CD19 and acute lymphoblastic leukemia: As expected, TG-1801, but not B6H12-mediated target occupancy, was highly dependent on CD19 expression, as shown when using the T-ALL-derived, CD19-negative, Jurkat cells, in which no significant CD47 blockade was detected with TG-1801 at doses as high as 2 μg/mL, contrasting with the sustained binding of B6H12 at the same concentration (Figure 1A, right and left panels).