Background: Ixabepilone is a member of the epothilone class of antineoplastic agents with activity against taxane-resistant tumors, and low susceptibility to common mechanisms of tumor resistance. This study evaluated ixabepilone in lieu of a taxane in combination with carboplatin and trastuzumab as neoadjuvant treatment for operable HER2-positive breast cancer.
Patients and methods: Patients ≥ 18 years of age with histologically-confirmed HER2-positive adenocarcinoma of the breast (clinical T1-T3, N0-N2, M0), normal left ventricular ejection fraction, and adequate organ function received trastuzumab 6 mg/kg intravenous (I.V.) (with 8 mg/kg loading dose cycle 1), ixabepilone 40 mg/m(2) I.V., and carboplatin area under the curve = 6.0 I.V. on day 1 of each 21-day cycle. Prophylactic growth factor support was permitted. After completing 6 cycles, patients underwent definitive surgery. After surgery, patients continued trastuzumab every 3 weeks for a total of 1 year. Locoregional radiation therapy and endocrine therapy was administered per institutional guidelines. The primary end point was the rate of pCR.
Results: Fifty-eight eligible women (median tumor size, 3.0 cm; clinical axillary lymph node involvement, 67%) initiated treatment between April 2009 and February 2010. Fifty-two patients (90%) underwent surgery, and pCR was observed in 27 patients (52%). Grade 3/4 neutropenia was the most common toxicity, occurring in 69% of patients and complicated by fever in 4 patients.
Conclusion: The combination of ixabepilone, carboplatin, and trastuzumab was feasible and active as a neoadjuvant regimen. Although the pCR rate of 52% falls within the range reported with other taxane/trastuzumab-based regimens, the greater incidence of severe neutropenia is a disadvantage for this regimen.
Keywords: Biologic; Chemotherapy; Monoclonal antibody.
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