Project description:We profiled two IDH1 mutant glioma models, grown as intracranial xenografts, treated with an IDH1 inhbitor. One model, BT424, was responsive to IDH1 inhibition by compound treatement and also displayed more transcriptional changes in response to treatment. The other model, GB10, was not responsive to IDH1 inhibition and was transcriptionally quiet after treatment with compound.
Project description:Astrocytoma, oligodendroglioma, oligoastrocytoma, and ependymoma are the main histologic subtypes of glioma. The molecular character of these subtypes has profound implications for understanding their causes and treatment. We describe the epigenetic landscape of these tumor types using novel DNA methylation profiling tools. There is a robust association of methylation profile with tumor histology and IDH1 mutation status. Furthermore, tumors with IDH1 mutation independently predict a tumor hypermethylator phenotype, histology, TP53 mutation status, patient age, and survival. Integrating tumor epigenetic and genetic alterations, this work provides a critical step toward better defining the somatic nature of glioma which will have great potential to impact clinical approaches to disease. This work provides an important step forward in classification of malignant brain tumors using DNA methylation profiling, integrating knowledge regarding IDH1 mutation in gliomas. The epigenetic homogeneity of the IDH1 mutant subclass despite histologic diversity implies that IDH1 mutation is a “driver” or functional determinant of a distinct DNA methylation phenotype, suggesting a novel role for an altered metabolic profile in the brain. This association occurs across histologic subtypes and demonstrates a clear relationship between genetic alteration and epigenetic profile. Fresh frozen tumor tissues were obtained from the University of California San Francisco (UCSF) Brain Tumor Research Center tissue bank with appropriate institutional review board approval. Tumors were diagnosed between 1990 and 2003. Tumor samples were defined as secondary GBM if the patients had prior histological diagnosis of a low-grade glioma. Tumors had previously been reviewed by UCSF neuropathologists to assign histologic subtype and grade. Normal brain tissue samples were from cancer-free patients who underwent temporal lobe resection as treatment for epilepsy at UCSF.
Project description:Astrocytoma, oligodendroglioma, oligoastrocytoma, and ependymoma are the main histologic subtypes of glioma. The molecular character of these subtypes has profound implications for understanding their causes and treatment. We describe the epigenetic landscape of these tumor types using novel DNA methylation profiling tools. There is a robust association of methylation profile with tumor histology and IDH1 mutation status. Furthermore, tumors with IDH1 mutation independently predict a tumor hypermethylator phenotype, histology, TP53 mutation status, patient age, and survival. Integrating tumor epigenetic and genetic alterations, this work provides a critical step toward better defining the somatic nature of glioma which will have great potential to impact clinical approaches to disease. This work provides an important step forward in classification of malignant brain tumors using DNA methylation profiling, integrating knowledge regarding IDH1 mutation in gliomas. The epigenetic homogeneity of the IDH1 mutant subclass despite histologic diversity implies that IDH1 mutation is a “driver” or functional determinant of a distinct DNA methylation phenotype, suggesting a novel role for an altered metabolic profile in the brain. This association occurs across histologic subtypes and demonstrates a clear relationship between genetic alteration and epigenetic profile.
Project description:The AVAglio and RTOG-0825 randomized, placebo-controlled phase III trials in newly diagnosed glioblastoma reported prolonged progression-free survival (PFS), but not overall survival (OS), with the addition of bevacizumab to radiotherapy/temozolomide. To establish whether certain patient subgroups derived OS benefit from the addition of bevacizumab to first-line standard-of-care therapy, AVAglio patients were retrospectively evaluated for molecular subtype, and bevacizumab efficacy assessed for each patient subgroup. A multivariate analysis accounting for prognostic covariates revealed that bevacizumab conferred a significant OS advantage versus placebo for patients with Proneural IDH1 wild-type tumors (17.1 v 12.8 months, respectively; hazard ratio, 0.43; 95% CI, 0.26 to 0.73; P = .002). This analysis also revealed an interaction between the Proneural subtype biomarker and treatment arm (P = .023). The group of patients with Mesenchymal and Proneural tumors derived a PFS benefit from bevacizumab, compared with placebo; however, this translated to an OS benefit in the Proneural subset only. Retrospective analysis of AVAglio data suggests that patients with IDH1 wild-type Proneural glioblastoma may derive OS benefit from first-line bevacizumab treatment. The predictive value of the Proneural subtype observed in AVAglio should be validated in an independent dataset. A total of 349 (bevacizumab arm, n = 171; placebo arm, n = 178) pretreatment specimens from AVAglio patients (total n = 921) were available for biomarker analysis. Samples were profiled for gene expression and isocitrate dehydrogenase 1 (IDH1) mutation status and classified into previously identified molecular subtypes. PFS and OS were assessed within each subtype.
Project description:The AVAglio and RTOG-0825 randomized, placebo-controlled phase III trials in newly diagnosed glioblastoma reported prolonged progression-free survival (PFS), but not overall survival (OS), with the addition of bevacizumab to radiotherapy/temozolomide. To establish whether certain patient subgroups derived OS benefit from the addition of bevacizumab to first-line standard-of-care therapy, AVAglio patients were retrospectively evaluated for molecular subtype, and bevacizumab efficacy assessed for each patient subgroup. A multivariate analysis accounting for prognostic covariates revealed that bevacizumab conferred a significant OS advantage versus placebo for patients with Proneural IDH1 wild-type tumors (17.1 v 12.8 months, respectively; hazard ratio, 0.43; 95% CI, 0.26 to 0.73; P = .002). This analysis also revealed an interaction between the Proneural subtype biomarker and treatment arm (P = .023). The group of patients with Mesenchymal and Proneural tumors derived a PFS benefit from bevacizumab, compared with placebo; however, this translated to an OS benefit in the Proneural subset only. Retrospective analysis of AVAglio data suggests that patients with IDH1 wild-type Proneural glioblastoma may derive OS benefit from first-line bevacizumab treatment. The predictive value of the Proneural subtype observed in AVAglio should be validated in an independent dataset.
Project description:IDH1 is the most commonly mutated metabolic gene across human cancers, with the highest mutational frequency observed in AML, glioma, chondrosarcoma, and intrahepatic cholangiocarcinoma. Mutations of the hot spot R132 codon alter the activity of the IDH1 enzyme, resulting in the NADPH-dependent conversion of alpha-ketoglutarate to (R)-2-hydroxyglutarate [(R)-2HG], which accumulates to mM levels within tumors. (R)-2HG competitively inhibits a range of enzymes that utilize alpha-ketoglutarate. Targets include the JmjC family histone demethylases and TET family DNA demethylases whose inhibition is linked to the altered epigenetic state characteristic of many mIDH tumors. To gain insight into the mechanisms underlying the anti-tumor efficacy of inhibition of mutant IDH1 we conducted RNA-sequencing (RNA-seq) analysis of purified tumor cells. For these studies, the immune-competent 2205 subcutaneous allograft model was treated with AG120 or vehicle for 6 days and non-tumor cells were removed by magnetic bead sorting (negative selection for CD45+ immune cells, CD31+ endothelial cells, TER119+ erythrocytes, and CD90.2+ fibroblasts).
Project description:Neomorphic mutations in isocitrate dehydrogenase 1 (IDH1) are driver mutations in acute myeloid leukemia (AML) and other cancers. We report the development of new allosteric inhibitors of mutant IDH1. Crystallographic and biochemical results demonstrated that compounds of this chemical series bind to an allosteric site and lock the enzyme in a catalytically inactive conformation, thereby enabling inhibition of different clinically relevant IDH1 mutants. Treatment of IDH1 mutant primary AML cells uniformly led to a decrease in intracellular 2-HG, abrogation of the myeloid differentiation block and induction of granulocytic differentiation at the level of leukemic blasts and more immature stem-like cells, in vitro and in vivo. Molecularly, treatment with the inhibitors led to a reversal of the DNA cytosine hypermethylation patterns caused by mutant IDH1 in AML patients’ cells. Our study provides proof-of-concept for the molecular and biological activity of novel allosteric inhibitors for targeting different mutant forms of IDH1 in leukemia. To obtain insight into the molecular mechanism for the induction of granulocytic differentiation and cell death following inhibition of IDH1 mutant protein in primary AML cells, we performed gene expression microarrays following treatment with either GSK321 IDH1 inhibitor or Controls (DMSO or GSK990 inactive inhibitor). Primary IDH1 mutant acute myeloid leukemia (AML) mononuclear (MNC) cells were treated in suspension cultures in differentiating media for 6 days with 3 microM GSK990 or GSK321 and an equal volume of DMSO. Followed by microarray analysis after RNA extraction.