A Nonmedical Switch From Adalimumab Originator to Biosimilar in Inflammatory Bowel Disease: Pharmacokinetics, Clinical Outcomes and Patient Experience in a Retrospective Real‐World Study

Objectives Data on the use of adalimumab (ADA) biosimilar Idacio (Fresenius Kabi) in inflammatory bowel disease is relatively sparse, whereas the efficacy and safety of other biosimilars have been well described. We evaluated the pharmacokinetics and clinical outcomes in a real‐world cohort of patients who switched from originator to Idacio. In addition, we surveyed patients’ experiences of the switching process. Methods A retrospective analysis of all IBD patients who participated in a nonmedical switch from ADA originator to Idacio at a tertiary centre was performed. Data on ADA drug levels, antibody levels and clinical and laboratory indices of disease activity (Harvey Bradshaw Index for Crohn’s disease, Simple Clinical Colitis Activity Index for ulcerative colitis, C‐reactive protein and faecal calprotectin) were collected prior to and after switching to Idacio. An anonymised patient survey was undertaken to evaluate injection site pain, level of understanding and acceptability of the switch. Results Four hundred and three patients were included. No difference in the ADA levels before and after switching was found ( p = 0.78). There were also no differences in clinical ( p = 0.06), biochemical ( p = 0.36) and biomarker ( p = 0.84) remission rates after switching. In the survey, patients reported moderate injection site pain after switching. The majority of patients self‐reported good levels of understanding of the financial rationale for switching, which correlated with a higher degree of acceptability of the switch ( p < 0.05). Conclusions Switching from ADA originator to Idacio appears effective and well tolerated. Patient engagement and education should be a key part of all nonmedical biosimilar switches.