Exploring the Reasons Behind the Substantial Discontinuation Rate Among Patients Taking CT-P13 in a Large Tertiary Hospital in Western Switzerland: A Retrospective Cohort Study Using Routinely Collected Medical Data

Abstract

Background: 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.

Objective: 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.

Methods: 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.

Results: 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).

Conclusions: 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.

Fig. 1

Flow diagram representing the distribution of the patients eligible or included in the study and the reasons for exclusion. GAS gastroenterological diagnosis group, IMM immunological diagnosis group, RHE rheumatological diagnosis group

Fig. 2

Kaplan–Meier plot showing the proportion of patients who discontinued CT-P13 over 360 days, by status. Both continuous and dotted heavy lines represent the median function curves. Both shaded areas represent the interquartile range. The black dotted line at 0.50 indicates when 50% of the initiators discontinued CT-P13 (~ 330 days)