Zercepac: Uses, Dosage & Side Effects
A monoclonal antibody targeting HER2-positive breast cancer and gastric cancer, working by binding to the HER2 receptor to inhibit cancer cell growth and trigger immune-mediated destruction
Zercepac (trastuzumab) is a monoclonal antibody used to treat HER2-positive breast cancer and HER2-positive metastatic gastric (stomach) cancer. It works by binding selectively to the HER2 protein on the surface of cancer cells, blocking the signals that drive tumor growth and flagging the cells for destruction by the immune system. Zercepac is a biosimilar to Herceptin and is administered as an intravenous infusion in a hospital or clinic setting. It is used both in early-stage breast cancer (to reduce the risk of recurrence after surgery) and in advanced or metastatic disease, either alone or in combination with chemotherapy. Treatment with Zercepac requires regular cardiac monitoring due to the risk of heart-related side effects.
Quick Facts: Zercepac
Key Takeaways
- Zercepac (trastuzumab) is a targeted monoclonal antibody that works specifically against HER2-positive cancers by binding to the HER2 receptor, blocking tumor growth signals and triggering immune-mediated cell death.
- It is approved for HER2-positive early breast cancer, metastatic breast cancer, and metastatic gastric cancer, and may be given alone or combined with chemotherapy agents such as paclitaxel, docetaxel, capecitabine, or cisplatin.
- Cardiotoxicity is the most significant risk: cardiac function must be monitored before, during (every 3 months), and for up to 2–5 years after treatment, as trastuzumab can cause heart muscle weakening and heart failure.
- The first infusion is given over 90 minutes with close observation; if tolerated, subsequent infusions may be shortened to 30 minutes. Treatment is typically given every 3 weeks or weekly depending on the regimen.
- Effective contraception must be used during treatment and for at least 7 months after the last dose; trastuzumab can cause serious harm to a developing fetus including reduced amniotic fluid and fetal death.
What Is Zercepac and What Is It Used For?
Zercepac contains the active substance trastuzumab, a recombinant humanized monoclonal antibody. Monoclonal antibodies are laboratory-engineered proteins designed to recognize and attach to specific targets on cells. Trastuzumab is designed to bind selectively to an antigen called human epidermal growth factor receptor 2 (HER2), also known as ErbB2. HER2 is a transmembrane protein that belongs to the epidermal growth factor receptor family, a group of receptor tyrosine kinases that play crucial roles in cell growth, differentiation, and survival.
In healthy tissue, HER2 is expressed at low levels and participates in normal cell signaling. However, in certain cancers, the HER2 gene is amplified and the HER2 protein is overexpressed—present in abnormally high quantities on the cancer cell surface. This overexpression, found in approximately 15–20% of breast cancers and 10–20% of gastric cancers, drives aggressive tumor growth by sending continuous proliferation signals to the cell. HER2-positive cancers tend to grow more rapidly and have historically been associated with a poorer prognosis than HER2-negative cancers.
When Zercepac binds to the extracellular domain of HER2, it exerts its anticancer effects through several complementary mechanisms. First, it blocks HER2-mediated intracellular signaling, preventing the activation of downstream pathways (such as PI3K/AKT and RAS/MAPK) that promote cell proliferation and survival. Second, it prevents the proteolytic cleavage of the HER2 extracellular domain, which would otherwise release a truncated but constitutively active fragment that can drive cancer growth. Third, and critically, trastuzumab recruits immune effector cells—particularly natural killer (NK) cells—to the cancer cell surface, triggering a process called antibody-dependent cellular cytotoxicity (ADCC), whereby the immune system directly kills the HER2-overexpressing cancer cells.
Zercepac is a biosimilar to the reference product Herceptin, meaning it has been developed and approved to be highly similar to the originator biologic in terms of quality, safety, and efficacy. Biosimilar trastuzumab products undergo rigorous comparative studies to demonstrate that there are no clinically meaningful differences from the reference product. Other approved trastuzumab biosimilars include Ontruzant, Ogivri, KANJINTI, Trazimera, and Herzuma.
Your doctor may prescribe Zercepac for the treatment of the following HER2-positive cancers:
- Early breast cancer with high HER2 levels: After surgery and/or radiotherapy, Zercepac is given as adjuvant therapy to reduce the risk of cancer recurrence. The landmark HERA trial and subsequent studies demonstrated that one year of adjuvant trastuzumab reduces the relative risk of recurrence by approximately 40% and improves overall survival in patients with HER2-positive early breast cancer. Trastuzumab may be given after standard chemotherapy, or concurrently with taxane-based chemotherapy, followed by single-agent trastuzumab to complete a total treatment duration of one year.
- Metastatic breast cancer with high HER2 levels: Zercepac can be used as first-line treatment in combination with chemotherapy agents such as paclitaxel or docetaxel. It may also be prescribed in combination with aromatase inhibitors for patients whose tumors are both HER2-positive and hormone receptor-positive. In cases where other treatments have proven ineffective, Zercepac may be used as monotherapy. The addition of trastuzumab to chemotherapy in HER2-positive metastatic breast cancer has been shown to improve overall response rates, time to disease progression, and overall survival.
- Metastatic gastric (stomach) cancer with high HER2 levels: Zercepac is used in combination with capecitabine or 5-fluorouracil and cisplatin as first-line treatment. The ToGA trial demonstrated that adding trastuzumab to chemotherapy significantly improved overall survival in patients with HER2-positive advanced gastric or gastro-oesophageal junction cancer, with a median survival benefit of approximately 2.7 months.
Before starting treatment with Zercepac, your doctor will test your tumor to confirm that it is HER2-positive. This is typically done using immunohistochemistry (IHC), which measures the amount of HER2 protein on the cell surface, and/or fluorescence in situ hybridization (FISH), which detects amplification of the HER2 gene. Only patients whose tumors are confirmed as HER2-positive will benefit from trastuzumab treatment.
Zercepac is only effective in cancers that overexpress HER2. Testing for HER2 status is a mandatory step before treatment can begin. Tumors classified as IHC 3+ or IHC 2+ with a positive FISH result are considered HER2-positive and eligible for trastuzumab therapy. If your tumor is HER2-negative, Zercepac will not provide clinical benefit.
What Should You Know Before Taking Zercepac?
Contraindications
There are specific situations in which Zercepac must not be used. Understanding these absolute contraindications is essential for patient safety before treatment begins.
- Hypersensitivity: Do not receive Zercepac if you are allergic (hypersensitive) to trastuzumab, murine (mouse) proteins, or any of the other ingredients in this medicine (L-histidine hydrochloride monohydrate, L-histidine, trehalose dihydrate, polysorbate 20). Allergic reactions can range from mild skin rashes to severe anaphylaxis.
- Severe respiratory compromise: Zercepac must not be given to patients who have severe breathing difficulties at rest due to their underlying cancer or who require supplemental oxygen therapy. The risk of fatal pulmonary events is significantly increased in these patients.
Warnings and Precautions
Treatment with Zercepac, alone or in combination with a taxane, can cause heart problems including weakening of the heart muscle and heart failure. The risk is increased if you have previously been treated with anthracycline chemotherapy (such as doxorubicin or epirubicin). Cardiac function will be monitored before treatment, every 3 months during treatment, and for 2–5 years after treatment ends. Some patients have died from cardiac complications. Report any new shortness of breath, leg swelling, persistent cough, or irregular heartbeat to your doctor immediately.
Before and during treatment with Zercepac, tell your doctor if any of the following apply to you:
- Heart disease history: If you have had heart failure, coronary artery disease, heart valve disease (heart murmurs), or high blood pressure, or if you are taking or have taken blood pressure medications. These conditions increase your risk of cardiac complications with trastuzumab.
- Previous anthracycline treatment: If you have previously received or are currently receiving doxorubicin or epirubicin (or any other anthracycline chemotherapy). These drugs can damage the heart muscle and increase the risk of heart problems when combined with trastuzumab, even when not given simultaneously.
- Breathing difficulties: If you suffer from shortness of breath, particularly if you are also being treated with a taxane (paclitaxel or docetaxel). Zercepac can cause respiratory difficulties, especially during the first infusion. In very rare cases, patients with severe pre-existing breathing problems have died during trastuzumab treatment.
- Previous cancer treatments: If you have received any other cancer treatments previously, as these may affect your ability to tolerate trastuzumab or influence the risk of certain side effects.
If you are receiving Zercepac in combination with other cancer treatments such as paclitaxel, docetaxel, an aromatase inhibitor, capecitabine, 5-fluorouracil, or cisplatin, you should also read the patient information leaflets for those medicines carefully.
Cardiac Monitoring Schedule
Because of the risk of cardiotoxicity, your heart function will be carefully assessed throughout your treatment journey with Zercepac. This monitoring typically involves echocardiography (cardiac ultrasound) or MUGA scan (multigated acquisition scan) to measure your left ventricular ejection fraction (LVEF)—a measure of how effectively your heart pumps blood.
- Before treatment: Baseline cardiac assessment is mandatory before starting Zercepac.
- During treatment: Cardiac function checks every 3 months. If signs of heart dysfunction develop, monitoring may increase to every 6–8 weeks.
- After treatment: Continued monitoring for 2–5 years after the last dose, as cardiac effects can be delayed.
If you develop signs of heart failure (inadequate blood pumping), your doctor may increase the frequency of monitoring, initiate treatment for heart failure, or discontinue Zercepac therapy depending on the severity.
Pregnancy and Breastfeeding
If you are pregnant, think you may be pregnant, or are planning to become pregnant, speak with your doctor before receiving Zercepac. You must use effective contraception during treatment and for at least 7 months after the last dose.
In rare cases, pregnant women treated with trastuzumab have experienced oligohydramnios—a reduction in the amount of amniotic fluid surrounding the developing baby. This condition can be harmful to the fetus and has been associated with incomplete lung development (pulmonary hypoplasia) and fetal death. If you become pregnant during treatment, your doctor will carefully weigh the risks and benefits of continuing therapy.
Do not breastfeed during treatment with Zercepac and for 7 months after your last dose, as the drug may pass into breast milk and could potentially harm the nursing infant.
Driving and Operating Machinery
Zercepac may affect your ability to drive or operate machinery. If you experience symptoms such as dizziness, drowsiness, chills, or fever during treatment, do not drive or operate machinery until these symptoms have resolved.
Children and Adolescents
Zercepac is not recommended for use in patients under 18 years of age. The safety and efficacy of trastuzumab have not been established in the pediatric population.
Important Information About Ingredients
Zercepac contains less than 1 mmol sodium per dose, meaning it is essentially sodium-free. It also contains polysorbate 20, which may cause allergic reactions in some individuals. Inform your doctor if you have any known allergies to polysorbates.
How Does Zercepac Interact with Other Drugs?
Drug interactions with Zercepac are primarily related to additive or synergistic toxicities when combined with other cancer treatments, rather than pharmacokinetic interactions involving drug metabolism enzymes. Trastuzumab is a large protein molecule that is not metabolized by the cytochrome P450 system, so traditional drug-drug interactions involving CYP enzymes are not a concern. However, the combination with certain other agents can significantly affect the safety profile.
It is essential to inform your doctor about all medications you are currently taking, have recently taken, or plan to take—including prescription drugs, over-the-counter medications, and herbal supplements. Because trastuzumab can take up to 7 months to be cleared from your body, you should also inform any new healthcare provider that you have been treated with Zercepac if you start any new medication within 7 months of your last dose.
Major Interactions
| Interacting Drug | Effect | Clinical Significance |
|---|---|---|
| Anthracyclines (doxorubicin, epirubicin) | Significantly increased risk of cardiotoxicity and congestive heart failure | Avoid concurrent use. If anthracyclines were given previously, cardiac risk persists. Careful cardiac monitoring is mandatory. |
| Other cardiotoxic agents | Additive risk of cardiac dysfunction | Use with caution. Increased monitoring of cardiac function recommended when combining trastuzumab with any potentially cardiotoxic medication. |
Approved Combination Regimens
| Combination Partner | Indication | Key Considerations |
|---|---|---|
| Paclitaxel | First-line metastatic breast cancer | Peripheral neuropathy may be additive. Monitor for infusion reactions with both agents. |
| Docetaxel | First-line metastatic breast cancer; early breast cancer | Neutropenia risk increased. Growth factor support may be needed. |
| Aromatase inhibitors | HER2+ and HR+ metastatic breast cancer | Used in hormone receptor-positive disease. Generally well tolerated combination. |
| Capecitabine or 5-FU + Cisplatin | Metastatic gastric cancer | Monitor for renal toxicity (cisplatin), hand-foot syndrome (capecitabine), and cardiac function. |
Trastuzumab has a long half-life of approximately 28 days. It can take up to 7 months for the drug to be completely cleared from your body after the last dose. During this period, interactions with newly started medications—particularly cardiotoxic agents—remain clinically relevant. Always inform your healthcare providers about prior trastuzumab treatment.
What Is the Correct Dosage of Zercepac?
Zercepac must only be administered by a doctor or nurse experienced in the management of cancer patients. Your doctor will determine the correct dose and treatment schedule based on your body weight, cancer type, and disease stage. Before starting treatment, your tumor must be confirmed as HER2-positive through appropriate testing.
Adults – Intravenous Formulation
The intravenous formulation of Zercepac is given as an infusion (drip) directly into a vein. Two dosing schedules are used:
Three-Weekly Regimen (Most Common)
Loading dose: 8 mg/kg body weight, infused over 90 minutes.
Maintenance dose: 6 mg/kg body weight every 3 weeks, infused over 30–90 minutes.
Used for early breast cancer, metastatic breast cancer, and metastatic gastric cancer.
Weekly Regimen
Loading dose: 4 mg/kg body weight, infused over 90 minutes.
Maintenance dose: 2 mg/kg body weight weekly, infused over 30 minutes.
May be used for metastatic breast cancer.
Administration Details
The first dose of Zercepac is always infused over 90 minutes, and you will be closely observed by healthcare staff during and for at least 6 hours after the start of the first infusion in case of side effects, particularly infusion-related reactions. If the first dose is well tolerated, subsequent doses may be infused over 30 minutes, with observation for at least 2 hours after the infusion.
If you experience any infusion-related symptoms, the infusion rate may be slowed down or temporarily stopped. You may be given supportive treatment to manage symptoms. After improvement, the infusion can usually be resumed. Sometimes symptoms can appear more than 6 hours after the infusion has started—if this occurs, contact your doctor immediately.
Duration of Treatment
- Early breast cancer (adjuvant): Typically 1 year of treatment (approximately 18 cycles of the three-weekly regimen), starting after completion of surgery and/or chemotherapy.
- Metastatic breast cancer: Treatment continues for as long as it remains effective and side effects are manageable. Your doctor will assess response regularly.
- Metastatic gastric cancer: Treatment continues for as long as clinical benefit is maintained.
Children
Zercepac is not recommended for patients under 18 years of age. There is insufficient clinical data on the safety and efficacy of trastuzumab in the pediatric population.
Elderly
No dose adjustment is required based on age alone. However, elderly patients may be more susceptible to cardiac side effects and should be monitored accordingly. The same dosing regimens used in younger adults apply to older patients.
Missed Dose
If you miss a scheduled dose of Zercepac, contact your doctor or treatment team as soon as possible to reschedule. Do not try to make up for a missed dose on your own. Your doctor will determine the appropriate timing and dose for your next infusion based on how long it has been since your last dose. Maintaining a regular treatment schedule is important for optimal effectiveness.
Stopping Treatment
Do not stop treatment with Zercepac without first talking to your doctor. All doses should be given at the correct time according to your dosing schedule (weekly or every 3 weeks). Premature discontinuation may reduce the effectiveness of treatment. If treatment must be stopped due to side effects (particularly cardiac problems), your doctor will continue to monitor your heart function even after treatment has ended, as Zercepac can remain in the body for up to 7 months.
To prevent medication errors, it is important to check the vial label to ensure that the medicine being prepared and administered is Zercepac (trastuzumab) and not a different product containing trastuzumab, such as trastuzumab emtansine (Kadcyla) or trastuzumab deruxtecan (Enhertu). These are different drugs with different indications, doses, and side effect profiles.
What Are the Side Effects of Zercepac?
Like all medicines, Zercepac can cause side effects, although not everyone gets them. Some side effects can be serious and may require hospitalization. Your healthcare team will monitor you closely, especially during and after infusions, and will perform regular blood tests and cardiac assessments throughout your treatment.
Serious Side Effects
During or after a Zercepac infusion, you may experience chills, fever, and other flu-like symptoms. These are very common (affecting more than 1 in 10 patients) and occur mainly during the first infusion and the first few hours thereafter. Additional symptoms may include nausea, vomiting, pain, muscle tension and tremor, headache, dizziness, breathing difficulties, changes in blood pressure, altered heart rhythm (palpitations, flutter, or irregular heartbeat), facial and lip swelling, and skin rash. While these reactions are usually temporary, some can be severe and, in rare cases, fatal. You will be monitored for at least 6 hours after the first infusion and at least 2 hours after subsequent infusions.
Cardiac complications can occur during or after treatment and may be serious. They include weakening of the heart muscle potentially leading to heart failure, inflammation around the heart, and altered heart rhythm. Symptoms to watch for include shortness of breath (including at night), persistent cough, fluid retention (swelling in legs or arms), and palpitations. Tell your doctor immediately if you experience any of these symptoms.
A group of metabolic complications that can occur after cancer treatment, characterized by high levels of potassium and phosphate and low levels of calcium in the blood. Symptoms may include kidney problems (weakness, breathlessness, fatigue, confusion), heart problems (fluttering or abnormal heart rhythm), seizures, vomiting or diarrhea, and tingling in the mouth, hands, or feet. Report any of these symptoms immediately.
Side Effects by Frequency
Very Common
May affect more than 1 in 10 people
- Infections
- Diarrhea and constipation
- Heartburn (dyspepsia)
- Fatigue
- Skin rash
- Chest pain and abdominal pain
- Joint pain and muscle pain
- Low red blood cell and white blood cell counts
- Hair loss
- Nosebleeds and runny nose
- Eye inflammation (conjunctivitis) and watery eyes
- Tremor, dizziness, and hot flushes
- Weight loss and appetite loss
- Insomnia and taste changes
- Low platelet count and easy bruising
- Numbness or tingling in fingers and toes
- Mouth and throat sores
- Shortness of breath, headache, and cough
- Nausea and vomiting
- Nail changes
- Hand-foot syndrome (pain, swelling, redness in hands/feet)
Common
May affect up to 1 in 10 people
- Allergic reactions
- Throat infections and urinary tract infections
- Breast inflammation and liver inflammation
- Kidney effects
- Increased muscle tone (hypertonia)
- Pain in arms and/or legs
- Itchy skin rash and drowsiness
- Hemorrhoids and itching
- Dry mouth, dry skin, and dry eyes
- Excessive sweating
- Feeling weak and unwell
- Anxiety and depression
- Asthma and lung infection
- Back pain, neck pain, and bone pain
- Acne and leg cramps
Uncommon
May affect up to 1 in 100 people
- Deafness
- Bumpy skin rash
- Wheezing
- Lung inflammation or scarring
Rare
May affect up to 1 in 1,000 people
- Jaundice (yellowing of skin/eyes)
- Anaphylactic reactions (severe whole-body allergic reaction)
Not Known
Frequency cannot be estimated from available data
- Abnormal or impaired blood clotting
- High potassium levels
- Swelling or bleeding behind the eyes
- Shock
- Abnormal heart rhythm
- Respiratory distress and acute fluid accumulation in the lungs
- Acute airway narrowing
- Abnormally low blood oxygen levels
- Liver damage and kidney failure
- Facial and lip swelling
- Reduced amniotic fluid (in pregnant patients)
- Underdeveloped fetal lungs and abnormal fetal kidney development
Some side effects may be related to your underlying cancer. If you are receiving Zercepac in combination with chemotherapy, some of the side effects may also be attributable to the chemotherapy agents. It is important to report all new or worsening symptoms to your healthcare team.
Contact your doctor or seek emergency care immediately if you experience: severe difficulty breathing, chest pain, sudden swelling of the face or throat, signs of a severe allergic reaction (rash spreading rapidly, wheezing, dizziness, rapid pulse), or new/worsening symptoms of heart failure (increasing shortness of breath, inability to lie flat, swollen ankles, persistent cough).
How Should You Store Zercepac?
Zercepac is a hospital-administered medication that will be stored and prepared by trained healthcare professionals. You will not typically need to store this medicine yourself. However, the following storage information is provided for completeness:
- Unopened vials: Store in a refrigerator at 2°C–8°C (36°F–46°F). Keep in the original carton to protect from light.
- Reconstituted solution: Chemically and physically stable for 48 hours at 2°C–8°C after reconstitution with sterile water for injections. Must not be frozen.
- Diluted infusion solution: Stable for up to 84 days at 2°C–8°C, 7 days at 23°C–27°C, and 24 hours at 30°C in polyethylene or polypropylene bags containing 0.9% sodium chloride solution.
- Shelf life: Do not use after the expiry date printed on the outer carton and vial label (EXP). The expiry date refers to the last day of the stated month.
- Visual inspection: Do not use if the solution contains visible particles or appears discolored before administration.
Keep all medicines out of sight and reach of children. Do not dispose of medicines in wastewater or household waste. Ask your pharmacist about proper disposal of medicines no longer in use, as this helps protect the environment.
What Does Zercepac Contain?
Each vial of Zercepac contains the following:
| Vial Size | Reconstitution Volume | Final Concentration | Total Volume After Reconstitution |
|---|---|---|---|
| 60 mg | 3.0 ml sterile water | Approx. 21 mg/ml | 3.1 ml |
| 150 mg | 7.2 ml sterile water | Approx. 21 mg/ml | 7.5 ml |
| 420 mg | 20.0 ml sterile water | Approx. 21 mg/ml | 20.6 ml |
Inactive Ingredients (Excipients)
- L-histidine hydrochloride monohydrate – buffer to maintain pH
- L-histidine – buffer to maintain pH
- α,α-trehalose dihydrate – stabilizer (lyoprotectant)
- Polysorbate 20 (E432) – surfactant to prevent protein aggregation. Note: polysorbates may cause allergic reactions in susceptible individuals.
Appearance
Zercepac is a white to slightly yellowish freeze-dried powder supplied in a glass vial with a rubber stopper. Each carton contains 1 vial. After reconstitution with sterile water for injections, the solution should be colorless to slightly yellowish, clear, and essentially free of visible particles. The reconstituted solution is further diluted in a 250 ml bag of 0.9% sodium chloride solution (normal saline) for intravenous infusion. Glucose-containing solutions must not be used for dilution.
Marketing Authorization Holder
Accord Healthcare S.L.U., World Trade Center, Moll de Barcelona s/n, Edifici Est 6a planta, 08039 Barcelona, Spain. Further information about Zercepac is available on the European Medicines Agency website.
Frequently Asked Questions
Zercepac is a biosimilar to Herceptin. Both contain the same active substance—trastuzumab—and work in the same way by targeting the HER2 protein on cancer cells. Biosimilars are approved only after extensive comparative studies demonstrate that they are highly similar to the reference product in terms of quality, safety, and efficacy, with no clinically meaningful differences. Zercepac and Herceptin can be used interchangeably for the same indications. The main difference is that biosimilars are typically available at a lower cost, improving access to this important cancer treatment.
Treatment duration depends on the type and stage of cancer. For early breast cancer (adjuvant treatment), the standard duration is 1 year, which corresponds to approximately 18 cycles of the three-weekly regimen. For metastatic breast cancer and metastatic gastric cancer, treatment continues for as long as it remains effective and the side effects are manageable—this can range from several months to years. Your oncologist will regularly assess your response to treatment using imaging and clinical evaluations to determine the optimal duration.
Hair loss (alopecia) is listed as a very common side effect of Zercepac, affecting more than 1 in 10 patients. However, the degree of hair loss varies between individuals and is often more significant when trastuzumab is combined with chemotherapy (particularly taxanes like paclitaxel or docetaxel), as these chemotherapy drugs are themselves strongly associated with hair loss. When Zercepac is used as a single agent, hair loss tends to be milder. Hair typically begins to regrow after treatment ends.
Cardiac function is monitored using echocardiography (cardiac ultrasound) or a MUGA scan, which measures your left ventricular ejection fraction (LVEF)—the percentage of blood your heart pumps out with each beat. A normal LVEF is typically 55–70%. Assessments are performed before starting treatment, every 3 months during treatment, and for 2–5 years after treatment completion. If your LVEF drops significantly, your doctor may pause or discontinue treatment. The good news is that trastuzumab-related cardiac dysfunction is often reversible when detected early and managed appropriately.
There are no specific contraindications to vaccination with trastuzumab alone. However, if you are also receiving chemotherapy alongside Zercepac, your immune system may be suppressed, which could affect both the safety (particularly with live vaccines) and effectiveness of vaccinations. Inactivated vaccines (such as the flu vaccine or COVID-19 vaccines) are generally considered safe. Live vaccines should be avoided during chemotherapy. Discuss your vaccination needs with your oncologist, who can advise on timing and appropriateness based on your overall treatment regimen.
All information is based on the approved Summary of Product Characteristics (SmPC) from the European Medicines Agency (EMA), the FDA prescribing information, and peer-reviewed clinical trials including the HERA trial, the ToGA trial, and ESMO/NCCN clinical practice guidelines. All medical claims follow the GRADE evidence framework with Evidence Level 1A, the highest quality of evidence based on systematic reviews of randomized controlled trials. iMedic receives no pharmaceutical company funding.
References
- European Medicines Agency (EMA). Zercepac (trastuzumab) – Summary of Product Characteristics. Last updated 2026. Available from: EMA EPAR.
- U.S. Food and Drug Administration (FDA). Trastuzumab Prescribing Information. Revised 2025. Available from: FDA Drug Label.
- Cameron D, Piccart-Gebhart MJ, Gelber RD, et al. 11 years’ follow-up of trastuzumab after adjuvant chemotherapy in HER2-positive early breast cancer: final analysis of the HERceptin Adjuvant (HERA) trial. Lancet. 2017;389(10075):1195–1205. doi:10.1016/S0140-6736(16)32616-2.
- Bang YJ, Van Cutsem E, Feyereislova A, et al. Trastuzumab 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. Lancet. 2010;376(9742):687–697. doi:10.1016/S0140-6736(10)61121-X.
- Slamon DJ, Leyland-Jones B, Shak S, et al. Use of chemotherapy plus a monoclonal antibody against HER2 for metastatic breast cancer that overexpresses HER2. N Engl J Med. 2001;344(11):783–792. doi:10.1056/NEJM200103153441101.
- Piccart-Gebhart MJ, Procter M, Leyland-Jones B, et al. Trastuzumab after adjuvant chemotherapy in HER2-positive breast cancer (HERA). N Engl J Med. 2005;353(16):1659–1672. doi:10.1056/NEJMoa052306.
- Cardoso F, Kyriakides S, Ohno S, et al. Early breast cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Ann Oncol. 2019;30(8):1194–1220. doi:10.1093/annonc/mdz173.
- National Comprehensive Cancer Network (NCCN). NCCN Clinical Practice Guidelines in Oncology: Breast Cancer. Version 2.2026.
- World Health Organization (WHO). WHO Model List of Essential Medicines – 23rd List. Geneva: WHO; 2023.
- Jackisch C, Scappaticci FA, Heinzmann D, et al. Neoadjuvant breast cancer treatment as a sensitive setting for trastuzumab biosimilar development and target-mediated drug disposition. Clin Pharmacol Ther. 2015;97(5):454–462. doi:10.1002/cpt.73.
Editorial Team
This article was written and reviewed by the iMedic Medical Editorial Team, comprising licensed specialist physicians with expertise in oncology, breast surgery, gastroenterology, and clinical pharmacology.
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