US regulatory advisors are questioning the effectiveness of GlaxoSmithKline’s biologic Nucala as a treatment for patients experiencing a sudden worsening of COPD.

Nucala (mepolizumab) is a monoclonal antibody – already approved for asthma – that works by inhibiting interleukin-5 (IL5) to decrease the maturation and survival of eosinophils, overproduction of which can cause inflammation in the lungs.

However, in documents posted on the FDA’s website ahead of an advisory committee meeting later this week, agency staff highlighted difficulties in determining whether inhibiting IL5 is a relevant therapeutic approach for COPD, and queried whether GSK had enough efficacy data to back use of Nucala in this setting.