AstraZeneca PLC (AZN.US) announced on Wednesday that its asthma medication Fasenra failed to control the rate of acute exacerbations in a late-stage study targeting patients with chronic obstructive pulmonary disease (COPD), marking a setback for the company's efforts to address this serious lung condition.

Fasenra represents AstraZeneca PLC's second best-selling respiratory and immunology drug. In the first half of 2025, the medication generated sales of $920 million, reflecting an 18% year-over-year increase.

The trial participants were current or former smokers receiving existing treatments who had experienced at least two acute exacerbations in the previous year. AstraZeneca PLC stated that Fasenra failed to achieve the primary endpoint compared to placebo in the study, adding that the company will analyze the complete study data to better understand the results.

Fasenra is a first-in-class IL-5Rα monoclonal antibody developed by AstraZeneca PLC. The drug has received approval in over 80 countries, including the United States, Japan, the European Union, and China, as an add-on maintenance treatment for severe eosinophilic asthma (SEA). It has also been approved in the United States and Japan for treating SEA in children and adolescents aged 6 years and older.

Additionally, the medication has gained approval in more than 60 countries for treating adult eosinophilic granulomatosis with polyangiitis (EGPA), while its indication for hypereosinophilic syndrome (HES) is currently under regulatory review.

Sharon Barr, an AstraZeneca PLC executive, commented: "COPD remains one of the leading causes of death globally and is a complex, heterogeneous disease. We will continue to advance other promising options in our development pipeline to address patients' unmet needs."

The company's other COPD treatments include its triple-combination inhaler Breztri Aerosphere and the investigational drug tozorakimab.

Meanwhile, AstraZeneca PLC announced that its rare disease drug Saphnelo successfully met the primary endpoint in a late-stage clinical trial, demonstrating significant reduction in systemic lupus erythematosus activity, a chronic autoimmune disease.