E-cadherin clone 36 nuclear staining dictates adverse disease outcome in lobular breast cancer patients

Clinicopathological Characteristics of a Distinct Tumor Phenotype: Invasive Lobular Carcinoma With Tubular Elements in the West German Study Group ADAPTcycle Trial

Invasive lobular carcinoma with tubular elements (ILC-TE) is a recently identified variant of invasive lobular breast carcinoma (ILC). The histology of ILC-TE is defined by noncohesive carcinoma cells mixed with cohesive tubular elements and complete loss of epithelial (E)-cadherin. Cell-cell adhesion is partially restored by switching from an E-cadherin-deficient to a placental (P)-cadherin-proficient status (EPS). The prevalence of ILC-TE remains unknown. Here, we report data from the central pathology review of >4500 hormone receptor-positive/HER2-negative breast cancer (BC) cases recruited to the West German Study Group (WSG) ADAPTcycle trial (NCT04055493). The central pathology review included prospective assessment of BC types, variants, and E-cadherin expression. Cases classified as ILC-TE were analyzed for their molecular features and clinicopathological characteristics. Pure ILC with complete loss of E-cadherin accounted for 630 of 4619 (13.6%) BC cases. ILC-TE accounted for 47 of 630 (7.5%) lobular carcinomas, making it more than twice as prevalent as mixed BC (NST/ILC). ILC-TE harbored deleterious CDH1/E-cadherin mutations in 27 of 35 (77%) cases tested. EPS was detected in 43 of 47 (91%) ILC-TE cases. EPS was significantly more common in ILC-TE than in classic ILC or other ILC variants (P < .001). Clinically, ILC-TE was associated with cT1 stage (P = .023), cN0 status (P = .024), lower histologic grade (P = .004), and lower Ki67 (P = .012). In contrast, solid ILC was associated with higher Ki67 (P = .006). Following preoperative endocrine therapy, higher post-preoperative endocrine therapy Ki67 levels were observed in trabecular ILC, solid-papillary ILC, and pleomorphic ILC (P < .001, P = .006, and P = .021, respectively). In summary, ILC-TE is a quite common ILC variant that is associated with EPS, less-aggressive clinical features, and slow growth.

Comprehensive characterization of invasive mammary carcinoma with lobular features: integrating morphology and E-cadherin immunohistochemistry patterns

BACKGROUND

Breast cancer treatment prioritizes molecular subtypes over histologic types. However, considering the unique biological behavior of invasive lobular carcinoma (ILC), its diagnosis is crucial for patient management. Therefore, this study aimed to review breast cancer cases, focusing on the E-cadherin patterns and lobular morphology of cases misclassified in the original reports.

METHODS

A comprehensive review was conducted on 481 breast cancer biopsy cases diagnosed as invasive breast carcinoma of no special type (IBC-NST) or ILC with E-cadherin staining. These cases were categorized into six groups based on tumor morphology (ductal/lobular) and E-cadherin expression pattern (membranous/loss/aberrant): (1) ductal/membranous, (2) lobular/loss, (3) lobular/aberrant, (4) mixed, (5) ductal/loss or aberrant, and (6) lobular/membranous.

RESULTS

In 211 cases (43.8%), an E-cadherin pattern indicating ILC (loss and aberrant) was observed alongside lobular morphology, representing 5.52% of all breast cancer biopsies during the relevant period. Moreover, 181 cases (37.6%) showed a membranous pattern with ductal morphology, 4 (0.8%) were mixed IBC-NST and ILC, and 85 (17.7%) exhibited discordance between morphology and E-cadherin expression. Notably, only 25.9% (15/58) of cases in group 3, characterized by aberrant E-cadherin patterns, were initially diagnosed as ILC, highlighting a significant diagnostic discrepancy. In group 6, where membranous E-cadherin pattern was present with lobular morphology, only 3.4% (2/58) were diagnosed as ILC in the original reports, indicating diagnostic challenges in morphology and immunohistochemistry discordance. Similarly, in group 5, which had ductal morphology with loss or aberrant E-cadherin expression, the initial diagnosis rate of IBC-NST was 33.3% (9/27), reflecting the complexities in interpreting discordant cases.

CONCLUSIONS

In real-world practice, diagnosing ILC often heavily depends on E-cadherin results. This study emphasizes the need for diagnostic clarification in cases with discordance between morphology and E-cadherin patterns.

E-Cadherin Mutational Landscape and Outcomes in Breast Invasive Lobular Carcinoma

Invasive lobular carcinomas (ILC) are characterized by the loss of E-cadherin expression and CDH1 gene inactivation. Diagnostic reproducibility for this tumor type is currently suboptimal and could be improved by a better understanding of its histomolecular and clinical heterogeneity. We have analyzed the relationship between the presence, type, or position of CDH1 mutations, E-cadherin expression, and clinicopathological features (including outcome) in a retrospective series of 251 primary ILC with a long follow-up (median: 9.5 years). The mutational status of E-cadherin gene (CDH1) was determined by RNA sequencing from frozen tumor samples. E-cadherin immunohistochemistry (IHC) was performed with antibodies directed against the intracellular domain (clone 4A2C7) and the extracellular domain (clone NCH38). IHC expression of p120 and β-catenin was also assessed in E-cadherin diffusely positive cases. Three major patterns of E-cadherin membrane expression were identified by IHC, with good agreement between the 2 clones (overall concordance: 83.8%, Kappa 0.67): null/focal expression (≤10%) (72.8% of cases for 4A2C7 and 83.8% for NCH38), heterogeneous expression (11%-89%) (19.2% of cases for 4A2C7 and 6.9% for NCH38), and diffuse expression (≥90%) (8% of cases for 4A2C7 and 9.3% for NCH38). E-cadherin membranous expression, when present, was abnormal (incomplete labeling and/or reduced intensity). ILC with diffuse E-cadherin expression showed abnormal β-catenin or p120-catenin staining in 21% of cases. Interestingly, these cases with diffusely expressed E-cadherin had a CDH1 mutation rate as high as the E-cadherin null/focal cases (∼70%) but were enriched in nontruncating mutations. Regarding CDH1 mutation location, intracytoplasmic domain mutations correlated with a divergent E-cadherin IHC phenotype between the 2 antibodies (4A2C7 ≤ 10%/NCH38 ≥ 10%). Clinico-pathological correlation analyses found that stromal amount (inversely correlated with tumor cellularity) and tumor-infiltrating lymphocytes were less abundant in ILC with E-cadherin null/focal cases. In addition, CDH1 truncating mutations were associated with radiohistologic size discordance and were identified in multivariate survival analysis as an independent poor prognosis factor in terms of metastasis risk and breast cancer-related mortality. Overall, our study highlights the importance of the precise mutational status of CDH1 in the clinical, radiological, histologic, and phenotypic expression of lobular carcinomas. These findings should be taken into account in future attempts to improve diagnostic criteria or methods for ILC, as well as for clinicobiological studies dedicated to this tumor type.

KLHL14 and E-Cadherin Nuclear Co-Expression as Predicting Factor of Nonfunctioning PitNET Invasiveness: Preliminary Study

Background/Objectives. Novel diagnostic and therapeutic approaches are needed to improve the clinical management of nonfunctioning pituitary neuroendocrine tumors (NF-PitNETs). Here, the expression of two proteins controlling the epithelial-mesenchymal transition (EMT)-an underlying NF-PitNET pathogenic mechanism-were analyzed as prognostic markers: E-cadherin (E-Cad) and KLHL14. Methods. The immunohistochemistry characterization of KLHL14 and E-Cad subcellular expression in surgical specimens of 12 NF-PitNET patients, with low and high invasiveness grades (respectively, Ki67+ < and ≥3%) was carried out. Results. The analysis of healthy vs. NF-PitNET tissues demonstrated an increased protein expression and nuclear translocation of KLHL14. Moreover, both E-Cad and KLHL14 shifted from a cytoplasmic (C) form in a low invasive NF-PitNET to a nuclear (N) localization in a high invasive NF-PitNET. A significant correlation was found between E-Cad/KLHL14 co-localization in the cytoplasm (p = 0.01) and nucleus (p = 0.01) and with NF-PitNET invasiveness grade. Conclusions. Nuclear buildup of both E-Cad and KLHL14 detected in high invasive NF-PitNET patients highlights a novel intracellular mechanism governing the tumor propensity to local invasion (Ki67+ ≥ 3%). The prolonged progression-free survival trend documented in patients with lower KLHL14 expression further supported such a hypothesis even if a larger cohort of NF-PitNET patients have to be analyzed to definitively recognize a key prognostic role for KLHL14.

Integration of Pathological Criteria and Immunohistochemical Evaluation for Invasive Lobular Carcinoma Diagnosis: Recommendations From the European Lobular Breast Cancer Consortium

Invasive lobular carcinoma (ILC) is the second most frequent type of breast cancer (BC) and its peculiar morphology is mainly driven by inactivation of CDH1, the gene coding for E-cadherin cell adhesion protein. ILC-specific therapeutic and disease-monitoring approaches are gaining momentum in the clinic, increasing the importance of accurate ILC diagnosis. Several essential and desirable morphologic diagnostic criteria are currently defined by the World Health Organization, the routine use of immunohistochemistry (IHC) for E-cadherin is not recommended. Disagreement in the diagnosis of ILC has been repeatedly reported, but interpathologist agreement increases with the use of E-cadherin IHC. In this study, we aimed to harmonize the pathological diagnosis of ILC by comparing 5 commonly used E-cadherin antibody clones (NCH-38, EP700Y, Clone 36, NCL-L-E-cad [Clone 36B5], and ECH-6). We determined their biochemical specificity for the E-cadherin protein and IHC staining performance according to type and location of mutation on the CDH1 gene. Western blot analysis on mouse cell lines with conditional E-cadherin expression revealed a reduced specificity of EP700Y and NCL-L-E-cad for E-cadherin, with cross-reactivity of Clone 36 to P-cadherin. The use of IHC improved interpathologist agreement for ILC, lobular carcinoma in situ, and atypical lobular hyperplasia. The E-cadherin IHC staining pattern was associated with variant allele frequency and likelihood of nonsense-mediated RNA decay but not with the type or position of CDH1 mutations. Based on these results, we recommend the indication for E-cadherin staining, choice of antibodies, and their interpretation to standardize ILC diagnosis in current pathology practice.

Invasive lobular breast cancer: Focus on prevention, genetics, diagnosis, and treatment

Invasive lobular cancer (ILC) is the most common of the breast cancer special types, accounting for up to 15% of all breast malignancies. The distinctive biological features of ILC include the loss of the cell adhesion molecule E-cadherin, which drives the tumor's peculiar discohesive growth pattern, with cells arranged in single file and dispersed throughout the stroma. Typically, such tumors originate in the lobules, are more commonly bilateral compared to invasive ductal cancer (IDC) and require a more accurate diagnostic examination through imaging. They are luminal in molecular subtype, and exhibit estrogen and progesterone receptor positivity and HER2 negativity, thus presenting a more unpredictable response to neoadjuvant therapies. There has been a significant increase in research focused on this distinctive breast cancer subtype, including studies on its pathology, its clinical and surgical management, and the high-resolution definition of its genomic profile, as well as the development of new therapeutic perspectives. This review will summarize the heterogeneous pattern of this unique disease, focusing on challenges in its comprehensive clinical management and on future insights and research objectives.

Ovarian Clear Cell Carcinoma and Markers of Epithelial-Mesenchymal Transition (EMT): Immunohistochemical Characterization of Tumor Budding

Tumor budding, largely considered a manifestation of epithelial-mesenchymal transition (EMT) is an established prognostic marker for several cancers. In a recent study, tumor budding was associated with poor clinical outcomes in early-stage ovarian clear cell carcinoma. Here, we evaluated the immune expression of 3 proteins shown to be associated with EMT (E-cadherin, β-catenin, and glypican-3) in 72 primary tumors of ovarian clear cell carcinoma with median follow-up of 39.47 mo. E-cadherin and β-catenin expression was further evaluated in tumor buds in 29 (40%) cases. In the tumor mass, diffuse membranous expression of E-cadherin and β-catenin was seen in 83% (60/72) and 81% (58/72) cases, respectively. Nuclear accumulation of E-cadherin was seen in 7 (10%) cases, while none of the cases showed nuclear β-catenin expression. Glypican-3 expression was diffuse in 33.3% (24/72), patchy in 29.2% (21/72), and absent in 37.5% (27/72) cases. Evaluation of tumor buds showed aberrant patterns of expression (complete loss/cytoplasmic accumulation/diminished, discontinuous incomplete membranous staining) of E-cadherin in 29/29 (100%) and of β-catenin in 26/29 (90%) cases. E-cadherin, β-catenin, and glypican-3 expression in the main tumor mass had no association with stage, lymph node status, recurrent/progressive disease, status at last follow-up, survival and histopathologic features ( P >0.05). Our finding of aberrant expression of both E-cadherin and β-catenin in tumor buds indicates involvement of Wnt signaling pathway/EMT in tumor budding and outlines its significance as a prognostic marker especially for early-stage ovarian clear cell carcinoma.

E-Cadherin Modulation and Inter-Cellular Trafficking in Tubular Gastric Adenocarcinoma: A High-Resolution Microscopy Pilot Study

Despite the numerous advances in tumor molecular biology and chemotherapy options, gastric adenocarcinoma is still the most frequent form of gastric cancer. One of the core proteins that regulates inter-cellular adhesion, E-cadherin plays important roles in tumorigenesis as well as in tumor progression; however, the exact expression changes and modulation that occur in gastric cancer are not yet fully understood. In an attempt to estimate if the synthesis/degradation balance matches the final membrane expression of this adhesion molecule in cancer tissue, we assessed the proportion of E-cadherin that is found in the Golgi vesicles as well as in the lysosomal pathway We utilized archived tissue fragments from 18 patients with well and poorly differentiated intestinal types of gastric cancer and 5 samples of normal gastric mucosa, by using high-magnification multispectral microscopy and high-resolution fluorescence deconvolution microscopy. Our data showed that E-cadherin is not only expressed in the membrane, but also in the cytoplasm of normal and tumor gastric epithelia. E-cadherin colocalization with the Golgian vesicles seemed to be increasing with less differentiated tumors, while co-localization with the lysosomal system decreased in tumor tissue; however, the membrane expression of the adhesion molecule clearly dropped from well to poorly differentiated tumors. Thus E-cadherin seems to be more abundantly synthetized than eliminated via lysosomes/exosomes in less differentiated tumors, suggesting that post-translational modifications, such as cleavage, conformational inactivation, or exocytosis, are responsible for the net drop of E-cadherin at the level of the membrane in more anaplastic tumors. This behavior is in perfect accordance with the concept of partial epithelial-to-mesenchymal transition (P-EMT), when the E-cadherin expression of tumor cells is in fact not downregulated but redistributed away from the membrane in recycling vesicles. Moreover, our high-resolution deconvolution microscopy study showed for the first time, at the tissue level, the presence of Lysosome-associated membrane glycoprotein 1 (LAMP1)-positive exosomes/multivesicular bodies being trafficked across the membranes of tumor epithelial cells. Altogether, a myriad of putative modulatory pathways is available as a treatment turning point, even if we are to only consider the metabolism of membrane E-cadherin regulation. Future super-resolution microscopy studies are needed to clarify the extent of lysosome/exosome exchange between tumor cells and with the surrounding stroma, in histopathology samples or even in vivo.

Results of a worldwide survey on the currently used histopathological diagnostic criteria for invasive lobular breast cancer

Invasive lobular carcinoma (ILC) represents the second most common subtype of breast cancer (BC), accounting for up to 15% of all invasive BC. Loss of cell adhesion due to functional inactivation of E-cadherin is the hallmark of ILC. Although the current world health organization (WHO) classification for diagnosing ILC requires the recognition of the dispersed or linear non-cohesive growth pattern, it is not mandatory to demonstrate E-cadherin loss by immunohistochemistry (IHC). Recent results of central pathology review of two large randomized clinical trials have demonstrated relative overdiagnosis of ILC, as only ~60% of the locally diagnosed ILCs were confirmed by central pathology. To understand the possible underlying reasons of this discrepancy, we undertook a worldwide survey on the current practice of diagnosing BC as ILC. A survey was drafted by a panel of pathologists and researchers from the European lobular breast cancer consortium (ELBCC) using the online tool SurveyMonkey®. Various parameters such as indications for IHC staining, IHC clones, and IHC staining procedures were questioned. Finally, systematic reporting of non-classical ILC variants were also interrogated. This survey was sent out to pathologists worldwide and circulated from December 14, 2020 until July, 1 2021. The results demonstrate that approximately half of the institutions use E-cadherin expression loss by IHC as an ancillary test to diagnose ILC and that there is a great variability in immunostaining protocols. This might cause different staining results and discordant interpretations. As ILC-specific therapeutic and diagnostic avenues are currently explored in the context of clinical trials, it is of importance to improve standardization of histopathologic diagnosis of ILC diagnosis.

Lobular Breast Cancer: Histomorphology and Different Concepts of a Special Spectrum of Tumors

Simple Summary

Invasive lobular breast cancer (ILC) is a special type of breast cancer (BC) that was first described in 1941. The diagnosis of ILC is made by microscopy of tumor specimens, which reveals a distinct morphology. This review recapitulates the developments in the microscopic assessment of ILC from 1941 until today. We discuss different concepts of ILC, provide an overview on ILC variants, and highlight advances which have contributed to a better understanding of ILC as a special histologic spectrum of tumors.

Abstract

Invasive lobular breast cancer (ILC) is the most common special histological type of breast cancer (BC). This review recapitulates developments in the histomorphologic assessment of ILC from its beginnings with the seminal work of Foote and Stewart, which was published in 1941, until today. We discuss different concepts of ILC and their implications. These concepts include (i) BC arising from mammary lobules, (ii) BC growing in dissociated cells and single files, and (iii) BC defined as a morpho-molecular spectrum of tumors with distinct histological and molecular characteristics related to impaired cell adhesion. This review also provides a comprehensive overview of ILC variants, their histomorphology, and differential diagnosis. Furthermore, this review highlights recent advances which have contributed to a better understanding of the histomorphology of ILC, such as the role of the basal lamina component laminin, the molecular specificities of triple-negative ILC, and E-cadherin to P-cadherin expression switching as the molecular determinant of tubular elements in CDH1-deficient ILC. Last but not least, we provide a detailed account of the tumor microenvironment in ILC, including tumor infiltrating lymphocyte (TIL) levels, which are comparatively low in ILC compared to other BCs, but correlate with clinical outcome. The distinct histomorphology of ILC clearly reflects a special tumor biology. In the clinic, special treatment strategies have been established for triple-negative, HER2-positive, and ER-positive BC. Treatment specialization for patients diagnosed with ILC is just in its beginnings. Accordingly, ILC deserves greater attention as a special tumor entity in BC diagnostics, patient care, and cancer research.

E-Cadherin expression in human tumors: a tissue microarray study on 10,851 tumors

BACKGROUND

The E-Cadherin gene (CDH1, Cadherin 1), located at 16q22.1 encodes for a calcium-dependent membranous glycoprotein with an important role in cellular adhesion and polarity maintenance.

METHODS

To systematically determine E-Cadherin protein expression in normal and cancerous tissues, 14,637 tumor samples from 112 different tumor types and subtypes as well as 608 samples of 76 different normal tissue types were analyzed by immunohistochemistry in a tissue microarray format.

RESULTS

E-Cadherin was strongly expressed in normal epithelial cells of most organs. From 77 tumor entities derived from cell types normally positive for E-Cadherin, 35 (45.5%) retained at least a weak E-Cadherin immunostaining in ≥99% of cases and 61 (79.2%) in ≥90% of cases. Tumors with the highest rates of E-Cadherin loss included Merkel cell carcinoma, anaplastic thyroid carcinoma, lobular carcinoma of the breast, and sarcomatoid and small cell neuroendocrine carcinomas of the urinary bladder. Reduced E-Cadherin expression was linked to higher grade (p = 0.0009), triple negative receptor status (p = 0.0336), and poor prognosis (p = 0.0466) in invasive breast carcinoma of no special type, triple negative receptor status in lobular carcinoma of the breast (p = 0.0454), advanced pT stage (p = 0.0047) and lymph node metastasis in colorectal cancer (p < 0.0001), and was more common in recurrent than in primary prostate cancer (p < 0.0001). Of 29 tumor entities derived from E-Cadherin negative normal tissues, a weak to strong E-Cadherin staining could be detected in at least 10% of cases in 15 different tumor entities (51.7%). Tumors with the highest frequency of E-Cadherin upregulation included various subtypes of testicular germ cell tumors and renal cell carcinomas (RCC). E-Cadherin upregulation was more commonly seen in malignant than in benign soft tissue tumors (p = 0.0104) and was associated with advanced tumor stage (p = 0.0276) and higher grade (p = 0.0035) in clear cell RCC, and linked to advanced tumor stage (p = 0.0424) and poor prognosis in papillary RCC (p ≤ 0.05).

CONCLUSION

E-Cadherin is consistently expressed in various epithelial cancers. Down-regulation or loss of E-Cadherin expression in cancers arising from E-Cadherin positive tissues as well as E-Cadherin neo-expression in cancers arising from E-Cadherin negative tissues is linked to cancer progression and may reflect tumor dedifferentiation.

Practicability of clinical application of bladder cancer molecular classification and additional value of epithelial-to-mesenchymal transition: prognostic value of vimentin expression

BACKGROUND

Bladder cancer (BlCa) taxonomy has proved its impact in patient outcome and selection for targeted therapies, but such transcriptomic-based classification has not yet translated to routine practice. Moreover, epithelial-to-mesenchymal transition (EMT) has shown relevance in acquisition of more aggressive BlCa phenotype. We aimed to test the usefulness of the molecular classification, as defined by immunohistochemistry (a routinely performed and easy-to-implement technique), in a well-defined BlCa cohort of both non-muscle invasive (NMIBC) and muscle invasive (MIBC) disease. Also, we aimed to assess the additional prognostic value of the mesenchymal marker vimentin to the stratification strategy.

METHODS

A total of 186 samples were available. Immunohistochemistry/RT-qPCR for luminal markers GATA3/FOXA1, basal markers KRT5/KRT6A and vimentin were performed.

RESULTS

mRNA expression levels of the markers positively correlated with immunoexpression scores. We found substantial overlapping in immunoexpression of luminal and basal markers, evidencing tumor heterogeneity. In MIBC, basal tumors developed recurrence more frequently. NMIBC patients with higher vimentin immunoexpression endured poorer disease-free survival, and increased expression was observed from normal bladder-NMIBC-MIBC-metastases.

CONCLUSIONS

The classification has the potential to be implemented in routine, but further adjustments in practical scoring should be defined; focusing on additional markers, including those related to EMT, may further refine BlCa molecular taxonomy.

E-cadherin immunohistochemical expression in invasive lobular carcinoma of the breast: correlation with morphology and CDH1 somatic alterations

E-cadherin (ECAD) immunohistochemical (IHC) expression is lost in ∼90% of invasive lobular carcinomas (ILCs) owing to genomic alterations of CDH1. We examined morphologic features and ECAD IHC expression in invasive breast carcinomas (BCs) with known CDH1 alterations. Between January 2014 and May 2018, 202 cases of BC with a CDH1 somatic alteration were identified. ECAD expression was lost in 77% (155/202) of cases and was retained in 23% (47/202) cases. Most (90%, 139/155) ECAD-negative cases were morphologically classified as ILC, while the remaining (10%, 16/155) were invasive mammary carcinoma with mixed ductal and lobular features (IMC). Of 47 cases with ECAD staining, 62% (29/47) were classified as ILC, 23% (11/47) were classified as IMC, and 15% (7/47) were classified as invasive ductal carcinoma (IDC). Of note, 51% (24/47) of ECAD-positive cases were initially diagnosed as IDC or IMC based on ECAD expression alone. For ECAD-negative BCs, 98% (152/155) of CDH1 alterations were truncating, and 2% (3/155) were variants of unknown significance (VUS). Truncating CDH1 alterations were identified in the majority of ECAD-positive BCs (72%, 34/47); however, VUS-type CDH1 alterations were more prevalent (28%, 13/47) in ECAD-positive BCs than in ECAD-negative BCs. Although 90% of ECAD-negative tumors were compatible with ILC in this study, 17% (29/168) of ILC cases were ECAD positive. In addition, CDH1 truncating alterations were seen in ECAD-positive ILC, supporting the notion of aberrant ECAD staining. Therefore, ECAD IHC expression must be interpreted in conjunction with morphology, and BC with classic histologic features of ILC should not be reclassified as IDC/IMC based solely on the status of ECAD IHC expression.