The purpose of this study is to investigate whether addition of Omalizumab enables a reduction in the dose of prednisone in patients with asthma and eosinophilic bronchitis.

This will be a double-blind placebo-controlled, 3-centre, randomized parallel group trial divided into two sequential study periods.

Period 1: After establishing the minimum dose of prednisone to maintain asthma control and maintain sputum eosinophils <3%, subjects will be randomized to either placebo or Omalizumab for 16 weeks (either once monthly for 4 months or every 2 weeks for 4 months).

Period 2: standardised prednisone reduction at intervals of 4-weeks until there is a clinical and eosinophilic exacerbation or bothersome steroid withdrawal effects. If patients have an exacerbation, they will be treated with prednisone. This patient will continue on Omalizumab or placebo during the entire duration of the study but not continue the phase of steroid reduction.

Inclusion criteria

1. Confirmed asthma within the past 2 years (12% bronchodilator reversibility or PC20 methacholine less than 8 mg/ml)
2. ACQ ≥1.5 and sputum eos ≥3% at the time of randomization
3. On ICS (≥ 1500 mcg fluticasone propionate or equivalent) with or without additional prednisone
4. Total serum IgE ≥30 IU/L and positive allergy skin prick test
5. Age between 18 and 75 years
6. Ability to provide informed consent

Exclusion criteria

1. Current smoker or ex-smokers with greater than 20 pack years
2. Co-morbid diseases which in the investigator's opinion would make the patient unsuitable to participate in the study
3. Currently on Omalizumab or has previously been treated with Omalizumab
4. Currently on other biologic therapies (eg. Prolia)
5. Pregnancy or lactation
6. Post bronchodilator FEV1 less than 50% predicted