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Background: Gene amplification or overexpression of human epidermal growth factor receptor HER2/ErB2 is seen in 25-30% of patients with breast cancer and is related to an aggressive disease. The mechanism behind the HER2 gene amplification is unknown, but it may be caused by continuous stimulation and activation. We hypothesised that autoantibodies against EGFR might have a stimulatory effect. To investigate this we developed a quantitative method to measure autoantibodies against EGFR in serum (S-EGFRAb). Methods: Serum samples from primary breast cancer patients were selected based on the degree of HER2 protein and gene amplification in the cancer tissue. Fifty patients had low levels of HER2 (≤16 ng/mg total protein) and no HER2 gene amplification; 43 patients had high levels of HER2 (≥200 ng/mg total protein) and HER2 gene amplification. Serum was also collected from controls consisting of 50 healthy age-matched women. An ELISA was developed to measure S-EGFRAb quantitatively. Results: No significant differences in S-EGFRAb concentrations were seen between patients with high and low levels of HER2 or between the patients and the controls. Furthermore, no significant correlations were observed between S-EGFRAb and stage, differentiation state, age or prognosis. A negative correlation (p=0.0022) was found between S-EGFRAb and disease free survival in the group of patients with relapse or death. Conclusions: S-EGFRAb can be measured accurately using the ELISA we developed. We conclude that autoantibodies against EGFR do not seem to be associated with the HER2 gene amplification phenomenon. [ABSTRACT FROM AUTHOR]

Background: Serum HER2 (S-HER2) was approved in 2003 by the US Food and Drug Administration (FDA) for monitoring trastuzumab treatment in tissue HER2 positive breast cancer patients. Information of the value of S-HER2 is scarce. We hypothesised that S-HER2 would reflect the clinical effect of trastuzumab. Methods: We followed 48 patients eligible for trastuzumab treatment for up to 6 years or until death. S-HER2 was measured on an ADVIA Centaur System and S-Trastuzumab was measured by an in-house developed fluorescent enzyme immunoassay system on the ImmunoCap 100. Results: A decrease in S-HER2 of ≥ 20% was correlated to no progression in the disease in 20 out of 21 clinical courses (p<0.0001). An increase in S-HER2 of ≥ 20% was correlated to progression in the disease in 40 out of 44 clinical courses (p<0.0001). Patients with no recurrence after trastuzumab treatment (n=18) had a median S-HER2 concentration of 10.5 μg/L, whereas patients alive with recurrence (n=13) had a median S-HER2 of 20.1 μg/L (p=0.002). Patients who died prompted by recurrence (n=17) had a median S-HER2 of 232.4 μg/L at latest measurement before death (p=<0.0001) compared to patients without recurrence. In two patients with S-HER2 values above 1000 μg/L the concentrations of S-trastuzumab were measured below the target trough concentration in serum of 10 mg/L. Conclusions: Decreasing values of S-HER2 predicts response to treatment whereas increasing levels predict resistance. S-HER2 above 1000 μg/L warns that standard doses of trastuzumab may be insufficient as reflected by low concentrations of S-trastuzumab. [ABSTRACT FROM AUTHOR]

Background: In this study the total and phosphorylated amount of epidermal growth factor receptor 1 (EGFR) and 2 (HER2) were measured together with EGFR ligands in tissue samples of breast cancer patients in order to investigate interrelations and possible prognostic values. Methods: Samples of malignant and non-cancer autologous reference tissue were collected from 415 breast cancer patients. The tissue samples were cut and either paraffin-embedded or homogenized in a lysis buffer to extract the proteins. HER2 was measured using both immunohistochemistry (IHC)/fluorescence in situ hybridization (FISH) and ADVIA Centaur. Phosphorylated HER2 and EGFR (pHER2, pEGFR), total EGFR and the ligands: epidermal growth factor (EGF), transforming growth factor-α (TGFα), amphiregulin (AREG), heparin-binding EGF-like growth factor (HB-EGF), betacellulin (BTC) and epiregulin (EREG) were measured using the Luminex. Results: The HER2 positivity rate was determined to be 25.2% by the Centaur method vs. 15.8% by IHC and FISH. HER2, HB-EGF, TGFα and AREG were upregulated in cancer tissue as compared with autologous reference tissue while EGFR, pEGFR and EGF were downregulated (p<10-6). pEGFR in autologous reference tissue was negatively correlated to the number of positive lymph nodes and to the tumor size (p=0.0007 and p=0.001, respectively) and furthermore, decreased in the group of mastectomy operated patients as compared with the lumpectomy group (p<10-6). HB-EGF in cancer tissue was positively associated with high grade tumors (p<10-6) and pHER2, HB-EGF and BTC were associated with poor disease free survival (p=0.017, p=0.012 and p=0.0026, respectively). Conclusions: Our study demonstrated a profound activation of the EGFR system. HB-EGF was increased by factor 10 in cancer tissue and related to the biological aggressiveness of the tumors, and pHER2, HB-EGF and BTC were associated with poor clinical outcome. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to determine the positive predictive value (PPV) of positive serum human epidermal growth factor receptor-2 (HER-2) for monitoring women with breast cancer following diagnosis and treatment in a routine clinical setting. Methods: Serum HER-2 was measured in 1348 patients with breast cancer: 837 during routine oncology clinic visits and 511 following new diagnosis. All patients with positive serum HER-2, 1/5 of negative patients from the oncology clinic, and all the newly diagnosed were followed; a total of 862 patients. Serum HER-2 was measured using the Bayer ADVIA Centaur assay. Tissue HER-2 was determined using immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). IHC +3 or IHC +2 and FISH>2.0 were positive. Patients were considered to have positive serum HER-2 when at least two values were >15 ng/mL. Recurrence, progression and regression were diagnosed according to usual clinical practice. Serum HER-2 concentrations did not contribute to diagnostic decision-making or selection of treatment. Results: From January 2004 to January 2009, 149 patients were found to have positive serum HER-2. Of these, 35 were tissue HER-2 positive at surgery, 69 tissue-negative and 45 were not determined. Fifty-five of 149 that were serum HER-2 positive (37%, 95% CI: 29–45) had metastases. Among the 35 tissue-positive patients, 25 had recurrence in the form of metastases and there was good correlation between recurrence/progression and increase in serum HER-2 (p<0.0003). There was also a high correlation between effect of treatment and decline in serum HER-2 (p<0.0003). Of the 69 tissue-negative patients, 29 had recurrence in the form of metastases, and there was good correlation with serum HER-2 levels (p<0.000004). In this routine application of serum HER-2, the PPV for metastases recurrence detection in both tissue-positive and tissue-negative was 54 of 104 (52%, 95% CI: 42%–62%), in tissue-positive 25 of 35 (71%, 95% CI: 54%–85%), in tissue-negative 29 of 69 (42%, 95% CI: 30%–54%). The lead time of increases in serum HER-2 before recurrence could be determined in ten tissue-positive patients was 3–24 months (mean 11.3 months), when compared to standard clinical imaging methods. Conclusions: Serum HER-2 is a useful marker for the detection of recurrence of breast cancer and for monitoring the effect of treatment, especially in tissue HER-2 positive patients. Clin Chem Lab Med 2009;47:1117–23. [ABSTRACT FROM AUTHOR]

Background: The epidermal growth factor receptor HER2 is overexpressed or amplified in 25%–30% of patients with breast cancer. The mechanism behind HER2 amplification is unknown, but may be a patho-physiological phenomenon caused by continuous stimulation and activation of the HER1-4 system. We have mapped the protein concentrations of HER1-4 in breast cancer tissue, autologous reference tissue, normal breast tissue and serum samples, to see whether non-cancer cells from these patients express a protein profile indicating general activation. Methods: Tissue samples from malignant and adjacent normal breast tissue (autologous reference tissue) were collected from 118 women consecutively admitted for surgical treatment of breast cancer. In addition, 26 samples of normal breast tissue were collected from healthy women having breast reduction surgery. The tissue samples were homogenized and the proteins extracted. The tissue and serum concentrations of HER1-4 were determined quantitatively using a commercially available enzyme linked immunosorbent assay (ELISA) method. Results: HER1 was down regulated in cancer tissue when compared to autologous reference tissue (p=8×10−6), while HER2 (p<10−7) and HER3 (p=3×10−5) were up regulated. Comparing autologous reference tissue with normal tissue showed down regulation of HER1 (p=0.122) and up regulation of HER2 (p=10−6), HER3 (p<10−7) and HER4 (p<10−7). Furthermore, we observed that correlations between the receptor combinations HER1-2, HER1-3 and HER1-4 were maintained from normal breast tissue to autologous reference breast tissue, but were lost in cancer tissue. Conclusions: We suggest that these findings indicate that breast cancer is a systemic disease where the HER1-4 system in autologous reference tissue is continuously activated, thus favoring the subsequent development of cancer. Clin Chem Lab Med 2009;47:977–84. [ABSTRACT FROM AUTHOR]

Background: The level of HER-2/neu in breast cancer cells is normally measured by immunohistochemistry (IHC) and/or fluorescence in situ hybridization (FISH). It determines whether patients should be treated with trastuzumab (Herceptin®). In this study, HER-2 protein in breast cancer tissue was measured using a quantitative method. Methods: Tissue samples of malignant and adjacent benign breast tissue were collected from 118 consecutive women admitted for surgical treatment of breast cancer. The HER-2 protein concentration was determined by 2 HER-2 assays: ELISA and the Bayer ADVIA Centaur assay. Paraffin-embedded tissue sections of the corresponding tumors were analyzed by IHC and FISH. Results: Increased HER-2 concentrations in cancer tissue were found compared to autologous reference tissue (p<0.0001, Wilcoxon test) and normal breast tissue (p<0.0001, Mann-Whitney test). Good concordance rates were observed between the methods: 95.8% for IHC and FISH; 86.4% for IHC and ELISA; and 87.3% for FISH and ELISA. The HER-2 positivity rate was determined to 26.3% by ELISA, 12.7% by IHC and 16.9% by FISH. No correlation was found with tumor grade, axillary node status or serum HER-2 levels. Conclusions: Detection of HER-2 overexpression by measuring HER-2 in tissue extracts by ELISA seems to be more sensitive than IHC and FISH. This suggests that some patients deprived of Herceptin treatment may benefit from this treatment and may also explain the conversion phenomenon from HER-2-negative to HER-2-positive observed in relapse and metastatic disease. Clin Chem Lab Med 2007;45:177–82. [ABSTRACT FROM AUTHOR]