Both have been shown to reduce blood eosinophil levels in asthma patients with potential efficacy in ABPA.106 A retrospective study of anti IL-5/5R treatment in patients with severe asthma with fungal sensitisation and ABPA showed a reduction in exacerbations in the ABPA subgroup.107 However, this study is limited by the small patient numbers in the ABPA subgroup (N = 9) and large randomised controlled trials are required to definitively understand the utility of anti-IL-5 therapy in ABPA. The gene discussed is IL5; the disease is asthma.