Clinical relevance of the triple-negative breast cancer concept: genetic basis and clinical utility of the concept

Differences in clinical outcomes between HER2-negative and HER2-positive luminal B breast cancer

The clinical features and prognosis of breast cancer can vary widely, depending on the molecular subtype. Luminal B breast cancers are usually either estrogen receptor-positive and/or progesterone receptor-positive with high proliferation of Ki67 index, or HER2 positive (HER2+). The authors compared the clinicopathologic factors and survival rates of different subtypes of luminal B breast cancer according to HER2 status. Between 2009 and 2013, 1131 cases of breast cancer were reviewed and characterized as 1 of 4 different molecular subtypes based on their immunohistochemical results: luminal A, luminal B, HER2+, or triple-negative breast cancer. From these, luminal B breast cancers were extracted and the clinical features and prognosis of the HER2- and the HER2 + subtypes were compared. Survival differed significantly based on the molecular subtype regardless of whether or not the patient received treatment with neoadjuvant chemotherapy. While patients with HER2- luminal B breast cancer who received neoadjuvant chemotherapy had better prognoses, patients with HER2 + luminal B breast cancer who did not receive neoadjuvant chemotherapy had better prognoses. Luminal B breast cancers showed different clinical outcomes and survival rates according to HER2 gene overexpression type. Physicians should consider these results when they establish a treatment strategy.

Circulating Tumor Cells in Breast Cancer Patients: A Balancing Act between Stemness, EMT Features and DNA Damage Responses

Circulating tumor cells (CTCs) traverse vessels to travel from the primary tumor to distant organs where they adhere, transmigrate, and seed metastases. To cope with these challenges, CTCs have reached maximal flexibility to change their differentiation status, morphology, migratory capacity, and their responses to genotoxic stress caused by metabolic changes, hormones, the inflammatory environment, or cytostatic treatment. A significant percentage of breast cancer cells are defective in homologous recombination repair and other mechanisms that protect the integrity of the replication fork. To prevent cell death caused by broken forks, alternative, mutagenic repair, and bypass pathways are engaged but these increase genomic instability. CTCs, arising from such breast tumors, are endowed with an even larger toolbox of escape mechanisms that can be switched on and off at different stages during their journey according to the stress stimulus. Accumulating evidence suggests that DNA damage responses, DNA repair, and replication are integral parts of a regulatory network orchestrating the plasticity of stemness features and transitions between epithelial and mesenchymal states in CTCs. This review summarizes the published information on these regulatory circuits of relevance for the design of biomarkers reflecting CTC functions in real-time to monitor therapeutic responses and detect evolving chemoresistance mechanisms.

Phospholipase Signaling in Breast Cancer

Breast cancer progression results from subversion of multiple intra- or intercellular signaling pathways in normal mammary tissues and their microenvironment, which have an impact on cell differentiation, proliferation, migration, and angiogenesis. Phospholipases (PLC, PLD and PLA) are essential mediators of intra- and intercellular signaling. They hydrolyze phospholipids, which are major components of cell membrane that can generate many bioactive lipid mediators, such as diacylglycerol, phosphatidic acid, lysophosphatidic acid, and arachidonic acid. Enzymatic processing of phospholipids by phospholipases converts these molecules into lipid mediators that regulate multiple cellular processes, which in turn can promote breast cancer progression. Thus, dysregulation of phospholipases contributes to a number of human diseases, including cancer. This review describes how phospholipases regulate multiple cancer-associated cellular processes, and the interplay among different phospholipases in breast cancer. A thorough understanding of the breast cancer-associated signaling networks of phospholipases is necessary to determine whether these enzymes are potential targets for innovative therapeutic strategies.

53BP1 Accumulation in Circulating Tumor Cells Identifies Chemotherapy-Responsive Metastatic Breast Cancer Patients

Evidence suggests that the DNA end-binding protein p53-binding protein 1 (53BP1) is down-regulated in subsets of breast cancer. Circulating tumor cells (CTCs) provide accessible “biopsy material” to track cell traits and functions and their alterations during treatment. Here, we prospectively monitored the 53BP1 status in CTCs from 67 metastatic breast cancer (MBC) patients with HER2- CTCs and known hormone receptor (HR) status of the primary tumor and/or metastases before, during, and at the end of chemotherapeutic treatment with Eribulin. Nuclear 53BP1 staining and genomic integrity were evaluated by immunocytochemical and whole-genome-amplification-based polymerase chain reaction (PCR) analysis, respectively. Comparative analysis of CTCs from patients with triple-negative and HR+ tumors revealed elevated 53BP1 levels in CTCs from patients with HR+ metastases, particularly following chemotherapeutic treatment. Differences in nuclear 53BP1 signals did not correlate with genomic integrity in CTCs at baseline or with nuclear γH2AX signals in MBC cell lines, indicating that 53BP1 detected features beyond DNA damage. Kaplan–Meier analysis revealed an increasing association between nuclear 53BP1-positivity and progression-free survival (PFS) during chemotherapy until the final visit. Our data suggest that 53BP1 detection in CTCs could be a useful marker to capture dynamic changes of chemotherapeutic responsiveness in triple-negative and HR+ MBC.

Transcriptomic analyses identify key differentially expressed genes and clinical outcomes between triple-negative and non-triple-negative breast cancer

Purpose

There are significant differences in the biological behavior between triple-negative breast cancer (TNBC) and non-triple-negative breast cancer (non-TNBC). In the present study, we identify key differential genes and clinical outcomes between TNBC and non-TNBC.

Materials and methods

Transcriptomic analyses used GEO datasets (GSE76275), gene ontology, KEGG pathway analysis and cBioPortal. Quantitative RT-PCR analysis (qRT-PCR) was used to validate the differentially expressed genes. We used the KM Plotter Online Tool and 240 patients with TNBC tissue microarray to assay the prognostic value of HORMAD1.

Results

The upregulated differentially expressed genes were enriched in transcription factor activity, sequence-specific DNA binding and nucleic acid binding transcription factor activity. Only 16 genes were upregulated when further screened for fold change >4-fold change. HORMAD1 and SOX8 exhibited high frequencies of change of greater than 10% (HORMAD1 was close to 20%). qRT-PCR results indicated that HORMAD1 and SOX8 mRNA levels were significantly upregulated in TNBC samples. In KM Plotter Online Tool, high HORMAD1 was associated with worse outcome. In our tissue microarray (including 240 TNBC tissues), IHC analysis revealed that 29.7% (55/240) of the tumor samples exhibited high HORMAD1 expression and 70.3% (185/240) of the tumor samples exhibited low HORMAD1 expression levels. Meanwhile, high HORMAD1 group has a bad prognosis.

Conclusion

The status of transcriptional activation is an important difference between TNBC and non-TNBC. HORMAD1 is a key differential gene associated with poor outcome in TNBC. Epigenetic therapy and agents targeting cancer/testis antigens might potentially help to customize therapies of TNBC.

Chiral polymer modified nanoparticles selectively induce autophagy of cancer cells for tumor ablation

BACKGROUND

Autophagy regulation through exogenous materials has aroused intensive attention to develop treatment protocols according to diverse human diseases. However, to the best of our knowledge, few examples have been reported to selectively control autophagy process and ultimately achieve efficient therapeutic potential.

RESULTS

In this study, monolayers of poly (acryloyl-L, D and racemic valine) (L-PAV-AuNPs, D-PAV-AuNPs and L/D-PAV-AuNPs) chiral molecules were anchored on the surfaces of gold nanoparticles (PAV-AuNPs), and the subsequent chirality-selective effects on autophagy activation were thoroughly studied. The cytotoxicity induced by PAV-AuNPs towards MDA-MB-231 cells (Breast cancer cells) was achieved mainly through autophagy and showed chirality-dependent, with D-PAV-AuNPs exhibiting high autophagy-inducing activity in vitro and in vivo. In contrast, the PAV-AuNPs exhibited autophagy inactivation for normal cells, e.g., 3T3 fibroblasts and HBL-100 cells. The chirality-selective autophagy activation effect in MDA-MB-231 cells was likely attributed to the chirality-variant ROS generation, cellular uptake and their continuous autophagy stimulus. Furthermore, the intratumoral injection of D-PAV-AuNPs could largely suppress the tumor growth but exhibit negligible toxicity in vivo.

CONCLUSIONS

As the first exploration on stereospecific NPs for autophagy induction, this work not only substantiates that chiral polymer coated NPs can selective induce autophagy-specific in cancer cells and achieve a high tumor eradication efficiency in vivo, but also opens up a new direction in discovering unprecedented stereospecific nanoagents for autophagy-associated tumor treatment.

Pathological complete response after cisplatin neoadjuvant therapy is associated with the downregulation of DNA repair genes in BRCA1-associated triple-negative breast cancers

Pathologic complete response (pCR) after neoadjuvant chemotherapy is considered a suitable surrogate marker of treatment efficacy in patients with triple-negative breast cancers (TNBCs). However, the molecular mechanisms underlying pCR as a result of such treatment remain obscure. Using real-time PCR arrays we compared the expression levels of 120 genes involved in the main mechanisms of DNA repair in 43 pretreatment biopsies of BRCA1-associated TNBCs exhibiting pCR and no pathological complete response (non-pCR) after neoadjuvant chemotherapy with cisplatin. Altogether, 25 genes were significantly differentially expressed between tumors exhibiting pCR and non-pCR, and these genes were downregulated in the pCR group compared to the non-pCR group. A difference in expression level greater than 1.5-fold was detected for nine genes: MGMT, ERCC4, FANCB, UBA1, XRCC5, XPA, XPC, PARP3, and RPA1. The non-homologous end joining and nucleotide excision repair pathways of DNA repair showed the most significant relevance. Expression profile of DNA repair genes associated with pCR was different in the node-positive (20 genes with fold change >1.5) and node-negative (only 3 genes) subgroups. Although BRCA1 germline mutations are the principal defects in BRCA1-associated TNBC, our results indicate that the additional downregulation of other genes engaged in major pathways of DNA repair may play a decisive role in the pathological response of these tumors to cisplatin neoadjuvant chemotherapy. The results suggest that patients with node-positive BRCA1-associated TNBCs that do not exhibit pCR after cisplatin neoadjuvant chemotherapy may be candidates for subsequent therapy with PARP inhibitors, whereas UBA1 may be a potential therapeutic target in node-negative subgroup.

How many diseases is triple negative breast cancer: the protagonism of the immune microenvironment

Triple negative breast cancer (TNBC) is a type of breast cancer (BC) that does not express the oestrogen and the progesterone receptors and the human epidermal growth factor receptor type 2 (HER2). Since there are no positive markers to reliably classify TNBC, these tumours are not yet treated with targeted therapies. Perhaps for this reason they are the most aggressive form of breast carcinomas. However, the clinical observation that these patients do not carry a uniformly dismal prognosis, coupled with data coming from pathology and epidemiology, suggests that this negative definition is not capturing a single clinical entity, but several. We critically evaluate this evidence in this paper, reviewing clinical and epidemiological data and new studies that aim to subclassify TNBC. Moreover, evidence on the role of tumour infiltrating lymphocytes (TILs) on TNBC progression, response to chemotherapy and patient outcome have been published. The heterogeneity, observed even at TILs level, highlights the idea that TNBC is much more than a single disease with a unique treatment. The exploration of the immune environment present at the tumour site could indeed help in answering the question 'How many diseases is TNBC' and will help to define prognosis and eventually develop new therapies, by stimulating the immune effector cells or by inhibiting immunological repressor molecules. In this review, we focus on the prospect of the patient's diverse immune signatures within the tumour as potential biomarkers and how they could be modulated to fight the disease.

The BRCA1ness signature is associated significantly with response to PARP inhibitor treatment versus control in the I-SPY 2 randomized neoadjuvant setting

BACKGROUND

Patients with BRCA1-like tumors correlate with improved response to DNA double-strand break-inducing therapy. A gene expression-based classifier was developed to distinguish between BRCA1-like and non-BRCA1-like tumors. We hypothesized that these tumors may also be more sensitive to PARP inhibitors than standard treatments.

METHODS

A diagnostic gene expression signature (BRCA1ness) was developed using a centroid model with 128 triple-negative breast cancer samples from the EU FP7 RATHER project. This BRCA1ness signature was then tested in HER2-negative patients (n = 116) from the I-SPY 2 TRIAL who received an oral PARP inhibitor veliparib in combination with carboplatin (V-C), or standard chemotherapy alone. We assessed the association between BRCA1ness and pathologic complete response in the V-C and control arms alone using Fisher's exact test, and the relative performance between arms (biomarker × treatment interaction, likelihood ratio p < 0.05) using a logistic model and adjusting for hormone receptor status (HR).

RESULTS

We developed a gene expression signature to identify BRCA1-like status. In the I-SPY 2 neoadjuvant setting the BRCA1ness signature associated significantly with response to V-C (p = 0.03), but not in the control arm (p = 0.45). We identified a significant interaction between BRCA1ness and V-C (p = 0.023) after correcting for HR.

CONCLUSIONS

A genomic-based BRCA1-like signature was successfully translated to an expression-based signature (BRC1Aness). In the I-SPY 2 neoadjuvant setting, we determined that the BRCA1ness signature is capable of predicting benefit of V-C added to standard chemotherapy compared to standard chemotherapy alone.

TRIAL REGISTRATION

I-SPY 2 TRIAL beginning December 31, 2009: Neoadjuvant and Personalized Adaptive Novel Agents to Treat Breast Cancer (I-SPY 2), NCT01042379 .

Next Generation Sequencing Reveals High Prevalence of BRCA1 and BRCA2 Variants of Unknown Significance in Early-Onset Breast Cancer in African American Women

BACKGROUND

Variants of unknown significance (VUSs) have been identified in BRCA1 and BRCA2 and account for the majority of all identified sequence alterations. Notably, VUSs occur disproportionately in people of African descent hampering breast cancer (BCa) management and prevention efforts in the population. Our study sought to identify and characterize mutations associated with increased risk of BCa at young age.

METHODS

In our study, the spectrum of mutations in BRCA1 and BRCA2 was enumerated in a cohort of 31 African American women of early age at onset breast cancer, with a family history of breast or cancer in general and/or with triple negative breast cancer. To improve the characterization of the BRCA1 and BRCA2 variants, bioinformatics tools were utilized to predict the potential function of each of the variants.

RESULTS

Using next generation sequencing methods and in silico analysis of variants, a total of 197 BRCA1 and 266 BRCA2 variants comprising 77 unique variants were identified in 31 patients. Of the 77 unique variants, one (1.3%) was a pathogenic frameshift mutation (rs80359304; BRCA2 Met591Ile), 13 (16.9%) were possibly pathogenic, 34 (44.2%) were benign, and 29 (37.7%) were VUSs. Genetic epidemiological approaches were used to determine the association with variant, haplotype, and phenotypes, such as age at diagnosis, family history of cancer and family history of breast cancer. There were 5 BRCA1 SNPs associated with age at diagnosis; rs1799966 (P=.045; Log Additive model), rs16942 (P=.033; Log Additive model), rs1799949 (P=.058; Log Additive model), rs373413425 (P=.040 and .023; Dominant and Log Additive models, respectively) and rs3765640 (P=.033 Log Additive model). Additionally, a haplotype composed of all 5 SNPs was found to be significantly associated with younger age at diagnosis using linear regression modeling (P=.023). Specifically, the haplotype containing all the variant alleles was associated with older age at diagnosis (OR= 5.03 95% CI=.91-9.14).

CONCLUSIONS

Knowing a patient's BRCA mutation status is important for prevention and treatment decision-making. Improving the characterization of mutations will lead to better management, treatment, and BCa prevention efforts in African Americans who are disproportionately affected with aggressive BCa and may inform future precision medicine genomic-based clinical studies.

"Triple negative breast cancer": Translational research and the (re)assembling of diseases in post-genomic medicine

The paper examines the debate about the nature and status of "Triple-negative breast cancer", a controversial biomedical entity whose existence illustrates a number of features of post-genomic translational research. The emergence of TNBC is intimately linked to the rise of molecular oncology, and, more generally, to the changing configuration of the life sciences at the turn of the new century. An unprecedented degree of integration of biological and clinical practices has led to the proliferation of bio-clinical entities emerging from translational research. These translations take place between platforms rather than between clinical and laboratory settings. The complexity and heterogeneity of TNBC, its epistemic and technical, biological and clinical dualities, result from its multiple instantiations via different platforms, and from the uneven distribution of biological materials, techniques, and objects across clinical research settings. The fact that TNBC comes in multiple forms, some of which seem to be incompatible or, at least, only partially overlapping, appears to be less a threat to the whole endeavor, than an aspect of an ongoing translational research project. Discussions of translational research that rest on a distinction between basic research and its applications fail to capture the dynamics of this new domain of activity, insofar as application is built-in from the very beginning in the bio-clinical entities that emerge from the translational research domain.

Tumor Infiltrating Lymphocytes Affect the Outcome of Patients with Operable Triple-Negative Breast Cancer in Combination with Mutated Amino Acid Classes

Background

Stromal tumor infiltrating lymphocytes (TILs) density is an outcome predictor in triple-negative breast cancer (TNBC). Herein we asked whether TILs are related to coding mutation load and to the chemical class of the resulting mutated amino acids, i.e., charged, polar, and hydrophobic mutations.

Methods

We examined paraffin tumors from TNBC patients who had been treated with adjuvant chemotherapy mostly within clinical trials (training cohort, N = 133; validation, N = 190) for phenotype concordance; TILs density; mutation load and types.

Results

Concordance of TNBC phenotypes was 42.1% upon local / central, and 72% upon central / central pathology assessment. TILs were not associated with mutation load, type and class of mutated amino acids. Polar and charged mutation patterns differed between TP53 and PIK3CA (p<0.001). Hydrophobic mutations predicted for early relapse in patients with high nodal burden and <50% TILs tumors (training: HR 3.03, 95%CI 1.11–8.29, p = 0.031; validation: HR 2.90, 95%CI 0.97–8.70, p = 0.057), especially if compared to patients with >50% TILs tumors (training p = 0.003; validation p = 0.015).

Conclusions

TILs density is unrelated to mutation load in TNBC, which may be regarded as an unstable phenotype. If further validated, hydrophobic mutations along with TILs density may help identifying TNBC patients in higher risk for relapse.

The Role of PIWIL4, an Argonaute Family Protein, in Breast Cancer

P-element-induced wimpy testis (PIWI) proteins bind to PIWI-interacting RNAs and play key roles in the biogenesis and functions of PIWI-interacting RNAs. It has been reported that PIWI proteins are essential for stem cell self-renewal and germline development in diverse organisms and that they are ectopically expressed in multiple forms of cancer. However, the role of PIWI in cancer remains elusive. Here we report that one of the four PIWI proteins in humans, PIWIL4, is highly expressed in both breast cancer tissues and the cytoplasm of MDA-MB-231 cells derived from breast cancer. Reducing PIWIL4 expression drastically impairs the migration ability of MDA-MB-231 cells, significantly increases their apoptosis, and mildly affects their proliferation. Our transcriptome and proteome analysis reveal that these functions are at least partially achieved via the PIWIL4 regulation of TGF-β and FGF signaling pathways and MHC class II proteins. These findings suggest that PIWIL4 may serve as a potential therapeutic target for breast cancer.

Higher levels of TIMP-1 expression are associated with a poor prognosis in triple-negative breast cancer

Background

Tissue inhibitor of metalloproteinases-1 (TIMP-1) is a multifunctional protein that can directly regulate apoptosis and metastasis. In this study, we investigated the functional and molecular mechanisms by which TIMP-1 influences triple-negative breast cancer (TNBC).

Methods

The expression level of TIMP-1 in breast cancer tissues was analyzed using the ONCOMINE microarray database. The overall survival of patients with distinct molecular subtypes of breast cancer stratified by TIMP-1 expression levels was evaluated using Kaplan–Meier analysis. Bisulfate sequencing PCR (BSP) was used to analyze the methylation status of the TIMP-1 promoter. Real-time-PCR (RT-PCR), Western blot and ELISA assays were used to evaluate gene and protein expression in cell lines and human tissue specimens. In addition, TIMP-1 function was analyzed using a series of in vitro and in vivo assays with cells in which TIMP-1 was inhibited using RNAi or neutralizing antibodies.

Results

We found that serum TIMP-1 levels were strongly enhanced in patients with TNBC and that elevated TIMP-1 levels were associated with a poor prognosis in TNBC. However, TIMP-1 levels were not significantly associated with overall survival in other subtypes of breast cancer or in the overall population of breast cancer patients. We also report the first evidence that the TIMP-1 promoter is hypomethylated in TNBC cell lines compared with non-TNBC cell lines, suggesting that aberrant TIMP-1 expression in TNBC results from reduced DNA methylation. RNAi-mediated silencing of TIMP-1 in TNBC cells induced cell cycle arrest at the G1 phase and reduced cyclin D1 expression. In addition, mechanistic analyses revealed that the p-Akt and p-NF-κB signaling pathways, but not the GSK-3β and MAPK1/2 pathways, are associated with TIMP-1 overexpression in TNBC cells. Moreover, neutralizing antibodies against TIMP-1 significantly decreased the rate of tumor growth in vivo.

Conclusions

Our findings suggest that TIMP-1 is a biomarker indicative of a poor prognosis in TNBC patients and that targeting TIMP-1 may provide an attractive therapeutic intervention specifically for triple-negative breast cancer patients.

BRCA1-like signature in triple negative breast cancer: Molecular and clinical characterization reveals subgroups with therapeutic potential

Triple negative (TN) breast cancers make up some 15% of all breast cancers. Approximately 10-15% are mutant for the tumor suppressor, BRCA1. BRCA1 is required for homologous recombination-mediated DNA repair and deficiency results in genomic instability. BRCA1-mutated tumors have a specific pattern of genomic copy number aberrations that can be used to classify tumors as BRCA1-like or non-BRCA1-like. BRCA1 mutation, promoter methylation, BRCA1-like status and genome-wide expression data was determined for 112 TN breast cancer samples with long-term follow-up. Mutation status for 21 known DNA repair genes and PIK3CA was assessed. Gene expression and mutation frequency in BRCA1-like and non-BRCA1-like tumors were compared. Multivariate survival analysis was performed using the Cox proportional hazards model. BRCA1 germline mutation was identified in 10% of patients and 15% of tumors were BRCA1 promoter methylated. Fifty-five percent of tumors classified as BRCA1-like. The functions of genes significantly up-regulated in BRCA1-like tumors included cell cycle and DNA recombination and repair. TP53 was found to be frequently mutated in BRCA1-like (P < 0.05), while PIK3CA was frequently mutated in non-BRCA1-like tumors (P < 0.05). A significant association with worse prognosis was evident for patients with BRCA1-like tumors (adjusted HR = 3.32, 95% CI = 1.30-8.48, P = 0.01). TN tumors can be further divided into two major subgroups, BRCA1-like and non-BRCA1-like with different mutation and expression patterns and prognoses. Based on these molecular patterns, subgroups may be more sensitive to specific targeted agents such as PI3K or PARP inhibitors.

Breast Cancer Survival Defined by the ER/PR/HER2 Subtypes and a Surrogate Classification according to Tumor Grade and Immunohistochemical Biomarkers

Introduction. ER, PR, and HER2 are routinely available in breast cancer specimens. The purpose of this study is to contrast breast cancer-specific survival for the eight ER/PR/HER2 subtypes with survival of an immunohistochemical surrogate for the molecular subtype based on the ER/PR/HER2 subtypes and tumor grade. Methods. We identified 123,780 cases of stages 1-3 primary female invasive breast cancer from California Cancer Registry. The surrogate classification was derived using ER/PR/HER2 and tumor grade. Kaplan-Meier survival analysis and Cox proportional hazards modeling were used to assess differences in survival and risk of mortality for the ER/PR/HER2 subtypes and surrogate classification within each stage. Results. The luminal B/HER2- surrogate classification had a higher risk of mortality than the luminal B/HER2+ for all stages of disease. There was no difference in risk of mortality between the ER+/PR+/HER2- and ER+/PR+/HER2+ in stage 3. With one exception in stage 3, the ER-negative subtypes all had an increased risk of mortality when compared with the ER-positive subtypes. Conclusions. Assessment of survival using ER/PR/HER2 illustrates the heterogeneity of HER2+ subtypes. The surrogate classification provides clear separation in survival and adjusted mortality but underestimates the wide variability within the subtypes that make up the classification.

P16 but not retinoblastoma expression is related to clinical outcome in no-special-type triple-negative breast carcinomas

Triple-negative breast carcinomas represent a tumor group of pivotal clinical importance given the lack of target therapies. The prognostic significance of triple-negative breast carcinomas remains unclear because of their histological and molecular heterogeneity. Currently, neither prognostic nor predictive factors are available for these tumors. Retinoblastoma (Rb) pathway loss has been linked to clinical outcome in various cancer types, including breast cancer. We investigated the association between Rb and p16 protein expression and clinical outcome in no-special-type triple-negative breast carcinomas. Immunohistochemical staining for Rb, p16, p53 and CK5 was carried out on a section from archival specimens of 117 no-special-type triple-negative breast carcinomas. Immunopositive p16 (p16+) and immunonegative Rb (Rb-) staining were seen in 49.5% and in 24.8% of tumors, respectively. There was an inverse correlation between p16+ and Rb- (P<0.001). P16+ was correlated with G3 grade (P<0.001), high Ki-67 (P=0.03), p53 overexpression (P<0.001) and CK5 immunopositivity (P=0.01). Rb- was not associated with any clinicopathologic variable. Follow-up and therapy data were available in 95 patients. In 20 patients treated with surgery only, neither p16+ nor Rb- immunostaining were associated with disease-free survival and overall survival. In 75 patients treated with adjuvant chemotherapy, p16+ was associated with good response to therapy with significant increased disease-free survival (P=0.001) and showed a trend towards a statistical significance for increased overall survival (P=0.056); Rb- were not associated with disease-free survival and overall survival. In multivariate analysis, p16+ was independently associated with disease-free and overall survival, with a hazard ratio of 0.18 (95% CI: 0.06-0.51; P=0.001) and 0.21 (95% CI: 0.06-0.74; P=0.015), respectively. In patients with no-special-type triple-negative breast carcinomas, p16+ is related to good response to adjuvant chemotherapy and can be considered the best surrogate marker for Rb pathway loss.

HIC1 silencing in triple-negative breast cancer drives progression through misregulation of LCN2

The tumor suppressor gene HIC1 is frequently deleted or epigenetically silenced in human cancer, where its restoration may improve cancer prognosis. Here, we report results illuminating how HIC1 silencing alters effect or signals in triple-negative breast cancer (TNBC), which are crucial for its pathogenesis. HIC1 expression was silenced only in TNBC compared with other molecular subtypes of breast cancer. Restoring HIC1 expression in TNBC cells reduced cell migration, invasion, and metastasis, whereas RNAi-mediated silencing of HIC1 in untransformed human breast cells increased their invasive capabilities. Mechanistic investigations identified the small-secreted protein lipocalin-2 (LCN2), as a critical downstream target of HIC1 in TNBC cells. Elevating LCN2 expression in cells expressing HIC1 partially rescued its suppression of cell invasion and metastasis. Notably, autocrine secretion of LCN2 induced by loss of HIC1 activated the AKT pathway through the neutrophil gelatinase-associated lipocalin receptor, which is associated with TNBC progression. Taken together, our findings revealed that the HIC1-LCN2 axis may serve as a subtype-specific prognostic biomarker, providing an appealing candidate target for TNBC therapy.

Molecular phenotypes in triple negative breast cancer from African American patients suggest targets for therapy

Triple negative breast cancer (TNBC) is characterized by high proliferation, poor differentiation and a poor prognosis due to high rates of recurrence. Despite lower overall incidence African American (AA) patients suffer from higher breast cancer mortality in part due to the higher proportion of TNBC cases among AA patients compared to European Americans (EA). It was recently shown that the clinical heterogeneity of TNBC is reflected by distinct transcriptional programs with distinct drug response profiles in preclinical models. In this study, gene expression profiling and immunohistochemistry were used to elucidate potential differences between TNBC tumors of EA and AA patients on a molecular level. In a retrospective cohort of 136 TNBC patients, a major transcriptional signature of proliferation was found to be significantly upregulated in samples of AA ethnicity. Furthermore, transcriptional profiles of AA tumors showed differential activation of insulin-like growth factor 1 (IGF1) and a signature of BRCA1 deficiency in this cohort. Using signatures derived from the meta-analysis of TNBC gene expression carried out by Lehmann et al., tumors from AA patients were more likely of basal-like subtypes whereas transcriptional features of many EA samples corresponded to mesenchymal-like or luminal androgen receptor driven subtypes. These results were validated in The Cancer Genome Atlas mRNA and protein expression data, again showing enrichment of a basal-like phenotype in AA tumors and mesenchymal subtypes in EA tumors. In addition, increased expression of VEGF-activated genes together with elevated microvessel area determined by the AQUA method suggest that AA patients exhibit higher tumor vascularization. This study confirms the existence of distinct transcriptional programs in triple negative breast cancer in two separate cohorts and that these programs differ by racial group. Differences in TNBC subtypes and levels of tumor angiogenesis in AA versus EA patients suggest that targeted therapy choices should be considered in the context of race.

Somatic copy number changes in DPYD are associated with lower risk of recurrence in triple-negative breast cancers

BACKGROUND

Genomic rearrangements at the fragile site FRA1E may disrupt the dihydropyrimidine dehydrogenase gene (DPYD) which is involved in 5-fluorouracil (5-FU) catabolism. In triple-negative breast cancer (TNBC), a subtype of breast cancer frequently deficient in DNA repair, we have investigated the susceptibility to acquire copy number variations (CNVs) in DPYD and evaluated their impact on standard adjuvant treatment.

METHODS

DPYD CNVs were analysed in 106 TNBC tumour specimens using multiplex ligation-dependent probe amplification (MLPA) analysis. Dihydropyrimidine dehydrogenase (DPD) expression was determined by immunohistochemistry in 146 tumour tissues.

RESULTS

In TNBC, we detected 43 (41%) tumour specimens with genomic deletions and/or duplications within DPYD which were associated with higher histological grade (P=0.006) and with rearrangements in the DNA repair gene BRCA1 (P=0.007). Immunohistochemical analysis revealed low, moderate and high DPD expression in 64%, 29% and 7% of all TNBCs, and in 40%, 53% and 7% of TNBCs with DPYD CNVs, respectively. Irrespective of DPD protein levels, the presence of CNVs was significantly related to longer time to progression in patients who had received 5-FU- and/or anthracycline-based polychemotherapy (hazard ratio=0.26 (95% CI: 0.07-0.91), log-rank P=0.023; adjusted for tumour stage: P=0.037).

CONCLUSION

Genomic rearrangements in DPYD, rather than aberrant DPD protein levels, reflect a distinct tumour profile associated with prolonged time to progression upon first-line chemotherapy in TNBC.

Another review on triple negative breast cancer. Are we on the right way towards the exit from the labyrinth?

Triple negative breast cancer is a heterogeneous group of tumors, lacking the expression of estrogen, progesterone and HER-2 receptors. As frequency, it accounts about 15-20% of all breast cancers. Although in the last years there was a "boom" in publishing over this issue, multiple molecular classifications being elaborated, "the triple negative breast cancer odyssey " is still far away from ending, as the complicated molecular pathways of pathogenesis and drug resistance mechanisms remain yet insufficiently explored. The aim of this review is presentation of molecular signatures that could predict outcome and drug resistance in triple negative breast cancer.

Breast cancer in women at high risk: the role of rapid genetic testing for BRCA1 and -2 mutations and the consequences for treatment strategies

Specific clinical questions rise when patients, who are diagnosed with breast cancer, are at risk of carrying a mutation in BRCA1 and -2 gene due to a strong family history or young age at diagnosis. These questions concern topics such as 1. Timing of genetic counseling and testing, 2. Choices to be made for BRCA1 or -2 mutation carriers in local treatment, contralateral treatment, (neo)adjuvant systemic therapy, and 3. The psychological effects of rapid testing. The knowledge of the genetic status might have several advantages for the patient in treatment planning, such as the choice whether or not to undergo mastectomy and/or prophylactic contralateral mastectomy. The increased risk of developing a second breast cancer in the ipsilateral breast in mutation carriers, is only slightly higher after primary cancer treatment, than in the general population. Prophylactic contralateral mastectomy provides a substantial reduction of contralateral breast cancer, although only a small breast cancer specific survival benefit. Patients should be enrolled in clinical trials to investigate (neo)-adjuvant drug regimens, that based on preclinical and early clinical evidence might be targeting the homologous recombination defect, such as platinum compounds and PARP inhibitors. If rapid testing is performed, the patient can make a well-balanced decision. Although rapid genetic counseling and testing might cause some distress, most women reported this approach to be worthwhile. In this review the literature regarding these topics is evaluated. Answers and suggestions, useful in clinical practice are discussed.

Understanding the biology of triple-negative breast cancer

Greater understanding of the biology of triple-negative breast cancer (TNBC) is needed to discern the roughly 60% of node-negative patients who are already cured with locoregional therapy from the 40% who need adjuvant systemic therapy to be cured. Recent evidence suggests that patients with TNBC whose tumours have an activated immune response gene signature have a more favourable outcome than TNBC patients without this signature. For the group who needs additional systemic therapy, the challenge remains to choose the right systemic drug combination for the right TNBC sub-type. Significant heterogeneity exists within the TNBC class that is exemplified by differing chemotherapeutic sensitivity observed for some sub-types. This heterogeneity establishes the need for identifying differentiating molecular markers within the overall class of TNBC disease, which may help refine therapeutic management. In this review, we discuss some of these promising predictive molecular markers for tailoring therapy. In addition, several gene expression profiling and functional studies employing genetic screens that help to establish TNBC sub-groups with varying sensitivities to a variety of targeted therapies currently under clinical investigation are conferred. It is anticipated that a greater understanding of the biology of TNBC and its complex heterogeneity will reveal novel targets or identify markers around which clinical trials in molecularly well-defined sub-groups can be designed.

MUTYH gene variants and breast cancer in a Dutch case–control study

The MUTYH gene is involved in base excision repair. MUTYH mutations predispose to recessively inherited colorectal polyposis and cancer. Here, we evaluate an association with breast cancer (BC), following up our previous finding of an elevated BC frequency among Dutch bi-allelic MUTYH mutation carriers. A case–control study was performed comparing 1,469 incident BC patients (ORIGO cohort), 471 individuals displaying features suggesting a genetic predisposition for BC, but without a detectable BRCA1 or BRCA2 mutation (BRCAx cohort), and 1,666 controls. First, for 303 consecutive patients diagnosed before age 55 years and/or with multiple primary breast tumors, the MUTYH coding region and flanking introns were sequenced. The remaining subjects were genotyped for five coding variants, p.Tyr179Cys, p.Arg309Cys, p.Gly396Asp, p.Pro405Leu, and p.Ser515Phe, and four tagging SNPs, c.37-2487G>T, p.Val22Met, c.504+35G>A, and p.Gln338His. No bi-allelic pathogenic MUTYH mutations were identified. The pathogenic variant p.Gly396Asp and the variant of uncertain significance p.Arg309Cys occurred twice as frequently in BRCAx subjects as compared to incident BC patients and controls (p = 0.13 and p = 0.15, respectively). The likely benign variant p.Val22Met occurred less frequently in patients from the incident BC (p = 0.03) and BRCAx groups (p = 0.11), respectively, as compared to the controls. Minor allele genotypes of several MUTYH variants showed trends towards association with lobular BC histology. This extensive case–control study could not confirm previously reported associations of MUTYH variants with BC, although it was too small to exclude subtle effects on BC susceptibility.

Quantitative copy number analysis by Multiplex Ligation-dependent Probe Amplification (MLPA) of BRCA1-associated breast cancer regions identifies BRCAness

Introduction

Our group has previously employed array Comparative Genomic Hybridization (aCGH) to assess the genomic patterns of BRCA1-mutated breast cancers. We have shown that the so-called BRCA1-like^aCGH profile is also present in about half of all triple-negative sporadic breast cancers and is predictive for benefit from intensified alkylating chemotherapy. As aCGH is a rather complex method, we translated the BRCA1^aCGH profile to a Multiplex Ligation-dependent Probe Amplification (MLPA) assay, to identify both BRCA1-mutated breast cancers and sporadic cases with a BRCA1-like^aCGH profile.

Methods

The most important genomic regions of the original aCGH based classifier (3q22-27, 5q12-14, 6p23-22, 12p13, 12q21-23, 13q31-34) were mapped to a set of 34 MLPA probes. The training set consisted of 39 BRCA1-like^aCGH breast cancers and 45 non-BRCA1-like^aCGH breast cancers, which had previously been analyzed by aCGH. The BRCA1-like^aCGH group consisted of germline BRCA1-mutated cases and sporadic tumours with low BRCA1 gene expression and/or BRCA1 promoter methylation. We trained a shrunken centroids classifier on the training set and validation was performed on an independent test set of 40 BRCA1-like^aCGH breast cancers and 32 non-BRCA1-like^aCGH breast cancer tumours. In addition, we validated the set prospectively on 69 new triple-negative tumours.

Results

BRCAness in the training set of 84 tumours could accurately be predicted by prediction analysis of microarrays (PAM) (accuracy 94%). Application of this classifier on the independent validation set correctly predicted BRCA-like status of 62 out of 72 breast tumours (86%). Sensitivity and specificity were 85% and 87%, respectively. When the MLPA-test was subsequently applied to 46 breast tumour samples from a randomized clinical trial, the same survival benefit for BRCA1-like tumours associated with intensified alkylating chemotherapy was shown as was previously reported using the aCGH assay.

Conclusions

Since the MLPA assay can identify BRCA1-deficient breast cancer patients, this method could be applied both for clinical genetic testing and as a predictor of treatment benefit. BRCA1-like tumours are highly sensitive to chemotherapy with DNA damaging agents, and most likely to poly ADP ribose polymerase (PARP)-inhibitors. The MLPA assay is rapid and robust, can easily be multiplexed, and works well with DNA derived from paraffin-embedded tissues.

Genomic signature of BRCA1 deficiency in sporadic basal-like breast tumors

About 10-20% of all breast carcinomas show a basal-like phenotype, while ∼ 90% of breast tumors from BRCA1-mutation carriers are of this subtype. There is growing evidence that BRCA1-mutated tumors are not just a specific subset of the basal-like tumors, but that (the majority of) basal-like tumors show a dysfunctional BRCA1 pathway. This has major treatment implications, because emerging regimens specifically targeting DNA repair mechanisms would then be most effective against these tumors. To further understand the involvement of BRCA1 deficiency in sporadic basal-like tumors, we investigated 41 basal-like tumors for BRCA1 mRNA expression by quantitative real-time polymerase chain reaction, BRCA1 promoter methylation, their genomic profile by array-CGH, and gene expression levels by whole genome expression arrays. Array-CGH results were compared to those of 34 proven BRCA1-mutated tumors. Basal-like tumors were subdivided into two equal groups: deficient and proficient in BRCA1 gene expression. The chromosomal makeup of BRCA1 deficient sporadic basal-like tumors was similar to that of BRCA1-mutated tumors. BRCA1 proficient sporadic basal-like tumors were more similar to nonbasal-like tumors. Only half of the basal-like breast tumors are actually deficient in BRCA1 expression. Gain of chromosome arm 3q is a marker for BRCA1 deficiency in hereditary and sporadic breast tumors.

Triple-negative breast cancer: epidemiology and management options

The triple receptor-negative breast cancer (TNBC) subtype is characterized by the lack of expression of both hormone receptors as well as lack of over-expression and/or lack of gene amplification of human epidermal growth factor receptor 2 (HER2). Approximately 10-15% of breast carcinomas are known to be of the TNBC subtype, which constitutes approximately 80% of all 'basal-like tumours'. Risk factors for TNBC include young age at breast cancer diagnosis, young age at menarche, high parity, lack of breast feeding, high body mass index and African American ethnicity. The majority of BRCA1 tumours are TNBC. TNBC has a worse prognosis and tends to relapse early compared with other subtypes of breast cancer. Conversely, it displays increased chemosensitivity compared with other breast tumour subtypes. Several agents are currently being investigated as potential therapeutic agents for the treatment of women with TNBC including agents targeted against EGFR, anti-angiogenic agents, multityrosine kinase inhibitors and poly (ADP-ribose) polymerase (PARP) inhibitors. This review focuses on the epidemiology of TNBC, its pathological features, natural history and recurrence patterns as well as current and future management options.

Development of metastatic HER2(+) breast cancer is independent of the adaptive immune system

The tumour-modulating effects of the endogenous adaptive immune system are rather paradoxical. Whereas some clinical and experimental observations offer compelling evidence for the existence of immunosurveillance, other studies have revealed promoting effects of the adaptive immune system on primary cancer development and metastatic disease. We examined the functional significance of the adaptive immune system as a regulator of spontaneous HER2(+) breast tumourigenesis and pulmonary metastasis formation, using the MMTV-NeuT mouse model in which mammary carcinogenesis is induced by transgenic expression of the activated HER2/neu oncogene. Although T and B lymphocytes infiltrate human and experimental HER2(+) breast tumours, genetic elimination of the adaptive immune system does not affect development of premalignant hyperplasias or primary breast cancers. In addition, we demonstrate that pulmonary metastasis formation in MMTV-NeuT mice is not dependent on the adaptive immune system. Thus, our findings reveal that spontaneous HER2-driven mammary tumourigenesis and metastasis formation are neither suppressed, nor altered by immunosurveillance mechanisms, nor promoted by the adaptive immune system.

Cytosolic phospholipase A2-α expression in breast cancer is associated with EGFR expression and correlates with an adverse prognosis in luminal tumours

Background:

The eicosanoid signalling pathway promotes the progression of malignancies through the production of proliferative prostaglandins (PGs). Cytosolic phospholipase A₂α (cPLA₂α) activity provides the substrate for cyclooxygenase-dependent PG release, and we have previously found that cPLA₂α expression correlated with EGFR/HER2 over-expression in a small number of breast cancer cell lines.

Methods:

The importance of differential cPLA₂α activity in clinical breast cancer was established by relating the expression of cPLA₂α in tissue samples from breast cancer patients, and two microarray-based gene expression datasets to different clinicopathological and therapeutic parameters.

Results:

High cPLA₂α mRNA expression correlated with clinical parameters of poor prognosis, which are characteristic of highly invasive tumours of the HER2-positive and basal-like subtype, including low oestrogen receptor expression and high EGFR expression. High cPLA₂α expression decreased overall survival in patients with luminal cancers, and correlated with a reduced effect of tamoxifen treatment. The cPLA₂α expression was an independent predictive parameter of poor response to endocrine therapy in the first 5 years of follow-up.

Conclusion:

This study shows a role of cPLA₂α in luminal breast cancer progression, in which the enzyme could represent a novel therapeutic target and a predictive marker.

BRCA1-mutated and basal-like breast cancers have similar aCGH profiles and a high incidence of protein truncating TP53 mutations

BACKGROUND

Basal-like breast cancers (BLBC) are aggressive breast cancers for which, so far, no targeted therapy is available because they typically lack expression of hormone receptors and HER2. Phenotypic features of BLBCs, such as clinical presentation and early age of onset, resemble those of breast tumors from BRCA1-mutation carriers. The genomic instability of BRCA1-mutated tumors can be effectively targeted with DNA-damaging agents and poly-(ADP-ribose) polymerase 1 (PARP1) inhibitors. Molecular similarities between BLBCs and BRCA1-mutated tumors may therefore provide predictive markers for therapeutic response of BLBCs.

METHODS

There are several known molecular features characteristic for BRCA1-mutated breast tumors: 1) increased numbers of genomic aberrations, 2) a distinct pattern of genomic aberrations, 3) a high frequency of TP53 mutations and 4) a high incidence of complex, protein-truncating TP53 mutations. We compared the frequency of TP53 mutations and the pattern and amount of genomic aberrations between BRCA1-mutated breast tumors, BLBCs and luminal breast tumors by TP53 gene sequencing and array-based comparative genomics hybridization (aCGH) analysis.

RESULTS

We found that the high incidence of protein truncating TP53 mutations and the pattern and amount of genomic aberrations specific for BRCA1-mutated breast tumors are also characteristic for BLBCs and different from luminal breast tumors.

CONCLUSIONS

Complex, protein truncating TP53 mutations in BRCA1-mutated tumors may be a direct consequence of genomic instability caused by BRCA1 loss, therefore, the presence of these types of TP53 mutations in sporadic BLBCs might be a hallmark of BRCAness and a potential biomarker for sensitivity to PARP inhibition. Also, our data suggest that a small subset of genomic regions may be used to identify BRCA1-like BLBCs. BLBCs share molecular features that were previously found to be specific for BRCA1-mutated breast tumors. These features might be useful for the identification of tumors with increased sensitivity to (high-dose or dose-dense) alkylating agents and PARP inhibitors.

Aberrant expression of DNA damage response proteins is associated with breast cancer subtype and clinical features

Landmark studies of the status of DNA damage checkpoints and associated repair functions in preneoplastic and neoplastic cells has focused attention on importance of these pathways in cancer development, and inhibitors of repair pathways are in clinical trials for treatment of triple negative breast cancer. Cancer heterogeneity suggests that specific cancer subtypes will have distinct mechanisms of DNA damage survival, dependent on biological context. In this study, status of DNA damage response (DDR)-associated proteins was examined in breast cancer subtypes in association with clinical features; 479 breast cancers were examined for expression of DDR proteins γH2AX, BRCA1, pChk2, and p53, DNA damage-sensitive tumor suppressors Fhit and Wwox, and Wwox-interacting proteins Ap2α, Ap2γ, ErbB4, and correlations among proteins, tumor subtypes, and clinical features were assessed. In a multivariable model, triple negative cancers showed significantly reduced Fhit and Wwox, increased p53 and Ap2γ protein expression, and were significantly more likely than other subtype tumors to exhibit aberrant expression of two or more DDR-associated proteins. Disease-free survival was associated with subtype, Fhit and membrane ErbB4 expression level and aberrant expression of multiple DDR-associated proteins. These results suggest that definition of specific DNA repair and checkpoint defects in subgroups of triple negative cancer might identify new treatment targets. Expression of Wwox and its interactor, ErbB4, was highly significantly reduced in metastatic tissues vs. matched primary tissues, suggesting that Wwox signal pathway loss contributes to lymph node metastasis, perhaps by allowing survival of tumor cells that have detached from basement membranes, as proposed for the role of Wwox in ovarian cancer spread.

Triple-negative breast cancers: unique clinical presentations and outcomes

BACKGROUND

Triple-negative (TN) breast cancers lack estrogen receptor (ER), progesterone receptor (PR), and HER2/neu amplification (HER2). Few studies have been dedicated to characterizing this subset of cancer.

MATERIALS AND METHODS

Retrospective review of a prospectively collected database of patients treated for invasive breast cancer at a single institution. Three tumor marker groups were compared: TN [ER-/PR-/HER2-], HER2+ [ERx/PRx/HER2+], and ER+ [ER+/PRx/HER2-].

RESULTS

Over 8 years, 123 TN, 210 HER2+, and 728 ER+ patients were identified. On average, TN patients were younger (mean age TN 59.7, HER2+ 62.0, ER+ 64.5 years, P = 0.0001). They were referred for genetic testing more frequently (17% TN, 10% HER2+, 10% ER+, P = 0.055) and were most likely to have a BRCA mutation identified if tested (24% TN, 10% HER2+, 4% ER+, P = 0.019). TN tumors were larger (mean size 2.1 cm TN, 2.0 cm HER2+, 1.8 cm ER+, P = 0.031) and most commonly detected by breast exam (54% TN, 43% HER2+, 42% ER+, P = 0.025). Lymph node involvement was least common with TN tumors (21% TN, 37% HER2+, 32% ER+, P = 0.013), and angiolymphatic invasion was less common for TN than HER2+ (18% TN, 24% HER2+, 15% ER+, P = 0.006). TN patients had significantly higher local or regional recurrence (5.7% TN, 2.9% HER2+, 1.0% ER+, P = 0.001), and the worst 5-year overall survival, although this did not reach statistical significance (85% ± 6% TN, 94% ± 2% HER2+, 91% ± 2% ER+).

CONCLUSIONS

TN breast cancers are associated with unique patient presentations, tumor characteristics, and clinical outcomes of which clinicians and investigators should be aware.

Clinicopathological features and treatment strategy for triple-negative breast cancer

Breast cancers are divided into at least 4 subtypes on the basis of gene expression profiles and expression of receptors (hormone receptors (HR) and HER2) as measured by immunohistochemistry. These subtypes have different prognoses and responses to treatments such as endocrine manipulation, anti-HER2 therapy, and chemotherapy. Triple-negative breast cancer (TNBC) is immunohistochemically defined as lacking estrogen and progesterone receptors and not overexpressing HER2. TNBC accounts for approximately 15% of breast cancer patients, and is more chemosensitive but has a worse prognosis than the HR-positive/HER2-negative phenotype. TNBC is a heterogeneous disease that does not offer specific targets in the same way as HR-positive and HER2-positive breast cancers, and is similar to basal-like breast cancer and BRCA1-related breast cancer. At present, the lack of highly effective therapeutic targets for TNBC leaves standard chemotherapy, for example the combination of anthracycline and taxane, as the only medical treatment, but this is insufficiently efficacious. Novel approaches for TNBC, for example DNA damaging agents, PARP-1 inhibitors, receptor tyrosin kinase inhibitors (TKIs), and antiangiogenesis agents, have been examined in clinical settings. Concerning therapeutic strategies for TNBC, it is most important to develop novel effective approaches for TNBC treatment and high-throughput predictive tools for standard chemotherapy and novel agents.

Biomarkers for Basal-like Breast Cancer

Initially recognized through microarray-based gene expression profiling, basal-like breast cancer, for which we lack effective targeted therapies, is an aggressive form of carcinoma with a predilection for younger women. With some success, immunohistochemical studies have attempted to reproduce the expression profile classification of breast cancer through identification of subtype-specific biomarkers. This review aims to present an in depth summary and analysis of the current status of basal-like breast cancer biomarker research. While a number of biomarkers show promise for future clinical application, the next logical step is a comprehensive investigation of all biomarkers against a gene expression profile gold standard for breast cancer subtype assignment.

Use of ER/PR/HER2 subtypes in conjunction with the 2007 St Gallen Consensus Statement for early breast cancer

Background

The 2007 St Gallen international expert consensus statement describes three risk categories and provides recommendations for treatment of early breast cancer. The set of recommendations on how to best treat primary breast cancer is recognized and used by clinicians worldwide. We now examine the variability of five-year survival of the 2007 St Gallen Risk Classifications utilizing the ER/PR/HER2 subtypes.

Methods

Using the population-based California Cancer Registry, 114,786 incident cases of Stages 1-3 invasive breast cancer diagnosed between 2000 and 2006 were identified. Cases were assigned to Low, Intermediate, or High Risk categories. Five-year-relative survival was computed for the three St Gallen risk categories and for the ER/PR/HER2 subtypes for further differentiation.

Results and Discussion

There were 9,124 (13%) cases classified as Low Risk, 44,234 (65%) cases as Intermediate Risk, and 14,340 (21%) as High Risk. Within the Intermediate Risk group, 33,735 (76%) were node-negative (Intermediate Risk 2) and 10,499 (24%) were node-positive (Intermediate Risk 3). For the High Risk group, 6,149 (43%) had 1 to 3 positive axillary lymph nodes (High Risk 4) and 8,191 (57%) had four or more positive lymph nodes (High Risk 5).

Using five-year relative survival as the principal criterion, we found the following: a) There was very little difference between the Low Risk and Intermediate Risk categories; b) Use of the ER/PR/HER2 subtypes within the Intermediate and High Risk categories separated each into a group with better five-year survival (ER-positive) and a group with worse survival (ER-negative), irrespective of HER2-status; c) The heterogeneity of the High Risk category was most evident when one examined the ER/PR/HER2 subtypes with four or more positive axillary lymph nodes; (d) HER2-positivity did not always translate to worse survival, as noted when one compared the triple positive subtype (ER+/PR+/HER2+) to the triple negative subtype (ER-/PR-/HER2-); and (e) ER-negativity appeared to be a stronger predictor of poor survival than HER2-positivity.

Conclusion

The use of ER/PR/HER2 subtype highlights the marked heterogeneity of the Intermediate and High Risk categories of the 2007 St Gallen statements. The use of ER/PR/HER2 subtypes and correlation with molecular classification of breast cancer is recommended.