Pharmacokinetic/LDL-C and exposure–response analysis of tafolecimab in Chinese hypercholesterolemia patients: Results from phase I, II, and III studies

Abstract

Tafolecimab, a novel fully human monoclonal antibody targeting PCSK9, has been assessed in Chinese healthy volunteers and patients with hypercholesterolemia. This analysis is to develop and qualify a population pharmacokinetics (PopPKs)/LDL-C model to characterize tafolecimab PK and LDL-C profiles, evaluate the impact of potential covariates on tafolecimab, estimate individual predicted exposure, and LDL-C decreasing, furthermore, explore exposure–response relationship to support clinical use. Data from six clinical trials in China were used to develop the PopPK/LDL-C model. A Michaelis–Menten approximation of the target-mediated drug disposition (TMDD) model was used to describe PK data and indirect response (IDR) model was developed to estimate the LDL-C profile. A stochastic approximation expectation maximization algorithm was applied to estimate PopPK/LDL-C parameters. The PK/LDL-C time course data for tafolecimab were well described by TMDD/IDR model. Baseline covariates resulting in statistically significant changes in PK/LDL-C parameters included: body weight and sex on absorption rate constant; body weight, sex, and unbound PCSK9 on central volume; body weight and sex on clearance; baseline LDL-C on first-order rate constants for the removal of an effect); and disease and sex on maximum effect. However, the magnitudes of changes associated with these covariates do not necessitate dose adjustment. Exposure–efficacy relationship indicated that the nadir of LDL-C reduction achieved with the steady-state trough plasma concentration (Ctrough) of tafolecimab at 5 μg/mL, and no further LDL-C decreasing with the increasing Ctrough. There was no exposure dependency observed in exposure-safety exploration. The PopPK/LDL-C model was successfully developed, validated, and predicted tafolecimab/LDL-C concentrations and individual exposures.