HER2/neu gene amplification and protein overexpression in G3 pT2 transitional cell carcinoma of the bladder: a role for anti-HER2 therapy?

HER2/neu is an oncogene encoding a type 1 tyrosine kinase growth factor receptor. Polysomy 17, gene amplification and HER2/neu protein overexpression are associated with a poor prognosis in transitional cell carcinomas (TCC) of the bladder. Due to the application of different laboratory techniques, the exact incidence of HER/neu abnormalities remains uncertain in TCC. Standardised laboratory techniques are therefore important in the determination of the HER2/neu status if an assessment of the potential value of anti-HER2/neu treatments in the clinical management of patients with TCC is to be made. In this study, 75 TCCs with evidence of detrusor muscle invasion at first clinical presentation were included. Gene amplification, polysomy 17 and HER2 copy number were assessed using fluorescence in situ hybridisation (FISH), with separate probes for chromosome 17 and HER2/neu. Protein overexpression was assessed using immunohistochemistry (IHC), with the CB11 antibody and a scoring system evaluating only membranous staining as positive. The mean patient age was 69.5 years (range 42-93 years) and the median survival was 15 months (range 1-156 months). Polysomy 17 occurred in 97%, increased HER/neu copy number in 92% and HER2/neu gene amplification in 7%. Protein overexpression occurred in 57% of cases. Polysomy 17 and HER2/neu protein overexpression are common in G3 pT2 TCCs of the bladder. However, gene amplification is uncommon. Mechanisms other than gene amplification may be responsible for protein overexpression in this tumour type. Evidence from breast cancer suggests that only tumours with HER2/neu gene amplification respond to the anti-HER2/neu therapy trastuzumab (Herceptin). If this were true for bladder cancer, only 4/75 (5%) of G3 pT2 TCCs would be suitable for treatment. The role of trastuzumab in these tumours remains untested at present.

HER2/neu overexpression in the development of muscle-invasive transitional cell carcinoma of the bladder

The mortality from transitional cell carcinoma (TCC) of the urinary bladder increases significantly with the progression of superficial or locally invasive disease (pTa/pT1) to detrusor muscle-invasive disease (pT2+). The most common prognostic markers in clinical use are tumour stage and grade, which are subject to considerable intra- and interobserver variation. Polysomy 17 and HER2/neu gene amplification and protein overexpression have been associated with more advanced disease. Standardised techniques of fluorescence in situ hybridisation and immunohistochemistry, which are currently applied to other cancers with a view to offering anti-HER2/neu therapies, were applied to tumour pairs comprising pre- and postinvasive disease from 25 patients undergoing treatment for bladder cancer. In the preinvasive tumours, increased HER2/neu copy number was observed in 76% of cases and increased chromosome 17 copy number in 88% of cases, and in the postinvasive group these values were 92 and 96%, respectively (not significantly different P=0.09 and 0.07, respectively). HER2 gene amplification rates were 8% in both groups. Protein overexpression rates were 76 and 52%, respectively, in the pre- and postinvasive groups (P=0.06). These results suggest that HER2/neu abnormalities occur prior to and persist with the onset of muscle-invasive disease. Gene amplification is uncommon and other molecular mechanisms must account for the high rates of protein overexpression. Anti-HER2/neu therapy might be of use in the treatment of TCC.

Correlation between immunohistochemistry (HercepTest) and fluorescence in situ hybridization (FISH) for HER-2 in 426 breast carcinomas from 37 centres

Accurate diagnostic assessment of HER-2 is essential for the appropriate application of the humanized anti-HER-2 monoclonal antibody trastuzumab (Herceptin) to the treatment of patients with metastatic breast cancer. The diagnostic test needs to be applicable to archival, fixed tissue removed at excision, in many cases several years earlier. We compared the assessment of HER-2 by immunohistochemistry (IHC; HercepTest) and fluorescence in situ hybridization (FISH) in 426 breast carcinomas from patients being considered for trastuzumab therapy. The tumours were tested in three reference centres having been sent in from 37 hospitals. Only 2/270 (0.7%) IHC 0/1+ tumours were FISH positive. Six of 102 (5.9%) IHC 3+ tumours were FISH negative. Five of the six had between 1.75 and 2.0 HER-2 gene copies per chromosome 17 and the sixth had multiple copies of chromosome 17. Thirteen per cent of tumours were IHC 2+ and overall 48% of these were FISH positive but this proportion varied markedly between the centres. Sixty IHC-stained slides selected to be enriched with 2+ cases were circulated between the three laboratories and scored. There were 20 cases in which there was some discordance in scoring. Consideration of the FISH score in these cases led to concordance in the designation of positivity/negativity in 19 of these 20 cases. These data support an algorithm in which FISH testing is restricted to IHC 2+ tumours in reference centres. The results may not extrapolate to laboratories with less experience or using different methodologies.

Chromosome 17 aneusomy is associated with poor prognostic factors in invasive breast carcinoma

Aberrations of chromosome 17 are common in breast cancer. Fluorescence in situ hybridization (FISH) enables gene or chromosome copy number to be assessed in situ in archival tissues and related to morphology and clinical outcome. In this study direct labeled DNA probes for the chromosome 17 alpha satellite and the HER2/neu gene were applied simultaneously to 5 micron sections of 214 formalin-fixed paraffin-embedded invasive primary breast carcinomas. A high proportion (54%) of invasive breast carcinomas displayed aneusomy of chromosome 17. Polysomy 17 correlated with multiple copies of HER2/neu (p = < 0.001), but not with HER2/neu amplification. Eighty-six patients without HER2/neu amplification had aneusomy 17. Fifty-eight of the 86 patients that had aneusomy 17 had high HER2/neu copy number. Twelve patients with normal copy number for chromosome 17 had amplification of HER2/neu and 30 patients had amplification of HER2/neu with aneusomy 17. Aneusomy 17 was associated with grade 3 carcinoma (p = 0.008), ER negativity (p = 0.0032) and a Nottingham prognostic index of greater than 5.4 (p = 0.039) but was not associated with survival by univariate analysis. In conclusion, the determination of chromosome 17 copy number should be incorporated in assessment of HER2/neu status, as this will give an accurate measure of amplification of HER2/neu and may also be helpful in determining suitability for breast carcinoma trials.

Genetic aberrations of c-myc and CCND1 in the development of invasive bladder cancer

Detrusor muscle invasive transitional cell carcinoma is associated with poor prognosis and is responsible for the majority of bladder cancer related deaths. Amplifications of c-myc and CCND1 are associated with detrusor-muscle-invasive transitional cell carcinoma, however, their precise role in driving disease progression is unclear. Fluorescence in situ hybridisation on archival tissue from 16 patients with primary diagnosis of > or = pT2 transitional cell carcinoma and 15 cases with primary pTa/pT1 disease subsequently progressing to detrusor-muscle-invasion was performed, in the latter group both pre and post muscle invasive events were studied. No patients presenting with >/=pT2 had amplification of c-myc, two out of 16 (12.5%) had CCND1 amplification. Of patients who developed > or = pT2, two out of 15 (13.3%) had amplification of c-myc, both in > or = pT2, five out of 15 (33.3%) had CCND1 amplification, two in pTa/pT1 tumours, three in > or = pT2 transitional cell carcinomas. In total, two out of 31 (6.5%) of patients' > or = pT2 TCCs were amplified for c-myc and six out of 31 (19%) were amplified for CCND1. Eighty-seven per cent (40 out of 46) of tumours were polysomic for chromosome 8 and 80% (37 out of 46) were polysomic for chromosome 11 and this reflected the high copy numbers of c-myc and CCND1 observed. In almost all cases an increase in c-myc/CCND1 copy number occurred prior to invasion and persisted in advanced disease. Amplification of CCND1 or alterations in c-myc/CCND1 early in bladder cancer may have clinical relevance in promoting and predicting progression to detrusor-muscle-invasive transitional cell carcinoma.

Genetic aberrations of NAT2 and chromosome 8: their association with progression in transitional cell carcinoma of the urinary bladder

INTRODUCTION/OBJECTIVE

N-acetyltransferase 2 (NAT2), mapped to 8p22, is a polymorphic enzyme which metabolizes aromatic amines. Loss of heterozygosity of 8p22 is associated with an increased risk of bladder cancer. This study evaluated NAT2 and chromosome 8 in sequential tumours from bladder cancer patients to determine if NAT2 alterations increase the risk of progression.

MATERIALS AND METHODS

Thirty-seven sequential carcinomas from 19 patients were assessed using fluorescence in situ hybridization.

RESULTS

Five carcinomas showed loss of NAT2; 4 of these were from pTa/pT1 tumours. Polysomy 8 was observed in 4 of 14 (29%) primary carcinomas (pTa/pT1), in 4 of 12 (33%) pTa/pT1 recurrences, and in 90% (9/10) of the detrusor muscle invasive tumours (pT2+). 6 of 8 (75%) locally invasive tumours with polysomy 8 were from patients who subsequently developed disease progression (pT2+). In total, 13.5% (5/37) of the carcinomas were abnormal for NAT2, and 46% (17/37) were abnormal for chromosome 8 copy number. Polysomy 8 was associated with high grade (p = 0.01) and stage (p = 0.03) and disease progression (p = 0.03).

CONCLUSION

Whilst there does not appear to be an association between loss of NAT2 and risk of progression in transitional cell carcinoma, the high rate of polysomy of chromosome 8 implies that other genes on this chromosome significantly influence disease progression.

Fluorescence in situ hybridization in paraffin tissue sections: pretreatment protocol

Fluorescence in situ hybridization has found wide application in the enumeration of gene and chromosome copy number both in isolated cells and in tissue sections. However, the technique has been less widely used than would be expected in formalin-fixed paraffin processed (archival) tissue. This article describes a method for assessing archival tissue sections, following pretreatment, before applying DNA probes, that gives consistent, reliable results.

Gene amplification and overexpression of HER2 in renal cell carcinoma

OBJECTIVE

To determine the frequency of HER2 genetic abnormalities in renal cell carcinoma (RCC) and hence assess the potential suitability of Herceptin immunotherapy.

PATIENTS AND METHODS

Tumours from 27 patients with RCC were assessed; all patients had undergone nephrectomy. Benign renal tissue from the nephrectomy specimens was studied in seven patients. Gene amplification was assessed using fluorescent in-situ hybridization, and protein over-expression using immunohistochemistry.

RESULTS

Twenty-four patients had clear cell renal carcinoma, two had papillary renal carcinoma and one a sarcomatoid variant carcinoma. There was no HER2 amplification in the tumours or the benign renal tissue. Polysomy 17 was detected in 11 of 27 tumours (41%) and increased HER2 copy number in seven (26%). Both polysomy 17 and increased HER2 copy number were absent in the benign renal tissue. Three tumours (11%) and six of the seven benign renal tissue samples over-expressed the HER2 protein.

CONCLUSIONS

HER2 amplification is absent and protein over-expression uncommon in RCC. This casts doubt on the suitability of Herceptin in the treatment of RCC.

Loss of heterozygosity on chromosomes 11 and 17 are markers of recurrence in TCC of the bladder

Approximately 2/3 of patients diagnosed with superficial transitional cell carcinoma of the urinary bladder (TCC) will recur within 2 years. Loss of chromosome 9 and loss of heterozygosity (LOH) at 9q34 in index TCCs identify a subset of patients at high risk of recurrence. This study explores genetic alterations on chromosomes 4, 8, 11 and 17 as predictors of recurrence. A total of 109 carcinomas were investigated at 26 loci. DNA was extracted from microdissected archival normal/tumour tissue and was analysed for loss of heterozygosity (LOH). Fluorescent PCR was performed and genotyping carried out on a Perkin Elmer ABI377 sequencer. LOH of D11S490 or D17S928 was significantly more frequent in index carcinomas of patients who experienced recurrence compared to those with no recurrence (P = 0.004 and 0.019 respectively). These results suggest that loss of these regions is associated with recurrence of TCC. Further investigation is required to identify genes in these regions, which might be responsible for driving recurrence in TCC of the urinary bladder.

Evaluating HER2 amplification and overexpression in breast cancer

The development of Herceptin (Trazumatab) makes testing for HER2 status important for choosing optimal therapy in breast cancer. This study addresses the precision, accuracy, and reproducibility of HER2 assays. HER2 was assessed retrospectively by immunohistochemistry (IHC) with Dako 'Herceptest', by IHC with the monoclonal antibody CB11, and by fluorescence in situ hybridization (FISH, PathVysion), in a series of 216 formalin-fixed breast carcinomas including 191 for which quantitative HER2 data from radioimmunohistochemistry (Q-IHC) were available. All tests were scored independently by two observers. Positivity rates varied between Herceptest (12.6%), FISH (19.4%), and CB11 IHC (28.5%). Kappa values showed that IHC-based tests were more susceptible to inter-observer variation (kappa=0.67 and 0.74 for Herceptest and CB11, respectively) than FISH (kappa=0.973). Overall test accuracy (see the Materials and methods section) for CB11 IHC (83.8%) was lower than Herceptest (87.4%) or FISH (93.2%). FISH predicted p185 HER2 overexpression (determined by Q-IHC) better (concordance index C.Ind. 0.90) than CB11 IHC (C.Ind.=0.85) or Herceptest (C.Ind.=0.81). Of 42 cases with gene amplification by FISH, 67% were positive in the Herceptest (2+ or 3+) vs. 83% with CB11. Of 174 cases negative by FISH, 96% were negative in the Herceptest and 68% with CB11. In conclusion, FISH is the most accurate, reproducible, and precise predictor of HER2 overexpression in routine diagnostic laboratories.

Amplification of the androgen receptor may not explain the development of androgen-independent prostate cancer

OBJECTIVE

To examine the role of androgen receptor (AR) gene amplification and aneusomy of the X chromosome in the development of antiandrogen-resistant prostate cancer.

PATIENTS AND METHODS

Twenty patients with prostate cancer resistant to androgen-deprivation therapy were selected for study. The records of patients with tumours before and after antiandrogen therapy, and with a full clinical follow-up, were retrieved. AR gene amplification and X chromosome copy number were assessed by fluorescence in situ hybridization using a labelled probe at locus Xq11-13 for the AR gene and a labelled alpha-satellite probe for the X chromosome. At least 20 nuclei were scored over three tumour areas by two independent observers.

RESULTS

Aneusomy of the X chromosome was reported respectively in seven (35%) and 11 (55%) tumours before and after hormone relapse, the AR gene copy number was increased in seven (35%) and 13 (65%), respectively, and AR gene amplification was detected in one (5%) and three (15%), respectively. Neither increased AR copy number nor AR amplification in primary tumours precluded a biological response to androgen-deprivation therapy.

CONCLUSION

The rate of AR gene amplification is too low to be solely responsible for the development of antiandrogen-resistant prostate cancer. Also, the presence of amplified AR and cells aneusomic for the X chromosome in primary tumours that respond to androgen-deprivation therapy suggests that an increase in AR gene copy number does not prevent a tumour from responding to this therapy. Therefore other mechanisms which could cause hormone-refractory prostate cancer must be investigated before it is understood why so many patients relapse with this disease.

Quantitation of FISH Signals in Archival Tumors

The term interphase cytogenetics was first used in 1986 by Cremer (1,2) to describe detection of chromosomal alterations using in situ techniques in interphase nuclei. This was a distinct advantage over conventional analyses as solid tumors could now be studied (2,3) and the possibility of applying the technique to specimens received in a diagnostic laboratory realised (4). The nonradioactive in situ method, fluorescence in situ hybridization (FISH), has been widely applied to study chromosomal rearrangements, malignancies, and chromosome mapping (4).

Aneusomy of chromosomes 7 and 17 predicts the recurrence of transitional cell carcinoma of the urinary bladder

OBJECTIVE

To determine if changes in chromosome 7 and 17 copy number can be used to predict recurrence in patients with primary noninvasive (pTa) or superficially invasive (pT1) transitional cell carcinoma (TCC) of the urinary bladder.

PATIENTS AND METHODS

Tissue specimens for 129 tumours from 52 patients (38 men and 14 women) with pTa/pT1 TCC at first diagnosis were retrieved from pathology archives. All patient notes were accessed and disease outcome documented for superficial (pTa/pT1) recurrence or progression to detrusor muscle invasion (>/= pT2). The tumours were examined for chromosomal copy number of chromosomes 7 and 17 using fluorescence in situ hybridization (FISH) with chromosome-specific probes. The copy number of chromosomes 7 and 17 was determined in interphase nuclei on intact 6 microm tissue sections.

RESULTS

Aneusomy of chromosomes 7 and 17 was detected in the index primary tumours of 10 of 32 (31%) patients with subsequent recurrent disease. No aneusomy for these chromosomes was detected in primary tumours from 20 patients with no detect-able recurrence (P = 0.0082). The relative risk of recurrence was 3.62 times greater (95% confidence interval 1.6-8.1, Cox's multiple regression P = 0.0019) for patients with chromosomal aneusomy in primary TCC. Neither stage nor grade of the primary tumours was associated with recurrence in these patients, nor was there a significant association with increased grade (G2/3) or stage (>/= pT2) at recurrence.

CONCLUSION

These results suggest that the measurement of aneusomy by FISH, using markers for chromosomes 7 and 17, predict recurrence in a subgroup of patients with pTa/pT1 tumours at presentation. This finding may offer a new objective and quantitative test for patients destined to recur.

Chromosomal aberrations in transitional cell carcinoma that are predictive of disease outcome are independent of polyploidy

OBJECTIVE

To determine whether aneusomy for chromosomes 7, 9 and 17 (reported to predict recurrence in up to 65% of patients with superficial transitional cell bladder cancer and thus providing the opportunity for early and effective treatment) reflects specific genetic events on these chromosomes or merely wider unspecific genetic damage to the cell, e.g. that increased copy numbers for 7 and 17 reflect tumour polyploidy.

MATERIALS AND METHODS

The study comprised 25 primary tumours; 6 microm thick sections from formalin-fixed and paraffin-embedded tumours were analysed. Chromosome copy numbers were determined by fluorescence in situ hybridization (FISH) using pericentromeric probes for chromosomes 7, 8, 9, 10, 11 and 17. A minimum of 200 nuclei per tumour area were scored by two independent observers.

RESULTS

Eight of the 25 tumours examined (32%) showed no evidence of chromosomal abnormalities as detected by FISH for any chromosomes analysed. Twelve tumours (48%) showed abnormalities for one or two chromosomes, five tumours (20%) showed abnormalities for multiple chromosomes and one tumour showed abnormalities for all chromosomes analysed, suggestive of polyploidy.

CONCLUSIONS

Chromosomal abnormalities predictive of recurrence occur largely in the absence of other gross chromosomal lesions. In a small proportion of cases other chromosomes are affected, but this is almost always distinct from tumour polyploidy.

Is chromosome 9 loss a marker of disease recurrence in transitional cell carcinoma of the urinary bladder?

Investigation of transitional cell carcinoma of the urinary bladder (TCC) patients classified by recurrence and/or progression has demonstrated that loss of chromosome 9, as detected by FISH analysis of the pericentromeric classical satellite marker at 9q12, occurs early. A total of 105 TCCs from 53 patients were analysed in situ by two independent observers for loss of chromosome 9 using quantitative fluorescence in situ hybridization (FISH). All 53 primary tumours were evaluated for chromosomes 9, 7 and 17. Normal ranges for chromosomal copy number were defined for normal skin epidermis and bladder epithelium. Values for chromosome 9 copy number outwith the range 1.51-2.10 (mean +/- 3 x s.d. of normal values) were significantly abnormal. Twenty-five TCCs were detected with consistent monosomic scores. Of 89 TCCs, in which multiple tumour areas were analysed, 85 tumours (96%) demonstrated the same chromosome 9 copy number in all areas (2-6) analysed; only three tumours demonstrated heterogeneity for this locus. A total of 36% (12 out of 33) of patients with subsequent disease recurrence demonstrated loss of chromosome 9 in their primary and all subsequent TCCs analysed. Only a single patient (n = 20) with non-recurrent TCC showed loss of chromosome 9 (P = 0.0085). Of 53 primary tumours, eight showed significant elevation of chromosome 17. Of these patients, six demonstrated elevation in chromosome 7 copy number. No abnormalities were observed in non-recurrent patients. This study describes rapid quantitation of chromosomal copy number by FISH using a pericentromeric probe for chromosome 9 in TCC of the urinary bladder. Routinely fixed and processed material was evaluated without disaggregation. Strict quality control of FISH demonstrated that this technique was reproducible in a clinical environment and could be used to detect genetic changes relevant to patient outcome. It is proposed that loss of chromosome 9 from primary TCC of the urinary bladder identified patients at high risk of recurrence and possible progression.