Abstract P5-10-02: Investigating the response and adaptation of estrogen receptor (ER)+ tumors in response to decreased estrogen availability using an agent-based model of the mammary epithelium

Introduction: Breast tumors consist of heterogenous cell populations with dominant features that can change over time. The development of resistance to previously effective therapies is an example of tumor evolution in response to selective pressure, where the differential composition of cells within a tumor may predispose to identifiable patterns of tumor growth and progression. We employ a previously developed computational model of ductal epithelial dynamics (the Duct Epithelial Agent Based Model or DEABM), able to reproduce known rates of tumorigenesis in both wild-type and BRCA1 populations, to investigate the putative population dynamics of ER+ tumors in response to decreased estrogen availability (DEA).

Methods: The DEABM is composed of computational agents representing individual cells (luminal and myoepithelial cells, their progenitor cells and fibroblasts) behaving based on rules established from published cellular and molecular mechanisms. Cells implement DNA damage/repair, cell division in response to estrogen/local growth factors, and apoptosis. Unrepaired DNA damage impacts genomic integrity, including eight representative oncogenes and tumor suppressors affecting critical pathways previously implicated in breast cancer (BRCA1, P53, E-cadherin, RUNX3, Myc, TGF-beta, MMP-3 and Telomerase). ER+ tumors were generated in 40 year simulations of wild-type and BRCA1 populations and subjected to DEA (90% reduction in estrogen effect targeted to ER+ cells, which could generally represent endocrine therapy for breast cancer.) Cell populations were characterized by mutation profiles, ER status, and response to estrogen suppression. Simulations were continued until development of DEA resistance, identified by reversal of growth suppression, and the mutations present at that point were analyzed for change.

Results: 3500 DEABM simulations over 40 years generated 69 wild-type ER+ tumors and 119 BRCA ER+ tumors. Of these 25% of wild-type ER+ tumors were sensitive to DEA vs. 35% of BRCA1 tumors, consistent with previously reported response rates. The percentage of ER+ cells was higher in initially sensitive tumors than in initially resistant tumors (84% vs. 66%, p = .001). Tumors initially resistant to DEA were more likely to carry mutations in the genes p53, E-cadherin and Myc (p = .001). Sensitive tumors acquired a significant increase in mutations during the interval between responsiveness to DEA and development of resistance (p = .001). Lastly, sensitive BRCA1 carriers were more likely to convert from ER+ to ER- status (p = .001).

Discussion: The DEABM generated simulated breast tumors with intra-tumoral heterogeneity that demonstrate varied responsiveness to DEA, similar to what is observed clinically. These results suggest there may be definable patterns of tumor evolution in response to DEA that could potentially guide the development or sequencing of therapeutic regimens. Computational models such as the DEABM can aid in visualizing molecular data in a dynamic form and allow researchers to carry out “thought experiments” concerning tumor behavior and intervention effect.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-10-02.

Utilization of radiotherapy for malignant phyllodes tumors: analysis of the National Cancer Data Base, 1998-2009

BACKGROUND

Malignant phyllodes tumors of the breast have traditionally been treated with surgical excision. Recently, the use of adjuvant radiotherapy has been advocated to reduce the risk of local recurrence; however, this recommendation is controversial in the absence of consistent outcome data. We hypothesize that there has been a trend toward increased utilization of adjuvant radiotherapy for malignant phyllodes tumors despite its uncertain effect on outcomes.

METHODS

Using the National Cancer Data Base, predictors of radiotherapy utilization were examined for women with malignant phyllodes from 1998 to 2009. Kaplan-Meier and Cox regression models were generated to determine the effect of radiotherapy on local recurrence (LR), disease-free survival (DFS), and overall survival (OS).

RESULTS

Of the 3,120 patients with malignant phyllodes, 57 % underwent breast conservation surgery and 42 % underwent mastectomy. Overall, 14.3 % of women received adjuvant radiotherapy. Utilization of radiotherapy doubled over the study period (9.5 % in 1998-1999 vs. 19.5 % in 2008-2009, p < 0.001). Women were significantly more likely to receive radiotherapy if they were diagnosed later in the study, were age 50-59 years old, had tumors >10 cm, or had lymph nodes removed. For the 1,774 patients with available recurrence data, overall recurrence was 14.1 %, and LR was 5.9 %. In adjusted models, adjuvant radiotherapy reduced LR (aHR 0.43, 95 % CI 0.19-0.95) but did not impact DFS or OS after 53 months' median follow-up.

CONCLUSIONS

Utilization of adjuvant radiotherapy for malignant phyllodes doubled from 1998 to 2009. Radiotherapy significantly reduced LR but had no effect on DFS or OS.

Dietary intakes of total and specific lignans are associated with clinical breast tumor characteristics

Dietary lignans may affect breast cancer by modifying tumor characteristics likely to affect prognosis. We investigated usual dietary intakes of total and specific lignans with tumor characteristics in 683 women with breast cancer and 611 healthy women without breast cancer enrolled in the Data Bank and BioRepository at Roswell Park Cancer Institute (RPCI). Clinicopathologic data were abstracted from the RPCI breast cancer database. Dietary lignan intakes were calculated from FFQ. OR and 95% CI were estimated with logistic regression adjusting for potential confounders and stratified by menopausal status. Women in the highest compared to the lowest tertile of total lignan intakes had a 40-50% lower odds of breast cancer regardless of menopausal status and substantially reduced odds of an invasive tumor, especially among premenopausal women [OR 0.48 (95% CI 0.26-0.86)]. Lignan intakes were inversely associated with odds of grade 3 tumors among premenopausal women. Lignan intakes were inversely associated with risk of estrogen receptor (ER) negative (ER(-)) breast cancer among premenopausal women [OR 0.16 (95% CI 0.03-0.44)] and particularly triple negative tumors [ER(-), progesterone receptor negative, HER2 negative; OR 0.16 (95% CI 0.04-0.62)]. There were significant differences in the contribution to these effects by specific lignans, especially matairesinol and lariciresinol. In summary, in this case-control study of dietary lignan intakes and breast cancer, we found that higher lignan intakes were associated with lower risks of breast cancer with more favorable prognostic characteristics. Future investigations are warranted to explore the strong associations observed with ER(-) cancer in premenopausal women.

The expression of TRMT2A, a novel cell cycle regulated protein, identifies a subset of breast cancer patients with HER2 over-expression that are at an increased risk of recurrence

Background

Over-expression of HER2 in a subset of breast cancers (HER2+) is associated with high histological grade and aggressive clinical course. Despite these distinctive features, the differences in response of HER2+ patients to both adjuvant cytotoxic chemotherapy and targeted therapy (e.g. trastuzumab) suggests that unrecognized biologic and clinical diversity is confounding treatment strategies. Furthermore, the small but established risk of cardiac morbidity with trastuzumab therapy compels efforts towards the identification of biomarkers that might help stratify patients.

Methods

A single institution tissue array cohort assembled at the Clearview Cancer Institute of Huntsville (CCIH) was screened by immunohistochemistry staining using a large number of novel and commercially available antibodies to identify those with a univariate association with clinical outcome in HER2+ patients. Staining with antibody directed at TRMT2A was found to be strongly associated with outcome in HER2+ patients. This association with outcome was tested in two independent validation cohorts; an existing staining dataset derived from tissue assembled at the Cleveland Clinic Foundation (CCF), and in a new retrospective study performed by staining archived paraffin blocks available at the Roswell Park Cancer Institute (RPCI).

Results

TRMT2A staining showed a strong correlation with likelihood of recurrence at five years in 67 HER2+ patients from the CCIH discovery cohort (HR 7.0; 95% CI 2.4 to 20.1, p < 0.0004). This association with outcome was confirmed using 75 HER2+ patients from the CCF cohort (HR 3.6; 95% CI 1.3 to 10.2, p < 0.02) and 64 patients from the RPCI cohort (HR 3.4; 95% CI 1.3-8.9, p < 0.02). In bivariable analysis the association with outcome was independent of grade, tumor size, nodal status and the administration of conventional adjuvant chemotherapy in the CCIH and RPCI cohorts.

Conclusions

Studies from three independent single institution cohorts support TRMT2A protein expression as a biomarker of increased risk of recurrence in HER2+ breast cancer patients. These results suggest that TRMT2A expression should be further studied in the clinical trial setting to explore its predictive power for response to adjuvant cytotoxic chemotherapy in combination with HER2 targeted therapy.

TLE3 as a candidate biomarker of response to taxane therapy

Introduction

The addition of taxanes (Ts) to chemotherapeutic regimens has not demonstrated a consistent benefit in early-stage breast cancer. To date, no clinically relevant biomarkers that predict T response have been identified.

Methods

A dataset of immunohistochemistry stains in 411 patients was mined to identify potential markers of response. TLE3 emerged as a candidate marker for T response. To test the association with T sensitivity, an independent 'triple-negative' (TN) validation cohort was stained with anti-TLE3 antibody.

Results

TLE3 staining was associated with improved 5-year disease-free interval (DFI) in the overall cohort (n = 441, P < 0.004), in patients treated with cyclophosphamide (C), methotrexate, and 5-fluorouracil (n = 72, P < 0.02), and in those treated with regimens containing doxorubicin (A) and a T (n = 65, P < 0.04). However, no association was shown with outcome in untreated patients (n = 203, P = 0.49) or those treated with a regimen containing A only (n = 66, P = 0.97). In the TN cohort, TLE3 staining was significantly associated with improved 5-year DFI in all patients (n = 81, P < 0.015), in patients treated with AC + T (n = 45, P < 0.02), but not in patients treated with AC (n = 17, P = 0.81). TLE3 was independent of tumor size, nodal status, and grade by bivariable analysis in both cohorts.

Conclusions

TLE3 staining is associated with improved DFI in T-treated patients in two independent cohorts. Since the validation study was performed in a TN cohort, TLE3 is not serving as a surrogate for estrogen receptor or HER2 expression. TLE3 should be studied in large clinical trial cohorts to establish its role in T chemotherapy selection.

Multiple primary tumors in men with breast cancer diagnoses: a SEER database review

BACKGROUND

Male breast cancer (MBC) comprises 1% of all breast cancers and less than 1% of cancer cases in men. After a diagnosis of MBC, men are at risk of developing a second primary cancer, particularly a second primary breast cancer. The objective of this study is to analyze the characteristics of the population of men diagnosed with a second malignancy, specifically a second MBC.

METHODS

Using the Surveillance, Epidemiology, and End Results (SEER) database, 4,873 male patients diagnosed with invasive or in situ breast cancer from 1973 to 2004 were identified and data from patients who developed a second MBC were reviewed. Additional non-breast primary cancer diagnoses were also recorded.

RESULTS

A review of 4,966 records corresponding to 4,873 patients revealed 4,462 invasive and 504 in situ breast cancer events. Of the 4,873 patients, 93 (1.9%) were identified with a second MBC. Among the 4,873 patients with MBC, 1,001 (21%) have other non-breast primary cancer diagnoses recorded in the SEER registry.

CONCLUSIONS

Although MBC is uncommon, these patients are at risk of a contralateral breast cancer and second primary non-breast cancers. Our findings support that men with breast cancer would benefit from continued long-term surveillance for breast cancer and appropriate screening for non-breast cancers.

Integrated approach to assess the domain of applicability of some commercial (Q)SAR models

An integrated framework of data analysis has been proposed to systematically address the determination of the domain of applicability (DA) of some commercial Quantitative Structure Activity Relationship ((Q)SAR) models based on the structure of test chemicals. This framework forms one of the important steps in dealing with the growing concerns on reliability of model-based predictions on toxicity of chemicals specifically in the regulatory context. The present study uses some of the well-known mutagenicity and carcinogenicity models that are available within the Casetox (MultiCASE Inc.) and TOPKAT (Accelrys Software Inc.) programs. The approach enumerated in this paper employs chemoinformatics tools that facilitate comparisons of key structural features as well as application of cluster analysis techniques. The approach has been illustrated using a set of eleven chemical structures selected from the Canadian Domestic Substances List (DSL) that are not present in the model training sets, and the efficacy of the approach has also been assessed using seven chemicals with known toxicities. The methodologies presented here could help address the issue of DA of complex (Q)SAR models and at the same time, serve as useful tools for regulators to make a preliminary assessment of (Q)SAR based systems thereby helping the process of hazard-based regulatory assessments of chemicals.

Influence of structural and functional modifications of selected genotoxic carcinogens on metabolism and mutagenicity - a review

Alterations in molecular structure are responsible for the differential biological response(s) of a chemical inside a biosystem. Structural and functional parameters that govern a chemical's metabolic course and determine its ultimate outcome in terms of mutagenic/carcinogenic potential are extensively reviewed here. A large number of environmentally-significant organic chemicals are addressed under one or more broadly classified groups each representing one or more characteristic structural feature. Numerous examples are cited to illustrate the influence of key structural and functional parameters on the metabolism and DNA adduction properties of different chemicals. It is hoped that, in the event of limited experimental data on a chemical's bioactivity, such knowledge of the likely roles played by key molecular features should provide preliminary information regarding its bioactivation, detoxification and/or mutagenic potential and aid the process of screening and prioritising chemicals for further testing.

In silico techniques for the study and prediction of xenobiotic metabolism: a review

Knowledge about metabolism is very important to understand the health risks posed by chemicals. The biochemical process of metabolism causes activation, inactivation, toxification, detoxification as well as changes in the physicochemical properties of a chemical. The long time consumption and high costs associated with animal tests and the challenges faced by traditional quantitative structure-activity relationship (QSAR) models in dealing with situations wherein parent chemical structures are less relevant to the ultimate effects have led to the development of in silico techniques for the prediction of xenobiotic metabolism. The strengths and limitations of some of the most commonly used in silico expert systems, and their application in studying metabolism of xenobiotic chemicals, have been reviewed. The in silico metabolism simulators possessed several distinguishing features imparted in part by the nature of knowledge rules (algorithms) encoded within them and in part by the integration of QSAR libraries and computational engines.

Triangular approach for the diagnosis of monoclonal gammopathy in malignancies

Monoclonal Gammopathy (MG) in multiple myeloma (MM) is an established association but its occurrence in nonmyelomatous malignancies and other inflammatory conditions is still a subject of research. We carried out this study to detect monoclonal gammopathy in myelomatous and nonmyelomatous malignancies by adopting the triangular approach of correlating radiologic findings, bone marrow studies and electrophoretic findings. 200 cases of malignancies (25 cases of multiple myeloma and 175 cases of nonmyelomatous malignancies) were studied. Serum and urine electrophoresis was carried out in every case and positive cases were subjected for typing by immunoelectrophoresis (IEP). The incidence of monoclonal gammopathy in nonmyelomatous malignancies was 2.29% (4/175 cases), in epithelial malignancies was 0.8% (1/125 cases) and 6% (3/50 cases) in haematological malignancies. Though the study sample was small, these interesting findings warrant more exhaustive research in this field.

Quantitative structure-activity relationships based on functional and structural characteristics of organic compounds

In the present quantitative structure-activity relationship (QSAR) modeling, organic compounds, including priority pollutants, have been considered and classified based on their functional and structural characteristics. Five physico-chemical characteristics have been used to develop a QSAR model for Pimephales promelas, by means of multiple regression analysis. Collinearity diagnostics was carried out using two different approaches based on condition index and K correlation index. The outlier analysis was carried out using the variable subsets obtained through both the approaches. An attempt has been made to justify the deletion of outliers in each group referring to their physico-chemical characteristics. The expressions obtained by using both approaches provide almost the same prediction accuracy, however, the latter approach resulted in expressions with reduced number of molecular descriptors. The QSARs obtained through this exercise would certainly assist in designing environment-friendly molecules with lower toxicity.

Immunocytochemical localization of bioregulatory peptides in marmoset testes

Immunocytochemical localization of neuropeptides (beta-endorphin, substance P, arginine vasopressin, oxytocin), pituitary hormones (adrenocorticotropin, prolactin, growth hormone, follicle stimulating hormone (FSH), gonadal inhibin, gastrin, and human chorionic gonadotrophin (hCG)) was carried out in marmoset testis during development. Both intensity of immunostaining and distribution of these peptides in testicular compartments viz. seminiferous tubules and Leydig cells changed dramatically during development. In vitro biosynthesis of inhibin and FSH was increased by hCG, whereas prolactin (5 micrograms) and prostatic inhibin peptide suppressed the synthesis of these hormones.

Disseminated nocardiosis

A middle aged female suffering from idiopathic thrombocytopenic purpura (ITP), on treatment with steroids, developed bronchopneumonia and pyopneumothorax due to opportunistic infection by Nocardia asteroides. Aspirates obtained from the lungs, liver, spleen, kidneys and bone marrow were positive for Nocardia asteroides, confirming disseminated infection in an immunocompromised host. The patient succumbed to the infection.

FSH in testes of marmosets during development: immunocytochemical localization and de novo biosynthesis

Immunocytochemical localization of FSH was carried out in various cell types of marmoset testes during development using antisera generated against intact as well as beta-subunit of human FSH. Significant differences in the intensity as well as distribution of FSH in various cell types were observed in neonatal, pubertal, and adult marmosets. Intensity of staining in Leydig cells was maximum at day 1 and in adults (1-3 years), whereas it was minimum at 3 months. In seminiferous tubules (Sertoli cells), FSH was present in trace amount until puberty and subsequently increased at maturity. Further studies demonstrate de novo biosynthesis of FSH-like moiety in vitro by testicular tissue, which was age dependent.

Cellular distribution of inhibin in marmoset testes during development

Using polyclonal antibodies against a 13 KD human testicular inhibin, immunocytochemical localization studies were carried out in marmoset monkey testes. The pattern as well as the intensity of immunocytochemical staining for inhibin vary substantially during development. In early development (day 1 to 2 months) Leydig cells are the predominant cell types showing intense staining which reaches its nadir at 3 months. Subsequently both Sertoli cells as well as Leydig cells show equal intensity of inhibin staining. Testicular inhibin is likely to play a vital role in cell to cell communication.

Prostate--an extrapituitary source of follicle-stimulating hormone (FSH): occurrence, localization, and de novo biosynthesis and its hormonal modulation in primates and rodents

A comparative study on the immunocytochemical localization, de novo biosynthesis, and hormonal modulation of follicle-stimulating hormone (FSH) was carried out in the prostates of man, monkey, dog, guinea pig, hamster, rat, and mouse. FSH was localized in the cytoplasm of the prostatic epithelial cells. In some specimens, staining was also observed in the nucleus. Both pituitary as well as prostatic FSH were coeluted on a Sephadex G-100 column and high-performance liquid chromatography (HPLC) indicating physicochemical similarities of FSH in both the tissues. Surprisingly, the modulation of pituitary and prostatic FSH by inhibin and its related peptides were comparable. The intensity and grandularity of FSH staining was stronger in the case of benign prostatic hyperplasia as compared with normal prostatic specimens. In view of the well-known effects of FSH on the cellular growth, differentiation, and function of gonadal tissues, a similar role for FSH in pathophysiology of prostate is postulated.

Primary intramuscular cold abscess in the left deltoid region: a case report

A case of primary intramuscular cold abscess in the left deltoid region is described. There was no underlying bone lesion in relation to cervical or thoracic spine, shoulder joint or upper humerus, and clavicle. It is postulated that the cold abscess might have developed as a result of reactivation of BCG lesion when the patient received a fresh dose of tubercular bacilli which produced only lymph node enlargement in the mediastinum because of the partial immunity the patient had.