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Purpose: Approximately 35% of HER2-amplified breast cancers have coamplification of the topoisomerase II-alpha (TOP2A) gene encoding an enzyme that is a major target of anthracyclines. This study was designed to evaluate whether TOP2A gene alterations may predict incremental responsiveness to anthracyclines in some breast cancers., Methods: A total of 4,943 breast cancers were analyzed for alterations in TOP2A and HER2. Primary tumor tissues from patients with metastatic breast cancer treated in a trial of chemotherapy plus/minus trastuzumab were studied for amplification/deletion of TOP2A and HER2 as a test set followed by evaluation of malignancies from two separate, large trials for changes in these same genes as a validation set. Association between these alterations and clinical outcomes was determined., Results: Test set cases containing HER2 amplification treated with doxorubicin and cyclophosphamide (AC) plus trastuzumab, demonstrated longer progression-free survival compared to those treated with AC alone (P = .0002). However, patients treated with AC alone whose tumors contain HER2/TOP2A coamplification experienced a similar improvement in survival (P = .004). Conversely, for patients treated with paclitaxel, HER2/TOP2A coamplification was not associated with improved outcomes. These observations were confirmed in a larger validation set, where HER2/TOP2A coamplification was again associated with longer survival when only anthracycline-containing chemotherapy was used for treatment compared with outcome in HER2-positive cancers lacking TOP2A coamplification., Conclusion: In a study involving nearly 5,000 breast malignancies, both test set and validation set demonstrate that TOP2A coamplification, not HER2 amplification, is the clinically useful predictive marker of an incremental response to anthracycline-based chemotherapy. Absence of HER2/TOP2A coamplification may indicate a more restricted efficacy advantage for breast cancers than previously thought.

Purpose: Docetaxel-trastuzumab (TH) is effective therapy for HER2-amplified metastatic breast cancer (MBC). Preclinical findings of synergy between docetaxel, carboplatin, and trastuzumab (TCH) prompted a phase III randomized trial comparing TCH with TH in patients with HER2-amplified MBC., Patients and Methods: Two hundred sixty-three patients were randomly assigned to receive eight 3-week cycles of TH (trastuzumab plus docetaxel 100 mg/m(2)) or TCH (trastuzumab plus carboplatin at area under the serum concentration-time curve 6 and docetaxel 75 mg/m(2)). Trastuzumab was given at 4 mg/kg loading dose followed by a 2 mg/kg dose once per week during chemotherapy, and then 6 mg/kg once every 3 weeks until progression., Results: Patient characteristics were balanced between groups. There was no significant difference between TH and TCH in terms of the primary end point, time to progression (medians of 11.1 and 10.4 months, respectively; hazard ratio, 0.914; 95% CI, 0.694 to 1.203; P = .57), response rate (72% for both groups), or overall survival (medians of 37.1 and 37.4 months, respectively; P = .99). Rates of grades 3 or 4 adverse effects for TH and TCH, respectively, were neutropenic-related complications, 29% and 23%; thrombocytopenia, 2% and 15%; anemia, 5% and 11%; sensory neuropathy, 3% and 0.8%; fatigue, 5% and 12%; peripheral edema, 3.8% and 1.5%; and diarrhea, 2% and 10%. Two patients given TCH died of sepsis, and one patient given TH experienced sudden cardiac death. Absolute left ventricular ejection fraction decline > 15% was seen in 5.5% of patients on the TH arm and 6.7% of patients on the TCH arm., Conclusion: Adding carboplatin did not enhance TH antitumor activity.TH (docetaxel, 100 mg/m(2)) and TCH (docetaxel, 75 mg/m(2)) demonstrated efficacy with acceptable toxicity in women with HER2-amplified MBC.