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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: To evaluate the efficacy and safety of docetaxel, cisplatin, and trastuzumab as primary systemic therapy for human epidermal growth factor receptor 2 (HER2) -positive, locally advanced breast cancer (LABC)., Patients and Methods: Forty-eight patients with immunohistochemistry-confirmed HER2-positive LABC or inflammatory breast cancer received 12 weeks of docetaxel, cisplatin, and trastuzumab with filgrastim, followed by surgery, adjuvant doxorubicin and cyclophosphamide, and locoregional radiotherapy with or without tamoxifen. The primary end point was pathologic complete response (pCR) in breast., Results: Baseline mean tumor size was 9.2 cm (range, 4 to 32 cm). pCR occurred in breast in 11 patients (23%; 95% CI, 12% to 37%) and breast and axilla in eight patients (17%; 95% CI, 8% to 30%). pCR rates in breast (HER2 positive, seven of 30 patients, 23% v HER2 negative, four of 18 patients, 22%; P > .05) and breast and axilla (four of 30 patients, 13% v four of 18 patients, 22%, respectively; P > .05) were similar regardless of HER2 status by fluorescence in situ hybridization (FISH). At a median follow-up time of 43 months, 4-year progression-free survival (PFS) rate was 81% (95% CI, 64% to 90%); overall survival (OS) rate was 86% (95% CI, 71% to 94%). In patients with pCR in breast and axilla, PFS and OS rates were 100% (95% CI, inestimable). In patients without pCR, PFS rate was 76% (95% CI, 57% to 88%; P = .15, log-rank test), and OS rate was 83% (95% CI, 66% to 92%; P = .21). Survival rates were similar regardless of FISH status. There were only two grade 4 adverse events., Conclusion: Twelve weeks of docetaxel, cisplatin, and trastuzumab is clinically active and leads to excellent survival in patients with large, HER2-positive tumors.

Purpose: To compare the efficacy of fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) in detecting the HER-2/neu alteration in human breast cancer., Patients and Methods: Unselected stage I, II, and III breast cancer patients (N = 900) were tested for HER-2/neu gene amplification by FISH in paraffin-embedded, formalin-fixed archival material. Of these samples, 856 were tested for HER-2/neu overexpression by non-antigen-retrieval IHC with the polyclonal antibody R60, the sensitivity and specificity of which was preliminarily compared with the United States Food and Drug Administration-approved HercepTest (Dako Corp, Carpinteria, CA). Patient survival was analyzed in relation to the presence of the HER-2/neu alteration as determined by these two methodologies., Results: A total of 189 (21%) of 900 patients were positive by FISH and 147 (17.2%) of 856 were positive by IHC. This discrepancy is consistent with expected loss of IHC sensitivity associated with tissue fixation/embedding. The HercepTest did not improve sensitivity and introduced false positives. Comparison of R60-based IHC with FISH demonstrates that patient survival is associated progressively to gene amplification level as determined by FISH, whereas for IHC an association is found only in the highest (3+) immunostaining group. Among FISH-negative tumors, 45 (6.6%) of 678 were IHC-positive, with a survival probability similar to that of FISH-negative/IHC-negative cases; FISH-positive/IHC-negative patients have a survival probability similar to that of FISH-positive/IHC-positive cases., Conclusion: IHC does not consistently discriminate patients likely to have a poor prognosis, whereas FISH provides superior prognostic information in segregating high-risk from lower-risk beast cancers. HER-2/neu protein overexpression in the absence of gene amplification occurs infrequently in breast cancer, in which case, patient outcome is similar to that of patients without the alteration.