A subset of T-ALL/T-LBL patients upregulates PIM1 expression in response to IL7. (A) PDX spleen samples were stimulated with 100 ng/mL IL7 for 30 minutes, after which phosphorylation sites were fixed with methanol and pSTAT5 (Tyr 694) was measured by flow cytometry. (B) CD127 protein expression levels, analyzed by flow cytometry, for 11 PDX spleen samples. (C) PDX spleen samples were stimulated with 50 ng/mL IL7 for 24 hours and were subsequently collected for RNA isolation. PIM1 messenger RNA (mRNA) expression levels are shown, measured by quantitative RT-PCR (RT-qPCR). (D) A PDX model of PDX#6 was established, after which 3 mice per group were treated for 2 weeks (5 days on/2 days off) with either 30 mg/kg AZD1208 or 100 mg/kg PIM447 or their respective vehicles. The percentages of human CD45⁺ (%hCD45⁺) leukemic blasts in peripheral blood (PB) are shown per group for 3 time points. (E) PDX#6 mice were euthanized after 2 weeks of treatment with either AZD1208 or PIM447. Spleen weights are shown per treatment group. (F) Ex vivo treatment of PDX#6 spleen cells. Fifty thousand cells were treated per condition for 72 hours in 10% RPMI supplemented with 10 ng/mL IL7, 50 ng/mL stem cell factor (SCF), 20 ng/mL FLT3, and 100 ng/mL IL2, in duplicate. Adenosine triphosphate (ATP) content was measured by means of a CellTiter-Glo viability assay. CNRQ, calibrated normalized relative quantity; IC50, 50% inhibitory concentration; PE, phycoerythrin.