Adjuvant Therapy with Trastuzumab for HER-2/neu-Positive Breast Cancer

Abstract

Learning Objectives: After completing this course, the reader will be able to: Select appropriate adjuvant therapy for patients with HER-2/neu-positive breast cancer.Monitor trastuzumab therapy for cardiac toxicity.Discuss the controversies that remain in the treatment of HER-2/neu-positive breast cancer. Access and take the CME test online and receive 1 AMA PRA category 1 creditTM at CME.TheOncologist.com Breast cancer is the most common cancer in women in the U.S. and western Europe. Amplification of the her-2/neu gene occurs in approximately 25% of invasive ductal carcinomas of the breast. In experimental models, transfection of the her-2/neu gene results in transformation of mammary epithelial cells. In human breast cancer, amplification of the her-2/neu gene results in protein over expression and poor prognosis. Patients whose tumors have her-2/neu gene amplification have a shorter disease-free survival time than patients whose tumors exhibit a normal her-2/neu gene copy number. her-2/ neu gene amplification identifies a biologically unique subset of aggressive breast tumors that are sensitive to growth inhibition and apoptosis induced by anti-HER-2/neu-targeted therapies. The first HER-2/neu-targeted approach to reach the clinic was trastuzumab, a humanized monoclonal antibody directed against the extracellular domain of the HER-2/neu protein. Trastuzumab therapy prolongs the survival of patients with metastatic HER-2/neu-overexpressing breast cancer when combined with chemotherapy and has recently been demonstrated to lead to dramatic improvements in disease-free survival when used in the adjuvant therapy setting in combination with or following chemotherapy. However, potential cardiotoxicity requires careful patient selection. Here, we review the recently completed clinical trials of adjuvant trastuzumab in the adjuvant setting. HER-2/neu testing, patient selection, cardiotoxicity, duration of therapy, and directions for future research are discussed.