In vivo VpreB1-ADC efficacy against an ETV6::RUNX1 B-ALL PDX model. NSG mice were transplanted through tail vein injection with 1 × 106 PDX B9 model cells. When 1% to 5% leukemia cells were detectable in the peripheral blood, mice were treated with VpreB1-ADC 2 mg/kg or PBS control (n = 10 mice per group) IP on days 1, 4, and 7. (A-C) After 48 hours from the completion of the therapy, 3 mice from each group were euthanized, femurs and spleens isolated, and leukemia burden assessed using either flow cytometry (human CD19 and CD45 antibodies) or IHC (human CD19). Representative flow cytometry plots (A) with quantification (B) and IHC (C) images are illustrated. ∗∗∗∗P < .0001. (D) The remaining mice were monitored for survival and Kaplan-Meier curves generated. The gray square indicates treatment duration. The log-rank (Mantel-Cox) test was used to compare the survival curves; ∗∗∗P < .001. H&E, hematoxylin and eosin.
