Drug target strategies in breast cancer treatment: recent developments.

Breast cancer (BC) is the leading cause of death among women all over the world. Estrogen receptor (ER) based therapy is one of the major approaches to target BC and is associated with various problems such as primary as well as secondary resistance. ER signaling is a complex pathway as many factors are involved; including several types of ERs and their associated co-regulators. Increasing understanding of ER signals results in new approaches targeting towards BCs. In this context, ER co-regulators have been explored and many modulators of ER co-regulators have been found out. EGFR and mTOR pathways also have significant impact on BC endocrine therapy because of the complex crosstalk mechanism which is responsible for primary and secondary resistance. Triple negative breast cancer (TNBC) is majorly associated with BRCA mutations. Currently there is no approved targeted therapy available in such form of cancer. Although PARP inhibitors seem to be suitable candidates for it. The present review is focused on the current scenario of ER, EGFR, as well as mTOR signaling target therapy. We have also discussed the current status of PARP inhibitors in BC chemotherapy.