Thus far, two TCEs have been clinically approved—catumaxomab, an EPCAM/CD3 bispecific, for malignant ascites and blinatumomab, a CD19/CD3 bispecific, for acute lymphoblastic leukemia (ALL)20, which has sparked efforts to advance additional TCEs targeting both hematologic and solid tumor indications. This evidence concerns the gene CD19 and acute lymphoblastic leukemia.