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.     

HER2 discordance between primary and metastatic breast cancer: Assessing the clinical impact

Background

In the setting of breast cancer relapse, treatment decisions are typically made by utilizing HER2, estrogen, and progesterone receptor expression status of the primary breast cancer. Recently, concern regarding receptor discordance has led to recommendations for rebiopsy for all cases of metastatic disease. However, whether this is an appropriate recommendation is uncertain, particularly as the clinical implications for HER2 discordance are unknown.

Methods

We performed a literature review to identify studies assessing HER2 discordance between primary and metastatic breast cancer. These studies were then reviewed for data relating to (1) impact of clinical factors on discordance rates, (2) prognostic impact of discordance, or (3) clinical outcomes from treatment alteration due to receptor discordance. Results were analyzed qualitatively.

Results

From 60 HER2 discordance studies identified, 24 contained information of interest for this review. No clear factor promoting HER2 discordance was identified. Loss of HER2 seemed to result in worse post-relapse survival and overall survival, although these data were often confounded by lack of treatment in the setting of receptor loss. Conversely, HER2 discordance was not associated with shorter DFS. Individual patients with receptor gain appear to have benefited from addition of targeted treatment, although data are limited to case reports.

Conclusion

Evidence of HER2 discordance leading to alterations in patient outcomes is limited, highlighting the need for further research in this area. Furthermore, lack of alteration in patient outcomes suggests that a more pragmatic approach to the decision to rebiopsy may be appropriate.     

Detection of HER2 amplification in circulating free DNA in patients with breast cancer

Background:

Human epidermal growth factor receptor 2 (HER2) is amplified and overexpressed in 20–25% of breast cancers. This study investigated circulating free DNA (cfDNA) for detection of HER2 gene amplification in patients with breast cancer.

Methods:

Circulating free DNA was extracted from plasma of unselected patients with primary breast cancer (22 before surgery and 68 following treatment), 30 metastatic patients and 98 female controls using the QIAamp Blood DNA Mini Kit (Qiagen). The ratio of HER2 to an unamplified reference gene (contactin-associated protein 1 (CNTNAP1)) was measured in cfDNA samples by quantitative PCR (qPCR) using SK-BR-3 cell line DNA as a positive control.

Results:

We validated the qPCR assay with DNA extracted from 23 HER2 3+ and 40 HER2-negative tumour tissue samples; the results agreed for 60 of 63 (95.2%) tumours. Amplification was detected in cfDNA for 8 of 68 patients following primary breast cancer treatment and 5 of 30 metastatic patients, but was undetected in 22 patients with primary breast cancer and 98 healthy female controls. Of the patients with amplification in cfDNA, 10 had HER2 3+ tumour status by immunohistochemistry.

Conclusions:

The results demonstrate for the first time the existence of amplified HER2 in cfDNA in the follow-up of breast cancer patients who are otherwise disease free. This approach could potentially provide a marker in patients with HER2-positive breast cancer.     

Topoisomerase II alpha amplification may predict benefit from adjuvant anthracyclines in HER2 positive early breast cancer

The purpose of the study was to evaluate the use of metabolic phenotype, described by high-resolution magic angle spinning magnetic resonance spectroscopy (HR MAS MRS), as a tool for prediction of histological grade, hormone status, and axillary lymphatic spread in breast cancer patients. Biopsies from breast cancer (n = 91) and adjacent non-involved tissue (n = 48) were excised from patients (n = 77) during surgery. HR MAS MR spectra of intact samples were acquired. Multivariate models relating spectral data to histological grade, lymphatic spread, and hormone status were designed. The multivariate methods applied were variable reduction by principal component analysis (PCA) or partial least-squares regression-uninformative variable elimination (PLS-UVE), and modelling by PLS, probabilistic neural network (PNN), or cascade correlation neural network. In the end, model verification by prediction of blind samples (n = 12) was performed. Validation of PNN training resulted in sensitivity and specificity ranging from 83 to 100% for all predictions. Verification of models by blind sample testing showed that hormone status was well predicted by both PNN and PLS (11 of 12 correct), lymphatic spread was best predicted by PLS (8 of 12), whereas PLS-UVE PNN was the best approach for predicting grade (9 of 12 correct). MR-determined metabolic phenotype may have a future role as a supplement for clinical decision-making-concerning adjuvant treatment and the adaptation to more individualised treatment protocols.     

Monosomy of chromosome 17 in breast cancer during interpretation of HER2 gene amplification

Monosomy of chromosome 17 may affect the assessment of HER2 amplification. Notably, the prevalence ranges from 1% up to 49% due to lack of consensus in recognition. We sought to investigate the impact of monosomy of chromosome 17 to interpretation of HER2 gene status. 201 breast carcinoma were reviewed for HER2 gene amplification and chromosome 17 status. FISH analysis was performed by using double probes (LSI/CEP). Absolute gene copy number was also scored per each probe. HER2 FISH test was repeated on serial tissue sections, ranging in thickness from 3 to 20 µm. Ratio was scored and subsequently corrected by monosomy after gold control test using the aCGH method to overcome false interpretation due to artefactual nuclear truncation. HER2 immunotests was performed on all cases. 26/201 cases were amplified (13%). Single signals per CEP17 were revealed in 7/201 (3.5%) cases. Five out of 7 cases appeared monosomic with aCGH (overall, 5/201, 2.5%) and evidenced single signals in >60% of nuclei after second-look on FISH when matching both techniques. Among 5, one case showed amplification with a pattern 7/1 (HER2/CEP17>2) of copies (3+ at immunotest); three cases revealed single signals per both probes (LSI/CEP=1) and one case revealed a 3:1 ratio; all last 4 cases showed 0/1+ immunoscore. We concluded that: 1) monosomy of chromosome 17 may be observed in 2.5% of breast carcinoma; 2) monosomy of chromosome 17 due to biological reasons rather than nuclear truncation was observed when using the cut-off of 60% of nuclei harboring single signals; 3) the skewing of the ratio due to single centromeric 17 probe may lead to false positive evaluation; 4) breast carcinomas showing a 3:1 ratio (HER2/CEP17) usually show negative 0/1+ immunoscore and <6 gene copy number at FISH.     

乳腺癌组织TOP2A和HER2/neu扩增与临床病理因素相关性研究

目的 拓扑异构酶Ⅱ(typeⅡtopoisomerase,TOP2A) DNA是常见的化疗疗效预测因子,HER2是与乳腺癌相关的重要的原癌基因之一.本研究探讨乳腺癌组织中人类表皮生长因子受体HER2/neu和TopoⅡ之间的关系,及其与临床病理因素之间的相关性.方法 收集广西医科大学附属肿瘤医院2010-02-01-2012-09-30手术治疗的96例乳腺浸润性导管癌标本,实时定量聚合酶链式反应(real time polymerase chainreaction,RQ-PCR)检测和评估基因扩增水平,免疫组织化学(immunohistochemistry,IHC)微阵列(n=76)检查基因扩增和蛋白质表达水平之间是否存在相互关系.结果 根据RQ-PCR或IHC微阵列取得的HER2/neu基因状态,TOP2A基因的扩增水平差异无统计学意义,P值分别为0.481和0.935.在HER2/neu(-)基因型患者中,29.1％(14/48)的患者显示出TOP2A基因水平高于第三四分位值,然而22.9％(11/48)的HER2/neu(+)基因型患者的数值处于第一四分位值(log TOP2A＜0.62),因此表明存在低水平的扩增.采用IHC以及荧光原位杂交(fluorescence in situ hybridization,FISH)方法确定具有HER2/neu-基因型的60例患者中,22.9％(11/48)的患者在IHC微阵列上被归类为TOP2A(+)基因型患者.同时,采用IHC以及FISH法将患者视为HER2/neu(+)基因型患者的14例患者中,大多数患者(n=10)被归类为TOP2A(+)基因型患者.结论 乳腺癌组织中TOP2A基因的扩增并不局限于带有HER2/neu(+)基因型的患者,并且很大比例的HER2/neu(-)基因型患者表现出具有高水平的TOP2A基因.     

c-myc amplification is a better prognostic factor than HER2/neu amplification in primary breast cancer.

Amplification of the c-myc and HER2/neu genes was found in 20 and 23%, respectively, of primary breast cancer tissues derived from 282 patients (median follow-up, 74 months). c-myc amplification was observed more frequently in larger tumors (P = 0.01) and in lymph node-positive patients (P = 0.01) but was not associated with age, menopausal status, or with differentiation grade or steroid receptor status. c-myc amplification was strongly negatively correlated with HER2/neu amplification (P less than 0.001). In univariate analysis, amplification of c-myc proved to be a significant predictor of reduced relapse-free and overall survival (for both, P less than 0.001). In multivariate analysis for relapse-free survival, c-myc amplification significantly (P = 0.001) added to the prognostic power of tumor size (P less than 0.001), lymph node status (P less than 0.001), and estrogen receptor status (P = 0.003), with the highest relative failure rate (1.8) after lymph node status (2.2). In this pilot study, c-myc amplification was predictive for outcome, especially among patients with node-negative disease or steroid receptor-positive tumors; 51 and 46% differences in actuarial 5-year recurrence rates when compared to patients with tumors with normal c-myc gene copy numbers, respectively. HER2/neu amplification was not associated with relapse-free survival but weakly with shorter overall survival in univariate analysis (P = 0.035). Only in the relatively small subgroup of steroid receptor-negative tumors, HER2/neu amplification may identify those patients with an increased risk of death. In conclusion, amplification of c-myc is an independent powerful prognosticator, particularly in node-negative and steroid receptor-positive breast cancer, whereas HER2/neu amplification may be of limited prognostic value, only in steroid receptor-negative disease.     

Dual HER2-targeted approaches in HER2-positive breast cancer

Approximately 15–20% of all breast cancers are human epidermal growth factor receptor 2 (HER2) positive, with clinical studies having validated the HER2 receptor tyrosine kinase pathway as an important therapeutic target. Presently, two HER2-targeted therapies are approved by the Food and Drug Administration for treatment of HER2-positive breast cancer: the HER2-targeted humanized monoclonal antibody trastuzumab and the small-molecule tyrosine kinase inhibitor lapatinib. Despite use of these HER2-targeted agents, many patients still experience disease progression. For this reason, numerous new agents and therapeutic strategies are under investigation. Based on preclinical data suggesting synergistic effects from dual therapy targeting HER2, clinical trials that test the effects of combining anti-HER2 agents have been conducted and are ongoing. Here, we review recently presented data from several clinical trials, which indicate that the strategy of combining HER2 blockade therapies can offer greater clinical efficacy, with adverse effects of varying degrees. Specifically, we review new data reported at the 2010 San Antonio Breast Cancer Symposium (SABCS 2010), including the phase II NeoSphere and phase III NeoALTTO clinical trials, and data from three clinical trials reported at the 2011 American Society of Clinical Oncology (ASCO 2011) meeting. Together these trials elucidate the potential role of combining trastuzumab with lapatinib or pertuzumab. We also discuss additional ongoing studies that will help further define the role of dual HER2 blockade therapies and its impact on clinical practice.     

Droplet digital PCR using HER2/EIF2C1 ratio for detection of HER2 amplification in breast cancer tissues

Breast cancers with amplification and overexpression of human epithelial growth factor receptor 2 (HER2) are associated with poor prognosis, and targeted for anti-HER2 therapy. Immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) are currently the recommended methods to asses HER2 overexpression/amplification. Droplet digital PCR (ddPCR), a highly accurate method to quantify DNA copy number, is potentially a robust alternative for HER2 diagnostics. In the FISH assay and most of previous ddPCR reports, chromosome 17 centromere (CEP17) has been used as the reference control to determine HER2/CEP17 ratio. Nevertheless, miss-classification could occur when HER2 is co-amplified with CEP17. To avoid this inherent defect, in the present study, we employed ddPCR assay using the human eukaryotic translation initiation factor 2C1 (EIF2C1) gene located at chromosome 1p34.3 as the reference control to quantify HER2 copy number in 31 frozen breast cancer tissues. HER2 status of these samples had been determined by FISH and classified as HER2-amplified and HER2-non-amplified breast cancers. The results showed that HER2 determined by ddPCR using HER2/EIF2C1 ratio was in good concordance with HER2 determined by FISH using HER2/CEP17 ratio, the concordance rate 87.1% (27/31), Kappa? =?0.719. The sensitivity and specificity of ddPCR assay was 90% (9/10) and 85.7% (18/21), respectively. The median HER2/EIF2C1 copy number ratio in HER2-amplified cancers (6.55, range 1.3–17.3) was significantly higher than in HER2-non-amplified cancers (1.05, range 0.6–3.6, p?<?0.001). This study demonstrated that ddPCR using HER2/EIF2C1 ratio could accurately assess HER2 status in frozen breast cancer tissues. Thus, our findings warrant further studies into breast cancer with HER2-equivocal by IHC/FISH.     

HER2 overexpressing metastatic breast cancer

Opinion statement More than 40,000 women in the United States die each year from metastatic breast cancer. Elucidation of HER2 and its role in malignant transformation has helped define a subset of aggressive breast cancer that may be relatively resistant to non-anthracycline-based therapies and hormonal agents, but responds to targeted molecular therapy. Trastuzumab, an antibody against HER2, has proven effective as single agent therapy in women with HER2 overexpressed metastatic breast cancer. Moreover, in combination with chemotherapy, trastuzumab has been shown to delay disease progression and improve overall survival for women with HER2-positive advanced breast cancer. The combination of chemotherapy and trastuzumab is emerging as a standard of care in women with HER2 overexpressed metastatic breast cancer. Several combination regimens using trastuzumab with taxanes, vinca alkaloids, or platinum compounds have demonstrated efficacy in first- and second-line treatment settings. However, the development of anthracycline-based combinations has been limited by concerns of related cardiotoxicity. Newer multi-agent regimens are in development. The optimal combination, duration, and sequence of trastuzumab therapy remain unknown in patients with HER2-positive metastatic disease. The role of continuing treatment after disease progression is also unclear. Evidence from some retrospective analyses suggest HER2-positive tumors are relatively resistant to tamoxifen and perhaps more responsive to aromatase inhibitors, although such data are inconclusive. HER2 status should not be used routinely for clinical decision making regarding hormonal therapy options. Several ongoing trials are attempting to address these and other issues related to HER2 testing to select the most appropriate candidates for these emerging therapies. While many questions remain, the treatment of HER2 overexpressing metastatic breast cancer is rapidly evolving, and represents a new approach to treatment in oncology.     

HER2 mutation status in Japanese HER2-positive breast cancer patients

Background

Human epidermal growth factor receptor 2 (HER2) gene amplification/overexpression is a major therapeutic target in breast cancer, and has been introduced as a predictive biomarker to identify patients who may benefit from therapy with anti-HER2 agents. HER2 somatic mutations have been reported, and these may influence the effect of HER2-targeted drugs.

Methods

Here, we sought HER2 mutations in a group of 135 Japanese breast cancer patients with HER2-positive tumors. We analyzed HER2 mutations by direct Sanger sequencing of two major areas, the extracellular domain at position 309–310 and the kinase domain between 755 and 781.

Results

Two patients with the HER2 somatic mutation S310F in the extracellular domain were found in this series. One patient with the S310F mutation had a node-negative invasive ductal carcinoma classified as HER2 2+ by the HercepTest and fluorescence in situ hybridization (FISH) positive, and which was estrogen receptor (ER)-negative and progesterone receptor (PgR)-negative. Another patient with the S310F mutation had an apocrine carcinoma with seven lymph nodes positive for metastasis, classified as HER2 3+ by the HercepTest, but which was FISH-negative, as well as ER-negative and PgR-negative. Both patients had received adjuvant single-agent trastuzumab therapy, and had no local recurrence or distant metastasis for five and three years after surgery, respectively.

Conclusions

Our data show that HER2 mutations are rare in HER2-positive Japanese breast cancer patients. The two mutations found in this study were identical, S310F. We suggest that in vitro experiments to determine whether the S310F mutation could be involved in resistance to anti-HER2 drugs are worthwhile in future.

     

Prognostic utility of fluorescence in situ hybridization for determining HER2 gene amplification in breast cancer

An accurate investigation of the HER2 proto-oncogene is extremely important for the therapy and prognostication of breast cancer. Currently, immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) are standard methods for this purpose. The aim of this study was to detect the expression and amplification of HER2 in paraffin-embedded samples of breast cancer tissue and to investigate the relationship between HER2 amplification and various clinicopathological parameters in advanced breast cancers. We used FISH to examine the HER2 gene amplification and IHC to examine the expression of HER2 protein, estrogen receptor (ER) and progesterone receptor (PR) in 62 advanced breast cancers. HER2 gene amplification was detected by FISH in 12 breast cancers (19%) and HER2 protein expression with a score of 3+ was detected by IHC in 11 (17%). There was a significant correlation between the HER2 gene amplification and HER2 protein overexpression in breast cancers (P<0.0001). However, some mismatching was evident: 3 cases, negative for the HER2 gene, showed a HER2 protein expression score of 3+ and 2 cases, positive for HER2 gene amplification, had HER2 protein expression scores of 0 and 1+ (negative), respectively. ER and PR were expressed in 41 (66%) and 46 (74%) cancers, respectively. No correlation was observed between the HER2 gene amplification and any of the clinicopathological parameters examined, including age, histopathological type, TNM stage, tumor size, lymph node status, relapse and expression of PR. We observed three patterns among the 6 deceased cases: i) triple negativity for HER2, ER and PR, ii) positivity for HER2 gene amplification with a mismatching HER2 protein expression, and iii) positivity for the HER2 gene amplification with a matching HER2 protein expression score of 2+ or 3+. The triple negative cases and HER2 gene amplification positive cases with a mismatching HER2 protein expression had a poor outcome. These results suggest that in breast cancer, the detection of HER2 gene amplification by FISH is desirable compared with the HER2 protein expression determined by IHC. Moreover, triple negativity for HER2, ER and PR is a potentially very important prognostic marker.     

HER2-positive breast cancer: from trastuzumab to innovatory anti-HER2 strategies

Overexpression of HER2 is encountered in approximately 20% of invasive breast cancers. It is an independent adverse prognostic factor and, more importantly, it is currently the best predictive factor for the activity of trastuzumab, an anti-HER2 monoclonal antibody (MoAb), which has revolutionized the treatment of this breast cancer subgroup. Increasing knowledge of molecular pathways involving the HER family of growth factor receptors has paved the way toward new efficient targeted therapies. Herein, we will review the targeted therapies of clinical importance for HER2-positive breast cancer, which include anti-HER2 MoAbs and tyrosine kinase inhibitors that directly interfere at the receptor level. Clinicians are still facing many uncertainties concerning the optimal use of these new agents, and scientists are working on dissecting the mechanisms of resistance developed by HER2-positive cancer cells. Interesting perspectives in the treatment of HER2-positive breast cancer will be discussed. They consist of designing HER2 peptide-based vaccines, targeting downstream pathway molecules beyond the membrane receptor, and exploring synergistic antineoplasic strategies.     

HER2-positive advanced breast cancer

It is important when treating a patient who has advanced breast cancer to establish the biologic characteristics of the tumor. In addition to knowing the hormone receptor status (estrogen and progesterone), human epidermal receptor 2 (HER2) should be evaluated. The measurement of this parameter is essential to optimizing the systemic management. This article reviews the biology of HER2, testing for HER2, clinical studies evaluating HER2-based therapies, side effects (specifically cardiotoxicity), and strategies for HER2-based therapies.