The research of Henk-Jan Guchelaar focuses entirely on ‘personalised therapeutics’. The discovery of pharmacogenetic biomarkers in cancer, the implementation of these biomarkers in clinical practice and the development of personalised therapies are the central themes within his field of research. This topic is considered very important in Europe and fits perfectly within the National Science Agenda route ‘personalised medicine’. In 2016, Guchelaar started a European collaboration project (Horizon 2020) which measures the effects of adapting drug prescriptions based on pharmacogenetic biomarkers using pharmacogenetic guidelines on treatment outcome and health care costs. In 2017 he has, in collaboration with several departments of the LUMC, the Leiden Academic Center for Drug Research (LACDR) and a number of companies at the BioScience Park in Leiden, initiated the ‘Leiden Network for Personalised Therapeutics’ (LNPT). Within this network fundamental and clinical researchers closely collaborate in the field of individualised therapy development.