Efficacy and Safety of Nonmedical Switching From Infliximab Originator to Infliximab Biosimilar CT-P13 in Patients With Inflammatory Bowel Disease, A Single-Center Prospective Study in Japan

Background: Although anti-TNF-α antibodies have created a paradigm shift in inflammatory bowel disease (IBD) treatment, they have contributed to the increase in medical costs. Although the use of infliximab biosimilar (IFX-BS) is recommended in Japan, there have been few reports on non-medical reason (NMR) switches. In our hospital, we introduced the NMR switch from IFX originator (IFX-O) to IFX-BS CT-P13 in IBD patients receiving maintenance IFX-O. Therefore, we aimed to clarify efficacy and safety of patients switched from IFX-O to IFX-BS. Methods: After informed consent, and IBD patients who were NMR switched were prospectively observed. The observation period was from switch to 56 weeks, and the safety, continuance rate, clinical remission rate at 56 weeks, and serum trough IFX concentrations (STIC) were examined (IRB approval number: C21-01-001). Per-protocol analysis was performed to evaluate non-inferiority of STIC at 8, 24, and 56 weeks compared to baseline. The non-inferiority margin was defined as 15%. Results: Of the 169 patients on maintenance IFX, 167 patients agreed to participate in the study with NMR. The safety analysis included all 167 patients, 136 with CD and 31 with UC (male/female 123/44, median age: 43 years, 97 patients with immunomodulator). The dosing regimen at baseline was 5 mg/kg in 132 patients, 10 mg/kg in 21 patients, and shortened interval in 14 patients. Adverse events were observed in 22.8% (38/167). Serious adverse events included one patient of discontinuation due to infusion reaction and one patient requiring hospitalization due to sepsis. Clinical remission rates at baseline were 88.3% (106/120) in CD patients (defined as CDAI < 150), excluding 16 patients with stoma and 93.5% (29/31) in UC patients (defined as Partial-Mayo ≤2). The continuance rate at 56 weeks was 94.7% in CD patients and 100% in UC patients. Clinical remission rates at 56 weeks were 86.8% (92/106) in CD patients and 86.2% (25/29) in UC patients. Regarding STIC, 119 patients comprised the per-protocol population. The mean STIC at baseline, week 8, 24, and 56 were 3.9 μg/mL (IQR: 2.4-6.3), 4.3 μg/mL (IQR: 2.8-7.1), 3.8 μg/mL (IQR: 2.3-5.6), and 4.9 μg/mL (IQR: 2.4-6.3), respectively. The mean ratio of STIC at week 8, 24, 56 compared with those at baseline were 115.6% (95% CI: 107.1-123.9), 101.2 (95% CI: 91.7-110.7) and 123.5 (95% CI: 109.0-137.9), respectively. In all cases, the results were non-inferiority. Conclusions: The results show that the NMR switch from IFX-O to IFX-BS in Japanese IBD patients has a high clinical remission and continuance rate, an acceptable safety profile, and no serological differences.