New agents for the management of resistant metastatic breast cancer.

INTRODUCTION: Metastatic breast cancer (MBC) is an incurable disease and treatment is directed towards symptom palliation and survival prolongation. Treatment selection in patients is based on tumor biology, age, comorbidities, performance status, tumor burden, and prior treatment history. Areas covered: This present review summarizes the recent treatment strategies in the management of MBC, highlighting regimens after first-line therapy. Topics discussed include new strategies for endocrine therapy, anti-HER2 therapy, and promising strategies for the management of triple negative breast cancer. Expert opinion: MBC is a heterogeneous entity and despite recent advances, there is significant room for improvement of treatment beyond first-line therapies. Combination regimens that can maximize clinical efficacy while minimizing toxicities are required. Current investigation approaches in advanced stages of clinical development include immunoconjugates, immune checkpoint blockade, novel cyclin-dependent-kinase inhibitors, and PARP inhibitors for MBC associated with germline BRCA mutations. We recommend that every patient with MBC should be evaluated for clinical trial options.