Cetuximab (Specialist drug)

How it works

It binds the extracellular domain of EGFR, blocking ligand binding and receptor activation and thereby inhibiting downstream signalling that drives tumour growth.

Prescribing in practice

• Severe infusion-related reactions, sometimes fatal, can occur particularly with the first infusion; give premedication and monitor closely during and after administration.
• It is effective only in RAS wild-type colorectal tumours, so RAS mutation status must be confirmed before use.
• Acneiform skin rash and hypomagnesaemia are very common and require management and electrolyte monitoring.

Monitoring

Monitor serum magnesium and other electrolytes during and after treatment, and observe closely for infusion reactions and skin toxicity.

Counselling the patient

• Report any rash, dry or cracked skin, and use emollients and sun protection as advised.
• Tell the team immediately if you feel unwell during an infusion, such as breathlessness, dizziness or a rash.
• Attend for blood tests to check your magnesium levels.

Evidence & guidelines

NICE has appraised cetuximab for RAS wild-type metastatic colorectal cancer and head and neck cancer, supported by randomised controlled trial data.