TKI response of BCR::ABL1–positive primary or PDX–expanded BCP-ALL samples using an ex vivo coculture assay. (A-C) Ex vivo response toward imatinib (A), dasatinib (B), and bosutinib (C). Violin plot of the AUC (y-axis) for pediatric (blue) and adult (red) BCR::ABL1–positive BCP-ALL samples (x-axis) cultured on mesenchymal stromal cells for 3 days. The thick black line represents the median, and the thin black lines represent the first quartile and the third quartile. (D) Correlation between the z-score of the AUC of imatinib, dasatinib, and bosutinib for pediatric and adult BCR::ABL1–positive BCP-ALL samples. (E) Relation of ex vivo TKI sensitivity with MRD at end of induction in patients started with imatinib treatment within 15 days from diagnosis. The box plots show the median z-score ± 1.5 interquartile range (IQR) in Tukey style. A Mann-Whitney U test was used to compare the z-score values between patients with a high MRD (≥10e-4) and a low MRD (<10e-4). (F) Relation of ex vivo drug sensitivity with occurrence of relapse in patients started with imatinib treatment within 50 days from diagnosis and with follow-up of at least 1 year from diagnosis, a relapse within 1 year from diagnosis, or a relapse after >1 year from diagnosis. One pediatric and 7 adult patients who died within 1 year of diagnosis in complete remission were excluded (supplemental Table 1). The box plots show the median z-score ± 1.5 IQR in Tukey style. A Mann-Whitney U test was used to compare the z-score values between patients who remained in CCR and those who relapsed. ima-dasa, imatinib-dasatinib; ima-bosu, imatinib-bosutinib; dasa-bosu, dasatinib-bosutinib; ns, not significant.