[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Antineoplastic monoclonal antibodies](https://durgical.com/en/pharmacology/classes/antineoplastic-monoclonal-antibodies/) › Panitumumab # Panitumumab ## Antineoplastic monoclonal antibodies? Antineoplastic monoclonal antibodies ## 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; effective contraception is used during treatment and for a short time after, and breastfeeding is avoided for the same period. Fully human anti-EGFR antibody for metastatic colorectal cancer without RAS mutations. Rash is nearly universal; magnesium falls. Updated Nov 1, 2026 ## Quick facts **Group** [Antineoplastic monoclonal antibodies](https://durgical.com/en/pharmacology/classes/antineoplastic-monoclonal-antibodies/) **Target** Epidermal growth factor receptor (EGFR, HER1), extracellular domain III **Key effects** Acne-like rash · Sensitivity to sunlight · Tiredness **Monitor** Magnesium and calcium before · Skin **ATC** L01FE02 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 ◎**Epidermal growth factor receptor (EGFR, HER1), extracellular domain III**Panitumumab ⓘ The crystal shows the panitumumab Fab bound to domain III of human EGFR, the domain that binds EGF. **Target in 3D:** Epidermal growth factor receptor (EGFR, HER1), extracellular domain III. PDB structure 5SX4 (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/5SX4) · Drag to rotate · pinch to zoom Panitumumab is a fully human IgG2 antibody that binds domain III of the EGFR outside the cell. It blocks EGF and related growth factors from binding, so the receptor's growth signals stop. When the tumour carries an activating RAS mutation, the signal is switched on further down the pathway and blocking the receptor does not help, which is why it is used only in RAS wild-type colorectal cancer. As an IgG2, it triggers immune killing (ADCC) less than cetuximab. - Panitumumab binds EGFR domain III - EGF cannot bind; the RAS–RAF–MAPK signal stops - Useless if RAS itself is mutated and always on ## Indications - Metastatic colorectal cancer without an abnormal RAS gene: first line with FOLFOX chemotherapy, or alone after fluoropyrimidine, oxaliplatin and irinotecan. [Colorectal cancer →](https://durgical.com/en/conditions/colorectal-cancer/) ## Adverse effects ### Common - Acne-like rash, dry or cracked skin, itching, nail-fold inflammation - Sensitivity to sunlight - Tiredness, nausea, vomiting, abdominal pain, constipation, diarrhoea - Mouth sores; longer eyelashes ### Serious (rare, important) - Severe skin reactions: blisters, peeling, painful ulcers, infection - Low magnesium and calcium: cramps, spasms, twitching - Severe infusion reactions - Interstitial lung disease - Eye inflammation with pain or light sensitivity; dehydration from diarrhoea ## Contraindications - Colorectal cancer with a RAS mutation (no benefit) ## Key interactions **Chemotherapy regimens (FOLFOX)** Intended combination in RAS wild-type disease; diarrhoea and dehydration add up. ## What is monitored - RAS testing of the tumour before starting - Magnesium and calcium before, during and after treatment - Skin, nails and eyes at every visit - Breathing symptoms and hydration ## Administration and safety - Slow intravenous infusion by a doctor or nurse; the patient is watched for infusion reactions. - The infusion is slowed or stopped for a reaction. ## Pregnancy and breastfeeding Avoid in pregnancy. Can harm the fetus; effective contraception is used during treatment and for a short time after, and breastfeeding is avoided for the same period. ## Nursing care - Teach skin care: moisturiser, sun protection with clothing, hat, sunglasses and sunscreen; report blisters, peeling or nail-fold swelling. - Ask about low magnesium or calcium, lung or kidney problems before starting. - Teach to report muscle cramps or twitching, eye pain or redness, new cough and signs of dehydration. - Confirm that a RAS test was done. ## Pharmacokinetics **Absorption** Intravenous infusion every two weeks. **Half-life** About 7.5 days (mean); its kinetics are non-linear. ## Memory aid PANItumumab: no RAS, no PANIc — it only works if RAS is normal. Rash means the drug is hitting EGFR; check the magnesium. ## Test yourself Think of the answer, then tap the question to see it. ## Which tumour test must be normal before panitumumab is used in colorectal cancer? RAS: it works only in RAS wild-type tumours. ## Which electrolyte typically falls with anti-EGFR antibodies? Magnesium (calcium may fall too). ## How does panitumumab differ from cetuximab in antibody type? Panitumumab is a fully human IgG2, which triggers immune cell killing less than cetuximab. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/panitumumab/) [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; effective contraception is used during treatment and for a short time after, and breastfeeding is avoided for the same period. ## Connections ## Related drugs 3 - [Cetuximab](https://durgical.com/en/pharmacology/cetuximab/) - [Fluorouracil](https://durgical.com/en/pharmacology/fluorouracil/) - [Irinotecan](https://durgical.com/en/pharmacology/irinotecan/) ## Related conditions 1 - [Colorectal cancer](https://durgical.com/en/conditions/colorectal-cancer/) [← Back to the class: Antineoplastic monoclonal antibodies](https://durgical.com/en/pharmacology/classes/antineoplastic-monoclonal-antibodies/) Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given. Sources: [Panitumumab Injection: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a607066.html) (MedlinePlus (U.S. National Library of Medicine), 2025); [Panitumumab - NCI](https://www.cancer.gov/about-cancer/treatment/drugs/panitumumab) (National Cancer Institute (U.S.), 2026); [Crystal Structure of panitumumab in complex with epidermal growth factor receptor domain 3.](https://www.rcsb.org/structure/5SX4) (RCSB Protein Data Bank, 2016). ## **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/panitumumab/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/panitumumab/