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How do Herceptin (trastuzumab) and Perjeta (pertuzumab) work together?

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

How do Herceptin and Perjeta work together for breast cancer?

Official answer


Herceptin and Perjeta work together by blocking the HER2 receptor, but instead of blocking the HER2 receptor in the same place, they each block separate areas, which means that when used together they are more effective at reducing breast cancer cell growth.

How do they work?

Herceptin (generic name: trastuzumab) and Perjeta (generic name: pertuzumab) are HER2 inhibitors so work by binding to HER2 receptor which:

  • Slows or reduces breast cancer growth.
  • Marks the cancer cell so that immune cells will recognize it as a cancer cell and destroy it.

Cancer occurs when cells grow in an uncontrolled fashion, so that the tumor can grow and spread.
How fast our cells grow, divide and repair themselves is controlled by receptors on the cells, when the receptor gets a signal the cell grows and divides.

Slowing breast cancer growth

  • In HER2 positive (HER2 +) breast cancer there are a lot more HER2 receptors on the cells than usual, so when there is a signal for growth all of the HER2 receptors give the cell the same message to grow and multiply, because there are so many messages it triggers the cancer cells grow and multiply too fast and too often.
  • Both Herceptin and Perjeta attach to the HER2 receptor which blocks the message telling the breast cancer cell to grow and multiply.
  • As the message is blocked it means that the cancer growth slows or stops.

Destroying breast cancer cells

  • Once Herceptin or Perjeta binds to the HER2 receptor on the breast cancer cell it also makes the cancer cell a target for the immune cells, who will recognize it and destroy the breast cancer cell.

Treatment Plans.

  • For specific types of breast cancer both drugs are given as part of a treatment plan in combination with other medications.

Click here for more information about Breast Cancer: Treatment and Prevention Options

Bottom Line:

  • Herceptin and Perjeta both block the HER2 receptor on breast cancer cells.
  • Binding to the HER2 receptor causes the breast cancer growth to be reduced and marks the breast cancer cells as a target for the immune cells, which destroy them.
  • By blocking the HER2 receptor in two separate areas means both drugs are attacking the HER2 receptor in two places, so that together they are more successful at suppressing tumor growth.

Related questions

  • Herceptin FDA Prescribing Label: [Accessed October 19, 2021]
  • Perjeta FDA Prescribing label [Accessed October 19, 2021]
  • Pertuzumab, trastuzumab, and docetaxel for HER2-positive metastatic breast cancer (CLEOPATRA study): overall survival results from a randomised, double-blind, placebo-controlled, phase 3 study: [Accessed October 19,2021]
  • Targeted Therapies: Perjeta [Accessed October 19,2021]
  • Targeted Therapies: Herceptin [Accessed October 19,2021]

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