Pertuzumab: Uses, Side Effects and Treatment Guide

Disclaimer: This information is intended to help you understand your treatment. Always discuss your health and treatment plan with your doctor or nurse, who can answer your specific questions.

If pertuzumab has been added to your breast cancer treatment, you may wonder why you need it as well as trastuzumab. The two medicines have similar names and act on the same target, but they attach to different parts of it.

Pertuzumab is a targeted treatment, not chemotherapy. It is often given with trastuzumab and chemotherapy to treat HER2-positive breast cancer. The combination your doctor recommends depends on the extent of the cancer, previous treatment and your general health.

Pertuzumab at a glance

What it treats: HER2-positive breast cancer—cancer with high amounts of a protein called HER2.
How it is used: With other cancer medicines, commonly trastuzumab and chemotherapy.
How it is given: Through a drip into a vein, or as a separate preparation combining pertuzumab and trastuzumab in an injection under the skin.
How often: Every three weeks.
What needs attention: Diarrhoea can occur, and regular heart checks are needed.

Why has pertuzumab been recommended?

HER2 is a protein on the surface of cells that helps them grow and divide. Some breast cancers have much more HER2 than usual. These are called HER2-positive cancers. Testing a sample of the cancer to confirm this is necessary before starting pertuzumab.

Pertuzumab helps prevent HER2 from joining with other related proteins to send growth signals. Trastuzumab acts on a different part of HER2. Using them together can block these signals more effectively than either approach alone.

Pertuzumab may be recommended in the following situations:

Before breast surgery (neoadjuvant therapy): With trastuzumab and chemotherapy to help shrink the cancer. It is used for selected patients, including those with larger tumours or cancer in nearby lymph nodes, the small glands that help filter fluid from tissues.
After breast surgery (adjuvant therapy): With trastuzumab as part of treatment to reduce the chance of the cancer returning. It is generally considered when that risk is higher.
When cancer has spread: With other medicines to help control HER2-positive breast cancer. One established combination is pertuzumab, trastuzumab and chemotherapy.

For some patients with breast cancer that cannot be removed by surgery or has spread, pertuzumab may instead be combined with trastuzumab deruxtecan. This is a different treatment combination with its own side effects and monitoring needs.

Approval and availability vary between countries. Your cancer team can explain whether the treatment described here is approved and appropriate for your situation.

How is pertuzumab administered?

There are two ways to administer treatment containing pertuzumab. The preparations are different and must be used by the intended route:

A drip into a vein: The first pertuzumab dose is given over about 60 minutes. Later doses may be administered faster if the first dose is well tolerated. Other medicines in your treatment plan are given separately.
An injection under the skin of the thigh: A combined preparation contains both pertuzumab and trastuzumab. It is an option when your treatment plan requires both medicines.

Time for checks, other medicines and observation adds to the appointment. Your team will watch for reactions during and after each dose, particularly the first.

The combined injection is not a substitute for pertuzumab plus trastuzumab deruxtecan. It contains trastuzumab, which is a different medicine.

How long will treatment continue?

Pertuzumab is given every three weeks. The overall treatment period depends on the purpose of treatment:

For early breast cancer: When continued after surgery, pertuzumab and trastuzumab are commonly planned for up to one year in total, including treatment given before surgery. Findings at surgery and side effects may lead your doctor to change the plan.
For cancer that has spread: Treatment may continue while it is controlling the cancer and side effects remain manageable. In a trastuzumab–pertuzumab plan, these two medicines may continue after chemotherapy finishes.

If you miss an appointment, contact your treatment team promptly. They will arrange the next dose and decide whether the delay requires any change.

What side effects should you know about?

Because pertuzumab is given with other medicines, the side effects you experience depend on the whole combination. They should not all be attributed to pertuzumab itself.

Diarrhoea

Loose or frequent stools are a recognised side effect of pertuzumab-containing treatment. They can be more troublesome while chemotherapy is also being given.

Ask your team what to do if diarrhoea starts and whether they will provide medicine to manage it. Drink fluids regularly unless your doctor has advised a fluid restriction. Contact your team if the diarrhoea continues, becomes frequent, or makes it difficult to eat or drink.

Dizziness, very little urine or an inability to keep fluids down may mean you are losing too much fluid and need urgent assessment.

Reactions during or shortly after a dose

Fever, chills, a rash, feeling sick or a headache can occur. Tell your nurse immediately if you feel unwell during treatment. The team may slow or pause the drip and give medicine to manage the reaction.

Other effects during combination treatment

You may experience:

Feeling sick, reduced appetite or a sore mouth.
Skin rash or dryness.
Tiredness or weakness.
Soreness or redness at the site of an injection.

Hair loss, changes in blood counts and tingling in the fingers or toes may occur during combination treatment. Some of these effects may be caused by the other medicines given with pertuzumab, particularly chemotherapy. They should not automatically be attributed to pertuzumab itself. Your team will explain the likely effects of your particular combination and arrange blood tests where needed.

Why are heart checks needed?

Pertuzumab-containing treatment can reduce the heart’s pumping ability, sometimes before symptoms develop.

You will usually have 2D echocardiography (2D echo) before treatment and about every three months during it. This test checks how well your heart pumps blood. Your doctor will decide whether you need additional checks.

If heart function worsens, treatment may be paused or stopped while the problem is assessed and treated.

When should you seek medical help?

Seek emergency care for:

Severe difficulty breathing.
Swelling of the tongue or throat.
Chest pain or fainting.
Severe diarrhoea, especially with signs of dehydration such as marked dizziness, confusion, very little urine or an inability to keep fluids down.

If these happen during treatment, alert the staff immediately.

Contact your cancer team urgently for:

New or worsening breathlessness, a persistent new cough, swollen feet or ankles, sudden weight gain, or a racing heartbeat.
Diarrhoea that persists or worsens, blood in the stools, or marked abdominal pain.
A temperature of 38°C or above, shaking chills, or feeling suddenly very unwell. Follow a lower temperature threshold if your team has given you one.

If you receive trastuzumab deruxtecan with pertuzumab, new breathing symptoms need prompt assessment because that medicine can cause lung inflammation.

Keep your treatment centre’s emergency contact number available to you and your family.

What should you discuss before starting?

Tell your team about any heart problems, high blood pressure, previous reactions to cancer medicines, and all medicines or supplements you take. Also mention ongoing diarrhoea or bowel problems.

If cost is a concern, ask about locally approved preparations and financial support. Where an approved pertuzumab biosimilar is available, it offers comparable effectiveness and safety and may cost less. Availability and savings vary between countries and treatment centres.

Pregnancy and breastfeeding

Pertuzumab can harm an unborn baby. If you could become pregnant, use effective birth control during treatment and for seven months after the last dose. Your team may arrange a pregnancy test before treatment starts.
Tell your team immediately if you think you may be pregnant during this period.
If you are breastfeeding, discuss this before treatment. Your team will advise you about feeding your baby safely.

How does pertuzumab differ from similarly named medicines?

Trastuzumab is another HER2-targeted medicine and is often used alongside pertuzumab. You can read more in our trastuzumab guide.

Trastuzumab emtansine and trastuzumab deruxtecan carry a cancer-killing drug attached to a HER2-targeted medicine. They are separate treatments, with different uses and side effects. Our trastuzumab deruxtecan guide explains that medicine in more detail.

Disclaimer: This article is for information only and does not replace personalised medical advice. Discuss your treatment, side effects and any concerns with your medical team. Do not start, stop or change treatment based on this article.

Pertuzumab: Uses, Side Effects and What to Expect