Safety of sequential biological therapy in inflammatory bowel disease: results from a tertiary referral centre.

Background: Biologicals represent the cornerstone of treatment for moderate-to-severe inflammatory bowel diseases (IBD). Many patients cycle between biologicals when encountering loss of response or adverse events.

Aim: To assess the occurrence of serious infections and malignancies with exposure to several (classes of) biologicals.

Methods: We performed a retrospective cohort study in a tertiary referral centre including consecutive IBD patients exposed to adalimumab, infliximab, ustekinumab or vedolizumab between 1996 and 2019. All serious infections and malignancies, as well as potential confounders, were accounted for.

Results: In total, 1575 patients were included with a median (interquartile range) follow-up of 10 (6-16) years and a duration of biological therapy of 71 (39-112) months. Incidence rates of serious infections were 3.4 per 100 patients' years (PY) in the post-biological setting. Serious infections after biological exposure were associated with systemic steroids in monotherapy (hazard ratio 2.96 [95% confidence interval 1.78-4.93], p < 0.0001), combination therapy of systemic steroids and a biological (2.44 [1.37-4.34], p = 0.002), female gender (1.25 [1.04-1.51], p = 0.02), and prior serious infections in the pre-biological setting (1.42 [1.03-1.96], p = 0.03). Malignancy rates were 1.06 per 100PY in the post-biological setting and increased with older age at biological initiation (1.04 [1.02-1.05], p < 0.0001). The risk for serious infections or malignancies was independent of type and number of biologicals to which the patient was exposed.

Conclusion: This study shows that the sequential use of biological therapy in IBD does not seem to convey an overall higher risk of serious infections or malignancies, but that underlying more refractory disease seems to increase this risk.