Clinical Relevance of Early Disseminated Breast Cancer Cells Depends on Their Cytokeratin Expression Pattern

Background: The factors determining the clinical relevance of disseminated tumor cells (DTC) in breast cancer patients are largely unknown. Here we compared the specificity and clinical performance of two anti-cytokeratin(CK) antibodies frequently used for DTC detection, namely A45-B/B3 (A45) and AE1/AE3 (AE). Additionally we explored the CK gene expression patterns in primary breast tumors.Methods: Specificities of antibodies A45 and AE for selected CKs were assessed by 2-DE western blot analysis. Using these antibodies bone marrow aspirates from 391 breast cancer patients (M0, pT1-3, pN0-3) were screened for the presence of DTC. To obtain prognostic information, patients were followed up over a median of 83 months for time to relapse and 99 months for time to death. Two breast cancer patient datasets (Oslo (n=123), and van de Vijver et al. (NEJM 2002; n=295)) were analysed for CK primary tumor gene expression patterns and grouped by hormone receptor (HR) status of the primary tumors. T-tests and hierarchial clustering analyses were applied.Results: AE detected CK5, CK7, CK8, and CK19, whereas A45 recognized CK7 and CK18. In total, 24 of 391 patients (6.1%) were DTC-positive for A45, and 41 (10.5%) for AE. Although concordance between the two antibodies was 84.4%, overlap among positive cases was only 3.2%. DTC-positivity with AE and A45 was more frequent in patients of higher nodal status (p=0.019 and p=0.036, respectively). Nearly all patients with A45-positive DTC had hormone receptor-positive tumors (23/24), while detection of AE-positive DTC was more frequent among hormone receptor negative patients (p=0.006). Clear differences in primary tumor CK expression patterns between HR+ and HR- tumors were detected in both datasets. Compared to HR- tumors, CKs up-regulated in HR+ tumors were CK8 and 18, in addition CK19 in two datasets, whereas e.g. CK5, CK6, CK7, CK14, CK15, CK16, and CK17 were significantly down-regulated.Survival analyses of all patients revealed shorter distant disease-free survival (p=0.039) for patients with A45-positive DTC, whereas the prognostic relevance of AE-positive DTC was restricted to node positive patients.Conclusion: The clinical utility of immunocytochemical DTC detection depends on the anti-CK antibody used, which may reflect the complex CK composition of DTC. Tumor CK expression patterns and their correlation to antibody-sprecific DTC detection will further be explored by A45- and AE- staining of corresponding patient samples.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3021.

Detect-Study: Comparison of Two Techniques for the Evaluation of the HER2 Expression on Circulating Tumor Cells in Metastatic Breast Cancer

Introduction:There is a growing body of evidence that the HER2 status can change during disease progression (Gancberg et al. 2003). However, the re-assessment of the HER2 status to evaluate the eligibility for HER2 targeted therapy by a tissue biopsy of the metastatic lesion may not always be feasible. In this context, determination of the HER2 status using CTCs might be a strategy with potential clinical application. So far, no large prospective studies were performed comparing different methods for CTCs detection and characterization. The aim of this trial was to determine the HER2 status of CTCs in metastatic breast cancer patients using the antibody based CellSearch©assay and the RT-PCR approach AdnaTest Breast Cancer and to assess the concordance rate between these two techniques. Both techniques are frequently used in clinical trials.Method:A total of 252 metastatic breast cancer patients from 9 different certified breast cancer centers (Düsseldorf, Erlangen, Essen, Freiburg, Hamburg, Heidelberg, Muenchen, Regensburg, Tuebingen) were enrolled in this prospective open trial from 01/2008 until 04/2009. HER2 status of CTCs was assessed using both the FDA approved CellSearch©Assay (Veridex, Warren, NJ, USA) and the AdnaTest Breast Cancer (Adnagen, Langenhagen, Germany) according to the manufacturers' instructions. A web based databank was designed for data management and online-documentation (www. detect-study.de). The study design was approved by the ethics' comittee (2007/B01).Results:Using the CellSearch©Assay, 133 of 252 (55%) metastatic patients had CTCs at the time of first diagnosis or disease progression. HER2 positivity was observed in 39% of CTC positive patients (52 of 133) but only 22 of these had initially a HER2 positive primary tumor. Eighty-eight of 225 (39%) patients were CTC positive using the AdnaTest Breast Cancer. The HER2 positivity rate was 47% (41 of 88). Eight of these patients had a HER2 positive primary tumor whereas 33 patients were initially HER2 negative or unknown. Summarizing the data, the rate of breast cancer patients with HER2 negative primary tumors but HER2 positive circulating tumor cells was 38% (32 of 61) and 48% (28 of 41) using the CellSearch Assay and the AdnaTest Breast Cancer, respectively. Considering only those patients who had CTCs on both tests (n=61), the concordance rate regarding HER2 expression was 51% (32 of 61).Conclusion:Based on CTCs the HER2 status can change during disease progression. However, using different techniques, disconcordant results were obtained. To prove the clinical value of these CTC assays and to implement the HER2 status of CTCs as a stratification parameter in future clinical trials, it will be mandatory to correlate clinical response to HER2 targetd therapy on each method in patients with HER2 positive CTCs.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3004.

Prospective Evaluation of Serum HER2 and HER2 Expression on Circulating Tumor Cells in Patients with Metastatic Breast Cancer within the DETECT Study

Background: Assessment of HER2 status at the time of metastatic disease might help to optimize treatment decisions in patients with no HER2 status determined at first diagnosis and could also be helpful since HER2 status may change during disease progression. In this context, determination of serum HER2 or the evaluation of HER2 status on circulating tumor cells (CTC) is of potential relevance especially for optimizing HER2-directed therapy. The aim of this study was therefore to determine the serum HER2 status and the HER2 status of CTC from corresponding patients.Methods: Blood samples were obtained in a prospective multicenter setting from 251 patients with metastatic breast cancer at the time of disease progression. Serum HER2 was determined using the commercial HER2 ELISA-kit (Oncogene Science). CTC were detected and HER2 expression was assessed with the CellSearch™ system (Veridex).Results: 119 of 251 (47%) metastatic patients had elevated serum HER2 levels above 15 ng/mL. Serum HER2 was elevated in 49 (66%) of 74 patients with HER2 positive primary tumors, in 57 of 148 (39%) with HER2 negative primary tumors and in 13 of 29 (45%) patients with unknown HER2 primary tumor status. CTC were detected in 133 of 243 evaluable patients (5 or more cells), in these HER2 overexpression on CTC (strong overexpression in at least one cell) was detected in 52 cases (39%). Only 20 of these patients had a HER2 positive primary tumor. In patients with HER2 positive CTC, serum levels were above the cut off in 34 of 52 (65%), while in those with HER2 negative CTC 44 of 81 (54%) showed elevated HER2 serum levels. Concordance between HER2 status of circulating tumor cells and elevated serum HER2 was seen in 71 of 133 patients (53%).Conclusions: Our study demonstrates with a prospective design that also in patients with initially negative HER2 tumor status elevated serum HER2 levels and/or HER2 positive CTC can be detected at the time of metastatic disease. This is of clinical relevance since these patients in current practice do not have access to HER2 targeted therapy.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3050.

Use of bone marrow micrometastasis to predict disease-free and overall survival in esophageal cancer: Evaluation of 304 cases

4519

Background: The presence of bone marrow micrometastases (BMM) yields prognostic information for patients at higher risk for recurrence and death. Aim of the study was to evaluate the role of BMM in esophageal cancer (EC). Methods: 304 consecutive patients operated for EC and with BMM status were included into the prospective study. BMM were assessed by a pan-anti- cytokeratin monoclonal antibody, A45-B/B3. Associations between BMM status and clinicopathological parameters as well as disease-free (DFS) and overall survival (OS) were calculated with chi-square-, log-rank test and Cox multivariate analysis. Results: Out of 304 patients 109 (35.9%) were BMM positive (BMM+) and 195 (64.1%) negative (BMM-). Significant correlation was found between BMM and tumor size, nodal stage and recurrence (P=0.02, 0.002 and <0.0001). DFS and OS were significantly better in BMM- compared to BMM+ patients (median 44.2 and 31.6 vs. 10.4 and 12.4 months, P<0.0001). Sub-analyses revealed that nodal negative (N-) patients with BMM- had a significant better DFS and OS compared to N- and BMM+ patients (50.8 and 41.5 vs. 18.0 and 16.3 months, P<0.0001). Nodal positive patients (N+) with BMM- had a better DFS and OS compared to N+ and BMM+ patients (22.1 and 24.8 vs. 9.0 and 11.3 months, P<0.0001). In the Cox multivariate analysis BMM was the strongest predictor of DFS and OS with a hazard ratio of 3.1 and 2.9 (P<0.0001). Also tumor size and nodal stage were found to be significant predictors, whereas age and sex were not. All analyses were repeated after stratification of the study group to underlying tumor type (adenocarcinoma (AC) and squamous cell carcinoma (SCC)). Significant differences were found at all levels as reported for the entire study group above within the AC and SCC group as well. Conclusions: To our knowledge this is the largest study evaluating the role of BMM in EC. Survival sub-analyses stratified to nodal and bone marrow status revealed a significant role of BMM in EC. Presence of BMM proved to be the strongest predictor of DFS and OS in AC and SCC of the esophageus.

No significant financial relationships to disclose.

Persistance of circulating tumor cells (CTCs) in peripheral blood of breast cancer (BC) patients two years after primary diagnosis

554

Background: In metastatic BC, CTCs have shown to predict treatment efficacy and reduced survival. Recent data also indicate a potential prognostic relevance of CTCs after adjuvant chemotherapy. The SUCCESS trial evaluates the role of persisting CTCs two years after diagnosis in primary BC patients treated with zoledronate. Methods: We analyzed 23 mL of peripheral blood in N+ and high-risk N- primary BC pts receiving 3xFEC(500/100/500)-3xDoc100 q3w vs. 3xFEC(500/100/500)-3xDocgemcitabine (75/1000 d1+8) chemotherapy followed by 2 yrs (4mg q3mx24m) vs. 5 yrs (4mg q3mx24m followed by q6mx36m) of zoledronate. CTC results after two years are shown. CTCs were assessed with the CellSearchSystem (Veridex, Warren, USA). After immunomagnetic enrichment with an anti-Epcam-antibody, cells were labelled with anti-cytokeratin (8,18,19) and anti-CD45 antibodies. Pts were examined after a mean of 29 months (range 20–43). Results: The data of 579 pts two years after diagnosis are available. 4.3% of pts (n = 25) presented with >1CTC in peripheral blood. In pts with the detection of CTCs, the mean number of cells was 1 (range 1–29). While we found 1 CTC in 5.9% and 2 CTCs in 1.6% of pts, 1.5% had 3–5 CTCs, 1.2% >5 CTCs. The presence of >1CTC did not correlate with tumor size (p = 0.41), nodal status (p = 0.41), grading (p = 0.45), hormonal status (p = 0.92) or HER-2-Status of the tumor (p = 0.59). In this patient group, 9.7% and 6.9% of pts had presented with >1CTC at primary diagnosis and after chemotherapy, respectively. While the presence of CTCs at diagnosis was associated with CTCs after two years (p = 0.03), there was no correlation of CTCs after chemotherapy with the results at primary diagnosis (p = 0.08) or at two years (p = 0.23). In 184 postmenopausal HR+ pts endocrine treatment data was analyzed. CTCs at two years were detected in 6.8% of pts on tamoxifen (n = 9), while 1.9% of pts were positive on anastrozole treatment (n = 1; p = 0.19). Conclusions: CTCs persisting cytostatic, endocrine and zoledronate treatment, can be observed in a relevant number of clinically recurrence-free BC patients. Longer follow-up within the German SUCCESS study will give further insight in their prognostic relevance and show whether they can be used for real time tumor phenotyping or serve as treatment target.

[Table: see text]

Persistence of isolated tumor cells in the bone marrow of breast cancer patients predicts increased risk for relapse – a European pooled analysis

Abstract #304

Purpose:&#x2028; The prognostic significance of DTC in the BM of breast cancer pts at the time of primary diagnosis has already been confirmed by a large pooled analysis. In view of the lack of early indicators for secondary adjuvant treatment, we here evaluated whether the persistence of DTC after adjuvant therapy confers a risk for relapse and breast cancer-related death.&#x2028; Patients and Methods:&#x2028; We analyzed BM aspirates of 723 pts from academic breast cancer units in Oslo (n=356), Munich (n=228) and Tuebingen (n=139) during recurrence-free follow-up at a mean interval of 31.7 months (standard deviation [std] 19.4 months) after primary diagnosis of breast cancer pT1-4, pN0-3 pM0. Carcinoma cells were detected using a standardized immunoassay with the monoclonal antibodies A45-B/B3 (Munich, Tuebingen), or AE1 and AE3 (Oslo), directed against cytokeratin (CK). Pts were followed for a median of 54.5 months (SD 25.1 months) after primary diagnosis.&#x2028; Results:&#x2028; Persistent DTC in the BM was detected in 15.5% of the pts (n=112). The Kaplan-Meier estimate for mean distant relapse-free survival was 162.5 months (157.9 – 167.0 95%CI) in pts with negative and 102.4 months (94.2 – 110.6, 95% CI, p&lt; .0001, log rank test) in pts with positive BM status. The mean overall survival was 170.1 months, (167.7 – 172.5 95% CI), compared to 113.4 months in patients with persistent DTC in BM (107.3 – 119.5, p &lt; .0001). In multivariate Cox regression analysis, allowing for BM status, tumor size, nodal status and histopathological grading, presence of DTC was an independent prognostic factor for reduced breast cancer specific survival ((RR 3.42, 1.64 – 7.13 95% CI, p= .001).&#x2028; Conclusion:&#x2028; Persistent DTC significantly predicts an increased risk for subsequent relapse, and, therefore, might serve as a potent monitoring tool for the follow-up of breast cancer pts. Future therapeutic intervention trials are currently being initiated to assess the benefit of secondary adjuvant treatment based on DTC detection as stratification parameter.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 304.

Characterization of the HER2 status on circulating breast cancer cells

Abstract #5018

Background: Detection and characterization of circulating tumor cells (CTC) in the peripheral blood of breast cancer patients could help to guide treatment decisions before the onset of overt metastasis as well as in the setting of advanced disease. The HER2 oncogene is the most prominent therapeutic target in breast cancer and shedding of the extracellular domain of this receptor seems to contribute to constitutive activation of HER2. Here we developed a novel assay to detect shedding of the extracellular domain (ECD) of the HER2 oncogene on single CTC and applied this assay to the analysis of blood from metastatic breast cancer patients.&#x2028; Material and Methods: Using a new dual fluorescent CK19/HER2-EPISPOT assay, the shedding of HER2 ECD by CTC from 49 metastatic breast cancer patients was assessed. In parallel, using the CellSearch system, the number of CTC and their HER2 expression were determined on 42 samples from metastatic breast cancer patients. A subgroup (n=34) of these patients was analyzed with both methods. This work was performed in the context of the activities of the DETECT study group.&#x2028; Results: In the CK19/HER2-EPISPOT assay 24 of 49 (48.9%) patients had CTC (mean, 12.4; median, 5; range 1-141) and among these positive patients, 7 of 24 (29.2%) showed also HER2-secreting CTC (mean, 3.3; median, 2; range, 1-14). Using the CellSearch™ system, in 23/42 (54.8%) patients CTC were found (mean, 82; median, 13; range, 1-656). HER2 staining intensity was heterogeneous even among CTC from the same patient. Regarding the samples analyzed with both methods, we found that 23.5%, 50.0%, 50.0% and 76.5% of the patients were positive with both detection methods, the EPISPOT assay only, the CellSearch™ system only and one or the other method, respectively.&#x2028; Discussion: These findings demonstrate, for the first time, that (i) CTC can secrete HER2 and (ii) HER2 secretion is not closely linked to HER2 CellSearch™ status. Both assays (i.e., EPISPOT and CellSearch™) have a comparative sensitivity and appear to be complementary for the detection and characterization of the HER2-status of CTC.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5018.

Detection, clinical relevance and specific biological properties of disseminating cancer cells in breast cancer patients

Abstract #P2-1

Metastatic relapse of carcinoma patients is mainly due to clinically occult micrometastases present at primary diagnosis, but undetectable even by high-resolution imaging technologies. Frequently, traditional prognostic factors are insufficient to predict metastasis and treatment decisions are mainly based on statistical risk parameters. Highly sensitive and specific cytometric and molecular methods enable now the detection of disseminated tumor cells (DTC) in bone marrow (BM) and circulating tumor cells (CTC) in peripheral blood of breast carcinoma patients. The presence of DTC has prognostic impact for patients with primary breast cancer with regard to metastatic relapse and overall survival (Braun et al, NEJM 2005) and DTC may even contribute to local relapse (Bidard et al., CCR 2008). However, BM analyses are not well accepted by the medical community for the clinical management patients in breast cancer and other solid tumors. Therefore, most current research efforts are directed to evaluate the clinical utility of CTC detection (Pantel & Panabieres, Nat. Clin Pract. Oncol. 2007). Because of the high variability of results obtained by different cytometric and molecular approaches, standardization of current technologies is urgently required (Fehm et al., Cancer 2006; Riethdorf et al., CCR 2008). While the prognostic significance of CTC could be demonstrated for metastatic breast cancer patients (Hayes & Smerage, CCR 2008), studies on the impact of CTC in primary breast cancer patients are still ongoing but the intermediate results are so far promising (Pantel et al., Nat. Clin Pract. Oncol. In press). Moreover, encouraging results on monitoring CTC during primary systemic or adjuvant chemotherapy in breast cancer patients were obtained in recent studies. Now further characterization of CTC is pivotal to understand the biology of tumor cell dissemination (Pantel et al., Nat. Rev. Cancer 2008). The molecular characterization of CTC with special emphasis on potential cancer stem cell features and therapeutically relevant targets such as HER2 (Wülfing et al., CCR 2006) might improve individual risk assessment and stratification of patients for targeted therapies. This characterization will contribute to more “tailored” and personalized anti-metastatic therapies. At present, the success or failure of anti-cancer therapies is only assessed retrospectively by the absence or presence of overt metastases during the post-operative follow up period. Real-time monitoring of peripheral blood (i.e., during and after systemic adjuvant therapy) for CTC might provide unique information for the clinical management of the individual cancer patient and allow an early change in therapy years before the appearance of overt metastases signals incurability (Panabieres et al., CCR 2008). Future clinical trials will show whether the assessment and monitoring of therapeutic targets (e.g., EGF-R, HER2 or VEGF) on CTC (and probably DTC) might become an important diagnostic tool for cancer patients undergoing targeted therapies and may provide new insights into the selection of tumour cells under biological therapies.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr P2-1.

Multicenter study on the detection of disseminated tumor cells in primary breast cancer

Abstract #5021

Background: Detection of disseminated tumor cells (DTC) in bone marrow (BM) has prognostic value in primary breast cancer (BC) and is currently under investigation for therapy stratification and monitoring. Anti-cytokeratin (CK) antibodies (Abs) have been established as markers for detection of such DTC in patients with BC. Here we present a direct comparison of the two Abs most frequently used for DTC detection over the past 10 years.&#x2028; Material and Methods: We screened BM samples from 391 BC patients of which 64 were node-positive (N+). All patients were free of any signs of overt metastases (stage M0, pT1-3, pN0-3). Tumor cells in BM were enriched by Ficoll-Hypaque gradient and the mononuclear cell (MNC) fraction was spun on slides. For each patient 2*106 MNC were analyzed per Ab, using A45-B/B3 (A45) and AE1/AE3 (AE) Abs in parallel. A45 staining was, however, performed a couple of years later than AE staining, on cytospins stored at -80°C. All samples were screened automatically for the presence of CK-positive cells. By morphological evaluation only TC-compatible cells were scored positive. Median follow-up times ranged from 5 to 118 months.&#x2028; Results: For both Abs, the number of DTC revealed was 5 or less. Of the 391 patients, 24 patients (6.1%) were positive for A45, and 41 patients (10.5%) for AE, respectively. Concordance obtained by cross-analysis for the two Abs was 84.4%, whereas the overlap in positive cases was only 3.2%. Regarding immunohistopathological characteristics AE- and A45-positive BM were found significantly more frequent in tumors of higher nodal status (p=0.003 and p=0.026), and for AE also in hormone receptor negative (HR-) compared to HR+ patients (p=0.006). Positivity for AE and/or A45 staining in BM correlated with high nodal status and large tumor size (p=0.001 and p= 0.016, respectively). Survival analyses revealed shorter relapse-free survival for A45-positive patients (p=0.026). In node-positive patients, a significantly worse prognosis regarding overall and BC specific survival was observed for AE-positive (p=0.0245 and p=0.0125) and for AE- and/or A45-positive patients (p=0.035 and p=0.044, respectively). In node-negative patients, A45-positivity was correlated to a significantly shorter relapse-free survival (p=0.032). Immunocytochemical double staining of BM samples from 26 patients (M+ and M0) revealed subpopulations of DTC labeled with both Abs (in 8/26 cases) and other DTC exclusively stained for either A45 or AE (4/26).&#x2028; Discussion: Our results indicate that the two anti-cytokeratin Abs most frequently used for DTC detection in BM do not give identical results. They appear to identify at least partially different subpopulations of DTC in BC patients. This implies a possible advantage of the combined use of these Abs in future trials using DTC diagnostics.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5021.