Neratinib (Specialist drug)

How it works

It irreversibly inhibits the HER2 and EGFR (HER1) receptor tyrosine kinases, blocking downstream signalling that drives tumour cell proliferation and survival.

Prescribing in practice

• Severe diarrhoea is very common and can cause dehydration and electrolyte disturbance; antidiarrhoeal prophylaxis should be initiated with the first dose and managed proactively.
• Hepatotoxicity can occur, so liver function should be checked at baseline and during treatment.
• It is metabolised by CYP3A4, so avoid concurrent strong CYP3A4 inhibitors or inducers and proton pump inhibitors as gastric acid reduction lowers absorption.

Monitoring

Monitor liver function tests during therapy and assess for diarrhoea and resulting dehydration at each review.

Counselling the patient

• Start the prescribed antidiarrhoeal medicine alongside treatment and report severe or persistent diarrhoea.
• Take with food and avoid antacid medicines unless advised by your specialist.

Evidence & guidelines

Approval was supported by the ExteNET trial demonstrating improved invasive disease-free survival in HER2-positive early breast cancer.