The treatment of psoriasis has been revolutionized by the emergence of biological therapies. Monoclonal antibodies (mAb) generally have complex pharmacokinetic (PK) properties with nonlinear distribution and elimination. In recent years, several population pharmacokinetic/pharmacodynamic (PK/PD) models capable of describing different types of mAb have been published. This study aims to summarize the findings of a literature search about population PK/PD modeling and therapeutic drug monitoring (TDM) of mAb in psoriasis. A total of 22 articles corresponding to population PK/PD models of tumor necrosis factor (TNF)-α inhibitors (adalimumab and golimumab), interleukin (IL)-23 inhibitors (guselkumab, tildrakizumab, and risankizumab), IL-23/IL-12 inhibitor (ustekinumab), and IL-17 inhibitors (secukinumab, ixekizumab, and brodalumab) were collected. A summary of the clinical trials conducted so far in psoriasis was included, together with the current structural population PK and PD models. The most significant and clinical covariates were body weight (BW) and the presence of immunogenicity on clearance (CL). The lack of consensus on PK/PD relationships has prevented establishing an adequate dosage and, therefore, accentuates the need for TDM in psoriasis.

Introduction and Objective Physiologically based pharmacokinetic (PBPK) models are increasingly used to predict food effect (FE) but model parameterization is challenged by in vitro–in vivo (IVIV) disconnect and/or parameter nonidentifiability. To overcome these issues, we propose a simplified PBPK model, in which all solubility-driven processes are lumped into a single parameter, solubility, which is optimized against observed concentration–time data. Methods A set of commercially available biopharmaceutical classification system (BCS) II/IV compounds was selected to measure the solubility in a fasted state simulated intestinal fluid (FaSSIF) medium. The compounds were ranked from the lowest to the highest dose-adjusted FaSSIF solubility (FaSSIF/D) value and subdivided into three areas based on an upper and a lower limit: drugs with FaSSIF/D > upper limit having no FE, drugs with FaSSIF/D < lower limit having FE, and drugs between the limits said to be in the sensitivity range (SR), for which we tested the hypothesis that solubility-limited absorption (SLA) identified by simplified PBPK model can reliably predict positive FE if their exposures are not impacted by gut efflux or gut metabolism. Results We demonstrate, using a subset of drugs within SR for which PBPK models were available, that drugs with SLA exhibited a positive FE, while those with no SLA did not show FE. Conclusions This proposal allows for a reliable binary prediction of FE to enable timely decisions on the need for pilot FE studies as well as the timing of pivotal FE studies. Graphical Abstract

Background/Objectives: Implementing model-informed precision dosing (MIPD) strategies guided by population pharmacokinetic/pharmacodynamic (PK/PD) models could enhance the management of inflammatory diseases such as psoriasis. However, the extent of individual experimental data gathered during MIPD significantly influences the uncertainty in estimating individual PK/PD parameters, affecting clinical dose selection decisions. Methods: This study proposes a methodology to individualize ustekinumab (UTK) dosing strategies for 23 Spanish patients with moderate to severe chronic plaque psoriasis., considering the uncertainty of individual parameters within a population PK/PD model. Results: An indirect response model from previous research was used to describe the PK/PD relationship between UTK serum concentrations and the Psoriasis Area and Severity Index (PASI) score. A maximum inhibition drug effect (I_max) model was selected, and a first-order remission constant rate of psoriatic skin lesion (k_out = 0.016 d⁻¹) was estimated. Conclusions: The MIPD approach predicted that 35% and 26% of the patients would need an optimized and intensified dosage regimen, respectively, compared to the regimen typically used in clinical practice. This analysis demonstrated its utility as a tool for selecting personalized UTK dosing regimens in clinical practice in order to optimize the probability of achieving targeted clinical outcomes in patients with psoriasis.

Background/Objectives: Patient care and control of inflammatory disorders, such as psoriasis, can be improved by model-informed precision dosing (MIPD) techniques based on population pharmacokinetic/pharmacodynamic (PK/PD) models. Clinical dose selection decisions based on MIPD strategies need to take account of the uncertainty associated with the individual PK/PD model parameters, which is determined by the quantity of individual observational data collected in clinical practice. Methods: The aim of this study was to propose an approach for personalized dosage regimens of secukinumab (SCK) in 22 Spanish patients with plaque psoriasis, whose severity level was considered moderate to severe, taking into account the uncertainty associated with individual parameters in a population-based PK/PD model. Results: The link between SCK serum concentrations and Psoriasis Area and Severity Index (PASI) scores was explained using an indirect response model. A maximum inhibition (I_max) drug effect model was applied to limit the progression of psoriatic skin lesions within the turnover PD mechanism, which explains the changes in PASI scores during treatment. A first-order remission rate constant for psoriatic lesions (k_out = 0.11 day⁻¹) was estimated. Conclusions: According to the MIPD strategy, 50% of patients would require an optimized regimen and 14% would require an intensified dosage regimen in comparison to current clinical treatment. This research has shown its usefulness as a tool for choosing individualized SCK dosage regimens in patients with long-lasting plaque psoriasis to improve the probability of achieving satisfactory response levels.