Personalized omalizumab treatment improves clinical benefit in patients with chronic spontaneous urticaria.

Omalizumab is a humanized anti-IgE mAb that was found to be highly efficacious in several randomized clinical trials, which led to licensing for chronic spontaneous urticaria (CSU) by the US Food and Drug Administration in 2014.1-3 Omalizumab targets free IgE at the site of the Fc region of IgE (FcεRI), which prevents free IgE from binding to the high-affinity receptor FcεRI on mast cells and basophils. Possible mechanisms of action in patients with CSU include neutralization of IgE autoantibodies in socalled ‘‘autoallergic’’ patients and the gradual downregulation of the FcεRI receptor in so-called ‘‘autoimmune’’ patients who have IgG antibodies directed against the high-affinity receptor FcεRI.4,5