CD19 and acute lymphoblastic leukemia: Comparing the killing capacity of CD19‐293, CD19‐63‐293 (with CD19‐scFv‐CD8‐CD63 targeting module), and CD19‐81‐293 (with CD19‐scFv‐CD8‐CD81 targeting module) cells (Figure S14, Supporting Information) revealed that both CD19‐63‐293 and CD19‐81‐293 cells exhibited potent target killing efficacy and efficiently depleted CD19 in B‐ALL cells (Figure S15, Supporting Information), indicating that the function of targeting modules was not compromised by structural optimization.