Title: Do older patients with severe asthma respond to asthma biologics?

<bold>Background:</bold> Older patients with severe asthma (SA) often have more comorbidities and are at higher risk of treatment related side effects. Most phase 3 biologic (mAb) studies excluded patients ≥75 years. We therefore evaluated clinical outcomes in patients ≥75 years receiving mAb therapy at our centre. <bold>Methods:</bold> Retrospective review of all patients ≥75 years treated with mAb for SA between January ‘17 and August ‘23. Results are median (IQR). <bold>Results:</bold> Of 74 patients, 44 (59%) were male, age 79 (77-82) years. 69 (95%) had adult-onset asthma. 30 (45%) patients were on benralizumab, 39 (53%) mepolizumab, 4 (5%) omalizumab, and 1 (1%) dupilumab. 71 (95%) were self-administering the mAb at home. After 12 months of treatment, 64 (86%) had a positive response to mAb defined as ≥50% reduction in exacerbations and/or maintenance oral corticosteroid (mOCS). Exacerbations reduced from 4 (0-14) in the year pre-mAb to 0 (0-5), p<0.001. Of the 36 patients on mOCS, 20 (55%) weaned off OCS for asthma. ACQ6 improved: 2.8 (0.0-5.5) to 1.5 (0.0-4.5), p<0.001. Asthma remission (off mOCS, no exacerbations, and ACQ <1.5) was achieved by 10 (14%) patients. 6 (8.1%) were mAb non-responders. There was a high-prevalence of polypharmacy- 89% were prescribed ≥5 medications. Multi-morbidity was common: 100% had ≥2 comorbidities, 96% had ≥3 comorbidities and 67% had ≥4 comorbidities. 8 patients died during the review period, none due to asthma. Adverse events were rare (4 patients, 5%): rash, joint pains, hair loss and weight loss. <bold>Conclusion:</bold> Despite a high prevalence of co-morbidities and polypharmacy, mAb use in patients ≥75 years with SA has similar, good clinical outcomes to patients <75 years in clinical trials and real-world studies.