AstraZeneca’s (LON:AZN) Fasenra (benralizumab) failures in chronic obstructive pulmonary disease (COPD) could be due to the antibody’s activity being limited to only those patients with an asthma-COPD overlap syndrome (ACOS) phenotype, where the drug’s use could be further explored, said experts.
In November 2017, Fasenra was approved to treat severe asthmatics with an elevated eosinophil count greater than or equal to 300cells/microliter. Earlier today, AstraZeneca announced that its second pivotal Fasenra study in COPD (TERRANOVA) failed to reach its primary endpoint, which mirrored a similar outcome of its first failed study (GALATHEA) on 11 May.
Based on responses seen in these pivotal studies with the similar agents approved in asthma and the proportion of ACOS phenotype patients present in other large COPD studies, experts suggested that Fasenra’s efficacy could be limited to those who also had underlying asthma, which could have contributed to the failure in the larger Phase III study. However, since multiple factors influence an ACOS phenotype, like smoking history and timing of onset of asthma, the identification of Fasenra responders using this phenotype still remains less than straightforward, they added.
Prior to these results, analysts had assigned a 40% chance of success for the studies, and a USD 1.3bn sales estimate for asthma and COPD. Since then, they have limited their optimism toward Fasenra’s role in asthma.