Human Epidermal Growth Factor Receptor-2 Immunohistochemistry Research Articles

Comparing core needle biopsy and surgical excision in breast cancer diagnosis: implications for clinical practice from a retrospective cohort study.

Preoperative ultrasound-guided core needle biopsy (CNB) is currently the standard procedure for managing breast illnesses. However, the differences in outcomes between CNB and surgical excision (SE) have not been thoroughly assessed. This study aimed to explore the disparities in pathological outcomes between these two procedures, using a large sample dataset. This retrospective study consecutively included patients who underwent CNB and SE at Shenzhen People's Hospital from May 2016 to June 2023. Immunohistochemistry (IHC) was utilized to determine the status of estrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor receptor-2 (HER2), and Ki-67. Patients presenting with HER2 IHC 2+ underwent additional fluorescence in situ hybridization (FISH) examination. The cutoff value for high Ki-67 expression was established at 14%. Molecular subtypes were classified into four groups (Luminal A, Luminal B, Triple-negative, and HER2-positive) and five groups [Luminal A, Luminal B+ (HER2-positive), Luminal B- (HER2-negative), Triple-negative, and HER2-positive], based on different criteria. A total of 4,209 patients were included in this study. Post-surgical confirmation revealed 2,410 cases as benign and 1,799 as malignant. Among the malignant cases, 334 were excluded due to either not having undergone direct surgery or having incomplete IHC results. The remaining 1,465 cases underwent IHC testing. CNB demonstrated a 97% concordance rate (CR) in diagnosing benign cases. The CRs for diagnosing invasive breast cancer (IBC) and carcinoma in situ (CIS) were 92% and 54%, respectively. ER, PgR, HER2, and Ki-67 exhibited CRs of 94%, 91%, 98%, and 84%, respectively. In the four-group classification, the overall diagnostic CR was 82%, with CRs for Luminal A, Luminal B, HER2-positive, and triple-negative breast cancer (TNBC) being 84%, 82%, 78%, and 85%, respectively. Under the five-group classification, the overall diagnostic CR was also 82%, with CRs for Luminal A, Luminal B+, Luminal B-, HER2-positive, and TNBC being 86%, 85%, 94%, 88%, and 92%, respectively. This study demonstrates that CNB is highly accurate in differentiating benign from malignant breast lesions, particularly showing significant consistency in the diagnosis of molecular subtypes, providing a reliable reference for clinical diagnosis.

Evidence for Unified Assessment Criteria of HER2 Immunohistochemistry in Colorectal Carcinoma

Human epidermal growth factor receptor-2 (HER2) expression is an important biomarker for the management of RAS wild-type metastatic colorectal carcinoma (CRC). Immunohistochemistry (IHC) with reflex in situ hybridization (ISH) is accepted as a standard method of assessment, yet there are currently the following 2 sets of criteria used to interpret results: the HER2 Amplification for Colorectal Cancer Enhanced Stratification criteria and the My Pathway criteria. The HER2 Amplification for Colorectal Cancer Enhanced Stratification criteria require ISH confirmation when IHC staining is 3+ in 10% to 49% of cells, whereas the My Pathway criteria mirror those for gastric HER2 assessment and do not recommend ISH confirmation in the previously referenced scenario. We aimed to assess the prevalence of HER2 3+ heterogeneity and its association with ERBB2 copy number amplification to evaluate the necessity of ISH testing when IHC staining is 3+ in <50% of cells. Next-generation sequencing of DNA (592-gene panel or whole exome sequencing) was performed for 13,208 CRC tumors submitted to Caris Life Sciences. HER2 (4B5) expression was tested using IHC. A subset of tumors was tested for ERBB2 amplification via chromogenic ISH and/or via next-generation sequencing (copy number amplification). χ2 tests or Fisher exact tests were applied where appropriate, with P values adjusted for multiple comparisons (P < .05). Of 13,208 CRCs with HER2 IHC, 87.4% (11,541/13,208) were negative for HER2 expression (≤3+ intensity and <10% tumor-cell staining) and 11.2% (1473/13,208) demonstrated at least low HER2 expression (1 to 2+ and ≥10%). Only 1.5% (194/13,208) of all tested tumors were either positive or heterogeneously positive for HER2 overexpression (3+ and ≥10%). Of these, 14% (28/194) had heterogenous HER2 overexpression (3+ staining of 10%-49% of cells). Among 22 HER2-positive/heterogenous cases with successful ISH testing, 100% (22/22) demonstrated amplification via ISH. Because the classification of tumors as HER2-positive/heterogenous using IHC correlated very closely with ISH positivity, our results suggest that ISH is likely unnecessary for CRCs with 3+ HER2 overexpression in 10% to 49% of neoplastic cells.

Evaluation of HER2 immunohistochemistry expression in non-standard solid tumors from a Single-Institution Prospective Cohort.

Human epidermal growth factor receptor-2 (HER2) is a well-established prognostic and predictive biomarker. It is an FDA-approved therapeutic target for HER2 positive breast, gastroesophageal, and more recently, lung and colon cancers. It is an emerging biomarker in biliary tract, bladder, cervical, endometrial, ovarian, and pancreatic cancers. The emergence of new indications warrants further characterization of HER2 expression in diverse cancer populations. This study investigated HER2 expression in solid tumour samples and the feasibility of obtaining these results. Prospective consent was obtained at a Canadian tertiary academic cancer center from adult oncology patients who were referred for molecular genetic testing of malignant tissue samples. Standard HER2-targeted malignancies were considered breast and gastroesophageal, and were excluded from this study. Between July 2020 and November 2023, 499 samples of solid tumors underwent immunohistochemistry (IHC) HER2 staining. A median turnaround time (TAT) of 14 days would be considered feasible for clinical decision making. The mean age (± SD) of participants was 67 ± 12.5 years, with 270 (54%) male and 229 (46%) female. HER2 protein expression was measured in 42 unique cancer types. IHC levels of 0, 1+, 2+, and 3+ were reported and were 43%, 12%, 35%, and 10% of all analyzable samples respectively (tissue inadequate in 3% of samples). The median TAT for HER2 expression results from time of request to result in release was 18 (interquartile range, 11 to 30) days. HER2 protein expression varies widely between different cancer types. TAT for HER2 IHC results was a median of 18 days, which is close to our feasibility cut-off.

In ER-Positive, HER2-Negative Breast Cancers, HER2 mRNA Levels Correlate Better with Clinicopathologic Features and Oncotype DX Recurrence Score than HER2 Immunohistochemistry

With the approval of trastuzumab deruxtecan for treating advanced human epidermal growth factor receptor-2 (HER2) low breast cancer (BC), it has become increasingly important to develop more accurate and reliable methods to identify HER2-low BC. In addition, HER2 immunohistochemistry (IHC) has limitations for quantification of HER2. We explored the relationship between HER2 IHC and mRNA levels and evaluated whether HER2 IHC scores and mRNA levels are associated with clinicopathologic features and Oncotype DX Recurrence Score (RS) in estrogen receptor (ER)-positive, HER2-negative BCs. A total of 750 BCs sent for Oncotype DX (ODX) testing were included in this study, and 559 with HER2 mRNA levels were available. There were no statistically significant differences between HER2 0 and HER2-low BC in clinicopathologic variables or ODX RS using HER2 IHC. There was a significant difference in median HER2 mRNA values between HER2 0 and HER2-low (8.7 vs 9.3, P < .001); however, the HER2 mRNA distribution had substantial overlap between these 2 groups with a suboptimal area under the receiver operating characteristic curve (area under the receiver operating characteristic curve = 0.68). A HER2 mRNA value of 9.2 was generated as the optimal cutoff for distinguishing HER2 0 and HER2-low BC. Comparing ER+ BCs with HER2 mRNA high (>9.2) and low (≤9.2) revealed a statistically significant difference in most clinicopathologic variables and ODX RS. From this large cohort of ER-positive, HER2-negative BC, our results demonstrated that HER2 mRNA levels correlated better with clinicopathologic features and recurrence risk as assessed by ODX RS than HER2 IHC scores. Our findings suggest that HER2 mRNA-detecting methods could potentially serve as a quantitative and reliable method for identifying a biologically meaningful group of HER2-low BC. Further study is needed to determine whether HER2 mRNA levels could be more reliable than IHC for identifying which patients will be most likely to benefit from trastuzumab deruxtecan.

Decreased HER2 expression in residual disease following neoadjuvant therapy in patients with HER2-positive breast cancer.

e12621 Background: Human epidermal growth factor receptor-2 (HER2) overexpression is a defining feature of roughly 20% of localized breast cancer and represents a critical target for therapy. Since the demonstration that residual disease (RD) after neo adjuvant therapy (NAT) is associated with worse prognosis and that adjuvant ado trastuzumab emtansine (tDM1) improves survival, NAT has become the standard of care for localized HER2+ breast cancer. Retesting for HER2 overexpression post resection is variable, and data is conflicting regarding the prognostic significance of changes in HER2 expression pre and post therapy. The objective of this study was to evaluate the association of pre and post neo adjuvant therapy HER2 immunohistochemistry (IHC) expression on breast cancer outcomes in our institutional database. Methods: After IRB approval, data was gathered for patients with localized HER2+ breast cancer receiving NAT including trastuzumab/pertuzumab at Yale Cancer Center between 2012 and 2022. Pathologic complete response (pCR) was defined as no residual invasive tumor in breast and lymph nodes. Patients were divided into 3 cohorts by response and HER2 IHC: Cohort 1 pCR Cohort 2 pre-treatment 3+/post treatment 1-2+, and Cohort 3 pre-treatment 3+/post treatment 3+. A Kaplan-Meier survival analysis was done to assess recurrence free survival at 36 months. Results: Within the specified time interval, we identified 104 patients with localized HER2-IHC 3+ breast cancer who received neoadjuvant therapy. The pCR rate was 62.5% (65/104), while 37.5% (39/104) of patients had RD. Among patients with RD, 58.9% (23/39) remained HER2 IHC 3+ and 41% (16/39) had decreased HER2 expression IHC1+/IHC 2+. Median follow-up was 27.9 months at time of analysis. In patients with HER2 3+ RD 26% (6/23) developed local recurrence or distant metastasis while none of patients with HER2 IHC 1+ or 2+ RD had relapse ( p= 0.0309). In patients with pCR, 6.15% (4/65) had recurrence. Kaplan-Meier survival analysis showed a significant difference between the 3 groups (log rank p= 0.004). Conclusions: In our retrospective cohort, decreased HER2 expression by IHC following neoadjuvant treatment was associated with lower recurrence rates. If confirmed, RD HER2 IHC expression could be used as a prognostic biomarker to select patients for more or less aggressive adjuvant therapy, stratify patients in adjuvant trials, and identify patients who may benefit from more intensive post therapy surveillance.

MOUNTAINEER-03: Phase 3 study of tucatinib, trastuzumab, and modified FOLFOX6 as first line treatment in HER2+ metastatic colorectal cancer.

TPS3631 Background: The current standard of care (SOC) for the treatment of metastatic colorectal cancer (mCRC) is multi-agent chemotherapy, with or without a VEGF or EGFR inhibitor. Human epidermal growth factor receptor-2 (HER2) is a validated clinical target in breast and gastric cancers. HER2 amplification occurs in 3%–5% of patients with mCRC; the rate of HER2 amplification can increase to approximately 10% in patients with RAS/BRAF wild-type mCRC tumors. Tucatinib (TUC)—a highly selective, HER2-directed tyrosine kinase inhibitor—is approved in multiple regions for HER2-positive (HER2+) metastatic breast cancer, approved in the US for HER2+ metastatic colorectal cancer, and under investigation in gastrointestinal cancers. MOUNTAINEER (NCT03043313) evaluated the safety and efficacy of TUC and trastuzumab (Tras) in patients with treatment-refractory RAS wild-type, HER2+ mCRC. Results from the primary endpoint analysis showed clinically meaningful activity, with a confirmed objective response rate (ORR) per blinded independent central review (BICR) of 38.1% (95% confidence interval [CI] 27.7, 49.3) and median duration of response per BICR of 12.4 months (95% CI 8.5, 20.5). Results also demonstrated TUC + Tras was well tolerated, with a low discontinuation rate (5.8%) and no deaths due to adverse events. MOUNTAINEER-03 will further investigate TUC in combination with modified FOLFOX (mFOLFOX) and Tras in patients with RAS wild-type HER2+ mCRC. Methods: MOUNTAINEER-03 (NCT05253651) is a global, open-label, randomized, phase III study for first-line treatment of HER2+ and RAS wild-type mCRC. Approximately 400 patients will be randomized 1:1 to the TUC experimental arm (TUC [300 mg orally twice daily] + Tras + mFOLFOX) or the SOC arm (mFOLFOX alone or in combination with either bevacizumab or cetuximab). HER2 status is determined centrally with tissue-based HER2 immunohistochemistry and in situ hybridization assays. Eligible patients must not have received prior treatment in the metastatic setting but may have received adjuvant treatment if completed &gt; 6 months prior to enrollment. Patients must be ≥18 years old with an Eastern Cooperative Oncology Group Performance Status of ≤1 and RAS wild-type mCRC. Patients with treated stable central nervous system metastases are eligible. Randomization is stratified by primary tumor location (left-sided vs other) and liver metastases (presence/absence). The primary endpoint is progression-free survival per RECIST v1.1 assessed by BICR. Key secondary endpoints are overall survival and confirmed ORR per RECIST v1.1 assessed by BICR. Enrollment is ongoing in North America, Asia, Australia, and Europe. Clinical trial information: NCT05253651 .

Development of an electrochemical biosensor for the detection of mammary gland carcinoma using molybdenum enhanced poly taurine nano-biofilms confirmed pathological findings

BackgroundDeveloping high-performance sensing frameworks for diagnosing anaplastic changes is the subject of debate. The lack of on-time diagnosis in patients with suspicious cancers can affect the prognosis and survival rate. As a correlate, the emergence of de novo strategies for developing transducing frameworks has an inevitable role in advanced biosensing. The combination of green chemistry procedures with eco-friendly and biocompatible materials is of high desirability in this context. The synthesis of new biocompatible and cost-effective nanomaterials to meet the emerging needs of rising demands appeals to new synthetic methodologies.MethodsHere, we applied the electrochemical synthesis method to the fabrication of biocompatible and subtly governed Molybdenum trioxide/poly taurine nano-bio films to monitor human epidermal growth factor receptor-2 (HER-2) in sera from breast cancer patients. Morphological and elemental assessments were performed using a scanning electron microscope, energy-dispersive X-Ray spectroscopy, and dot mapping analyses. In addition, HER-2 immunohistochemistry (IHC) staining was performed on tissue samples, and data were compared to the values obtained by Molybdenum trioxide/poly taurine nano-bio films.ResultsWe also noted our platform is eligible for feasible, rapid, and specific determination of HER-2 factor in human samples. The method had a lower limit of quantification of 0.000001 ng/mL and a linear dynamic range between 0.1 ng/mL and 0.000001 ng/mL. IHC imaging showed that the degree of anaplastic changes in breast samples (intensity of HER-2 factor) was closely associated with the intensity of signals obtained by our developed immunosensor.ConclusionsAccording to the obtained desirable coordination with pathological studies, the designed biosensor has excellent capability to use as a reliable diagnostic tool in clinical laboratories.Graphical

Abstract 967: Real-world transcriptomic biomarkers as replacement for immunohistochemistry and FISH studies in breast cancer

Abstract Background: Human epidermal growth factor receptor-2 (HER2) and hormone receptors are typically used as binary biomarkers for selecting breast cancer therapy. There is a need to explore the clinical relevance of these biomarkers as continuous variables. This is particularly relevant for the new class of antibody-drug conjugates (ADC), in which a relatively low HER2 expression level is adequate for targeting tumor cells. We explored the potential of RNA profiling, determined by next generation sequencing (NGS), to provide more flexible clinical biomarkers as compared with immunohistochemistry (IHC) or fluorescent in situ hybridization (FISH). Methods: Clinical and laboratory data from 57 breast cancers collected by the COTA real-world data company were used to study biomarker levels as detected by routine clinical transcriptomic tests. HER2 (ERBB2), estrogen receptor alpha (ESR1), and androgen receptor (AR) mRNA levels were compared with reported HER2 and estrogen receptor (ER) IHC and FISH results. Results: RNA levels accurately reflected and predicted HER2 amplification (see table below). Importantly, RNA data showed significant variation and overlap in the levels of ERBB2 mRNA between cases scored by IHC as zero, 1+, and 2+. This variation correlated with progression-free survival (PFS). Similarly, the ESR1 RNA levels accurately reflected ER status and demonstrated significant variation between positive cases. RNA data also showed significant variations in the AR levels. Patients wssith high AR mRNA levels had significantly better PFS (P=0.05). Patients expressing high ER and AR levels had significantly better PFS than those expressing low ESR1 and AR levels (P=0.03). Conclusions: These findings suggest that RNA analysis using NGS is an alternative to IHC and FISH. RNA provides continuous data that can determine cut-off points predicting response to therapy and should be explored in predicting ADC response. ERBB2 mRNA levels (FPKM) in various HER2 IHC groupss IHC Score Valid N Mean Median Minimum Maximum Quartile Range Std.Dev. Zero 19 231 243 63 537 170 110 Zero vs one 3 151 155 45 253 208 104 Zero to one vs one 18 397 302 172 845 365 222 One Vs two 13 495 423 159 1094 273 284 Two vs three 4 7523 7649 937 13859 7183 5310 Citation Format: Maher Albitar, Andre Goy, Andrew Pecora, Deena Graham, Donna Donna McNamara, Ahmad Ahmad Charifa, Andrew IP, Wanlong Ma, Stanley Waintraub. Real-world transcriptomic biomarkers as replacement for immunohistochemistry and FISH studies in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 967.

Comparison of breast cancer HER-2 receptor testing with immunohistochemistry and in situ hybridization.

Human epidermal growth factor receptor-2 (HER2) status can be tested with immunohistochemistry (IHC) and in situ hybridization (ISH). The 2018 American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) HER2 testing guidelines suggest initial HER2 testing using IHC and further testing IHC equivocal cases with ISH. However, many institutions perform both IHC and ISH on the same specimen. This study aims to analyze the concordance between HER2 IHC and ISH in order to evaluate the benefit of repeating HER2 testing on the same breast cancer specimens. Patients diagnosed with invasive breast cancer through BreastScreen NSW Sydney West program between January 2018 and December 2020 were identified and their HER2 IHC and HER2 ISH results on core needle biopsy (CNB) and surgical excisions (SE) were retrospectively collected. Specimens with both IHC and ISH results were then analyzed for agreement and concordance using unweighted kappa values. Equivocal IHC (2+) cases were excluded from concordance analysis. Overall, there were 240 invasive breast cancer specimens (CNB and SE) with both IHC and ISH recorded. Concordance between HER2 IHC and ISH was 100% (95% CI: 96.2-100%; κ=1.00 (P<0.001)). Of the IHC equivocal cases (n=146), 94.5% were ISH negative. There was perfect positive concordance and agreement between non-equivocal IHC and ISH results. This reinforces that IHC alone can be utilized reliably for testing HER2 status of non-equivocal cases consistent with the 2018 ASCO/CAP guidelines.

A multicenter study on efficacy of dual-target neoadjuvant therapy for HER2-positive breast cancer and a consistent analysis of efficacy evaluation of neoadjuvant therapy by Miller-Payne and RCB pathological evaluation systems (CSBrS-026).

The aim of this study was to investigate the factors influencing pathological complete response (pCR) rate in early breast cancer patients receiving neoadjuvant dual-target [trastuzumab (H) + pertuzumab (P)] therapy combined with chemotherapy. Additionally, the consistency of the Miller-Payne and residual cancer burden (RCB) systems in evaluating the efficacy of neoadjuvant therapy for early human epidermal growth factor receptor-2 (HER2)+ breast cancer was analyzed. The clinicopathological data of female patients with early-stage HER2+ breast cancer who received dual-target neoadjuvant therapy at 26 hospitals of the Chinese Society of Breast Surgery (CSBrS) from March 2019 to December 2021 were collected. Patients were allocated to four groups: the HER2 immunohistochemistry (IHC) 3+/hormone receptor (HR)-, IHC3+/HR+, IHC2+ in situ hybridization (ISH)+/HR- and IHC2+ ISH+/HR+ groups. The overall pCR rate for patients, the pCR rate in each group and the factors affecting the pCR rate were analyzed. The consistency between the Miller-Payne and RCB systems in assessing the efficacy of neoadjuvant therapy was analyzed. From March 1, 2019, to December 31, 2021, 77,376 female patients with early-stage breast cancer were treated at 26 hospitals; 18,853 (24.4%) of these patients were HER2+. After exclusion of unqualified patients, 2,395 patients who received neoadjuvant dual-target (H+P) therapy combined with chemotherapy were included in this study. The overall pCR rate was 53.0%, and the patients' HR statuses and different HER2+ statuses were significantly correlated with the pCR rate (P<0.05). The consistency of the pathological efficacy assessed by the Miller-Payne and RCB systems was 88.0% (κ=0.717, P<0.001). Different HER2 expression statuses and HR expression statuses are correlated with the pCR rate after dual-target neoadjuvant therapy in HER2+ breast cancer patients. There is a relatively good consistency between Miller-Payne and RCB systems in evaluating the pathologic efficacy of neoadjuvant therapy for HER2+ breast cancer.

Clinicopathologic significance of human epidermal growth factor receptor 2 expression and gene amplification in gastric carcinoma.

This study is aimed at determining the human epidermal growth factor receptor-2 (HER-2) gene status in gastric cancers using immunohistochemistry (IHC) and silver DNA in situ hybridization (SISH) technique and investigating the relationship between HER-2 status and clinicopathological variables. We examined 104 gastric carcinoma cases with gastrectomy specimens. The age, sex, histopathological tumor type, tumor differentiation, tumor localization, tumor size, invasion depth, lymph node metastasis status, HER-2 IHC evaluation results, and SISH evaluation results of the cases were recorded. In the present study, the SISH-confirmed HER-2 positivity rate (SISH amplification) is 14.4%. A statistically significant relationship was found between HER-2 status and tumor invasion depth (P = 0.03). It was observed that as the depth of invasion increased, HER-2 positivity decreased. No statistically significant relationship was found between HER-2 status and sex, age, tumor size, differentiation, histopathological classification, lymph node metastasis, and tumor localization (P > 0.05). The rate of HER-2 2+ cases was found to be high. HER-2 status is negatively correlated with the depth of invasion in gastric cancers, and HER-2 positivity increases as the depth of invasion decreases. HER-2 may be early molecular evidence in oncogenesis. Immunohistochemically, HER-2 2+ cases should be confirmed by the in situ hybridization (ISH) technique.

The Exciting New Field of HER2-Low Breast Cancer Treatment.

Simple SummaryBreast cancer can express, at varied levels, a protein named HER2, commonly responsible for making it grow and send distant metastases. In the past, patients affected by the so called HER2-positive breast cancer had lower probabilities of cure and survival, though with the advent of drugs that target HER2, three decades ago, their prognosis has greatly improved. So far, only patients with strong HER2 expression on their tumour can be treated with these benefitial drugs, like trastuzumab, though recently stronger drugs have also been shown capable of eliminating breast cancer cells with lower levels of HER2 expression (HER2-low). Sooner or later, these new drugs, like trastuzumab-deruxtecan, may be available for treating such patients. Therefore, the aim of this narrative review of the literature is to provide an outline of what is going on on this specific field of research, and what could be expected in the future in the clinic. Since human epidermal growth factor receptor-2 (HER2) characterization, going through clinical research and regulatory approval of HER2-targeted therapies, much has elapsed and is still unfolding. Hitherto, only breast cancer (BC) patients with HER2 immunohistochemistry 3+ or with HER2 gene fluorescence in-situ hybridization (FISH) amplification (a.k.a., HER2-positive BC) have benefited from anti-HER2 agents. In recent years, however, much of the research effort has been expanded, with positive outcomes being reached for formerly known HER2-negative BC that yet express HER2 to some degree (HER2 immunohistochemistry 1+ or 2+, but FISH negative) and are currently being classified as HER2-low BC for the purpose of trial enrollment. In this sense, our aim is to review the body of evidence of HER2-low BC that led to the study of first-generation anti-HER2 agents, like trastuzumab, and how they have failed to achieve any clinical applicability in this setting. In addition, we review new data that is leading to the growing success of the new generation of drugs, especially the promising HER2-directed antibody–drug conjugates. A narrative review is also performed regarding the rationale behind the consolidated and ongoing clinical trials studying anti-HER2 agents in combination with unrelated agents, such as immunotherapy, endocrine therapy, and CDK4/6 inhibitors. Hopefully, all this ongoing research effort will be able to extend the survival benefits seen with anti-HER2 agents in HER2-positive disease, at least to some degree, to the greater proportion of patients with HER2-low BC.

Predictors of pathological complete response to neoadjuvant treatment and changes to post-neoadjuvant HER2 status in HER2-positive invasive breast cancer

The response of human epidermal growth factor receptor2 (HER2)- positive breast cancer (BC) patients to anti-HER2 targeted therapy is significant. However, the response is not uniform and a proportion of HER2-positive patients do not respond. This study aims to identify predictors of response in the neoadjuvant treatment and to assess the discordance rate of HER2 status between pre- and post-treatment specimens in HER2-positive BC patients. The study group comprised 500 BC patients treated with neoadjuvant chemotherapy (NACT) and/or neoadjuvant anti-HER2 therapy and surgery who had tumours that were 3+ or 2+ with HER2 immunohistochemistry (IHC). HER2 IHC 2+ tumours were classified into five groups by fluorescence in situ hybridisation (FISH) according to the 2018 ASCO/CAP guidelines of which Groups 1, 2 and 3 were considered HER2 amplified. Pathological complete response (pCR) was more frequent in HER2 IHC 3+ tumours than in HER2 IHC 2+/HER2 amplified tumours, when either in receipt of NACT alone (38% versus 13%; p = 0.22) or neoadjuvant anti-HER2 therapy (52% versus 20%; p < 0.001). Multivariate logistic regression analysis showed that HER2 IHC 3+ and histological grade 3 were independent predictors of pCR following neoadjuvant anti-HER2 therapy. In the HER2 IHC 2+/HER2 amplified tumours or ASCO/CAP FISH Group 1 alone, ER-negativity was an independent predictor of pCR following NACT and/or neoadjuvant anti-HER2 therapy. In the current study, 22% of HER2-positive tumours became HER2-negative by IHC and FISH following neoadjuvant treatment, the majority (74%) HER2 IHC 2+/HER2 amplified tumours. Repeat HER2 testing after neoadjuvant treatment should therefore be considered.

Differential prognostic value of positiveHER2 status determined by immunohistochemistry or fluorescence in situ hybridization in breast cancer.

Human epidermal growth factor-receptor-2 (HER2) is a membrane-tyrosine-kinase that is amplified/overexpressed up to 20% in breast cancer. HER2 positive status is associated with faster disease progression, higher metastatic potential, and shorter disease-free/overall survival and also has emerged as an important therapeutic target in breast cancer. HER2 status can be determined by in-situ-hybridization (ISH) or immunohistochemistry (IHC). Although the concordance rate between ISH and IHC is well-known, the prognostic power of both technologies if tested in parallel on the same tumor has not been studied extensively. In this study we retrospectively analyzed a large HER2 positive breast cancer cohort tested both with fluorescence labeled ISH (FISH) and IHC in parallel on each case. We stratified HER2 positive results by FISH and IHC with long-term overall survival, 5-year survival and metastases/recurrence rates. Positive HER2 status both FISH and IHC was available in 364 patients. The number of HER2 FISH-positive and FISH-negative patients was 342 and 22, respectively. The number of HER2 IHC 0/1 + , IHC 2 + , and IHC 3 + patients was 12, 42, and 310, respectively. Among the patients with IHC 3 + status, 288 were FISH-positive and 22 FISH-negative. HER2 status determined by FISH correlated with clinical outcomes (overall survival and with metastases/recurrence, p = 0.036, p = 0.039), whereas HER2 status determined by IHC did not. Our results indicate that prognostic information in HER2 positive breast cancer also depends on the methodology of how positivity was determined. In our cohort, FISH was superior to IHC based positive HER2 status.

Abstract P4-07-10: Gene expression profiling in immunophenotypic triple negative breast carcinomas harboring HER-2 amplification identifies tumors with distinct molecular signatures and increased ERBB2 gene expression

Abstract Introduction: Breast carcinomas can be classified by hormone receptors and human epidermal growth factor receptor-2 (HER-2) status. HER-2 status is assessed using immunohistochemistry (IHC) and/or fluorescent in situ hybridization (FISH). Immunophenotypic triple negative breast cancers (iTNBC) may harbor an amplification of HER-2 detected by FISH (iTNBC-FISHAmp) or may be negative by FISH (iTNBC-FISHNeg). The discrepancy between protein expression and gene amplification in these tumors poses relevant questions on tumor biology and for treatment implications. Here we investigate iTNBC-FISHAmp and iTNBC-FISHNeg by gene expression profile. Methods: A total of 40 iTNBC were selected. HER-2 IHC scores (0 or 1+) were annotated. All the tumors were tested by FISH showing 20 iTNBC-FISHAmp and 20 iTNBC-FISHNeg. The tumor morphology was reviewed by 2 pathologists, and stromal tumor infiltrating lymphocytes (sTILs) were estimated as high (H-sTILs) or low (L-sTILs). The areas of tumor with best cellularity were selected for RNA extraction. Gene expression profiling using a panel of 776 genes across 33 biological signatures was performed using Nanostring technology. Results: ERBB2 gene expression was significantly higher in iTNBC-FISHAmp when compared to iTNBC-FISHNeg tumors (p&amp;lt;0.001). ERBB2 gene expression was significantly higher in tumors with IHC 1+ when compared to tumors with IHC 0 (p&amp;lt;0.001). Genes related to the biologic stromal signature showed a lower expression in iTNBC-FISHAmp when compared with iTNBC-FISHNeg (p=0.015). All tumors were classified as basal-like molecular subtype. The histologic presence of sTILs had no correlation with ERBB2 gene expression. Tumors with H-sTILs significantly correlated with the multiple biological signatures related to inflammation and immunoresponse, including PDL1, PD1, TIGIT, CD8, Cytotoxic cells, TREG (regulatory T cell), TIS (tumor inflammatory signature); while tumors with L-sTILs significantly correlated with B7-H3, stromal, AR, and claudin-low signatures. Conclusions: Our results demonstrate that iTNBC tumors are a heterogeneous entity at the molecular level. In iTNBC-FISHAmp, ERBB2 gene is significantly up-regulated despite low HER-2 protein expression. Tumors with HER-2 IHC 1+ are associated with higher gene expression than tumors with IHC 0. iTNBC-FISHAmp show a lower expression of genes related to biologic stoma signature with possible implications on biology of tumor microenvironment. The histological assessment of sTILs in iTNBC correlates with multiple gene expression signatures that are closely related to tumor immunogenicity and sensitivity to immunotherapy. Further studies are needed to establish the functional role of HER-2 signaling in these tumors. Citation Format: Paolo Cotzia, Theodore Vougiouklakis, Ursula Andreo, George Jour, Christopher Schwartz, Maryann Kwa, Sylvia Adams, Francisco Esteva, Deborah Axelrod, Freya Schnabel, Matija Snuderl, Farbod Darvishian. Gene expression profiling in immunophenotypic triple negative breast carcinomas harboring HER-2 amplification identifies tumors with distinct molecular signatures and increased ERBB2 gene expression [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-07-10.

HER2, chromosome 17 polysomy and DNA ploidy status in breast cancer; a translational study

Breast cancer treatment depends on human epidermal growth factor receptor-2 (HER2) status, which is often determined using dual probe fluorescence in situ hybridisation (FISH). Hereby, also loss and gain of the centromere of chromosome 17 (CEP17) can be observed (HER2 is located on chromosome 17). CEP17 gain can lead to difficulty in interpretation of HER2 status, since this might represent true polysomy. With this study we investigated whether isolated polysomy is present and how this effects HER2 status in six breast cancer cell lines and 97 breast cancer cases, using HER2 FISH and immunohistochemistry, DNA ploidy assessment and multiplex ligation dependent probe amplification. We observed no isolated polysomy of chromosome 17 in any cell line. However, FISH analysis did show CEP17 gain in five of six cell lines, which reflected gains of the whole chromosome in metaphase spreads and aneuploidy with gain of multiple chromosomes in all these cases. In patients’ samples, gain of CEP17 indeed correlated with aneuploidy of the tumour (91.1%; p < 0.001). Our results indicate that CEP17 gain is not due to isolated polysomy, but rather due to widespread aneuploidy with gain of multiple chromosomes. As aneuploidy is associated with poor clinical outcome, irrespective of tumour grade, this could improve future therapeutic decision making.

The Impact of Partial Weak Staining in Normal Breast Epithelium on the Reliability of Immunohistochemistry Results in HercepTest-positive Breast Cancer

IntroductionAlthough normal epithelial cells do not show human epidermal growth factor receptor-2 (HER2) gene amplification and should lack membrane staining by HER2 immunohistochemistry (IHC), HER2 staining in benign breast epithelium is occasionally encountered. The significance of this occurrence has not yet been adequately studied, and its associated American Society of Clinical Oncology/College of American Pathologists recommendations are vague. Our objective is to assess the correlation between HER2 IHC 3+ breast cancer cases with normal epithelium staining (NES) and their corresponding fluorescence in situ hybridization (FISH) results, and to suggest recommendations for interpretation. Materials and MethodsA total of 154 breast cancer cases with HER2 IHC 3+ were reviewed. NES, along with other clinicopathologic characteristics, were recorded. NES was scored as present or absent. All study cases were sent for FISH testing. All cases, and particularly those that showed false positivity for IHC (positive IHC, negative FISH) were examined for NES. ResultsOf the 154 cases, 146 cases were FISH-positive (94.8%) and 2 failed FISH testing (1.3%). Conversely, 22% (34/154) of the cases showed NES for HER2. Of these 34 cases, 23 (67%) were FISH-amplified, 9 (26%) were FISH not amplified, and 2 failed FISH testing. Notably, all of the false-positive (FISH-negative) breast cancer cases showed some degree of positivity in normal breast epithelium. ConclusionsOur findings, though descriptive, show a very strong association between NES and false-positive HER2 IHC. This confirms the need to carefully evaluate IHC-positive breast cancers for NES, and to have a low threshold for confirmatory testing by FISH.

Abstract P1-03-02: ASCO/CAP human epidermal growth factor receptor-2 (HER2) in situ hybridization (ISH) categories evaluated by quantitative HER2 protein diagnostic methodologies: A comparative analysis

Abstract Background: In 2013, the ASCO/CAP consensus panel published updated guidelines for HER2 testing in breast cancer that modified the definition of HER2 amplification by in situ hybridization (ISH), creating five new prognostic categories (group 1: classic amplified, group 2: monosomy, group 3: co-amplified (polysomy), group 4: equivocal, and group 5: classic non-amplified). Patients determined to be ISH amplified, were considered eligible for HER2-directed therapy. Concern over whether patients from non-classic groups 2-4 would benefit from treatment has led to the recent publication of the 2018 HER2 focused update. This update has modified the criteria for interpreting these ISH categories, recommending that the final diagnosis take into consideration a combination of HER2 immunohistochemistry (IHC) and ISH results. With increased emphasis on the HER2 protein assessment, it has prompted us to quantitatively examine HER2 protein expression in the ISH categories, using two different novel technologies. Materials &amp; Methods: A cohort of 170 cases (URMC) and 102 cases (PSHMC) of invasive breast cancers, which had previously undergone HER2 IHC and ISH testing, were selected for this study. Cases were sorted and categorized into the HER2 ISH categories defined by ASCO/CAP. HER2 protein expression was quantitatively measured in the URMC and PSHMC cohorts using a novel immunodetection methodology (streptavidin-coated Phosphor-Integrated Dot (PID) fluorescent nanoparticles), and a novel dual-antibody, proximity-binding immunoassay (HERmark® Breast Cancer Assay, Monogram Biosciences, South San Francisco, California), respectively. HER2 protein expression was compared to the HER2 FISH and IHC results by ASCO/CAP category. Results: Cases in group 1 had a significantly (p &amp;lt; 0.01) higher average PID/cell and HERmark compared to cases in groups 2-5 (Table 1). Cases in groups 2-4 showed lower quantitative levels of HER2 protein expression, similar to the classic non-amplified cases (group 5). Group 1 was further divided into three subgroups (Table 2): Group A - ISH high-level amplified (ratio &amp;gt; 2, HER2 &amp;gt; 6, CEP17 &amp;lt; 2.7), Group B - amplified with elevated CEP17 (ratio &amp;gt; 2, CEP17 &amp;gt; 2.7), and Group C - low-level amplified (ratio &amp;gt; 2, HER2 &amp;gt; 4 and &amp;lt; 6). Group A and B had a significantly (p &amp;lt; 0.01) higher average PID/cell and HERmark compared to Group C. Group C was more comparable to cases in groups 2-5 (Table 1). Conclusion: Our results suggest that quantitative assessment of HER2 protein expression may help to further classify cases for HER2 status for targeted therapy, supporting the 2018 ASCO/CAP recommendation that non-classic ISH results might be resolved by evaluating protein expression. Follow up studies with a larger patient cohort and dual quantitative assessment are warranted. Average PID/cell and HERmark in ASCO category groupsASCO category groupN (URMC)PID/cell (URMC)*N (PSHMC)HERmark (PSHMC)*18888.07761.521011.20N/A32016.0213.84238.5315.95296.3208.3*averageTable 2:Average PID/cell and HERmark in subgroups of Group 1SubgroupN (URMC)PID/cell (URMC)*N (PSHMC)HERmark (PSHMC)*A24157.66465.7B34101.61044.1C3016.9329.8*average Citation Format: Buscaglia B, Turner B, Goda H, Huang W, Leitzel K, Natori T, Nakano Y, Okada H, Sperinde J, Ali S, Vasekar M, D'Aguiar M, McMahon L, Henry J, Lipton A, Hicks D. ASCO/CAP human epidermal growth factor receptor-2 (HER2) in situ hybridization (ISH) categories evaluated by quantitative HER2 protein diagnostic methodologies: A comparative analysis [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 P1-03-02.

Elevated serum HER‐2 predicts poor prognosis in breast cancer and is correlated to ADAM10 expression

Human epidermal growth factor receptor‐2 (HER‐2) overexpression in breast tumor tissues is associated with a poor prognosis but may benefit from treatment with trastuzumab. The extracellular domain (ECD) of HER‐2 can be measured in serum and which has been a new inspection item in clinical laboratory of several hospitals. However, whether serum HER‐2 ECD can be a marker of HER‐2 status in tumor tissues still confused clinicians. This study is a retrospective observation to explore the correlation between serum HER‐2 ECD shedding and tissue HER‐2 status in breast cancer patients. Meanwhile, we will further uncover the potential clinical significance of serum HER‐2 ECD detection. A total of 545 unselected breast cancer patients from Fudan University Shanghai Cancer Center were enrolled in this study. At primary diagnosis without any treatment, serum HER‐2 ECD was measured on ADVIA Centaur assay; meanwhile, tissue HER‐2 from core needle biopsy was tested through immunohistochemistry (IHC) and fluorescent in situ hybridization (FISH). We showed that serum HER‐2 ECD concentration was related to tissue HER‐2 status. Nevertheless, 36.9% of patients with tissue HER‐2 overexpression had low levels of HER‐2 ECD shedding (<15 ng/mL) in serum. Here, we demonstrated that HER‐2 ECD shedding was also associated with protein expression and alpha‐secretase activity of a disintegrin and metalloproteinase 10 (ADAM10) using tumor tissues and cell lines. Progression‐free survival (PFS) data from breast cancer patients in TNM phase II and III with tissue HER‐2 IHC 3+ were analyzed using Kaplan‐Meier plotter. The patients with serum HER‐2 ECD above 15 ng/mL had lower progression‐free survival than those with serum HER‐2 ECD <15 ng/mL. Thus, serum HER‐2 ECD could be a biomarker to identify the subgroup of poorer outcome among HER‐2 overexpression breast cancer patients. Inhibition of ADAM10 activity may have potential therapeutic benefit for this most aggressive tumor subgroup.

High HER2 protein levels correlate with increased survival in breast cancer patients treated with anti-HER2 therapy

IntroductionCurrent methods to determine HER2 (human epidermal growth factor receptor 2) status are affected by reproducibility issues and do not reliably predict benefit from anti-HER2 therapy. Quantitative measurement of HER2 may more accurately identify breast cancer (BC) patients who will respond to anti-HER2 treatments. MethodsUsing selected reaction monitoring mass spectrometry (SRM-MS), we quantified HER2 protein levels in formalin-fixed, paraffin-embedded (FFPE) tissue samples that had been classified as HER2 0, 1+, 2+ or 3+ by immunohistochemistry (IHC). Receiver operator curve (ROC) analysis was conducted to obtain optimal HER2 protein expression thresholds predictive of HER2 status (by standard IHC or in situ hybridization [ISH]) and of survival benefit after anti-HER2 therapy. ResultsAbsolute HER2 amol/μg levels were significantly correlated with both HER2 IHC and amplification status by ISH (p < 0.0001). A HER2 threshold of 740 amol/μg showed an agreement rate of 94% with IHC and ISH standard HER2 testing (p < 0.0001). Discordant cases (SRM-MS-negative/ISH-positive) showed a characteristic amplification pattern known as double minutes. HER2 levels >2200 amol/μg were significantly associated with longer disease-free survival (DFS) and overall survival (OS) in an adjuvant setting and with longer OS in a metastatic setting. ConclusionQuantitative HER2 measurement by SRM-MS is superior to IHC and ISH in predicting outcome after treatment with anti-HER2 therapy.