Imatinib

How it works

It inhibits the BCR-ABL tyrosine kinase produced by the Philadelphia chromosome, and also KIT and PDGFR kinases, blocking the signalling that drives malignant cell proliferation.

Prescribing in practice

• Fluid retention and oedema, including pleural or pericardial effusion, can occur and may be serious, so monitor weight and watch for unexpected fluid accumulation.
• It is a CYP3A4 substrate and inhibitor, so review concomitant medicines for clinically important interactions.
• Myelosuppression and hepatotoxicity occur, requiring dose modification for significant cytopenias or deranged liver function.

Monitoring

Monitor full blood count, liver function and weight regularly, and assess molecular or cytogenetic response according to disease.

Counselling the patient

• Take it with food and a large glass of water to reduce stomach upset.
• Report rapid weight gain, swelling, breathlessness, bleeding or signs of infection.
• Avoid grapefruit juice and tell your team about any other medicines you take.

Evidence & guidelines

Imatinib transformed the management of chronic myeloid leukaemia following the IRIS trial and is recommended by NICE as first-line therapy.