Introduction: No standardized response criteria exist to biologics in severe asthma. If incomplete, switching can be proposed.

Aims and objectives: To evaluate response to 4 different biologics and to describe withdrawals and switches.

Methods: 88 severe asthmatic patients treated with biologics (Omalizumab/OMA=41, Mepolizumab/MEPO=23, Benralizumab/BENRA=15, Dupilumab/DUPI=9) were recruited until July 2022. We defined patients ?Responder/R?, ?Partial Responder/PR? or ?Non Responder/NR? based on major/minor criteria.  Response was evaluated at year 3 for OMA/MEPO, 2 for BENRA and 1 for DUPI or at withdrawals/switches.

Results: R were 56,6 % OMA, 94,7% MEPO, 100 % BENRA and 88,8% DUPI. 17 of 88 patients (10 R, 3 PR,  4 NR) withdrew biologics for poor doctor-assessed efficacy, of which 7 switched to another agent. Other 6 patients switched after a full course of 5 years treatment. We observed: OMA to MEPO (n=3)/BENRA (n=2)/DUPI (n=3), 3 MEPO to DUPI and 2 BENRA to DUPI. 2 patients switched twice (MEPO to DUPI) and 1 switched 3 times (DUPI to BENRA), mostly for uncontrolled nasal polyposis.  After switching, patients were all R (n=15)/PR (n=1).  

Conclusions: Based on our retrospective criteria each biologic showed a high rate of success. OMA response was lower probably because of its first usage that limited the best eligibility based on personalized therapy. Response, despite ?criteria label?, should be evaluated ?case-by-case?. Switching aimed to reach a complete control on asthma symptoms/comorbidities and occurred mostly from anti-IgE to anti-IL-5/IL-5R/IL-4R? and from anti IL-5/IL-5R to anti-IL-4R?.