Ron Mathijssen studied medicine at the Erasmus University Rotterdam for which he received his MD degree in 2000. Two years later he defended his thesis (cum laude) entitled: ‘Irinotecan: from Clinical Pharmacokinetics to Pharmacogenetics’. Subsequently, he became Internist, Medical Oncologist, and Clinical Pharmacologist. He is closely collaborating with national and international groups, supervises several PhD students, and published over 120 peer reviewed papers. In addition, he teaches students, reviews papers for many journals, and is a member of the Dutch Cancer Society scientific counsel. Finally, he is chair of the Dutch Pharmacology Oncology Group; a national collaboration to individualize the dose of anti-cancer drugs. Since 2013, he is a professor in Individualized Oncological Pharmacotherapy at the Department of Medical Oncology, heading the division of Translational Pharmacology. His main research is focused on ‘tailored therapy’ of systemic anti-cancer agents like taxanes, tamoxifen, irinotecan, tyrosine kinase inhibitors, and phase I drugs.