Mayo Clinic College of Medicine and Science 1 article published in JoVE Cancer Research Using CRISPR/Cas9 to Knock Out GM-CSF in CAR-T Cells Rosalie M. Sterner1,2, Michelle J. Cox3, Reona Sakemura3, Saad S. Kenderian2,3 1Mayo Clinic Medical Scientist Training Program, Mayo Clinic College of Medicine and Science, 2Department of Immunology, Mayo Clinic, 3Division of Hematology, Mayo Clinic Here, we present a protocol to genetically edit CAR-T cells via a CRISPR/Cas9 system.