Abemaciclib [Specialist drug]

How it works

It inhibits CDK4 and CDK6, preventing phosphorylation of the retinoblastoma protein and arresting the cell cycle at the G1 phase to halt tumour proliferation.

Prescribing in practice

• Diarrhoea is very common and can be severe and lead to dehydration; manage promptly with antidiarrhoeal treatment, fluids and dose modification as needed.
• It can cause neutropenia and has been associated with venous thromboembolism and interstitial lung disease, requiring vigilance and treatment interruption when indicated.
• It is a CYP3A4 substrate, so review concomitant strong inducers or inhibitors and adjust according to the SPC.

Monitoring

Monitor full blood count, liver function and for signs of diarrhoea, thromboembolism and pulmonary symptoms during treatment.

Counselling the patient

• Start antidiarrhoeal treatment at the first sign of loose stools, increase fluids and contact your team if it does not settle.
• Report breathlessness, leg swelling or pain, or signs of infection promptly.
• Take it as a regular oral treatment and do not stop or change the dose without advice.

Evidence & guidelines

NICE technology appraisals support abemaciclib combined with endocrine therapy for advanced hormone receptor-positive, HER2-negative breast cancer.