Targeted therapies for early breast cancer

Hormone-blocking therapy, also called endocrine therapy or anti-oestrogen therapy, works by depriving breast cancer cells of the hormones that they need to grow. It is used in the treatment of hormone receptor-positive breast cancer.

There are several different hormone-blocking therapy drugs available, including tamoxifen, anastrozole, letrozole and exemestane. Each works to block the effect of oestrogen, either by attaching to the oestrogen receptors on breast cancer cells so that oestrogen cannot enter the cells and help them grow, or by lowering the amount of oestrogen circulating in the body. 

Clinical trials are currently investigating several drugs that target and block pathways in cancer cells that are responsible for resistance to hormone-blocking therapies.

A targeted therapy called a CDK4/6 inhibitor (e.g. abemaciclib) may be given in combination with hormone-blocking therapy in high-risk early breast cancers to reduce the risk of recurrence.

Trastuzumab, pertuzumab (Perjeta) and trastuzumab emtansine (Kadcyla) are targeted therapies used in the treatment of early breast cancer that block the action of HER2 receptors on cells.

Breast cancers that are HER2-positive have excessive numbers of HER2 receptors on the surface of the cancer cells. These receptors allow growth factors to stimulate the growth of the cancer cells. Treatments that block the HER2 receptors prevent this growth stimulation, in turn, controlling the cancer.

There are also other targeted therapies available.

Immunotherapy is treatment that uses certain parts of a person’s immune system to fight diseases such as cancer. Different types of immunotherapy drugs are available, and they work in different ways.

Immunotherapy can work by stimulating the immune system to find cancer cells or by adding components to a person’s immune system such as man-made immune system proteins.

Keytruda (pembrolizumab) is one of the first immunotherapies that is shown to be effective for early-stage triple negative breast cancer.

Talk to your medical oncologist for more information.