The symptomatic benefit from asthma biologics is not sustained throughout the dosing schedule

<bold>Background:</bold> Biologic treatments (mAbs) for severe asthma reduce asthma exacerbations and improve asthma control. Many patients report a decrease in the symptomatic benefit of their mAb near the end of the dosing schedule. Using an anonymised online questionnaire, we investigated the frequency of this phenomenon, its management and if it varied by mAb. <bold>Results:</bold> 625 patients on SA mAbs were contacted, 269 (43%) responded (127 benralizumab, 100 mepolizumab, 31 omalizumab, 11 dupilumab). 68% (183/269) reported symptoms (increased breathlessness in 70%, tiredness in 54% and increased wheeze in 51%) pre-dose. This was most likely to occur a week before their next dose but 29% reported symptoms for 2 weeks. While increased symptoms were reported with all mAbs, it was significant for benralizumab (77% vs 23%, p<0.001), dupilumab (82% vs 18%, p=0.03) and 4-weekly omalizumab (79% vs 21%, p=0.004); but not mepolizumab (53% vs 47%). When comparing the eosinophil-targeting mAbs, more patients on benralizumab reported pre-dose symptoms compared to mepolizumab, p=0.001. 29% (53/183) reported needing oral steroids to alleviate symptoms- this did not differ by mAb type. <bold>Conclusion:</bold> Over two thirds of patients who responded to our survey reported a decrease in the symptomatic benefit of their mAb prior to the next dose; almost 30% reporting needing a course of steroids to manage these symptoms. More patients on benralizumab experienced increased symptoms compared to mepolizumab, this may be related to the longer dosing schedule of benralizumab. Future work should focus on biomarker and lung function assessment pre-dose to investigate if the reported symptoms are due to waning of the biological effect.