Target Therapy In Breast Cancer

What are targeted cancer therapies Targeted cancer therapies are drugs or other substances thatblock the growth and spread of cancer by interfering with specific molecules ( molecular targets )that are involved in the growth, progression, and spread of cancer. Breast cancer is aheterogeneous group of diseases that are clinically subdivided as hormone receptor–positive,HER2+, and triple-negative breast cancer, to guide therapeutic interventions. Agents that targetestrogen receptor (ER) and HER2 are among the most successful cancer therapeutics. About 2 out of3 breast cancers are hormone receptor-positive (ER-positive or PR-positive). For women with thesecancers, treatment with hormone therapy is often helpful. Certain targeted therapy drugs canmake hormone therapy even more effective, although these targeted drugs can also add to the sideeffects. A number of hormonal therapeutic agents have been approved for the treatment of ER+disease, including tamoxifen, aromatase inhibitors (AIs), and fulvestrant. For about 1 in 5 womenwith breast cancer, the cancer cells have too much of a growth-promoting protein known asHER2/neu (or just HER2) on their surface. These cancers, known as HER2-positive breast cancers,tend to grow and spread more aggressively, but a number of drugs have been developed that targetthis protein. For HER2+ breast cancer, a growing number of HER2-targeted agents have becomeavailable, including trastuzumab, lapatinib, pertuzumab, and Ado-trastuzumab emtansine(Kadcyla, also known as TDM-1). However, these agents are ineffective for triple-negative breastcancers (TNBC). In addition, de novo or acquired resistance to these agents is common, despite thepresence of ER and HER2. Novel therapeutic targets are being developed as treatment strategies forTNBC and resistant ER and HER2+ diseases.