CT-P13 is an infliximab biosimilar that was granted market authorization in Switzerland in 2016. Despite the growing literature supporting the equivalence of CT-P13 compared with originator infliximab regarding the efficacy, safety, and immunogenicity and the undeniable cost-saving opportunities, CT-P13 remains widely underused in Switzerland.
Leaving aside the phenomenon of a low initiation rate, this study aimed to explore the reasons behind the high discontinuation rate observed among the patients taking CT-P13 in a large tertiary hospital in Western Switzerland.
We performed a retrospective cohort study using routinely collected data. Patients were eligible if they received originator infliximab or CT-P13 between September 2017 and December 2020. They were included if they had received at least two CT-P13 infusions during the same period. Patients were excluded if the follow-up was incomplete prior to or 6 months after their first CT-P13 infusion and if they had an oncological main diagnosis. Primary outcomes were the reasons for treatment discontinuation.
One hundred and fifty-six patients were included and classified into two groups: switchers who were treated with originator infliximab and were switched to CT-P13 (n = 85, 54%) and initiators who did not receive originator infliximab prior to CT-P13 treatment (n = 71, 46%). Included patients belonged to three different groups of diagnosis: gastroenterological (67, 43%), rheumatological (61, 39%), and immunological (28, 18%). Twenty-three (27%) switchers and 35 (49%) initiators discontinued CT-P13 after 12 months. Main reasons for CT-P13 discontinuation were lack of efficacy (n = 21, 36%) and secondary loss of response (n = 16, 28%); however, objective assessments were not available. Initiators' probability to discontinue CT-P13 at 12 months was significantly higher than switchers' (p < 0.01).
Lack of efficacy and secondary loss of response were the main reasons for the high CT-P13 discontinuation rate observed in a large tertiary hospital in Western Switzerland. Lack of active training and coordination among healthcare professionals and little education in patients may have exacerbated patients' subjective complaints and increased the CT-P13 discontinuation rate.