Filgotinib (GLPG0634) is a selective inhibitor of JAK1 currently in development for the treatment of RA and Crohn’s disease. This paper describes the pharmacokinetics of filgotinib and its active metabolite, as well as the PK/PD modelling to support dose selection for phase IIB.

Two phase I, randomised, double-blind, placebo-controlled trials in healthy volunteers and one phase IIa proof-of-concept study in RA patients were used to evaluate single and multiple doses of filgotinib.