[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Antibody-drug conjugates (ADCs)](https://durgical.com/en/pharmacology/classes/antibody-drug-conjugates/) › Trastuzumab emtansine # Trastuzumab emtansine ## ADCs? Antibody-drug conjugates (ADCs) ## High alert? An error with this medicine can cause serious harm: double checks and protocols are used. ## Pregnancy: avoid? Avoid in pregnancy. Can harm the fetus (boxed warning); a negative pregnancy test is required and effective contraception is used during and after treatment. Trastuzumab joined to the microtubule poison DM1; used in HER2-positive breast cancer. Watch the liver, the heart and the platelets. Updated Nov 1, 2026 Also called: ado-trastuzumab emtansine, T-DM1 ## Quick facts **Group** [Antibody-drug conjugates (ADCs)](https://durgical.com/en/pharmacology/classes/antibody-drug-conjugates/) **Target** HER2 (ErbB2) receptor on tumour cells **Used for** Early HER2-positive breast cancer **Key effects** Fatigue · Nausea · Muscle and joint pain **Monitor** Liver tests before each dose · Heart function **ATC** L01FD03 No doses: the clinician sets them by the current guideline. On this page - The basics Mechanism of action - Indications - Adverse effects - Pharmacokinetics - Memory aid - Clinical What the labels mean - Safety Contraindications - Key interactions - What is monitored - Administration and safety - Pregnancy and breastfeeding - Nursing care - Study Test yourself - Connections Connections ## Mechanism of action ◎**HER2 (ErbB2) receptor on tumour cells**Trastuzumab emtansine ⓘ The cryo-EM structure shows the HER2 extracellular domain bound by trastuzumab (the antibody part of this conjugate) and pertuzumab; the DM1 payload is not in the structure. **Target in 3D:** HER2 (ErbB2) receptor on tumour cells. PDB structure 6OGE (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/6OGE) · Drag to rotate · pinch to zoom The antibody keeps trastuzumab's HER2 blockade and delivers DM1 (emtansine), a maytansine derivative attached to lysine residues. After binding HER2 the complex enters the cell by receptor-mediated endocytosis; proteases in the lysosome release DM1 into the cytosol, where it disrupts microtubules, arrests mitosis and triggers apoptosis. - Binds HER2 on the breast cancer cell - Taken in by endocytosis and digested in lysosomes - DM1 is released and disrupts microtubules - Mitotic arrest and apoptosis ## Indications - HER2-positive metastatic breast cancer previously treated with trastuzumab and a taxane. [Breast cancer →](https://durgical.com/en/conditions/breast-cancer/) - Early HER2-positive breast cancer with residual invasive disease after neoadjuvant treatment (adjuvant use). [Breast cancer →](https://durgical.com/en/conditions/breast-cancer/) ## Adverse effects ### Common - Fatigue, headache - Nausea, constipation, diarrhoea - Muscle and joint pain - Dry or watery eyes, blurred vision - Nosebleeds and easy bruising ### Serious (rare, important) - Serious or fatal hepatotoxicity (boxed warning) - Reduced left ventricular function and heart failure (boxed warning) - Embryo-fetal toxicity (boxed warning) - Thrombocytopenia and bleeding - Peripheral neuropathy - Infusion and allergic reactions ## Contraindications - Allergy to the drug or to trastuzumab - Caution in liver disease and heart disease ## Key interactions **Trastuzumab and trastuzumab deruxtecan** Different drugs: never substituted for one another. **Aspirin, anticoagulants and other drugs that raise bleeding risk** Bleeding is more likely when platelets are low. **Other liver-toxic medicines and grapefruit** May raise the risk of liver damage; they are discussed before use. ## What is monitored - Liver tests before each dose - Heart function (ejection fraction) before and during treatment - Platelet count - Signs of neuropathy - Confirmation that the tumour is HER2-positive before starting ## Administration and safety - Intravenous infusion only, never as a push; the first infusion is watched closely for reactions. - Check the full name: «trastuzumab» alone and the two trastuzumab conjugates are different drugs. - Hazardous drug: prepared and handled with chemotherapy precautions. ## Pregnancy and breastfeeding Avoid in pregnancy. Can harm the fetus (boxed warning); a negative pregnancy test is required and effective contraception is used during and after treatment. ## Nursing care - Check liver tests and platelets before each dose. - Observe the patient during and after the infusion for chills, fever or breathing difficulty. - Ask about swelling, breathlessness or palpitations (heart failure) and tingling in the hands or feet. - Teaching: report yellow skin, dark urine, black stools or unusual bleeding; use effective contraception. ## Pharmacokinetics **Absorption** Intravenous infusion every few weeks. **Elimination** The antibody part is catabolised like other proteins. ## Memory aid «T-DM1: Destroys Microtubules, watch 1-2-3»: 1 liver, 2 heart, 3 platelets. ## Test yourself Think of the answer, then tap the question to see it. ## What is the payload of trastuzumab emtansine and what does it target? DM1 (emtansine), a maytansine derivative that disrupts microtubules. ## What are the three boxed warnings of trastuzumab emtansine? Hepatotoxicity, cardiac toxicity (reduced ejection fraction) and embryo-fetal toxicity. ## In which early breast cancer setting is trastuzumab emtansine used? HER2-positive early breast cancer with residual invasive disease after neoadjuvant therapy. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/trastuzumab-emtansine/) [More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology) ## What the labels mean **High alert** An error with this medicine can cause serious harm: double checks and protocols are used. **Pregnancy: avoid** Avoid in pregnancy. Can harm the fetus (boxed warning); a negative pregnancy test is required and effective contraception is used during and after treatment. ## Connections ## Related drugs 2 - [Trastuzumab](https://durgical.com/en/pharmacology/trastuzumab/) - [Trastuzumab deruxtecan](https://durgical.com/en/pharmacology/trastuzumab-deruxtecan/) ## Related conditions 1 - [Breast cancer](https://durgical.com/en/conditions/breast-cancer/) [← Back to the class: Antibody-drug conjugates (ADCs)](https://durgical.com/en/pharmacology/classes/antibody-drug-conjugates/) Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given. Sources: [Ado-trastuzumab Emtansine Injection: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a613031.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [Ado-Trastuzumab Emtansine - NCI](https://www.cancer.gov/about-cancer/treatment/drugs/ado-trastuzumab-emtansine) (National Cancer Institute, 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=L01FD03) (WHO Collaborating Centre for Drug Statistics Methodology, 2026). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/pharmacology/trastuzumab-emtansine/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/trastuzumab-emtansine/