Self-reported efficacy and safety of infliximab and adalimumab biosimilars after non-medical switch in patients with inflammatory bowel disease: results of a multicenter survey

Few data are available on subjective disease control and perception of adverse events (AEs) during switching from original anti-TNF agents to biosimilars.Hungarian patients with inflammatory bowel disease were interviewed after a mandatory non-medical switch from an infliximab (IFX) originator to a biosimilar GP1111 or from an adalimumab (ADA) originator to a biosimilar GP2017. Drug choice was based on patient's and physician's decision. Subjective efficacy was measured using a 10-point scale, and AEs were assessed. Difference in efficacy before and after the switch was compared within and between the drugs.Seventy-three ADA and 106 IFX switching patients were interviewed. Subjective efficacy of IFX biosimilar was rated lower compared to IFX originator (8.72 ± 1.68 vs. 7.77 ± 2.34; p = 0.001). The ADA biosimilar was rated higher than its originator (9.02 ± 1.61 vs. 8.42 ± 1.93; p = 0.017). Patients receiving ADA biosimilar were more satisfied with the new treatment compared to IFX (p = 0.032). The incidence of new AEs was 85% in the ADA and 55% in the IFX group (1.79 vs. 0.93 AEs per patient, respectively, p < 0.001).Subjective efficacy of switching to a biosimilar was proven in case of ADA, while reduced efficacy was experienced with IFX biosimilar. Perception of AEs was high and varied between biosimilars.