Topoisomerase IIα as a Marker Predicting the Efficacy of Anthracyclines in Breast Cancer: Are We at the End of the Beginning?

Topoisomerase IIα 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

Purpose

Amplification of the HER-2/neu and topoisomerase IIα (TOP2A) genes has been linked to the effects of anthracyclines. Their role in predicting the outcome of anthracycline-based adjuvant chemotherapy for breast cancer patients has remained controversial.

Patients and Methods

The present substudy of the Scandinavian Breast Group trial 9401, in which an epirubicin-based regimen (nine courses of tailored and dose-escalated fluorouracil, epirubicin, and cyclophosphamide [FEC]) was compared with three or four courses of standard FEC followed by bone marrow–supported high-dose chemotherapy (cyclophosphamide, thiotepa, and carboplatin), included high-risk breast cancer patients (with eight or more positive axillary lymph nodes or at least five nodes with additional poor prognostic indicators). Amplification of HER-2/neu was determined retrospectively in paraffin-embedded tumor tissue sections by chromogenic in situ hybridization. TOP2A was tested only in HER-2/neu–amplified tumors.

Results

HER-2/neu amplification alone, which was present in 32.7% of the tumors, was a strong prognostic factor for short relapse-free (P = .0034) and overall survival (P = .0008) but showed no direct association with treatment assignment. TOP2A coamplification, which was present in 37% of HER-2/neu–amplified tumors, was associated with better relapse-free survival in patients treated with tailored and dose-escalated FEC (hazard ratio [HR] = 0.45; P = .049). A statistical multivariate Cox's regression analysis confirmed the predictive significance of TOP2A coamplification (HR = 0.30; P = .020) in HER-2/neu–amplified tumors. There was no such association in patients with HER-2/neu–amplified tumors without TOP2A gene amplification.

Conclusion

Coamplification of HER-2/neu and TOP2A may define a subgroup of high-risk breast cancer patients who benefit from individually tailored and dose-escalated adjuvant anthracyclines.

Changes of Topoisomerase IIα Expression in Breast Tumors after Neoadjuvant Chemotherapy Predicts Relapse-Free Survival

PURPOSE

To assess the value of changes in the expression of topoisomerase IIalpha (TopoII) and the proto-oncogene erbB-2 (HER-2) as predictors of relapse-free survival in women with operable breast cancer treated with anthracycline-based neoadjuvant chemotherapy.

PATIENTS AND METHODS

Seventy-seven patients with primary breast cancer who had undergone neoadjuvant anthracycline-based chemotherapy were included in the present study. TopoII and HER-2 were measured by immunohistochemistry in prechemotherapy and postchemotherapy (at the time of surgery) tumor specimens, and the value of their changes as predictors of relapse-free survival were evaluated by Kaplan-Meier and Cox proportional hazard regression analyses.

RESULTS

Neoadjuvant chemotherapy resulted in a significant reduction in the percentage of cells expressing TopoII (P < 0.0001). No significant change was observed for HER-2. TopoII and HER-2 expression before chemotherapy predicted tumor response to treatment. Changes in TopoII expression after chemotherapy were strongly associated with a poor relapse-free survival (P < 0.0001) in a Cox multivariate analysis adjusted for other clinicopathologic prognostic factors.

CONCLUSION

Changes in TopoII expression after anthracycline-based neoadjuvant chemotherapy is an independent predictor of a poor relapse-free survival in patients with breast cancer. Tumor cells displaying an increased TopoII expression after treatment may be responsible for relapses, and may, therefore, define a group of patients with anthracycline-resistant breast cancer.

Predictive Markers in Breast and Other Cancers: A Review

Background: Unpredictable efficacy and toxicity are hallmarks of most anticancer therapies. Predictive markers are factors that are associated with response or resistance to a particular therapy.

Methods: The English literature relating to predictive markers in oncology was reviewed. Particular attention was paid to metaanalyses, systematic reviews, prospective trials, and guidelines issued by expert panels.

Results: The prototype predictive tests in oncology are the estrogen receptor (ER) and progesterone receptor (PR), which are used to select patients with breast cancer likely to respond to hormone therapy. A more recently introduced predictive marker is HER-2 for selecting patients with advanced breast cancer for treatment with the therapeutic antibody trastuzumab (Herceptin). In adjuvant breast cancer, overproduction of HER-2 may also indicate an enhanced sensitivity to high-dose anthracycline-based regimens. On the other hand, in both early and advanced breast cancer, high concentrations of HER-2 appear to correlate with a lower probability of response to hormone therapy. Although many different anticancer drugs appear to mediate tumor regression by inducing apoptosis, there is currently no consistent evidence that any of the molecules implicated in this process can be used as predictive markers.

Conclusions: Currently, the only recommended predictive markers in oncology are ER and PR for selecting endocrine-sensitive breast cancers and HER-2 for identifying breast cancer patients with metastatic disease who may benefit from trastuzumab. For malignancies other than breast cancers, validated predictive markers do not exist at present.

Facts and Controversies in Systemic Treatment of Metastatic Breast Cancer

The management of metastatic breast cancer remains an important and controversial issue. The systemic therapy, comprising endocrine, cytotoxic and biological agents, can be administered sequentially or in combination. Few drugs or combinations provide a significant improvement in survival and, therefore, in the great majority of cases, treatment is given with a palliative intent. With the exception of first-line therapy, for which general agreement exists, currently there is no consensual standard of care. This review will summarize the current knowledge and outline the controversial issues related to systemic therapy of metastatic breast cancer, with emphasis on treatment tailoring. The potential role of tumor molecular profile(s) in the selection of patients that could benefit the most from each strategy/agent will be discussed.