Impact of the 2013 American Society of Clinical Oncology/College of American Pathologists guideline recommendations for human epidermal growth factor receptor 2 (HER2) testing of invasive breast carcinoma: a focus on tumours assessed as ‘equivocal’ for HE

Targeting chromosomal instability in patients with cancer

Chromosomal instability (CIN) is a hallmark of cancer and a driver of metastatic dissemination, therapeutic resistance, and immune evasion. CIN is present in 60-80% of human cancers and poses a formidable therapeutic challenge as evidenced by the lack of clinically approved drugs that directly target CIN. This limitation in part reflects a lack of well-defined druggable targets as well as a dearth of tractable biomarkers enabling direct assessment and quantification of CIN in patients with cancer. Over the past decade, however, our understanding of the cellular mechanisms and consequences of CIN has greatly expanded, revealing novel therapeutic strategies for the treatment of chromosomally unstable tumours as well as new methods of assessing the dynamic nature of chromosome segregation errors that define CIN. In this Review, we describe advances that have shaped our understanding of CIN from a translational perspective, highlighting both challenges and opportunities in the development of therapeutic interventions for patients with chromosomally unstable cancers.

HER2-Low Luminal Breast Carcinoma Is Not a Homogenous Clinicopathological and Molecular Entity

BACKGROUND

With the development of some new antibody-drug conjugates, the HER2 classification of breast carcinomas now includes the HER2-low (H2L) category: IHC 1+, 2+ non-amplified by ISH, and double-equivocal carcinomas, mostly luminal, expressing hormone receptors (HR+).

METHODS

We analyzed mutational status and transcriptomic activities of three HER2 effector pathways: PI3K-AKT, MAPK, and JAK-STAT, in association with clinicopathologic features, in 62 H2L carcinomas compared to 43 HER2-positive and 20 HER2-negative carcinomas, all HR+.

RESULTS

H2L carcinomas had significantly lower histoprognostic grades and mitotic and Ki67 proliferation indexes than HER2-positive carcinomas. Their PIK3CA mutation rates were close to those of HER2-negative and significantly higher than in HER2-positive carcinomas, contrary to TP53 mutations. At the transcriptomic level, we identified three distinct groups which did not reflect the new HER2 classification. H2L and HER2-negative carcinomas shared most of clinicopathological and molecular characteristics, except HER2 membrane expression (mRNA levels). The presence of a mutation in a signaling pathway had a strong pathway activation effect. PIK3CA mutations were more prevalent in H2L carcinomas, leading to a strong activation of the PI3K-AKT signaling pathway even in the absence of HER2 overexpression/amplification.

CONCLUSION

PIK3CA mutations may explain the failure of conventional anti-HER2 treatments, suggesting that new antibody-drug conjugates may be more effective.

Three-dimensional growth sensitizes breast cancer cells to treatment with ferroptosis-promoting drugs

Drugs causing ferroptosis, iron-mediated cell death, represent promising tools for cancer treatment. While exploring the effect of these drugs on breast cancer (BC), we found that a ferroptosis-inducing drug erastin dramatically inhibits tumorigenicity of human BC cells in mice but when used at a concentration known to effectively kill other cell types only modestly reduces such growth in 2D monolayer culture. BCs grow in vivo as 3D masses, and we found that ferroptosis inducers erastin and sulfasalazine inhibit growth of multiple human BC cell lines in 3D culture significantly stronger than in 2D culture. To understand the mechanism of this differential effect, we found that ferroptosis inducers upregulate mRNAs encoding multiple direct and indirect autophagy stimulators, such as ATG16L2, ATG9A, ATG4D, GABARAP, SQSTM/p62, SEC23A and BAX, in tumor cells growing in 2D but not in 3D culture. Furthermore, these drugs promoted autophagy of tumor cells growing in a 2D but not in a 3D manner. We observed that pharmacological inhibition of autophagy-stimulating protein kinase ULK1 or RNA interference-mediated knockdown of autophagy mediator ATG12 significantly sensitized tumor cells to erastin treatment in 2D culture. We also found that ferroptosis-promoting treatments upregulate heme oxygenase-1 (HO-1) in BC cells. HO-1 increases cellular free iron pool and can potentially promote ferroptosis. Indeed, we observed that HO-1 knockdown by RNA interference reversed the effect of ferroptosis inducers on BC cell 3D growth. Hence, the effect of these drugs on such growth is mediated by HO-1. In summary, autophagy triggered by ferroptosis-promoting drugs reduces their ability to kill BC growing in a 2D manner. This protection mechanism is inhibited in BC cells growing as a 3D mass, and ferroptosis-promoting drugs kill such cells more effectively. Moreover, this death is mediated by HO-1. Thus, ferroptosis induction represents a promising strategy for blocking 3D BC growth.

Invasive Breast Cancer with HER2 ≥4.0 and <6.0: Risk Classification and Molecular Typing by a 21-Gene Expression Assay and MammaPrint Plus BluePrint Testing

PURPOSE

To investigate the HER2 status and clinicopathological features in invasive breast cancer with HER2 ≥4.0 and <6.0, which has always been controversial.

METHODS

Forty breast cancer cases with HER2 ≥4.0 and <6.0 by fluorescence in situ hybridization (FISH) were collected and classified into two groups based on the HRE2/CEP17 ratio (Group A: ≥2.0, n=22; Group B: <2.0, n=18). Clinicopathological characteristics, HER2 status, risk classification, and molecular typing were further analyzed and compared by 21-Gene expression assay and MammaPrint plus BluePrint test.

RESULTS

The majority of cases in both groups were invasive carcinoma (NOS), with histological grade II, HR+, Ki-67 ≥20%, HER2 2+, and a high risk of recurrence, although younger patients and lymph node metastases were more common in Group A. Surprisingly, all HR+ breast cancers in both groups were classified as luminal-type, HR- cases were all basal-type or unknown, and the index of HER2 in all cases was <0.000 using the BluePrint test, which indicated that HER2 status should be negative. Furthermore, the level of HER2 mRNA expression in all cases of both groups was <10.7, which was defined as HER2 negative by the 21-Gene expression assay. In addition, 10 patients of Group A received anti-HER2 neoadjuvant therapy; only one patient with HR- achieved Grade 5 based on the Miller-Payne system, whereas none of the patients achieved pathological complete response (pCR) based on the Residual Cancer Burden system.

CONCLUSION

Group A breast cancer, which has always been unquestionably diagnosed as HER2 amplification, was more likely to be HER2 negative and derived less benefit from anti-HER2 neoadjuvant chemotherapy. Group A breast cancer should be distinguished from classical HER2-positive breast cancers when assessing HER2 FISH, and a larger cohort of Group A patients should be included in further studies.

ErbB2/Her2-dependent downregulation of a cell death-promoting protein BLNK in breast cancer cells is required for 3D breast tumor growth

A significant proportion of breast cancers are driven by ErbB2/Her2 oncoprotein that they overexpress. These malignancies are typically treated with various ErbB2-targeted drugs, but many such cancers develop resistance to these agents and become incurable. Conceivably, treatment of ErbB2-positive cancers could be facilitated by use of agents blocking oncogenic signaling mechanisms downstream of ErbB2. However, current understanding of these mechanisms is limited. The ability of solid tumor cells to resist anoikis, cell death triggered by cell detachment from the extracellular matrix (ECM), is thought to be critical for 3D tumor growth. In an effort to understand the mechanisms of ErbB2-driven breast cancer cell anoikis resistance we found that detachment of non-malignant breast epithelial cells from the ECM upregulates a cell death-promoting tumor suppressor adapter protein BLNK and that ErbB2 blocks this upregulation by reducing tumor cell levels of transcription factor IRF6. We further observed that trastuzumab, a therapeutic anti-ErbB2 antibody, upregulates BLNK in human trastuzumab-sensitive but not trastuzumab-resistant ErbB2-positive breast cancer cells. Moreover, we established that BLNK promotes anoikis by activating p38 MAP kinase and that ErbB2-dependent BLNK downregulation blocks breast cancer cell anoikis. In search for pharmacological approaches allowing to upregulate BLNK in tumor cells we found that clinically approved proteasome inhibitor bortezomib upregulates IRF6 and BLNK in human breast cancer cells and inhibits their 3D growth in a BLNK-dependent manner. In addition, we found that BLNK upregulation in human ErbB2-positive breast cancer cells blocks their ability to form tumors in mice. Furthermore, we used publicly available data on mRNA levels in multiple breast cancers to demonstrate that increased BLNK mRNA levels correlate with increased relapse-free survival in a cohort of approximately 400 patients with ErbB2-positive breast cancer. In summary, we discovered a novel mechanism of ErbB2-driven 3D breast tumor growth mediated by ErbB2-dependent BLNK downregulation.

Characteristics of HER2-negative breast cancers with FISH-equivocal status according to 2018 ASCO/CAP guideline

BACKGROUND

According to 2018 ASCO/CAP guideline, HER2 FISH-equivocal breast cancers will be categorized as HER2 negative except those with IHC 3+. However, whether or not HER2 FISH-equivocal breast cancers was a heterogeneous group has not been well illustrated.

METHODS

195 HER2 FISH-equivocal breast cancer samples were collected from 2014 to 2018. The molecular subtype was identified according to 2013 St Gallen consensus, and HER2 status was also re-determined following 2018 ASCO/CAP guideline. All samples were classified into 4 groups according to the average HER2 copy number (4.0-4.4, 4.5-4.9, 5.0-5.4, 5.5-5.9 signals/cell). The relationship between HER2 copy number and clinicopathological parameters was analyzed.

RESULTS

183 (93.8%) of 195 FISH-equivocal cases were classified as luminal-like subtype, while the other 12 (6.2%) were undetermined. Following 2018 ASCO/CAP guideline, all FISH-equivocal cases were recategorized as HER2 negative. Therefore, 31(15.9%) cases were luminal A-like, 152 (77.9%) were luminal B-like (HER2 negative) and 12 (6.2%) were triple negative. The average HER2 copy number showed a positive correlation with chromosome 17 polysomy, but had no significant association with other clinicopathological parameters as well as prognosis. 17 (8.7%) patients were treated with trastuzumab, but showed no difference in prognosis with those who didn't receive targeted therapy.

CONCLUSIONS

In this study, all HER2 FISH-equivocal breast cancers were recategorized as HER2 negative according to 2018 ASCO/CAP guideline. Most of these patients were luminal B-like (HER2 negative). The average HER2 copy number had no significant association with clinicopathological parameters, as well as prognosis.

Intratumoral Heterogeneity and Immune Response Indicators to Predict Overall Survival in a Retrospective Study of HER2-Borderline (IHC 2+) Breast Cancer Patients

Breast cancer (BC) categorized as human epidermal growth factor receptor 2 (HER2) borderline [2+ by immunohistochemistry (IHC 2+)] presents challenges for the testing, frequently obscured by intratumoral heterogeneity (ITH). This leads to difficulties in therapy decisions. We aimed to establish prognostic models of overall survival (OS) of these patients, which take into account spatial aspects of ITH and tumor microenvironment by using hexagonal tiling analytics of digital image analysis (DIA). In particular, we assessed the prognostic value of Immunogradient indicators at the tumor–stroma interface zone (IZ) as a feature of antitumor immune response. Surgical excision samples stained for estrogen receptor (ER), progesterone receptor (PR), Ki67, HER2, and CD8 from 275 patients with HER2 IHC 2+ invasive ductal BC were used in the study. DIA outputs were subsampled by HexT for ITH quantification and tumor microenvironment extraction for Immunogradient indicators. Multiple Cox regression revealed HER2 membrane completeness (HER2 MC) (HR: 0.18, p = 0.0007), its spatial entropy (HR: 0.37, p = 0.0341), and ER contrast (HR: 0.21, p = 0.0449) as independent predictors of better OS, with worse OS predicted by pT status (HR: 6.04, p = 0.0014) in the HER2 non-amplified patients. In the HER2-amplified patients, HER2 MC contrast (HR: 0.35, p = 0.0367) and CEP17 copy number (HR: 0.19, p = 0.0035) were independent predictors of better OS along with worse OS predicted by pN status (HR: 4.75, p = 0.0018). In the non-amplified tumors, three Immunogradient indicators provided the independent prognostic value: CD8 density in the tumor aspect of the IZ and CD8 center of mass were associated with better OS (HR: 0.23, p = 0.0079 and 0.14, p = 0.0014, respectively), and CD8 density variance along the tumor edge predicted worse OS (HR: 9.45, p = 0.0002). Combining these three computational indicators of the CD8 cell spatial distribution within the tumor microenvironment augmented prognostic stratification of the patients. In the HER2-amplified group, CD8 cell density in the tumor aspect of the IZ was the only independent immune response feature to predict better OS (HR: 0.22, p = 0.0047). In conclusion, we present novel prognostic models, based on computational ITH and Immunogradient indicators of the IHC biomarkers, in HER2 IHC 2+ BC patients.

Variable Expression of the Disialoganglioside GD2 in Breast Cancer Molecular Subtypes

Simple Summary

GD2 is an antigen that is tumor-specific and can be used as a target for specific immunotherapies. Since the knowledge about GD2 in breast cancer is limited, we analyzed the frequency of GD2 expression in breast cancer using two different staining methods and the impact of GD2 expression on the survival of breast cancer patients. GD2 expression was found in more than 50% of breast cancer cases, with the highest frequency in hormone receptor-positive tumors. GD2 expression was not significantly associated with patient outcome. Unlike previous studies with smaller sample sizes that lacked correlation with clinical data, this study includes a larger cohort and associations with survival data and shows that GD2 is expressed on human breast cancer cells, providing a potential target for immunotherapies (e.g., anti-GD2 antibodies or GD2 CAR T cells), that are currently undergoing clinical testing.

Abstract

The disialoganglioside GD2 is a tumor-associated antigen that may allow for the application of targeted immunotherapies (anti-GD2 antibodies, GD2 CAR T cells) in patients with neuroblastoma and other solid tumors. We retrospectively investigated GD2 expression in a breast cancer cohort, using immunohistochemistry (IHC) and immunofluorescence (IF) on tissue microarrays (TMAs), and its impact on survival. GD2 expression on IHC (n = 568) and IF (n = 503) was investigated in relation to subtypes and patient outcome. Overall, 50.2% of the 568 IHC-assessed samples and 69.8% of the 503 IF-assessed samples were GD2-positive. The highest proportion of GD2-positive tumors was observed in luminal tumors. Significantly fewer GD2-positive cases were detected in triple-negative breast cancer (TNBC) compared with other subtypes. The proportion of GD2-expressing tumors were significantly lower in HER2-positive breast cancer in comparison with luminal tumors on IF staining (but not IHC). GD2 expression of IHC or IF was not significantly associated with disease-free or overall survival, in either the overall cohort or in individual subtypes. However, GD2 expression can be seen in more than 50% of breast cancer cases, with the highest frequency in hormone receptor-positive tumors. With this high expression frequency, patients with GD2-positive advanced breast cancer of all subtypes may benefit from GD2-targeting immunotherapies, which are currently subject to clinical testing.

Reproducibility of mRNA-Based Testing of ESR1, PGR, ERBB2, and MKI67 Expression in Invasive Breast Cancer-A Europe-Wide External Quality Assessment

Simple Summary

Four biomarkers [estrogen receptor (ER), progesterone receptor (PgR), Ki-67, and HER2], are used to stratify breast cancer (BC) into subtypes predictive of therapy response. In a Europe-wide external quality assessment, we compared performance of an mRNA-based method [Xpert^® Breast Cancer STRAT4 (CE-IVD)] for determining ESR1, PGR, ERBB2, and MKI67 expression against the gold standard [immunohistochemistry (IHC)/HER2 in situ hybridization (ISH)]. The coordinating center (CC) and five European laboratories tested ten breast cancer samples. STRAT4 binary (positive or negative) results of each marker were compared with the gold standard. ESR1 and ERBB2 mRNA results were concordant with IHC/ISH in all single analyses. In contrast, PGR and MKI67 results were discordant in a few cases, which had STRAT4 expression values close to assay cut-offs and immunohistochemically presented heterogeneous low positive PgR and heterogeneous Ki-67. STRAT4 assay may be a reproducible method. However, cases with expression values close to cut-offs should be carefully reviewed.

Abstract

Estrogen receptor (ER), progesterone receptor (PgR), Ki-67, and HER2 immunohistochemistry (IHC) together with HER2 in situ hybridization (ISH) are utilized to classify invasive breast cancer (IBC) into predictive molecular subtypes. As IHC evaluation may be hampered by analytical errors, gene expression assays could offer a reliable alternative. In this first Europe-wide external quality assessment (EQA) study, we investigated performance of mRNA-based Xpert^® Breast Cancer STRAT4 (CE-IVD) in five European laboratories. The cohort comprised ten pre-therapy IBC core biopsies diagnosed in the coordinating center (CC). STRAT4 binary (positive or negative) mRNA results of each marker (ESR1, PGR, ERBB2, MKI67) were compared with the gold standard IHC/ISH performed by the CC. Sensitivity, specificity, and accuracy of ESR1 and ERBB2 mRNA were 100% for all samples. In contrast, PGR expression was falsely negative for one case by two sites and MKI67 falsely negative for two cases (respectively by four and one sites). These cases had STRAT4 expression values close to assay cut-offs and immunohistochemically presented heterogeneous low positive PgR and heterogeneous Ki-67. Our EQA shows that STRAT4 mRNA assay may be a reproducible method to evaluate ER, PgR, HER2, and Ki-67 status. However, cases with expression values close to assay cut-offs should be carefully reviewed.

An Evaluation of Clinicopathological Correlation and Outcome of Human Epidermal Growth Factor Receptor 2 Subgroups Reclassified According to the Latest ASCO/CAP Guideline

BACKGROUND

The latest American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guideline has updated the interpretation of uncommon human epidermal growth factor receptor 2 (HER2) in situ hybridization (ISH) patterns (groups 2-4) with concomitant HER2 immunohistochemistry, leading to changes in the diagnosis of these subgroups. We sought to assess the clinicopathological features and outcomes in these subgroups in detail with our local cohort.

PATIENTS AND METHODS

Clinicopathologic features of groups 2 to 4 were compared to the typical amplified group (group 1: HER2/CEP17 ≥ 2, HER2 ≥ 4) and non-amplified group (group 5: HER2/CEP17 < 2, HER2 < 4).

RESULTS

Group 2 (HER2/CEP17 ≥ 2, HER2 < 4) cases showed lower Ki67 expression and grade (P ≤ .002) than group 1 but no differences compared with group 5. Group 4 (HER2/CEP17 < 2, HER2 = 4-6) cases were associated with less necrosis, more estrogen receptor positivity, lower grade, more nodal metastases, and more special histotypes (P ≤ .037) than group 1, but higher grade and more nodal metastases (P ≤ .021) than group 5. Except for presenting as a larger tumor and of special histotypes, group 3 (HER2/CEP17 < 2, HER2 ≥ 6) cases showed no other significant differences from group 1, but were of higher grade and Ki67 level than groups 2, 4, and 5. Group 4, similar to group 5, showed worse survival than group 1 (disease-free survival: log-rank = 5.547, P = .019; overall survival: log-rank = 4.678, P = .031). The rate of relapse was similar in group 4 with and without anti-HER2 therapy, albeit with limited cases.

CONCLUSION

Our findings indicate more similarities among groups 2, 4, and 5 than between groups 1 and 3, supporting the HER2 categorization in the latest guideline. Additional studies may be warranted to assess the outcomes of these patients with different management approaches.

Tumor levels of the mediators of ErbB2-driven anoikis resistance correlate with breast cancer relapse in patients receiving trastuzumab-based therapies

PURPOSE

Patients with ErbB2/Her2 oncoprotein-positive breast cancers often receive neoadjuvant therapies (NATs) containing the anti-ErbB2 antibody trastuzumab. Tumors that are still present after NATs are resected, and patients continue receiving trastuzumab. These cancers are associated with high relapse risk. Whether relapse will occur cannot be presently reliably predicted. The ability to make such predictions could improve disease management. We found previously that ErbB2 blocks breast tumor cell anoikis, apoptosis induced by cell detachment from the extracellular matrix, by downregulating the pro-apoptotic protein Irf6 and upregulating the anti-apoptotic protein Epidermal Growth Factor Receptor (EGFR) in the cells and, thus, promotes their three-dimensional growth. We now tested whether tumor levels of these proteins before and after NATs correlate with patients' relapse-free survival (RFS) and overall survival (OS).

METHODS

We selected archival breast tumor samples collected from 37 women with ErbB2-positive stages II and III breast cancer before and after NATs. We used immunohistochemistry to test whether levels of the indicated proteins in respective tumors correlate with RFS and OS.

RESULTS

We observed that the presence of high Irf6 levels in the tumors following NATs correlated with reduced RFS and OS. Perhaps not by coincidence, we noticed that trastuzumab-sensitive ErbB2-positive breast cancer cells selected for the ability to overproduce exogenous Irf6 in culture acquired trastuzumab resistance. Finally, EGFR presence in patients' tumors before or after NATs was associated with decreased RFS and OS.

CONCLUSIONS

This study could help identify patients with ErbB2-positive tumors that are at increased risk of disease relapse following NATs.

Trastuzumab-induced upregulation of a protein set in extracellular vesicles emitted by ErbB2-positive breast cancer cells correlates with their trastuzumab sensitivity

Background

ErbB2/HER2 oncoprotein often drives breast cancers (BCs) which are treated with the anti-ErbB2 antibody trastuzumab. The efficacy of trastuzumab-based metastatic BC therapies is routinely assessed by imaging studies. Trastuzumab typically becomes ineffective in the case of this disease and is then replaced by other drugs. Biomarkers of BC trastuzumab response could allow imaging studies and the switch to other drugs to occur earlier than is now possible. Moreover, bone-only BC metastases can be hard to measure, and biomarkers of their trastuzumab response could facilitate further treatment decisions. Such biomarkers are presently unavailable. In this study, we searched for proteins whose levels in BC cell-emitted extracellular vesicles (EVs) potentially correlate with BC trastuzumab sensitivity.

Methods

We isolated EVs from cultured trastuzumab-sensitive and trastuzumab-resistant human BC cells before and after trastuzumab treatment and characterized these EVs by nanoparticle tracking analysis and electron microscopy. We found previously that ErbB2 drives BC by downregulating a pro-apoptotic protein PERP. We now tested whether trastuzumab-induced PERP upregulation in EVs emitted by cultured human BC cells correlates with their trastuzumab sensitivity. We also used mass spectrometry to search for additional proteins whose levels in such EVs reflect BC cell trastuzumab sensitivity. Once we identified proteins whose EV levels correlate with this sensitivity in culture, we explored the feasibility of testing whether their levels in the blood EVs of trastuzumab-treated metastatic BC patients correlate with patients’ response to trastuzumab-based treatments.

Results

We found that neither trastuzumab nor acquisition of trastuzumab resistance by BC cells affects the size or morphology of EVs emitted by cultured BC cells. We established that EV levels of proteins PERP, GNAS2, GNA13, ITB1, and RAB10 correlate with BC cell trastuzumab response. Moreover, these proteins were upregulated during trastuzumab-based therapies in the blood EVs of a pilot cohort of metastatic BC patients that benefited from these therapies but not in those derived from patients that failed such treatments.

Conclusions

Upregulation of a protein set in EVs derived from cultured breast tumor cells correlates with tumor cell trastuzumab sensitivity. It is feasible to further evaluate these proteins as biomarkers of metastatic BC trastuzumab response.

Impact of the Updated Guidelines on Human Epidermal Growth Factor Receptor 2 (HER2) Testing in Breast Cancer

Purpose

In 2007, the American Society of Clinical Oncology and the College of American Pathologists had established a human epidermal growth factor receptor 2 (HER2) testing guideline, which was updated in 2013 and subsequently in 2018. We assessed the clinical impact of the recent update by comparing the in situ hybridization (ISH) results based on the 2007, 2013, and 2018 guidelines.

Methods

We assessed 2 cohorts. The first cohort included 1,161 primary invasive breast cancer (IBC) samples including 18 bilateral IBC cases, with both immunohistochemistry (IHC) and silver-enhanced ISH (SISH) results available for the HER2 status. The second cohort included 160 IBC cases with equivocal HER2 IHC, assessed using SISH. We retrospectively evaluated and compared the HER2 SISH results.

Results

There were 22 (1.9%) and 20 (12.5%) cases with altered SISH results according to the 2013 guidelines in cohorts 1 and 2, respectively. As per the 2018 guidelines, final HER2 statuses of 16 (1.4%) and 14 (8.5%) cases changed in cohorts 1 and 2, respectively. The 2013 guidelines increased the positive rate compared to the 2007 guidelines, in both cohorts (0.6% and 6.2%, respectively). Most equivocal cases in cohorts 1 (92.3%) and 2 (100%) as per the 2013 guidelines were reclassified as HER2-negative according to the 2018 guidelines. The 2018 guidelines increased the negative rates (1.3% in cohort 1 and 8.7% in cohort 2) and slightly decreased the positive rates (−0.2% in cohort 1 and −3.1% in cohort 2), compared to the 2013 guidelines. With each update, minor changes in the positive and negative rates were observed in whole breast cancer samples (cohort 1). However, the 2018 guidelines affected previously defined HER2-positive IBC with equivocal IHC results.

Conclusion

Under the 2013 guidelines, the positive and equivocal cases increased. However, the 2018 guidelines eliminated ambiguous cases by reclassifying them as HER2-negative.

PIWI-Like 1 and PIWI-Like 2 Expression in Breast Cancer

Simple Summary

A family of proteins, the PIWI proteins, play a crucial role in the regulation of the development of germ cells and self-preservation of so-called stem cells. Former studies have shown that these proteins can be over- or underrepresented (over-/underexpressed) in some cancers and, in the case of abnormal expression, may be correlated with worse outcomes of tumor patients. In our study, we investigated the influence of the two PIWI proteins, PIWI-like 1 and PIWI-like 2, on the survival of breast cancer patients and their correlation with certain breast cancer subtypes. If a breast cancer showed a higher expression of PIWI-like 1 protein but less PIWI-like 2 protein than in non-tumorous tissue, the patient suffered from a more aggressive breast cancer subtype and had shorter survival. By analyzing these two proteins in breast cancer, we were able to predict tumor aggressiveness and prognosis.

Abstract

PIWI-like 1 and PIWI-like 2 play a role in stem cell self-renewal, and enhanced expression has been reported for several tumor entities. However, few studies have investigated PIWI-like 1 and PIWI-like 2 expressions in breast cancer subtypes regarding prognosis. Therefore, we examined protein expression in a large consecutive cohort of breast cancer patients and correlated it to breast cancer subtypes and survival outcome. PIWI-like 1 and PIWI-like 2 expressions were evaluated using immunohistochemistry in a cohort of 894 breast cancer patients, of whom 363 were eligible for further analysis. Percentage and intensity of stained tumor cells were analyzed and an immunoreactive score (IRS) was calculated. The interaction of PIWI-like 1 and PIWI-like 2 showed a prognostic effect on survival. For the combination of high PIWI-like 1 and low PIWI-like 2 expressions, adjusted hazard ratios (HRs) were significantly higher with regard to overall survival (OS) (HR 2.92; 95% confidence interval (CI) 1.24, 6.90), disease-free survival (DFS) (HR 3.27; 95% CI 1.48, 7.20), and distant disease-free survival (DDFS) (HR 7.64; 95% CI 2.35, 24.82). Both proteins were significantly associated with molecular-like and PAM50 subgroups. Combining high PIWI-like 1 and low PIWI-like 2 expressions predicted poorer prognosis and both markers were associated with aggressive molecular subtypes.

Clinicopathologic features of breast cancer reclassified as HER2-amplified by fluorescence in situ hybridization with alternative chromosome 17 probes

OBJECTIVE

Dual probe fluorescence in situ hybridization (FISH) assays for determination of human epidermal growth factor receptor 2 (HER2) gene amplification in breast cancer provide a ratio of HER2 to chromosome 17. The ratio may be skewed by copy number alterations (CNA) in the control locus for chromosome 17 (CEP17). We analyzed the impact of alternative chromosome 17 control probes on HER2 status in a series of breast cancers with an emphasis on patients reclassified as amplified.

METHODS

Breast cancer patients with equivocal HER2 immunohistochemistry (2+) and equivocal FISH with CEP17 were included. Reclassification of HER2 status was assessed with alternative chromosome 17 control probes (LIS1 and RARA).

RESULTS

A total of 40 unique patients with 46 specimens reflexed to alternative chromosome 17 probe testing were identified. The majority (>80%) of patients had pT1-2, hormone receptor-positive tumors with an intermediate or high combined histologic grade. There were 34/46 (73.9%) specimens reclassified as amplified with alternative probes, corresponding to 29/40 (72.5%) patients. Of the patients reclassified as amplified with alternative probes, 34.5% (10/29) received HER2-targeted therapy.

CONCLUSION

In this series, the majority of breast cancers tested with alternative chromosome 17 control probes under the 2013 ASCO/CAP Guidelines were converted to HER2-amplified. The treatment data and the clinicopathologic profile of the tumors suggest that most of these patients will neither receive nor benefit from HER2-targeted therapy. The findings support the recommendation in the 2018 ASCO/CAP HER2 Guidelines to discontinue the use of alternative chromosome 17 probes.

The updated 2018 American Society of Clinical Oncology/College of American Pathologists guideline on human epidermal growth factor receptor 2 interpretation in breast cancer: comparison with previous guidelines and clinical significance of the proposed in situ hybridization groups

The aim of the study was to evaluate the impact of the updated 2018 American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guideline on human epidermal growth factor receptor 2 (HER2) interpretation in breast cancer compared with that of the previous guidelines and also the significance of in situ hybridization (ISH) groups proposed by the updated guideline. HER2 ISH reports and immunohistochemistry (IHC) data from 1,348 invasive breast cancers diagnosed at a single institution were included in this study. HER2 IHC was reassessed using the 2018 guideline, and HER2 ISH status was determined by the 2007, 2013, and 2018 guidelines. When applying the updated guideline, most of the HER2 ISH-equivocal cases as per the previous guidelines were reclassified as ISH negative, and 0.8% of HER2 ISH-positive tumors as per the 2007 guideline and 2.5% of those as per the 2013 guideline were changed to ISH negative. Accordingly, the negative HER2 ISH results significantly increased in the 2018 guideline compared with the 2013 guideline. HER2 ISH-positive tumors in ISH group 3 (HER2/chromosome enumeration probe 17 [CEP17] ratio <2.0 and average HER2 copy number ≥6.0 per cell) were characterized by equivocal HER2 protein expression, CEP17 copy number gain, and low HER2 copy numbers compared with classic HER2 ISH-positive tumors in ISH group 1 (HER2/CEP17 ratio ≥2.0 and average HER2 copy number ≥4.0 per cell). HER2 ISH-negative tumors in ISH group 4 (HER2/CEP17 ratio <2.0 with average HER2 copy number ≥4.0 and < 6.0 per cell) revealed more aggressive clinicopathologic features and poorer clinical outcomes than those in ISH group 5 (HER2/CEP17 ratio <2.0 and average HER2 copy number <4.0 per cell), especially in the hormone receptor-positive subgroup. In conclusion, implementation of the updated 2018 ASCO/CAP guideline leads to a significant increase in HER2 ISH-negative results compared with the 2013 guideline, mainly via reclassification of the ISH-equivocal cases to ISH-negative ones. ISH groups proposed by the updated guideline provide additional information on the clinicopathologic characteristics of the tumors.

Impact of 2013 ASCO/CAP guidelines on various HER2 reporting categories in breast cancer by fluorescentin-situhybridization and Immunohistochemistry: A meta-analysis with systematic review

Objective:

The ASCO/CAP guidelines for reporting HER2 in breast cancer, first released in 2007, aimed to standardize the reporting protocol, and were updated in 2013 and 2018, to ensure right treatment. Several studies have analyzed the changes attributed to 2013 updated guidelines, and majority of them found increase in positive and equivocal cases. However, the precise implication of these updated guidelines is still contentious, in spite of the latest update (2018 guidelines) addressing some of the issues. We conducted systematic review and meta- analysis to see the impact of 2013 guidelines on various HER2 reporting categories by both FISH and IHC.

Materials and Methods:

After extensively searching the pertinent literature, 16 studies were included for the systematic review. We divided our approach in three strategies: (1) Studies in which breast cancer cases were scored for HER2 by FISH or IHC as a primary test concurrently by both 2007 and 2013 guidelines, (2) Studies in which HER2 results were equivocal by IHC and were followed by reflex-FISH test by both 2007 and 2013 guidelines, and (3) Studies in which trends of HER2 reporting were compared in the two periods before and after implementation of updated 2013 guidelines. All the paired data in these respective categories was pooled and analyzed statistically to see the overall impact of the updated guidelines.

Results:

In the first category, by pooled analysis of primary FISH testing there has been a significant increase in the equivocal cases (P< 0.001) and positive cases (P= 0.037). We also found 8.3% and 0.8% of all the negative cases from 2007 guidelines shifted to equivocal and positive categories, respectively. Similarly by primary IHC testing there has been a significant increase in both equivocal cases (P< 0.001) and positive cases (P= 0.02). In the second category of reflex-FISH testing there was a substantial increase in the equivocal cases (P< 0.0001); however there is insignificant decrease (10% to 9.7%;P= 0.66) in the amplified cases. In the third approach for evaluating the trend, with the implementation of 2013 guidelines, there was increase in the equivocal category (P= 0.025) and positive category (P= 0.0088) by IHC. By FISH test also there was significant increase in the equivocal category (P< 0.001) while the increase in the positive category was non-significant (P= 0.159).

Conclusions:

The updated 2013 guidelines has significantly increased the positive and equivocal cases using primary FISH or IHC test and with further reflex testing, thereby increasing the double equivocal cases and increasing the cost and delaying the decision for definite management. However, whether the additional patients becoming eligible for HDT will derive treatment benefit needs to be answered by further large clinical trials.

Deciphering HER2 Breast Cancer Disease: Biological and Clinical Implications

The main obstacle for designing effective treatment approaches in breast cancer is the extensive and the characteristic heterogeneity of this tumor. The vast majority of critical genomic changes occurs during breast cancer progression, creating a significant variability within primary tumors as well as between the primary breast cancer and their metastases, a hypothesis have already demonstrated in retrospective studies (1). A clear example of this is the HER2-positive breast cancer. In these tumors, we can find all of the transcriptional subtypes of breast cancer, even the basal like or luminal A subtypes. Although the HER2-enriched is the most representative transcriptional subtype in the HER2-positive breast cancer, we can find it too in breast cancers with HER2-negative status. This intrinsic subtype shows a high expression of the HER2 and is associated with proliferation-related genes clusters, among other features. Therefore, two hypotheses can be suggested. First, the HER2 amplification can be a well-defined driver event present in all of the intrinsic subtypes, and not a subtype marker isolated. Secondly, HER2-enriched subtype can have a distinctive transcriptional landscape independent of HER2 amplification. In this review, we present an extensive revision about the last highlights and advances in clinical and genomic settings of the HER2-positive breast cancer and the HER2-enriched subtype, in an attempt to improving the knowledge of the underlying biology of both entities and to explaining the intrinsic heterogeneity of HER2-positive breast cancers.

Assessing the impact of the 2018 American Society of Clinical Oncology/College of American Pathologists recommendations on human epidermal growth factor receptor 2 testing by fluorescence in situ hybridization in breast carcinoma

The American Society of Clinical Oncology/College of American Pathologists recently updated their recommendations on human epidermal growth factor receptor 2 (HER2) testing by fluorescence in situ hybridization (FISH) in invasive breast cancer, with a focus on the clarification of less common test patterns of ISH. We assessed the impact of the updated ASCO/CAP guidelines on 1044 FISH tested tumors by comparing categorization according to the 2007, 2013, and 2018 ISH classification criteria. The 2013 guidelines increased the number of positive cases (17.4% vs 10.7%) identifying 70 (6.7%) additional patients who met the eligibility criteria for consideration for HER2-targeted therapy compared with the 2007 guidelines. There was a reduction in equivocal tumors (7.7%) with tumors classified as equivocal by the 2007 guidelines (n = 136) redistributed into positive (74, 54.4%) and negative (49, 36.0%) groups. The 2018 guidelines reclassified 10.8% of tumors in our series with a reduction in the number of positive tumors (7.1%). While the proportion of positive tumors (10.2%) was similar to that in 2007 (10.7%), the composition of this group was significantly altered. HER2 equivocal cases, a group which under the 2013 guidelines caused diagnostic and treatment difficulties, were largely eliminated. Our findings suggest that the 2018 update represents a potentially significant change in therapeutic options for a substantial proportion of patients with 2.9% of FISH-positive tumors according to the 2007 and 2013 guidelines now categorized as HER2 negative and, thus, ineligible for HER2-targeted therapy.

What to expect from the 2018 ASCO/CAP HER2 guideline in the reflex in situ hybridization test of immunohistochemically equivocal 2+ cases?

To evaluate the effect of the 2018 ASCO/CAP guideline in the identification of HER2-positive breast carcinomas (BC) in reflex in situ hybridization (ISH) test. A total of 592 primary invasive BC cases from before and after the publication of the updated ASCO/CAP guideline were evaluated for HER2 amplification by silver ISH according to the 2013 and 2018 guidelines. Cases were mostly (95%) HER2 equivocal by immunohistochemistry (IHC), not centrally reviewed. Other reasons for referring cases were IHC confirmation, IHC discordancy (either between needle-core-biopsy (NCB) and surgical excision specimen (SES) or between different laboratories) and IHC result unexpected for histopathologic features. Cases evaluated with the 2013 guideline (1st cohort) were 14.6% HER2-positive, decreasing significantly after the reclassification with the 2018 guideline due to the exclusion of group 2 cases without HER2 protein overexpression. Cases studied after the implementation of the 2018 guideline (2nd cohort) were 8.7% HER2-positive, a frequency that was not significantly different from the reclassification of the 1st cohort with the 2018 guideline. All cases referred for IHC confirmation had the expected ISH result. Cases with IHC discordancy between NCB and SES were ISH concordant. Only one out of 14 cases with an IHC score 3+ and classified as histological grade 1 or with a Ki67 below 10% was classified as ISH HER2-positive. The 2018 ASCO/CAP guideline resulted in a decrease of HER2-positive cases in reflex ISH test, selecting less patients for anti-HER2-targeted therapy.

The FDA-Approved Breast Cancer HER2 Evaluation Kit (HercepTest; Dako) May Miss Some HER2-Positive Breast Cancers

OBJECTIVES

Accurate evaluation of human epidermal growth factor receptor 2 (HER2) in breast cancer is critical.

METHODS

HER2 fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) tests were performed on 52 cases using a US Food and Drug Administration (FDA)-approved kit (HercepTest, FDA kit) and a laboratory-developed test (LDT) with the HercepTest antibody and a Leica Bond automated stainer.

RESULTS

By FISH, 22 were HER2 positive, 29 were negative, and one was equivocal. Of the 22 HER2 FISH-positive cases, five were negative by the FDA kit and none by LDT. The five discrepant cases were retested using the same FDA kit in another Clinical Laboratory Improvement Amendments-certified laboratory, and all five cases were still negative. None of the 29 HER2 FISH-negative cases were positive by the FDA kit or LDT. The overall IHC-FISH concordance rate was 90.4% for the FDA kit and 100% for the LDT.

CONCLUSIONS

The FDA kit may miss some HER2-positive cases. The LDT has a higher sensitivity and a higher concordance rate with FISH results.

Bimetallic ZrHf-based metal-organic framework embedded with carbon dots: Ultra-sensitive platform for early diagnosis of HER2 and HER2-overexpressed living cancer cells

We report here a new bimetallic ZrHf metal-organic framework (ZrHf-MOF) embedded with abundant carbon dots (CDs) (denoted as CDs@ZrHf-MOF), which exhibits strong fluorescence and rich-amino-functionalization. The CDs@ZrHf-MOF can be applied as the scaffold for anchoring aptamer strands to determine human epidermal growth factor receptor-2 (HER2) and living HER2-overexpressed MCF-7 cells. The basic characterizations reveal that the CDs are embedded within the interior cavities of ZrHf-MOF without varying the nanostructure, leading to good biocompatibility, strong fluorescence, and high electrochemical activity of CDs@ZrHf-MOF. As compared with the pristine ZrHf-MOF, the CDs@ZrHf-MOF-based electrochemical aptasensor displays better sensing performances toward both HER-2 and MCF-7 cells, giving an extremely low detection limit of 19 fg mL^-1 (HER2 concentration range: 0.001-10 ng mL^-1) and 23 cell mL^-1 (cell concentration range: 1 × 10²~1 × 10⁵ cell mL^-1), with good selectivity, stability, reproducibility, and acceptable applicability. The proposed strategy for developing CDs@ZrHf-MOF-based aptasensor is promising for the early and sensitive detection of cancer markers and living cancer cells.

ErbB2-driven downregulation of the transcription factor Irf6 in breast epithelial cells is required for their 3D growth

Background

The ability of solid tumor cells to resist anoikis, apoptosis triggered by cell detachment from the extracellular matrix (ECM), is thought to be critical for 3D tumor growth. ErbB2/Her2 oncoprotein is often overproduced by breast tumor cells and blocks their anoikis by partially understood mechanisms. In our effort to understand them better, we observed that detachment of nonmalignant human breast epithelial cells from the ECM upregulates the transcription factor Irf6. Irf6 is thought to play an important role in mammary gland homeostasis and causes apoptosis by unknown mechanisms. We noticed that ErbB2, when overproduced by detached breast epithelial cells, downregulates Irf6.

Methods

To test whether ErbB2 downregulates Irf6 in human ErbB2-positive breast cancer cells, we examined the effect of ErbB2 inhibitors, such as the anti-ErbB2 antibody trastuzumab or the ErbB2/epidermal growth factor receptor small-molecule inhibitor lapatinib, on Irf6 in these cells. Moreover, we performed Irf6 IHC analysis of tumor samples derived from the locally advanced ErbB2-positive breast cancers before and after neoadjuvant trastuzumab-based therapies. To examine the role of Irf6 in anoikis of nonmalignant and ErbB2-overproducing breast epithelial cells, we studied anoikis after knocking down Irf6 in the former cells by RNA interference and after overproducing Irf6 in the latter cells. To examine the mechanisms by which cell detachment and ErbB2 control Irf6 expression in breast epithelial cells, we tested the effects of genetic and pharmacological inhibitors of the known ErbB2-dependent signaling pathways on Irf6 in these cells.

Results

We observed that trastuzumab and lapatinib upregulate Irf6 in ErbB2-positive human breast tumor cells and that neoadjuvant trastuzumab-based therapies tend to upregulate Irf6 in human breast tumors. We found that detachment-induced Irf6 upregulation in nonmalignant breast epithelial cells requires the presence of the transcription factor ∆Np63α and that Irf6 mediates their anoikis. We showed that ErbB2 blocks Irf6 upregulation in ErbB2-overproducing cells by activating the mitogen-activated protein kinases that inhibit ∆Np63α-dependent signals required for Irf6 upregulation. Finally, we demonstrated that ErbB2-driven Irf6 downregulation in ErbB2-overproducing breast epithelial cells blocks their anoikis and promotes their anchorage-independent growth.

Conclusions

We have demonstrated that ErbB2 blocks anoikis of breast epithelial cells by downregulating Irf6.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-1080-1) contains supplementary material, which is available to authorized users.

Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer: American Society of Clinical Oncology/College of American Pathologists Clinical Practice Guideline Focused Update

PURPOSE.—

To update key recommendations of the American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) human epidermal growth factor receptor 2 (HER2) testing in breast cancer guideline.

METHODS.—

Based on the signals approach, an Expert Panel reviewed published literature and research survey results on the observed frequency of less common in situ hybridization (ISH) patterns to update the recommendations.

RECOMMENDATIONS.—

Two recommendations addressed via correspondence in 2015 are included. First, immunohistochemistry (IHC) 2+ is defined as invasive breast cancer with weak to moderate complete membrane staining observed in >10% of tumor cells. Second, if the initial HER2 test result in a core needle biopsy specimen of a primary breast cancer is negative, a new HER2 test may (not "must") be ordered on the excision specimen based on specific clinical criteria. The HER2 testing algorithm for breast cancer is updated to address the recommended workup for less common clinical scenarios (approximately 5% of cases) observed when using a dual-probe ISH assay. These scenarios are described as ISH group 2 ( HER2/chromosome enumeration probe 17 [CEP17] ratio ≥2.0; average HER2 copy number <4.0 signals per cell), ISH group 3 ( HER2/CEP17 ratio <2.0; average HER2 copy number ≥6.0 signals per cell), and ISH group 4 ( HER2/CEP17 ratio <2.0; average HER2 copy number ≥4.0 and <6.0 signals per cell). The diagnostic approach includes more rigorous interpretation criteria for ISH and requires concomitant IHC review for dual-probe ISH groups 2 to 4 to arrive at the most accurate HER2 status designation (positive or negative) based on combined interpretation of the ISH and IHC assays. The Expert Panel recommends that laboratories using single-probe ISH assays include concomitant IHC review as part of the interpretation of all single-probe ISH assay results.

Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer: American Society of Clinical Oncology/College of American Pathologists Clinical Practice Guideline Focused Update

Purpose To update key recommendations of the American Society of Clinical Oncology/College of American Pathologists human epidermal growth factor receptor 2 (HER2) testing in breast cancer guideline. Methods Based on the signals approach, an Expert Panel reviewed published literature and research survey results on the observed frequency of less common in situ hybridization (ISH) patterns to update the recommendations. Recommendations Two recommendations addressed via correspondence in 2015 are included. First, immunohistochemistry (IHC) 2+ is defined as invasive breast cancer with weak to moderate complete membrane staining observed in > 10% of tumor cells. Second, if the initial HER2 test result in a core needle biopsy specimen of a primary breast cancer is negative, a new HER2 test may (not "must") be ordered on the excision specimen based on specific clinical criteria. The HER2 testing algorithm for breast cancer is updated to address the recommended work-up for less common clinical scenarios (approximately 5% of cases) observed when using a dual-probe ISH assay. These scenarios are described as ISH group 2 ( HER2/chromosome enumeration probe 17 [CEP17] ratio ≥ 2.0; average HER2 copy number < 4.0 signals per cell), ISH group 3 ( HER2/CEP17 ratio < 2.0; average HER2 copy number ≥ 6.0 signals per cell), and ISH group 4 ( HER2/CEP17 ratio < 2.0; average HER2 copy number ≥ 4.0 and < 6.0 signals per cell). The diagnostic approach includes more rigorous interpretation criteria for ISH and requires concomitant IHC review for dual-probe ISH groups 2 to 4 to arrive at the most accurate HER2 status designation (positive or negative) based on combined interpretation of the ISH and IHC assays. The Expert Panel recommends that laboratories using single-probe ISH assays include concomitant IHC review as part of the interpretation of all single-probe ISH assay results. Find additional information at www.asco.org/breast-cancer-guidelines .

Comparative Performance of Breast Cancer Human Epidermal Growth Factor Receptor 2 Fluorescence In Situ Hybridization and Brightfield In Situ Hybridization on College of American Pathologists Proficiency Tests

CONTEXT.—

Fluorescence in situ hybridization (FISH) and brightfield in situ hybridization (ISH) are 2 clinically approved laboratory methods for detecting ERBB2 (HER2) amplification in breast cancer.

OBJECTIVE.—

To compare the performance of FISH and brightfield ISH on proficiency testing administered by the College of American Pathologists Laboratory Accreditation Program.

DESIGN.—

Retrospective review was performed on 70 tissue core samples in 7 separate proficiency testing surveys conducted between 2009 and 2013.

RESULTS.—

The samples included 13 consensus-amplified tissue cores, 53 consensus-nonamplified cores, and 4 cores that did not reach consensus for FISH and/or brightfield ISH. There were 2552 individual responses for FISH and 1871 individual responses for brightfield ISH. Consensus response rates were comparable for FISH (2474 of 2524; 98.0%) and brightfield ISH (2135 of 2189; 97.5%). The FISH analysis yielded an average HER2 copy number per cell that was significantly higher (by 2.86; P = .02) compared with brightfield ISH for amplified cores. For nonamplified cores, FISH yielded slightly, but not significantly, higher (by 0.17; P = .10) HER2 copy numbers per cell. There was no significant difference in the average HER2 to control ratio for either consensus-amplified or consensus-nonamplified cores. Participants reported "unable to analyze" more frequently for brightfield ISH (244 of 2453; 9.9%) than they did for FISH (160 of 2684; 6.0%).

CONCLUSIONS.—

Our study indicates a high concordance rate in proficiency testing surveys, with some significant differences noted in the technical performance of these assays. In borderline cases, updated American Society of Clinical Oncology/College of American Pathologists cutoff thresholds that place greater emphasis on HER2 copy number per cell could accentuate those differences between FISH and brightfield ISH.

The Assessment of HER2 Gene Status by Fluorescence In Situ Hybridization in Invasive Breast Carcinomas With Equivocal HER2 Immunostaining: Experience From a Single Institution

Background. A subset of breast carcinomas harbors overexpression of the human epidermal growth factor receptor 2 (HER2). Fluorescence in situ hybridization (FISH) should be performed in breast carcinomas with equivocal HER2 immunostaining (immunohistochemistry [IHC] HER2 2+). The aim of our study is to investigate clinicopathologic factors associated with HER2 status in breast invasive carcinomas with IHC HER2 2+ through FISH analysis. Methods. This is a retrospective study including the FISH analysis of 111 patients with invasive breast carcinomas with equivocal HER2 immunostaining. Results. The mean age was 49.51 ± 10.48 years, and invasive breast carcinoma of no special type was the most histological type in our study (96.4%). Most patients had tumors positive for hormones receptors (88.2% positive for estrogen receptor and 81.4% for progesterone receptor). On FISH, the HER2 amplification rate was 22.5%. There was no significant association of HER2 status with any clinicopathologic factors ( P > .05). Conclusions. Our study shows that there are no reliable clinicopathologic factors to predict the HER2 status in breast tumors with equivocal HER2 immunostaining, supporting the necessary usage of FISH in such circumstances.

Immunohistochemistry and alternative FISH testing in breast cancer with HER2 equivocal amplification

Purpose

While HER2 testing is well established in directing appropriate treatment for breast cancer, a small percentage of cases show equivocal results by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). Alternative probes may be used in equivocal cases. We present a single community-based institution’s experience in further evaluating these cases.

Patients and methods

Between 2014 and 2016, 4255 samples were submitted for HER2 amplification testing by alternative probes, TP53, RAI1, and RARA. Of the patients tested by FISH, 505/3908 (12.9%) also had IHC data.

Results

Most (73.9%) FISH equivocal cases remained equivocal after IHC testing. However, 50.5% of equivocal cases were classified as HER2 amplified by alternative probes. Most cases were positive by more than one probe: 78% of positive cases by RAI1 and 73.9% by TP53. There was a significant difference between IHC and FISH alternative testing (p < 0.0001) among the equivocal cases by conventional FISH testing, 44% of IHC negative cases became positive while 36% of the positive IHC cases became negative by alternative FISH testing. Available data showed that 41% of patients were treated with palbociclib and were positive by alternative FISH.

Conclusion

The prevalence of double HER2 equivocal cases and the discrepancy between IHC and alternative FISH testing suggest that FISH alternative testing using both RAI1 and TP53 probes is necessary for conclusive classification. Because almost half of FISH equivocal cases converted to HER2 amplified upon alternative testing, clinical studies to determine the benefit of anti-HER2 therapy in these patients are urgently needed.

HER2 equivocal breast cancer that is positive by alternative probe HER2 FISH are classified as HER2 negative by Oncotype DX

In breast cancer, human epidermal growth factor receptor 2 (HER2) status is determined by immunohistochemistry (IHC) and/or in situ hybridization. Oncotype DX also reports HER2 status by an rt-PCR-based assay. Assay concordance between IHC and fluorescent in situ hybridization (FISH) (including alternative probe HER2 FISH) vs Oncotype DX HER2 rt-PCR has not been described in the post-2013 American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) HER2 Guideline revision setting. We performed a retrospective review of HER2 equivocal invasive breast carcinoma from 2014 to 2016 with the Oncotype DX HER2 result. Fifteen patients with HER2 equivocal invasive breast cancer had Oncotype DX performed. Of these, 13 underwent alternative probe HER2 FISH yielding 4 negative, 6 equivocal and 3 positive results. All 15 cases were classified as HER2 negative by Oncotype DX rt-PCR, including the three cases which were positive by alternative probe HER2 FISH, yielding a discordance rate for Oncotype DX rt-PCR HER2 of 20% (3/15). All three patients with HER2-positive breast cancer on the basis of alternative probe HER2 FISH received anti-HER2-targeted therapy. Treatment decisions based on HER2 status should utilize the IHC/FISH result as Oncotype DX results may incorrectly disqualify some patients from being eligible for anti-HER2 therapy based on the current 2013 ASCO/CAP HER2 Guidelines.

TILGen: A Program to Investigate Immune Targets in Breast Cancer Patients - First Results on the Influence of Tumor-Infiltrating Lymphocytes

BACKGROUND

Despite advancements in the treatment of primary and metastatic breast cancer, many patients lack a durable response to these treatments. Patients with triple-negative breast cancer (TNBC) and human epidermal growth factor receptor 2(HER2)-positive breast cancer who do not have a pathological complete response (pCR) after neoadjuvant chemotherapy (NACT) have a very poor prognosis. Tumor-infiltrating lymphocytes (TILs) have been identified as a predictive marker for pCR after NACT in TNBC and HER2-positive breast cancer. These patient populations could also be suitable for novel treatment strategies including neoepitope-based therapies. This work analyses the effect of TILs on the pCR in neoadjuvantly treated patients in the TILGen study and presents the procedures aimed at establishing neoepitope-based therapies in this study.

METHODS

Neoadjuvantly treated HER2-positive and TNBC patients were eligible for the presented analysis concerning the association between TILs and pCR. A total of 146 patients could be identified within the TILGen study. TILs were evaluated as percentage of stromal tumor tissue in core biopsies at primary diagnosis. The phenotype 'lymphocyte-predominant breast cancer' (LPBC) was associated with pCR by logistic regression adjusted for estrogen receptor status, progesterone receptor status, HER2 status, age at diagnosis, and grading.

RESULTS

LPBC was seen in 24 (16.4%) patients. In this patient group, 66.7% achieved a pCR, while the pCR rate was 32.8% in patients with a low TIL count. The adjusted odds ratio was 6.60 (95% confidence interval 2.02-21.56; p < 0.01).

CONCLUSION

TILs are a strong predictor of pCR in TNBC and HER2-positive breast cancer patients. Implications for the use of this information including the effect on prognosis might help to identify patients most likely to benefit from a neoepitope-based therapy approach.

Impact of 2013 ASCO/CAP HER2 reporting guidelines in breast cancer: An assessment study from Indian oncology centre that primarily performs HER2 IHC testing with special emphasis on IHC equivocal category

The ASCO/CAP guidelines for HER2 reporting in breast cancer published in 2007 and were updated in 2013 to assure that the right patient receives the targeted therapy. The updated guidelines have lowered the threshold for HER2 positivity criteria and altered the equivocal category for both IHC and FISH. This first study from India addresses the impact of these updated guidelines in the various reporting categories at a tertiary care centre. We compared the trend of HER2 IHC reporting 1 year before (Period A) and 1 year after (Period B) the implementation of updated 2013 ASCO/CAP guidelines. All HER2 equivocal IHC cases of post 2013 guidelines were reclassified as per 2007 guidelines to detect additional number of cases that have been put into equivocal category. Reflex FISH correlation was also assessed to detect any additional cases eligible for anti HER2 therapy with implementation of these updated guidelines. With implementation of updated 2013 guidelines, there was significant decrease in the number of cases scored as 1+ (from 30.7% to 20.6%; P value: .0001) while significant increase in number of 2+ cases (from 20.2% to 27.3%; P value: .004). Post 2013 guidelines, 39% (64 cases) of tumors were additionally put into the equivocal category which would have been considered as negative (score 1+) as per 2007 guidelines. The reflex FISH testing in these equivocal cases resulted in detection of only 1.5% of additional cases eligible for anti HER2 therapy. With implementation of updated 2013 guidelines, there is no significant increase in HER2 positivity trend. However, there is appreciable increase in IHC equivocal cases which subsequently led to increased reflex FISH testing without significantly contributing to the detection of additional eligible cases for anti HER2 therapy, but resulted in delaying of definite HER2 status along with financial implications.

Can breast cancer patients with HER2 dual-equivocal tumours be managed as HER2-negative disease?

BACKGROUND

Increasing human epidermal growth factor receptor 2 (HER2) immunohistochemistry (IHC)/fluorescence in situ hybridisation (FISH) dual-equivocal breast tumours are reported after the 2013 American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) guideline update. The aim of this study is to investigate the clinico-pathologic characteristics, treatment patterns and disease outcome of these patients with HER2 dual-equivocal tumours.

PATIENTS AND METHODS

Patients with HER2 IHC 2+ and available FISH results were retrospectively analysed from the Comprehensive Breast Health Center, Shanghai Ruijin Hospital. The 2013 ASCO/CAP guideline was applied to define HER2-positive, dual-equivocal and -negative groups. Patient characteristics, systemic treatment patterns and survival were compared among these groups. Reverse transcriptase-polymerase chain reaction-based assays were applied to test HER2 mRNA expression level.

RESULTS

Among 691 patients included, 133 (19.25%) were HER2 positive, 25 (3.62%) were HER2 dual-equivocal and 533 (77.13%) were HER2 negative. Univariate and multivariate analyses stated that HER2 dual-equivocal tumours shared more similarity with HER2-negative tumours, whereas HER2-positive tumours had rather different clinico-pathologic features. HER2 dual-equivocal tumours had similar HER2 mRNA levels compared with HER2-negative tumours (P = 0.26), which were much less compared with HER2-positive breast cancer. Besides, adjuvant systemic treatment patterns were comparable between HER2-negative and dual-equivocal tumours, and none of HER2 dual-equivocal patients received anti-HER2 treatment. There was no survival difference among these three groups (P = 0.43).

CONCLUSION

HER2 dual-equivocal tumours share more similarity with HER2-negative disease in terms of clinico-pathologic features, HER2 mRNA levels, adjuvant systemic treatment patterns and disease outcome, which deserves further clinical evaluation.

Mek activity is required for ErbB2 expression in breast cancer cells detached from the extracellular matrix

Detachment of non-malignant epithelial cells from the extracellullar matrix (ECM) triggers their growth arrest and apoptosis. Conversely, carcinoma cells can grow without adhesion to the ECM. This capacity for anchorage-independent growth is thought to be critical for tumor progression. ErbB2/Her2 oncoprotein is overproduced by a significant fraction of breast cancers and promotes anchorage-independent tumor cell growth by poorly understood mechanisms. In an effort to understand them we found that in order to produce ErbB2, detached breast cancer cells require the activity of an ErbB2 effector protein kinase Mek and that Mek-driven ErbB2 expression is neccesary for anchorage-independent growth of such cells. We observed that Mek inhibition does not alter ErbB2 mRNA levels in detached cancer cells and that ErbB2 protein loss induced by this inhibition can be blocked by a lysosomal inhibitor. We also noticed that an increase of the density of cancer cells detached from the ECM downregulates a Mek effector protein kinase Erk and causes ErbB2 loss. Those cells that survive after ErbB2 loss display resistance to trastuzumab, an anti-ErbB2 antibody used for ErbB2-positive breast cancer treatment. Thus, Mek-induced ErbB2 stabilization in detached breast cancer cells is critical for their ability to grow anchorage-independently and their trastuzumab sensitivity.

Breast carcinomas with low amplified/equivocal HER2 by Ish: potential supporting role of multiplex ligation-dependent probe amplification

BACKGROUND

This is a retrospective cross sectional study aimed to verify whether Multiplex Ligation-dependent Probe Amplification (MLPA), a quantitative molecular assay, may represent a valuable reflex test in breast cancer with equivocal HER2 expression by immunohistochemistry and HER2 gene signals/nucleus (s/n) ranging between 4.0 and 5.9 by in situ hybridization.

METHODS

A series of 170 breast carcinomas scored as 2+ for HER2 expression by immunohistochemistry, were selected from our files and analyzed in parallel by silver in situ hybridization and by MLPA. According to ASCO-CAP 2013 guidelines, 54/170 tumors, displaying 4.0-5.9 HER2 gene s/n, were defined as low amplified (ratio ≥ 2) or equivocal (ratio < 2) on the basis of centromere enumeration probe 17 (CEP17) status. An independent set of 108 score 2+ breast cancers represented the external validation set. Concordance between the two techniques was assessed through the use of Cohen's K statistic.

RESULTS

A concordance rate of 78.2% (Cohen's K statistic: 0,548 95% CI:[0,419-0,677]) between in situ hybridization and MLPA was found in the whole series of 170 cases and of 55.5% (Cohen's K statistic: -0,043 95% CI:[-0,271-0,184]) in the 54 tumors presenting 4.0-5.9 HER2 gene s/n. By MLPA, we found HER2 amplification or gain in 14% of the 21 BC presenting a disomic status and in 18% of the 33 BC presenting a CEP17 > 2.0. These data were further confirmed in the external validation set. Interestingly, the 54 low amplified/equivocal breast carcinomas presented a frequency of hormonal receptor positivity significantly higher than that observed in the amplified tumors and similar to the non-amplified one (p = 0.016 for estrogen receptor and p = 0.001 for progesterone receptor).

CONCLUSIONS

To avoid to offer patients an ineffective therapy, HER2 status should be studied more thoroughly in low amplified and equivocal cases which can have lower response rates and shorter time to progression to trastuzumab. In this context, our data indicate that MLPA may be a reliable, objective supporting test in selecting HER2 positive breast cancer patients.

Impact of repeat HER2 testing after initial equivocal HER2 FISH results using 2013 ASCO/CAP guidelines

PURPOSE

The updated 2013 American Society of Clinical Oncology/College of American Pathologists guideline recommendations for human epidermal growth factor receptor 2 (HER2) testing have made some major changes in HER2 fluorescence in situ hybridization (FISH) interpretation criteria with additional FISH equivocal cases. Repeat HER2 testing is recommended after initial HER2 FISH equivocal results; however, little is known about its impact on final HER2 status. The aim of this study is to investigate whether reflex test clarifies HER2 status, and to characterize clinicopathological features of the newly defined HER2 equivocal group.

METHODS

A total of 886 consecutive cases of primary invasive breast cancer conducted with dual-probe HER2 FISH testing between November 2013 and December 2015 were reviewed. HER2 immunohistochemistry (IHC) and FISH testing were performed on a different tissue block or a new specimen after initial HER2 FISH equivocal results.

RESULTS

Compared to 2007 guideline, 85 (9.6%) cases changed their category by using 2013 guideline. The major change of the 85 cases is that 57 (6.4%) cases in HER2 FISH-negative category changed to equivocal, and the equivocal category cases increased from 36 to 67. HER2 FISH equivocal was significantly associated with HER2 IHC equivocal (2+) and chromosome 17 polysomy (P < 0.01). Repeat testing by IHC and FISH clarified HER2 status in 33 and 42% of HER2 equivocal cases, respectively. Overall 32 (48%) initial HER2 equivocal cases stayed HER2 equivocal after repeat FISH and or IHC testing. These tumors were ER/PR+, with high KI-67 index.

CONCLUSION

New guidelines classify more HER2 FISH equivocal cases. Repeat HER2 testing clarifies HER2 status in about 50% of initial HER2 FISH equivocal cases. In addition, HER2 equivocal cases merit further study as there is limited information about prognosis and optimal treatment strategy for this population.

Comparative Analysis of Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer According to 2007 and 2013 American Society of Clinical Oncology/College of American Pathologists Guideline Recommendations

Purpose To study the effect of the 2013 updates to the 2007 American Society of Clinical Oncology/College of American Pathologists recommendations for human epidermal growth factor receptor 2 (HER2) testing in breast cancer on testing patterns and interpretation in a large regional reference laboratory. Patients and Methods Patient cases with HER2 testing scores for breast biomarker evaluation were selected from our laboratory information system during two 12-month periods (2012 and 2014). The number of tests performed, type of specimens, proportion of HER2-positive and equivocal patient cases, and number of repeat tests on subsequent excisional specimens were examined and compared. Results Although the number of samples tested increased between 2012 and 2014 (2,201 v 2,558 patient cases; 2,278 v 2,659 tumors), HER2 positivity remained constant (15.7% v 15.5%, respectively). The number of repeat tests performed within 6 months more than doubled (122 [5.5%) of 2,201 v 302 [11.8%] of 2,558; P < .001), and the proportion of immunohistochemistry (IHC) 2+ tumors was significantly lower in 2014 than in 2012 (20.3% v 25.3%; P < .001). However, the proportion of patient cases with unresolved HER2 statuses (equivocal by IHC and in situ hybridization) was significantly higher in 2014 (four of 2,278 v 90 of 2,660; P < .001). Conclusion Our findings indicate that the 2013 updates to the American Society of Clinical Oncology/College of American Pathologists recommendations for HER2 testing in breast cancer did not affect the overall HER2-positivity rate or the proportion of patients eligible for HER2-targeted therapy. The proportion of tests and repeat tests performed increased, as did the number of patient cases categorized as ISH equivocal. The benefit of targeted therapy in the equivocal group is not proven, so targeted therapy should not be considered for patients in this category which should be redefined in future iterations of the recommendations.

Counting invasive breast cancer cells in the HER2 silver in-situ hybridization test: how many cells are enough?

AIM

To evaluate the intraobserver and interobserver reproducibility of the HER2 in-situ hybridization (ISH) test in breast cancer by measuring the impact of counting different numbers of invasive cancer cells.

METHODS AND RESULTS

A cohort of 101 primary invasive breast cancer cases were evaluated for HER2 gene amplification by silver ISH, and the concordance among four observers with different levels of experience, counting different numbers of invasive cancer cells, was determined. The evaluation of the samples included scoring 20 nuclei, in three different areas. The cases were scored twice, with a washout interval of at least 2 weeks. We observed an increase in the intraobserver concordance rate between the first and second evaluations with an increase in cell count. A count of 60 invasive cells was needed to obtain a concordance rate near 95% and an agreement rate greater than 0.80 by all observers. The interobserver concordance rate of the HER2 test also increased with the increase in cell count, reaching at least a 90% concordance rate with a count of 60 invasive cells. The median variability of both the HER2/CEP17 ratio and the average HER2 copy number between different evaluations decreased with the increase in cell count, being statistically higher in HER2-positive cases.

CONCLUSIONS

The minimal cell number recommended in current guidelines should be raised to at least 40, and preferably 60, invasive cells. Moreover, cases with amplification levels close to the threshold should be subjected to a dual count from an experienced observer.

Her2/neu Status Determination in Breast Cancer: A Single Institutional Experience Using a Dual-Testing Approach With Immunohistochemistry and Fluorescence In Situ Hybridization

OBJECTIVES

According to current guidelines, either immunohistochemistry (IHC) or in situ hybridization (ISH) can be used to determine human epidermal growth factor receptor 2 (Her2/neu) status in breast carcinoma. While the guidelines explicitly delineate result interpretation, there is no consensus on the most appropriate testing algorithm.

METHODS

The Her2/neu statuses of 369 consecutive cases of invasive breast cancer (from 351 patients) were assessed in a dual-testing algorithm that uses both IHC and fluorescence ISH (FISH). FISH was performed using dual-color HER2/ chromosome enumeration probe 17 ( CEP17 ) probes, and if equivocal results were obtained, reflex testing using HER2/lissencephaly gene 1 ( LIS1 ) probes was used. Results from both modalities were scored and reported using American Society of Clinical Oncology/College of American Pathologists 2013 criteria.

RESULTS

Sixty-one (16.5%) of the 369 tumors were found to be Her2/neu positive by at least one modality. The overall concordance between IHC and FISH results was 97.6%. Six of the 369 tumors were reclassified as Her2/neu positive after a negative IHC result. FISH was also able to identify significantly more Her2/neu-positive cases than IHC.

CONCLUSIONS

The commonly used reflex strategy based on IHC results may deny potentially beneficial targeted therapy for a small cohort of patients, which should be considered as testing guidelines are formulated and the cost-benefit analyses of various testing algorithms are assessed.

Well-differentiated invasive breast cancers with equivocal HER2 immunohistochemistry: what is the yield of routine reflex in-situ hybridization testing?

AIMS

The 2013 American Society of Clinical Oncology and the College of American Pathologists (ASCO/CAP) HER2 guidelines recommend testing all invasive breast cancers for HER2, typically with immunohistochemistry (IHC) followed by in-situ hybridization (ISH) when IHC is equivocal. As well-differentiated breast cancers are rarely HER2-positive, we assessed the value of routine reflex HER2 ISH testing for this subset of breast cancers.

METHODS AND RESULTS

We collected HER2 IHC 2+ cases and fluorescence in-situ hybridization (FISH) data from primary breast cancers with well-differentiated tumour types (grade 1 ductal carcinomas, classic lobular carcinomas, tubular, cribriform and pure mucinous carcinomas) at our centre from 2010 to 2015. Haematoxylin and eosin (H&E) and IHC slides were reviewed to confirm tumour type, grade and IHC score based on ASCO/CAP 2013 guidelines and their recent revisions. Of 4633 invasive carcinomas, 1133 had a well-differentiated tumour type; 177 of these were HER2 IHC equivocal, three of which were low-level amplified by FISH (0.3% of all well-differentiated tumours). One amplified case was classic invasive lobular carcinoma and two were invasive ductal carcinomas, grade 1. One amplified case had chromosome 17 monosomy, and one was rescored as HER2 IHC 1+ upon review. 'Basolateral' staining was noted in one amplified case and in 65 of 174 (37.4%) non-amplified cases. This incomplete membranous staining pattern was observed in the majority of invasive ductal carcinomas that were rescored as 1+ according to the revised 2013 guidelines.

CONCLUSIONS

The rate of HER2 amplification among well-differentiated breast cancers is very low. Basolateral staining in well-differentiated tumours may be overinterpreted as HER2 IHC 2+, but is rarely associated with HER2 amplification.

HER2 Gene Protein Assay Is Useful to Determine HER2 Status and Evaluate HER2 Heterogeneity in HER2 Equivocal Breast Cancer

OBJECTIVES

Approximately 15% of breast cancers show equivocal human epidermal growth factor receptor 2 (HER2) results on HER2 immunohistochemistry (IHC) and are reflexed for fluorescence in situ hybridization (FISH). However, some cases remain equivocal. In this study, we evaluated these double-equivocal cases by using a novel gene protein assay (GPA), which can simultaneously assess HER2 gene copy number and protein on a single slide using bright-field microscopy.

METHODS

GPA was performed on 42 HER2 IHC and FISH double-equivocal cases.

RESULTS

GPA was negative for amplification in 28 cases, equivocal in three cases, and positive in 11 cases. The GPA results showed excellent concordance with either repeat FISH using a chromosome 17 centromere probe or FISH using an alternative probe. Furthermore, HER2 heterogeneity was identified in three of 11 GPA-positive cases.

CONCLUSIONS

HER2 GPA performs accurately and is very useful to determine HER2 status in HER2 IHC and FISH double-equivocal breast cancer cases and identify HER2 heterogeneity.

RAI1 Alternate Probe Identifies Additional Breast Cancer Cases as Amplified Following Equivocal HER2 Fluorescence In Situ Hybridization Testing: Experience From a National Reference Laboratory

Context.—In 2013 the American Society of Clinical Oncology and College of American Pathologists updated the HER2 guidelines and changed the equivocal category for HER2 in situ hybridization testing to an average HER2 copy number of 4.0 to 5.9 with a HER2:CEP17 ratio of less than 2.0 and proposed retesting, with an option of using another control probe to avoid false-negative results. RAI1, located at band position 17p11.2, is a popular alternate probe locus for retesting equivocal changes.

Objective.—To review experience with the RAI1 alternate probe in HER2 fluorescence in situ hybridization equivocal breast cancers.

Design.—Primary and metastatic breast cancers with equivocal HER2 fluorescence in situ hybridization, retested with an alternate (RAI1) probe, were identified. HER2, RAI1, and CEP17 copy numbers, HER2 to control probe ratios, and genetic heterogeneity were recorded. Hematoxylin-eosin–stained slides were reviewed for type and grade of cancer.

Results.—Of 876 cases tested with CEP17 as the reference probe, 97 (11.1%) had equivocal HER2 fluorescence in situ hybridization results. Additional testing with the RAI1 probe classified 39.2% cases (38 of 97) as amplified with a HER2:RAI1 ratio ranging from 2.0 to 3.2 (mean, 2.37); 3.1% (3 of 97) were still unclassifiable because of a deletion of RAI1.

Conclusions.—RAI1 identified close to 40% of original HER2 fluorescence in situ hybridization equivocal cases as amplified, making these patients eligible for targeted therapies. It is not known whether guidelines for US Food and Drug Administration–approved probes can be extrapolated to alternate probes when an alternate control probe shows losses or gains. Because of the lack of guidelines for reporting HER2 status with alternate probes, laboratories face challenges in interpreting results.

The importance of tissue confirmation of metastatic disease in patients with breast cancer: lesson from a brain metastasis case

Background

The discrepancy of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) statuses in breast cancers has been reported. Available systemic therapy for patients with breast cancer is based on the molecular subtypes as identified by IHC and/or FISH. However, these biomarkers may change throughout tumor progression.

Case presentation

We report a relatively uncommon case of a 39-year-old Chinese woman with local advanced breast cancer (LABC) treated with 6 cycles of docetaxel, doxorubicin and cyclophosphamide (TAC) regimen neoadjuvant chemotherapy, and subsequently mastectomy, intensity-modulated radiation therapy (IMRT) and tamoxifen followed as regularly. Brain metastatic event appeared in 6 months after mastectomy. Treatment for brain metastasis was surgical resection and followed by whole brain radiotherapy (WBRT) approved by multidisciplinary team (MDT). Initial pathological diagnosis was IDC, cT4N1M0, luminal B (ER+ 90%, PR+90%, HER2 0, Ki67+ 70%) based on ultrasound-guided core needle biopsy. Surgical pathology revealed IDC, pT2N3M0 luminal B (ER+ 20%, PR+20%, HER2 0, Ki67+ 20%). Histological response to neoadjuvant chemotherapy is grade 3 according to the Miller/Payne grading system. Final pathology of brain metastasis showed a HER2 overexpression metastatic breast cancer luminal B (ER+ 70%, PR+ 70%, HER2 2+, Ki67+ 30%), FISH confirmed HER2 overexpression. Weekly paclitaxel plus trastuzumab was given for 12 weeks, then trastuzumab every 3 weeks for a whole year. Patient follow-up is still ongoing, no new events appear yet.

Conclusions

The determination of hormone receptors and HER2 status should be routinely performed in all involved tissues, if possible, and systemic therapy should be tailored following the latest finding.