Presence Of Isocitrate Dehydrogenase 1 Mutation Research Articles

Clinical Outcomes After Progression on First-Line Therapies in IDH1 Mutated Versus Wild-Type Intrahepatic Cholangiocarcinoma Patients.

Isocitrate dehydrogenase-1 (IDH1) mutations occur in a significant proportion of intrahepatic cholangiocarcinomas (iCCAs). No data are available regarding the prognostic impact of IDH1 mutations in advanced iCCA patients after progression on first-line therapies. We investigated the role of IDH1 mutation in advanced iCCA after progression on first-line therapies. After progression on first-line therapies for advanced iCCA, consecutive patients were retrospectively collected. The IDH1 status was tested at baseline. This analysis aimed to examine the association between the presence of IDH1 missense mutations and survival outcomes in patients with advanced iCCA treated with a second-line therapy. The analysis included 119 patients; 56/119 (47%) were IDH1 mutated (IDH1m) and 63/119 (53%) were IDH1 wild type (IDH1 WT). At univariate analysis for overall survival (OS), the presence of IDH1 mutation was associated with a worse median OS (mOS; 8.2 vs. 14.1 months; hazard ratio [HR] 1.9, 95% confidence interval [CI] 1.2-3.0, p=0.0047). Patients harboring IDH1 mutations showed a worse objective response rate (ORR) compared with patients without IDH1 mutation, whereas no significant differences in disease control rate (DCR) were found. Multivariate analysis confirmed IDH1 mutations as an independent negative prognostic factor for OS (HR 1.7, 95% CI 1.1-2.7, p=0.0256). By evaluating only patients receiving FOLFOX as second-line therapy, no statistically significant differences were found in terms of both OS and PFS between IDH1m and IDH1WT patients. In this subset of patients, those harboring an IDH1 mutation showed a worse ORR and DCR compared with those without. Finally, at univariate analysis for OS from third-line treatment, the presence of an IDH1 mutation was associated with a trend toward a worse mOS (6.0 vs. 11.9 months; HR 1.6, 95% CI 0.8-3.2, p=0.25). The present analysis constitutes the first evidence of a negative prognostic impact of IDH1 mutations in a cohort of patients treated after progression on first-line therapies in contrast to IDH1 inhibitors.

Adaptive Evolution of the GDH2 Allosteric Domain Promotes Gliomagenesis by Resolving IDH1R132H-Induced Metabolic Liabilities.

Hotspot mutations in the isocitrate dehydrogenase 1 (IDH1) gene occur in a number of human cancers and confer a neomorphic enzyme activity that catalyzes the conversion of α-ketoglutarate (αKG) to the oncometabolite D-(2)-hydroxyglutarate (D2HG). In malignant gliomas, IDH1R132H expression induces widespread metabolic reprogramming, possibly requiring compensatory mechanisms to sustain the normal biosynthetic requirements of actively proliferating tumor cells. We used genetically engineered mouse models of glioma and quantitative metabolomics to investigate IDH1R132H-dependent metabolic reprogramming and its potential to induce biosynthetic liabilities that can be exploited for glioma therapy. In gliomagenic neural progenitor cells, IDH1R132H expression increased the abundance of dipeptide metabolites, depleted key tricarboxylic acid cycle metabolites, and slowed progression of murine gliomas. Notably, expression of glutamate dehydrogenase GDH2, a hominoid-specific enzyme with relatively restricted expression to the brain, was critically involved in compensating for IDH1R132H-induced metabolic alterations and promoting IDH1R132H glioma growth. Indeed, we found that recently evolved amino acid substitutions in the GDH2 allosteric domain conferred its nonredundant, glioma-promoting properties in the presence of IDH1 mutation. Our results indicate that among the unique roles for GDH2 in the human forebrain is its ability to limit IDH1R132H-mediated metabolic liabilities, thus promoting glioma growth in this context. Results from this study raise the possibility that GDH2-specific inhibition may be a viable therapeutic strategy for gliomas with IDH mutations.Significance: These findings show that the homonid-specific brain enzyme GDH2 may be essential to mitigate metabolic liabilities created by IDH1 mutations in glioma, with possible implications to leverage its therapeutic management by IDH1 inhibitors. Cancer Res; 78(1); 36-50. ©2017 AACR.

Genetics and Epigenetics of Glioblastoma: Applications and Overall Incidence of IDH1 Mutation.

Glioblastoma is the most fatal brain cancer found in humans. Patients suffering from glioblastoma have a dismal prognosis, with a median survival of 15 months. The tumor may develop rapidly de novo in older patients or through progression from anaplastic astrocytomas in younger patients if glioblastoma is primary or secondary, respectively. During the past decade, significant advances have been made in the understanding of processes leading to glioblastoma, and several important genetic defects that appear to be important for the development and progression of this tumor have been identified. Particularly, the discovery of recurrent mutations in the isocitrate dehydrogenase 1 (IDH1) gene has shed new light on the molecular landscape in glioblastoma. Indeed, emerging research on the consequences of mutant IDH1 protein expression suggests that its neomorphic enzymatic activity catalyzing the production of the oncometabolite 2-hydroxyglutarate influences a range of cellular programs that affect the epigenome and contribute to glioblastoma development. One of the exciting observations is the presence of IDH1 mutation in the vast majority of secondary glioblastoma, while it is almost absent in primary glioblastoma. Growing data indicate that this particular mutation has clinical and prognostic importance and will become a critical early distinction in diagnosis of glioblastoma.

BI-07 * HYPERPOLARIZED [1-13C] GLUTAMATE: A METABOLIC IMAGING BIOMARKER OF IDH1 MUTATIONAL STATUS IN GLIOMA

Mutations of the isocitrate dehydrogenase 1 (IDH1) gene are among the most prevalent in low-grade glioma and secondary glioblastoma, represent an early pathogenic event and are being considered a promising therapeutic target. Consequently, non-invasive imaging methods are needed to monitor IDH1 status. Amongst these, we previously demonstrated the use of 13C MR spectroscopic imaging of hyperpolarized [1-13C] α-ketoglutarate (α-KG) to non-invasively assess IDH1 status through the detection of the conversion of hyperpolarized α-ketoglutarate to 2-hydroxyglutarate (2-HG) catalyzed by mutant IDH1. Importantly, in addition to its oncogenic role, IDH1 mutation is also associated with global modulations in metabolism. Interestingly, a study recently uncovered a relationship between presence of IDH1 mutation and decreased activity of the branched chained amino acid transaminase 1 (BCAT1) enzyme, which transaminates amino acids while converting α-KG to glutamate. Given this new study, we decided to expand on our previous findings and investigated the potential of hyperpolarized α-KG as an imaging probe to monitor BCAT1-driven α-KG-to-glutamate conversion and its modulation in the presence of IDH1 mutation. We investigated two isogenic glioblastoma lines that differed only in their IDH1 status, and performed experiments in live cells and in vivo in rat orthotopic tumors. Following injection of hyperpolarized α-KG, hyperpolarized glutamate production was detected both in cells and in vivo, and the level of hyperpolarized glutamate was significantly lower in mutant IDH1 cells and tumors compared to their IDH1-wild-type counterparts. Importantly however, the observed drop in hyperpolarized glutamate was likely mediated not only by a drop in BCAT1 activity, but also by reductions in aspartate transaminase and glutamate dehydrogenase activities, suggesting additional metabolic reprogramming at least in our model. Hyperpolarized glutamate could thus inform on multiple mutant IDH1-associated metabolic events and serve as a secondary metabolic biomarker of IDH1 mutational status in gliomas, together with 2-HG.

P04.14 * IDH1 MUTATION IN LOW-GRADE GLIOMAS RELATED TO EPILEPSY AS INITIAL SYMPTOM

Seizures are common in low-grade gliomas (LGGs) and are highly correlated with the presence of the isocitrate-dehydrogenase 1 mutation (IDH1m). We aimed to explore the correlation between the IDH1m in LGGs and the presence of epilepsy as initial symptom. METHODS: Observational retrospective study on 164 patients with LGGs (86 oligodendrogliomas, 41 astro-oligodendroglial tumors and 37 astrocytomas) of whom 71% had seizures as initial symptom, analyzed according to Fisher's exact and Mann Whitney test. RESULTS. There was no difference in age or brain tumor location in patient with or without seizures. Seizures were more frequent in the group of IDH1m (92/117; 78 %) vs. (27/47; 57.4%), p = 0.01. Fronto-insular location was more frequent in the group of IDH1m (75/117; 65%) vs (13/47; 27%), p = 0.01. There was no difference if analyzed by histological type of low-grade gliomas, except for oligodendrogliomas, in which seizures were more frequent with IDH1m 52/65 (80,0 %) p = 0.02. The average age of the IDH1m with seizures was not significantly higher: 41.5 yrs vs. 39.5 yrs without seizures, p = 0.27. The type of seizures simple/complex partial (64/117; 55%) vs. generalized (53/117; 45%) is similar regardless of the presence of IDH1m, p = 0.8 CONCLUSION. Epilepsy as initial symptom in oligodendrogliomas is associated with the presence of IDH1 mutation. Fronto-insular location is more frequent among IDH1 mutated LGGs. There is no difference in type of seizures among IDH1 mutated LGGs.