish this in all four cancer mortality indicators and on target for breast and colon and rectum.

Citation Format: Christina M. Bischoff, Norma F. Kanarek. No Maryland county left behind: Statewide intervention may reduce geographic disparities. [abstract]. In: Proceedings of the Fifth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2012 Oct 27-30; San Diego, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(10 Suppl):Abstract nr A01.
Abstract A66: Admixture and fine mapping in African Americans identifies a susceptibility locus for prostate cancer on chromosome 7.
Authors: Ruterbusch Julie J. , Levin Albert M. , Kittles Rick , Rybicki Benjamin A. , Bock Cathryn H.
Published: August 2014

Background: There are well documented racial disparities in prostate cancer among African American (AA) men in the United States. AA men have a 60% higher incidence rate and over twice the mortality rate of Caucasian men. A previous admixture mapping study identified a region on chromosome 7 where excess European ancestry was associated with increased prostate cancer risk (Bock et al., 2009). Fine mapping of this region was performed to further identify prostate cancer susceptibility loci.

Methods: DNA from 420 prostate cancer cases and 244 controls from Henry Ford Hospital in Detroit, MI and Howard University in Washington, DC was genotyped using an Illumina 1M chip. After quality control exclusions, 54,105 single-nucleotide polymorphisms (SNPs) on chromosome 7 were available for this analysis. Local ancestry was estimated using the Local Ancestry in adMixed Populations (LAMP) program, with ancestral allele frequencies obtained from HapMap. Admixture linkage was confirmed using an affected-only test. Fine-mapping within the region was conducted using the MIX-score method proposed by Pasaniuc et al. (2011) to identify the SNP(s) most likely to explain the admixture linkage.

Results: The admixture linkage signal spanned from 7q31.1 (112.27Mb) to 7q34 (137.90Mb). Within this region, there were three SNPs with MIX-score p-values less than the Bonferonni corrected significance threshold. The highest level of significance was attained at SNP rs13221538 (p=1.16*10-7). This SNP is located in an intron of the Cadherin-like and PC-esterase domain-containing protein 1 (CPED1) gene. Adjusting for local ancestry, the allelic odds ratio for this SNP was 1.52 (p=1.16*10-5), and the C allele of this SNP is more prevalent in the Northern and Western European population (CEU - 82%) than in the West African population (YRI – 60%). While little is known about the function of CPED1, it is located between genes WNT16 and ING3. WNT16 is known to be involved in oncogenesis, and the WNT pathway has been implicated in b-catenin signaling and prostate cancer development.

Conclusion: Utilizing admixture linkage information, association fine mapping has narrowed the region on chromosome 7q associated with prostate cancer risk and identified potential candidate SNPs likely to explain the observed admixture.

Citation Format: Julie J. Ruterbusch, Albert M. Levin, Rick Kittles, Benjamin A. Rybicki, Cathryn H. Bock. Admixture and fine mapping in African Americans identifies a susceptibility locus for prostate cancer on chromosome 7. [abstract]. In: Proceedings of the Fifth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2012 Oct 27-30; San Diego, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(10 Suppl):Abstract nr A66.
Abstract B30: Selective small molecule AXL inhibitor BGB324 overcomes acquired drug resistance in non-small cell lung carcinoma models.
Authors: Wnuk-Lipinska Katarzyna , Gausdal Gro , Sandal Tone , Frink Robin , Hinz Stefan , Hellesøy Monica , Ahmed Lavina , Haugen Hallvard , Haugen Hallvard , Xiao Liang , Blø Magnus , Micklem David , Minna John , Brekken Rolf , Zhou Longen , Lorens James
Published: August 2014

Axl is a member of the TAM (Tyro3, Axl and Mer) family of receptor tyrosine kinases that regulate multiple cellular responses including cell survival, proliferation, and migration. Axl expression is associated with a variety of human cancers including non-small cell lung carcinoma (NSCLC), and is predictive of poor patient overall survival. Axl is induced by the epithelial-to-mesenchymal transition (EMT) gene program in cancer cells. Axl signaling is required to maintain EMT-associated features including invasiveness, metastasis, and can confer resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), as well as other chemotherapeutic agents. BGB324 is a potent, reversible and selective small molecule inhibitor of Axl that has recently entered into phase I clinical trials. We evaluated the effects of BGB324 on NSCLC cells in in vitro 3D assays and in mouse xenograft models, in combination with targeted and chemotherapeutic agents. BGB324 in combination with EGFR TKI erlotinib demonstrated a synergistic anti-proliferation effect on NCI-H1299 (mesenchymal, EGFR wild-type, erlotinib-resistant) human NSCLC cells in 3D culture. In mouse xenograft models using NCI-H1299 cells BGB324 treatment significantly enhanced the antitumor acitivity of Docetaxel. Similarly, using the mesenchymal NSCLC cell line A549 (EGFR wild-type), the combination of BGB324 with either erlotinib or anti-VEGF agent bevacizumab showed synergistic or additive anti-tumour activity. Furthermore, in HCC827 (EGFR mutant, erlotinib-sensitive) human NSCLC xenograft model, addition of BGB324 treatment strikely delayed the emergence of acquired resistance to erlotinib. Taken together, these data suggest the first-in-class selective Axl inhibitor BGB324 can overcome acquired resistance in in vivo models of NSCLC. Studies in human NSCLC patient-derived xenograft models and mechanisms of action are in progress.

Citation Format: Katarzyna Wnuk-Lipinska, Gro Gausdal, Tone Sandal, Robin Frink, Stefan Hinz, Monica Hellesøy, Lavina Ahmed, Hallvard Haugen, Hallvard Haugen, Liang Xiao, Magnus Blø, David Micklem, John Minna, Rolf Brekken, Longen Zhou, James Lorens. Selective small molecule AXL inhibitor BGB324 overcomes acquired drug resistance in non-small cell lung carcinoma models. [abstract]. In: Proceedings of the AACR-IASLC Joint Conference on Molecular Origins of Lung Cancer; 2014 Jan 6-9; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2014;20(2Suppl):Abstract nr B30.
Drug Repurposing Identifies a Synergistic Combination Therapy with Imatinib Mesylate for Gastrointestinal Stromal Tumor
Authors: Pessetto Ziyan Y. , Ma Yan , Hirst Jeff J. , von Mehren Margaret , Weir Scott J. , Godwin Andrew K.
Published: August 2014

Gastrointestinal stromal tumor (GIST) is a rare and therefore often neglected disease. Introduction of the kinase inhibitor imatinib mesylate radically improved the clinical response of patients with GIST; however, its effects are often short-lived, with GISTs demonstrating a median time-to-progression of approximately two years. Although many investigational drugs, approved first for other cancers, have been subsequently evaluated for the management of GIST, few have greatly affected the overall survival of patients with advanced disease. We employed a novel, focused, drug-repurposing effort for GIST, including imatinib mesylate–resistant GIST, evaluating a large library of FDA-approved drugs regardless of current indication. As a result of the drug-repurposing screen, we identified eight FDA-approved drugs, including fludarabine phosphate (F-AMP), that showed synergy with and/or overcame resistance to imatinib mesylate. F-AMP induces DNA damage, Annexin V, and caspase-3/7 activities as the cytotoxic effects on GIST cells, including imatinib mesylate–resistant GIST cells. F-AMP and imatinib mesylate combination treatment showed greater inhibition of GIST cell proliferation when compared with imatinib mesylate and F-AMP alone. Successful in vivo experiments confirmed the combination of imatinib mesylate with F-AMP enhanced the antitumor effects compared with imatinib mesylate alone. Our results identified F-AMP as a promising, repurposed drug therapy for the treatment of GISTs, with potential to be administered in combination with imatinib mesylate or for treatment of imatinib mesylate–refractory tumors. Mol Cancer Ther; 13(10); 2276–87. ©2014 AACR.
Abstract B16: Cells containing mutations in the cohesin component, STAG2, are sensitive to PARP inhibition
Authors: Bailey Melanie L. , O'Neil Nigel J. , Pel Derek M. van , Hieter Phil
Published: August 2014

Synthetic lethality (SL) has been proposed as a strategy to specifically target cells harboring cancer mutations while leaving unmutated, non-cancer cells unaffected, thus minimizing drug side effects. One genetic vulnerability common to many types of cancer is chromosome instability (or CIN). CIN can lead to increased genetic mutation and aneuploidy in cancer cells thereby distinguishing them from their normal neighbors and making it a possible candidate phenotype to target by SL. Here, we focus on the multifunctional cohesin complex that is critical for accurate chromosome segregation and genome stability because it tethers sister chromatids together after DNA replication and maintains cohesion until their separation in anaphase. Although several subunits of cohesin have been shown to be mutated in tumors, recent data identifies a cohesin component, STAG2 (Stromal Antigen 2 or SA-2) as a highly mutated gene in several types of cancer including Ewing's sarcoma, melanoma and glioblastomas (GBMs). As a previous study in our lab had shown that knockdown of any one of the core cohesion subunits SMC1A, SMC3 or RAD21 can render cells sensitive to the poly ADP-ribose polymerase (PARP) inhibitor olaparib, we sought to determine if cell lines harboring cancer-specific STAG2 mutations showed similar sensitivity. Using paired GBM cell lines containing either a truncated STAG2 or wild-type STAG2 knock-in, we found that STAG2 mutation status was, indeed, associated with significantly decreased proliferation in the presence of PARP inhibition. Interestingly, olaparib treatment led to an accumulation of cells in the G2 phase of the cell cycle and an increase in DNA damage markers. Furthermore, in the presence of increasing concentrations of olaparib, a higher percentage of STAG2-mutated cells had micronuclei and fragmented nuclei compared to their wild-type STAG2 knock-in counterparts. Taken together, these data suggest that the DNA repair enzyme PARP may be a potential therapeutic SL target for tumors harboring mutations in STAG2.

Citation Format: Melanie L. Bailey, Nigel J. O'Neil, Derek M. van Pel, Phil Hieter. Cells containing mutations in the cohesin component, STAG2, are sensitive to PARP inhibition. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Synthetic Lethal Approaches to Cancer Vulnerabilities; May 17-20, 2013; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(5 Suppl):Abstract nr B16.
Abstract A242: R-spondin 2 drives Wnt signaling and tumor formation in breast and liver cancer.
Authors: Conboy Caitlin B. , Tschida Bobbi R. , Hu Hsiangyu , Burns Michael B. , Temiz Nuri A. , Kuka Timothy , Keng Vincent W. , Toffanin Sara , Harris Reuben S. , Llovet Josep , Starr Timothy K. , Largaespada David A.
Published: August 2014

Background: R-spondins are secreted agonists of Wnt signaling that function in development and promote tissue stem cell proliferation. Rspo2 was identified as a candidate oncogene in intestinal tumors via a Sleeping Beauty transposon insertional mutagenesis screen in mice (1). Further, oncogenic activation of RSPO2 and RSPO3 mediated by recurrent genomic rearrangements has been identified in human colorectal cancer (2). The purpose of the current study was to determine if R-spondins function as oncogenes in other cancer types characterized by active Wnt signaling.

Methods: R-spondin mRNA expression was determined in primary human breast tumors and adjacent normal tissue by quantitative RT-PCR. Affymetrix microarrays were used to assay gene expression and classify by molecular subtype human hepatocellular carcinomas compared to pre-malignant lesions and normal livers. RSPO2 was depleted or overexpressed in breast cell lines by stable transduction with anti-RSPO2 shRNA or RSPO2 cDNA. Resulting changes in gene expression and proliferation were measured by qRT-PCR and MTS assay respectively. RSPO2 was somatically overexpressed in murine liver by hydrodynamic injection and Fah selection in an Fah-null model. Subsequent gene expression studies were conducted by qRT-PCR and immunohistochemistry.

Results: RSPO2 was highly expressed in 12% of primary human breast tumors compared to adjacent normal tissue. Similarly, RSPO2 expression was elevated in the subset of primary human liver cancers with activated Wnt/beta-catenin signaling. In human breast cancer cells with elevated RSPO2 expression, RSPO2 knockdown decreased Wnt signaling and proliferation, while RSPO2 overexpression in a non-tumorigenic breast epithelial cell line potentiated Wnt signaling. Overexpression of RSPO2 in the mouse liver increased Wnt signaling and promoted an enlarged liver phenotype and tumor formation.

Conclusions: These data strongly suggest that RSPO2 is a driver of human breast and liver cancer. Future work will further characterize signaling pathways implicated in RSPO-driven phenotypes, and develop targeted therapy to inhibit RSPO signaling.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A242.

Citation Format: Caitlin B. Conboy, Bobbi R. Tschida, Hsiangyu Hu, Michael B. Burns, Nuri A. Temiz, Timothy Kuka, Vincent W. Keng, Sara Toffanin, Reuben S. Harris, Josep Llovet, Timothy K. Starr, David A. Largaespada. R-spondin 2 drives Wnt signaling and tumor formation in breast and liver cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A242.
Abstract A249: Navitoclax and veliparib yield cytotoxicity with lower doses than used for single agents in women's cancers.
Authors: Lee Jung-Min , Stacy Alyssa , Yu Minshu , Kohn Elise C.
Published: August 2014

Background: The apoptosis inhibitor Bcl-XL is upregulated in recurrent ovarian (Ov) and breast (Br) cancer(Ca)s. Modest clinical activity with navitoclax, Bcl-2, Bcl-XL inhibitor, was observed in hematologic malignancies, although a significant grade 3/4 thrombocytopenia has been a challenge for the further development of navitoclax. Our phase I/Ib study of olaparib (PARP inhibitor) and carboplatin (NCT00647062) in Ov and BrCa patients with BRCA1/2 mutation showed a change in Bim and Bcl-2 tissue protein quantities measured before and after 1 cycle correlated with the duration of response (r2=-0.86, p=0.007). We hypothesized combination of PARP inhibitor, veliparib, with navitoclax will yield clinical synergy at doses lower than used for single agents in women's cancers, thus with the potential to minimize the thrombocytopenia.

Materials and Method: We have examined cell injury in Ov (SKOV3, OVCAR8) and triple negative breast cancer (MDA-MB231) cell lines. Cell injury was measured with XTT assays. The clinically attainable dosage of navitoclax and veliparib were compared to the IC50 and a physiologically attainable dose was obtained. Protein expression of Bcl-2, Bcl-XL, Mcl-1, an anti-apoptotic protein of the Bcl-2 family, BAG3, a chaperone protein stabilizing and preventing degradation of Mcl-1 were examined using immunoblot to identify potential biomarkers.

Results: Veliparib (up to 50uM) had little single agent activity, up to 11% inhibition of control growth in all cell lines; navitoclax also had limited single agent activity in doses attainable clinically, up to 31% inhibition of control growth at 5uM. Concurrent administration of the two agents yielded a dose dependent increase in cell injury in all cell lines (up to 49% inhibition; p<0.05). Protein expression of Bcl-2 and Bcl-XL was reduced by navitoclax and combination of navitoclax and veliparib showed further reduction in all cell lines. Mcl-1 protein expression was reduced by the combination in all cell lines, although BAG3 was reduced by the combination, only in SKOV3. Further analysis of protein expression, drug effects in soft agar density-independent cultures, and survival assays are in progress in other Br and OvCa cell lines.

Conclusions: These preliminary results suggest that the combination of PARP inhibition and Bcl2/Bcl-XL neutralization may be cooperative in yielding better results than either agent alone. Further studies are ongoing to complete credentialing this novel drug combination.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A249.

Citation Format: Jung-Min Lee, Alyssa Stacy, Minshu Yu, Elise C. Kohn. Navitoclax and veliparib yield cytotoxicity with lower doses than used for single agents in women's cancers. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A249.
Abstract A266: Leucovorin rescue of high dose pralatrexate in mesothelioma xenografts.
Authors: Tedeschi Philip M. , Farooqi Iqra , Kathari Yamini , Bertino Joseph R.
Published: August 2014

Pralatrexate is a second generation antifolate that targets dihydrofolate reductase. It was found to have a higher affinity to reduced folate carrier type 1 (RFC-1), the primary folate transporter, and has high intracellular retention via enhanced polyglutamylation. Mucositis, rather than bone marrow toxicity, is the dose limiting toxicity (DLT) in patients. In this study, we examine whether the use of leucovorin (folinic acid) can reduce pralatrexate DLT when used in mouse xenografts, and possibly enable high dose pralatrexate treatment. Nude mice bearing H2052 mesothelioma xenografts were treated with pralatrexate at normal and toxic doses with or without leucovorin administration 24 hours later. Tumors were measured three times weekly and toxicity monitored through weight loss. Leucovorin was found to abrogate pralatrexate toxicities at high doses without sacrificing efficacy. These results demonstrate that high dose pralatrexate with subsequent leucovorin rescue may be a viable treatment strategy in mesothelioma and other cancers.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A266.

Citation Format: Philip M. Tedeschi, Iqra Farooqi, Yamini Kathari, Joseph R. Bertino. Leucovorin rescue of high dose pralatrexate in mesothelioma xenografts. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A266.
Abstract A27: Proteomic study of the of posttranslational modifications (phosphorylation and glycosylation) and its significance in human breast cancer.
Authors: Kaur Navkiran , Jauhari Parul
Published: August 2014

Post translational modifications are the biochemical modifications introduced into the protein after translation (or during translation in case of co-translational modification). Various changes that occur are in the form of chemical groups added to various residues of the target protein by specific enzymes like glycosyltransferase, kinase, methyltransferase, etc. Various studies have shown that cancer cells differ from non-neoplastic cells not only in expression of proteins and their related function, but they also have major differences in the pattern of post-translational modification. These changes may be direct result of difference in expression levels of PTM-responsible enzymes, or differences in the functioning of the same. In the same manner, differences in PTM pattern of cancer proteins leads to many structural and functional changes in the target proteins, many of which may be responsible in furthering the neoplastic characteristics and survival of the cancer cell. Since PTM leads to change in functionality in target proteins, this study aims to find a direct relation between change in function of both pro-apoptotic and anti-apoptotic proteins and cancer cell immortality. Theoretically, pro-apoptotic proteins need to be non-functional for the cell to skip apoptosis, as is often seen in cancer cells. Also, the activity of anti-apoptotic proteins needs to be subdued by PTM to reach the same results. Differential PTM of various proteins in cancer cells with respect to non-neoplastic cells has been seen to be of great significance. This upregulation or downregulation of certain type of specific PTM can be a factor for the overall progression and development of cancer. Present study was desined with an aim to identifying the proteome exclusive to breast cancer cells, and also to study the differential PTM pattern of the same and determine the significance of this difference in various aspects of cancer occurrence, pathogenesis and progression. We found that the there is a significant change in the expression profiling of phosphorylation and glycosylation patterns of various proteins associated with breast cancer as assessed by using various bioinformatic based tools.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A27.

Citation Format: Navkiran Kaur, Parul Jauhari. Proteomic study of the of posttranslational modifications (phosphorylation and glycosylation) and its significance in human breast cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A27.
Abstract A283: PI3K/Akt/mTOR dual inhibitors have an advantage over single inhibitors in overcoming prostate cancer radioresistance.
Authors: Chang Lei , Graham Peter , Hao Jingli , Ni Jie , Bucci Joseph , Cozzi Paul , Kearseley John , Li Yong
Published: August 2014

Purpose: Radioresistance is a major problem in prostate cancer (CaP) radiotherapy (RT). The phosphatidylinositol-3-kinase (PI3K)/Akt/mTOR signaling pathway plays a central role in cancer metastasis and radioresistance. This study aimed to evaluate the effects of combination of dual or single inhibitors targeting PI3K/Akt/mTOR pathway proteins with RT in CaP radioresistant (RR) cells in vitro.

Experimental Design: Three CaP-RR cell lines (PC-3RR, DU145RR, and LNCaPRR) were established in our laboratory by radiation treatment and their radioresistance was confirmed by colony assay. The half maximal inhibitory concentration (IC50) values of four inhibitors including two dual inhibitors (BEZ235 and PI103) and two single inhibitors (BKM120 and Rapamycin) were tested by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in CaP RR cells. Combination of 1/2 IC50 doses of each inhibitor with RT was examined to decide which inhibitor has a better capability to improve radiosensitivity of CaP-RR cells by cologenic assay and apoptosis assays.

Results: We found that CaP-RR cells are associated with epithelial-mesenchymal transition (EMT) and enhanced cancer stem cell phenotypes, and the activation of PI3K/Akt/mTOR signaling pathway. We also found that the combination of single inhibitor either BKM120 (targeting PI3k) or rapamycin (Targeting mTOR) with RT had limited capability to improve radiosensitivity, including less regression of colony formation and inducing less apoptosis in CaP RR cells, whereas dual inhibitor BEZ235 or PI103 combined with RT could effectively improve radiosensitivity, obviously inhibit CaP RR cells in colony ability (P<0.05), and induce more apoptosis (P<0.05).

Conclusions: Our findings suggest that PI3K/Akt/mTOR pathway is actively involved in CaP radioresistance and the dual PI3K/Akt/mTOR inhibitors (BEZ235 and PI103) have obvious advantages over single inhibitors in sensitizing radiation therapy and overcome CaP radioresistance. Using a PI3K/mTOR dual inhibitor with RT is a promising modality for the treatment of CaP to overcome radioresistance and this combination approach is worthwhile for future animal study and clinical trials.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A283.

Citation Format: Lei Chang, Peter Graham, Jingli Hao, Jie Ni, Joseph Bucci, Paul Cozzi, John Kearseley, Yong Li. PI3K/Akt/mTOR dual inhibitors have an advantage over single inhibitors in overcoming prostate cancer radioresistance. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A283.
Abstract B237: CD105: A therapeutic target for sarcomas.
Authors: Fritchie Karen , Attia Steven , Okuno Scott , Arndt Carola , Robinson Steven
Published: August 2014

Purpose: Endoglin/CD105 is a homodimeric transmembrane glycoprotein that is expressed on the proliferating endothelium of solid tumors. TRC105, the chimeric IgG1 antibody with high affinity binding for human CD105, has recently undergone human testing. This exploratory study sought to validate CD105 as a potential therapeutic target in sarcomas.

Methods: We performed immunohistochemical staining for CD105 expression in 146 retrospectively identified paraffin embedded sarcoma patient samples in our tumor registry, utilizing an anti-CD105 antibody (clone 4G11, Novocastra). The diagnoses were verified and samples were examined for CD105 expression in the malignant vasculature as well as tumor cells.

Results: The vast majority of specimen expressed CD105 in the tumor vasculature, 134 of 137 evaluable cases. CD105 expression in the cells of the varied sarcoma histologies themselves were as follows: 19/20 angiosarcomas, 6/7 Ewing sarcomas, 8/20 undifferentiated pleomorphic sarcomas, 6/20 uterine leiomyosarcomas (LMS), 4/20 osteosarcomas, 3/20 non-uterine LMS, 3/20 synovial sarcomas. None of the 19 evaluated chondrosarcoma cells expressed CD105. Thirteen of 19 angiosarcomas showed CD105 expression in >50% of tumor cells, 3 of 19 showed CD105 expression in 25-49% of the tumor cells and 3 of 19 showed CD105 expression in 5-24% of tumor cells.

Conclusions: CD105 targeting appears to be a rational antiangiogenic therapeutic approach in sarcomas, with particular emphasis on angiosarcomas. A clinical trial utilizing TRC105 in soft tissue sarcomas is currently under development.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B237.

Citation Format: Karen Fritchie, Steven Attia, Scott Okuno, Carola Arndt, Steven Robinson. CD105: A therapeutic target for sarcomas. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B237.
Abstract B61: Differential response of normal and malignant urothelial cells to CHK1 and ATM inhibitors.
Authors: Wang Wei-Ting , Catto James , Meuth Mark
Published: August 2014

While DNA damage response pathways are well characterized in cancer cells, much less is known about their status in normal cells. These pathways protect tumor cells from DNA damage and replication stress and consequently present potential therapeutic targets. However, a better understanding of the response of normal cells to DNA damage is needed before a role in cancer treatment can be pursued. Here we characterize the response of hTERT-immortalized normal human urothelial (NHU) cells to agents that disrupt DNA replication. In contrast to malignant cells, the ATR-CHK1 signaling cascade is activated late after treatment with a replication inhibitor in hTERT-NHU cells and these cells do not depend upon the ATR-CHK1 signaling cascade for protection from apoptosis during DNA replication stress. Instead ATM signaling is more rapidly activated under these conditions. Intriguingly, an ATM inhibitor not only suppressed checkpoint activation after exposure to replication inhibitors but also stopped entry of cells into S phase suggesting activation of a G1 checkpoint. Consistent with this, cells treated with the ATM inhibitor and thymidine showed increased levels of cyclin-dependent kinase inhibitor p19INK4D and reduced phosphorylation of the retinoblastoma protein. Nevertheless ATM inhibitor-treated hTERT-NHU cells re-entered S-phase upon release into inhibitor-free medium. In contrast, a bladder cancer cell line treated with the ATM inhibitor progressed more slowly through S-phase and showed a dramatic increase in apoptosis following co-treatment with ATM and replication inhibitors. Taken together, our findings suggest that ATM and CHK1 signaling cascades play different roles in tumor and normal epithelial cells, confirming these as promising therapeutic targets.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B61.

Citation Format: Wei-Ting Wang, James Catto, Mark Meuth. Differential response of normal and malignant urothelial cells to CHK1 and ATM inhibitors. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B61.