Population pharmacokinetic modeling of vedolizumab for graft-versus-host disease prophylaxis in adults with allogeneic hematopoietic stem cell transplant.

We aimed to characterize the population pharmacokinetics (PK) of vedolizumab for acute graft-versus-host disease prophylaxis in adults undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) and assess potential clinically relevant covariates. Dosing, patient characteristics, and PK from a phase 1b, open-label, dose-finding study of vedolizumab 75 mg initial dose escalated to 300 mg and a phase 3 study of vedolizumab 300 mg in patients receiving allo-HSCT were analyzed using a two-compartment population PK model with linear elimination. Covariates included age, race, weight, sex, albumin, lymphocyte count, GvHD type, and concomitant medications. Weight, albumin, and lymphocyte count were time-varying covariates. Model selection was driven by goodness-of-fit criteria, precision of parameter estimates, and visual predictive checks. In 193 patients undergoing allo-HSCT, vedolizumab PK were well described by a two-compartment, linear PK model. Using reference covariate values, final parameter estimates (95% confidence intervals [CI]) were: clearance, 0.148 (0.136, 0.162) L/day; central volume of distribution, 3.12 (3.03, 3.21) L; intercompartmental clearance, 0.500 (0.408, 0.612) L/day; and peripheral volume of distribution, 3.95 (3.52, 4.44) L. Weight and albumin were the most important predictors of vedolizumab PK, with clearance decreasing by ≈20% for low body weight/high albumin and increasing by ≈30% for high body weight/low albumin. There was an inverse relationship between vedolizumab clearance and age, but no detectable effect for lymphocyte count or GvHD type. Post hoc analyses did not detect any relationship between vedolizumab PK and concomitant medications. In summary, the covariates studied did not have a clinically meaningful effect on the PK of vedolizumab.