Basal-like Group Research Articles

Interleukin-3 production by basal-like breast cancer cells is associated with poor prognosis

ABSTRACT: Breast cancer represents a collection of pathologies with different molecular subtypes, histopathology, risk factors, clinical behavior, and responses to treatment. “Basal-like” breast cancers predominantly lack the receptors for estrogen and progesterone (ER/PR), lack amplification of human epidermal growth factor receptor 2 (HER2) but account for 10–15% of all breast cancers, are largely insensitive to targeted treatment and represent a disproportionate number of metastatic cases and deaths. Analysis of interleukin (IL)-3 and the IL-3 receptor subunits (IL-3RA + CSF2RB) reveals elevated expression in predominantly the basal-like group. Further analysis suggests that IL-3 itself, but not the IL-3 receptor subunits, associates with poor patient outcome. Histology on patient-derived xenografts supports the notion that breast cancer cells are a significant source of IL-3 that may promote disease progression. Taken together, these observations suggest that IL-3 may be a useful marker in solid tumors, particularly triple negative breast cancer, and warrants further investigation into its contribution to disease pathogenesis.

Multicentricity in Different Molecular Subtypes of Breast Cancer: A Cross-sectional Study in Isfahan.

Breast cancer is the most common cancer leading to death in women. Women with multicentric breast cancer were reported more likely to have poor prognosis. Here, we decided to study and compare the frequency distribution of multicentricity in different subtypes of breast cancer. This is a cross-sectional study that was performed in 2019-20 on medical records and breast pathology reports of 250 patients who undergone mastectomy due to breast cancer. Demographic data of all patients including age, along with other medical data such as menstruation condition, breast cancer grade, multicentricity status, stage, and expression of estrogen receptor (ER), progesterone (PR), and human epidermal growth factor receptor 2 (HER2) receptors were collected from medical records. Samples were divided into four subtypes of Luminal B, Luminal A, HER2 expressing, and basal-like. The mean age of patients was 50.21 ± 11.15 years. Ninety-five patients (38%) had multicentricity and HER2 expressing (48.5%) and Luminal A (41.4%) were most common in patients with multicentricity. In addition, basal-like group presented with least multicentricity (13.5%) among the subtypes (P = 0.008). We also showed significant increased chances of multicentricity in Luminal B (odds ratio [OR] = 3.782) (P = 0.033), Luminal A (OR = 5.164) (P = 0.002), and HER2-expressing group (OR = 5.393) (P = 0.011). Taken together, we showed significantly increased chances of multicentricity in patients with HER2-expression, Luminal A, and Luminal B groups compared to basal-like group or triple negative. These results were in line with most previous studies; however, we showed higher rates of multicentricity among our population compared to some previous reports.

Investigation of the differences of breast cancer molecular subtypes in radiological and histopathological parameters and their effects on lymphovascular invasion

Introduction: Breast cancer has heterogeneous tumor biology. Therefore, breast cancer is divided into molecular subtypes. However, molecular subtypes also show heterogeneity within themselves. In our study, we compared whether there were radiological and pathological differences between breast cancer molecular subtypes. Methods: The data of 569 patients operated on for breast cancer in our General Surgery clinic during an 8-year period were analyzed retrospectively. After dividing the patients into groups consisting of molecular subtypes, their radiological and pathological findings were compared. Results: According to the molecular classification of breast cancer, 47.6% of the patients were in the luminal A group, 23.9% in luminal B, 7.7% in HER2-enriched, and 12% in TN, and 8.8% in normal-like groups. DCIS and LCIS were significantly less common in the TN group than in the others (p=0.015). Tumor diameter and grade were considerably higher in the normal-like, HER2-enriched, and TN groups than in the other groups (p<0.001, p<0.001). LVI was significantly lower in luminal A and significantly higher in luminal B (p<0.001). Mortality was significantly higher in the luminal B and TN groups than in the other groups (p = 0.029). Conclusion: The addition of the basal-like group when classifying breast cancer into molecular subtypes showed histopathological differences. More studies are needed to investigate its effects on treatment and prognosis. Keywords: Breast cancer, Molecular subtype, Genotype, Immunohistochemistry, Survival

Application of Fluorescence Dye in Combination with Methylene Blue for Axillary Reverse Mapping in Patients with Modified Radical Mastectomy for Breast Cancer.

Background Axillary reverse mapping (ARM) is a novel intraoperative technique developed in recent years. This study was aimed at determining the effect of combined use of fluorescence dye and methylene blue, as well as its feasibility of ARM in patients with breast cancers who undergo modified radical mastectomy. Method From January 2016 to June 2017, 46 patients with primary breast cancer at stage I-IV (Tis-T3, N0-N3, and M0) who received modified radical mastectomy were enrolled in this study. The exclusion criteria included preoperative radiotherapy/chemotherapy or bilateral disease. Patients were divided into 2 groups: methylene blue group (22 patients, 47.8%) and methylene blue+indocyanine green (ICG) group (24 patients, 52.2%). ARM was performed before surgery. Results The overall visualization rate of ARM nodes was 80.4% (37/46). The visualization rate was significantly increased in methylene blue+ICG group (91.67%, 22/24) than that in methylene blue group (63.64%, 14/22) (P = 0.032). There was a statistical difference of visualization rate between clinical groups of N0-N1 and N3-N4 (t = 2.431, P = 0.19 < 0.05). Although there was no significant difference found in the total drainage volume and arm perimeter of patients between the two groups (P > 0.05), the harden diameter of the injection site in methylene blue+ICG group was significantly longer than that in methylene blue group (P < 0.05). Among the 44 patients with different molecular profiling of breast cancer, there was no significant difference of visualization rate of ARM nodes in luminal A group (100%,5/5), luminal B group (75.0%, 18/24, P = 0.21), HER2 group (75.0%, 6/8, P = 0.22), and basal-like group (85.7%, 6/7, P = 0.37). Conclusions ARM using methylene blue+ICG presented greater identification rate than that with methylene blue alone, especially in patients with more invasive breast cancer. Our finding offers support for the improvement of ARM in future breast cancer management.

Investigation of genes and pathways involved in breast cancer subtypes through gene expression meta-analysis

BackgroundMolecular-based studies have revealed heterogeneity in Breast cancer BC while also improving classification and treatment. However, efforts are underway to distinguish between distinct subtypes of breast cancer. In this study, the results of several microarray studies were combined to identify genes and pathways specific to each BC subtype. MethodsMeta-analysis of multiple gene expression profile datasets was screened to find differentially expressed genes (DEGs) across subtypes of BC and normal breast tissue samples. Protein-protein interaction network and gene set enrichment analysis were used to identify critical genes and pathways associated with BC subtypes. The differentially expressed genes from meta-analysis was validated using an independent comprehensive breast cancer RNA-sequencing dataset obtained from the Cancer Genome Atlas (TCGA). ResultsWe identified 110 DEGs (13 DEGs in all and 97 DEGs in each subtype) across subtypes of BC. All subtypes had a small set of shared DEGs enriched in the Chemokine receptor bind chemokine pathway. Luminal A specific were enriched in the translational elongation process in mitochondria, and the enhanced process in luminal B subtypes was interferon-alpha/beta signaling. Cell cycle and mitotic DEGs were enriched in the basal-like group. All subtype-specific DEG genes (100%) were successfully validated for Luminal A, Luminal B, ERBB2, and Normal-like. However, the validation percentage for Basal-like group was 77.8%. ConclusionIntegrating researches such as a meta-analysis of gene expression might be more effective in uncovering subtype-specific DEGs and pathways than a single-study analysis. It would be more beneficial to increase the number of studies that use matched BC subtypes along with GEO profiling approaches to reach a better result regarding DEGs and reduce probable biases. However, achieving 77.8% overlap in basal-specific genes and complete concordance in specific genes related to other subtypes can implicate the strength of our analysis for discovering the subtype-specific genes.

Bioinformatics analysis revealing prognostic significance of TIMP2 gene in breast cancer.

Tissue inhibitor of metalloproteinases 2 (TIMP2) is a member of the TIMP gene family. Accumulated evidence indicates that TIMP2 plays a significant role in various tumor processes including cell growth, apoptosis, invasion, and metastasis. However, the expression patterns and exact roles of TIMP2 had not been elucidated in breast cancer. In our research, we evaluated the expression and prognostic value of TIMP2 in breast cancer through analyzing various databases including Oncomine, bc-GenExMiner, PrognoScan, UCSC Xena, Kaplan–Meier Plotter, and PPI network. The results showed that TIMP2 was down-regulated in various breast cancer subtypes. Additionally, TIMP2 was significantly associated with age, estrogen receptor status, basal-like group, triple-negative breast cancer, PAM50 subtypes, and RSSPC subtypes. Also, the expression of TIMP2 was related to overall survival with different clinical characteristics. We analyzed the co-expressed genes with TIMP2 and interaction information with other proteins. These results disclosed that TIMP2 might serve as a potential target and prognostic biomarker in breast cancer. However, additional research is required to demonstrate our findings and motivate the clinical importance of TIMP2 in breast cancer.

Abstract 2489: Characterization of breast cancer ctDNA with Omi-Seq

Abstract Cancer patients' cell free DNA (cfDNA) contains circulating tumor-derived DNA (ctDNA). The fast dynamic of clearance allows ctDNA to be used as biomarkers for tumor real time profiling. The benefit of non-invasive, cost effective, and easily-repetitive sampling makes liquid biopsy a highly-desirable option for molecular assessment. Deep sequencing has been widely used to investigate subpopulations in complex biological samples. However, there are still limitations of the sequencing technology due to the low yield of cfDNA amount, and errors introduced during sample preparation and sequencing. Approximately 1% of bases are incorrectly identified, depending on the specific platform and sequence context. Although Molecular Identifier can theoretically greatly reduce errors, it suffers from several drawbacks. First, it is difficult to synthesize double strand adapters with randomized Molecular Identifier. Second, due to the difficulty in making high quality Single Molecular Identifier (SMI) adaptors, the ligation efficiency might be compromised and therefore might require large amounts of input DNA. To optimize the liquid biopsy protocol, we first examined if there is any bias in the molecular barcodes' selection during library preparation. Indeed, a skewed trend with molecular barcode selection in ligation process has been detected. We also evaluated the error rates in molecular barcodes and found that there is a substantial amount of errors (~5% of total reads carrying the wrong molecular barcode). To overcome these issues, Omi-seq calculates Digital Molecular Identifier (DMI) using a pool of regular adapters with defined barcodes which can be easily synthesized in high quality. We then analyzed Horizon multiplex I cfDNA reference standard with the lowest available allele frequency (AF) 0.1%. With Omi-error correction, Omi-Seq was able to reproducibly detect the variants. We also evaluated Omi-Seq in real patient samples, Omi-Seq is able to detect variants at AF 0.03%. Omi-Seq was utilized to created cancer profiles for 202 subjects enrolled in The First Affiliated Hospital of Wenzhou Medical University breast cancer study. The gene landscape indicated that the most frequently detected genes are PIK3CA and TP53, followed by ERBB2. The accuracy of Her2 CNV in tissue/FFPE sample is 96% with 85 % sensitivity and 100% specificity. Mutation numbers vary between different molecular subtypes of cfDNA, where the basal-like group had more variants detected than Luminal patients. Furthermore, the ratio changes of max ctDNA AF (ctF) are highly correlated to the clinical response measurement, including cancer relapse, metastatic and treatment resistance. Our data show that ctDNA characterization with Omi-seq could extend the capacity of personalized cancer clinical management. Citation Format: Yinghao Wang, Yaoyao Guan, Jingjing Xiang, Lingguo Kong, Lizhi Lin, Judy Webb, Yunguang Tong, Ouchen Wang. Characterization of breast cancer ctDNA with Omi-Seq [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2489.

Integrative molecular profiling and response to chemotherapy on the COMPASS trial.

188 Background: Predictive mutational and transcriptional features in advanced PDAC are needed for improved patient stratification and treatment selection. Methods: Patients (pts) on the COMPASS trial with advanced PDAC are prospectively recruited prior to first-line chemotherapy for WGS and RNAseq. Tumor tissue undergoes enrichment by laser capture microdissection with genomic analyses available within eight wks. Tumor responses and clinical outcomes in this maturing cohort were correlated with molecular characteristics. Results: 157 pts underwent a tumor biopsy between Dec 2015 and Jul 2018 with over 95% success in achieving results. 141 genomes have been reported in pts planned to receive chemotherapy; the median time from biopsy to report was 35.5 days. In the ITT population,118 pts are summarised for first-line response. The median age was 63 yrs (29-81), 55% were male, and 16% had locally advanced disease. 66 (56%) received modified FFX as first-line treatment. 25 (21%) tumors displayed the Moffitt basal-like RNA signature which associated with chemotherapy resistance, with tumor shrinkage mainly observed in the classical RNA subtype (p = 0.002). GATA6 expression (log10 scale) clearly separated Moffitt subgroups with classical tumors exhibiting high expression (p &lt; 0.0001). GATA6 in situ hybridization strongly correlated with RNAseq, (r = 0.89, p &lt; 0.001) with strong correlation also seen with GATA6 IHC. The median overall survival (OS) in the classical group was 8.5 mths vs. 6.6 mths in the basal-like group (HR 0.53, 95% CI 0.32-0.89 p = 0.015). In those treated with mFFX, median OS was 10.1mths in classical versus 6.6mths in the basal-like subtypes, (HR 0.32, 95% CI 0.16-0.63, p=0.001). 30% of pts had potentially actionable genetic alterations including BRAF variants (n = 4) and an NTRK3-EML4 fusion in KRAS WT tumors (8%). Signatures of homologous recombination deficiency (HRD) were found in seven pts; two additional pts with BRCA germline variants did not exhibit somatic HRD hallmarks. Conclusions: Subsets of pts with advanced PDAC have actionable variants including those with HRD signatures and patients with KRAS WT tumors. GATA6 is a putative predictive biomarker of transcriptomic subgroups which should be incorporated in clinical trials. Clinical trial information: NCT02750657.

Discordance of the PAM50 Intrinsic Subtypes Compared with Immunohistochemistry-Based Surrogate in Breast Cancer Patients: Potential Implication of Genomic Alterations of Discordance.

PurposeWe aimed to analyze the discordance between immunohistochemistry (IHC)-based surrogate subtyping and PAM50 intrinsic subtypes and to assess overall survival (OS) according to discordance.Materials and MethodsA total of 607 patients were analyzed. Hormone receptor (HR) expression was evaluated by IHC, and human epidermal growth factor receptor 2 (HER2) expression was analyzed by IHC and/or fluorescence in situ hybridization. PAM50 intrinsic subtypes were determined according to 50 cancer genes using the NanoString nCounter Analysis System. We matched concordant tumor as luminal A and HR+/HER2–, luminal B and HR+/HER2+, HR–/HER2+ and HER2–enriched, and triple-negative breast cancer (TNBC) and normal- or basal-like. We used Ion Ampliseq Cancer Panel v2 was used to identify the genomic alteration related with discordance. The Kaplan-Meier method was used to estimate OS.ResultsIn total, 233 patients (38.4%) were discordant between IHC-based subtype and PAM50 intrinsic subtype. Using targeted sequencing, we detected somatic mutation–related discordant breast cancer including the VHL gene in the HR+/HER2– group (31% in concordant group, 0% in discordant group, p=0.03) and the IDH and RET genes (7% vs. 12%, p=0.02 and 0% vs. 25%, p=0.02, respectively) in the TNBC group. Among the luminal A/B patients with a discordant result had significantly worse OS (median OS, 73.6 months vs. not reached; p < 0.001), and among the patients with HR positivity, the basal-like group as determined by PAM50 showed significantly inferior OS compared to other intrinsic subtypes (5-year OS rate, 92.2% vs. 75.6%; p=0.01).ConclusionA substantial portion of patients showed discrepancy between IHC subtype and PAM50 intrinsic subtype in our study. The survival analysis demonstrated that current IHC-based classification could mislead the treatment and result in poor outcome. Current guidelines for IHC might be updated accordingly.

Contemporary classification of breast cancer

Studies of breast cancers using gene expression profiling have identified several major subtypes. The best characterised are luminal A, luminal B, HER2-enriched and basal-like, which differ in their gene expression patterns, clinical features, response to treatment and outcome. One of the most novel findings has been the characterisation of basal-like breast cancers, which are often high-grade invasive ductal carcinomas with solid architecture, high mitotic rate, stromal lymphocytic infiltrate, pushing border, geographic necrosis and/or a central fibrotic focus. They are typically ER-, PR-, and HER2-negative and have a poor prognosis. Interestingly, some tumours with a favourable prognosis also cluster in the basal-like group (adenoid cystic and secretory carcinomas). Approximately 70–80% of basal-like tumours are clinically triple negative and vice versa.

Modulation of Molecular Biomarker Expression in Response to Chemotherapy in Invasive Ductal Carcinoma.

Breast cancer (BC) has varied morphological and biological features and is classified based on molecular and morphological examinations. Molecular classification of BC is based on biological gene-expression profiling. In this study, biomarker modulation was assessed during BC treatment in 30 previously untreated patients. Heterogeneity among patients was pathologically diagnosed and classified into luminal and basal-like immunohistochemical profiles based on estrogen, progesterone, and human epidermal growth factor receptor (ER/PR/HER2) status. Marker heterogeneity was compared with mRNA biomarker expression in patients with BC before and after therapy. Reverse transcription-polymerase chain reaction was performed for molecular characterization. Expression and modulation of biological markers, CK19, hMAM, CEA, MUC, Myc, Ki-67, HER2/neu, ErbB2, and ER, were assessed after treatment, where the expression of the biomarkers CK19, Ki-67, Myc, and CEA was noted to be significantly decreased. Marker expression modulation was determined according to different stages and pathological characteristics of patients; coexpression of three markers (CK19, Ki-67, and Myc) was specifically modulated after therapy. In the histopathologically classified basal-like group, two markers (CK19 and Ki-67) were downregulated and could be considered as diagnostic biomarkers. In conclusion, pathological characteristics and marker variation levels can be evaluated to decide a personalized treatment for patients.

High Expression of CCR7 Predicts Lymph Node Metastasis and Good Prognosis in Triple Negative Breast Cancer

Background/Aims: Previous preclinical and clinical studies have reported a positive correlation between the expression of the C-C chemokine receptor 7 (CCR7) and the incidence of lymph node metastasis in breast cancer. However, the prognostic relevance of CCR7 expression in breast cancer remains contradictory till now. The aim of this study is to assess the correlation of the CCR7 expression with other clinicopathological features and prognosis in breast cancer. Methods: The CCR7 gene amplification and mRNA expression levels from approximately 3,000 patients were retrieved from human breast cancer databases and analyzed. Furthermore, a total of 188 primary triple negative breast cancer patients were enrolled in this study (diagnosed since January 2009 to January 2013 from the Second Hospital of Dalian Medical University). The protein levels of CCR7 were examined by immunohistochemistry using paraffin-embedded tumor tissues. Results: The analysis of gene amplification and mRNA levels showed the expression of CCR7 in breast cancer correlated with better prognosis. When we compared the CCR7 expressions in different subtypes, the basal-like group showed the highest expression of CCR7 and exhibited a better prognosis. Consistently, Kaplan–Meier analysis of 188 triple negative breast cancer patients showed that the prognosis of patients with positive CCR7 expression was significantly better than those with negative expression (HR=0.642, p=0.0275). Additionally, we also observed a positive correlation between lymph node metastasis and the CCR7 expression (p=0.0096). Conclusions: Our results indicated that elevated CCR7 expression as a marker for increased lymph node metastasis, in addition to serve as an independent prognostic indicator for better overall survival in triple negative breast cancer patients.

Attempt towards a novel classification of triple-negative breast cancer using immunohistochemical markers.

Significant efforts have been made to gain a better understanding of the heterogeneity of triple-negative breast cancers from the histological to the molecular and genomic levels. In this study, we attempted to bring forward gene expression subtypes of triple-negative breast cancer (TBNC) to the clinic, by translating gene stratification to clinically accessible immunohistochemical (IHC) classification. Using IHC analysis, we categorized 154 TBNC cases into three main subclasses. Differences in the frequencies of basic characteristics and clinicopathological parameters between the subtypes were examined using Chi-square tests. We defined three main groups among the 154 triple-negative cases. The basal-like (BL) group expressed cytokeratin (CK) 5/6 and/or CK14 (83 cases), the AR+ group demonstrated positivity for androgen receptor (18 cases), and the final group exhibited a CD44+CD24-/low phenotype (39 cases). There were three overlapping cases between the BL subgroup and the CD44+CD24-/low phenotype subgroup, and 11 unclassified cases. In this new IHC classification, three subcategories exhibited a statistical difference with regard to age, tumor size, histological grade, tumor necrosis, Ki67 labeling index, relapse-free survival, breast cancer-specific survival and response to chemotherapy. According to our definition, the BL group and CD44+CD24-/low phenotype could be observed in tumors that were not triple-negative, and BL tumors that were triple-negative demonstrated almost undistinguishable clinicopathological characteristics compared with BL tumors that were not triple-negative. The same observation was made with CD44+CD24-/low tumors that were triple-negative vs. CD44+CD24-/low tumors that were not. The AR+ group demonstrated undistinguishable clinicopathological characteristics compared with the luminal subtype. We successfully distinguished three subtypes exhibiting diverse clinicopathological and prognostic characteristics with the minimum use of IHC markers.

Abstract P4-09-15: BRCAness and PD-L1 expression of basal-like and not basal-like triple negative breast cancer

Abstract Background: Triple Negative Breast Cancer (TNBC) subtype occurs in approximately 20% of all patients with breast cancer and is associated with rapid growth, early metastasis and poor prognosis compared with other subtypes. TNBCs are a heterogeneous disease entity and further subclassification is needed, but still ongoing. In this study, we assessed BRCAness, defined as shared characteristics between sporadic and BRCA1-mutated tumors, in a cohort of basal-like and non-basal-like TNBCs. Patients and Methods: DNA was isolated from formalin-fixed paraffin-embedded tumor tissues and BRCAness status was analyzed in 262 patients with primary TNBCs resected at our three hospitals between 2004 and 2014. Classification of BRCAness was performed by using Multiple Ligation-dependent Probe Amplification (MLPA) with the probemix P376 BRCA1ness by MRC (Amsterdam, Holland). The tumor subtypes were routinely determined immunohistochemically by using resected specimens. Basal-like phenotype was defined as being positive for Epidermal Growth Factor Receptor (EGFR) and/or Cytokeratin 5/6 (CK5/6). Moreover, TNBCs were stained and analyzed for programmed cell death ligand-1 (PD-L1) expression as a target of new immune therapies. Results: Of 262 TNBCs, 232 tumors (88.5%) was a basal-like phenotype. The results of MLPA assay showed that 159 (68.5%) of 232 tumors had a BRCAness profile. Patients with basal-like BRCAness tumors were younger than patients with basal-like non-BRCAness tumors (p&amp;lt;0.0001). There was no significant difference between the two groups regarding pathological stage. The basal-like BRCAness group had shorter relapse-free survival (RFS) and overall survival (OS) than the basal-like non-BRCAness group (p=0.028 and p=0.13, respectively), and anthracycline-based regimens provided greater benefit to the basal-like BRCAness group significantly (p=0.01 in RFS and p=0.007 in OS). PD-L1 was expressed in 71 (44.7%) of 159 basal-like TNBCs with BRCAness. Conclusion: We reported the majority of basal-like TNBCs showed a BRCAness profile and PD-L1 expressed in approximately 50% of BRCAness tumors. It is known that about 30% of BRCAness tumors are BRCA1-mutated tumors. Those biomarkers are essential for subclassification of TNBCs and may offer not only platinum-based chemotherapy but also novel therapies, such as immune-targeted therapies of PD-1/PD-L1 inhibitors and PARP inhibitors, to patients with basal-like TNBCs with BRCAness. Citation Format: Mori H, Kubo M, Yamada M, Kai M, Osako T, Nishimura R, Arima N, Okido M, Kuroki S, Oda Y, Nakamura M. BRCAness and PD-L1 expression of basal-like and not basal-like triple negative breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-09-15.

Abstract 2307: Targeted agents and chemotherapeutic treatments of genetically engineered Basal-like breast cancer mouse model

Abstract Background: Genomic characterization of human breast tumors has resulted in the identification of at least five distinct tumor subtypes (Luminal A and B, HER2-enriched, Claudin-low, and Basal-like). These subtypes each show their own unique biology, which correlates with distinct patient outcomes. Basal-like Breast Cancer (BLBC) is associated with high grade, BRCA1 mutation status, younger patient age, and increased frequency in African Americans. In order to identify novel therapeutic strategies for BLBC, we developed a genetically engineered mouse model based upon two common human BLBC genetic events, namely BRCA1 and TP53 loss. Results: We developed a genetically engineered mouse (GEM) model of breast cancer by inactivating TP53 and BRCA1 genes using Cre-LOX technology in the mammary gland (K14-cre / TP53 L/L / BRCA1 L/L). As part of the characterization of this GEM model, we performed gene expression profiling and DNA copy number analysis using aCGH arrays on the Basal-like tumors from this model (25/27 total tumors were Basal-like). We found a number of chromosomal regions that were similarly altered and found to be specific to mouse and human BLBC including gains of mouse chromosome 1q and 12q and losses in chromosomes 3F1 and 15q. Subsequently two tumors from the murine Basal-like group were taken and expanded into an orthotopic syngeneic model where they passaged in wild type FVB mice. These two tumors lines were then tested extensively with chemotherapeutics (Doxorubicin, Carboplatin, Cytoxan, Paclitaxel) and biologically targeted agents (MEK inhibitor/AZD6244, PI3K Inhibitor/BEZ235, PARP Inhibitor/ABT888 and mTOR Inhibitor/Everolimus). The DNA damaging agents exhibited exceptional efficacy (i.e. ABT888, Cytoxan, and Carboplatin), whereas the biologically targeted agents tended to at best, only slow tumor growth, even in combination. Conclusions: Genetic engineering of mice using TP53 and BRCA1 loss results in tumors of predominantly the Basal-like subtype phenotype. As expected, these tumors were exquisitely sensitive to DNA damaging chemotherapeutics including cytoxan and carboplatin, yet generally insensitive to the 3 tested kinase inhibitors. Novel combinations of targeted agents and chemotherapeutics are now being tested. Citation Format: Cristina M. Contreras, Grace O. Silva, Adam D. Pfefferle, Charles M. Perou. Targeted agents and chemotherapeutic treatments of genetically engineered Basal-like breast cancer mouse model. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2307. doi:10.1158/1538-7445.AM2015-2307

Efficacy and prognosis of neoadjuvant chemotherapy is correlated with breast cancer molecular classification.

Breast cancer is one of the most common cancers affecting women globally. Recent studies have begun to investigate the possibility of customized treatment options for individuals based on the specific cancer type. Here, we sought to analyze the relationship between the molecular classification of breast cancer and the efficacy and prognosis of neoadjuvant chemotherapy (NCT). The study included 100 breast cancer patients treated with an NCT regimen of epirubicin and docetaxel (ET) who were divided into groups based on cancer subtype (luminal, HER2 over-expression, and basal-like subtype). The nuclear classification, number of NCT cycles, pathological remission rate, and clinical curative effect, as well as the disease-free survival time (DFS) and the overall survival (OS), were compared across groups. The nuclear grade of participants in the basal-like group was significantly higher than those in the other groups but this group had fewer preoperative NCT cycles and lower pathological remission and clinical efficacy (Z=53.245, 50.077, 62.467, χ2=16.082, p<0.05). The OS and DFS of participants in the luminal subtype group were significantly higher than those in other groups while those in the basal-like subtype group were the lowest. The OS and DFS of participants who achieved pathological complete remission (pCR) through NCT treatment were significantly higher than those of the patients who had not achieved pCR through NCT treatment (χ2=9.558, 10.139, p<0.05). Therefore, we conclude that when NCT (ET regimen) is used in the treatment of breast cancer, the curative effects and prognosis appear to be correlated with the molecular classification of the tumor. Based on these results, clinicians should consider the molecular classification of the individual tumor to design the most effective treatment option.

Breast cancer in very young women: Clinicopathological study of 149 patients ≤25 years old

BackgroundBreast cancer in young women has different clinical and pathologic features and a more aggressive biological behavior when compared to breast cancers in older women. However, information is limited to the group of very young women (≤25 years). ObjectivesThe aim of the present study was to investigate the pathological characteristics of breast cancer in 149 Brazilian women who were ≤25 years old at the time of breast cancer diagnosis. Materials and methodsTumor samples diagnosed between 2003 and 2009 were analyzed from the archives of the Bacchi Laboratory. ResultsIn our series of 149 Brazilian women ≤25 years, 8.7% presented with in situ disease only. Of 136 invasive carcinomas, 91.9% were of the ductal type and 45.6% were of histological grade III. Overall, estrogen receptor (ER) was positive in 59.6% cases, and HER2 overexpression was detected in 32.8%. We also found a low prevalence of Luminal A cases and a high prevalence of Triple Negative cases. Statistical analysis showed that HER2 and basal-like groups had a lower overall survival expectation. Follow-up data showed high frequencies of regional lymph node metastasis, distant metastasis, and tumor-related deaths. ConclusionThe present study represents the largest series of breast cancer arising in women ≤25 years and establishes the main clinical, pathological, immunohistochemical and follow-up features of this population.

Identification of pathogenesis pathway in basal-like breast cancer based on mutant p53 protein and topoisomerase-IIα expression

Background: Basal-like breast cancer is difficult to treat with standard regimen therapy, because it doesn’t express hormone receptors or epidermal growth factor receptors. Identification of oncogenesis pathway is expected to find molecules which can be used as target for therapy. One candidate molecule is topoisomerase-IIα whose expression is regulated by p53. This study aimed to compare the expression of mutant p53 proteins and topoisomerase IIα in basal-like and non basal-like breast cancer, and to determine the association between mutant p53 proteins and topoisomerase IIα in basal-like group.Methods: The samples were 40 formalin fixed paraffin embedded tissues from verified triple negative breast cancer tissue. The samples were divided into 2 groups, basal-like and non basal-like breast cancer, based on cytokeratin - 5 (CK-5) expression. Mutant p53 proteins and topoisomerase IIα were stained using immunohistochemistry method, scored and compared. Statistical test used SPSS software version 16 for descriptive statistics, kappa test, normality test, comparison of two mean, and categorical comparison.Results: Median (min-max) of mutant p53 protein expression in basal-like group was 21 (0-100), the non basal-like group was 2 (0-80), p = 0.061. Min-max of topoisomerase IIα in basal-like group was 263 (15-492), non basal-like group was 262 (0-481), p = 0.409. There was an association between mutant p53 positivity with breast cancer subtype (p = 0.027) and between mutant p53-topoisomerase IIα coexpression with breast cancer subtype (p = 0.018).Conclusion: Co-expression of mutant p53 with topoisomerase IIα has the role in one of the pathway of basal-like breast cancer pathogenesis.

CD70: A Potential Target in Breast Cancer?

CD70 is a co-stimulatory molecule involved in the immune response and also in cancer development and progression. Recent studies show that high CD70 expression in cancer cells may inhibit the anti-tumor response. Furthermore, CD70 expression has been reported as a predictive marker of resistance to chemotherapy in ovarian cancers. Some in vitro studies have shown that CD70 expression is epigenetically down-regulated through hypermethylation of its promoter during tumoral progression. This study evaluated the level of CD70 expression in surgical samples of breast invasive tumors and determined its correlation with CD70 promoter methylation.Twenty “luminal A” and 20 “basal-like” frozen samples from early breast tumors were retrospectively selected. CD70 expression was evaluated by quantitative real-time PCR. Total DNA was bisulfite-treated, and methylation levels of 5 consecutive CG sites present in the proximal region (-464, -421) of the promoter were assessed by pyrosequencing analysis. Statistical analyses were performed using the Mann-Whitney test.The median relative CD70 expression level was 0.37 and was significantly higher in the basal-like group (0.78 [0.24-31.7]) compared to the luminal A group (0.25 [0.03-1.83], p=0.0001). The median methylation level was 61%, with no significant difference between the basal-like (63%) and luminal A (58%) groups. No correlation was found between CD70 expression and CD70 methylation level.In this study, higher CD70 expression was observed in the basal-like group, but this expression was not related to promoter methylation. The higher expression in the poor-prognosis subgroup of patients makes CD70 a potential target for emerging anti-CD70 therapies.

Abstract ES03-1: Clinical 101: The pathology of breast cancer

Abstract Numerous histological types of breast cancer are recognized based on their discrete architectural patterns and associated different risk factors, clinical presentations, pathological features, patterns of spread, response to therapy and outcomes. Traditional prognostic factors include tumor size, lymph node status, tumor grade, and immunohistochemical profile of Estrogen and Progesterone Receptor (ER and PR) and Her2/neu gene amplification status. Histological tumor grade assesses degree of differentiation (tubule formation and nuclear pleomorphism) and proliferative activity (mitotic index). The three histological grades mirror aggressiveness and correlate with survival. Expression profiling reveals only two genomic grades, low and high. The ER positive, HER2 positive and triple negative tumors have correlative molecular subtypes on transcriptome analysis; two ER positive groups, luminal A and B where B tumors have a high proliferation compared with A, a HER2 enriched group, and basal-like group corresponding to triple negative tumors. A molecular apocrine group is characterized by ER negative, Androgen Receptor positive status with paradoxical expression of ER related genes and often HER2. A subset of molecular apocrine carcinomas have a morphological correlate. The traditional prognostic factors used to determine therapy neither capture the complexity of breast cancer nor provide tailored enough treatment options for individual patients. Gene expression profiles which predict disease recurrence pick out the proliferation related genes and a number of different prognostic signatures despite them having &amp;lt; 25% of shared genes between the signatures (e.g. OncotypeDX, PAM50, Mammaprint) identify the Luminal A low risk subgroup, which does not benefit from chemotherapy. These prognostic signatures have no value in ER negative disease where there is a high rate of resistance to chemotherapy regimens. Predictors of sensitivity or resistance to specific regimens of chemotherapy in all tumors and predictors of resistance to hormone therapy in ER positive tumors are needed. The low and high grade genomic signatures reflect two distinct models of tumor progression. The low grade neoplasia pathway is characterized by simple diploid karyotypes, and luminal A type invasive carcinomas in this group share genetic and transcriptomic features with precursor lesions, ADH, FEA. Special subtype tumors in this pathway include tubular, lobular, cribriform, mucinous carcinomas and some neuroendocrine carcinomas. The high grade pathway encompasses high grade DCIS, and high grade invasive ductal carcinoma and is characterized by aneuploidy and complex karyotypes. Although tumors can be lumped broadly into low and high grade, there is enormous diversity between tumors even within the molecular subgroups. For example the basal-like/triple negative group includes tumors with distinct morphology, clinical presentation, prognosis and molecular profiles which requires tailoring of therapies. Two rare low grade clinically indolent basal-like tumors include Secretory carcinomas which harbor a characteristic recurrent balanced chromosomal translocation which leads to a fusion transcript ETV6-NTRK3 and Adenoid cystic carcinomas which have a MYB-NFIB fusion gene. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr ES03-1.