Survival Outcomes in Invasive Lobular Carcinoma Compared to Oestrogen Receptor-Positive Invasive Ductal Carcinoma

E-Cadherin-Mediated Cell-Cell Adhesion and Invasive Lobular Breast Cancer

E-cadherin is a transmembrane protein and central component of adherens junctions (AJs). The extracellular domain of E-cadherin forms homotypic interactions with E-cadherin on adjacent cells, facilitating the formation of cell-cell adhesions, known as AJs, between neighbouring cells. The intracellular domain of E-cadherin interacts with α-, β- and p120-catenins, linking the AJs to the actin cytoskeleton. Functional AJs maintain epithelial tissue identity and integrity. Transcriptional downregulation of E-cadherin is the first step in epithelial-to-mesenchymal transition (EMT), a process essential in development and tissue repair, which, in breast cancer, can contribute to tumour progression and metastasis. In addition, loss-of-function mutations in E-cadherin are a defining feature of invasive lobular breast cancer (also known as invasive lobular carcinoma (ILC)), the second most common histological subtype of breast cancer. ILC displays a discohesive, single-file invasive growth pattern due to the loss of functional AJs. Despite being so prevalent, until recently there has been limited ILC-focused research and historically ILC patients have often been excluded from clinical trials. Despite displaying a number of good prognostic indicators, such as low grade and high rates of estrogen receptor positivity, ILC patients tend to have similar or poorer outcomes relative to the most common subtype of breast cancer, invasive ductal carcinoma (IDC). In ILC, E-cadherin loss promotes hyperactivation of growth factor receptors, in particular insulin-like growth factor 1 receptor, anoikis resistance and synthetic lethality with ROS1 inhibition. These features introduce clinical vulnerabilities that could potentially be exploited to improve outcomes for ILC patients, for whom there are currently limited tailored treatments available.

Core needle biopsy changes the expression of TGFβ1 and TGFβRII at protein level, and the distribution of CD4 and CD8 positive T cells in primary breast cancer

Core needle biopsy (CNB) has become a paradigm in preoperative breast cancer (BC) diagnosis. Although considered safe, it is an invasive procedure, which changes the tumor microenvironment. It facilitates a tumor supportive immune response, induces epithelial-mesenchymal transition (EMT), and enables the release of circulating tumor cells. The cytokine Transforming Growth Factor β (TGFβ) with its pleiotropic immunologic functions has an important role in this process. The aim of this study was to clarify the specific impact of CNB on the activity of the TGFβ pathway in early BC. We compared formalin fixed paraffin embedded samples from CNBs to the corresponding surgical resection specimens (SRSs) of 49 patients with BC. We found that the expression of TGFβ1 at protein level was significantly higher in both tumor epithelial and benign stromal cells in the SRSs (p=0.001), whereas the expression of TGFβRII in tumor cells was lower (p=0.001). The frequency of intra tumoral CD8 and CD4 positive T lymphocytes was lower in SRSs (p=0081 and p=0001, respectively), while in the peripheral stroma their prevalence was increased (p=0001 and p=0012, respectively). Our results show that CNB changes the hallmarks of the TGFβ path way in early BC. These CNB-induced changes in the tumor and in its microenvironment suggest that the procedure may change the immunological anti-tumor response of the host.

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.

Pathway-based signatures predict patient outcome, chemotherapy benefit and synthetic lethal dependencies in invasive lobular breast cancer

BACKGROUND

Invasive Lobular Carcinoma (ILC) is a morphologically distinct breast cancer subtype that represents up to 15% of all breast cancers. Compared to Invasive Breast Carcinoma of No Special Type (IBC-NST), ILCs exhibit poorer long-term outcome and a unique pattern of metastasis. Despite these differences, the systematic discovery of robust prognostic biomarkers and therapeutically actionable molecular pathways in ILC remains limited.

METHODS

Pathway-centric multivariable models using statistical machine learning were developed and tested in seven retrospective clinico-genomic cohorts (n = 996). Further external validation was performed using a new RNA-Seq clinical cohort of aggressive ILCs (n = 48).

RESULTS AND CONCLUSIONS

mRNA dysregulation scores of 25 pathways were strongly prognostic in ILC (FDR-adjusted P < 0.05). Of these, three pathways including Cell-cell communication, Innate immune system and Smooth muscle contraction were also independent predictors of chemotherapy response. To aggregate these findings, a multivariable machine learning predictor called PSILC was developed and successfully validated for predicting overall and metastasis-free survival in ILC. Integration of PSILC with CRISPR-Cas9 screening data from breast cancer cell lines revealed 16 candidate therapeutic targets that were synthetic lethal with high-risk ILCs. This study provides interpretable prognostic and predictive biomarkers of ILC which could serve as the starting points for targeted drug discovery for this disease.

Reporting on invasive lobular breast cancer in clinical trials: a systematic review

Invasive lobular breast cancer (ILC) differs from invasive breast cancer of no special type in many ways. Evidence on treatment efficacy for ILC is, however, lacking. We studied the degree of documentation and representation of ILC in phase III/IV clinical trials for novel breast cancer treatments. Trials were identified on Pubmed and clinicaltrials.gov. Inclusion/exclusion criteria were reviewed for requirements on histological subtype and tumor measurability. Documentation of ILC was assessed and ILC inclusion rate, central pathology and subgroup analyses were evaluated. Inclusion restrictions concerning tumor measurability were found in 39/93 manuscripts. Inclusion rates for ILC were documented in 13/93 manuscripts and varied between 2.0 and 26.0%. No central pathology for ILC was reported and 3/13 manuscripts had ILC sub-analyses. ILC is largely disregarded in most trials with poor representation and documentation. The current inclusion criteria using RECIST v1.1, fall short in recognizing the unique non-measurable metastatic infiltration of ILC.

Effect of histological breast cancer subtypes invasive lobular versus non-special type on survival in early intermediate-to-high-risk breast carcinoma: results from the SUCCESS trials

BACKGROUND

Invasive lobular breast carcinomas (ILC) have different histological features compared to non-special type carcinomas (NST), but the effect of histological subtypes on survival is controversial. In this study, we compared clinicopathological characteristics and outcomes between ILC and NST based on a large pooled data set from three adjuvant breast cancer trials (SUCCESS A, B, and C) and investigated a potential differential effect of recurrence risk related to nodal stage on survival.

METHODS

From 2005 to 2017, the large randomized controlled SUCCESS A, B, and C trials enrolled 8190 patients with primary, intermediate-to-high-risk breast carcinoma. All patients received adjuvant chemotherapy, and endocrine and/or HER2-targeted treatment was given where appropriate. Survival outcomes in terms of disease-free survival (DFS), overall survival (OS), breast cancer-specific survival (BCSS), and distant disease-free survival (DDFS) were estimated using the Kaplan-Meier method and analyzed using log-rank tests as well as univariable and adjusted multivariable Cox regression models.

RESULTS

In the SUCCESS trials, 6284 patients had NST and 952 had ILC. The median follow-up time was 64 months. ILC patients were older, more likely to receive mastectomy, and more likely to have larger tumor sizes, lymph node infiltration, hormone receptor-positive, HER2neu-negative, and luminal A-like tumors than NST patients. In the overall cohort, no significant differences between ILC and NST were detectable regarding the four survival endpoints, with hazard ratios obtained in adjusted multivariable cox regressions of 0.96 (95% CI 0.77-1.21, p = 0.743) for DFS, 1.13 (95% CI 0.85-1.50, p = 0.414) for OS, 1.21 (95% CI 0.89-1.66, p = 0.229) for BCSS, and 0.95 (95% CI 0.73-1.24, p = 0.689) for DDFS. However, a differential effect of nodal stage on survival was observed, with better survival for ILC patients with pN0/pN1 tumors and worse survival for ILC patients with pN2/pN3 tumors compared to NST patients.

CONCLUSIONS

Our results revealed that ILC was associated with worse survival compared to NST for patients at high risk of recurrence due to advanced lymph node infiltration. These findings should be taken into account for treatment decisions and monitoring.

Histologic tumor type as a determinant of survival in hormone receptor-positive, HER2-negative, pT1-3 invasive ductal and lobular breast cancer

PURPOSE

The aim of the study was to compare the difference in survival between invasive ductal (IDC) and lobular carcinoma (ILC).

METHODS

Data of patients (n = 1843) with a hormone receptor-positive, HER2-negative, pT1-3 IDC or ILC cancer without distant metastasis, treated at the Ghent University Hospital over the time period 2001-2015, were analyzed.

RESULTS

ILC represented 13.9% of the tumors, had a higher percentage of pT3 and pN3 stages than IDC, lymphovascular space invasion (LVSI) was less present and Ki-67 was mostly low. 73.9% of ILCs were grade 2, whereas IDC had more grade 1 and grade 3 tumors. Kaplan-Meier curves and log-rank testing showed a significant worse DFS for ILC with pN ≥ 1 than for their IDC counterpart. In a multivariable Cox regression analysis the histologic tumor type, ductal or lobular, was a determinant of DFS over 120 months (IDC as reference; hazard ratio for ILC 1.77, 95% CI 1.08-2.90) just as the ER Allred score (hazard ratio 0.84, 95% CI 0.78-0.91), LVSI (hazard ratio 1.75, 95% CI 1.12-2.74) and pN3 (hazard ratio 2.29, 95% CI 1.03-5.09). Determinants of OS over ten years were age (hazard ratio 1.05, 95% CI 1.02-1.07), LVSI (hazard ratio 3.62, 95% CI 1.92-6.82) and the ER Allred score (hazard ratio 0.80, 95% CI 0.73-0.89).

CONCLUSION

The histologic tumor type, ductal or lobular, determines DFS in hormone receptor-positive, HER2-negative, pT1-3 breast cancer besides the ER Allred score, LVSI and pN3.

Association of body mass index with clinicopathological features and survival in patients with primary invasive lobular breast cancer

PURPOSE

Invasive lobular carcinoma (ILC) represents up to 15% of all breast carcinomas. While the proportion of women with overweight and obesity increases globally, the impact of body mass index (BMI) at primary diagnosis on clinicopathological features of ILC and the prognosis of the patients has not been investigated yet.

PATIENTS AND METHODS

We performed a multicentric retrospective study including patients diagnosed with non-metastatic pure ILC. The association of BMI at diagnosis with clinicopathological variables was assessed using linear or multinomial logistic regression. Univariable and multivariable survival analyses were performed to evaluate the association of BMI with disease-free survival (DFS), distant recurrence-free survival (DRFS), and overall survival (OS).

RESULTS

The data of 2856 patients with ILC and available BMI at diagnosis were collected, of which 2570/2856 (90.0%) had oestrogen receptor (ER)-positive and human epidermal growth factor receptor (HER2) not amplified/overexpressed (ER+/HER2-) ILC. Of these 2570 patients, 80 were underweight (3.1%), 1410 were lean (54.9%), 712 were overweight (27.7%), and 368 were obese (14.3%). Older age at diagnosis, a higher tumour grade, a larger tumour size, a nodal involvement, and multifocality were associated with a higher BMI. In univariable models, higher BMI was associated with worse outcomes for all end-points (DFS: hazard ratio (HR) 1.21, 95CI 1.12-1.31, p value<0.01; DRFS: HR 1.25, 95CI 1.12-1.40, p value<0.01; OS: HR 1.25, 95CI 1.13-1.37, p value<0.01). This association was not statistically significant in multivariable analyses (DFS: HR 1.09, 95CI 0.99-1.20, p value 0.08; DRFS: HR 1.03, 95CI 0.89-1.20, p value 0.67; OS: HR 1.11, 95CI 0.99-1.24, p value 0.08), whereas grade, tumour size, and nodal involvement were still prognostic for all end-points.

CONCLUSION

Worse prognostic factors such as higher grade, larger tumour size, and nodal involvement are associated with higher BMI in ER+/HER2- ILC, while there was no statistical evidence for an independent prognostic role for BMI. Therefore, we hypothesise that the effect of BMI on survival could be mediated through its association with these clinicopathological variables.

Optimized Modeling of Metastatic Triple-Negative Invasive Lobular Breast Carcinoma

Invasive lobular carcinoma (ILC) is a common breast cancer subtype that is often diagnosed at advanced stages and causes significant morbidity. Late-onset secondary tumor recurrence affects up to 30% of ILC patients, posing a therapeutic challenge if resistance to systemic therapy develops. Nonetheless, there is a lack of preclinical models for ILC, and the current models do not accurately reproduce the complete range of the disease. We created clinically relevant metastatic xenografts to address this gap by grafting the triple-negative IPH-926 cell line into mouse milk ducts. The resulting intraductal xenografts accurately recapitulate lobular carcinoma in situ (LCIS), invasive lobular carcinoma, and metastatic ILC in relevant organs. Using a panel of 15 clinical markers, we characterized the intratumoral heterogeneity of primary and metastatic lesions. Interestingly, intraductal IPH-926 xenografts express low but actionable HER2 and are not dependent on supplementation with the ovarian hormone estradiol for their growth. This model provides a valuable tool to test the efficiency of potential new ILC therapeutics, and it may help detect vulnerabilities within ILC that can be exploited for therapeutic targeting.

Treatment and outcome in metastatic lobular breast cancer in the prospective German research platform OPAL

PURPOSE

Evidence about routine treatment and outcome of patients with invasive lobular cancer (ILC) is limited, especially regarding metastatic disease. Here we present prospective real-world data of patients with metastatic ILC (mILC) as compared to patients with metastatic invasive ductal cancer (mIDC) receiving systemic therapy in routine care in Germany.

METHODS

Prospective data on patient and tumor characteristics, treatments, and outcomes of patients with mILC (n = 466) and mIDC (n = 2100), recruited between 2007 and 2021 into the Tumor Registry Breast Cancer/OPAL were analyzed.

RESULTS

Compared to mIDCs, patients with mILC were older at start of first-line treatment (median 69 vs. 63 years) and had more often lower grade (G1/G2: 72.8% vs. 51.2%), hormone receptor (HR)-positive (83.7% vs. 73.2%) and less often HER2-positive (14.2% vs. 28.6%) tumors, which metastasized more frequently to the bone (19.7% vs. 14.5%) or peritoneum (9.9% vs. 2.0%), and less frequently to the lungs (0.9% vs. 4.0%). Median OS of patients with mILC (n = 209) and mIDC (n = 1158) was 30.2 months [95% confidence interval (CI) 25.3, 36.0] and 33.7 months [95% CI 30.3, 37.9], respectively. Multivariate survival analysis did not show a significant prognostic impact of the histological subtype [HR mILC vs. mIDC 1.18 (95% CI 0.97-1.42)].

CONCLUSION

Overall, our real-world data confirm clinicopathological differences between mILC and mIDC breast cancer patients. Despite patients with mILC presenting with some favorable prognostic factors, ILC histopathology was not associated with a better clinical outcome in multivariate analysis, suggesting the need for more tailored treatment strategies for patients with the lobular subtype.

Current and future diagnostic and treatment strategies for patients with invasive lobular breast cancer

BACKGROUND

Invasive lobular breast cancer (ILC) is the second most common type of breast cancer after invasive breast cancer of no special type (NST), representing up to 15% of all breast cancers.

DESIGN

Latest data on ILC are presented, focusing on diagnosis, molecular make-up according to the European Society for Medical Oncology Scale for Clinical Actionability of molecular Targets (ESCAT) guidelines, treatment in the early and metastatic setting and ILC-focused clinical trials.

RESULTS

At the imaging level, magnetic resonance imaging-based and novel positron emission tomography/computed tomography-based techniques can overcome the limitations of currently used imaging techniques for diagnosing ILC. At the pathology level, E-cadherin immunohistochemistry could help improving inter-pathologist agreement. The majority of patients with ILC do not seem to benefit as much from (neo-)adjuvant chemotherapy as patients with NST, although chemotherapy might be required in a subset of high-risk patients. No differences in treatment efficacy are seen for anti-human epidermal growth factor receptor 2 (HER2) therapies in the adjuvant setting and cyclin-dependent kinases 4 and 6 inhibitors in the metastatic setting. The clinical utility of the commercially available prognostic gene expression-based tests is unclear for patients with ILC. Several ESCAT alterations differ in frequency between ILC and NST. Germline BRCA1 and PALB2 alterations are less frequent in patients with ILC, while germline CDH1 (gene coding for E-cadherin) alterations are more frequent in patients with ILC. Somatic HER2 mutations are more frequent in ILC, especially in metastases (15% ILC versus 5% NST). A high tumour mutational burden, relevant for immune checkpoint inhibition, is more frequent in ILC metastases (16%) than in NST metastases (5%). Tumours with somatic inactivating CDH1 mutations may be vulnerable for treatment with ROS1 inhibitors, a concept currently investigated in early and metastatic ILC.

CONCLUSION

ILC is a unique malignancy based on its pathological and biological features leading to differences in diagnosis as well as in treatment response, resistance and targets as compared to NST.