In many severe asthmatics, eosinophils cause inflammation and airways 
hyperresponsiveness, resulting in frequent exacerbations, impaired lung 
function, and reduced quality of life. Interleukin-5 (IL-5) is a key cytokine 
for eosinophil growth, differentiation, recruitment, activation, and survival. 
Anti-IL-5-based therapies (mepolizumab and reslizumab are humanized monoclonal 
antibodies (hmAbs) that recognize free IL-5, benralizumab is a hmAb directed at 
the α subunit of the IL-5R) target the IL-5-signaling in eosinophilic asthma. 
Areas covered: The pharmacodynamic/pharmacokinetic profile of benralizumab and 
how it provided indications that permitted optimization of the design and 
timelines of the pivotal trials are described. Expert opinion: Benralizumab has 
the advantage over other anti-IL-5 therapies to target the IL-5Rα itself. 
Afucosylation enhances its interaction with its binding site and facilitates its 
pharmacological activity. Other benefits of benralizumab are fast (within 24 h) 
depletion of peripheral blood eosinophils, potent suppressive activity of bone 
marrow eosinophils and eosinophil precursors, tissue eosinophil apoptosis 
regardless of the presence of eosinophil survival factors and even at low IL-5R 
densities. The fact that benralizumab is dosed subcutaneously and is equally 
effective when given every eight weeks instead than every four weeks provides 
patients with convenience of self-administration and make it appealing for 
patients who dislike injections.