Abstract
Abstract Background Biosimilar adalimumab (ADA-B) has been approved in Canada for inflammatory bowel disease (IBD) for over eight years, but real-world descriptions of therapy persistence (discontinuation/switching) comparing ADA-B to its bio-originator (ADA-O) are still scarce. We compared discontinuation of ADA-B and ADA-O in IBD. Methods CAN-AIM is a team funded to do high-priority research projects for Health Canada and other stakeholders. Canadian IBD Research Consortium members contributed to CAN-AIM’s prospective pan-Canadian clinical registry of biosimilar/bio-originator users. We enrolled adults with a clinical diagnosis of Crohn’s disease (CD) or ulcerative colitis (UC), starting a bio-originator or corresponding biosimilar from Feb 2009 to Mar 2024. We assessed time to discontinuation through Kaplan-Meier curves with a log-rank test (right-censoring at loss to follow-up or end of study) and reasons for discontinuation. Using multivariable Cox regression, we assessed time to drug discontinuation, comparing ADA-B and ADA-O. Covariates included age, sex, underlying condition (CD/UC), disease duration, race and ethnicity, calendar year, smoking, education, disease activity (moderate or severe: Crohn’s Disease Activity Index ≥220, Harvey-Bradshaw Index ≥8 or Partial Mayo Score ≥5), obesity (body mass index >30), comorbidity, and prior use of other biologics, as well as previous/current corticosteroids and non-biologic immunosuppressants. Results We followed 103 IBD individuals for a median of 5.0 years (interquartile range of 3.6 to 9.2). IBD duration, age, race and ethnicity, and smoking were comparable among the two groups (Table 1). We censored four individuals who changed from ADA-O to ADA-B due to provincial drug insurance formulary requirements. There were 37 (35.9 %) other discontinuations, or 133.9 events per 1000 person-years. The main reasons for discontinuation were secondary loss of response (n=20, 54.1% of 37) and adverse events (n=7, 18.9%). Other reasons included insurance changes (n=2), patient choice (n=1), and unknown or missing reasons (n=7). Median time to discontinuation was 4.0 years (95% confidence interval [CI] 1.4-5.8) for ADA-O and 6.7 (95% CI 3.6-9.2) for ADA-B. Risk of discontinuation was lower in ADA-B versus ADA-O, with a wide CI (adjusted hazard ratio [aHR] 0.46, 95% CI 0.22–0.97 – Table 2). Older age, female sex, UC, higher education, more recent calendar year, and corticosteroids were significantly associated with discontinuation. Conclusion In this real-world IBD analysis, ADA-B was not associated with a greater risk of discontinuation.
Published Version
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