Adults and adolescents with severe, uncontrolled asthma treated with tezepelumab experienced fewer asthma exacerbations throughout all seasons of the year. Results from a placebo controlled multicenter study – NAVIGATOR– tested 1059 participants. The results showed that tezepelumab reduced the AAER by 63% in winter, 46% in spring, 62% in summer and 54% in patients as compared to the placebo. Jointly developed by Amgen and AstraZeneca, tezepelumab (branded as Tezspire) is a biologic drug for severe asthma that acts at the top of the inflammatory cascade by targeting thymic stromal lymphopoietin (TSLP). The drug was approved in the US in December.