Comparison of the Pharmacokinetics of CT-P13 Between Crohn's Disease and Ulcerative Colitis

Background: We aimed to compare trough infliximab levels and the development of antidrug antibody (ADA) for 1 year between Crohn's disease (CD) and ulcerative colitis (UC) patients who were biologic-naive, and to evaluate their impact on clinical outcomes. Methods: This was a prospective, multicenter, observational study. Biologic-naive patients with moderate to severe CD or UC who started CT-P13, an infliximab biosimilar, therapy were enrolled. Trough drug and ADA levels were measured periodically for 1 year after CT-P13 initiation. Results: A total of 267 patients who received CT-P13 treatment were included (CD 168, UC 99). The rates of clinical remission (72% vs. 32.3%, P<0.001) at week 54 were significantly higher in CD than in UC. The median trough drug level (μg/mL) was significantly higher in CD than in UC up to week 14 (week 2, 18.7 vs. 14.7, P<0.001; week 6, 12.5 vs. 8.6, P<0.001; week 14, 3.4 vs. 2.5, P=0.001). The median ADA level (AU/mL) was significantly lower in CD than in UC at week 2 (6.3 vs. 6.5, P=0.046), week 30 (7.9 vs. 11.8, P=0.007), and week 54 (9.3 vs. 12.3, P=0.032). Development of ADA at week 2 [adjusted odds ratio (aOR)=0.15, P=0.026], initial C-reactive protein level (aOR=0.87, P=0.032), and CD over UC (aOR=1.92, P<0.001) were independent predictors of clinical remission at week 54. Conclusion: Infliximab shows more favorable pharmacokinetics, including high drug trough and low ADA levels, in CD than in UC, which might result in better clinical outcomes for 1-year infliximab treatment in CD patients.