William J. Gullick

c-erbB-2 oncoprotein expression in primary and advanced breast cancer.

Immunoreactivity for c-erbB-2 oncogene product expression has been investigated in patients with breast cancer using the polyclonal antibody 21N. Three series of patients were studied, 602 presenting with primary operable cancer, 57 with stage 3 and 123 with stage 4 disease. Representative tissue sections of each primary tumour were stained using a standard immunoperoxidase technique. Invasive tumour membrane immunoreactivity was assessed and identified in 15% of patients with primary operable cancer and 20% in the advanced breast cancer group. The results demonstrate a relationship between poorer survival and oncogene expression in all three patient groups. Patients in the primary operable cancer group with membrane oncoprotein expression had a poorer outcome, 35% 10-year survival, compared with those in which membrane expression was absent, 55% 10-year survival. The median survival of patients with stage 3 disease with c-erbB-2 membrane positivity was 17 months compared to 24 months with membrane negativity. In stage 4 disease median survival with membrane expression was 8.8 months compared to 19.7 months with no membrane expression. In addition in the series of primary cancers a correlation existed between histological grade and membrane immunoreactivity. Multivariate analysis showed histological grade to be a more powerful prognostic factor than c-erbB-2 protein expression. In conclusion, this study demonstrates, in a large series of patients presenting to one centre, that c-erbB-2 protein expression is a prognostic indicator in patients with primary operable and advanced breast disease.

Expression of the c-erbB-4/HER4 protein and mRNA in normal human fetal and adult tissues and in a survey of nine solid tumour types

The c‐erbB‐4/HER4 receptor belongs to the family of the type I growth factor receptors. Mouse monoclonal antibodies have been raised to the cytoplasmic domain of the c‐erbB‐4 receptor and characterized; the antibody HFR‐1 has been used to determine the pattern of expression of the c‐erbB‐4 protein immunohistochemically in formalin‐fixed, paraffin‐embedded adult and fetal tissues. The expression of c‐erbB‐4 mRNA was determined by using 35S‐labelled riboprobes and tissue in situ hybridization. c‐erbB‐4 is widely expressed in many adult and fetal tissues, including the lining epithelia of the gastrointestinal, urinary, reproductive, and respiratory tracts, as well as the skin, skeletal muscle, circulatory, endocrine, and nervous systems. The developing brain and heart notably express high levels of this receptor. The pattern of c‐erbB‐4 protein expression is also reported in a survey of common solid human cancers. Loss of expression was noted in 40–80 per cent of adenocarcinomas and up to 100 per cent of squamous cell carcinomas, whereas overexpression was observed in about 10–20 per cent of adenocarcinomas and astrocytomas. In general, the pattern of c‐erbB‐4 expression in normal tissues and cancers suggests that it tends to be associated with the differentiated compartment.

A monoclonal antibody recognizing human cancers with amplification/overexpression of the human epidermal growth factor receptor.

Epidermal growth factor receptor (EGFR) has attracted considerable attention as a target for cancer therapy. Wild-type (wt)EGFR is amplified/overexpressed in a number of tumor types, and several mutant forms of the coding gene have been found, with ΔEGFR, a deletion mutation lacking exons 2–7 of the external domain, being the most common and particularly associated with glioblastoma. We generated monoclonal antibodies (mAbs) against NR6ΔEGFR (mouse fibroblast line NR6 transfected with ΔEGFR). mAb 806 with selective reactivity for NR6ΔEGFR in mixed hemadsorption assays, fluorescence-activated cell sorting, Western blot, and immunohistochemistry was analyzed in detail and compared with mAbs 528 (anti-wtEGFR) and DH8.3 (anti-ΔEGFR). In xenograft tumors and molecularly pretyped glioblastomas, the reactivity pattern was as follows: 528 reactive with amplified and nonamplified wtEGFR; DH8.3 reactive with ΔEGFR; and 806 reactive with amplified/overexpressed wtEGFR (with or without ΔEGFR). In normal tissues, 528 but not DH8.3 or 806 was widely reactive with many organs, e.g., liver expressing high EGFR levels. In glioblastoma and non-CNS tumor panels, 806 was reactive with a high proportion of glioblastomas and a substantial number of epithelial cancers of lung and of head and neck. DH8.3 reactivity was restricted to ΔEGFR-positive glioblastoma. Thus, 806 represents a category of mAbs that recognizes tumors with EGFR amplification/overexpression but not normal tissues or tumors with normal EGFR levels. Our study also indicates that ΔEGFR is restricted to glioblastoma, in contrast to other reports that this mutation is found in tumors outside the brain.

Novel monoclonal antibody specific for the de2-7 epidermal growth factor receptor (EGFR) that also recognizes the EGFR expressed in cells containing amplification of the EGFR gene

In some respects, the EGFR appears to be an attractive target for tumor‐targeted antibody therapy: it is overexpressed in many types of epithelial tumor and inhibition of signaling often induces an anti‐tumor effect. The use of EGFR specific antibodies, however, may be limited by uptake in organs that have high endogenous levels of the wild type EGFR such as the liver. The de2‐7 EGFR (or EGFRvIII) is a naturally occurring extracellular truncation of the EGFR found in a number of tumor types including glioma, breast, lung and prostate. Antibodies directed to this tumor specific variant of the EGFR provide an alternative targeting strategy, although the lower proportion of tumors that express the de2‐7 EGFR restricts this approach. We describe a novel monoclonal antibody (MAb 806) that potentially overcomes the difficulties associated with targeting the EGFR expressed on the surface of tumor cells. MAb 806 bound to de2‐7 EGFR transfected U87MG glioma cells (U87MG.Δ2‐7) with high affinity (∼1 × 109 M−1), but did not bind parental cells that express the wild type EGFR. Consistent with this observation, MAb 806 was unable to bind a soluble version of the wild type EGFR containing the extracellular domain. In contrast, immobilization of this extracellular domain to ELISA plates induced saturating and dose response binding of MAb 806, suggesting that MAb 806 can bind the wild type EGFR under certain conditions. MAb 806 also bound to the surface of A431 cells, which due to an amplification of the EGFR gene express large amounts of the EGFR. Interestingly, MAb 806 only recognized 10% of the total EGFR molecules expressed by A431 cells and the binding affinity was lower than that determined for the de2‐7 EGFR. MAb 806 specifically targeted U87MG.Δ2‐7 and A431 xenografts grown in nude mice with peak levels in U87MG.Δ2‐7 xenografts detected 8 h after injection. No specific targeting of parental U87MG xenografts was observed. Following binding to U87MG.Δ2‐7 cells, MAb 806 was rapidly internalized by macropinocytosis and subsequently transported to lysosomes, a process that probably contributes to the early targeting peak observed in the xenografts. Thus, MAb 806 can be used to target tumor cells containing amplification of the EGFR gene or de2‐7 EGFR but does not bind to the wild type EGFR when expressed on the cell surface.

c-erbB3 and c-erbB4 expression is a feature of the endocrine responsive phenotype in clinical breast cancer.

We examined c-erbB3 and c-erbB4 mRNA expression in 47 primary breast cancer samples by simultaneous RT–PCR and have investigated correlations between these parameters and the expression of both ER and EGFR mRNA and protein as measured by RT–PCR and ICA and with Ki67 immunostaining. A direct association was found between c-erbB3 and c-erbB4 mRNA and ER marker status measured by either RT–PCR (c-erbB3 P=0.0003; c-erbB4 P=0.02) or ICA (c-erbB-3 P=0.002; c-erbB4 P=0.01). Inverse associations were seen between c-erbB3 and c-erbB4 mRNA marker status and EGFR membrane protein (c-erbB3: P=0.003; c-erbB4: P=0.003) and mRNA (c-erbB4: P=0.009) status. These associations were reinforced by Spearman Rank Correlation Tests. A significant relationship was seen between Ki67 and c-erbB4 mRNA status and level. Measurements of c-erbB3 protein levels in tumour samples removed from a further 89 patients of known response to endocrine therapy: (i) confirmed the relationship between c-erbB3 and ER and (ii) identified that patients whose ER positive tumours expressed high levels of c-erbB3 were most likely to benefit from endocrine measures. A non-significant trend was recorded between c-erbB3 levels and Ki67 immunostaining. These results clearly demonstrate that increased c-erbB3 and c-erbB4 expression appears to be associated with the prognostically-favourable ER phenotype.

Recommendations for HER2 testing in the UK

Determining the HER2 status of breast carcinomas is a prerequisite for the use of the monoclonal antibody trastuzumab (Herceptin®), which has recently been licensed for the treatment of metastatic disease. This necessitates a test based on archival material. The preferred analyses are immunohistochemistry with fluorescent in situ hybridisation (FISH) as a follow up test for ambiguous results. Guidelines have been developed for standardised, well controlled procedures for the provision of reliable results. A group of three reference laboratories has been established to provide advice, quality assurance, and materials, where needed.

Brown and white adipose tissues: intrinsic differences in gene expression and response to cold exposure in mice

Brown adipocytes dissipate energy, whereas white adipocytes are an energy storage site. We explored the plasticity of different white adipose tissue depots in acquiring a brown phenotype by cold exposure. By comparing cold-induced genes in white fat to those enriched in brown compared with white fat, at thermoneutrality we defined a “brite” transcription signature. We identified the genes, pathways, and promoter regulatory motifs associated with “browning,” as these represent novel targets for understanding this process. For example, neuregulin 4 was more highly expressed in brown adipose tissue and upregulated in white fat upon cold exposure, and cell studies showed that it is a neurite outgrowth-promoting adipokine, indicative of a role in increasing adipose tissue innervation in response to cold. A cell culture system that allows us to reproduce the differential properties of the discrete adipose depots was developed to study depot-specific differences at an in vitro level. The key transcriptional events underpinning white adipose tissue to brown transition are important, as they represent an attractive proposition to overcome the detrimental effects associated with metabolic disorders, including obesity and type 2 diabetes.

Expression of transforming growth factor alpha, amphiregulin and cripto-1 in human breast carcinomas.

The expression of three epidermal growth factor (EGF)-related peptides, transforming growth factor alpha (TGF-alpha), amphiregulin (AR) and cripto-1 (CR-1), was examined by immunocytochemistry (ICC) in 68 primary infiltrating ductal (IDCs) and infiltrating lobular breast carcinomas (ILCs), and in 23 adjacent non-involved human mammary tissue samples. Within the 68 IDC and ILC specimens, 54 (79%) expressed immunoreactive TGF-alpha, 52 (77%) expressed AR and 56 (82%) expressed CR-1. Cytoplasmic staining was observed with all of the antibodies, and this staining could be eliminated by preabsorption of the antibodies with the appropriate peptide immunogen. Cytoplasmic staining with all of the antibodies was confined to the carcinoma cells, since no specific immunoreactivity could be detected in the surrounding stromal or endothelial cells. In addition to cytoplasmic reactivity, the AR antibody also exhibited nuclear staining in a number of the carcinoma specimens. No significant correlations were found between the percentage of carcinoma cells that were positive for TGF-alpha, AR or CR-1 and oestrogen receptor status, axillary lymph node involvement, histological grade, tumour size, proliferative index, loss of heterozygosity on chromosome 17p or overall patient survival. However, a highly significant inverse correlation was observed between the average percentage of carcinoma cells that expressed AR in individual tumours and the presence of a point-mutated p53 gene. Likewise, a significantly higher percentage of tumour cells in the ILC group expressed AR as compared with the average percentage of tumour cells that expressed AR in the IDC group. Of the 23 adjacent, non-involved breast tissue samples, CR-1 could be detected by ICC in only three (13%), while TGF-alpha was found in six (26%) and AR in ten (43%) of the non-involved breast tissues. These data demonstrate that breast carcinomas express multiple EGF-related peptides and show that the differential expression of CR-1 in malignant breast epithelial cells may serve as a potential tumour marker for breast cancer.

C-erbB-3 in human breast carcinoma: expression and relation to prognosis and established prognostic indicators.

A series of 346 patients with primary operable breast cancer and a series of 145 patients with advanced breast cancer were investigated for c-erbB-3 protein expression using the monoclonal antibody RTJ1. Formalin-fixed, paraffin-embedded tumour samples were stained using a standard immunochemical method and staining was assessed on a four-point scale. The study aimed to observe the expression of the c-erbB-3 protein and investigate any relationship between expression and established prognostic indicators and prognosis. In both the primary and advanced series breast tumour tissue was found to stain heterogeneously for c-erbB-3. The staining was observed to be predominantly cytoplasmic and the majority of tumours exhibited moderate positivity. However, 15% and 35% of cases in the primary operable and advanced series respectively displayed strong positive staining. No significant difference was found between the staining in the primary and advanced series. In the primary operable breast cancers, no significant associations were demonstrated with overall survival, disease-free interval, regional recurrence, the presence of distant metastases, age, menopausal status, oestrogen receptor status, histological grade, lymph node stage, vascular invasion and c-erbB-2 protein expression. However, a significant association was seen between the degree of c-erbB-3 immunoreactivity and both tumour size (P < 0.01) and tumour type prognostic group (P = 0.05). No overall association with local recurrence was seen when the four groups of c-erbB-3 expression were analysed (P = 0.12), but when those tumours showing no or weak staining were compared with those showing moderate and strong immunoreactivity it was seen that the latter were significantly more likely to develop local recurrence (P = 0.03). In the series of patients with advanced disease, no significant associations were demonstrated with survival, UICC criteria, age, menopausal status, oestrogen receptor status, histological grade, c-erbB-2 status or the presence of vascular invasion. In conclusion this study found variable expression of c-erbB-3 protein in human breast carcinoma and an association with some recognised prognostic factors in those patients with primary operable breast carcinoma. It seems, however, unlikely that c-erbB-3 protein expression will emerge as a powerful enough prognostic factor to be of value in clinical practice.

Assessment of HER2 status in breast cancer: why, when and how?

Human epidermal growth factor receptor 2 (HER2) is overexpressed, usually as a result of HER2 proto-oncogene amplification, in 20-30% of breast cancers. A HER2-positive status is generally associated with more aggressive disease and a worse prognosis. Furthermore, a positive HER2 status may predict the likelihood of resistance to some conventional therapies, as well as probably being predictive of sensitivity to anthracycline dose intensification. In addition to this prognostic/predictive value, HER2 is a target for specific therapy, with anti-HER2 monoclonal antibody therapy available in the USA. This article reviews the different assays used to determine HER2 status, discussing their relative advantages/disadvantages and the need for their standardisation before integration alongside other pathological indices into the clinical management of breast cancer.