MEDI4212 is a humanized IgG1λ monoclonal antibody inhibitor targeting IgE. It effectively inhibits human IgE-mediated functional responses, such as calcium signaling, β-hexosaminidase release, and phagocytosis, through its receptor FcεRI. MEDI4212 prevents IgE from binding to CD23 with an IC50 of 8 nM and can be utilized in severe asthma research.