Jiang and colleagues showed that IDH1 and IDH2 proteins are required to generate NADPH in the mitochondria, enabling cells to mitigate mitochondrial ROS and maximize growth.31 High concentrations of HMS-101 may interfere with the oxidative function of IDH1/2 thus reducing NADPH and increasing reactive oxygen species in the mitochondria, which inhibits cell growth. 2HG production, induced cellular differentiation and prolonged survival in a syngeneic mutant IDH1 mouse model and a patient-derived human AML xenograft model in vivo. Cells treated with HMS-101 showed a marked upregulation of the differentiation-associated transcription factors CEBPA and PU.1, and a decrease in cell cycle regulator cyclin A2. In addition, the compound attenuated histone hypermethylation. Together, HMS-101 is a unique inhibitor that binds Eugenol to the active site of IDH1mut directly and is active in IDH1mut preclinical models. Introduction Mutations in the active site arginine residue (R132) of (mutations. Treatment was started with HMS-101 or solvent intraperitoneally once daily starting on day 45 after transplantation and continued until death at a dose of 40 mg/kg body weight. At 18 weeks, the R-2HG concentration in serum declined by 2.9-fold in HMS-101 treated mice (Figure 6A) and at 22 and 26 weeks after transplantation, the proportion of CD14, a marker of monocytic differentiation, on human cells was significantly higher in HMS-101 treated mice compared to controls (Figure 6B). Median survival was significantly prolonged by 20 days in HMS-101 treated mice (median survival 210 vs 230 days, Figure 6C). In an impartial, second PDX model, which harbored p.R132Hp.R882H, p.A72T, and p.T288CfsTer12 mutations, the percentage of human CD45+ cells in the peripheral Eugenol blood of mice increased in vehicle-treated animals but was essentially absent in HMS-101 treated mice (Supplementary Determine S11A). In an impartial third PDX model, NSG mice were transplanted with primary p.W288CfsTer12 p.G1931D mutant Eugenol AML cells. Both HMS-101 and vehicle-treated mice had comparable percentages of human CD45+ cells in peripheral blood of mice (Supplementary Physique S11B). There was no significant difference between Rabbit polyclonal to PAWR the number of colonies formed by IDH1mut/NRASwt and IDH1mut/NRASmut primary AML cells in the presence of HMS-101 compared to control treated cells, suggesting that NRASmut is not predictive of response to HMS-101. Further, HMS-101 did not inhibit the colony formation of mutant AML patient cells indicating specificity towards mutant IDH1 (Physique 6D). Open in a separate window Physique 5 HMS-101 inhibits proliferation, induces myeloid differentiation and prolongs survival in leukemic mice in vivo(A) Unbound HMS-101 plasma concentrations in C57BL6/J mice treated with a daily dose of 16, 40 and 160 mg/kg HMS-101 for 9 days. Plasma was collected before Eugenol the next injection on day 1, day 2, day 7 and day 8 (mean SEM of 5 animals/dose). The dashed line indicates the in vitro IC50 in HoxA9 IDH1mut cells. (B) Absolute concentration of R-2HG in the serum of mice transplanted with HoxA9 IDH1mut cells and treated with HMS-101 at a dose of 40mg/kg for 8 weeks (mean SEM). (C) Engraftment of HoxA9 IDH1mut cells in peripheral blood of mice treated with either vehicle (left) or HMS-101 at a dose of 40mg/kg at the indicated time points (mean SEM). (D) White blood cell count, (E) hemoglobin level, and (F) platelet count in peripheral blood at different time points after the start of treatment with vehicle or HMS-101 at a dose of 40mg/kg (mean SEM). (G) Morphology and fluorescence of peripheral blood cells from HoxA9+IDH1mut transplanted mice treated with vehicle (left) or HMS-101 (right) at 15 weeks after treatment (400X initial magnification). Mutant IDH1 was expressed from a retroviral vector that co-expresses GFP. Thus, GFP positive cells indicate IDH1 mutant leukemic cells. (H) Survival of HoxA9+IDH1mut transplanted mice treated with either vehicle or HMS-101. * P 0.05, **P 0.01, *** P .001 # week 15 after transplantation or at death if the mouse died before week 15 due to leukemia Open in a separate window Figure 6 HMS-101 induces differentiation in primary IDH1 mutant AML cells.(A) Absolute concentration of R-2HG in the serum of PDX-IDH1R132C mice treated with HMS-101 at a dose of 40mg/kg or vehicle for 18 weeks (mean SEM). (B) Percentage of human CD14+ cells in peripheral blood of Eugenol PDX-IDH1R132C mice at different time points with either vehicle or HMS-101 at dose of 40mg/kg (mean SEM). (C) Survival of PDX-IDH1R132C transplanted mice treated with either vehicle or HMS-101. (D) Colony forming cell assay of IDH1/2 wt, IDH1mut/NRASwt, IDH1mut/NRASmut and IDH2mut primary cells from AML patients treated with HMS-101 relative.
