Efficacy, Safety, and Cost-Effectiveness of the Infliximab Biosimilar GP-1111 in Patients with Inflammatory Bowel Disease Who Underwent a Nonmedical Switch: A Prospective Cohort Study

Abstract

Purpose: Data regarding treatment switch from the originator infliximab (IFX) to GP-1111 in inflammatory bowel disease (IBD) are limited. Only a few studies have examined the financial aspects of biosimilar use, none of them regarding GP-1111. The study aimed to evaluate the long-term efficacy and safety of the IFX biosimilar GP-1111 in patients with IBD who underwent a nonmedical switch from the original IFX in real-life settings. Further, it investigated the switch from a health economics perspective. Patients and Methods: A prospective cohort study was conducted on patients with IBD who were on maintenance IFX treatment and who switched to the IFX biosimilar GP-1111 due to financial constraints, with a 1-year follow-up period. Clinical and laboratory parameters were measured at baseline and at weeks 8, 16, and 52 and serum IFX levels were measured at baseline and at week 24. Statistical analyses were performed using the paired t-test, Pearson’s chi-square test, Kaplan–Meier survival curves, Cox proportional hazard regression models, and univariate linear model. Results: This study included 142 patients (95 with Crohn’s disease and 47 with ulcerative colitis). The average serum IFX level remained within the therapeutic range from baseline (3.2 ± 2.3 μg/mL) to week 24 (3.7 ± 2.7 μg/mL, p = 0.106). The corticosteroid-free remission (S-SFR) rates were stable (baseline: 69.7%, follow-up: 72.9%, p = 0.58). The 1-year treatment persistence rate was 83.1%. The adverse events included allergic reactions (IR: 6.3 per 100 patient-years) and paradoxical reactions (IR: 2.4 per 100 patient-years). Based on the estimated cost analysis, biosimilar use could lead to significant savings, with a total of 201.9 million HUF (514,000 €). Conclusion: The IFX biosimilar GP-1111 was safe and effective against IBD in real-world settings. The average serum IFX levels and S-SFR rates remained stable, while no identifiable factors leading to treatment discontinuation were observed. Biosimilar use has a cost advantage with a reassuring safety profile.