City of Hope Beckman Research Institute and Medical Center 1 article published in JoVE Cancer Research In Vitro Tumor Cell Rechallenge For Predictive Evaluation of Chimeric Antigen Receptor T Cell Antitumor Function Dongrui Wang1,2, Renate Starr1, Darya Alizadeh1, Xin Yang1, Stephen J. Forman*1, Christine E. Brown*1 1Department of Hematology & Hematopoietic Cell Transplantation, T Cell Therapeutics Research Laboratory, City of Hope Beckman Research Institute and Medical Center, 2Irell and Manella Graduate School of Biological Sciences, City of Hope Beckman Research Institute and Medical Center Here, we describe an in vitro co-culture method to recursively challenge tumor-targeted T cells, which allows for phenotypic and functional analysis of antitumor T cell activity.