Triple negative breast cancer (TNBC) is a subtype of breast cancer that lacks estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression. Targeted therapy for TNBC is challenging because these receptors, which are often targeted in other breast cancer subtypes, are not present.

There are some targeted therapies that have shown promise in treating TNBC, including:

1. PARP inhibitors: These drugs block a specific enzyme called poly ADP-ribose polymerase (PARP), which is involved in DNA repair. TNBC cells are often deficient in DNA repair mechanisms, making them more susceptible to PARP inhibitors. Olaparib and talazoparib are examples of PARP inhibitors approved for the treatment of TNBC.

2. Immune checkpoint inhibitor: These drugs activate the immune system to attack cancer cells. Pembrolizumab and atezolizumab are examples of immune checkpoint inhibitors that have been approved for the treatment of TNBC in combination with chemotherapy

3. Antibody-drug conjugates (ADCs): ADCs are a type of targeted therapy that combines an antibody that targets a specific protein on cancer cells with a chemotherapy drug. Sacituzumab govitecan is an ADC that targets Trop-2, a protein overexpressed in TNBC.

4. VEGF inhibitors: These drugs target vascular endothelial growth factor (VEGF), a protein that stimulates the growth of blood vessels. Bevacizumab is a VEGF inhibitor that has shown some benefit in combination with chemotherapy for the treatment of TNBC.