Omalizumab

Question 1

What is omalizumab?

Answer 1

Recombinant humanised IgG1 monoclonal antibody that selectively binds to and decreases serum levels of free human IgE and down regulates the number of high affinity IgE receptors on mast cells, basophils and dendritic cells

Question 2

Indications for Omalizumab?

Answer 2

• Asthma
• Chronic spontaneous urticaria
• Off label: atopic dermatitis, eosinophilic granulomatosis with polyangiitis, bullous pemphigoid, mastocytosis

Question 3

PBS criteria for omalizumab?

Answer 3

Severe CSU
- symptoms for >6 weeks,
- UAS7 score ≥ 28, itch score >8

·        >12 years of age
·        Failed 2 weeks of standard treatment with:
	o   H1 antihistamine at maximally tolerated dose of PLUS
		·        H2 antihistamines 150mg BD
		·        Leukotriene receptor antagonist (montelukast 10mg daily)
		·        Doxepin up to 25mg TDS
·        Treated by dermatologist, immunologist or general physician, S100 hospital

Question 4

Omalizumab dosing

Answer 4

Subcutaneous injection of 300mg every 4 weeks,

can reduce to 150mg or increase to 450mg or 600mg

Question 5

Pregnancy category of omalizumbab?

Answer 5

Category B1

Excreted into breast milk to avoid in lactation

Question 6

Adverse effects of omalizumab?

Answer 6

Anaphylaxis (0.1-0.2% asthma patients, mostly within first 2 hours and in first dose) - need to observe in healthcare setting for at least the first 3 doses. Risk anaphylaxis up to 24 hours (60 mins TGA)
· Anaphylactoid reactions
· Injection site reactions in 10-15%
· Serum sickness-like reactions: fever, arthralgia, urticarial eruption, LAD, typically 1-5 days after administration
· URTI
· Headache
· Nasopharyngitis
· Arthralgias
· Gastroenteritis
· Parasitic infection/helminth
○ Thrombocytopenia
○ Can unveil Churg Strauss syndrome