Abstract
Hormone-dependent breast cancer is the first example of cancer treated by targeted therapy for more than 30 years. Blocking estrogen pathway was the first therapeutical strategy for this subtype of breast cancer, and remains the principle of current standard treatment. Despite the efficacy of drugs used in endocrine therapy, hormone resistance is a major problem for the management of patients with hormone-dependent breast cancer. In this review, we will discuss the development of strategies targeting the PI3K/Akt/mTOR pathway, CDK4/6 (Cyclin Dependent Kinase 4/6) and FGFR (Fibroblast Growth Factor Receptor) in hormone-dependent metastatic breast cancer (ER+). Recent results of clinical trials showed that combination of endocrine therapy with such pharmacological inhibitors is a promising strategy to overcome endocrine resistance. Mutated forms and isoforms of ERα have been recently discovered and its targeting could represent an therapeutic alternative. Future progress will focus on the identification of new compounds and combinations with other targeted therapies to improve the efficacy of such inhibitors in clinical practice.