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Targeting mutant p53 in ALL
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BCD
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GHI
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Figure 6. Anti-leukemia activity of APR-246 and synergy with genotoxic therapy in TP53-mutated acute lymphoblastic leukemia in vivo. (A) Schematic representa- tion of the experimental procedure: endpoint analysis assessing leukemia loads in differently treated recipients. (B-D) Dose-dependent reduction of leukemia load in bone marrow (BM) (B), spleen (S) (C) and central nervous system (CNS) (D) upon treatment of mice bearing TP53mut-4 (mutation R175H) acute lymphoblastic leukemia (ALL) with solvent or increasing doses of APR-246 for 3 weeks as indicated (n=3 recipients per group, except n=2 for BM 100 mg/kg). Student t-test, *P<0.05; n.s., not significant. (E) Restoration of p53 wildtype conformation upon in vivo APR-246 therapy, immunoprecipitation (IP: anti-wt p53 specific antibody PAb1620, western blot: anti-p53 antibody DO-7, light chain-specific goat anti-mouse peroxidase conjugated binding protein, GAPDH as a loading control), and (F) dose-dependent induction of p53 transcriptional targets PUMA and p21 (western blot, GAPDH as a loading control). (G-I) Significant reduction of leukemia load in bone marrow (BM) (G), spleen (S) (H) and central nervous system (CNS) (I) upon treatment of TP53mut-3 (mutations R248Q, R213X) ALL-bearing mice with APR-246 (APR, 100 mg/kg) or solvent (CTRL) for 3 weeks, n=6 mice per group, Student t-test, *P<0.05. (J) Schematic representation of the experimental procedure: survival analysis. (K) Superior survival of animals treated with APR-246 (APR, 50 mg/kg, 3 weeks, days 1-5; n=6) as compared to doxorubicin (DOX, 2 mg/kg, 3 weeks, day 1; n=7) or vehicle (CTRL, 3 weeks, days 1-5; n=7) (P<0.0001); and synergy of the combination of APR-246 and doxorubicin (COMBI, APR-246, 50 mg/kg, days 1-5, and doxorubicin, 2 mg/kg, day 5; n=7) leading to increased survival as compared to APR-246 treatment alone (P=0.0005). Kaplan-Meier analysis, log-rank test.
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