Cambridge, UK, September 8, 2026
AstraZeneca has reported detailed results from the Phase III OBERON and TITANIA trials showing that tozorakimab significantly reduced moderate-to-severe COPD exacerbations across a broad population of patients who continued to experience exacerbations despite inhaled standard-of-care treatment. The findings, presented at the European Respiratory Society (ERS) Congress 2026 and simultaneously published in the New England Journal of Medicine, strengthen the clinical profile of the investigational IL-33-targeting biologic and support its potential as a new treatment option for patients with chronic obstructive pulmonary disease.
Tozorakimab Delivers Consistent Phase III COPD Results
The OBERON and TITANIA trials together randomized 2,306 patients with symptomatic COPD who had experienced at least two moderate or one severe exacerbation during the previous year. Participants received tozorakimab 300 mg once every four weeks or placebo for 52 weeks on top of inhaled maintenance therapy. The studies evaluated patients irrespective of blood eosinophil count and included both current and former smokers across different levels of lung-function impairment. In the primary population of former smokers, tozorakimab reduced the annualized rate of moderate-to-severe COPD exacerbations by 29% in OBERON and 34% in TITANIA compared with placebo. In the broader population of current and former smokers, reductions were 30% and 29%, respectively. These findings are important because COPD is a heterogeneous disease, and treatment effects can vary according to inflammatory biomarkers and smoking history. A pooled analysis further showed reductions across all prespecified patient subgroups, including different blood eosinophil levels. Patients with baseline blood eosinophils below 150 cells/µL experienced a 23% reduction in moderate-to-severe exacerbations, while reductions reached 34% among patients with eosinophil counts of at least 150 cells/µL and 43% among those at or above 300 cells/µL.
IL-33 Targeting May Address Inflammation and Mucus Dysfunction
Tozorakimab is an investigational monoclonal antibody targeting interleukin-33 (IL-33). AstraZeneca is developing the therapy to inhibit signaling from both reduced and oxidized forms of IL-33, with the objective of addressing inflammatory pathways as well as the mucus dysfunction associated with COPD progression. An additional integrated analysis presented at ERS 2026 showed that tozorakimab reduced mucus plug scores in a broad COPD population. Mucus plugs are an emerging measure associated with poorer COPD outcomes, making the finding potentially relevant to understanding how IL-33 inhibition could influence multiple disease mechanisms. However, these findings should be distinguished from the trials’ primary exacerbation endpoint. The treatment was generally well tolerated, with a favourable safety profile reported across the studies. AstraZeneca identified injection-site reaction as the only adverse drug reaction reported for tozorakimab in the full results.
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FDA Priority Review Supports Regulatory Progress
The positive OBERON and TITANIA findings come as AstraZeneca advances tozorakimab through regulatory review. The company’s Biologics License Application (BLA) for 300 mg administered every four weeks as an add-on maintenance treatment for adults with COPD has been accepted by the US FDA for Priority Review. The Prescription Drug User Fee Act date is anticipated in the first quarter of 2027. The therapy is also under regulatory review in major markets including the European Union and China. Tozorakimab remains investigational for COPD and is not yet approved for this indication. The broader development program also includes studies in severe asthma and severe viral lower respiratory tract disease. The Phase III OBERON and TITANIA results therefore represent an important milestone for AstraZeneca’s respiratory pipeline, particularly because the treatment demonstrated efficacy across a broad COPD population rather than being restricted to a narrowly defined biomarker group.
Source: AstraZeneca press release
