Last updated: 12 March 2026
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HER2-targeted agents
For early or locally advanced HER2+ breast cancer, the most common targeted therapy drug used is trastuzumab. Your treatment team may refer to trastuzumab by a brand name (e.g. Herzuma, Kanjinti or Ogivri). It is also known as Herceptin, although 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. It also encourages the body’s own immune cells to help find and destroy cancer cells. Usually used in combination with chemotherapy drugs for early breast cancer, trastuzumab can increase the effect of the chemotherapy.
Trastuzumab can be given through a drip into a vein (infusion) or as an injection under the skin. The first infusion takes about 90 minutes (called the loading dose). The following infusions each take 30–60 minutes. You will usually have a dose every 3 weeks, for up to 12 months. The first 4–6 doses are given while you are having chemotherapy treatment.
Side effects
Side effects are usually caused by the chemotherapy drugs, and often ease once chemotherapy finishes and you are having trastuzumab only. Side effects from trastuzumab are uncommon, but can include headache, fever and diarrhoea. In some cases, trastuzumab can affect how the heart works, so you will have tests to check your heart function before and during treatment.
CDK inhibitors
Abemaciclib is a type of cyclin-dependent kinase (CDK) inhibitor. It is used with hormone therapy. Abemaciclib may be used after surgery and chemotherapy for larger, high-risk ER+, HER2– breast cancers, for cancers involving several lymph nodes, or cancers at high risk of returning. Another drug (ribociclib) may soon become more widely available.
Side effects
Nausea or diarrhoea may occur, but this can be managed. Your blood count may be affected, so regular blood tests are needed.
PARP inhibitors
There are several new drugs for people who have inherited a BRCA mutation, or whose cancer has developed BRCA mutations. These are called poly (ADP-ribose) polymerase (PARP) inhibitors and include the drug olaparib. Ask your doctor if this may be suitable for you.
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Sources and references
This information has been developed by Cancer Council NSW on behalf of all other state and territory Cancer Councils and Cancer Council Australia as part of a National Cancer Information Subcommittee initiative. We thank the reviewers of this content: Dr Diana Adams, Medical Oncologist, Macarthur Cancer Therapy Centre, NSW; Prof Bruce Mann, Specialist Breast Surgeon and Director, Breast Cancer Services, The Royal Melbourne and The Royal Women’s Hospitals, VIC; Dr Shagun Aggarwal, Specialist Plastic and Reconstructive Surgeon, Prince of Wales, Sydney Children’s and Royal Hospital for Women, NSW; Andrea Concannon, consumer; Jenny Gilchrist, Nurse Practitioner Breast Oncology, Macquarie University Hospital, NSW; Monica Graham, 13 11 20 Consultant, Cancer Council WA; Natasha Keir, Nurse Practitioner Breast Oncology, GenesisCare, QLD; Dr Bronwyn Kennedy, Breast Physician, Chris O’Brien Lifehouse and Westmead Breast Cancer Institute, NSW; Lisa Montgomery, consumer; A/Prof Sanjay Warrier, Specialist Breast Surgeon, Chris O’Brien Lifehouse, NSW; Dr Janice Yeh, Radiation Oncologist, Peter MacCallum Cancer Centre, VIC. We also thank the health professionals, consumers and editorial teams who have worked on previous editions of this title.
Photographs have been reproduced with permission from A/Prof James French, Westmead Breast Cancer Institute, NSW; Prof Elisabeth Elder, Westmead Breast Cancer Institute and The University of Sydney, NSW; and Breast Cancer: Taking Control, breastcancertakingcontrol.com © Boycare Publishing, 2010.
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