Pharmacokinetics and efficacy of subcutaneous infliximab 120 mg every 2 weeks: a post hoc comparison with intravenous dosing in a phase 1 study in patients with inflammatory bowel disease.

Background: A phase 1 study of CT-P13 demonstrated pharmacokinetic non-inferiority of subcutaneous (SC) infliximab (IFX) to intravenous (IV) IFX in patients with inflammatory bowel disease. This post hoc analysis aimed to evaluate outcomes in the subset of patients who received IFX SC 120 mg every 2 weeks (Q2W) (eventual approved standard dose). Methods: In the phase 1 study (NCT02883452), patients received IFX IV induction therapy at Week (W) 0 and W2 and were randomized at W6 to receive IFX SC 120 mg (for patients weighing <80 kg at W6) or 240 mg (for ≥80 kg) Q2W from W6 through W54, or IFX IV 5 mg/kg every 8 weeks (Q8W) from W6 through W22 and IFX SC 120 mg (for <80 kg at W30) or 240 mg (for ≥80 kg) Q2W from W30 to W54. This analysis included patients weighing <80 kg and thus received IFX SC 120 mg Q2W from W6 (SC 120 mg Q2W subset, Results: Between W23 and W25, serum IFX concentrations in both subsets were within a similar range, but from W25 through W30, patients in the SC 120 mg Q2W subset exhibited higher serum IFX concentrations than in the IV 5 mg/kg Q8W subset, yielding significantly higher drug exposure. Efficacy and safety outcomes were comparable between subsets throughout. Conclusions: These data support a favorable pharmacokinetic profile of the approved standard dose of IFX SC.