Background Omalizumab is an antibody used for the treatment of asthma with high blood levels of IgE (>76 IU/ml), as it is not expected to show much efficacy when levels are lower. In the first case The authors present, use of omalizumab was requested for a severe case of asthma with normal levels of IgE. It was also used in a case of persistent atopic dermatitis with high levels of IgE (800-900 IU/mL).

Purpose To evaluate the use of omalizumab beyond its approved indications and to discuss the results of the treatment in two off-label uses resistant to approved treatments.

Materials and methods Medical charts were reviewed and literature research was carried out for both cases in order to process the off-label approval. Clinical evolution was followed from the first administration of the antibody to present.

Results The first case was uncontrolled asthma secondary to Churg-Strauss vasculitis, with normal IgE levels and no allergic component (negative standard prick-test results and normal fraction of nitric oxide in exhalation). Omalizumab was prescribed at a dose of 150 mg every 4 weeks. After 4 doses, the vasculitis no longer caused symptoms; recurrent asthma flares continued, although not causing emergency episodes. In the second case, after adverse effects to all therapeutic options tried, off-label use of omalizumab was considered. After 450 mg every 15 days over a year, the patient had made satisfactory clinical progress with remission of the symptoms and normal serum levels of IgE.

Conclusions At present, the first patient is continuing treatment with omalizumab in order to need less emergency care, reduce oral corticosteroids and achieve a better quality of life. It was effective against the dermatitis and did not produce adverse effects. Neither of them developed anaphylaxis, the main adverse effect of the use of omalizumab.