The cases reported by Grohé et al are interesting, but they need to be better debated.1 As far as we know, we were the first group to administer anti-IgE to a patient with Churg–Strauss syndrome (CSS) with asthma.2 3

In our patient, CSS had shown remission with systemic corticosteroid but he still presented with asthma which was difficult to control. The asthma did not improve despite the use of high-dose inhaled corticosteroids, long-acting β₂ agonists and several courses of steroid pulse therapy. Omalizumab was given and his asthma was controlled as well as could be expected, but a marked improvement in eosinophilia was also observed. The patient was not taking systemic corticosteroids or immunosuppressive agents at this time.

Besides the IgE blockage effect, studies have shown antiallergic and anti-inflammatory properties of anti-IgE, among which is the reduction in circulating and tissue eosinophils.4 On the other hand, there are at least three cases of temporal association between anti-IgE use and the development of CSS.5 CSS was probably caused by systemic steroid tapering in these cases, rather than anti-IgE use.

In the report by Grohé et al, it was not clear if the patients showed only improvement in respiratory symptoms or also in other CSS manifestations after introduction of anti-IgE. Moreover, at the time omalizumab was administered, the patients were also taking corticosteroids and immunosuppressives (all these drugs were acting).

Together, these cases suggest that omalizumab can be used in patients with CSS to treat and control asthma, but they also show that anti-IgE alone is not enough to control CSS activity. Systemic corticosteroids are the drug of choice to treat this disease.5

Although we are getting more evidence about the safety of omalizumab in patients with asthma and CSS, larger long-term studies are needed before the widespread use of anti-IgE can be recommended and also to verify if it is effective in the treatment of CSS.