Therapeutic strategies for metastatic triple negative breast cancer

Abstract

Although triple negative breast cancer (TNBC) is defined by the lack of expression of hormone receptors and HER2, from now on, we should not treat this subtype as “disease characterized by lack” but “the disease characterized by gain”. The third or more targets other than hormone receptors and HER2 have been suggested and many drugs including those designed to affect such targets have been studied in patients with TNBC. Platinum-based regimens have been used as a standard of care in TNBC, and immune checkpoint inhibitors have been investigated mostly in TNBC. PARP inhibitors are promising in patients with BRCA1/2 mutations or homologous recombination deficiency, anti-epidermal growth factor receptor (EGFR) agents and anti-androgen receptor (AR) agents have been investigated in patients with EGFR and AR expression, respectively, and other targeted agents are also under development. Several subtypes have been identified among TNBC and found to differentially respond to specific drugs. Based on these circumstances, we must efficiently develop appropriate classification and treatment in TNBC. In this symposium, I will discuss recent or ongoing clinical trials including WJOG9917B (NEWBEAT), a phase II trial of first-line treatment with paclitaxel, bevacizumab and nivolumab in patients with HER2-negative metastatic breast cancer.