Clinical Cancer Research Targets Advances in Breast Cancer
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Cancer Research Clinical Cancer Research
Cancer Epidemiology Biomarkers & Prevention Molecular Cancer Therapeutics
Molecular Cancer Research Cancer Prevention Research
Cancer Prevention Journals Portal Cancer Reviews Online
Annual Meeting Education Book Meeting Abstracts Online

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Coon, J. S.
Right arrow Articles by Preisler, H. D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Coon, J. S.
Right arrow Articles by Preisler, H. D.
Clinical Cancer Research Vol. 8, 1061-1067, April 2002
© 2002 American Association for Cancer Research


Molecular Oncology, Markers, Clinical Correlates

Amplification and Overexpression of Topoisomerase II{alpha} Predict Response to Anthracycline-based Therapy in Locally Advanced Breast Cancer1

John S. Coon2, Elizabeth Marcus, Shalina Gupta-Burt, Steven Seelig, Kris Jacobson, Shande Chen, Vivian Renta, Geraldo Fronda and Harvey D. Preisler

Rush Medical College, Chicago, Illinois 60612 [J. S. C, S. G-B., S. C., H. D. P.]; Cook County Hospital, Chicago, Illinois 60612 [E. M., V. R., G. F.]; and Vysis, Inc, Downers Grove, Illinois 60515 [S. S., K. J.]


    ABSTRACT
 Top
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Purpose: The putative association between erbB-2 overexpression and favorable response to anthracyline-based therapy in breast cancer is controversial, and the mechanism unclear. We sought to determine whether coamplification and overexpression of the topoisomerase II{alpha} gene, near erbB-2 on chromosome 17, and a known anthracycline target, may underlie the association.

Experimental Design: Thirty-five patients who had locally advanced breast cancer (LABC) and who had received neoadjuvant, anthracycline-based therapy were studied. Copy number of topoisomerase II{alpha} and erbB-2 was determined by fluorescence in situ hybridization, and expression by immunohistochemistry.

Results: Of 8 patients with erbB-2 amplification, 5 had a complete response (CR) or minimal residual disease (MRD), 3 had a partial response (PR), and none had stable (StD) or progressive disease (PD) at the time of mastectomy, versus 3 CR or MRD, 16 PR, and 8 StD or PD for patients without amplification (P = 0.008). In contrast, erbB-2 overexpression was not significantly associated with response (P = 0.114). Of 6 patients with topoisomerase II{alpha} amplification, 4 had CR or MRD, 2 PR, and none StD or PD, versus 4 CR or MRD, 17 PR, and 8 StD or PD for patients without amplification (P = 0.034). All of the tumors with topoisomerase II{alpha} amplification also had erbB-2 amplification, but not vice versa. Overexpression of topoisomerase II{alpha} (9 patients) was also associated with favorable response (P = 0.021).

Conclusions: Coamplification of erbB-2 and topoisomerase II{alpha} is significantly associated with favorable local response to anthracycline-based therapy in LABC. The expression data favor a plausible mechanism based on topoisomerase II{alpha} biology.


    INTRODUCTION
 Top
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
The therapy of LABC3 continues to be a difficult problem. Historically, patients had a very poor rate of survival with single modality treatment. Recently, with the routine use of multimodality therapy, specifically chemotherapy, surgery, and radiation, survival has improved (1) . Favorable response to neoadjuvant chemotherapy is associated with improved survival (1) . Several tumor markers have been reported to be predictors of neoadjuvant chemotherapy response in LABC, including estrogen receptor (2) , progesterone receptor (2) , proliferation index (2 , 3) , ploidy (3) , and apoptotic index (3) . These studies have not provided a basis for selecting optimal chemotherapy for individual patients, however. This results in some patients receiving aggressive therapy without significant benefit. A possible approach to this problem is to customize therapy for individual patients based on demonstrating molecular targets in their tumor cells for specific drugs. Defining such targets may be a prerequisite for improving outcome in this disease.

The controversial and seemingly paradoxical observation that breast cancer patients with erbB-2 overexpression may benefit more than others from anthracycline-based therapy may provide a lead to defining a useful target for chemotherapy (4 , 5) . This observation seems paradoxical because erbB-2 is a well-known oncogene the amplification and overexpression of which have long been linked to adverse prognosis in breast carcinoma (6 , 7) . Furthermore, attempts to link erbB-2 up-regulation to increased sensitivity to anthracyclines via manipulating expression in cell lines have been unsuccessful (8) . The report that the gene for topoisomerase II{alpha}, a well-established molecular target for anthracyclines in experimental systems, is frequently coamplified with erbB-2 in breast cancer, because of their proximity on chromosome 17, now provides a plausible, although unproved, mechanism for the putative link between erbB-2 overexpression and anthracycline response (9) . That a gene amplification event commonly encountered in clinical malignancies makes affected tumors more drug-sensitive, rather than drug-resistant, runs counter to a well-accepted paradigm in tumor biology (9) . Another recent insight that may bear on the significance of erbB-2 in LABC is the demonstration that only high-level erbB-2 overexpression in breast cancer is associated with gene amplification and is more biologically significant than low-level overexpression (compared with normal breast epithelium; Ref. 10 ). This appears to underlie the observation that assessing erbB-2 overexpression by immunohistochemistry may be less informative clinically than measuring gene amplification by FISH (11) . Diverse methodology for assessing erbB-2 probably contributes significantly to the controversy concerning the significance of erbB-2 overexpression in this and other important contexts. The recent report that approximately 12% of breast cancers that express erbB-2 also express an activated, phosphorylated form of erbB-2, by immunohistochemistry, may further complicate the assessment of expression (12) . Because of these observations, we studied both overexpression and gene copy number of both erbB-2 and topoisomerase II{alpha} in a group of 35 patients with LABC treated with anthracycline-based neoadjuvant chemotherapy.


    MATERIALS AND METHODS
 Top
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Patients.
Patients with LABC who were treated with neoadjuvant, anthracycline-based chemotherapy at Cook County Hospital between 1996 and 1999 were included in this retrospective study, provided that there was sufficient paraffin-embedded tissue available from the diagnostic (pretherapy) biopsy. All of the patients had a mastectomy after completion of chemotherapy, permitting pathological assessment of the response of the breast tumor. CR was defined as no residual tumor identified in the mastectomy specimen, based on the study of H&E-stained sections. MRD was defined as no gross tumor and microscopic invasive carcinoma present in two or less high-power fields. PR was defined as >50% reduction in the sum of the products of the perpendicular diameters of all measurable lesions within the pathological specimen compared with the clinical measurements taken at diagnosis by physical examination. MR was defined as a 26–49% decrease in the size of measurable lesions. StD was defined as <25% increase or a decrease in the size of measurable lesions. PD was defined as >25% increase in the size of measurable lesions at mastectomy. Studies were approved by the Institutional Review Boards at Cook County Hospital and at Rush Medical College. The patients treated as part of a clinical trial gave informed consent for the study. The requirement for consent was waved by the Institutional Review Boards for the other patients, because the study entailed minimal risk, consisting of an analysis of preexisting diagnostic specimens and clinical data.

Immunohistochemistry.
In preparation for antibody staining, paraffin sections (5-µm, freshly cut) were deparaffinized and rehydrated using standard technique. A microwave antigen retrieval method was then carried out in citrate buffer (13) . The tissue was stained using a Ventana ES Histo-stainer (Ventana Medical Systems, Tucson, AZ), using supplied diaminobenzidine and avidin-biotin conjugate immunoperoxidase chemistry. Sections were stained for erbB-2 with the A 485 rabbit polyclonal antibody, Lot 035(401) from Dako Corp. (Carpinteria, CA) at 1:125 dilution. Sections were stained for topoisomerase II{alpha} with the JH2.7 monoclonal antibody from Lab Vision Corp. (Fremont, CA) at a dilution of 1:100. A single block from the pretherapy biopsy was selected for analysis for each patient on the basis of having the greatest area of well-preserved tumor. Immunostaining frequency of all tumor cells on each slide was scored subjectively on a scale of 0 to 4 (actual cell counting was not performed) without knowledge of clinical patient data, as described previously (13) . The scoring was as follows: <1% positive tumor cells, 0; 1–10%, 1; 10–35%, 2; 36–70%, 3; and >71%, 4. Tumor cell staining intensity was also scored on a scale of 0 to 4 but was found to be so closely related to frequency that it was not further considered in this study. Only cell membrane-associated staining was considered for erbB-2. Only nuclear staining was considered for topoisomerase II{alpha}.

FISH.
Paraffin blocks were sectioned at 5 µm and mounted onto SuperFrost positively charged slides (Shandon, Inc., Pittsburgh, PA) and baked at 56°C overnight to fix the tissue onto the slides. After baking, the slides were treated with Pretreatment Solution (Vysis, Inc., Downers Grove, IL) and protease I (Vysis, Inc) according to a protocol similar to that published by Hopman et al. (14) . Slides were dewaxed and then incubated in pretreatment solution for 10 min at 80°C. Slides were washed and then incubated in 4 mg/ml protease I in 0.2 N HCL at 37°C for 15 min, dehydrated in graded ethanol baths, and air dried. Sections were hybridized with a FISH probe combination containing a prototype SpectrumGreen LSI Topo II-{alpha}, SpectrumOrange LSI HER-2 (erbB-2), and SpectrumAqua CEP-17 (all probes from Vysis, Inc.) using a HYBrite instrument that performs codenaturation and hybridization (Vysis, Inc.). The topoisomerase II{alpha} probe covers ~280 kb, including the entire topoisomerase II{alpha} gene and the sequence tag site markers, WI-15402, SGC31792, and WI-17575 (a subsequently released commercial version of this Vysis multicolor probe set included an LSI Topo II-{alpha} probe targeting a larger, 400-kb region). The LSI HER-2 probe covers ~190 kb, including the entire erbB-2 gene. The CEP 17 probe contains sequence homologous to the D17Z1 satellite repeat sequence. Probe hybridization mixture was applied to each section, and glass coverslips were immediately applied and sealed with rubber cement. Slides were then codenatured at 73°C for 5 min and were hybridized at 37°C for 16–18 h. After removing the coverslips, the slides were incubated at 73°C in 2x SSC/0.3% NP40 for 2 min to remove nonspecifically bound FISH probe, and then were air dried in the dark. DAPI I counterstain (Vysis, Inc.) was applied to the specimen to allow visualization of the nuclei.

The FISH slides were evaluated using a Zeiss Axioscope epifluorescence microscope (Carl Zeiss, Inc, Thornwood, NY). Signals were visualized, and counting was performed using a DAPI single-band pass filter set to visualize nuclei, a green single-band pass filter to visualize SpectrumGreen TopoII-{alpha}, an orange single-band pass filter set to visualize SpectrumOrange HER-2, and an aqua single-band pass filter set to visualize SpectrumAqua CEP-17. Signals for each probe were counted in 25–30 tumor-cell nuclei. For nuclei with greater than 20 erbB-2 or topoisomerase II signals, an estimate of 21 signals was used for the purpose of calculating signal ratios. A ratio of 2.5 or greater for erbB-2/CEP-17 or for topoisomerase II/CEP-17 was considered to indicate amplification.

Statistical Methods.
Response of the tumor in the breast at the time of mastectomy was divided into three categories: CR or MRD, PR, and StD or PD. Immunohistochemistry data were categorized as overexpressed, or not, and FISH data were categorized as amplified, or not. Fisher’s exact test (2-tailed) was used to examine associations between each of the markers and response of the breast tumors to chemotherapy. Results were considered statistically significant at the 0.05 level. The sample size was small in this study. A power calculation based on Fisher’s exact test for 2 x 2 table (from PASS), assuming 8 CR or MRD patients and 27 other patients, showed a power of 48% if the percentage of amplified is 50% among CR or MRD patients and is 10% among other patients. The same technique was used for other categorical data. To investigate associations between patient age and response and other markers, the two-sample Wilcoxon test or the Kruskal-Wallis test (for more than two groups) was used. Age was treated as a continuous variable and was grouped by the category for response or the markers. Age was then compared among the groups. This was done to compare the conditional distributions of age-given categories. If there is no association between age and response (or the markers), then there should be no difference among groups. The sample size is important in this context. For example, if the mean age is 55.3 (SD, 4.5) in 6 topoisomerase II{alpha} amplified patients and the mean age is 47.1 (SD, 8.8) in 29 nonamplified patients, the power (based on a 2-sided level of 0.05) is ~95%. However, if the mean age is 46.8 (SD, 7.1) in 9 patients with topoisomerase II{alpha} overexpression, and the mean age is 49.2 (SD, 9.3) in 29 patients without overexpression, the power (based on a 2-sided level of 0.05) is only ~13%.


    RESULTS
 Top
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Patients.
A total of 35 patients with LABC who were treated with anthracycline-based therapy before mastectomy at Cook County Hospital between 1996 and 1999 were included in the study. All of the patients had biopsy-proven invasive breast carcinoma: 19 ductal, 5 lobular, and 11 diagnosed as breast adenocarcinoma, not otherwise specified. The ages of the patients ranged from 35 to 69 (mean, 48.5) years. Seven patients had stage IIB tumors, 18 had IIIA, and 10 IIIB. Twenty-two patients received six 21-day cycles of 50 mg/m2 doxorubicin (300 mg/m2 total) and 75 mg/m2 docetaxel (450 mg/m2 total) as part of a clinical trial; the others received CAF. CAF therapy comprised six 21-day cycles of 500 mg/m2 cyclophosphamide (3000 mg/m2 total), 50 mg/m2 doxorubicin (300 mg/m2 total), and, 500 mg/m2 5-fluorouracil (3000 mg/m2 total). Five patients achieved a CR and 3 a MRD rating in the breast at the time of mastectomy, 19 had a PR, none had MR, 5 had StD, and 3 had PD while on chemotherapy. The fraction of patients with positive lymph nodes at mastectomy in each response group was as follows: CR, 0 of 5; MRD, 1 of 3 (microscopic); PR, 9 of 19; StD, 1 of 5; and PD, 3 of 3.

FISH Analysis.
Eight patients’ tumors (23%) showed amplification of the erbB-2 gene as assessed by FISH, with erbB-2:CEP-17 ratios ranging from 2.60 to 8.86 (Fig. 1)Citation . No erbB-2 deletions were detected. One patient had high-grade polyploidy for chromosome 17 with mean CEP-17 value per cell of 13.2. Another patient exhibited deletion of one allele of CEP-17. Six patients’ tumors (17%) showed amplification of topoisomerase II{alpha}, with topoisomerase II:CEP-17 ratios ranging from 2.70 to 5.70. No definite deletions of topoisomerase II{alpha} were observed. All of the tumors with topoisomerase II{alpha} amplification also had erbB2 amplification.



View larger version (42K):
[in this window]
[in a new window]
[Download PPT slide]
 
Fig. 1. Example of discordant amplification of erbB-2 but not topoisomerase II{alpha}, as visualized in a single tumor cell by multicolor FISH. DAPI counterstain, x1000. a, SpectrumGreen LSI Topo II-{alpha} probe showing normal copy number of 2 for topoisomerase II{alpha}. b, SpectrumOrange LSI HER-2 probe showing high-level amplification of erbB-2. c, SpectrumAqua CEP-17 probe showing normal copy number of 2 for centromeric region of chromosome 17.

 
Immunohistochemistry.
Fifteen patients’ tumors were interpreted as overexpressing erbB-2 because they showed widespread (3+ or 4+) membrane staining that surrounded individual tumor cells (Fig. 2a)Citation . The association between erbB-2 overexpression and gene amplification had borderline statistical significance (P = 0.051). Nine tumors had erbB-2 overexpression without amplification, whereas two had amplification without apparent overexpression (Table 1)Citation . Topoisomerase II{alpha} staining was largely confined to the nucleus of the tumor cells in which it was detectable, with rare tumors exhibiting faint cytoplasmic staining. Only nuclear staining was considered in scoring. Nine patients had topoisomerase II{alpha} overexpression, defined as 3+ or 4+ staining (Fig. 2b)Citation . There was no evidence for an association between topoisomerase II{alpha} overexpression and gene amplification (P = 0.635; Table 2Citation ). Most notably, only two of nine tumors with topoisomerase II{alpha} overexpression had amplification. There was also no evidence of an association between expression of topoisomerase II{alpha} and expression of erbB-2 (P = 0.700).



View larger version (112K):
[in this window]
[in a new window]
[Download PPT slide]
 
Fig. 2. Example of immunohistochemistry results for erbB-2 and topoisomerase II{alpha}. Diaminobenzidine (brown) chromagen, hematoxylin counterstain, x400. a, immunoperoxidase stain for erbB-2, demonstrating widespread cell membrane staining, interpreted as overexpression. b, immunoperoxidase stain for topoisomerase II{alpha} showing nuclear staining of the majority of the tumor cells, interpreted as overexpression.

 

View this table:
[in this window]
[in a new window]

 
Table 1 Comparison of erbB-2 amplification and overexpression

Copy number of erbB-2 was measured by FISH; tumors with erbB-2:CEP-17 ratio greater than 2.5 were considered amplified. erbB-2 expression in the cell membrane was measured by immunohistochemistry. The association between erbB-2 overexpression and gene amplification had borderline statistical significance (P = 0.051).

 

View this table:
[in this window]
[in a new window]

 
Table 2 Comparison of topoisomerase II{alpha} amplification and overexpression

Copy number of topoisomerase II{alpha} was measured by FISH; tumors with topoisomerase II{alpha}:CEP-17 ratio greater than 2.5 were considered amplified. Topoisomerase II{alpha} expression in the nucleus was measured by immunohistochemistry. There was no evidence for an association between topoisomerase II{alpha} overexpression and gene amplification (P = 0.635).

 
Association of Molecular Markers with Response to Therapy.
The clinical end point in this study was the local tumor response in the breast, defined by comparing the breast tumor at presentation with the tumor, if any, at the time of mastectomy after chemotherapy. Amplification of erbB-2 was significantly associated with a favorable local tumor response to chemotherapy (Table 3)Citation . Of eight patients with erbB-2 amplification, five had a CR or MRD, three had a PR, and none had StD or PD at the time of mastectomy. In contrast, the 27 patients without amplification had 3 CR or MRD, 16 PR, and 8 StD or PD (P = 0.008). If CR or MRD versus all of the other responses are compared, P = 0.007.


View this table:
[in this window]
[in a new window]

 
Table 3 Amplification of erbB-2 is related to chemotherapy response

Copy number of erbB-2, as determined by FISH, was significantly associated with local tumor response to chemotherapy (P = 0.008). If CR or MRD versus all other responses are compared, P = 0.007. Response was determined by comparison of the breast tumor at presentation with the mastectomy specimen.

 
Unlike erbB-2 gene amplification, erbB-2 overexpression was not significantly associated with breast tumor response to chemotherapy (P = 0.114) although if CR or MRD versus all of the other responses are compared, there was a borderline association (P = 0.051; Table 4Citation ). Neither of the two patients with erbB-2 overexpression and StD or PD had erbB-2 amplification, and in the 7 patients with PR, only one overexpressing tumor had amplification. To further analyze the possible link between erbB-2 overexpression and chemotherapy response, we considered separately the 27 patients without erbB-2 amplification, including 9 with overexpression (Table 5)Citation . Among these patients, there was no evidence of an association between erbB-2 overexpression and tumor response (P = 0.843).


View this table:
[in this window]
[in a new window]

 
Table 4 Overexpression of erbB-2 versus chemotherapy response

Overexpression of erbB-2, as determined by immunohistochemistry, was not significantly associated with breast tumor response to chemotherapy (P = 0.114), although if CR or MRD versus all of the other responses are compared, there was a borderline association (P = 0.051). Response was determined by comparison of the breast tumor at presentation with the mastectomy specimen.

 

View this table:
[in this window]
[in a new window]

 
Table 5 Overexpression of erbB-2 versus chemotherapy response tumors with amplification excluded

For the 27 patients who did not have erbB-2 amplification, there was no evidence of an association between erbB-2 overexpression and tumor response (P = 0.843). Response was determined by comparison of the breast tumor at presentation with the mastectomy specimen.

 
Amplification of topoisomerase II{alpha} was significantly associated with a more favorable tumor response to chemotherapy (Table 6)Citation . Of six patients with amplification, 4 had CR or MRD, 2 PR, and none StD or PD, versus 4 with CR or MRD, 17 with PR, and 8 with StD or PD among patients without amplification (P = 0.034). If CR or MRD versus all of the other responses are compared, P = 0.016. Topoisomerase II{alpha} overexpression was also significantly associated with favorable chemotherapy response (Table 7)Citation . Of 9 patients with overexpression, 5 had a CR or MRD, 2 had a PR, and 2 had StD or PD, versus 3 with CR or MRD, 17 with PR, and 6 with StD or PD among those without overexpression (P = 0.021). If patients with CR or MRD versus all of the other responses are compared, P = 0.015. None of the four patients with overexpression who failed to achieve a CR or MRD had amplification, which suggests that gene amplification is a more specific marker for favorable response than overexpression as detected by immunohistochemistry. Also, two of the three patients without overexpression who achieved CR or MRD had amplification, which suggests that immunohistochemistry alone should not be used to infer that a patient is unlikely to benefit from anthracycline-based therapy. Nevertheless, three of the five patients with overexpression who achieved CR or MRD were not amplified. This suggests that overexpression of topoisomerase II{alpha} by immunohistochemistry, in the absence of amplification, may sometimes be biologically meaningful. Of the eight patients who achieved CR or MRD, only one had neither overexpression nor amplification.


View this table:
[in this window]
[in a new window]

 
Table 6 Amplification of topoisomerase II{alpha} is related to chemotherapy response

Amplification of topoisomerase II{alpha}, as determined by FISH, was significantly associated with more favorable tumor response to chemotherapy (P = 0.034). If CR or MRD versus all of the other responses are compared, P = 0.016. Response was determined by comparison of the breast tumor at presentation with the mastectomy specimen. CR = complete response, MRD = minimal residual disease, PR = partial response, SD = stable disease, PD = progressive disease.

 

View this table:
[in this window]
[in a new window]

 
Table 7 Overexpression of topoisomerase II{alpha} is associated with chemotherapy response

Topoisomerase II{alpha} overexpression was significantly associated with favorable chemotherapy response (P = 0.021). If patients with CR or MRD versus all of the other responses are compared, P = 0.015. Response was determined by comparison of the breast tumor at presentation with the mastectomy specimen.

 
Consideration of Other Tumor and Patient Factors.
Other available patient and tumor factors for which an association with response to therapy seemed reasonably likely were tested for such an association. There was no evidence for an association between response and patient age, the histological type of the tumor (ductal, lobular, or unspecified), tumor grade (II or III), tumor stage (IIB, IIIA, or IIIB), estrogen or progesterone receptor status (immunohistochemistry by a commercial reference laboratory), or type of chemotherapy (doxorubicin and docetaxel versus CAF). None of these factors was significantly associated with those which predicted response (erbB-2 amplification, topoisomerase II{alpha} amplification or overexpression) except patient age, which was associated with topoisomerase II{alpha} amplification (P = 0.015).


    DISCUSSION
 Top
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Some large studies have reported a positive association between erbB-2 overexpression and favorable response to anthracyclines in breast cancer (4 , 5) , but the existence of this association and its underlying mechanism remain controversial (15) . This study sought to clarify several issues related to this putative association. The patients included were quite uniform with regard to stage and presentation, all falling into the relatively uncommon category of LABC. This group of patients permitted assessing a very well-defined measure of response to neoadjuvant chemotherapy, namely the effect on the tumor in the breast at the time of mastectomy. Clearly, systemic tumor response (development of clinically evident metastases) and survival are also extremely important in evaluating the efficacy of chemotherapy and will be evaluated in this group of patients when sufficient data become available. Nevertheless, these other end points appear to involve a multitude of tumor and host factors, in addition to drug sensitivity of the tumor cells. Other important features of this study are that we determined both overexpression and gene amplification for erbB-2, using a FISH strategy the performance characteristics of which have been well documented (11) . Also included were expression and gene amplification studies on topoisomerase II{alpha}, based on the recent documentation that this gene is often coamplified with erbB-2 in breast cancer and is a well-known target for topoisomerase II{alpha} poisons, including the anthracyclines (9 , 16) . This suggests that coamplification of topoisomerase II{alpha} with erbB-2 may be the principal mechanism underlying the putative relationship between erbB-2 overexpression and response to anthracyclines.

Our data showed a highly significant association between erbB-2 amplification and favorable response to anthracyclines. The association between overexpression and response nevertheless failed to reach statistical significance, and no evidence was found for a link between overexpression and response in patients without amplification. These observations suggest that favorable response is associated with erbB-2 amplification, rather than overexpression itself. Although erbB-2 amplification and high-level overexpression are strongly linked in breast cancer, overexpression (compared with normal breast epithelium) without amplification is also well documented in the literature (6 , 10) . A recent report using special methods for quantifying overexpression suggests that overexpression in the absence of amplification is at a lower level than that associated with amplification (10) . It is also important to recognize that using immunohistochemistry as a quantitative measure of erbB-2 expression is sometimes quite difficult in the small needle biopsies that comprised the patient material in this study, because of tissue edge artifacts and uncertain discrimination between specific and nonspecific staining. Therefore, some of the tumors that were scored as high-level overexpressers and that did not have amplification may actually represent low-level overexpressers (false positives). Two of the patients with erbB-2 amplification were not scored as overexpressers and are presumed to be false negatives. This problem has been recognized in previous studies comparing FISH with immunohistochemistry for erbB-2, and has been attributed to protein degradation in the paraffin-embedded material, in addition to the interpretation problems mentioned above (11) . This implies that the FISH assay may be technically more robust for evaluating the clinically important erbB-2 status of tumors, especially in needle biopsies such as were used in this study. This idea is supported by a recent report demonstrating greater reliability of amplification assays than immunohistochemistry for predicting prognosis based on erbB-2 status (11) . The marginal association between overexpression and response is also consistent with an important role for topoisomerase II{alpha}, because amplification of the two genes was tightly linked in our patients and in other studies (9) .

Our data support the idea that topoisomerase II{alpha} amplification in clinical breast cancer specimens occurs as a result of proximity to the oncogene, erbB-2, because all cases with topoisomerase II{alpha} amplification had erbB-2 amplification, but not vice versa. In contrast to the findings of Jarvinen et al. (9) , however, who described deletion of topoisomerase II{alpha} with frequency equal to amplification in tumors with erbB-2 amplification, we did not detect topoisomerase II{alpha} deletions. The probe set used in our study was designed primarily for detecting amplification of the topoisomerase II{alpha} region in a three-probe multicolor assay. This provides the advantage of measuring the erbB-2, topoisomerase II{alpha}, and chromosome 17 centromere copy numbers in each cell individually, allowing accurate identification of clonal variations. As a result, the topoisomerase II{alpha} target region was significantly larger than that used by Jarvinen et al. (9) . Therefore, their probe may have detected smaller deletions that may have been missed with our probe. Another possibility is that their smaller probe is associated with lower hybridization and/or detection efficiency, leading to the artifactual appearance of deletions in some cases. It is unclear at present whether discriminating between tumors that have deletion of one topoisomerase II{alpha} allele, versus those that have two alleles (not amplified), would be biologically or clinically significant.

Both the gene amplification and expression data for topoisomerase II{alpha} are consistent with the notion that this protein is an important determinant of sensitivity of breast cancer to anthracycline-based therapy. This potentially important conclusion requires confirmatory evidence from additional studies because of the small size and retrospective nature of the study population. The disparity between amplification and overexpression may be partly explained by the fact that topoisomerase II{alpha} is a cell cycle-regulated protein. In fact the frequency of topoisomerase II{alpha} expression in a population of cells is tightly linked to the rate of cell proliferation, and topoisomerase II{alpha} has been suggested as a proliferation marker (17) . This probably tends to obscure the relationship between gene amplification and overexpression. Attempting to quantify protein expression by immunohistochemistry in small biopsy samples is also difficult, as discussed above. Our data suggest that measuring topoisomerase II{alpha} amplification by FISH is more specific than measuring expression by immunohistochemistry for predicting anthracyline responsiveness, because four of six patients with amplification had CR or MRD, and the other two had PR. Previous studies of topoisomerase II{alpha} expression versus response to drugs that target it have been inconsistent in finding a significant relationship (18 , 19) . It also appears likely, however, that FISH may miss some tumors with biologically significant topoisomerase II{alpha} overexpression, because four patients without amplification had CR or MRD, and all but one of these had topoisomerase II{alpha} overexpression. It may be that patients who have neither amplification nor overexpression should be offered an alternative to anthracyclines, because only one such patient had CR or MRD in our series. Clearly, however, more patients must be studied to arrive at conclusions sufficiently secure to provide the basis for planning treatment. It also appears likely that developing an optimal clinical assay for topoisomerase II{alpha} may be at least as complex as the process for erbB-2. Measuring phosphorylation of topoisomerase II{alpha} may also be useful because its activity may be so regulated (20) .

This study does not completely settle the question of whether erbB-2 amplification plays a functional role in determining favorable response to certain anticancer drugs, or is only a marker for topoisomerase II{alpha} coamplification. We found only two patients with isolated erbB-2 amplification; one had MRD, and the other PR. More patients of this kind are needed to test the hypothesis that LABC patients with erbB-2 amplification alone will not respond as well to anthracycline-based therapy as those who have coamplification of topoisomerase II{alpha}. erbB-2 overexpression has been associated with a favorable response to taxanes, perhaps because erbB-2 overexpression activates mitogen-activated protein kinase, which mediates Taxol-induced cell killing (21) . A mechanism based on facilitating response to taxanes does not appear to explain our data, however, because there was no apparent association between tumor response and whether or not a taxane (versus cyclophosphamide and 5-fluorouracil) was combined with doxorubicin. Prospective clinical studies in which patients receive a course of anthracycline alone and taxane alone may be needed to further resolve this important question.


    FOOTNOTES
 
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

1 Support for this study was provided by the Bears Care Fund, Brian Piccolo Foundation, and the Aventis Corporation. This work was presented in part at the Annual AACR Meeting, April 2001, New Orleans. Back

2 To whom requests for reprints should be addressed, at Department of Pathology, Rush Medical College, 1653 West Congress Parkway, Chicago, IL 60612. Phone: (312) 942-5250; Fax: (312) 666-7250; E-mail: jcoon{at}rush.edu Back

3 The abbreviations used are: LABC, locally advanced breast cancer; FISH, fluorescence in situ hybridization; CR, complete response; MRD, minimal residual disease; PR, partial response; MR, minimal response, StD, stable disease; PD, progressive disease; DAPI, 4,6-diamidino-2-phenylindole; CAF, cyclophosphamide-doxorubicin-5 fluorouracil. Back

Received 6/12/01; revised 11/30/01; accepted 12/15/01.


    REFERENCES
 Top
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

  1. McMasters K. M., Hunt K. K. Neoadjuvant chemotherapy, locally advanced breast cancer, and quality of life. J. Clin. Oncol., 17: 441-444, 1999.[Free Full Text]
  2. Colleoni M., Minchella I., Mazzarol G., Nole F., Peruzzotti G., Rocca A., Viale G., Orlando L., Ferretti G., Curigliano G., Veronesi P., Intra M., Goldhirsch A. Response to primary chemotherapy in breast cancer patients with tumors not expressing estrogen and progesterone receptors. Ann. Oncol., 11: 1057-1059, 2000.[Abstract/Free Full Text]
  3. Chang J., Omerod M., Powles T. J., Allred D. C., Ashley S. E., Dowsett M. Apoptosis and proliferation as predictors of chemotherapy response in patients with breast carcinoma. Cancer (Phila.), 89: 2145-2152, 2000.[CrossRef][Medline]
  4. Thor A. S., Berry D. A., Budman D. R., Muss H. B., Kute T., Henderson I. C., Barcos M., Cirrincione C., Edgerton S., Allred I. C., Norton L., Liu E. T. ErbB-2, p53, and efficacy of adjuvant therapy in lymph node-positive breast cancer. J. Natl. Cancer Inst. (Bethesda), 90: 1346-1360, 1998.[Abstract/Free Full Text]
  5. Paik S., Bryant J., Park C., Fisher B., Tan-Chiu E., Hyams D., Fisher E. R., Lippman M. E., Wickerham M. E., Wolmark N. ErbB-2 and response to doxorubicin in patients with axillary lymph node-positive, hormone receptor-negative breast cancer. J. Natl. Cancer Inst. (Bethesda), 90: 1361-1370, 1998.[Abstract/Free Full Text]
  6. Press M. F., Bernstein L., Thomas P. A., Meisner L. F., Zhou J.-Y., Ma Y., Hung G., Robinson R. A., Harris C., El-Naggar A., Slamon D. J., Phillips R. N., Ross J. S., Wolman S. R., Flom K. J. HER-2/neu gene amplification characterized by fluorescence in situ hybridization: poor prognosis in node-negative breast carcinomas. J. Clin. Oncol., 15: 2894-2904, 1997.[Abstract]
  7. Slamon D. J., Clark G. M., Wong S. G., Levin W. J., Ullrich A., McGuire W. L. Human breast cancer: correlation of relapse and survival with amplification of the HER-2/neu oncogene. Science (Wash. DC), 235: 177-182, 1987.[Abstract/Free Full Text]
  8. Pegram M. D., Ginn R. S., Arzoo K., Beryt M., Pietras R. J., Slamon D. J. The effect of HER-2/neu overexpression on chemotherapeutic drug sensitivity in human breast and ovarian cancer cells. Oncogene, 15: 537-547, 1997.[CrossRef][Medline]
  9. Jarvinen T. A. H., Tanner M., Rantanen V., Barlund M., Borg A., Grenman S., Isola J. Amplification and deletion of topoisomerase II{alpha} associate with erbB-2 amplification and affect sensitivity to topoisomerase II inhibitor doxorubicin in breast cancer. Am. J. Pathol., 156: 839-847, 2000.[Abstract/Free Full Text]
  10. Robertson K. W., Reeves J. R., Smith G., Keith W. N., Ozanne B. W., Cooke T. G., Stanton P. D. Quantitative estimation of epidermal growth factor receptor and c-erbB-2 in human breast cancer. Cancer Res., 56: 3823-3830, 1996.[Abstract/Free Full Text]
  11. Pauletti G., Dandekar S., Rong H., Ramos L., Peng H., Seshadri R., Slamon D. J. Assessment of methods for tissue-based detection of the HER-2/neu alteration in human breast cancer: a direct comparison of fluorescence in situ hybridization and immunohistochemistry. J. Clin. Oncol., 18: 3651-3664, 2000.[Abstract/Free Full Text]
  12. Thor A. D., Liu S., Edgerton S., Moore D., Kasowitz K. M., Benz C. C., Stern D. F., DiGiovanna M. P. Activation (tyrosine phosphorylation) of erbB-2 (HER-2/neu): a study of incidence and correlation with outcome in breast cancer. J. Clin. Oncol., 18: 3230-3239, 2000.[Abstract/Free Full Text]
  13. Venkatesan T. K., Kuropkat C., Caldarelli D. D., Panje W. R., Hutchinson J. C., Chen S., Coon J. S. Prognostic significance of p27 expression in carcinoma of the oral cavity and oropharynx. Laryngoscope, 109: 1329-1333, 1999.[CrossRef][Medline]
  14. Hopman A. H. N., Claessen J. S., Speel E. J. M. Multi-color brightfield in situ hybridization on tissue section. Histochem. Cell Biol., 108: 291-298, 1997.[CrossRef][Medline]
  15. Vincent-Salomon A., Carton M., Frenaux P., Palangie T., Beuzeboc P., Mouret E., de Cremoux P., Coue O., Zafrani B., Nicolas A., Clough K., Fourquet A., Pouillart P., Sastre-Garau X. ERBB2 overexpression in breast carcinomas: no positive correlation with complete pathological response to preoperative high-dose anthracyline-based chemotherapy. Eur. J. Cancer, 36: 586-591, 2000.
  16. Nitiss J. L., Beck W. T. Antitopoisomerase drug action and resistance. Eur. J. Cancer, 12A: 958-966, 1996.
  17. Holden J. A. Human deoxyribonucleic acid topoisomerases: Molecular targets of anticancer drugs. Ann. Clin. Lab. Science, 27: 402-412, 1997.
  18. Dingemans A. C., Witlox M. A., Stallaert R.A.L.M., van der Valk P., Postmus P. E., Giaccone G. Expression of DNA topoisomerase II{alpha} and topoisomerase IIß genes predicts survival and response to chemotherapy in patients with small cell lung cancer. Clin. Cancer Res., 5: 2048-2058, 1999.[Abstract/Free Full Text]
  19. Klumper E., Giaccone G., Pieters R., Broekema G., van Ark-Otte J., van Wering E. R., Kaspers G. J. L., Veerman A. J. P. Topoisomerase II{alpha} gene expression in childhood acute lymphoblastic leukemia. Leukemia (Baltimore), 9: 1653-1660, 1995.[Medline]
  20. Oloumi A., Macphail S. H., Johnston P. J., Banath J. P., Olive P. L. Changes in subcellular distribution of topoisomerase II{alpha} correlate with etoposide resistance in multicell spheroids and xenograft tumors. Cancer Res., 60: 5747-5753, 2000.[Abstract/Free Full Text]
  21. Baselga J., Seidman A. D., Rosen P. P., Norton L. HER2 overexpression and paclitaxel sensitivity in breast cancer: Therapeutic implications. Oncology, 11 (Suppl. 2): 43-48, 1997.



This article has been cited by other articles:


Home page
The OncologistHome page
J. S. Ross, E. A. Slodkowska, W. F. Symmans, L. Pusztai, P. M. Ravdin, and G. N. Hortobagyi
The HER-2 Receptor and Breast Cancer: Ten Years of Targeted Anti-HER-2 Therapy and Personalized Medicine
Oncologist, April 1, 2009; 14(4): 320 - 368.
[Abstract] [Full Text] [PDF]


Home page
Clin. Cancer Res.Home page
M. Dowsett and A. K. Dunbier
Emerging Biomarkers and New Understanding of Traditional Markers in Personalized Therapy for Breast Cancer
Clin. Cancer Res., December 15, 2008; 14(24): 8019 - 8026.
[Abstract] [Full Text] [PDF]


Home page
Proc. Natl. Acad. Sci. USAHome page
R. J. Leary, J. C. Lin, J. Cummins, S. Boca, L. D. Wood, D. W. Parsons, S. Jones, T. Sjoblom, B.-H. Park, R. Parsons, et al.
Integrated analysis of homozygous deletions, focal amplifications, and sequence alterations in breast and colorectal cancers
PNAS, October 21, 2008; 105(42): 16224 - 16229.
[Abstract] [Full Text] [PDF]


Home page
Ann OncolHome page
D. Rayson, D. Richel, S. Chia, C. Jackisch, S. van der Vegt, and T. Suter
Anthracycline-trastuzumab regimens for HER2/neu-overexpressing breast cancer: current experience and future strategies
Ann. Onc., September 1, 2008; 19(9): 1530 - 1539.
[Abstract] [Full Text] [PDF]


Home page
JCOHome page
F. Cardoso, M. Saghatchian, A. Thompson, E. Rutgers, and for the TRANSBIG Consortium Steering Committee
Inconsistent Criteria Used in American Society of Clinical Oncology 2007 Update of Recommendations for the Use of Tumor Markers in Breast Cancer
J. Clin. Oncol., April 20, 2008; 26(12): 2058 - 2059.
[Full Text] [PDF]


Home page
Journal of Pharmacy PracticeHome page
L.-P. P. Tran and J. L. Grabinski
Chemotherapy for Early-Stage Breast Cancer: A Paradigm in Flux
Journal of Pharmacy Practice, February 1, 2008; 21(1): 46 - 56.
[Abstract] [PDF]


Home page
The OncologistHome page
A. Morabito, M. C. Piccirillo, K. Monaco, C. Pacilio, F. Nuzzo, P. Chiodini, C. Gallo, A. de Matteis, F. Perrone, and NCI Naples Breast Cancer Group
First-Line Chemotherapy for HER-2 Negative Metastatic Breast Cancer Patients Who Received Anthracyclines as Adjuvant Treatment
Oncologist, November 1, 2007; 12(11): 1288 - 1298.
[Abstract] [Full Text] [PDF]


Home page
The OncologistHome page
J. T. Jorgensen, K. V. Nielsen, and B. Ejlertsen
Pharmacodiagnostics and Targeted Therapies--A Rational Approach for Individualizing Medical Anticancer Therapy in Breast Cancer
Oncologist, April 1, 2007; 12(4): 397 - 405.
[Abstract] [Full Text] [PDF]


Home page
J. Clin. Pathol.Home page
M Tretiakova, M Turkyilmaz, T Grushko, M Kocherginsky, C Rubin, B Teh, and X J Yang
Topoisomerase II{alpha} in Wilms' tumour: gene alterations and immunoexpression
J. Clin. Pathol., December 1, 2006; 59(12): 1272 - 1277.
[Abstract] [Full Text] [PDF]


Home page
JCOHome page
M. Tanner, J. Isola, T. Wiklund, B. Erikstein, P. Kellokumpu-Lehtinen, P. Malmstrom, N. Wilking, J. Nilsson, and J. Bergh
Topoisomerase II{alpha} Gene Amplification Predicts Favorable Treatment Response to Tailored and Dose-Escalated Anthracycline-Based Adjuvant Chemotherapy in HER-2/neu-Amplified Breast Cancer: Scandinavian Breast Group Trial 9401
J. Clin. Oncol., June 1, 2006; 24(16): 2428 - 2436.
[Abstract] [Full Text] [PDF]


Home page
JCOHome page
A. U. Buzdar
Topoisomerase II{alpha} Gene Amplification and Response to Anthracycline-Containing Adjuvant Chemotherapy in Breast Cancer
J. Clin. Oncol., June 1, 2006; 24(16): 2409 - 2411.
[Full Text] [PDF]


Home page
Clin. Cancer Res.Home page
N. Tinari, R. Lattanzio, C. Natoli, E. Cianchetti, D. Angelucci, E. Ricevuto, C. Ficorella, P. Marchetti, S. Alberti, M. Piantelli, et al.
Changes of Topoisomerase II{alpha} Expression in Breast Tumors after Neoadjuvant Chemotherapy Predicts Relapse-Free Survival
Clin. Cancer Res., March 1, 2006; 12(5): 1501 - 1506.
[Abstract] [Full Text] [PDF]


Home page
Ann OncolHome page
M. Colozza, E. Azambuja, F. Cardoso, C. Sotiriou, D. Larsimont, and M. J. Piccart
Proliferative markers as prognostic and predictive tools in early breast cancer: where are we now?
Ann. Onc., November 1, 2005; 16(11): 1723 - 1739.
[Abstract] [Full Text] [PDF]


Home page
JCOHome page
A. S. Knoop, H. Knudsen, E. Balslev, B. B. Rasmussen, J. Overgaard, K. V. Nielsen, A. Schonau, K. Gunnarsdottir, K. E. Olsen, H. Mouridsen, et al.
Retrospective Analysis of Topoisomerase IIa Amplifications and Deletions As Predictive Markers in Primary Breast Cancer Patients Randomly Assigned to Cyclophosphamide, Methotrexate, and Fluorouracil or Cyclophosphamide, Epirubicin, and Fluorouracil: Danish Breast Cancer Cooperative Group
J. Clin. Oncol., October 20, 2005; 23(30): 7483 - 7490.
[Abstract] [Full Text] [PDF]


Home page
Endocr Relat CancerHome page
P J Barrett-Lee
Growth factor signalling in clinical breast cancer and its impact on response to conventional therapies: a review of chemotherapy
Endocr. Relat. Cancer, July 1, 2005; 12(Supplement_1): S125 - S133.
[Abstract] [Full Text] [PDF]


Home page
Molecular Cancer TherapeuticsHome page
V. Durbecq, M. Paesmans, F. Cardoso, C. Desmedt, A. Di Leo, S. Chan, K. Friedrichs, T. Pinter, S. Van Belle, E. Murray, et al.
Topoisomerase-II{alpha} expression as a predictive marker in a population of advanced breast cancer patients randomly treated either with single-agent doxorubicin or single-agent docetaxel
Mol. Cancer Ther., October 1, 2004; 3(10): 1207 - 1214.
[Abstract] [Full Text] [PDF]


Home page
Mol. Cell. ProteomicsHome page
J. S. Ross, J. A. Fletcher, K. J. Bloom, G. P. Linette, J. Stec, W. F. Symmans, L. Pusztai, and G. N. Hortobagyi
Targeted Therapy in Breast Cancer: The HER-2/neu Gene and Protein
Mol. Cell. Proteomics, April 1, 2004; 3(4): 379 - 398.
[Abstract] [Full Text] [PDF]


Home page
The OncologistHome page
S. H. Giordano
Update on Locally Advanced Breast Cancer
Oncologist, December 1, 2003; 8(6): 521 - 530.
[Abstract] [Full Text] [PDF]


Home page
The OncologistHome page
J. S. Ross, J. A. Fletcher, G. P. Linette, J. Stec, E. Clark, M. Ayers, W. F. Symmans, L. Pusztai, and K. J. Bloom
The HER-2/neu Gene and Protein in Breast Cancer 2003: Biomarker and Target of Therapy
Oncologist, August 1, 2003; 8(4): 307 - 325.
[Abstract] [Full Text] [PDF]


Home page
Am. J. Pathol.Home page
D. E. Hansel, A. Rahman, M. Hidalgo, P. J. Thuluvath, K. D. Lillemoe, R. Shulick, J.-L. Ku, J.-G. Park, K. Miyazaki, R. Ashfaq, et al.
Identification of Novel Cellular Targets in Biliary Tract Cancers Using Global Gene Expression Technology
Am. J. Pathol., July 1, 2003; 163(1): 217 - 229.
[Abstract] [Full Text] [PDF]


Home page
Cancer Res.Home page
S. Park and C. D. James
Lanthionine Synthetase Components C-like 2 Increases Cellular Sensitivity to Adriamycin by Decreasing the Expression of P-Glycoprotein through a Transcription-mediated Mechanism
Cancer Res., February 1, 2003; 63(3): 723 - 727.
[Abstract] [Full Text] [PDF]


Home page
Clin. Cancer Res.Home page
J. Climent, J. A. Martinez-Climent, D. Blesa, M. J. Garcia-Barchino, R. Saez, D. Sanchez-Izquierdo, P. Azagra, A. Lluch, and J. Garcia-Conde
Genomic Loss of 18p Predicts an Adverse Clinical Outcome in Patients with High-Risk Breast Cancer
Clin. Cancer Res., December 1, 2002; 8(12): 3863 - 3869.
[Abstract] [Full Text] [PDF]


This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Coon, J. S.
Right arrow Articles by Preisler, H. D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Coon, J. S.
Right arrow Articles by Preisler, H. D.


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Cancer Research Clinical Cancer Research
Cancer Epidemiology Biomarkers & Prevention Molecular Cancer Therapeutics
Molecular Cancer Research Cancer Prevention Research
Cancer Prevention Journals Portal Cancer Reviews Online
Annual Meeting Education Book Meeting Abstracts Online