Identification of a subpopulation of metastatic breast cancer patients with very high HER2 expression levels and possible resistance to trastuzumab

Prognostic impact of HER2 biomarker levels in trastuzumab-treated early HER2-positive breast cancer

BACKGROUND

Overexpression of human epidermal growth factor receptor 2 (HER2) caused by HER2 gene amplification is a driver in breast cancer tumorigenesis. We aimed to investigate the prognostic significance of manual scoring and digital image analysis (DIA) algorithm assessment of HER2 copy numbers and HER2/CEP17 ratios, along with ERBB2 mRNA levels among early-stage HER2-positive breast cancer patients treated with trastuzumab.

METHODS

This retrospective study comprised 371 early HER2-positive breast cancer patients treated with adjuvant trastuzumab, with HER2 re-testing performed on whole tumor sections. Digitized tumor tissue slides were manually scored and assessed with uPath HER2 Dual ISH image analysis, breast algorithm. Targeted ERBB2 mRNA levels were assessed by the Xpert® Breast Cancer STRAT4 Assay. HER2 copy number and HER2/CEP17 ratio from in situ hybridization assessment, along with ERBB2 mRNA levels, were explored in relation to recurrence-free survival (RFS).

RESULTS

The analysis showed that patients with tumors with the highest and lowest manually counted HER2 copy number levels had worse RFS than those with intermediate levels (HR = 2.7, CI 1.4-5.3, p = 0.003 and HR = 2.1, CI 1.1-3.9, p = 0.03, respectively). A similar trend was observed for HER2/CEP17 ratio, and the DIA algorithm confirmed the results. Moreover, patients with tumors with the highest and the lowest values of ERBB2 mRNA had a significantly worse prognosis (HR = 2.7, CI 1.4-5.1, p = 0.003 and HR = 2.8, CI 1.4-5.5, p = 0.004, respectively) compared to those with intermediate levels.

CONCLUSIONS

Our findings suggest that the association between any of the three HER2 biomarkers and RFS was nonlinear. Patients with tumors with the highest levels of HER2 gene amplification or ERBB2 mRNA were associated with a worse prognosis than those with intermediate levels, which is of importance to investigate in future clinical trials studying HER2-targeted therapy.

Recapitulating the Lateral Organization of Membrane Receptors at the Nanoscale

Many cell membrane functions emerge from the lateral presentation of membrane receptors. The link between the nanoscale organization of the receptors and ligand binding remains, however, mostly unclear. In this work, we applied surface molecular imprinting and utilized the phase behavior of lipid bilayers to create platforms that recapitulate the lateral organization of membrane receptors at the nanoscale. We used liposomes decorated with amphiphilic boronic acids that commonly serve as synthetic saccharide receptors and generated three lateral modes of receptor presentation─random distribution, nanoclustering, and receptor crowding─and studied their interaction with saccharides. In comparison to liposomes with randomly dispersed receptors, surface-imprinted liposomes resulted in more than a 5-fold increase in avidity. Quantifying the binding affinity and cooperativity proved that the boost was mediated by the formation of the nanoclusters rather than a local increase in the receptor concentration. In contrast, receptor crowding, despite the presence of increased local receptor concentrations, prevented multivalent oligosaccharide binding due to steric effects. The findings demonstrate the significance of nanometric aspects of receptor presentation and generation of multivalent ligands including artificial lectins for the sensitive and specific detection of glycans.

Current challenges and unmet needs in treating patients with human epidermal growth factor receptor 2-positive advanced breast cancer

Human epidermal growth factor receptor 2 oncogene (HER2-positive) overexpression/amplification occurs in less than 20% of breast cancers and has traditionally been associated with poor prognosis. Development of therapies that target HER2 has significantly improved outcomes for patients with HER2-positive advanced breast cancer (ABC). Currently available HER2-targeted agents include the monoclonal antibodies trastuzumab, pertuzumab, and margetuximab, the small-molecule inhibitors lapatinib, tucatinib, neratinib, and pyrotinib, as well as the antibody-drug conjugates trastuzumab emtansine and trastuzumab deruxtecan. Optimal sequencing of these agents in the continuum of the disease is critical to maximize treatment outcomes. The large body of clinical evidence generated over the past 2 decades aids clinicians in treatment decision-making. However, patients with HER2-positive ABC and specific disease characteristics and/or comorbidities, such as leptomeningeal disease, brain metastases, or cardiac dysfunction, are generally excluded from large randomized clinical trials, and elderly or frail patients are often underrepresented. In addition, there is great inequality in the accessibility of approved drugs across countries. This article addresses various challenging clinical situations when treating patients with HER2-positive ABC. The objective is to provide guidance to clinicians on how and when HER2-targeted therapies and additional treatments can be best implemented in routine clinical practice, on the basis of existing clinical evidence and expert opinion where needed.

The emerging role of radionuclide molecular imaging of HER2 expression in breast cancer

Targeting of human epidermal growth factor type 2 (HER2) using monoclonal antibodies, antibody-drug conjugates and tyrosine kinase inhibitors extends survival of patients with HER2-expressing metastatic breast cancer. High expression of HER2 is a predictive biomarker for such specific treatment. Accurate determination of HER2 expression level is necessary for stratification of patients to targeted therapy. Non-invasive in vivo radionuclide molecular imaging of HER2 has a potential of repetitive measurements, addressing issues of heterogeneous expression and conversion of HER2 status during disease progression or in response to therapy. Imaging probes based of several classes of targeting proteins are currently in preclinical and early clinical development. Both preclinical and clinical data suggest that the most promising are imaging agents based on small proteins, such as single domain antibodies or engineered scaffold proteins. These agents permit a very specific high-contrast imaging at the day of injection.

Higher serum PD-L1 level predicts increased overall survival with lapatinib versus trastuzumab in the CCTG MA.31 phase 3 trial

BACKGROUND

The purpose of this retrospective biomarker study of the Canadian Cancer Trials Group (CCTG) MA.31 randomized phase 3 trial (lapatinib vs trastuzumab) of HER2-positive metastatic breast cancer (MBC) was to evaluate the prognostic and predictive biomarker utility of pretreatment serum programmed death ligand 1 (PD-L1) levels.

METHODS

CCTG MA.31 accrued 652 HER2-positive patients; 387 had serum available (185 in the trastuzumab arm and 202 in the lapatinib arm). The Ella immunoassay platform (ProteinSimple, San Jose, California) was used to quantitate serum PD-L1 levels. Stepwise forward Cox multivariable analyses were performed for progression-free survival and overall survival (OS).

RESULTS

In the whole trial population, continuous pretreatment serum PD-L1 levels were not associated with OS. However, within the trastuzumab arm, a higher continuous pretreatment serum PD-L1 level was significant for shorter OS (hazard ratio [HR], 3.85; P = .04), but within the lapatinib arm, pretreatment serum PD-L1 was not associated with OS (P = .37). In the whole trial, in a multivariable analysis for OS, serum PD-L1 (median cut point) remained a significant independent covariate (HR, 2.38; P = .001). There was a significant interaction between treatment arm and continuous serum PD-L1 (bootstrap method; P = .0025): at or above 214.2 pg/mL (the 89th percentile), serum PD-L1 was associated with significantly shorter OS with trastuzumab treatment versus lapatinib treatment.

CONCLUSIONS

In the CCTG MA.31 trial, serum PD-L1 was a significant predictive factor: a higher pretreatment serum PD-L1 level was associated with shorter OS with trastuzumab treatment but with longer OS with lapatinib treatment. Immune evasion may decrease the effectiveness of trastuzumab therapy. Further evaluation of elevated serum PD-L1 in advanced breast cancer is warranted to identify patients with HER2-positive MBC who may benefit from novel immune-targeted therapies in addition to trastuzumab.

Impact of 68Ga-NOTA-MAL-MZHER2 PET imaging in advanced gastric cancer patients and therapeutic response monitoring

PURPOSE

Clinical PET imaging of human epidermal growth factor receptor 2 (HER2) can noninvasively detect HER2 overexpression in lesions. A novel ⁶⁸Ga-NOTA-MAL-MZHER2 (⁶⁸Ga-HER2) affibody was developed for clinical PET/CT, and its safety, tissue dosimetry, ability to detect HER2-positive lesions, and utility for HER2-targeted therapy in patients with advanced gastric cancer (AGC) were evaluated.

METHODS

Thirty-four patients with AGC (23 with HER2-positive and 11 with HER2-negative primary lesions) were included and underwent PET/CT after an injection of approximately 3.7 MBq/kg body weight ⁶⁸Ga-HER2 affibody. Thirteen patients (8 HER2-positive and 5 HER2-negative patients) were scanned at 1, 2, and 3 h post-injection to determine the best imaging timepoint, and the remaining patients were scanned at the optimized timepoint. All patients underwent standard ¹⁸F-FDG PET/CT within 7 d to identify viable lesions. The SUV_max of lesions larger than 1.0 cm were analyzed. Five lesion maxima were analyzed for each organ.

RESULTS

(1) The ⁶⁸Ga-HER2 affibody was safe and effective, and optimal image contrast was observed 2 h post-injection; the average effective absorbed dose was 0.0215 mSv/MBq. (2) The HER2-positive group had significantly higher ⁶⁸Ga-HER2 affibody uptake than the HER2-negative group (SUV_max 10.7 ± 12.5 vs 3.8 ± 1.7, p = 0.005). The specificity and sensitivity were 100 and 55.4%, respectively, with a SUV_max cutoff value of 6.6. The SUV_max of the lesions ranged from 1.6 to 73.0, suggesting heterogeneity in HER2 expression. (3) ⁶⁸Ga-HER2 affibody uptake showed an organ-dependent difference in patients with HER2-positive expression. Bone metastases had the highest uptake (SUV_max 40.5 ± 24.9), followed by liver metastases (SUV_max 11.9 ± 3.9) and lymph node metastases (SUV_max 5.6 ± 3.7), while the uptake in other lesions, including in the primary lesion, was relatively lower (SUV_max 7.3 ± 3.7). (4) Patients receiving therapy had a non-significantly lower lesion SUV_max than patients not receiving therapy (SUV_max 8.8 ± 4.9 vs 11.8 ± 15.2) (p = 0.253). Additionally, the ⁶⁸Ga-HER2 affibody detected positive lesions in 1/11 patients with HER2-negative primary gastric cancer, which was confirmed by second generation gene sequencing. (5) Moreover, ten patients underwent baseline PET/CT followed by targeted anti-HER2 therapy. Patients with lesions showing high avidity to the ⁶⁸Ga-HER2 affibody showed longer progression-free survival (PFS) than those with lesions showing low avidity (4-9 m vs 2-3 m).

CONCLUSION

⁶⁸Ga-HER2 affibody PET/CT is a feasible method to noninvasively detect the HER2 status in AGC patients and enable early detection with a low dose. Ongoing anti-HER2 therapy did not influence ⁶⁸Ga-HER2 affibody imaging, which allowed repeated evaluations to monitor the HER2 status after anti-HER2 therapy. This method provides an in vivo understanding of AGC biology that will ultimately help oncologists improve individualized therapy plans.

Prognostic Value of Plasma HER2 Gene Copy Number in HER2-Positive Metastatic Breast Cancer Treated with First-Line Trastuzumab

Objective

Patients with HER2-positive metastatic breast cancer (MBC) benefit from trastuzumab-based therapy but eventually develop intrinsic or acquired resistance. Whether plasma HER2 gene copy number (GCN) could predict survival after trastuzumab treatment remained controversial. We evaluated the prognostic value of plasma HER2 GCN using low-coverage whole-genome sequencing (LC-WGS).

Methods

The plasma was collected from HER2-positive MBC patients whose pre-therapeutic samples were available before first-line trastuzumab-based treatment. Plasma DNA was extracted and assessed by LC-WGS for HER2 GCN. The optimal cut-off point for HER2 GCN to shorter survival was determined by receiver operating characteristic (ROC) curve analysis.

Results

A total of 49 patients were retrieved from 2013 to 2017, among whom 21 had multiple organ involvement (≥3 sites). Variations of HER2 GCN in pre-therapeutic plasma ranged from 1.89 to 23.86 (median = 2.59). ROC analysis identified the optimal cut-off point for HER2 GCN as 2.82 (P = 0.005), with 23 patients had high-level HER2 GCN and 26 in the low-level group. Both progression-free survival (PFS, P = 0.032) and overall survival (OS, P = 0.006) were adversely associated with high-level HER2 GCN. In multivariate analyses, high HER2 GCN was independently associated with shorter PFS [hazard ratio (HR) = 2.042, P = 0.037], while both high HER2 GCN (HR = 4.909, P = 0.004) and more metastatic organs (HR = 4.019, P = 0.011) were negative prognostic factors for OS.

Conclusion

In this population of patients with HER2-positive MBC, individuals with high HER2 GCNs in plasma had worse prognosis after trastuzumab-based therapy. Plasma HER2 GCN may be a prognostic marker in these patients.

HER2 amplification level is not a prognostic factor for HER2-positive breast cancer with trastuzumab-based adjuvant treatment: a systematic review and meta-analysis

Background

Trastuzumab-based therapy is a standard, targeted treatment for HER2-positive breast cancer in the adjuvant setting. However, patients do not benefit equally from it and the association between HER2 amplification level and patients' survival remains controversial. A systematic review and meta-analysis was conducted by incorporating all available evidence to evaluate the association between disease free survival (DFS) and HER2 amplification level.

Results

Three cohort studies involving 1360 HER2-positive breast cancer patients stratified by HER2 amplification magnitude were eligible for meta-analysis. The combined HRs for DFS were 1.05 (95% CI: 0.80−1.36, p = 0.74) and 0.97 (95% CI: 0.73−1.29, p = 0.83) for HER2 gene copy number (GCN) and HER2/CEP 17 ratio. No evidence of heterogeneity or public bias was found.

Methods

Databases including PubMed, Embase, Web of Science, and Cochrane Central Register of Controlled Trials (CENTRAL), were searched for eligible literature. HER2 amplification level was evaluated by fluorescence in situ hybridization (FISH) in terms of gene copy number (GCN) and HER2/CEP17 ratio. Hazard ratios (HRs) for DFS with 95% confidence interval (CI) according to the amplification level of HER2 were extracted. The outcomes were synthesized based on a fixed-effects model.

Conclusions

HER2 amplification level is not a prognostic factor for HER2-positive breast cancer with trastuzumab-based targeted therapy in the clinical adjuvant setting.

HER2/CEP17 Ratios and Clinical Outcome in HER2-Positive Early Breast Cancer Undergoing Trastuzumab-Containing Therapy

Background

Adjuvant therapy comprising the HER2 receptor antagonist trastuzumab is associated with a significant improvement in disease-free and overall survival as compared to chemotherapy alone in localized HER2-positive breast cancer (BC). However, a subset of HER2-positive tumors seems to respond less favorably to trastuzumab. Various mechanisms have been proposed for trastuzumab resistance, such as high HER2 to Chromosome 17 FISH (HER2/CEP17) ratios and the possibility that single agent trastuzumab may not suffice to efficiently block HER2 downstream signaling thresholds. In a retrospective analysis we evaluated whether HER2/CEP17 ratios might have an impact on disease-free survival (DFS).

Methods

Clinical records of Stage I-III BC patients with HER2-positive tumors were reviewed at our institution from 2007–2013. We analyzed demographics, tumor characteristics including tumor size and grade, lymph node involvement and estrogen receptor expression as well as treatment with respect to chemotherapeutic regimens from the clinical charts. HER2/CEP17 ratios were determined by routine pathology analysis using in situ fluorescent hybridization (FISH). Upon statistical preview we defined three groups of HER2 amplification based on FISH ratio (2.2 to 4, >4 to 8, >8), in order to evaluate an association between HER2 gene amplification and DFS with trastuzumab containing therapies. DFS was analyzed using Cox-regression.

Results

A total of 332 patients with HER2-positive BC were reviewed. Median age was 54 (range 23–89) years. The majority of tumors were classified T1 (50%) or T2 (39%), node negative (52%) and of high grade G3 histology (70%). We identified 312 (94%) tumors as immunohistochemistry (IHC) score 3+ and HER2/CEP17 ratios were available from 278 patients (84%). 30% (N = 84) had tumors with high HER2/CEP17 ratios (>8). Univariate analysis found no correlation between outcome, age, histological grade, sequence as well as anthracycline content of chemotherapy. However, a prognostic impact was detected for tumor size (p = 0.02), nodal status (p<0.01), proliferation index (p<0.01), level (≥20%) of estrogen receptor expression (p = 0.03) and neoadjuvant therapeutic setting (p = 0.03), respectively. Importantly, univariate and multivariable analysis revealed that standard trastuzumab containing chemotherapy resulted in impaired disease free survival among tumors with FISH ratio >8 (p<0.01). Although less pronounced, a similar association was found also with respect to high HER2 gene copy numbers (>12) and DFS (p = 0.01).

Conclusions

In early BC patients, tumors with high HER2 amplification ratios (>8), may less likely respond to standard trastuzumab-containing therapies. Although, we obtained a similar effect for high HER2 gene copy numbers, this provides only an indirect speculation and not a proof that high HER2/CEP17 ratios may induce HER2 resistance.

Estrogen receptor alpha gene amplification in breast cancer: 25 years of debate

Twenty-five years ago, Nembrot and colleagues reported amplification of the estrogen receptor alpha gene (ESR1) in breast cancer, initiating a broad and still ongoing scientific debate on the prevalence and clinical significance of this genetic aberration, which affects one of the most important genes in breast cancer. Since then, a multitude of studies on this topic has been published, covering a wide range of divergent results and arguments. The reported prevalence of this alteration in breast cancer ranges from 0% to 75%, suggesting that ESR1 copy number analysis is hampered by technical and interpreter issues. To date, two major issues related to ESR1 amplification remain to be conclusively addressed: (1) The extent to which abundant amounts of messenger RNA can mimic amplification in standard fluorescence in situ hybridization assays in the analysis of strongly expressed genes like ESR1, and (2) the clinical relevance of ESR1 amplification: Such relevance is strongly disputed, with data showing predictive value for response as well as for resistance of the cancer to anti-estrogen therapies, or for subsequent development of cancers in the case of precursor lesions that display amplification of ESR1. This review provides a comprehensive summary of the various views on ESR1 amplification, and highlights explanations for the contradictions and conflicting data that could inform future ESR1 research.

Anti-HER2 Therapy Beyond Second-Line for HER2-Positive Metastatic Breast Cancer: A Short Review and Recommendations for Several Clinical Scenarios from a Spanish Expert Panel

BACKGROUND

The aim of this project was to provide an expert opinion regarding anti-human epidermal growth factor receptor 2 (HER2) therapy beyond second-line treatment of metastatic breast cancer (mBC).

METHODS

A group of experts discussed specific issues concerning anti-HER2 therapy in late-line settings in mBC.

RESULTS

Trastuzumab emtansine (T-DM1) or dual HER2 blockade appeared to be good options for HER2-positive mBC after ≥ 2 HER2-targeted therapies. Once an objective response has been achieved with anti-HER2-containing therapy, the anti-HER2 agent can be continued until progression of the disease, unacceptable toxicity or patient decision. mBC treated with ≥ 3 consecutive lines of anti-HER therapy, ≥ 1 being a dual HER2 blockade and with early progression of disease during a fourth or later-line treatment, are clinically resistant to anti-HER therapy. For progression of metastasis in the brain after anti-HER2 therapy, lapatinib and chemotherapy appear to be a good alternative after best local treatment.

CONCLUSIONS

Further clinical trials are needed to provide valuable knowledge about the best treatment options in the later settings of mBC.

Measuring HER2-Receptor Expression In Metastatic Breast Cancer Using [68Ga]ABY-025 Affibody PET/CT

Purpose: Positron Emission Tomography (PET) imaging of HER2 expression could potentially be used to select patients for HER2-targed therapy, predict response based on uptake and be used for monitoring. In this phase I/II study the HER2-binding Affibody molecule ABY-025 was labeled with ⁶⁸Ga-gallium ([⁶⁸Ga]ABY-025) for PET to study effect of peptide mass, test-retest variability and correlation of quantified uptake in tumors to histopathology.

Experimental design: Sixteen women with known metastatic breast cancer and on-going treatment were included and underwent FDG PET/CT to identify viable metastases. After iv injection of 212±46 MBq [⁶⁸Ga]ABY-025 whole-body PET was performed at 1, 2 and 4 h. In the first 10 patients (6 with HER2-positive and 4 with HER2-negative primary tumors), [⁶⁸Ga]ABY-025 PET/CT with two different doses of injected peptide was performed one week apart. In the last six patients (5 HER2-positive and 1 HER2-negative primary tumors), repeated [⁶⁸Ga]ABY-025 PET were performed one week apart as a test-retest of uptake in individual lesions. Biopsies from 16 metastases in 12 patients were collected for verification of HER2 expression by immunohistochemistry and in-situ hybridization.

Results: Imaging 4h after injection with high peptide content discriminated HER2-positive metastases best (p<0.01). PET SUV correlated with biopsy HER2-scores (r=0.91, p<0.001). Uptake was five times higher in HER2-positive than in HER2-negative lesions with no overlap (p=0.005). The test-retest intra-class correlation was r=0.996. [⁶⁸Ga]ABY-025 PET correctly identified conversion and mixed expression of HER2 and targeted treatment was changed in 3 of the 16 patients.

Conclusion: [⁶⁸Ga]ABY-025 PET accurately quantifies whole-body HER2-receptor status in metastatic breast cancer.

HER2 testing and its predictive utility in anti-HER2 breast cancer therapy

Breast cancer treatment is dependent on accurate pathologic diagnosis. HER2 testing is now universally recommended as part of evaluation of invasive breast cancer. HER2 testing is available via various slide and non-slide based assays, and interpretation of results continues to evolve. Herein we review these testing modalities and their incorporation into the 2013 ASCO/CAP guidelines. Once accurate HER2 status has been established the proper treatment based on recent clinical trials can be instituted.

Targeting HER2 for the treatment of breast cancer

HER2 (ErbB2), a member of the HER family of tyrosine kinase receptors (HER1-4), is a major driver of tumor growth in 20% of breast cancers. Treatment with the anti-HER2 monoclonal antibody trastuzumab has revolutionized the outcome of patients with this aggressive breast cancer subtype, but intrinsic and acquired resistance is common. Growing understanding of the biology and complexity of the HER2 signaling network and of potential resistance mechanisms has guided the development of new HER2-targeted agents. Combinations of these drugs to more completely inhibit the HER receptor layer, or combining HER2-targeted agents with agents that target downstream signaling, alternative pathways, or components of the host immune system, are being vigorously investigated in the preclinical and clinical settings. As a result, the list of more effective and well tolerated FDA-approved new regimens for patients with HER2+ tumors is constantly growing.

Quantification of HER family receptors in breast cancer

The clinical success of trastuzumab in breast cancer taught us that appropriate tumor evaluation is mandatory for the correct identification of patients eligible for targeted therapies. Although HER2 protein expression by immunohistochemistry (IHC) and gene amplification by fluorescence in situ hybridization (FISH) assays are routinely used to select patients to receive trastuzumab, both assays only partially predict response to the drug. In the case of epidermal growth factor receptor (EGFR), the link between the presence of the receptor or its amplification and response to anti-EGFR therapies could not be demonstrated. Even less is known for HER3 and HER4, mainly due to lack of robust and validated assays detecting these proteins. It is becoming evident that, besides FISH and IHC, we need better assays to quantify HER receptors and categorize the patients for individualized treatments. Here, we present the current available methodologies to measure HER family receptors and discuss the clinical implications of target quantification.

Advances in the Molecular Analysis of Breast Cancer: Pathway toward Personalized Medicine

Background

Breast cancer is a heterogeneous disease that encompasses a wide range of clinical behaviors and histological and molecular variants. It is the most common type of cancer affecting women worldwide and is the second leading cause of cancer death.

Methods

A comprehensive literature search was performed to explore the advances in molecular medicine related to the diagnosis and treatment of breast cancer.

Results

During the last few decades, advances in molecular medicine have changed the landscape of cancer treatment as new molecular tests complement and, in many instances, exceed traditional methods for determining patient prognosis and response to treatment options. Personalized medicine is becoming the standard of care around the world. Developments in molecular profiling, genomic analysis, and the discovery of targeted drug therapies have significantly improved patient survival rates and quality of life.

Conclusions

This review highlights what pathologists need to know about current molecular tests for classification and prognostic/predictive assessment of breast carcinoma as well as their role as part of the medical team.

Quantitative assessment of HER2 amplification in HER2-positive breast cancer: its association with clinical outcomes

Human epidermal growth factor receptor 2 (HER2) is an effective therapeutic target in breast cancer. However, not all patients benefit from trastuzumab-based therapy. We aimed to investigate whether patients with different levels of HER2 amplification would experience different clinical outcomes with trastuzumab-based chemotherapy. We quantified the HER2 gene copy number (GCN) and HER2/centromere chromosome probe 17 (CEP17) ratio in 291 breast cancer patients with HER2 amplification confirmed by immunohistochemistry and fluorescence in situ hybridization. The optimal cutoff points for HER2 GCN and the HER2/CEP17 ratios for distinguishing positive results were determined by receiver operating characteristic (ROC) curve analyses. ROC analysis identified optimal cutoff points for HER2 GCN and HER2/CEP17 ratios as 11.5 and 6.5 (P = 0.039 and P = 0.012), respectively. The DFS in patients with HER2 GCN <11.5 was significantly longer than in HER2 GCN ≥11.5 patients (P = 0.015) according to Kaplan-Meier survival curves analysis. Similarly, patients with HER2/CEP17 ratios <6.5 had a significantly longer DFS than those with HER2/CEP17 ratios ≥6.5 (P = 0.013). Moreover, patients with HER2 cluster amplification showed a worse survival than those with HER2 non-cluster amplification (P = 0.041). This study demonstrated a significant association between the level of HER2 amplification and survival time in a relatively large cohort of HER2-positive breast cancer patients undergoing trastuzumab-based chemotherapy. Further investigations of more precise quantitative measurements and larger cohorts are required to define this threshold.

HER3, p95HER2, and HER2 protein expression levels define multiple subtypes of HER2-positive metastatic breast cancer

Trastuzumab is effective in the treatment of HER2/neu over-expressing breast cancer, but not all patients benefit from it. In vitro data suggest a role for HER3 in the initiation of signaling activity involving the AKT–mTOR pathway leading to trastuzumab insensitivity. We sought to investigate the potential of HER3 alone and in the context of p95HER2 (p95), a trastuzumab resistance marker, as biomarkers of trastuzumab escape. Using the VeraTag® assay platform, we developed a dual antibody proximity-based assay for the precise quantitation of HER3 total protein (H3T) from formalin-fixed paraffin-embedded (FFPE) breast tumors. We then measured H3T in 89 patients with metastatic breast cancer treated with trastuzumab-based therapy, and correlated the results with progression-free survival and overall survival using Kaplan–Meier and decision tree analyses that also included HER2 total (H2T) and p95 expression levels. Within the sub-population of patients that over-expressed HER2, high levels of HER3 and/or p95 protein expression were significantly associated with poor clinical outcomes on trastuzumab-based therapy. Based on quantitative H3T, p95, and H2T measurements, multiple subtypes of HER2-positive breast cancer were identified that differ in their outcome following trastuzumab therapy. These data suggest that HER3 and p95 are informative biomarkers of clinical outcomes on trastuzumab therapy, and that multiple subtypes of HER2-positive breast cancer may be defined by quantitative measurements of H3T, p95, and H2T.

Recommendations for human epidermal growth factor receptor 2 testing in breast cancer: American Society of Clinical Oncology/College of American Pathologists clinical practice guideline update

PURPOSE

To update the American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guideline recommendations for human epidermal growth factor receptor 2 (HER2) testing in breast cancer to improve the accuracy of HER2 testing and its utility as a predictive marker in invasive breast cancer.

METHODS

ASCO/CAP convened an Update Committee that included coauthors of the 2007 guideline to conduct a systematic literature review and update recommendations for optimal HER2 testing.

RESULTS

The Update Committee identified criteria and areas requiring clarification to improve the accuracy of HER2 testing by immunohistochemistry (IHC) or in situ hybridization (ISH). The guideline was reviewed and approved by both organizations.

RECOMMENDATIONS

The Update Committee recommends that HER2 status (HER2 negative or positive) be determined in all patients with invasive (early stage or recurrence) breast cancer on the basis of one or more HER2 test results (negative, equivocal, or positive). Testing criteria define HER2-positive status when (on observing within an area of tumor that amounts to >10% of contiguous and homogeneous tumor cells) there is evidence of protein overexpression (IHC) or gene amplification (HER2 copy number or HER2/CEP17 ratio by ISH based on counting at least 20 cells within the area). If results are equivocal (revised criteria), reflex testing should be performed using an alternative assay (IHC or ISH). Repeat testing should be considered if results seem discordant with other histopathologic findings. Laboratories should demonstrate high concordance with a validated HER2 test on a sufficiently large and representative set of specimens. Testing must be performed in a laboratory accredited by CAP or another accrediting entity. The Update Committee urges providers and health systems to cooperate to ensure the highest quality testing.

Recommendations for human epidermal growth factor receptor 2 testing in breast cancer: American Society of Clinical Oncology/College of American Pathologists clinical practice guideline update

PURPOSE

To update the American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guideline recommendations for human epidermal growth factor receptor 2 (HER2) testing in breast cancer to improve the accuracy of HER2 testing and its utility as a predictive marker in invasive breast cancer.

METHODS

ASCO/CAP convened an Update Committee that included coauthors of the 2007 guideline to conduct a systematic literature review and update recommendations for optimal HER2 testing.

RESULTS

The Update Committee identified criteria and areas requiring clarification to improve the accuracy of HER2 testing by immunohistochemistry (IHC) or in situ hybridization (ISH). The guideline was reviewed and approved by both organizations.

RECOMMENDATIONS

The Update Committee recommends that HER2 status (HER2 negative or positive) be determined in all patients with invasive (early stage or recurrence) breast cancer on the basis of one or more HER2 test results (negative, equivocal, or positive). Testing criteria define HER2-positive status when (on observing within an area of tumor that amounts to > 10% of contiguous and homogeneous tumor cells) there is evidence of protein overexpression (IHC) or gene amplification (HER2 copy number or HER2/CEP17 ratio by ISH based on counting at least 20 cells within the area). If results are equivocal (revised criteria), reflex testing should be performed using an alternative assay (IHC or ISH). Repeat testing should be considered if results seem discordant with other histopathologic findings. Laboratories should demonstrate high concordance with a validated HER2 test on a sufficiently large and representative set of specimens. Testing must be performed in a laboratory accredited by CAP or another accrediting entity. The Update Committee urges providers and health systems to cooperate to ensure the highest quality testing. This guideline was developed through a collaboration between the American Society of Clinical Oncology and the College of American Pathologists and has been published jointly by invitation and consent in both Journal of Clinical Oncology and the Archives of Pathology & Laboratory Medicine.

The HER2 amplicon includes several genes required for the growth and survival of HER2 positive breast cancer cells

About 20% of breast cancers are characterized by amplification and overexpression of the HER2 oncogene. Although significant progress has been achieved for treating such patients with HER2 inhibitor trastuzumab, more than half of the patients respond poorly or become resistant to the treatment. Since the HER2 amplicon at 17q12 contains multiple genes, we have systematically explored the role of the HER2 co-amplified genes in breast cancer cell growth and their relation to trastuzumab resistance. We integrated aCGH data of the HER2 amplicon from 71 HER2 positive breast tumors and 10 cell lines with systematic functional RNA interference analysis of 23 core amplicon genes with several phenotypic endpoints in a panel of trastuzumab responding and non-responding HER2 positive breast cancer cells. Silencing of HER2 caused a greater growth arrest and apoptosis in the responding compared to the non-responding cell lines, indicating that the resistant cells are inherently less dependent on the HER2 pathway. Several other genes in the amplicon also showed a more pronounced effect when silenced; indicating that expression of HER2 co-amplified genes may be needed to sustain the growth of breast cancer cells. Importantly, co-silencing of STARD3, GRB7, PSMD3 and PERLD1 together with HER2 led to an additive inhibition of cell viability as well as induced apoptosis. These studies indicate that breast cancer cells may become addicted to the amplification of several genes that reside in the HER2 amplicon. The simultaneous targeting of these genes may increase the efficacy of the anti-HER2 therapies and possibly also counteract trastuzumab resistance. The observed additive effects seem to culminate to both apoptosis and cell proliferation pathways indicating that these pathways may be interesting targets for combinatorial treatment of HER2+ breast cancers.

Advanced HER2-positive gastric cancer: current and future targeted therapies

The prognostic value of human epidermal growth factor receptor 2 (HER2) in gastric cancer is controversial. Consensus guidelines have standardized the testing of HER2 status in gastric cancer. Overexpression of this receptor occurs in approximately 20% of gastric and gastro-esophageal junction adenocarcinomas, predominantly those of the intestinal type. Recently, trastuzumab has emerged as the first targeted drug to improve overall survival when combined with chemotherapy in advanced HER2-positive gastric cancer. Primary and secondary resistance to trastuzumab has become a major problem and new strategies to overcome this resistance are needed. A high percentage of advanced HER2-positive gastric cancer patients who progress on trastuzumab therapy are candidates for second-line therapy. New families of targeted drugs, including tyrosine kinase inhibitors (TKIs) such as lapatinib and PF-00299804, mammalian target of rapamycin (mTOR) pathway inhibitors such as everolimus, heat-shock protein 90 (HSP90) inhibitors such as AUY922, HER dimerization inhibitors such as pertuzumab, and antibody-chemotherapy conjugates such as trastuzumab-emtansine (T-DM1), could offer alternative second-line treatments when trastuzumab-based first-line therapy fails.

Quantum dots-based molecular classification of breast cancer by quantitative spectroanalysis of hormone receptors and HER2

The emerging molecular breast cancer (BC) classification based on key molecules, including hormone receptors (HRs), and human epidermal growth factor receptor 2 (HER2) has been playing an important part of clinical practice guideline. The current molecular classification mainly based on their fingerprints, however, could not provide enough essential information for treatment decision making. The molecular information on both patterns and quantities could be more helpful to heterogeneities understanding for BC personalized medicine. Here we conduct quantitative determination of HRs and HER2 by quantum dots (QDs)-based quantitative spectral analysis, which had excellent consistence with traditional method. Moreover, we establish a new molecular classification system of BC by integrating the quantitative information of HER2 and HRs, which could better reveal BC heterogeneity and identify 5 molecular subtypes with different 5-year prognosis. Furthermore, the emerging 5 molecular subtypes based on simple quantitative molecules information could be as informative as multi-genes analysis in routine practice, and might help formulate a more personalized comprehensive therapy strategy and prognosis prediction.

Anti-HER agents in gastric cancer: from bench to bedside

Despite some advances in the past few years, the search for effective treatment modalities for advanced gastric and gastro-esophageal junction cancer is far from over. Available data clearly demonstrate that the development of new drugs will have little, if any, chance of success if it is not guided by in-depth knowledge of disease biology. However, using biologic agents to target key molecular pathways, such as those regulated by human epidermal growth factor receptor (HER) family members, may be effective. Indeed, the positive results achieved by the anti-HER2 agent trastuzumab in a phase III trial in HER2-positive patients support this approach. Many new anti-HER molecules are now under evaluation for the treatment of gastric and gastro-esophageal junction cancer, but so far attempts to identify reliable predictive factors from phase I and II trials have produced inconclusive results. In addition, large phase III trials are still being conducted in molecularly unselected populations. Refining patient selection is essential to maximize the benefit of targeted agents, to avoid significant toxicities and for the development of alternative therapeutic approaches in patients who have nonresponsive disease.

Analytical Validation of a Highly Quantitative, Sensitive, Accurate, and Reproducible Assay (HERmark) for the Measurement of HER2 Total Protein and HER2 Homodimers in FFPE Breast Cancer Tumor Specimens

We report here the results of the analytical validation of assays that measure HER2 total protein (H2T) and HER2 homodimer (H2D) expression in Formalin Fixed Paraffin Embedded (FFPE) breast cancer tumors as well as cell line controls. The assays are based on the VeraTag technology platform and are commercially available through a central CAP-accredited clinical reference laboratory. The accuracy of H2T measurements spans a broad dynamic range (2-3 logs) as evaluated by comparison with cross-validating technologies. The measurement of H2T expression demonstrates a sensitivity that is approximately 7–10 times greater than conventional immunohistochemistry (IHC) (HercepTest). The HERmark assay is a quantitative assay that sensitively and reproducibly measures continuous H2T and H2D protein expression levels and therefore may have the potential to stratify patients more accurately with respect to response to HER2-targeted therapies than current methods which rely on semiquantitative protein measurements (IHC) or on indirect assessments of gene amplification (FISH).