Clin Cancer Res
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Multicenter Study
Phase I Study to Assess the Combination of Afatinib with Trastuzumab in Patients with Advanced or Metastatic HER2-Positive Breast Cancer.
The HER2 mAb, trastuzumab, is a standard therapy for patients with HER2-positive breast cancer before acquired resistance. Afatinib, an irreversible, oral, small-molecule ErbB family blocker, shows clinical activity in trastuzumab-refractory HER2-positive breast cancer. ⋯ The MTD of afatinib was 20 mg daily combined with the recommended weekly dose of trastuzumab, with 1 of 6 patients showing DLTs in the dose escalation. However, additional DLTs occurred in the dose-expansion phase meaning that this MTD cannot be recommended for phase II development without strict diarrhea management. There was no evidence suggesting relevant pharmacokinetic drug-drug interactions. Signs of clinical activity were seen in trastuzumab-resistant HER2-positive breast cancer, suggesting further investigation with optimal diarrhea management is warranted.