Recent Developments in HER2-Directed Therapy in Breast Cancer

Abstract

This review will discuss recent important trials for the treatment of HER2-positive breast cancer, emphasize ongoing areas of development, and highlight areas of unmet need. Advances for early-stage treatment have been driven by key clinical trials with pertuzumab, neratinib, and TDM-1. In the adjuvant setting, dual HER2 targeting with trastuzumab and pertuzumab has demonstrated modest improvement in disease-free survival. Neratinib also showed modest benefit in the extended adjuvant setting after prior trastuzumab. Finally, for patients who did not achieve pathologic complete response to neoadjuvant therapy, adjuvant therapy with TDM-1 showed significant disease-free survival benefit over trastuzumab. In advanced disease, neratinib appears to have activity beyond standard second line treatment. Promising compounds with early-phase data reviewed are tucatinib, margetuximab, and antibody-drug complexes. Immunotherapy in HER2-positive disease also has early-phase data. Endocrine therapy in combination with CDK4/6 inhibition and HER2-targeted therapy is in evaluation. Two areas of unmet need include CNS disease and disease treatment in the elderly population. In the wake of recent practice changing clinical trials, HER2-directed therapy is rapidly evolving. Future advances in therapy are anticipated with ongoing studies.