Targeted therapy destroys or slows down the growth of breast cancer cells by attaching to and inhibiting specific proteins that help cancer cells grow, spread, and live longer. These proteins are usually located on the surface or inside cancer cells. This means that targeted drugs attack breast cancer cells specifically, without harming normal cells.

Like chemotherapy, targeted therapy is introduced into the bloodstream and spreads to almost all areas of the body. This makes them useful for treating cancers that have spread beyond the breast. Targeted drugs sometimes work in cases where chemotherapy drugs do not, and some targeted drugs can help other types of treatment work better.

It is important to note, however, that in TNBC, the cancer cells do not have some of the proteins that targeted drugs are designed to attach to; hence, many of these targeted therapies do not work for TNBC.