Metaplastic Breast Carcinoma Versus Triple-Negative Breast Cancer: Survival and Response to Treatment

Translational Aspects in Metaplastic Breast Carcinoma

Breast cancer is the most common cancer among women. Metaplastic breast carcinoma (MpBC) is a rare, heterogeneous group of invasive breast carcinomas, which are classified as predominantly triple-negative breast carcinomas (TNBCs; HR-negative/HER2-negative). Histologically, MpBC is classified into six subtypes. Two of these are considered low-grade and the others are high-grade. MpBCs seem to be more aggressive, less responsive to neoadjuvant chemotherapy, and have higher rates of chemoresistance than other TNBCs. MpBCs have a lower survival rate than expected for TNBCs. MpBC treatment represents a challenge, leading to a thorough exploration of the tumor immune microenvironment, which has recently opened the possibility of new therapeutic strategies. The epithelial-mesenchymal transition in MpBC is characterized by the loss of intercellular adhesion, downregulation of epithelial markers, underexpression of genes with biological epithelial functions, upregulation of mesenchymal markers, overexpression of genes with biological mesenchymal functions, acquisition of fibroblast-like (spindle) morphology, cytoskeleton reorganization, increased motility, invasiveness, and metastatic capabilities. This article reviews and summarizes the current knowledge and translational aspects of MpBC.

A Single-Center 18-Year Series of 73 Cases of Metaplastic Carcinoma of the Breast

Aim

To examine the clinical management of metaplastic breast cancer (MeBC), particularly the role of chemotherapy.

Methods

This retrospective study included patients with MeBC (n = 73) from a tertiary breast cancer center: the "Centre des Maladies du Sein of the CHU de Québec-Université Laval." The specimens were reviewed by two pathologists. Patient and tumor characteristics, systemic therapy (neoadjuvant and adjuvant), disease-free survival (DFS), and overall survival (OS) were recorded.

Results

The median follow-up was 57.2 months. The mean tumor size was 39.5 ± 32.1 (range, 1-200) mm. Most were in grade 3 (75.3%), without evidence of clinical nodal involvement (75.3%), and triple-negative (79.5%). Chemotherapy was given to 49 (67.1%) patients. Thirty-seven patients (50.7%) underwent a mastectomy, and 22/37 (59.5%) received radiotherapy. Adjuvant chemotherapy was given to 36 patients (49.3%), and nine (12.3%) patients were treated with neoadjuvant chemotherapy. The 5-year OS and DFS rates were 60.2% and 66.8%. Among the nine patients who received neoadjuvant chemotherapy, three (33.3%) achieved a partial response, three (33.3%) had stable disease, and three (33.3%) had disease progression. The use of chemotherapy, especially in the adjuvant setting, had a significant positive effect on 5-year OS (P=0.003) and 5-year DFS (P=0.004). Nodal involvement was associated with worse OS (P=0.049) but similar DFS (P=0.157). Lumpectomy was associated with better 5-year OS (P < 0.0001) and DFS (P=0.0002) compared with mastectomy.

Conclusion

MeBC represents a rare heterogeneous group of malignancies with poor prognosis. Adjuvant chemotherapy was associated with improved OS and DFS. Patients should be carefully selected for neoadjuvant chemotherapy.

Outcomes of Metaplastic Breast Cancer Versus Triple-Negative Breast Cancer: A Propensity Score Matching Analysis

PURPOSE

This study aims to compare the survival outcomes of metaplastic breast cancer (MPBC) with triple-negative breast cancer (TNBC) and identify prognostic factors that influence the survival outcomes of MPBC patients and TNBC patients.

METHODS

Patients with nonmetastatic MPBC or TNBC were reviewed from our database. Patients' clinicopathologic and molecular features were analyzed with respect to outcomes, including disease-free survival (DFS) and overall survival (OS). Propensity score matching (PSM) with a one-to-three matching between MPBC patients and TNBC patients was performed.

RESULTS

A total of 857 female patients (76 MPBC patients and 781 TNBC patients) were included in this study. A subgroup of triple-negative MPBC (n  =  60) was matched with TNBC (n  =  180) cases based on patient characteristics and treatments. Kaplan-Meier analysis indicated that the MPBC group was associated with worse OS and DFS before (P  =  0.0046 both) and after (P  =  0.011 and P  =  0.0046, respectively) PSM. Multivariable analysis revealed that a higher T stage (T > 2) (P  =  0.032) and higher lymph node stage (N3 vs. N0-2, P  =  0.012) were associated with worse OS after PSM. For DFS, the MPBC group (P  =  0.012), higher T stage (T > 2) (P  =  0.032), and higher lymph node stage (N3 vs. N0-2, P  =  0.045) were associated with worse DFS. Among the 76 MPBC patients, a higher T stage and mesenchymal differentiation were associated with worse OS (pT1/2 vs. pT3/4 and mesenchymal differentiation vs. other subtypes, P  =  0.007 and P  =  0.011, respectively).

CONCLUSIONS

Compared with TNBC, MPBC was associated with worse OS and DFS. Mesenchymal differentiation has a worse DFS than other subtypes of MPBC.

Clinicopathological characteristics and prognosis of metaplastic breast cancer versus triple-negative invasive ductal carcinoma: a retrospective analysis

BACKGROUND

Metaplastic breast cancer(MBC) is a specific pathological type of invasive breast cancer. There are few studies related to MBC due to its rarity. This study aimed to analyse the differences in clinicopathological characteristics and prognosis between Metaplastic breast cancer and triple-negative invasive ductal carcinoma (TN-IDC).

METHODS

We retrospectively compared the clinicopathological characteristics of patients diagnosed with MBC and TN-IDC at the Fourth Hospital of Hebei Medical University between 2011 and 2020 in a 1:2 ratio. The log-rank test was used to compare the two groups' disease-free survival (DFS) and overall survival (OS). For MBCs, we performed univariate and multivariate analyses using the Cox proportional hazards model to determine the characteristics that impacted OS and DFS.

RESULTS

A total of 81 patients with MBC and 162 patients with TN-IDC were included in this study. At initial diagnosis, MBC patients had larger tumour diameters(P = 0.03) and fewer positive lymph nodes (P = 0.04). Patients with MBC were more likely to have organ metastases after surgery (P = 0.03). Despite receiving the same treatment, MBC patients had worse DFS (HR = 1.66, 95%CI 0.90-3.08, P = 0.11) and OS (HR = 1.98, 95% CI 1.03-3.81, P = 0.04), and OS was statistically significant. Positive lymph nodes at initial diagnosis were associated with worse DFS (HR = 3.98, 95%CI 1.05-15.12, P = 0.04) and OS (HR = 3.70, 95%CI 1.03-13.34, P = 0.04) for patients with MBC. The efficacy of platinum-based agents is insensitive for MBC patients receiving chemotherapy. In addition, patients treated with preoperative chemotherapy had worse DFS compared to patients treated with postoperative chemotherapy (HR = 3.51, 95%CI 1.05-11.75, P = 0.04).

CONCLUSIONS

The clinicopathological characteristics and prognosis of MBC and TN-IDC differ in many ways. Further studies are required to determine suitable treatment guidelines for patients with MBC.

Metaplastic breast cancer: an all-round multidisciplinary consensus

Metaplastic breast cancer (MpBC) is a rare and aggressive histologic subtype of breast cancer (BC) characterized by the presence of at least two cellular types, commonly epithelial and mesenchymal components. Despite growing evidence that MpBC is a unique entity, it has long been treated as a variant of nonspecial type (NST) BC. MpBC typically shows the phenotype of triple-negative breast cancer (TNBC), but compared to NST-TNBC, it is a relatively chemorefractory tumor associated with worse outcomes. Therefore, there is an urgent need to develop management guidelines specifically for MpBC to improve the prognosis of patients with early MpBC. This expert consensus aims to guide diagnosis and standardize clinical management of early MpBC among treating physicians. We provide guidance on the challenging radiological and pathological diagnosis of MpBC. Evidence on the involvement of genetic predisposition in the development of MpBC is also explored. We emphasize the importance of a multidisciplinary approach for the treatment of patients with early MpBC. The optimal surgery and radiotherapy approach is presented, as well as the opportunity offered by novel therapeutic approaches to increase treatment response in this chemoresistant subtype. Appropriate management of patients with MpBC is critical to reduce the high risk of local and distant recurrence that characterizes this disease.

The conundrum of metaplastic breast cancer: a single Egyptian institution retrospective 10-year experience (2011-2020)

BACKGROUND

Metaplastic breast cancer (MetBC) still represents a conundrum owing to its peculiar histogenesis and molecular drivers that render it extremely resistant to standard chemotherapy with ultimate dismal survival.

AIM

Describe the Egyptian National Cancer Institute's (NCI-E) experience with MetBC regarding its clinicopathologic features, treatment, and survival outcomes.

PATIENTS AND METHODS

Between 2011 and 2020, all MetBC patients presented to NCI-E were retrospectively evaluated. Original clinicopathologic data, therapeutic modalities, pathologic response to neoadjuvant chemotherapy (NACT), recurrence, and date of last follow-up/death were obtained from archived charts.

RESULTS

A cohort of 135 females, the median age was 52 years, and median follow-up period was 40 months (range: 2.6-130.8). Two-thirds were triple negative (TN). Squamous carcinoma was prevalent in 74.8% followed by carcinoma with osseous/chondroid differentiation, spindle cell, and low-grade adenosquamous carcinoma encountered in 13.3, 7.4, and 4.5%, respectively. Modified radical mastectomy was done in 59.3%, and positive nodes (pN+) were depicted in 37.7%. Median Ki-67 was 45% (range: 10-88); grade III and lymphovascular invasion (LVI) were observed in 83.7 and 43.7%, respectively. Stage II was the most common (49%), whereas initial stage IV was encountered in 8.1%. Anthracyclines/taxane combinations were rampant in adjuvant/neoadjuvant settings. The latter was employed in 41 patients, with only 3 cases (7.3%) achieving pathologic complete response (pCR), while moderate/significant residual tumor burden was found in 83%. The 5-year DFS and OS were 56.4 and 57.6%, respectively. Spindle cell carcinoma showed the worst survival parameters in univariate analysis. On the multivariate level, higher tumor stage (pT3 & 4), Ki-67 ≥ 45%, and TN subtype were independent variables for worse DFS and OS; age ≥ 52 years and the presence of LVI were independent features for worse DFS, whereas pN+ was an independent parameter for worse OS.

CONCLUSIONS

This study further solidifies the dreadful response of MetBC to conventional chemotherapy regimens employed in common non-metaplastic pathologies. A radical shift in treatment standards tailored to combat the molecular landscape of this distinctive tumor is urgently needed. Immunotherapy and molecularly targeted agents demonstrated promising results in phase I and II trials with hopeful sooner implementation in phase III studies.

Mixed metaplastic carcinoma of the breast: a case report

A 68 year-old woman with no significant medical history discovered a lump incidentally in her left breast. The patient's initial imaging revealed a 4.6-cm irregular mass at 11:00 categorized as a BI-RADS 5 as well as an enlarged axillary lymph node and an area of 2.5 cm of heterogeneous calcifications in the 3 o'clock position. The 4.6-cm lesion was revealed to be infiltrating ductal carcinoma with a squamous component, mixed metaplastic carcinoma, which was strongly ER (100+)/PR (100+) positive, HER-2/Neu negative on FISH. The 2.5-cm calcifications were ductal carcinoma in situ. The patient completed neoadjuvant chemotherapy, and had an excellent response. After further discussion, the patient elected for breast conservation therapy and underwent a left wireless localized partial mastectomy with a left axillary dissection. Surgical pathology revealed a near complete pathologic response with only 8-mm residual tumour as well as a negative conversion of the clipped axillary node.

Transcriptomic alterations underlying metaplasia into specific metaplastic components in metaplastic breast carcinoma

BACKGROUND

Metaplastic breast carcinoma (MpBC) typically consists of carcinoma of no special type (NST) with various metaplastic components. Although previous transcriptomic and proteomic studies have reported subtype-related heterogeneity, the intracase transcriptomic alterations between metaplastic components and paired NST components, which are critical for understanding the pathogenesis underlying the metaplastic processes, remain unclear.

METHODS

Fifty-nine NST components and paired metaplastic components (spindle carcinomatous [SPS], matrix-producing, rhabdoid [RHA], and squamous carcinomatous [SQC] components) were microdissected from specimens obtained from 27 patients with MpBC for gene expression profiling using the NanoString Breast Cancer 360 Panel on a NanoString nCounter FLEX platform. BC360-defined signatures were scored using nSolver software.

RESULTS

Hierarchical clustering and principal component analysis revealed a heterogeneous gene expression profile (GEP) corresponding to the NST components, but the GEP of metaplastic components exhibited subtype dependence. Compared with the paired NST components, the SPS components demonstrated the upregulation of genes related to stem cells and epithelial-mesenchymal transition and displayed enrichment in claudin-low and macrophage signatures. Despite certain overlaps in the enriched functions and signatures between the RHA and SPS components, the specific differentially expressed genes differed. We observed the RHA-specific upregulation of genes associated with vascular endothelial growth factor signaling. The chondroid matrix-producing components demonstrated the upregulation of hypoxia-related genes and the downregulation of the immune-related MHC2 signature and the TIGIT gene. In the SQC components, TGF-β and genes associated with cell adhesion were upregulated. The differentially expressed genes among metaplastic components in the 22 MpBC cases with one or predominantly one metaplastic component clustered paired NST samples into clusters with correlation with their associated metaplastic types. These genes could be used to separate the 31 metaplastic components according to respective metaplastic types with an accuracy of 74.2%, suggesting that intrinsic signatures of NST may determine paired metaplastic type. Finally, the EMT activity and stem cell traits in the NST components were correlated with specimens displaying lymph node metastasis.

CONCLUSIONS

We presented the distinct transcriptomic alterations underlying metaplasia into specific metaplastic components in MpBCs, which contributes to the understanding of the pathogenesis underlying morphologically distinct metaplasia in MpBCs.

Prognosis and clinicopathological characteristics of metaplastic breast cancer: A meta-analysis

BACKGROUND

To compare the clinicopathological characteristics and prognosis of metaplastic breast cancer (MBC) and triple-negative breast cancer (TNBC).

METHODS

A meta-analysis was performed on relevant cohort or case-control studies retrieved by a literature search of the PubMed, EMBASE, Ovid, and Web of Science databases. Hazard ratio (HR) was used to evaluate disease-free survival (DFS) and overall survival (OS), and the odds ratio (OR) and corresponding 95% confidence interval (CI) was used to evaluate clinicopathological characteristics, including age, tumor diameter, lymph node metastasis status, distant metastasis status, TNM staging, and histological grade.

RESULTS

Nine studies were included in the meta-analysis. Compared with TNBC patients, the HRs for 5-year DFS and 5-year OS of those with MBC were 1.64 (95% confidence interval [CI] 1.36 - 1.98; P < .001) and 1.52 (95% CI 1.27 - 1.81; P < .001), respectively. The OR for age ≥ 50 years, tumor diameter ≤ 5 cm, lymph node-negative, distant metastasis, TNM stage III and IV, and histological grade 3 was 1.63 (95% CI 1.45-1.84), 0.29 (95% CI 0.14-0.58), 1.46 (95% CI 1.13-1.88), 1.59 (95% CI 0.89-2.81), 1.49 (95% CI 0.80-2.77), and 2.25 (95% CI 0.85-5.97), respectively.

CONCLUSION

Patients with MBC had worse prognosis than those with TNBC. Furthermore, regarding clinicopathological characteristics, patients with MBC mostly presented at ≥ 50 years of age, with tumor diameter > 5 cm, and negative lymph nodes at first diagnosis. Moreover, there were no statistically significant differences in the occurrence of distant metastasis, TNM stages III and IV, or histological grade 3. MBC treatment was not assessed in this study. Data from randomized controlled trials are needed to guide the treatment of patients with MBC.

Metaplastic Breast Cancer: Mesenchymal Subtype Has Worse Survival Outcomes

Background

Metaplastic breast carcinoma (MBC) is a rare type of breast cancer that accounts for 0.2-1% of all breast cancers. To date, there are only few institutional studies comparing survival rates between different subtypes. In this retrospective cohort study, we aim to evaluate factors effecting survival rates of different subtypes of MBC.

Methods

This retrospective cohort study observed 118 nonmetastatic MBC patient records extracted from 15,244 breast cancer cases between December 2000 and December 2020. In order to analyze factors effecting survival rates of mesenchymal subtype of MBC, all cases are classified as mesenchymal (n = 45) and other (n = 48). Twenty-five cases could not be sub-classified due to the missing data. Univariate and multivariate logistic regression analyses were performed to define factors associated with survival rates.

Results

Of the 15,244 cases, 118 (0.8%) were nonmetastatic MBC. 105 were triple negative and 12 were nonluminal HER2. There was no significant difference between mesenchymal and other subgroups for age, median tumor size, AJCC staging, and type of surgery. Of the five local recurrences with known subgroup, four of them had mesenchymal subtype. It is demonstrated that mesenchymal subtype was significantly associated with worse 5-year disease-free survival and disease-specific survival (HR: 2.35 [1.01-5.48], p = 0.049, and HR: 3.16 [1.06-9.47], p = 0.040 with 95% CI, respectively).

Conclusion

This study is one of the few studies presenting the survival outcomes of subtypes of MBCs. Nonetheless, it is the only study demonstrating that mesenchymal subtype had worse survival outcomes. Further studies are needed to determine the outcome of different subtypes of MBCs.

Metaplastic breast cancers and triple-negative breast cancers of no special type: are they prognostically different? A systematic review and meta-analysis

BACKGROUND AND AIMS

Metaplastic breast cancer (MBC) and triple-negative (TN) BC of no special type are often confounded with each other in terms of survival and prognosis. In this systematic study and meta-analysis, we evaluated the prognosis of each of these two different diagnoses.

METHODS

We conducted a systematic literature search and review using the MOOSE guidelines, through PUBMED database, the Ovid MEDLINE database, and the ISI Web of Science Citation Index Expanded (SCI Expanded). Overall survival (OS) and disease-free survival (DFS) were the main outcomes considered.

RESULTS

Our review eventually selected six independent studies, with a total of more than 59 519 patients. MBC was found to associate with worse OS compared to TNBC of no special type, with a significant 40% increased risk of death [summary hazard ratio (SHR) = 1.40, 95% confidence interval (CI): 1.30-1.50]. We found neither heterogeneity ( I2 = 0%) nor evidence of publication bias ( P = 0.82 and P = 0.49 by Begg's and Egger's test, respectively) between studies. No statistically significant difference was found between MBC and TNBC of no special type in terms of DFS (SHR = 1.17, 95% CI: 0.80-1.71).

CONCLUSION

This study demonstrates that TNBC of no special type and MBC have comparable DFS, although the latter presents a significantly worse prognosis in terms of OS. Despite DFS being similar in both subtypes, this did not result in significant OS benefits, with MBC score being the worse of the two diseases.

Differences of Clinicopathological Features between Metaplastic Breast Carcinoma and Nonspecific Invasive Breast Carcinoma and Prognostic Profile of Metaplastic Breast Carcinoma

Introduction

Metaplastic breast carcinoma is a rare special type of breast cancer, which has distinguished clinical characteristics. We aimed to evaluate the clinicopathological features of metaplastic breast carcinoma compared with nonspecific invasive breast carcinoma and study the prognosis of metaplastic breast carcinoma.

Methods

We reviewed metaplastic breast carcinoma cases (n = 37) from January 2000 to December 2021 and nonspecific invasive breast carcinoma cases (n = 433) from January 2019 to December 2020 extracted from our institution retrospectively. The following variables were recorded, including the patients' general information, complications, T stage, expression of estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2, Ki-67, molecular subtyping, lymph node status, skin or chest wall involvement, vessel carcinoma embolus, therapy modality (surgical treatments, chemotherapy, and radiotherapy), and survival.

Results

Patients with metaplastic breast carcinoma had more advanced disease than patients with nonspecific invasive breast carcinoma (T stage: P=0.0011). A greater proportion of metaplastic breast carcinoma presented with triple-negative breast cancer than nonspecific invasive breast carcinoma (79.41% vs. 12.47%, P ≤ 0.001). Our study showed that the skin or chest wall invasion was more frequent in metaplastic breast carcinoma patients (11.76% vs. 1.62%, P=0.005). The 5-year survival rate for metaplastic breast carcinoma patients was 57.66% (95% CI: 0.3195∼0.7667). No local recurrence was observed while distant metastasis occurred in 33.33% of patients with metaplastic breast carcinoma. Death due to disease occurred in 24.24% of patients with metaplastic breast carcinoma.

Conclusion

The majority of metaplastic breast carcinoma patients had more advanced disease and triple-negative disease than nonspecific invasive breast carcinoma patients. Also, metaplastic breast carcinoma patients had frequent skin or chest wall invasion and a high rate of distant metastasis and mortality.

Metaplastic carcinoma of the breast with squamous differentiation: prognostic factors and multidisciplinary treatment

Background

The objective of this study was to analyze the characteristics of patients diagnosed with metaplastic carcinoma of the breast with squamous differentiation and to identify the particular clinical and histological characteristics that need to be taken into account in this type of tumors.

Case presentation

Retrospective observational study of two patients managed at our hospital between 2014 and 2020 (15 months mean follow-up), plus all cases published in the last 7 years (8 patients). Thus, a total of 10 cases were analyzed, all with less than 2 years mean global survival. Studied variables were: age, medical background, tumor size, axillary involvement, radiological characteristics, surgical approach, complementary treatments, histologic characteristics, and progression of the disease. In 50% of cases, the disease appeared as a palpable mass of rapid growth, associated with axillary infiltration; 80% of the tumors were triple negative; 30% of them progressed to distant metastatic disease in 30%.

Conclusions

This unusual carcinoma requires a complex multidisciplinary treatment. Its prognosis is unfavorable due to its high local aggressiveness, with rapid progression and appearance of metastatic disease. The predominance of different histological components may determine the response to medical treatments.

Metaplastic Breast Carcinoma Presenting as a Mixed Solid and Cystic Lesion

The objective of this paper is to report a rare presentation of metaplastic breast carcinoma (MBC) as a mixed solid/cystic mass and emphasize the possibility of having a different biopsy report and final diagnosis.

MBC is a rare type of breast cancer consisting of mesenchymal or mixed mesenchymal and epithelial components. It is believed to result from the conversion of glandular cells into non-glandular cells through various forms of mutations. It is common in females and more frequent in older women. MBC is a triple-negative breast cancer (progestin receptor, estrogen receptor, and human epidermal growth factor receptor 2) with a very poor prognosis when compared with other types of breast cancers.

This is a case of an 84-year-old woman presenting with rapidly growing mixed solid and cystic breast mass with a final diagnosis of MBC. The initial biopsy report was high-grade ductal carcinoma in situ. This is an unusual presentation of MBC.

Chemotherapy significantly improves long-term survival of small lesion node negative metaplastic breast carcinoma in T1c population rather than T1a and T1b

Metaplastic breast carcinoma (MpBC) is considered a highly aggressive disease, the outcome of chemotherapy on small lesions (T1abcN0M0) MpBC patients remain unclear. We identified 890 female MpBC patients in the Surveillance, Epidemiology, and End Results (SEER) database from 2000 to 2016. After propensity score matching (PSM), 584 patients were matched. Survival probability was compared among T1a, T1b, and T1c patients and between patients with and without chemotherapy using Kaplan–Meier analysis and Cox proportional hazard analysis. Significance was set at two-sided P < 0.05. We classified 49, 166, and 675 patients as T1a, T1b, and T1c MpBC, respectively. The chemotherapy group included 404 patients (45.4%). Following PSM, survival analysis indicated that the patients who underwent chemotherapy had higher OS (P = 0.0002) and BCSS (P = 0.0276) in the T1c substage, but no significant difference was detected in T1a or T1b patients. In this population-based study, small lesion MpBC showed a favorable prognosis. Chemotherapy improved the prognosis of T1c MpBC patients but not T1a and T1b patients to a beneficial extent. Our findings may offer novel insight into a therapeutic strategy for MpBC.

Survival in metaplastic breast carcinoma: A case series

BACKGROUND

Metaplastic breast carcinoma (MBC) is a rare type of breast cancer (0.20-1.00% of all cases). With a more aggressive clinical course, MBC frequently presents as a triple-negative subtype.

OBJECTIVE

To describe a case series, analyzing patients survival in four MBC cases.

METHODS

The cases were obtained from 532 medical records of breast cancer patients (0.7% of the total).

RESULTS

All patients were female. Mean patient age was 49 years (range: 38-60 years). Mean tumor size was 8.9 cm (range: 3.0-15.5 cm). Mastectomy was performed in three cases. One patient had axillary nodal metastasis. All underwent chemotherapy and three received radiation therapy after surgery.

CONCLUSIONS

With a mean follow-up of 36 months (range: 10-60 months), one case had a tumor recurrence (25%). Three patients (75%) died from metastatic disease and one (25%) is still alive and free of disease.

A Multicenter Phase II Trial of Ipilimumab and Nivolumab in Unresectable or Metastatic Metaplastic Breast Cancer: Cohort 36 of Dual Anti-CTLA-4 and Anti-PD-1 Blockade in Rare Tumors (DART, SWOG S1609)

PURPOSE

Metaplastic breast cancer (MpBC) is a rare aggressive subtype that responds poorly to cytotoxics. Median survival is approximately eight months for metastatic disease. We report results for advanced MpBC treated with ipilimumab+nivolumab, a cohort of S1609 for rare cancers (DART: NCT02834013).

METHODS

Prospective, open-label, multicenter phase II (two-stage) trial of ipilimumab (1mg/kg IV q6weeks) plus nivolumab (240mg IV q2weeks) for advanced MpBC. Primary endpoint was objective response rate (ORR). Secondary endpoints included progression-free survival (PFS), overall survival (OS) and toxicity.

RESULTS

Overall, 17 evaluable patients enrolled. Median age was 60 years (26-85); median number of prior therapy lines, 2 (0-5). ORR was 18%; 3/17 patients achieved objective responses (1 complete, 2 partial responses) (2 spindle cell, 1 chondromyxoid histology), which are ongoing at 28+, 33+ and 34+ months, respectively. Median PFS and OS were 2 and 12 months, respectively. Altogether, 11 patients (65%) experienced adverse events (AEs), including one grade 5 AE. Eight patients (47%) developed an immune-related AE (irAE); with adrenal insufficiency observed in all three responders. Responses occurred in tumors with low tumor mutational burden, low PD-L1 and absent TILs.

CONCLUSION

The ipilimumab and nivolumab combination showed no new safety signals and met its primary endpoint with 18% ORR in advanced, chemotherapy-refractory MpBC. All responses are ongoing at >2 to almost 3 years later. The effect of ipilimumab and nivolumab was associated with exceptional responses in a subset of patients versus no activity. This combination warrants further investigation in MpBC, with special attention to understanding mechanism of action, and carefully designed to weigh against the significant risks of irAEs.

Clinicopathologic Characteristics and Outcome Descriptors of Metaplastic Breast Carcinoma

CONTEXT.—

Metaplastic breast carcinoma is an aggressive form of breast cancer that accounts for 0.5% to 3% of all breast cancers.

OBJECTIVE.—

To study the clinicopathologic characteristics and outcomes of this rare disease.

DESIGN.—

Retrospective study of patients with a diagnosis of metaplastic breast carcinoma between 2000 and 2019. Hematoxylin-eosin-stained slides were reviewed and additional clinical data were obtained from electronic medical records. Univariable and multivariable Cox proportional hazard regression analyses were used to determine associations between overall survival and several clinicopathologic variables.

RESULTS.—

Of the 125 patients with metaplastic breast carcinoma identified, only patients with high-grade disease (N = 115) were included in the data analysis. A total of 38 participants (33%) were white, 66 (57%) were African American, and 11 (10%) belonged to other ethnicities. The median age at diagnosis was 57 years. The median tumor size was 3 cm. Heterologous histology was seen in 30% of cases. Multivariable analyses showed that patients with a larger tumor size had worse overall survival (hazard ratio [HR], 1.25; 95% CI, 1.10-1.44; P < .001). Distant metastatic disease was also associated with worse overall survival on multivariable analysis (HR, 10.27; 95% CI, 2.03-55.54; P = .005). In addition to treatment with either partial or complete mastectomies, 84 patients (73%) received chemotherapy. Multivariable analyses showed that chemotherapy had no effect on overall survival (HR, 0.53; 95% CI, 0.09-6.05; P = .55).

CONCLUSIONS.—

A larger tumor size and distant metastatic disease are associated with worse overall survival in patients with metaplastic breast carcinoma. Additional studies are needed to further characterize our findings.

Benefit of adjuvant chemotherapy in patients with special histology subtypes of triple-negative breast cancer: a systematic review

PURPOSE

Breast cancer (BC) is a leading cause of morbidity, disability, and mortality in women, worldwide; triple-negative BC (TNBC) is a subtype traditionally associated with poorer prognosis. TNBC special histology subtypes present distinct clinical and molecular features and sensitivity to antineoplastic treatments. However, no consensus has been defined on the best adjuvant therapy. The aim of the review is to study the evidence from literature to inform the choice of adjuvant treatments in this setting.

METHODS

We systematically searched literature assessing the benefit of adjuvant chemotherapy in patients with TNBC special histotypes (PROSPERO: CRD42020153818).

RESULTS

We screened 6404 records (15 included). All the studies estimated the benefit of different chemotherapy regimens, in retrospective cohorts (median size: 69 patients (range min-max: 17-5142); median follow-up: 51 months (range: 21-268); mostly in Europe and USA). In patients with early-stage adenoid cystic TNBC, a marginal role of chemotherapy was reported. Similar for apocrine TNBC. Medullary tumors exhibited an intrinsic good prognosis with a limited role of chemotherapy, suggested to be modulated by the presence of tumor-infiltrating lymphocytes. A significant impact of chemotherapy on the overall survival was estimated in patients with metaplastic TNBC. Limitations were related to the retrospective design of all the studies and heterogeneous treatments received by the patients.

CONCLUSIONS

There is potential opportunity to consider treatment de-escalation and less intense therapies in some patients with early, special histology-type TNBC. International efforts are indispensable to validate prospective clinical decision models.

An Update on the Molecular Pathology of Metaplastic Breast Cancer

Metaplastic breast cancer (MpBC) is a fascinating morphologic sub-type of breast cancer, characterised by intra-tumoural heterogeneity. By definition, these tumors show regions of metaplasia that can present as spindle, squamous, chondroid or even osseous differentiation. MpBC are typically triple-negative, and are therefore not targetable with hormone therapy or anti-HER2 therapies, leaving only chemotherapeutics for management. MpBC are known for their aggressive course and poor response to chemotherapy. We review herein the pathology and molecular landscape of MpBC and discuss opportunities for targetted therapies as well as immunotherapies.

A comprehensive overview of metaplastic breast cancer: clinical features and molecular aberrations

Metaplastic breast cancer (MpBC) is an exceedingly rare breast cancer variant that is therapeutically challenging and aggressive. MpBC is defined by the histological presence of at least two cellular types, typically epithelial and mesenchymal components. This variant harbors a triple-negative breast cancer (TNBC) phenotype, yet has a worse prognosis and decreased survival compared to TNBC. There are currently no standardized treatment guidelines specifically for MpBC. However, prior studies have found that MpBC typically has molecular alterations in epithelial-to-mesenchymal transition, amplification of epidermal growth factor receptor, PI3K/Akt signaling, nitric oxide signaling, Wnt/β-catenin signaling, altered immune response, and cell cycle dysregulation. Some of these molecular alterations have been studied as therapeutic targets, in both the preclinical and clinical setting. This current review discusses the histological organization and cellular origins of MpBC, molecular alterations, the role of radiation therapy, and current clinical trials for MpBC.

Tumor-infiltrating lymphocyte abundance and programmed death-ligand 1 expression in metaplastic breast carcinoma: implications for distinct immune microenvironments in different metaplastic components

Both stromal tumor-infiltrating lymphocytes (sTILs) and programmed death-ligand 1 (PD-L1) affect responses to immunotherapy; however, the extent of sTIL and PD-L1 expression within various metaplastic components in metaplastic breast carcinoma (MBC), which are critical for the characterization of immune microenvironments, remains unreported. We profiled sTIL infiltration and PD-L1 expression in different metaplastic components of specimens from 82 MBC patients. The overall positivity for high or intermediate (H/I) sTIL, immune cell-PD-L1 (IcPD-L1), and tumor cell-PD-L1 (TcPD-L1) was 34.1%, 47.6%, and 17.1%, respectively, but differences specific to MBC subtypes and each metaplastic component existed. Squamous cell carcinoma exhibited the highest positivity rates of sTIL(H/I) (50.0%) and IcPD-L1 (66.7%), while matrix-producing carcinoma had the lowest respective rates (14.3% and 28.6%). The positivity rates of sTIL(H/I) and IcPD-L1 were the highest in squamous component (Sq) and the lowest in chondroid component (Ch). All cases that had discordant sTIL categories between carcinoma of no special type (NST) and metaplastic components showed sTIL(H/I) positivity higher in Sq, but lower in spindled component (Sp) and Ch. While there was no pattern of higher IcPD-L1-positivity in Sp, six of the seven cases that were TcPD-L1-discordant between NST and Sp were TcPD-L1-positive in Sp, suggesting a trend for higher TcPD-L1 in Sp. The diagnostic predictability of total tumor IcPD-L1 positivity based on IcPD-L1 positivity in Sq and Ch was 95.2% and 33.3%, respectively. Multivariate analysis showed that sTIL(H/I) positivity, but not PD-L1 positivity, correlated with better survival. Our data implicate distinct immune microenvironments in different metaplastic components in MBC, which may have immunopathologic, diagnostic, and therapeutic significance.

Metaplastic breast cancer: Prognostic and therapeutic considerations

INTRODUCTION

Metaplastic breast cancer (MBC) is a rare condition of breast tumor with different subtypes, considered a disease with worse prognosis; treatments and survival are often unclear and conflicting.

METHODS

We consecutively collected 153 primary MBCs of different subtypes. Breast surgery, neoadjuvant or adjuvant treatment, clinic-pathological factors, number and type of events during follow-up were considered to evaluate overall survival (OS) and invasive disease-free survival (IDFS).

RESULTS

The majority of MBC was triple-negative (TN) subtype (88.7%), G3 (95.3%), pN0 (70.6%), and with high levels of Ki-67 (93.5%). For OS and IDFS, no significant associations were seen between the different MBC subtypes. The matched triple-negative MBC (TNMBC) and ductal TNBC cohorts had similar prognosis both in terms of OS (p = .411) and IDFS (p = .981). We observed a positive trend for TNMBC patients treated in the adjuvant setting with the cyclofosfamide, methotrexate, 5-fluorouracil protocol for better OS (p = .090) and IDFS (p = .087). A poor or absent response rate was observed in the neoadjuvant setting.

CONCLUSION

Our results demonstrate that metaplastic and ductal breast cancers with TN phenotype are similar in terms of overall and disease-free survival. Metaplastic cancers are poorly responsive to neoadjuvant treatment, and in the absence of novel targeted therapies, surgical treatment remains the first choice.

Patterns of Care and Survival of Metastatic Metaplastic Breast Cancer Patients

Background: Metaplastic breast cancer (MBC) is a rare, aggressive variant of breast cancer, usually triple negative disease and chemotherapy refractory. Despite this, the standard of care remains the same as invasive ductal breast cancer. We sought to analyze patterns of care and outcomes among patients with metastatic MBC.

Methods: Patients over 18 years diagnosed with metastatic MBC from 2004-2015 were identified in the National Cancer Database (NCDB). Clinical and demographic details were compared between two groups (chemotherapy vs no chemotherapy). Logistic regression was performed to assess for predictors of receiving chemotherapy. The Kaplan-Meier method was used to assess overall survival (OS) and Cox regression analysis was used to assess the impact of covariates on OS.

Results: There were 7,580 patients with MBC of which 417 (5.5%) presented with metastatic disease. Median age was 65 years (interquartile range (IQR) 54-76) and median follow up for living patients was 48 months (IQR 31-77). One hundred and fifty-six (37.4%) patients received chemotherapy. On multivariable logistic regression analyses, treatment at an academic facility was associated with an increased likelihood of receiving chemotherapy (OR 3.14, 95% CI 1.95-5.03, p<0.001) while age ≥65 years (OR 0.54, 95% CI 0.34-0.86, p=0.009) and receipt of hormonal therapy (OR 0.35, 95% CI 0.15-0.85, p=0.021) were associated with a decreased likelihood of receiving chemotherapy. On multivariable Cox regression analysis, higher Charlson-Deyo score (hazard ratio (HR) 1.35-1.78, p<0.05) was associated with worse survival while receipt of chemotherapy (HR 0.76, 95% CI 0.59-0.99, p=0.041) and having insurance (HR 0.34-0.47, p<0.05) were associated with improved survival. Patients who received chemotherapy had improved median (twelve versus eight months), one-year (51% versus 38%), and two-year (35% versus 21%) OS, as compared to those who did not receive chemotherapy (p=0.006). 

Conclusions: In this study of MBC patients, there was a survival benefit with palliative chemotherapy in the setting of metastatic disease. As expected, treatment was most often given to younger patients.

Changes in Peripheral and Local Tumor Immunity after Neoadjuvant Chemotherapy Reshape Clinical Outcomes in Patients with Breast Cancer

PURPOSE

The recent approval of anti-programmed death-ligand 1 immunotherapy in combination with nab-paclitaxel for metastatic triple-negative breast cancer (TNBC) highlights the need to understand the role of chemotherapy in modulating the tumor immune microenvironment (TIME).

EXPERIMENTAL DESIGN

We examined immune-related gene expression patterns before and after neoadjuvant chemotherapy (NAC) in a series of 83 breast tumors, including 44 TNBCs, from patients with residual disease (RD). Changes in gene expression patterns in the TIME were tested for association with recurrence-free (RFS) and overall survival (OS). In addition, we sought to characterize the systemic effects of NAC through single-cell analysis (RNAseq and cytokine secretion) of programmed death-1-high (PD-1^HI) CD8⁺ peripheral T cells and examination of a cytolytic gene signature in whole blood.

RESULTS

In non-TNBC, no change in expression of any single gene was associated with RFS or OS, while in TNBC upregulation of multiple immune-related genes and gene sets were associated with improved long-term outcome. High cytotoxic T-cell signatures present in the peripheral blood of patients with breast cancer at surgery were associated with persistent disease and recurrence, suggesting active antitumor immunity that may indicate ongoing disease burden.

CONCLUSIONS

We have characterized the effects of NAC on the TIME, finding that TNBC is uniquely sensitive to the immunologic effects of NAC, and local increases in immune genes/sets are associated with improved outcomes. However, expression of cytotoxic genes in the peripheral blood, as opposed to the TIME, may be a minimally invasive biomarker of persistent micrometastatic disease ultimately leading to recurrence.

Molecular Features of Metaplastic Breast Carcinoma: An Infrequent Subtype of Triple Negative Breast Carcinoma

Metaplastic breast carcinoma (MBC) is a heterogeneous group of infrequent invasive carcinomas that display differentiation of the neoplastic epithelium towards squamous cells and/or mesenchymal-type elements. Most MBC have a triple negative phenotype and poor prognosis. Thus, MBC have worse survival rates than other invasive breast carcinomas, including other triple negative breast carcinomas (TNBC). In this study, we reviewed the molecular features of MBC, pointing out the differences among subtypes. The most frequently mutated genes in MBC were TP53 and PIK3CA. Additionally, mutations in the other genes of the PI3K/AKT pathway indicated its importance in the pathogenesis of MBC. Regarding copy number variations (CNVs), MYC was the most frequently amplified gene, and the most frequent gene loss affected the CDKN2A/CDKN2B locus. Furthermore, the pattern of mutations and CNVs of MBC differed from those reported in other TNBC. However, the molecular profile of MBC was not homogeneous among histological subtypes, being the alterations in the PI3K pathway most frequent in spindle cell carcinomas. Transcriptomic studies have demonstrated an epithelial to mesenchymal program activation and the enrichment of stemness genes in most MBC. In addition, current studies are attempting to define the immune microenvironment of these tumors. In conclusion, due to specific molecular features, MBC have a different clinical behavior from other types of TNBC, being more resistant to standard chemotherapy. For this reason, new therapeutic approaches based on tumor molecular characteristics are needed to treat MBC.

EHD2 is a Predictive Biomarker of Chemotherapy Efficacy in Triple Negative Breast Carcinoma

EHD2 is a mechanotransducing ATPase localized in caveolae invaginations at the plasma membrane. EHD2 has recently been associated with several human cancers, however the significance of EHD2 transcript levels in cancer prognosis remains debated. Breast cancer is the most commonly occurring cancer in women and prognosis is variable depending on the subtypes. Triple negative breast cancer (TNBC) often has a poor therapeutic response. The aim of this study was to assess the prognostic significance of EHD2 transcripts and protein expression levels in breast carcinomas. We found that low EHD2 levels were associated with enhanced proliferation, migration and invasion of TNBC cells. EHD2 expression was significantly reduced in TNBC tissues and the loss of EHD2 led to higher expression of the pro-tumoral cytokine IL-8. In apparent contradiction with in vitro data, multivariate analysis of two independent cohorts of breast cancer patients revealed that low EHD2 was in fact associated with good prognosis in the highly proliferative TNBC subtype. Accordingly, TNBC low EHD2 expressers were found to benefit the most from chemotherapy when compared to all subtypes of breast cancers. Our study validates EHD2 expression level as an independent prognostic factor of metastasis-free survival and as a new predictive marker of chemotherapy efficacy in TNBC patients.

Assessment of outcomes and novel immune biomarkers in metaplastic breast cancer: a single institution retrospective study

BACKGROUND

Metaplastic breast cancer remains poorly characterized given its rarity and heterogeneity. The majority of metaplastic breast cancers demonstrate a phenotype of triple-negative breast cancer; however, differences in clinical outcomes between metaplastic breast cancer and triple-negative breast cancer in the era of third-generation chemotherapy remain unclear.

METHODS

We compared the clinical outcomes between women with metaplastic breast cancer and women with triple-negative breast cancer diagnosed between 1994 and 2014. Metaplastic breast cancer patients were matched 1:3 to triple-negative breast cancer patients by stage and age at diagnosis. Distant disease-free survival (DDFS) and overall survival (OS) were estimated using Kaplan Meier methods and Cox proportional hazard regression models. Immune checkpoint markers were characterized by immunohistochemistry in a subset of samples.

RESULTS

Forty-four metaplastic breast cancer patients (stage I 14%; stage II 73%; stage III 11%; stage IV 2%) with an average age of 55.4 (± 13.9) years at diagnosis. Median follow-up for the included metaplastic breast cancer and triple-negative breast cancer patients (n = 174) was 2.8 (0.1-19.0) years. The DDFS and OS between matched metaplastic breast cancer and triple-negative breast cancer patients were similar, even when adjusting for clinical covariates (DDFS: HR = 1.64, p = 0.22; OS: HR = 1.64, p = 0.26). Metaplastic breast cancer samples (n = 27) demonstrated greater amount of CD163 in the stroma (p = 0.05) and PD-L1 in the tumor (p = 0.01) than triple-negative breast cancer samples (n = 119), although more triple-negative breast cancer samples were positive for CD8 in the tumor than metaplastic breast cancer samples (p = 0.02).

CONCLUSIONS

Patients with metaplastic breast cancer had similar outcomes to those with triple-negative breast cancer based on DDFS and OS. The immune checkpoint marker profile of metaplastic breast cancers in this study may prove useful in future studies attempting to demonstrate an association between immune profile and survival.

Response to mTOR and PI3K inhibitors in enzalutamide-resistant luminal androgen receptor triple-negative breast cancer patient-derived xenografts

Luminal androgen receptor (LAR) breast cancer accounts for 10% of all triple-negative breast cancers (TNBC). Anti-androgen therapy for this subtype is in development, but yields only partial clinical benefits. In this study, we aimed to characterize the genomic alterations of LAR TNBC, to analyze activation of the PI3K signaling pathway and to compare the response to PI3K pathway inhibitors with that to anti-androgen therapy in patient-derived xenografts (PDX) of LAR TNBC.

Methods: Four LAR PDX models were identified, on the basis of their transcriptomic profiles, in a cohort of 57 PDX models of TNBC. The expression of AR-related genes, basal and luminal cytokeratins and EMT genes was analyzed by RT-PCR and IHC. AKT1 and PIK3CA mutations were identified by targeted NGS, and activation of the PI3K pathway was analyzed with a reverse-phase protein array. Three LAR PDXs with a PIK3CA or AKT1 mutation were treated with the AR inhibitor enzalutamide, a PI3K inhibitor, a dual PI3K-mTOR inhibitor and a mTORC1-mTORC2 inhibitor. Finally, we screened a clinical cohort of 329 TNBC for PIK3CA and AKT1 hotspot mutations.

Results: LAR TNBC PDXs were significantly enriched in PIK3CA and AKT1 mutations, and had higher levels of luminal-androgen-like gene expression and a higher PI3K pathway protein activation score than other TNBC subtypes. Immunohistochemistry analysis revealed strong expression of the luminal cytokeratin CK18 and AR in three LAR PDX models. We found that mTOR and PI3K inhibitors had marked antitumor activity in vivo in PDX harboring genomic alterations of PIK3CA and AKT1 genes that did not respond to the AR antagonist enzalutamide. PIK3CA mutations were detected in more than one third of AR+ TNBC from patients (38%), and only 10% of AR-negative TNBC.

Conclusion: Our results for PDX models of LAR TNBC resistant to enzalutamide indicate that PIK3CA and AKT1 are potential therapeutic targets.

Metaplastic Carcinoma of the Breast: Analysis of 38 Cases from a Single Institute

OBJECTIVE

To evaluate the pathological and radiological features, hormone profiles, surgery and treatment methods of metaplastic breast carcinoma cases diagnosed at our center in the light of current literature.

MATERIAL AND METHOD

A total of 38 metaplastic breast cancer cases diagnosed between 2006-2018 at our center were included in the study. The patients were evaluated in terms of age, tumor size, localization, histological grade, hormone profiles (ER, PR, Her2-neu), American Joint Committee on Cancer (AJCC) Tumor, Lymph node status, Metastases (TNM) stage, progression, survival, radiological features, types of surgery and therapy modalities (chemotherapy and / or radiotherapy).

RESULTS

The age of the patients ranged between 32 and 95 years. Pathological evaluation of cases showed that 14 were pure epithelial (IC-NST + squamous cell carcinoma) and 24 were metaplastic carcinomas with mesenchymal differentiation. Ductal carcinoma in situ (DCIS) was accompanying an invasive component in twenty cases. Seventeen patients had lymph node metastasis. Twelve patients developed distant metastasis. Thirty patients were triple negative for hormone receptors. The mean follow-up period of the patients was 34 months. The estimated life expectancy was 116 months. All of the patients received chemotherapy and 28 patients received adjuvant radiotherapy. There was no correlation between tumor size and lymph node or distant metastasis in our series. Our findings are consistent with the literature.

CONCLUSION

Metaplastic breast carcinoma is a rare entity among breast carcinomas. Metaplastic carcinomas of the breast draw attention with the differences in their clinical course and the radiological and pathological heterogeneity.

Comparison of outcomes between metaplastic and triple-negative breast cancer patients

Purpose

Metaplastic breast cancer (MBC) is a rare, aggressive variant of breast cancer that has been associated with poor clinical outcomes, as has triple-negative breast (TNBC) cancer. Limited studies compare the clinical characteristics and prognosis of MBC to TNBC. This study uses a large, contemporary US cancer database to compare clinical characteristics and survival outcomes for patients with MBC to those with TNBC.

Methods

The National Cancer Database was queried for women with cT1-4N1-3M0 MBC or TNBC diagnosed between 2004 and 2013 and treated with definitive surgery. Chi-squared analysis was performed to determine differences between the cohorts. Kaplan-Meier curves compared overall survival (OS), and Cox regression determined patient factors associated with OS.

Results

Altogether, 55,847 patients met the inclusion criteria; 50,705 (90.8%) had TNBC and 5,142 (9.2%) had MBC. Most patients had no comorbid conditions (82%), N0 disease (71%), poorly differentiated histology (77%), received chemotherapy (87%), and received radiation therapy (60%). Amongst all patients, patients with TNBC disease were observed to have greater OS than those with MBC (5-year OS 72.0% vs 55.8%, p < 0.001). The greater observed OS for patients with TNBC persisted when controlling for stage and when comparing propensity score matched cohorts. On Cox regression, lower age, T1 status, N0 status, chemotherapy, TNBC disease, and radiation therapy (RT) were associated with improved OS.

Conclusions

MBC had an association with poorer OS compared to TNBC, while RT and chemotherapy receipt were associated with improved OS for patients regardless of stage. Further studies are needed to corroborate the conclusions herein.

•

Metaplastic breast cancer is associated with poor clinical outcomes.

•

Metaplastic breast cancer associated with worse survival than patients with triple negative invasive ductal carcinoma.

•

Radiation therapy and chemotherapy associated with improved survival for patients with metaplastic breast cancer.

Metaplastic breast carcinoma: a clinical-pathologic study of 97 cases with subset analysis of response to neoadjuvant chemotherapy

Metaplastic breast carcinoma is a rare heterogeneous category of breast cancer, often associated with a poor prognosis. Clinical-pathologic studies with respect to varied morphologic subtypes are lacking. There is also a dearth of studies assessing the response of metaplastic breast carcinoma to neoadjuvant chemotherapy. Cases of metaplastic breast carcinoma diagnosed between 2007 and 2017 were identified. Various clinical-pathologic variables were tested for association with survival. Patients who underwent neoadjuvant chemotherapy were assessed for pathologic response. Median age at diagnosis with metaplastic breast carcinoma was 64 years. With a median follow-up of 39 months, 26 patients (27%) recurred (24 distant and 2 loco-regional). The overall survival rate of the cohort was 66% (64/97). A number of variables were associated with survival in univariable analysis; however, in multivariable analysis, only lymph node status and tumor size (pT3 vs. pT1/2) were significantly associated with all survival endpoints: recurrence-free survival, distant recurrence-free survival, overall survival and breast cancer-specific survival. Twenty-nine of 97 (30%) patients with metaplastic breast carcinoma received neoadjuvant chemotherapy. Five (17%) patients achieved pathologic complete response. Matrix-producing morphology was associated with higher probability of achieving pathologic complete response (p = 0.027). Similar to other breast cancer subtypes, tumor size and lymph node status are prognostic in metaplastic carcinomas. The pathologic complete response rate of metaplastic breast carcinoma in our cohort was 17%, higher than previously reported. Although the matrix-producing subtype was associated with pathologic complete response, there was no survival difference with respect to tumor subtypes.

A large collection of integrated genomically characterized patient-derived xenografts highlighting the heterogeneity of triple-negative breast cancer

Triple-negative breast cancer (TNBC) represents 10% of all breast cancers and is a very heterogeneous disease. Globally, women with TNBC have a poor prognosis, and the development of effective targeted therapies remains a real challenge. Patient-derived xenografts (PDX) are clinically relevant models that have emerged as important tools for the analysis of drug activity and predictive biomarker discovery. The purpose of this work was to analyze the molecular heterogeneity of a large panel of TNBC PDX (n = 61) in order to test targeted therapies and identify biomarkers of response. At the gene expression level, TNBC PDX represent all of the various TNBC subtypes identified by the Lehmann classification except for immunomodulatory subtype, which is underrepresented in PDX. NGS and copy number data showed a similar diversity of significantly mutated gene and somatic copy number alteration in PDX and the Cancer Genome Atlas TNBC patients. The genes most commonly altered were TP53 and oncogenes and tumor suppressors of the PI3K/AKT/mTOR and MAPK pathways. PDX showed similar morphology and immunohistochemistry markers to those of the original tumors. Efficacy experiments with PI3K and MAPK inhibitor monotherapy or combination therapy showed an antitumor activity in PDX carrying genomic mutations of PIK3CA and NRAS genes. TNBC PDX reproduce the molecular heterogeneity of TNBC patients. This large collection of PDX is a clinically relevant platform for drug testing, biomarker discovery and translational research.

Metaplastic carcinoma of the breast: Prognosis and response to systemic treatment in metastatic disease

BACKGROUND

Metaplastic breast carcinomas (MpBCs) are rare, aggressive breast cancers. Due to the scant literature of this disease most guidelines do not give recommendation for this entity. The aim of the study was to review the clinicopathologic features, treatment, and outcomes of the patients with MpBC treated at our institution.

MATERIAL AND METHODS

We searched databases for patients with histologically confirmed MpBC from 2002 to 2016.

RESULTS

A total of 78 patients with MpBC were included in the study. All histological material was reviewed by an experienced breast pathologist. Most tumors were grade 3 (83%) and triple negative (85%). Eighty-two percent were node negative. Sixty-four percent received adjuvant chemotherapy. The 5-year disease free survival was 63% and 5-year breast cancer specific overall survival was 61%. Tumor size and mixed metaplastic histology were associated with worse outcome in this patient group. One third of the patients (n = 28) had metastatic disease at initial presentation or developed metastases at follow-up. The lungs were the most common site of first distant recurrence. Half (n = 14) of these patients received palliative chemotherapy. Of those only 6% (n = 2) had partial response and 18% had stable disease as best response to treatment. The median overall survival time with metastatic disease was only 3.4 months.

CONCLUSION

MpBC is an aggressive type of breast cancer with poor outcome despite low nodal involvement and aggressive local and systemic therapy. Tumor response to palliative systemic chemotherapy remains poor for MpBC patients.

Comparative prognostic analysis for triple-negative breast cancer with metaplastic and invasive ductal carcinoma

AIMS

Triple-negative breast cancer comprises different histological subtypes, including metaplastic breast cancer (MBC) and ductal carcinomas (IDCs). The purpose of this study was to compare triple-negative MBC (TN-MBC) with triple-negative IDC (TN-IDC) in terms of survival and predictive factors.

METHODS

With access to the Surveillance, Epidemiology and End Result (SEER) database, a total of 19 383 patients met the eligibility criteria. Clinicopathological characteristics were compared between groups using the χ² test. Univariate and multivariate analyses were applied to evaluate the disease-specific survival (DSS) and overall survival (OS). Subgroup analyses summarised the hazard ratios of TN-MBC versus TN-IDC using a forest plot.

RESULTS

A total of 586 patients with TN-MBC and 18 797 with TN-IDC were included in this study. Patients with TN-MBC were older and presented with larger tumour sizes, relatively rare lymph node positive disease, and had received more chemotherapy. Compared with TN-IDC, the TN-MBC group showed a significantly poorer prognosis before and after the 1:3 matched case-control analysis. Further subgroup analysis indicated that patients with TN-MBC were older, were from specific races, and those with distant metastasis and not receiving radiotherapy had worse prognosis than patients with TN-IDC in terms of DFS and OS.

CONCLUSION

Our results showed that patients with TN-MBC had unique clinicopathological characteristics and poorer prognostic subtype compared with TN-IDC. This improves our understanding of the clinicopathological and prognostic features of this rare entity but also provides more convincing therapeutic guidelines for TN-MBC in patients with breast cancer.

Metaplastic breast cancers: Genomic profiling, mutational burden and tumor-infiltrating lymphocytes

Metaplastic breast cancer (MPBC) is a rare subtype that accounts for <1% of all breast cancers. Although these are typically "triple negative," they are relatively chemotherapy-refractory compared to conventional triple negative invasive breast cancers with more aggressive features and an overall poor prognosis. MPBC is a heterogeneous group of tumors that are enriched for TP53 and PIK3CA mutations, and have been found to have high PD-L1 expression though the mechanisms underlying its immunogenicity remain unclear. We perform comprehensive genomic profiling in the largest MPBC dataset (n = 192) to date and assess for other potential biomarkers of immune response.

LATS1 and LATS2 suppress breast cancer progression by maintaining cell identity and metabolic state

In luminal B tumors LATS2 depletion results in metabolic rewiring whereas LATS1 depletion promotes the expression of basal-like features.

Deregulated activity of LArge Tumor Suppressor (LATS) tumor suppressors has broad implications on cellular and tissue homeostasis. We examined the consequences of down-regulation of either LATS1 or LATS2 in breast cancer. Consistent with their proposed tumor suppressive roles, expression of both paralogs was significantly down-regulated in human breast cancer, and loss of either paralog accelerated mammary tumorigenesis in mice. However, each paralog had a distinct impact on breast cancer. Thus, LATS2 depletion in luminal B tumors resulted in metabolic rewiring, with increased glycolysis and reduced peroxisome proliferator-activated receptor γ (PPARγ) signaling. Furthermore, pharmacological activation of PPARγ elicited LATS2-dependent death in luminal B-derived cells. In contrast, LATS1 depletion augmented cancer cell plasticity, skewing luminal B tumors towards increased expression of basal-like features, in association with increased resistance to hormone therapy. Hence, these two closely related paralogs play distinct roles in protection against breast cancer; tumors with reduced expression of either LATS1 or LATS2 may rewire signaling networks differently and thus respond differently to anticancer treatments.

Histologic heterogeneity of triple negative breast cancer: A National Cancer Centre Database analysis

BACKGROUND

Triple negative breast cancer (TNBC) is an aggressive disease, but recent studies have identified heterogeneity in patient outcomes. However, the utility of histologic subtyping in TNBC has not yet been well-characterised. This study utilises data from the National Cancer Center Database (NCDB) to complete the largest series to date investigating the prognostic importance of histology within TNBC.

METHODS

A total of 729,920 patients (pts) with invasive ductal carcinoma (IDC), metaplastic breast carcinoma (MBC), medullary breast carcinoma (MedBC), adenoid cystic carcinoma (ACC), invasive lobular carcinoma (ILC) or apocrine breast carcinoma (ABC) treated between 2004 and 2012 were identified in the NCDB. Of these, 89,222 pts with TNBC that received surgery were analysed. Kaplan-Meier analysis, log-rank testing and multivariate Cox proportional hazards regression were utilised with overall survival (OS) as the primary outcome.

RESULTS

MBC (74.1%), MedBC (60.6%), ACC (75.7%), ABC (50.1%) and ILC (1.8%) had significantly different proportions of triple negativity when compared to IDC (14.0%, p < 0.001). TNBC predicted an inferior OS in IDC (p < 0.001) and ILC (p < 0.001). Lumpectomy and radiation (RT) were more common in MedBC (51.7%) and ACC (51.5%) and less common in MBC (33.1%) and ILC (25.4%), when compared to IDC (42.5%, p < 0.001). TNBC patients with MBC (HR 1.39, p < 0.001), MedBC (HR 0.42, p < 0.001) and ACC (HR 0.32, p = 0.003) differed significantly in OS when compared to IDC.

CONCLUSION(S)

Our results indicate that histologic heterogeneity in TNBC significantly informs patient outcomes and thus, has the potential to aid in the development of optimum personalised treatments.

Metaplastic Breast Cancer Treatment and Outcomes in 2500 Patients: A Retrospective Analysis of a National Oncology Database

BACKGROUND

Metaplastic breast cancer (MBC) is characterized by chemoresistance and hematogenous spread. We sought to identify factors associated with improved MBC outcomes and increased likelihood of MBC diagnosis.

METHODS

Women ≥ 18 years of age with stage I-III MBC and non-MBC diagnosed between 2010 and 2014 were identified in the National Cancer Data Base. Kaplan-Meier and multivariate Cox proportional hazards models were used to estimate associations with overall survival (OS). Multivariate logistic regression identified factors associated with MBC diagnosis.

RESULTS

Overall, 2451 MBC and 568,057 non-MBC patients were included; 70.3% of MBC vs. 11.3% of non-MBC patients were triple negative (p < 0.001). Five-year OS was reduced among MBC vs. non-MBC patients for the entire cohort (72.7 vs. 87.5%) and among triple-negative patients (71.1 vs. 77.8%; both p < 0.001). In MBC, triple-negative (vs. luminal) subtype was not associated with worse OS (hazard ratio [HR] 1.16, 95% confidence interval [CI] 0.88-1.54, p = 0.28). Compared with non-MBC patients, MBC patients were more likely to receive mastectomy (59.0 vs. 44.9%), chemotherapy (74.1 vs. 43.1%), and axillary lymph node dissection (ALND; 35.2 vs. 32.2%, all p ≤ 0.001). MBC patients more frequently had negative ALND (pN0) than non-MBC patients (20.0 vs. 10.6%, p < 0.001). Among MBC patients, chemotherapy (HR 0.69, 95% CI 0.53-0.89, p = 0.004) and radiotherapy (HR 0.52, 95% CI 0.39-0.69, p < 0.001) were associated with improved survival, while ALND was associated with decreased survival (HR 1.37, 95% CI 1.06-1.77, p = 0.02).

CONCLUSIONS

MBC patients had worse survival than non-MBC patients, independent of receptor status, suggesting that MBC may confer an additional survival disadvantage. Multimodal therapy was associated with improved outcomes, but ALND was not and may be overutilized in MBC.

Management of the axilla in metaplastic breast carcinoma

Background

Metaplastic breast cancer (MBC), characterized by admixed epithelial, squamous or mesenchymal elements, constitutes <1% of breast cancers and has a poor prognosis but a paradoxically low reported rate of axillary lymph node (LN) involvement. Due to its rarity, data on appropriate axillary management is lacking, prompting this investigation of LN status and outcomes.

Methods

We identified 41 MBC patients treated at our institution 2001-2011 who were followed for a median of 66 months. Statistical analyses evaluated axillary ultrasound (AUS), fine needle aspiration (FNA), and sentinel LN biopsy (SLNB) in association with LN status.

Results

Median tumor size was 2.7 cm and 76% were triple-negative. Twenty-three patients (56%) had preoperative AUS: 9 (39%) showed ≥1 suspicious LN, 6 proceeded to LN FNA and 3 were confirmed positive. Six patients had neoadjuvant chemotherapy, including 2 FNA LN+. Ten patients were LN+ at operation. Among 19 patients undergoing AUS and axillary surgery, AUS ± FNA sensitivity was 100% and specificity was 94%. LN positivity correlated with increasing tumor size, grade and angiolymphatic invasion. 16 patients recurred, 63% with distant disease (10/16) and one with isolated axillary disease after a negative SLNB not preceded by AUS. Overall SLNB accuracy was 96% (23/24), but absent preoperative AUS, 1/7 (14%) of SLNBs were falsely negative.

Conclusions

Our study is the first to specifically address the performance and utility of AUS/FNA and SLNB for MBC patients. AUS/FNA at diagnosis followed by SLN surgery provided accurate nodal staging and critical prognostic information to inform treatment recommendations. We recommend this approach for axillary management of MBC patients.

Clinical value of R-spondins in triple-negative and metaplastic breast cancers

Background:

RSPO ligands, activators of the Wnt/β-catenin pathway, are overexpressed in different cancers. The objective of this study was to investigate the role of RSPOs in breast cancer (BC).

Methods:

Expression of RSPO and markers of various cancer pathways were measured in breast tumours and cell lines by qRT–PCR. The effect of RSPO on the Wnt/β-catenin pathway activity was determined by luciferase assay, western blotting, and qRT–PCR. The effect of RSPO2 inhibition on proliferation was determined by using RSPO2 siRNAs. The effect of IWR-1, an inhibitor of the Wnt/β-catenin pathway, was examined on the growth of an RSPO2-positive patient-derived xenograft (PDX) model of metaplastic triple-negative BC.

Results:

We detected RSPO2 and RSPO4 overexpression levels in BC, particularly in triple-negative BC (TNBC), metaplastic BC, and triple-negative cell lines. Various mechanisms could account for this overexpression: presence of fusion transcripts involving RSPO, and amplification or hypomethylation of RSPO genes. Patients with RSPO2-overexpressing tumours have a poorer metastasis-free survival (P=3.6 × 10⁻⁴). RSPO2 and RSPO4 stimulate Wnt/β-catenin pathway activity. Inhibition of RSPO expression in a TN cell line inhibits cell growth, and IWR-1 significantly inhibits the growth of an RSPO2-overexpressing PDX.

Conclusions:

RSPO overexpression could therefore be a new prognostic biomarker and therapeutic target for TNBC.