The currently approved add-on biological treatments for severe asthma include anti-IgE treatment for severe allergic asthma (omalizumab), anti-IL5 or anti-IL5R for severe eosinophilic (mepolizumab, benralizumab, and reslizumab), and anti-IL4R for severe eosinophilic/Type 2 asthma or patients requiring maintenance OCS asthma (dupilumab) (Table 6). Here, IL4R is linked to asthma.