Evolution of chromosome-arm aberrations in breast cancer through genetic network rewiring.

The basal breast cancer subtype is enriched for triple-negative breast cancer (TNBC) and displays consistent large chromosomal deletions. Here, we characterize evolution and maintenance of chromosome 4p (chr4p) loss in basal breast cancer. Analysis of The Cancer Genome Atlas data shows recurrent deletion of chr4p in basal breast cancer. Phylogenetic analysis of a panel of 23 primary tumor/patient-derived xenograft basal breast cancers reveals early evolution of chr4p deletion. Mechanistically we show that chr4p loss is associated with enhanced proliferation. Gene function studies identify an unknown gene, C4orf19, within chr4p, which suppresses proliferation when overexpressed-a member of the PDCD10-GCKIII kinase module we name PGCKA1. Genome-wide pooled overexpression screens using a barcoded library of human open reading frames identify chromosomal regions, including chr4p, that suppress proliferation when overexpressed in a context-dependent manner, implicating network interactions. Together, these results shed light on the early emergence of complex aneuploid karyotypes involving chr4p and adaptive landscapes shaping breast cancer genomes.

In situ Raman spectroscopy and machine learning unveil biomolecular alterations in invasive breast cancer.

Significance: As many as 60% of patients with early stage breast cancer undergo breast-conserving surgery. Of those, 20% to 35% need a second surgery because of incomplete resection of the lesions. A technology allowing in situ detection of cancer could reduce re-excision procedure rates and improve patient survival. Aim: Raman spectroscopy was used to measure the spectral fingerprint of normal breast and cancer tissue ex-vivo. The aim was to build a machine learning model and to identify the biomolecular bands that allow one to detect invasive breast cancer. Approach: The system was used to interrogate specimens from 20 patients undergoing lumpectomy, mastectomy, or breast reduction surgery. This resulted in 238 ex-vivo measurements spatially registered with standard histology classifying tissue as cancer, normal, or fat. A technique based on support vector machines led to the development of predictive models, and their performance was quantified using a receiver-operating-characteristic analysis. Results: Raman spectroscopy combined with machine learning detected normal breast from ductal or lobular invasive cancer with a sensitivity of 93% and a specificity of 95%. This was achieved using a model based on only two spectral bands, including the peaks associated with C-C stretching of proteins around 940 cm - 1 and the symmetric ring breathing at 1004 cm - 1 associated with phenylalanine. Conclusions: Detection of cancer on the margins of surgically resected breast specimen is feasible with Raman spectroscopy.

Improved platform for breast cancer circulating tumor cell enrichment and characterization with next-generation sequencing technology.

Circulating tumor cells (CTCs) represent cells shed from the primary tumor or metastatic sites and can be used to monitor treatment response and tumor recurrence. However, CTCs circulate in extremely low numbers making in-depth analysis beyond simple enumeration challenging when collected from peripheral blood. Furthermore, tumor heterogeneity, a hallmark of many tumors, especially breast cancer, further complicates CTC characterization. To overcome this limitation, we developed a platform based on the large-scale isolation of CTCs by apheresis, allowing us to collect CTCs in large numbers, which were preserved live in liquid nitrogen for further characterization. Flow cytometry followed by cell sorting (FACS) was performed using a combination of antibodies directed against cell surface markers of white blood cells (CD45) and epithelial tumor cells (CK8). Analysis of subpopulations CD45+/- and CK8+/- by bulk RNA sequencing (RNAseq) and the CD45-/CK8 positive population by single-cell RNAseq was performed. The CD45- population was enriched using CD45 magnetic beads separation and examined by IHC for pan-cytokeratin and immunofluorescence (IF) for specific markers, including the elusive circulating cancer stem cells (CSCs). CSC-rich mammospheres were grown in vitro for further analysis and treated to examine their response to chemotherapeutic agents. Finally, mammospheres were transplanted into the mammary fat pad and bone of immunodeficient mice to examine tumor growth in vivo. This platform enables the detection and collection of CTCs in early and late-stage breast cancer patients of every subtype. Markers including CD44/24, ALDH1 and CXCR4 were identified by IF and showed high expression following mammosphere culture, which responded predictably to chemotherapeutic agents. Mammospheres were also transplanted into nude mice and induced tumors in the mammary fat pad and bone following intra-tibial transplantation. Finally, bulk RNA analysis of the FACS isolated CD45+/- and CK8+/- cells showed a clear separation of CD45- away from CD45+ populations. Single-cell RNAseq of the FACS isolated CD45-/CK8+ cells showed the presence of 4-5 clusters, confirming the high degree of heterogeneity of CTCs. Our platform for large-scale isolation of CTCs using apheresis is suitable for an in-depth analysis of the cancer phenotype and may eventually allow evaluation in real-time of the disease process to optimize cancer regimens.

Intra-Tumoral CD8+ T-Cell Infiltration and PD-L1 Positivity in Homologous Recombination Deficient Pancreatic Ductal Adenocarcinoma.

The immune contexture of pancreatic ductal adenocarcinoma (PDAC) is generally immunosuppressive. A role for immune checkpoint inhibitors (ICIs) in PDAC has only been demonstrated for the rare and hypermutated mismatch repair (MMR) deficient (MMR-d) subtype. Homologous recombination repair (HR) deficient (HR-d) PDAC is more prevalent and may encompass up to 20% of PDAC. Its genomic instability may promote a T-cell mediated anti-tumor response with therapeutic sensitivity to ICIs. To investigate the immunogenicity of HR-d PDAC, we used multiplex immunohistochemistry (IHC) to compare the density and spatial distribution of CD8+ cytotoxic T-cells, FOXP3+ regulatory T-cells (Tregs), and CD68+ tumor-associated macrophages (TAMs) in HR-d versus HR/MMR-intact PDAC. We also evaluated the IHC positivity of programmed death-ligand 1 (PD-L1) across the subgroups. 192 tumors were evaluated and classified as HR/MMR-intact (n=166), HR-d (n=25) or MMR-d (n=1) based on germline testing and tumor molecular hallmarks. Intra-tumoral CD8+ T-cell infiltration was higher in HR-d versus HR/MMR-intact PDAC (p<0.0001), while CD8+ T-cell densities in the peri-tumoral and stromal regions were similar in both groups. HR-d PDAC also displayed increased intra-tumoral FOXP3+ Tregs (p=0.049) and had a higher CD8+:FOXP3+ ratio (p=0.023). CD68+ TAM expression was similar in HR-d and HR/MMR-intact PDAC. Finally, 6 of the 25 HR-d cases showed a PD-L1 Combined Positive Score of >=1, whereas none of the HR/MMR-intact cases met this threshold (p<0.00001). These results provide immunohistochemical evidence for intra-tumoral CD8+ T-cell enrichment and PD-L1 positivity in HR-d PDAC, suggesting that HR-d PDAC may be amenable to ICI treatment strategies.

Claudin-2 promotes colorectal cancer liver metastasis and is a biomarker of the replacement type growth pattern.

Claudin-2 promotes breast cancer liver metastasis by enabling seeding and early cancer cell survival. We now demonstrate that Claudin-2 is functionally required for colorectal cancer liver metastasis and that Claudin-2 expression in primary colorectal cancers is associated with poor overall and liver metastasis-free survival. We have examined the role of Claudin-2, and other claudin family members, as potential prognostic biomarkers of the desmoplastic and replacement histopathological growth pattern associated with colorectal cancer liver metastases. Immunohistochemical analysis revealed higher Claudin-2 levels in replacement type metastases when compared to those with desmoplastic features. In contrast, Claudin-8 was highly expressed in desmoplastic colorectal cancer liver metastases. Similar observations were made following immunohistochemical staining of patient-derived xenografts (PDXs) that we have established, which faithfully retain the histopathology of desmoplastic or replacement type colorectal cancer liver metastases. We provide evidence that Claudin-2 status in patient-derived extracellular vesicles may serve as a relevant prognostic biomarker to predict whether colorectal cancer patients have developed replacement type liver metastases. Such a biomarker will be a valuable tool in designing optimal treatment strategies to better manage patients with colorectal cancer liver metastases.

Epithelial-Myoepithelial Carcinoma of the Breast with Rhabdoid Features.

Epithelial-myoepithelial carcinoma of the breast is a rare biphasic tumor composed of intermixed malignant epithelial and myoepithelial components. Myoepithelial cells are known to adopt varied morphologies, including spindle, chondroid, clear cell, and rhabdoid morphologies, and can represent a diagnostic challenge when isolated on biopsy. Rhabdomyosarcoma, phyllodes tumor, metaplastic carcinoma, and myoepithelial carcinoma are primary breast tumors that all have been shown to exhibit rhabdoid features, whether representing true differentiation or morphological mimic. We here report an epithelial-myoepithelial carcinoma of the breast with rhabdoid features in a 76-year-old woman. The rhabdoid-appearing myoepithelial cells are negative for myogenin, consistent with a rhabdoid-like morphology rather than a true rhabdoid differentiation, comparably to previously described myoepithelial carcinoma with rhabdoid features. To our knowledge, this is the first reported case of epithelial-myoepithelial carcinoma of the breast with rhabdoid features and thus adds another entity to the differential diagnosis of breast lesions with rhabdoid features.

Predicting Relapse in Patients With Triple Negative Breast Cancer (TNBC) Using a Deep-Learning Approach.

The abundance and/or location of tumor infiltrating lymphocytes (TILs), especially CD8+ T cells, in solid tumors can serve as a prognostic indicator in various types of cancer. However, it is often difficult to select an appropriate threshold value in order to stratify patients into well-defined risk groups. It is also important to select appropriate tumor regions to quantify the abundance of TILs. On the other hand, machine-learning approaches can stratify patients in an unbiased and automatic fashion. Based on immunofluorescence (IF) images of CD8+ T lymphocytes and cancer cells, we develop a machine-learning approach which can predict the risk of relapse for patients with Triple Negative Breast Cancer (TNBC). Tumor-section images from 9 patients with poor outcome and 15 patients with good outcome were used as a training set. Tumor-section images of 29 patients in an independent cohort were used to test the predictive power of our algorithm. In the test cohort, 6 (out of 29) patients who belong to the poor-outcome group were all correctly identified by our algorithm; for the 23 (out of 29) patients who belong to the good-outcome group, 17 were correctly predicted with some evidence that improvement is possible if other measures, such as the grade of tumors, are factored in. Our approach does not involve arbitrarily defined metrics and can be applied to other types of cancer in which the abundance/location of CD8+ T lymphocytes/other types of cells is an indicator of prognosis.

Chemogenomic profiling of breast cancer patient-derived xenografts reveals targetable vulnerabilities for difficult-to-treat tumors.

Subsets of breast tumors present major clinical challenges, including triple-negative, metastatic/recurrent disease and rare histologies. Here, we developed 37 patient-derived xenografts (PDX) from these difficult-to-treat cancers to interrogate their molecular composition and functional biology. Whole-genome and transcriptome sequencing and reverse-phase protein arrays revealed that PDXs conserve the molecular landscape of their corresponding patient tumors. Metastatic potential varied between PDXs, where low-penetrance lung micrometastases were most common, though a subset of models displayed high rates of dissemination in organotropic or diffuse patterns consistent with what was observed clinically. Chemosensitivity profiling was performed in vivo with standard-of-care agents, where multi-drug chemoresistance was retained upon xenotransplantation. Consolidating chemogenomic data identified actionable features in the majority of PDXs, and marked regressions were observed in a subset that was evaluated in vivo. Together, this clinically-annotated PDX library with comprehensive molecular and phenotypic profiling serves as a resource for preclinical studies on difficult-to-treat breast tumors.

Ovarian Mixed Malignant Brenner-Mucinous Tumor with Signet Ring Cells.

Mucinous carcinomas with signet ring cells in the ovary, particularly those composed predominantly of signet ring cells, are extremely rare, and in vast majority of cases, they represent metastasis from another site such as the stomach, appendix, pancreaticobiliary tract, bladder, and breast (Hristov et al., 2007, Kiyokawa et al., 2006, Vang et al., 2006, Young, 2006). Malignant Brenner tumor is also rare comprising less than 0.5% of ovarian carcinoma. Although mixed Brenner-Mucinous tumors are relatively common, the combination of a primary ovarian signet ring carcinoma with a malignant Brenner tumor is unique and to the best of our knowledge not previously reported in the literature.

PTHrP, A Biomarker for CNS Metastasis in Triple-Negative Breast Cancer and Selection for Adjuvant Chemotherapy in Node-Negative Disease.

BACKGROUND: Triple-negative breast cancer (TNBC) is characterized by poor prognosis and lack of targeted therapies and biomarkers to guide decisions on adjuvant chemotherapy. Parathyroid hormone-related protein (PTHrP) is frequently overexpressed in breast cancer and involved in proliferation and metastasis, two hallmarks of poor prognosis for node-negative breast cancer. We investigated the prognostic value of PTHrP with respect to organ-specific metastasis and nodal status in TNBC. METHODS: We assessed PTHrP expression using immunohistochemistry in a clinically annotated tissue microarray for a population-based study of 314 patients newly diagnosed with TNBC, then analyzed its correlation to progression and survival using Kaplan-Meier and Cox regression analyses. The Cancer Genome Atlas (TCGA) validation analysis was performed through Bioconductor. All statistical tests were two-sided. RESULTS: PTHrP overexpression (160 of 290 scorable cases, 55.2%) was statistically significantly associated in univariate analysis with decreased overall survival (OS) in our cohort (P = .0055) and The Cancer Genome Atlas (P = .0018) and decreased central nervous system (CNS)-progression-free survival (P = .0029). In multivariate analysis, PTHrP was a statistically significant independent prognostic factor for CNS-progression-free survival in TNBC (hazard ratio [HR] = 5.014, 95% confidence interval [CI] = 1.421 to 17.692, P = .0122) and for OS selectively in node-negative TNBC (HR = 2.423, 95% CI = 1.129 to 5.197, P = .0231). Strikingly, PTHrP emerged as the only statistically significant prognostic factor (HR = 2.576, 95% CI = 1.019 to 6.513, P = .0456) for OS of low-clinical risk node-negative patients who did not receive adjuvant chemotherapy. CONCLUSIONS: PTHrP is a novel independent prognostic factor for CNS metastasis and adjuvant chemotherapy selection of low-clinical risk node-negative TNBC. Its predictive value needs to be prospectively assessed in clinical trials.

Value of Shear Wave Elastography for the Differentiation of Benign and Malignant Microcalcifications of the Breast.

OBJECTIVE. The objective of our study was to evaluate whether shear wave elastography (SWE) can differentiate benign from malignant microcalcifications of the breast when detected on ultrasound (US). SUBJECTS AND METHODS. Between February 9, and June 23, 2016, 74 patients with mammographically detected suspicious microcalcifications underwent breast US. When microcalcifications were identified on US, stiffness was assessed using SWE. Biopsy was subsequently performed under US guidance using a 10-gauge vacuum-assisted needle. Qualitative and quantitative elastography results were compared between benign and malignant calcifications as well as between pure ductal carcinoma in situ and lesions with invasive components using the Mann-Whitney U test. ROC curves were created to assess the performance of SWE in detecting malignancy and invasive components. RESULTS. Twenty-nine groups of microcalcifications in 29 patients were identified on US. At pathology, 16 groups were benign and 13 were malignant. Stiffness of malignant calcifications was significantly higher than that of the benign ones (p = 0.0004). The AUC, sensitivity, specificity, negative predictive value, positive predictive value, and accuracy of SWE for the diagnosis of malignancy were 0.89, 69%, 100%, 80%, 100%, and 86%, respectively, and for detection of an invasive component were 0.93, 75%, 100%, 75%, 100%, and 85%. CONCLUSION. SWE has the potential to differentiate benign from malignant micro-calcifications of the breast when detected on US with high specificity.

Spatially distinct tumor immune microenvironments stratify triple-negative breast cancers.

Understanding the tumor immune microenvironment (TIME) promises to be key for optimal cancer therapy, especially in triple-negative breast cancer (TNBC). Integrating spatial resolution of immune cells with laser capture microdissection gene expression profiles, we defined distinct TIME stratification in TNBC, with implications for current therapies including immune checkpoint blockade. TNBCs with an immunoreactive microenvironment exhibited tumoral infiltration of granzyme B+CD8+ T cells (GzmB+CD8+ T cells), a type 1 IFN signature, and elevated expression of multiple immune inhibitory molecules including indoleamine 2,3-dioxygenase (IDO) and programmed cell death ligand 1 (PD-L1), and resulted in good outcomes. An "immune-cold" microenvironment with an absence of tumoral CD8+ T cells was defined by elevated expression of the immunosuppressive marker B7-H4, signatures of fibrotic stroma, and poor outcomes. A distinct poor-outcome immunomodulatory microenvironment, hitherto poorly characterized, exhibited stromal restriction of CD8+ T cells, stromal expression of PD-L1, and enrichment for signatures of cholesterol biosynthesis. Metasignatures defining these TIME subtypes allowed us to stratify TNBCs, predict outcomes, and identify potential therapeutic targets for TNBC.

Infiltration of CD8+ T cells into tumor cell clusters in triple-negative breast cancer.

Infiltration of [Formula: see text] T lymphocytes into solid tumors is associated with good prognosis in various types of cancer, including triple-negative breast cancer (TNBC). However, the mechanisms underlying different infiltration levels are largely unknown. Here, we have characterized the spatial profile of [Formula: see text] T cells around tumor cell clusters (tightly connected tumor cells) in the core and margin regions in TNBC patient samples. We found that in some patients, the [Formula: see text] T cell density first decreases when moving in from the boundary of the tumor cell clusters and then rises again when approaching the center. To explain various infiltration profiles, we modeled the dynamics of T cell density via partial differential equations. We spatially modulated the diffusion/chemotactic coefficients of T cells (to mimic physical barriers) or introduced the localized secretion of a diffusing T cell chemorepellent. Combining the spatial-profile analysis and the modeling led to support for the second idea; i.e., there exists a possible chemorepellent inside tumor cell clusters, which prevents [Formula: see text] T cells from infiltrating into tumor cell clusters. This conclusion was consistent with an investigation into the properties of collagen fibers which suggested that variations in desmoplastic elements does not limit infiltration of [Formula: see text] T lymphocytes, as we did not observe significant correlations between the level of T cell infiltration and fiber properties. Our work provides evidence that [Formula: see text] T cells can cross typical fibrotic barriers and thus their infiltration into tumor clusters is governed by other mechanisms possibly involving a local repellent.

Afadin cooperates with Claudin-2 to promote breast cancer metastasis.

Claudin-2 promotes breast cancer liver metastasis by enabling seeding and early cancer cell survival. We now demonstrate that the PDZ-binding motif of Claudin-2 is necessary for anchorage-independent growth of cancer cells and is required for liver metastasis. Several PDZ domain-containing proteins were identified that interact with the PDZ-binding motif of Claudin-2 in liver metastatic breast cancer cells, including Afadin, Arhgap21, Pdlim2, Pdlim7, Rims2, Scrib, and ZO-1. We specifically examined the role of Afadin as a potential Claudin-2-interacting partner that promotes breast cancer liver metastasis. Afadin associates with Claudin-2, an interaction that requires the PDZ-binding motif of Claudin-2. Loss of Afadin also impairs the ability of breast cancer cells to form colonies in soft agar and metastasize to the lungs or liver. Immunohistochemical analysis of Claudin-2 and/or Afadin expression in 206 metastatic breast cancer tumors revealed that high levels of both Claudin-2 and Afadin in primary tumors were associated with poor disease-specific survival, relapse-free survival, lung-specific relapse, and liver-specific relapse. Our findings indicate that signaling downstream from a Claudin-2/Afadin complex enables the efficient formation of breast cancer metastases. Moreover, combining Claudin-2 and Afadin as prognostic markers better predicts the potential of breast cancer to metastasize to soft tissues.

Imaging features of pure and mixed forms of mucinous breast carcinoma with histopathological correlation.

METHODS:: A cross-sectional study identified cases of mucinous breast carcinoma from pathology records (2004-2012). Two radiologists classified imaging features by consensus and two pathologists classified cases into pure or mixed subtypes. Bi-variable analyses were performed using relevant statistical tests. RESULTS:: We identified 80 lesions in 77 female patients (median age 65 years, range 29-88): 58 lesions on mammograhy, 72 on ultrasound, and 25 on MRI. Statistically significant findings (p < 0.05) are as follows. On mammography, tumour margins tended to be indistinct (12, 48%) and spiculated (11, 44%) for pure and mixed lesions, respectively. Pure mucinous masses were less microcalcified (23, 77%) and mixed masses equally so. On ultrasound, pure tumours tended towards an irregular or oval shape (44, 42%) with mixed tumours having an irregular shape (78%). More pure tumours (53%) had posterior acoustic enhancement than mixed lesions (33%), and all pure tumours lacked posterior acoustic shadowing. Pure lesions had a heterogeneous echo pattern more than mixed tumours (78% vs 39%). On MRI, pure tumours tended towards a persistent kinetic curve (42%) whereas mixed tumours predominantly had a washout pattern (75%). Most pure tumours were T2 hyperintense (83%) whereas mixed lesions were T2 isointense or hyperintense (61%, 23%), respectively. CONCLUSION:: An analysis of imaging features can help to infer underlying histology of pure and mixed forms of mucinous breast carcinoma. ADVANCES IN KNOWLEDGE:: Pure mucinous carcinomas present less suspicious imaging features than mixed mucinous carcinomas and could be mistaken for non malignant lesions. An imaging analysis of mucinous breast carcinoma can help infer their underlying histology.

Evaluating the Impact of Breast Density on Preoperative MRI in Invasive Lobular Carcinoma.

BACKGROUND: The focus of this study was to assess the accuracy of breast MRI in predicting pathologic tumor size in invasive lobular carcinoma (ILC) and to evaluate the incidence and factors associated with the detection of additional MRI lesions in ILC patients. STUDY DESIGN: We retrospectively reviewed data from patients with stage I to III ILC diagnosed between 2010 and 2016 at our institution. Univariable and multivariable logistic regression were used to determine factors associated with detection of additional suspicious lesions on MRI. RESULTS: The cohort included 99 women with ILC who underwent preoperative MRI, with a median age of 61 years (range 35 to 80 years). The sensitivity of MRI for detecting invasive lobular carcinoma was 99%, higher than that of mammography (68%) and ultrasound (92%). Mammography and ultrasound had a tendency to underestimate ILC, and MRI estimates of final tumor size were concordant in the majority (58.6%) of cases, with a median discordance of -2 mm. Magnetic resonance imaging detected additional ipsilateral malignancy in 23.2%, occult contralateral disease in 3.0%, and altered surgical management in 29.3% of ILC cases. In multivariable analyses, factors significantly associated with additional suspicious findings on MRI included higher breast density (odds ratio 3.19; 95% CI 1.01 to 10.0) and lymph node-positive disease (odds ratio 4.02; 95% CI 0.96 to 16.9). CONCLUSIONS: Preoperative MRI is a useful adjunct to conventional breast imaging in ILC, particularly in women with dense breast tissue.

Reflex Testing for Germline BRCA1, BRCA2, PALB2, and ATM Mutations in Pancreatic Cancer: Mutation Prevalence and Clinical Outcomes From Two Canadian Research Registries.

PURPOSE: We investigated the translational value of reflex testing for germline mutations in four homology-directed DNA repair predisposition genes (BRCA1, BRCA2, PALB2, and ATM) in consecutive patients with pancreatic adenocarcinoma. METHODS: One hundred fifty patients with French-Canadian (FC) ancestry were evaluated for founder mutations, and 114 patients were subsequently assessed by full gene sequencing and multiplex ligation-dependent probe amplification for nonfounder mutations. Two hundred thirty-six patients unselected for ancestry were also assessed for mutations by full gene sequencing. RESULTS: The FC founder mutation prevalence among the 150 patients was 5.3% (95% CI, 2.6% to 10.3%), and the nonfounder mutation prevalence across the four genes among the 114 patients tested was 2.6% (95% CI, 0.6% to 7.8%). In the case series unselected for ancestry, 10.0% (95% CI, 2.7% to 26.4%) of patients reporting Ashkenazi Jewish (AJ) ancestry carried an AJ founder mutation, with no nonfounder mutations identified. The mutation prevalence among patients without FC/AJ ancestry was 4.9% (95% CI, 2.6% to 8.8%). Mutations were more frequent in patients diagnosed at ≤ 50 years of age (P = .03) and in patients with either two or more first- or second-degree relatives with pancreas, breast, ovarian or prostate cancer, or one such relative and a second primary of one of these cancer types (P < .001). BRCA1, BRCA2, and PALB2 carriers with late-stage (III or IV) disease had an overall survival advantage (P = .049), particularly if treated with platinum-based chemotherapies (P = .030). CONCLUSION: Considering these results, we recommend reflex founder mutation testing of patients with FC/AJ ancestry and full gene sequencing of patients who are ≤ 50 years or meet the identified family history criteria. Reflex testing of all incident patients for these four genes may become justified as full gene sequencing costs decline.

Features from Computerized Texture Analysis of Breast Cancers at Pretreatment MR Imaging Are Associated with Response to Neoadjuvant Chemotherapy.

Purpose To evaluate whether features from texture analysis of breast cancers were associated with pathologic complete response (pCR) after neoadjuvant chemotherapy and to explore the association between texture features and tumor subtypes at pretreatment magnetic resonance (MR) imaging. Materials and Methods Institutional review board approval was obtained. This retrospective study included 85 patients with 85 breast cancers who underwent breast MR imaging before neoadjuvant chemotherapy between April 10, 2008, and March 12, 2015. Two-dimensional texture analysis was performed by using software at T2-weighted MR imaging and contrast material-enhanced T1-weighted MR imaging. Quantitative parameters were compared between patients with pCR and those with non-pCR and between patients with triple-negative breast cancer and those with non-triple-negative cancer. Multiple logistic regression analysis was used to determine independent parameters. Results Eighteen tumors (22%) were triple-negative breast cancers. pCR was achieved in 30 of the 85 tumors (35%). At univariate analysis, mean pixel intensity with spatial scaling factor (SSF) of 2 and 4 on T2-weighted images and kurtosis on contrast-enhanced T1-weighted images showed a significant difference between triple-negative breast cancer and non-triple-negative breast cancer (P = .009, .003, and .001, respectively). Kurtosis (SSF, 2) on T2-weighted images showed a significant difference between pCR and non-pCR (P = .015). At multiple logistic regression, kurtosis on T2-weighted images was independently associated with pCR in non-triple-negative breast cancer (P = .033). A multivariate model incorporating T2-weighted and contrast-enhanced T1-weighted kurtosis showed good performance for the identification of triple-negative breast cancer (area under the receiver operating characteristic curve, 0.834). Conclusion At pretreatment MR imaging, kurtosis appears to be associated with pCR to neoadjuvant chemotherapy in non-triple-negative breast cancer and may be a promising biomarker for the identification of triple-negative breast cancer. © RSNA, 2017.

A Targetable EGFR-Dependent Tumor-Initiating Program in Breast Cancer.

Therapies targeting epidermal growth factor receptor (EGFR) have variable and unpredictable responses in breast cancer. Screening triple-negative breast cancer (TNBC) patient-derived xenografts (PDXs), we identify a subset responsive to EGFR inhibition by gefitinib, which displays heterogeneous expression of wild-type EGFR. Deep single-cell RNA sequencing of 3,500 cells from an exceptional responder identified subpopulations displaying distinct biological features, where elevated EGFR expression was significantly enriched in a mesenchymal/stem-like cellular cluster. Sorted EGFRhi subpopulations exhibited enhanced stem-like features, including ALDH activity, sphere-forming efficiency, and tumorigenic and metastatic potential. EGFRhi cells gave rise to EGFRhi and EGFRlo cells in primary and metastatic tumors, demonstrating an EGFR-dependent expansion and hierarchical state transition. Similar tumorigenic EGFRhi subpopulations were identified in independent PDXs, where heterogeneous EGFR expression correlated with gefitinib sensitivity. This provides new understanding for an EGFR-dependent hierarchy in TNBC and for patient stratification for therapeutic intervention.

Progressive polarity loss and luminal collapse disrupt tissue organization in carcinoma.

Epithelial cancers (carcinoma) account for 80%-90% of all cancers. The development of carcinoma is associated with disrupted epithelial organization and solid ductal structures. The mechanisms underlying the morphological development of carcinoma are poorly understood, but it is thought that loss of cell polarity is an early event. Here we report the characterization of the development of human breast lesions leading to carcinoma. We identified a unique mechanism that generates solid ducts in carcinoma through progressive loss of polarity and collapse of the luminal architecture. This program initiates with asymmetric divisions of polarized cells that generate a stratified epithelium containing both polarized and depolarized cells. Stratified regions form cords that penetrate into the lumen, subdividing it into polarized secondary lumina. The secondary lumina then collapse with a concomitant decrease in RhoA and myosin II activity at the apical membrane and ultimately lose apical-basal polarity. By restoring RhoA activity in mice, ducts maintained lumen and cell polarity. Notably, disrupted tissue architecture through luminal collapse was reversible, and ducts with a lumen were re-established after oncogene suppression in vivo. This reveals a novel and common mechanism that contributes to carcinoma development by progressively disrupting cell and tissue organization.