CD28 and acute myeloid leukemia: The systematic preclinical evaluation of CD33-directed CAR T cell constructs identified the CD33-targeted lintuzumab-based 2nd generation CAR construct (LIN-CD28-CD3Z) to be most efficacious (161) and led to the multicenter CD33-specifc CAR T cell trial (NCT03971799) for pediatric patients with relapsed and refractory AML.