Genotypic intratumoral heterogeneity in breast carcinoma with HER2/neu amplification: evaluation according to ASCO/CAP criteria

Understanding the spectrum of HER2 status in breast cancer: From HER2-positive to ultra-low HER2

HER2 (human epidermal growth factor receptor 2) status in breast cancer spans a spectrum from HER2-positive to ultra-low HER2, each category influencing prognosis and treatment decisions differently. Approximately 20 % of breast cancers overexpress HER2, correlating with aggressive disease and poorer outcomes without targeted therapy. HER2 status is determined through immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH), guiding therapeutic strategies. HER2-positive breast cancer exhibits HER2 protein overexpression or gene amplification, benefiting from HER2-targeted therapies like trastuzumab and pertuzumab. In contrast, HER2-negative breast cancer lacks HER2 overexpression and amplification, treated based on hormone receptor status. HER2-low breast cancer represents a newly recognized category with low HER2 expression, potentially benefiting from evolving therapies. Ultra-low HER2 cancers, characterized by minimal expression without gene amplification, challenge conventional classifications and treatment paradigms. Their distinct molecular profiles and clinical behaviors suggest unique therapeutic approaches. Recent diagnostic guideline updates refine HER2 assessment, enhancing precision in identifying patients for targeted therapies. Challenges remain in accurately classifying HER2-low tumors and optimizing treatment efficacy, necessitating ongoing research and innovative diagnostic methods. Understanding the heterogeneity and evolving landscape of HER2 status in breast cancer is crucial for advancing personalized treatment strategies and improving patient outcomes.

Discordance of HER2 Expression and/or Amplification on Repeat Testing

We sought to assess discordance of HER2 status in patients with HER2-amplified/expressing solid tumors who underwent reevaluation of HER2 status. Patients with metastatic solid tumors and HER2 expression by IHC or amplification by FISH/next-generation sequencing on local testing underwent central HER2 IHC/FISH testing with either archival or fresh biopsies and were evaluated for discordance in HER2 status. 70 patients (12 cancer types) underwent central HER2 reevaluation, including 57 (81.4%) with a new biopsy. In 30 patients with HER2 3+ on local IHC, 21 (70.0%) were 3+, 5 (16.7%) were 2+, 2 (6.7%) were 1+, and 2 (6.7%) had 0 HER2 expression on central IHC. In 15 patients whose cancers were 2+ on local IHC, 2 (13.3%) were 3+, 5 (33.3%) were 2+, 7 (46.7%) were 1+, and 1 (6.7%) had 0 HER2 expression on central IHC. HER2 discordance was seen in 16 of 52 (30.8%) of patients with HER2 overexpression/amplification who underwent a new image-guided biopsy. Discordance was observed in 10 (33.3%) of 30 patients who received intervening HER2-targeted therapy and in 6 (23.8%) of 22 patients who did not. In the 8 patients who had central HER2 assessment from the same archival block used for local testing, none were discordant. Discordance of HER2 status is common in patients with tumors previously identified as HER2-expressing, especially in patients with HER2 2+ tumors. Repeat biomarker evaluation may have value when considering HER2-targeted therapies.

HER2-low breast cancer: evolution of HER2 expression from primary tumor to distant metastases

BACKGROUND

Breast cancer (BC) with low human epidermal growth factor receptor 2 (HER2) expression is attracting much attention due to the breakthrough progress of novel anti-HER2 antibody-drug conjugates. HER2 expression is examined in patients with HER2-low BC and their distant metastases in this study, so as to further clarify the dynamic characteristics of HER2 low status in the process of disease progression.

METHODS

Patients diagnosed with HER2 low breast cancer (defined as IHC1+ or IHC2+/ISH-) between 2012 and 2021 were included in this study. We evaluated HER2 expression of primary sites and metastatic sites, compared the impact of different clinicopathological parameters on HER2 status of metastases and compared the overall survival and disease-free survival of patients with different HER2 status in metastases.

RESULTS

Ninety-eight patients were included. All HER2 IHC scores were confirmed and the consistent rate with the original pathological report was 81.1%. 27.6% of the patients showed different HER2 status in metastases. The HER2 discordance rate differed among different metastatic sites (p = 0.040). The higher the T stage of the primary BC, the higher the rate of HER2 discordance was observed (p = 0.042). For the specimen type of metastasis, HER2 discordant rate was higher in surgical specimen than biopsy (p = 0.050). No difference of HER2 discordance rate was found between HER2-1+ and HER2-2+ patients. But comparing HER2 IHC score, HER2-2+ patients were less likely to have consistent metastatic HER2 levels than HER2-1+ patients (p = 0.006). No difference in survival outcomes was observed between patients with different HER2 status in metastases.

CONCLUSIONS

There is a possibility of HER2 expression alteration in the metastases of HER2-low breast cancer. And the rate of altered HER2 low expression was different among different metastatic sites, different T stages of primary BC and specimen type of metastasis. No prognostic significance was observed.

Pathological identification of HER2-low breast cancer: Tips, tricks, and troubleshooting for the optimal test

The introduction of novel anti-HER2 antibody-drug conjugates (ADC) for the treatment of HER2-low breast cancers has transformed the traditional dichotomy of HER2 status to an expanded spectrum. However, the identification of HER2-low (i.e., immunohistochemistry (IHC) score 1 + or IHC score 2+, without gene amplification) tumors is challenged by methodological and analytical variables that might influence the sensitivity and reproducibility of HER2 testing. To open all possible therapeutic opportunities for HER2-low breast cancer patients the implementation of more accurate and reproducible testing strategies is mandatory. Here, we provide an overview of the existing barriers that may trouble HER2-low identification in breast cancer and discuss practical solutions that could enhance HER-low assessment.

Genomic Classification of HER2-Positive Patients With 80-Gene and 70-Gene Signatures Identifies Diversity in Clinical Outcomes With HER2-Targeted Neoadjuvant Therapy

The prospective Neoadjuvant Breast Registry Symphony Trial compared the 80-gene molecular subtyping signature with clinical assessment by immunohistochemistry and/or fluorescence in situ hybridization in predicting pathologic complete response (pCR) and 5-year outcomes in patients with early-stage breast cancer.

Update on prognostic and predictive biomarkers of breast cancer

Breast cancer represents a heterogeneous group of human cancer at both histological and molecular levels. Estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) are the most commonly used biomarkers in clinical practice for making treatment plans for breast cancer patients by oncologists. Recently, PD-L1 testing plays an important role for immunotherapy for triple-negative breast cancer. With the increased understanding of the molecular characterization of breast cancer and the emergence of novel targeted therapies, more potential biomarkers are needed for the development of more personalized treatments. In this review, we summarized several main prognostic and predictive biomarkers in breast cancer at genomic, transcriptomic and proteomic levels, including hormone receptors, HER2, Ki67, multiple gene expression assays, PD-L1 testing, mismatch repair deficiency/microsatellite instability, tumor mutational burden, PIK3CA, ESR1 andNTRK and briefly introduced the roles of digital imaging analysis in breast biomarker evaluation.

Efficacy of trastuzumab emtansine (T-DM1) and lapatinib after dual HER2 inhibition with trastuzumab and pertuzumab in patient with metastatic breast cancer: Retrospective data from a French multicenter real-life cohort

Purpose

Trastuzumab-emtansine (T-DM1), as well as lapatinib plus capecitabine were proven effective in two Phase III studies, following first-line trastuzumab plus a taxane. The introduction of dual HER2 blockade by trastuzumab and pertuzumab as first-line has positioned T-DM1 into second-line, and lapatinib plus capecitabine beyond, without formal evaluation of these strategies.

Methods

ESME Data Platform (NCT03275311) included individual data from all patients aged ≥18 years, in whom first-line treatment for metastatic breast cancer (MBC) was initiated between January 1, 2008 and December 31, 2016 in one of the 18 French Comprehensive Cancer Centers. The efficacy of T-DM1 and lapatinib plus capecitabine combination, following double blockade associating trastuzumab and pertuzumab were evaluated in this national real-life database. Eligibility criteria were: female, MBC, HER2+ tumor, first-line taxane-based chemotherapy and dual HER2-blockage by trastuzumab plus pertuzumab. Cohort A received second-line T-DM1, and Cohort B second-line T-DM1 and third or fourth-line lapatinib plus capecitabine.

Results

Cohort A comprised 233 patients, and Cohort B 47 patients. Median progression-free survival (PFS) was 7.1 months in Cohort A and 4.6 months in Cohort B. Median overall survival were 36.7 months and 12.9 months, respectively. PFS was significantly dependent on the preceding treatment line's duration. In cohort A, HER2 expression status was a significant predictive factor of PFS.

Conclusion

First-line trastuzumab plus pertuzumab do not markedly diminish T-DM1's efficacy in second-line. Similarly, sequential treatment with trastuzumab plus pertuzumab then T-DM1 does not noticeably modify the efficacy of lapatinib plus capecitabine.

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French real-life cohort.

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Dual blockade HER2 does not markedly diminish T-DM1's activity in second-line and lapatinib's activity in third or fourth line.

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The second-line (T-DM1) PFS was significantly longer when the first-line treatment with trastuzumab plus pertuzumab was ≥12 months.

Digital Imaging Correlation of Immunohistochemistry and Fluorescence in Situ Hybridization in Breast Carcinoma Cases with HER2 Genetic Heterogeneity

Genetic Heterogeneity (GH) is a rare but important event in evaluation of HER2 amplification status. We investigated whether HER2 FISH Genetic Heterogeneity (GH) correlated with increased protein expression by immunohistochemistry (IHC) and/or morphologic features using image analyses. Retrospective search of HER2 FISH GH cases 2016-2020 was performed. Cases with both FISH and IHC slides available were considered eligible and were digitally imaged. Additional demographic, histological, and treatment information was compiled from pathology and medical records when available. Overall, 11/15 (73.3%) of the cases had HER2 FISH GH that matched to areas of HER2 over-expression or focally different morphology. Nine cases with areas of gene amplification overlapped with <10% of intense circumferential protein expression ("Mini 3+,"), and one case with focal micropapillary features. Clinical information was available on 6 (40%) patients, all were alive with no evidence of disease (mean follow up 30. 5 months; range 12-65 months). One patient with GH and a lymph node metastasis showed non-amplified population in the nodal tumor. GH when defined as discrete clusters of amplified cells following 2013 ASCO/CAP guidelines, -even when less than 10 % of the tumor cells-frequently has morphologic correlates such as focal intense protein overexpression or micropapillary morphology. Clinical significance of these focal gene amplification and protein over-expression needs to be further investigated.

Molecular characterization of extrahepatic cholangiocarcinoma: perihilar and distal tumors display divergent genomic and transcriptomic profiles

BACKGROUND

Extrahepatic cholangiocarcinoma (ECC) is classified into two subtypes based on anatomic origin: distal extrahepatic (DECC) and perihilar (PHCC) cholangiocarcinoma. This study aimed to shed light on its genomic and transcriptomic profiles.

RESEARCH DESIGN AND METHODS

The genomic alterations of 99 ECC (47 PHCC and 52 DECC) were investigated by next-generation sequencing of 96 genes. A subgroup of cases, representative of each subtype, was further investigated using transcriptomic analysis. Bioinformatics tools were applied for clustering and pathway analysis and defining the immune composition of the tumor microenvironment.

RESULTS

PHCC had more frequent KRAS mutations (p = 0.0047), whereas TP53 mutations were more common in DECC (p = 0.006). Potentially actionable alterations included high-tumor mutational burden and/or microsatellite instability (7.1%), PI3KCA mutations (8.1%), and MYC (10.1%) and ERBB2 amplification (5.1%). The transcriptomic profiles showed the presence of three distinct clusters, which followed the anatomic origin and differed in immune microenvironment. DECC appeared to contain two distinct tumor subgroups, one enriched for druggable alterations and one lacking actionable opportunities.

CONCLUSIONS

This study provides new insights into the molecular landscape and the actionable alterations of ECC. Our findings represent a step toward improved ECC molecular taxonomy and therapeutic strategies for precision oncology.

Comparison of the multigene panel test and OncoScan™ for the determination of HER2 amplification in breast cancer

The diagnostic accuracy of the multigene panel test (MPT) and OncoScan™ in the determination of HER2 amplification in breast tumors remains controversial. In the present study, HER2 copy number was analyzed using both MPT and OncoScan™ in 45 breast tumors and was compared with that in fluorescent in situ hybridization (FISH) analysis. Tumors with low cellularity were examined using tumor cell enrichment and fluorescence‑activated cell sorting. Both MPT and OncoScan™ exhibited significant correlations with FISH with respect to the determination of HER2 amplification in breast tumors. However, the correlation coefficient was significantly higher for the comparison of MPT and FISH (r=0.770) compared with that between OncoScan™ and FISH (r=0.564). The accuracy of MPT (93.3%) was slightly higher compared with that in OncoScan™ (84.4%) in determining the HER2 status, which was mostly explained by the higher sensitivity of MPT in tumors with low cellularity (83.3 vs. 33.3%), but not in those with high cellularity (81.8 vs. 72.7%). The specificity was 100% for both tests. The MPT exhibited higher sensitivity in the determination of the amplification of other genes, including MYC, fibroblast growth factor receptor 1 and GATA binding protein 3 in tumors with low cellularity compared with that in tumors with high cellularity. OncoScan™ exhibited low sensitivity without tumor cell enrichment. The results suggested that MPT could be a promising method to determine HER2 status in breast tumors and that it could exhibit improved accuracy compared with that in OncoScan™ in tumors with low cellularity.

HER2 Testing Characteristics Can Predict Residual Cancer Burden following Neoadjuvant Chemotherapy in HER2-Positive Breast Cancer

Objectives

The response to HER2-targeted neoadjuvant chemotherapy (NAC) in HER2-positive (+) breast cancer can be quantified using residual cancer burden (RCB) pathologic evaluation to predict relapse free/overall survival. However, more information is needed to characterize the relationship between patterns of HER2 testing results and response to NAC. We evaluated clinicopathologic characteristics associated with RCB categories in HER2+ patients who underwent HER2-directed NAC.

Methods

A retrospective chart review was conducted with Stage I-III HER2+ breast cancer cases following NAC and surgical resection. HER2 immunohistochemistry (IHC) staining and fluorescence in situ hybridization (FISH), histologic/clinical characteristics, hormone receptor status, and RCB scores (RCB-0, RCB-I, RCB-II, and RCB-III) were evaluated.

Results

64/151 (42.4%) patients with HER2+ disease had pathologic complete response (pCR). Tumors with suboptimal response (RCB-II and RCB-III) were more likely to demonstrate less than 100% HER2 IHC 3+ staining (p < 0.0001), lower HER2 FISH copies (p < 0.0001), and lower HER2/CEP17 ratios (p = 0.0015) compared to RCB-I and RCB-II responses. Estrogen receptor classification using ≥10% versus ≥1% staining showed greater association with higher RCB categories.

Conclusions

HER2+ characteristics show differing response to therapy despite all being categorized as positive; tumors with less than 100% IHC 3+ staining, lower HER2 FISH copies, and lower HER2/CEP17 ratios resulted in higher RCB scores.

Estrogen Receptor, Progesterone Receptor, and Human Epidermal Growth Factor Receptor-2 Testing in Breast Cancer: Assessing the Value of Repeated Centralized Testing in Excision Specimens

At some tertiary breast care centers, where many patients are referred from other institutions, it is routine to repeat testing for estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER2/neu) in excision specimens if these tests were performed on the preceding biopsy at the referring facility. The goal of this study is to assess the value of this practice. We documented results from ER, PR, and HER2 testing in 541 consecutive invasive breast cancers excised over a 2.5-year period and analyzed the subset (n=153) for which testing was performed on the excision specimen solely due to the fact that testing on the preceding biopsy was performed at an outside institution. The rates and directions of biopsy-to-excision change were as follows: ER [1.3% (2/153), 100% from (+) to (-)]; PR [4% (6/153), 83% from (+) to (-)]; HER2/neu assessed by immunohistochemistry [21% (29/137)]; HER2/neu assessed by fluorescence in situ hybridization [3.3% (2/61); 50% from amplified to nonamplified and 50% vice versa]. There were no ER(-) and PR(-) biopsy cases that became ER and/or PR(+) in the excision. By coordinate analysis for the hormone receptors [ie, ER and/or PR(+) being indicative of "hormone receptor" (HR) positivity], there were no cases that changed from HR(+) in the biopsy to HR(-) in the excision (or vice versa), which suggests that repeat testing for ER and PR in this setting is of limited value. In an analysis that incorporated both immunohistochemistry and in situ fluorescence hybridization results, there were 2 cases with a clinically significant biopsy-to-excision change in HER2/neu status in which that change was detected primarily because the excision was retested. These findings provide baseline data for formulating policies on whether repeat testing should routinely be performed in the described scenario.

HER2 intratumoral heterogeneity is independently associated with distal metastasis and overall survival in HER2-positive breast carcinomas

PURPOSE

Human epidermal growth factor receptor 2 (HER2) intratumoral heterogeneity (ITH) occurs in a subset of breast cancers. Our recent study revealed it as an independent predictive factor for the response to anti-HER2 neoadjuvant therapy. In this study, we aimed to investigate its association with distal metastasis.

METHODS

HER2 ITH was assessed using HER2 gene protein assay (GPA) on whole tissue sections of pretreatment biopsies from a cohort of 158 HER2-positive invasive breast carcinomas and correlated with patients' clinical follow-up outcomes along with other clinicopathologic characteristics.

RESULTS

Fifty-seven cases (36%) showed HER2 ITH including 19 with genetic, 8 with both genetic and non-genetic, and 30 with non-genetic ITH. Multivariate analysis demonstrated larger tumor size, positive resected lymph node(s), negative PR, and the presence of HER2 ITH were independently associated with distal metastasis. Additionally, multivariate analysis demonstrated larger tumor size and the presence of HER2 ITH were the only independent factors associated with decreased overall survival (death).

CONCLUSION

The presence of HER2 ITH is an independent factor associated with poor overall survival and increased distal metastasis in HER2-positive breast cancer patients.

Deciphering HER2 Breast Cancer Disease: Biological and Clinical Implications

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

Novel HER2-Targeting Antibody-Drug Conjugates of Trastuzumab Beyond T-DM1 in Breast Cancer: Trastuzumab Deruxtecan(DS-8201a) and (Vic-)Trastuzumab Duocarmazine (SYD985)

Targeted drug delivery has improved cancer treatment significantly in recent years, although it is difficult to achieve. Different approaches have been developed to apply targeted drug delivery. Among which, antibody-drug conjugate (ADC) provides a potentially ideal solution to such a challenge. ADC is an innovative drug treatment model with three key components: payload, monoclonal antibody, and linker. The monoclonal antibody targets the antigen-expressing tumor cells and internalizes the payload linked by the linker to the target cells to reduce the side effects of the traditional chemotherapy drugs. The off-target effect has an excellent therapeutic prospect. Among them, ado-trastuzumab emtansine (T-DM1) is a successful example of targeting human epidermal growth factor receptor-2 (HER2). Its antibody (trastuzumab) is derived from Herceptin with annual sales of more than $6 billion. It has excellent targeting and specific anti-tumor activity against HER2. Its linker is not cleavable and releases the Lys-linker-payload to kill the cells. The two ADCs described here use the same antibody as T-DM1, but the cleavable linker and the more toxic payload allow them to have the not only targeting of T-DM1, but also the reduce T-DM1 resistance and improve efficacy in heterogeneous tumors. This paper describes the mechanism of action and the biochemical characteristics of different parts and preclinical and clinical progress of trastuzumab deruxtecan(DS-8201a) and (vic-)trastuzumab duocarmazine (SYD985).

Hormone receptor, human epidermal growth factor receptor-2, and Ki-67 status in primary breast cancer and corresponding recurrences or synchronous axillary lymph node metastases

The therapeutic strategy for breast cancer is determined by the surrogate subtype, which is defined by biomarkers, such as estrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor receptor-2 (HER2), and Ki-67. In previous reports, the rate of discordance in ER, PgR, and HER2 between primary breast cancer and recurrent lesions or synchronous axillary lymph node metastasis was 15-25, 25-40, and 5-25 or 7-50, 10-50, and 3-30%, respectively. Overall, hormone receptors tended to weaken during the metastatic process, while patterns of HER2 were not uniform. Regarding the Ki-67 labeling index, an increase in metastatic lesions compared with primary lesions was the dominant pattern, suggesting that aggressive subclones with high proliferative potential form metastases. The loss of expression of hormone receptor or an increase in the Ki-67 labeling index in metastasis seemed to be associated with a poor prognosis. However, most previous studies did not report the background characteristics of patients, or they included subjects with varied characteristics, including those on systemic therapy, and were based on relatively small populations; therefore, definitive conclusions could not be drawn. Future studies should explore how to select therapies according to the biomarkers in primary breast cancer and/or its metastasis.

Pathologic Features and Clinical Implications of Breast Cancer With HER2 Intratumoral Genetic Heterogeneity

OBJECTIVES

To review breast cancer with human epidermal growth factor receptor 2 (HER2) genetic heterogeneity (GH), with a focus on clinician interpretation of the results and subsequent management.

METHODS

We retrospectively searched all consecutive invasive breast cancers that underwent HER2 fluorescent in situ hybridization testing and identified cases with HER2 GH.

RESULTS

Eleven (0.4%) cases of primary breast tumors with reported HER2 GH were identified over 76 months. HER2-positive tumor cells comprised a mean ± SD of 20% ± 15% of the overall tumor population (range, 5%-50%) and exhibited high levels of amplification (HER2/CEP17 = 5.4 ± 2.9). Three cases had morphologic heterogeneity. Of the four patients who completed neoadjuvant chemotherapy, two had trastuzumab; all showed a partial pathologic response. We identified two cases in which there appeared to be clinical misinterpretation of the HER2 results.

CONCLUSIONS

HER2 GH is an infrequent event, may contain morphologic heterogeneity, could infer incomplete response to neoadjuvant therapy, and requires adequate communication with treating clinicians.

Relationship between tumor biomarkers and efficacy in MARIANNE, a phase III study of trastuzumab emtansine ± pertuzumab versus trastuzumab plus taxane in HER2-positive advanced breast cancer

Background

The phase III EMILIA and TH3RESA trials demonstrated clinical benefits of trastuzumab emtansine (T-DM1) therapy in patients with previously treated HER2-positive metastatic breast cancer (MBC). Data from these and other trials showed that T-DM1–associated survival benefits were observed across biomarker subgroups tested in these trials. Prespecified, exploratory analyses of the phase III MARIANNE study examined the effects of HER2-related biomarkers on PFS in patients administered T-DM1 in the first-line MBC setting.

Methods

In MARIANNE, patients with previously untreated HER2-positive MBC were randomized (1:1:1) to trastuzumab plus taxane, T-DM1 plus placebo, or T-DM1 plus pertuzumab. Biomarker subgroups included HER2 and HER3 mRNA expression levels (≤median vs. >median), HER2 staining intensity (IHC 3+ vs. 2+ vs. 0/1+), PIK3CA status (mutated vs. non-mutated), PTEN H-score (≤median vs. >median), and PTEN protein expression level (0 vs. 1+ vs. 2+ vs. 3+ vs. 4+). PFS was analyzed descriptively for each subgroup using Kaplan–Meier methodology. Additional exploratory post-hoc analyses evaluated the effects of HER2 heterogeneity. Multivariate analyses were also performed.

Results

Median PFS was numerically longer for patients with HER2 mRNA levels >median versus ≤median across treatment arms. In general, there were no predictive biomarkers of benefit for either T-DM1 treatment arm; most hazard ratios were close to 1 with wide confidence intervals that included the value 1. Focal HER2 expression (IHC 3+ or IHC 2+) was present in 3.8% of patients and was associated with numerically shorter PFS in the T-DM1–containing treatment arms versus trastuzumab plus taxane. Compared with non-mutated PIK3CA, mutated PIK3CA was associated with numerically shorter median PFS across treatment groups. Post-hoc multivariate analysis showed HER2 mRNA expression and mutated PIK3CA were prognostic for PFS (P ≤ 0.001 for both biomarkers).

Conclusions

In MARIANNE, biomarkers related to the HER2 pathway did not have predictive value for PFS when comparing T-DM1 (with or without pertuzumab) with trastuzumab plus taxane. However, HER2 mRNA level and PIK3CA mutation status showed prognostic value. Evaluation of other potential biomarkers, including immune markers, is ongoing.

Trial registration

Registration number: NCT01120184. Date of registration: April 28, 2010 (registered prospectively).

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5687-0) contains supplementary material, which is available to authorized users.

Histopathological markers of treatment response and recurrence risk in ovarian cancers and borderline tumors

Histopathology plays an important role in defining response to treatment for different tumor types. Histopathologic response criteria are currently used as reference standard in various types of cancer, including breast cancer, gastroesophageal cancer, and bone tumors. Since there were no generally accepted response criteria established for ovarian cancer, a systematic analysis of various features of tumor regression was performed. Patient survival served as the reference standard to validate the histopathologic features of tumor regression. In contrast to ovarian cancer, borderline ovarian tumors are epithelial ovarian neoplasms characterized by up-regulated cellular proliferation and cytologic atypia but without destructive stromal invasion. While borderline ovarian tumors generally have an excellent prognosis with a 5‑year survival of > 95%, recurrences and malignant transformation occur in a small percentage of patients. Nevertheless, the identification of patients at increased risk for recurrence remains difficult. The aim of studying histopathological markers in ovarian cancers and borderline tumors was to evaluate whether histopathologic features including molecular pathologic alterations can predict patient outcome, particularly the risk of recurrence of serous and mucinous borderline tumors.

Core needle biopsy as an alternative to whole section in IHC4 score assessment for breast cancer prognostication

AIMS

IHC4 score, based on expression of four routine markers (oestrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) and proliferation marker, Ki67), is a recently developed, cost-effective prognostic tool in breast cancer. Possibly, the score may be useful also in advanced diseases where only core needle biopsy (CNB) is available and neoadjuvant therapy. However, its studies on CNB are scant. This study examined whether IHC4 score assessment on CNB is comparable to that from whole section (WS).

METHODS

Immunohistochemical (IHC) analysis was performed for ER, PR, HER2 and Ki67 on 108 paired CNB and WS to evaluate IHC4 score (with follow-up range 1-230 months and 5 relapse/death). Concordance between the two was examined. Factors that affected the concordance were analysed. Additionally, IHC4 score was compared with Nottingham Prognostic Index (NPI).

RESULTS

There was moderate concordance between IHC4 score on CNB and WS (all cases: κ=0.699, p<0.001; ER+ cases: κ=0.595, p<0.001). Among the IHC4 components, concordance for HER2 was the poorest (κ=0.178, p<0.001 in all cases; ER+ cases: κ=0.082, p<0.097). Significant factors affecting concordance between CNB and WS included number of cores, total core length and percentage of tumour cells in cores (p≤0.030), indicating the importance of sufficient sampling. Interestingly, the concordance was also affected by patients' age (p=0.039). There was poor agreement between IHC4 score and NPI (κ≤0.160).

CONCLUSION

Our results suggested that IHC4 score can be used on adequately sampled CNB. Its poor agreement with NPI highlights the independence of the two factors.

Equivocal (HER2 IHC 2+) breast carcinomas: gene-protein assay testing reveals association between genetic heterogeneity, individual cell amplification status and potential treatment benefits

AIMS

Genetic heterogeneity can pose a challenge to identifying eligible cases for targeted therapy in the human epidermal growth factor receptor 2 (HER2) immunohistochemistry (IHC) 2+ breast carcinoma group. In this study, we characterised this subset of tumours according to clinicopathological parameters.

METHODS AND RESULTS

We assessed 1000 tumour cells per case and recorded the number of HER2 and chromosome enumeration probe 17 (CEP17) copies using gene-protein assay slides. HER2 status was determined based on ASCO/CAP 2013 guidelines. Tumours with 5-50% of cancer cells with amplification were considered to be heterogeneous, whereas those with >50% were considered to be non-heterogeneous. In a study cohort of 110 HER2 IHC 2+ carcinomas, 93 (84.5%) were non-amplified, 12 (10.9%) were amplified and five (4.5%) were ISH-equivocal. All the HER2-amplified and two of ISH-equivocal cases (12.7%) corresponded to non-heterogeneous tumours, with highly significant differences evident in the average HER2/CEP17 ratio (P = 0.0002) and the proportion of cells with HER2 >6 copies (P < 0.0001) compared with heterogeneous lesions. NST grade 3 and HER2-amplified carcinomas average HER2/CEP17 ratio correlated with an increased number of cells with HER2/CEP17 ≥2.0 (P < 0.014). Triple-negative CEP17 polysomic carcinomas showed increased metastatic capacity (P = 0.003) compared with other tumour types.

CONCLUSION

Non-heterogeneous HER2 IHC 2+ tumours tend to be HER2-amplified. Adding the percentage of cells with HER2 >6 copies to the average HER2/CEP17 ratio may facilitate assessment of amplification status in ISH-equivocal cases. The proportion of cells with HER2/CEP17 ≥2.0 contributes information concerning the actual average HER2/CEP17 ratio, depending on tumour type.

HER2 Heterogeneity Is Associated with Poor Survival in HER2-Positive Breast Cancer

Intratumoral human epidermal growth factor receptor 2 (HER2) heterogeneity has been reported in 16⁻36% of HER2-positive breast cancer and its clinical impact is under discussion. We examined the biological effects of HER2-heterogeneity on mouse models and analyzed metastatic brains by RNA sequence analysis. A metastatic mouse model was developed using 231-Luc (triple negative cells) and 2 HER2-positive cell lines, namely, HER2-60 and HER2-90 which showed heterogeneous and monotonous HER2 expressions, respectively. Metastatic lesions developed in 3 weeks in all the mice injected with HER2-60 cells, and in 69% of the mice injected with HER2-90 and 87.5% of the mice injected with 231-Luc. The median survival days of mice injected with 231-Luc, HER2-60, and HER2-90 cells were 29 (n = 24), 24 (n = 22) and 30 (n = 13) days, respectively. RNA sequence analysis showed that CASP-1 and its related genes were significantly downregulated in metastatic brain tumors with HER2-60 cells. The low expression of caspase-1 could be a new prognostic biomarker for early relapse in HER2-positive breast cancer.

Genetic alterations analysis in prognostic stratified groups identified TP53 and ARID1A as poor clinical performance markers in intrahepatic cholangiocarcinoma

The incidence and mortality rates of intrahepatic cholangiocarcinoma have been rising worldwide. Few patients present an early-stage disease that is amenable to curative surgery and after resection, high recurrence rates persist. To identify new independent marker related to aggressive behaviour, two prognostic groups of patient were selected and divided according to prognostic performance. All patients alive at 36 months were included in good prognostic performers, while all patients died due to disease within 36 months in poor prognostic performers. Using high-coverage target sequencing we analysed principal genetic alterations in two groups and compared results to clinical data. In the 33 cases included in poor prognosis group, TP53 was most mutated gene (p = 0.011) and exclusively present in these cases. Similarly, ARID1A was exclusive of this group (p = 0.024). TP53 and ARID1A are mutually exclusive in this study. Statistical analysis showed mutations in TP53 and ARID1A genes and amplification of MET gene as independent predictors of poor prognosis (TP53, p = 0.0031, ARID1A, p = 0.0007, MET, p = 0.0003 in Cox analysis). LOH in PTEN was also identified as marker of disease recurrence (p = 0.04) in univariate analysis. This work improves our understanding of aggressiveness related to this tumour type and has identified novel prognostic markers of clinical outcome.

Improving accuracy of breast cancer biomarker testing in India

There is a global mandate even in countries with low resources to improve the accuracy of testing biomarkers in breast cancer viz. oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2neu) given their critical impact in the management of patients. The steps taken include compulsory participation in an external quality assurance (EQA) programme, centralized testing, and regular performance audits for laboratories. This review addresses the status of ER/PR and HER2neu testing in India and possible reasons for the delay in development of guidelines and mandate for testing in the country. The chief cause of erroneous ER and PR testing in India continues to be easily correctable issues such as fixation and antigen retrieval, while for HER2neu testing, it is the use of low-cost non-validated antibodies and interpretative errors. These deficiencies can however, be rectified by (i) distributing the accountability and responsibility to surgeons and oncologist, (ii) certification of centres for testing in oncology, and (iii) initiation of a national EQA system (EQAS) programme that will help with economical solutions and identifying the centres of excellence and instill a system for reprimand of poorly performing laboratories.

Challenges and future of biomarker tests in the era of precision oncology: Can we rely on immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH) to select the optimal patients for matched therapy?

Molecular techniques have improved our understanding of the pathogenesis of cancer development. These techniques have also fueled the rational development of targeted drugs for patient populations stratified by their genetic characteristics. These novel methods have changed the classic paradigm of diagnostic pathology; among them are IHC, FISH, polymerase chain reaction (PCR) and microarray technology. IHC and FISH detection methods for human epidermal growth factor receptor-2 (HER2), epidermal growth factor receptor (EGFR) and programmed death ligand-1 (PD-L1) were recently approved by the Food and Drug Administration (FDA) as routine clinical practice for cancer patients. Here, we discuss general challenges related to the predictive power of these molecular biomarkers for targeted therapy in cancer medicine. We will also discuss the prospects of utilizing new biomarkers for fibroblast growth factor receptor (FGFR) and hepatocyte growth factor receptor (cMET/MET) targeted therapies for developing new and robust predictive biomarkers in oncology.

High Histologic Grade and High Ki-67 Expression Predict Phenotypic Alterations in Node Metastasis in Primary Breast Cancers

PURPOSE

Several studies have shown that estrogen receptor (ER) and progesterone receptor (PR) expression and human epidermal growth factor receptor 2 (HER2) expression may vary during tumoral progression. We aimed to describe and compare ER, PR, and HER2 expressions in primary breast tumors and synchronic axillary nodal metastases, and evaluate phenotypic correlations between them.

METHODS

Patients were identified prospectively through surgical procedures between September 2013 and July 2016. The status of ER, PR, HER2, and Ki-67 were pathologically analyzed in breast cancers and axillary nodal metastases; these patients were classified based on the breast cancer phenotypes into five subgroups.

RESULTS

Synchronic axillary nodal metastases were observed in 127 patients. In breast cancers and nodal metastases, correlation analyses of ER, PR, and Ki-67 expression showed a statistical dependence and concordance between these samples was unambiguously demonstrated through Bland-Altman plots for each determination. Primary breast tumors were classified as follows: luminal A, 41.6%; luminal B, 40.0%; luminal B/HER2, 9.6%; HER2, 2.4%; triple negative, 6.4%. Alterations in phenotype were observed in 28% of patients. The most frequent phenotypic alteration was from luminal B to A (36.4%). Ten cases (30.3%) showed alterations with therapeutic implications; six gained HER2 overexpression, and four, hormonal receptor (HR) expression. A moderate strength of agreement (Cohen's κ coefficient, 0.59; 95% confidence interval, 0.48-0.71) was observed. In multivariate analyses, high histologic grade (odds ratio [OR], 2.79; p<0.047) and high Ki-67 expression (OR, 1.05; p<0.037) were independent factors predictive of phenotypic alterations.

CONCLUSION

Strong correlations were observed in HR and Ki-67 expressions between primary breast tumors and axillary nodal metastases, and a moderate concordance was observed in their phenotypical characteristics. Nevertheless, alterations did exist, and one-third of these changes may have therapeutic implications. The nodal metastases of tumors with high grade and high Ki-67 expression may need to be analyzed, to obtain complete therapeutic information.

'Non-classical' HER2 FISH results in breast cancer: a multi-institutional study

The 2013 CAP/ASCO HER2 Testing Guidelines Update modified HER2 FISH categories such that some cases with 'monosomy', 'co-amplification/polysomy', low-level increased HER2 signals or clustered heterogeneity now are considered amplified or equivocal. This study examines the frequency and clinico-pathologic characteristics of breast cancers with equivocal or 'non-classical' HER2 FISH results. Breast cancers (2001-2014) with HER2 FISH results, HER2 immunohistochemistry, ER, grade, and age from three institutions (Stanford, UCSF, UWMC) were collected. HER2 FISH was interpreted using the updated recommendations. Amplified cases with non-classical results were grouped into the following categories: (1) 'monosomy' (ratio ≥2.0, mean HER2/cell<4.0); (2) 'co-amplified' (ratio<2.0, mean HER2/cell ≥6.0); (3) 'low amplified' (ratio ≥2.0, mean HER2/cell 4.0-5.9). Heterogeneous cases with clustered HER2-positive cells were also included. Of 8068 cases, 5.2% were equivocal and 4.6% had a 'non-classical' HER2 amplified result; 1.4% 'monosomy', 0.8% 'co-amplified', 2.1% 'low amplified', and 0.3% clustered heterogeneity. These cancers had a high frequency of ER positive (80.4%), Nottingham grade 3 (52.1%) results. The highest percentage of grade 3 cancers (66.7%) and positive HER2 immunohistochemistry (31.7%) was in the 'co-amplified' group. The 'monosomy' group had the highest percent grade 1 cancers (13.3%) and was most frequently HER2 immunohistochemistry negative (30.1%). Equivocal cases had very similar characteristics to the 'low-amplified' category. Cases with non-classical HER2 amplification or equivocal results are typically ER positive, higher grade cancers. 'Co-amplified' cases have the highest frequencies of aggressive characteristics and 'monosomy' cases the highest frequencies of lower risk features. With little clinical outcomes data currently available on these non-classical HER2 results, these results support the current classification scheme for HER2 FISH, with case-by-case correlation with additional clinical-pathologic factors when evaluating whether to offer HER2-targeted therapies in these non-classical cases.

[89Zr]Trastuzumab: Evaluation of Radiation Dosimetry, Safety, and Optimal Imaging Parameters in Women with HER2-Positive Breast Cancer

PURPOSE

The purpose of the present study is to evaluate safety, human radiation dosimetry, and optimal imaging time of [89Zr]trastuzumab in patients with HER2-positive breast cancer.

PROCEDURES

Twelve women with HER2-positive breast cancer underwent [89Zr]trastuzumab positron emission tomography (PET)/X-ray computed tomography (CT) twice within 7 days post-injection. Biodistribution data from whole-torso PET/CT images and organ time-activity curves were created using data from all patients. Human dosimetry was calculated using OLINDA with the adult female model.

RESULTS

High-quality images and the greatest tumor-to-nontumor contrast were achieved with images performed 5 ± 1 day post-injection. Increased [89Zr]trastuzumab uptake was seen in at least one known lesion in ten patients. The liver was the dose-limiting organ (retention of ∼12 % of the injected dose and average dose of 1.54 mSv/MBq). The effective dose was 0.47 mSv/MBq. No adverse effects of [89Zr]trastuzumab were encountered.

CONCLUSION

[89Zr]trastuzumab was safe and optimally imaged at least 4 days post-injection. The liver was the dose-limiting organ.

Targeted next-generation sequencing enables reliable detection of HER2 (ERBB2) status in breast cancer and provides ancillary information of clinical relevance

HER2-positive breast cancers are a heterogeneous group of tumors, which share amplification and overexpression of HER2. In routine diagnostics, the HER2 (ERBB2) status is currently assessed by immunohistochemistry (IHC) and in situ hybridization (ISH). Data on targeted next-generation sequencing (NGS) approaches that could be used to determine the HER2 status are sparse. Employing two breast cancer-related gene panels, we performed targeted NGS of 41 FFPE breast cancers for which full pathological work-up including ISH and IHC results was available. Selected cases were analyzed by qPCR. Of the 41 cases, the HER2 status of the 4 HER2-positive and 6 HER2-negative tumors was independently detected by our NGS approach achieving a concordance rate of 100%. The remaining 31 cases were equivocal HER2 cases by IHC of which 5 showed amplification of HER2 by ISH. Our NGS approach classified all non-amplified cases correctly as HER2 negative and corroborated all but one of the 5 cases with amplified HER2 as detected by ISH. For the overall cohort, concordance between the gold standard and NGS was 97.6% (sensitivity 88.9% and specificity 100%). Additionally, we observed mutations in PIK3CA (44%), HER2 (8%), and CDH1 (6%) among others. Amplifications were found in CCND1 (12%), followed by MYC (10%) and EGFR (2%) and deletions in CDKN2A (10%), MAP2K4 and PIK3R1 (2% each). We here show that targeted NGS data can be used to interrogate the HER2 status with high specificity and high concordance with gold standard methods. Moreover, this approach identifies additional genetic events that may be clinically exploitable. © 2016 Wiley Periodicals, Inc.

[Immunohistochemical changes in the lungs from fetuses and newborn infants at 20- 40 weeks' gestation with false left-sided congenital diaphragmatic hernia]

OBJECTIVE

to study changes in the expression of growth factors in the lungs from fetuses and newborn infants at 20-40 weeks' gestation with false left-sided congenital diaphragmatic hernia (CDH).

MATERIAL AND METHODS

Lung fragments obtained at autopsies were examined using immunohistochemically stained paraffin sections. The expression indices of insulin-like growth factor-1 (IGF-1), platelet-derived growth factor (PDGF), epidermal growth factor (EGF), and transforming grow factor-β (TGF-β) in the fetal lung sections were compared with the results of survey and elective staining techniques, the morphometric data of digitized lung sections, and the indicators obtained in the comparison group.

RESULTS

Morphofunctional changes in the connective tissue, pulmonary vessels, and bronchial and alveolar epithelium at 20-24, 25-27, and 28-40 weeks' gestation were characterized, partly explaining the development of bilateral pulmonary hypoplasia in CDH. There was evidence for the involvement of PDGF, IGF-1, and EGF in primary pulmonary hypoplasia. PDGF deficiency plays a certain role in secondary pulmonary hypoplasia.

CONCLUSION

The findings can be used in researches and in the practical work of pathologists and forensic medical experts.

HER2 Status in Premalignant, Early, and Advanced Neoplastic Lesions of the Stomach

Objectives. HER2 expression in gastric cancer (GC) has received attention as a potential target for therapy with Trastuzumab. We reviewed the current knowledge on HER2 status in premalignant gastric lesions and in early (EGC) and advanced (AGC) GC to discuss the possible pathogenetic and prognostic roles of HER2 overexpression in GC. Results. HER2 overexpression was documented in gastric low-grade (LG) and high-grade intraepithelial neoplasia (HG-IEN), with higher frequency in gastric type dysplasia. HER2 overexpression was significantly associated with disease recurrence and poor prognosis in EGC representing an independent risk factor for lymph node metastases. HER2 overexpression was more frequent in AGC characterized by high grade, advanced stage, and high Ki-67 labeling index. The discordance in HER2 status was evidenced between primitive GC and synchronous or metachronous metastases. Conclusions. HER2 overexpression in premalignant gastric lesions suggests its potential involvement in the early steps of gastric carcinogenesis. The assessment of HER2 status in EGC may be helpful for the identification of patients who are at low risk for developing nodal metastases. Finally, the possible discordance in HER2 status between primary GC and its synchronous metastases support routine assessment of HER2 both in the primary GC and in its metastatic lesions.

Clinicopathologic Significance of the Intratumoral Heterogeneity of HER2 Gene Amplification in HER2-Positive Breast Cancer Patients Treated With Adjuvant Trastuzumab

OBJECTIVES

Although intratumoral heterogeneity of human epidermal growth factor receptor 2 (HER2) gene amplification has been associated with a poor prognosis for primary HER2-positive breast cancer and metastatic HER2-positive breast cancer treated with trastuzumab, the clinicopathologic significance in a setting involving trastuzumab treatment as an adjuvant treatment has not been studied in patients.

METHODS

We retrospectively investigated 443 patients with HER2-positive breast cancer treated with surgery, adjuvant chemotherapy, and 1 year of trastuzumab. Three areas that showed different levels of HER2 protein expression were chosen, and silver in situ hybridization was performed.

RESULTS

HER2 regional and genetic heterogeneity was found in 6.2% and 6.8% of tumors, respectively. Both types of heterogeneity were significantly associated with hormone receptor positivity, HER2 immunohistochemistry score of 2+, a low level of HER2 gene amplification, and absence of an extensive intraductal component. Genetic heterogeneity also showed strong correlation with a lower histologic grade. In the hormone receptor-positive group, the regional heterogeneity affected disease-free survival of patients (hazard ratio, 4.869; 95% confidence interval, 1.424-16.646; P = .005), whereas genetic heterogeneity did not.

CONCLUSIONS

Evaluation of intratumoral heterogeneity, especially in cases with hormone receptor positivity, may be valuable for assessing the prognosis of HER2-positive patients anticipating treatment with adjuvant systemic therapy and trastuzumab.

In situ single-cell analysis identifies heterogeneity for PIK3CA mutation and HER2 amplification in HER2-positive breast cancer

Detection of minor, genetically distinct subpopulations within tumors is a key challenge in cancer genomics. Here we report STAR-FISH (specific-to-allele PCR-FISH), a novel method for the combined detection of single-nucleotide and copy number alterations in single cells in intact archived tissues. Using this method, we assessed the clinical impact of changes in the frequency and topology of PIK3CA mutation and HER2 (ERBB2) amplification within HER2-positive breast cancer during neoadjuvant therapy. We found that these two genetic events are not always present in the same cells. Chemotherapy selects for PIK3CA-mutant cells, a minor subpopulation in nearly all treatment-naive samples, and modulates genetic diversity within tumors. Treatment-associated changes in the spatial distribution of cellular genetic diversity correlated with poor long-term outcome following adjuvant therapy with trastuzumab. Our findings support the use of in situ single cell-based methods in cancer genomics and imply that chemotherapy before HER2-targeted therapy may promote treatment resistance.

Detecting intratumoral heterogeneity in routine breast-HER2 testing: low yield of testing multiple blocks

BACKGROUND

Intratumoral heterogeneity can lead to uncertainty in breast carcinoma HER2 testing, both with respect to pathology reporting and clinical significance. The standard practice is to perform breast biomarker testing on a single representative section of tumor; however, concern over heterogeneity often leads to testing on additional tissue blocks. Our objective was to assess the diagnostic yield of testing multiple blocks of a single invasive breast carcinoma.

METHODS

We performed a retrospective review of 139 consecutive cases (between 2006 and 2012) in which clinical HER2 testing was performed in multiple blocks. Tumor characteristics and HER2 studies (both immunohistochemistry and data from in situ hybridization) were reviewed. Regional differences in morphology and HER2 immunoreactivity were recorded. In situ hybridization was performed in 25 of 139 of the cases; patterns of genetic heterogeneity were reviewed. We audited discordances in HER2 result between blocks.

RESULTS

Testing of multiple blocks yielded no additional HER2 information in 134 (96.4%) of 139 cases. Morphologic differences or heterogeneity in HER2 expression was observed in 22 (15.8%) of 139 of cases. Only 5 of these showed differences in HER2 between blocks, of which 4 were associated with equivocal HER2 immunohistochemistry, and 4 were high-grade.

CONCLUSIONS

In the vast majority of cases, even those with heterogeneity, testing of a single block is sufficient for an accurate HER2 determination. High-grade tumors with equivocal HER2 status and observable heterogeneity are more likely to yield a different result on testing of additional blocks.

High-density SNP arrays improve detection of HER2 amplification and polyploidy in breast tumors

BACKGROUND

Human epidermal growth factor receptor-2 (HER2) overexpression and gene amplification are currently established by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH), respectively. This study investigates whether high-density single nucleotide polymorphism (SNP) arrays can provide additional diagnostic power to assess HER2 gene status.

METHODS

DNA from 65 breast tumor samples previously diagnosed by HER2 IHC and FISH analysis were blinded and examined for HER2 copy number variation employing SNP array analysis.

RESULTS

SNP array analysis identified 24 (37%) samples with selective amplification or imbalance of the HER2 region in the q-arm of chromosome 17. In contrast, only 15 (23%) tumors were found to have HER2 amplification by IHC and FISH analysis. In total, there was a discrepancy in 19 (29%) samples between SNP array and IHC/FISH analysis. In 12 of these cases, the discrepancy towards FISH could be attributed to concomitant amplification or deletion of the centromeric region, which harbors the FISH reference probe sequence. In 3 tumors, repeated IHC/FISH analysis revealed that the original IHC/FISH analysis had failed to indicate the correct HER2 expression level. Finally, the SNP array analysis revealed that more than two thirds of the samples exhibited polyploidy that was unrecognized by conventional FISH.

CONCLUSIONS

Collectively, the data show that determination of HER2 copy number variations by SNP array-based genomic segmentation analysis is an effective supplement to IHC/FISH HER2 analysis that, by providing additional diagnostic sensitivity and accuracy, may elect more women for targeted treatment with HER2 inhibitors.

[Use of the new 2013 ASCO/CAP guidelines to study HERS status by fluorescence in situ hybridization in patients with breast cancer]

Despite the long-term history of HER2 testing in breast cancer (BC), the results of its study are frequently interpreted ambiguously. The introduction of the new 2013 ASCO/CAP guidelines is aimed to further optimize HERS testing in view of new scientific evidence for the biological characteristics of BC.

OBJECTIVE

to study the results of assessing HERS2 status in patients with the questionable level of protein expression according to the 2007 versus 2013 ASCO/CAP criteria.

SUBJECTS AND METHODS

Biopsy specimens from 572 patients diagnosed with BC after immunohistochemical examination, including HER2 status assessment, were investigated by fluorescence in situ hybridization.

RESULTS

The use of the new 2013 ASCO/CAP criteria versus the previous criteria to determine intratumor heterogeneity, HER2 gene copy number, and the so-called chromosome 17 polysomy was ascertained to cause a statistically significant increase in HER2-positive cases from 25 to 42.5% (OR=2.2178; 95% CI, 1.8254-2.6950; р=0.0005).

CONCLUSION

The use of the new guidelines additionally permits effective therapy in patients with BC, which may be another step to improve survival in this large patient group.

HER2 heterogeneity affects trastuzumab responses and survival in patients with HER2-positive metastatic breast cancer

OBJECTIVES

Heterogeneity of HER2 gene amplification is found in a subset of breast cancers. We investigated the impact of HER2 heterogeneity on trastuzumab responses and clinical outcomes in 112 patients with HER2-positive metastatic breast cancer.

METHODS

Regional and genetic heterogeneity of HER2 gene amplification was determined in three different areas of each tumor by immunohistochemistry and silver in situ hybridization. We also assessed the overall levels of HER2 amplification and the proportion of tumor cells with a HER2/CEP17 ratio of more than 2.2 or strong and complete membranous (3+) expression of HER2 protein.

RESULTS

HER2 regional and genetic heterogeneity based on the HER2/CEP17 ratio was confirmed in 8.7% and 2.7% of cases, respectively. Poor response to trastuzumab was associated with overall low-level or equivocal amplification, HER2 regional heterogeneity by the HER2/CEP17 ratio, the HER2/CEP17 ratio of more than 2.2 in less than 80% of tumor cells, and HER2 immunohistochemical expression of 3+ in less than 75% of tumor cells. In survival analyses, low-level or equivocal HER2 amplification, HER2 regional heterogeneity based on the HER2/CEP17 ratio, and the HER2/CEP17 ratio of more than 2.2 in less than 80% of tumor cells were associated with shorter time to progression and lower overall survival in univariate and multivariate analyses.

CONCLUSIONS

These results suggest that accurate assessment of HER2 status, including HER2 heterogeneity, is important in predicting trastuzumab responses and outcomes in patients with HER2-positive metastatic breast cancer.

Intratumoral heterogeneity of HER2 protein and amplification of HER2 gene in salivary duct carcinoma

Salivary duct carcinoma (SDC) is an aggressive adenocarcinoma of the salivary glands, and accounts for 1-3% of all malignant salivary gland tumors, resembling morphologically invasive ductal carcinoma (IDC) of the breast. In contrast to IDC of the breast and gastric carcinoma (GC), the study of human epidermal growth factor receptor 2 (HER2) in SDC has not progressed. Therefore, we investigated the relationship between HER2 protein expression and amplification of the HER2 gene, and compared them in terms of intratumoral heterogeneity (ITH) in 13 cases of SDC using immunohistochemistry and dual color in situ hybridization. We found seven cases with protein overexpression (53.8%) and five cases with gene amplification (38.5%) in accordance with ASCO/CAP guidelines. ITH of HER2 protein expression was seen in seven cases (53.8%). Interestingly, the ratio of the HER2 gene showed homogenous distribution with or without the presence of ITH of HER2 protein expression. SDC tends to have more ITH of HER2 protein similarly to GC, in contrast to IDC of the breast. ITH of HER2 protein in SDC has no heterogeneity of the HER2 gene amplification. The mechanism of HER2 protein expression in SDC might proceed through a more complex pathway relative to that of IDC of the breast.

Intratumoral heterogeneity impacts the response to anti-neu antibody therapy

BACKGROUND

Along with de novo resistance, continued exposure to trastuzumab, an anti-human epidermal growth factor receptor 2 (HER2/neu) antibody, can lead to acquired resistance. In this study, we characterize a new anti-HER2/neu antibody resistant and metastatic mouse breast carcinoma cell line, TUBO-P2J. This cell line was developed during in vivo experiments using the antibody sensitive and non-metastatic tumor line TUBO. In addition, TUBO-P2J was used to establish an intratumoral HER2 heterogenous animal tumor model to evaluate the therapeutic effects of anti-HER2/neu antibody.

METHODS

After establishing the cell line, TUBO-P2J was characterized regarding its susceptibility to anti-neu antibody and chemotherapeutics, as well as its metastatic potential in vitro and in vivo. In addition, expression profiles of metastasis related genes were also evaluated. A clinically relevant intratumoral HER2 heterogenous tumor model was established by inoculating mice with tumor cells consisting of TUBO and TUBO-P2J at a ratio of 1,000:1 or 10,000:1. Tumor growth and mouse survival were used to evaluate the therapeutic effects of anti-neu antibody.

RESULTS

The TUBO-P2J cell line is a HER2/neu negative and highly metastatic variant of TUBO. This cell line was resistant to anti-neu antibody therapy, and when inoculated subcutaneously, metastasized to the lungs within 14 days. Compared to the parental TUBO cell line, TUBO-P2J displayed an epithelial-mesenchymal transition (EMT) related gene expression profile including: the loss of E-cadherin, and increased Vimentin, Snail, and Twist1 expression. In addition, TUBO-P2J exhibited increased invasion and migration activity, and was resistant to chemotherapy drugs. Finally, mixed tumor implantations experiments revealed that an increased percentage of TUBO-P2J rendered tumors less responsive to anti-neu antibody therapy.

CONCLUSION

This study describes a novel model of intratumoral heterogenous metastatic breast cancer in immune competent mice that can be used to develop novel or combined immunotherapies to overcome antibody resistance.

High-sensitivity BRAF mutation analysis: BRAF V600E is acquired early during tumor development but is heterogeneously distributed in a subset of papillary thyroid carcinomas

CONTEXT

The homogeneous distribution of BRAF V600E in papillary thyroid carcinoma (PTC) has been called into question by recent reports. These studies claim that BRAF V600E is heterogeneous and is limited to tumor cell subsets in the majority of PTCs.

OBJECTIVE

The objective of the study was to understand the allele distribution of BRAF V600E by evaluating the percentage of mutated neoplastic cells in a group of PTCs using two different highly sensitive analytical approaches: allele-specific locked nucleic acid PCR and 454 next-generation sequencing targeted to BRAF exon 15.

STUDY DESIGN

BRAF V600E was investigated using allele-specific locked nucleic acid PCR on 155 consecutive samples of PTC. Mutated cases were reanalyzed by 454 next-generation sequencing and immunohistochemistry. Because the evaluation of genetic heterogeneity in tumor samples can be profoundly biased by contamination with normal cells, all mutation frequency data were normalized to the real amount of neoplastic cells within each tumor.

RESULTS

Eighty-five of 155 PTCs (54.8%) were BRAF V600E mutated. The distribution of mutated neoplastic cells within the tumor was as follows: greater than 80% in 37 of 85 (43.5%), 30-80% in 39 of 85 (45.9%), and less than 30% in 9 of 85 (10.6%). In most of the PTCs with less than 80% BRAF V600E-positive neoplastic cells, the mutation was present in large neoplastic cell subpopulations. Tumors with less than 30% mutated neoplastic cells were smaller than tumors with a percentage of mutated cells greater than 80% or between 30% and 80% (P < .05).

CONCLUSIONS

BRAF V600E is heterogeneously distributed in some PTCs. The large BRAF V600E neoplastic cell subpopulations found in mutated cases is consistent with the view that the BRAF V600E is acquired early during PTC development.

Two histopathologically different diseases: hormone receptor-positive and hormone receptor-negative tumors in HER2-positive breast cancer

The clinical behavior of human epidermal growth factor 2 (HER2)-positive breast cancer, including pathologic complete response rate and pattern of relapse and metastasis, differs substantially according to hormone receptor (HR) status. We investigated various histopathologic features of HER2-positive breast cancer and their correlation with HR status. We retrospectively analyzed tumors of 450 HER2-positive breast cancer patients treated with chemotherapy and 1 year of trastuzumab. HR-/HER2+ tumors showed higher nuclear grade, less tubule formation, higher histologic grade, frequent apocrine features, diffuse and abundant lymphocytic infiltration, strong HER2 immunohistochemical staining (3+), higher average HER2 copy number and HER2/CEP17 ratio, the absence of HER2 genetic heterogeneity, and greater p53 expression than HR+/HER2+ tumors. An inverse correlation was observed between estrogen receptor or progesterone receptor Allred score and average HER2 copy number or HER2/CEP17 ratio. The percentage of ductal carcinoma in situ (DCIS) within the tumor was negatively correlated with ER Allred score, but positively correlated with average HER2 copy number and HER2/CEP17 ratio. Pathologic tumor size and DCIS percentage also showed a significant inverse correlation. Ratio of metastatic to total examined lymph node number was significantly correlated with average HER2 copy number and HER2/CEP17 ratio. High pT stage (hazard ratio, 2.370; p = 0.027), the presence of lymphovascular invasion (hazard ratio, 2.806; p = 0.005), and HR negativity (hazard ratio, 2.202; 1.074-4.513; p = 0.031) were found to be independent prognostic indicators of poor disease-free survival. In conclusion, HR+/HER2+ and HR-/HER2+ breast cancer showed distinct histopathologic features that may be relevant to their distinct clinical behavior.

Current status of anti-human epidermal growth factor receptor 2 therapies: predicting and overcoming herceptin resistance

Human epidermal growth factor receptor 2-overexpressing (HER2+) breast cancer occurs in 20% to 25% of cases and is associated with poor prognosis. Trastuzumab (Herceptin; Genentech, South San Francisco, CA) is a monoclonal antibody targeting the HER2 extracellular domain that has been shown to significantly reduce relapse rates. However, some patients with HER2+ tumors do not respond to Herceptin, and 60% to 85% of patients with HER2+ metastatic breast cancer acquire resistance within a short time period. In this review, we discuss proposed mechanisms of action of trastuzumab and trastuzumab resistance and various drugs that have been developed to overcome drug resistance. We introduce the basal molecular subtype as a predictor of increased risk in HER2+ breast cancer and a possible alternative cause of drug resistance.

HER2 in situ hybridization in breast cancer: clinical implications of polysomy 17 and genetic heterogeneity

Trastuzumab-containing therapy is a standard of care for patients with HER2+ breast cancer. HER2 status is routinely assigned using in situ hybridization to assess HER2 gene amplification, but interpretation of in situ hybridization results may be challenging in tumors with chromosome 17 polysomy or intratumoral genetic heterogeneity. Apparent chromosome 17 polysomy, defined by increased chromosome enumeration probe 17 (CEP17) signal number, is a common genetic aberration in breast cancer and represents an alternative mechanism for increasing HER2 copy number. Some studies have linked elevated CEP17 count ('polysomy') with adverse clinicopathologic features and HER2 overexpression, although there are numerous discrepancies in the literature. There is evidence that elevated CEP17 ('polysomy') count might account for trastuzumab response in tumors with normal HER2:CEP17 ratios. Nonetheless, recent studies establish that apparent 'polysomy' (CEP17 increase) is usually related to focal pericentromeric gains rather than true polysomy. Assigning HER2 status may also be complex where multiple cell subclones with distinct HER2 amplification characteristics coexist within the same tumor. Such genetic heterogeneity affects up to 40% of breast cancers when assessed according to a College of American Pathologists guideline, although other definitions have been proposed. Recent data have associated heterogeneity with unfavorable clinicopathologic variables and poor prognosis. Genetically heterogeneous tumors harboring HER2-amplified subclones have the potential to benefit from trastuzumab, but this has yet to be evaluated in clinical studies. In this review, we discuss the implications of apparent polysomy 17 and genetic heterogeneity for assigning HER2 status in clinical practice. Among our recommendations, we support the use of mean HER2 copy number rather than HER2:CEP17 ratio to define HER2 positivity in cases where coamplification of the centromere might mask HER2 amplification. We also highlight a need to harmonize in situ hybridization scoring methodology to support accurate HER2 status determination, particularly where there is evidence of heterogeneity.

Continuous tissue microarray based identification of cancers with homogeneous target expression for successful targeted therapy in clinical routine practice

In cancer therapy, the number of drugs targeting cells with characteristic molecular aberrations is continuously rising. However, application of these new drugs still is limited to a few tumor entities. The aim of this study was to test the concept of routinely identifying all possible cancer patients who might eventually benefit from targeted therapy. Therefore, all malignant tumors routinely submitted to our Institute of Pathology over a period of 4 months were brought into a tissue microarray format. Using "in situ" methods, tumors were analyzed for HER2, EGFR, and KIT status as examples for potential therapeutic target genes. In positive cases, target heterogeneity was excluded by analyzing all available large sections. Outside of tumor entities for which targeted drugs are already approved, the study revealed six tumors with homogeneously distributed HER2 overexpression/amplification (bladder, esophageal and colorectal) and seven tumors with homogeneous EGFR amplification (vulvar, ovarian, breast, esophageal and laryngeal, and adenocarcinoma of unknown primary). A total of 151 tumors showed KIT overexpression but none of seven sequenced cases showed KIT mutations. We furthermore report on a 69-year-old patient with homogeneously HER2-amplified metastatic colorectal cancer who is successfully treated by trastuzumab monotherapy. This study demonstrates that tissue microarray based screening for therapeutic target genes in tumors outside established indications represents a feasible approach suitable for routine application. The successful treatment of one patient with homogeneously HER2 positive metastatic colorectal cancer argues for the clinical utility of this approach at least in carefully selected, homogeneous cancers.