pertuzumab
Perjeta (pertuzumab) is a HER2/neu receptor antagonist from Genentech that blocks HER2 from pairing with other HER family receptors, shutting down a key growth signal in HER2-positive breast cancer. It is used with trastuzumab and chemotherapy in metastatic, neoadjuvant, and adjuvant settings.
This page is based on EMA, FDA, DailyMed, and NCI prescribing information for pertuzumab; the mechanism is explained in plain language, and analogies are used only where they stay accurate.
How it works
Explains what the medicine does in the body, not dosing, side effects, or safety.
An analogy
Imagine HER2 as a socket on the surface of a breast cancer cell that is always looking for a plug to pair with. When it finds a partner — say HER3 — the two snap together and send a powerful 'grow and divide' message into the cell. Pertuzumab acts like a cap that fits over the socket, so no partner can plug in. Without that pairing, the growth signal never gets sent, and the cancer cell slows down or dies.
In simple terms
Pertuzumab is a monoclonal antibody that targets the HER2 receptor on cancer cells. HER2 is a protein found in excess on some breast cancer cells, where it teams up with other HER family receptors to drive rapid cell growth. Pertuzumab binds to HER2 at the spot where it would normally pair with a partner receptor, blocking that pairing and the growth signals that follow. It is always given together with trastuzumab — which binds a different part of HER2 — and chemotherapy, so the cancer cell is attacked from more than one direction.
In depth
Pertuzumab is a humanised IgG1 monoclonal antibody that binds to subdomain II of the extracellular domain of HER2 (ERBB2). This is the dimerisation arm required for HER2 to form heterodimers with HER1 (EGFR), HER3 (ERBB3), or HER4 (ERBB4). By sterically blocking this interface, pertuzumab inhibits ligand-independent HER2 homodimerisation as well as ligand-dependent heterodimerisation, suppressing downstream PI3K/Akt/mTOR and RAS/RAF/MEK/ERK signalling cascades. Because HER3 is the most potent activator of the PI3K pathway and cannot signal without dimerising with HER2, pertuzumab is particularly effective at shutting down this axis. Combined with trastuzumab (which binds subdomain IV and promotes antibody-dependent cellular cytotoxicity and receptor degradation), the two antibodies produce complementary anti-HER2 activity.
See it in motion
A schematic animation of the mechanism — simplified for clarity, not drawn to scale.
Pertuzumab acts like a cap that fits over the socket
- HER2 is a protein found in excess on some breast cancer cells, where it teams up with other HER family receptors to drive rapid cell growth.
- When it finds a partner — say HER3 — the two snap together and send a powerful 'grow and divide' message into the cell.
- Pertuzumab binds to HER2 at the spot where it would normally pair with a partner receptor, blocking that pairing and the growth signals that follow.
- Without that pairing, the growth signal never gets sent, and the cancer cell slows down or dies.
Target: HER2 (ERBB2)
A transmembrane tyrosine kinase receptor of the EGFR family; unlike other family members, HER2 has no known direct ligand but is the preferred dimerisation partner for other activated HER receptors. Pertuzumab binds domain II of HER2, preventing it from pairing with HER1, HER3, or HER4 and blocking downstream proliferative signalling.
Approved uses
Approved uses differ by country and change over time. Always follow your local prescribing information.
Approved uses in European Union
EMA- In combination with trastuzumab and docetaxel, for the treatment of adult patients with HER2-positive metastatic or locally recurrent unresectable breast cancer who have not received previous anti-HER2 therapy or chemotherapy for their metastatic disease
- In combination with trastuzumab and chemotherapy, for the neoadjuvant treatment of adult patients with HER2-positive, locally advanced, inflammatory, or early stage breast cancer at high risk of recurrence
Approved uses in United States
FDA- In combination with trastuzumab and docetaxel, for the treatment of adults with HER2-positive metastatic breast cancer who have not received prior anti-HER2 therapy or chemotherapy for metastatic disease
- In combination with trastuzumab and chemotherapy, as neoadjuvant treatment of adults with HER2-positive, locally advanced, inflammatory, or early stage breast cancer (either greater than 2 cm in diameter or node positive), as part of a complete treatment regimen for early breast cancer
- Adjuvant treatment of adults with HER2-positive early breast cancer at high risk of recurrence
Approved uses in United States
DailyMed- In combination with trastuzumab and docetaxel, for the treatment of adults with HER2-positive metastatic breast cancer who have not received prior anti-HER2 therapy or chemotherapy for metastatic disease
- In combination with trastuzumab and chemotherapy, for the neoadjuvant treatment of adults with HER2-positive, locally advanced, inflammatory, or early stage breast cancer as part of a complete treatment regimen for early breast cancer
- Adjuvant treatment of adults with HER2-positive early breast cancer at high risk of recurrence
Approved uses in United States
NCI- A humanized recombinant monoclonal antibody directed against the extracellular dimerization domain of the HER-2 tyrosine kinase receptor; binding directly inhibits the ability of HER-2 to dimerize with other HER tyrosine kinase receptor proteins, preventing activation of HER signalling pathways and resulting in tumor cell apoptosis
Official sources
The statements on this page trace back to these records.
- Perjeta (pertuzumab) — Summary of product characteristics and package leaflet, English version
European Medicines Agency
- U.S. Food and Drug Administration: PERJETA prescribing information
U.S. Food and Drug Administration
- DailyMed: PERJETA prescribing information
DailyMed, U.S. National Library of Medicine
- National Cancer Institute: pertuzumab
National Cancer Institute
This page explains how the medicine works — it isn’t the patient leaflet. For anything that applies to you, read the leaflet that came with your medicine or ask your pharmacist.
MedUnfold provides educational content and is not medical advice. Always follow your local prescribing information and healthcare professional.