Establishing PK Equivalence Between Adalimumab and ABP 501 in the Presence of Antidrug Antibodies Using Population PK Modeling

Purpose: ABP 501 (European Union, adalimumab; United States, adalimumab-atto) is a biosimilar to the adalimumab reference product (RP). A model was developed characterizing population pharmacokinetic (PK) variables of ABP 501 and adalimumab RP to include the impact of antidrug antibodies (ADAs). Methods: Data were retrospectively analyzed from a single-dose, parallel-group bioequivalence study in healthy adults who received a single 40-mg SC injection of ABP 501 or adalimumab RP. Modeling was performed by using NONMEM 7.2. The impact of ADAs on PK similarity was assessed from population model-based AUC(0-infinity) values using ANCOVA. Findings: Linear compartment models with various clearance pathways were compared with a one-compartment distribution, first-order subcutaneous absorption model. The final model, a one-compartment model with first-order subcutaneous absorption and linear clearance from the central compartment with an additional time-dependent linear clearance for ADA-positive subjects, described ABP 501 and adalimumab RP population PK variables. Model-derived estimates confirmed PK similarity for ABP 501 and adalimumab RP despite the impact of ADAs. (C) 2021 The Authors. Published by Elsevier Inc.