A Phase I clinical trial (NCT03126864) investigated the feasibility and safety of autologous T-cells, modified to express a CD33-targeted CAR with 4-1BB and CD3ζ endo-domains and co-expressed with truncated human epidermal growth factor receptor (HER1t), in patients with r/r AML. The gene discussed is CD33; the disease is acute myeloid leukemia.