We read with interest the recent open labeled investigation with etanercept as add-on therapy in 15 patients with chronic severe asthma by Howarth and colleagues.¹ In these patients treatment with etanercept (25 mg administered subcutaneously twice a week for a period of 12 weeks) was associated with a substantial improvement in asthma symptoms, lung function, and bronchial hyperresponsiveness (BHR). The clinical improvement was measured by means of the Juniper asthma control questionnaire (ACQ) score; during treatment with etanercept the ACQ score fell considerably from a mean (range) of 26 (9–32) to 11 (4–27).

The most common adverse effects during treatment were respiratory tract infections (58.8%) and asthma exacerbations (52.9%). Ten of the 15 patients presented with respiratory tract infections associated with worsening of asthma control. The majority of asthma exacerbations are caused by acute respiratory viral infections, of which rhinoviruses are by far the most frequent,^2,3 but other respiratory pathogens are also important.^4,5 Immunosuppression induced by …