**6.2 Quilizumab**

Quilizumab is a humanized, afucosylated, monoclonal IgG1 antibody, that binds membrane-bound IgE on B cells at the M1-prime segment, which is absent in soluble IgE (**Table 1**). In healthy volunteers and patients with allergic rhinitis or asthma, this anti-IgE antibody resulted able to reduce the total and specific IgE serum levels for at least 6 months after the last dose [110, 111]. This may implicate that quilizumab affects long-term IgE memory and bears the capacity for a sustained effect compared to omalizumab. Regarding quilizumab, there is no published evidence about its effect on angioedema and only one clinical trial is currently ongoing (NCT01987947) in CU. A previous randomized trial of quilizumab in adults with refractory CSU revealed that, although it reduced median serum IgE levels by approximately 30% over 20 weeks, it did not cause clinically relevant effects as assessed by ISS7 and UAS7 [112]. The study investigators hypothesized that the remaining serum IgE may be produced by long-lived IgE plasma cells that are not targeted by the drug due to their lack of membrane IgE.
