IL4 and asthma: In the meantime, other downstream effector cytokines, such as IL-4, IL-5, and IL-13, remain the current best available targets for biologic treatment of severe asthma with their associated biologics such as dupilumab, an IL-4 receptor antagonist, benralizumab, an IL-5R-binding antibody, reslizumab and mepolizumab, an IgG1 and an IgG4 neutralizing IL-5 antibody, and omalizumab, an anti-IgE antibody which binds to the Fc region of free IgE (173–175).