Pemigatinib (Pemazyre)

Medicine at a glance

Pemigatinib, also known by the verified brand Pemazyre, is a targeted medicine taken as tablets. It blocks growth signals involving proteins called fibroblast growth factor receptors, or FGFRs. A suitable gene test result is important when the team considers this treatment.

The usual starting dose is 13.5 mg once daily, but your prescribed dose may be lower. Many people take it for 14 days followed by seven days without treatment. A different, continuous schedule is used in some specialist plans. Follow your own written calendar.

Tablets can be taken with or without food. They must be swallowed whole. Regular blood tests, particularly phosphate measurements, and specialist eye examinations are central to safe treatment. Feeling well does not mean these checks can be skipped.

What pemigatinib is and how it works

FGFR proteins help cells receive instructions about growth and survival. Certain gene changes can keep these signals unusually active. Pemigatinib interferes with the activity of FGFR1, FGFR2 and FGFR3, which may slow or shrink disease that depends on these signals.

A gene fusion means that parts of two genes have joined together. A rearrangement is a change in the usual organisation of genetic material. These findings can be important to treatment selection, but different FGFR changes are not interchangeable. Your team interprets the actual laboratory report.

Healthy tissues also use FGFR signals. Their disruption helps explain effects on phosphate balance, the eyes, nails and skin. “Targeted” does not mean side-effect free. Treatment aims and the likely benefits depend on your situation; a matching test does not guarantee a response.

How the team decides whether it is suitable

Your oncologist considers the diagnosis, relevant molecular results, previous treatment, symptoms, general health and applicable prescribing information. An FGFR2 fusion or rearrangement may guide one treatment plan, while an FGFR1 rearrangement is relevant to certain specialist blood or bone-marrow plans. This distinction can also change the dosing calendar.

Ask which result supports your prescription and how it was tested. Tissue or other samples may be needed, and a result from a broad gene panel may require further interpretation. An FGFR alteration found on a report does not automatically mean pemigatinib is appropriate.

The team also weighs existing retinal disease, kidney or liver problems, ability to swallow tablets and interacting medicines. Severe kidney or liver impairment can require a lower dose. Discuss the planned goal of treatment and what would lead to a pause, dose reduction or change.

Before treatment starts

Tell the team about eye disease, previous retinal detachment, changes in vision, diabetes-related eye problems, kidney or liver disease, and current digestive symptoms. Bring all medicines and supplements, including those bought without a prescription. Mention medicines for reflux, infections, seizures, heart disease and blood thinning.

Baseline assessment includes blood tests and a comprehensive eye examination with optical coherence tomography, usually shortened to OCT. This scan shows the layers at the back of the eye. It can detect changes before you notice a problem. A pregnancy test is needed if you could become pregnant.

Get a written dose calendar and hospital contact number. Check whether you have a planned seven-day break, when blood tests and eye visits are due, and who will advise about phosphate results. If phosphate-lowering medicines are prescribed, request instructions for both treatment days and break days.

How pemigatinib is taken

Dose and treatment calendar

Pemazyre tablets come in 4.5 mg, 9 mg and 13.5 mg strengths. Take the prescribed daily dose at about the same time, with or without food. Swallow the tablets whole with water; do not split, crush, chew or dissolve them. Contact the pharmacy if swallowing becomes difficult. Do not improvise a feeding-tube method.

The common intermittent schedule is 14 daily doses followed by seven days without pemigatinib, making a 21-day cycle. Current US information also describes daily treatment without a planned break for selected FGFR1-rearranged blood or bone-marrow disease. The seven-day break must not be added to a continuous plan without instructions.

Treatment continues while its benefit and tolerability justify it. Your team may delay the next cycle, temporarily stop treatment or reduce the dose after blood tests or side effects. A changed dose is a safety adjustment, not proof that treatment has stopped working.

A late or missed dose

If you remember less than four hours after the scheduled time, take the missed dose. If it is four hours or more late, skip it and take the next scheduled dose at the usual time. Do not double up. This follows the professional prescribing instructions; contact your pharmacist if the wording in your supplied leaflet differs.

If you vomit after a dose, do not take a replacement. Take the next dose when it is normally scheduled. Do not use a planned rest day to make up a missed or vomited tablet. Repeated vomiting needs medical advice because of dehydration and mineral disturbances.

Monitoring and checking whether treatment is working

Blood tests follow phosphate and other minerals, kidney and liver function, and blood counts as appropriate to your treatment. Phosphate can rise early, so keep the initial appointments even if you have no symptoms. The frequency increases if results become abnormal.

The recommended eye schedule is a comprehensive examination including OCT before treatment, every two months during the first six months, then every three months. New visual symptoms require urgent assessment between visits. After a retinal problem, closer follow-up is needed; US information specifies reassessment every three weeks until resolution or treatment discontinuation.

Creatinine, a blood marker often used to assess kidneys, can rise because pemigatinib changes how the kidneys handle that marker. This does not always mean filtration has worsened. However, true kidney injury and dehydration can also occur. The team may use other tests to clarify a persistent rise. Never dismiss reduced urine or severe thirst as “just the blood test”.

Scans, examination, symptoms and relevant disease-specific blood or bone-marrow tests help assess benefit. Ask when the first assessment is planned and which findings will guide the next decision. Side-effect severity is not a reliable measure of how well treatment is working.

Common side effects and practical management

Changes in phosphate

Phosphate is a mineral needed by cells and bones. Pemigatinib commonly raises its level in the blood; low levels can also occur, including during treatment for high phosphate. Either change may be silent, which is why blood tests matter.

Your team may recommend a lower-phosphate diet and a medicine that reduces phosphate absorption. Do not remove whole food groups without dietetic advice: maintaining protein and energy intake remains important. Check nutritional drinks, mineral supplements and antacids with the pharmacist.

US prescribing guidance introduces dietary measures when phosphate is above 5.5 mg/dL and phosphate-lowering treatment, with weekly blood checks, above 7 mg/dL. These are clinician decision points, not instructions to adjust tablets yourself. More severe or persistent changes can require a pemigatinib pause or reduction.

Phosphate-lowering treatment may need to change during a seven-day break or when phosphate becomes low. Ask for a written plan rather than automatically continuing the same binder and diet through every break. Report cramps, tingling around the mouth, unusual weakness or confusion promptly.

Mouth, taste and appetite

Mouth ulcers, dryness and changes in taste can make eating uncomfortable. Use a soft toothbrush, keep your mouth clean and ask about suitable rinses and pain relief. Softer, moist foods may be easier to manage. Report ulcers or soreness that reduce eating or drinking; white patches can need assessment for infection.

Diarrhoea, constipation and sickness

Ask in advance which bowel and anti-sickness medicines you should use. For diarrhoea, follow the team's fluid advice and contact them if it persists, worsens or is accompanied by fever, blood, dizziness or reduced urine. Repeated vomiting or inability to keep fluids down needs prompt assessment. Constipation may require a laxative; severe abdominal pain or vomiting should not be managed with extra laxatives alone.

Nails, skin and hair

Nails can become brittle, discoloured, painful or lift away from the nail bed. Keep them short, protect your hands during wet work and avoid trauma to the cuticles. Contact the team promptly for redness, swelling or discharge around a nail, which can indicate infection. Ask for help before walking or hand use becomes difficult.

Dry skin and painful palms or soles can occur. Regular moisturising, comfortable footwear and reducing friction may help. Hair thinning or loss and eyelash changes can affect confidence; discuss practical support. New painful lumps or dark skin patches need urgent assessment rather than routine moisturiser alone.

Tiredness and discomfort

Fatigue, joint or back pain can interfere with daily life. Balance activity with rest and ask which pain medicines are safe with your prescription. Report a marked change rather than assuming it is expected; anaemia, dehydration or mineral changes may contribute.

Less common but important side effects

Retinal changes and vision

Pemigatinib can cause fluid-related separation involving layers at the back of the eye. US information describes retinal pigment epithelial detachment; European information uses the term serous retinal detachment. These problems may be found on a scan before symptoms develop.

Report blurred vision, flashes, floaters, black spots or any new visual disturbance immediately, and obtain advice before taking another dose. The eye specialist and oncology team decide whether treatment can continue, needs a pause or should stop. Do not restart after an eye-related interruption until they advise you.

Dry eyes are also common and may benefit from recommended lubricating drops. Do not assume new blurring is simply dryness. Eye pain or a red, light-sensitive eye also needs prompt assessment. Sudden loss of sight or a curtain-like shadow across vision is an emergency.

Mineral deposits and painful skin damage

Persistently high phosphate can allow calcium-phosphate deposits to form in soft tissues. Serious skin damage called calciphylaxis has been reported, including in people without advanced kidney disease. Report hard lumps, painful patches, ulcers or darkening skin immediately. Severe pain, blackened skin or an open wound needs urgent medical assessment.

Severe mineral disturbance or dehydration

Markedly low phosphate or sodium can affect muscles, thinking and other body functions. New confusion, a seizure, collapse or severe weakness requires urgent care. Vomiting and diarrhoea can add to these problems. Do not attempt to correct abnormal results yourself with salt, phosphate, calcium or high-dose supplements.

Other medicines, supplements and vaccinations

Pemigatinib is affected by an enzyme called CYP3A. Some medicines raise its concentration and side-effect risk; others lower exposure and may reduce benefit. Examples include certain antibiotics, antifungals and seizure medicines, and rifampicin. Avoid grapefruit and St John's wort.

US information advises avoiding strong or moderate CYP3A inhibitors and reducing pemigatinib if they cannot be avoided. European dose-adjustment instructions specifically address strong inhibitors. Do not apply a dose change found online: the pharmacist must check the exact medicine and prescribing information.

Stomach-acid medicines need particular attention. European information advises avoiding proton pump inhibitors, such as omeprazole or esomeprazole. US information does not impose the same restriction. Ask the team to select your reflux treatment; simply separating doses does not establish that a proton pump inhibitor is suitable.

European information also advises at least six hours between pemigatinib and certain medicines with a narrow safety margin carried by a protein called P-gp. Examples include digoxin, dabigatran and colchicine. This is not a universal spacing rule for all medicines or all regional labels. Obtain an individual timetable and never stop an anticoagulant yourself.

Check supplements, herbal remedies and any newly prescribed medicine before starting them. Discuss vaccination with the oncology team, who will consider blood counts, accompanying treatment and vaccine type. Do not assume every vaccine is prohibited or that every vaccine is appropriate during treatment.

Everyday life during treatment

Use a calendar or alarm to track both doses and rest days. Record missed doses and changes authorised by the team. Keep tablets in their original packaging, away from children, moisture and excessive heat, and follow the storage instructions supplied with your product. Return unused medicine to the pharmacy.

A symptom diary can help connect visual changes, bowel symptoms or nail pain with treatment dates. Do not wait to fill it in before reporting something urgent. Arrange transport if vision changes or fatigue make driving unsafe.

Discuss work, exercise and travel around the blood-test and eye-appointment schedule. Carry your medication list and enough medicine in its labelled pack. Before travel, know how to access urgent eye care and oncology advice. Ask a dietitian to fit any phosphate restriction around foods you normally eat and enjoy.

Tell your dentist and other healthcare professionals that you are taking pemigatinib before procedures or new prescriptions. Keep routine mouth care gentle, and report a dental infection or persistent mouth pain early.

Ask for support if changes in appearance, fatigue or worry affect sleep, relationships or intimacy. Comfortable activity and everyday contact with others are usually possible; follow any specific infection precautions related to low blood counts or other treatment. You do not have to manage practical and emotional difficulties alone.

Fertility, contraception, pregnancy and breastfeeding

Pemigatinib can harm an unborn baby. If you could become pregnant, use effective contraception throughout treatment and for one week after the final dose. Men with a partner who could become pregnant also need effective contraception during treatment and for at least one week afterwards. US counselling information also applies this precaution when the partner is already pregnant; discuss suitable barrier protection with the team. Contact the team promptly if pregnancy occurs or is suspected.

European information advises a barrier method, such as condoms, as a second contraceptive method because the effect on contraceptive metabolism and effectiveness has not been studied. This is a precaution about uncertainty, not proof that every hormonal contraceptive fails. US information does not state the same additional-barrier requirement; agree an appropriate plan with your team.

Do not breastfeed during treatment or for one week after the final dose. Human fertility effects are uncertain. If future parenthood matters to you, discuss preservation options before starting where feasible. Treatment-related changes in periods or fertility do not remove the need for contraception.

If another medicine in your plan requires a longer precaution period, that period still applies. A planned seven-day pemigatinib break is part of treatment and is not a window to stop contraception or resume breastfeeding.

After treatment finishes

Agree when blood tests and eye follow-up will continue. Phosphate-lowering medicines and diet restrictions need reassessment as pemigatinib's effects change; do not continue them indefinitely without a plan. Eye problems may need ongoing specialist review even after the tablets stop.

Keep reporting persistent or new symptoms. Ask which medicines to continue, return unused tablets and retain your treatment summary. The one-week reproductive and breastfeeding precautions apply after the actual final dose, with longer requirements from other medicines followed where relevant.

Frequently asked questions