Early Infliximab Trough Levels Predict the Long-term Efficacy of Infliximab in a Randomized Controlled Trial in Patients with Active Crohn's Disease Comparing, between CT-P13 and Originator Infliximab

Gut Liver. 2023 May 15;17(3):430-440. doi: 10.5009/gnl220005. Epub 2022 Aug 17.


Background/aims: The clinical efficacy and safety of CT-P13 are comparable to originator infliximab for Crohn's disease in CT-P13 3.4 study (NCT02096861). We performed a multivariate logistic analysis to demonstrate the association between early infliximab trough levels and treatment outcomes of CT-P13 and originator infliximab.

Methods: Early serum infliximab trough levels and anti-drug antibody (ADA) levels were compared between CT-P13 (n=100) and originator infliximab (n=98) groups. Receiver operating characteristic (ROC) analysis and multivariate logistic analysis were conducted to identify optimal cutoffs of serum infliximab trough levels and predictive factors for clinical outcomes.

Results: The median infliximab trough levels were not different between CT-P13 and originator infliximab groups at week 6, week 14, and in median ADA levels at week 14, respectively. ROC analysis found an infliximab concentration threshold of 4.5 μg/mL at week 6 and 4.0 μg/mL at week 14 as the cutoff value with the highest accuracy for the prediction of clinical outcomes. Serum infliximab trough levels at weeks 6 and 14 predicted clinical remission at weeks 30 and 54, and endoscopic remission at week 54. The combinations of clinical remission or C-reactive protein normalization with an early infliximab trough level improved the prediction of long-term clinical or endoscopic remission.

Conclusions: A threshold in serum infliximab trough level at week 6 and week 14 was highly predictive for long-term clinical outcomes. There were no statistical differences in serum infliximab trough levels and ADA levels between CT-P13 and originator infliximab.

Keywords: CT-P13; Crohn disease; Immunogenicity; Infliximab trough level.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Antibodies, Monoclonal / therapeutic use
  • Biosimilar Pharmaceuticals* / therapeutic use
  • Crohn Disease* / drug therapy
  • Gastrointestinal Agents / therapeutic use
  • Humans
  • Inflammatory Bowel Diseases* / drug therapy
  • Infliximab / therapeutic use
  • Treatment Outcome


  • Infliximab
  • CT-P13
  • Biosimilar Pharmaceuticals
  • Antibodies, Monoclonal
  • Gastrointestinal Agents

Grants and funding

ACKNOWLEDGEMENTS The work was supported by Celltrion (Incheon, South Korea) and Pfizer (New York, NY, USA).