TOP2A Status in Chemotherapy-Treated Breast Cancer Patients Using FISH in Cytokertatin-Positve Cells
William E Pierceall, Jiri Bartek, Jirina Bartkova, Heli Nevanlinna, Carl Blomqvist. On-Q-ity, Inc, Waltham, MA; Danish Cancer Society, Copenhagen, Denmark; Helsinki University Central Hospital, Helsinki, Finland
Background: Tumor biomarker analysis increasingly provides information for predicting outcomes with specific chemotherapeutic regimens (personalized medicine). TOP2A is a DNA helicase that is targeted by anthracyclines, cytotoxic therapeutics commonly used as both adjuvant and palliative treatment of breast cancer. Several large studies have shown that TOP2A copy number variations (CNV) are predictive to response and outcome after anthracycline based chemotherapy.
Design: We have developed an approach for analyzing FFPE breast tumors on tissue microarrays with TOP2A fluorescence in situ hybridization (FISH) coupled with cytokeratin immunofluorescence (IF) to specifically identify tumor cells. Stained tissue from breast cancer patient specimens was imaged and analyzed using Metafer/Metacyte (Metasystems) by a customized image classifier and high throughput analysis.
Results: TOP2A:CEN17 ratios ≥ 2.0 (amplified) and ≤ 0.8 (deleted) were observed for 10.0% and 6.1% of the patients, respectively, and established as cut-offs for statistical tests. Patient subgroup outcomes for adjuvant chemotherapy (CEF, CMF, No Chemotherapy [CT]) were evaluated. No statistically significant differences were observed in clinical endpoints for TOP2A status in anthracycline-treated patients. However, patients with TOP2A aberrations receiving methotrexate-based therapy exhibited significant decrease in 5yr Distant Disease-Free Survival (5yrDDFS) and Breast Cancer-Specific Overall Survival (BCSOS), especially for the group with TOP2A deletions (DFS HR=5.31, p=0.001 and BCSOS HR=6.45, p<0.001). No significant differences were seen in the No CT treatment group. Topo2A protein levels by immunohistochemistry were assessed with no correlative statistical relevance to IF/FISH-based prognosis for CEF or CMF groups. Interestingly, aberrant (under)expressing No CT patients exhibited better 5yrDDFS [HR=0.39, p=0.004) and trended toward more favorable BCSOS (HR=0.61, p=0.11).
Conclusions: Our results indicate a strategy by which targeted scoring of FISH signals to cytokeratin-positive staining tumor cells may provide a tool for added precision and efficiency in the evaluation of the TOP2A from tumor tissue.
Monday, March 19, 2012 1:00 PM
Poster Session II # 58, Monday Afternoon