Targeted therapy for breast cancer

Targeted therapy drugs attack specific features of cancer cells to stop the cancer growing and spreading.

Learn more about:

• What drugs are available?
• How trastuzumab works
• Side effects of trastuzumab
• PARP inhibitors
• Video: What are immunotherapy and targeted therapy?

What drugs are available?

The drugs that are currently available do not work for all types of breast cancer. They are mostly useful for HER2 positive breast cancers. The drug abemaciclib is used for both HER2+ and HER2– breast cancers. For early or locally advanced breast cancer, the most common targeted therapy drug used is trastuzumab.

How trastuzumab works

Your treatment team may refer to trastuzumab by a brand name, such as Herzuma, Kanjinti or Ogivri. It is also known by the brand name Herceptin, though this version is now rarely used in Australia. Trastuzumab works by attaching itself to HER2+ breast cancer cells, destroying the cells or reducing their ability to divide and grow. Trastuzumab also encourages the body’s own immune cells to help find and destroy the cancer cells.

Trastuzumab is used in combination with chemotherapy. It has been shown to increase the effect of chemotherapy drugs on early breast cancer. Most people have trastuzumab via a drip into a vein (infusion), but some people have it as an injection under the skin.

The first infusion takes about 90 minutes. This is called the loading dose. The following infusions take 30–60 minutes each. You will usually have a dose every three weeks, for up to 12 months. The first four doses are given while you are having chemotherapy treatment.

Side effects of trastuzumab

Your medical team will monitor you for side effects. These are usually caused by the chemotherapy. This means that once chemotherapy finishes and you are continuing with trastuzumab only, most side effects ease. For example, hair grows back, there is no nausea or vomiting, and you no longer need regular blood tests.

Although side effects from trastuzumab itself are uncommon, they can include headache, fever and diarrhoea. In some people, trastuzumab can affect how the heart works, so you will have tests to check your heart function before and during treatment.

PARP inhibitors

There are a number of new drugs for people who have inherited a BRCA mutation, or whose cancer has developed BRCA mutations. These are called PARP inhibitors. Ask your doctor whether these drugs may be appropriate for you.

→ READ MORE: Managing side effects of breast cancer

Video: What are immunotherapy and targeted therapy?

Watch this short video to learn more about targeted and immunotherapy