Strategies for managing endocrine resistance in advanced hormone receptor-positive and HER2-negative breast cancer
Abstract
Hormone therapy is a fundamental therapeutic modality in advanced hormone receptor-positive (HR) and HER2-negative breastcancer. Its use is clearly superior to chemotherapy.
It is known that, sooner or later, resistance to hormone therapy will occur.Everolimus (Afinitor(R)) - an mTOR inhibitor used in the second line of treatment in combination with exemestane - was the firstdrug to have broken and delayed hormone resistance. Other drugs to have reached a similar goal by a different mechanisminclude palbociclib, ribociclib, and abemaciclib - cyclin-dependent kinase 4/6 inhibitors (CDK 4/6) that are very effective in thefirst line in combination with non-steroidal aromatase inhibitors (particularly with letrozole).
The same agents in combinationwith fulvestrant have shown (so far, the results for palbociclib and, more recently, for abemaciclib have become available) highefficacy in the second treatment line. Currently, a number of studies are under way aimed at delaying hormone resistance.
Someof the regimens presented in this paper will likely become in the near future the standard of hormone therapy for advancedHR-positive and HER2-negative breast cancer.