Adoptive transfer of T and natural killer (NK) cells expressing chimeric antigen receptors (CARs) has shown remarkable clinical efficacy against advanced B cell malignancies. However, many patients do not benefit from this treatment either because they do not respond or subsequently relapse. It is therefore of paramount importance to understand the mechanisms of tumour resistance to CAR T/NK cells. Prior to initiating clinical trials, model systems in which engineered immune cells can be characterized and tested for their potency and safety should be in place. To date, few models perfectly recapitulate the human immune system and tumour microenvironment, and some models have revealed CAR T/NK limitations that were contradicted or missed entirely in other models. Thus, careful model selection is a crucial step in evaluating CAR T/NK cell treatment and a major issue in the field of cancer immunotherapy. In this project, innovative preclinical human models that have been developed over the last years by our Teams (Dr. Donnadieu, Paris/ Prof. Hansmann and Hartmann, Frankfurt) will be implemented and optimized to enable advanced monitoring of CAR T/NK cell efficacy that we generate (Prof. Ullrich, Frankfurt). These assays include an ex vivo 4D human model that fully preserves the lymphoma environment and a microchannel system that enables to dissecting of engineered T and NK cell motility. Using these two models, our objectives are to monitor, using confocal fluorescent imaging techniques, early and late CD19 CAR T/NK cell responses as well as their abilities to kill malignant cells. The role played by suppressive cells and components contained within the lymphoma environment on CAR T/NK cell responses will also be investigated. Thus, we believe in significantly enriching the current state-of-the-art approaches for the evaluation and prediction of specific CAR immune cell-based therapeutics and overcoming resistance mechanisms. Finally, the results obtained during this project will allow further optimization of personalized immune cell-based therapy of lymphoma