[A case of severe asthma responsive to omalizumab treatment despite a low serum IgE level and lack of sensitized allergens].

A 49-year-old female patient suffering from severe intractable asthma uncontrolled even with high-dose inhaled glucocorticosteroids (fluticasone 1000 μg/day+ciclesonide 800 μg/day), salmeterol inhaler (100 μg/day) and oral betamethasone (1 mg/day) was admitted to our hospital because of severe asthma attack. The total serum IgE level was low at 9 (IU/mL). Though perennial allergens was also negative, administration of 150 mg omalizumab was started in August 2009 with the patient's consent, resulting in noticeable improvements in asthma symptoms and the peak expiratory flow (PEF) were achieved. Due to her weight gain and general malaise, the drug was discontinued after the second administration, resulting in worsening of asthma symptoms. Omalizumab therapy was restarted in January 2010 and marked improvements in asthma symptoms and PEF were noted. The effects continued for approximately three weeks after administration. After the sixth administration, the dose of oral betamethasone successfully reduced to 0.5 mg/day. When comparing the six-month pre- and post-omalizumab therapy period, asthma-related events such as unscheduled hospital visits were also reduced, and the dose of oral betamethasone could also be reduced to 64% of the pre-therapy period after the omalizumab treatment. This case strongly suggests the therapeutic effect of omalizumab in the treatment of severe intractable asthma with low serum IgE level without identifiable allergens.