Translational PBPK
and First Time in
Human Dose Predictions
Accurately predicting pharmacokinetics (PK) and target site exposure is essential for any drug development strategy, as it informs decisions about how a drug will be delivered and its potential impact on patient outcomes. By integrating pharmacokinetics with pharmacodynamics (PD), we can predict therapeutic responses and develop dosing strategies that are both safe and effective. This integration allows for a deeper understanding of the dose-response relationship, critical for determining optimal dosing regimens.
Physiologically based pharmacokinetic (PBPK) and quantitative systems pharmacology (QSP) models provide detailed insights into how a drug is absorbed, distributed, metabolized, and excreted (ADME), as well as how it interacts with biological targets to produce desired therapeutic effects.
Translational PBPK refers to the use of physiologically based pharmacokinetic modeling to bridge this gap, leveraging in vitro and in vivo data to predict human PK and inform early clinical decisions, such as First Time in Human (FTIH) dosing.
These models account for complex biological interactions and individual variability, enabling predictions that reflect real-world conditions. This comprehensive modeling approach not only optimizes dose levels to balance efficacy and safety but also supports personalized treatment adjustments across different patient populations, ensuring that dosing strategies are tailored for maximum therapeutic benefit with minimal risk.
Physiologically based biopharmaceutics modeling (PBBM) is a specific field of PBPK model applications that aims to establish the link between the formulation’s properties and in vivo performance.
This field of application of PBPK modeling is evolving at a fast-pace and offers the link between in vivo and in vitro to support pharmaceutical development in the selection of the best drug substance and product, as well as later in development in the establishment of manufacturing quality and controls.
Dissolution testing is often a key input in PBBM. Results from in vitro experiments characterizing drug substances and the formulation behavior (e.g., solubility, particle size, dissolution) can be linked to key ADME parameters and integrated into full PBPK models to predict PK exposure in plasma and/or specific tissues or organs.
These models can also be linked to Pharmacodynamic (PD) relationships to derive the impact of physicochemical, drug and formulation properties on safety and efficacy. The role of Physiologically Based Biopharmaceutics Modeling (PBBM) in drug development spans multiple stages, including supporting patient-centric design, guiding life cycle management, informing regulatory submissions, streamlining development processes, optimizing dosing strategies, enhancing study design, and aiding in formulation development and developability assessment.

What we can offer
At ESQlabs, we specialize in developing tailored PBPK and PD models for a variety of drug modalities, including small molecules, biologics, and novel drug formats. Using the Open Systems Pharmacology Suite, we combine ADME properties and receptor interactions to simulate dose-effect relationships across different dosing regimens. Our models support critical phases of drug development, from discovery to clinical trials, providing predictive insights to refine dosing strategies and maximize therapeutic benefits while minimizing risks.

Related Platforms
Large Molecules, Biologics and Novel Modalities
Small Molecules and Chemicals
QSP Disease and QST Models
Digital Twins for Micro-physiological Systems: MPSlabs
Related publications and initatives
Meet the Team

Alexander Kulesza
Alexander is a Chemist by training with a PhD focusing on theoretical and computational methods for structural and optical property predictions.
After spending several years in academia (U. of Lyon) working on molecular dynamics simulation and free energy methods, Alex has most recently been working with CROs in applying large-scale disease and quantitative systems pharmacology models integrated into clinical trial simulations, across a number of disease areas.
Alex leads QSP/T and qAOP / Systems Pharmacology with the aim to promote widespread application of physiologically based and mechanistic modeling and to create robust and qualified, yet versatile models and applications for high impact decision making.

Christian Maass
Christian Maass is a physicist and computational biologist with over eight years of academic and industrial experience, where he established a strong national and international network. He is passionate about the integration of computational modeling and biological experiments for translational pharmacology applications.
Before joining ESQlabs, Christian Maass worked in various therapeutic areas, e.g. neurodegenerative, inflammatory, and metabolic diseases (Alzheimer, rheumatoid arthritis, NASH/NAFLD). Among others, he developed individualized PBPK models for molecular radiotherapy (leukemia), automated workflows for big data (*omics), network-based analysis of inflammation diseases, and mechanistic modeling of organ-on-chip data.
He received his Master in Medical Physics from the University College London in 2012 and PhD from the University of Heidelberg in 2015. As a postdoctoral researcher at the Massachusetts Institute of Technology (MIT), Cambridge, MA, USA, he focused on application-driven method development for microphysiological systems in safety pharmacology. In 2018, Christian Maass joined Certara’s Quantitative Systems Pharmacology (QSP) team, working on liver disease models and leading projects to integrate organ-on-chip (OoC) and computational modeling for translational pharmacology applications.
- Studying metabolism with multiorgan chips: new tools for diseasemodelling, pharmacokinetics and pharmacodynamics
- Considering developmental neurotoxicity in vitro data forhuman health risk assessment using physiologicallybased kinetic modeling: deltamethrin case study
- Considering developmental neurotoxicity in vitro data for human health risk assessment using physiologically-based kinetic modeling: deltamethrin case study
- Dependence of treatment planning accuracy in peptide receptor radionuclide therapy on the sampling schedule
- Physiologically Based Pharmacokinetic Modeling Is Essential in 90Y-Labeled Anti-CD66 Radioimmunotherapy
- Establishing quasi-steady state operations of microphysiological systems (MPS) using tissue-specific metabolic dependencies
- Multi-functional scaling methodology for translational pharmacokinetic and pharmacodynamic applications using integrated microphysiological systems (MPS)
- Translational Assessment of Drug-Induced Proximal Tubule Injury Using a Kidney Microphysiological System
- Modelling human liver fibrosis in the context of non-alcoholic steatohepatitis using a microphysiological system
- A systematic review of kidney-on-a-chip-based models to study human renal (patho-)physiology

Diane Lefaudeux
Diane Lefaudeux is an interdisciplinary scientist with a strong drive to understand complex mechanisms and in particular those arising from biological systems.
Before joining ESQlabs, she worked at Novadiscovery where she developed PBPK-QSP models on various therapeutic areas to predict outcomes using virtual populations.
Diane obtained her Master’s degree in General Engineering from École Centrale Paris, France, as well as in Control Systems Engineering and Systems Biology from University of Stuttgart, Germany.

Laura Villain
Laura Villain is a biomodeler with interests in various mechanistic modeling approaches and statistical methods. She has experience with popPK, QSP, and PBPK models, complemented by her biostatistics skills.
Before joining ESQlabs, she worked at Novadiscovery, where she developed and improved several PBPK and PBPK-QSP models to reproduce in silico trials. She gained in-depth knowledge of all the steps required to develop a model that can reproduce clinical outputs in compliance with regulatory guidelines. She is also interested in R programming and has provided internal training on R within the company. Before that, she worked as a postdoctoral researcher in biostatistics in the oncology field at INRIA (Bordeaux University). There, she explored high-dimensional methods to link omics data with time-to-event outcomes.
Laura received her Master’s degree in biomodeling sciences from INSA Lyon (France). For her Ph.D. thesis, she studied the impact of interleukin 7 injections on HIV-infected patients. She used a mechanistic model and proposed an adaptive protocol of injections. Her PhD research was supervised by Dr. Daniel Commenges and Prof. Rodolphe Thiébaut at the Department of Public Health at Bordeaux University.

Marco Siccardi
Marco is a Clinical Biologist by training with a PhD in molecular pharmacology and PK/PD modelling. He spent over 15 years at the University of Liverpool working on the topic of pharmacogenetics and in developing PBPK approaches for the optimisation of drug delivery, including HIV therapy optimisation.
Marco has most recently been working with CROs in taking this approaches for modelling and simulation approaches and PKTK (Systems Toxicology) models across a number of disease areas.
Marco leads the Systems Toxicology team with the aim to promote collaborative innovation and to develop novel modeling approaches to streamline the toxicological assessment.
- Development of an end-to-end Quantitative Model-Informed Drug Development (MIDD) ECOSYSTEM
- A review of OSP suite PBBM capabilities: looking ahead
- Roadmap for action for advancing aggregate exposure to chemicals in the EU
- Application of High-Throughput PBPK Modeling to Develop an IVIVE Approach for Oral Permeability
- Enhancing PB(P)K Models for the Female Reproductive Tract: A Framework for Local and Systemic Drug Kinetics
- Advancing Maternal-Fetal and Lactation PBK Models for Cross-Species Risk Assessment in Toxicology
- High-Throughput PBPK Framework in R using Open Systems Pharmacology Software for Anti-Tuberculosis Drug Development

Pavel Balazki
Pavel Balazki is a bioinformatitian by training with over 10 years of experience in PB(P)K and QSP/T modeling and software development.
Pavel’s modeling expertices is focused on developing complex PB-QSP/T disease models, such as the Diabetes Platform or the Thyroid Hormones Toxicology Platform.
Pavel leads the Software ToolChain team at ESQlabs, developing new technologies to enable an integrated ecosystem of software, models, and solutions.
- Development of an end-to-end Quantitative Model-Informed Drug Development (MIDD) ECOSYSTEM
- Evaluation of the drug-drug interaction potential of treosulfan using a physiologically-based pharmacokinetic modelling approach
- Application of High-Throughput PBPK Modeling to Develop an IVIVE Approach for Oral Permeability
- Harnessing Open-Source Solutions: Insights From the FirstOpen Systems Pharmacology (OSP) Community Conference
- Harnessing Open-Source Solutions: Insights From the First Open Systems Pharmacology (OSP) Community Conference
- Advancing Maternal-Fetal and Lactation PBK Models for Cross-Species Risk Assessment in Toxicology
- High-Throughput PBPK Framework in R using Open Systems Pharmacology Software for Anti-Tuberculosis Drug Development

Raphaëlle Lesage
Raphaëlle, is a Systems Pharmacologist and Bioengineer by training. At ESQlabs, she focuses on applying PBPK and QSP modelling to support drug development, she coordinates the Special Population core service and is particularly interested in modelling special populations to optimize therapeutic strategies, design trials, and prevent unsafe exposure..
Previously, she served as Chief Scientific Officer at the Virtual Physiological Human Institute, where she coordinated scientific working groups in multiple European projects and led stakeholder engagement and regulatory initiatives for advancing in silico medicine.
She studied Bioengineering and Computational modelling for Biology and Pharmacology at Polytech Nice Sophia. She obtained a degree in reseach valorization from UMPC (Paris) and she holds an interdisciplinary PhD in Engineering and Biomedical Sciences from KU Leuven (Belgium), where she conducted research on computational modelling of therapeutic strategies to limit cartilage degeneration or promote bone regeneration.
Vanessa Baier
Vanessa Baier is bioinformatician by training, with a focus on computational modeling in the field of systems biology/systems pharmacology. She has experience with lab data management tools, Bayesian population PBPK techniques, and the contextualization of in vitro data and mechanistic PBPK models. Her main area at ESQlabs lies in vitro/in vivo extrapolation and toxicity modeling within PBPK QSP
Vanessa Baier studied computer science at TU Braunschweig and Bioinformatics at Goethe University Frankfurt. After an internship at Sanofi, she completed her master thesis at Bayer in the group of Complex Systems Modeling / Applied Mathematics. She then joined the group of Lars Kuepfer at RWTH Aachen University to complete her PhD on PBPK modeling of drug-induced liver injury (DILI) .
- Evaluation of BCRP‑Related DDIs Between Methotrexateand Cyclosporin A Using Physiologically Based PharmacokineticModelling
- A generic avian physiologically-based kinetic (PBK) model and itsapplication in three bird species
- Reproductive toxicity in birds predicted by physiologically-based kinetics and bioenergetics modelling
- A generic avian physiologically-based kinetic (PBK) model and its application in three bird species

Wilbert de Witte
Wilbert de Witte is a Pharmacologist with a strong drive to understand complex mechanisms and the models that represent them. At ESQlabs, he leads the large molecule PBPK and novel modalities platform and he leads the large molecule focus group of the OSP community.
Before joining ESQlabs, he worked at Ablynx NV, later Sanofi Ghent, on the preclinical and clinical development of NANOBODY® therapeutics. He developed several PBPK and PBPK-QSP models as well as traditional TMDD and PKPD models for mechanistic analysis of in vitro, in vivo, and clinical data. He accumulated in-depth knowledge on the behavior of large molecules in different modalities and with various target binding characteristics.
Wilbert de Witte obtained his Master’s degree in Bio-Pharmaceutical Sciences from Leiden University (the Netherlands). For his PhD thesis, he studied the impact of drug-target binding kinetics on in vivo drug action. His PhD research was supervised by Prof. Liesbeth de Lange, Prof. Piet-Hein van der Graaf and Prof. Meindert Danhof at the department of Pharmacology at Leiden University.
- Local depletion of large molecule drugs due to target binding in tissue interstitial space
- Harnessing Open-Source Solutions: Insights From the FirstOpen Systems Pharmacology (OSP) Community Conference
- Harnessing Open-Source Solutions: Insights From the First Open Systems Pharmacology (OSP) Community Conference
- Local depletion of large molecule drugs due to target binding in tissue interstitial space
- Whole-Body Physiologically Based Pharmacokinetic Modeling Framework for Tissue Target Engagement of CD3 Bispecific Antibodies