Invasive Lobular Breast Cancer Research Articles

Key regulators of lipid metabolism drive endocrine resistance in invasive lobular breast cancer

BackgroundInvasive lobular breast carcinoma (ILC) is a histological subtype of breast cancer that is characterized by loss of E-cadherin and high expression of estrogen receptor alpha (ERα). In many cases, ILC is effectively treated with adjuvant aromatase inhibitors (AIs); however, acquired AI resistance remains a significant problem.MethodsTo identify underlying mechanisms of acquired anti-estrogen resistance in ILC, we recently developed six long-term estrogen-deprived (LTED) variant cell lines from the human ILC cell lines SUM44PE (SUM44; two lines) and MDA-MB-134VI (MM134; four lines). To better understand mechanisms of AI resistance in these models, we performed transcriptional profiling analysis by RNA-sequencing followed by candidate gene expression and functional studies.ResultsMM134 LTED cells expressed ER at a decreased level and lost growth response to estradiol, while SUM44 LTED cells retained partial ER activity. Our transcriptional profiling analysis identified shared activation of lipid metabolism across all six independent models. However, the underlying basis of this signature was distinct between models. Oxysterols were able to promote the proliferation of SUM44 LTED cells but not MM134 LTED cells. In contrast, MM134 LTED cells displayed a high expression of the sterol regulatory element-binding protein 1 (SREBP1), a regulator of fatty acid and cholesterol synthesis, and were hypersensitive to genetic or pharmacological inhibition of SREBPs. Several SREBP1 downstream targets involved in fatty acid synthesis, including FASN, were induced, and MM134 LTED cells were more sensitive to etomoxir, an inhibitor of the rate-limiting enzyme in beta-oxidation, than their respective parental control cells. Finally, in silico expression analysis in clinical specimens from a neo-adjuvant endocrine trial showed a significant association between the increase of SREBP1 expression and lack of clinical response, providing further support for a role of SREBP1 in the acquisition of endocrine resistance in breast cancer.ConclusionsOur characterization of a unique series of AI-resistant ILC models identifies the activation of key regulators of fatty acid and cholesterol metabolism, implicating lipid-metabolic processes driving estrogen-independent growth of ILC cells. Targeting these changes may prove a strategy for prevention and treatment of endocrine resistance for patients with ILC.

Lobular breast cancer: patterns of intraabdominal metastatic spread on imaging and prognostic significance.

To retrospectively review the frequency, patterns and intra-abdominal sites of metastatic invasive lobular breast cancer, and to correlate the findings with overall survival. From a pathology database search revealing 327 patients with metastatic lobular breast cancer at our institution from January 2004 through August 2014, imaging was available in 116 patients (age range, 31-87years, mean age, 55). Simple descriptive statistics were performed to record and tabulate the abdominal metastatic spread. Prognostic significance of abdominal metastases and individual abdominal metastatic sites was studied using the Log-rank test and construction of Kaplan-Meier curves. The most frequent sites of intra-abdominal metastatic invasive lobular breast cancer were peritoneum (55 patients, 47%), followed by liver (37 patients, 32%), bowel (34 patients, 29%), ovary (33 patients, 28%), retroperitoneum (16 patients, 14%), ureter (16 patients, 14%), and lymph nodes (15 patients, 13%). Bowel obstruction was noted in 15 patients (13%) and hydronephrosis in 25 patients (22%). The median abdominal metastasis-free survival was 76months (interquartile range: 17-191). The overall survival (OS) was 86months (interquartile range: 49-188). Patients with abdominal metastases had shorter OS. Patients with hepatic metastases had shorter overall survival than those patients without hepatic metastases (p = 0.02, Log-Rank test). Invasive lobular breast cancer has a predilection for metastasizing to both typical (liver) and atypical intra-abdominal sites (peritoneum, GI tract, and adnexa). Presence of intra-abdominal disease and hepatic metastases in patients with ILC negatively affects overall survival.

αE-catenin is a candidate tumor suppressor for the development of E-cadherin-expressing lobular-type breast cancer.

Although mutational inactivation of E‐cadherin (CDH1) is the main driver of invasive lobular breast cancer (ILC), approximately 10–15% of all ILCs retain membrane‐localized E‐cadherin despite the presence of an apparent non‐cohesive and invasive lobular growth pattern. Given that ILC is dependent on constitutive actomyosin contraction for tumor development and progression, we used a combination of cell systems and in vivo experiments to investigate the consequences of α‐catenin (CTNNA1) loss in the regulation of anchorage independence of non‐invasive breast carcinoma. We found that inactivating somatic CTNNA1 mutations in human breast cancer correlated with lobular and mixed ducto‐lobular phenotypes. Further, inducible loss of α‐catenin in mouse and human E‐cadherin‐expressing breast cancer cells led to atypical localization of E‐cadherin, a rounded cell morphology, and anoikis resistance. Pharmacological inhibition experiments subsequently revealed that, similar to E‐cadherin‐mutant ILC, anoikis resistance induced by α‐catenin loss was dependent on Rho/Rock‐dependent actomyosin contractility. Finally, using a transplantation‐based conditional mouse model, we demonstrate that inducible inactivation of α‐catenin instigates acquisition of lobular features and invasive behavior. We therefore suggest that α‐catenin represents a bona fide tumor suppressor for the development of lobular‐type breast cancer and as such provides an alternative event to E‐cadherin inactivation, adherens junction (AJ) dysfunction, and subsequent constitutive actomyosin contraction. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Corrigendum to "Opening the Door for Immune Oncology Studies in Invasive Lobular Breast Cancer".

Corrigendum to "Opening the Door for Immune Oncology Studies in Invasive Lobular Breast Cancer".

186 (PB-087) - Higher risk of metachronous contralateral breast cancer in patients with invasive lobular breast cancer

186 (PB-087) - Higher risk of metachronous contralateral breast cancer in patients with invasive lobular breast cancer

Discussion of: Neoadjuvant systemic therapy in invasive lobular breast cancer: Is it indicated?

Discussion of: Neoadjuvant systemic therapy in invasive lobular breast cancer: Is it indicated?

Immune Infiltration in Invasive Lobular Breast Cancer.

BackgroundInvasive lobular breast cancer (ILC) is the second most common histological subtype of breast cancer after invasive ductal cancer (IDC). Here, we aimed at evaluating the prevalence, levels, and composition of tumor-infiltrating lymphocytes (TILs) and their association with clinico-pathological and outcome variables in ILC, and to compare them with IDC.MethodsWe considered two patient series with TIL data: a multicentric retrospective series (n = 614) and the BIG 02-98 study (n = 149 ILC and 807 IDC). We compared immune subsets identified by immuno-histochemistry in the ILC (n = 159) and IDC (n = 468) patients from the Nottingham series, as well as the CIBERSORT immune profiling of the ILC (n = 98) and IDC (n = 388) METABRIC and The Cancer Genome Atlas patients. All ILC/IDC comparisons were done in estrogen receptor (ER)–positive/human epidermal growth factor receptor 2 (HER2)–negative tumors. All statistical tests were two-sided.ResultsTIL levels were statistically significantly lower in ILC compared with IDC (fold-change = 0.79, 95% confidence interval = 0.70 to 0.88, P < .001). In ILC, high TIL levels were associated with young age, lymph node involvement, and high proliferative tumors. In the univariate analysis, high TIL levels were associated with worse prognosis in the retrospective and BIG 02-98 lobular series, although they did not reach statistical significance in the latter. The Nottingham series revealed that the levels of intratumoral but not total CD8+ were statistically significantly lower in ILC compared with IDC. Comparison of the CIBERSORT profiles highlighted statistically significant differences in terms of immune composition.ConclusionsThis study shows differences between the immune infiltrates of ER-positive/HER2-negative ILC and IDC in terms of prevalence, levels, localization, composition, and clinical associations.

Opening the Door for Immune Oncology Studies in Invasive Lobular Breast Cancer.

Opening the Door for Immune Oncology Studies in Invasive Lobular Breast Cancer.

Abstract P5-17-01: Lobular breast cancer alliance - Advocates advancing research, screening, treatment and follow-up care for lobular breast disease

Abstract Introduction Thirty patient advocates attended the First International Invasive Lobular Breast Cancer Symposium in 2016 at the University of Pittsburgh Cancer Center. The conference underscored that invasive lobular breast cancer (ILC) and other lobular pathologies are understudied. Specifically: ILC is the sixth most prevalent cancer of women and the second most frequently diagnosed histological subtype of breast cancer impacting up to 34,000 patients a year in the US. ILC is a molecularly distinct breast cancer with unique subtypes and variants with differences in presentation and behavior, including physical findings of thickening and a tendency to metastasize to unique locations. While ILC is frequently associated with a good initial prognosis, recent analysis suggests that long-term outcomes of ILC may be worse than those stage-matched to ductal breast cancer. Current imaging tools are less reliable for early detection of lobular disease and detection of distant recurrence. Standard of care chemotherapy and endocrine therapies may have different effectiveness applied to ILC and IDC. Challenges Growing interest in ILC research requires improved methods to identify, communicate with and link patients with ILC to clinical trials and research. Advocates with advanced science training are needed as partners for research proposals and grant reviews. Lobular breast cancer is under-represented in key meetings and literature. Encouraging opportunities to share ILC research as agenda topics and fostering collaborations between researchers, clinicians and advocates can accelerate progress and refine clinical practices for screening, treatment and follow-up. Patients living with ILC lack a central on-line source of lobular breast cancer information and resources. This information gap is a barrier to help patients recognize signs of lobular breast cancer's unique presentation and metastatic behaviors. Results The Lobular Breast Cancer Alliance (LBCA) was formed by patient advocates who attended the First International ILC Symposium in response to advocate-identified opportunities to advance research, refine treatments and enhance patient education. LBCA's mission is to bridge patients, clinicians and researchers to increase our knowledge of lobular breast disease and promote research that leads to advancements in prevention, diagnosis, treatment and patient follow-up care. Conclusions LBCA is driving an increased awareness of lobular breast cancer with specific goals: Build a clinically accurate, patient centered website devoted to lobular breast cancer at www.LobularBreastCancer.org. Elevate lobular research and foster opportunities for researcher, advocate and clinician collaborations at prominent conferences and meetings. Identify barriers to conduct research on ILC and metastasis and link patients and advocates to ILC tumor research and clinical trials. Initiate peer-to-peer clinician outreach strategy through targeted literature, meetings and education services to share information on ILC presentation, metastatic patterns and screening and treatment challenges of patients with ILC. Build partnerships with existing breast cancer organizations to integrate ILC into existing information resources and work on common goals. Citation Format: Petitti L, Axelrod J, Campbell-Kotler M, Frank E, Jaremek J, Levine J, McWilliams M, Migyanka F, Ryan N, Viggiano E, Metzger-Filho O, Oesterreich S, Pate L. Lobular breast cancer alliance - Advocates advancing research, screening, treatment and follow-up care for lobular breast disease [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-17-01.

Abstract P1-01-07: Clinical and histological characteristics of peritoneal metastases of invasive lobular breast cancer

Abstract Introduction: In previously reported autopsy series, peritoneal metastases have been detected in up to 40% of patients with invasive lobular breast cancer (ILC). Despite modern diagnostic techniques such as high-resolution ultrasound, it remains a challenge to differentiate ovarian cancer from metastatic breast cancer with peritoneal manifestation before or during surgery. The goal of this analysis was to determine typical clinical and immunohistological features of peritoneal metastasis of ILC. Specifically, we asked the question whether there are predictive factors in primary breast cancer associated with subsequent development of peritoneal metastasis. Patients and methods: We identified 58 patients with ovarian metastases in the Charité cancer register (4,792 breast cancer patients from 2003 to 2015). We looked for clinical and pathological differences between breast cancer patients with (N=58) and without (N=4734) peritoneal metastases and between ILC and non-ILC breast cancer subtypes. Imaging and surgical reports of these 58 patients with ILC intraperitoneal metastases were reviewed. Results: The majority (84.7%) of primary breast cancers consisted of subtypes other than ILC and only 15.3% were histologically characterized as ILC. In contrast, 63.6% of patients with peritoneal metastases had histologically proven ILC in the metastatic tissue. Other subtypes where found in the 36.4% of the metastatic tissue (p&amp;lt;0.001). The Odds ratio for peritoneal metastases for ILC was 2.35 (95% CI 1.655-3.332) and for Non-ILC 0.23 (0.185-0.284). There were no significant differences in receptor status between primary and peritoneal metastatic ILC. Comparing ER/PR expressions levels on primary tumor versus metastasis, while statistically not significant (p= 0.805), showed a rise in ER expression in 42.95% in the metastatic tissue while PR expression remained stable with no difference in 53.3% and a rise in the metastatic site in only 26.7% (p= 0.715). Median age of all patients with primary breast cancer was 60 years (10%-90%: 41-75). There was a significant difference in age at diagnosis of metastasis between patients with (50.5 years) and without peritoneal metastases (59 years) (p= 0.002). Median time to development of peritoneal metastases for all patients was 48.5 months (10%-90%: 0-191.7), for ILC 44 months (0-198.2) and for Non-ILC 56.5 months (6.7-206.4) (p= 0.487). Median survival time for patients with ILC and peritoneal metastases was 56 months, for Non-ILC 53 months (p=0.759). 33 of 58 patients had radiologic evidence of disease, 26 with ILC and 7 with Non-ILC. An ovarian mass was detected by imaging in 15/26 patients with ILC and 4/7 patients with non-ILC. Ascites and diffuse peritoneal metastases were seen in 18/26 patients with detectable ILC and in 4/7 patients with Non-ILC. Conclusion: This is the first comprehensive analysis of clinical and pathological characteristics of peritoneal metastases showing ILC is more frequent than other histologic subtypes. Patients with peritoneal metastasis are significantly younger (median 50.5y.) than patients without. The clinical signs are similar to those of ovarian cancer except and therefore the diagnosis of metastatic ILC must be taken into consideration as a differential diagnosis. Citation Format: Karsten MM, Ingold-Heppner B, Oesterreich S, Sander S, Machleidt A, von Waldenfels G, Denkert C, Blohmer JU. Clinical and histological characteristics of peritoneal metastases of invasive lobular breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-01-07.

Accuracy of Predictions of Patients With Breast Cancer of Future Well-being After Immediate Breast Reconstruction

Making a good decision about breast reconstruction requires predicting how one would feel after the procedure, but people tend to overestimate the impact of events on future well-being. To assess how well patients predict future well-being after mastectomy, with or without immediate reconstruction, with the following a priori hypotheses: Patients will overestimate the negative impact of mastectomy and positive impact of reconstruction, and prediction accuracy will be associated with decision satisfaction and decision regret. This prospective cohort survey study was conducted at a single, multidisciplinary academic oncology clinic from July 2012 to February 2014. Adult women undergoing mastectomy for stage 1, 2, or 3 invasive ductal or lobular breast cancer, ductal carcinoma in situ, or prophylaxis were invited to participate. Data analysis was conducted from September 2015 to October 2017. Mastectomy only or mastectomy with immediate reconstruction. Preoperative measures predicted were 12-month happiness (Cantril Ladder) and quality of life, predicted satisfaction with breasts, sexual attractiveness, breast numbness, and pain (measured with BreastQ single items). Measures at 12 months postoperative added the Decision Regret Scale and Satisfaction With Decisions Scale. Of 214 eligible patients, 182 consecutive patients were approached, and 145 enrolled (80%). Of these 145 patients, 131 returned surveys (72%) and 111 of these remained at 12 months (88%). Fifteen who had delayed reconstruction were excluded from analysis, leaving a final cohort of 96 women; 54 had not had reconstruction and 42 had had reconstruction. The mean (SD) age of the cohort was 53.9 (12.1) years; 73 (76%) were white; 50 (52%) were college graduates; 54 (56%) were privately insured; 69 (72%) had disease at stages 0, 1, or 2; and 31 (32%) received adjuvant radiation. Patients having mastectomy without reconstruction underestimated future well-being in all domains. Differences were significant for quality of life scores (mean predicted, 68 vs mean actual, 74; t50, -2.47; P = .02) and satisfaction with breasts-clothed (mean predicted, 2.4 vs mean actual, 2.8; t49, -2.11; P = .04). Patients undergoing mastectomy with reconstruction overestimated future well-being in all but 1 domain. Differences were significant for satisfaction with breasts-unclothed (mean predicted, 3.1 vs mean actual, 2.6; t41, 2.70; P = .01); sexual attractiveness-clothed (mean predicted, 3.7 vs mean actual, 3.3; t39, 2.29; P = .03); sexual attractiveness-unclothed (mean predicted, 3.3 vs mean actual, 2.3; t40, 5.57; P < .001). Both groups experienced more numbness than predicted (mean predicted, 2.79 and 2.72 for mastectomy only and mastectomy with reconstruction groups, respectively; mean actual, 3.52 and 3.56, respectively; t47, -3.4 and t38, -2.9, respectively; P < .01). Patients who were less happy (β = 6.3; P = .02) or had greater pain (β = 8.7; P < .001) than predicted had greater regret. Patients underestimated future well-being after mastectomy and overestimated well-being after reconstruction. Misprediction was associated with regret. Decision support for breast reconstruction should address expectations about well-being.

Pre-operative and intra-operative detection of axillary lymph node metastases in 108 patients with invasive lobular breast cancer undergoing mastectomy

BackgroundDespite the recent changes in the treatment of the axilla in selected breast cancer patient, positive sentinel lymph node (SLN) in patients undergoing mastectomy still necessitates axillary lymph node dissection (ALND). In invasive lobular carcinoma (ILC), pre-operative detection of the lymph node metastasis may be demanding due to its unique morphology. The aim of this study was to examine the benefit of preoperative axillary ultrasound (AUS), ultrasound-guided fine-needle aspiration biopsy (US-FNAB), and intra-operative imprint cytology (IIC), in order to avoid two-stage axillary surgery in patients with ILC undergoing mastectomy.MethodsThe object of this study were 102 patients (median age 52, range 34–73 years) with clinically non-suspicious axilla in whom 108 mastectomies were performed after a pre-operative AUS investigation. Whenever a metastasis was detected in a sentinel lymph node, ALND was done. Reports of the pre-operative AUS investigation, US-FNAB, and IIC were compared with definitive histopathological reports of surgical specimens.ResultsIn 46 cases lymph node metastases were diagnosed. AUS suspicious lymph nodes were found in 29/108 cases and histopathology confirmed metastases in 22/30 cases. US-FNAB was performed in 29 cases with AUS suspicious lymph nodes. Cytology proved metastases in 11/29 cases. Histopathology confirmed metastases in 10/11 cases with only isolated tumor cells found in one case. IIC investigation was performed in 63 cases and in 10/27 cases metastases were confirmed by histopathology. Pre-operative AUS, US-FNAB, and/or IIC investigation enabled ALND during a single surgical procedure in 20/46 patients with metastases in lymph nodes.ConclusionPre-operative AUS, US-FNAB, and/or IIC are/is beneficial in patients with ILC planned for mastectomy in order to decrease the number of two stage axillary procedures.

An analysis of 68 invasive lobular breast cancer cases in clinicopathological characteristics and the prognostic determinants

Objective: To study the clinicopathological characteristics and the prognostic determinants of the invasive lobular carcinoma breast cancer. Methods: This was a retrospective single-center study of invasive lobular breast cancer cases diagnosed from January 2008 to December 2014 at Peking University First Hospital Breast Disease Center. The study enrolled 68 invasive lobular breast cancer patients, which represented 3.64% (68/1 870) of total invasive breast cancer. The median age of all selected patients was 46 years ranging from 36 to 83 years. All patients were restaged based on the 8(th) edition of AJCC cancer staging system and follow-up data including disease-free survival (DFS) and overall survival (OS) were analyzed to explore the prognostic determinants. The 5-year OS and DFS were calculated using Kaplan-Meier method; the significance of correlations between clinicopathological features and prognostic factors was estimated using log-rank test. Results: There were significant differences in OS between patients with different anatomic stage, prognostic stage, lymph node metastasis, progesterone receptor (PR) expression, lymphvascular invasion and perineural invasion (χ(2:) 4.318 to 32.394, all P<0.05); significant differences in DFS were also observed between patients with different anatomic stage, prognostic stage, lymph node metastasis, PR expression, human epidermal growth factor receptor-2 expression, Ki-67 level, histological grade and lymphvascular invasion (χ(2:) 4.347 to 27.369, all P<0.05). Prognostic stages of 52.9% patients changed compared with anatomic stage, among which Luminal subtype mainly downstaged (22/30), however, triple negative subtype mainly upstaged (6/6). Conclusions: Anatomic stage, prognostic stage, lymph node metastasis, PR expression, lymphvascular invasion are the prognostic factors of invasive lobular breast cancer. Regard to invasive lobular breast cancer patients, clinicians should pay close attention to the differences between prognostic stage and anatomic stage.

Variants in members of the cadherin-catenin complex, CDH1 and CTNND1, cause blepharocheilodontic syndrome.

Blepharocheilodontic syndrome (BCDS) consists of lagophthalmia, ectropion of the lower eyelids, distichiasis, euryblepharon, cleft lip/palate and dental anomalies and has autosomal dominant inheritance with variable expression. We identified heterozygous variants in two genes of the cadherin-catenin complex, CDH1, encoding E-cadherin, and CTNND1, encoding p120 catenin delta1 in 15 of 17 BCDS index patients, as was recently described in a different publication. CDH1 plays an essential role in epithelial cell adherence; CTNND1 binds to CDH1 and controls the stability of the complex. Functional experiments in zebrafish and human cells showed that the CDH1 variants impair the cell adhesion function of the cadherin-catenin complex in a dominant-negative manner. Variants in CDH1 have been linked to familial hereditary diffuse gastric cancer and invasive lobular breast cancer; however, no cases of gastric or breast cancer have been reported in our BCDS cases. Functional experiments reported here indicated the BCDS variants comprise a distinct class of CDH1 variants. Altogether, we identified the genetic cause of BCDS enabling DNA diagnostics and counseling, in addition we describe a novel class of dominant negative CDH1 variants.

Abstract B158: Exploiting IGF1R pathway activation as a therapeutic strategy for E-cadherin deficient breast cancers

Abstract Insulin-like growth factor I (IGF1) plays an important role in breast cancer initiation and progression due to its regulation of cell proliferation, migration, and invasion. These characteristics make IGF1R an attractive therapeutic target; however, only a subset of patients show beneficial response to IGF1R inhibitors in clinical trials. To identify putative biomarkers of response to IGF1, we performed a proteomic screen in 21 breast cancer cell lines stimulated with IGF1. Using a novel integrated computational and experimental approach, we identified levels of E-cadherin (CDH1), a major component of the adherens junction (AJ), as a repressor of IGF1R signaling. CDH1 is genetically lost in invasive lobular breast cancer (ILC), a subtype of breast cancer that accounts for ~10-15% of total cases. E-cadherin is also downregulated in estrogen receptor (ER)-negative breast cancers that have undergone epithelial to mesenchymal transition. Consistent with the proteomic screen, knockdown of E-cadherin enhanced IGF1-induced activation of IGF1R and downstream Akt and ERK1/2 phosphorylation, and this enhanced cell cycle progression. Disruption of the AJ alone with an E-cadherin monoclonal antibody also enhanced IGF1R signaling. Further, we have shown a direct interaction of IGF1R and E-cadherin using in situ proximity ligation assay indicating a physical regulation of E-cadherin on IGF1R signaling. Supporting the clinical relevance of our observations, we found increased expression of IGF1 ligand and increased IGF1R phosphorylation in E-cadherin deficient ER+ ILC tumors in The Cancer Genome Atlas (TCGA) compared to ER+ invasive ductal carcinomas (IDC). We also discovered a correlation between mRNA expression and the activation of the IGF gene signature in (1) a cohort of ER+ ILC tumors compared to ER+ IDC and (2) a subset of ER-negative tumors within TCGA. We have previously published that IGF1R inhibitors are effective in inhibiting growth of ER-negative breast cancer cell lines and xenograft models in combination with chemotherapy. Thus, we focused our studies on understanding the utility of IGF1R pathway inhibition in ER+ ILC as a therapeutic strategy. Our data indicate that IGF1R and Akt pathway inhibitors are effective in inhibiting growth in ER+ ILC cell lines and ex vivo tumor culture, and synergize with standard-of-care anti-ER targeted therapy. Therefore, we hypothesize that loss of E-cadherin potentiates IGF1R signaling to enhance breast cancer progression and that loss of E-cadherin expression in ILC and ER-negative tumors may highlight those susceptible to IGF1R inhibition. Citation Format: Alison M. Nagle, Cemal Erdem, Kevin Levine, Christos Sotiriou, Otto Metzger, D Lans Taylor, Timothy Lezon, Steffi Oesterreich, Adrian V. Lee. Exploiting IGF1R pathway activation as a therapeutic strategy for E-cadherin deficient breast cancers [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B158.

Lobular carcinoma in situ and invasive lobular breast cancer are characterized by enhanced expression of transcription factor AP-2β

Transcription factor AP-2β (TFAP2B) regulates embryonic organ development and is overexpressed in alveolar rhabdomyosarcoma, a rare childhood malignancy. Gene expression profiling has implicated AP-2β in breast cancer (BC). This study characterizes AP-2β expression in the mammary gland and in BC. AP-2β protein expression was assessed in the normal mammary gland epithelium, in various reactive, metaplastic and pre-invasive neoplastic lesions and in two clinical BC cohorts comprising >2000 patients. BCs from various genetically engineered mouse (GEM) models were also evaluated. Human BC cell lines served as functional models to study siRNA-mediated inhibition of AP-2β. The normal mammary gland epithelium showed scattered AP-2β-positive cells in the luminal cell layer. Various reactive and pre-invasive neoplastic lesions, including apocrine metaplasia, usual ductal hyperplasia and lobular carcinoma in situ (LCIS) showed enhanced AP-2β expression. Cases of ductal carcinoma in situ (DCIS) were more often AP-2β-negative (P<0.001). In invasive BC cohorts, AP-2β-positivity was associated with the lobular BC subtype (P<0.001), loss of E-cadherin (P<0.001), a positive estrogen receptor (ER) status (P<0.001), low Ki67 (P<0.001), low/intermediate Oncotype DX recurrence scores (P<0.001), and prolonged event-free survival (P=0.003). BCs from GEM models were all AP-2β-negative. In human BC cell lines, AP-2β expression was independent from ER-signaling. SiRNA-mediated inhibition of AP-2β diminished proliferation of lobular BC cell lines in vitro. In summary, AP-2β is a new mammary epithelial differentiation marker. Its expression is preferentially retained and enhanced in LCIS and invasive lobular BC and has prognostic implications. Our findings indicate that AP-2β controls tumor cell proliferation in this slow-growing BC subtype.

Outcomes in women with invasive ductal or invasive lobular early stage breast cancer treated with anastrozole or exemestane in CCTG (NCIC CTG) MA.27

BackgroundHistological subtype, (invasive ductal breast cancer (IDBC)/invasive lobular breast cancer (ILBC)), might be a marker for differential response to endocrine therapy in breast cancer. MethodsClinical trial MA.27 compared 5 years of adjuvant anastrozole or exemestane in postmenopausal patients with hormone receptor positive early breast cancer. We evaluated IDBC versus ILBC (based on original pathology reports) as predictor for event-free survival (EFS) and overall survival (OS). ResultsA total of 5709 patients (5021 with IDBC and 688 with ILBC) were included (1876 were excluded because of missing or other histological subtype). Median follow-up was 4.1 years. Overall, histological subtype did not influence OS or EFS (HR (hazard ratio) 1.14, 95% confidence interval (CI) [0.79–1.63], P = 0.49 and HR 1.04, 95% CI [0.77–1.41], P = 0.81, respectively). There was no significant difference in OS between treatment with exemestane versus treatment with anastrozole in the IDBC group (HR = 0.92, 95% CI [0.73–1.16], P = 0.46). In the ILBC group, a marginally significant difference in favour of treatment with anastrozole was seen (HR = 1.79, 95% CI [0.98–3.27], P = 0.055). In multivariable analysis a prognostic effect of the interaction between treatment and histological subtype on OS (but not on EFS) was noted, suggesting a better outcome for patients with ILBC on anastrozole (HR 2.1, 95% CI [0.99–4.29], P = 0.05). After stepwise selection in the multivariable model, a marginally significant prognostic effect for the interaction variable (treatment with histological subtype) on OS (but not on EFS) was noted (Ratio of HR 2.1, 95% CI [1.00–4.31], P = 0.05). ConclusionOur data suggest an interaction effect between treatment and histology (P = 0.05) on OS. Here, patients with ILBC cancers had a better OS when treated with anastrozole versus exemestane, whereas no difference was noted for patients with IDBC. Clinical Trial informationNCT00066573.

In Vivo Detection of HSP90 Identifies Breast Cancers with Aggressive Behavior.

Purpose: Hsp90, a chaperone to numerous molecular pathways in malignant cells, is elevated in aggressive breast cancers. We hypothesized that identifying breast cells with elevated Hsp90 activity in situ could result in early detection of aggressive breast cancers.Experimental Design: We exploited the uptake of an Hsp90 inhibitor by malignant cells to create an imaging probe (HS131) of Hsp90 activity by linking it to a near-infrared (nIR) dye. HS131 uptake into cells correlated with cell membrane expression of Hsp90 and was used to image molecular subtypes of murine and human breast cancers in vitro and in murine models.Results: HS131 imaging was both sensitive and specific in detecting the murine 4T1 breast cancer cell line, as well as subclones with differing metastatic potential. Highly metastatic subclones (4T07) had high HS131 uptake, but subclones with lower metastatic potential (67NR, 168FARN) had low HS131 uptake. We generated isogenic cell lines to demonstrate that overexpression of a variety of specific oncogenes resulted in high HS131 uptake and retention. Finally, we demonstrated that HS131 could be used to detect spontaneous tumors in MMTV-neu mice, as well as primary and metastatic human breast cancer xenografts. HS131 could image invasive lobular breast cancer, a histologic subtype of breast cancer which is often undetectable by mammography.Conclusions: An HSP90-targeting nIR probe is sensitive and specific in imaging all molecular subtypes of murine and human breast cancer, with higher uptake in aggressive and highly metastatic clones. Clinical studies with Hsp90-targeting nIR probes will be initiated shortly. Clin Cancer Res; 23(24); 7531-42. ©2017 AACR.

Neoadjuvant systemic therapy in invasive lobular breast cancer: Is it indicated?

BackgroundThis study investigated patients with invasive lobular breast carcinoma (ILC) to determine the benefit of neoadjuvant systemic therapy (NAST). MethodsPatients with ILC treated from 2006 to 2015 were identified. Tumor characteristics and treatment data were analyzed. ResultsOf the 560 patients with ILC, 77 patients received NAST. Patients who received NAST presented with larger clinical T stages compared to patients who received surgery first (p < 0.001). Pathological complete response (pCR) to NAST was seen in 17% of patients. Only 14% of patients with clinically positive lymph nodes downstaged to N0. These patients were more likely to have HER2 positive tumors (p < 0.029) and larger tumor size at diagnosis (p < 0.015). Mastectomy was performed in 84% of patients and lumpectomy in 16%. ConclusionsOnly a minority of patients with ILC achieve pCR. The majority of patients still undergo mastectomy; therefore the benefit of NAST in ILC appears limited.

Estrogen induces c-Kit and an aggressive phenotype in a model of invasive lobular breast cancer

Among the molecular subtypes of breast cancer are luminal (A or B) estrogen receptor positive (ER+), HER2+, and triple negative (basal-like). In addition to the molecular subtypes, there are 18 histologic breast cancer subtypes classified on appearance, including invasive lobular breast carcinoma (ILC), which are 8–15% of all breast cancers and are largely ER+ tumors. We used a new model of ER+ ILC, called BCK4. To determine the estrogen regulated genes in our ILC model, we examined BCK4 xenograft tumors from mice supplemented with or without estrogen using gene expression arrays. Approximately 3000 genes were regulated by estrogen in vivo. Hierarchical cluster analyses of the BCK4 derived tumors compared with ER+ and ER- breast cancer cell lines show the estrogen treated BCK4 tumors group with ER- breast cancers most likely due to a high proliferation score, while tumors from cellulose supplemented mice were more related to ER+ breast tumor cells. To elucidate genes regulated in vitro by estrogen in BCK4 cells, we performed expression profiling using Illumina arrays of the BCK4 cell line, treated with or without estrogen in vitro. A set of ~200 overlapping genes were regulated by estrogen in the BCK4 cell line and xenograft tumors, and pathway analysis revealed that the c-Kit pathway might be a target to reduce estrogen-induced proliferation. Subsequent studies found that inhibition of c-Kit activity using imatinib mesylate (Gleevec®) blocked estrogen mediated stimulation of BCK4 tumors and BCK4 cells in vitro as effectively as the anti-estrogen fulvestrant (Faslodex®). Decreased expression of c-Kit using shRNA also decreased baseline and estrogen induced proliferation in vitro and in vivo. These studies are the first to indicate that c-Kit inhibition is an effective approach to target c-Kit+ ILC.