P43 Patient tolerability of adalimumab biosimilar therapy in dermatology and rheumatology: real-world experience from a large tertiary centre

Abstract Adalimumab is widely used in the treatment of immune-mediated inflammatory diseases. It highest-spend drug National Health Service, costing more than £400 million annually. In 2018, adalimumab biosimilars became available, leading to substantial cost savings. However, patient tolerability remains underexplored. We evaluated biosimilar therapy (Idacio®) patients who were switched from Humira® a large dermatology and rheumatology tertiary centre. identified all issued with prescription Humira by [psoriasis hidradenitis suppurativa (HS)] or (rheumatoid arthritis, psoriatic ankylosing spondylitis Behçet disease) analysed number Idacio between January 2021 March 2022. Patient electronic records reviewed up October 2022 identify back originator product documented reason for switch. The primary outcome was numbers product. Of 769 Humira, 694 during study period. these, 134 (19.3%) product, 102 whom (76.1%) remained on this follow-up. highest proportion individuals switching observed HS population (26.7%). most common reasons patient-reported loss disease control (n = 63; 47.0%), injection pain 51; 38.1%) both 10; 7.5%). median time switch 197 days (interquartile range 138–280). prescribed Idacio, 32 (4.6%) an alternative biologic agent Our experience previous switches within (etanercept, rituximab infliximab) has resulted few requiring originator. data indicate that around one five our higher citing may relate citrate excipient content larger volume Idacio. Loss efficacy well established adalimumab, part due antidrug antibodies, cannot be specifically attributed biosimilar. Switching alter patient’s confidence drug, which particularly important when it first-line only approved condition. Data switch-back rates other required understand how generalizable findings are potential economic implications.