Population Pharmacokinetics and Pharmacokinetics-Pharmacodynamics Analyses of Elafibranor to Support Dose Selection...

Elafibranor 80 mg/day is approved for second-line primary biliary cholangitis (PBC) treatment. We present pharmacokinetic (PK) analyses of elafibranor and its metabolite, GFT1007, and pharmacokinetic-pharmacodynamic (PKPD) analyses describing the relationship between their exposure and responses in alkaline phosphatase (ALP) and total bilirubin (TB). PK data originated from 17 clinical trials. Separate elafibranor and GFT1007 PK models were developed using nonlinear mixed-effects modeling. Effects of covariates on PK parameters were explored. PKPD data originated from one phase II and one phase III trial; separate ALP and TB models were developed using a sequential approach. The sum of the areas under the plasma-concentration time curve during a dosing interval at steady state of elafibranor and GFT1007 (AUC_{τ,ss sum}) from the PK models was used as a driver for drug effects. A joint ALP-TB model, considering correlations in the inter-individual variability on selected parameters, was developed and used to perform simulations. Elafibranor and GFT1007 are described by structurally similar two-compartmental models. Elafibranor has a longer elimination half-life versus GFT1007 (59.7 versus 10.7 h); predicted time to steady state was 12.4 versus 2.22 days. Covariate effects on the PK of elafibranor and GFT1007 had a limited effect on the PD response of patients receiving the 80 mg/day regimen. Based on PKPD simulations, elafibranor 80 mg/day showed a clear effect and improvement in ALP and TB versus placebo. Saturation in ALP responses was observed for > 30 μmol·h/L, reached by around 60% of patients. These analyses support that elafibranor 80 mg/day is an efficacious PBC treatment.