Alexander Michels, Paul-Ehrlich-Institut, Langen, Germany, provides an overview of mouse models currently used in preclinical chimeric antigen receptor (CAR)-T cell studies. Humanized mouse models may not be entirely representative of the human immune system in terms of cell count, activation sequences and cell phenotypes. As syngeneic mouse models consist mouse cancer cell lines, human vectors and receptors must be adapted to mice, though the risk of graft versus host disease (GvHD) is lower. This interview took place at the International Conference on Lymphocyte Engineering (ICLE) 2022.