Fig. 6

Nelarabine combined with ZSTK-474 is able to induce a marked cytotoxic effect in relapsed T-ALL patients with upregulated PI3K signaling. a MTT assays of lymphoblasts from relapsed T-ALL patients (Pts) with activated PI3K signaling treated with nelarabine for 72 h. Data shown are the mean of at least two different experiments ± SD. b Flow cytometric cell count with eBeads123/PI staining of T-ALL blasts treated with nelarabine alone or combined with ZSTK-474 for 24, 48,72 h. c Flow cytometric analysis of Annexin V-FITC/PI of T-ALL blasts treated with nelarabine alone or combined with ZSTK-474. The percentages of early apoptotic cells (Annexin-V FITC⁺/PI⁻; bottom right quadrant) and late apoptotic/necrotic cells (Annexin-V FITC⁺/PI⁺; top right quadrant) are plotted. The histograms are representative of two separate experiments. d Cell viability assays of lymphoblasts from relapsed T-ALL patients treated for 72 h with increasing concentrations of nelarabine alone or combined with the pan PI3K inhibitor ZSTK-474 at fixed ratios. Results are the mean of two different experiments ± SD. e, f Flow cytometric analysis documenting a decrease of p-AKT (Ser473) (e) and Bcl2 (f) levels, respectively, in response to the combination of nelarabine and ZSTK-474 at the indicated concentrations for 48 h. The histograms are representative of two separate experiments