Pertuzumab

Pertuzumab is a recombinant humanized monoclonal antibody and targeted anticancer medicine used to treat human epidermal growth factor receptor 2 (HER2)-positive breast cancer. It belongs to the HER2/neu receptor antagonist class of medicines and works by binding to a specific region of the HER2 receptor on cancer cells. This prevents HER2 from pairing with other HER-family receptors, particularly HER3, thereby reducing signalling pathways involved in cancer cell growth and survival. Pertuzumab is commonly combined with trastuzumab, which binds to a different region of HER2, and chemotherapy to provide complementary HER2 blockade. Depending on the disease setting, it may also be used with other approved HER2-directed treatments. Pertuzumab is administered intravenously by a healthcare professional, with dosing generally repeated every three weeks. Treatment selection depends on confirmed HER2-positive tumour status, disease stage, previous treatment, and the patient's overall health. It is used in both early-stage and metastatic breast cancer in defined treatment regimens. Important safety considerations include reduced heart function, infusion-related reactions, hypersensitivity, diarrhoea, and potential harm to an unborn baby. Cardiac assessments and appropriate clinical monitoring are therefore important throughout treatment. The choice and duration of treatment should be determined by an oncology specialist according to the approved regimen and individual treatment response.

Pertuzumab was developed as a targeted antibody against HER2, a receptor that can be overexpressed in certain breast cancers and contribute to tumour growth. Its distinct binding site on HER2 allows it to complement trastuzumab and provide dual receptor blockade. The medicine was first approved by the United States Food and Drug Administration (FDA) in June 2012 for HER2-positive metastatic breast cancer in combination with trastuzumab and docetaxel. The European Medicines Agency (EMA) granted marketing authorisation in the European Union on 4 March 2013. Subsequent clinical evidence, including the NeoSphere and TRYPHAENA studies in the neoadjuvant setting and the APHINITY study in the adjuvant setting, supported its use in selected patients with early-stage HER2-positive breast cancer. The CLEOPATRA trial established its role in metastatic disease. In December 2025, the FDA also approved trastuzumab deruxtecan in combination with pertuzumab for the first-line treatment of adults with unresectable or metastatic HER2-positive breast cancer under the specified eligibility criteria. Regulatory indications and approved combinations may differ by country and product. Local prescribing information should be checked before treatment decisions are made.

Pertuzumab is used in combination with other anticancer medicines for selected adults with confirmed HER2-positive breast cancer. In metastatic disease, it is used with trastuzumab and docetaxel for patients who have not previously received anti-HER2 therapy or chemotherapy for metastatic disease. It may also be used with trastuzumab and chemotherapy before surgery, known as neoadjuvant treatment, for eligible patients with locally advanced, inflammatory, or early-stage breast cancer at increased risk of recurrence. After surgery, it may be continued with trastuzumab and chemotherapy as adjuvant treatment for patients with HER2-positive early breast cancer at high risk of recurrence. In the United States, pertuzumab is also used with trastuzumab deruxtecan for eligible adults receiving first-line treatment for unresectable or metastatic HER2-positive breast cancer under the applicable approval. Pertuzumab is not intended for every type of breast cancer; confirmation of HER2 status through appropriate tumour testing is essential. The selected combination depends on disease stage, previous treatment, tumour characteristics, local regulatory approval, and the patient's clinical condition.

Pertuzumab is administered as an intravenous infusion by a trained healthcare professional in a clinical setting. For the standard three-weekly intravenous regimen, the recommended initial dose is 840 mg infused over approximately 60 minutes, followed by 420 mg every three weeks, usually infused over 30–60 minutes if the previous infusion was tolerated. It is commonly given alongside trastuzumab and chemotherapy, with the administration schedule coordinated with the other medicines in the regimen. The exact schedule, infusion sequence, and treatment duration depend on whether pertuzumab is being used for neoadjuvant, adjuvant, or metastatic disease and on the specific approved combination. In early breast cancer, treatment may continue through the planned perioperative regimen, with adjuvant pertuzumab-containing treatment generally limited to a total course of up to one year or 18 cycles, as applicable. In metastatic disease, treatment is generally continued until disease progression or unacceptable toxicity. Cardiac function should be assessed before treatment and regularly during therapy. Missed doses, prolonged treatment interruptions, and infusion reactions require management according to the relevant prescribing information.

Common side effects associated with pertuzumab-containing regimens include diarrhoea, nausea, vomiting, fatigue, rash, hair loss, and reduced appetite. Patients may also experience neutropenia, anaemia, low white blood cell counts, peripheral neuropathy, or other blood-related changes, particularly when chemotherapy is part of the treatment. Infusion-related symptoms such as chills, fever, headache, or allergic-type reactions can occur during or after administration. The frequency and severity of adverse effects depend on the combination regimen, treatment setting, and individual health status. Some effects may be manageable with supportive medicines, hydration, dose adjustments of accompanying chemotherapy, or other measures prescribed by the oncology team. Patients should report persistent diarrhoea, fever, unusual bruising, worsening fatigue, or symptoms that interfere with daily activities. Side effects should be assessed by the treating team rather than managed by independently stopping or changing treatment.

Pertuzumab carries important warnings concerning left ventricular dysfunction and embryo-fetal toxicity. Treatment may reduce the heart's pumping ability and, in some cases, contribute to clinical heart failure, particularly when used with other HER2-directed medicines or certain chemotherapy regimens. Cardiac function must be assessed before treatment and monitored at appropriate intervals; treatment may need to be withheld or discontinued if clinically significant deterioration occurs. Infusion-related reactions and serious hypersensitivity, including anaphylaxis, can occur and require prompt medical assessment and treatment. Exposure during pregnancy may cause fetal harm, including pregnancy loss or birth defects, so pregnancy status should be assessed before treatment when applicable and effective contraception discussed. Severe or persistent diarrhoea and complications related to accompanying chemotherapy also require clinical attention. Patients should seek urgent medical care for severe breathing difficulty, facial or throat swelling, chest pain, fainting, or other signs of a serious reaction. Treatment interruption or permanent discontinuation should be decided by the oncology team according to the severity of the event and the applicable prescribing guidance.

Before starting pertuzumab, clinicians should confirm HER2-positive disease using an appropriately validated test and review the patient's medical history, cardiac function, current medicines, pregnancy status where relevant, and planned treatment regimen. Patients with existing heart disease, reduced left ventricular ejection fraction, previous cardiotoxic treatment, or other cardiovascular risk factors may require closer assessment and monitoring. Pregnancy should be avoided during treatment, and patients who could become pregnant should receive counselling about effective contraception and the recommended precautions after the last dose according to the applicable product information. Breastfeeding should also be discussed with the treating specialist. Pertuzumab is a monoclonal antibody cleared mainly through protein catabolism rather than the usual pathways responsible for many small-molecule drug interactions, so classic metabolic interactions are not generally expected. However, its use with trastuzumab, chemotherapy, or other HER2-directed medicines can affect the overall safety profile, especially cardiac function and blood counts. All prescription medicines, non-prescription products, and supplements should be reviewed by the healthcare team. Vaccine decisions, including the timing of live vaccines during chemotherapy or other immunosuppressive treatment, should be guided by the treating clinician and the relevant regimen.

Confirm HER2 status before prescribing pertuzumab and select the regimen according to the approved indication, disease stage, and previous treatment history. Document baseline left ventricular ejection fraction and arrange repeat cardiac assessments throughout therapy in line with the relevant prescribing information and the patient's cardiac risk. Verify pregnancy status where applicable and provide counselling on fetal risk and contraception. Before each infusion, review recent symptoms, previous infusion reactions, diarrhoea, hydration, blood counts, and the tolerability of accompanying treatments. Administer the initial dose over the recommended period and observe the patient for infusion-related or hypersensitivity reactions, with emergency medicines and equipment available. Ensure that trastuzumab, chemotherapy, and any other combination medicines are scheduled and administered according to their individual prescribing instructions. If an infusion is delayed or interrupted, follow the specific product guidance for restarting or repeating a dose rather than automatically resuming the previous schedule. Provide clear patient instructions about cardiac symptoms, severe diarrhoea, fever, allergic reactions, and when urgent medical assessment is required. Coordinate care among oncology prescribers, pharmacists, infusion nurses, and other relevant healthcare professionals to support safe administration and consistent monitoring.