Figure 1. Effects of mutant-specific IDH1 inhibitor in endogenous IDH1 mutant cancer cells.
(A) R-2-HG levels in IDH1 mutant lines (MGG119 and MGG152 have IDH1R132H, HT1080 harbors IDH1R132C) measured by liquid chromatography-mass spectrometry (LC-MS) +/− mutant-specific IDH1 inhibitor (IDH1i 5 μM, 48 hr) in vitro. (B) Cell viability assay of cell lines after incubation with IDH1i (CellTiter-Glo, normalized to DMSO control). MGG lines were analyzed at day 9, HT1080 and 30T were analyzed at day 3. (C) Concentrations of mouse MGG152 orthotopic xenograft tissue IDH1i (upper panel) and R-2-HG (lower panel) measured by LC-MS. Data were acquired after 5-day oral gavage, 2×/day, of IDH1i (400 mg/kg, n=5) or vehicle (n=5). (D) Kaplan-Meier estimates of survival by treatment. SCID mice bearing MGG152 orthotopic xenografts were randomly assigned to oral gavage of IDH1i (red, 400 mg/kg 2×/day, n=6) or vehicle (black, 2×/day, n=6). Median survival with IDH1i, 46 days (95% CI; 42–50) and with vehicle, 46 days (95% CI; 45–48, p=0.79). (E) Western blot analysis of histone methylation marks in MGG152 (IDH1R132H) cells +/− IDH1i for 2 days or 10 months. MGG8, IDH1/2 wild-type. Actin, loading control. (F) Methylation-specific PCR (MSP) showing MGMT gene promoter methylation in MGG152 +/− IDH1i. P, passage number; U, unmethylated; M, methylated. (G) Genome-wide distribution of DNA methylation in MGG152 cells treated with DMSO or IDH1i (5 μM) for 2 days (R=0.996, p<0.001, left) and 10 months (R=0.989, p<0.001, right). (H) Cell viability assay (CellTiter-Glo) of MGG152 treated with DMSO or IDH1i (5 μM) for 12 months in vitro. Data were obtained at day 3 and normalized to DMSO control at day 0. (I) Kaplan-Meier estimates of survival after intracerebral implantation of pre-treated MGG152. Cells were incubated +/− IDH1i in vitro for the indicated cell passage number and then 1×105 cells were implanted into SCID mouse brains. Animals were then monitored for survival. In all panels: bars, +/− SEM; *, p<0.05. See also Figure S1.