From Intravenous to Subcutaneous Infliximab: the Same but Different? Real-World Evidence from a Tertiary Center

Recently, a subcutaneous formulation of infliximab was approved. The switch from intravenous infliximab to subcutaneous infliximab may improve convenience, but data on pharmacokinetics and immunogenicity are limited. We aimed to compare the efficacy and tolerability of subcutaneous infliximab and to assess whether the formulation results in higher plasma levels of infliximab.

Retrospective, single-center cohort study. Patients with Crohn's disease or ulcerative colitis, 18 years of age or older, clinically stable, receiving intravenous infliximab (5mg/kg every eight weeks) for more than 6 months were switched. Subcutaneous infliximab (120 mg) was administered every 2 weeks. Clinical and analytical evaluations were performed on day 0, week 2, week 8, and week 16. Plasma levels of infliximab and anti-drug antibodies were measured at these time points.

41 patients included (27 with Crohn's disease and 14 with ulcerative colitis. Azathioprine was administered concomitantly in 47.6%. All patients remained in clinical remission. Analytical biomarkers remained stable. Treatment persistence: 95.1%. Median plasma levels of infliximab at day 0, week 2, week 8, and week 16: 4.89 (3.25 - 7.27), 9.17 (7.89 - 12.6), 19.91 (15.02 - 21.64) and 21.55 (17.18 - 29.57) ug/mL, respectively. Statistically significant difference of plasma levels of infliximab in day 0 vs. week 2 and week 2 vs week 8. Azathioprine resulted in a statistically significant difference in plasma levels of infliximab only at day 0 (not at week 2, week 8, or week 16). Plasma levels of infliximab at week 2, week 8, and week 16, but not at baseline, were statistically associated with body mass index. No anti-drug antibodies were detected. No severe adverse effects. Three patients developed injection site reactions. Three patients developed arthralgia of undetermined significance.

Switching from intravenous infliximab to subcutaneous infliximab maintained clinical response. Plasma levels of infliximab at week two were still lower than expected, considering the results at week eight. A possible advantage of subcutaneous infliximab may be the diminished necessity for concomitant immunomodulators.