Abstract OT1-1-17: LUX-Breast 2: Phase II, open-label study of oral afatinib in HER2-overexpressing metastatic breast cancer (MBC) patients (pts) who progressed on prior trastuzumab and/or lapatinib*

Therapeutic Considerations in Treating HER2-Positive Metastatic Breast Cancer

Despite advances in detection and treatment, metastatic breast cancer (MBC) remains the second highest cause of cancer-related death for women in the United States. Human epidermal growth factor receptor-2 (HER2) is amplified in 25-30% of breast cancers and is associated with aggressive disease and, historically, with poorer outcomes. The advent of trastuzumab, a monoclonal antibody to HER2, revolutionized the management of HER2-positive breast cancer (BC) in the metastatic and adjuvant settings. However, relapse despite adjuvant trastuzumab and resistance to trastuzumab in the metastatic setting remain substantial clinical problems for many patients with HER2-positive BC. As such, analyzing the mechanisms of trastuzumab resistance and developing new therapy to overcome trastuzumab resistance are research priorities. There has been progress, with the approval of three additional HER2-targeted agents in the last six years: lapatinib, pertuzumab, and ado-trastuzumab emtansine (T-DM1). Other HER2-targeted therapies, including neratinib and afatinib, are in clinical development, and trials of novel agents such as heat shock protein-90 (HSP90) inhibitors, phosphatidylinositol-3-kinase (PI3K) inhibitors, and HER2-targeted vaccines are ongoing. In addition to developing new therapy, research is addressing several unique challenges in the management of HER2-positive MBC. In this article, we discuss advances in the treatment of HER2-positive MBC, with a focus on novel HER2-targeted therapy and HER2-targeted agents recently approved by the United States Food and Drug Administration (FDA). Additionally, we also address the management of brain metastases (BM) and hormone receptor (HR) - positive, HER2-positive MBC.

Afatinib: first global approval

Afatinib, an irreversible inhibitor of the ErbB family of tyrosine kinases, is under development with Boehringer Ingelheim for the once-daily, oral treatment of cancer. Afatinib downregulates ErbB signalling by covalently binding to epidermal growth factor receptor (EGFR), human epidermal growth factor receptor (HER) 2 and HER4, irreversibly inhibiting tyrosine kinase autophosphorylation. It also inhibits transphosphorylation of HER3. Oral afatinib (Gilotrif™) has been approved in the US for the first-line treatment of patients with metastatic non-small-cell lung cancer (NSCLC) who have tumours with EGFR exon 19 deletions or exon 21 (L858R) substitution mutations as detected by a US FDA-approved test. Afatinib has also been approved in Taiwan for the first-line treatment of patients with EGFR mutation-positive NSCLC. In addition, the European Medicines Agency's Committee for Medicinal Products for Human Use has recommended the approval of afatinib (Giotrif®) for the treatment of patients with locally advanced or metastatic NSCLC with activating EGFR mutations who are EGFR tyrosine kinase inhibitor naïve. Afatinib is also under regulatory review in Canada, Japan and other Asian countries. This article summarizes the milestones in the development of afatinib, leading to this first approval in patients with metastatic NSCLC.