Key points
- Trastuzumab (Herceptin) is an antibody that attaches to the HER2 protein on cancer cells; it is used only when the tumour test is HER2-positive [1].
- It is used in HER2-positive breast cancer (after surgery or in disease that has spread) and in HER2-positive stomach cancer that has spread [1].
- After surgery for breast cancer, the whole course of treatment is one year (52 weeks), and longer is not recommended [1].
- The most important side effect is a weakened heart; this is why a heart scan (echocardiogram or a similar scan) is done before starting and every 3 months [1].
- It harms an unborn baby; avoid pregnancy during treatment and for 7 months after the last dose [1].
What is this drug and how does it work?
For physicians
Trastuzumab, brand name Herceptin, is a humanised IgG1 monoclonal antibody that binds with high affinity to the outer part of the HER2 protein (human epidermal growth factor receptor 2) [1]. In some cancers, tumour cells have a lot of HER2 protein on their surface or the HER2 gene is amplified; these tumours are called "HER2-positive", and this drug is used only for them [1].
In laboratory and animal experiments, trastuzumab has inhibited the growth of tumour cells that have a lot of HER2 [1]. It also recruits the body's immune cells to destroy cancer cells (antibody-dependent cell-mediated cytotoxicity, or ADCC), and this effect is seen preferentially in cells with a lot of HER2 [1].
Herceptin must not be substituted with the related drugs trastuzumab emtansine (Kadcyla) or trastuzumab deruxtecan (Enhertu); these are different drugs with different doses and side effects [1]. Intravenous Herceptin also has different instructions from subcutaneous trastuzumab products [1].
Which cancers is it used for?
According to the FDA label, trastuzumab is approved for adults with HER2-positive breast cancer and stomach cancer, and patients should be selected on the basis of a validated HER2 test on a tumour sample (HER2 protein overexpression or HER2 gene amplification) [1]. In stomach cancer, tests specific to stomach cancer should be used, because the HER2 staining pattern differs from breast cancer [1]. Approved uses may differ between countries, and not every patient with these cancers is a candidate for this drug.
Your doctor may prescribe this drug for:
- HER2-positive breast cancer — adjuvant treatment (after surgery) [1, 2, 3, 4]
- HER2-positive breast cancer — that has spread [1, 5]
- HER2-positive cancer of the stomach or the junction between the stomach and oesophagus — that has spread [1, 6]
- HER2-positive cancer of the stomach or the junction between the stomach and oesophagus — with pembrolizumab [7, 8]
- HER2-positive bowel cancer (outside the Herceptin label) [1, 9]
Whether it suits you depends on the type and stage of your cancer and your test results. Details of each use are in the section for doctors.
For physicians
| Cancer | Conditions of use | Key evidence |
|---|---|---|
| HER2-positive breast cancer — adjuvant treatment (after surgery) | Node-positive or node-negative disease (if node-negative: hormone receptor-negative or one high-risk feature); with doxorubicin, cyclophosphamide and paclitaxel or docetaxel, with docetaxel and carboplatin, or as a single agent after multimodality anthracycline-based chemotherapy [1] | Joint analysis of NSABP B31 and NCCTG N9831 [2]: HR for disease-free survival 0.48 and HR for overall survival 0.64 [1]; HERA [3]: HR for disease-free survival 0.54 [1]; BCIRG006 [4]: HR for disease-free survival 0.67 (TCH regimen) and 0.60 (AC→TH regimen) [1] |
| HER2-positive breast cancer — metastatic | First line with paclitaxel; or as a single agent in patients who have received one or more chemotherapy regimens for metastatic disease [1] | H0648g trial [5]: median time to progression 7.2 vs 4.5 months and median overall survival 25.1 vs 20.3 months with trastuzumab added to chemotherapy; H0649g (single agent): objective response 14% [1] |
| HER2-positive gastric or gastro-oesophageal junction cancer — metastatic | With cisplatin and capecitabine or fluorouracil, in patients who have not been treated for metastatic disease [1] | ToGA trial [6]: median overall survival 13.5 vs 11.0 months (HR 0.73) [1] |
| HER2-positive gastric or gastro-oesophageal junction cancer — with pembrolizumab | Trastuzumab with pembrolizumab and fluoropyrimidine- and platinum-containing chemotherapy, as first-line treatment of advanced tumours expressing PD-L1 (CPS ≥ 1); this use is in the pembrolizumab label [7] | KEYNOTE-811: median progression-free survival 10.0 vs 8.1 months (HR 0.72) [8] |
| HER2-positive colorectal cancer (outside the Herceptin label) | With tucatinib in metastatic or unresectable, chemotherapy-refractory, RAS wild-type disease; this use is not in the Herceptin label [1, 9] | MOUNTAINEER (phase 2, no comparison group): confirmed objective response 38.1% [9] |
The main source for the table is the FDA label for Herceptin; evidence figures are quoted from the FDA label or the original trial paper.
How it is given and dose
Treatment regimens and doses: index6 regimens
Trastuzumab is given as an intravenous infusion (drip) at the treatment centre and must not be given as a rapid intravenous injection [1]. The first dose (loading dose) is given over about 90 minutes; later doses take 30 minutes on the weekly schedule and 30 to 90 minutes on the 3-weekly schedule [1].
- Length of treatment: as adjuvant treatment of breast cancer, 52 weeks in total; in metastatic breast or stomach cancer, as long as the disease does not progress [1].
- Before starting: an HER2 test on a tumour sample, a measurement of heart function (left ventricular ejection fraction, or LVEF) by echocardiogram or MUGA scan, and, in women who could become pregnant, a check of pregnancy status [1].
- During treatment: LVEF every 3 months and at the end of treatment; after adjuvant treatment ends, every 6 months for at least 2 years [1].
- During the infusion: if an infusion reaction (such as fever and chills) occurs, the rate is slowed, and with shortness of breath or a significant fall in blood pressure the infusion is stopped [1].
Before starting: HER2 (IHC 3+ or gene amplification with an approved test; in gastric cancer with a gastric-specific test); thorough cardiac assessment and baseline LVEF by echo or MUGA immediately before starting; pregnancy test [1].
Administration: IV infusion only (not push or bolus); dilute in 250 mL of 0.9% sodium chloride (5% dextrose must not be used); do not mix with other drugs. Do not substitute with trastuzumab emtansine or trastuzumab deruxtecan (check the vial label). Premedication is not routinely needed [1].
Adjustment by LVEF (there is no dose reduction): hold for at least 4 weeks with an absolute fall of 16% or more from baseline, or LVEF below normal with an absolute fall of 10% or more; repeat LVEF every 4 weeks; resume if LVEF returns to normal within 4 to 8 weeks and the fall from baseline is 15% or less; stop permanently for a persistent fall of more than 8 weeks or more than 3 holds for cardiomyopathy [1].
For physicians
Dose and schedule (FDA label)
AC then paclitaxel + trastuzumab (NSABP B31 / N9831)
HER2-positive breast cancer, adjuvant treatmentCycle length: —
HER2-positive breast cancer, adjuvant treatment
Before prescribing: Prescribing notes| Drug | Dose | Route | Schedule |
|---|---|---|---|
| 4 cycles | |||
| Doxorubicin + cyclophosphamide | 60 + 600 mg/m² | IV | Day 1 every 3 weeks |
| 12 weeks | |||
| Paclitaxel | 80 mg/m² weekly (or 175 mg/m² every 3 weeks in B31) | IV | Weekly |
| With the taxane | |||
| Weekly trastuzumab | Initial dose 4 mg/kg, then 2 mg/kg | IV infusion; initial 90 minutes, then 30 minutes | Weekly, 12 weeks |
| One week after the last weekly dose | |||
| Trastuzumab | 6 mg/kg | IV infusion over 30 to 90 minutes | Every 3 weeks |
Chemotherapy doses as described for the trials in the label [1].
Evidence: NSABP B-31 / NCCTG N9831 (2005)
TCH: docetaxel + carboplatin + trastuzumab (BCIRG006)
HER2-positive breast cancer, adjuvant treatment without an anthracyclineCycle length: Every 3 weeks
HER2-positive breast cancer, adjuvant treatment without an anthracycline
Before prescribing: Prescribing notes| Drug | Dose | Route | Schedule |
|---|---|---|---|
| 6 cycles | |||
| Docetaxel + carboplatin | 75 mg/m² + AUC 6 | IV (carboplatin over 30 to 60 minutes) | Day 1 every 3 weeks |
| With the taxane | |||
| Weekly trastuzumab | Initial dose 4 mg/kg, then 2 mg/kg | IV infusion; initial 90 minutes, then 30 minutes | Weekly, 18 weeks |
| One week after the last weekly dose | |||
| Trastuzumab | 6 mg/kg | IV infusion over 30 to 90 minutes | Every 3 weeks |
In the AC then TH arm of the same trial, docetaxel was 100 mg/m² every 3 weeks for 4 cycles and trastuzumab weekly for 12 weeks [1].
Evidence: BCIRG-006 (2011)
Single-agent trastuzumab after chemotherapy (HERA)
Adjuvant treatment, within 3 weeks of completing multimodality anthracycline-based chemotherapyCycle length: Every 3 weeks
Adjuvant treatment, within 3 weeks of completing multimodality anthracycline-based chemotherapy
Before prescribing: Prescribing notes| Drug | Dose | Route | Schedule |
|---|---|---|---|
| Trastuzumab | Initial dose 8 mg/kg, then 6 mg/kg | IV infusion; initial 90 minutes, then 30 to 90 minutes | Every 3 weeks |
[1]
Evidence: HERA (2005)
Metastatic breast cancer
First line with paclitaxel, or as a single agent after previous chemotherapyCycle length: Weekly
First line with paclitaxel, or as a single agent after previous chemotherapy
Before prescribing: Prescribing notes| Drug | Dose | Route | Schedule |
|---|---|---|---|
| Trastuzumab | Initial dose 4 mg/kg, then 2 mg/kg | IV infusion; initial 90 minutes, then 30 minutes | Weekly |
[1]
Metastatic gastric or GEJ cancer (ToGA)
HER2-positive, no previous treatment for metastatic diseaseCycle length: Every 3 weeks
HER2-positive, no previous treatment for metastatic disease
Before prescribing: Prescribing notes| Drug | Dose | Route | Schedule |
|---|---|---|---|
| Trastuzumab | Initial dose 8 mg/kg, then 6 mg/kg | IV infusion; initial 90 minutes, then 30 to 90 minutes | Every 3 weeks |
| 6 cycles | |||
| Cisplatin | 80 mg/m² | IV infusion over 2 hours | Day 1 |
| Capecitabine or fluorouracil | 1000 mg/m² twice a day, or 800 mg/m²/day | Oral / continuous IV infusion | Days 1 to 14 / days 1 to 5 |
With PD-L1 CPS 1 or more: add pembrolizumab 200 mg before trastuzumab and chemotherapy (KEYNOTE-811; pembrolizumab label) [1, 7].
Evidence: ToGA (2010)
Subcutaneous form (Herceptin Hylecta)
HER2-positive breast cancer (adjuvant or metastatic); not gastric cancerCycle length: Every 3 weeks
HER2-positive breast cancer (adjuvant or metastatic); not gastric cancer
Before prescribing: Prescribing notes| Drug | Dose | Route | Schedule |
|---|---|---|---|
| Trastuzumab + hyaluronidase | 600 mg / 10,000 units (fixed dose, no loading dose) | Subcutaneous in the thigh over 2 to 5 minutes (alternate right and left thigh) | Every 3 weeks |
Its dose and administration differ from the IV form, and it must not be given intravenously [11].
Doses follow the trial protocol, guideline or official drug label (source given in the notes of each regimen). Before prescribing, check blood counts, renal and hepatic function, drug interactions and the patient’s condition, and adjust the dose according to the drug label.
Infusion reaction: mild to moderate: slow the rate; dyspnoea or significant hypotension: interrupt and treat; severe or life-threatening reaction: strongly consider stopping permanently. Most severe reactions occur during or immediately after the first infusion [1].
Missed dose: delay of 1 week or less: give the maintenance dose (2 or 6 mg/kg) as soon as possible and continue 7 or 21 days later. Delay of more than 1 week: re-load (4 or 8 mg/kg over about 90 minutes), then continue the schedule [1].
Monitoring: LVEF every 3 months during treatment and at the end; after adjuvant treatment every 6 months for at least 2 years. Pulmonary symptoms (pneumonitis, ARDS). Exacerbation of chemotherapy-induced neutropenia [1].
Side effects
The most common side effects:
- Fever and chills with the first infusion in about 4 in 10 people; controlled with medicines and by slowing the infusion, and less common with later infusions [1].
- Headache, diarrhoea, nausea, tiredness, cough and joint pain [1].
- When it is given with chemotherapy, low white blood cells and the fever that comes with them are slightly more common [1].
For physicians
According to the FDA label, the most common side effects of trastuzumab in adjuvant and metastatic breast cancer are: fever, nausea, vomiting, infusion reactions, diarrhoea, infections, increased cough, headache, fatigue, dyspnoea, rash, neutropenia (a type of white blood cell), anaemia and myalgia [1].
- Infusion reactions: with the first infusion, chills and fever were reported in about 40% of trial patients and were managed with symptomatic medicines and sometimes a slower infusion rate; permanent discontinuation for this reason was needed in fewer than 1% of patients [1].
- Adjuvant treatment (HERA trial, one year of trastuzumab vs observation): headache 10% vs 3%, arthralgia 8% vs 6%, nasopharyngitis 8% vs 3%, diarrhoea 7% vs 1%, fever 6% vs 0.4% and nausea 6% vs 1% [1].
- Metastatic breast cancer (single-agent trastuzumab): pain 47%, asthenia 42%, fever 36%, nausea 33%, chills 32%, headache 26%, increased cough 26% and diarrhoea 25% [1].
- Gastric cancer (ToGA trial, with chemotherapy vs chemotherapy alone): neutropenia 78% vs 73%, diarrhoea 37% vs 28%, fatigue 35% vs 28%, anaemia 28% vs 21%, stomatitis 24% vs 15% and weight loss 23% vs 14% [1].
When trastuzumab is given with chemotherapy, severe neutropenia and febrile neutropenia have been seen more often than with chemotherapy alone [1].
Serious side effects
These side effects are less common but serious; if you notice any sign of them, tell your team early:
- A weakened heart: shortness of breath, swollen legs, palpitations or unusual tiredness; this is why a heart scan is done every 3 months [1].
- A severe reaction during the infusion: shortness of breath, swelling of the face or throat, or dizziness, usually with the first infusion or up to 24 hours later [1].
- Lung damage: a new cough or shortness of breath [1].
- Harm to an unborn baby: do not become pregnant during treatment and for 7 months afterwards [1].
For physicians
Boxed warning: the FDA label warns about four serious risks: cardiomyopathy (damage to the heart muscle), infusion reactions, pulmonary toxicity and embryo-fetal toxicity [1].
- Cardiac toxicity: trastuzumab can cause left ventricular dysfunction, arrhythmias, hypertension, disabling heart failure, cardiomyopathy and cardiac death; symptomatic cardiac dysfunction is 4 to 6 times more common in people receiving it, with the highest rate when used with anthracyclines [1]. In the joint analysis of NSABP B31 and NCCTG N9831, congestive heart failure occurred in 3.2% of the trastuzumab group vs 1.3% of the control group, and in HERA in 2% vs 0.3% [1]. The risk of cardiac dysfunction has been higher in patients aged 65 and over [1].
- Severe infusion reactions: serious and sometimes fatal reactions such as bronchospasm, anaphylaxis, angioedema (swelling under the skin and mucous membranes), hypoxia and severe hypotension have been reported, usually during or immediately after the first infusion [1]. Symptoms usually appear during the infusion or up to 24 hours afterwards [1].
- Pulmonary toxicity: including dyspnoea, interstitial pneumonitis, pulmonary infiltrates, pleural effusion, non-cardiogenic pulmonary oedema, acute respiratory distress syndrome and pulmonary fibrosis, which can be fatal [1]. In adjuvant treatment, pneumonitis or pulmonary infiltrates occurred in 0.7% of trastuzumab recipients vs 0.3% with chemotherapy alone [1].
- Embryo-fetal toxicity: use in pregnancy can lead to oligohydramnios and, as a result, pulmonary hypoplasia, skeletal abnormalities and neonatal death [1].
- Kidney problems: in ToGA, renal impairment was seen in 18% of the trastuzumab group vs 14.5% of the chemotherapy-alone group, and severe renal failure in 2.7% vs 1.7% [1].
When should I call my doctor?
If you have any of the following symptoms, contact your doctor or treatment team straight away [1]:
- New or worsening shortness of breath, or a cough
- Swelling of the ankles or legs, or of the face
- Palpitations
- Weight gain of more than 5 pounds (about 2.3 kg) in 24 hours
- Dizziness or loss of consciousness
- During the infusion or up to 24 hours afterwards: fever and chills, shortness of breath, wheezing, swelling of the face or lips, or feeling very weak
- Pregnancy or a possible pregnancy
In severe cases, such as severe shortness of breath, swelling of the face and throat or loss of consciousness, call your local emergency number.
Interactions, pregnancy and precautions
- Drug interactions: no formal drug interaction studies with Herceptin have been done in humans, but no important interactions were seen in studies with accompanying drugs such as paclitaxel, doxorubicin, docetaxel, carboplatin, cisplatin and capecitabine [1]. The most important point is anthracyclines (such as doxorubicin): because trastuzumab is cleared slowly from the body, anthracycline treatment is avoided where possible for up to 7 months after stopping it, and if needed, heart function is monitored closely [1].
- Pregnancy and contraception: pregnancy status is checked before starting, and women who could become pregnant should use effective contraception during treatment and for 7 months after the last dose [1]. If you become pregnant during treatment or within 7 months afterwards, tell your doctor straight away; monitoring for low amniotic fluid is needed [1].
- Breastfeeding: there is no information on whether trastuzumab passes into human milk; the decision about breastfeeding should be made with your doctor, taking into account its benefits, the mother's need for treatment and the 7-month washout period of the drug [1].
- Fertility: in a study in female monkeys, no evidence of impaired fertility was seen [1]; even so, if you are planning a pregnancy in the future, talk to your doctor before starting treatment.
- Vaccines: the FDA label gives no specific advice about vaccination; talk to your treatment team before any vaccine.
- Missed appointment: if you miss an infusion, contact the treatment centre as soon as possible rather than waiting for the next appointment; if the delay is more than one week, a loading dose may be needed again [1].
Frequently asked questions
Is trastuzumab chemotherapy?
No. Trastuzumab is a targeted monoclonal antibody that binds to the HER2 protein [1]. Even so, in many regimens it is given with chemotherapy drugs such as paclitaxel, docetaxel or cisplatin [1].
How long does treatment with trastuzumab last?
As adjuvant treatment of breast cancer, 52 weeks in total [1]. Continuing beyond one year is not recommended: in a large study, two years of treatment gave no extra benefit compared with one year and caused more heart problems [1]. In metastatic disease, treatment continues until the disease progresses [1].
Why do I need an echocardiogram before and during treatment?
Because the most important serious side effect of trastuzumab is heart damage, and it can lower the left ventricular ejection fraction (LVEF) even without symptoms [1]. The label recommends measuring LVEF immediately before starting, every 3 months during treatment and at the end of it, and every 6 months for at least 2 years after adjuvant treatment [1]. If a significant fall is seen, treatment is paused [1].
If my tumour is HER2-negative, will trastuzumab help?
Is Herceptin the same as Kadcyla or Enhertu?
No. All three act on HER2, but Kadcyla (trastuzumab emtansine) and Enhertu (trastuzumab deruxtecan) are antibodies joined to an anticancer drug, and the FDA label forbids substituting them for Herceptin [1]. For example, in a large study of patients who still had residual invasive disease after treatment before surgery, trastuzumab emtansine was compared with trastuzumab [10].
Scientific evidence
Show detailsHide
Key studies
5 itemsTrastuzumab in combination with chemotherapy versus chemotherapy alone for treatment of HER2-positive advanced gastric or gastro-oesophageal junction cancer (ToGA): a phase 3, open-label, randomised controlled trial
Pembrolizumab plus trastuzumab and chemotherapy for HER2-positive gastric or gastro-oesophageal junction adenocarcinoma: interim analyses from the phase 3 KEYNOTE-811 randomised placebo-controlled trial
Trastuzumab Deruxtecan plus Pertuzumab for HER2-Positive Metastatic Breast Cancer
Tucatinib plus trastuzumab for chemotherapy-refractory, HER2-positive, RAS wild-type unresectable or metastatic colorectal cancer (MOUNTAINEER): a multicentre, open-label, phase 2 study
Trastuzumab Emtansine for Residual Invasive HER2-Positive Breast Cancer
Related cancer types
Treatment regimens (physicians)
References
11 referencesShow all references, 8 with a study cardClose the reference list
Numbers in the text, such as [1], refer to these sources. Sources with a “Study card” button are summarised in the site’s evidence library.
- 1HERCEPTIN (trastuzumab) for injection, for intravenous use: Prescribing Information
- 2Trastuzumab plus Adjuvant Chemotherapy for Operable HER2-Positive Breast Cancer
- 3Trastuzumab after Adjuvant Chemotherapy in HER2-Positive Breast Cancer
- 4Adjuvant Trastuzumab in HER2-Positive Breast Cancer
- 5Use of Chemotherapy plus a Monoclonal Antibody against HER2 for Metastatic Breast Cancer That Overexpresses HER2
- 6Trastuzumab in combination with chemotherapy versus chemotherapy alone for treatment of HER2-positive advanced gastric or gastro-oesophageal junction cancer (ToGA): a phase 3, open-label, randomised controlled trial
- 7
- 8Pembrolizumab plus trastuzumab and chemotherapy for HER2-positive gastric or gastro-oesophageal junction adenocarcinoma: interim analyses from the phase 3 KEYNOTE-811 randomised placebo-controlled trial
- 9
- 10Trastuzumab Emtansine for Residual Invasive HER2-Positive Breast Cancer
- 11HERCEPTIN HYLECTA (trastuzumab and hyaluronidase-oysk) injection, for subcutaneous use: Prescribing Information
This page is based on reputable scientific sources and was last updated on 28 October 2026. The content of this website is for educational and informational purposes only and does not replace consultation, diagnosis or treatment by a specialist physician. Consult your treating physician about any treatment decision.
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