Amivantamab (Rybrevant; Rybrevant Faspro)

Amivantamab at a glance

Amivantamab is a bispecific antibody: it attaches to two targets, EGFR and MET. Rybrevant is a verified brand. The intravenous product goes into a vein. A different subcutaneous formulation goes under the skin; its US brand is Rybrevant Faspro, while European information calls it Rybrevant solution for injection. These products have different doses and preparation instructions. They are not interchangeable milligram for milligram.

Subcutaneous treatment contains hyaluronidase, which helps the medicine spread through tissue under the skin. It must not be given into a vein. Your team should confirm the formulation at each visit, particularly when treatment changes. This guide does not establish local brand availability or Indian approval.

Important concerns include administration reactions, skin and nail problems, lung inflammation and eye problems. Blood-clot prevention is particularly important when amivantamab is used with lazertinib. Many practical difficulties can be treated early; report changes rather than waiting until they become severe.

How amivantamab works

EGFR and MET are proteins involved in signals that help cells grow and survive. Certain changes in cancer cells can make these signalling pathways overactive. Amivantamab attaches to EGFR and MET on the outside of cells, interferes with their signalling and helps immune cells recognise and attack targeted cells.

It is a targeted monoclonal antibody, with immune-mediated actions. It is not a conventional chemotherapy drug or a checkpoint inhibitor. It may be prescribed alone or alongside another medicine; combining treatments does not make their instructions identical. The benefit and risks depend on your cancer's biology and your whole treatment plan.

Healthy tissues also use these proteins. This helps explain why a targeted treatment can affect skin, nails and other organs. Having side effects does not prove that treatment is working, and having few side effects does not prove that it is ineffective.

How the team decides whether it is suitable

The oncologist considers your diagnosis, molecular results, previous treatment, general health and applicable prescribing information. EGFR testing is central to selection. Relevant findings may include an exon 20 insertion, exon 19 deletion or exon 21 L858R substitution. These are different changes in the EGFR gene, not interchangeable descriptions.

Testing may use cancer tissue or a blood sample that looks for tumour-derived genetic material. Ask which result supports your prescription. A general description such as “EGFR positive” may not convey enough detail. Although the antibody also targets MET, this does not mean that any MET result alone establishes suitability.

Discuss previous lung inflammation, significant breathing problems, skin or eye disease, blood clots, bleeding and allergies. Severe organ impairment may require additional consideration because evidence is limited in some groups. The team also considers whether accompanying treatment changes your risks or monitoring needs.

Before treatment starts

Expect a review of symptoms, weight, examination findings and blood tests. These commonly include blood counts, kidney and liver function, salts and albumin, a blood protein that can fall during treatment. Your team arranges baseline cancer assessments and a plan for checking response. Pregnancy testing is needed when pregnancy is possible.

Bring a complete medicine list, including supplements, non-prescription painkillers, skin products and medicines from other clinics. Mention allergies to hyaluronidase or components of an injection, previous infusion reactions and any anticoagulant you already take. The subcutaneous US product must not be used with a known allergy to hyaluronidase or its ingredients.

Before the first appointment, obtain the premedication instructions and the preventive skin-care plan. Some intravenous steroid doses start at home two days beforehand. Check that you have the tablets and understand the timing. If a dose is missed or vomited, contact the unit for instructions before treatment rather than taking extra tablets yourself.

When lazertinib accompanies amivantamab, ask about blood-clot prevention before starting. Also keep your hospital's urgent oncology contact details available to you and your caregiver.

How treatment is given

Intravenous treatment

A nurse gives diluted Rybrevant through an intravenous line. The US label specifies a peripheral vein for the first two treatment weeks to help manage infusion reactions. The first week's dose is divided between two consecutive days. The initial appointments are long: the US label estimates about four to six hours for day one and six to eight hours for day two, before allowing for other appointment tasks or interruptions. Later infusions may be shorter if tolerated.

Doses depend on weight at the start and the accompanying treatment. For the every-two-week plan, examples are 1,050 mg for someone initially below 80 kg and 1,400 mg for someone at or above 80 kg. Treatment starts weekly for four weeks, with the first dose split, then continues every two weeks from week five. A chemotherapy-containing plan uses different doses and moves to every three weeks from week seven after the initial weekly phase. These are examples, not instructions to calculate your own dose.

Report pain, burning, swelling or leakage around the line immediately. Nurses monitor you for reactions and may stop or slow the infusion and give treatment. Do not try to tolerate symptoms silently to finish the appointment sooner.

Subcutaneous treatment

A trained professional injects the specific subcutaneous product into the abdomen. Each injection takes approximately five minutes. Some doses need more than one injection, so five minutes is not necessarily the total injection or appointment time. Premedication, assessment and observation also take time. Sites are rotated and damaged, bruised or inflamed skin is avoided.

The initial subcutaneous dose is not split across two days like the intravenous dose. For treatment alone or with lazertinib, current labels include weekly treatment for four weeks followed by either every-two-week or every-four-week treatment from week five. The every-four-week dose is larger: for example, the amivantamab component is 3,520 mg below 80 kg and 4,640 mg at or above 80 kg, compared with 1,600 mg and 2,240 mg respectively for the every-two-week schedule. Hyaluronidase is supplied with it.

A chemotherapy-containing subcutaneous plan uses different doses: treatment is given in weeks one, two, three and four, then at three-week intervals, with the next dose in week seven. US and European labels describe these phases differently but specify the same visit pattern. Follow your team's written calendar for the exact product. Do not change appointments by comparing another patient's schedule.

Medicines before treatment and observation

You receive an antihistamine and fever-reducing medicine before doses. Steroids are required for initial treatment and may be needed again after reactions or a prolonged interruption. The intravenous schedule includes additional dexamethasone tablets before the first infusion; that schedule must not automatically be copied to the subcutaneous product. Ask the nurse to check all doses already taken.

Treatment must take place where staff can manage serious reactions. There is no single observation duration suitable for everyone in the reviewed labels. Follow your unit's instructions, and tell staff before leaving if you feel unwell. Reactions can also occur after the appointment.

If you miss a visit, call promptly. Subcutaneous missed-dose rules have specific timing windows, particularly during the initial weekly period; the team decides whether to reschedule or skip that dose. Do not simply wait until the next calendar date. Vomiting does not remove an injected or infused dose, so it must not be replaced. Hospital pharmacy staff manage preparation and storage; this is not a self-injection medicine.

Monitoring and checking treatment response

At visits, describe breathing changes, rash, nail pain, bowel symptoms, swelling, eye problems and any difficulty managing daily activities. Blood tests can show changes before symptoms develop, including low albumin, altered liver tests, electrolyte changes or reduced blood counts. The timing depends on the combination and your previous results; there is no universal amivantamab-only blood-test timetable.

Scans and other assessments are arranged separately to evaluate cancer control. Feeling better is valuable, but does not replace these checks. Likewise, a temporary pause for a reaction does not automatically mean the cancer has worsened.

The team may delay, reduce or stop amivantamab because of toxicity. Confirmed treatment-related lung inflammation or a life-threatening reaction can require permanent discontinuation. Ask for a clear plan after any interruption, including which supportive medicines continue and when you should next be reviewed.

Common side effects and practical care

Rash, dryness and sun sensitivity

An acne-like rash, itching, dryness and cracking can occur. These changes may involve the face, scalp or other areas and can be painful or affect sleep and confidence. Report them early. Do not assume an acne-like rash should be treated with ordinary acne products, which may irritate the skin further.

Current US prevention instructions include a prescribed oral antibiotic, such as doxycycline or minocycline, during the first 12 weeks, followed by an antibiotic scalp lotion for the next nine months of treatment. Moisturiser that does not block pores is used on the face and body, excluding the scalp. A daily 4% chlorhexidine wash for hands and feet is also recommended. Your team should prescribe and explain the plan, including alternatives for allergies or intolerance; do not independently start antibiotics or apply antiseptic to the eyes or face.

Limit sun exposure during treatment and for two months afterwards. Use protective clothing, shade and broad-spectrum sunscreen. Prevention reduces risk but does not guarantee that a rash will be mild. Painful extensive redness, blistering, peeling or sores involving the mouth or eyes need urgent assessment.

Nail-fold problems

The skin around nails can become red, swollen, tender or infected, called paronychia. It may make walking, fastening clothes or using a phone difficult. Keep nails gently trimmed and avoid cutting or picking cuticles. Reduce friction from tight shoes and protect hands during wet work.

Tell the team about pain, discharge or spreading redness. A photograph can help show change between appointments, but should not delay urgent advice. Do not drain a painful swelling yourself. The team may prescribe treatment or arrange specialist skin care.

Mouth soreness and changes in eating

Mouth inflammation can make food or drinks uncomfortable. Use gentle mouth care and a soft toothbrush; choose softer foods and avoid foods that sting. Ask the team for an appropriate rinse or pain treatment. Report ulcers, suspected thrush or difficulty swallowing. If pain prevents drinking, obtain prompt advice rather than waiting for a scheduled visit.

Nausea, reduced appetite, diarrhoea or constipation may also occur, with patterns affected by partner medicines. Take prescribed supportive medicines as directed. Repeated vomiting, worsening loose stools, dizziness or reduced urine needs assessment for dehydration. Ask for dietetic help if eating or weight is deteriorating.

Swelling, low albumin and tiredness

Fluid may collect in the legs or other areas. Low albumin can contribute, but new swelling should not automatically be blamed on a blood result. Report its onset, whether it affects one or both legs and whether breathing has changed. Do not start water tablets or sharply change fluid intake yourself. One painful swollen leg may be a clot.

Fatigue and muscle or joint discomfort can interfere with normal life. Pace activities, allow rest and keep gently active when able. New severe weakness or a major change in exercise tolerance warrants review for treatable causes such as anaemia, infection or a clot.

Important serious side effects

Infusion, injection and allergic reactions

Symptoms include flushing, fever, chills, nausea, chest discomfort, breathlessness, light-headedness or faintness. Severe allergy may involve swelling of the lips, tongue or throat. Tell staff immediately during administration; they decide whether treatment can safely restart. Serious reactions remain possible with the under-the-skin formulation.

At home, follow the urgent plan given by the unit. Severe breathing difficulty, throat swelling or collapse is an emergency. Do not drive yourself or wait to see whether an antihistamine helps.

Lung inflammation

Amivantamab can cause interstitial lung disease or pneumonitis, meaning inflammation within lung tissue. New or worsening cough, breathlessness or fever needs immediate contact with the oncology team. Infection, a clot and other causes may produce similar symptoms, so assessment is essential. Do not assume the symptoms are simply the cancer or a minor cold. The team should withhold amivantamab while suspected pneumonitis is assessed and stop it permanently if confirmed.

Blood clots, particularly with lazertinib

A clot in a leg vein may cause one-sided swelling, pain, tenderness or warmth. A clot reaching the lungs can cause sudden breathlessness, chest pain or collapse. The combination with lazertinib has an important clot risk, and current prescribing information recommends preventive anticoagulation for the first four months. The prescriber then reviews whether it should continue.

Anticoagulants are sometimes called blood thinners. They reduce risk but do not eliminate it. The labels do not recommend vitamin K antagonists such as warfarin for this preventive strategy. If you already take warfarin or another anticoagulant, your clinicians must coordinate the plan; do not stop, replace or double it yourself. Report unusual bleeding, and seek urgent help for uncontrolled bleeding, black stools or vomiting blood.

Eye problems

Dry eyes, redness, blurred vision, light sensitivity or pain can occur. More serious inflammation or damage to the cornea, the clear front surface of the eye, needs specialist assessment. Contact the team promptly for new symptoms; pain or altered vision needs urgent assessment. Stop wearing contact lenses until assessed and do not use leftover steroid eye drops.

Blood-count and organ-function changes

Low blood counts and liver-test changes may occur, especially with accompanying treatments. Report fever, shivering, unusual bruising, bleeding, worsening breathlessness, jaundice or dark urine. Follow your team's infection instructions even if a temperature reading is not high. Serious illness can occur without fever.

When amivantamab is combined with lazertinib, liver injury can be severe. Current US partner guidance calls for liver enzymes and bilirubin before treatment and again as clinically indicated. Significant liver toxicity may require the team to withhold both medicines, then reduce or stop treatment according to recovery. Report jaundice or dark urine promptly rather than waiting for the next blood test.

Other medicines, supplements and vaccinations

Amivantamab is broken down differently from many cancer tablets, so the familiar food and enzyme-interaction rules for tablets should not simply be copied. Nevertheless, the full treatment plan needs a pharmacist's review. Lazertinib, anticoagulants, preventive antibiotics and chemotherapy can each add interactions.

Check before taking aspirin, ibuprofen, herbal products or supplements, particularly when using a blood thinner. Do not assume spacing two medicines apart removes an interaction. Tell the team before another clinician starts a new prescription.

Avoid live vaccines during amivantamab treatment in accordance with European product information. Ask about suitable non-live vaccinations, such as flu or COVID-19 vaccines, and the best timing. After treatment, timing depends on immune recovery and accompanying medicines rather than one universal waiting period.

Everyday life during treatment

Plan transport and practical support for the early visits. Antihistamines may make you sleepy, and fatigue, dizziness or eye symptoms can make driving unsafe. Avoid driving or operating equipment when affected. A shorter injection does not necessarily mean you can return immediately to demanding activities.

There is no amivantamab food-timing requirement because it is not swallowed. Eat and drink as your team recommends and follow separate instructions for tablets given alongside it. Ask about drinking alcohol if liver tests are abnormal or other medicines cause drowsiness.

Discuss travel early so appointments and preventive medicines remain organised. Maintain gentle activity as tolerated, but do not exercise through unexplained chest pain or breathlessness. Tell your dentist and other clinicians about treatment and anticoagulation before procedures. Support for visible skin changes, fatigue and emotional strain is part of cancer care; ask for it when needed.

Fertility, pregnancy and breastfeeding

Amivantamab may harm a developing baby. A pregnancy test should be arranged before treatment when appropriate. Patients who can become pregnant should use effective contraception during treatment and for three months after the last dose. Tell the team immediately about a suspected pregnancy.

The reviewed amivantamab labels do not provide a separate male contraception interval. Accompanying medicines may have specific instructions for patients or partners and may require longer precautions. Ask for one written plan covering the entire treatment, rather than applying amivantamab's interval to everything.

US information advises no breastfeeding during treatment and for three months afterwards. European information requires an individual decision about stopping breastfeeding or treatment without specifying the same post-treatment interval. Do not resume breastfeeding without an agreed plan. Human fertility effects are uncertain; discuss fertility preservation before starting if future parenthood matters to you.

After treatment finishes

Continue follow-up for ongoing skin, nail, eye or breathing problems. Symptoms that start after the final dose may still need prompt assessment. Maintain sun precautions for two months, and follow the contraception and breastfeeding plan.

Do not stop an anticoagulant or preventive medicine simply because an amivantamab visit has been cancelled. Ask which medicines continue, which stop and when each decision will be reviewed. Keep a record of any serious reaction and the exact formulation you received for future healthcare visits.

Frequently asked questions