Lymphomas, like most other cancers, consist of multiple distinct cancer cell populations within each patient. These tumour subpopulations have distinct genetic and biological characteristics leading to different drug response profiles.  We will characterise these tumour subpopulations in aggressive lymphoma on multiple biological levels including gene mutations, gene expression, protein abundance, surface protein profiles, and drug response.  Using the in-depth characterisation of subpopulations in the discovery cohort we will investigate large clinical patient cohorts with multiparametric immunofluorescence and describe the association of subclonal histology and response to chemotherapy.  The improved understanding of tumour subpopulations and their impact on therapy efficacy combined with the ability to detect those subpopulations in diagnostic biopsies using multiparametric immunofluorescence has the potential to improve treatment stratification and thereby patient survival while reducing side-effects and treatment costs.   We will perform in-depth interviews with patients treated in our centers for personalised medicine to optimise the communication of increasingly complex diagnostic and therapeutic procedures in personalised medicine.  These data will be complemented by quantitative surveys to create communication guidelines for personalised medicine.