IL-5 receptor alpha (IL-5Rα / CD125); Fc region additionally engages

Class

Humanized afucosylated monoclonal antibody (IgG1 kappa)

Pathway

IL-5 / eosinophil survival and activation pathway (T2/eosinophilic inflammation) — depletes eosinophils via antibody-dependent cell-mediated cytotoxicity

Notes

original target text: IL-5 receptor alpha (IL-5Rα / CD125); Fc region additionally engages FcγRIIIa on NK cells (ADCC)

IL-5 receptor alpha (IL-5Rα, also called CD125) is a cell-surface receptor found mainly on eosinophils, a type of white blood cell, and to a lesser degree on basophils. It is one half of the receptor for interleukin-5 (IL-5), a signaling protein made by immune cells that controls how many eosinophils are produced, how long they survive, and how active they become. In diseases marked by "type 2" or eosinophilic inflammation—severe eosinophilic asthma, chronic rhinosinusitis with nasal polyps, hypereosinophilic syndromes—eosinophils accumulate in tissue and release damaging proteins that injure surrounding cells and drive symptoms. Rather than mopping up circulating IL-5, an antibody directed at IL-5Rα attaches to the receptor on the eosinophil itself. Because this particular antibody has been engineered to remove certain sugar groups (afucosylation), its tail region (Fc) binds more strongly to Fc receptors on natural killer cells, triggering a process called antibody-dependent cell-mediated cytotoxicity that actively destroys the eosinophil. This combination of receptor blockade and directed cell killing produces a deeper and faster reduction in eosinophil numbers than approaches that simply block the cytokine, which matters wherever eosinophil-driven inflammation underlies disease.