FOLR1 and acute myeloid leukemia: Using the FOLR1-directed CAR with the intermediate spacer, we further tested the target specificity of FOLR1-directed CAR T cells against FOLR1-positive (C/G-CB [taken after >9 weeks in EC coculture], WSU-AML, Kasumi-1 FOLR1+) and FOLR1-negative (Kasumi-1) cells.