Elevated erbB-2 oncoprotein levels in preoperative and follow-up serum samples define an aggressive disease course in patients with breast cancer

Overcoming trastuzumab resistance in HER2-positive breast cancer using combination therapy

Human epidermal growth factor receptor 2 (HER2)-positive breast cancer (BC) comprises around 20-30% of all BC subtypes and is correlated with poor prognosis. For many years, trastuzumab, a monoclonal antibody, has been used to inhibit the HER2 activity. Though, the main resistance to trastuzumab has challenged the use of this drug in the management of HER2-positive BC. Therefore, the determination of resistance mechanisms and the incorporation of new agents may lead to the development of a better blockade of the HER family receptor signaling. During the last few years, some therapeutic drugs have been developed for treating patients with trastuzumab-resistant HER2-positive BC that have more effective influences in the management of this condition. In this regard, the present study aimed at reviewing the mechanisms of trastuzumab resistance and the innovative therapies that have been investigated in trastuzumab-resistant HER2-positive BC subjects.

The extracellular domain of Her2 in serum as a biomarker of breast cancer

Breast cancer is a major health problem worldwide. In ~15% of breast cancers, the epidermal growth factor receptor HER2, a transmembrane protein, is overexpressed. This HER2 overexpression is associated with an aggressive form of the disease and a poor clinical prognosis. The extracellular domain (ECD) of HER2 is released into the blood by a proteolytic mechanism known as "ECD shedding". This proteolytic shedding leaves a constitutively active truncated receptor in the membrane that is 10-100-fold more oncogenic than the full-length receptor and promotes the growth and survival of cancer cells. Shedding of the HER2 ECD is increased during metastasis: whereas 15% of primary breast cancer patients have elevated levels of serum HER2 ECD (sHER2 ECD), the levels reach 45% in patients with metastatic disease. Thus, sHER2 ECD has been proposed as a promising biomarker for cancer recurrence and for monitoring the disease status of patients overexpressing HER2. Nevertheless, in 2016, the American Society of Clinical Oncology advises clinicians not to use soluble HER2 levels to guide their choice of adjuvant therapy for patients with HER2-positive breast cancer, because the evidence was considered not strong enough. Currently, biomarkers such as carcinoembryonic antigen and cancer antigen 15-3 are widely used to monitor metastatic breast cancer disease even if the level of evidence of clinical impact of this monitoring is poor. In this article, we review the evidence that sHER2 ECD might be used in some situations as a biomarker for breast cancer. Although this serum biomarker will not replace the direct measurement of tumor HER2 status for diagnosis of early-stage tumors; it might be especially useful in metastatic disease for prognosis, as an indicator of cancer progression and of therapy response, particularly to anti-HER2 therapies. Owing to these data, sHER2 ECD should be considered as a promising biomarker to detect cancer recurrence and metastasis.

A combination of p53-activating APR-246 and phosphatidylserine-targeting antibody potently inhibits tumor development in hormone-dependent mutant p53-expressing breast cancer xenografts

Background

Between 30 and 40% of human breast cancers express a defective tumor suppressor p53 gene. Wild-type p53 tumor suppressor protein promotes cell-cycle arrest and apoptosis and inhibits vascular endothelial growth factor-dependent angiogenesis, whereas mutant p53 protein (mtp53) lacks these functions, resulting in tumor cell survival and metastasis. Restoration of p53 function is therefore a promising drug-targeted strategy for combating mtp53-expressing breast cancer.

Methods

In this study, we sought to determine whether administration of APR-246, a small-molecule drug that restores p53 function, in combination with 2aG4, an antibody that targets phosphatidylserine residues on tumor blood vessels and disrupts tumor vasculature, effectively inhibits advanced hormone-dependent breast cancer tumor growth.

Results

APR-246 reduced cell viability in mtp53-expressing BT-474 and T47-D human breast cancer cells in vitro, and significantly induced apoptosis in a dose-dependent manner. However, APR-246 did not reduce cell viability in MCF-7 breast cancer cells, which express wild-type p53. We next examined APR-246's anti-tumor effects in vivo using BT-474 and T47-D tumor xenografts established in female nude mice. Tumor-bearing mice were treated with APR-246 and/or 2aG4 and tumor volume followed over time. Tumor growth was more effectively suppressed by combination treatment than by either agent alone, and combination therapy completely eradicated some tumors. Immunohistochemistry analysis of tumor tissue sections demonstrated that combination therapy more effectively induced apoptosis and reduced cell proliferation in tumor xenografts than either agent alone. Importantly, combination therapy dramatically reduced the density of blood vessels, which serve as the major route for tumor metastasis, in tumor xenografts compared with either agent alone.

Conclusion

Based on our findings, we contend that breast tumor growth might effectively be controlled by simultaneous targeting of mtp53 protein and tumor blood vessels in mtp53-expressing cancers.

Evaluation of HER-2/neu in Serum and Tissue of Primary and Metastatic Breast Cancer Patients using an Automated Enzyme Immunoassay

Serum HER-2/neu concentrations were evaluated in 172 healthy subjects, 176 primary and 55 metastatic breast cancer patients, employing a new automated assay (Bayer Immuno 1™ serum HER-2/neu). Using 13 ng/mL as the cutoff, abnormal HER-2/neu serum levels were found in 8% (14/176) of primary and 50.9% (28/55) of metastatic breast cancer patients.

Both in primary and metastatic breast cancer a significant relationship was found with the stage of the disease when serum HER-2/neu was considered as a categorized variable (p=0.0003 and p=0.02, respectively), but not when it was taken as a continuous variable (p=0.247 and p=0.146, respectively). Moreover, we evaluated the correlation between Immuno 1™ HER-2/neu and Oncogene Research Products ELISA assay in 53 normal subjects, 46 primary and 34 metastatic breast cancer patients. The correlation was relatively good (p<0.0001), although substantial differences could be found in single cases. The Immuno 1™ assay was also evaluated for the first time in breast cancer tissue. The method, which showed good performance both in terms of imprecision and linearity, was used to measure HER-2/neu protein in 140 cytosol samples from primary breast cancer tissue and in homogenates from 40 matched cases. The correlation between the two matrixes was very close (p<0.0001). By contrast, no correlation was found between serum and matched cytosol (p=0.101) or ho-mogenate samples (p=0.511).

Epidermal Growth Factor Receptor Serum Levels and Prognostic Value in Malignant Gliomas

Aims and background

The epidermal growth factor receptor (EGFR) is a member of a family of cell membrane receptors that use tyrosine kinase activity as the signal transduction mechanism. It is commonly expressed or overexpressed by many solid tumors and correlates with disease progression and a poor clinical prognosis. Increased EGFR expression might therefore be a strong prognostic feature in multiple tumor types, and inhibition of its cellular actions may have substantial therapeutic benefit. The aim of this study was to estimate the EGFR serum concentration for potential use as a biological marker of brain cancer to predict prognosis and follow-up after treatment.

Methods and study design

Serum samples obtained from 50 healthy individuals and 65 brain cancer patients (35 glioblastoma multiforme and 30 anaplastic astrocytomas) were collected before and after treatment and assayed for EGFR extracellular domain serum concentrations by a sandwich ELISA.

Results

EGFR was elevated in 47 of 65 brain cancer patients, with mean serum values of 84 ± 18 ng/ml, compared with that of healthy controls (43.6 ± 11 ng/ml, P = 0.001). There was a significant difference in the mean serum levels of EGFR between glioblastoma multiforme patients (96.2 ± 12 ng/ml) and anaplastic astrocytoma patients (71.6 ± 18 ng/ml, P = 0.04). Sixty brain cancer patients underwent surgery; EGFR serum levels did not show significant differences from those observed before surgery. For all patients, median overall survival was 13 months (anaplastic astrocytoma, 18 months; glioblastoma multiforme, 12.5 months). In 47 patients with high EGFR serum levels, overall survival was reduced (P = 0. 01), with a median survival time corresponding to 11.5 months (anaplastic astrocytoma, 14.5 months; glioblastoma multiforme, 10.5 months).

Conclusions

Although a prospective study with large sample size is warranted, serum EGFR extracellular domain may be potentially useful as a biological marker of gliomas for prediction of prognosis and follow-up after treatment.

ADVIA Centaur® Her-2/Neu Shows Value in Monitoring Patients with Metastatic Breast Cancer

Introduction

The proteolytic breakdown product corresponding to the extracellular domain (ECD) of the HER-2/neu oncoprotein p185 is found in the circulation of healthy individuals and patients having cancers of epithelial origin. For the current evaluation we sought to determine the analytical performance as well as the clinical utility of the newly developed ADVIA Centaur® HER-2/neu assay (Bayer HealthCare LLC, Diagnostics Division, Tarrytown, NY, USA) in monitoring patients with metastatic breast cancer during the course of disease and treatment and to compare the obtained results with those of CA 15–3.

Methods

The analytical performance (including precision, normal range, interfering substances, minimum detectable concentration, dilution recovery, spiking recovery and high-dose hook effect) were determined. HER-2/neu and CA 15–3 values were measured in retrospective samples obtained from 59 patients with metastatic breast cancer undergoing treatment over a 6–12 month period. Serial changes in serum HER-2/neu and CA 15–3 were correlated with changes in clinical status on a visit-to-visit basis. For each pair of serial measurements, changes of equal to or greater than, or less than 15% for HER-2/neu and 21% for CA 15–3 were considered to indicate progression or lack of progression, respectively.

Results

The ADVIA Centaur HER-2/neu assay demonstrated within-run imprecision and total imprecision ranging from 3.0–5.6% and from 3.2–5.7%, respectively. The upper limit of normal was 15.2 ng/mL (90% CI: 14.2–17.0 ng/mL). No significant interference (<5%) was seen with bilirubins, hemoglobin, triglycerides and cholesterol or therapeutic drugs commonly present in the sera of breast cancer patients. The minimum detectable concentration (analytical sensitivity) was found to be 0.5 ng/mL. The patient population in the clinical study included breast cancer patients who responded to therapy (stable, partial or complete response) or had disease progression. HER-2/neu levels showed a concordance of 78.1% (82/105 restaging time points) with the clinical course of disease, whereas CA 15–3 levels showed a concordance of 76.2% (80/105 restaging time points). The concordance with clinical status increased to 85.7% (90/105 restaging time points) when both results were used in combination as a series test.

Conclusions

The ADVIA Centaur HER-2/neu assay provides excellent analytical performance for serial testing of serum HER-2/neu levels. The clinical data demonstrate the usefulness of serum HER-2/neu in monitoring metastatic breast cancer patients during treatment. Furthermore, the results indicate that serum HER-2/neu and CA 15–3 may be useful in identifying disease progression or therapeutic response in different subgroups of women with metastatic breast cancer.

Evaluation of HER2/neu oncoprotein in serum & tissue samples of women with breast cancer

Background & objectives:

The proto-oncogene HER2/neu has been extensively studied in breast cancer patients. Serum levels of HER2/neu by ELISA in breast cancer patients were compared with tissue HER2/neu expression and with other clinicopathological parameters with the aim to investigate whether the serum assay could replace the established tests (IHC/FISH) for HER-2 status.

Methods:

Blood and Tru-cut biopsy samples were collected for determining HER2/neu status in 64 breast cancer patients. The tissue specimens were processed routinely and immunohistochemistry (IHC) for HER2/ER/PR (oestrogen/progesterone receptors) performed. Fluorescence in-situ hybridization (FISH) was performed on all HER2/neu 2 positive cases. Sixty age matched healthy females and females with benign breast disease were taken as controls for ELISA.

Results:

Of the 64 breast cancer cases, 25 (39.1%) had elevated serum HER2/neu levels accompanied with increased tissue expression of HER2/neu receptors. On IHC, HER2/neu score was 3+ in 24 (37.5%) cases, 2+ in three (4.6%), 1+ in 18 (28.1%); while 19 cases (29.7%) showed no HER2/neu expression. Of the three 2+ cases on IHC, two showed amplification on FISH. Twenty one (32.8%) patients were ER positive and 17 (26.6%) were PR positive. There was a significant correlation (P<0.001) of serum HER2 concentration with tumour size, lymph node involvement, stage of disease and histological grade. Serum HER2/neu levels showed a negative correlation with ER status (P=0.047) but no correlation with PR status.

Interpretation & conclusions:

The results suggest that elevated serum HER2 level was associated with a clinicopathological aggressive phenotype of breast carcinoma and was related to tissue HER2 overexpression. Therefore, serum HER2 may be useful for monitoring the course of the disease and response to treatment.

A prospective study to assess the clinical utility of serum HER2 extracellular domain in breast cancer with HER2 overexpression

Purpose

We explored the clinical utility of human epidermal growth factor receptor-2 extracellular domain (HER2/ECD) in patients treated for an invasive breast cancer with HER2 overexpression.

Methods

We prospectively studied HER2/ECD levels in the sera of 334 women included between 2007 and 2014, all treated with trastuzumab. HER2/ECD levels were measured at diagnosis, during treatments, and along the follow-up. We investigated the relationship of HER2/ECD with other clinicopathological parameters at diagnosis, its prognosis value, and its utility during the monitoring of a neoadjuvant treatment and the follow-up.

Results

Elevated HER2/ECD at diagnosis correlated positively with parameters associated with tumor aggressiveness. Disease-free survival of non-metastatic patients was significantly shorter in patients with high HER2/ECD at diagnosis (HR = 13.6, 95 % CI 1.6–113.6, P < 0.0001). Progression-free survival of metastatic patients was better for patients with low HER2/ECD (HR = 2.6, 95 % CI 1.2–5.3, P = 0.033). A multivariate analysis revealed that HER2/ECD level at diagnosis was an independent prognosis factor. During neoadjuvant therapy, a significant decrease in HER2/ECD was reported only for the complete histological response group (P = 0.031). During the follow-up, HER2/ECD helped predict relapse, disease progression, and metastases before imaging in 18.6 % cases of the studied cohort.

Conclusions

HER2/ECD is a prognosis factor that is valuable in evaluating the neoadjuvant treatment efficiency. HER2/ECD also appears to be a helpful surveillance biomarker for the early diagnosis of relapses and to predict the fate of metastases. This study brings evidences to support the use of HER2/ECD in the management of HER2-positive breast cancer.

Serum Human Epidermal Growth Factor 2 Extracellular Domain as a Predictive Biomarker for Lapatinib Treatment Efficacy in Patients With Advanced Breast Cancer

Purpose

We examined the prognostic and predictive value of serum human epidermal growth factor 2 (HER2) extracellular domain (sHER2) in patients with advanced breast cancer treated with lapatinib using data from three randomized trials.

Patients and Methods

We analyzed sHER2 and tissue HER2 (tHER2) data from 1,902 patients (84%) who were randomly assigned to receive lapatinib or control in the trials EGF30001, EGF30008, and EGF100151. Cox regression analyses were performed to correlate both biomarkers with progression-free survival (PFS) and overall survival (OS).

Results

Median sHER2 levels were 25.1 and 10.1 ng/mL in tHER2-amplified (tHER-positive) and nonamplified (tHER-negative) populations, respectively (r = 0.42 for sHER2-tHER2 correlation). Lapatinib had significant PFS benefit over control (hazard ratio [HR], 0.855; P = .004), but not OS (HR, 0.941; P = .33). Lapatinib PFS benefit is independently predicted by higher sHER2 values (HR per 10-ng/mL increase in sHER2: lapatinib-containing therapies, 1.009 v nonlapatinib-containing therapies, 1.044; Pinteraction < .001) and by positive tHER2 (HR [lapatinib v nonlapatinib]: tHER2 positive, 0.638 v tHER2 negative, 0.940; Pinteraction = .001). Within the tHER2-positive subpopulation (n = 515), higher sHER2 values still independently predicted lapatinib PFS benefit (HR per 10-ng/mL increase in sHER2: lapatinib-containing therapies, 1.017 v nonlapatinib-containing therapies, 1.041; Pinteraction = .008). In control arms (n = 936), higher sHER2 was associated with worse prognosis in multivariable analyses (PFS HR per 10 ng/mL: PFS, 1.024; P < .001; and OS, 1.018; P < .001).

Conclusion

Higher sHER2 predicts greater PFS benefit with lapatinib independent of tHER2 status. High sHER2 is also independently prognostic for worse survival in patients who received nonlapatinib-containing therapies. The predictive role of sHER2 for other anti-HER2 agents requires further research.

Serum tumor markers in patients with breast cancer

Several serum tumor markers have been investigated in patients with breast cancer for assessing outcome, predicting recurrence and monitoring the therapeutic response. There is a general consensus concerning their limited application in diagnosing malignancy; however, serum tumor markers can be considered for the early detection of recurrence. The most effective markers for this indication are cancer antigens (CA)15-3 and 27.29, and c-erbB-2, although their efficacy in establishing disease progression has not been determined to date. In terms of evaluating prognosis and predicting response to therapy, only the expression of c-erbB-2 has clinical evidence. To conclude, at present, no serum tumor marker is cost effective, and none can be used with confidence in the decision making regarding breast cancer patients.

Circulating oncoproteins HER2/neu, EGFR and CAIX (MN) as novel cancer biomarkers

Pharmaceutical companies have developed targeted therapies such as trastuzumab and lapatinib for human epidermal growth factor receptor (HER)2/neu-positive tumors, while others have developed antiepidermal growth factor receptor (EGFR) therapies, such as tarceva and erbitux for EGFR-positive tumors. A drug called rencarex is targeted to an oncoprotein designated carbonic anhydrase IX (CAIX), which is being evaluated in renal cell carcinoma patients. Based on these targeted therapeutic approaches, this review describes clinical research studies performed with enzyme-linked immunosorbent assays specific for the circulating oncoproteins, HER2/neu, EGFR and CAIX. These circulating biomarkers have the potential to be used in conjunction with the specific targeted therapies for patient selection, monitoring and management. With the variety of new therapeutic options, the major challenge ahead will be to select the appropriate therapy or combinations of therapies for each patient. Specific biomarker tests, either alone or in panels, will be needed at the appropriate time in the course of disease to ensure that patients receive the right drug at the right time. These tests will also be valuable in monitoring the efficacy of the targeted therapies. A circulating biomarker such as serum HER2/neu may be able to specifically identify patients with progressing HER2/neu-positive disease and provide the information needed by physicians to choose from the variety of HER2/neu-targeted therapies that will soon be available to cancer patients.

Biomarkers for the clinical management of breast cancer: international perspective

The higher incidence of breast cancer in developed countries has been tempered by reductions in mortality, largely attributable to mammographic screening programmes and advances in adjuvant therapy. Optimal systemic management requires consideration of clinical, pathological and biological parameters. Oestrogen receptor alpha (ERα), progesterone receptor (PgR) and human epidermal growth factor receptor 2 (HER2) are established biomarkers evaluated at diagnosis, which identify cardinal subtypes of breast cancer. Their prognostic and predictive utility effectively guides systemic treatment with endocrine, anti-HER2 and chemotherapy. Hence, accurate and reliable determination remains of paramount importance. However, the goals of personalized medicine and targeted therapies demand further information regarding residual risk and potential benefit of additional treatments in specific circumstances. The need for biomarkers which are fit for purpose, and the demands placed upon them, is therefore expected to increase. Technological advances, in particular high-throughput global gene expression profiling, have generated multi-gene signatures providing further prognostic and predictive information. The rational integration of routinely evaluated clinico-pathological parameters with key indicators of biological activity, such as proliferation markers, also provides a ready opportunity to improve the information available to guide systemic therapy decisions. The additional value of such information and its proper place in patient management is currently under evaluation in prospective clinical trials. Expanding the utility of biomarkers to lower resource settings requires an emphasis on cost effectiveness, quality assurance and possible international variations in tumor biology; the potential for improved clinical outcomes should be justified against logistical and economic considerations.

Challenges in the clinical utility of the serum test for HER2 ECD

Approximately 15-30% of breast cancers over-express the HER2/neu receptor. Historically, over-expression of HER2/neu has been identified using IHC or FISH, both of which are invasive approaches requiring tissue samples. Recent evidence has shown that some tumors identified as "negative" using these methods can respond to HER2/neu targeted therapy. Shedding of the extracellular domain (ECD) of the receptor into the circulation has led to the development of a serum test of HER2 ECD as an additional approach to probe HER2/neu overexpression. The serum test will be able to monitor the dynamic changes of HER2 status over the course of disease progression. Some studies further suggest that the serum HER2 ECD level and its change may serve as a biomarker to reflect patients' response to therapy. Yet more than 10years after the first serum HER2 ECD test was approved by the FDA, serum HER2 testing has yet to be widely used in clinical practice. In this article we will review the progress of the serum HER2 ECD test and discuss some obstacles impeding its incorporation into broad clinical practice. We will also discuss recent improvements in the sensitivity and specificity of the assay that offer some hope for the future of serum HER2 test.

Serum HER2/ECD value in stage I and II early breast cancer: need of a lower cut-off?

BACKGROUND

HER2 overexpression is well-established risk factor of worse prognosis in metastatic and early breast cancer. HER2 positivity can be determined from tumor tissue by immunohistochemical staining or by fluorescent in situ hybridization, or from serum by measuring concentration of HER2 receptor extracellular domain (HER2/ECD). HER2/ECD correlates well with worse prognosis in metastatic and locally advanced (stage III) disease if serum concentration is >15 ng/ml, but there are no consistent data for patients with early breast cancer.

METHODS AND RESULTS

41 patients with stage I and II breast cancer and 52 healthy controls were included into the study. HER2/ECD was determined before surgery and correlated with HER2/neu overexpression, Ki67, hormone receptor status and disease stage, and compared with value in healthy controls. Mean serum HER2/ECD concentration in patients was 8.62 ng/ml and 5.78 ng/ml in controls, and the difference was statistically significant (p = 0.000061). The best diagnostic cut-off value was 7.7 ng/ml, with 76.92% sensitivity and 72.92% specificity. Positive predictive value of the test was 69.77% and negative predictive value was 79.55%, with 74.71% of patients correctly classified. Serum HER2/ECD correlated with hormone receptors status, and no correlation with histological overexpression has been observed. CONCLUSION. Serum HER2/ECD concentration of ≥7.7 ng/ml has possible diagnostic value in stage I and II breast cancer. It should not be used as a determinant of HER2 positivity. Prognostic significance of HER2/ECD in early breast cancer, its correlation with hormone receptor status, and interconnection between hormone receptors and HER2 receptor signaling should be further analyzed, since it may have therapeutic implications.

High serum HER2 extracellular domain levels: correlation with a worse disease-free survival and overall survival in primary operable breast cancer patients

PURPOSE

High serum human epidermal growth factors receptor-2 (HER2) extracellular domain (ECD) has been identified as an independent prognostic indicator of poor prognosis in metastatic breast cancer. However, its prognostic value in primary operable breast cancer was still controversial. We aim to investigate the correlation between serum HER2 ECD levels and tissue HER2 status, the association between serum HER2 ECD levels and clinicopathological characteristics, and their impacts on disease-free survival (DFS) and overall survival (OS) in primary operable breast cancer.

METHODS

Two hundred and fifty-two primary operable breast cancer patients pretreated from 2002 to 2009 in Sun Yat-Sen University Cancer Center were enrolled in this study. Serum HER2 ECD was measured by chemiluminescent assay, and tissue HER2 status was accessed by immunohistochemistry (IHC) and fluorescent in situ hybridization (FISH) assay.

RESULTS

There was a significant correlation between serum HER2 ECD levels and HER2 tissue status (P < 0.001, R = 0.36). High serum HER2 ECD levels (≥15 ng/mL) were significantly associated with age (≥35 years) (P = 0.028), postmenopausal status (P < 0.001), stage III (P < 0.001), tumor size (≥2 cm) (P < 0.001), lymph node involvement (P < 0.001), negative estrogen receptor (P = 0.005), and progesterone receptor status (P = 0.001). Multivariate analysis showed that high serum HER2 ECD level was an independent prognostic factor of worse DFS (P = 0.014) and OS (P = 0.014) in primary operable breast cancer patients.

CONCLUSION

Serum HER2 ECD level can reflect tissue HER2 status and can be an independent prognostic indicator for primary operable breast cancer patients.

Serum HER2 level measured by dot blot: a valid and inexpensive assay for monitoring breast cancer progression

Human epidermal growth factor receptor 2 (HER2) is one of the most important prognostic and predictive factors for breast cancer patients. Recently, serum HER2 ECD level of patients detected by enzyme-linked immunoabsorbent assay (ELISA) has been shown to predict tumor HER2 status and reveal its association with tumor progression, recurrence and poor prognosis. In this study, we established a new method, dot blot assay, to measure the serum HER2 level in breast cancer patients and further to evaluate the clinical value for monitoring breast cancer progression. We found that the serum HER2 level measured by dot blot assay was significantly correlated with tissue HER2 status in breast cancer patients (P = 0.001), and also significantly correlated with HER2 level measured by ELISA (P = 1.06×10⁻¹¹). Compared with ELISA method, the specificity and sensitivity of dot blot assay were 95.3% and 65.0%, respectively. The serum HER2 levels of patients with grade III or ER-negative were higher than those with grade I–II (P = 0.004) and ER-positive (P = 0.033), respectively. Therefore, the novel dot blot method to detect serum HER2 level is a valid and inexpensive assay with potential application in monitoring breast cancer progression in clinical situations.

Current technologies for HER2 testing in breast cancer

BACKGROUND

Molecular techniques play an increasingly important role in breast cancer detection and help in the prediction of prognosis and treatment response. HER-2/neu predicts the sensitivity of breast tumors to trastuzumab and lapatinib. Presently there are several ways to assess HER2 status at the protein level (e.g. ELISA), at the RNA level (RT-PCR, microarray) and at the DNA level (fluorescence in situ hybridization, chromogenic in situ hybridization (ISH), silver in situ hybridization or multiplex ligation-dependent probe amplification).

DESIGN

This paper provides an overview of new developments in HER2 testing.

RESULTS

Although these techniques correlate well in comparative studies, discrepancies remain. Each technique has its own (dis)advantages and thus there is no real gold standard. Not surprisingly, there is no consensus at present on which of the protein- or gene-based techniques is superior, on the use of mono- or duo-probe ISH systems, nor on the use of manual or fully-automated staining- and scoring systems.

CONCLUSION

Until large clinical trials clearly point out one strategy as the best predictive one for trastuzumab response, the choice for a testing strategy will probably be based on local preferences which consider both practical and economic issues. Standardization, proper internal and external quality control assessment, laboratory accreditation and automation of tissue processing (autostainers) and interpretation methods (image analysis) will play an increasingly important role in HER2 testing.

Targeting mutant p53 protein and the tumor vasculature: an effective combination therapy for advanced breast tumors

Breast cancer progression depends upon the elaboration of a vasculature sufficient for the nourishment of the developing tumor. Breast tumor cells frequently contain a mutant form of p53 (mtp53), a protein which promotes their survival. The aim of this study was to determine whether combination therapy targeting mtp53 and anionic phospholipids (AP) on tumor blood vessels might be an effective therapeutic strategy for suppressing advanced breast cancer. We examined the therapeutic effects, singly, or in combination, of p53 reactivation and induction of massive apoptosis (PRIMA-1), which reactivates mtp53 and induces tumor cell apoptosis, and 2aG4, a monoclonal antibody that disrupts tumor vasculature by targeting AP on the surface of tumor endothelial cells and causes antibody-dependent destruction of tumor blood vessels, leading to ischemia and tumor cell death. Xenografts from two tumor cell lines containing mtp53, BT-474 and HCC-1428, were grown in nude mice to provide models of advanced breast tumors. After treatment with PRIMA-1 and/or 2aG4, regressing tumors were analyzed for vascular endothelial growth factor (VEGF) expression, blood vessel loss, and apoptotic markers. Individual drug treatment led to partial suppression of breast cancer progression. In contrast, combined treatment with PRIMA-1 and 2aG4 was extremely effective in suppressing tumor growth in both models and completely eradicated approximately 30% of tumors in the BT-474 model. Importantly, no toxic effects were observed in any treatment group. Mechanistic studies determined that PRIMA-1 reactivated mtp53 and also exposed AP on the surface of tumor cells as determined by enhanced 2aG4 binding. Combination treatment led to significant induction of tumor cell apoptosis, loss of VEGF expression, as well as destruction of tumor blood vessels. Furthermore, combination treatment severely disrupted tumor blood vessel perfusion in both tumor models. The observed in vitro PRIMA-1-induced exposure of tumor epithelial cell AP might provide a target for 2aG4 and contribute to the increased effectiveness of such combination therapy in vivo. We conclude that the combined targeting of mtp53 and the tumor vasculature is a novel effective strategy for combating advanced breast tumors.

Value and Limitations of Measuring HER-2 Extracellular Domain in the Serum of Breast Cancer Patients

The human epidermal receptor-2 (HER-2) is overexpressed or amplified in 15% to 25% of breast cancers. Determination of HER-2 tumor status offers clinically useful information, as it selects patients who may benefit from treatment with trastuzumab, the monoclonal antibody against HER-2. Currently approved methods for HER-2 testing include immunohistochemistry or fluorescent in situ hybridization using tumor tissue. A fragment of HER-2 composed of its extracellular domain (ECD) can also be detected in the serum of some patients with breast cancer. As an easily accessible tumor marker, it could offer additional useful prognostic or predictive information. This review will briefly address the biology of the circulating HER-2 ECD and discuss the evidence to support the role, if any, for measuring HER-2 ECD levels in women with breast cancer. In particular, we focus on the value and limitations of serum ECD in both early and advanced breast cancer in the following clinical contexts: as a marker of HER-2 tumor tissue status; clinical implications of raised levels in women who have a tumor not overexpressing HER-2; as a prognostic indicator and as a predictor of response to treatment; and as a monitoring tool for early recurrence. On the basis of our review of the literature, we conclude that there is currently insufficient evidence to support the use of serum HER-2 ECD in the routine management of individual patients with breast cancer. This conclusion is in agreement with the 2007 American Society of Clinical Oncology guidelines on the use of biomarkers in breast cancer.

The HER-2 receptor and breast cancer: ten years of targeted anti-HER-2 therapy and personalized medicine

The human epidermal growth factor receptor (HER-2) oncogene encodes a transmembrane tyrosine kinase receptor that has evolved as a major classifier of invasive breast cancer and target of therapy for the disease. The validation of the general prognostic significance of HER-2 gene amplification and protein overexpression in the absence of anti-HER-2 targeted therapy is discussed in a study of 107 published studies involving 39,730 patients, which produced an overall HER-2-positive rate of 22.2% and a mean relative risk for overall survival (OS) of 2.74. The issue of HER-2 status in primary versus metastatic breast cancer is considered along with a section on the features of metastatic HER-2-positive disease. The major marketed slide-based HER-2 testing approaches, immunohistochemistry, fluorescence in situ hybridization, and chromogenic in situ hybridization, are presented and contrasted in detail against the background of the published American Society of Clinical Oncology-College of American Pathologists guidelines for HER-2 testing. Testing issues, such as the impact of chromosome 17 polysomy and local versus central HER-2 testing, are also discussed. Emerging novel HER-2 testing techniques, including mRNA-based testing by real-time polymerase chain reaction and DNA microarray methods, HER-2 receptor dimerization, phosphorylated HER-2 receptors, and HER-2 status in circulating tumor cells, are also considered. A series of biomarkers potentially associated with resistance to trastuzumab is discussed with emphasis on the phosphatase and tensin homologue deleted on chromosome ten/Akt and insulin-like growth factor receptor pathways. The efficacy results for the more recently approved small molecule HER-1/HER-2 kinase inhibitor lapatinib are also presented along with a more limited review of markers of resistance for this agent. Additional topics in this section include combinations of both anti-HER-2 targeted therapies together as well as with novel agents including bevacizumab, everolimus, and tenespimycin. A series of novel HER-2-targeting agents is also presented, including pertuzumab, ertumaxomab, HER-2 vaccines, and recently discovered tyrosine kinase inhibitors. Biomarkers predictive of HER-2 targeted therapy toxicity are included, and the review concludes with a consideration of HER-2 status in the prediction of response to non-HER-2 targeted treatments including hormonal therapy, anthracyclines, and taxanes.

Utility of serum HER2 extracellular domain assessment in clinical decision making: pooled analysis of four trials of trastuzumab in metastatic breast cancer

PURPOSE

Trastuzumab is a humanized monoclonal antibody directed against human epidermal growth factor receptor 2 (HER2). Trastuzumab alone or in combination with chemotherapy has been shown to be effective in patients with HER2-positive early and metastatic breast cancer. The extracellular domain (ECD) of the HER2 protein may be shed into the serum and is detectable using an enzyme-linked immunosorbent assay. Correlations have been reported between raised baseline ECD levels and response to trastuzumab, suggesting that serum ECD levels may be useful in making treatment decisions in patients with HER2-positive breast cancer. We investigated this relationship, and also the effect of trastuzumab and chemotherapy on ECD levels, in patients with advanced breast cancer.

METHODS

This study analyzed sequential ECD determinations on 322 patients treated with six different treatment regimens in four clinical trials.

RESULTS

Baseline values were available in 296 patients, and of these, 205 (69%) had raised levels (> 15 ng/mL). No clear relationship was found between baseline ECD levels and tumor response. After initiating combination therapy, ECD levels declined irrespective of treatment received and tumor response. For trastuzumab monotherapy, some trend between changes in ECD levels in early cycles and best response was discernable, but the overlap was too broad to be clinically useful. Disease progression was not reliably predicted by rising ECD levels in the majority of patients.

CONCLUSION

Based on our data, we cannot recommend using serum HER2 ECD levels to make trastuzumab or other treatment decisions for individual patients with advanced/metastatic breast cancer.

HER2: The Neu Prognostic Marker for Breast Cancer

A fundamental mechanism of genetic alteration is amplification of entire gene sequences that results in overexpression of a gene product or protein. If the amplified gene is a member of the oncogene family and/or a regulator of DNA replication or cell cycle progression, overexpression of this oncoprotein may result in enhanced growth advantages for these cells. Amplification of one such oncogene, HER2 (neu, erbB-2), in up to 35% of human breast cancers is associated with a poor prognosis but may predict response to various therapeutic modalities. FDA-approved assays are available to detect the HER2 protein receptor or the HER2 gene sequence to determine eligibility for Herceptin treatment or adriamycin treatment in node positive patients, respectively. As testing for HER2 is becoming more common in the clinical laboratory, we provide an overview of the biology, diagnostic methods, and emerging clinical value of HER2 gene amplification.

Evaluation of serum HER2 extracellular domain in early breast cancer patients: correlation with clinicopathological parameters and survival

BACKGROUND

We explored the correlation between serum human epidermal growth factor receptor-2 (HER2) extracellular domain (ECD) and tissue HER2 status, their relationship with clinicopathological parameters and their impact on disease-free survival (DFS) and overall survival in early breast cancer patients.

PATIENTS AND METHODS

This prospective trial included patients with stage I-III breast cancer. Serum HER2 ECD levels were measured by two enzyme-linked immunosorbent assays before surgical treatment. Tissue HER2 status was analyzed by immunohistochemistry (IHC) in all tumors; FISH assay was utilized in HER2 2+ tumors by IHC.

RESULTS

From May 2000 to July 2005, 256 consecutive stage I-III breast cancer patients were included in this study. High serum HER2 ECD levels (>or=15 ng/ml) were reported in 23 patients (9.0%) and HER2-positive status in tumor tissue was observed in 42 patients (16.4%) with a concordance of 87.1%. High HER2 ECD levels were significantly associated with high histological grade (P = 0.003), stage III (P = 0.008), lymph node involvement (P = 0.035) and negativity of both estrogen (P = 0.016) and progesterone (P = 0.007) receptors. At multivariate analysis, high serum HER2 ECD levels were a significant independent prognostic factor of worse DFS (P = 0.009).

CONCLUSIONS

A statistically significant association was observed between high serum HER2 ECD levels and worse DFS in early breast cancer patients.

HER-2/neu diagnostics in breast cancer

HER-2/neu status of the primary breast cancer (PBC) is determined by immunohistochemistry and fluorescent in situ hybridization. Because of a variety of technical factors, however, the PBC may not accurately reflect the metastatic tumor in terms of HER-2/neu status. Recently published guidelines recommend that tumors be defined as HER-2/neu positive if 30% or more of the cells are 3+. Circulating levels of the HER-2 extracellular domain can be measured in serum using a test cleared by the US Food and Drug Administration, and increased serum HER-2/neu levels to above 15 ng/ml can reflect tumor progression. Studies comparing tissue HER-2/neu status of the PBC and HER-2/neu levels above 15 ng/ml in metastatic breast cancer patients are also reviewed.

Circulating protein biomarkers of pharmacodynamic activity of sunitinib in patients with metastatic renal cell carcinoma: modulation of VEGF and VEGF-related proteins

BACKGROUND

Sunitinib malate (SUTENT) is an oral, multitargeted tyrosine kinase inhibitor, approved multinationally for the treatment of advanced RCC and of imatinib-resistant or - intolerant GIST. The purpose of this study was to explore potential biomarkers of sunitinib pharmacological activity via serial assessment of plasma levels of four soluble proteins from patients in a phase II study of advanced RCC: VEGF, soluble VEGFR-2 (sVEGFR-2), placenta growth factor (PlGF), and a novel soluble variant of VEGFR-3 (sVEGFR-3).

METHODS

Sunitinib was administered at 50 mg/day on a 4/2 schedule (4 weeks on treatment, 2 weeks off treatment) to 63 patients with metastatic RCC after failure of first-line cytokine therapy. Predose plasma samples were collected on days 1 and 28 of each cycle and analyzed via ELISA.

RESULTS

At the end of cycle 1, VEGF and PlGF levels increased >3-fold (relative to baseline) in 24/54 (44%) and 22/55 (40%) cases, respectively (P < 0.001). sVEGFR-2 levels decreased >or= 30% in 50/55 (91%) cases and >or= 20% in all cases (P < 0.001) during cycle 1, while sVEGFR-3 levels were decreased >or= 30% in 48 of 55 cases (87%), and >or= 20% in all but 2 cases. These levels tended to return to near-baseline after 2 weeks off treatment, indicating that these effects were dependent on drug exposure. Overall, significantly larger changes in VEGF, sVEGFR-2, and sVEGFR-3 levels were observed in patients exhibiting objective tumor response compared with those exhibiting stable disease or disease progression (P < 0.05 for each analyte; analysis not done for PlGF).

CONCLUSION

Sunitinib treatment in advanced RCC patients leads to modulation of plasma levels of circulating proteins involved in VEGF signaling, including soluble forms of two VEGF receptors. This panel of proteins may be of value as biomarkers of the pharmacological and clinical activity of sunitinib in RCC, and of angiogenic processes in cancer and other diseases.

Kinetics of serum HER-2/neu changes in patients with HER-2-positive primary breast cancer after initiation of primary chemotherapy

BACKGROUND

The purpose of the study was to determine the utility of quantitation of the extracellular domain (ECD) of the HER-2/neu receptor in the serum for predicting response to treatment in patients with primary breast cancer receiving neoadjuvant therapy.

METHODS

HER-2/neu ECD was measured in sera obtained from 39 patients with HER-2-amplified stage II-III primary breast cancer undergoing neoadjuvant chemotherapy. Patients were randomly assigned to either 4 cycles of paclitaxel followed by 4 cycles of fluorouracil, epirubicin, and cyclophosphamide (FEC) (n = 10) or to the same chemotherapy with simultaneous weekly trastuzumab for 24 weeks (n = 29). Changes in HER-2 ECD were monitored with the Bayer HER-2/neu assay over 6 months and correlated with pathological response to treatment.

RESULTS

Before initiation of chemotherapy, 28.2% of patients had elevated concentration of the HER-2 ECD (>15 ng/mL). The median baseline serum HER-2 ECD concentration was 13.6 ng/mL (mean +/- SD, 20.3 +/- 35.5 ng/mL). A decrease in the median HER-2 ECD levels from baseline to Week 3 and from baseline to Week 6 of chemotherapy was seen regardless of treatment regimen. No significant difference in baseline HER-2 ECD levels was observed between the groups who achieved pathological complete response (pCR) and the group with residual disease (P = .41). However, a 9% drop from Week 3 to Week 6 after initial chemotherapy was predictive of pCR (P = .04).

CONCLUSION

A decrease in serum HER-2 ECD levels early during treatment was associated with pathological response in patients receiving primary chemotherapy, particularly trastuzumab-based regimens. Serum HER-2 ECD levels may serve to monitor neoadjuvant therapy in HER-2-positive primary breast cancer.

Serum c-erbB-2 protein is a useful marker for monitoring tumor recurrence of the breast

C-erbB-2 oncogene protein (ErbB-2/HER-2) overexpression is a prognostic marker of breast carcinoma. The purpose of this study was to evaluate serum ErbB-2 for monitoring tumor recurrence of operable breast carcinoma patients. The subjects were 86 breast carcinoma patients with stage I-IIIB. Sera were collected at preoperative and postoperative periods from 1996 to 2000. The cutoff value was set at 5.4 ng/ml for preoperative patients and at 6.5 ng/ml for postoperative patients. Twenty-nine patients (34%) had higher preoperative serum ErbB-2 levels (>or=5.4 ng/ml). A higher preoperative serum ErbB-2 was associated with higher clinical stage, larger tumor size, nodal metastasis, higher histologic grade and lymphatic invasion, but not with vascular invasion, hormonal receptor status or other tumor markers, such as carcinoembryonic antigen (CEA) and carbohydrate antigen 15-3 (CA15-3). As of April 2005, 27 patients (31%) had recurrence and 18 (62%) of them had a higher preoperative serum ErbB-2. Seventeen patients died of tumor progression. The recurrence-free survival rates at 7 years after breast surgery were 84% in 57 patients with a normal preoperative serum ErbB-2 and 41% in 29 patients with a higher preoperative serum ErbB-2 (p < 0.0001). The overall survival rates at 7 years were 93% and 55% (p < 0.0001), respectively. A multivariate analysis revealed that preoperative serum ErbB-2 was an independent prognostic factor for recurrence-free survival and overall survival in breast carcinoma patients. The specificities and sensitivities of postoperative tumor markers (CEA, CA15-3 and ErbB-2) were 91%, 100% and 85%, and 40%, 30% and 70%, respectively. Serum ErbB-2 is a preoperative prognostic marker and may be useful for monitoring tumor recurrence of the breast.

Serum HER2 extracellular domain in metastatic breast cancer patients treated with weekly trastuzumab and paclitaxel: association with HER2 status by immunohistochemistry and fluorescence in situ hybridization and with response rate

PURPOSE

We explored the relationship between circulating HER2 extracellular domain (ECD) and tissue HER2 status as determined by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). We also examined its predictive value in a cohort of metastatic breast cancer patients treated with weekly trastuzumab and paclitaxel.

METHODS

Eligible patients had pre- and post-treatment stored serum specimens and were treated on a previously reported phase II trial. Retrospective analysis evaluated: the association between pretreatment serum HER2 ECD and tissue HER2 status by IHC and FISH; and the association between change in serum HER2 ECD after 12 weeks of therapy and response proportion.

RESULTS

Stored serum samples were available for 55/95 (58%) patients. Statistically significant associations were found between HER2 status as assessed by IHC and FISH, and baseline serum HER2 ECD level. Patients whose ECD normalized after 12 weeks of therapy had a higher response proportion compared with patients with persistently high ECD levels (68% versus 15%, P=0.005). A relative decline of over 55% from baseline HER2 ECD predicted response to therapy.

CONCLUSION

A statistically significant association was observed between pretreatment serum HER2 ECD and tissue HER2 status as assessed by IHC and FISH. A decrease in serum HER2 ECD level was a significant predictor of response to trastuzumab-based therapy.

Expression of epidermal growth factor receptor in cervical tissue and serum in patients with cervical neoplasia

OBJECTIVE

We hypothesized that there may be a relationship between epidermal growth factor receptor (EGFR) expression in cervical tissue and serum in patients with cervical neoplasia.

MATERIALS AND METHODS

The expression of EGFR was measured in cervical tissues from 23 cervical intraepithelial neoplasia patients and 16 cervical carcinoma patients using immunohistochemical staining and the level of serum EGFR extracellular domain was measured in serum from 17 cervical intraepithelial neoplasia patients and 14 cervical carcinoma patients using enzyme-linked immunosorbent assay.

RESULTS

The expression of EGFR was significantly increased as normal cervical tissue progressed to cervical intra-epithelial neoplasia then to cervical carcinoma (p = .009). The mean level of serum EGFR according to the intensity of immunohistochemical staining in negative, weakly positive, positive, and strongly positive staining was 19.36 +/- 3.12 fmol/mL, 20.99 +/- 3.59 fmol/mL, 29.08 +/- 16.86 fmol/mL, and 24.34 +/- 10.35 fmol/mL, respectively (p = .450).

CONCLUSIONS

We believe that the level of serum EGFR may have a similar role as tumor markers such as the EGFR expression in cervical neoplastic tissue.

Prognostic and Predictive Impact of the HER-2/neu Extracellular Domain (ECD) in the Serum of Patients Treated with Chemotherapy for Metastatic Breast Cancer

BACKGROUND

The extracellular domain of the HER-2/neu -receptor (ECD) is shed from the receptor protein and can be detected in serum. However, the clinical implication of HER-2/neu ECD measurement must be further evaluated.

METHODS

In patients with metastatic breast cancer participating in a trial on first-line chemotherapy, the association of serum HER-2/neu ECD with progression-free interval, survival, and response was studied. Blood samples of patients receiving epirubicin and either cyclophosphamide (EC) or paclitaxel (ET) were collected before (n = 103) and in addition, after three courses of therapy (n = 46).

RESULTS

HER-2/neu ECD levels correlate with HER-2/neu overexpression of corresponding primary tumors determined by immunohistochemistry (antibody CB11, p = 0.018) with an optimized cut-off at 15 ng/mL. Elevated serum levels of HER-2/neu ECD before chemotherapy were correlated with shorter overall survival (p = 0.0097), but not with reduced progression-free survival and response to chemotherapy. In subgroup analyses, patients with elevated pretherapeutic HER-2/neu ECD levels treated with EC showed shorter overall survival (p = 0.0092); no difference was seen in the ET group. With regard to progression-free survival, patients with elevated HER-2/neu ECD levels tended to benefit from ET (p = 0.0341), in patients with low levels no difference was observed between EC and ET. A decrease of HER-2/neu ECD levels after three courses of therapy was associated with response to therapy (p = 0.006).

CONCLUSION

In our group of metastatic breast cancer patients, elevated HER-2/neu ECD levels are associated with decreased overall survival. With regard to progression-free survival, particularly patients with high HER-2/neu ECD levels seem to benefit from taxane-containing chemotherapy.

Monitoring the Circulating Levels of the HER2/neu Oncoprotein in Breast Cancer

The HER2/neu oncoprotein is a major target for the development of new cancer therapies and is similar to the estrogen receptor, which guides hormone therapy. The HER2/neu status is used to guide therapy decisions in patients with HER2/neu-overexpressing breast cancer tumors. The HER2/neu oncogene, or c-erbB-2, encodes a transmembrane receptor protein that is expressed on normal epithelial cells and can be overexpressed in breast cancer cells. Studies have shown that the extracellular domain (ECD) of the HER2/neu oncoprotein is released from the cell and can be measured in the circulation of women with breast cancer. Enzyme-linked immunosorbent assay methods used to measure the circulating HER2/neu ECD have shown that the prevalence of elevated ECD levels is approximately 18.1% in women with primary breast cancer and approximately 45.6% in women with metastatic breast cancer (MBC). Many studies have monitored the circulating ECD levels after surgery and indicate that increasing ECD levels can indicate recurrence of breast cancer earlier than clinical diagnosis. Studies in women with MBC showed that serial changes in circulating HER2/neu ECD levels paralleled the clinical course of disease, regardless of the treatment regimen. Several studies identified a subgroup of patients with MBC who had HER2/neu-negative disease by tissue testing but developed elevated ECD levels with MBC. In contrast to tissue testing, which is a one-time event, monitoring the circulating levels of the HER2/neu ECD in patients with breast cancer provides a real-time assessment of the HER2/neu status and provides important information for managing the therapy of patients with MBC.

Targeted therapy in breast cancer: the HER-2/neu gene and protein

The HER-2/neu oncogene, a member of the epidermal growth factor receptor or erb gene family, encodes a transmembrane tyrosine kinase receptor that has been linked to prognosis and response to therapy with the anti-HER-2-humanized monoclonal antibody, trastuzumab (Herceptin, Genentech, South San Francisco, CA) in patients with advanced metastatic breast cancer. HER-2/neu status has also been tested for its ability to predict the response of breast cancer to other therapies including hormonal therapies, topoisomerase inhibitors, and anthracyclines. This review includes an analysis of 80 published studies encompassing more than 25,000 patients designed to consider the relative advantages and disadvantages of the various methods of measuring HER-2/neu in clinical breast cancer specimens. Southern blotting, PCR amplification detection, and fluorescence in situ hybridization assays designed to detect HER-2/neu gene amplification are compared with HER-2/neu protein overexpression assays performed by immunohistochemical techniques applied to frozen and paraffin-embedded tissues and enzyme immunoassays performed on tumor cytosols. The significance of HER-2/neu overexpression in ductal carcinoma in situ and the HER-2/neu status in uncommon female breast conditions and male breast cancer are also considered. The role of HER-2/neu testing for the prediction of response to trastuzumab therapy in breast cancer is reviewed along with the current studies designed to test whether HER-2/neu status can predict the response to standard and newer hormonal therapies, cytotoxic chemotherapy, and radiation. The review will also evaluate the status of serum-based testing for circulating HER-2/neu receptor protein and its ability to predict disease outcome and therapy response.

Potential clinical utility of serum HER-2/neu oncoprotein concentrations in patients with breast cancer

BACKGROUND

The HER-2/neu oncogene and its p185 receptor protein are indicators of a more aggressive form of breast cancer. HER-2/neu status guides Herceptin therapy, specifically directed to the extracellular domain (ECD) of the HER-2/neu oncoprotein. The HER-2/neu ECD is shed from cancer cells into the circulation and is measurable by immunoassay.

METHODS

We performed a systematic review of the peer-reviewed literature on circulating ECD with respect to prevalence, prognosis, prediction of response to therapy, and monitoring of breast cancer.

RESULTS

The prevalence of increased ECD in patients with primary breast cancer varied between 0% and 38% (mean, 18.5%), whereas in metastatic disease the range was from 23% to 80% (mean, 43%). Some women with HER-2/neu-negative tumors by tissue testing develop increased ECD concentrations in metastatic disease. Increased ECD has been correlated with indicators of poor prognosis, e.g., overall survival and disease-free survival. Increased ECD predicts a poor response to hormone therapy and some chemotherapy regimens but can predict improved response to combinations of Herceptin and chemotherapy. Many studies support the value of monitoring ECD during breast cancer progression because serial increases precede the appearance of metastases and longitudinal ECD changes parallel the clinical course of disease.

CONCLUSIONS

The monitoring of circulating HER-2/neu ECD provides a tool for assessing prognosis, for predicting response to therapy, and for earlier detection of disease progression and timely intervention with appropriate therapy.

ELISA for quantitation of serum C-erbB-2 oncoprotein in breast cancer patients

C-erbB-2 is a protooncogene that is overexpressed in various cancers, either due to its amplification and/or increased transcription, and has been associated with more aggressive disease and a poor clinical prognosis in 20-30% of patients with breast cancer. Besides the prognostic factors such as tumor size, tumor grade, lymph node status, etc., which are significant in the management of breast cancer, C-erbB-2 level might also serve as an additional factor. Immunohistochemistry is the most frequently used method to study the expression of C-erbB-2 in breast cancer. We have generated a panel of monoclonal antibodies against C-erbB-2 oncoprotein with a view to evaluate their application for the diagnosis and therapy of breast cancer. In the present study, a simple, quantitative sandwich ELISA has been developed that uses two monoclonal antibodies directed against the extracellular domain of C-erbB-2 product, designated as CIBCgp185 as the capture antibody and CIBCHER-2 as the detector antibody. C-erbB-2 protein, isolated from BT474 cells, a human breast carcinoma cell line with high expression of C-erbB-2 and purified by Concanavalin A-Sepharose 4B affinity chromatography and HPLC has been used to develop the ELISA procedure. Sera samples of 150 healthy women donors and of 300 breast cancer patients with different histological types of malignancies have been analysed. The control women had serum C-erbB-2 in the range of 4.0-13.2 ng/mL, whereas the 300 breast cancer patients studied had a range of 4.8-75.2 ng/mL with a cut off value of 13.8 ng/mL. Our study showed that 18.6% of breast cancer patients had elevated levels of circulating C-erbB-2. These results might suggest that the serum C-erbB-2 level can be used as a potential tumor marker for breast cancer and that the Sandwich ELISA procedure might serve as an excellent alternative to immunohistochemistry in the near future.

Serum HER-2/neu in the management of breast cancer patients

The clinical role of HER-2/neu, a 185 kD epithelial transmembranous protein, has evolved after the approval of the anti-HER-2/neu targeted monoclonal antibody trastuzumab (Herceptin) for the therapy of metastatic breast cancer. The extracellular domain of HER-2/neu undergoes proteolytic cleavage from the full-length protein by metalloproteases, and is shed into the blood as a circulating antigen. While HER-2/neu gene amplification and/or protein overexpression are detected in approximately 25% of primary breast cancers, serum HER-2/neu levels are elevated beyond the upper limit of normal in 50 to 60% of stage IV breast cancer patients. HER-2/neu in serum can be detected by enzyme immunoassays (manual and automated versions). It has been shown to have prognostic and predictive information in breast cancer patients. Monitoring for recurrence by serum HER-2/neu reaches a high sensitivity for HER-2/neu positive tumors. Longitudinal follow-up of patients during any kind of systemic therapy allows for monitoring of the therapeutic success. When utilized in these applications, serum HER-2/neu testing is complementary to HER-2/neu tissue results and to the determination of classical tumor markers such as CA 15-3, CA 27.29 and CEA, which are not targeted by specific forms of systemic therapy.

Growth factor receptors in breast cancer: potential for therapeutic intervention

Increased expression and activation of receptor tyrosine kinases occurs frequently in human breast carcinomas. Several therapies targeting these receptors are currently in clinical trials. Therapeutic strategies include blockade of individual receptors with monoclonal antibodies and inhibition of tyrosine kinase function. Trastuzumab is the first of these biologic therapies to be approved for patients with human epidermal growth factor receptor 2 (HER2)-overexpressing metastatic breast cancer. Novel trastuzumab-based combinations are being investigated in patients with advanced breast cancer. Large clinical trials have also been launched in the adjuvant setting. Small molecules that inhibit specific tyrosine kinases (e.g., epidermal growth factor receptor, HER2) are in phase I and phase II clinical trials. Other growth-factor-targeted drugs that have reached clinical development include STI571 and antibodies directed at the insulin-like growth factor pathway. Biologic therapies directed against these important receptors are promising. In this review we discuss challenges and opportunities for the development of growth-factor-targeted approaches for the treatment of breast cancer.

Clinical utility of serial serum c-erbB-2 determinations in the follow-up of breast cancer patients

To evaluate the ability of serum c-erbB-2 protein to (1) indicate occult and manifest metastases and (2) reflect response to first-line therapy, serial serum c-erbB-2 measurements were performed in a retrospective series of 52 primary breast cancer patients who had developed metastatic disease during follow-up. The results were compared with CA 15-3. Preoperatively, 31% (16/52) of the primary breast cancer patients had elevated c-erbB-2 concentrations. The CA 15-3 positivity rate was 13% (7/52). After surgery, 10 of the 52 patients showed either stable but highly elevated or rising c-erbB-2 serum levels indicating serum c-erbB-2 producing minimal residual disease. Increasing CA 15-3 concentrations were seen in only three patients. Elevated serum c-erbB-2 levels predicted manifest metastases in 27 and 50% of the patients at 6 and 3 months, respectively, prior to clinical diagnosis. CA 15-3 was less sensitive. Only 16 and 32% of the patients had increased CA 15-3 serum concentrations at 6 and 3 months, respectively, prior to clinical detection. The positivity rates of c-erbB-2 and CA 15-3 were similar when metastases were clinically diagnosed. Elevated c-erbB-2 concentrations were found in 62% (32/52). The sensitivity of CA 15-3 was 56% (29/52). The association between serum profiles and response to first-line therapy was evaluated in detail for 45 patients. Serial c-erbB-2 and CA 15-3 measurements reflected disease course in 24 and 27 patients, respectively. The serum profiles of c-erbB-2 and CA 15-3 were similar in 17 patients. In summary, our results suggest that serial determinations of serum c-erbB-2 are useful to monitor breast cancer patients.

Cellular immunity to the Her-2/neu protooncogene

Her-2/neu (HER-2) is a 185-kDa receptor-like glycoprotein that is overexpressed by a variety of tumors such as breast, ovarian, gastric, and colorectal carcinomas. Overexpression of this oncogene is directly associated with malignant transformation of epithelial cells. The frequency of HER-2 overexpression varies among the different types of cancers, but universally represents a marker of poor prognosis. The critical role of HER-2 in epithelial oncogenesis as well as its selective overexpression on malignant tissues makes it an ideal target for immunotherapy. Antibodies and T cells reactive to HER-2 are known to naturally occur in patients with HER-2 positive tumors, confirming the immunogenicity of the molecule. Both antibodies as well as T cells reactive to HER-2 have been utilized for immunotherapy of HER-2 positive tumors. The "humanized" monoclonal antibody Herceptin has been tested in several clinical trials and found to be an effective adjuvant therapy for HER-2 positive breast and ovarian cancer patients. However, the frequency of patients responding to Herceptin is limited and a majority of patients initially responding to Herceptin develop resistance within a year of treatment. The use of vaccination strategies that generate T cell responses with or without accompanying antibody responses may serve to mitigate the problem. Various strategies for generating T cell-mediated responses against HER-2 are currently being examined in animal models or in clinical trials. The potential advantages of the various approaches to immunotherapy, their pitfalls, and the mechanisms by which HER-2 positive tumors can evade immune responses are discussed in this review.

c-erbB-2 protein in serum of primary lung cancer patients

We determined c-erbB-2 protein level in serum of 86 primary lung cancer patients (78 non-small cell lung carcinomas (NSCLC), 3 small cell carcinomas, 5 not histologically defined) and in 61 controls. Aim of this study was to evaluate the clinical usefulness of c-erbB-2 as marker for lung cancer diagnosis. The protein was measured with a commercially available sandwich enzyme immunoassay. Mean levels of c-erbB-2 were 72.8 +/- 122.3 fmol/ml in lung cancers and 64.6 +/- 17.5 fmol/ml in controls (P = 0.2). No association was found between c-erbB-2 levels and histotype, tumor stage, sex and smoking habits. Among NSCLC, only four patients showed a c-erbB-2 concentration higher than the selected cut-off value of 99.6 fmol/ml. Subjects with levels higher than the 75th percentile in tumors (73 fmol/ml) had a shorter median survival than those with lower levels (6.3 months versus 10.0 months, P = 0.003). Our results indicated that serum c-erbB-2 protein is not a reliable diagnostic marker. There is, however, a suggestion of a possible clinical usefulness in terms of survival prediction.

The Her-2/neu gene and protein in breast cancer 2003: biomarker and target of therapy

The HER-2/neu oncogene encodes a transmembrane tyrosine kinase receptor with extensive homology to the epidermal growth factor receptor. In this review, the association of HER-2/neu gene and protein abnormalities with prognosis and response to therapy with trastuzumab and to other therapies in breast cancer is presented. By considering a series of 80 published studies encompassing more than 25,000 patients, the relative advantages and disadvantages of Southern blotting, polymerase chain reaction amplification, and fluorescence in situ hybridization assays designed to detect HER-2/neu gene amplification are compared with HER-2/neu protein overexpression assays performed by immunohistochemical techniques applied to frozen and paraffin-embedded tissues and enzyme immunoassays performed on tumor cytosols. The significance of HER-2/neu overexpression in ductal carcinoma in situ and the HER-2/neu status in uncommon female breast conditions and male breast cancer are also considered. The role of HER-2/neu testing for the prediction of response to trastuzumab therapy in breast cancer is presented as well as its potential impact on responses to standard and newer hormonal therapies, cytotoxic chemotherapy, and radiation. The review also evaluates the status of serum-based testing for circulating HER-2/neu receptor protein and its ability to predict disease outcome and therapy response.

Association between the ras p21 oncoprotein in blood samples and breast cancer

To assess the potential of using oncoprotein levels in blood as a marker of breast cancer status, we measured ras p21 in blood samples taken from 34 breast cancer cases and 60 non-cancer controls including 26 women with benign breast disease (BBD) and 34 healthy women. Plasma samples drawn before surgery or at routine office visit were analyzed for ras p21 by Western blot with computer aided image analysis to measure staining intensity in integrated pixel units (IPU). We found detectable levels of ras p21 in 53% of the blood samples of cases, in 27% of the BBD controls and 26% of the healthy controls. Comparing cases to the combined control group (n=60) and controlling for known breast cancer risk factors, ras p21 was associated with breast cancer status (odds ratio=5.22, 95% CI=1.58-17.23). The median levels of ras p21 staining were higher in cases (7.04 IPU, P=0.03) compared to BBD controls (0.00 IPU) or healthy controls (0.00 IPU). The sensitivity of the assay for detecting breast cancer was 50% which compares favorably with that seen for erbB-2 ( approximately 10%), a more extensively studied blood-borne tumor marker. Ras p21 may be useful in the early detection of breast tumors and in post-surgical follow-up of patients, giving patients and physicians new tools for managing breast cancer.