Chromosome instability and benefit from adjuvant anthracyclines in breast cancer.

BACKGROUND: Duplication of the centromeric region of chromosome 17 (Ch17CEP) is associated with sensitivity to anthracyclines. An explanation may be chromosome instability (CIN); a frequent event in solid tumours associated with poor outcome. The predictive value of CIN seems to be drug dependent and CIN has been associated with both sensitivity and resistance to chemotherapy. METHODS: In this study, we used fluorescent in situ hybridisation for chromosomes 1, 7, 11, 17 and 18 to identify patients with high tumour CIN% in 322 patients recruited into the BR9601 clinical trial. RESULTS: High tumour CIN% was correlated to Ch17CEP (P=3.68e-7) and is associated with a reduced RFS (P=0.0011) and OS (P=0.04). Patients with high CIN had a decreased risk of death on E-CMF compared with CMF. CONCLUSION: CIN is of prognostic significance and may be of predictive value in determining anthracycline response, although further testing is required.

Targeting anthracyclines in early breast cancer: new candidate predictive biomarkers emerge.

The search for a predictive marker of sensitivity to anthracycline-based chemotherapy has proven challenging. Despite human epidermal growth factor receptor 2 (HER2) being a strong prognostic marker in breast cancer, the only therapies with which there is a recognized functional link to the HER2 oncogene are those directly targeting the molecule itself. Despite this, HER2 has been extensively assessed as a predictive marker in a variety of chemotherapy regimens including anthracyclines. Analysis of anthracycline response in patients with HER2 amplification has given conflicting results. This led to the suggestion that HER2 amplification was acting as a surrogate for the gene encoding topoisomerase IIα (TOP2A), a direct cellular target of anthracyclines. Despite an attractive functional link between TOP2A and anthracyclines, published studies have failed to show strong evidence of an interaction between TOP2A genetic aberrations and anthracycline response. A number of other biomarkers have also been assessed for their role in predicting anthracycline response, including TP53 (tumour protein 53) and BRCA1 (breast cancer 1, early onset), together with an increasing emergence of gene expression profiling to produce predictive signatures of response. Moreover, recent evidence has emerged from presentations suggesting new candidate markers of response that warrant further investigation: Chr17CEP duplication and tissue inhibitor of metalloproteases 1. This review will discuss research into HER2 and TOP2A as predictive markers of anthracycline response and will focus on current research into other possible candidate predictive markers.

Type I receptor tyrosine kinases as predictive or prognostic markers in early breast cancer.

The type I receptor tyrosine kinase (RTK) family of proteins play an essential role in the progression of early breast cancer. Our understanding of the role of these proteins has increased over the last 20 years, however, as yet, there are still a number of unanswered questions regarding their position in endocrine resistance, chemotherapy resistance and in the biology of breast cancer. There have been, and are currently, a number of clinical trials that have examined the use of anticancer therapy such as cytotoxic drugs, and treatments that target the RTKs and signaling pathways that have been identified. There is clear evidence that molecular subtypes of cancer respond differently to different therapeutic options, which challenges the 'one size fits all' approach to chemotherapy. Here we review the human epidermal growth factor receptor family of proteins and their potential predictive or prognostic role in early breast cancer.

Observer variation in immunohistochemical analysis of protein expression, time for a change?

AIM: Immunohistochemical analysis of protein expression is central to most clinical translational studies and defines patient treatment or selection criteria for novel drugs. Interobserver variation is rarely analysed despite recognition that this is a key area of potential inaccuracy. Therefore our aim was to examine observer variation and suggest the revision of current standards. METHODS AND RESULTS: We analysed inter- and intra-observer variation, by interclass correlation coefficient (ICCC) and kappa statistics, in 8661 samples. Intra-observer assessment of nuclear, cytoplasmic and membrane staining for seven proteins in 1323 samples resulted in an ICCC of 0.94 and a kappa-value of 0.787. Interobserver reproducibility, assessed on 28 proteins by seven observer pairs in 8661 carcinomas, gave an ICCC of 0.90 and a kappa-value of 0.70. No significant effect of either antibody or cellular compartmentalization was observed. CONCLUSION: We have demonstrated that ICCC is a consistent method to assess observer variation when a continuous scoring system is used, compared with kappa statistics, which depends on a categorical system. Given the importance of accurate assessment of protein expression in diagnostic and experimental medicine, we suggest raising thresholds for observer variation: ICCC of 0.7 should be regarded as the minimum acceptable standard, ICCC of 0.8 as good and ICCC of > or = 0.9 as excellent.

HER2 and COX2 expression in human prostate cancer.

COX2 and HER2 expression are associated with a poor prognosis in prostate cancer and HER2 has been linked to COX2 expression in colorectal cancer. The association between COX2 and HER2 expression was investigated in 117 patients with prostate cancer (89) or Benign prostatic hyperplasia (BPH) (28). Tissue was analysed for HER2 amplification by fluorescent in situ hybridisation, and HER2 and COX2 protein expression by immunohistochemistry (IHC). All tumours analysed expressed COX2 at a significantly higher level than BPH tissue (P=0.041). Only low levels of HER2 gene amplification (8%, 7/89) and HER2 protein expression (12%, 11/89) were observed. HER2 protein expression was rarely observed and did not correlate with HER2 amplification or COX2 expression. Although HER2 does not drive COX2 expression in prostate cancer, this study identified high levels of COX2 expressed in locally advanced prostate cancer, suggesting COX2 could be a potential therapeutic target. COX2 inhibitors are currently being used in clinical trials for the treatment of other tumour types.

Equine telomeres and telomerase in cellular immortalisation and ageing.

To determine the role of telomeres in cellular ageing in equids, we analysed telomere lengths in peripheral blood derived DNA samples from a panel of donkeys (Equus asinus) ranging from 2 to 30 years of age. The average telomere lengths ranged from 7 to 21 kbp and a statistically significant inverse correlation between telomere lengths and donor age was demonstrated. Similarly, telomere lengths in primary fibroblasts isolated from a horse (Equus equus) demonstrated telomeric loss with in vitro ageing when cultured to senescence. We extended this study to evaluate activity of the enzyme telomerase in various equine cell cultures, normal equine tissues and equine benign tumour samples. Initially a panel of equine immortalised and primary cell cultures were evaluated for telomerase activity using a standard telomere repeat amplification protocol (TRAP) assay. High levels of telomerase activity were detected in equine immortalised cells with no activity evident in primary cell cultures. Similarly, no telomerase activity could be detected in normal equine tissues or equine benign tumour samples of the sarcoid or papilloma type. We conclude that telomere attrition may contribute to ageing in equids. However, it would appear that telomerase does not play a major role in the development of the most common benign tumours of the horse.