Evaluation of a Therapeutic Drug Monitoring Strategy for Adalimumab in Psoriasis: A Prospective Pharmacokinetic-Pharmacodynamic Study.

Using a real-world psoriasis cohort, we established the pharmacokinetic-pharmacodynamic (PKPD) relationship for the biologic therapy adalimumab and evaluated the clinical utility and cost-effectiveness of a proactive therapeutic drug monitoring (TDM) strategy. A total of 543 patients on adalimumab monotherapy for psoriasis provided 946 pharmacokinetic samples and 1700 Psoriasis Area Severity Index (PASI) disease severity measurements. To describe the PASI change over time, a one-compartment linear PK model with first-order absorption and elimination was linked to a turnover mechanism of skin lesions. Based on the PKPD relationship and a predefined therapeutic range, real-time stochastic simulation was performed for a proactive TDM strategy, where trough levels guided dose escalation or reduction. Compared to the standard care, the TDM strategy improved PASI90 and PASI75 by 37.5% and 12.8%, respectively, with a 25.9% increase in drug costs. In the future, incorporating the PKPD model into a Bayesian therapeutic monitoring algorithm could facilitate individualized adalimumab dosing.