HER2 targeted therapy drugs

When the type of breast cancer is HER2-positive, this means there are lots of HER2 receptors on the surface of your cancer cells. These receptors cause the cancer cells to grow and divide more quickly.

HER2 therapies work by blocking the HER2 receptors to stop the cells from dividing and growing. They are generally most useful for HER2-positive breast cancers, not HER2-negative.

Trastuzumab (Herceptin)

Most people whose breast cancers are HER2-positive are offered trastuzumab.

Trastuzumab is given as an injection under the skin or as an intravenous (IV) infusion.

If you have early breast cancer:

Herceptin is usually given with chemotherapy, before or after surgery.

Herceptin before surgery: given for between 12 and 18 weeks.

Herceptin after surgery: often given with chemotherapy for 3 months, then continued alone for a total of 12 months.

If you have metastatic breast cancer:

You are usually given Herceptin with chemotherapy and another HER2 targeted treatment, pertuzumab (Perjeta). You may take it for an unlimited time, until it is no longer working, or causes you too many side effects.

Availability: on the PBS.

Other trastuzumab medicines available through the PBS include:

• Herzuma (also known as Ritemvia, Rituzena and Tuxella)
• Ogivri
• Ontruzant
• Kanjinti
• Trazimera.

Your medical oncologist will talk to you about what treatment is most suitable for you.

Side effects

Everyone reacts differently to treatment and some people may have more side effects than others. Find out about Side effects of trastuzumab and when to contact your treating team.

Pertuzumab (Perjeta)

Pertuzumab (Perjeta) is another HER2 targeted therapy commonly used for the treatment of HER2 positive breast cancer.

If you have early breast cancer:

It is often given with trastuzumab and chemotherapy, for up to 6 cycles, before surgery (neoadjuvant). Sometimes it can be given after surgery with trastuzumab for 12 months in total.

If you have metastatic breast cancer:

It is given with trastuzumab and chemotherapy (for at least a few weeks to months).

You can continue pertuzumab indefinitely in combination with trastuzuamb, as long as it is working to control the cancer, and not causing too many side effects.

Availability: not on the PBS (Mar 2025)

Side effects

Side effects may include diarrhoea and heart problems.

Trastuzumab emtansine/TDM1 (Kadcyla)

TDM1 is trastuzumab with a very small dose of chemotherapy (emtansine) attached to it. This type of drug is called an antibody drug conjugate (ADC). It is essentially a targeted chemotherapy.

It is given to patients with HER2 positive early and metastatic breast cancer.

If you have early breast cancer:

Your doctor may recommend TDM1 if:

• you have had neoadjuvant chemo AND
• cancer cells were detected in the breast tissue or lymph nodes that the surgeon removed (residual disease).

TDM1 is given intravenously every 3 weeks for 14 cycles after surgery. It can be given throughout radiotherapy, although some radiation doctors prefer you to start after you finish radiotherapy.

If you have metastatic breast cancer:

TDM1 is given intravenously every 3 weeks, usually after Herceptin and Perjeta have stopped working, or Enhertu has stopped working.

You take this indefinitely, until it stops working, or you have too many side effects.

Availability: on the PBS

Side effects

TDM1 has fewer side effects than other chemotherapy, but generally a few more side effects than trastuzumab alone. It can cause rare but serious side effects. 

Neratinib (Nerlynx)

Neratinib (Nerlynx) is sometimes offered after you finish trastuzumab. It is for people with HER2-positive early breast cancer. Neratinib blocks the cancer cells' ability to receive growth signals and therefore inhibits cancer cell growth and multiplication.

Neratinib is a tablet and is given for 12 months. You must start it within a year of finishing trastuzumab.

Availability: not on the PBS (Mar 2025).

You may be able to access Neratinib through the pharmaceutical company’s access program. Ask your medical oncologist if you:

• are being treated with trastuzumab
• finished trastuzumab within the last 12 months.

Side effects

Diarrhoea is common, especially in the first 2 months, and can be severe. Your treating team can help you manage this side effect.