Abstract PD1-2: PIK3CA mutations and/or low PTEN predict resistance to combined anti-HER2 therapy with lapatinib and trastuzumab and without chemotherapy in TBCRC006, a neoadjuvant trial of HER2-positive breast cancer patients

We have recently reported that in patients with HER2-positive breast cancer, neoadjuvant targeted therapy with lapatinib and trastuzumab to more completely block the HER receptor layer, combined with endocrine therapy (in ER-positive tumors) and without chemotherapy led to a substantial 27% pathologic complete response (pCR) rate in the breast. Activation of downstream signaling pathways may lead to resistance to therapies targeting the HER pathway receptors. Aberrant activation of the PI3K pathway via decreased levels of PTEN and/or the presence of activating PIK3CA mutations has been implicated in resistance to targeted anti-HER2 therapy, but results of clinical trials are all confounded by the co-administration of chemotherapy and are inconsistent. We sought to clarify the role of these variables in predicting pCR, a surrogate for long-term outcome, in patients treated with potent targeted therapy alone in a prospective Phase II neoadjuvant trial in patients with HER2-positive breast cancer.

Patients with large tumors (median 6 cm) were given 12 weeks of lapatinib plus trastuzumab followed by surgery (Rimawi et al. JCO, 2013). Serial tissue biopsies were obtained from study participants. For this study, we focused on baseline pre-treatment characteristics. PTEN protein levels were measured by IHC and scored using the H-score. PIK3CA mutations were identified on extracted DNA using multiplex PCR with targeted next generation sequencing (the Ion Torrent 50-gene cancer mutation panel).

Of 64 evaluable patients, tissue was available on 59 for PTEN IHC, and sufficient DNA was available on 33 for the mutation panel. PTEN median H-score was 100 (range 0-300). PTEN status when dichotomized by the median was correlated with pCR (32% in high PTEN vs. 9% in low PTEN, p = 0.04). Activating PIK3CA mutations were identified in 12 out of 33 tumors (36%; 3 mutations in the helical and 9 in the catalytic domain) and were independent of ER status. None of the patients whose tumors harbored a PIK3CA mutation achieved pCR (p = 0.06). There was no association between PTEN status and PIK3CA mutation suggesting they are independent variables (p = 0.44). When PIK3CA mutations were considered together with PTEN status, there were 31 cases with data on both. The overall pCR rate in this cohort was 16% (lower than pCR rate observed in the overall trial). However, 0/17 cases (0%) with a mutation and/or PTEN low expression (<100 H score) had a pCR compared to 5/14 cases (36%) with PI3KCA wild type and high PTEN levels (p = 0.01).

We conclude that PI3K pathway activation downstream of HER2 as a result of either low PTEN or activating PIK3CA mutation results in resistance to the combination of lapatinib and trastuzumab. This is the first report on patient tissue samples from a neoadjuvant trial using the combination of lapatinib and trastuzumab without chemotherapy. If validated in a larger cohort, our findings suggest that patients with HER2 positive tumors and who also harbor aberrant downstream PI3K pathway activation may benefit from the addition of PI3K/Akt/mTOR inhibitors to potent HER2 blockade.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD1-2.

Abstract P4-19-04: Biobank management and tracking web-based system for a breast cancer oriented biobank v2.0: Preliminary analysis

The quality of biospecimens and associated data accuracy in a Biobank must be collected and consistent according to standardized methods in order to achieve international harmonization and coordination among biobanking networks.

Sharing successful strategies between the Baylor College of Medicine (BCM) Breast and Cancer Centers and Breast Center Buenos Aires (BCBA) was the fundamental stone for the creation of an Argentinean Breast Cancer oriented Biobank with a shared data management system. We have designed, developed and implemented a computer system to easily manage sensible associated data. This innovative system, allows the data entry in a visual, intuitive, friendly and orderly way, integrating all the information for further analysis and easy use of samples for translational research.

Objective: Develop and improve (v2.0) a bilingual web-based tool for biospecimen management, inventory, clinical and breast cancer data registration according with international standards of data security quality assurance and ISBER Best Practices for Biorepositories.

Methods: System Characteristics:

Multi-tier architecture, relying on a SQL server 2008 R2 data base. Operating System: Windows Server Series. Programmer Language .net 4.0 C#.. The system operates with Internet Explorer as flat client or similar.

Bilingual English/Spanish system, fully configurable by modules, HIPPA compliant sensible data confidentiality, with de-identification of samples through 2D bar codes.

Results : System Capabilities and Improvements v2.0:

• Security Module: Allows to manage predetermined profiles (Clinical Research Coordinator Clinical staff as Phlebotomist, Pathologist, PA, MDs, PhDs, Researchers), audit controls implemented through permits according to the profile.

• Master Tables: allows to insert/add/change data associated into master tables, providing system user independence.

• General Registration Module: Online statistics allows to see immediately the number of consented individuals, types of samples and their classification.

• Sample Management: Assigns unequivocally identification of each sample in a 2D bar code for freezer lab labels(LabExpert®). Has online statistical information on the number of samples and tubes used, for an easy supply management. Automatically assigns the location of samples per product type in the freezer. Allows to know the occupancy rate online.

• Breast Cancer Module: A comprehensive data base in an attractive visual environment of eight screens: Clinical data, Biopsy, Definitive Surgery, Systemic Treatment, Radiation Treatment, Cancer Events, follow up and Summary screen. Includes path reports and sample collection forms attached in each corresponding biopsy or surgery screen for easy view and data entry quality assurance.

Conclusion: This Biobank Management System was designed in a friendly and intuitive data entry environment by a multidisciplinary team including breast surgeons, pathologists, oncologists, statisticians, system engineers and programmers from BCM and BCBA. It could be adapted to be used in full or in separate modules by Breast Centers and Breast Cancer Oriented Biobanks.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-19-04.

Abstract P4-19-03: Breast cancer oriented biobank and associated biobank management system: Preliminary analysis on 9043 samples from 274 individuals

Four years ago, after our Baylor College of Medicine (BCM) Breast and Cancer Centers experience, we decided to initiate a related translational research Project at the Breast Center Buenos Aires (BCBA) in Argentina. This included the development of a breast cancer-oriented Management System for clinical and lab data attached to a biorepository of tumor and normal breast tissue with matched blood specimens. We strictly followed ISBER Best Practices for Biorepositories, and shared the same protocols and strategies with BCM to facilitate international collaborative breast cancer research, being extremely aware of international standards.

Objectives: Creation of a breast cancer-oriented blood, breast tissue and tumor biobank for translational research purposes. Creation of a Biobank Management and Tracking System, with a breast cancer database for associated epidemiological, pathological, clinical, and follow-up data of each patient.

Methods: From April 2011 to June 2013 we processed blood and tissue samples from BCBA. Blood is collected at several time points during the breast cancer disease process: pre-surgical, pre-systemic treatment, and, if applicable, in the metastatic setting. Blood products are stored as whole blood, plasma, buffy coat, red blood cell pellet, serum and clot at -80°C or in GenPlates®. Fresh tissue and tumor samples were collected during surgical or core biopsy proceedings and stored fresh at -80°C in 1 ml cryovials and as FFPE (formalin-fixed paraffin embedded) tissue. Upon enrollment, participants completed an extensive epidemiological and risk factor questionnaire, which is supplemented by medical record abstraction for relevant pathological and clinical data, and re-contacted once a year for follow-up.

Preparation and adaptation processes were compliant with the Population Sciences Biorepository and Smith Breast Center Tumor Bank at BCM: 1) IRB-approved informed consent documents 2) Epidemiological and risk factor questionnaires (Core/Breast module); 3) Blood and tissue collection and processing protocols.

A web-based data management and tracking system was specifically designed for the BCBA biobank.

Results:

To date, we have collected 9043 samples, from 274 individuals, in 293 sample collections. Of 5449 frozen samples, 5054 (92.7%) are blood and 395 (7.3%) are tissue. We also collected 3264 blood samples in GenPlate® wells from 68 patients on 17 plates, and extracted DNA from them into Gentegra® tubes, all stored at room temperature.

230 FFPE breast cancer tissue biopsies from 20 surgical specimens, given by the pathologist after diagnosis, stored in cassettes at room temperature in our lab, were also included in the system starting from January 2013.

All of them have been classified by the physician into three categories: Healthy Control 15.3% (n = 42), Benign 55.1% (n = 151) and Cancer 29.6% (n = 81). We collected epidemiological, and cancer data from all of them in our system.

Conclusion: It took nearly 4 years from inception to realization for this biobank; however, the potential benefit to translation breast cancer research is large. The overall value of this biobank will depend on the number of individuals/samples accrued, the follow-up attained and data accuracy.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-19-03.

Pilot study exploring lung allograft surfactant protein A (SP-A) expression in association with lung transplant outcome

Primary graft failure and chronic lung allograft dysfunction (CLAD) limit lung transplant long-term outcomes. Various lung diseases have been correlated with surfactant protein (SP) expression and polymorphisms. We sought to investigate the role of SP expression in lung allografts prior to implantation, in relation to posttransplant outcomes. The expression of SP-(A, B, C, D) mRNA was assayed in 42 allografts. Posttransplant assessments include pulmonary function tests, bronchoscopy, broncho-alveolar lavage fluid (BALF) and biopsies to determine allograft rejection. BALF was assayed for SP-A, SP-D in addition to cytokines IL-8, IL-12 and IL-2. The diagnosis of CLAD was evaluated 6 months after transplantation. Lung allografts with low SP-A mRNA expression prior to implantation reduced survival (Log-rank p < 0.0001). No association was noted for the other SPs. Allografts with low SP-A mRNA had greater IL-2 (p = 0.03) and IL-12 (p < 0.0001) in the BALF and a greater incidence of rejection episodes (p = 0.003). Levels of SP-A mRNA expression were associated with the SP-A2 polymorphisms (p = 0.015). Specifically, genotype 1A1A(0) was associated with lower SP-A mRNA expression (p < 0.05). Lung allografts with low levels of SP-A mRNA expression are associated with reduced survival. Lung allograft SP-A mRNA expression appears to be associated with SP-A gene polymorphisms.

Cardiovascular risk in recipients with kidney transplants from expanded criteria donors

INTRODUCTION

Posttransplant cardiovascular disease (CVD) is the leading cause of death in renal transplant (RT) recipients and is more evident in recipients with transplants from expanded criteria donors (ECD).

OBJECTIVES

We analyzed the evolution of cardiovascular risk factors and their association with patient mortality.

MATERIALS AND METHODS

We undertook a single-center, prospective study of RT patients (n = 360) between 1999 and 2006. These were 180 recipients with transplants from ECD and 180 controls. We analyzed the baseline characteristics and the cardiovascular risk factors: hypertension, diabetes, dyslipidemia, CVD, and anemia. Posttransplant analyses included the evolution of cardiovascular risk factors and causes of death.

RESULTS

The mean age of the ECD was 63.5 ± 5.4 versus 32.0 ± 13.2 years in the non-ECD (P < .001) and the recipient ages were 58.4 ± 8.7 versus 40.8 ± 13.3 years, respectively (P < .001). The median interquartile range [IQR] dialysis time was 25 months (15-39) versus 20 months (12-44; P = .017). The pretransplant body mass index was 26.89 ± 3.91 versus 25.43 ± 4.72 kg/m(2) (P = .002); the median (IQR) number of antihypertensive drugs was two (1-2) versus two (1-2.75; P = .015); dyslipidemia was present in 32.5% versus 21.6% (P = .024), diabetes in 10.6% versus 5.6% (P = .087), and CVD in 13.3% versus 7.8% (P = .086). Treatment with erythropoiesis-stimulating agents (ESA) was received by 84.9% versus 83.9% (P = .857). Concerning transplantation, the mean follow-up was 64.3 ± 33.7 months. Hypertension was present at 3 and 5 years in 85.6% versus 69.5% (P = .001) and 87.9% versus 72.8% (P = .009), respiratory. Treatment with angiotensin-converting enzyme inhibitors/angiotensin-II receptor blockers at 3 and 5 years was 79.8% versus 64.5% and 85.6% versus 65%. Dyslipidemia was present at 5 years in 63.1% versus 58.0% (P = .482). De novo diabetes occurred in 16.7% versus 11.1% (P = .128), and CVD in 13.5% versus 4.5% (P = .003). Univariate and multivariate Cox regression proportional hazards models were constructed to analyze the factors associated with patient death.

CONCLUSIONS

CVD is the most common cause of death in recipients of ECD, RT, 40% in the ECD group versus 28.6% in the control group. Tight control of cardiovascular risk factors and a good pretransplant patient selection contributed to the good results obtained.

Hypovitaminosis D and incidence of obesity: a prospective study

The aim of this study was to assess the relationship between obesity and vitamin D status cross-sectionally, the relationship between obesity and the incidence of hypovitaminosis D prospectively and inversely the relationship between vitamin D status and incidence of obesity in a population-based cohort study in Spain. At baseline (1996-1998), 1226 subjects were evaluated and follow-up assessments were performed in 2002-2004 and 2005-2007, participants undergoing an interview and clinical examination with an oral glucose tolerance test. At the second visit, 25-hydroxyvitamin D and intact parathyroid hormone concentrations were also measured. Prevalence of obesity at the three visits was 28.1, 36.2 and 39.5%, respectively. The prevalence of vitamin D deficiency (25-hydroxyvitamin D ≤ 20 ng/ml (≤ 50 nmol/l)) was 34.7%. Neither obesity at baseline (OR=0.98, 95% CI: 0.69-1.40, P=0.93) nor the development of obesity between baseline and the second evaluation (OR=0.80, 95% CI: 0.48-1.33, P=0.39) were significantly associated with vitamin D status. In subjects who were non-obese (BMI <30 kg/m²) at the second evaluation, 25-hydroxyvitamin D values ≤ 17 ng/ml (≤ 42.5 nmol/l) were significantly associated with an increased risk of developing obesity in the next 4 years (OR=2.35, 95% CI: 1.03-5.4, P=0.040 after diverse adjustments). We conclude that vitamin D deficiency is associated with an increased risk of developing obesity.

Abstract S5-8: Parallel upregulation of Bcl2 and estrogen receptor (ER) expression in HER2+ breast cancer patients treated with neoadjuvant lapatinib

Background: We previously showed in HER2+ models of breast cancer (BC) that potent inhibition of the HER receptor layer can lead to re-expression of estrogen receptor (ER) or activation of the ER pathway. Consequently, the anti-apoptotic ER gene product Bcl2 is upregulated, resulting in enhanced tumor cell survival and treatment resistance. In this study, we investigated whether Bcl2 and ER expression levels are simultaneously increased by neoadjuvant treatment with the dual HER1/2 tyrosine kinase inhibitor lapatinib in HER2+ BC patients.

Methods: In a neoadjuvant phase II clinical trial 49 HER2+ BC patients were treated with lapatinib as a single agent for 6 weeks, followed by trastuzumab/docetaxel for 12 weeks before surgery. Tumor specimens were prospectively collected at different time-points during lapatinib treatment (baseline, and weeks 2 and 4). Bcl2, ER, progesterone receptor (PR), total (t) and phosphorylated (p)-HER2, and Ki67 were assessed by immunohistochemistry. Spearman correlation was used to evaluate the association among the biomarkers at baseline, and the correlation of their changes over time. Fisher's Exact test and non-parametric Wilcoxon rank sum test were used respectively to determine if the frequency and the magnitude of Bcl2 expression changes were associated with baseline ER status.

Results: 35/49 HER2+ tumor specimens (71%) were available for baseline evaluation of Bcl2 and ER. Of those, 12 (34%) were ER-positive (Allred score ≥ 3) and 23 (66%) ER-negative. Baseline Bcl2 expression correlated positively with ER (r = .75; p &lt; .0001) and PR (r = .53; p = .0015), and inversely with t-HER2 (r = −.43; p = .0097). ER baseline expression correlated positively with PR (r = .57; p = .0004), and inversely with t and p-HER2 (r = −.55; p = .0005, and r = −.37; p = .0282, respectively) and Ki67 (r = −.39; p = .0271). Bcl2 changes at week 2 (w2) positively correlated with changes in both ER and PR levels (r = .70; p = .0002 and r = .57; p = .0076, respectively). Additionally, the increase in Bcl2 expression, observed in 9 of the 23 (39%) tumors with tissue available at w2, was significantly more frequent (p = .0147) and of greater magnitude (p = .0001) in ER-pos vs. ER-neg tumors — 8/9 ER-pos tumors at w2 (including 3 converted from ER-neg by lapatinib) had increased Bcl2, while only 1 of the 14 (7%) ER-neg tumors (at baseline and w2) had increased Bcl2. The expression of ER itself at w2 also increased in 3 out of the 6 (50%) tumors which were originally ER-pos and had tissue available at w2, and in all of them Bcl2 increased in parallel. Of note, the single baseline ER-pos tumor that showed a reduction in ER at w2 had a parallel decrease in Bcl2. Similar observations or trends were found at week 4.

Conclusion: Our study suggests that Bcl2 is upregulated as a result of enhanced/restored ER activity upon anti-HER2 therapy with lapatinib in HER2+ tumors. This further supports the use of endocrine along with anti-HER-2 therapy to block this escape pathway which could otherwise cause treatment resistance. In addition, the ER re-expression with lapatinib treatment observed in this study emphasizes the need to re-biopsy HER2+/ER− patients receiving anti-HER2 therapy and to add endocrine therapy if the tumor becomes ER-positive.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr S5-8.

Abstract P2-16-02: A web-based data management system for a multicenter international breast cancer oriented blood, tissue, and data biobank

The quality of biospecimens and associated data must be consistent and collected according to standardized methods in order to achieve international harmonization and coordination among biobanking networks.

Sharing successful strategies between the Baylor College of Medicine (BCM) Cancer Center and Breast Center Buenos Aires (BCBA) is the driving force for the creation of an Argentinean Breast Cancer oriented Biobank with a shared data management system.

Objective: To create a bilingual web-based tool for biospecimen management, inventory, clinical and breast cancer data registration according to international standards of data security quality assurance (ISO 27001).

Methods/System Characteristics: The system permits users to enter and retrieve data concerning the collection, storage, quality assurance and distribution of biospecimens, and provides clinical and other patient data for samples while maintaining strict patient confidentiality.

It has a multi-tier architecture, developed using Service-Oriented Architecture (SOA) software design principles in .net 4.0, and uses a SQL server database backbone. The system allows multidimensional data analysis trough On Line Analytical Processes (OLAP) and operates with standard web clients, such as Internet Explorer.

User Profiles/Access Levels: Clinical staff (e.g., clinical research coordinator, phlebotomist, pathologist, PA, MD) conduct participant and consent registration and preregistration, epidemiological questionnaire data entry, barcode label generation, form printing, and clinical and pathological cancer data entry.Biospecimen resource staff (e.g., lab technicians) track and store data about biospecimen collection, inventory, tracking and distribution, generate sample barcode labels, and maintain sample allocation and freezer maps for the system.Scientists have the ability to search for biospecimens and associated data for their own translational research projects.

Breast Cancer Database: Detailed clinical, pathological, treatment and follow-up breast cancer information are captured for each patient, including TNM, biopsy and definitive surgery of primary tumor and events, systemic and radiation treatment, recurrences and metastasis, follow-up. A summary screen provides a snapshot of these data to the viewer. Pathology reports and sample collection forms are attached in each corresponding biopsy or surgery screen for easy viewing and quality assurance.

Conclusion: This Biobank Management System was designed by a multidisciplinary team to improve and streamline the workflow for each member of the biobank by: allowing preregistration capabilities before consenting individuals or collecting samples, automatic generation of clinical and sample ID labels, and real-time statistics with certified secure sensible information confidentiality. This system's value is its wide range of uses, from the day-to-day management of a multicenter biobank to the storage of detailed clinical cancer-related data in a user-friendly and intuitive data entry environment.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-16-02.

Effect of preen oil on plumage bacteria: an experimental test with the mallard

Feathers are essential for avian thermoregulation, communication or flight and a reduction of plumage condition may alter these functions and reduce individual fitness. Recently, descriptive studies provided evidence that birds carry feather-degrading bacteria on their plumage that have the ability to degrade feathers rapidly under laboratory conditions. If such bacteria reduce avian fitness, natural selection should favour the evolution of anti-bacterial defences to limit the effects of these detrimental microorganisms. Preening behaviour and associated preen gland secretions have been proposed as the main factor used by birds to limit feather-degrading bacterial growth and some recent in vitro studies provided evidence that uropygial oil inhibited the growth of some keratinolytic strains in passerines. However, preen oil antimicrobial properties remained to be experimentally tested in vivo. We conducted an experiment with mallards (Anas platyrhynchos) onto which we fixed a removable mechanism that blocked access to the uropygial gland in a first group of mallards, whilst birds in a second group had the same removable mechanism but access to their gland and a third group of birds had normal access to their gland. We found no significant effect of our treatment on total and feather-degrading bacterial loads. Three hypotheses may explain the discrepancy between our results and previous in vitro studies. First, in vitro studies may have over-estimated the bactericidal properties of the preen oil. Second, preen gland deprivation may have affected only a small portion of the feather-degrading bacterial community. Third, ducks and passerine oils might have different bactericidal properties.

P5-21-01: A Renewable Tissue Resource of Phenotypically Stable Human Breast Cancer Xenografts for Preclinical Studies

Introduction Translational breast cancer research is hampered severely by difficulties in obtaining and studying primary human breast tissue, and by the lack of in vivo preclinical models that accurately reflect patient tumor biology. These limitations are due, in part, to the fact that traditional immunocompromised mouse models are not generally permissive for growth. We sought to circumvent some of these limitations by transplanting and growing human mammary tumors in the mammary fat pad of SCID/Beige immunocompromised mice in the absence of exogenous human fibroblasts.

Aims and Methods To establish a set of stable human breast cancer xenografts for preclinical studies. Human breast cancer biopsies were received, minced into small fragments and then transplanted directly into “cleared” fat pads of recipient SCID/Beige immunocompromised mice. Transplanted fat pads were checked weekly. After initial tumor was palpated and harvested, tumor fragments were transplanted into new SCID/Beige hosts for subsequent transplant generations. Serial immunohistochemical evaluations were performed to confirm human origin and biomarker status. Analytical flow cytometry for evaluating expression of proposed “cancer stem cell” markers, and gene and protein expression analysis were carried out on all stable lines.

Results and Conclusions Xenograft lines were established directly from breast cancer patient samples, without intervening culture in vitro, using the epithelium-free mammary fat pad as the transplantation site. Of the conditions tested, xenograft take rate was highest in the presence of a low-dose estradiol pellet without exogenous human fibroblasts. Thirty six stably transplantable xenograft lines representing 27 patients were established, using pre-treatment, mid-treatment, and/or post-treatment samples. Most patients yielding xenografts were “triple-negative” (ER-PR-HER2−) (n=21), we were able to establish lines from three ER-PR-HER2+ patients, one ER+PR+HER2−, one ER+PR-HER2−and one “triple-positive” (ER+PR+HER2+) patients. Serially passaged xenografts show phenotypic consistency with the tumor of origin at the histopathology level, and remarkable stability across multiple transplant generations at both the genomic, transcriptomic, and proteomic levels. Of 27 lines evaluated fully, thirteen xenografts showed metastasis to the mouse lung. These models thus serve as a renewable, quality-controlled tissue resource, and should prove useful for preclinical evaluation of experimental therapeutics.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-21-01.

P4-01-18: AP-1 Blockade Potentiates the Anti-Tumor Effect of Endocrine Treatment and Reverts the Resistant Phenotype in Hormone Receptor-Positive Breast Cancer

Background: Resistance to endocrine therapy is a major clinical issue. The transcription factor AP-1 is a key regulator of cell growth and survival as well as a downstream signaling component of several pathways deregulated in endocrine-resistant breast cancer. We have previously shown that acquired endocrine resistance is associated with increased AP-1 activity. AP-1 has also been shown to interact with and modulate the ER network and transcriptional program, especially under hyperactive growth factor signaling, which is commonly associated with endocrine resistance. We hypothesized that interfering with AP-1 function would circumvent endocrine resistance possibly due to its role in modulating ER transcriptional activity.

Methods and results: We inhibited AP-1 function by a genetic approach. We used two different MCF7 clones stably transfected with a Doxycycline (Dox)-inducible dominant-negative (DN) c-Jun (MCF7/Tet-Off Tam67 clones 62 and 67) and two vector-alone control MCF7 clones. Xenografts of these clones were established in ovariectomized nude mice supplemented with estrogen (E2). Mice were then randomized to continued E2 supplementation (control) or to endocrine therapy with either estrogen deprivation (ED) or tamoxifen (Tam), all in the presence or absence of Dox to induce the DN c-Jun expression. AP-1 blockade in both MCF7/Tet-Off Tam67 clones significantly enhanced sensitivity to Tam by reducing time to tumor size halving (p=.014 and p=.006 for clone 62 and 67, respectively) and time to complete tumor disappearance (p=.001 and p=.0034 for clone 62 and 67, respectively). Similar results were obtained with ED treatment. In addition, AP-1 blockade significantly delayed the onset of Tam resistance by increasing time to tumor size doubling (p=.0028). Furthermore, induction of DN c-Jun resulted in a dramatic shrinkage of growing tumors after long-term Tam treatment, suggesting reversal of endocrine resistance with AP-1 blockade. None of the above effects was observed in control clones upon Dox removal. Interestingly, no significant effect of AP-1 blockade was observed on E2-stimulated tumor growth. IHC analysis showed that AP-1 blockade induced tumor response by reducing proliferation (i.e., decreased % of Ki67- and phospho-Histone 3-positive cells) and by inducing apoptosis (i.e., increased % of cleaved caspase 3/7-positive cells). Bioinformatic analyses were conducted to intersect our MCF7 xenograft/Tam-resistant gene signature and the datasets of genes associated with ER DNA-binding sites obtained by whole-genome ER cistromic analysis under estrogen or epidermal growth factor (EGF) stimulation of MCF7 cells. A significant enrichment of the genes associated with the EGF-unique ER DNA-binding sites was observed within our Tam-resistant signature (p&lt;2E-16). Remarkably, 90% of these DNA binding sites harbored an AP-1 motif.

Conclusions: We show that AP-1 blockade increases tumor sensitivity and circumvents resistance to endocrine therapy, thus warranting the development of AP-1-targeted therapy to improve endocrine treatment outcomes. Overall, we suggest that AP-1 is critical in induction of a switch in the ER transcriptional program and may be a new hallmark of endocrine resistance.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-01-18.

Surveillance programme for important equine infectious respiratory pathogens in the USA

The prevalence and epidemiology of important viral (equine influenza virus [EIV], equine herpesvirus type 1 [EHV-1] and EHV-4) and bacterial (Streptococcus equi subspecies equi) respiratory pathogens shed by horses presented to equine veterinarians with upper respiratory tract signs and/or acute febrile neurological disease were studied. Veterinarians from throughout the USA were enrolled in a surveillance programme and were asked to collect blood and nasal secretions from equine cases with acute infectious upper respiratory tract disease and/or acute onset of neurological disease. A questionnaire was used to collect information pertaining to each case and its clinical signs. Samples were tested by real-time PCR for the presence of EHV-1, EHV-4, EIV and S equi subspecies equi. A total of 761 horses, mules and donkeys were enrolled in the surveillance programme over a 24-month study period. In total, 201 (26.4 per cent) index cases tested PCR-positive for one or more of the four pathogens. The highest detection rate was for EHV-4 (82 cases), followed by EIV (60 cases), S equi subspecies equi (49 cases) and EHV-1 (23 cases). There were 15 horses with double infections and one horse with a triple infection. The detection rate by PCR for the different pathogens varied with season and with the age, breed, sex and use of the animal.