Henk-Jan Drenth, PhD. (Managing Director)
Peter Vis, MSc. (Principal Consultant Pharmacometrician, Director Business Development)
Teun Post, PharmD, PhD. (Principal Consultant Pharmacometrician, Director Operations)
Nelleke Snelder, PhD. (Principal Consultant Pharmacometrician, Director Education)
Tamara van Steeg, PhD. (Principal Consultant Pharmacometrician, Director Research)
Joost DeJongh, PhD. (Senior Expert, Population PKPD concepts)
Emir Mesic, BSc. (Consultant Pharmacometrician)
Diana Hijdra, BSc. (Data Manager)
Anne Keunecke, PhD. (Consultant Pharmacometrician)
Richard Hooijmaijers, BSc. (Senior Expert, Pharmacometric software development)
Paul van den Berg, MSc. (Senior Consultant Pharmacometrician)
Martijn Ruppert, MSc. (Consultant Pharmacometrician)
Sven Hoefman, PhD. (Principal Consultant Pharmacometrician)
Martijn van Noort, PhD. (Senior Expert, Pharmacometric methods and applied mathematics)
Rolien Bosch, MSc. (Senior Expert, Multiscale Systems Pharmacology Modelling)
Eleonora Marostica, PhD. (Consultant Pharmacometrician)
Jan Berkhout, PhD. (Consultant Pharmacometrician)
Esmée Vendel, PhD. (Consultant Pharmacometrician)
Morris Muliaditan PhD. (Consultant Pharmacometrician)
Bas Goulooze PhD. (Senior Expert, Advanced Pharmacodynamics)
Stefan Zeiser PhD. (Consultant Pharmacometrician)
Marjolein van Westing (Management Assistant)
Anne Heijnen, Msc. (Consultant Pharmacometrician)

Henk-Jan Drenth is the Managing Director of LAPP. He obtained an MSc in Chemistry in 1994, followed by a PhD in Toxicology (PBPK modelling) in 2000 at the Utrecht University, The Netherlands. Henk-Jan worked as a project manager in clinical pharmacology at Tibotec-Virco in Belgium, responsible for Therapeutic Drug Monitoring and Pharmacometrics (2000-2002). He joined LAP&P in 2002, where he worked in many projects with a wide range of therapeutic areas, such as oncology, blood disorders, women’s health, infectious diseases, cardiovascular, and CNS. The projects he worked on ranged from very early (discovery) to late stage (post marketing).

Under the management of Henk-Jan, the company has grown to a professional organisation by the implementation of expert modelling techniques and automation tools, embedded in a modern Quality Management System. This allows the company to optimally serve clients with their drug development and pharmacometric projects.

Henk-Jan enjoys the energy within the company to innovate and create new solutions to support drug development decisions and to get things done. He also loves the collaboration with Academia to educate pharmacometricians of the future. Henk-Jan lives close to the Belgian border in The Netherlands.



Peter Vis is Principal Consultant Pharmacometrics and Director Business Development. Peter has extensive experience in drug development, both in consultancy and within the pharmaceutical industry. He studied Bio-Pharmaceutical Sciences at the Leiden University (The Netherlands) and graduated in 1991. He straightaway started his pharmacometric career by joining Servier in the UK, serving many projects across many therapeutic areas like diabetes, oncology and cardiovascular disease.

In 2000, Peter engaged in consultancy, first with with Pharsight (USA) and later in 2002 with Exprimo (Belgium), where he worked on a wide range of projects with different modelling techniques. In 2008 Peter became Director Advanced Modelling and Simulation at Tibotec/Janssen in Belgium to support decision making in drug development projects, regarding optimisation of e.g. dose selection or study design. Peter has extensive experience in drug development for paediatric use and supported many PIP’s.

In 2012 he joined LAPP, where he uses his creative mind, thinking fast whilst listening to clients to provide a suitable plan to support the client’s request.

Peter lives with his family in the Highlands of Scotland.


Joost deJongh is a Senior Expert Pharmacometrician with LAP&P. Joost has extensive experience in consultancy in pharmacometrics. Following a study in chemistry at the University of Amsterdam (The Netherlands), he received his MSc (with honours) in 1988.

In 1994 he obtained his PhD degree at the Research Institute of Toxicology (RITOX) at Utrecht University (The Netherlands) on the subject of pharmacokinetic mixture interactions between environmental contaminants.

From 1994-1999 he was employed as a research associate and lecturer at RITOX, focusing on PB-PK modelling and Quantitative Structure Activity Relationships (QSAR's) for translational in vitro-in vivo scaling. He has contributed to over fifty peer-reviewed publications with academic and industry groups, and to over ten PhD projects.

Over the past years, disease systems analysis has been his primary area of interest, with focus on models for combination therapies, tolerance and growth.

Joost lives in our country’s Capital city; he was the first consultant to be employed for LAP&P, at its start in 1999.



Richard Hooijmaijers is a Senior Expert Pharmacometrician with LAP&P. He studied Biology and Medical Laboratory Research, at Hogeschool, Utrecht (the Netherlands). He started his career with Kinesis Pharma (the Netherlands) and fulfilled several positions: SAS programmer, software developer, PKPD modeller, and group leader PKPD. In 2008 he became consultant software development and data analysis with 3D Pharm-Exchange in Tilburg. His experience with software development in combination with his pharmacometrics skills supplements the company’s assets.

Richard gets energised by developing new software parts to be added to the company’s automation toolbox, to make the work more efficient. Richard joined LAP&P in 2014. He lives in Raamsdonk with his family, and loves to be on his boat in the Biesbosch during the weekends.


Teun Post is a Principal Consultant Pharmacometrics and Director Operations. He studied Pharmaceutical Sciences and obtained his PharmD (2002) at Utrecht University, The Netherlands. After that, he started as Pharmacometrician at LAP&P. Subsequently, he joined the pharmaceutical industry in 2007 at Organon/Schering-Plough/Merck & Co.

At Merck & Co, Teun worked as Principal Scientist (Director) Clinical PKPD. In this position, he added value to regulatory submissions with FDA and EMA by authoring several CTD modules and by guiding the registration process. This resulted in a broad view on the drug development process. During this time, he also obtained his PhD in Clinical Pharmacology and Pharmacometrics (2009) at Leiden University. The thesis title is: ‘Disease system analysis - between complexity and (over)simplification’.

In 2014, Teun rejoined LAP&P thereby strengthening the company with his pharmacometric experience and expertise ranging from descriptive to mechanistic to systems-pharmacology approaches in drug development.

Teun is an enthusiastic drug developer, with a wide-range experience in both the pharmaceutical industry and consultancy. This combination offers robust and pragmatic plans for the client.


Sven Hoefman is a Principal Consultant Pharmacometrician with LAP&P. Sven holds a PhD in biotechnology and two Master titles; one as Industrial Engineer in Biochemistry at PIH Kortrijk (Belgium) and the other in Applied Microbial Systematics at Ghent University (Belgium), both achieved with great honour.

After two years working as Research Associate Bioanalytics and Pharmacokinetics at Ablynx (Belgium), Sven started his PhD research at Ghent University, where he could be found in the lab studying microbial communities and their role in global warming. After obtaining his PhD, he rejoined Ablynx as a pharmacometrician in 2013. During this time, Sven focused on translational and clinical pharmacokinetics of biologics and was responsible for implementation of model-based drug development within multiple projects ranging from discovery to Phase II clinical development.

Sven joined LAP&P in 2017, where he’s passionate about working in a multidisciplinary environment where mechanistic modeling is applied to support drug development and to enhance our understanding of complex biological processes.

Sven occasionally stays in the centre of Leiden, a popular destination for the Flemish since the end of the 16th century, where he’s promoting Belgian beers and questioning his ability to speak the language as the locals respond to him in English. He lives in his hometown Kortrijk together with his wife and kids.


Jan Berkhout is a Consultant Pharmacometrician with LAP&P. He has studied Biomedical Sciences at the Vrije Universiteit (VU), Amsterdam, where he received his Top-Master’s in System Biology in 2008. The same year, Jan started his PhD research within the systems bioinformatics group at the VU in Amsterdam with a focus on design principles of regulatory networks. He continued his scientific career from 2013 to 2015 as a PostDoc at the Leiden Academic Center for Drug Research (LACDR) and Erasmus Medical Centre, Rotterdam in systems pharmacology developing disease-progression models.

Jan joined LAP&P in July 2015 as a consultant pharmacometrician. Jan has a strong mathematical background and a biological view on disease progression, which is very much appreciated in pharmacometric projects to support drug development.

Jan lives close to Leiden and keeps training to improve himself on the marathon.


Emir Mesic is a Consultant Pharmacometrician with LAP&P. He has studied Biology and Medical Laboratory Research in Enschede (the Netherlands). In 2002 he started his scientific career at Galapagos Genomics NV, a genomics-based drug discovery company in Leiden, where he worked on RNA-interference. He was involved in development of cell-based functional assays using a wide range of molecular biology techniques. Emir joined LAP&P in 2006. He specialised in operational activities regarding the software, in addition to quantitative modelling. Apart from his pharmacometric skills, Emir is LAP&P’s expert in Quality Management topics. Emir lives close to Leiden with his wife and two children.


Nelleke Snelder is a Principal Consultant Pharmacometrics  and Director Education with LAP&P. She studied Life Sciences and Technology at Leiden University and Technical University Delft and graduated in 2004. During this multidisciplinary study she integrated knowledge of Biology, Chemistry, Physics, Technology, Informatics, Pharmacology and Mathematics. While working at LAPP, Nelleke conducted a PhD study on the development of a systems pharmacology model of the cardiovascular system. She obtained her PhD in 2014 at Leiden University. Here experience in pharmacometics covers a wide range of therapeutic area’s and techniques and she headed many different projects as a project manager. Today, Nelleke is a mathematical expert in dynamical system analysis. She monitors the educational needs within LAP&P and stimulates research by asking the right questions at the right time to contribute to further scientific development.

Nelleke is open minded and a pragmatic pharmacometrician who likes to find scientifically sound solutions for drug development questions, while focussing on the project goals.

Nelleke joined LAP&P in 2004 and lives with her partner close to Leiden, within the reach of an electrically powered car.


Tamara van Steeg is a Principal Consultant Pharmacometrics and Director Research with LAP&P. She has studied Bio-Pharmaceutical Sciences at Leiden University (The Netherlands) and graduated in 2002. She obtained her PhD at the department of pharmacology of the Leiden Academic Centre of Drug Research (LACDR). Her research focused on the influence of protein binding on pharmacodynamics and resulted in a thesis entitled: The free drug hypothesis: “Fact or Fiction?” (2008).

Tamara specialises in translational approaches, Quantitative Systems Pharmacology, and the PK and PD of biopharmaceuticals. She applied this expertise in discovery and development projects for many different therapeutic areas like: cardiovascular safety, oncology, neurodegenerative disorders, infectious diseases, and immunology.

She is highly effective and efficient in gathering the relevant scientific knowledge and thinking on the pharmacological concepts, which need to be implemented in order to solve complex problems.

Tamara has a broad experience in Pharmacometrics and is an experienced teacher in this field. She is optimistic and a great collaborator who enjoys to train people both within the company and in academic collaborations. Tamara joined LAP&P in 2006 and lives in Delft with a group of friends and her family.


Rolien Bosch is a Senior Expert Pharmacometrician Pharmacometrician with LAP&P. She has studied Pharmaco-chemistry at the Vrije University of Amsterdam (The Netherlands), and specialised in Molecular Design. She started her career with Organon in 2004 as a molecular modeller and design chemist in multidisciplinary research project teams to improve pharmacologically active structures. She moved from research to development and became a pharmacometrician in 2011 with Merck & Co, with a focus on data visualisation.

Rolien is enthusiastic about data and making sense out of it to support the development of drugs.

Rolien joined LAP&P in 2014. She lives in The Netherlands with her saxophones, husband and two children.


Anne Keunecke is a Consultant Pharmacometrician with LAP&P. She obtained her PhD in Clinical Pharmacy and Pharmacometrics at the Rheinische Friedrich-Wilhems University in Bonn (Germany), where she focused on optimizing dosing regimen of metal complexes in cancer patients via PK/PD modeling, and was responsible for related bioanalytical assay development and validation functioning as a CRO for pharmaceutical companies.

In 2008 she started as PostDoc at the University in Halle and later in Berlin at the departments of Clinical Pharmacy, where she developed PK models for monoclonal antibodies and was a member of the DDMoRe consortium. Her technical skills and experience with large molecules bring constructive input in drug development projects.

Anne is enthusiastic about her work because of the open environment with clients and colleagues, which allows her to solve complex problems spanning over a range of disciplines.

Anne joined LAP&P in 2013. Anne lives with her husband in Leiden and loves to ride with her kids in a ‘bakfiets’.


Martijn van Noort is a Senior Expert Pharmacometrician with LAP&P. He holds a PhD in Mathematics from the University of Groningen, where his research concerned the analysis of the time evolution of mathematical models, a subject known as Dynamical Systems. In the following four years he continued his research at GeorgiaTech, Atlanta, USA and Imperial College, London, UK. In 2006 he joined TNO in Delft, the Netherlands. Martijn is highly analytical, and has the drive and ability to turn abstract ideas into usable products. His background and analytical view on projects results in constructive approaches and plans. He enthusiastically applies mathematics to pharmacometrics to help solve drug development issues.

Martijn joined LAP&P in 2016. He lives in Leiden and occasionally drives to the office with his 1974 Ford Mustang.



Eleonora Marostica is a Consultant Pharmacometrician with LAP&P. In 2010, she obtained her MSc degree in Biomedical Engineering with honors from the University of Pavia (Italy) with a thesis on joint models of response and dropout in clinical trials for the development of psychiatric drugs. In 2014, she received her PhD in Bioengineering and Bioinformatics at the University of Pavia with a research topic on PK/PD modelling of clinical data in depression, asthma and oncology. Since 2010, she collaborated with the Clinical Pharmacology Departments at GlaxoSmithKline in Verona (Italy) and Janssen Pharmaceutica (Belgium). After her PhD, she was a Postdoctoral Researcher at the University of Ghent (Belgium) working on translational PK/PD modelling of drug-induced QT-interval prolongation. Her mathematical background and her insight in model-based drug development bring value to the company.

Eleonora likes to work in a team and she maintains a high level of curiosity. Eleonora joined LAP&P in 2015. She learned Dutch with an Italian-Flemish twist and lives in Italy.​


Paul van den Berg is a Senior Consultant Pharmacometrician with LAP&P. He has studied Biochemistry at the Hogeschool Zeeland in Vlissingen (The Netherlands). Starting in 2010, Paul studied part time ‘Modelling and Simulation in PK and PD’ at the University of Manchester, Manchester School of Pharmacy, (UK), where he received his MSc in 2014. During this study he developed a PK/PD model for a monoclonal antibody and its B-cell depleting effect. He started his pharmacometric career in 2006 at Kinesis Pharma in Breda (The Netherlands) and fulfilled several positions during which time he became an experienced PKPD modeller. In 2011 he was appointed group leader Pharmacometrics and Biometrics.

Paul has a broad view on the PKPD modelling field which makes him valuable for many different types of projects.

According to Paul, modeling and simulation is an interesting field of work, because the recipe for a successful model usually comprises the ingredients: science, creativity and pragmatism, but in varying proportions depending on the project. Paul joined LAP&P in 2015. He lives on one of the Dutch islands below sealevel.


Diana Hijdra is Data Manager with LAP&P. Diana has studied Analytical Chemistry at the Hogeschool of Leiden (The Netherlands). She started her career with Octoplus in 2001 in Leiden as a laboratory technician. Here she developed analytical methods to support the development of new drugs. In 2007 she joined LAP&P as a data manager. She supports the team by customising input datasets from clients to workable formats to start a modelling project with. Diana likes to be involved in the diversity of preclinical and clinical projects with different kinds and formats of input data.

Diana lives with her family in the flower capital of the world (Aalsmeer) with its famous “pramenrace”.


Martijn Ruppert is a Consultant Pharmacometrician with LAP&P. He studied econometrics at the Tilburg University (The Netherlands) and he graduated in 2006 in Operations Research and Management Science. He started his pharmacometric career with Kinesis Pharma in 2008 and fulfilled many positions; starting as a data analyst and becoming a statistical programmer and PKPD modeler. As such, Martijn worked on a wide range of projects in a diverse set of therapeutic area’s. His statistical and programming background is effective in several projects within the company. Martijn joined LAP&P in 2015.

Esmée Vendel is a Consultant Pharmacometrician with LAP&P. She has studied biopharmaceutical sciences at Leiden University (The Netherlands). In 2014, after an abroad internship at the Deutsches Krebsforschungszentrum (DKFZ) in Heidelberg, Germany, she obtained her MSc degree. During her master studies, Esmée developed an interest in mathematics and mathematical modelling. After her studies, Esmée started working as a research assistant at Leiden University and Centrum voor Wiskunde en Informatica (CWI), where she worked on computer models to study the initial stages of tumour formation. In february 2015, Esmée started her PhD in Mathematical Pharmacology at the Mathematical Institute of Leiden University, in collaboration with the Leiden Academic Centre for Drug Research (LACDR). During her PhD, she developed a mathematical model to predict the local distribution of medicines within the brain.

Esmée is driven by curiosity and is passionate to make sense out of data and find solutions to complex problems. Supported by her background in both pharmacology and mathematical modelling, she is eager to apply her obtained knowledge to aid drug development. Esmée joined LAP&P in 2019 and lives in Haarlem. In her free time, she enjoys to listen to and make music, read, and play tennis.


Morris Muliaditan is a Consultant Pharmacometrician with LAP&P. He has studied Biopharmaceutical Sciences at Leiden University (The Netherlands). During his studies, Morris developed a keen interest in the application of quantitative pharmacology in drug discovery and development. After the completion of his MSc in 2013, he started a PhD in Clinical Pharmacology at the University College London (UCL) School of Pharmacy in 2014 where he focused on the use of translational drug-disease modelling framework to inform the development and dose rationale for drug combinations for the treatment of tuberculosis. This PhD was performed in collaboration with GlaxoSmithKline (GSK) which enabled him to apply model-informed drug discovery and development (MIDD) principles in real settings. After the completion of his PhD in 2018, he subsequently joined the Translational Medicine/DMPK group in GSK Stevenage where he provided PK/PD support for discovery projects in a broad range of therapeutic area’s (oncology, respiratory, infectious disease, immuno-inflammation).

Morris has a broad experience in the use of pharmacometrics in preclinical and clinical drug development. He enjoys collaborating with a multidisciplinary team and likes to translate and communicate complex problems into fit-for purpose modelling solutions to address key questions and inform decision-making in drug discovery and development.
Morris joined LAP&P in 2020 and lives in Bodegraven with his family.


Bas Goulooze is a Senior Expert Pharmacometrician with LAP&P. In 2016, he obtained his MSc degree in Bio-Pharmaceutical Science (with honours) at the Leiden University (The Netherlands).

He obtained his PhD (with honours) at the Leiden University, after performing pharmacometric research on the pharmacodynamics of analgesics in both paediatric and adult populations. His PhD research covered clinical research questions on optimal pain management, as well as the introduction of novel pharmacodynamic modelling methodology.

Bas joined LAP&P in 2020, lives in Leiden and likes to commute to the LAP&P office by bike.


Stefan Zeiser is a Consultant Pharmacometrician with LAPP. He studied Mathematics at the University of Heidelberg, Germany, and holds a PhD in Biomathematics from the University of Greifswald, Germany. After more than six years working mainly in the Systems Biology area, he started his pharmacometric career at Nycomed, Germany, in 2008.

In 2010 he moved to The Netherlands where he worked as a pharmacometrician on various clinical projects at Kinesis Pharma, Breda, for six years. Thereafter, he moved to ProQR Therapeutics in Leiden, The Netherlands, where he worked as a pharmacometrician on preclinical projects for the development of oligonucleotides for the treatment of orphan diseases. Stefan joined LAP&P in 2018.

Marjolein van Westing is the Management Assistant at LAP&P. In this function she supports the Managing Director in all business aspects of the company. In addition, she assists the Research and Education areas of the Management Team. Before joining LAP&P in 2018, she worked as Business Administrator in general health care.

Marjolein is a proactive person who likes to streamline various business aspects required for others to do their Modelling and Simulation work. Overall, she enjoys making things work.


Anne Heijnen is a Consultant Pharmacometrician with LAP&P. She studied Bio-Pharmaceutical Sciences at Leiden University (The Netherlands). During her studies she developed an interest in modelling. She found that modelling can be compared to solving complex riddles, which is something she loves to do. She started as an intern at LAP&P in 2022, which led to obtaining her Masters degree in the same year. Anne has joined LAP&P as a consultant in 2023 where she hopes to solve a lot of those modelling riddles.

Anne lives in Voorhout with her family and loves to sail, ski and play underwaterhockey.