Omalizumab (CRSwNP)

How it works

Omalizumab is a humanised monoclonal antibody that binds free immunoglobulin E (IgE), preventing it from binding its high-affinity receptor on mast cells and basophils and thereby reducing the type-2 allergic inflammation that drives polyp formation.

Prescribing in practice

• Anaphylaxis can occur, sometimes with a delayed onset, so doses are given under supervision with resuscitation facilities and an observation period after injection.
• It is add-on therapy and not for acute symptom relief; dosing is determined by baseline IgE level and body weight.
• It should be initiated and reviewed by a specialist against agreed CRSwNP access criteria, with intranasal corticosteroids continued.

Monitoring

Observe patients after injection for hypersensitivity, and review nasal obstruction, polyp size and symptom scores at defined points to confirm continued benefit.

Counselling the patient

• This is a long-term add-on treatment, not a reliever for sudden symptoms.
• Keep using your steroid nasal spray unless advised otherwise.
• Seek urgent help for any signs of a severe allergic reaction such as breathing difficulty, swelling or faintness, which can occur some hours after the injection.

Evidence & guidelines

Omalizumab is licensed for severe CRSwNP on the basis of randomised trials demonstrating reduced polyp size and nasal congestion, and is positioned by NICE for specialist add-on use.