Mepolizumab eligibility in children with severe asthma – do we need paediatric specific criteria?

Background: Children > 6yr with poor asthma control despite maximally prescribed treatment have Problematic Severe Asthma. Detailed multidisciplinary team (MDT) assessment is key to phenotype children for identification of modifiable factors and consideration of licensed biological therapies (Omalizumab, Mepolizumab). We reviewed eligibility for biologics in a regional paediatric severe asthma centre in the UK. Methods: 67 patients on Steps 4-5 of GINA guideline therapies underwent protocol-based hospital, school and home MDT asthma assessment between 2015-2018. Medication adherence was assessed by electronic monitoring device (EMD). Spirometry, fractional exhaled nitric oxide (FeNO), blood tests for full blood count, IgE and aeroallergen sensitisation were performed. Results: Median age at assessment was 10.9 yr (range 6.0-15.8 yr). Male:Female - 40:27. Median inhaled steroid dose was 1000mcg Beclomethasone equivalent (range 400-2000mcg). 44 (66%) were on long-term oral steroids. Median FEV1 was 81% predicted (range 45-115%). Median FeNO was 37ppb (range 7-210ppb). 42 (63%) had adherence assessed by EMD. 35 (52%) were eligible for Omalizumab; 54 (80%) were eligible for Mepolizumab; 27 (40%) were eligible for both. There was no correlation between FeNO and peripheral eosinophil count in patients eligible for Mepolizumab (p=0.23). Conclusions: Surprisingly 80% children in our cohort fulfilled the criteria for Mepolizumab. The effect of interventions including improved medication adherence on peripheral eosinophil count is unknown. Due to resource implications, robust studies to identify paediatric-specific eligibility criteria and biomarkers predicting response to Mepolizumab should be explored.