HER2-positive Breast Cancer Cases Research Articles

Landscape of HER2-low breast cancer: Insights from a six-year study on incidence and clinicopathological characteristics.

e13148 Background: Human epidermal growth factor receptor 2 (HER2)-low breast cancer has emerged as a subtype of breast cancer, defined by HER2 1+ or 2+ in immunohistochemistry (IHC) and the absence of the ERBB2 gene amplification on fluorescence in situ hybridization (FISH). Recent trials showed marked response of HER2 breast cancer to novel anti-HER2 antibody-drug conjugates, rising interest in the HER2-low subtype. To date, data on characteristics of HER2-low breast cancer subtype is limited. Herein, we describe the clinicopathological characteristics of HER2-low breast cancer subtype compared HER2-zero/negative breast cancer. Methods: Real-world data from the Anatomic Pathology Division of Hotel Dieu de France, spanning 2017-2022, was retrospectively collected. Patients with HER2-IHC 3+ and HER2-IHC 2+ with ISH-amplified (HER2-positive) were excluded to compare HER2-low to HER2-zero breast cancer subtypes. Patients were then categorized based on their hormone receptor (HR) status. Clinicopathological characteristics between the groups were compared using a Chi-Square and Mann–Whitney U tests. Results: Out of 1195 patients, we observed 341 (28.5%) HER2-low breast cancers cases. HER2-positive breast cancer cases (n=178; 14.9%) were subsequently excluded. There was no significant difference in age and sex between the HER2-low and the HER2-zero group (p=0.3 and 0.8, respectively). HER2-low breast cancer was associated with positive estrogen receptor (ER) status and positive progesterone receptor (PR) status (p<0.001 and p=0.01, respectively). Ductal adenocarcinomas were more frequently observed in the HER2-low group, whereas lobular and metaplastic adenocarcinomas were especially prevalent in the HER2-zero group (all p<0.001). When stratified by HR status, 87.4% of patients had HR-positive status and 12.6% were HR-negative. Furthermore, the occurrence rate of tumors with a low Ki-67 labeling index was comparable between the two groups (p=0.9). However, among the HR-negative group, HER2-low tumors tended to show lower proliferation index compared to HER2-zero tumors (p = 0.04; Table). Conclusions: In conclusion, this study showed that HER2-low is a distinct from HER2-zero and is frequently present among patients with breast cancer. Clinicopathological features such as histological type differ between HER2-zero and HER2-low breast cancer. Our findings suggest that, within HR-negative breast cancer, breast cancer with low HER2 expression exhibits a less aggressive profile when compared to HER2-zero tumors. [Table: see text]

Landscape of HER2-low breast cancer: Insights from a six-year study on prevalence and clinicopathological characteristics

Human epidermal growth factor receptor 2 (HER2)-low breast cancer has emerged as a subtype of breast cancer, defined by HER2 1+/2+ in immunohistochemistry (IHC) and absence of ERBB2 gene amplification on fluorescence in situ hybridization (FISH). Recent trials showed marked response of HER2-low breast cancer to novel anti-HER2 antibody-drug-conjugates. Data on characteristics of HER2-low breast cancer subtype is limited. Real-world data from the Anatomic Pathology Department of Hotel-Dieu de France, spanning 2017–2023, was retrospectively collected. HER2-positive patients were excluded to compare HER2-low to HER2-zero breast cancer subtypes. Clinicopathological characteristics between the groups were compared using a Chi-Squared test. Out of 1195 patients, we observed 341 (28.5 %) HER2-low breast cancers cases. HER2-positive breast cancer cases (n = 178; 14.9 %) were excluded. There was no significant difference in age and sex between HER2-low and HER2-zero group (p = 0.33 and 0.79, respectively). HER2-low breast cancer was associated with positive estrogen receptor status and positive progesterone receptor status (p < 0.001 and p = 0.01, respectively). Ductal adenocarcinomas were more commonly observed in HER2-low group (p < 0.001). When stratified by hormone (HR) status, 87.4 % of patients had HR-positive status and 12.6 % were HR-negative. Among the HR-negative group, HER2-low tumors tended to show lower proliferation index compared to HER2-zero tumors (25%vs.10 %, p = 0.04). This study showed that HER2-low is distinct from HER2-zero and is common among patients with breast cancer. Clinicopathological features such as histological type differ between HER2-zero and HER2-low breast cancer. Within HR-negative breast cancer, those with low HER2 expression exhibit a less aggressive profile compared to HER2-zero tumors.

Abstract PO1-27-03: Studies on factors for pathological complete response after neoadjuvant chemotherapy in relation to HER2 status in primary breast cancer

Abstract Background: Neoadjuvant chemotherapy (NAC) has been increasingly used as the frontline therapy for the management of high-risk localized breast cancer (BC). Achieving pathological complete response (pCR) following NAC is associated with significantly better disease-free (DFS) and overall survival (OS), particularly for triple negative (TN) and HER2+ breast cancer. Among HER2 negative BC, HER2-low BC is a newly defined subset that has a HER2 immunohistochemical (IHC)-1+ or 2+/ISH negative phenotype. HER2 status is divided into 3 categories: HER2 positive, HER2-low, and HER2-zero. In this study, we investigated factors for pCR in relation to HER2 status and survival after NAC. Methods: A total of 197 cases with primary BC from January 2013 to July 2023 were enrolled in this study. There were 83 HER2 positive cases (including 7 HER2 2+/ISH+ cases) and 114 HER2 (78 HER2-low and 36 HER2-0) negative cases. HER2 3+ was dichotomized according to the staining cell rate (cut-off point; 90%) into the following two groups; HER2 3+/&amp;gt;90% (70 cases) and HER2 3+/&amp;lt; 90% (6 cases). The chemotherapy regimen was anthracycline and taxane with the addition of anti-HER2 therapy if the cases were HER2-positive. The clinicopathological factors examined were age, nodal status, tumor size, ER/PgR (cut-off points; 1% and 10%), and the Ki-67 index value (cut-off points: 20% and 40%). pCR was defined as the absence of residual invasive cancer on H&amp;E evaluation of the complete resected breast specimen (ypT0/Tis). We investigated the correlation between pCR and clinicopathological factors. The DFS and OS were calculated using the Kaplan-Meier method and analyzed using the log-rank procedure. Uni- and multivariate analyses of factors for pCR were performed using regression analysis. Results: 1. pCR was observed in 48 cases (57.8%) after NAC in the HER2 positive group and 17 cases (14.9%) in the HER2 negative group. 2. There was no significant relationship between the pCR rate and ER, PgR, Ki-67, menopausal and nodal status in the HER2 positive group. However, pCR was significantly observed more often in smaller tumors. HER2 3+( &amp;gt;90%) had a significantly higher pCR rate than HER2 3+(≤90%) and HER2 2+(ISH+). Multivariate analysis revealed that HER2 3+( &amp;gt;90%) and tumor size (≤5cm) were significant factors for pCR in HER2 positive BC cases. 3. Patients with pCR after NAC had significantly better DFS in HER2 positive BC cases. 4. There was a significant correlation between the pCR rate and ER≤10%, PgR≤10% and tumor size &amp;lt; 5cm in the HER2 negative BC cases. There was no relationship between the pCR rate and the HER2 status; 19.4% in HER2-0 and 12.8% in HER2-low. 5. Multivariate analysis revealed that the PgR status and tumor size were significant factors for pCR in the HER2 negative BC cases. 6. There was no significant difference in DFS between patients with pCR and non-pCR, especially in the luminal type BC cases. Moreover, no significant difference was observed between HER2-low and HER2-0. Conclusion: pCR rate after NAC was 57.8% in the HER2 positive cases and 14.9% in the HER2 negative cases. Moreover, the HER2 3+( &amp;gt;90%) group had a significantly higher pCR rate than the HER2 3+(≤90%) and HER2 2+(ISH+) groups. There was no correlation between the HER2 status (HER2-low and HER2-0) and pCR rate in the HER2 negative BC cases. In addition, the ER/PgR negativity (≤10%) was a significant factor for pCR in the HER2 negative cases. These findings suggest that the IHC data on the HER2 and ER/PgR status may be effective in predicting the pCR rate after NAC in BC cases. Citation Format: Nobuyuki Arima, Reiki Nishimura, Kazuhiro Muramoto, Atsushi Inayoshi, Tomio Tanigawa, Sugiko Watanabe. Studies on factors for pathological complete response after neoadjuvant chemotherapy in relation to HER2 status in primary breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-27-03.

Abstract 2524: Molecular and clinicopathologic landscape of HER2 positive breast cancer: A single institution study

Abstract Background: Human epidermal growth factor receptor 2 (HER2) is a transmembrane tyrosine kinase that is encoded by the ERBB2 gene, located on chromosome 17. Expression levels of HER2 are a key pathogenic and treatment-associated factor in breast carcinomas, with HER2 expression reported as per the ASCO/CAP scoring guidelines. Outside the intense focus on the HER2 overexpression few studies currently exist that look at the comprehensive molecular profile of these aggressive tumors. Design: Our institutional pathology database was searched for patients with breast carcinoma diagnosed between 2009 and 2013 and with HER2 scored as 3+ based on immunohistochemistry, or HER2 2+ with confirmatory positive FISH results. Comprehensive next-generation sequencing (NGS) was performed using the Illumina TruSight Oncology 523 gene panel, and clinicopathologic data were gathered from the institutional electronic health record system. A CoMutation plot was made using the CoMut python library. Results: The mean age of the patients at time of diagnosis was 56.1±12.7 years. The tumors were overwhelmingly high-grade, with 26/30 being grade 3 and the remaining 4/30 being grade 2 and a mean size of 2.6 cm. All were histologically invasive ductal carcinoma, and 26/30 were scored as HER2 3+ on IHC while 4/30 were HER2 2+ with positive FISH. ER was positive in 30% of cases (9/30), PR was positive in 23.3% (7/30), p53 was positive by IHC in 53.3% (16/30), and the mean Ki-67 proliferative index was 47.1%. 20 of the 30 (66%) cases meeting the inclusion criteria had pathogenic mutations detected by NGS testing. Several distinct molecular subgroups were seen on the CoMutation plot (figure 1). The mean tumor mutational burden (TMB) was 14.1 mutations per megabase. A significant subset of the tumors 70% (14/20) showed TP53 mutations, and 30% (6/20) show PIK3CA mutations. Of interest, only 1/14 tumors showed a co-occurring homologous recombination repair gene mutation and one tumor (1/20) showed mutations in 2 homologous recombination pathway genes (FANCA and BRCA1) as well as numerous additional mutations (tumor mutational burden of 65.3 mutations per megabase). Conclusion: Overall the mean TMB was 14.1 mutations/megabase in this HER2-positive breast cancer study set. Over 2/3 of our HER2-positive breast cancer cases also had TP53 mutations. In addition, 1/3 had PIK3CA mutations, suggesting that a subset of HER2-positive carcinomas also harbor other potentially actionable mutations which may increase the effectiveness of our existing interventions. Additional studies are needed to further subclassify genetically distinct subsets of HER2-positive breast cancers and to further understand clinical, pathologic and treatment-related differences in this aggressive breast cancer subset. Citation Format: Gokce Deniz Ardor, Zachary M. Coty-Fattal, Luis Z. Blanco, Kalliopi Siziopikou. Molecular and clinicopathologic landscape of HER2 positive breast cancer: A single institution study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2524.

DNA Methylation-Regulated HOXC8's Role in HER2-Positive Breast Cancer Function and its Contribution to Herceptin Resistance.

The epidermal growth factor receptor 2 (HER2) is overexpressed in 30% of breast cancers, and this overexpression is strongly correlated with a poor prognosis. Herceptin is a common treatment for HER2-positive breast cancer; however, cancer cells tend to adapt gradually to the drug, rendering it ineffective. The study revealed an association between the methylation status of the Homeobox C8 (HOXC8) gene and tumor development. Therefore, it is of paramount importance to delve into the interaction between HOXC8 and HER2-positive breast cancer, along with its molecular mechanisms. This exploration holds significant implications for a deeper understanding of the pathophysiological processes underlying HER2-positive breast cancer. Tumor tissue and pathological data from patients with HER2-positive breast cancer were systematically collected. Additionally, the human HER2-positive breast cancer cell line, SKBR3, was cultured in vitro to assess both the expression level of HOXC8 and the degree of DNA methylation. The study aimed to explore the relationship between the relative expression of HOXC8 and the clinical characteristics of breast cancer patients. The expression level of HOXC8 and the promoter methylation of HOXC8 were verified by methylation treatment of SKBR3 breast cancer cells. The regulation of HOXC8 was meticulously carried out, leading to the division of the cells into distinct groups. The study further analyzed the expression levels and biological capabilities within each group. Finally, the in vitro and in vivo sensitivity of the cells to Herceptin, a common treatment for HER2-positive breast cancer, was measured to assess the efficacy of the drug. In HER2-positive breast cancer cases characterized by poor methylation, there was an up-regulation of HOXC8. Its expression was found to be correlated with key clinical factors such as tumor size, lymph node status, clinical tumor, node, metastasis (cTNM) staging, and Herceptin resistance (p < 0.05). Upon methylation of breast cancer cells, there was a significant decrease in HOXC8 expression (p < 0.05). The study revealed that overexpression of HOXC8 resulted in increased proliferation, cloning, and metastasis of HER2-positive breast cancer cells, along with a reduced apoptosis rate (p < 0.05). Conversely, interference with HOXC8 expression reversed this scenario (p < 0.05). A Herceptin-resistant substrain, POOL2, was established using SKBR3 cells. Animal studies demonstrated that overexpressing HOXC8 accelerated tumor development and enhanced POOL2 cells' resistance to Herceptin (p < 0.05). However, following interference with HOXC8, POOL2 cells exhibited increased responsiveness to Herceptin, leading to a gradual reduction in tumor size (p < 0.05). In HER2-positive breast cancer, the expression of HOXC8 is elevated in a manner dependent on DNA methylation, and this elevated expression is closely linked to the pathology of the patient. Interfering with HOXC8 expression demonstrates the potential to partially inhibit the development and spread of breast cancer, as well as to alleviate resistance to Herceptin.

Changes in HER2 status and survival outcomes in patients with non-pathological complete response after neoadjuvant targeted treatment.

To study the changes in human epidermal growth factor receptor 2 (HER2) expression in patients with HER2-positive breast cancer before and after neoadjuvant treatment. The clinicopathologic data of 499 patients with HER2-positive breast cancer who completed neoadjuvant treatment and surgery at the Fourth Hospital of Hebei Medical University from 2018 to 2021 were retrospectively analyzed. According to the new adjuvant regimen, 298 patients were divided into the trastuzumab + pertuzumab combined chemotherapy group (dual target group), and 201 patients were divided into the trastuzumab combined chemotherapy group (single target group).The effect of different neoadjuvant regimens on HER2 status was analyzed by comparing HER2 expression before and after treatment. A total of 255 of 499 neoadjuvant patients with HER2-positive breast cancer achieved a pathological complete response (pCR). pCR was achieved in 60.07% (179/298) of the dual target group and 37.81% (76/201) of the single target group, and the difference was statistically significant (χ² = 23.795, P < .001). Among 244 cases of HER2-positive breast cancer that did not reach pCR (non-pCR), there was a certain negative conversion rate of HER2 expression after neoadjuvant treatment, and the overall negative conversion rate was 13.11% (32/244). The negative conversion rates of the dual target group was 17.65% (21/119) and single target group was 8.80% (11/125), (χ² = 4.188, P = .041). The DFS of 499 patients in the pCR group was 98.43% (251/255), which was significantly higher than that in the non-pCR group 92.21% (225/244), (χ² = 8.536, P = .003). Only 2 (0.20%) of 32 patients with negative HER2 had recurrence and metastasis. Neoadjuvant treatment had an effect on the expression status of HER2, especially in the dual target group. For patients with negative HER2, the optimal treatment strategy remains to be explored, but continued anti-HER2 treatment is still recommended.

Investigation of Tumor Heterogeneity Using Integrated Single-Cell RNA Sequence Analysis to Focus on Genes Related to Breast Cancer-, EMT-, CSC-, and Metastasis-Related Markers in Patients with HER2-Positive Breast Cancer.

Human epidermal growth factor receptor 2 (HER2) protein, which is characterized by the amplification of ERBB2, is a molecular target for HER2-overexpressing breast cancer. Many targeted HER2 strategies have been well developed thus far. Furthermore, intratumoral heterogeneity in HER2 cases has been observed with immunohistochemical staining and has been considered one of the reasons for drug resistance. Therefore, we conducted an integrated analysis of the breast cancer single-cell gene expression data for HER2-positive breast cancer cases from both scRNA-seq data from public datasets and data from our cohort and compared them with those for luminal breast cancer datasets. In our results, heterogeneous distribution of the expression of breast cancer-related genes (ESR1, PGR, ERBB2, and MKI67) was observed. Various gene expression levels differed at the single-cell level between the ERBB2-high group and ERBB2-low group. Moreover, molecular functions and ERBB2 expression levels differed between estrogen receptor (ER)-positive and ER-negative HER2 cases. Additionally, the gene expression levels of typical breast cancer-, CSC-, EMT-, and metastasis-related markers were also different across each patient. These results suggest that diversity in gene expression could occur not only in the presence of ERBB2 expression and ER status but also in the molecular characteristics of each patient.

Efficacy of neoadjuvant therapy on HER2-positive breast cancer: a clinicopathological analysis

Objective: To investigate the efficacy of neoadjuvant therapy (NAT) on HER2-positive breast cancer and to analyze their clinicopathological features. Methods: A total of 480 cases of HER2-positive breast cancer who received neoadjuvant therapy (NAT), diagnosed at the Department of Pathology of Fudan University Shanghai Cancer Center from 2015 to 2020, were retrospectively identified. Clinicopathological parameters such as age, tumor size, molecular subtype, type of targeted therapy, Ki-67 proliferation index, ER and HER2 immunohistochemical expression, and HER2 amplification status were analyzed to correlate with the efficacy of NAT. Results: Among 480 patients with HER2-positive breast cancer, 209 achieved pathology complete response (pCR) after NAT, with a pCR rate of 43.5%. Of all the cases,457 patients received chemotherapy plus trastuzumab and 23 patients received chemotherapy with trastuzumab and pertuzumab. A total of 198 cases (43.3%) achieved pCR in patients with chemotherapy plus trastuzumab, and 11 cases (47.8%) achieved pCR in patients with chemotherapy plus trastuzumab and pertuzumab. The pCR rate in the latter group was higher, but there was no statistical significance. The results showed that the pCR rate of IHC-HER2 3+patients (49%) was significantly higher than that of IHC-HER2 2+patients (26.1%, P<0.001). The higher the mean HER2 copy number in the FISH assay, the higher the pCR rate was achieved. The expression level of ER was inversely correlated with the efficacy of NAT, and the pCR rate in the ER-positive group (28.2%) was significantly lower than that in the ER-negative group (55.8%, P<0.001). The pCR rate (29.1%) of patients with luminal B type was lower than that of HER2 overexpression type (55.8%, P<0.001). In addition, higher Ki-67 proliferation index was associated with higher pCR rate (P<0.001). The pCR rate was the highest in the tumor ≤2 cm group (57.7%), while the pCR rate in the tumor >5 cm group was the lowest (31.1%). The difference between the groups was significant (P=0.005). Conclusions: HER2 copy numbers, HER2 immunohistochemical expression level, molecular subtype, ER expression level and Ki-67 proliferation index are significantly associated with pCR after NAT. In addition, fluorescence in situ hybridization results, HER2/CEP17 ratio and tumor size could also significantly affect the efficacy of NAT.

Abstract P2-04-01: Immunoexpression of markers related to the HER2 pathway in cases of pure positive her2 breast carcinoma treated with trastuzumab

Abstract Introduction: Breast cancer is a heterogeneous disease with well-defined molecular subtypes and variable clinical behavior. The overexpressed HER2 subtype represents approximately 20% of all breast carcinomas. It is associated with a poor prognosis, increased risk of systemic and brain metastases, and poor overall survival until the advent of anti-HER2 therapies, such as trastuzumab. Its introduction into clinical practice has improved the prognosis in cases of breast cancer with overexpressing of pure HER2. However, some cases develop resistance to this drug. Objectives: To evaluate immunoexpression of possible markers involved in the HER2 pathway in breast carcinoma with overexpressing of pure HER2 treated with trastuzumab. Methods: We included 90 patients diagnosed with pure positive HER2 breast carcinoma treated with trastuzumab at the IBCC and HSP/Unifesp public hospitals between 2009 and 2018. Through immunohistochemistry, markers involved in the HER2 pathway (MUC4, IGF-1, IGF-1R, EGFR, p21, p27, p53, p16, cyclin D1, PTEN, CDK4, Bcl-2, VEGF, AR, MDM2, and TNFα) were analyzed samples paraffin-embedded of tumor and compromised lymph nodes and then, correlated with clinicopathological variables. The statistics were performed using the SPSS® software, version 25, from the company IBM, values equal to or less than 0.05 were considered significant (p ≤0.05). To verify possible associations between the clinical-pathological variables and the analyzed markers, Pearson’s X2 test, and Fisher’s exact test were used; for survival analysis, the Kaplan-Meier method was used. Results: Treatment resistance of pure HER2-positive breast cancer cases after trastuzumab treatment was 40%; the OS of this series was 4.13 years (95% CI 5.1 - 12.5) and the DFS was 3.6 years (95% CI 5.1 - 13.1). In the tumor samples it was possible to determine potential markers of good prognosis: cyclin D1 with nuclear grade (p=0.049) and recurrence (p=0.038); IGF-1 with tumor size (p= 0.015) and death (p= 0.046); p16 with response to treatment (p= 0.016); PTEN with response to treatment (p= 0.050) and death (p= 0.030). The results also showed possible markers of poor prognosis such as p53 with SBR GH (p= 0.003) and GN (p= 0.048); and IGF-1R with compromised lymph node (p=0.016). In compromised lymph nodes samples, the correlations showed TNFα with tumor size (p=0.043); and CDK4 with the response to treatment (p=0.011) as possible markers of good prognosis; only p53 with GH SBR grade (p= 0.045) maintained its potential for poor prognosis. Conclusions: In tumor samples, it was possible to demonstrate that the markers: cyclin D1, IGF-1, p16, and PTEN had the potential for a good prognosis panel and p53 and IGF-1R for worse. In samples of compromised lymph nodes, p53 remained as a marker of poor prognosis, while TNFα and CDK4 of good prognosis. Citation Format: Andreia Fabiana V. Franco, Angela Flavia L. Waitzberg, Joaquim T. Araujo Neto, Fatima S. Pasini. Immunoexpression of markers related to the HER2 pathway in cases of pure positive her2 breast carcinoma treated with trastuzumab [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-04-01.

Network Pharmacological Analysis Identifies the Curcumin Analog CCA-1.1 Targeting Mitosis Regulatory Process in HER2-Positive Breast Cancer

Recent studies present that the CCA-1.1 (a curcumin derivative) impedes the proliferation of breast cancer cells (luminal, HER2-overexpressed, and TNBC cells). Currently, we analyze the possible target of action of CCA-1.1, particularly in breast cancer cells with HER2 amplification using bioinformatics analysis. The differentially expressed genes (DEGs) of HER2-positive breast cancer were retrieved from TCGA-BRCA data (via UALCAN). We used three web-based tools (Swiss Target Prediction, BindingDB, and TargetNet) to predict the potential target of CCA-1.1 using the SMILE-similarity feature. The functional annotation and network enrichment were processed in WebGestalt. The alteration of selected genes was observed in CBioPortal. The protein-protein interaction (PPI) network was constructed in STRING, then ranked based on the degree score using Cytohubba feature in Cytoscape. The survival analysis from the hub-gene was collected in GEPIA2 with selection only for HER2-positive breast cancer cases. The correlation between the hub genes and tumor-infiltrating immune markers was determined using TIMER web tools. The pathway network analysis highlighted the cell cycle regulation in mitosis as affected signaling amid the putative CCA-1.1 targets. We denoted eight potential genes that could be responsible for inhibiting mitosis regulation upon CCA-1.1 treatment, including AURKA, AURKB, PLK1, TPX2, KIF11, MELK, CDK1, and CHEK1. Several of the potential markers (AURKB, AURKA, CDK1, and CHEK1) revealed to be correlated with the immune cells’ infiltration markers. CCA-1.1 might regulate mitosis to induce cell cycle arrest and lead to cell death. The predicted targets of CCA-1.11 gave insight into the potency of CCA-1.1 to be with immunotherapy. Further validation of the data presented in the study is essentially needed to develop CCA-1.1 for breast cancer.

Long-term follow-up of early stage HER2-positive breast cancer patients treated with trastuzumab: A population-based real world multicenter cohort study.

IntroductionSince its introduction in standard of care, trastuzumab has revolutionized the treatment of patients with early and late stages of HER2-positive breast cancer. While the initial clinical trials were convincing and lead to major changes in practice, more knowledge on the long-term outcome and tolerability is needed. The present study was designed to assess the survival, prognostic factors and relapse patterns after the implementation of trastuzumab in a real-world cohort.MethodsAll cases of HER2-positive breast cancer diagnosed between 2006 and 2014 in the Southeast Healthcare Region of Sweden were retrospectively identified. Medical records were thoroughly reviewed with regard to clinicopathological parameters, treatments, relapse pattern and adverse events.Results643 patients were identified and 599 were eligible for analysis. Breast cancer specific survival, distant recurrence free survival and local recurrence free survival were 93.4%, 89.7% and 98.0% for trastuzumab treated patients and 87.4%, 81.6% and 87.4% in patients not treated with trastuzumab, respectively. ER status, nodal status and trastuzumab treatment were all independent prognostic factors in multivariable analysis. No new safety concerns were discovered.ConclusionThe real-world outcome of trastuzumab-treated patients with early HER2-positive breast cancer is similar to what has been previously reported in long-term follow up of prospective clinical trials. ER status, nodal status and trastuzumab treatment are independent prognostic factors for breast cancer specific mortality rate, distant recurrence rate and locoregional recurrence rate in HER2-positive patients in the trastuzumab era.

Mammographic density to predict response to neoadjuvant systemic breast cancer therapy.

Mammographic density (MD) is a risk factor for breast cancer (BC) development, and recurrence. However, its predictive value has been less studied. Herein, we challenged MD as a biomarker associated with response in patients treated with neoadjuvant therapy (NAT). Data on all NAT treated BC patients prospectively collected in the registry of Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy (2009-2019) were identified. Diagnostic mammograms were used to evaluate and score MD as categorized by the Breast Imaging-Reporting and Data System (BI-RADS), which identifies 4 levels of MD in keeping with relative increase of fibro-glandular over fat tissue. Each case was classified according to the following categories a (MD < 25%), b (26-50%), c (51-75%), and d (> 75%). The association between MD and pathological complete response (pCR), i.e., absence of BC cells in surgical specimens, was analyzed in multivariable setting used logistic regression models with adjustment for clinical and pathological variables. A total of 442 patients were analyzed, 120 of which (27.1%) attained a pCR. BI-RADS categories a, b, c, and d accounted for 10.0%, 37.8%, 37.1% and 15.2% of cases. Corresponding pCR were 20.5%, 26.9%, 30.5%, 23.9%, respectively. At multivariable analysis, when compared to cases classified as BI-RADS a, those with denser breast showed an increased likelihood of pCR with odds ratio (OR) of 1.70, 2.79, and 1.47 for b, c and d categories, respectively (p = 0.0996), independently of age, BMI [OR underweight versus (vs) normal = 3.76], clinical nodal and tumor status (OR T1/Tx vs T4 = 3.87), molecular subtype (HER2-positive vs luminal = 10.74; triple-negative vs luminal = 8.19). In subgroup analyses, the association of MD with pCR was remarkable in triple-negative (ORs of b, c and d versus a: 1.85, 2.49 and 1.55, respectively) and HER2-positive BC cases (ORs 2.70, 3.23, and 1.16). Patients with dense breast are more likely to attain a pCR at net of other predictive factors. The potential of MD to assist decisions on BC management and as a stratification factor in neoadjuvant clinical trials should be considered.

Clinical therapeutic effects of trastuzumab in HER2-positive breast cancer patients: A protocol for systematic review and meta-analysis.

Background:Despite the developments in diagnosis and treatment of HER2-positive metastatic breast cancer, there is a high likelihood in the development of resistance to trastuzumab. In general, HER2-positive patients with deteriorated health face negative clinical outcomes. The present study is conducted to systematically explore the medicinal properties of trastuzumab in HER2-positive breast cancer patients.Methods:Randomized controlled trials investigating the clinical properties of including trastuzumab to treat HER2-positive breast cancer cases will be sourced by exploring these online-based databases: MEDLINE, BIOSIS, China National Knowledge Infrastructure (CNKI), Cochrane Library, EMBASE, Central Register of Controlled Trials, and WanFang. Two independent authors will screen the literature, gather data, and assess the quality of selected studies. The significance of the relationship between the medical properties of trastuzumab when incorporated to treat HER2-positive breast cancer cases will be evaluated according to the relative risk, mean differences or standardized mean differences, and 95% confidence interval.Results:The outcomes from this review shall be issued in a journal that will be reviewed by peers.Conclusion:The conclusions presented in this review will serve as a reference for clinical practitioners and scholars to determine whether trastuzumab is an effective and safety intervention for treating HER2-positive breast cancer patients.Ethics and dissemination:Since this study is a systematic review of published studies, an ethical approval is not needed.Systematic review registration number:March 31, 2021.osf.io/wvqkf (https://osf.io/wvqkf/).

Abstract PS2-30: The expression of PD-L1 (Ventana SP142) in HER2-positive breast cancer and its relationship with clinicopathological characteristics

Abstract Objective: This article aims to investigate the correlation between the expression of PD-L1 and tumor-infiltrating lymphocytes, clinicopathological features and prognosis in HER2-positive breast cancer.Methods: This study included 156 cases of HER2-positive breast cancer. Three 2mm tumor cores were selected for each case, and the expression of PD-L1 on ICs was detected by Immunohistochemistry. Statistical software SPSS 24.00 was used for analysis, χ2 test and Fisher exact test were used for correlation and consistency analysis; Logistic regression analysis was used for multivariate analysis; Kaplan-Meier analysis was used for univariate survival; Cox regression analysis was used for multivariate survival; TILs and PD-L1 correlation was analyzed by Spearman rank; P&amp;lt;0.05 was considered statistically significant.Results: In HER2-positive breast cancer the expression rate of PD-L1 on ICs was 31.4%. In HER2-positive breast cancer the expression of PD-L1 on ICs was significantly correlated with the tumor size, the presence or absence of lymphovascular invasion, the expression of TILs, CD4 and CD8 (P&amp;lt;0.05); obtained using Logistic multivariate regression analysis The tumor size, the presence or absence of vascular tumor plugs, the expression of TILs and CD8 were independent factors affecting PD-L1 expression (P &amp;lt;0.05). Spearman rank correlation analysis showed that TILs infiltration level was positively correlated with interstitial immune cell PD-L1 expression in HER2-positive breast cancer patients (r = 0.486,P &amp;lt;0.05). Univariate survival analysis of disease-free survival (DFS) for HER2-positive breast cancer the patient's tumor size, lymphovascular invasion, lymph node metastasis, TILs, tumor immune microenvironment classification-CD4 (TIME-CD4) and tumor immune microenvironment classification-CD8 (TIME-CD8) has a significant effect on patients' DFS (P&amp;lt;0.05); multivariate survival analysis revealed that patients had lymphovascular invasion, TILs, TIME-CD4 and TIME-CD8 as HER2-positive breast cancer independent factors of DFS (P&amp;lt;0.05).Conclusions: The expression of PD-L1 on ICs in HER2-positive breast cancer is related to tumor size, presence or absence of lymphovascular invasion, TILs,CD4 expression and CD8 expression.The independent influencing factors of disease-free survival in patients with HER2-positive breast cancer are the presence or absence of lymphovascular invasion, TILs, TIME-CD4 and TIME-CD8. Among them, patients with no lymphovascular invasion and higher levels of tumor infiltrating lymphocytes had better prognosis; CD4-/PD-L1- group had better prognosis in the TIME-CD4 and CD8+/PD-L1- group had better prognosis in the TIME-CD8. There is a positive correlation between TILs infiltration level and PD-L1 expression, suggesting that HER2-positive breast cancer patients can be accurately treated according to different TILs infiltration levels and PD-L1 expression.Key words: breast cancer; HER2-positive;PD-L1;TILs Citation Format: Ningning Zhang, Yueping Liu. The expression of PD-L1 (Ventana SP142) in HER2-positive breast cancer and its relationship with clinicopathological characteristics [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS2-30.

Dysregulation of TLR2 Serves as a Prognostic Biomarker in Breast Cancer and Predicts Resistance to Endocrine Therapy in the Luminal B Subtype.

Background: Breast cancer (BCa) is a serious global health burden among females, and the development of resistance represents an important challenge to BCa treatment. Here, we examined the expression of toll-like receptor 2 (TLR2) in BCa patients and the prognostic value of TLR2 for predicting endocrine resistance.Methods: The study included 150 BCa patients, of which 82 underwent endocrine therapy. TLR2 mRNA expression was measured by quantitative Real-Time PCR, and its prognostic value was determined by Kaplan-Meier survival analysis. Changes in the expression of TLR2 in BCa patients with endocrine resistance were assessed, and the value of TLR2 for predicting endocrine resistance was evaluated using the receiver operating characteristic curve analysis.Results: TLR2 expression was higher in BCa tissue than in normal tissue and associated with tumor size, HER2 status, tumor subtype, and TNM stage. TLR2 upregulation was associated with poor prognosis in patients with BCa, as well as endocrine resistance, and TLR2 upregulation was more prevalent among HER2-positive BCa cases. The predictive performance of TLR2 for endocrine resistance was higher in HER2-positive BCa than in other hormone receptor-positive BCa cases.Conclusion: TLR2 upregulation is a promising biomarker for prognosis and predicting resistance to endocrine therapy. The relationship between TLR2 and HER2 indicates that TLR2 may be involved in endocrine resistance through the HER2 signaling pathway in BCa.

Abstract P6-09-12: Using multiphoton laser scanning microscopy to assess neoadjuvant therapy outcome in core needle biopsies: A novel methodology

Abstract Background: Over-expression of Human Epidermal Growth Factor receptor-2 (HER2) in breast cancer is associated with an aggressive clinical course and poor prognosis. Targeting HER2 over-expression has been shown to be a remarkably effective therapeutic modality in the metastatic, adjuvant and neoadjuvant setting and the pathologic response to neoadjuvant treatment in HER2-positive breast cancer has been shown to be an excellent surrogate for a good outcome. The stromal tumor microenvironment is implicated in fostering tumor growth, facilitating cell migration and ultimately resulting in metastatic disease. Specifically, the collagenous extracellular matrix, which includes fibrillar collagen, has been suggested to play a role in the migration of malignant breast epithelial cells within the surrounding stroma. We have developed a novel methodology which uses an intrinsic optical signature to quantitatively evaluate fibrillar collagen (Burke et al. BMC Cancer 15 (2015): 929). Here, we evaluate the ability of this quantitative methodology to predict the pathologic response after neoadjuvant HER2-targeted treatment as assessed by the Residual Cancer Burden score/class (RCB). This quantitative evaluation in pre-treatment biopsies is then correlated with the pathologic response to treatment in the post-therapy resection. Material and Methods: Clinical pathologic variables for 29 cases of HER2-positive breast cancer that had undergone neoadjuvant chemotherapy plus HER2-targeted therapy were retrieved from the medical record database at URMC, including the post-treatment RCB score and ER/PR/HER2 status. Second harmonic generation (SHG) is an intrinsic optical signal produced by fibrillar collagen. To quantify collagen microstructure in the pre-treatment core biopsy, we used SHG imaging to determine the average forward to backward-light scattering ratio (F/B). The F/B ratio is sensitive to structural properties of collagen fibers. Results: Logistic regression was used to assess the association between F/B and the binary response variable RCB class (0/1 or 2/3). A likelihood ratio test was used to calculate the p-value to test whether the regression coefficient for F/B was zero (i.e. no effect) in the tumor-stromal interface. The average F/B ratio at the leading edge of the tumor stratified by RCB class is shown in Table 1. When evaluated in the bulk of the tumor tissue, F/B was not correlated with RCB status; however, when evaluated at the leading edge of the tumor stromal interface, F/B was significantly correlated with RCB status (p=0.035). Table 1:RCB class and average F/BRCB class (n)Average F/B ± SEM0/1 (19)16.95 ± 1.062/3 (10)12.32 ± 1.84 Conclusions: We have previously shown that the measurement of F/B in the primary tumor after resection is an independent prognostic indicator of metastasis-free survival in breast cancer. Our results in the current study furthers these observations and suggests that the evaluations of the microstructure of collagen fibers by F/B measurement from the pre-treatment biopsy, specifically at the leading edge of the tumor-stroma interface, may be useful for predicting pathologic response to trastuzumab-based neoadjuvant therapy. Further studies in a larger patient cohort are warranted. Citation Format: Desa DE, Turner BM, Buscaglia B, Hill RL, Strawderman RL, Hicks DG, Brown EB. Using multiphoton laser scanning microscopy to assess neoadjuvant therapy outcome in core needle biopsies: A novel methodology [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-09-12.

Hormonal treatment combined with targeted therapies in endocrine-responsive and HER2-positive metastatic breast cancer.

Approximately 50% of HER2 positive breast cancer cases are also estrogen receptor (ER) positive. Data supports a role for close cross-talk between the ER and HER2 signaling pathways as an important contributor to the development of de novo or acquired resistance to hormone therapies. Therefore a strategy that simultaneously blocks both signaling pathways is a reasonable approach to prevent or overcome either endocrine or anti-HER2 therapy resistance. Moreover, preclinical data support the idea that PI3K inhibitors and CDK4/6 could be an attractive target that functions downstream of both ER and HER2 pathways. We conducted a literature review of the results of phase II and III studies testing targeted therapies in metastatic breast cancer with HER2-positive and hormonal-receptor-positive disease. The analyses included efficacy and toxicity data from earlier studies with a single anti-HER2 drug combined with hormonal therapy up to more recent studies testing new molecules targeting these signaling pathways. The aims of this review are to summarize current knowledge and to discuss research development including the possibility to spare chemotherapy in this subgroup of HER2-positive breast cancer patients.

Abstract P2-06-02: Breast cancer HER2 epigenetic intratumoral heterogeneity results from lack of HER2 protein translation

Abstract Research objective Previously, we reported the negative correlation between pathological complete response (pCR) and HER2 positive breast cancer exhibiting amplified HER2 gene tumor cells without HER2 protein overexpression (HER2 epigenetic intratumoral heterogeneity) among trastuzumab-based neoadjuvant chemotherapy treated patients. Our objective in this study was to elucidate if tumor cells with HER2 epigenetic intratumoral heterogeneity express HER2 RNA using a HER2 RNA in situ hybridization (ISH) method. Materials and methods Formalin-fixed, paraffin-embedded (FFPE) sections of breast cancer biopsy samples were investigated for HER2 RNA expression at the individual cell level using a HER2 RNA ISH assay. RNA preservation in tissue sections was examined using a peptidylprolyl isomerase B (PPIB) RNA ISH assay. Three groups of cases were examined: 1) HER2 negative breast cancer cases (HER2 RNA ISH negative control group). 2) HER2 positive breast cancer cases with homogeneous HER2 positive tumor cells (HER2 RNA ISH positive control; pCR group) 3) HER2 positive breast cancer cases with HER2 epigenetic intratumoral heterogeneity (a mixture of HER2 gene and protein positive tumor cells and HER2 gene positive tumor cells without HER2 protein expression; incomplete response group) Consecutive sections of HER2 RNA ISH slides were stained for HER2 gene and protein concurrently on the same tissue section using HER2 gene-protein assay (GPA) which is a combination of FDA-approved HER2 immunohistochemical (HER2 protein) and HER2 dual ISH (HER2 gene and chromosome 17 centromere) assays. Analyses of HER2 RNA expression in individual cells was microscopically evaluated and matched to HER2 GPA slides. Results RNA preservation was confirmed in tissue sections of all three groups by a PPIB RNA ISH assay. Tumor cells of HER2 negative breast cancer cases (negative control group) lacked HER2 RNA ISH signal while HER2 gene and protein positive tumor cells of homogeneous breast cancer cases (positive control group) demonstrated high HER2 RNA expression levels. HER2 gene and protein positive tumor cells of HER2 positive intratumoral heterogeneity cases showed high HER2 RNA expression. However, amplified HER2 gene breast cancer cells without HER2 protein overexpression of HER2 positive intratumoral heterogeneity cases also showed high levels of HER2 RNA expression. Thus, revealing in cases with intratumoral heterogeneity, transcription of HER2 RNA occurs, but translation of HER2 protein is altered by some mechanism(s) in tumor cells. Conclusions Transcription of HER2 RNA was observed in breast tumor cells with amplified HER2 gene but absence of HER2 protein overexpression (HER2 epigenetic intratumoral heterogeneity) of patients who showed incomplete response to neoadjuvant trastuzumab therapy. Our study suggests that inconsistent HER2 protein translation in breast cancer with HER2 epigenetic heterogeneity might be the primary resistance mechanism to trastuzumab-based neoadjuvant chemotherapy. Citation Format: Nitta H, Horii R, Murillo A, Portier B, Akiyama F. Breast cancer HER2 epigenetic intratumoral heterogeneity results from lack of HER2 protein translation [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-06-02.

Abstract 5428: Lactate production as a potential marker of HER2-addiction and Trastuzumab susceptibility

Abstract Background: Although the introduction of the HER2-specific humanized monoclonal antibody Trastuzumab (T) in clinical practice revolutionized the treatment of HER2-positive breast cancer (BC), about half of the T-treated patients do not benefit or become refractory after its administration. Despite different molecular tumor profiles significantly associated with T benefit were reported, the identification of a non invasive clinical approach to select patients responsive or not to T is still a clinical unmet task. We recently reported that mammary cancer cell lines derived from spontaneous nodules arisen in mice transgenic for the human d16HER2 splice variant (HER2-addicted) were significantly enriched in genes involved in glycolysis pathway versus those developed in mice transgenic for the human full-length HER2-positive (WTHER2) (HER2-non addicted) (1,2). Accordingly, the aim of our study was to define whether tumor lactate levels could reflect HER2 addiction and, in turn, T susceptibility. Methods: The metabolite content in murine and human HER2-positive cell lines and specimens was determined by quantitative Nuclear Magnetic Resonance (NMR) spectroscopy. The optical metabolic imaging that quantifies the levels of the anaerobic glycolysis-related metabolite nicotinamide adenine dinucleotide (NADH) and the aerobic metabolite flavin adenine dinucleotide (FAD) was represented by Optical redox ratio (NADH/FAD). The extracellular levels of lactate were calculated by blood gas analyzer. Results: The metabolic profile of HER2-addicted (MI6, MI7) versus -non-addicted (WTHER2_1, WTHER2_2) murine tumor cells revealed higher intracellular levels of metabolites associated to glycolysis in MI6 and MI7 cells versus WTHER2-positive cells. In keeping, also the evaluation of the metabolic profile of human HER2-positive BC cell lines classified as addicted (SKBR3 and BT474) or not (MDAMB453 and MDAMB361) to HER2-signaling (3) confirmed significant higher intracellular and extracellular levels of lactate in HER2-addicted versus -non-addicted cells. The extracellular levels of NADH and NADH/FAD ratio further sustained a significantly higher activity of an anaerobic metabolism in HER2-addicted cells. Noteworthy, the metabolic profile of 27 HER2-positive BC cases treated with T, classified as HER2-addicted or not on the basis of the activation status of d16HER2 (1), provided further evidence of significantly higher levels of lactate in tumors HER2-addicted. Conclusions: Overall, even if a dysregulated glucose metabolism is a tumor hallmark, our results provide relevant in vitro and in vivo evidences of the potential future non-invasive lactate detection as a possible biomarker of HER2-addiction and T-responsiveness. Supported by the Italian Ministry of Health and AIRC.

PIK3CA mutations in HER2-positive Breast Cancer Patients; Frequency and Clinicopathological Perspective in Egyptian Patients

Missense mutations in PIK3CA are common in breast cancers. They mostly involve exons 9 and 20 which encode kinase and helical domains of the protein and may result in its activation. PIK3CA activating mutations were previously shown to predict lower pathologic complete response (pCR) in HER2-positive breast cancer cases undergoing neoadjuvant human epidermal growth factor receptor 2-targeting therapy. Hence, the present work was conducted to estimate the mutation frequency in PIK3CA in 51 HER2-positive patients by direct sequencing. Our results showed 8 out of 51 (15.7%) to harbor PIK3CA mutations in either exon 9 or 20, or both. Three patients had mutations in both exons 9 and 20. Seven (13.7%) possess missense mutations in exon 20 which changed the amino acid sequence of the protein (H1047R, M1040I, and G1049G). Only four cases harbored mutations in exon 9, changing the codon sequences (E545K E545A, and R524K). Taking the clinicopathological data to account, the mutation frequency was greater in ductal than lobular carcinomas, in grade II rather than III and in lymph node positive lesions, with a higher HER2 score and which are ER/PR negative. However, none of the correlations proved statistically significant. In conclusion, to the best of our knowledge, the PIK3CA mutation frequency in this study is the first report regarding HER2-positive breast cancer patients in Egypt. Hereby, we highlight a moderate frequency which could be useful in the future as a predictive marker for anti-HER2 therapy.