Fig. 7. Mutant IL7R B-ALLs are sensitive to PI3K/mTOR and SK pharmacological inhibition.

a Dactolisib in vivo administration scheme. Leukemic cells (2 × 10⁵) were transferred into Rag−/−γc−/− hosts. b Leukemia cell frequency detected in blood 6 days after treatment (n = 10). Two-tailed, unpaired t-test. c Kaplan–Meier survival curves, and respective log-rank p value, of animals (n = 7 control; n = 6 dactolisib) treated with vehicle or dactolisib (30 mg/kg). d Z-score values of chemical screen library for kinase inhibitors tested in IL-3-dependent Ba/F3 cells stably transduced with mutant IL7R and cultured in the absence of IL-3. Each compound is represented by one dot. SKi is denoted in red. Dotted lines represent Z-score cut-off. e Immunoblot analysis of STAT5 phosphorylation in Ba/F3 cells pre-treated with SKi (10 µM) or DMSO for 2 h and then stimulated with either IL-3 (IL7R WT cells) or IL-7 (IL7R mutant cells). IL7R WT-transduced cells were used merely as transduction controls for IL7R mutant cells but express IL-3R and respond to IL-3. IL-7 was used in IL7R mutant cells to reinforce IL-7R signaling while keeping the same period (30′) of cytokine stimulation as in IL-3-stimulated cells. This experiment was repeated once with identical results. f Viability, evaluated by FSC × SSC flow cytometry discrimination, of IL-3-cultured IL7R WT cells or IL-7-cultured IL7R mutant Ba/F3 cells treated with SKi or DMSO for 72 h. g Viability of leukemia cells from three independent mice, as compared to healthy B cell precursor controls in the presence of IL-7, cultured with increasing concentrations of SKi for 12 h. Viability index is normalized to the control condition (DMSO). Average ± s.e.m. is shown for each concentration. h Viability (Annexin V/7AAD expression) of representative leukemia cells incubated with SK2 inhibitor Compound 55 (20 µM) or DMSO for 12 h. i Dose-dependent effect of Compound 55 on leukemia cell viability (n = 4; 2 PAX5 P80R and 2 Ph-like). j Compound 55 in vivo administration scheme. Leukemic cells (2 × 10⁵) were transferred into Rag−/−γc−/− hosts. k Kaplan–Meier survival curves and respective log-rank p value of animals treated with vehicle (n = 7) or Compound 55 (n = 6; 5 mg/kg). l–n Viability of mutant IL7R human PAX5 P80R primary B-ALL cells cultured with increasing concentrations of (l) Dactolisib, (m) Compound 49, or (n) Compound 55 for 48 h. Viability index is normalized to the control condition (DMSO). Lines represent average of the duplicates, which are shown, for each patient sample. Source data are provided as a Source Data file.