Hertinib

Indications

Neratinib is a targeted cancer medicine used for HER2-positive breast cancer. It is used in adults with early-stage HER2-positive breast cancer after they have completed a year of Trastuzumab-based treatment (extended adjuvant therapy) to lower the chance of the cancer returning, and together with Capecitabine for advanced or metastatic HER2-positive breast cancer after earlier HER2-targeted treatments.

How It Works

Neratinib is a tyrosine kinase inhibitor. It binds permanently inside cancer cells to the HER1, HER2 and HER4 receptors, switching off the growth signals these receptors send. This slows or stops the growth of cancer cells that depend on HER2.

Dosage and Administration

The dose is set by your cancer specialist, as prescribed, and may be started low and increased over the first weeks to reduce diarrhoea. Tablets are taken once a day with food, at about the same time each day, swallowed whole. Your doctor will usually prescribe an anti-diarrhoea medicine (such as Loperamide) to take regularly during the first cycles. Do not change the dose or stop without talking to your specialist.

Interactions

• Proton pump inhibitors (such as Omeprazole) and H2 blockers: reduce absorption; avoid PPIs. If needed, H2 blockers or antacids must be separated from Neratinib as your doctor advises.
• Strong or moderate CYP3A4 inhibitors (Ketoconazole, Clarithromycin, Ritonavir, grapefruit juice): raise levels and side effects; avoid.
• CYP3A4 inducers (Rifampicin, Carbamazepine, Phenytoin, St John's Wort): lower its effect; avoid.
• Digoxin and Dabigatran (P-gp substrates): levels may rise.

Contraindications

• Allergy to Neratinib or any ingredient.
• Use with strong CYP3A4 inducers such as Rifampicin or St John's Wort.
• Severe liver impairment (in some guidance).

Side Effects

Diarrhoea is very common and can be severe, especially in the first month. Other common effects include nausea, vomiting, stomach pain, tiredness, rash, mouth sores, reduced appetite, muscle cramps and raised liver enzymes.

Get urgent medical help if you have severe or persistent diarrhoea (for example 4 or more extra stools a day despite medicine), signs of dehydration such as dizziness, very little urine or extreme thirst, fever with diarrhoea, yellow skin or eyes, dark urine, severe stomach pain, or signs of a severe allergic reaction.

Pregnancy and Lactation

Neratinib can harm an unborn baby. Women should use effective contraception during treatment and for at least 1 month after the last dose, and men with female partners for at least 3 months after. Do not breastfeed during treatment and for at least 1 month after the last dose.

Precautions and Warnings

Drink plenty of fluids and follow the diarrhoea plan your doctor gives you. Liver tests are checked regularly. Tell your doctor about all medicines, herbal products and indigestion remedies. Report any new symptom promptly, as the dose may need to be paused or reduced.

Overdose

Overdose is likely to cause severe diarrhoea, nausea, vomiting and dehydration. Seek medical help at once.

Therapeutic Class

Antineoplastic, HER2 tyrosine kinase inhibitor (targeted therapy).

Storage

Store below 30°C in a dry place, in the original container with the desiccant, away from light and out of the reach of children.