Asthma

In clinical studies, serum free IgE levels were reduced in a dose-dependent manner within 1 hour following the first dose and maintained between doses. Mean serum free IgE decrease was greater than 96% using recommended doses. Serum total IgE levels (i.e., bound and unbound) increased after the first dose due to the formation of omalizumab:IgE complexes, which have a slower elimination rate compared with free IgE. At 16 weeks after the first dose, average serum total IgE levels were five-fold higher compared with pre-treatment when using standard assays. After discontinuation of XOLAIR dosing, the XOLAIR-induced increase in total IgE and decrease in free IgE were reversible, with no observed rebound in IgE levels after drug washout. Total IgE levels did not return to pre-treatment levels for up to one year after discontinuation of XOLAIR.

Chronic Rhinosinusitis with Nasal Polyps

In clinical studies in chronic rhinosinusitis with nasal polyps (CRSwNP) patients, omalizumab treatment led to a reduction in serum free IgE and an increase in serum total IgE levels, similar to the observations in asthma patients. The mean total IgE concentrations at baseline were 168 IU/mL and 218 IU/mL in CRSwNP Trial 1 and 2, respectively. After repeated dosing every 2 or 4 weeks, with dosage and frequency according to Table 3, the mean predose free IgE concentrations at Week 16 were 10.0 IU/mL in CRSwNP Trial 1 and 11.7 IU/mL in CRSwNP Trial 2 and remained stable at 24 weeks of treatment. Total IgE levels in serum increased due to the formation of omalizumab-IgE complexes, which have a slower elimination rate compared with free IgE. After repeated dosing every 2 or 4 weeks, with dosage and frequency according to Table 3, mean and median predose serum total IgE levels at Week 16 were 3- to 4- fold higher compared with pre-treatment levels, and remained stable between 16 and 24 weeks of treatment.

IgE-Mediated Food Allergy

In a clinical study in patients with IgE-mediated food allergy, omalizumab treatment led to a reduction in serum free IgE and an increase in serum total IgE levels, similar to the observations in asthma patients. The mean total IgE concentration at baseline was 810 IU/mL. After repeated dosing every 2 or 4 weeks, with dosage and frequency according to Table 4, the mean pre-dose free IgE concentration at Week 16 was 10.0 IU/mL. Mean total IgE levels in serum increased about 2.4-fold due to the formation of omalizumab-IgE complexes, which have a longer half-life compared with free IgE.

Chronic Spontaneous Urticaria

In clinical studies in chronic spontaneous urticaria (CSU) patients, XOLAIR treatment led to a dose-dependent reduction of serum free IgE and an increase of serum total IgE levels, similar to the observations in asthma patients. Maximum suppression of free IgE was observed 3 days following the first subcutaneous dose. After repeat dosing once every 4 weeks, predose serum free IgE levels remained stable between 12 and 24 weeks of treatment. Total IgE levels in serum increased after the first dose due to the formation of omalizumab-IgE complexes which have a slower elimination rate compared with free IgE. After repeat dosing once every 4 weeks at 75 mg up to 300 mg, average predose serum total IgE levels at Week 12 were two- to three-fold higher compared with pre-treatment levels, and remained stable between 12 and 24 weeks of treatment. After discontinuation of XOLAIR dosing, free IgE levels increased and total IgE levels decreased towards pre-treatment levels over a 16-week follow-up period.