CD19 and acute lymphoblastic leukemia: In 2017, Gardner et al. published the results of a phase I trial in which 43 children and young adults (between 1 and 27 years old) suffering from relapsing/remitting B-ALL were treated with a CAR-T-cell product, which had a defined composition of 1:1 CD4+/CD8+ CAR-T-cells (targeting CD19).