Nanoproteomics deciphers the prognostic value of EGFR family proteins-based liquid biopsy

Monitoring tumor-associated protein status in serum can effectively track tumors and avoid time-consuming, costly, and invasive tissue biopsy. Epidermal growth factor receptor (EGFR) family proteins are often recommended in the clinical management of multiple solid tumors. However, the low-abundance of serum EGFR (sEGFR) family proteins hinders the depth-understanding of their function and tumor management. Herein, a nanoproteomics approach coupling with aptamer-modified MOFs (NMOFs-Apt) with mass spectrometry was developed for the enrichment and quantitative analysis of sEGFR family proteins. This nanoproteomics approach exhibited high sensitivity and specificity for sEGFR family protein quantification, with the limit of quantification as low as 1.00 nM. After detecting 626 patients' sEGFR family proteins with various malignant tumors, we concluded that the levels of serum proteins had a moderate concordance with tissue counterparts. Metastatic breast cancer patients with a high level of serum human epidermal growth factor receptor 2 (sHER2) and a low level of sEGFR had a poor prognosis, and patients with a sHER2 decrease of more than 20% had longer disease-free time after receiving chemotherapy. This nanoproteomics method provided a simple and effective approach for low-abundant serum protein detection and our results clarified the potential of sHER2 and sEGFR as cancer markers.

Obtaining and characterization of monoclonal antibodies against recombinant extracellular domain of human epidermal growth factor receptor 2

Human epidermal growth factor receptor 2 (HER2) is an important biomarker for detection and treatment of different types of cancers such as breast, ovarian, stomach cancer. In this study, we developed a monoclonal antibody against the extracellular domain (ECD) of HER2 biomarker of breast cancer. For this purpose, the ECD-HER2 gene was amplified and cloned into an expression vector. Gene was generated in Escherichia coli BL21 (DE3) strain for expression of recombinant protein. The expressed protein was separated by SDS-PAGE and detected by anti-his monoclonal antibody in immunoblotting. Hybridoma cells were obtained by fusing myeloma cells with mouse spleen cells injected with recombinant ECD-HER2 and screened by ELISA for the production of monoclonal antibody. The results indicate that out of three candidate hybridoma cells one clone (1E7) was producing the highest titer and antibody specificity was envisioned in ELISA results. In vivo scaling up culture of hybridoma cells in BALB/C mice lead to significant increase in the monoclonal antibody concentration up to 16 mg/ml. Immunochemical methods demonstrated the specificity of developed antibody against ECD-HER2 protein.

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.

A clinical evaluation of the TK 210 ELISA in sera from breast cancer patients demonstrates high sensitivity and specificity in all stages of disease

Thymidine kinase (TK1) is an enzyme involved in DNA synthesis that leaks into the blood as a result of high cell turnover, particularly in the case of cancer. Serum TK1 activity has been used for prognosis and monitoring of leukemia and lymphoma patients for many years. Here, we describe the first clinical results with the newly developed TK 210 ELISA from AroCell AB. Sera from 124 breast cancer patients with known TNM classification along with sera from 53 healthy females were analyzed by TK 210 ELISA for TK1 protein and TK1 activity levels by the ³[H]-deoxythymidine (dThd) phosphorylation assay. The limit of detection for the TK 210 ELISA was 0.17 ng/ml, and 60 % of the sera from female blood donors were below this value. The median TK1 levels found in sera from breast cancer patients with T1 to T4 stage disease were 0.31, 0.46, 0.47, and 0.55 ng/ml, and these levels significantly differed from healthy controls. The median values of the biomarker CA 15-3 were also increased in patient sera from T1 to T4 patients (16, 34, 36, 40 U/ml, respectively). TK 210 ELISA showed significantly higher sensitivity for the T1 and T2 breast cancer patients compared to the TK activity assay. The combination of the TK1 ELISA and CA 15-3 biomarkers demonstrated a significant increase in sensitivity up to 15 % compared to each marker alone. This evaluation of the TK 210 ELISA strongly suggests that it can provide independent and complementary information for patients with breast cancer.

Expression and Characterization of the Extracellular Domain of Human HER2 from Escherichia Coli, and Production of Polyclonal Antibodies Against the Recombinant Proteins

Human epidermal growth factor receptor 2 (HER2) is a member of the epidermal growth factor receptor (EGFR) family. In this study, the whole extracellular domain gene of HER2 was amplified by RT-PCR from human breast cancer cell line SK-BR-3. The genes of membrane-distal region (A) and membrane proximal region (B) of HER2 extracellular domain were amplified from the cloned template, and then inserted into the expression vector pET-28a and pET-30a, respectively. The recombinant expression vectors were transformed into Escherichia coli BL21 (DE3) cells and induced by isopropyl-b-D-thiogalactopyranoside (IPTG) for expression of proteins His-A and His-B. The expressed proteins were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and western blot. The optimization of culture conditions led us to accomplish the recombinant protein induction with 1.0 mM IPTG at 37 °C for 8 h, and both proteins were expressed in the insoluble form. Both proteins were purified under the denaturing condition using Ni-NTA sepharose column. Balb/c mice were immunized with the purified proteins and then effectively produced polyclonal antibodies, which reached to a relatively high titer by ELISA testing and had good specificity by western blot detection. The HER2 ECD proteins His-A and His-B could be expressed in E. coli and were suitable for production of high titer antibodies against HER2 ECD.

Serum HER2 in combination with CA 15-3 as a parameter for prognosis in patients with early breast cancer

AIM

HER2 in breast cancer tissue is a marker of high prognostic and predictive relevance. Soluble HER2, the extracellular domain of the HER2/neu receptor (HER2 ECD), which is shed into the blood, has been suggested to be a helpful tumor marker. We investigated the relationship between the concentrations of HER2 ECD, CEA and CA 15-3, the association of these markers with clinicopathological features and the impact of HER2 ECD alone and in combination with known prognostic factors on disease free survival (DFS) and cancer specific survival (CSS) in untreated early breast cancer patients.

PATIENTS AND METHODS

HER2 ECD (ADVIA, Bayer), CEA (AxSYM, Abbott) and CA 15-3 (Elecsys, Roche) were measured at time of primary diagnosis in the pre-therapeutic (pre-operative) sera of 241 breast cancer patients and were correlated with clinicopathological parameters and outcome.

RESULTS

Higher HER2 ECD levels were significantly correlated with postmenopausal status (p=0.016) and tissue HER2-overexpression (p<0.0001). Higher serum levels of CA 15-3 were associated with larger tumor size (p=0.019), positive lymph nodes (p=0.019), UICC stage III (p<0.01), positive tissue HER2-overexpression (p<0.05) and negative hormone receptor status (p=0.016). In multivariate analysis, serum HER2 ECD levels, CA 15-3 levels, large tumor size and negative hormonal status were independent prognostic factors in DFS. Patients with both high levels of HER2 ECD (>15 ng/mL) and high serum levels of CA 15-3 (>24 U/mL) had the poorest prognosis with a DFS after 3 years of 50.0%. Patients without elevated serum levels had a better outcome with a DFS of 91.2%.

CONCLUSIONS

In our retrospective analysis, HER2 ECD and CA 15-3 were independent and better prognostic tools than HER2 in tissue. Prospective validation is necessary to confirm their usefulness in clinical practice.

Serum HER2 levels and HER2 status in tumor cells in advanced gastric cancer patients

OBJECTIVE

Increased serum human epidermal growth factor receptor 2 levels have been found in metastatic breast cancer patients and are correlated with human epidermal growth factor receptor 2 overexpression in tumor cells. However, the prevalence of serum human epidermal growth factor receptor 2 in gastric cancer patients has not been elucidated.

METHODS

We retrospectively analyzed formalin-fixed paraffin-embedded tumor tissues and serum samples from 96 advanced gastric cancer patients. Human epidermal growth factor receptor 2 expression and gene amplification in tumor cells were determined by immunohistochemistry and fluorescence in situ hybridization. Serum human epidermal growth factor receptor 2 levels were measured using a chemiluminescent immunoassay. Human epidermal growth factor receptor 2 positivity in tumor cells was defined as immunohistochemistry 2+ with fluorescence in situ hybridization positive or immunohistochemistry 3+ with any fluorescence in situ hybridization results.

RESULTS

All tissue samples and serum samples were successfully measured. Nineteen patients (20%) were human epidermal growth factor receptor 2-positive in tumor cells. The median serum human epidermal growth factor receptor 2 level was 9.3 ng/ml (range, 5.0-332.4 ng/ml), and serum human epidermal growth factor receptor 2 levels were significantly separated according to human epidermal growth factor receptor 2 status in tumor cells (P < 0.0001, Wilcoxon's rank sum test); median serum human epidermal growth factor receptor 2 levels in human epidermal growth factor receptor 2-negative patients and -positive patients were 8.9 (range, 5.0-20.5) and 24.0 (range, 9.7-332.4), respectively. There were 15 serum human epidermal growth factor receptor 2-positive patients (16%) using a cutoff value of 15 ng/ml. The sensitivity and the specificity of serum human epidermal growth factor receptor 2 with respect to human epidermal growth factor receptor 2 positivity in tumor cells were 53 and 94%, respectively.

CONCLUSIONS

Serum human epidermal growth factor receptor 2 measurements cannot be substituted for tissue human epidermal growth factor receptor 2 diagnosis in advanced gastric cancer patients. However, serum human epidermal growth factor receptor 2 levels are associated with human epidermal growth factor receptor 2 overexpression in tumor cells. Further investigations of clinical significance of serum human epidermal growth factor receptor 2 as a predictive marker and a therapy-monitoring marker are warranted.

Properties of cellular and serum forms of thymidine kinase 1 (TK1) in dogs with acute lymphocytic leukemia (ALL) and canine mammary tumors (CMTs): implications for TK1 as a proliferation biomarker

BACKGROUND

Thymidine kinase 1 (TK1) is a deoxyribonucleic acid (DNA) precursor enzyme and a proliferation biomarker used for prognosis and treatment monitoring of breast cancer in humans. The aim was to determine if serum thymidine kinase 1 (sTK1) activity and sTK1 protein levels in dogs with mammary tumors could be useful in veterinary medicine.

RESULTS

Serum samples from 20 healthy dogs and 27 dogs with mammary tumors were analyzed for sTK1 activity, using an [(3)H]-deoxythymidine (dThd) phosphorylation assay, and for sTK1 protein levels by immune affinity/Western blot assay. The molecular forms of sTK1 in acute lymphocytic leukemia (ALL), canine mammary tumor (CMT), and healthy sera were determined by size exclusion chromatography. Mean sTK1 activities in CMT were 1.0 ± 0.36 pmol/min/mL, differing significantly from healthy dogs (mean ± SD = 0.73 ± 0.26 pmol/min/mL). Serum TK1 protein (26 kDa polypeptide) levels were also significantly higher in CMTs compared to healthy dogs (mean ± SD = 28.5 ± 11.4, and 8.5 ± 4 ng/mL, respectively). Cellular TK1 isolated from ALL tumor cells was predominantly a dimer, while the serum TK1 activity eluted as a high molecular weight (MW) oligomer. In analyses of CMT tissue extracts, TK1 activity eluted in two peaks, a minor peak with a high MW oligomer and a major tetramer peak. Western blot analysis of chromatographic fractions showed that cellular TK1 protein in both ALL and CMT dogs, and to some extent serum TK1 from ALL dogs, correlated with activity profiles, but a large fraction of inactive TK1 protein was detected in CMT.

CONCLUSIONS

Serum TK1 protein and activity levels were significantly higher in CMT than in healthy dogs. Size exclusion chromatography demonstrated major differences in the molecular forms of sTK1 in ALL, healthy, and CMT dogs, with a large fraction of inactive TK1 protein in CMT. Our results showed that the sTK1 protein assay can differentiate benign tumors (early stage tumors) from healthy more efficiently than sTK1 activity assay. This preliminary data supports that sTK1 protein assay is clinically useful. Further studies are needed to evaluate the diagnostic or prognostic role of serum TK1 protein in CMTs.

Overall survival and clinicopathological characteristics of patients with breast cancer in relation to the expression pattern of HER-2, IL-6, TNF-α and TGF-β1

The present study was conducted to investigate the prognostic significance of co-expression patterna of HER-2, IL-6, TNF-a and TGF-β1 in breast cancer, by correlating the number of markers with positive expression with clinicopathological characteristics indicative of tumor progression and overall survival. One hundred thirty consecutive patients with primary breast cancer were prospectively included and evaluated. Serum concentrations of the above markers were measured by ELISA. Median split was used to subdivide patients with marker positive or negative expression. The presence of ≥ 3 positive markers was independently associated with extended lymph node (>3) involvement (aOR, 11.94, p=0.001) and lymphovascular invasion (aOR, 12.04, p=0.018), increasing the prognostic significance of each marker considered separately. Additional prognostic information regarding survival was also provided; as the number of positive markers increased, a gradually reduction of survival time was observed. In addition, patients with 4 positive markers had significantly shorter survival (25 vs 39 months, p=0.006) and a more than 4 fold increased risk of death (aHR, 4.35, p=0.003) compared to patients with 3 positive markers. Our findings suggest that the coexpression pattern of these four markers could be used clinically as a useful marker for tumor extension and outcome of breast cancer.

The significance of CA15-3 in breast cancer patients and its relationship to HER-2 receptor status

Breast cancer is estimated to be the most common malignancy affecting women in Iraq. The cancer antigen CA 15-3 has been used as a possible serum marker of occult and recurrent breast carcinoma, either alone or in combination with other tumor markers such as HER2/neu, that has evolved as a major classifier of invasive breast cancer and target of therapy for the disease. ELISA, used to evaluate serum levels of CA15-3 and immuno-histochemistry staining technique, was used to establish the HER2/neu status. The results of this study indicate an increased level of CA15-3 in breast cancer patients (29.02+/-1.79 IU/ml) as compared to both women with benign tumor and healthy controls (13.78+/-1.24 and 8.92+/-0.48 IU/ml, respectively), and that this increase is associated to advanced stages. Patients with HER2/neu positive malignancies show elevated serum CA15-3 (37.09+/-2.55 IU/ml), as well as patients who developed recurrence (40.75+/-2.11 IU/ml). Our data study suggests that higher levels of CA 15-3 would be a reliable prognostic marker as they were directly related to advanced stages and recurrence. In addition persistent elevation of CA 15-3 was associated to HER2/neu positivity in breast cancer patients.

Serum HER2 supports HER2-testing in tissue at the time of primary diagnosis of breast cancer

AIM

HER2 in tissue is of high prognostic value. Soluble HER2, the extracellular domain (ECD), has been suggested to be a helpful biomarker. We investigated whether there is a relationship between HER2 ECD and HER2 in tissue and whether this relationship could be used for diagnostic purposes.

METHODS

HER2 ECD was measured in healthy individuals (N=283, 184 females, 99 males), in patients with history of breast cancer (BC) with no evidence of disease (N=249) as well as in BC patients before any treatment (N=565). HER2 in tissue was determined by immunohistochemistry and HER2 ECD was analyzed by immunoassay.

RESULTS

HER2 ECD levels were higher in healthy men than in healthy women (medians 12.9 ng/mL vs. 9.9 ng/mL, p<0.001). We observed an age dependency in women that means the older the women the higher the HER2 ECD level. In treated BC patients there was only a weak difference between younger and older women. For patients without distant metastases as well as patients with metastatic disease we observed a correlation of HER2 in serum and tissue. The median concentrations of HER2 ECD were 11.7 ng/mL (13.2 ng/mL) for the HER2-negative (HER2-positive) patients in the non-metastatic-group (p<0.001) and 11.9 ng/mL (16.0 ng/mL) in the metastatic-group (p=0.01). Using a cut-off of 30 ng/mL the HER2 in tissue was always positive, corresponding to a specificity of 99.8% and a sensitivity of 10.3%.

CONCLUSIONS

There is a strong correlation between HER2 ECD and HER2 in tissue. HER2 ECD supports the HER2 testing in tissue and may reveal false-negative tissue findings.

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.

Elevated levels of serum tumor markers CA 15-3 and CEA are prognostic factors for diagnosis of metastatic breast cancers

To investigate the prognostic value of tumor markers, cancer antigen 15-3 (CA 15-3) and carcinoembryonic antigen (CEA) levels at diagnosis of systemic recurrence. After primary treatments of locoregional breast cancers, serum CA 15-3 and/or CEA concentrations were regularly measured, and systemic recurrences were identified in 351 patients between January 1999 and December 2009. The association between tumor marker levels at systemic recurrence and survival were investigated by univariate and multivariate analyses. Elevated CA 15-3 and CEA levels were identified in 194 of 349 (55.6 %) and 111 of 308 (36.0 %) patients, respectively, at diagnosis of systemic recurrence. Elevated levels of CA 15-3 and CEA were correlated with visceral or multiple recurrences and elevated preoperative levels. Elevation of CA 15-3 was more prominent in younger patients and in primary node-positive tumors, while CEA was elevated in older patients at diagnosis and in estrogen receptor (ER)-positive tumors. Elevated tumor markers as well as ER negativity, short disease-free interval, and advanced stage at initial diagnosis showed independent prognostic significance on multivariate analysis. Among 306 patients for whom levels of both tumor markers at recurrence were available, 106 patients without elevation of either marker showed significantly better overall survival than those with elevated levels of either one or both markers, and the significance persisted in multivariate analysis. Elevated serum CA 15-3 and CEA levels at recurrence suggest increased tumor burden and may be prognostic for survival for metastatic breast cancer patients.

Correlation study of Carcino Embryonic Antigen & Cancer Antigen 15.3 in pretreated female breast cancer patients

Carcino Embryonic Antigen (CEA) and Cancer Antigen 15.3 (CA15.3) are the most common tumor markers in breast cancer patients. Measurement of circulating tumor markers is a non-invasive quantitative method. Serum levels of CEA and CA 15.3 were studied in female breast cancer patients prior to treatment. To evaluate the utility of these markers, 207 Breast carcinoma patients belonging to all the stages were considered. Healthy age matched 75 female individuals formed the control group. The serum levels of CEA and CA 15.3 were analyzed by Enzyme Linked Immunosorbent Assay (ELISA). Results were taken and compared with stages, tumor size, node and grade. The serum CA 15.3 levels were significant in all the study parameters whereas serum CEA levels showed no significant changes with any of the parameters. Measurement of serum CA 15.3 levels showed significant correlation (24.8%) with advanced stages and larger tumor sizes, whereas serum CEA levels did not show any significant correlation in breast cancer patients prior to treatment.

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.

Impact of Serum HER2 Levels on Survival and Its Correlation with Clinicopathological Parameters in Women with Breast Cancer

Purpose

The aims of our study were to assess the correlation between serum HER2 and clinicopathologic factors, the effect of serum HER2 on survival rate, and the effect of changes in serum HER2 levels between pre- and post-adjuvant chemotherapy on survival rate.

Methods

The study subjects, 200 women with breast cancer, were a subset of patients operated on between January 2005 and December 2006. We evaluated changes in serum HER2 levels between pre- and post-adjuvant chemotherapy.

Results

Being estrogen receptor (ER) negative was also correlated with high serum HER2 (p=0.017). The number of patients with changes in serum HER2 (>20% increased level during the follow-up period) was correlated with advanced T-stage (p=0.010), advanced American Joint Committee on Cancer (AJCC) stage (p=0.015) and poor histologic grade (p=0.001). Univariate analysis for prognostic factors associated with disease-free survival (DFS) revealed that the difference in DFS between those with serum HER2 level <15 ng/mL and those with levels ≥15 ng/mL was statistically significant (p=0.0129) and the changes in serum HER2 levels were also statistically significant (p=0.001). Prognostic factors associated with overall survival revealed that the changes in serum HER2 levels between pre- and post-adjuvant chemotherapy were statistically significant (p=0.0012).

Conclusion

Serum HER2 level is associated with a more advanced degree of axillary lymph node involvement and associated with ER negativity. And Changes in serum HER2 levels are associated with more advanced AJCC staging and histologic tumor grade. There are significant associations between serum HER2 level, changes in serum HER2 levels and 5-year DFS.

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.

Association between AgNORs and Immunohistochemical Expression of ER, PR, HER2/neu, and p53 in Breast Carcinoma

Settings. Despite the limited diagnostic utility of AgNORs (argyrophilic nucleolar organiser region-associated proteins) for individual breast lesions, AgNOR analysis bears a significant potential for characterizing cell proliferative activity of breast lesions. Methodology. The present study investigated the relationship between mean AgNORs count and immunohistochemical expression of ER, PR, HER2/neu, and p53 in breast carcinoma in serial paraffin sections from 137 breast carcinomas. Twenty control cases of benign breast lesions were included. Results. Mean AgNOR counts correlated significantly inversely with hormone estrogen receptors (ER), Progesterone receptors (PR), and p53 immunohistochemical expression, denoting P values of 0.05, 0.01, and 0.001, respectively. No significant correlation was found between mean AgNOR counts and HER2/neu, P = 0.9. Mean AgNOR count was significantly higher in grade II tumor cells. We conclude that mean AgNOR counts correlate with ER, PR, and P53 tumor markers in breast carcinomas. Conclusion. We recommend the use of mean AgNOR count for accurate reporting of breast carcinomas, as well as prediction of ER, PR, and P53 in routine paraffin sections.

Tumor markers in metastatic breast cancer subtypes: frequency of elevation and correlation with outcome

BACKGROUND

Little is known about the correlations between tumor markers (TMs), breast cancer subtypes, site(s) of metastasis and prognosis.

METHODS

Women diagnosed with metastatic breast cancer were included. Breast cancer subtypes were defined as LuminalA, LuminalB, LuminalHer2, Her2, Basal and non-Basal triple negative (TN). Levels of elevation of TM values [cancer antigen 15-3 (CA 15-3), carcinoembryonic antigen (CEA) and cancer antigen 125 (CA 125)] among the subtypes were analyzed. Site(s) of metastasis and outcomes were captured.

RESULTS

Eight hundred and ten patients were included. Luminal subtypes were associated with an elevation in at least one TM: 90.8% of LuminalHer2+, 90% of LuminalB and 88.6% of LuminalA. TMs were less frequently elevated in Basal (74.1%) and non-Basal TN (71.4%) cases (P < 0.001). CA 15-3 was the most frequently elevated TM. The incidence of TM elevation did not differ between patients with solitary versus multiple metastatic sites. Breast cancer-specific survival (BCSS) was significantly worse for patients with elevated TMs (P = 0.001).

CONCLUSIONS

TM elevation of CA 15-3, CEA and/or CA 125 was documented in the majority of patients with metastatic breast cancer with CA 15-3 occurring most commonly. Luminal subtypes expressed elevated TMs significantly more frequently compared with the non-Luminal groups. TM elevation was not different between the different sites of metastasis. Overall, elevated TMs predicted a worse BCSS.

Integrated microfluidic platform for the electrochemical detection of breast cancer markers in patient serum samples

A microsystem integrating electrochemical detection for the simultaneous detection of protein markers of breast cancer is reported. The microfluidic platform was realized by high precision milling of polycarbonate sheets and features two well distinguishable sections: a detection zone incorporating the electrode arrays and the fluid storage part. The detection area is divided into separate microfluidic chambers addressing selected electrodes for the measurement of samples and calibrators. The fluidic storage part of the platform consists of five reservoirs to store the reagents and sample, which are interfaced by septa. These reservoirs have the appropriate volume to run a single assay per cartridge and are manually filled. The liquids from the reservoirs are actuated by applying a positive air pressure (i.e.via a programmable syringe pump) through the septa and are driven to the detection zone via two turning valves. The application of the realised platform in the individual and simultaneous electrochemical detection of proteic cancer markers with very low detection limits are demonstrated. The microsystem has also been validated using real patient serum samples and excellent correlation with ELISA results obtained.

Prognostic role of serum cancer antigen 15-3 in breast cancer patients with isolated bone metastases

OBJECTIVE

To investigate the association between cancer antigen (CA) 15-3 and clinicopathological parameters in patients who had breast cancer with isolated bone metastases at the time of diagnosis and to analyse the effect on clinical outcomes.

METHODS

Between June 2004 and January 2007, the data of 129 consecutive patients were examined.

RESULTS

Elevated CA 15-3 levels were associated with poor disease-free survival (p = 0.001) and overall survival (p = 0.006). In multivariate analysis, serum CA 15-3 level (p = 0.003) was found to be an independent factor in overall survival.

CONCLUSION

Elevated CA 15-3 level is a useful parameter for predicting clinical outcomes.

The role of surgery in breast cancer patients with isolated bone metastases at the time of diagnosis

BACKGROUND

Surgery for the primary tumor in breast cancer patients with synchronous isolated bone metastasis is applied for palliation. The aim was to determine whether surgical removal of the primary tumor provides a better survival and disease progression.

METHODS

Forty-four patients were diagnosed between the dates June 2004 and January 2007 and these patients are classified according to the removal of the primary tumor or not. Patients and tumor characteristics, removal of the primary tumor, and response to systemic therapy are examined as the factors that were affecting overall survival and time to progression of the disease.

RESULTS

The median follow-up time was 37.5 months. Mean time to progression and overall survival was longer for the patients who received surgery than the patients who did not (20.4 vs. 18.4 months and 57.6 vs. 44.5 months, respectively), but these were not significant (P = 0.58, P = 0.39). In multivariate analysis, response to systemic treatment [(P = 0.03), hazard ratio = 0.44, 95% confidence interval = 0.20-0.93] was independent factor associated with overall survival.

CONCLUSION

The response to systemic therapy is the major factor on survival in the breast cancer patients with isolated bone metastasis. Excision of the primary tumor has no effect on time to progression and overall survival.

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.

Clinical significance and prognostic value of serum sHER-2/neu levels in patients with solid tumors

The purpose of this study was to determine HER-2/neu in the serum of patients with solid tumors and to investigate its potential usefulness in predicting the clinical course of the disease. At the same time, we compared the ability of serum HER-2/neu, CA15.3, CA12-5, CA19-9, carcino embryonic antigen (CEA), and alpha-feto-protein (AFP) in breast, colorectal, and lung cancer patients. Forty, thirty-six, and twenty-three patients with lung, colon and breast cancer were included in this study, respectively. Serum levels of HER-2/neu, CA15.3, CA12-5, CA19-9, CEA, and AFP were measured. Her-2 neu levels were significantly higher in the breast cancer groups than colorectal and lung cancer and controls groups (P < 0.01). There is no significant difference when compared with others groups (P > 0.05). There was a positive correlation between the HER-2/neu and CA15-3 values in breast cancer groups. We found 0.75(0.59-0.90) for Her-2/neu from the area under the curve (AUC). P-value for breast cancer is 0.003, and we discovered that 9 ng/ml was the best inersection point. In this situation, we calculated that sensitivity was 65.2%, specificity was 100%, positive predictive value was 100%, negative predictive value 75.8%, and accuracy was 83.4%. These findings indicate that serum HER2/neu levels are clinically valuable in monitoring metastatic breast cancer and non-small cell lung cancer patients. Prognosis of breast cancer provides an additional value over the commonly used CA15-3 test. Measurements of levels of serum HER-2/neu provide prognostic and predictive information to the clinician and can especially be used for monitoring metastatic breast cancer patients. Further clinical validation is needed to confirm these findings.

Determination of HER2 status using both serum HER2 levels and circulating tumor cells in patients with recurrent breast cancer whose primary tumor was HER2 negative or of unknown HER2 status

Introduction

At the time when metastatic disease is identified, assessment of human epidermal growth factor receptor (HER)2 status might help to optimize treatment decisions if HER2 status was not determined at first diagnosis and if HER2 positivity has been acquired during disease progression. Within this context, determination of serum HER2 or evaluation of HER2 status in circulating tumor cells (CTCs) may be of clinical relevance because metastatic tissue may be difficult to obtain for analysis as a result of its localization. The aim of this study was therefore to determine the HER2 status in serum and corresponding CTCs in patients with metastatic breast cancer whose primary tumors were HER2 negative or of unknown HER2 status.

Methods

Blood samples were obtained from 77 metastatic breast cancer patients with negative (n = 44) or unknown (n = 33) HER2 status. Serum HER2 was determined using a commercial HER2/neu ELISA kit. CTCs were detected by slide-based assay using immunomagnetic enrichment and characterized by phenotyping and genotyping. Alternatively, a commercial kit, based on RT-PCR, was used to detect and characterize CTCs.

Results

Twenty out of 77 patients with metastatic disease had elevated serum levels of HER2. Blood samples could be analyzed for the presence of CTCs in 67 patients. Eight out of 21 patients with detectable CTCs exhibited HER2 amplification. Twenty-three out of 77 patients were HER2 positive using at least one method. Concordance between HER2 status of CTCs and serum HER2 was observed in 15 of 21 patients (71%). In six patients conflicting results were obtained. Three patients with elevated serum HER2 status had HER2-negative CTCs, whereas three patients with HER2-positive CTCs had normal serum HER2 levels.

Conclusion

A subgroup of patients with initially negative or unknown HER2 status can have elevated serum HER2 levels and/or HER2-positive CTCs at the time of development of metastatic disease. Although only a small number of patients were studied, our observations are of clinical relevance because, currently, these patients do not have access to HER2-targeted therapy.

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.

Serum EGFR and serum HER-2/neu are useful predictive and prognostic markers in metastatic breast cancer patients treated with metronomic chemotherapy

BACKGROUND

Metronomic chemotherapy has been demonstrated to be of value in patients with advanced breast cancer. No reliable markers of response are available. In breast tumor, HER-2/neu is a prognostic factor, whereas no definite data exist for EGFR. The aim of the study was to evaluate the prognostic and predictive role of serum HER-2/neu and serum EGFR in breast cancer patients treated with low-dose chemotherapy.

METHODS

Serum levels of HER-2/neu (n = 135) and of EGFR (n = 113) were prospectively determined before the start of chemotherapy, after 2 months of treatment, and when progressive disease was diagnosed.

RESULTS

Elevated (>15 ng/mL) serum HER-2/neu before the start of chemotherapy was not associated with response rate, whereas elevated serum HER-2/neu at 2 months was significantly associated with reduced long-term clinical benefit (24 weeks) (P < .001), as well as changes in HER-2/neu levels between baseline and 2 months (P < .0001). Multivariate analysis identified a >or=20% increase of serum HER-2/neu as an independent factor for progression-free survival (PFS). Kinetics of serum HER-2/neu were significantly associated with PFS (P < .0001) and overall survival (OS) (P = .015). Low baseline serum levels of EGFR (<45 ng/mL) were predictive of reduced response rate both at 2 months (P = .031) and after 24 weeks (P = .022). Moreover, they were significantly associated with reduced PFS (P = .016) and OS (P = .015).

CONCLUSIONS

Serum HER-2/neu and EGFR may represent useful markers for early prediction of probability of response, PFS, and OS in patients with advanced breast cancer treated with metronomic chemotherapy.

Lymph node status as a guide to selection of available prognostic markers in breast cancer: the clinical practice of the future?

Prognosticators evaluating survival in breast cancer vary in significance in respect to lymph node status. Studies have shown e.g. that HER2/neu immunohistochemistry or HER2/neu gene amplification analysis do perform well as prognosticators in lymph node positive (LN +) patients but are less valuable in lymph node negative (LN -) patients. We collected data from different studies and tried to evaluate the relative significance of different prognosticators in LN+/LN- patient groups. In LN+ patients HER2/neu and E-cadherin immunohistochemistry were the statistically most significant prognosticators followed by proliferation associated features (mitotic counts by SMI (standardised mitotic index) or MAI (mitotic activity index), or S-phase fraction). Bcl-2 immunohistochemistry was also significant but p53 and cystatin A had no significance as prognosticators. In LN- patients proliferation associated prognosticators (SMI, MAI, Ki-67 index, PCNA immunohistochemistry, S-phase fraction) are especially valuable and also Cathepsin D, cystatin A, and p53 are significant, but HER2/neu or bcl-2, or E-cadherin less significant or without significance. We find that in studies evaluating single prognosticators one should distinguish between prognosticators suitable for LN+ and LN- patients. This will allow the choice of best prognosticators in evaluating the prospects of the patient. The distinction between LN+ and LN- patients in this respect may also be of special value in therapeutic decisions.

Purification and characterization of recombinant extracellular domain of human HER2 from Escherichia coli

The human epidermal growth factor receptor 2 (HER2) is a member of the epidermal growth factor receptor (EGFR) family, and it plays an important role in the development of many human adenocarcinomas. The extracellular domain (ECD) of HER2 is an ideal target for therapeutic approaches. In order to obtain large quantities of active HER2 ECD protein for biochemical and structural analysis and for detecting anti-HER2 ECD antibodies in serum, a systematic assessment of optimal parameters for the refolding of the glutathione S-transferase (GST) fusion protein was carried out. After the GST-HER2 ECD inclusion bodies were solubilized with denaturation buffer containing 8M urea, an approach was then used to optimize refolding parameters. This approach utilized dilution of denatured and reduced GST-HER2 ECD into different refolding buffers using orthogonal design method. Optimal refolding was obtained in an alkaline buffer containing reduced and oxidized glutathione, and subsequent incubation at 4 degrees C for 24h. After purification with glutathione Sepharose 4B and PreScission protease cleavage of the fusion protein, 8.9mg of recombinant HER2 ECD was obtained from 1L of Escherichia coli. Rabbit polyclonal antibodies against HER2 ECD were obtained. The purified protein was found to be immunogenic and useful for immunodiagnostic studies of serum HER2 ECD and its antibodies by using enzyme-linked immunosorbent assay (ELISA).

Serial Plasma Osteopontin Levels Have Prognostic Value in Metastatic Breast Cancer

PURPOSE

Osteopontin is a malignancy-associated protein measurable in blood and tumor tissue. To evaluate its prognostic value in advanced disease, we conducted a prospective clinical study measuring serial osteopontin plasma levels in women with metastatic breast cancer throughout the course of their disease.

EXPERIMENTAL DESIGN

One hundred fifty-eight women with newly diagnosed metastatic breast cancer were enrolled in the study. Plasma osteopontin was measured using our validated ELISA, at baseline and every 3 to 12 weeks during and after therapy until death. Multivariate time-dependent survival analyses were conducted using models that right censored patient outcomes 3, 6, and 12 months after the last known osteopontin measurement.

RESULTS

Osteopontin was measured in 1,378 samples (median, 9 per patient). Ninety-nine patients had elevated baseline osteopontin (median, 177 ng/mL; range, 1-2,648 ng/mL). In univariate analysis, elevated baseline osteopontin was associated with short survival (P = 0.02). In a multivariate model incorporating standard prognostic factors, baseline osteopontin was significantly associated with survival duration (relative risk, 1.001; P = 0.038). Metastasis-free interval, visceral metastases, and Eastern Cooperative Oncology Group status 2 to 4 also retained significance. In a multivariate model incorporating standard prognostic factors and changes in sequential osteopontin levels, an osteopontin increase of >250 ng/mL at any time was the variable with the most prognostic value for poor survival (relative risk, 3.26; P = 0.0003), and poor Eastern Cooperative Oncology Group status also retained significance.

CONCLUSIONS

This is the first study to show that in women with metastatic breast cancer, increases in osteopontin levels over time are strongly associated with poor survival. Sequential monitoring of osteopontin may have use in making treatment decisions for these patients.

Serum HER2 as a response indicator to various chemotherapeutic agents in tissue HER2 positive metastatic breast cancer

PURPOSE

The aim of study was to evaluate the usefulness of serum HER2 as a therapeutic response indicator in patients with HER2 positive metastatic breast cancer (MBC).

MATERIALS AND METHODS

The levels of serum HER2 and CA15.3 were assayed in 148 serial serum samples from 50 HER2 positive MBC patients at both the baseline and follow-ups. The changes in the levels of serum HER2 and CA15.3 in relation to the tumor responses to the various chemotherapy regimens were monitored.

RESULTS

The levels of serum HER2 and CA15.3 were elevated in 82% and 62% of tissue HER2 positive patients, respectively, prior to therapies, with the changes in both tumor markers showing statistical significance in relation to the tumor responses (p<0.01) in patients with elevated baseline serum markers.

CONCLUSION

The level of serum HER2 could be a valuable response indicator, not only for trastuzumab containing therapy, but also for other common MBC chemotherapeutic agents. Also, as it is more frequently elevated, the serum level of HER2 may also be a more useful tumor marker than CA15.3 in HER2 positive MBC.

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.

Metastatic breast cancer: overview of treatment

Patients with metastatic breast cancer have a median survival of 2 to 3 years. Twenty percent of the patients who present with bone-only metastasis will be alive at 5 years from diagnosis. Current therapies are aimed at improving the quality of life, symptom control, and prolongation of survival. Newer endocrine and chemotherapeutic drugs are available to the medical oncologist for care of patients with metastatic breast cancer. We will briefly review the new advances in the treatment of metastatic breast cancer.

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.