The Pathological Response to Anthracycline is Associated with Topoisomerase IIα Gene Amplification in the HER2 Breast Cancer Subset.

Background: HER2-positive breast cancer sensitivity to anthracyclines is enhanced when topoisomerase IIα (TOP2A) is co-amplified under both adjuvant and metastatic settings. However, the relationship between anthracycline sensitivity and TOP2A amplification in HER2-positive breast cancers in neoadjuvant settings is not known. Methods: The TOP2A gene status was examined by FISH in biopsies from 18 patients who received anthracycline and cyclophosphamide before surgery. Results: The TOP2A gene was amplified in 6/17 patients and was significantly associated with pathological response to the chemotherapy regimen. Conclusions: TOP2A amplification could predict anthracycline-sensitivity. Thus, the HER2/TOP2A co-amplified subtype may be effectively treated by anthracycline-containing regimens alone.