TNFα inhibitor treatment trajectories

Patients with immune-mediated inflammatory diseases, such as rheumatic diseases or inflammatory bowel disease are commonly treated with a type of medicine called Tumour Necrosis Factor (TNF) α inhibitors. The therapeutic effect of these TNFα inhibitors can vary between patients. Thus, patients often need to switch to a different treatment. In our thesis we showed that about 17% of IMID patients switch treatment, mainly due to loss of effect. As TNFα inhibitors are costly therapies, transitioning patients to a biosimilar (different brand name, same active ingredient), is a good option for cost containment. We found that several European medical associations have guidelines on transitioning patients from the original TNFα inhibitor (originator) to biosimilar. We found that one in six patients who transitioned from originator TNFα inhibitor to the biosimilar subsequently retransitioned to the originator (stopped biosimilar and restarted originator). Despite originators and biosimilars being similar in terms of efficacy and safety, these patients experienced loss of therapeutic effect and/or side effects from the biosimilar. We found that several factors might affect the number of patients retransitioning, such as the disease severity of the patients and extra monitoring to patients during transitioning. Patients who retransitioned had a more than threefold risk of stopping their originator treatment, indicating that they are still not satisfactorily treated after retransitioning. Patients mentioned that they missed autonomy in transitioning to the biosimilar, and they felt like their hospital prioritised finances over their wellbeing. These findings provide several strategies for improving biosimilar implementation in clinical practice, such as careful selection of a biosimilar, increasing trust in biosimilars, providing follow-up care to transitioned patients and accepting a certain proportion of patients retransitioning.