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A. Chaturvedi et al.
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Figure 1. Mutant IDH1 inhibitor BAY1436032 and azacitidine synergize to inhibit human IDH1 mutant acute myeloid leukemia cells ex vivo. (A) Inhibition of colony
in previous experiments) with varying concentrations of azacitidine in colony forming assays using primary human acute myeloid leukemia (AML) cells with wild-type or mutant IDH1. The graph represents the proportion of colonies relative to cells treated with BAY1436032 at 100 nM (mean ± standard error of the mean). From the six patients with IDH1 mutant AML, four harbored an IDH1 R132H mutation and one each an IDH1 R132C and IDH1 R132G mutation. (B) Proportion of viable cells in S phase of the cell cycle after treatment with BAY1436032 (100 nM) or azacitidine (100 nM) or the combination of both relative to DMSO-treated cells (mean ± standard error of the mean). From the 5 patients with IDH1 mutant AML, 3 harbored an IDH1 R132H mutation and 1 each an IDH1 R132C and IDH1 R132G. (C) A representative fluorescence-activated cell sorting plot of IDH1 wild-type and IDH mutant primary AML cells treated ex vivo with either vehicle, BAY1436032, azacitidine or BAY1436032 and azacitidine in combination. (D) Inhibition of colony formation after treat- ment with serial dilutions of azacitidine and BAY1436032, alone or in combination using primary human IDH1 mutant AML cells. Five patients harbored an IDH1 R132H and one an IDH1 R132C mutation. (E) Isobologram analysis of the combination of azacitidine and BAY1436032 in IDH1 mutant AML patient cells. The indi- vidual doses of azacitidine and BAY1436032 to achieve 90% growth inhibition (effective dose [ED] or fraction affected [Fa]=0.9), 75% growth inhibition (ED 75 or Fa=0.75), and 50% growth inhibition (ED 50 or Fa=0.5) were plotted on the x- and y-axes. Combination index (CI) values calculated using CompuSyn software is
formation by combining BAY1436032 (100 nm, corresponding to the IC
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depicted in the graph. A CI of 1 indicates an additive effect, a CI <1 a synergistic effect and a CI >1 antagonism. Wt: wild-type, mut: mutant.
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haematologica | 2021; 106(2)