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What is Herceptin? Is Herceptin a chemo drug? How does it work?

Medically reviewed by Melisa Puckey, BPharm. Last updated on Oct 9, 2023.

What is Herceptin? What does HER2 positive mean?

Official answer


What is Herceptin?

Herceptin (generic name: trastuzumab) is an anticancer drug.

Is Herceptin a chemo drug?

No, Herceptin is not a chemo drug, it is a targeted therapy anticancer drug.

Anticancer drugs can be divided into different groups:

  • targeted therapy
  • chemotherapy (often called chemo)
  • hormonal drug therapy
  • Immunotherapy

Herceptin belongs in the targeted therapy group of anticancer drugs, so it is not in the chemotherapy group of anticancer drugs.

Targeted therapy can be further divided into different subgroups:

  • monoclonal antibodies (herceptin)
  • angiogenesis inhibitors
  • proteasome inhibitors
  • signal transduction inhibitors

Herceptin is a type of targeted therapy anticancer drug called a monoclonal antibody. Herceptin works by targeting HER2 receptors to fight cancer cell growth.

What does HER2 positive mean and how does it cause cancer?

  • Genes (in our cells) are the code or formula for making proteins that a cell needs to function and be healthy.
  • HER2 (human epidermal growth factor receptor2) is a gene that has the code for a protein that is the HER2 receptor.
  • HER2 receptors control how a healthy cell grows, divides, and repairs itself.
  • In some people the HER2 gene is faulty and there ends up being too many HER2 genes - this is called HER2 gene amplification.
  • When there are a lot more HER2 genes, they make too many HER2 receptors - this is called HER2 receptor overexpression.
  • The excessive amount of HER2 receptors causes cancer to develop as the cells divide and multiply in an uncontrolled way.
  • Cancer is called HER2 positive (HER2 +) if you have HER2 gene amplification or HER2 receptor overexpression.
  • Cancer that is HER2 positive can be treated with anticancer drugs that attach to and block the HER2 receptors, so slows cells multiplying and prevents cancer progression.

How does Herceptin work?

  • Herceptin is from a group of medicines called monoclonal antibodies, which are sometimes called biological drugs
  • Herceptin is an antibody that is created to match the cancer cell receptor called HER2, and attaches to it like a key fits a lock.
  • People with HER2 positive cancer have too many HER2 genes and too many HER2 receptors which triggers cells to multiply very quickly
  • Herceptin binds to the HER2 receptor and prevents the cancer cells from multiplying which prevents further cancer growth.
  • Another way Herceptin works against cancer is once it is bound to the HER2 receptor it makes it a target for the immune cells to kill it. This is called antibody-dependant cellular cytotoxicity (ADCC)

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What cancers is Herceptin used for?

Herceptin is used specifically for breast cancer and gastric cancer that are HER2 positive.

Adjuvant breast cancer:

  • Herceptin is indicated for adjuvant treatment of HER2 overexpressing node positive or node negative (estrogen receptor-negative/progesterone receptor-negative or with one high risk feature) breast cancer.
  • High risk features are pathological tumor size greater than 2 cm, Grade 2–3, or age < 35 years.
  • Herceptin is part of a combination treatment plan.
  • Adjuvant treatment is a treatment after tumor removal surgery, so that it destroys any remaining cells that may have been left behind and so helps prevent recurrence.

Metastatic Breast Cancer:

  • Herceptin is used as first line treatment for HER2-overexpressing metastatic breast cancer, in combination with paclitaxel.
  • Herceptin is used on its own in patients who have received one or more chemotherapy regimes for the metastatic HER2-overexpressing breast cancer.

Metastatic Gastric Cancer:

  • Herceptin can be used in patients who have HER2-overexpressing metastatic gastric cancer or gastroesophageal junction adenocarcinoma, and
  • have not had any earlier treatment of metastatic cancer, and
  • is used in combination with cisplatin and capecitabine or 5-fluorouracil.

Bottom line:

  • Herceptin is a type of targeted therapy anticancer drug called a monoclonal antibody.
  • Herceptin is used to treat cancers that are HER2 positive and is indicated for adjuvant breast cancer, metastatic breast cancer and metastatic gastric cancer.
  • Herceptin works by binding to the HER2 receptor which prevents the number cells from multiplying which prevents further cancer growth, and also makes the cancer cells a target so that the immune system will destroy the cancer cell.

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