Targeted Metabolomic Profiling in Acute Myeloid Leukemia with IDH2^R140 and IDH2^R172 Mutations

Introduction

Acute myeloid leukemia (AML) represents an aggressive bone marrow malignancy with diverse genetic abnormalities. The tumor cells, to support their own growth and proliferation, may alter metabolism 1) to accelerated glycolysis to provide energy/biosynthetic precursors and 2) to produce intermediates by active TCA cycle for synthesis of essential biomolecules [1]. Mutations of isocitrate dehydrogenase (IDH1/2) as frequent mutations (affecting approximately 20% of AML patients) cause the reduction of α-ketoglutarate to D-2-hydroxyglutarate instead of oxidative decarboxylation of isocitrate to α-ketoglutarate. IDH2 mutations occur almost exclusively in hematopoietic tumors. Whereas IDH2^R140 mutation is frequently accompanied by normal cytogenetics and NPM1 mutations, IDH2^R172 is frequently the only mutation detected in AML. In addition, IDH2^R172 confers a poor prognosis in patients with AML [2, 3].

The aim of this study was to characterize and uncover the differences in metabolism of AML patients with or without IDH2 mutations in diagnosis (the initial stage), in remission (after chemotherapy treatment), and before transplantation (after conditioning).

Methods

Serum metabolomics profiles were generated with samples obtained at diagnosis, in remission, and before transplantation from patients (n=20) treated in the Institute of Hematology and Blood Transfusion, Prague, Czech Republic. Patients were assigned in IDH2^WT (n=7) and IDH2^R140/ IDH2^R172 (n=7/6) groups. Targeted metabolomic profiling of 19 metabolites related mainly to TCA cycle and glycolysis was performed by LC-MS/MS.

Results

Using non-parametric randomized block analysis of variance (Friedman test) we found significant differences in levels of 13 metabolites among treatment periods for all AML patients. Moreover, when comparing each treatment periods for all patients, we found significantly decreasing levels of 12 metabolites between the initial stage and the period before transplantation. If we considered the division of patients into groups according to IDH2 mutations, we found significantly different levels of 4 metabolites among treatment periods for samples of patients with IDH2^R140,namely 2 metabolites of TCA cycle: isocitrate, succinate; and 3-hydroxybutyrate and urate. We obtained significantly different levels in the same number of other metabolites for IDH2^WT. In samples of patients with IDH2^R172 we found significantly different levels of 8 metabolites among treatment periods, namely 5 metabolites of TCA cycle: citrate, 2-hydroxyglutarate, succinate, fumarate, malate; 2 metabolites of glycolysis: 3-phosphoglycerate, phosphoenolpyruvate; and pyroglutamate of glutathione metabolism. Furthermore, using Nemenyi post-hoc test we ascertained significantly decreasing levels of named metabolites in IDH2^R140 and IDH2^R172 samples before transplantation with respect to the initial stages of AML (diagnosis).

Conclusion

Overall, this study identified significant changes in several metabolites of TCA cycle and glycolysis between initial and final treatment periods and also between remission and period before transplantation in AML patients. With respect to IDH2 mutations we found more significant changes in metabolites specifically in TCA cycle for IDH2^R172 patients relative to IDH2^R140. The results of our preliminary targeted metabolomic profiling of AML patients with IDH2 mutations are corresponding with the already described differences in morphological and genetic patterns in the patients and, moreover, support the classification of IDH2^R172 as separate AML subtype. Metabolomic profiling thus seems to be a new valuable tool providing additional important information.

Acknowledgment

This work was supported by the European Regional Development Fund and the state budget of the Czech Republic (project AIIHHP: CZ.02.1.01/0.0/0.0/16_025/0007428, OP RDE, Ministry of Education, Youth and Sports), by the project of the Ministry of Health, Czech Republic, 00023736, by Grant from the Academy of Sciences, Czech Republic, P205/12/G118, and by ERDF OPPK CZ.2.16/3.1.00/24001.

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[3] Meggendorfer M, Cappelli LV, Walter W, Haferlach C, Kern W, Falini B, Haferlach T. Leukemia. 2018;32(5):1249-1253.