Meet the Toxys team!
Scientific and business expertise, great teamwork, and an ambition to make a huge impact in the toxicology field make us who we are. We value collaboration internally and externally as advancing the science keeps us growing as a united team.
Get to know our team below and feel free to reach out if you are interested in joining us!
Management Team
Giel Hendriks
Chief Executive Officer
Paula van Rossum
Chief Business Officer
Remco Derr
Chief Operating Officer
Amer Jamalpoor
Chief Scientific Officer
Giel Hendriks
Chief Executive Officer
Giel Hendriks has a PhD in molecular biology from Utrecht University and worked for four years as a post-doctoral fellow in at Leiden University, studying the relationship between DNA damage and gene mutations. After this fundamental scientific projects he made a switch and worked for six years a senior scientist at the Leiden University Medical Center on the development of in vitro reporter systems to detect and understand the mechanisms of genotoxicity. During this period, he has been instrumental in the development of the ToxTracker assay.
In 2014, Giel obtained pre-seed financing from NGI to start Toxys and to bring the ToxTracker assay to the market. As the CEO of Toxys, he worked to develop the company into an internationally recognised contract research organisation (CRO) in genetic toxicology and chemical safety testing for the pharmaceutical, cosmetics and chemical industry.
After winning the HollandBio BioBusiness Masterclass in 2015, in the beginning of 2016 he secured Seed financing from InnovationQuarter and the Zeeland Investment Fund to establish a new Toxys laboratory, further grow the company and continue the development of innovative in vitro cell assays for mechanistic toxicity screening.
Paula van Rossum
Chief Business Officer
Paula van Rossum joined Toxys in 2016 and is the Chief Business Officer. Paula is a driven professional with a track record in BD & Sales. She was Chief Business Officer for OcellO, a spin-off company from Leiden University where she was involved in the business development and business management. Previously she was project manager Life Sciences at the Utrecht Science Park where she was involved in the promotion and acquisition and Liaison Officer for the LACDR (Leiden University). Paula studied biomedical sciences and graduated in both the Research and Business track.
Remco Derr
Chief Operating Officer
Remco Derr joined Toxys in 2014 and is Chief Operating Officer. He studied biomedical sciences at the university of Ghent (Bachelor) and university of Leiden (Master). During his master he did a research internship at the department of Toxicogenetics in the Leiden University where he studied DNA damage mechanisms. He joined Toxys in 2014 and has been on board since the beginning. Within toxys he oversees the performance of the fee-for-service screening and helps to develop novel applications of the ToxTracker assay.
Amer Jamalpoor
Chief Scientific Officer
Amer Jamalpoor obtained his Master’s degree in Biomedical Sciences (Human Toxicology specialisation) from Radboud University in Nijmegen. During his study, he evaluated clinically relevant drug-drug interactions and drug toxicity in human cells and animal models. During his Ph.D. at Utrecht University, he developed and modelled human kidney proximal tubule cells and kidney organoids by combining CRISPR-Cas9 and omics technologies to identify and test toxicity profiles of potential therapeutic agents for monogenic kidney disorders. In November 2020, Amer joined Toxys as a lead scientist, utilising his expertise to further develop and commercialise ReproTracker and additional in vitro assays for developmental toxicology.
Genetic Toxicology
Inger Brandsma
Director
Mathyn Rijkers
Study Director
Marit Hoogenboom
Scientist
Alison Idemudia
Assistant Scientist
Inger Brandsma
Director
Inger Brandsma obtained her PhD from the Erasmus Medical Centre in Rotterdam, where she studied the role of changes in DNA double strand break repair in cancer cells relating to resistance to PARP inhibitors. After completing her PhD, she worked as a postdoc at the Institute of Cancer Research in London for two years, continuing her work on mechanisms of PARP inhibitor resistance. In 2018, Inger joined Toxys as a senior scientist, utilising her expertise in DNA damage responses, genome stability and cancer to develop novel mechanistic toxicity assays.
Mathyn Rijkers
Study Director
Mathyn obtained his Master’s degree in Biomedical Sciences at Utrecht University. During his major internship, he studied the effects of micro- and nanoplastics on macrophages at the Institute for Risk Assessment Sciences in Utrecht. In February 2022, Mathyn joined Toxys as an intern for his minor internship, where he investigated the applicability of human skin S9 in the ToxTracker assay. Mathyn is currently working as the study director for ToxTracker.
Marit Hoogenboom
Scientist
Marit obtained her PhD from the Erasmus Medical Center in Rotterdam where she focused on DNA damage repair and the transcription stress response. Marit joined Toxys in 2020 as an R&D scientist, using her expertise to further develop and implement novel toxicity assays. Marit co-developed the TubulinTracker and MutaTracker assays and is currently study director for MutaTracker.
Alison Idemudia
Assistant Scientist
Alison obtained her master’s degree in Biomolecular sciences, with a specialization in biochemistry, at the Vrije Universiteit Amsterdam. During her thesis internship Alison worked on characterizing an iPSC-derived in vitro model intended for assessment of chemical-induced nephrotoxicity.
Marije Meijer
Associate Scientist
Danielle Beije
Associate Scientist
Amy Gernaat
Assistant Scientist
David Schuster
Scientist
Marije Meijer
Assistant Scientist
Marije obtained her Bachelors of Life Science at the University of Applied Sciences Leiden. Previously, she worked at the OIE Reference Laboratory for Leptospirosis (also known as Expertise Centre for Leptospirosis) as a technician. In 2022, Marije joined Toxys where she has been performing ToxTracker and other mechanistic toxicity assays for our sponsors.
Danielle Beije
Assistant Scientist
Danielle obtained her Master’s degree in Bio-Pharmaceutical Sciences (Drug Discovery and Safety specialization) at Leiden University. During her thesis internship, she studied synergetic treatment combinations between various kinase inhibitors and selective transcriptional CDK inhibitors in triple-negative breast cancer cells. Previously, she worked as a research technician on pulmonary arterial hypertension at the Department of Physiology at Amsterdam UMC. In July 2024, Danielle joined Toxys as an assistant scientist performing the ToxTracker assay as well as other mechanistic toxicity assays.
Amy Gernaat
Assistant Scientist
Amy obtained her Master’s degree in Bio-Medical Sciences at Leiden University in 2024. During her minor internship, she studied the effect of alphavirus infection on host translational shut-off at the department of Medical Microbiology at the LUMC. In September 2023 Amy joined Toxys as an intern for her major internship, where she investigated the applicability of the ToxTracker assay for testing N-nitrosamines in vitro. As from July 2024, Amy joined Toxys as an assistant scientist performing the ToxTracker assay as well as other mechanistic toxicity assays.
David Schuster, PhD
Scientist
David obtained his PhD in Chemical and Environmental Toxicology at the University of Ottawa, conducting collaborative work with Health Canada. His doctoral work focused on utilizing both conventional methodologies and error-corrected next-generation sequencing (ecNGS) for high resolution mutagenicity assessment. Currently, he works as a Scientist at Toxys, applying his profound expertise on genotoxicity and mutagenic mechanisms for complex data analysis. His ongoing work is focusing on establishing advanced methodologies, such as the in vitro micronucleus assay and ecNGS, to expand the company’s scientific portfolio and refine toxicological testing capacities.
Developmental Toxicology
José Manuel Horcas Nieto
Director
Sabine Hartvelt
Study Director
Jing Fang
Scientist
Gaonan Zhang
Study Investigator
José Manuel Horcas Nieto
Director
Sabine Hartvelt
Study Director
Jing Fang
Scientist
Gaonan Zhang
Study Investigator
Gaonan obtained her first BSc in Agriculture from Shenyang Agriculture University and her second BSc in Life Science from HAN University of Applied Sciences. She performed her internships at the departments of Dermatology and Human Genetics at Radboud UMC in Nijmegen. Before joining Toxys in 2020, Gaonan worked as a DNA sequencing technician. At Toxys, Gaonan is performing ReproTracker, ToxTracker and other mechanistic toxicity assays for our sponsors.
Connor Philippo
Associate Scientist
Lois Stokkers
Assistant Scientist
Luuk Blokland
Assistant Scientist
Connor Philippo
Assistant Scientist
Lois Stokkers
Assistant Scientist
Luuk Blokland
Assistant Scientist
Investigative Toxicology
Tamara Meijer
Study Director
Eva de Tombe
Study Investigator
Bensu Tangil
Assistant Scientist
Quinty Walschots
Assistant Scientist
Tamara Meijer
Study Director
Tamara holds a Master’s degree in Drug Discovery and Safety (specialisation Drug Disposition and Safety Assessment) from the Vrije Universiteit Amsterdam (VU). During her Master’s internship, she investigated the impact of various chemicals on the mitochondrial function in vitro. She continued her scientific journey as a PhD candidate in Molecular Toxicology at the VU, focusing on the application of New Approach Methodologies to assess chemical-induced nephrotoxicity. In 2024, she joined Toxys as a Scientist and now works as Study Director in the investigative toxicology team.
Eva de Tombe
Assistant Scientist
Eva obtained her Bachelors and Masters degree in Bio-Pharmaceutical Sciences (Drug Discovery and Safety specialization) at Leiden University. During her thesis internship, she investigated the mechanism of bile salt induced apoptosis in cystic fibrosis with mouse cholangiocyte organoids at the Erasmus Medical Centre in Rotterdam. During an earlier internship, she worked on the development of multicolor HepG2 BAC reporter cell lines at the Leiden Academic Centre for Drug Research (LACDR). In January 2023, Eva joined Toxys as an assistant scientist performing the ToxTracker assay as well as other cell-based toxicity tests.
Bensu Tangil
Assistant Scientist
Bensu received her Bachelor’s in Biology at the University of San Francisco and received her MSc in Biology at Wageningen University. During her master’s thesis, she helped develop an in vitro chemical testing model for invertebrates in the department of Ecotoxicology. Prior to Toxys, she worked as a Research Assistant at VitroLabs, where she supported multiple projects on bovine tissue culture for lab grown leather. She joined the ToxProfiler team in April 2024 as an Assistant Scientist, due to her passion for toxicology and reducing animal testing.
Quinty Walschots
Assistant Scientist
Quinty obtained her master’s degree in Bio-Medical Sciences at Leiden University. During her master’s internship, she worked on the validation of an hiPSC-derived in vitro neuronal model for schizophrenia, at the department of Psychiatry at the Erasmus MC. In September 2025, Quinty joined Toxys as an Assistant Scientist in the ToxProfiler team.
Data Science
Tom Zwetsloot
Associate Scientist
Yusuf Hussien
Data Scientist
Tom Zwetsloot
Associate Scientist
Tom holds a Bachelor’s degree from the Leiden University of Applied Science in Biology and biomedical sciences. After his graduation, Tom held the position of Research Technician at the Leiden University Medical Center, department of anatomy and embryology. In his role as research technician he worked on stem cell differentiation. Tom joined Toxys in 2017 where he applies his experience in stem cell research and data analysis.
Yusuf Hussien
Data Scientist
Yusuf obtained his PhD in Bioinformatics and Genetic Toxicology from Swansea University, where he researched drug analysis and visualization strategies using computational New Approach Methodologies (NAMs) to derive Points of Departure (PoDs) across multiplexed toxicological assays. Currently, he works as a Data Scientist at Toxys, applying his expertise in programming languages like R and Python to evaluate and visualize toxicological datasets. His contributions support the ongoing development and refinement of scientific tools and toxicological paradigms.
Support
Marlon Dijkshoorn
Financial Director
Jacqueline Blonk
Laboratory Manager
Marianne Brummelkamp
Office Manager
Marlon Dijkshoorn
Financial Director
Having more than 25 years of experience in financial management from large enterprises to venture funds and small technology companies, Marlon acts as part time CFO for Toxys. From 1999 to 2004 Marlon was CFO for Life Science Partners assisting in the establishment of Funds I and II. During 2005 Marlon established Finmar B.V. a boutique financial advisory and management service for SMEs in the health and medical sectors. Marlon provides financial planning, tax and strategic support for SMEs in the early phases. Having experience of sitting on both sides of the risk capital table Marlon provides critical support in raising capital investments and delivering timely and high quality information to both management and shareholders. Marlon holds a degree in Business Economy from the Erasmus University.
Jacqueline Blonk
Laboratory Manager
Jacqueline joined Toxys in 2023 as Laboratory Manager. She studied Biology and medical laboratory sciences at Hogeschool Rotterdam and she has 28 years of laboratory experience in various companies.
Marianne Brummelkamp
Office Manager
Sales & Marketing
Aaron Boswell
Director BD & Sales
Katarina Spencer
Manager BD & Sales
Noelia Muñoz Martín
Marketing Manager
Aaron Boswell
Director BD & Sales
Aaron has 15+ years of experience at the intersection of science and commerce, with a background in genomics, error-corrected sequencing, and applications in cell therapy, oncology, and genetic toxicology. He supports Toxys customers throughout the United States. Aaron holds a B.S. in Molecular, Cellular and Developmental Biology and an MBA from the University of Washington.
Elias Halkes-Wellstead
Director BD & Sales
Elias has an MSc in Genetic Toxicology, a strong commercial background in driving both US and European sales as well as first-hand experience utilizing ToxTracker.
Katarina Spencer
Manager BD & Sales
Katarina joined Toxys in November 2024 as part of the Business Development and Sales team, where she leverages her scientific background and industry experience to support the company’s growth and partnerships. She holds an MSc in Genetics from Stellenbosch University in South Africa, where her research focused on using CRISPR/Cas technology to enhance virus resistance in grapevine. Prior to joining Toxys, she worked as a Study Director at Charles River Laboratories in Veszprém, Hungary, and Eurofins BioPharma Product Testing in Munich, Germany, conducting in vitro and genetic toxicology studies. Being part of Toxys is especially meaningful to her, as it allows her to contribute to developing safer products while reducing animal use in toxicity testing.
Tulya Kavaklioglu
Marketing Manager
Tulya has a combined background in science (molecular biology & genetics, neuroscience) and marketing. Prior to joining Toxys in 2024, she first worked as a researcher in Nijmegen at the Max Planck Institute for Psycholinguistics, then as a freelance marketer working with different companies in the Netherlands and Belgium. Tulya strives to bring a strategic approach to marketing and help Toxys grow.
Our sales consultants provide us with their expertise and business development support.
Hanna Frykman
Director BD & Sales
Ruairí Mac Síomóin
Japan Liaison
Hanna Frykman
Director BD & Sales
Hanna works for Toxys since 2020 as Independent Consultant in Business Development and Sales. She has vast experienced in sales, marketing and business development demonstrated in a history of working in the life science and start-up industry on national and international arena. Previously Hanna worked at the Swedish life science company SenzaGen where she was building up marketing, communication and sales from start-up through an IPO.
Hanna has done her Master studies at Lund University in Physical Geography and minor in General Business Studies, she did her Sales education in Dublin and followed up with Strategic Marketing education at IHM Business School in Sweden.
Ruairí Mac Síomóin
Japan liaison
Based in Japan, Ruairí is our primary point of contact for Toxys’s Japanese customers and interested parties. With over 25 years’ experience in the pharma / life sciences field, Ruairí provides a strong connection to the Japanese market, allowing Toxys to expand its reach in Asia. Ruairí received his M.Sc. from the Institute of Medical Science of the University of Tokyo and his B.Sc. from the Moyne Institute of Preventative Medicine at Trinity College, Ireland. Ruairi has previously worked at Chugai Pharmaceutical Co. Ltd. in Tokyo and Amersham Biosciences Japan (now GE Healthcare). His academic and industry research experience has been in the infectious disease and oncology areas.
Curious to learn more about what it’s like to work at Toxys?
Visit our career page.
