CD19 and acute lymphoblastic leukemia: Shah et al., who developed a novel CD22-targeted/4-1BB CAR T-cell and tested it in a phase I dose–escalation trial in children and young adults with R/R CD22 hematologic malignancies, described a dose-dependent antileukemic response in CD19-negative/dim or CD191 relapsed ALL patients with an acceptable toxicity profile that included limited CRS, minimal neurotoxicity, and an effective signal that was not altered by earlier CD19 targeting.