Catalan Institute of Oncology (ICO-L'Hospitalet) 1 article published in JoVE Cancer Research Testing Cancer Immunotherapeutics in a Humanized Mouse Model Bearing Human Tumors Jordi M. Lanis*1, Matthew S. Lewis*1, Hannah Strassburger1, Kristina Larsen1, Stacey M. Bagby2, Adrian T. A. Dominguez2, Juan A. Marín-Jiménez3, Roberta Pelanda1, Todd M. Pitts2, Julie Lang1 1Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver Anschutz Medical Campus, 2Division of Oncology, School of Medicine, University of Colorado Denver Anschutz Medical Campus, 3 This protocol outlines the generation of human immune system (HIS) mice for immuno-oncology studies. Instructions and considerations in the use of this model for testing human immunotherapeutics on human tumors implanted in this model are presented with an emphasis on characterizing the response of the human immune system to the tumor.