The FDA has approved Astrazeneca plc and Amgen Inc.’s first-in-class biologic, tezepelumab, for the add-on maintenance treatment of adults and children ages 12 and older with severe asthma, adding further competition to a hotly contested market. An injection marketed under the brand name Tezspire, tezepelumab inhibits the action of thymic stromal lymphopoietin (anti-TLSP). This is a signaling molecule at the top of several cascades influencing allergic, eosinophilic and other types of airway inflammation associated with severe asthma, including airway hyperresponsiveness.